text: /*
   *  SSLv3/TLSv1 shared functions
   *
   *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
   *  SPDX-License-Identifier: Apache-2.0
   *
   *  Licensed under the Apache License, Version 2.0 (the "License"); you may
   *  not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *
   *  http://www.apache.org/licenses/LICENSE-2.0
   *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *
   *  This file is part of mbed TLS (https://tls.mbed.org)
   */
  /*
   *  The SSL 3.0 specification was drafted by Netscape in 1996,
   *  and became an IETF standard in 1999.
   *
   *  http://wp.netscape.com/eng/ssl3/
   *  http://www.ietf.org/rfc/rfc2246.txt
   *  http://www.ietf.org/rfc/rfc4346.txt
   */
  
  #if !defined(MBEDTLS_CONFIG_FILE)
  #include "mbedtls/config.h"
  #else
  #include MBEDTLS_CONFIG_FILE
  #endif
  
  #if defined(MBEDTLS_SSL_TLS_C)
  
  #if defined(MBEDTLS_PLATFORM_C)
  #include "mbedtls/platform.h"
  #else
  #include <stdlib.h>
  #define mbedtls_calloc    calloc
  #define mbedtls_free      free
  #endif
  
  #include "mbedtls/debug.h"
  #include "mbedtls/ssl.h"
  #include "mbedtls/ssl_internal.h"
  
  #include <string.h>
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C) && \
      defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
  #include "mbedtls/oid.h"
  #endif
  
  /* Implementation that should never be optimized out by the compiler */
  static void mbedtls_zeroize( void *v, size_t n ) {
      volatile unsigned char *p = v; while( n-- ) *p++ = 0;
  }
  
  /* Length of the "epoch" field in the record header */
  static inline size_t ssl_ep_len( const mbedtls_ssl_context *ssl )
  {
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
          return( 2 );
  #else
      ((void) ssl);
  #endif
      return( 0 );
  }
  
  /*
   * Start a timer.
   * Passing millisecs = 0 cancels a running timer.
   */
  static void ssl_set_timer( mbedtls_ssl_context *ssl, uint32_t millisecs )
  {
      if( ssl->f_set_timer == NULL )
          return;
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "set_timer to %d ms", (int) millisecs ) );
      ssl->f_set_timer( ssl->p_timer, millisecs / 4, millisecs );
  }
  
  /*
   * Return -1 is timer is expired, 0 if it isn't.
   */
  static int ssl_check_timer( mbedtls_ssl_context *ssl )
  {
      if( ssl->f_get_timer == NULL )
          return( 0 );
  
      if( ssl->f_get_timer( ssl->p_timer ) == 2 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "timer expired" ) );
          return( -1 );
      }
  
      return( 0 );
  }
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
  /*
   * Double the retransmit timeout value, within the allowed range,
   * returning -1 if the maximum value has already been reached.
   */
  static int ssl_double_retransmit_timeout( mbedtls_ssl_context *ssl )
  {
      uint32_t new_timeout;
  
      if( ssl->handshake->retransmit_timeout >= ssl->conf->hs_timeout_max )
          return( -1 );
  
      new_timeout = 2 * ssl->handshake->retransmit_timeout;
  
      /* Avoid arithmetic overflow and range overflow */
      if( new_timeout < ssl->handshake->retransmit_timeout ||
          new_timeout > ssl->conf->hs_timeout_max )
      {
          new_timeout = ssl->conf->hs_timeout_max;
      }
  
      ssl->handshake->retransmit_timeout = new_timeout;
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %d millisecs",
                          ssl->handshake->retransmit_timeout ) );
  
      return( 0 );
  }
  
  static void ssl_reset_retransmit_timeout( mbedtls_ssl_context *ssl )
  {
      ssl->handshake->retransmit_timeout = ssl->conf->hs_timeout_min;
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %d millisecs",
                          ssl->handshake->retransmit_timeout ) );
  }
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
  
  #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
  /*
   * Convert max_fragment_length codes to length.
   * RFC 6066 says:
   *    enum{
   *        2^9(1), 2^10(2), 2^11(3), 2^12(4), (255)
   *    } MaxFragmentLength;
   * and we add 0 -> extension unused
   */
  static unsigned int mfl_code_to_length[MBEDTLS_SSL_MAX_FRAG_LEN_INVALID] =
  {
      MBEDTLS_SSL_MAX_CONTENT_LEN,    /* MBEDTLS_SSL_MAX_FRAG_LEN_NONE */
      512,                    /* MBEDTLS_SSL_MAX_FRAG_LEN_512  */
      1024,                   /* MBEDTLS_SSL_MAX_FRAG_LEN_1024 */
      2048,                   /* MBEDTLS_SSL_MAX_FRAG_LEN_2048 */
      4096,                   /* MBEDTLS_SSL_MAX_FRAG_LEN_4096 */
  };
  #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
  
  #if defined(MBEDTLS_SSL_CLI_C)
  static int ssl_session_copy( mbedtls_ssl_session *dst, const mbedtls_ssl_session *src )
  {
      mbedtls_ssl_session_free( dst );
      memcpy( dst, src, sizeof( mbedtls_ssl_session ) );
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
      if( src->peer_cert != NULL )
      {
          int ret;
  
          dst->peer_cert = mbedtls_calloc( 1, sizeof(mbedtls_x509_crt) );
          if( dst->peer_cert == NULL )
              return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
  
          mbedtls_x509_crt_init( dst->peer_cert );
  
          if( ( ret = mbedtls_x509_crt_parse_der( dst->peer_cert, src->peer_cert->raw.p,
                                          src->peer_cert->raw.len ) ) != 0 )
          {
              mbedtls_free( dst->peer_cert );
              dst->peer_cert = NULL;
              return( ret );
          }
      }
  #endif /* MBEDTLS_X509_CRT_PARSE_C */
  
  #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
      if( src->ticket != NULL )
      {
          dst->ticket = mbedtls_calloc( 1, src->ticket_len );
          if( dst->ticket == NULL )
              return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
  
          memcpy( dst->ticket, src->ticket, src->ticket_len );
      }
  #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
  
      return( 0 );
  }
  #endif /* MBEDTLS_SSL_CLI_C */
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
  int (*mbedtls_ssl_hw_record_init)( mbedtls_ssl_context *ssl,
                       const unsigned char *key_enc, const unsigned char *key_dec,
                       size_t keylen,
                       const unsigned char *iv_enc,  const unsigned char *iv_dec,
                       size_t ivlen,
                       const unsigned char *mac_enc, const unsigned char *mac_dec,
                       size_t maclen ) = NULL;
  int (*mbedtls_ssl_hw_record_activate)( mbedtls_ssl_context *ssl, int direction) = NULL;
  int (*mbedtls_ssl_hw_record_reset)( mbedtls_ssl_context *ssl ) = NULL;
  int (*mbedtls_ssl_hw_record_write)( mbedtls_ssl_context *ssl ) = NULL;
  int (*mbedtls_ssl_hw_record_read)( mbedtls_ssl_context *ssl ) = NULL;
  int (*mbedtls_ssl_hw_record_finish)( mbedtls_ssl_context *ssl ) = NULL;
  #endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
  
  /*
   * Key material generation
   */
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
  static int ssl3_prf( const unsigned char *secret, size_t slen,
                       const char *label,
                       const unsigned char *random, size_t rlen,
                       unsigned char *dstbuf, size_t dlen )
  {
      size_t i;
      mbedtls_md5_context md5;
      mbedtls_sha1_context sha1;
      unsigned char padding[16];
      unsigned char sha1sum[20];
      ((void)label);
  
      mbedtls_md5_init(  &md5  );
      mbedtls_sha1_init( &sha1 );
  
      /*
       *  SSLv3:
       *    block =
       *      MD5( secret + SHA1( 'A'    + secret + random ) ) +
       *      MD5( secret + SHA1( 'BB'   + secret + random ) ) +
       *      MD5( secret + SHA1( 'CCC'  + secret + random ) ) +
       *      ...
       */
      for( i = 0; i < dlen / 16; i++ )
      {
          memset( padding, (unsigned char) ('A' + i), 1 + i );
  
          mbedtls_sha1_starts( &sha1 );
          mbedtls_sha1_update( &sha1, padding, 1 + i );
          mbedtls_sha1_update( &sha1, secret, slen );
          mbedtls_sha1_update( &sha1, random, rlen );
          mbedtls_sha1_finish( &sha1, sha1sum );
  
          mbedtls_md5_starts( &md5 );
          mbedtls_md5_update( &md5, secret, slen );
          mbedtls_md5_update( &md5, sha1sum, 20 );
          mbedtls_md5_finish( &md5, dstbuf + i * 16 );
      }
  
      mbedtls_md5_free(  &md5  );
      mbedtls_sha1_free( &sha1 );
  
      mbedtls_zeroize( padding, sizeof( padding ) );
      mbedtls_zeroize( sha1sum, sizeof( sha1sum ) );
  
      return( 0 );
  }
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
  static int tls1_prf( const unsigned char *secret, size_t slen,
                       const char *label,
                       const unsigned char *random, size_t rlen,
                       unsigned char *dstbuf, size_t dlen )
  {
      size_t nb, hs;
      size_t i, j, k;
      const unsigned char *S1, *S2;
      unsigned char tmp[128];
      unsigned char h_i[20];
      const mbedtls_md_info_t *md_info;
      mbedtls_md_context_t md_ctx;
      int ret;
  
      mbedtls_md_init( &md_ctx );
  
      if( sizeof( tmp ) < 20 + strlen( label ) + rlen )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      hs = ( slen + 1 ) / 2;
      S1 = secret;
      S2 = secret + slen - hs;
  
      nb = strlen( label );
      memcpy( tmp + 20, label, nb );
      memcpy( tmp + 20 + nb, random, rlen );
      nb += rlen;
  
      /*
       * First compute P_md5(secret,label+random)[0..dlen]
       */
      if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_MD5 ) ) == NULL )
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
  
      if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
          return( ret );
  
      mbedtls_md_hmac_starts( &md_ctx, S1, hs );
      mbedtls_md_hmac_update( &md_ctx, tmp + 20, nb );
      mbedtls_md_hmac_finish( &md_ctx, 4 + tmp );
  
      for( i = 0; i < dlen; i += 16 )
      {
          mbedtls_md_hmac_reset ( &md_ctx );
          mbedtls_md_hmac_update( &md_ctx, 4 + tmp, 16 + nb );
          mbedtls_md_hmac_finish( &md_ctx, h_i );
  
          mbedtls_md_hmac_reset ( &md_ctx );
          mbedtls_md_hmac_update( &md_ctx, 4 + tmp, 16 );
          mbedtls_md_hmac_finish( &md_ctx, 4 + tmp );
  
          k = ( i + 16 > dlen ) ? dlen % 16 : 16;
  
          for( j = 0; j < k; j++ )
              dstbuf[i + j]  = h_i[j];
      }
  
      mbedtls_md_free( &md_ctx );
  
      /*
       * XOR out with P_sha1(secret,label+random)[0..dlen]
       */
      if( ( md_info = mbedtls_md_info_from_type( MBEDTLS_MD_SHA1 ) ) == NULL )
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
  
      if( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
          return( ret );
  
      mbedtls_md_hmac_starts( &md_ctx, S2, hs );
      mbedtls_md_hmac_update( &md_ctx, tmp + 20, nb );
      mbedtls_md_hmac_finish( &md_ctx, tmp );
  
      for( i = 0; i < dlen; i += 20 )
      {
          mbedtls_md_hmac_reset ( &md_ctx );
          mbedtls_md_hmac_update( &md_ctx, tmp, 20 + nb );
          mbedtls_md_hmac_finish( &md_ctx, h_i );
  
          mbedtls_md_hmac_reset ( &md_ctx );
          mbedtls_md_hmac_update( &md_ctx, tmp, 20 );
          mbedtls_md_hmac_finish( &md_ctx, tmp );
  
          k = ( i + 20 > dlen ) ? dlen % 20 : 20;
  
          for( j = 0; j < k; j++ )
              dstbuf[i + j] = (unsigned char)( dstbuf[i + j] ^ h_i[j] );
      }
  
      mbedtls_md_free( &md_ctx );
  
      mbedtls_zeroize( tmp, sizeof( tmp ) );
      mbedtls_zeroize( h_i, sizeof( h_i ) );
  
      return( 0 );
  }
  #endif /* MBEDTLS_SSL_PROTO_TLS1) || MBEDTLS_SSL_PROTO_TLS1_1 */
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  static int tls_prf_generic( mbedtls_md_type_t md_type,
                              const unsigned char *secret, size_t slen,
                              const char *label,
                              const unsigned char *random, size_t rlen,
                              unsigned char *dstbuf, size_t dlen )
  {
      size_t nb;
      size_t i, j, k, md_len;
      unsigned char tmp[128];
      unsigned char h_i[MBEDTLS_MD_MAX_SIZE];
      const mbedtls_md_info_t *md_info;
      mbedtls_md_context_t md_ctx;
      int ret;
  
      mbedtls_md_init( &md_ctx );
  
      if( ( md_info = mbedtls_md_info_from_type( md_type ) ) == NULL )
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
  
      md_len = mbedtls_md_get_size( md_info );
  
      if( sizeof( tmp ) < md_len + strlen( label ) + rlen )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      nb = strlen( label );
      memcpy( tmp + md_len, label, nb );
      memcpy( tmp + md_len + nb, random, rlen );
      nb += rlen;
  
      /*
       * Compute P_<hash>(secret, label + random)[0..dlen]
       */
      if ( ( ret = mbedtls_md_setup( &md_ctx, md_info, 1 ) ) != 0 )
          return( ret );
  
      mbedtls_md_hmac_starts( &md_ctx, secret, slen );
      mbedtls_md_hmac_update( &md_ctx, tmp + md_len, nb );
      mbedtls_md_hmac_finish( &md_ctx, tmp );
  
      for( i = 0; i < dlen; i += md_len )
      {
          mbedtls_md_hmac_reset ( &md_ctx );
          mbedtls_md_hmac_update( &md_ctx, tmp, md_len + nb );
          mbedtls_md_hmac_finish( &md_ctx, h_i );
  
          mbedtls_md_hmac_reset ( &md_ctx );
          mbedtls_md_hmac_update( &md_ctx, tmp, md_len );
          mbedtls_md_hmac_finish( &md_ctx, tmp );
  
          k = ( i + md_len > dlen ) ? dlen % md_len : md_len;
  
          for( j = 0; j < k; j++ )
              dstbuf[i + j]  = h_i[j];
      }
  
      mbedtls_md_free( &md_ctx );
  
      mbedtls_zeroize( tmp, sizeof( tmp ) );
      mbedtls_zeroize( h_i, sizeof( h_i ) );
  
      return( 0 );
  }
  
  #if defined(MBEDTLS_SHA256_C)
  static int tls_prf_sha256( const unsigned char *secret, size_t slen,
                             const char *label,
                             const unsigned char *random, size_t rlen,
                             unsigned char *dstbuf, size_t dlen )
  {
      return( tls_prf_generic( MBEDTLS_MD_SHA256, secret, slen,
                               label, random, rlen, dstbuf, dlen ) );
  }
  #endif /* MBEDTLS_SHA256_C */
  
  #if defined(MBEDTLS_SHA512_C)
  static int tls_prf_sha384( const unsigned char *secret, size_t slen,
                             const char *label,
                             const unsigned char *random, size_t rlen,
                             unsigned char *dstbuf, size_t dlen )
  {
      return( tls_prf_generic( MBEDTLS_MD_SHA384, secret, slen,
                               label, random, rlen, dstbuf, dlen ) );
  }
  #endif /* MBEDTLS_SHA512_C */
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  
  static void ssl_update_checksum_start( mbedtls_ssl_context *, const unsigned char *, size_t );
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_1)
  static void ssl_update_checksum_md5sha1( mbedtls_ssl_context *, const unsigned char *, size_t );
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
  static void ssl_calc_verify_ssl( mbedtls_ssl_context *, unsigned char * );
  static void ssl_calc_finished_ssl( mbedtls_ssl_context *, unsigned char *, int );
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
  static void ssl_calc_verify_tls( mbedtls_ssl_context *, unsigned char * );
  static void ssl_calc_finished_tls( mbedtls_ssl_context *, unsigned char *, int );
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
  static void ssl_update_checksum_sha256( mbedtls_ssl_context *, const unsigned char *, size_t );
  static void ssl_calc_verify_tls_sha256( mbedtls_ssl_context *,unsigned char * );
  static void ssl_calc_finished_tls_sha256( mbedtls_ssl_context *,unsigned char *, int );
  #endif
  
  #if defined(MBEDTLS_SHA512_C)
  static void ssl_update_checksum_sha384( mbedtls_ssl_context *, const unsigned char *, size_t );
  static void ssl_calc_verify_tls_sha384( mbedtls_ssl_context *, unsigned char * );
  static void ssl_calc_finished_tls_sha384( mbedtls_ssl_context *, unsigned char *, int );
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  
  int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
  {
      int ret = 0;
      unsigned char tmp[64];
      unsigned char keyblk[256];
      unsigned char *key1;
      unsigned char *key2;
      unsigned char *mac_enc;
      unsigned char *mac_dec;
      size_t iv_copy_len;
      const mbedtls_cipher_info_t *cipher_info;
      const mbedtls_md_info_t *md_info;
  
      mbedtls_ssl_session *session = ssl->session_negotiate;
      mbedtls_ssl_transform *transform = ssl->transform_negotiate;
      mbedtls_ssl_handshake_params *handshake = ssl->handshake;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> derive keys" ) );
  
      cipher_info = mbedtls_cipher_info_from_type( transform->ciphersuite_info->cipher );
      if( cipher_info == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "cipher info for %d not found",
                              transform->ciphersuite_info->cipher ) );
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      md_info = mbedtls_md_info_from_type( transform->ciphersuite_info->mac );
      if( md_info == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "mbedtls_md info for %d not found",
                              transform->ciphersuite_info->mac ) );
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      /*
       * Set appropriate PRF function and other SSL / TLS / TLS1.2 functions
       */
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
      if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
      {
          handshake->tls_prf = ssl3_prf;
          handshake->calc_verify = ssl_calc_verify_ssl;
          handshake->calc_finished = ssl_calc_finished_ssl;
      }
      else
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
      if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_3 )
      {
          handshake->tls_prf = tls1_prf;
          handshake->calc_verify = ssl_calc_verify_tls;
          handshake->calc_finished = ssl_calc_finished_tls;
      }
      else
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA512_C)
      if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
          transform->ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
      {
          handshake->tls_prf = tls_prf_sha384;
          handshake->calc_verify = ssl_calc_verify_tls_sha384;
          handshake->calc_finished = ssl_calc_finished_tls_sha384;
      }
      else
  #endif
  #if defined(MBEDTLS_SHA256_C)
      if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
      {
          handshake->tls_prf = tls_prf_sha256;
          handshake->calc_verify = ssl_calc_verify_tls_sha256;
          handshake->calc_finished = ssl_calc_finished_tls_sha256;
      }
      else
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      /*
       * SSLv3:
       *   master =
       *     MD5( premaster + SHA1( 'A'   + premaster + randbytes ) ) +
       *     MD5( premaster + SHA1( 'BB'  + premaster + randbytes ) ) +
       *     MD5( premaster + SHA1( 'CCC' + premaster + randbytes ) )
       *
       * TLSv1+:
       *   master = PRF( premaster, "master secret", randbytes )[0..47]
       */
      if( handshake->resume == 0 )
      {
          MBEDTLS_SSL_DEBUG_BUF( 3, "premaster secret", handshake->premaster,
                         handshake->pmslen );
  
  #if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
          if( ssl->handshake->extended_ms == MBEDTLS_SSL_EXTENDED_MS_ENABLED )
          {
              unsigned char session_hash[48];
              size_t hash_len;
  
              MBEDTLS_SSL_DEBUG_MSG( 3, ( "using extended master secret" ) );
  
              ssl->handshake->calc_verify( ssl, session_hash );
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
              if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
              {
  #if defined(MBEDTLS_SHA512_C)
                  if( ssl->transform_negotiate->ciphersuite_info->mac ==
                      MBEDTLS_MD_SHA384 )
                  {
                      hash_len = 48;
                  }
                  else
  #endif
                      hash_len = 32;
              }
              else
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
                  hash_len = 36;
  
              MBEDTLS_SSL_DEBUG_BUF( 3, "session hash", session_hash, hash_len );
  
              ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
                                        "extended master secret",
                                        session_hash, hash_len,
                                        session->master, 48 );
              if( ret != 0 )
              {
                  MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
                  return( ret );
              }
  
          }
          else
  #endif
          ret = handshake->tls_prf( handshake->premaster, handshake->pmslen,
                                    "master secret",
                                    handshake->randbytes, 64,
                                    session->master, 48 );
          if( ret != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
              return( ret );
          }
  
          mbedtls_zeroize( handshake->premaster, sizeof(handshake->premaster) );
      }
      else
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "no premaster (session resumed)" ) );
  
      /*
       * Swap the client and server random values.
       */
      memcpy( tmp, handshake->randbytes, 64 );
      memcpy( handshake->randbytes, tmp + 32, 32 );
      memcpy( handshake->randbytes + 32, tmp, 32 );
      mbedtls_zeroize( tmp, sizeof( tmp ) );
  
      /*
       *  SSLv3:
       *    key block =
       *      MD5( master + SHA1( 'A'    + master + randbytes ) ) +
       *      MD5( master + SHA1( 'BB'   + master + randbytes ) ) +
       *      MD5( master + SHA1( 'CCC'  + master + randbytes ) ) +
       *      MD5( master + SHA1( 'DDDD' + master + randbytes ) ) +
       *      ...
       *
       *  TLSv1:
       *    key block = PRF( master, "key expansion", randbytes )
       */
      ret = handshake->tls_prf( session->master, 48, "key expansion",
                                handshake->randbytes, 64, keyblk, 256 );
      if( ret != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "prf", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "ciphersuite = %s",
                     mbedtls_ssl_get_ciphersuite_name( session->ciphersuite ) ) );
      MBEDTLS_SSL_DEBUG_BUF( 3, "master secret", session->master, 48 );
      MBEDTLS_SSL_DEBUG_BUF( 4, "random bytes", handshake->randbytes, 64 );
      MBEDTLS_SSL_DEBUG_BUF( 4, "key block", keyblk, 256 );
  
      mbedtls_zeroize( handshake->randbytes, sizeof( handshake->randbytes ) );
  
      /*
       * Determine the appropriate key, IV and MAC length.
       */
  
      transform->keylen = cipher_info->key_bitlen / 8;
  
      if( cipher_info->mode == MBEDTLS_MODE_GCM ||
          cipher_info->mode == MBEDTLS_MODE_CCM )
      {
          transform->maclen = 0;
  
          transform->ivlen = 12;
          transform->fixed_ivlen = 4;
  
          /* Minimum length is expicit IV + tag */
          transform->minlen = transform->ivlen - transform->fixed_ivlen
                              + ( transform->ciphersuite_info->flags &
                                  MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16 );
      }
      else
      {
          /* Initialize HMAC contexts */
          if( ( ret = mbedtls_md_setup( &transform->md_ctx_enc, md_info, 1 ) ) != 0 ||
              ( ret = mbedtls_md_setup( &transform->md_ctx_dec, md_info, 1 ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_setup", ret );
              return( ret );
          }
  
          /* Get MAC length */
          transform->maclen = mbedtls_md_get_size( md_info );
  
  #if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
          /*
           * If HMAC is to be truncated, we shall keep the leftmost bytes,
           * (rfc 6066 page 13 or rfc 2104 section 4),
           * so we only need to adjust the length here.
           */
          if( session->trunc_hmac == MBEDTLS_SSL_TRUNC_HMAC_ENABLED )
              transform->maclen = MBEDTLS_SSL_TRUNCATED_HMAC_LEN;
  #endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
  
          /* IV length */
          transform->ivlen = cipher_info->iv_size;
  
          /* Minimum length */
          if( cipher_info->mode == MBEDTLS_MODE_STREAM )
              transform->minlen = transform->maclen;
          else
          {
              /*
               * GenericBlockCipher:
               * 1. if EtM is in use: one block plus MAC
               *    otherwise: * first multiple of blocklen greater than maclen
               * 2. IV except for SSL3 and TLS 1.0
               */
  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
              if( session->encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED )
              {
                  transform->minlen = transform->maclen
                                    + cipher_info->block_size;
              }
              else
  #endif
              {
                  transform->minlen = transform->maclen
                                    + cipher_info->block_size
                                    - transform->maclen % cipher_info->block_size;
              }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1)
              if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 ||
                  ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_1 )
                  ; /* No need to adjust minlen */
              else
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
              if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_2 ||
                  ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
              {
                  transform->minlen += transform->ivlen;
              }
              else
  #endif
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
                  return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
              }
          }
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "keylen: %d, minlen: %d, ivlen: %d, maclen: %d",
                     transform->keylen, transform->minlen, transform->ivlen,
                     transform->maclen ) );
  
      /*
       * Finally setup the cipher contexts, IVs and MAC secrets.
       */
  #if defined(MBEDTLS_SSL_CLI_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
      {
          key1 = keyblk + transform->maclen * 2;
          key2 = keyblk + transform->maclen * 2 + transform->keylen;
  
          mac_enc = keyblk;
          mac_dec = keyblk + transform->maclen;
  
          /*
           * This is not used in TLS v1.1.
           */
          iv_copy_len = ( transform->fixed_ivlen ) ?
                              transform->fixed_ivlen : transform->ivlen;
          memcpy( transform->iv_enc, key2 + transform->keylen,  iv_copy_len );
          memcpy( transform->iv_dec, key2 + transform->keylen + iv_copy_len,
                  iv_copy_len );
      }
      else
  #endif /* MBEDTLS_SSL_CLI_C */
  #if defined(MBEDTLS_SSL_SRV_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
      {
          key1 = keyblk + transform->maclen * 2 + transform->keylen;
          key2 = keyblk + transform->maclen * 2;
  
          mac_enc = keyblk + transform->maclen;
          mac_dec = keyblk;
  
          /*
           * This is not used in TLS v1.1.
           */
          iv_copy_len = ( transform->fixed_ivlen ) ?
                              transform->fixed_ivlen : transform->ivlen;
          memcpy( transform->iv_dec, key1 + transform->keylen,  iv_copy_len );
          memcpy( transform->iv_enc, key1 + transform->keylen + iv_copy_len,
                  iv_copy_len );
      }
      else
  #endif /* MBEDTLS_SSL_SRV_C */
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
      if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
      {
          if( transform->maclen > sizeof transform->mac_enc )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          memcpy( transform->mac_enc, mac_enc, transform->maclen );
          memcpy( transform->mac_dec, mac_dec, transform->maclen );
      }
      else
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_2)
      if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
      {
          mbedtls_md_hmac_starts( &transform->md_ctx_enc, mac_enc, transform->maclen );
          mbedtls_md_hmac_starts( &transform->md_ctx_dec, mac_dec, transform->maclen );
      }
      else
  #endif
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_init != NULL )
      {
          int ret = 0;
  
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_init()" ) );
  
          if( ( ret = mbedtls_ssl_hw_record_init( ssl, key1, key2, transform->keylen,
                                          transform->iv_enc, transform->iv_dec,
                                          iv_copy_len,
                                          mac_enc, mac_dec,
                                          transform->maclen ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_init", ret );
              return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
          }
      }
  #endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
  
  #if defined(MBEDTLS_SSL_EXPORT_KEYS)
      if( ssl->conf->f_export_keys != NULL )
      {
          ssl->conf->f_export_keys( ssl->conf->p_export_keys,
                                    session->master, keyblk,
                                    transform->maclen, transform->keylen,
                                    iv_copy_len );
      }
  #endif
  
      if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_enc,
                                   cipher_info ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
          return( ret );
      }
  
      if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_dec,
                                   cipher_info ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
          return( ret );
      }
  
      if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_enc, key1,
                                 cipher_info->key_bitlen,
                                 MBEDTLS_ENCRYPT ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
          return( ret );
      }
  
      if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_dec, key2,
                                 cipher_info->key_bitlen,
                                 MBEDTLS_DECRYPT ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
          return( ret );
      }
  
  #if defined(MBEDTLS_CIPHER_MODE_CBC)
      if( cipher_info->mode == MBEDTLS_MODE_CBC )
      {
          if( ( ret = mbedtls_cipher_set_padding_mode( &transform->cipher_ctx_enc,
                                               MBEDTLS_PADDING_NONE ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_set_padding_mode", ret );
              return( ret );
          }
  
          if( ( ret = mbedtls_cipher_set_padding_mode( &transform->cipher_ctx_dec,
                                               MBEDTLS_PADDING_NONE ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_set_padding_mode", ret );
              return( ret );
          }
      }
  #endif /* MBEDTLS_CIPHER_MODE_CBC */
  
      mbedtls_zeroize( keyblk, sizeof( keyblk ) );
  
  #if defined(MBEDTLS_ZLIB_SUPPORT)
      // Initialize compression
      //
      if( session->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
      {
          if( ssl->compress_buf == NULL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 3, ( "Allocating compression buffer" ) );
              ssl->compress_buf = mbedtls_calloc( 1, MBEDTLS_SSL_BUFFER_LEN );
              if( ssl->compress_buf == NULL )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
                                      MBEDTLS_SSL_BUFFER_LEN ) );
                  return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
              }
          }
  
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "Initializing zlib states" ) );
  
          memset( &transform->ctx_deflate, 0, sizeof( transform->ctx_deflate ) );
          memset( &transform->ctx_inflate, 0, sizeof( transform->ctx_inflate ) );
  
          if( deflateInit( &transform->ctx_deflate,
                           Z_DEFAULT_COMPRESSION )   != Z_OK ||
              inflateInit( &transform->ctx_inflate ) != Z_OK )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "Failed to initialize compression" ) );
              return( MBEDTLS_ERR_SSL_COMPRESSION_FAILED );
          }
      }
  #endif /* MBEDTLS_ZLIB_SUPPORT */
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= derive keys" ) );
  
      return( 0 );
  }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
  void ssl_calc_verify_ssl( mbedtls_ssl_context *ssl, unsigned char hash[36] )
  {
      mbedtls_md5_context md5;
      mbedtls_sha1_context sha1;
      unsigned char pad_1[48];
      unsigned char pad_2[48];
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify ssl" ) );
  
      mbedtls_md5_init( &md5 );
      mbedtls_sha1_init( &sha1 );
  
      mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
      mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
  
      memset( pad_1, 0x36, 48 );
      memset( pad_2, 0x5C, 48 );
  
      mbedtls_md5_update( &md5, ssl->session_negotiate->master, 48 );
      mbedtls_md5_update( &md5, pad_1, 48 );
      mbedtls_md5_finish( &md5, hash );
  
      mbedtls_md5_starts( &md5 );
      mbedtls_md5_update( &md5, ssl->session_negotiate->master, 48 );
      mbedtls_md5_update( &md5, pad_2, 48 );
      mbedtls_md5_update( &md5, hash,  16 );
      mbedtls_md5_finish( &md5, hash );
  
      mbedtls_sha1_update( &sha1, ssl->session_negotiate->master, 48 );
      mbedtls_sha1_update( &sha1, pad_1, 40 );
      mbedtls_sha1_finish( &sha1, hash + 16 );
  
      mbedtls_sha1_starts( &sha1 );
      mbedtls_sha1_update( &sha1, ssl->session_negotiate->master, 48 );
      mbedtls_sha1_update( &sha1, pad_2, 40 );
      mbedtls_sha1_update( &sha1, hash + 16, 20 );
      mbedtls_sha1_finish( &sha1, hash + 16 );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 36 );
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
  
      mbedtls_md5_free(  &md5  );
      mbedtls_sha1_free( &sha1 );
  
      return;
  }
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
  void ssl_calc_verify_tls( mbedtls_ssl_context *ssl, unsigned char hash[36] )
  {
      mbedtls_md5_context md5;
      mbedtls_sha1_context sha1;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify tls" ) );
  
      mbedtls_md5_init( &md5 );
      mbedtls_sha1_init( &sha1 );
  
      mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
      mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
  
       mbedtls_md5_finish( &md5,  hash );
      mbedtls_sha1_finish( &sha1, hash + 16 );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 36 );
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
  
      mbedtls_md5_free(  &md5  );
      mbedtls_sha1_free( &sha1 );
  
      return;
  }
  #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 */
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
  void ssl_calc_verify_tls_sha256( mbedtls_ssl_context *ssl, unsigned char hash[32] )
  {
      mbedtls_sha256_context sha256;
  
      mbedtls_sha256_init( &sha256 );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify sha256" ) );
  
      mbedtls_sha256_clone( &sha256, &ssl->handshake->fin_sha256 );
      mbedtls_sha256_finish( &sha256, hash );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 32 );
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
  
      mbedtls_sha256_free( &sha256 );
  
      return;
  }
  #endif /* MBEDTLS_SHA256_C */
  
  #if defined(MBEDTLS_SHA512_C)
  void ssl_calc_verify_tls_sha384( mbedtls_ssl_context *ssl, unsigned char hash[48] )
  {
      mbedtls_sha512_context sha512;
  
      mbedtls_sha512_init( &sha512 );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc verify sha384" ) );
  
      mbedtls_sha512_clone( &sha512, &ssl->handshake->fin_sha512 );
      mbedtls_sha512_finish( &sha512, hash );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calculated verify result", hash, 48 );
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc verify" ) );
  
      mbedtls_sha512_free( &sha512 );
  
      return;
  }
  #endif /* MBEDTLS_SHA512_C */
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  
  #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
  int mbedtls_ssl_psk_derive_premaster( mbedtls_ssl_context *ssl, mbedtls_key_exchange_type_t key_ex )
  {
      unsigned char *p = ssl->handshake->premaster;
      unsigned char *end = p + sizeof( ssl->handshake->premaster );
      const unsigned char *psk = ssl->conf->psk;
      size_t psk_len = ssl->conf->psk_len;
  
      /* If the psk callback was called, use its result */
      if( ssl->handshake->psk != NULL )
      {
          psk = ssl->handshake->psk;
          psk_len = ssl->handshake->psk_len;
      }
  
      /*
       * PMS = struct {
       *     opaque other_secret<0..2^16-1>;
       *     opaque psk<0..2^16-1>;
       * };
       * with "other_secret" depending on the particular key exchange
       */
  #if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
      if( key_ex == MBEDTLS_KEY_EXCHANGE_PSK )
      {
          if( end - p < 2 )
              return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
          *(p++) = (unsigned char)( psk_len >> 8 );
          *(p++) = (unsigned char)( psk_len      );
  
          if( end < p || (size_t)( end - p ) < psk_len )
              return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
          memset( p, 0, psk_len );
          p += psk_len;
      }
      else
  #endif /* MBEDTLS_KEY_EXCHANGE_PSK_ENABLED */
  #if defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)
      if( key_ex == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
      {
          /*
           * other_secret already set by the ClientKeyExchange message,
           * and is 48 bytes long
           */
          *p++ = 0;
          *p++ = 48;
          p += 48;
      }
      else
  #endif /* MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED */
  #if defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED)
      if( key_ex == MBEDTLS_KEY_EXCHANGE_DHE_PSK )
      {
          int ret;
          size_t len;
  
          /* Write length only when we know the actual value */
          if( ( ret = mbedtls_dhm_calc_secret( &ssl->handshake->dhm_ctx,
                                        p + 2, end - ( p + 2 ), &len,
                                        ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_calc_secret", ret );
              return( ret );
          }
          *(p++) = (unsigned char)( len >> 8 );
          *(p++) = (unsigned char)( len );
          p += len;
  
          MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K  );
      }
      else
  #endif /* MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED */
  #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
      if( key_ex == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK )
      {
          int ret;
          size_t zlen;
  
          if( ( ret = mbedtls_ecdh_calc_secret( &ssl->handshake->ecdh_ctx, &zlen,
                                         p + 2, end - ( p + 2 ),
                                         ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ecdh_calc_secret", ret );
              return( ret );
          }
  
          *(p++) = (unsigned char)( zlen >> 8 );
          *(p++) = (unsigned char)( zlen      );
          p += zlen;
  
          MBEDTLS_SSL_DEBUG_MPI( 3, "ECDH: z", &ssl->handshake->ecdh_ctx.z );
      }
      else
  #endif /* MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED */
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      /* opaque psk<0..2^16-1>; */
      if( end - p < 2 )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      *(p++) = (unsigned char)( psk_len >> 8 );
      *(p++) = (unsigned char)( psk_len      );
  
      if( end < p || (size_t)( end - p ) < psk_len )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      memcpy( p, psk, psk_len );
      p += psk_len;
  
      ssl->handshake->pmslen = p - ssl->handshake->premaster;
  
      return( 0 );
  }
  #endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
  /*
   * SSLv3.0 MAC functions
   */
  static void ssl_mac( mbedtls_md_context_t *md_ctx, unsigned char *secret,
                       unsigned char *buf, size_t len,
                       unsigned char *ctr, int type )
  {
      unsigned char header[11];
      unsigned char padding[48];
      int padlen;
      int md_size = mbedtls_md_get_size( md_ctx->md_info );
      int md_type = mbedtls_md_get_type( md_ctx->md_info );
  
      /* Only MD5 and SHA-1 supported */
      if( md_type == MBEDTLS_MD_MD5 )
          padlen = 48;
      else
          padlen = 40;
  
      memcpy( header, ctr, 8 );
      header[ 8] = (unsigned char)  type;
      header[ 9] = (unsigned char)( len >> 8 );
      header[10] = (unsigned char)( len      );
  
      memset( padding, 0x36, padlen );
      mbedtls_md_starts( md_ctx );
      mbedtls_md_update( md_ctx, secret,  md_size );
      mbedtls_md_update( md_ctx, padding, padlen  );
      mbedtls_md_update( md_ctx, header,  11      );
      mbedtls_md_update( md_ctx, buf,     len     );
      mbedtls_md_finish( md_ctx, buf +    len     );
  
      memset( padding, 0x5C, padlen );
      mbedtls_md_starts( md_ctx );
      mbedtls_md_update( md_ctx, secret,    md_size );
      mbedtls_md_update( md_ctx, padding,   padlen  );
      mbedtls_md_update( md_ctx, buf + len, md_size );
      mbedtls_md_finish( md_ctx, buf + len          );
  }
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  
  #if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER) ||     \
      ( defined(MBEDTLS_CIPHER_MODE_CBC) &&                                  \
        ( defined(MBEDTLS_AES_C) || defined(MBEDTLS_CAMELLIA_C) ) )
  #define SSL_SOME_MODES_USE_MAC
  #endif
  
  /*
   * Encryption/decryption functions
   */
  static int ssl_encrypt_buf( mbedtls_ssl_context *ssl )
  {
      mbedtls_cipher_mode_t mode;
      int auth_done = 0;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> encrypt buf" ) );
  
      if( ssl->session_out == NULL || ssl->transform_out == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      mode = mbedtls_cipher_get_cipher_mode( &ssl->transform_out->cipher_ctx_enc );
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "before encrypt: output payload",
                        ssl->out_msg, ssl->out_msglen );
  
      /*
       * Add MAC before if needed
       */
  #if defined(SSL_SOME_MODES_USE_MAC)
      if( mode == MBEDTLS_MODE_STREAM ||
          ( mode == MBEDTLS_MODE_CBC
  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
            && ssl->session_out->encrypt_then_mac == MBEDTLS_SSL_ETM_DISABLED
  #endif
          ) )
      {
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
          if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
          {
              ssl_mac( &ssl->transform_out->md_ctx_enc,
                        ssl->transform_out->mac_enc,
                        ssl->out_msg, ssl->out_msglen,
                        ssl->out_ctr, ssl->out_msgtype );
          }
          else
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
          defined(MBEDTLS_SSL_PROTO_TLS1_2)
          if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
          {
              mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_ctr, 8 );
              mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_hdr, 3 );
              mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, ssl->out_len, 2 );
              mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc,
                               ssl->out_msg, ssl->out_msglen );
              mbedtls_md_hmac_finish( &ssl->transform_out->md_ctx_enc,
                               ssl->out_msg + ssl->out_msglen );
              mbedtls_md_hmac_reset( &ssl->transform_out->md_ctx_enc );
          }
          else
  #endif
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac",
                         ssl->out_msg + ssl->out_msglen,
                         ssl->transform_out->maclen );
  
          ssl->out_msglen += ssl->transform_out->maclen;
          auth_done++;
      }
  #endif /* AEAD not the only option */
  
      /*
       * Encrypt
       */
  #if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
      if( mode == MBEDTLS_MODE_STREAM )
      {
          int ret;
          size_t olen = 0;
  
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %d, "
                              "including %d bytes of padding",
                         ssl->out_msglen, 0 ) );
  
          if( ( ret = mbedtls_cipher_crypt( &ssl->transform_out->cipher_ctx_enc,
                                     ssl->transform_out->iv_enc,
                                     ssl->transform_out->ivlen,
                                     ssl->out_msg, ssl->out_msglen,
                                     ssl->out_msg, &olen ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
              return( ret );
          }
  
          if( ssl->out_msglen != olen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
      }
      else
  #endif /* MBEDTLS_ARC4_C || MBEDTLS_CIPHER_NULL_CIPHER */
  #if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CCM_C)
      if( mode == MBEDTLS_MODE_GCM ||
          mode == MBEDTLS_MODE_CCM )
      {
          int ret;
          size_t enc_msglen, olen;
          unsigned char *enc_msg;
          unsigned char add_data[13];
          unsigned char taglen = ssl->transform_out->ciphersuite_info->flags &
                                 MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16;
  
          memcpy( add_data, ssl->out_ctr, 8 );
          add_data[8]  = ssl->out_msgtype;
          mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
                             ssl->conf->transport, add_data + 9 );
          add_data[11] = ( ssl->out_msglen >> 8 ) & 0xFF;
          add_data[12] = ssl->out_msglen & 0xFF;
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "additional data used for AEAD",
                         add_data, 13 );
  
          /*
           * Generate IV
           */
  #if defined(MBEDTLS_SSL_AEAD_RANDOM_IV)
          ret = ssl->conf->f_rng( ssl->conf->p_rng,
                  ssl->transform_out->iv_enc + ssl->transform_out->fixed_ivlen,
                  ssl->transform_out->ivlen - ssl->transform_out->fixed_ivlen );
          if( ret != 0 )
              return( ret );
  
          memcpy( ssl->out_iv,
                  ssl->transform_out->iv_enc + ssl->transform_out->fixed_ivlen,
                  ssl->transform_out->ivlen - ssl->transform_out->fixed_ivlen );
  #else
          if( ssl->transform_out->ivlen - ssl->transform_out->fixed_ivlen != 8 )
          {
              /* Reminder if we ever add an AEAD mode with a different size */
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          memcpy( ssl->transform_out->iv_enc + ssl->transform_out->fixed_ivlen,
                               ssl->out_ctr, 8 );
          memcpy( ssl->out_iv, ssl->out_ctr, 8 );
  #endif
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "IV used", ssl->out_iv,
                  ssl->transform_out->ivlen - ssl->transform_out->fixed_ivlen );
  
          /*
           * Fix pointer positions and message length with added IV
           */
          enc_msg = ssl->out_msg;
          enc_msglen = ssl->out_msglen;
          ssl->out_msglen += ssl->transform_out->ivlen -
                             ssl->transform_out->fixed_ivlen;
  
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %d, "
                              "including %d bytes of padding",
                         ssl->out_msglen, 0 ) );
  
          /*
           * Encrypt and authenticate
           */
          if( ( ret = mbedtls_cipher_auth_encrypt( &ssl->transform_out->cipher_ctx_enc,
                                           ssl->transform_out->iv_enc,
                                           ssl->transform_out->ivlen,
                                           add_data, 13,
                                           enc_msg, enc_msglen,
                                           enc_msg, &olen,
                                           enc_msg + enc_msglen, taglen ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_encrypt", ret );
              return( ret );
          }
  
          if( olen != enc_msglen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          ssl->out_msglen += taglen;
          auth_done++;
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "after encrypt: tag", enc_msg + enc_msglen, taglen );
      }
      else
  #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
  #if defined(MBEDTLS_CIPHER_MODE_CBC) &&                                    \
      ( defined(MBEDTLS_AES_C) || defined(MBEDTLS_CAMELLIA_C) )
      if( mode == MBEDTLS_MODE_CBC )
      {
          int ret;
          unsigned char *enc_msg;
          size_t enc_msglen, padlen, olen = 0, i;
  
          padlen = ssl->transform_out->ivlen - ( ssl->out_msglen + 1 ) %
                   ssl->transform_out->ivlen;
          if( padlen == ssl->transform_out->ivlen )
              padlen = 0;
  
          for( i = 0; i <= padlen; i++ )
              ssl->out_msg[ssl->out_msglen + i] = (unsigned char) padlen;
  
          ssl->out_msglen += padlen + 1;
  
          enc_msglen = ssl->out_msglen;
          enc_msg = ssl->out_msg;
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
          /*
           * Prepend per-record IV for block cipher in TLS v1.1 and up as per
           * Method 1 (6.2.3.2. in RFC4346 and RFC5246)
           */
          if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
          {
              /*
               * Generate IV
               */
              ret = ssl->conf->f_rng( ssl->conf->p_rng, ssl->transform_out->iv_enc,
                                    ssl->transform_out->ivlen );
              if( ret != 0 )
                  return( ret );
  
              memcpy( ssl->out_iv, ssl->transform_out->iv_enc,
                      ssl->transform_out->ivlen );
  
              /*
               * Fix pointer positions and message length with added IV
               */
              enc_msg = ssl->out_msg;
              enc_msglen = ssl->out_msglen;
              ssl->out_msglen += ssl->transform_out->ivlen;
          }
  #endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
  
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %d, "
                              "including %d bytes of IV and %d bytes of padding",
                              ssl->out_msglen, ssl->transform_out->ivlen,
                              padlen + 1 ) );
  
          if( ( ret = mbedtls_cipher_crypt( &ssl->transform_out->cipher_ctx_enc,
                                     ssl->transform_out->iv_enc,
                                     ssl->transform_out->ivlen,
                                     enc_msg, enc_msglen,
                                     enc_msg, &olen ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
              return( ret );
          }
  
          if( enc_msglen != olen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1)
          if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 )
          {
              /*
               * Save IV in SSL3 and TLS1
               */
              memcpy( ssl->transform_out->iv_enc,
                      ssl->transform_out->cipher_ctx_enc.iv,
                      ssl->transform_out->ivlen );
          }
  #endif
  
  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
          if( auth_done == 0 )
          {
              /*
               * MAC(MAC_write_key, seq_num +
               *     TLSCipherText.type +
               *     TLSCipherText.version +
               *     length_of( (IV +) ENC(...) ) +
               *     IV + // except for TLS 1.0
               *     ENC(content + padding + padding_length));
               */
              unsigned char pseudo_hdr[13];
  
              MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
  
              memcpy( pseudo_hdr +  0, ssl->out_ctr, 8 );
              memcpy( pseudo_hdr +  8, ssl->out_hdr, 3 );
              pseudo_hdr[11] = (unsigned char)( ( ssl->out_msglen >> 8 ) & 0xFF );
              pseudo_hdr[12] = (unsigned char)( ( ssl->out_msglen      ) & 0xFF );
  
              MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", pseudo_hdr, 13 );
  
              mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc, pseudo_hdr, 13 );
              mbedtls_md_hmac_update( &ssl->transform_out->md_ctx_enc,
                               ssl->out_iv, ssl->out_msglen );
              mbedtls_md_hmac_finish( &ssl->transform_out->md_ctx_enc,
                               ssl->out_iv + ssl->out_msglen );
              mbedtls_md_hmac_reset( &ssl->transform_out->md_ctx_enc );
  
              ssl->out_msglen += ssl->transform_out->maclen;
              auth_done++;
          }
  #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
      }
      else
  #endif /* MBEDTLS_CIPHER_MODE_CBC &&
            ( MBEDTLS_AES_C || MBEDTLS_CAMELLIA_C ) */
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      /* Make extra sure authentication was performed, exactly once */
      if( auth_done != 1 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= encrypt buf" ) );
  
      return( 0 );
  }
  
  #define SSL_MAX_MAC_SIZE   48
  
  static int ssl_decrypt_buf( mbedtls_ssl_context *ssl )
  {
      size_t i;
      mbedtls_cipher_mode_t mode;
      int auth_done = 0;
  #if defined(SSL_SOME_MODES_USE_MAC)
      size_t padlen = 0, correct = 1;
  #endif
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> decrypt buf" ) );
  
      if( ssl->session_in == NULL || ssl->transform_in == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      mode = mbedtls_cipher_get_cipher_mode( &ssl->transform_in->cipher_ctx_dec );
  
      if( ssl->in_msglen < ssl->transform_in->minlen )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "in_msglen (%d) < minlen (%d)",
                         ssl->in_msglen, ssl->transform_in->minlen ) );
          return( MBEDTLS_ERR_SSL_INVALID_MAC );
      }
  
  #if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
      if( mode == MBEDTLS_MODE_STREAM )
      {
          int ret;
          size_t olen = 0;
  
          padlen = 0;
  
          if( ( ret = mbedtls_cipher_crypt( &ssl->transform_in->cipher_ctx_dec,
                                     ssl->transform_in->iv_dec,
                                     ssl->transform_in->ivlen,
                                     ssl->in_msg, ssl->in_msglen,
                                     ssl->in_msg, &olen ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
              return( ret );
          }
  
          if( ssl->in_msglen != olen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
      }
      else
  #endif /* MBEDTLS_ARC4_C || MBEDTLS_CIPHER_NULL_CIPHER */
  #if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CCM_C)
      if( mode == MBEDTLS_MODE_GCM ||
          mode == MBEDTLS_MODE_CCM )
      {
          int ret;
          size_t dec_msglen, olen;
          unsigned char *dec_msg;
          unsigned char *dec_msg_result;
          unsigned char add_data[13];
          unsigned char taglen = ssl->transform_in->ciphersuite_info->flags &
                                 MBEDTLS_CIPHERSUITE_SHORT_TAG ? 8 : 16;
          size_t explicit_iv_len = ssl->transform_in->ivlen -
                                   ssl->transform_in->fixed_ivlen;
  
          if( ssl->in_msglen < explicit_iv_len + taglen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) < explicit_iv_len (%d) "
                                  "+ taglen (%d)", ssl->in_msglen,
                                  explicit_iv_len, taglen ) );
              return( MBEDTLS_ERR_SSL_INVALID_MAC );
          }
          dec_msglen = ssl->in_msglen - explicit_iv_len - taglen;
  
          dec_msg = ssl->in_msg;
          dec_msg_result = ssl->in_msg;
          ssl->in_msglen = dec_msglen;
  
          memcpy( add_data, ssl->in_ctr, 8 );
          add_data[8]  = ssl->in_msgtype;
          mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
                             ssl->conf->transport, add_data + 9 );
          add_data[11] = ( ssl->in_msglen >> 8 ) & 0xFF;
          add_data[12] = ssl->in_msglen & 0xFF;
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "additional data used for AEAD",
                         add_data, 13 );
  
          memcpy( ssl->transform_in->iv_dec + ssl->transform_in->fixed_ivlen,
                  ssl->in_iv,
                  ssl->transform_in->ivlen - ssl->transform_in->fixed_ivlen );
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "IV used", ssl->transform_in->iv_dec,
                                       ssl->transform_in->ivlen );
          MBEDTLS_SSL_DEBUG_BUF( 4, "TAG used", dec_msg + dec_msglen, taglen );
  
          /*
           * Decrypt and authenticate
           */
          if( ( ret = mbedtls_cipher_auth_decrypt( &ssl->transform_in->cipher_ctx_dec,
                                           ssl->transform_in->iv_dec,
                                           ssl->transform_in->ivlen,
                                           add_data, 13,
                                           dec_msg, dec_msglen,
                                           dec_msg_result, &olen,
                                           dec_msg + dec_msglen, taglen ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_decrypt", ret );
  
              if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED )
                  return( MBEDTLS_ERR_SSL_INVALID_MAC );
  
              return( ret );
          }
          auth_done++;
  
          if( olen != dec_msglen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
      }
      else
  #endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
  #if defined(MBEDTLS_CIPHER_MODE_CBC) &&                                    \
      ( defined(MBEDTLS_AES_C) || defined(MBEDTLS_CAMELLIA_C) )
      if( mode == MBEDTLS_MODE_CBC )
      {
          /*
           * Decrypt and check the padding
           */
          int ret;
          unsigned char *dec_msg;
          unsigned char *dec_msg_result;
          size_t dec_msglen;
          size_t minlen = 0;
          size_t olen = 0;
  
          /*
           * Check immediate ciphertext sanity
           */
  #if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
          if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
              minlen += ssl->transform_in->ivlen;
  #endif
  
          if( ssl->in_msglen < minlen + ssl->transform_in->ivlen ||
              ssl->in_msglen < minlen + ssl->transform_in->maclen + 1 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) < max( ivlen(%d), maclen (%d) "
                                  "+ 1 ) ( + expl IV )", ssl->in_msglen,
                                  ssl->transform_in->ivlen,
                                  ssl->transform_in->maclen ) );
              return( MBEDTLS_ERR_SSL_INVALID_MAC );
          }
  
          dec_msglen = ssl->in_msglen;
          dec_msg = ssl->in_msg;
          dec_msg_result = ssl->in_msg;
  
          /*
           * Authenticate before decrypt if enabled
           */
  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
          if( ssl->session_in->encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED )
          {
              unsigned char computed_mac[SSL_MAX_MAC_SIZE];
              unsigned char pseudo_hdr[13];
  
              MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
  
              dec_msglen -= ssl->transform_in->maclen;
              ssl->in_msglen -= ssl->transform_in->maclen;
  
              memcpy( pseudo_hdr +  0, ssl->in_ctr, 8 );
              memcpy( pseudo_hdr +  8, ssl->in_hdr, 3 );
              pseudo_hdr[11] = (unsigned char)( ( ssl->in_msglen >> 8 ) & 0xFF );
              pseudo_hdr[12] = (unsigned char)( ( ssl->in_msglen      ) & 0xFF );
  
              MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", pseudo_hdr, 13 );
  
              mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, pseudo_hdr, 13 );
              mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec,
                               ssl->in_iv, ssl->in_msglen );
              mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec, computed_mac );
              mbedtls_md_hmac_reset( &ssl->transform_in->md_ctx_dec );
  
              MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", ssl->in_iv + ssl->in_msglen,
                                                ssl->transform_in->maclen );
              MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac", computed_mac,
                                                ssl->transform_in->maclen );
  
              if( mbedtls_ssl_safer_memcmp( ssl->in_iv + ssl->in_msglen, computed_mac,
                                ssl->transform_in->maclen ) != 0 )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
  
                  return( MBEDTLS_ERR_SSL_INVALID_MAC );
              }
              auth_done++;
          }
  #endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
  
          /*
           * Check length sanity
           */
          if( ssl->in_msglen % ssl->transform_in->ivlen != 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) %% ivlen (%d) != 0",
                             ssl->in_msglen, ssl->transform_in->ivlen ) );
              return( MBEDTLS_ERR_SSL_INVALID_MAC );
          }
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
          /*
           * Initialize for prepended IV for block cipher in TLS v1.1 and up
           */
          if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
          {
              dec_msglen -= ssl->transform_in->ivlen;
              ssl->in_msglen -= ssl->transform_in->ivlen;
  
              for( i = 0; i < ssl->transform_in->ivlen; i++ )
                  ssl->transform_in->iv_dec[i] = ssl->in_iv[i];
          }
  #endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
  
          if( ( ret = mbedtls_cipher_crypt( &ssl->transform_in->cipher_ctx_dec,
                                     ssl->transform_in->iv_dec,
                                     ssl->transform_in->ivlen,
                                     dec_msg, dec_msglen,
                                     dec_msg_result, &olen ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
              return( ret );
          }
  
          if( dec_msglen != olen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1)
          if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 )
          {
              /*
               * Save IV in SSL3 and TLS1
               */
              memcpy( ssl->transform_in->iv_dec,
                      ssl->transform_in->cipher_ctx_dec.iv,
                      ssl->transform_in->ivlen );
          }
  #endif
  
          padlen = 1 + ssl->in_msg[ssl->in_msglen - 1];
  
          if( ssl->in_msglen < ssl->transform_in->maclen + padlen &&
              auth_done == 0 )
          {
  #if defined(MBEDTLS_SSL_DEBUG_ALL)
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%d) < maclen (%d) + padlen (%d)",
                          ssl->in_msglen, ssl->transform_in->maclen, padlen ) );
  #endif
              padlen = 0;
              correct = 0;
          }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
          if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
          {
              if( padlen > ssl->transform_in->ivlen )
              {
  #if defined(MBEDTLS_SSL_DEBUG_ALL)
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad padding length: is %d, "
                                      "should be no more than %d",
                                 padlen, ssl->transform_in->ivlen ) );
  #endif
                  correct = 0;
              }
          }
          else
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_2)
          if( ssl->minor_ver > MBEDTLS_SSL_MINOR_VERSION_0 )
          {
              /*
               * TLSv1+: always check the padding up to the first failure
               * and fake check up to 256 bytes of padding
               */
              size_t pad_count = 0, real_count = 1;
              size_t padding_idx = ssl->in_msglen - padlen - 1;
  
              /*
               * Padding is guaranteed to be incorrect if:
               *   1. padlen >= ssl->in_msglen
               *
               *   2. padding_idx >= MBEDTLS_SSL_MAX_CONTENT_LEN +
               *                     ssl->transform_in->maclen
               *
               * In both cases we reset padding_idx to a safe value (0) to
               * prevent out-of-buffer reads.
               */
              correct &= ( ssl->in_msglen >= padlen + 1 );
              correct &= ( padding_idx < MBEDTLS_SSL_MAX_CONTENT_LEN +
                                         ssl->transform_in->maclen );
  
              padding_idx *= correct;
  
              for( i = 1; i <= 256; i++ )
              {
                  real_count &= ( i <= padlen );
                  pad_count += real_count *
                               ( ssl->in_msg[padding_idx + i] == padlen - 1 );
              }
  
              correct &= ( pad_count == padlen ); /* Only 1 on correct padding */
  
  #if defined(MBEDTLS_SSL_DEBUG_ALL)
              if( padlen > 0 && correct == 0 )
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad padding byte detected" ) );
  #endif
              padlen &= correct * 0x1FF;
          }
          else
  #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
            MBEDTLS_SSL_PROTO_TLS1_2 */
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          ssl->in_msglen -= padlen;
      }
      else
  #endif /* MBEDTLS_CIPHER_MODE_CBC &&
            ( MBEDTLS_AES_C || MBEDTLS_CAMELLIA_C ) */
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "raw buffer after decryption",
                     ssl->in_msg, ssl->in_msglen );
  
      /*
       * Authenticate if not done yet.
       * Compute the MAC regardless of the padding result (RFC4346, CBCTIME).
       */
  #if defined(SSL_SOME_MODES_USE_MAC)
      if( auth_done == 0 )
      {
          unsigned char tmp[SSL_MAX_MAC_SIZE];
  
          ssl->in_msglen -= ssl->transform_in->maclen;
  
          ssl->in_len[0] = (unsigned char)( ssl->in_msglen >> 8 );
          ssl->in_len[1] = (unsigned char)( ssl->in_msglen      );
  
          memcpy( tmp, ssl->in_msg + ssl->in_msglen, ssl->transform_in->maclen );
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
          if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
          {
              ssl_mac( &ssl->transform_in->md_ctx_dec,
                        ssl->transform_in->mac_dec,
                        ssl->in_msg, ssl->in_msglen,
                        ssl->in_ctr, ssl->in_msgtype );
          }
          else
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
          defined(MBEDTLS_SSL_PROTO_TLS1_2)
          if( ssl->minor_ver > MBEDTLS_SSL_MINOR_VERSION_0 )
          {
              /*
               * Process MAC and always update for padlen afterwards to make
               * total time independent of padlen
               *
               * extra_run compensates MAC check for padlen
               *
               * Known timing attacks:
               *  - Lucky Thirteen (http://www.isg.rhul.ac.uk/tls/TLStiming.pdf)
               *
               * We use ( ( Lx + 8 ) / 64 ) to handle 'negative Lx' values
               * correctly. (We round down instead of up, so -56 is the correct
               * value for our calculations instead of -55)
               */
              size_t j, extra_run = 0;
              extra_run = ( 13 + ssl->in_msglen + padlen + 8 ) / 64 -
                          ( 13 + ssl->in_msglen          + 8 ) / 64;
  
              extra_run &= correct * 0xFF;
  
              mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_ctr, 8 );
              mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_hdr, 3 );
              mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_len, 2 );
              mbedtls_md_hmac_update( &ssl->transform_in->md_ctx_dec, ssl->in_msg,
                               ssl->in_msglen );
              mbedtls_md_hmac_finish( &ssl->transform_in->md_ctx_dec,
                               ssl->in_msg + ssl->in_msglen );
              /* Call mbedtls_md_process at least once due to cache attacks */
              for( j = 0; j < extra_run + 1; j++ )
                  mbedtls_md_process( &ssl->transform_in->md_ctx_dec, ssl->in_msg );
  
              mbedtls_md_hmac_reset( &ssl->transform_in->md_ctx_dec );
          }
          else
  #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
                MBEDTLS_SSL_PROTO_TLS1_2 */
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "message  mac", tmp, ssl->transform_in->maclen );
          MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac", ssl->in_msg + ssl->in_msglen,
                         ssl->transform_in->maclen );
  
          if( mbedtls_ssl_safer_memcmp( tmp, ssl->in_msg + ssl->in_msglen,
                           ssl->transform_in->maclen ) != 0 )
          {
  #if defined(MBEDTLS_SSL_DEBUG_ALL)
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
  #endif
              correct = 0;
          }
          auth_done++;
  
          /*
           * Finally check the correct flag
           */
          if( correct == 0 )
              return( MBEDTLS_ERR_SSL_INVALID_MAC );
      }
  #endif /* SSL_SOME_MODES_USE_MAC */
  
      /* Make extra sure authentication was performed, exactly once */
      if( auth_done != 1 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      if( ssl->in_msglen == 0 )
      {
          ssl->nb_zero++;
  
          /*
           * Three or more empty messages may be a DoS attack
           * (excessive CPU consumption).
           */
          if( ssl->nb_zero > 3 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "received four consecutive empty "
                                  "messages, possible DoS attack" ) );
              return( MBEDTLS_ERR_SSL_INVALID_MAC );
          }
      }
      else
          ssl->nb_zero = 0;
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          ; /* in_ctr read from peer, not maintained internally */
      }
      else
  #endif
      {
          for( i = 8; i > ssl_ep_len( ssl ); i-- )
              if( ++ssl->in_ctr[i - 1] != 0 )
                  break;
  
          /* The loop goes to its end iff the counter is wrapping */
          if( i == ssl_ep_len( ssl ) )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "incoming message counter would wrap" ) );
              return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
          }
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= decrypt buf" ) );
  
      return( 0 );
  }
  
  #undef MAC_NONE
  #undef MAC_PLAINTEXT
  #undef MAC_CIPHERTEXT
  
  #if defined(MBEDTLS_ZLIB_SUPPORT)
  /*
   * Compression/decompression functions
   */
  static int ssl_compress_buf( mbedtls_ssl_context *ssl )
  {
      int ret;
      unsigned char *msg_post = ssl->out_msg;
      size_t len_pre = ssl->out_msglen;
      unsigned char *msg_pre = ssl->compress_buf;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> compress buf" ) );
  
      if( len_pre == 0 )
          return( 0 );
  
      memcpy( msg_pre, ssl->out_msg, len_pre );
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "before compression: msglen = %d, ",
                     ssl->out_msglen ) );
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "before compression: output payload",
                     ssl->out_msg, ssl->out_msglen );
  
      ssl->transform_out->ctx_deflate.next_in = msg_pre;
      ssl->transform_out->ctx_deflate.avail_in = len_pre;
      ssl->transform_out->ctx_deflate.next_out = msg_post;
      ssl->transform_out->ctx_deflate.avail_out = MBEDTLS_SSL_BUFFER_LEN;
  
      ret = deflate( &ssl->transform_out->ctx_deflate, Z_SYNC_FLUSH );
      if( ret != Z_OK )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "failed to perform compression (%d)", ret ) );
          return( MBEDTLS_ERR_SSL_COMPRESSION_FAILED );
      }
  
      ssl->out_msglen = MBEDTLS_SSL_BUFFER_LEN -
                        ssl->transform_out->ctx_deflate.avail_out;
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "after compression: msglen = %d, ",
                     ssl->out_msglen ) );
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "after compression: output payload",
                     ssl->out_msg, ssl->out_msglen );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= compress buf" ) );
  
      return( 0 );
  }
  
  static int ssl_decompress_buf( mbedtls_ssl_context *ssl )
  {
      int ret;
      unsigned char *msg_post = ssl->in_msg;
      size_t len_pre = ssl->in_msglen;
      unsigned char *msg_pre = ssl->compress_buf;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> decompress buf" ) );
  
      if( len_pre == 0 )
          return( 0 );
  
      memcpy( msg_pre, ssl->in_msg, len_pre );
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "before decompression: msglen = %d, ",
                     ssl->in_msglen ) );
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "before decompression: input payload",
                     ssl->in_msg, ssl->in_msglen );
  
      ssl->transform_in->ctx_inflate.next_in = msg_pre;
      ssl->transform_in->ctx_inflate.avail_in = len_pre;
      ssl->transform_in->ctx_inflate.next_out = msg_post;
      ssl->transform_in->ctx_inflate.avail_out = MBEDTLS_SSL_MAX_CONTENT_LEN;
  
      ret = inflate( &ssl->transform_in->ctx_inflate, Z_SYNC_FLUSH );
      if( ret != Z_OK )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "failed to perform decompression (%d)", ret ) );
          return( MBEDTLS_ERR_SSL_COMPRESSION_FAILED );
      }
  
      ssl->in_msglen = MBEDTLS_SSL_MAX_CONTENT_LEN -
                       ssl->transform_in->ctx_inflate.avail_out;
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "after decompression: msglen = %d, ",
                     ssl->in_msglen ) );
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "after decompression: input payload",
                     ssl->in_msg, ssl->in_msglen );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= decompress buf" ) );
  
      return( 0 );
  }
  #endif /* MBEDTLS_ZLIB_SUPPORT */
  
  #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
  static int ssl_write_hello_request( mbedtls_ssl_context *ssl );
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
  static int ssl_resend_hello_request( mbedtls_ssl_context *ssl )
  {
      /* If renegotiation is not enforced, retransmit until we would reach max
       * timeout if we were using the usual handshake doubling scheme */
      if( ssl->conf->renego_max_records < 0 )
      {
          uint32_t ratio = ssl->conf->hs_timeout_max / ssl->conf->hs_timeout_min + 1;
          unsigned char doublings = 1;
  
          while( ratio != 0 )
          {
              ++doublings;
              ratio >>= 1;
          }
  
          if( ++ssl->renego_records_seen > doublings )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "no longer retransmitting hello request" ) );
              return( 0 );
          }
      }
  
      return( ssl_write_hello_request( ssl ) );
  }
  #endif
  #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
  
  /*
   * Fill the input message buffer by appending data to it.
   * The amount of data already fetched is in ssl->in_left.
   *
   * If we return 0, is it guaranteed that (at least) nb_want bytes are
   * available (from this read and/or a previous one). Otherwise, an error code
   * is returned (possibly EOF or WANT_READ).
   *
   * With stream transport (TLS) on success ssl->in_left == nb_want, but
   * with datagram transport (DTLS) on success ssl->in_left >= nb_want,
   * since we always read a whole datagram at once.
   *
   * For DTLS, it is up to the caller to set ssl->next_record_offset when
   * they're done reading a record.
   */
  int mbedtls_ssl_fetch_input( mbedtls_ssl_context *ssl, size_t nb_want )
  {
      int ret;
      size_t len;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> fetch input" ) );
  
      if( ssl->f_recv == NULL && ssl->f_recv_timeout == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
                              "or mbedtls_ssl_set_bio()" ) );
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      if( nb_want > MBEDTLS_SSL_BUFFER_LEN - (size_t)( ssl->in_hdr - ssl->in_buf ) )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "requesting more data than fits" ) );
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          uint32_t timeout;
  
          /* Just to be sure */
          if( ssl->f_set_timer == NULL || ssl->f_get_timer == NULL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "You must use "
                          "mbedtls_ssl_set_timer_cb() for DTLS" ) );
              return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
          }
  
          /*
           * The point is, we need to always read a full datagram at once, so we
           * sometimes read more then requested, and handle the additional data.
           * It could be the rest of the current record (while fetching the
           * header) and/or some other records in the same datagram.
           */
  
          /*
           * Move to the next record in the already read datagram if applicable
           */
          if( ssl->next_record_offset != 0 )
          {
              if( ssl->in_left < ssl->next_record_offset )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
                  return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
              }
  
              ssl->in_left -= ssl->next_record_offset;
  
              if( ssl->in_left != 0 )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 2, ( "next record in same datagram, offset: %d",
                                      ssl->next_record_offset ) );
                  memmove( ssl->in_hdr,
                           ssl->in_hdr + ssl->next_record_offset,
                           ssl->in_left );
              }
  
              ssl->next_record_offset = 0;
          }
  
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %d, nb_want: %d",
                         ssl->in_left, nb_want ) );
  
          /*
           * Done if we already have enough data.
           */
          if( nb_want <= ssl->in_left)
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
              return( 0 );
          }
  
          /*
           * A record can't be split accross datagrams. If we need to read but
           * are not at the beginning of a new record, the caller did something
           * wrong.
           */
          if( ssl->in_left != 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          /*
           * Don't even try to read if time's out already.
           * This avoids by-passing the timer when repeatedly receiving messages
           * that will end up being dropped.
           */
          if( ssl_check_timer( ssl ) != 0 )
              ret = MBEDTLS_ERR_SSL_TIMEOUT;
          else
          {
              len = MBEDTLS_SSL_BUFFER_LEN - ( ssl->in_hdr - ssl->in_buf );
  
              if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
                  timeout = ssl->handshake->retransmit_timeout;
              else
                  timeout = ssl->conf->read_timeout;
  
              MBEDTLS_SSL_DEBUG_MSG( 3, ( "f_recv_timeout: %u ms", timeout ) );
  
              if( ssl->f_recv_timeout != NULL )
                  ret = ssl->f_recv_timeout( ssl->p_bio, ssl->in_hdr, len,
                                                                      timeout );
              else
                  ret = ssl->f_recv( ssl->p_bio, ssl->in_hdr, len );
  
              MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
  
              if( ret == 0 )
                  return( MBEDTLS_ERR_SSL_CONN_EOF );
          }
  
          if( ret == MBEDTLS_ERR_SSL_TIMEOUT )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "timeout" ) );
              ssl_set_timer( ssl, 0 );
  
              if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
              {
                  if( ssl_double_retransmit_timeout( ssl ) != 0 )
                  {
                      MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake timeout" ) );
                      return( MBEDTLS_ERR_SSL_TIMEOUT );
                  }
  
                  if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
                  {
                      MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
                      return( ret );
                  }
  
                  return( MBEDTLS_ERR_SSL_WANT_READ );
              }
  #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
              else if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
                       ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
              {
                  if( ( ret = ssl_resend_hello_request( ssl ) ) != 0 )
                  {
                      MBEDTLS_SSL_DEBUG_RET( 1, "ssl_resend_hello_request", ret );
                      return( ret );
                  }
  
                  return( MBEDTLS_ERR_SSL_WANT_READ );
              }
  #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
          }
  
          if( ret < 0 )
              return( ret );
  
          ssl->in_left = ret;
      }
      else
  #endif
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %d, nb_want: %d",
                         ssl->in_left, nb_want ) );
  
          while( ssl->in_left < nb_want )
          {
              len = nb_want - ssl->in_left;
  
              if( ssl_check_timer( ssl ) != 0 )
                  ret = MBEDTLS_ERR_SSL_TIMEOUT;
              else
              {
                  if( ssl->f_recv_timeout != NULL )
                  {
                      ret = ssl->f_recv_timeout( ssl->p_bio,
                                                 ssl->in_hdr + ssl->in_left, len,
                                                 ssl->conf->read_timeout );
                  }
                  else
                  {
                      ret = ssl->f_recv( ssl->p_bio,
                                         ssl->in_hdr + ssl->in_left, len );
                  }
              }
  
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %d, nb_want: %d",
                                          ssl->in_left, nb_want ) );
              MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
  
              if( ret == 0 )
                  return( MBEDTLS_ERR_SSL_CONN_EOF );
  
              if( ret < 0 )
                  return( ret );
  
              ssl->in_left += ret;
          }
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
  
      return( 0 );
  }
  
  /*
   * Flush any data not yet written
   */
  int mbedtls_ssl_flush_output( mbedtls_ssl_context *ssl )
  {
      int ret;
      unsigned char *buf, i;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> flush output" ) );
  
      if( ssl->f_send == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
                              "or mbedtls_ssl_set_bio()" ) );
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      /* Avoid incrementing counter if data is flushed */
      if( ssl->out_left == 0 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
          return( 0 );
      }
  
      while( ssl->out_left > 0 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "message length: %d, out_left: %d",
                         mbedtls_ssl_hdr_len( ssl ) + ssl->out_msglen, ssl->out_left ) );
  
          buf = ssl->out_hdr + mbedtls_ssl_hdr_len( ssl ) +
                ssl->out_msglen - ssl->out_left;
          ret = ssl->f_send( ssl->p_bio, buf, ssl->out_left );
  
          MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_send", ret );
  
          if( ret <= 0 )
              return( ret );
  
          ssl->out_left -= ret;
      }
  
      for( i = 8; i > ssl_ep_len( ssl ); i-- )
          if( ++ssl->out_ctr[i - 1] != 0 )
              break;
  
      /* The loop goes to its end iff the counter is wrapping */
      if( i == ssl_ep_len( ssl ) )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "outgoing message counter would wrap" ) );
          return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
  
      return( 0 );
  }
  
  /*
   * Functions to handle the DTLS retransmission state machine
   */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
  /*
   * Append current handshake message to current outgoing flight
   */
  static int ssl_flight_append( mbedtls_ssl_context *ssl )
  {
      mbedtls_ssl_flight_item *msg;
  
      /* Allocate space for current message */
      if( ( msg = mbedtls_calloc( 1, sizeof(  mbedtls_ssl_flight_item ) ) ) == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %d bytes failed",
                              sizeof( mbedtls_ssl_flight_item ) ) );
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
      }
  
      if( ( msg->p = mbedtls_calloc( 1, ssl->out_msglen ) ) == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %d bytes failed", ssl->out_msglen ) );
          mbedtls_free( msg );
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
      }
  
      /* Copy current handshake message with headers */
      memcpy( msg->p, ssl->out_msg, ssl->out_msglen );
      msg->len = ssl->out_msglen;
      msg->type = ssl->out_msgtype;
      msg->next = NULL;
  
      /* Append to the current flight */
      if( ssl->handshake->flight == NULL )
          ssl->handshake->flight = msg;
      else
      {
          mbedtls_ssl_flight_item *cur = ssl->handshake->flight;
          while( cur->next != NULL )
              cur = cur->next;
          cur->next = msg;
      }
  
      return( 0 );
  }
  
  /*
   * Free the current flight of handshake messages
   */
  static void ssl_flight_free( mbedtls_ssl_flight_item *flight )
  {
      mbedtls_ssl_flight_item *cur = flight;
      mbedtls_ssl_flight_item *next;
  
      while( cur != NULL )
      {
          next = cur->next;
  
          mbedtls_free( cur->p );
          mbedtls_free( cur );
  
          cur = next;
      }
  }
  
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
  static void ssl_dtls_replay_reset( mbedtls_ssl_context *ssl );
  #endif
  
  /*
   * Swap transform_out and out_ctr with the alternative ones
   */
  static void ssl_swap_epochs( mbedtls_ssl_context *ssl )
  {
      mbedtls_ssl_transform *tmp_transform;
      unsigned char tmp_out_ctr[8];
  
      if( ssl->transform_out == ssl->handshake->alt_transform_out )
      {
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip swap epochs" ) );
          return;
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "swap epochs" ) );
  
      /* Swap transforms */
      tmp_transform                     = ssl->transform_out;
      ssl->transform_out                = ssl->handshake->alt_transform_out;
      ssl->handshake->alt_transform_out = tmp_transform;
  
      /* Swap epoch + sequence_number */
      memcpy( tmp_out_ctr,                 ssl->out_ctr,                8 );
      memcpy( ssl->out_ctr,                ssl->handshake->alt_out_ctr, 8 );
      memcpy( ssl->handshake->alt_out_ctr, tmp_out_ctr,                 8 );
  
      /* Adjust to the newly activated transform */
      if( ssl->transform_out != NULL &&
          ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
      {
          ssl->out_msg = ssl->out_iv + ssl->transform_out->ivlen -
                                       ssl->transform_out->fixed_ivlen;
      }
      else
          ssl->out_msg = ssl->out_iv;
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_activate != NULL )
      {
          if( ( ret = mbedtls_ssl_hw_record_activate( ssl, MBEDTLS_SSL_CHANNEL_OUTBOUND ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_activate", ret );
              return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
          }
      }
  #endif
  }
  
  /*
   * Retransmit the current flight of messages.
   *
   * Need to remember the current message in case flush_output returns
   * WANT_WRITE, causing us to exit this function and come back later.
   * This function must be called until state is no longer SENDING.
   */
  int mbedtls_ssl_resend( mbedtls_ssl_context *ssl )
  {
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_resend" ) );
  
      if( ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialise resending" ) );
  
          ssl->handshake->cur_msg = ssl->handshake->flight;
          ssl_swap_epochs( ssl );
  
          ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_SENDING;
      }
  
      while( ssl->handshake->cur_msg != NULL )
      {
          int ret;
          mbedtls_ssl_flight_item *cur = ssl->handshake->cur_msg;
  
          /* Swap epochs before sending Finished: we can't do it after
           * sending ChangeCipherSpec, in case write returns WANT_READ.
           * Must be done before copying, may change out_msg pointer */
          if( cur->type == MBEDTLS_SSL_MSG_HANDSHAKE &&
              cur->p[0] == MBEDTLS_SSL_HS_FINISHED )
          {
              ssl_swap_epochs( ssl );
          }
  
          memcpy( ssl->out_msg, cur->p, cur->len );
          ssl->out_msglen = cur->len;
          ssl->out_msgtype = cur->type;
  
          ssl->handshake->cur_msg = cur->next;
  
          MBEDTLS_SSL_DEBUG_BUF( 3, "resent handshake message header", ssl->out_msg, 12 );
  
          if( ( ret = mbedtls_ssl_write_record( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
              return( ret );
          }
      }
  
      if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
          ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
      else
      {
          ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
          ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_resend" ) );
  
      return( 0 );
  }
  
  /*
   * To be called when the last message of an incoming flight is received.
   */
  void mbedtls_ssl_recv_flight_completed( mbedtls_ssl_context *ssl )
  {
      /* We won't need to resend that one any more */
      ssl_flight_free( ssl->handshake->flight );
      ssl->handshake->flight = NULL;
      ssl->handshake->cur_msg = NULL;
  
      /* The next incoming flight will start with this msg_seq */
      ssl->handshake->in_flight_start_seq = ssl->handshake->in_msg_seq;
  
      /* Cancel timer */
      ssl_set_timer( ssl, 0 );
  
      if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
          ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
      {
          ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
      }
      else
          ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
  }
  
  /*
   * To be called when the last message of an outgoing flight is send.
   */
  void mbedtls_ssl_send_flight_completed( mbedtls_ssl_context *ssl )
  {
      ssl_reset_retransmit_timeout( ssl );
      ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
  
      if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
          ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
      {
          ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
      }
      else
          ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
  }
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
  
  /*
   * Record layer functions
   */
  
  /*
   * Write current record.
   * Uses ssl->out_msgtype, ssl->out_msglen and bytes at ssl->out_msg.
   */
  int mbedtls_ssl_write_record( mbedtls_ssl_context *ssl )
  {
      int ret, done = 0, out_msg_type;
      size_t len = ssl->out_msglen;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write record" ) );
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
          ssl->handshake != NULL &&
          ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
      {
          ; /* Skip special handshake treatment when resending */
      }
      else
  #endif
      if( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
      {
          out_msg_type = ssl->out_msg[0];
  
          if( out_msg_type != MBEDTLS_SSL_HS_HELLO_REQUEST &&
              ssl->handshake == NULL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
          }
  
          ssl->out_msg[1] = (unsigned char)( ( len - 4 ) >> 16 );
          ssl->out_msg[2] = (unsigned char)( ( len - 4 ) >>  8 );
          ssl->out_msg[3] = (unsigned char)( ( len - 4 )       );
  
          /*
           * DTLS has additional fields in the Handshake layer,
           * between the length field and the actual payload:
           *      uint16 message_seq;
           *      uint24 fragment_offset;
           *      uint24 fragment_length;
           */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
          if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
          {
              /* Make room for the additional DTLS fields */
              memmove( ssl->out_msg + 12, ssl->out_msg + 4, len - 4 );
              ssl->out_msglen += 8;
              len += 8;
  
              /* Write message_seq and update it, except for HelloRequest */
              if( out_msg_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
              {
                  ssl->out_msg[4] = ( ssl->handshake->out_msg_seq >> 8 ) & 0xFF;
                  ssl->out_msg[5] = ( ssl->handshake->out_msg_seq      ) & 0xFF;
                  ++( ssl->handshake->out_msg_seq );
              }
              else
              {
                  ssl->out_msg[4] = 0;
                  ssl->out_msg[5] = 0;
              }
  
              /* We don't fragment, so frag_offset = 0 and frag_len = len */
              memset( ssl->out_msg + 6, 0x00, 3 );
              memcpy( ssl->out_msg + 9, ssl->out_msg + 1, 3 );
          }
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
  
          if( out_msg_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
              ssl->handshake->update_checksum( ssl, ssl->out_msg, len );
      }
  
      /* Save handshake and CCS messages for resending */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
          ssl->handshake != NULL &&
          ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING &&
          ( ssl->out_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC ||
            ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE ) )
      {
          if( ( ret = ssl_flight_append( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "ssl_flight_append", ret );
              return( ret );
          }
      }
  #endif
  
  #if defined(MBEDTLS_ZLIB_SUPPORT)
      if( ssl->transform_out != NULL &&
          ssl->session_out->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
      {
          if( ( ret = ssl_compress_buf( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "ssl_compress_buf", ret );
              return( ret );
          }
  
          len = ssl->out_msglen;
      }
  #endif /*MBEDTLS_ZLIB_SUPPORT */
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_write != NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_write()" ) );
  
          ret = mbedtls_ssl_hw_record_write( ssl );
          if( ret != 0 && ret != MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_write", ret );
              return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
          }
  
          if( ret == 0 )
              done = 1;
      }
  #endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
      if( !done )
      {
          ssl->out_hdr[0] = (unsigned char) ssl->out_msgtype;
          mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
                             ssl->conf->transport, ssl->out_hdr + 1 );
  
          ssl->out_len[0] = (unsigned char)( len >> 8 );
          ssl->out_len[1] = (unsigned char)( len      );
  
          if( ssl->transform_out != NULL )
          {
              if( ( ret = ssl_encrypt_buf( ssl ) ) != 0 )
              {
                  MBEDTLS_SSL_DEBUG_RET( 1, "ssl_encrypt_buf", ret );
                  return( ret );
              }
  
              len = ssl->out_msglen;
              ssl->out_len[0] = (unsigned char)( len >> 8 );
              ssl->out_len[1] = (unsigned char)( len      );
          }
  
          ssl->out_left = mbedtls_ssl_hdr_len( ssl ) + ssl->out_msglen;
  
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "output record: msgtype = %d, "
                              "version = [%d:%d], msglen = %d",
                         ssl->out_hdr[0], ssl->out_hdr[1], ssl->out_hdr[2],
                       ( ssl->out_len[0] << 8 ) | ssl->out_len[1] ) );
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "output record sent to network",
                         ssl->out_hdr, mbedtls_ssl_hdr_len( ssl ) + ssl->out_msglen );
      }
  
      if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write record" ) );
  
      return( 0 );
  }
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
  /*
   * Mark bits in bitmask (used for DTLS HS reassembly)
   */
  static void ssl_bitmask_set( unsigned char *mask, size_t offset, size_t len )
  {
      unsigned int start_bits, end_bits;
  
      start_bits = 8 - ( offset % 8 );
      if( start_bits != 8 )
      {
          size_t first_byte_idx = offset / 8;
  
          /* Special case */
          if( len <= start_bits )
          {
              for( ; len != 0; len-- )
                  mask[first_byte_idx] |= 1 << ( start_bits - len );
  
              /* Avoid potential issues with offset or len becoming invalid */
              return;
          }
  
          offset += start_bits; /* Now offset % 8 == 0 */
          len -= start_bits;
  
          for( ; start_bits != 0; start_bits-- )
              mask[first_byte_idx] |= 1 << ( start_bits - 1 );
      }
  
      end_bits = len % 8;
      if( end_bits != 0 )
      {
          size_t last_byte_idx = ( offset + len ) / 8;
  
          len -= end_bits; /* Now len % 8 == 0 */
  
          for( ; end_bits != 0; end_bits-- )
              mask[last_byte_idx] |= 1 << ( 8 - end_bits );
      }
  
      memset( mask + offset / 8, 0xFF, len / 8 );
  }
  
  /*
   * Check that bitmask is full
   */
  static int ssl_bitmask_check( unsigned char *mask, size_t len )
  {
      size_t i;
  
      for( i = 0; i < len / 8; i++ )
          if( mask[i] != 0xFF )
              return( -1 );
  
      for( i = 0; i < len % 8; i++ )
          if( ( mask[len / 8] & ( 1 << ( 7 - i ) ) ) == 0 )
              return( -1 );
  
      return( 0 );
  }
  
  /*
   * Reassemble fragmented DTLS handshake messages.
   *
   * Use a temporary buffer for reassembly, divided in two parts:
   * - the first holds the reassembled message (including handshake header),
   * - the second holds a bitmask indicating which parts of the message
   *   (excluding headers) have been received so far.
   */
  static int ssl_reassemble_dtls_handshake( mbedtls_ssl_context *ssl )
  {
      unsigned char *msg, *bitmask;
      size_t frag_len, frag_off;
      size_t msg_len = ssl->in_hslen - 12; /* Without headers */
  
      if( ssl->handshake == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "not supported outside handshake (for now)" ) );
          return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
      }
  
      /*
       * For first fragment, check size and allocate buffer
       */
      if( ssl->handshake->hs_msg == NULL )
      {
          size_t alloc_len;
  
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialize reassembly, total length = %d",
                              msg_len ) );
  
          if( ssl->in_hslen > MBEDTLS_SSL_MAX_CONTENT_LEN )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake message too large" ) );
              return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
          }
  
          /* The bitmask needs one bit per byte of message excluding header */
          alloc_len = 12 + msg_len + msg_len / 8 + ( msg_len % 8 != 0 );
  
          ssl->handshake->hs_msg = mbedtls_calloc( 1, alloc_len );
          if( ssl->handshake->hs_msg == NULL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc failed (%d bytes)", alloc_len ) );
              return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
          }
  
          /* Prepare final header: copy msg_type, length and message_seq,
           * then add standardised fragment_offset and fragment_length */
          memcpy( ssl->handshake->hs_msg, ssl->in_msg, 6 );
          memset( ssl->handshake->hs_msg + 6, 0, 3 );
          memcpy( ssl->handshake->hs_msg + 9,
                  ssl->handshake->hs_msg + 1, 3 );
      }
      else
      {
          /* Make sure msg_type and length are consistent */
          if( memcmp( ssl->handshake->hs_msg, ssl->in_msg, 4 ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "fragment header mismatch" ) );
              return( MBEDTLS_ERR_SSL_INVALID_RECORD );
          }
      }
  
      msg = ssl->handshake->hs_msg + 12;
      bitmask = msg + msg_len;
  
      /*
       * Check and copy current fragment
       */
      frag_off = ( ssl->in_msg[6]  << 16 ) |
                 ( ssl->in_msg[7]  << 8  ) |
                   ssl->in_msg[8];
      frag_len = ( ssl->in_msg[9]  << 16 ) |
                 ( ssl->in_msg[10] << 8  ) |
                   ssl->in_msg[11];
  
      if( frag_off + frag_len > msg_len )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid fragment offset/len: %d + %d > %d",
                            frag_off, frag_len, msg_len ) );
          return( MBEDTLS_ERR_SSL_INVALID_RECORD );
      }
  
      if( frag_len + 12 > ssl->in_msglen )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid fragment length: %d + 12 > %d",
                            frag_len, ssl->in_msglen ) );
          return( MBEDTLS_ERR_SSL_INVALID_RECORD );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "adding fragment, offset = %d, length = %d",
                          frag_off, frag_len ) );
  
      memcpy( msg + frag_off, ssl->in_msg + 12, frag_len );
      ssl_bitmask_set( bitmask, frag_off, frag_len );
  
      /*
       * Do we have the complete message by now?
       * If yes, finalize it, else ask to read the next record.
       */
      if( ssl_bitmask_check( bitmask, msg_len ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "message is not complete yet" ) );
          return( MBEDTLS_ERR_SSL_WANT_READ );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "handshake message completed" ) );
  
      if( frag_len + 12 < ssl->in_msglen )
      {
          /*
           * We'got more handshake messages in the same record.
           * This case is not handled now because no know implementation does
           * that and it's hard to test, so we prefer to fail cleanly for now.
           */
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "last fragment not alone in its record" ) );
          return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
      }
  
      if( ssl->in_left > ssl->next_record_offset )
      {
          /*
           * We've got more data in the buffer after the current record,
           * that we don't want to overwrite. Move it before writing the
           * reassembled message, and adjust in_left and next_record_offset.
           */
          unsigned char *cur_remain = ssl->in_hdr + ssl->next_record_offset;
          unsigned char *new_remain = ssl->in_msg + ssl->in_hslen;
          size_t remain_len = ssl->in_left - ssl->next_record_offset;
  
          /* First compute and check new lengths */
          ssl->next_record_offset = new_remain - ssl->in_hdr;
          ssl->in_left = ssl->next_record_offset + remain_len;
  
          if( ssl->in_left > MBEDTLS_SSL_BUFFER_LEN -
                             (size_t)( ssl->in_hdr - ssl->in_buf ) )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "reassembled message too large for buffer" ) );
              return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
          }
  
          memmove( new_remain, cur_remain, remain_len );
      }
  
      memcpy( ssl->in_msg, ssl->handshake->hs_msg, ssl->in_hslen );
  
      mbedtls_free( ssl->handshake->hs_msg );
      ssl->handshake->hs_msg = NULL;
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "reassembled handshake message",
                     ssl->in_msg, ssl->in_hslen );
  
      return( 0 );
  }
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
  
  static int ssl_prepare_handshake_record( mbedtls_ssl_context *ssl )
  {
      if( ssl->in_msglen < mbedtls_ssl_hs_hdr_len( ssl ) )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake message too short: %d",
                              ssl->in_msglen ) );
          return( MBEDTLS_ERR_SSL_INVALID_RECORD );
      }
  
      ssl->in_hslen = mbedtls_ssl_hs_hdr_len( ssl ) + (
                      ( ssl->in_msg[1] << 16 ) |
                      ( ssl->in_msg[2] << 8  ) |
                        ssl->in_msg[3] );
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "handshake message: msglen ="
                          " %d, type = %d, hslen = %d",
                          ssl->in_msglen, ssl->in_msg[0], ssl->in_hslen ) );
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          int ret;
          unsigned int recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
  
          /* ssl->handshake is NULL when receiving ClientHello for renego */
          if( ssl->handshake != NULL &&
              recv_msg_seq != ssl->handshake->in_msg_seq )
          {
              /* Retransmit only on last message from previous flight, to avoid
               * too many retransmissions.
               * Besides, No sane server ever retransmits HelloVerifyRequest */
              if( recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 &&
                  ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 2, ( "received message from last flight, "
                                      "message_seq = %d, start_of_flight = %d",
                                      recv_msg_seq,
                                      ssl->handshake->in_flight_start_seq ) );
  
                  if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
                  {
                      MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
                      return( ret );
                  }
              }
              else
              {
                  MBEDTLS_SSL_DEBUG_MSG( 2, ( "dropping out-of-sequence message: "
                                      "message_seq = %d, expected = %d",
                                      recv_msg_seq,
                                      ssl->handshake->in_msg_seq ) );
              }
  
              return( MBEDTLS_ERR_SSL_WANT_READ );
          }
          /* Wait until message completion to increment in_msg_seq */
  
          /* Reassemble if current message is fragmented or reassembly is
           * already in progress */
          if( ssl->in_msglen < ssl->in_hslen ||
              memcmp( ssl->in_msg + 6, "\0\0\0",        3 ) != 0 ||
              memcmp( ssl->in_msg + 9, ssl->in_msg + 1, 3 ) != 0 ||
              ( ssl->handshake != NULL && ssl->handshake->hs_msg != NULL ) )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "found fragmented DTLS handshake message" ) );
  
              if( ( ret = ssl_reassemble_dtls_handshake( ssl ) ) != 0 )
              {
                  MBEDTLS_SSL_DEBUG_RET( 1, "ssl_reassemble_dtls_handshake", ret );
                  return( ret );
              }
          }
      }
      else
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
      /* With TLS we don't handle fragmentation (for now) */
      if( ssl->in_msglen < ssl->in_hslen )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS handshake fragmentation not supported" ) );
          return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
      }
  
      if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER &&
          ssl->handshake != NULL )
      {
          ssl->handshake->update_checksum( ssl, ssl->in_msg, ssl->in_hslen );
      }
  
      /* Handshake message is complete, increment counter */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
          ssl->handshake != NULL )
      {
          ssl->handshake->in_msg_seq++;
      }
  #endif
  
      return( 0 );
  }
  
  /*
   * DTLS anti-replay: RFC 6347 4.1.2.6
   *
   * in_window is a field of bits numbered from 0 (lsb) to 63 (msb).
   * Bit n is set iff record number in_window_top - n has been seen.
   *
   * Usually, in_window_top is the last record number seen and the lsb of
   * in_window is set. The only exception is the initial state (record number 0
   * not seen yet).
   */
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
  static void ssl_dtls_replay_reset( mbedtls_ssl_context *ssl )
  {
      ssl->in_window_top = 0;
      ssl->in_window = 0;
  }
  
  static inline uint64_t ssl_load_six_bytes( unsigned char *buf )
  {
      return( ( (uint64_t) buf[0] << 40 ) |
              ( (uint64_t) buf[1] << 32 ) |
              ( (uint64_t) buf[2] << 24 ) |
              ( (uint64_t) buf[3] << 16 ) |
              ( (uint64_t) buf[4] <<  8 ) |
              ( (uint64_t) buf[5]       ) );
  }
  
  /*
   * Return 0 if sequence number is acceptable, -1 otherwise
   */
  int mbedtls_ssl_dtls_replay_check( mbedtls_ssl_context *ssl )
  {
      uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
      uint64_t bit;
  
      if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
          return( 0 );
  
      if( rec_seqnum > ssl->in_window_top )
          return( 0 );
  
      bit = ssl->in_window_top - rec_seqnum;
  
      if( bit >= 64 )
          return( -1 );
  
      if( ( ssl->in_window & ( (uint64_t) 1 << bit ) ) != 0 )
          return( -1 );
  
      return( 0 );
  }
  
  /*
   * Update replay window on new validated record
   */
  void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl )
  {
      uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
  
      if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
          return;
  
      if( rec_seqnum > ssl->in_window_top )
      {
          /* Update window_top and the contents of the window */
          uint64_t shift = rec_seqnum - ssl->in_window_top;
  
          if( shift >= 64 )
              ssl->in_window = 1;
          else
          {
              ssl->in_window <<= shift;
              ssl->in_window |= 1;
          }
  
          ssl->in_window_top = rec_seqnum;
      }
      else
      {
          /* Mark that number as seen in the current window */
          uint64_t bit = ssl->in_window_top - rec_seqnum;
  
          if( bit < 64 ) /* Always true, but be extra sure */
              ssl->in_window |= (uint64_t) 1 << bit;
      }
  }
  #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
  
  #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
  /* Forward declaration */
  static int ssl_session_reset_int( mbedtls_ssl_context *ssl, int partial );
  
  /*
   * Without any SSL context, check if a datagram looks like a ClientHello with
   * a valid cookie, and if it doesn't, generate a HelloVerifyRequest message.
   * Both input and output include full DTLS headers.
   *
   * - if cookie is valid, return 0
   * - if ClientHello looks superficially valid but cookie is not,
   *   fill obuf and set olen, then
   *   return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
   * - otherwise return a specific error code
   */
  static int ssl_check_dtls_clihlo_cookie(
                             mbedtls_ssl_cookie_write_t *f_cookie_write,
                             mbedtls_ssl_cookie_check_t *f_cookie_check,
                             void *p_cookie,
                             const unsigned char *cli_id, size_t cli_id_len,
                             const unsigned char *in, size_t in_len,
                             unsigned char *obuf, size_t buf_len, size_t *olen )
  {
      size_t sid_len, cookie_len;
      unsigned char *p;
  
      if( f_cookie_write == NULL || f_cookie_check == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      /*
       * Structure of ClientHello with record and handshake headers,
       * and expected values. We don't need to check a lot, more checks will be
       * done when actually parsing the ClientHello - skipping those checks
       * avoids code duplication and does not make cookie forging any easier.
       *
       *  0-0  ContentType type;                  copied, must be handshake
       *  1-2  ProtocolVersion version;           copied
       *  3-4  uint16 epoch;                      copied, must be 0
       *  5-10 uint48 sequence_number;            copied
       * 11-12 uint16 length;                     (ignored)
       *
       * 13-13 HandshakeType msg_type;            (ignored)
       * 14-16 uint24 length;                     (ignored)
       * 17-18 uint16 message_seq;                copied
       * 19-21 uint24 fragment_offset;            copied, must be 0
       * 22-24 uint24 fragment_length;            (ignored)
       *
       * 25-26 ProtocolVersion client_version;    (ignored)
       * 27-58 Random random;                     (ignored)
       * 59-xx SessionID session_id;              1 byte len + sid_len content
       * 60+   opaque cookie<0..2^8-1>;           1 byte len + content
       *       ...
       *
       * Minimum length is 61 bytes.
       */
      if( in_len < 61 ||
          in[0] != MBEDTLS_SSL_MSG_HANDSHAKE ||
          in[3] != 0 || in[4] != 0 ||
          in[19] != 0 || in[20] != 0 || in[21] != 0 )
      {
          return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
      }
  
      sid_len = in[59];
      if( sid_len > in_len - 61 )
          return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
  
      cookie_len = in[60 + sid_len];
      if( cookie_len > in_len - 60 )
          return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
  
      if( f_cookie_check( p_cookie, in + sid_len + 61, cookie_len,
                          cli_id, cli_id_len ) == 0 )
      {
          /* Valid cookie */
          return( 0 );
      }
  
      /*
       * If we get here, we've got an invalid cookie, let's prepare HVR.
       *
       *  0-0  ContentType type;                  copied
       *  1-2  ProtocolVersion version;           copied
       *  3-4  uint16 epoch;                      copied
       *  5-10 uint48 sequence_number;            copied
       * 11-12 uint16 length;                     olen - 13
       *
       * 13-13 HandshakeType msg_type;            hello_verify_request
       * 14-16 uint24 length;                     olen - 25
       * 17-18 uint16 message_seq;                copied
       * 19-21 uint24 fragment_offset;            copied
       * 22-24 uint24 fragment_length;            olen - 25
       *
       * 25-26 ProtocolVersion server_version;    0xfe 0xff
       * 27-27 opaque cookie<0..2^8-1>;           cookie_len = olen - 27, cookie
       *
       * Minimum length is 28.
       */
      if( buf_len < 28 )
          return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
  
      /* Copy most fields and adapt others */
      memcpy( obuf, in, 25 );
      obuf[13] = MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST;
      obuf[25] = 0xfe;
      obuf[26] = 0xff;
  
      /* Generate and write actual cookie */
      p = obuf + 28;
      if( f_cookie_write( p_cookie,
                          &p, obuf + buf_len, cli_id, cli_id_len ) != 0 )
      {
          return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      *olen = p - obuf;
  
      /* Go back and fill length fields */
      obuf[27] = (unsigned char)( *olen - 28 );
  
      obuf[14] = obuf[22] = (unsigned char)( ( *olen - 25 ) >> 16 );
      obuf[15] = obuf[23] = (unsigned char)( ( *olen - 25 ) >>  8 );
      obuf[16] = obuf[24] = (unsigned char)( ( *olen - 25 )       );
  
      obuf[11] = (unsigned char)( ( *olen - 13 ) >>  8 );
      obuf[12] = (unsigned char)( ( *olen - 13 )       );
  
      return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
  }
  
  /*
   * Handle possible client reconnect with the same UDP quadruplet
   * (RFC 6347 Section 4.2.8).
   *
   * Called by ssl_parse_record_header() in case we receive an epoch 0 record
   * that looks like a ClientHello.
   *
   * - if the input looks like a ClientHello without cookies,
   *   send back HelloVerifyRequest, then
   *   return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
   * - if the input looks like a ClientHello with a valid cookie,
   *   reset the session of the current context, and
   *   return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
   * - if anything goes wrong, return a specific error code
   *
   * mbedtls_ssl_read_record() will ignore the record if anything else than
   * MBEDTLS_ERR_SSL_CLIENT_RECONNECT or 0 is returned, although this function
   * cannot not return 0.
   */
  static int ssl_handle_possible_reconnect( mbedtls_ssl_context *ssl )
  {
      int ret;
      size_t len;
  
      ret = ssl_check_dtls_clihlo_cookie(
              ssl->conf->f_cookie_write,
              ssl->conf->f_cookie_check,
              ssl->conf->p_cookie,
              ssl->cli_id, ssl->cli_id_len,
              ssl->in_buf, ssl->in_left,
              ssl->out_buf, MBEDTLS_SSL_MAX_CONTENT_LEN, &len );
  
      MBEDTLS_SSL_DEBUG_RET( 2, "ssl_check_dtls_clihlo_cookie", ret );
  
      if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
      {
          /* Dont check write errors as we can't do anything here.
           * If the error is permanent we'll catch it later,
           * if it's not, then hopefully it'll work next time. */
          (void) ssl->f_send( ssl->p_bio, ssl->out_buf, len );
  
          return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
      }
  
      if( ret == 0 )
      {
          /* Got a valid cookie, partially reset context */
          if( ( ret = ssl_session_reset_int( ssl, 1 ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "reset", ret );
              return( ret );
          }
  
          return( MBEDTLS_ERR_SSL_CLIENT_RECONNECT );
      }
  
      return( ret );
  }
  #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
  
  /*
   * ContentType type;
   * ProtocolVersion version;
   * uint16 epoch;            // DTLS only
   * uint48 sequence_number;  // DTLS only
   * uint16 length;
   *
   * Return 0 if header looks sane (and, for DTLS, the record is expected)
   * MBEDTLS_ERR_SSL_INVALID_RECORD if the header looks bad,
   * MBEDTLS_ERR_SSL_UNEXPECTED_RECORD (DTLS only) if sane but unexpected.
   *
   * With DTLS, mbedtls_ssl_read_record() will:
   * 1. proceed with the record if this function returns 0
   * 2. drop only the current record if this function returns UNEXPECTED_RECORD
   * 3. return CLIENT_RECONNECT if this function return that value
   * 4. drop the whole datagram if this function returns anything else.
   * Point 2 is needed when the peer is resending, and we have already received
   * the first record from a datagram but are still waiting for the others.
   */
  static int ssl_parse_record_header( mbedtls_ssl_context *ssl )
  {
      int ret;
      int major_ver, minor_ver;
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "input record header", ssl->in_hdr, mbedtls_ssl_hdr_len( ssl ) );
  
      ssl->in_msgtype =  ssl->in_hdr[0];
      ssl->in_msglen = ( ssl->in_len[0] << 8 ) | ssl->in_len[1];
      mbedtls_ssl_read_version( &major_ver, &minor_ver, ssl->conf->transport, ssl->in_hdr + 1 );
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "input record: msgtype = %d, "
                          "version = [%d:%d], msglen = %d",
                          ssl->in_msgtype,
                          major_ver, minor_ver, ssl->in_msglen ) );
  
      /* Check record type */
      if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE &&
          ssl->in_msgtype != MBEDTLS_SSL_MSG_ALERT &&
          ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
          ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type" ) );
  
          if( ( ret = mbedtls_ssl_send_alert_message( ssl,
                          MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                          MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE ) ) != 0 )
          {
              return( ret );
          }
  
          return( MBEDTLS_ERR_SSL_INVALID_RECORD );
      }
  
      /* Check version */
      if( major_ver != ssl->major_ver )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "major version mismatch" ) );
          return( MBEDTLS_ERR_SSL_INVALID_RECORD );
      }
  
      if( minor_ver > ssl->conf->max_minor_ver )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "minor version mismatch" ) );
          return( MBEDTLS_ERR_SSL_INVALID_RECORD );
      }
  
      /* Check length against the size of our buffer */
      if( ssl->in_msglen > MBEDTLS_SSL_BUFFER_LEN
                           - (size_t)( ssl->in_msg - ssl->in_buf ) )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
          return( MBEDTLS_ERR_SSL_INVALID_RECORD );
      }
  
      /* Check length against bounds of the current transform and version */
      if( ssl->transform_in == NULL )
      {
          if( ssl->in_msglen < 1 ||
              ssl->in_msglen > MBEDTLS_SSL_MAX_CONTENT_LEN )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
              return( MBEDTLS_ERR_SSL_INVALID_RECORD );
          }
      }
      else
      {
          if( ssl->in_msglen < ssl->transform_in->minlen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
              return( MBEDTLS_ERR_SSL_INVALID_RECORD );
          }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
          if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
              ssl->in_msglen > ssl->transform_in->minlen + MBEDTLS_SSL_MAX_CONTENT_LEN )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
              return( MBEDTLS_ERR_SSL_INVALID_RECORD );
          }
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_2)
          /*
           * TLS encrypted messages can have up to 256 bytes of padding
           */
          if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 &&
              ssl->in_msglen > ssl->transform_in->minlen +
                               MBEDTLS_SSL_MAX_CONTENT_LEN + 256 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
              return( MBEDTLS_ERR_SSL_INVALID_RECORD );
          }
  #endif
      }
  
      /*
       * DTLS-related tests done last, because most of them may result in
       * silently dropping the record (but not the whole datagram), and we only
       * want to consider that after ensuring that the "basic" fields (type,
       * version, length) are sane.
       */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          unsigned int rec_epoch = ( ssl->in_ctr[0] << 8 ) | ssl->in_ctr[1];
  
          /* Drop unexpected ChangeCipherSpec messages */
          if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
              ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC &&
              ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ChangeCipherSpec" ) );
              return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
          }
  
          /* Drop unexpected ApplicationData records,
           * except at the beginning of renegotiations */
          if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
              ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
              && ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
                     ssl->state == MBEDTLS_SSL_SERVER_HELLO )
  #endif
              )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
              return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
          }
  
          /* Check epoch (and sequence number) with DTLS */
          if( rec_epoch != ssl->in_epoch )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "record from another epoch: "
                                          "expected %d, received %d",
                                          ssl->in_epoch, rec_epoch ) );
  
  #if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
              /*
               * Check for an epoch 0 ClientHello. We can't use in_msg here to
               * access the first byte of record content (handshake type), as we
               * have an active transform (possibly iv_len != 0), so use the
               * fact that the record header len is 13 instead.
               */
              if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
                  ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER &&
                  rec_epoch == 0 &&
                  ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
                  ssl->in_left > 13 &&
                  ssl->in_buf[13] == MBEDTLS_SSL_HS_CLIENT_HELLO )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "possible client reconnect "
                                              "from the same port" ) );
                  return( ssl_handle_possible_reconnect( ssl ) );
              }
              else
  #endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
                  return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
          }
  
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
          /* Replay detection only works for the current epoch */
          if( rec_epoch == ssl->in_epoch &&
              mbedtls_ssl_dtls_replay_check( ssl ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "replayed record" ) );
              return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
          }
  #endif
      }
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
  
      return( 0 );
  }
  
  /*
   * If applicable, decrypt (and decompress) record content
   */
  static int ssl_prepare_record_content( mbedtls_ssl_context *ssl )
  {
      int ret, done = 0;
  
      MBEDTLS_SSL_DEBUG_BUF( 4, "input record from network",
                     ssl->in_hdr, mbedtls_ssl_hdr_len( ssl ) + ssl->in_msglen );
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_read != NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_read()" ) );
  
          ret = mbedtls_ssl_hw_record_read( ssl );
          if( ret != 0 && ret != MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_read", ret );
              return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
          }
  
          if( ret == 0 )
              done = 1;
      }
  #endif /* MBEDTLS_SSL_HW_RECORD_ACCEL */
      if( !done && ssl->transform_in != NULL )
      {
          if( ( ret = ssl_decrypt_buf( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decrypt_buf", ret );
              return( ret );
          }
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "input payload after decrypt",
                         ssl->in_msg, ssl->in_msglen );
  
          if( ssl->in_msglen > MBEDTLS_SSL_MAX_CONTENT_LEN )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
              return( MBEDTLS_ERR_SSL_INVALID_RECORD );
          }
      }
  
  #if defined(MBEDTLS_ZLIB_SUPPORT)
      if( ssl->transform_in != NULL &&
          ssl->session_in->compression == MBEDTLS_SSL_COMPRESS_DEFLATE )
      {
          if( ( ret = ssl_decompress_buf( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decompress_buf", ret );
              return( ret );
          }
      }
  #endif /* MBEDTLS_ZLIB_SUPPORT */
  
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          mbedtls_ssl_dtls_replay_update( ssl );
      }
  #endif
  
      return( 0 );
  }
  
  static void ssl_handshake_wrapup_free_hs_transform( mbedtls_ssl_context *ssl );
  
  /*
   * Read a record.
   *
   * Silently ignore non-fatal alert (and for DTLS, invalid records as well,
   * RFC 6347 4.1.2.7) and continue reading until a valid record is found.
   *
   */
  int mbedtls_ssl_read_record( mbedtls_ssl_context *ssl )
  {
      int ret;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read record" ) );
  
      if( ssl->in_hslen != 0 && ssl->in_hslen < ssl->in_msglen )
      {
          /*
           * Get next Handshake message in the current record
           */
          ssl->in_msglen -= ssl->in_hslen;
  
          memmove( ssl->in_msg, ssl->in_msg + ssl->in_hslen,
                   ssl->in_msglen );
  
          MBEDTLS_SSL_DEBUG_BUF( 4, "remaining content in record",
                             ssl->in_msg, ssl->in_msglen );
  
          if( ( ret = ssl_prepare_handshake_record( ssl ) ) != 0 )
              return( ret );
  
          return( 0 );
      }
  
      ssl->in_hslen = 0;
  
      /*
       * Read the record header and parse it
       */
  read_record_header:
      if( ( ret = mbedtls_ssl_fetch_input( ssl, mbedtls_ssl_hdr_len( ssl ) ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
          return( ret );
      }
  
      if( ( ret = ssl_parse_record_header( ssl ) ) != 0 )
      {
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
          if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
              ret != MBEDTLS_ERR_SSL_CLIENT_RECONNECT )
          {
              if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_RECORD )
              {
                  /* Skip unexpected record (but not whole datagram) */
                  ssl->next_record_offset = ssl->in_msglen
                                          + mbedtls_ssl_hdr_len( ssl );
  
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding unexpected record "
                                              "(header)" ) );
              }
              else
              {
                  /* Skip invalid record and the rest of the datagram */
                  ssl->next_record_offset = 0;
                  ssl->in_left = 0;
  
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record "
                                              "(header)" ) );
              }
  
              /* Get next record */
              goto read_record_header;
          }
  #endif
          return( ret );
      }
  
      /*
       * Read and optionally decrypt the message contents
       */
      if( ( ret = mbedtls_ssl_fetch_input( ssl,
                                   mbedtls_ssl_hdr_len( ssl ) + ssl->in_msglen ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
          return( ret );
      }
  
      /* Done reading this record, get ready for the next one */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
          ssl->next_record_offset = ssl->in_msglen + mbedtls_ssl_hdr_len( ssl );
      else
  #endif
          ssl->in_left = 0;
  
      if( ( ret = ssl_prepare_record_content( ssl ) ) != 0 )
      {
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
          if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
          {
              /* Silently discard invalid records */
              if( ret == MBEDTLS_ERR_SSL_INVALID_RECORD ||
                  ret == MBEDTLS_ERR_SSL_INVALID_MAC )
              {
                  /* Except when waiting for Finished as a bad mac here
                   * probably means something went wrong in the handshake
                   * (eg wrong psk used, mitm downgrade attempt, etc.) */
                  if( ssl->state == MBEDTLS_SSL_CLIENT_FINISHED ||
                      ssl->state == MBEDTLS_SSL_SERVER_FINISHED )
                  {
  #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
                      if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
                      {
                          mbedtls_ssl_send_alert_message( ssl,
                                  MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                                  MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
                      }
  #endif
                      return( ret );
                  }
  
  #if defined(MBEDTLS_SSL_DTLS_BADMAC_LIMIT)
                  if( ssl->conf->badmac_limit != 0 &&
                      ++ssl->badmac_seen >= ssl->conf->badmac_limit )
                  {
                      MBEDTLS_SSL_DEBUG_MSG( 1, ( "too many records with bad MAC" ) );
                      return( MBEDTLS_ERR_SSL_INVALID_MAC );
                  }
  #endif
  
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record (mac)" ) );
                  goto read_record_header;
              }
  
              return( ret );
          }
          else
  #endif
          {
              /* Error out (and send alert) on invalid records */
  #if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
              if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
              {
                  mbedtls_ssl_send_alert_message( ssl,
                          MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                          MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
              }
  #endif
              return( ret );
          }
      }
  
      /*
       * When we sent the last flight of the handshake, we MUST respond to a
       * retransmit of the peer's previous flight with a retransmit. (In
       * practice, only the Finished message will make it, other messages
       * including CCS use the old transform so they're dropped as invalid.)
       *
       * If the record we received is not a handshake message, however, it
       * means the peer received our last flight so we can clean up
       * handshake info.
       *
       * This check needs to be done before prepare_handshake() due to an edge
       * case: if the client immediately requests renegotiation, this
       * finishes the current handshake first, avoiding the new ClientHello
       * being mistaken for an ancient message in the current handshake.
       */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
          ssl->handshake != NULL &&
          ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
      {
          if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
                  ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "received retransmit of last flight" ) );
  
              if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
              {
                  MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
                  return( ret );
              }
  
              return( MBEDTLS_ERR_SSL_WANT_READ );
          }
          else
          {
              ssl_handshake_wrapup_free_hs_transform( ssl );
          }
      }
  #endif
  
      /*
       * Handle particular types of records
       */
      if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
      {
          if( ( ret = ssl_prepare_handshake_record( ssl ) ) != 0 )
              return( ret );
      }
  
      if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "got an alert message, type: [%d:%d]",
                         ssl->in_msg[0], ssl->in_msg[1] ) );
  
          /*
           * Ignore non-fatal alerts, except close_notify and no_renegotiation
           */
          if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "is a fatal alert message (msg %d)",
                             ssl->in_msg[1] ) );
              return( MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
          }
  
          if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
              ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a close notify message" ) );
              return( MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY );
          }
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED)
          if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
              ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no_cert" ) );
              /* Will be handled when trying to parse ServerHello */
              return( 0 );
          }
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) && defined(MBEDTLS_SSL_SRV_C)
          if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 &&
              ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
              ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
              ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_CERT )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a SSLv3 no_cert" ) );
              /* Will be handled in mbedtls_ssl_parse_certificate() */
              return( 0 );
          }
  #endif /* MBEDTLS_SSL_PROTO_SSL3 && MBEDTLS_SSL_SRV_C */
  
          /* Silently ignore: fetch new message */
          goto read_record_header;
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read record" ) );
  
      return( 0 );
  }
  
  int mbedtls_ssl_send_fatal_handshake_failure( mbedtls_ssl_context *ssl )
  {
      int ret;
  
      if( ( ret = mbedtls_ssl_send_alert_message( ssl,
                      MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                      MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE ) ) != 0 )
      {
          return( ret );
      }
  
      return( 0 );
  }
  
  int mbedtls_ssl_send_alert_message( mbedtls_ssl_context *ssl,
                              unsigned char level,
                              unsigned char message )
  {
      int ret;
  
      if( ssl == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> send alert message" ) );
  
      ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT;
      ssl->out_msglen = 2;
      ssl->out_msg[0] = level;
      ssl->out_msg[1] = message;
  
      if( ( ret = mbedtls_ssl_write_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= send alert message" ) );
  
      return( 0 );
  }
  
  /*
   * Handshake functions
   */
  #if !defined(MBEDTLS_KEY_EXCHANGE_RSA_ENABLED)         && \
      !defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)     && \
      !defined(MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED)     && \
      !defined(MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED)   && \
      !defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED) && \
      !defined(MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED)    && \
      !defined(MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED)
  int mbedtls_ssl_write_certificate( mbedtls_ssl_context *ssl )
  {
      const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
  
      if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
          ssl->state++;
          return( 0 );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
      return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
  }
  
  int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
  {
      const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
  
      if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
          ssl->state++;
          return( 0 );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
      return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
  }
  #else
  int mbedtls_ssl_write_certificate( mbedtls_ssl_context *ssl )
  {
      int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
      size_t i, n;
      const mbedtls_x509_crt *crt;
      const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write certificate" ) );
  
      if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
          ssl->state++;
          return( 0 );
      }
  
  #if defined(MBEDTLS_SSL_CLI_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
      {
          if( ssl->client_auth == 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip write certificate" ) );
              ssl->state++;
              return( 0 );
          }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
          /*
           * If using SSLv3 and got no cert, send an Alert message
           * (otherwise an empty Certificate message will be sent).
           */
          if( mbedtls_ssl_own_cert( ssl )  == NULL &&
              ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
          {
              ssl->out_msglen  = 2;
              ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT;
              ssl->out_msg[0]  = MBEDTLS_SSL_ALERT_LEVEL_WARNING;
              ssl->out_msg[1]  = MBEDTLS_SSL_ALERT_MSG_NO_CERT;
  
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "got no certificate to send" ) );
              goto write_msg;
          }
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
      }
  #endif /* MBEDTLS_SSL_CLI_C */
  #if defined(MBEDTLS_SSL_SRV_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
      {
          if( mbedtls_ssl_own_cert( ssl ) == NULL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no certificate to send" ) );
              return( MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED );
          }
      }
  #endif
  
      MBEDTLS_SSL_DEBUG_CRT( 3, "own certificate", mbedtls_ssl_own_cert( ssl ) );
  
      /*
       *     0  .  0    handshake type
       *     1  .  3    handshake length
       *     4  .  6    length of all certs
       *     7  .  9    length of cert. 1
       *    10  . n-1   peer certificate
       *     n  . n+2   length of cert. 2
       *    n+3 . ...   upper level cert, etc.
       */
      i = 7;
      crt = mbedtls_ssl_own_cert( ssl );
  
      while( crt != NULL )
      {
          n = crt->raw.len;
          if( n > MBEDTLS_SSL_MAX_CONTENT_LEN - 3 - i )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "certificate too large, %d > %d",
                             i + 3 + n, MBEDTLS_SSL_MAX_CONTENT_LEN ) );
              return( MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE );
          }
  
          ssl->out_msg[i    ] = (unsigned char)( n >> 16 );
          ssl->out_msg[i + 1] = (unsigned char)( n >>  8 );
          ssl->out_msg[i + 2] = (unsigned char)( n       );
  
          i += 3; memcpy( ssl->out_msg + i, crt->raw.p, n );
          i += n; crt = crt->next;
      }
  
      ssl->out_msg[4]  = (unsigned char)( ( i - 7 ) >> 16 );
      ssl->out_msg[5]  = (unsigned char)( ( i - 7 ) >>  8 );
      ssl->out_msg[6]  = (unsigned char)( ( i - 7 )       );
  
      ssl->out_msglen  = i;
      ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
      ssl->out_msg[0]  = MBEDTLS_SSL_HS_CERTIFICATE;
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) && defined(MBEDTLS_SSL_CLI_C)
  write_msg:
  #endif
  
      ssl->state++;
  
      if( ( ret = mbedtls_ssl_write_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write certificate" ) );
  
      return( ret );
  }
  
  int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
  {
      int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
      size_t i, n;
      const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info;
      int authmode = ssl->conf->authmode;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
  
      if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK ||
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECJPAKE )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
          ssl->state++;
          return( 0 );
      }
  
  #if defined(MBEDTLS_SSL_SRV_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
          ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
          ssl->state++;
          return( 0 );
      }
  
  #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
      if( ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET )
          authmode = ssl->handshake->sni_authmode;
  #endif
  
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
          authmode == MBEDTLS_SSL_VERIFY_NONE )
      {
          ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_SKIP_VERIFY;
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate" ) );
          ssl->state++;
          return( 0 );
      }
  #endif
  
      if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
          return( ret );
      }
  
      ssl->state++;
  
  #if defined(MBEDTLS_SSL_SRV_C)
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
      /*
       * Check if the client sent an empty certificate
       */
      if( ssl->conf->endpoint  == MBEDTLS_SSL_IS_SERVER &&
          ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
      {
          if( ssl->in_msglen  == 2                        &&
              ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT            &&
              ssl->in_msg[0]  == MBEDTLS_SSL_ALERT_LEVEL_WARNING  &&
              ssl->in_msg[1]  == MBEDTLS_SSL_ALERT_MSG_NO_CERT )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "SSLv3 client has no certificate" ) );
  
              ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_MISSING;
              if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL )
                  return( 0 );
              else
                  return( MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE );
          }
      }
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_2)
      if( ssl->conf->endpoint  == MBEDTLS_SSL_IS_SERVER &&
          ssl->minor_ver != MBEDTLS_SSL_MINOR_VERSION_0 )
      {
          if( ssl->in_hslen   == 3 + mbedtls_ssl_hs_hdr_len( ssl ) &&
              ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE    &&
              ssl->in_msg[0]  == MBEDTLS_SSL_HS_CERTIFICATE   &&
              memcmp( ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl ), "\0\0\0", 3 ) == 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLSv1 client has no certificate" ) );
  
              ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_MISSING;
              if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL )
                  return( 0 );
              else
                  return( MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE );
          }
      }
  #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
            MBEDTLS_SSL_PROTO_TLS1_2 */
  #endif /* MBEDTLS_SSL_SRV_C */
  
      if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
          return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
      }
  
      if( ssl->in_msg[0] != MBEDTLS_SSL_HS_CERTIFICATE ||
          ssl->in_hslen < mbedtls_ssl_hs_hdr_len( ssl ) + 3 + 3 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
          return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
      }
  
      i = mbedtls_ssl_hs_hdr_len( ssl );
  
      /*
       * Same message structure as in mbedtls_ssl_write_certificate()
       */
      n = ( ssl->in_msg[i+1] << 8 ) | ssl->in_msg[i+2];
  
      if( ssl->in_msg[i] != 0 ||
          ssl->in_hslen != n + 3 + mbedtls_ssl_hs_hdr_len( ssl ) )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
          return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
      }
  
      /* In case we tried to reuse a session but it failed */
      if( ssl->session_negotiate->peer_cert != NULL )
      {
          mbedtls_x509_crt_free( ssl->session_negotiate->peer_cert );
          mbedtls_free( ssl->session_negotiate->peer_cert );
      }
  
      if( ( ssl->session_negotiate->peer_cert = mbedtls_calloc( 1,
                      sizeof( mbedtls_x509_crt ) ) ) == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
                         sizeof( mbedtls_x509_crt ) ) );
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
      }
  
      mbedtls_x509_crt_init( ssl->session_negotiate->peer_cert );
  
      i += 3;
  
      while( i < ssl->in_hslen )
      {
          if( ssl->in_msg[i] != 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
              return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
          }
  
          n = ( (unsigned int) ssl->in_msg[i + 1] << 8 )
              | (unsigned int) ssl->in_msg[i + 2];
          i += 3;
  
          if( n < 128 || i + n > ssl->in_hslen )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate message" ) );
              return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
          }
  
          ret = mbedtls_x509_crt_parse_der( ssl->session_negotiate->peer_cert,
                                    ssl->in_msg + i, n );
          if( ret != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, " mbedtls_x509_crt_parse_der", ret );
              return( ret );
          }
  
          i += n;
      }
  
      MBEDTLS_SSL_DEBUG_CRT( 3, "peer certificate", ssl->session_negotiate->peer_cert );
  
      /*
       * On client, make sure the server cert doesn't change during renego to
       * avoid "triple handshake" attack: https://secure-resumption.com/
       */
  #if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
          ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
      {
          if( ssl->session->peer_cert == NULL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "new server cert during renegotiation" ) );
              return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
          }
  
          if( ssl->session->peer_cert->raw.len !=
              ssl->session_negotiate->peer_cert->raw.len ||
              memcmp( ssl->session->peer_cert->raw.p,
                      ssl->session_negotiate->peer_cert->raw.p,
                      ssl->session->peer_cert->raw.len ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "server cert changed during renegotiation" ) );
              return( MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE );
          }
      }
  #endif /* MBEDTLS_SSL_RENEGOTIATION && MBEDTLS_SSL_CLI_C */
  
      if( authmode != MBEDTLS_SSL_VERIFY_NONE )
      {
          mbedtls_x509_crt *ca_chain;
          mbedtls_x509_crl *ca_crl;
  
  #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
          if( ssl->handshake->sni_ca_chain != NULL )
          {
              ca_chain = ssl->handshake->sni_ca_chain;
              ca_crl   = ssl->handshake->sni_ca_crl;
          }
          else
  #endif
          {
              ca_chain = ssl->conf->ca_chain;
              ca_crl   = ssl->conf->ca_crl;
          }
  
          if( ca_chain == NULL )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no CA chain" ) );
              return( MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED );
          }
  
          /*
           * Main check: verify certificate
           */
          ret = mbedtls_x509_crt_verify_with_profile(
                                  ssl->session_negotiate->peer_cert,
                                  ca_chain, ca_crl,
                                  ssl->conf->cert_profile,
                                  ssl->hostname,
                                 &ssl->session_negotiate->verify_result,
                                  ssl->conf->f_vrfy, ssl->conf->p_vrfy );
  
          if( ret != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "x509_verify_cert", ret );
          }
  
          /*
           * Secondary checks: always done, but change 'ret' only if it was 0
           */
  
  #if defined(MBEDTLS_ECP_C)
          {
              const mbedtls_pk_context *pk = &ssl->session_negotiate->peer_cert->pk;
  
              /* If certificate uses an EC key, make sure the curve is OK */
              if( mbedtls_pk_can_do( pk, MBEDTLS_PK_ECKEY ) &&
                  mbedtls_ssl_check_curve( ssl, mbedtls_pk_ec( *pk )->grp.id ) != 0 )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (EC key curve)" ) );
                  if( ret == 0 )
                      ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE;
              }
          }
  #endif /* MBEDTLS_ECP_C */
  
          if( mbedtls_ssl_check_cert_usage( ssl->session_negotiate->peer_cert,
                                    ciphersuite_info,
                                    ! ssl->conf->endpoint,
                                   &ssl->session_negotiate->verify_result ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (usage extensions)" ) );
              if( ret == 0 )
                  ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE;
          }
  
          if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL )
              ret = 0;
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate" ) );
  
      return( ret );
  }
  #endif /* !MBEDTLS_KEY_EXCHANGE_RSA_ENABLED
            !MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED
            !MBEDTLS_KEY_EXCHANGE_DHE_RSA_ENABLED
            !MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED
            !MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED
            !MBEDTLS_KEY_EXCHANGE_ECDH_RSA_ENABLED
            !MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA_ENABLED */
  
  int mbedtls_ssl_write_change_cipher_spec( mbedtls_ssl_context *ssl )
  {
      int ret;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write change cipher spec" ) );
  
      ssl->out_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
      ssl->out_msglen  = 1;
      ssl->out_msg[0]  = 1;
  
      ssl->state++;
  
      if( ( ret = mbedtls_ssl_write_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write change cipher spec" ) );
  
      return( 0 );
  }
  
  int mbedtls_ssl_parse_change_cipher_spec( mbedtls_ssl_context *ssl )
  {
      int ret;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse change cipher spec" ) );
  
      if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
          return( ret );
      }
  
      if( ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad change cipher spec message" ) );
          return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
      }
  
      if( ssl->in_msglen != 1 || ssl->in_msg[0] != 1 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad change cipher spec message" ) );
          return( MBEDTLS_ERR_SSL_BAD_HS_CHANGE_CIPHER_SPEC );
      }
  
      /*
       * Switch to our negotiated transform and session parameters for inbound
       * data.
       */
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "switching to new transform spec for inbound data" ) );
      ssl->transform_in = ssl->transform_negotiate;
      ssl->session_in = ssl->session_negotiate;
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
          ssl_dtls_replay_reset( ssl );
  #endif
  
          /* Increment epoch */
          if( ++ssl->in_epoch == 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS epoch would wrap" ) );
              return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
          }
      }
      else
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
      memset( ssl->in_ctr, 0, 8 );
  
      /*
       * Set the in_msg pointer to the correct location based on IV length
       */
      if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
      {
          ssl->in_msg = ssl->in_iv + ssl->transform_negotiate->ivlen -
                        ssl->transform_negotiate->fixed_ivlen;
      }
      else
          ssl->in_msg = ssl->in_iv;
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_activate != NULL )
      {
          if( ( ret = mbedtls_ssl_hw_record_activate( ssl, MBEDTLS_SSL_CHANNEL_INBOUND ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_activate", ret );
              return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
          }
      }
  #endif
  
      ssl->state++;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse change cipher spec" ) );
  
      return( 0 );
  }
  
  void mbedtls_ssl_optimize_checksum( mbedtls_ssl_context *ssl,
                              const mbedtls_ssl_ciphersuite_t *ciphersuite_info )
  {
      ((void) ciphersuite_info);
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_1)
      if( ssl->minor_ver < MBEDTLS_SSL_MINOR_VERSION_3 )
          ssl->handshake->update_checksum = ssl_update_checksum_md5sha1;
      else
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA512_C)
      if( ciphersuite_info->mac == MBEDTLS_MD_SHA384 )
          ssl->handshake->update_checksum = ssl_update_checksum_sha384;
      else
  #endif
  #if defined(MBEDTLS_SHA256_C)
      if( ciphersuite_info->mac != MBEDTLS_MD_SHA384 )
          ssl->handshake->update_checksum = ssl_update_checksum_sha256;
      else
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
          return;
      }
  }
  
  void mbedtls_ssl_reset_checksum( mbedtls_ssl_context *ssl )
  {
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_1)
       mbedtls_md5_starts( &ssl->handshake->fin_md5  );
      mbedtls_sha1_starts( &ssl->handshake->fin_sha1 );
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
      mbedtls_sha256_starts( &ssl->handshake->fin_sha256, 0 );
  #endif
  #if defined(MBEDTLS_SHA512_C)
      mbedtls_sha512_starts( &ssl->handshake->fin_sha512, 1 );
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  }
  
  static void ssl_update_checksum_start( mbedtls_ssl_context *ssl,
                                         const unsigned char *buf, size_t len )
  {
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_1)
       mbedtls_md5_update( &ssl->handshake->fin_md5 , buf, len );
      mbedtls_sha1_update( &ssl->handshake->fin_sha1, buf, len );
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
      mbedtls_sha256_update( &ssl->handshake->fin_sha256, buf, len );
  #endif
  #if defined(MBEDTLS_SHA512_C)
      mbedtls_sha512_update( &ssl->handshake->fin_sha512, buf, len );
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_1)
  static void ssl_update_checksum_md5sha1( mbedtls_ssl_context *ssl,
                                           const unsigned char *buf, size_t len )
  {
       mbedtls_md5_update( &ssl->handshake->fin_md5 , buf, len );
      mbedtls_sha1_update( &ssl->handshake->fin_sha1, buf, len );
  }
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
  static void ssl_update_checksum_sha256( mbedtls_ssl_context *ssl,
                                          const unsigned char *buf, size_t len )
  {
      mbedtls_sha256_update( &ssl->handshake->fin_sha256, buf, len );
  }
  #endif
  
  #if defined(MBEDTLS_SHA512_C)
  static void ssl_update_checksum_sha384( mbedtls_ssl_context *ssl,
                                          const unsigned char *buf, size_t len )
  {
      mbedtls_sha512_update( &ssl->handshake->fin_sha512, buf, len );
  }
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
  static void ssl_calc_finished_ssl(
                  mbedtls_ssl_context *ssl, unsigned char *buf, int from )
  {
      const char *sender;
      mbedtls_md5_context  md5;
      mbedtls_sha1_context sha1;
  
      unsigned char padbuf[48];
      unsigned char md5sum[16];
      unsigned char sha1sum[20];
  
      mbedtls_ssl_session *session = ssl->session_negotiate;
      if( !session )
          session = ssl->session;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished ssl" ) );
  
      mbedtls_md5_init( &md5 );
      mbedtls_sha1_init( &sha1 );
  
      mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
      mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
  
      /*
       * SSLv3:
       *   hash =
       *      MD5( master + pad2 +
       *          MD5( handshake + sender + master + pad1 ) )
       *   + SHA1( master + pad2 +
       *         SHA1( handshake + sender + master + pad1 ) )
       */
  
  #if !defined(MBEDTLS_MD5_ALT)
      MBEDTLS_SSL_DEBUG_BUF( 4, "finished  md5 state", (unsigned char *)
                      md5.state, sizeof(  md5.state ) );
  #endif
  
  #if !defined(MBEDTLS_SHA1_ALT)
      MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha1 state", (unsigned char *)
                     sha1.state, sizeof( sha1.state ) );
  #endif
  
      sender = ( from == MBEDTLS_SSL_IS_CLIENT ) ? "CLNT"
                                         : "SRVR";
  
      memset( padbuf, 0x36, 48 );
  
      mbedtls_md5_update( &md5, (const unsigned char *) sender, 4 );
      mbedtls_md5_update( &md5, session->master, 48 );
      mbedtls_md5_update( &md5, padbuf, 48 );
      mbedtls_md5_finish( &md5, md5sum );
  
      mbedtls_sha1_update( &sha1, (const unsigned char *) sender, 4 );
      mbedtls_sha1_update( &sha1, session->master, 48 );
      mbedtls_sha1_update( &sha1, padbuf, 40 );
      mbedtls_sha1_finish( &sha1, sha1sum );
  
      memset( padbuf, 0x5C, 48 );
  
      mbedtls_md5_starts( &md5 );
      mbedtls_md5_update( &md5, session->master, 48 );
      mbedtls_md5_update( &md5, padbuf, 48 );
      mbedtls_md5_update( &md5, md5sum, 16 );
      mbedtls_md5_finish( &md5, buf );
  
      mbedtls_sha1_starts( &sha1 );
      mbedtls_sha1_update( &sha1, session->master, 48 );
      mbedtls_sha1_update( &sha1, padbuf , 40 );
      mbedtls_sha1_update( &sha1, sha1sum, 20 );
      mbedtls_sha1_finish( &sha1, buf + 16 );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, 36 );
  
      mbedtls_md5_free(  &md5  );
      mbedtls_sha1_free( &sha1 );
  
      mbedtls_zeroize(  padbuf, sizeof(  padbuf ) );
      mbedtls_zeroize(  md5sum, sizeof(  md5sum ) );
      mbedtls_zeroize( sha1sum, sizeof( sha1sum ) );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
  }
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
  static void ssl_calc_finished_tls(
                  mbedtls_ssl_context *ssl, unsigned char *buf, int from )
  {
      int len = 12;
      const char *sender;
      mbedtls_md5_context  md5;
      mbedtls_sha1_context sha1;
      unsigned char padbuf[36];
  
      mbedtls_ssl_session *session = ssl->session_negotiate;
      if( !session )
          session = ssl->session;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished tls" ) );
  
      mbedtls_md5_init( &md5 );
      mbedtls_sha1_init( &sha1 );
  
      mbedtls_md5_clone( &md5, &ssl->handshake->fin_md5 );
      mbedtls_sha1_clone( &sha1, &ssl->handshake->fin_sha1 );
  
      /*
       * TLSv1:
       *   hash = PRF( master, finished_label,
       *               MD5( handshake ) + SHA1( handshake ) )[0..11]
       */
  
  #if !defined(MBEDTLS_MD5_ALT)
      MBEDTLS_SSL_DEBUG_BUF( 4, "finished  md5 state", (unsigned char *)
                      md5.state, sizeof(  md5.state ) );
  #endif
  
  #if !defined(MBEDTLS_SHA1_ALT)
      MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha1 state", (unsigned char *)
                     sha1.state, sizeof( sha1.state ) );
  #endif
  
      sender = ( from == MBEDTLS_SSL_IS_CLIENT )
               ? "client finished"
               : "server finished";
  
      mbedtls_md5_finish(  &md5, padbuf );
      mbedtls_sha1_finish( &sha1, padbuf + 16 );
  
      ssl->handshake->tls_prf( session->master, 48, sender,
                               padbuf, 36, buf, len );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, len );
  
      mbedtls_md5_free(  &md5  );
      mbedtls_sha1_free( &sha1 );
  
      mbedtls_zeroize(  padbuf, sizeof(  padbuf ) );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
  }
  #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 */
  
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
  static void ssl_calc_finished_tls_sha256(
                  mbedtls_ssl_context *ssl, unsigned char *buf, int from )
  {
      int len = 12;
      const char *sender;
      mbedtls_sha256_context sha256;
      unsigned char padbuf[32];
  
      mbedtls_ssl_session *session = ssl->session_negotiate;
      if( !session )
          session = ssl->session;
  
      mbedtls_sha256_init( &sha256 );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished tls sha256" ) );
  
      mbedtls_sha256_clone( &sha256, &ssl->handshake->fin_sha256 );
  
      /*
       * TLSv1.2:
       *   hash = PRF( master, finished_label,
       *               Hash( handshake ) )[0.11]
       */
  
  #if !defined(MBEDTLS_SHA256_ALT)
      MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha2 state", (unsigned char *)
                     sha256.state, sizeof( sha256.state ) );
  #endif
  
      sender = ( from == MBEDTLS_SSL_IS_CLIENT )
               ? "client finished"
               : "server finished";
  
      mbedtls_sha256_finish( &sha256, padbuf );
  
      ssl->handshake->tls_prf( session->master, 48, sender,
                               padbuf, 32, buf, len );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, len );
  
      mbedtls_sha256_free( &sha256 );
  
      mbedtls_zeroize(  padbuf, sizeof(  padbuf ) );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
  }
  #endif /* MBEDTLS_SHA256_C */
  
  #if defined(MBEDTLS_SHA512_C)
  static void ssl_calc_finished_tls_sha384(
                  mbedtls_ssl_context *ssl, unsigned char *buf, int from )
  {
      int len = 12;
      const char *sender;
      mbedtls_sha512_context sha512;
      unsigned char padbuf[48];
  
      mbedtls_ssl_session *session = ssl->session_negotiate;
      if( !session )
          session = ssl->session;
  
      mbedtls_sha512_init( &sha512 );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> calc  finished tls sha384" ) );
  
      mbedtls_sha512_clone( &sha512, &ssl->handshake->fin_sha512 );
  
      /*
       * TLSv1.2:
       *   hash = PRF( master, finished_label,
       *               Hash( handshake ) )[0.11]
       */
  
  #if !defined(MBEDTLS_SHA512_ALT)
      MBEDTLS_SSL_DEBUG_BUF( 4, "finished sha512 state", (unsigned char *)
                     sha512.state, sizeof( sha512.state ) );
  #endif
  
      sender = ( from == MBEDTLS_SSL_IS_CLIENT )
               ? "client finished"
               : "server finished";
  
      mbedtls_sha512_finish( &sha512, padbuf );
  
      ssl->handshake->tls_prf( session->master, 48, sender,
                               padbuf, 48, buf, len );
  
      MBEDTLS_SSL_DEBUG_BUF( 3, "calc finished result", buf, len );
  
      mbedtls_sha512_free( &sha512 );
  
      mbedtls_zeroize(  padbuf, sizeof( padbuf ) );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= calc  finished" ) );
  }
  #endif /* MBEDTLS_SHA512_C */
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  
  static void ssl_handshake_wrapup_free_hs_transform( mbedtls_ssl_context *ssl )
  {
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "=> handshake wrapup: final free" ) );
  
      /*
       * Free our handshake params
       */
      mbedtls_ssl_handshake_free( ssl->handshake );
      mbedtls_free( ssl->handshake );
      ssl->handshake = NULL;
  
      /*
       * Free the previous transform and swith in the current one
       */
      if( ssl->transform )
      {
          mbedtls_ssl_transform_free( ssl->transform );
          mbedtls_free( ssl->transform );
      }
      ssl->transform = ssl->transform_negotiate;
      ssl->transform_negotiate = NULL;
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "<= handshake wrapup: final free" ) );
  }
  
  void mbedtls_ssl_handshake_wrapup( mbedtls_ssl_context *ssl )
  {
      int resume = ssl->handshake->resume;
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "=> handshake wrapup" ) );
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
      if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
      {
          ssl->renego_status =  MBEDTLS_SSL_RENEGOTIATION_DONE;
          ssl->renego_records_seen = 0;
      }
  #endif
  
      /*
       * Free the previous session and switch in the current one
       */
      if( ssl->session )
      {
  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
          /* RFC 7366 3.1: keep the EtM state */
          ssl->session_negotiate->encrypt_then_mac =
                    ssl->session->encrypt_then_mac;
  #endif
  
          mbedtls_ssl_session_free( ssl->session );
          mbedtls_free( ssl->session );
      }
      ssl->session = ssl->session_negotiate;
      ssl->session_negotiate = NULL;
  
      /*
       * Add cache entry
       */
      if( ssl->conf->f_set_cache != NULL &&
          ssl->session->id_len != 0 &&
          resume == 0 )
      {
          if( ssl->conf->f_set_cache( ssl->conf->p_cache, ssl->session ) != 0 )
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "cache did not store session" ) );
      }
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
          ssl->handshake->flight != NULL )
      {
          /* Cancel handshake timer */
          ssl_set_timer( ssl, 0 );
  
          /* Keep last flight around in case we need to resend it:
           * we need the handshake and transform structures for that */
          MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip freeing handshake and transform" ) );
      }
      else
  #endif
          ssl_handshake_wrapup_free_hs_transform( ssl );
  
      ssl->state++;
  
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "<= handshake wrapup" ) );
  }
  
  int mbedtls_ssl_write_finished( mbedtls_ssl_context *ssl )
  {
      int ret, hash_len;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write finished" ) );
  
      /*
       * Set the out_msg pointer to the correct location based on IV length
       */
      if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
      {
          ssl->out_msg = ssl->out_iv + ssl->transform_negotiate->ivlen -
                         ssl->transform_negotiate->fixed_ivlen;
      }
      else
          ssl->out_msg = ssl->out_iv;
  
      ssl->handshake->calc_finished( ssl, ssl->out_msg + 4, ssl->conf->endpoint );
  
      /*
       * RFC 5246 7.4.9 (Page 63) says 12 is the default length and ciphersuites
       * may define some other value. Currently (early 2016), no defined
       * ciphersuite does this (and this is unlikely to change as activity has
       * moved to TLS 1.3 now) so we can keep the hardcoded 12 here.
       */
      hash_len = ( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 ) ? 36 : 12;
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
      ssl->verify_data_len = hash_len;
      memcpy( ssl->own_verify_data, ssl->out_msg + 4, hash_len );
  #endif
  
      ssl->out_msglen  = 4 + hash_len;
      ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
      ssl->out_msg[0]  = MBEDTLS_SSL_HS_FINISHED;
  
      /*
       * In case of session resuming, invert the client and server
       * ChangeCipherSpec messages order.
       */
      if( ssl->handshake->resume != 0 )
      {
  #if defined(MBEDTLS_SSL_CLI_C)
          if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
              ssl->state = MBEDTLS_SSL_HANDSHAKE_WRAPUP;
  #endif
  #if defined(MBEDTLS_SSL_SRV_C)
          if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
              ssl->state = MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC;
  #endif
      }
      else
          ssl->state++;
  
      /*
       * Switch to our negotiated transform and session parameters for outbound
       * data.
       */
      MBEDTLS_SSL_DEBUG_MSG( 3, ( "switching to new transform spec for outbound data" ) );
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          unsigned char i;
  
          /* Remember current epoch settings for resending */
          ssl->handshake->alt_transform_out = ssl->transform_out;
          memcpy( ssl->handshake->alt_out_ctr, ssl->out_ctr, 8 );
  
          /* Set sequence_number to zero */
          memset( ssl->out_ctr + 2, 0, 6 );
  
          /* Increment epoch */
          for( i = 2; i > 0; i-- )
              if( ++ssl->out_ctr[i - 1] != 0 )
                  break;
  
          /* The loop goes to its end iff the counter is wrapping */
          if( i == 0 )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS epoch would wrap" ) );
              return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
          }
      }
      else
  #endif /* MBEDTLS_SSL_PROTO_DTLS */
      memset( ssl->out_ctr, 0, 8 );
  
      ssl->transform_out = ssl->transform_negotiate;
      ssl->session_out = ssl->session_negotiate;
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_activate != NULL )
      {
          if( ( ret = mbedtls_ssl_hw_record_activate( ssl, MBEDTLS_SSL_CHANNEL_OUTBOUND ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_activate", ret );
              return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
          }
      }
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
          mbedtls_ssl_send_flight_completed( ssl );
  #endif
  
      if( ( ret = mbedtls_ssl_write_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write finished" ) );
  
      return( 0 );
  }
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
  #define SSL_MAX_HASH_LEN 36
  #else
  #define SSL_MAX_HASH_LEN 12
  #endif
  
  int mbedtls_ssl_parse_finished( mbedtls_ssl_context *ssl )
  {
      int ret;
      unsigned int hash_len;
      unsigned char buf[SSL_MAX_HASH_LEN];
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse finished" ) );
  
      ssl->handshake->calc_finished( ssl, buf, ssl->conf->endpoint ^ 1 );
  
      if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
          return( ret );
      }
  
      if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
          return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
      }
  
      /* There is currently no ciphersuite using another length with TLS 1.2 */
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
      if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
          hash_len = 36;
      else
  #endif
          hash_len = 12;
  
      if( ssl->in_msg[0] != MBEDTLS_SSL_HS_FINISHED ||
          ssl->in_hslen  != mbedtls_ssl_hs_hdr_len( ssl ) + hash_len )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
          return( MBEDTLS_ERR_SSL_BAD_HS_FINISHED );
      }
  
      if( mbedtls_ssl_safer_memcmp( ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl ),
                        buf, hash_len ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
          return( MBEDTLS_ERR_SSL_BAD_HS_FINISHED );
      }
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
      ssl->verify_data_len = hash_len;
      memcpy( ssl->peer_verify_data, buf, hash_len );
  #endif
  
      if( ssl->handshake->resume != 0 )
      {
  #if defined(MBEDTLS_SSL_CLI_C)
          if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
              ssl->state = MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC;
  #endif
  #if defined(MBEDTLS_SSL_SRV_C)
          if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
              ssl->state = MBEDTLS_SSL_HANDSHAKE_WRAPUP;
  #endif
      }
      else
          ssl->state++;
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
          mbedtls_ssl_recv_flight_completed( ssl );
  #endif
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse finished" ) );
  
      return( 0 );
  }
  
  static void ssl_handshake_params_init( mbedtls_ssl_handshake_params *handshake )
  {
      memset( handshake, 0, sizeof( mbedtls_ssl_handshake_params ) );
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_1)
       mbedtls_md5_init(   &handshake->fin_md5  );
      mbedtls_sha1_init(   &handshake->fin_sha1 );
       mbedtls_md5_starts( &handshake->fin_md5  );
      mbedtls_sha1_starts( &handshake->fin_sha1 );
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
      mbedtls_sha256_init(   &handshake->fin_sha256    );
      mbedtls_sha256_starts( &handshake->fin_sha256, 0 );
  #endif
  #if defined(MBEDTLS_SHA512_C)
      mbedtls_sha512_init(   &handshake->fin_sha512    );
      mbedtls_sha512_starts( &handshake->fin_sha512, 1 );
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  
      handshake->update_checksum = ssl_update_checksum_start;
      handshake->sig_alg = MBEDTLS_SSL_HASH_SHA1;
  
  #if defined(MBEDTLS_DHM_C)
      mbedtls_dhm_init( &handshake->dhm_ctx );
  #endif
  #if defined(MBEDTLS_ECDH_C)
      mbedtls_ecdh_init( &handshake->ecdh_ctx );
  #endif
  #if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
      mbedtls_ecjpake_init( &handshake->ecjpake_ctx );
  #if defined(MBEDTLS_SSL_CLI_C)
      handshake->ecjpake_cache = NULL;
      handshake->ecjpake_cache_len = 0;
  #endif
  #endif
  
  #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
      handshake->sni_authmode = MBEDTLS_SSL_VERIFY_UNSET;
  #endif
  }
  
  static void ssl_transform_init( mbedtls_ssl_transform *transform )
  {
      memset( transform, 0, sizeof(mbedtls_ssl_transform) );
  
      mbedtls_cipher_init( &transform->cipher_ctx_enc );
      mbedtls_cipher_init( &transform->cipher_ctx_dec );
  
      mbedtls_md_init( &transform->md_ctx_enc );
      mbedtls_md_init( &transform->md_ctx_dec );
  }
  
  void mbedtls_ssl_session_init( mbedtls_ssl_session *session )
  {
      memset( session, 0, sizeof(mbedtls_ssl_session) );
  }
  
  static int ssl_handshake_init( mbedtls_ssl_context *ssl )
  {
      /* Clear old handshake information if present */
      if( ssl->transform_negotiate )
          mbedtls_ssl_transform_free( ssl->transform_negotiate );
      if( ssl->session_negotiate )
          mbedtls_ssl_session_free( ssl->session_negotiate );
      if( ssl->handshake )
          mbedtls_ssl_handshake_free( ssl->handshake );
  
      /*
       * Either the pointers are now NULL or cleared properly and can be freed.
       * Now allocate missing structures.
       */
      if( ssl->transform_negotiate == NULL )
      {
          ssl->transform_negotiate = mbedtls_calloc( 1, sizeof(mbedtls_ssl_transform) );
      }
  
      if( ssl->session_negotiate == NULL )
      {
          ssl->session_negotiate = mbedtls_calloc( 1, sizeof(mbedtls_ssl_session) );
      }
  
      if( ssl->handshake == NULL )
      {
          ssl->handshake = mbedtls_calloc( 1, sizeof(mbedtls_ssl_handshake_params) );
      }
  
      /* All pointers should exist and can be directly freed without issue */
      if( ssl->handshake == NULL ||
          ssl->transform_negotiate == NULL ||
          ssl->session_negotiate == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc() of ssl sub-contexts failed" ) );
  
          mbedtls_free( ssl->handshake );
          mbedtls_free( ssl->transform_negotiate );
          mbedtls_free( ssl->session_negotiate );
  
          ssl->handshake = NULL;
          ssl->transform_negotiate = NULL;
          ssl->session_negotiate = NULL;
  
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
      }
  
      /* Initialize structures */
      mbedtls_ssl_session_init( ssl->session_negotiate );
      ssl_transform_init( ssl->transform_negotiate );
      ssl_handshake_params_init( ssl->handshake );
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          ssl->handshake->alt_transform_out = ssl->transform_out;
  
          if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
              ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
          else
              ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
  
          ssl_set_timer( ssl, 0 );
      }
  #endif
  
      return( 0 );
  }
  
  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
  /* Dummy cookie callbacks for defaults */
  static int ssl_cookie_write_dummy( void *ctx,
                        unsigned char **p, unsigned char *end,
                        const unsigned char *cli_id, size_t cli_id_len )
  {
      ((void) ctx);
      ((void) p);
      ((void) end);
      ((void) cli_id);
      ((void) cli_id_len);
  
      return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
  }
  
  static int ssl_cookie_check_dummy( void *ctx,
                        const unsigned char *cookie, size_t cookie_len,
                        const unsigned char *cli_id, size_t cli_id_len )
  {
      ((void) ctx);
      ((void) cookie);
      ((void) cookie_len);
      ((void) cli_id);
      ((void) cli_id_len);
  
      return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
  }
  #endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY && MBEDTLS_SSL_SRV_C */
  
  /*
   * Initialize an SSL context
   */
  void mbedtls_ssl_init( mbedtls_ssl_context *ssl )
  {
      memset( ssl, 0, sizeof( mbedtls_ssl_context ) );
  }
  
  /*
   * Setup an SSL context
   */
  int mbedtls_ssl_setup( mbedtls_ssl_context *ssl,
                         const mbedtls_ssl_config *conf )
  {
      int ret;
      const size_t len = MBEDTLS_SSL_BUFFER_LEN;
  
      ssl->conf = conf;
  
      /*
       * Prepare base structures
       */
      if( ( ssl-> in_buf = mbedtls_calloc( 1, len ) ) == NULL ||
          ( ssl->out_buf = mbedtls_calloc( 1, len ) ) == NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed", len ) );
          mbedtls_free( ssl->in_buf );
          ssl->in_buf = NULL;
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
      }
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          ssl->out_hdr = ssl->out_buf;
          ssl->out_ctr = ssl->out_buf +  3;
          ssl->out_len = ssl->out_buf + 11;
          ssl->out_iv  = ssl->out_buf + 13;
          ssl->out_msg = ssl->out_buf + 13;
  
          ssl->in_hdr = ssl->in_buf;
          ssl->in_ctr = ssl->in_buf +  3;
          ssl->in_len = ssl->in_buf + 11;
          ssl->in_iv  = ssl->in_buf + 13;
          ssl->in_msg = ssl->in_buf + 13;
      }
      else
  #endif
      {
          ssl->out_ctr = ssl->out_buf;
          ssl->out_hdr = ssl->out_buf +  8;
          ssl->out_len = ssl->out_buf + 11;
          ssl->out_iv  = ssl->out_buf + 13;
          ssl->out_msg = ssl->out_buf + 13;
  
          ssl->in_ctr = ssl->in_buf;
          ssl->in_hdr = ssl->in_buf +  8;
          ssl->in_len = ssl->in_buf + 11;
          ssl->in_iv  = ssl->in_buf + 13;
          ssl->in_msg = ssl->in_buf + 13;
      }
  
      if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
          return( ret );
  
      return( 0 );
  }
  
  /*
   * Reset an initialized and used SSL context for re-use while retaining
   * all application-set variables, function pointers and data.
   *
   * If partial is non-zero, keep data in the input buffer and client ID.
   * (Use when a DTLS client reconnects from the same port.)
   */
  static int ssl_session_reset_int( mbedtls_ssl_context *ssl, int partial )
  {
      int ret;
  
      ssl->state = MBEDTLS_SSL_HELLO_REQUEST;
  
      /* Cancel any possibly running timer */
      ssl_set_timer( ssl, 0 );
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
      ssl->renego_status = MBEDTLS_SSL_INITIAL_HANDSHAKE;
      ssl->renego_records_seen = 0;
  
      ssl->verify_data_len = 0;
      memset( ssl->own_verify_data, 0, MBEDTLS_SSL_VERIFY_DATA_MAX_LEN );
      memset( ssl->peer_verify_data, 0, MBEDTLS_SSL_VERIFY_DATA_MAX_LEN );
  #endif
      ssl->secure_renegotiation = MBEDTLS_SSL_LEGACY_RENEGOTIATION;
  
      ssl->in_offt = NULL;
  
      ssl->in_msg = ssl->in_buf + 13;
      ssl->in_msgtype = 0;
      ssl->in_msglen = 0;
      if( partial == 0 )
          ssl->in_left = 0;
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      ssl->next_record_offset = 0;
      ssl->in_epoch = 0;
  #endif
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
      ssl_dtls_replay_reset( ssl );
  #endif
  
      ssl->in_hslen = 0;
      ssl->nb_zero = 0;
      ssl->record_read = 0;
  
      ssl->out_msg = ssl->out_buf + 13;
      ssl->out_msgtype = 0;
      ssl->out_msglen = 0;
      ssl->out_left = 0;
  #if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
      if( ssl->split_done != MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED )
          ssl->split_done = 0;
  #endif
  
      ssl->transform_in = NULL;
      ssl->transform_out = NULL;
  
      memset( ssl->out_buf, 0, MBEDTLS_SSL_BUFFER_LEN );
      if( partial == 0 )
          memset( ssl->in_buf, 0, MBEDTLS_SSL_BUFFER_LEN );
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_reset != NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_reset()" ) );
          if( ( ret = mbedtls_ssl_hw_record_reset( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_reset", ret );
              return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
          }
      }
  #endif
  
      if( ssl->transform )
      {
          mbedtls_ssl_transform_free( ssl->transform );
          mbedtls_free( ssl->transform );
          ssl->transform = NULL;
      }
  
      if( ssl->session )
      {
          mbedtls_ssl_session_free( ssl->session );
          mbedtls_free( ssl->session );
          ssl->session = NULL;
      }
  
  #if defined(MBEDTLS_SSL_ALPN)
      ssl->alpn_chosen = NULL;
  #endif
  
  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
      if( partial == 0 )
      {
          mbedtls_free( ssl->cli_id );
          ssl->cli_id = NULL;
          ssl->cli_id_len = 0;
      }
  #endif
  
      if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
          return( ret );
  
      return( 0 );
  }
  
  /*
   * Reset an initialized and used SSL context for re-use while retaining
   * all application-set variables, function pointers and data.
   */
  int mbedtls_ssl_session_reset( mbedtls_ssl_context *ssl )
  {
      return( ssl_session_reset_int( ssl, 0 ) );
  }
  
  /*
   * SSL set accessors
   */
  void mbedtls_ssl_conf_endpoint( mbedtls_ssl_config *conf, int endpoint )
  {
      conf->endpoint   = endpoint;
  }
  
  void mbedtls_ssl_conf_transport( mbedtls_ssl_config *conf, int transport )
  {
      conf->transport = transport;
  }
  
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
  void mbedtls_ssl_conf_dtls_anti_replay( mbedtls_ssl_config *conf, char mode )
  {
      conf->anti_replay = mode;
  }
  #endif
  
  #if defined(MBEDTLS_SSL_DTLS_BADMAC_LIMIT)
  void mbedtls_ssl_conf_dtls_badmac_limit( mbedtls_ssl_config *conf, unsigned limit )
  {
      conf->badmac_limit = limit;
  }
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
  void mbedtls_ssl_conf_handshake_timeout( mbedtls_ssl_config *conf, uint32_t min, uint32_t max )
  {
      conf->hs_timeout_min = min;
      conf->hs_timeout_max = max;
  }
  #endif
  
  void mbedtls_ssl_conf_authmode( mbedtls_ssl_config *conf, int authmode )
  {
      conf->authmode   = authmode;
  }
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
  void mbedtls_ssl_conf_verify( mbedtls_ssl_config *conf,
                       int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *),
                       void *p_vrfy )
  {
      conf->f_vrfy      = f_vrfy;
      conf->p_vrfy      = p_vrfy;
  }
  #endif /* MBEDTLS_X509_CRT_PARSE_C */
  
  void mbedtls_ssl_conf_rng( mbedtls_ssl_config *conf,
                    int (*f_rng)(void *, unsigned char *, size_t),
                    void *p_rng )
  {
      conf->f_rng      = f_rng;
      conf->p_rng      = p_rng;
  }
  
  void mbedtls_ssl_conf_dbg( mbedtls_ssl_config *conf,
                    void (*f_dbg)(void *, int, const char *, int, const char *),
                    void  *p_dbg )
  {
      conf->f_dbg      = f_dbg;
      conf->p_dbg      = p_dbg;
  }
  
  void mbedtls_ssl_set_bio( mbedtls_ssl_context *ssl,
          void *p_bio,
          mbedtls_ssl_send_t *f_send,
          mbedtls_ssl_recv_t *f_recv,
          mbedtls_ssl_recv_timeout_t *f_recv_timeout )
  {
      ssl->p_bio          = p_bio;
      ssl->f_send         = f_send;
      ssl->f_recv         = f_recv;
      ssl->f_recv_timeout = f_recv_timeout;
  }
  
  void mbedtls_ssl_conf_read_timeout( mbedtls_ssl_config *conf, uint32_t timeout )
  {
      conf->read_timeout   = timeout;
  }
  
  void mbedtls_ssl_set_timer_cb( mbedtls_ssl_context *ssl,
                                 void *p_timer,
                                 mbedtls_ssl_set_timer_t *f_set_timer,
                                 mbedtls_ssl_get_timer_t *f_get_timer )
  {
      ssl->p_timer        = p_timer;
      ssl->f_set_timer    = f_set_timer;
      ssl->f_get_timer    = f_get_timer;
  
      /* Make sure we start with no timer running */
      ssl_set_timer( ssl, 0 );
  }
  
  #if defined(MBEDTLS_SSL_SRV_C)
  void mbedtls_ssl_conf_session_cache( mbedtls_ssl_config *conf,
          void *p_cache,
          int (*f_get_cache)(void *, mbedtls_ssl_session *),
          int (*f_set_cache)(void *, const mbedtls_ssl_session *) )
  {
      conf->p_cache = p_cache;
      conf->f_get_cache = f_get_cache;
      conf->f_set_cache = f_set_cache;
  }
  #endif /* MBEDTLS_SSL_SRV_C */
  
  #if defined(MBEDTLS_SSL_CLI_C)
  int mbedtls_ssl_set_session( mbedtls_ssl_context *ssl, const mbedtls_ssl_session *session )
  {
      int ret;
  
      if( ssl == NULL ||
          session == NULL ||
          ssl->session_negotiate == NULL ||
          ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT )
      {
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      if( ( ret = ssl_session_copy( ssl->session_negotiate, session ) ) != 0 )
          return( ret );
  
      ssl->handshake->resume = 1;
  
      return( 0 );
  }
  #endif /* MBEDTLS_SSL_CLI_C */
  
  void mbedtls_ssl_conf_ciphersuites( mbedtls_ssl_config *conf,
                                     const int *ciphersuites )
  {
      conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_0] = ciphersuites;
      conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_1] = ciphersuites;
      conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_2] = ciphersuites;
      conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_3] = ciphersuites;
  }
  
  void mbedtls_ssl_conf_ciphersuites_for_version( mbedtls_ssl_config *conf,
                                         const int *ciphersuites,
                                         int major, int minor )
  {
      if( major != MBEDTLS_SSL_MAJOR_VERSION_3 )
          return;
  
      if( minor < MBEDTLS_SSL_MINOR_VERSION_0 || minor > MBEDTLS_SSL_MINOR_VERSION_3 )
          return;
  
      conf->ciphersuite_list[minor] = ciphersuites;
  }
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
  void mbedtls_ssl_conf_cert_profile( mbedtls_ssl_config *conf,
                                      const mbedtls_x509_crt_profile *profile )
  {
      conf->cert_profile = profile;
  }
  
  /* Append a new keycert entry to a (possibly empty) list */
  static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
                                  mbedtls_x509_crt *cert,
                                  mbedtls_pk_context *key )
  {
      mbedtls_ssl_key_cert *new;
  
      new = mbedtls_calloc( 1, sizeof( mbedtls_ssl_key_cert ) );
      if( new == NULL )
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
  
      new->cert = cert;
      new->key  = key;
      new->next = NULL;
  
      /* Update head is the list was null, else add to the end */
      if( *head == NULL )
      {
          *head = new;
      }
      else
      {
          mbedtls_ssl_key_cert *cur = *head;
          while( cur->next != NULL )
              cur = cur->next;
          cur->next = new;
      }
  
      return( 0 );
  }
  
  int mbedtls_ssl_conf_own_cert( mbedtls_ssl_config *conf,
                                mbedtls_x509_crt *own_cert,
                                mbedtls_pk_context *pk_key )
  {
      return( ssl_append_key_cert( &conf->key_cert, own_cert, pk_key ) );
  }
  
  void mbedtls_ssl_conf_ca_chain( mbedtls_ssl_config *conf,
                                 mbedtls_x509_crt *ca_chain,
                                 mbedtls_x509_crl *ca_crl )
  {
      conf->ca_chain   = ca_chain;
      conf->ca_crl     = ca_crl;
  }
  #endif /* MBEDTLS_X509_CRT_PARSE_C */
  
  #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
  int mbedtls_ssl_set_hs_own_cert( mbedtls_ssl_context *ssl,
                                   mbedtls_x509_crt *own_cert,
                                   mbedtls_pk_context *pk_key )
  {
      return( ssl_append_key_cert( &ssl->handshake->sni_key_cert,
                                   own_cert, pk_key ) );
  }
  
  void mbedtls_ssl_set_hs_ca_chain( mbedtls_ssl_context *ssl,
                                    mbedtls_x509_crt *ca_chain,
                                    mbedtls_x509_crl *ca_crl )
  {
      ssl->handshake->sni_ca_chain   = ca_chain;
      ssl->handshake->sni_ca_crl     = ca_crl;
  }
  
  void mbedtls_ssl_set_hs_authmode( mbedtls_ssl_context *ssl,
                                    int authmode )
  {
      ssl->handshake->sni_authmode = authmode;
  }
  #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
  
  #if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
  /*
   * Set EC J-PAKE password for current handshake
   */
  int mbedtls_ssl_set_hs_ecjpake_password( mbedtls_ssl_context *ssl,
                                           const unsigned char *pw,
                                           size_t pw_len )
  {
      mbedtls_ecjpake_role role;
  
      if( ssl->handshake == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
          role = MBEDTLS_ECJPAKE_SERVER;
      else
          role = MBEDTLS_ECJPAKE_CLIENT;
  
      return( mbedtls_ecjpake_setup( &ssl->handshake->ecjpake_ctx,
                                     role,
                                     MBEDTLS_MD_SHA256,
                                     MBEDTLS_ECP_DP_SECP256R1,
                                     pw, pw_len ) );
  }
  #endif /* MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED */
  
  #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
  int mbedtls_ssl_conf_psk( mbedtls_ssl_config *conf,
                  const unsigned char *psk, size_t psk_len,
                  const unsigned char *psk_identity, size_t psk_identity_len )
  {
      if( psk == NULL || psk_identity == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      if( psk_len > MBEDTLS_PSK_MAX_LEN )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      /* Identity len will be encoded on two bytes */
      if( ( psk_identity_len >> 16 ) != 0 ||
          psk_identity_len > MBEDTLS_SSL_MAX_CONTENT_LEN )
      {
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      if( conf->psk != NULL || conf->psk_identity != NULL )
      {
          mbedtls_free( conf->psk );
          mbedtls_free( conf->psk_identity );
          conf->psk = NULL;
          conf->psk_identity = NULL;
      }
  
      if( ( conf->psk = mbedtls_calloc( 1, psk_len ) ) == NULL ||
          ( conf->psk_identity = mbedtls_calloc( 1, psk_identity_len ) ) == NULL )
      {
          mbedtls_free( conf->psk );
          mbedtls_free( conf->psk_identity );
          conf->psk = NULL;
          conf->psk_identity = NULL;
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
      }
  
      conf->psk_len = psk_len;
      conf->psk_identity_len = psk_identity_len;
  
      memcpy( conf->psk, psk, conf->psk_len );
      memcpy( conf->psk_identity, psk_identity, conf->psk_identity_len );
  
      return( 0 );
  }
  
  int mbedtls_ssl_set_hs_psk( mbedtls_ssl_context *ssl,
                              const unsigned char *psk, size_t psk_len )
  {
      if( psk == NULL || ssl->handshake == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      if( psk_len > MBEDTLS_PSK_MAX_LEN )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      if( ssl->handshake->psk != NULL )
          mbedtls_free( ssl->handshake->psk );
  
      if( ( ssl->handshake->psk = mbedtls_calloc( 1, psk_len ) ) == NULL )
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
  
      ssl->handshake->psk_len = psk_len;
      memcpy( ssl->handshake->psk, psk, ssl->handshake->psk_len );
  
      return( 0 );
  }
  
  void mbedtls_ssl_conf_psk_cb( mbedtls_ssl_config *conf,
                       int (*f_psk)(void *, mbedtls_ssl_context *, const unsigned char *,
                       size_t),
                       void *p_psk )
  {
      conf->f_psk = f_psk;
      conf->p_psk = p_psk;
  }
  #endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
  
  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
  int mbedtls_ssl_conf_dh_param( mbedtls_ssl_config *conf, const char *dhm_P, const char *dhm_G )
  {
      int ret;
  
      if( ( ret = mbedtls_mpi_read_string( &conf->dhm_P, 16, dhm_P ) ) != 0 ||
          ( ret = mbedtls_mpi_read_string( &conf->dhm_G, 16, dhm_G ) ) != 0 )
      {
          mbedtls_mpi_free( &conf->dhm_P );
          mbedtls_mpi_free( &conf->dhm_G );
          return( ret );
      }
  
      return( 0 );
  }
  
  int mbedtls_ssl_conf_dh_param_ctx( mbedtls_ssl_config *conf, mbedtls_dhm_context *dhm_ctx )
  {
      int ret;
  
      if( ( ret = mbedtls_mpi_copy( &conf->dhm_P, &dhm_ctx->P ) ) != 0 ||
          ( ret = mbedtls_mpi_copy( &conf->dhm_G, &dhm_ctx->G ) ) != 0 )
      {
          mbedtls_mpi_free( &conf->dhm_P );
          mbedtls_mpi_free( &conf->dhm_G );
          return( ret );
      }
  
      return( 0 );
  }
  #endif /* MBEDTLS_DHM_C && MBEDTLS_SSL_SRV_C */
  
  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
  /*
   * Set the minimum length for Diffie-Hellman parameters
   */
  void mbedtls_ssl_conf_dhm_min_bitlen( mbedtls_ssl_config *conf,
                                        unsigned int bitlen )
  {
      conf->dhm_min_bitlen = bitlen;
  }
  #endif /* MBEDTLS_DHM_C && MBEDTLS_SSL_CLI_C */
  
  #if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
  /*
   * Set allowed/preferred hashes for handshake signatures
   */
  void mbedtls_ssl_conf_sig_hashes( mbedtls_ssl_config *conf,
                                    const int *hashes )
  {
      conf->sig_hashes = hashes;
  }
  #endif
  
  #if defined(MBEDTLS_ECP_C)
  /*
   * Set the allowed elliptic curves
   */
  void mbedtls_ssl_conf_curves( mbedtls_ssl_config *conf,
                               const mbedtls_ecp_group_id *curve_list )
  {
      conf->curve_list = curve_list;
  }
  #endif
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
  int mbedtls_ssl_set_hostname( mbedtls_ssl_context *ssl, const char *hostname )
  {
      size_t hostname_len;
  
      if( hostname == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      hostname_len = strlen( hostname );
  
      if( hostname_len + 1 == 0 )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      if( hostname_len > MBEDTLS_SSL_MAX_HOST_NAME_LEN )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      ssl->hostname = mbedtls_calloc( 1, hostname_len + 1 );
  
      if( ssl->hostname == NULL )
          return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
  
      memcpy( ssl->hostname, hostname, hostname_len );
  
      ssl->hostname[hostname_len] = '\0';
  
      return( 0 );
  }
  #endif
  
  #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
  void mbedtls_ssl_conf_sni( mbedtls_ssl_config *conf,
                    int (*f_sni)(void *, mbedtls_ssl_context *,
                                  const unsigned char *, size_t),
                    void *p_sni )
  {
      conf->f_sni = f_sni;
      conf->p_sni = p_sni;
  }
  #endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
  
  #if defined(MBEDTLS_SSL_ALPN)
  int mbedtls_ssl_conf_alpn_protocols( mbedtls_ssl_config *conf, const char **protos )
  {
      size_t cur_len, tot_len;
      const char **p;
  
      /*
       * "Empty strings MUST NOT be included and byte strings MUST NOT be
       * truncated". Check lengths now rather than later.
       */
      tot_len = 0;
      for( p = protos; *p != NULL; p++ )
      {
          cur_len = strlen( *p );
          tot_len += cur_len;
  
          if( cur_len == 0 || cur_len > 255 || tot_len > 65535 )
              return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      conf->alpn_list = protos;
  
      return( 0 );
  }
  
  const char *mbedtls_ssl_get_alpn_protocol( const mbedtls_ssl_context *ssl )
  {
      return( ssl->alpn_chosen );
  }
  #endif /* MBEDTLS_SSL_ALPN */
  
  void mbedtls_ssl_conf_max_version( mbedtls_ssl_config *conf, int major, int minor )
  {
      conf->max_major_ver = major;
      conf->max_minor_ver = minor;
  }
  
  void mbedtls_ssl_conf_min_version( mbedtls_ssl_config *conf, int major, int minor )
  {
      conf->min_major_ver = major;
      conf->min_minor_ver = minor;
  }
  
  #if defined(MBEDTLS_SSL_FALLBACK_SCSV) && defined(MBEDTLS_SSL_CLI_C)
  void mbedtls_ssl_conf_fallback( mbedtls_ssl_config *conf, char fallback )
  {
      conf->fallback = fallback;
  }
  #endif
  
  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
  void mbedtls_ssl_conf_encrypt_then_mac( mbedtls_ssl_config *conf, char etm )
  {
      conf->encrypt_then_mac = etm;
  }
  #endif
  
  #if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
  void mbedtls_ssl_conf_extended_master_secret( mbedtls_ssl_config *conf, char ems )
  {
      conf->extended_ms = ems;
  }
  #endif
  
  #if defined(MBEDTLS_ARC4_C)
  void mbedtls_ssl_conf_arc4_support( mbedtls_ssl_config *conf, char arc4 )
  {
      conf->arc4_disabled = arc4;
  }
  #endif
  
  #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
  int mbedtls_ssl_conf_max_frag_len( mbedtls_ssl_config *conf, unsigned char mfl_code )
  {
      if( mfl_code >= MBEDTLS_SSL_MAX_FRAG_LEN_INVALID ||
          mfl_code_to_length[mfl_code] > MBEDTLS_SSL_MAX_CONTENT_LEN )
      {
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      conf->mfl_code = mfl_code;
  
      return( 0 );
  }
  #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
  
  #if defined(MBEDTLS_SSL_TRUNCATED_HMAC)
  void mbedtls_ssl_conf_truncated_hmac( mbedtls_ssl_config *conf, int truncate )
  {
      conf->trunc_hmac = truncate;
  }
  #endif /* MBEDTLS_SSL_TRUNCATED_HMAC */
  
  #if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
  void mbedtls_ssl_conf_cbc_record_splitting( mbedtls_ssl_config *conf, char split )
  {
      conf->cbc_record_splitting = split;
  }
  #endif
  
  void mbedtls_ssl_conf_legacy_renegotiation( mbedtls_ssl_config *conf, int allow_legacy )
  {
      conf->allow_legacy_renegotiation = allow_legacy;
  }
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
  void mbedtls_ssl_conf_renegotiation( mbedtls_ssl_config *conf, int renegotiation )
  {
      conf->disable_renegotiation = renegotiation;
  }
  
  void mbedtls_ssl_conf_renegotiation_enforced( mbedtls_ssl_config *conf, int max_records )
  {
      conf->renego_max_records = max_records;
  }
  
  void mbedtls_ssl_conf_renegotiation_period( mbedtls_ssl_config *conf,
                                     const unsigned char period[8] )
  {
      memcpy( conf->renego_period, period, 8 );
  }
  #endif /* MBEDTLS_SSL_RENEGOTIATION */
  
  #if defined(MBEDTLS_SSL_SESSION_TICKETS)
  #if defined(MBEDTLS_SSL_CLI_C)
  void mbedtls_ssl_conf_session_tickets( mbedtls_ssl_config *conf, int use_tickets )
  {
      conf->session_tickets = use_tickets;
  }
  #endif
  
  #if defined(MBEDTLS_SSL_SRV_C)
  void mbedtls_ssl_conf_session_tickets_cb( mbedtls_ssl_config *conf,
          mbedtls_ssl_ticket_write_t *f_ticket_write,
          mbedtls_ssl_ticket_parse_t *f_ticket_parse,
          void *p_ticket )
  {
      conf->f_ticket_write = f_ticket_write;
      conf->f_ticket_parse = f_ticket_parse;
      conf->p_ticket       = p_ticket;
  }
  #endif
  #endif /* MBEDTLS_SSL_SESSION_TICKETS */
  
  #if defined(MBEDTLS_SSL_EXPORT_KEYS)
  void mbedtls_ssl_conf_export_keys_cb( mbedtls_ssl_config *conf,
          mbedtls_ssl_export_keys_t *f_export_keys,
          void *p_export_keys )
  {
      conf->f_export_keys = f_export_keys;
      conf->p_export_keys = p_export_keys;
  }
  #endif
  
  /*
   * SSL get accessors
   */
  size_t mbedtls_ssl_get_bytes_avail( const mbedtls_ssl_context *ssl )
  {
      return( ssl->in_offt == NULL ? 0 : ssl->in_msglen );
  }
  
  uint32_t mbedtls_ssl_get_verify_result( const mbedtls_ssl_context *ssl )
  {
      if( ssl->session != NULL )
          return( ssl->session->verify_result );
  
      if( ssl->session_negotiate != NULL )
          return( ssl->session_negotiate->verify_result );
  
      return( 0xFFFFFFFF );
  }
  
  const char *mbedtls_ssl_get_ciphersuite( const mbedtls_ssl_context *ssl )
  {
      if( ssl == NULL || ssl->session == NULL )
          return( NULL );
  
      return mbedtls_ssl_get_ciphersuite_name( ssl->session->ciphersuite );
  }
  
  const char *mbedtls_ssl_get_version( const mbedtls_ssl_context *ssl )
  {
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          switch( ssl->minor_ver )
          {
              case MBEDTLS_SSL_MINOR_VERSION_2:
                  return( "DTLSv1.0" );
  
              case MBEDTLS_SSL_MINOR_VERSION_3:
                  return( "DTLSv1.2" );
  
              default:
                  return( "unknown (DTLS)" );
          }
      }
  #endif
  
      switch( ssl->minor_ver )
      {
          case MBEDTLS_SSL_MINOR_VERSION_0:
              return( "SSLv3.0" );
  
          case MBEDTLS_SSL_MINOR_VERSION_1:
              return( "TLSv1.0" );
  
          case MBEDTLS_SSL_MINOR_VERSION_2:
              return( "TLSv1.1" );
  
          case MBEDTLS_SSL_MINOR_VERSION_3:
              return( "TLSv1.2" );
  
          default:
              return( "unknown" );
      }
  }
  
  int mbedtls_ssl_get_record_expansion( const mbedtls_ssl_context *ssl )
  {
      size_t transform_expansion;
      const mbedtls_ssl_transform *transform = ssl->transform_out;
  
  #if defined(MBEDTLS_ZLIB_SUPPORT)
      if( ssl->session_out->compression != MBEDTLS_SSL_COMPRESS_NULL )
          return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
  #endif
  
      if( transform == NULL )
          return( (int) mbedtls_ssl_hdr_len( ssl ) );
  
      switch( mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_enc ) )
      {
          case MBEDTLS_MODE_GCM:
          case MBEDTLS_MODE_CCM:
          case MBEDTLS_MODE_STREAM:
              transform_expansion = transform->minlen;
              break;
  
          case MBEDTLS_MODE_CBC:
              transform_expansion = transform->maclen
                        + mbedtls_cipher_get_block_size( &transform->cipher_ctx_enc );
              break;
  
          default:
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
              return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
      }
  
      return( (int)( mbedtls_ssl_hdr_len( ssl ) + transform_expansion ) );
  }
  
  #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
  size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl )
  {
      size_t max_len;
  
      /*
       * Assume mfl_code is correct since it was checked when set
       */
      max_len = mfl_code_to_length[ssl->conf->mfl_code];
  
      /*
       * Check if a smaller max length was negotiated
       */
      if( ssl->session_out != NULL &&
          mfl_code_to_length[ssl->session_out->mfl_code] < max_len )
      {
          max_len = mfl_code_to_length[ssl->session_out->mfl_code];
      }
  
      return max_len;
  }
  #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
  const mbedtls_x509_crt *mbedtls_ssl_get_peer_cert( const mbedtls_ssl_context *ssl )
  {
      if( ssl == NULL || ssl->session == NULL )
          return( NULL );
  
      return( ssl->session->peer_cert );
  }
  #endif /* MBEDTLS_X509_CRT_PARSE_C */
  
  #if defined(MBEDTLS_SSL_CLI_C)
  int mbedtls_ssl_get_session( const mbedtls_ssl_context *ssl, mbedtls_ssl_session *dst )
  {
      if( ssl == NULL ||
          dst == NULL ||
          ssl->session == NULL ||
          ssl->conf->endpoint != MBEDTLS_SSL_IS_CLIENT )
      {
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
      }
  
      return( ssl_session_copy( dst, ssl->session ) );
  }
  #endif /* MBEDTLS_SSL_CLI_C */
  
  /*
   * Perform a single step of the SSL handshake
   */
  int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl )
  {
      int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
  
      if( ssl == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
  #if defined(MBEDTLS_SSL_CLI_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
          ret = mbedtls_ssl_handshake_client_step( ssl );
  #endif
  #if defined(MBEDTLS_SSL_SRV_C)
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
          ret = mbedtls_ssl_handshake_server_step( ssl );
  #endif
  
      return( ret );
  }
  
  /*
   * Perform the SSL handshake
   */
  int mbedtls_ssl_handshake( mbedtls_ssl_context *ssl )
  {
      int ret = 0;
  
      if( ssl == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> handshake" ) );
  
      while( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
      {
          ret = mbedtls_ssl_handshake_step( ssl );
  
          if( ret != 0 )
              break;
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= handshake" ) );
  
      return( ret );
  }
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
  #if defined(MBEDTLS_SSL_SRV_C)
  /*
   * Write HelloRequest to request renegotiation on server
   */
  static int ssl_write_hello_request( mbedtls_ssl_context *ssl )
  {
      int ret;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write hello request" ) );
  
      ssl->out_msglen  = 4;
      ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
      ssl->out_msg[0]  = MBEDTLS_SSL_HS_HELLO_REQUEST;
  
      if( ( ret = mbedtls_ssl_write_record( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write hello request" ) );
  
      return( 0 );
  }
  #endif /* MBEDTLS_SSL_SRV_C */
  
  /*
   * Actually renegotiate current connection, triggered by either:
   * - any side: calling mbedtls_ssl_renegotiate(),
   * - client: receiving a HelloRequest during mbedtls_ssl_read(),
   * - server: receiving any handshake message on server during mbedtls_ssl_read() after
   *   the initial handshake is completed.
   * If the handshake doesn't complete due to waiting for I/O, it will continue
   * during the next calls to mbedtls_ssl_renegotiate() or mbedtls_ssl_read() respectively.
   */
  static int ssl_start_renegotiation( mbedtls_ssl_context *ssl )
  {
      int ret;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> renegotiate" ) );
  
      if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
          return( ret );
  
      /* RFC 6347 4.2.2: "[...] the HelloRequest will have message_seq = 0 and
       * the ServerHello will have message_seq = 1" */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
          ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
      {
          if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
              ssl->handshake->out_msg_seq = 1;
          else
              ssl->handshake->in_msg_seq = 1;
      }
  #endif
  
      ssl->state = MBEDTLS_SSL_HELLO_REQUEST;
      ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS;
  
      if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
          return( ret );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= renegotiate" ) );
  
      return( 0 );
  }
  
  /*
   * Renegotiate current connection on client,
   * or request renegotiation on server
   */
  int mbedtls_ssl_renegotiate( mbedtls_ssl_context *ssl )
  {
      int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
  
      if( ssl == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
  #if defined(MBEDTLS_SSL_SRV_C)
      /* On server, just send the request */
      if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
      {
          if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
              return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
          ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING;
  
          /* Did we already try/start sending HelloRequest? */
          if( ssl->out_left != 0 )
              return( mbedtls_ssl_flush_output( ssl ) );
  
          return( ssl_write_hello_request( ssl ) );
      }
  #endif /* MBEDTLS_SSL_SRV_C */
  
  #if defined(MBEDTLS_SSL_CLI_C)
      /*
       * On client, either start the renegotiation process or,
       * if already in progress, continue the handshake
       */
      if( ssl->renego_status != MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS )
      {
          if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
              return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
          if( ( ret = ssl_start_renegotiation( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "ssl_start_renegotiation", ret );
              return( ret );
          }
      }
      else
      {
          if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
              return( ret );
          }
      }
  #endif /* MBEDTLS_SSL_CLI_C */
  
      return( ret );
  }
  
  /*
   * Check record counters and renegotiate if they're above the limit.
   */
  static int ssl_check_ctr_renegotiate( mbedtls_ssl_context *ssl )
  {
      if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER ||
          ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING ||
          ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED )
      {
          return( 0 );
      }
  
      if( memcmp( ssl->in_ctr,  ssl->conf->renego_period, 8 ) <= 0 &&
          memcmp( ssl->out_ctr, ssl->conf->renego_period, 8 ) <= 0 )
      {
          return( 0 );
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 1, ( "record counter limit reached: renegotiate" ) );
      return( mbedtls_ssl_renegotiate( ssl ) );
  }
  #endif /* MBEDTLS_SSL_RENEGOTIATION */
  
  /*
   * Receive application data decrypted from the SSL layer
   */
  int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
  {
      int ret, record_read = 0;
      size_t n;
  
      if( ssl == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read" ) );
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
              return( ret );
  
          if( ssl->handshake != NULL &&
              ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
          {
              if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
                  return( ret );
          }
      }
  #endif
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
      if( ( ret = ssl_check_ctr_renegotiate( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
          return( ret );
      }
  #endif
  
      if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
      {
          ret = mbedtls_ssl_handshake( ssl );
          if( ret == MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO )
          {
              record_read = 1;
          }
          else if( ret != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
              return( ret );
          }
      }
  
      if( ssl->in_offt == NULL )
      {
          /* Start timer if not already running */
          if( ssl->f_get_timer != NULL &&
              ssl->f_get_timer( ssl->p_timer ) == -1 )
          {
              ssl_set_timer( ssl, ssl->conf->read_timeout );
          }
  
          if( ! record_read )
          {
              if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
              {
                  if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
                      return( 0 );
  
                  MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
                  return( ret );
              }
          }
  
          if( ssl->in_msglen  == 0 &&
              ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA )
          {
              /*
               * OpenSSL sends empty messages to randomize the IV
               */
              if( ( ret = mbedtls_ssl_read_record( ssl ) ) != 0 )
              {
                  if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
                      return( 0 );
  
                  MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
                  return( ret );
              }
          }
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
          if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "received handshake message" ) );
  
  #if defined(MBEDTLS_SSL_CLI_C)
              if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
                  ( ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_REQUEST ||
                    ssl->in_hslen != mbedtls_ssl_hs_hdr_len( ssl ) ) )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not HelloRequest)" ) );
  
                  /* With DTLS, drop the packet (probably from last handshake) */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
                  if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
                      return( MBEDTLS_ERR_SSL_WANT_READ );
  #endif
                  return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
              }
  
              if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
                  ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not ClientHello)" ) );
  
                  /* With DTLS, drop the packet (probably from last handshake) */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
                  if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
                      return( MBEDTLS_ERR_SSL_WANT_READ );
  #endif
                  return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
              }
  #endif
  
              if( ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED ||
                  ( ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
                    ssl->conf->allow_legacy_renegotiation ==
                                                  MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION ) )
              {
                  MBEDTLS_SSL_DEBUG_MSG( 3, ( "refusing renegotiation, sending alert" ) );
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3)
                  if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_0 )
                  {
                      /*
                       * SSLv3 does not have a "no_renegotiation" alert
                       */
                      if( ( ret = mbedtls_ssl_send_fatal_handshake_failure( ssl ) ) != 0 )
                          return( ret );
                  }
                  else
  #endif /* MBEDTLS_SSL_PROTO_SSL3 */
  #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_2)
                  if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
                  {
                      if( ( ret = mbedtls_ssl_send_alert_message( ssl,
                                      MBEDTLS_SSL_ALERT_LEVEL_WARNING,
                                      MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION ) ) != 0 )
                      {
                          return( ret );
                      }
                  }
                  else
  #endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 ||
            MBEDTLS_SSL_PROTO_TLS1_2 */
                  {
                      MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
                      return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
                  }
              }
              else
              {
                  /* DTLS clients need to know renego is server-initiated */
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
                  if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
                      ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
                  {
                      ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING;
                  }
  #endif
                  ret = ssl_start_renegotiation( ssl );
                  if( ret == MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO )
                  {
                      record_read = 1;
                  }
                  else if( ret != 0 )
                  {
                      MBEDTLS_SSL_DEBUG_RET( 1, "ssl_start_renegotiation", ret );
                      return( ret );
                  }
              }
  
              /* If a non-handshake record was read during renego, fallthrough,
               * else tell the user they should call mbedtls_ssl_read() again */
              if( ! record_read )
                  return( MBEDTLS_ERR_SSL_WANT_READ );
          }
          else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
          {
  
              if( ssl->conf->renego_max_records >= 0 )
              {
                  if( ++ssl->renego_records_seen > ssl->conf->renego_max_records )
                  {
                      MBEDTLS_SSL_DEBUG_MSG( 1, ( "renegotiation requested, "
                                          "but not honored by client" ) );
                      return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
                  }
              }
          }
  #endif /* MBEDTLS_SSL_RENEGOTIATION */
  
          /* Fatal and closure alerts handled by mbedtls_ssl_read_record() */
          if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
          {
              MBEDTLS_SSL_DEBUG_MSG( 2, ( "ignoring non-fatal non-closure alert" ) );
              return( MBEDTLS_ERR_SSL_WANT_READ );
          }
  
          if( ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad application data message" ) );
              return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
          }
  
          ssl->in_offt = ssl->in_msg;
  
          /* We're going to return something now, cancel timer,
           * except if handshake (renegotiation) is in progress */
          if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
              ssl_set_timer( ssl, 0 );
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
          /* If we requested renego but received AppData, resend HelloRequest.
           * Do it now, after setting in_offt, to avoid taking this branch
           * again if ssl_write_hello_request() returns WANT_WRITE */
  #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
          if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
              ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
          {
              if( ( ret = ssl_resend_hello_request( ssl ) ) != 0 )
              {
                  MBEDTLS_SSL_DEBUG_RET( 1, "ssl_resend_hello_request", ret );
                  return( ret );
              }
          }
  #endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
  #endif
      }
  
      n = ( len < ssl->in_msglen )
          ? len : ssl->in_msglen;
  
      memcpy( buf, ssl->in_offt, n );
      ssl->in_msglen -= n;
  
      if( ssl->in_msglen == 0 )
          /* all bytes consumed  */
          ssl->in_offt = NULL;
      else
          /* more data available */
          ssl->in_offt += n;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read" ) );
  
      return( (int) n );
  }
  
  /*
   * Send application data to be encrypted by the SSL layer,
   * taking care of max fragment length and buffer size
   */
  static int ssl_write_real( mbedtls_ssl_context *ssl,
                             const unsigned char *buf, size_t len )
  {
      int ret;
  #if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
      size_t max_len = mbedtls_ssl_get_max_frag_len( ssl );
  
      if( len > max_len )
      {
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
          if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
          {
              MBEDTLS_SSL_DEBUG_MSG( 1, ( "fragment larger than the (negotiated) "
                                  "maximum fragment length: %d > %d",
                                  len, max_len ) );
              return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
          }
          else
  #endif
              len = max_len;
      }
  #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
  
      if( ssl->out_left != 0 )
      {
          if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
              return( ret );
          }
      }
      else
      {
          ssl->out_msglen  = len;
          ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA;
          memcpy( ssl->out_msg, buf, len );
  
          if( ( ret = mbedtls_ssl_write_record( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
              return( ret );
          }
      }
  
      return( (int) len );
  }
  
  /*
   * Write application data, doing 1/n-1 splitting if necessary.
   *
   * With non-blocking I/O, ssl_write_real() may return WANT_WRITE,
   * then the caller will call us again with the same arguments, so
   * remember wether we already did the split or not.
   */
  #if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
  static int ssl_write_split( mbedtls_ssl_context *ssl,
                              const unsigned char *buf, size_t len )
  {
      int ret;
  
      if( ssl->conf->cbc_record_splitting ==
              MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED ||
          len <= 1 ||
          ssl->minor_ver > MBEDTLS_SSL_MINOR_VERSION_1 ||
          mbedtls_cipher_get_cipher_mode( &ssl->transform_out->cipher_ctx_enc )
                                  != MBEDTLS_MODE_CBC )
      {
          return( ssl_write_real( ssl, buf, len ) );
      }
  
      if( ssl->split_done == 0 )
      {
          if( ( ret = ssl_write_real( ssl, buf, 1 ) ) <= 0 )
              return( ret );
          ssl->split_done = 1;
      }
  
      if( ( ret = ssl_write_real( ssl, buf + 1, len - 1 ) ) <= 0 )
          return( ret );
      ssl->split_done = 0;
  
      return( ret + 1 );
  }
  #endif /* MBEDTLS_SSL_CBC_RECORD_SPLITTING */
  
  /*
   * Write application data (public-facing wrapper)
   */
  int mbedtls_ssl_write( mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len )
  {
      int ret;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write" ) );
  
      if( ssl == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
      if( ( ret = ssl_check_ctr_renegotiate( ssl ) ) != 0 )
      {
          MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
          return( ret );
      }
  #endif
  
      if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
      {
          if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
              return( ret );
          }
      }
  
  #if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
      ret = ssl_write_split( ssl, buf, len );
  #else
      ret = ssl_write_real( ssl, buf, len );
  #endif
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write" ) );
  
      return( ret );
  }
  
  /*
   * Notify the peer that the connection is being closed
   */
  int mbedtls_ssl_close_notify( mbedtls_ssl_context *ssl )
  {
      int ret;
  
      if( ssl == NULL || ssl->conf == NULL )
          return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write close notify" ) );
  
      if( ssl->out_left != 0 )
          return( mbedtls_ssl_flush_output( ssl ) );
  
      if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
      {
          if( ( ret = mbedtls_ssl_send_alert_message( ssl,
                          MBEDTLS_SSL_ALERT_LEVEL_WARNING,
                          MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY ) ) != 0 )
          {
              MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_send_alert_message", ret );
              return( ret );
          }
      }
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write close notify" ) );
  
      return( 0 );
  }
  
  void mbedtls_ssl_transform_free( mbedtls_ssl_transform *transform )
  {
      if( transform == NULL )
          return;
  
  #if defined(MBEDTLS_ZLIB_SUPPORT)
      deflateEnd( &transform->ctx_deflate );
      inflateEnd( &transform->ctx_inflate );
  #endif
  
      mbedtls_cipher_free( &transform->cipher_ctx_enc );
      mbedtls_cipher_free( &transform->cipher_ctx_dec );
  
      mbedtls_md_free( &transform->md_ctx_enc );
      mbedtls_md_free( &transform->md_ctx_dec );
  
      mbedtls_zeroize( transform, sizeof( mbedtls_ssl_transform ) );
  }
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
  static void ssl_key_cert_free( mbedtls_ssl_key_cert *key_cert )
  {
      mbedtls_ssl_key_cert *cur = key_cert, *next;
  
      while( cur != NULL )
      {
          next = cur->next;
          mbedtls_free( cur );
          cur = next;
      }
  }
  #endif /* MBEDTLS_X509_CRT_PARSE_C */
  
  void mbedtls_ssl_handshake_free( mbedtls_ssl_handshake_params *handshake )
  {
      if( handshake == NULL )
          return;
  
  #if defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) || \
      defined(MBEDTLS_SSL_PROTO_TLS1_1)
      mbedtls_md5_free(    &handshake->fin_md5  );
      mbedtls_sha1_free(   &handshake->fin_sha1 );
  #endif
  #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
  #if defined(MBEDTLS_SHA256_C)
      mbedtls_sha256_free(   &handshake->fin_sha256    );
  #endif
  #if defined(MBEDTLS_SHA512_C)
      mbedtls_sha512_free(   &handshake->fin_sha512    );
  #endif
  #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
  
  #if defined(MBEDTLS_DHM_C)
      mbedtls_dhm_free( &handshake->dhm_ctx );
  #endif
  #if defined(MBEDTLS_ECDH_C)
      mbedtls_ecdh_free( &handshake->ecdh_ctx );
  #endif
  #if defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
      mbedtls_ecjpake_free( &handshake->ecjpake_ctx );
  #if defined(MBEDTLS_SSL_CLI_C)
      mbedtls_free( handshake->ecjpake_cache );
      handshake->ecjpake_cache = NULL;
      handshake->ecjpake_cache_len = 0;
  #endif
  #endif
  
  #if defined(MBEDTLS_ECDH_C) || defined(MBEDTLS_ECDSA_C) || \
      defined(MBEDTLS_KEY_EXCHANGE_ECJPAKE_ENABLED)
      /* explicit void pointer cast for buggy MS compiler */
      mbedtls_free( (void *) handshake->curves );
  #endif
  
  #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
      if( handshake->psk != NULL )
      {
          mbedtls_zeroize( handshake->psk, handshake->psk_len );
          mbedtls_free( handshake->psk );
      }
  #endif
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C) && \
      defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
      /*
       * Free only the linked list wrapper, not the keys themselves
       * since the belong to the SNI callback
       */
      if( handshake->sni_key_cert != NULL )
      {
          mbedtls_ssl_key_cert *cur = handshake->sni_key_cert, *next;
  
          while( cur != NULL )
          {
              next = cur->next;
              mbedtls_free( cur );
              cur = next;
          }
      }
  #endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_SERVER_NAME_INDICATION */
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      mbedtls_free( handshake->verify_cookie );
      mbedtls_free( handshake->hs_msg );
      ssl_flight_free( handshake->flight );
  #endif
  
      mbedtls_zeroize( handshake, sizeof( mbedtls_ssl_handshake_params ) );
  }
  
  void mbedtls_ssl_session_free( mbedtls_ssl_session *session )
  {
      if( session == NULL )
          return;
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
      if( session->peer_cert != NULL )
      {
          mbedtls_x509_crt_free( session->peer_cert );
          mbedtls_free( session->peer_cert );
      }
  #endif
  
  #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
      mbedtls_free( session->ticket );
  #endif
  
      mbedtls_zeroize( session, sizeof( mbedtls_ssl_session ) );
  }
  
  /*
   * Free an SSL context
   */
  void mbedtls_ssl_free( mbedtls_ssl_context *ssl )
  {
      if( ssl == NULL )
          return;
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> free" ) );
  
      if( ssl->out_buf != NULL )
      {
          mbedtls_zeroize( ssl->out_buf, MBEDTLS_SSL_BUFFER_LEN );
          mbedtls_free( ssl->out_buf );
      }
  
      if( ssl->in_buf != NULL )
      {
          mbedtls_zeroize( ssl->in_buf, MBEDTLS_SSL_BUFFER_LEN );
          mbedtls_free( ssl->in_buf );
      }
  
  #if defined(MBEDTLS_ZLIB_SUPPORT)
      if( ssl->compress_buf != NULL )
      {
          mbedtls_zeroize( ssl->compress_buf, MBEDTLS_SSL_BUFFER_LEN );
          mbedtls_free( ssl->compress_buf );
      }
  #endif
  
      if( ssl->transform )
      {
          mbedtls_ssl_transform_free( ssl->transform );
          mbedtls_free( ssl->transform );
      }
  
      if( ssl->handshake )
      {
          mbedtls_ssl_handshake_free( ssl->handshake );
          mbedtls_ssl_transform_free( ssl->transform_negotiate );
          mbedtls_ssl_session_free( ssl->session_negotiate );
  
          mbedtls_free( ssl->handshake );
          mbedtls_free( ssl->transform_negotiate );
          mbedtls_free( ssl->session_negotiate );
      }
  
      if( ssl->session )
      {
          mbedtls_ssl_session_free( ssl->session );
          mbedtls_free( ssl->session );
      }
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
      if( ssl->hostname != NULL )
      {
          mbedtls_zeroize( ssl->hostname, strlen( ssl->hostname ) );
          mbedtls_free( ssl->hostname );
      }
  #endif
  
  #if defined(MBEDTLS_SSL_HW_RECORD_ACCEL)
      if( mbedtls_ssl_hw_record_finish != NULL )
      {
          MBEDTLS_SSL_DEBUG_MSG( 2, ( "going for mbedtls_ssl_hw_record_finish()" ) );
          mbedtls_ssl_hw_record_finish( ssl );
      }
  #endif
  
  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
      mbedtls_free( ssl->cli_id );
  #endif
  
      MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= free" ) );
  
      /* Actually clear after last debug message */
      mbedtls_zeroize( ssl, sizeof( mbedtls_ssl_context ) );
  }
  
  /*
   * Initialze mbedtls_ssl_config
   */
  void mbedtls_ssl_config_init( mbedtls_ssl_config *conf )
  {
      memset( conf, 0, sizeof( mbedtls_ssl_config ) );
  }
  
  #if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
  static int ssl_preset_default_hashes[] = {
  #if defined(MBEDTLS_SHA512_C)
      MBEDTLS_MD_SHA512,
      MBEDTLS_MD_SHA384,
  #endif
  #if defined(MBEDTLS_SHA256_C)
      MBEDTLS_MD_SHA256,
      MBEDTLS_MD_SHA224,
  #endif
  #if defined(MBEDTLS_SHA1_C)
      MBEDTLS_MD_SHA1,
  #endif
      MBEDTLS_MD_NONE
  };
  #endif
  
  static int ssl_preset_suiteb_ciphersuites[] = {
      MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
      MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
      0
  };
  
  #if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
  static int ssl_preset_suiteb_hashes[] = {
      MBEDTLS_MD_SHA256,
      MBEDTLS_MD_SHA384,
      MBEDTLS_MD_NONE
  };
  #endif
  
  #if defined(MBEDTLS_ECP_C)
  static mbedtls_ecp_group_id ssl_preset_suiteb_curves[] = {
      MBEDTLS_ECP_DP_SECP256R1,
      MBEDTLS_ECP_DP_SECP384R1,
      MBEDTLS_ECP_DP_NONE
  };
  #endif
  
  /*
   * Load default in mbedtls_ssl_config
   */
  int mbedtls_ssl_config_defaults( mbedtls_ssl_config *conf,
                                   int endpoint, int transport, int preset )
  {
  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
      int ret;
  #endif
  
      /* Use the functions here so that they are covered in tests,
       * but otherwise access member directly for efficiency */
      mbedtls_ssl_conf_endpoint( conf, endpoint );
      mbedtls_ssl_conf_transport( conf, transport );
  
      /*
       * Things that are common to all presets
       */
  #if defined(MBEDTLS_SSL_CLI_C)
      if( endpoint == MBEDTLS_SSL_IS_CLIENT )
      {
          conf->authmode = MBEDTLS_SSL_VERIFY_REQUIRED;
  #if defined(MBEDTLS_SSL_SESSION_TICKETS)
          conf->session_tickets = MBEDTLS_SSL_SESSION_TICKETS_ENABLED;
  #endif
      }
  #endif
  
  #if defined(MBEDTLS_ARC4_C)
      conf->arc4_disabled = MBEDTLS_SSL_ARC4_DISABLED;
  #endif
  
  #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
      conf->encrypt_then_mac = MBEDTLS_SSL_ETM_ENABLED;
  #endif
  
  #if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
      conf->extended_ms = MBEDTLS_SSL_EXTENDED_MS_ENABLED;
  #endif
  
  #if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
      conf->cbc_record_splitting = MBEDTLS_SSL_CBC_RECORD_SPLITTING_ENABLED;
  #endif
  
  #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
      conf->f_cookie_write = ssl_cookie_write_dummy;
      conf->f_cookie_check = ssl_cookie_check_dummy;
  #endif
  
  #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
      conf->anti_replay = MBEDTLS_SSL_ANTI_REPLAY_ENABLED;
  #endif
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      conf->hs_timeout_min = MBEDTLS_SSL_DTLS_TIMEOUT_DFL_MIN;
      conf->hs_timeout_max = MBEDTLS_SSL_DTLS_TIMEOUT_DFL_MAX;
  #endif
  
  #if defined(MBEDTLS_SSL_RENEGOTIATION)
      conf->renego_max_records = MBEDTLS_SSL_RENEGO_MAX_RECORDS_DEFAULT;
      memset( conf->renego_period, 0xFF, 7 );
      conf->renego_period[7] = 0x00;
  #endif
  
  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_SRV_C)
              if( endpoint == MBEDTLS_SSL_IS_SERVER )
              {
                  if( ( ret = mbedtls_ssl_conf_dh_param( conf,
                                  MBEDTLS_DHM_RFC5114_MODP_2048_P,
                                  MBEDTLS_DHM_RFC5114_MODP_2048_G ) ) != 0 )
                  {
                      return( ret );
                  }
              }
  #endif
  
      /*
       * Preset-specific defaults
       */
      switch( preset )
      {
          /*
           * NSA Suite B
           */
          case MBEDTLS_SSL_PRESET_SUITEB:
              conf->min_major_ver = MBEDTLS_SSL_MAJOR_VERSION_3;
              conf->min_minor_ver = MBEDTLS_SSL_MINOR_VERSION_3; /* TLS 1.2 */
              conf->max_major_ver = MBEDTLS_SSL_MAX_MAJOR_VERSION;
              conf->max_minor_ver = MBEDTLS_SSL_MAX_MINOR_VERSION;
  
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_0] =
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_1] =
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_2] =
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_3] =
                                     ssl_preset_suiteb_ciphersuites;
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
              conf->cert_profile = &mbedtls_x509_crt_profile_suiteb;
  #endif
  
  #if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
              conf->sig_hashes = ssl_preset_suiteb_hashes;
  #endif
  
  #if defined(MBEDTLS_ECP_C)
              conf->curve_list = ssl_preset_suiteb_curves;
  #endif
              break;
  
          /*
           * Default
           */
          default:
              conf->min_major_ver = MBEDTLS_SSL_MAJOR_VERSION_3;
              conf->min_minor_ver = MBEDTLS_SSL_MINOR_VERSION_1; /* TLS 1.0 */
              conf->max_major_ver = MBEDTLS_SSL_MAX_MAJOR_VERSION;
              conf->max_minor_ver = MBEDTLS_SSL_MAX_MINOR_VERSION;
  
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
              if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
                  conf->min_minor_ver = MBEDTLS_SSL_MINOR_VERSION_2;
  #endif
  
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_0] =
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_1] =
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_2] =
              conf->ciphersuite_list[MBEDTLS_SSL_MINOR_VERSION_3] =
                                     mbedtls_ssl_list_ciphersuites();
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
              conf->cert_profile = &mbedtls_x509_crt_profile_default;
  #endif
  
  #if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
              conf->sig_hashes = ssl_preset_default_hashes;
  #endif
  
  #if defined(MBEDTLS_ECP_C)
              conf->curve_list = mbedtls_ecp_grp_id_list();
  #endif
  
  #if defined(MBEDTLS_DHM_C) && defined(MBEDTLS_SSL_CLI_C)
              conf->dhm_min_bitlen = 1024;
  #endif
      }
  
      return( 0 );
  }
  
  /*
   * Free mbedtls_ssl_config
   */
  void mbedtls_ssl_config_free( mbedtls_ssl_config *conf )
  {
  #if defined(MBEDTLS_DHM_C)
      mbedtls_mpi_free( &conf->dhm_P );
      mbedtls_mpi_free( &conf->dhm_G );
  #endif
  
  #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
      if( conf->psk != NULL )
      {
          mbedtls_zeroize( conf->psk, conf->psk_len );
          mbedtls_zeroize( conf->psk_identity, conf->psk_identity_len );
          mbedtls_free( conf->psk );
          mbedtls_free( conf->psk_identity );
          conf->psk_len = 0;
          conf->psk_identity_len = 0;
      }
  #endif
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
      ssl_key_cert_free( conf->key_cert );
  #endif
  
      mbedtls_zeroize( conf, sizeof( mbedtls_ssl_config ) );
  }
  
  #if defined(MBEDTLS_PK_C) && \
      ( defined(MBEDTLS_RSA_C) || defined(MBEDTLS_ECDSA_C) )
  /*
   * Convert between MBEDTLS_PK_XXX and SSL_SIG_XXX
   */
  unsigned char mbedtls_ssl_sig_from_pk( mbedtls_pk_context *pk )
  {
  #if defined(MBEDTLS_RSA_C)
      if( mbedtls_pk_can_do( pk, MBEDTLS_PK_RSA ) )
          return( MBEDTLS_SSL_SIG_RSA );
  #endif
  #if defined(MBEDTLS_ECDSA_C)
      if( mbedtls_pk_can_do( pk, MBEDTLS_PK_ECDSA ) )
          return( MBEDTLS_SSL_SIG_ECDSA );
  #endif
      return( MBEDTLS_SSL_SIG_ANON );
  }
  
  mbedtls_pk_type_t mbedtls_ssl_pk_alg_from_sig( unsigned char sig )
  {
      switch( sig )
      {
  #if defined(MBEDTLS_RSA_C)
          case MBEDTLS_SSL_SIG_RSA:
              return( MBEDTLS_PK_RSA );
  #endif
  #if defined(MBEDTLS_ECDSA_C)
          case MBEDTLS_SSL_SIG_ECDSA:
              return( MBEDTLS_PK_ECDSA );
  #endif
          default:
              return( MBEDTLS_PK_NONE );
      }
  }
  #endif /* MBEDTLS_PK_C && ( MBEDTLS_RSA_C || MBEDTLS_ECDSA_C ) */
  
  /*
   * Convert from MBEDTLS_SSL_HASH_XXX to MBEDTLS_MD_XXX
   */
  mbedtls_md_type_t mbedtls_ssl_md_alg_from_hash( unsigned char hash )
  {
      switch( hash )
      {
  #if defined(MBEDTLS_MD5_C)
          case MBEDTLS_SSL_HASH_MD5:
              return( MBEDTLS_MD_MD5 );
  #endif
  #if defined(MBEDTLS_SHA1_C)
          case MBEDTLS_SSL_HASH_SHA1:
              return( MBEDTLS_MD_SHA1 );
  #endif
  #if defined(MBEDTLS_SHA256_C)
          case MBEDTLS_SSL_HASH_SHA224:
              return( MBEDTLS_MD_SHA224 );
          case MBEDTLS_SSL_HASH_SHA256:
              return( MBEDTLS_MD_SHA256 );
  #endif
  #if defined(MBEDTLS_SHA512_C)
          case MBEDTLS_SSL_HASH_SHA384:
              return( MBEDTLS_MD_SHA384 );
          case MBEDTLS_SSL_HASH_SHA512:
              return( MBEDTLS_MD_SHA512 );
  #endif
          default:
              return( MBEDTLS_MD_NONE );
      }
  }
  
  /*
   * Convert from MBEDTLS_MD_XXX to MBEDTLS_SSL_HASH_XXX
   */
  unsigned char mbedtls_ssl_hash_from_md_alg( int md )
  {
      switch( md )
      {
  #if defined(MBEDTLS_MD5_C)
          case MBEDTLS_MD_MD5:
              return( MBEDTLS_SSL_HASH_MD5 );
  #endif
  #if defined(MBEDTLS_SHA1_C)
          case MBEDTLS_MD_SHA1:
              return( MBEDTLS_SSL_HASH_SHA1 );
  #endif
  #if defined(MBEDTLS_SHA256_C)
          case MBEDTLS_MD_SHA224:
              return( MBEDTLS_SSL_HASH_SHA224 );
          case MBEDTLS_MD_SHA256:
              return( MBEDTLS_SSL_HASH_SHA256 );
  #endif
  #if defined(MBEDTLS_SHA512_C)
          case MBEDTLS_MD_SHA384:
              return( MBEDTLS_SSL_HASH_SHA384 );
          case MBEDTLS_MD_SHA512:
              return( MBEDTLS_SSL_HASH_SHA512 );
  #endif
          default:
              return( MBEDTLS_SSL_HASH_NONE );
      }
  }
  
  #if defined(MBEDTLS_ECP_C)
  /*
   * Check if a curve proposed by the peer is in our list.
   * Return 0 if we're willing to use it, -1 otherwise.
   */
  int mbedtls_ssl_check_curve( const mbedtls_ssl_context *ssl, mbedtls_ecp_group_id grp_id )
  {
      const mbedtls_ecp_group_id *gid;
  
      if( ssl->conf->curve_list == NULL )
          return( -1 );
  
      for( gid = ssl->conf->curve_list; *gid != MBEDTLS_ECP_DP_NONE; gid++ )
          if( *gid == grp_id )
              return( 0 );
  
      return( -1 );
  }
  #endif /* MBEDTLS_ECP_C */
  
  #if defined(MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED)
  /*
   * Check if a hash proposed by the peer is in our list.
   * Return 0 if we're willing to use it, -1 otherwise.
   */
  int mbedtls_ssl_check_sig_hash( const mbedtls_ssl_context *ssl,
                                  mbedtls_md_type_t md )
  {
      const int *cur;
  
      if( ssl->conf->sig_hashes == NULL )
          return( -1 );
  
      for( cur = ssl->conf->sig_hashes; *cur != MBEDTLS_MD_NONE; cur++ )
          if( *cur == (int) md )
              return( 0 );
  
      return( -1 );
  }
  #endif /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
  
  #if defined(MBEDTLS_X509_CRT_PARSE_C)
  int mbedtls_ssl_check_cert_usage( const mbedtls_x509_crt *cert,
                            const mbedtls_ssl_ciphersuite_t *ciphersuite,
                            int cert_endpoint,
                            uint32_t *flags )
  {
      int ret = 0;
  #if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
      int usage = 0;
  #endif
  #if defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
      const char *ext_oid;
      size_t ext_len;
  #endif
  
  #if !defined(MBEDTLS_X509_CHECK_KEY_USAGE) &&          \
      !defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
      ((void) cert);
      ((void) cert_endpoint);
      ((void) flags);
  #endif
  
  #if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
      if( cert_endpoint == MBEDTLS_SSL_IS_SERVER )
      {
          /* Server part of the key exchange */
          switch( ciphersuite->key_exchange )
          {
              case MBEDTLS_KEY_EXCHANGE_RSA:
              case MBEDTLS_KEY_EXCHANGE_RSA_PSK:
                  usage = MBEDTLS_X509_KU_KEY_ENCIPHERMENT;
                  break;
  
              case MBEDTLS_KEY_EXCHANGE_DHE_RSA:
              case MBEDTLS_KEY_EXCHANGE_ECDHE_RSA:
              case MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA:
                  usage = MBEDTLS_X509_KU_DIGITAL_SIGNATURE;
                  break;
  
              case MBEDTLS_KEY_EXCHANGE_ECDH_RSA:
              case MBEDTLS_KEY_EXCHANGE_ECDH_ECDSA:
                  usage = MBEDTLS_X509_KU_KEY_AGREEMENT;
                  break;
  
              /* Don't use default: we want warnings when adding new values */
              case MBEDTLS_KEY_EXCHANGE_NONE:
              case MBEDTLS_KEY_EXCHANGE_PSK:
              case MBEDTLS_KEY_EXCHANGE_DHE_PSK:
              case MBEDTLS_KEY_EXCHANGE_ECDHE_PSK:
              case MBEDTLS_KEY_EXCHANGE_ECJPAKE:
                  usage = 0;
          }
      }
      else
      {
          /* Client auth: we only implement rsa_sign and mbedtls_ecdsa_sign for now */
          usage = MBEDTLS_X509_KU_DIGITAL_SIGNATURE;
      }
  
      if( mbedtls_x509_crt_check_key_usage( cert, usage ) != 0 )
      {
          *flags |= MBEDTLS_X509_BADCERT_KEY_USAGE;
          ret = -1;
      }
  #else
      ((void) ciphersuite);
  #endif /* MBEDTLS_X509_CHECK_KEY_USAGE */
  
  #if defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
      if( cert_endpoint == MBEDTLS_SSL_IS_SERVER )
      {
          ext_oid = MBEDTLS_OID_SERVER_AUTH;
          ext_len = MBEDTLS_OID_SIZE( MBEDTLS_OID_SERVER_AUTH );
      }
      else
      {
          ext_oid = MBEDTLS_OID_CLIENT_AUTH;
          ext_len = MBEDTLS_OID_SIZE( MBEDTLS_OID_CLIENT_AUTH );
      }
  
      if( mbedtls_x509_crt_check_extended_key_usage( cert, ext_oid, ext_len ) != 0 )
      {
          *flags |= MBEDTLS_X509_BADCERT_EXT_KEY_USAGE;
          ret = -1;
      }
  #endif /* MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE */
  
      return( ret );
  }
  #endif /* MBEDTLS_X509_CRT_PARSE_C */
  
  /*
   * Convert version numbers to/from wire format
   * and, for DTLS, to/from TLS equivalent.
   *
   * For TLS this is the identity.
   * For DTLS, use one complement (v -> 255 - v, and then map as follows:
   * 1.0 <-> 3.2      (DTLS 1.0 is based on TLS 1.1)
   * 1.x <-> 3.x+1    for x != 0 (DTLS 1.2 based on TLS 1.2)
   */
  void mbedtls_ssl_write_version( int major, int minor, int transport,
                          unsigned char ver[2] )
  {
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          if( minor == MBEDTLS_SSL_MINOR_VERSION_2 )
              --minor; /* DTLS 1.0 stored as TLS 1.1 internally */
  
          ver[0] = (unsigned char)( 255 - ( major - 2 ) );
          ver[1] = (unsigned char)( 255 - ( minor - 1 ) );
      }
      else
  #else
      ((void) transport);
  #endif
      {
          ver[0] = (unsigned char) major;
          ver[1] = (unsigned char) minor;
      }
  }
  
  void mbedtls_ssl_read_version( int *major, int *minor, int transport,
                         const unsigned char ver[2] )
  {
  #if defined(MBEDTLS_SSL_PROTO_DTLS)
      if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
      {
          *major = 255 - ver[0] + 2;
          *minor = 255 - ver[1] + 1;
  
          if( *minor == MBEDTLS_SSL_MINOR_VERSION_1 )
              ++*minor; /* DTLS 1.0 stored as TLS 1.1 internally */
      }
      else
  #else
      ((void) transport);
  #endif
      {
          *major = ver[0];
          *minor = ver[1];
      }
  }
  
  #endif /* MBEDTLS_SSL_TLS_C */
  