text: /* ssl/t1_lib.c */
  /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   * All rights reserved.
   *
   * This package is an SSL implementation written
   * by Eric Young (eay@cryptsoft.com).
   * The implementation was written so as to conform with Netscapes SSL.
   *
   * This library is free for commercial and non-commercial use as long as
   * the following conditions are aheared to.  The following conditions
   * apply to all code found in this distribution, be it the RC4, RSA,
   * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
   * included with this distribution is covered by the same copyright terms
   * except that the holder is Tim Hudson (tjh@cryptsoft.com).
   *
   * Copyright remains Eric Young's, and as such any Copyright notices in
   * the code are not to be removed.
   * If this package is used in a product, Eric Young should be given attribution
   * as the author of the parts of the library used.
   * This can be in the form of a textual message at program startup or
   * in documentation (online or textual) provided with the package.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *    "This product includes cryptographic software written by
   *     Eric Young (eay@cryptsoft.com)"
   *    The word 'cryptographic' can be left out if the rouines from the library
   *    being used are not cryptographic related :-).
   * 4. If you include any Windows specific code (or a derivative thereof) from
   *    the apps directory (application code) you must include an acknowledgement:
   *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
   *
   * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   * The licence and distribution terms for any publically available version or
   * derivative of this code cannot be changed.  i.e. this code cannot simply be
   * copied and put under another distribution licence
   * [including the GNU Public Licence.]
   */
  /* ====================================================================
   * Copyright (c) 1998-2007 The OpenSSL Project.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. All advertising materials mentioning features or use of this
   *    software must display the following acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
   *
   * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For written permission, please contact
   *    openssl-core@openssl.org.
   *
   * 5. Products derived from this software may not be called "OpenSSL"
   *    nor may "OpenSSL" appear in their names without prior written
   *    permission of the OpenSSL Project.
   *
   * 6. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by the OpenSSL Project
   *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
   *
   * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   * OF THE POSSIBILITY OF SUCH DAMAGE.
   * ====================================================================
   *
   * This product includes cryptographic software written by Eric Young
   * (eay@cryptsoft.com).  This product includes software written by Tim
   * Hudson (tjh@cryptsoft.com).
   *
   */
  
  #include <stdio.h>
  #include <openssl/objects.h>
  #include <openssl/evp.h>
  #include <openssl/hmac.h>
  #ifndef OPENSSL_NO_EC
  #ifdef OPENSSL_NO_EC2M
  # include <openssl/ec.h>
  #endif
  #endif
  #include <openssl/ocsp.h>
  #include <openssl/rand.h>
  #include "ssl_locl.h"
  
  const char tls1_version_str[] = "TLSv1" OPENSSL_VERSION_PTEXT;
  
  #ifndef OPENSSL_NO_TLSEXT
  static int tls_decrypt_ticket(SSL *s, const unsigned char *tick, int ticklen,
                                const unsigned char *sess_id, int sesslen,
                                SSL_SESSION **psess);
  static int ssl_check_clienthello_tlsext_early(SSL *s);
  int ssl_check_serverhello_tlsext(SSL *s);
  #endif
  
  SSL3_ENC_METHOD TLSv1_enc_data = {
      tls1_enc,
      tls1_mac,
      tls1_setup_key_block,
      tls1_generate_master_secret,
      tls1_change_cipher_state,
      tls1_final_finish_mac,
      TLS1_FINISH_MAC_LENGTH,
      tls1_cert_verify_mac,
      TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
      TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
      tls1_alert_code,
      tls1_export_keying_material,
      0,
      SSL3_HM_HEADER_LENGTH,
      ssl3_set_handshake_header,
      ssl3_handshake_write
  };
  
  SSL3_ENC_METHOD TLSv1_1_enc_data = {
      tls1_enc,
      tls1_mac,
      tls1_setup_key_block,
      tls1_generate_master_secret,
      tls1_change_cipher_state,
      tls1_final_finish_mac,
      TLS1_FINISH_MAC_LENGTH,
      tls1_cert_verify_mac,
      TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
      TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
      tls1_alert_code,
      tls1_export_keying_material,
      SSL_ENC_FLAG_EXPLICIT_IV,
      SSL3_HM_HEADER_LENGTH,
      ssl3_set_handshake_header,
      ssl3_handshake_write
  };
  
  SSL3_ENC_METHOD TLSv1_2_enc_data = {
      tls1_enc,
      tls1_mac,
      tls1_setup_key_block,
      tls1_generate_master_secret,
      tls1_change_cipher_state,
      tls1_final_finish_mac,
      TLS1_FINISH_MAC_LENGTH,
      tls1_cert_verify_mac,
      TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
      TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
      tls1_alert_code,
      tls1_export_keying_material,
      SSL_ENC_FLAG_EXPLICIT_IV | SSL_ENC_FLAG_SIGALGS | SSL_ENC_FLAG_SHA256_PRF
          | SSL_ENC_FLAG_TLS1_2_CIPHERS,
      SSL3_HM_HEADER_LENGTH,
      ssl3_set_handshake_header,
      ssl3_handshake_write
  };
  
  long tls1_default_timeout(void)
  {
      /*
       * 2 hours, the 24 hours mentioned in the TLSv1 spec is way too long for
       * http, the cache would over fill
       */
      return (60 * 60 * 2);
  }
  
  int tls1_new(SSL *s)
  {
      if (!ssl3_new(s))
          return (0);
      s->method->ssl_clear(s);
      return (1);
  }
  
  void tls1_free(SSL *s)
  {
  #ifndef OPENSSL_NO_TLSEXT
      if (s->tlsext_session_ticket) {
          OPENSSL_free(s->tlsext_session_ticket);
      }
  #endif                          /* OPENSSL_NO_TLSEXT */
      ssl3_free(s);
  }
  
  void tls1_clear(SSL *s)
  {
      ssl3_clear(s);
      s->version = s->method->version;
  }
  
  #ifndef OPENSSL_NO_EC
  
  static int nid_list[] = {
      NID_sect163k1,              /* sect163k1 (1) */
      NID_sect163r1,              /* sect163r1 (2) */
      NID_sect163r2,              /* sect163r2 (3) */
      NID_sect193r1,              /* sect193r1 (4) */
      NID_sect193r2,              /* sect193r2 (5) */
      NID_sect233k1,              /* sect233k1 (6) */
      NID_sect233r1,              /* sect233r1 (7) */
      NID_sect239k1,              /* sect239k1 (8) */
      NID_sect283k1,              /* sect283k1 (9) */
      NID_sect283r1,              /* sect283r1 (10) */
      NID_sect409k1,              /* sect409k1 (11) */
      NID_sect409r1,              /* sect409r1 (12) */
      NID_sect571k1,              /* sect571k1 (13) */
      NID_sect571r1,              /* sect571r1 (14) */
      NID_secp160k1,              /* secp160k1 (15) */
      NID_secp160r1,              /* secp160r1 (16) */
      NID_secp160r2,              /* secp160r2 (17) */
      NID_secp192k1,              /* secp192k1 (18) */
      NID_X9_62_prime192v1,       /* secp192r1 (19) */
      NID_secp224k1,              /* secp224k1 (20) */
      NID_secp224r1,              /* secp224r1 (21) */
      NID_secp256k1,              /* secp256k1 (22) */
      NID_X9_62_prime256v1,       /* secp256r1 (23) */
      NID_secp384r1,              /* secp384r1 (24) */
      NID_secp521r1,              /* secp521r1 (25) */
      NID_brainpoolP256r1,        /* brainpoolP256r1 (26) */
      NID_brainpoolP384r1,        /* brainpoolP384r1 (27) */
      NID_brainpoolP512r1         /* brainpool512r1 (28) */
  };
  
  static const unsigned char ecformats_default[] = {
      TLSEXT_ECPOINTFORMAT_uncompressed,
      TLSEXT_ECPOINTFORMAT_ansiX962_compressed_prime,
      TLSEXT_ECPOINTFORMAT_ansiX962_compressed_char2
  };
  
  /* The client's default curves / the server's 'auto' curves. */
  static const unsigned char eccurves_auto[] = {
      /* Prefer P-256 which has the fastest and most secure implementations. */
      0, 23,                      /* secp256r1 (23) */
      /* Other >= 256-bit prime curves. */
      0, 25,                      /* secp521r1 (25) */
      0, 28,                      /* brainpool512r1 (28) */
      0, 27,                      /* brainpoolP384r1 (27) */
      0, 24,                      /* secp384r1 (24) */
      0, 26,                      /* brainpoolP256r1 (26) */
      0, 22,                      /* secp256k1 (22) */
  # ifndef OPENSSL_NO_EC2M
      /* >= 256-bit binary curves. */
      0, 14,                      /* sect571r1 (14) */
      0, 13,                      /* sect571k1 (13) */
      0, 11,                      /* sect409k1 (11) */
      0, 12,                      /* sect409r1 (12) */
      0, 9,                       /* sect283k1 (9) */
      0, 10,                      /* sect283r1 (10) */
  # endif
  };
  
  static const unsigned char eccurves_all[] = {
      /* Prefer P-256 which has the fastest and most secure implementations. */
      0, 23,                      /* secp256r1 (23) */
      /* Other >= 256-bit prime curves. */
      0, 25,                      /* secp521r1 (25) */
      0, 28,                      /* brainpool512r1 (28) */
      0, 27,                      /* brainpoolP384r1 (27) */
      0, 24,                      /* secp384r1 (24) */
      0, 26,                      /* brainpoolP256r1 (26) */
      0, 22,                      /* secp256k1 (22) */
  # ifndef OPENSSL_NO_EC2M
      /* >= 256-bit binary curves. */
      0, 14,                      /* sect571r1 (14) */
      0, 13,                      /* sect571k1 (13) */
      0, 11,                      /* sect409k1 (11) */
      0, 12,                      /* sect409r1 (12) */
      0, 9,                       /* sect283k1 (9) */
      0, 10,                      /* sect283r1 (10) */
  # endif
      /*
       * Remaining curves disabled by default but still permitted if set
       * via an explicit callback or parameters.
       */
      0, 20,                      /* secp224k1 (20) */
      0, 21,                      /* secp224r1 (21) */
      0, 18,                      /* secp192k1 (18) */
      0, 19,                      /* secp192r1 (19) */
      0, 15,                      /* secp160k1 (15) */
      0, 16,                      /* secp160r1 (16) */
      0, 17,                      /* secp160r2 (17) */
  # ifndef OPENSSL_NO_EC2M
      0, 8,                       /* sect239k1 (8) */
      0, 6,                       /* sect233k1 (6) */
      0, 7,                       /* sect233r1 (7) */
      0, 4,                       /* sect193r1 (4) */
      0, 5,                       /* sect193r2 (5) */
      0, 1,                       /* sect163k1 (1) */
      0, 2,                       /* sect163r1 (2) */
      0, 3,                       /* sect163r2 (3) */
  # endif
  };
  
  static const unsigned char suiteb_curves[] = {
      0, TLSEXT_curve_P_256,
      0, TLSEXT_curve_P_384
  };
  
  # ifdef OPENSSL_FIPS
  /* Brainpool not allowed in FIPS mode */
  static const unsigned char fips_curves_default[] = {
  #  ifndef OPENSSL_NO_EC2M
      0, 14,                      /* sect571r1 (14) */
      0, 13,                      /* sect571k1 (13) */
  #  endif
      0, 25,                      /* secp521r1 (25) */
  #  ifndef OPENSSL_NO_EC2M
      0, 11,                      /* sect409k1 (11) */
      0, 12,                      /* sect409r1 (12) */
  #  endif
      0, 24,                      /* secp384r1 (24) */
  #  ifndef OPENSSL_NO_EC2M
      0, 9,                       /* sect283k1 (9) */
      0, 10,                      /* sect283r1 (10) */
  #  endif
      0, 22,                      /* secp256k1 (22) */
      0, 23,                      /* secp256r1 (23) */
  #  ifndef OPENSSL_NO_EC2M
      0, 8,                       /* sect239k1 (8) */
      0, 6,                       /* sect233k1 (6) */
      0, 7,                       /* sect233r1 (7) */
  #  endif
      0, 20,                      /* secp224k1 (20) */
      0, 21,                      /* secp224r1 (21) */
  #  ifndef OPENSSL_NO_EC2M
      0, 4,                       /* sect193r1 (4) */
      0, 5,                       /* sect193r2 (5) */
  #  endif
      0, 18,                      /* secp192k1 (18) */
      0, 19,                      /* secp192r1 (19) */
  #  ifndef OPENSSL_NO_EC2M
      0, 1,                       /* sect163k1 (1) */
      0, 2,                       /* sect163r1 (2) */
      0, 3,                       /* sect163r2 (3) */
  #  endif
      0, 15,                      /* secp160k1 (15) */
      0, 16,                      /* secp160r1 (16) */
      0, 17,                      /* secp160r2 (17) */
  };
  # endif
  
  int tls1_ec_curve_id2nid(int curve_id)
  {
      /* ECC curves from RFC 4492 and RFC 7027 */
      if ((curve_id < 1) || ((unsigned int)curve_id >
                             sizeof(nid_list) / sizeof(nid_list[0])))
          return 0;
      return nid_list[curve_id - 1];
  }
  
  int tls1_ec_nid2curve_id(int nid)
  {
      /* ECC curves from RFC 4492 and RFC 7027 */
      switch (nid) {
      case NID_sect163k1:        /* sect163k1 (1) */
          return 1;
      case NID_sect163r1:        /* sect163r1 (2) */
          return 2;
      case NID_sect163r2:        /* sect163r2 (3) */
          return 3;
      case NID_sect193r1:        /* sect193r1 (4) */
          return 4;
      case NID_sect193r2:        /* sect193r2 (5) */
          return 5;
      case NID_sect233k1:        /* sect233k1 (6) */
          return 6;
      case NID_sect233r1:        /* sect233r1 (7) */
          return 7;
      case NID_sect239k1:        /* sect239k1 (8) */
          return 8;
      case NID_sect283k1:        /* sect283k1 (9) */
          return 9;
      case NID_sect283r1:        /* sect283r1 (10) */
          return 10;
      case NID_sect409k1:        /* sect409k1 (11) */
          return 11;
      case NID_sect409r1:        /* sect409r1 (12) */
          return 12;
      case NID_sect571k1:        /* sect571k1 (13) */
          return 13;
      case NID_sect571r1:        /* sect571r1 (14) */
          return 14;
      case NID_secp160k1:        /* secp160k1 (15) */
          return 15;
      case NID_secp160r1:        /* secp160r1 (16) */
          return 16;
      case NID_secp160r2:        /* secp160r2 (17) */
          return 17;
      case NID_secp192k1:        /* secp192k1 (18) */
          return 18;
      case NID_X9_62_prime192v1: /* secp192r1 (19) */
          return 19;
      case NID_secp224k1:        /* secp224k1 (20) */
          return 20;
      case NID_secp224r1:        /* secp224r1 (21) */
          return 21;
      case NID_secp256k1:        /* secp256k1 (22) */
          return 22;
      case NID_X9_62_prime256v1: /* secp256r1 (23) */
          return 23;
      case NID_secp384r1:        /* secp384r1 (24) */
          return 24;
      case NID_secp521r1:        /* secp521r1 (25) */
          return 25;
      case NID_brainpoolP256r1:  /* brainpoolP256r1 (26) */
          return 26;
      case NID_brainpoolP384r1:  /* brainpoolP384r1 (27) */
          return 27;
      case NID_brainpoolP512r1:  /* brainpool512r1 (28) */
          return 28;
      default:
          return 0;
      }
  }
  
  /*
   * Get curves list, if "sess" is set return client curves otherwise
   * preferred list.
   * Sets |num_curves| to the number of curves in the list, i.e.,
   * the length of |pcurves| is 2 * num_curves.
   * Returns 1 on success and 0 if the client curves list has invalid format.
   * The latter indicates an internal error: we should not be accepting such
   * lists in the first place.
   * TODO(emilia): we should really be storing the curves list in explicitly
   * parsed form instead. (However, this would affect binary compatibility
   * so cannot happen in the 1.0.x series.)
   */
  static int tls1_get_curvelist(SSL *s, int sess,
                                const unsigned char **pcurves,
                                size_t *num_curves)
  {
      size_t pcurveslen = 0;
      if (sess) {
          *pcurves = s->session->tlsext_ellipticcurvelist;
          pcurveslen = s->session->tlsext_ellipticcurvelist_length;
      } else {
          /* For Suite B mode only include P-256, P-384 */
          switch (tls1_suiteb(s)) {
          case SSL_CERT_FLAG_SUITEB_128_LOS:
              *pcurves = suiteb_curves;
              pcurveslen = sizeof(suiteb_curves);
              break;
  
          case SSL_CERT_FLAG_SUITEB_128_LOS_ONLY:
              *pcurves = suiteb_curves;
              pcurveslen = 2;
              break;
  
          case SSL_CERT_FLAG_SUITEB_192_LOS:
              *pcurves = suiteb_curves + 2;
              pcurveslen = 2;
              break;
          default:
              *pcurves = s->tlsext_ellipticcurvelist;
              pcurveslen = s->tlsext_ellipticcurvelist_length;
          }
          if (!*pcurves) {
  # ifdef OPENSSL_FIPS
              if (FIPS_mode()) {
                  *pcurves = fips_curves_default;
                  pcurveslen = sizeof(fips_curves_default);
              } else
  # endif
              {
                  if (!s->server || s->cert->ecdh_tmp_auto) {
                      *pcurves = eccurves_auto;
                      pcurveslen = sizeof(eccurves_auto);
                  } else {
                      *pcurves = eccurves_all;
                      pcurveslen = sizeof(eccurves_all);
                  }
              }
          }
      }
      /* We do not allow odd length arrays to enter the system. */
      if (pcurveslen & 1) {
          SSLerr(SSL_F_TLS1_GET_CURVELIST, ERR_R_INTERNAL_ERROR);
          *num_curves = 0;
          return 0;
      } else {
          *num_curves = pcurveslen / 2;
          return 1;
      }
  }
  
  /* Check a curve is one of our preferences */
  int tls1_check_curve(SSL *s, const unsigned char *p, size_t len)
  {
      const unsigned char *curves;
      size_t num_curves, i;
      unsigned int suiteb_flags = tls1_suiteb(s);
      if (len != 3 || p[0] != NAMED_CURVE_TYPE)
          return 0;
      /* Check curve matches Suite B preferences */
      if (suiteb_flags) {
          unsigned long cid = s->s3->tmp.new_cipher->id;
          if (p[1])
              return 0;
          if (cid == TLS1_CK_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256) {
              if (p[2] != TLSEXT_curve_P_256)
                  return 0;
          } else if (cid == TLS1_CK_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384) {
              if (p[2] != TLSEXT_curve_P_384)
                  return 0;
          } else                  /* Should never happen */
              return 0;
      }
      if (!tls1_get_curvelist(s, 0, &curves, &num_curves))
          return 0;
      for (i = 0; i < num_curves; i++, curves += 2) {
          if (p[1] == curves[0] && p[2] == curves[1])
              return 1;
      }
      return 0;
  }
  
  /*-
   * Return |nmatch|th shared curve or NID_undef if there is no match.
   * For nmatch == -1, return number of  matches
   * For nmatch == -2, return the NID of the curve to use for
   * an EC tmp key, or NID_undef if there is no match.
   */
  int tls1_shared_curve(SSL *s, int nmatch)
  {
      const unsigned char *pref, *supp;
      size_t num_pref, num_supp, i, j;
      int k;
      /* Can't do anything on client side */
      if (s->server == 0)
          return -1;
      if (nmatch == -2) {
          if (tls1_suiteb(s)) {
              /*
               * For Suite B ciphersuite determines curve: we already know
               * these are acceptable due to previous checks.
               */
              unsigned long cid = s->s3->tmp.new_cipher->id;
              if (cid == TLS1_CK_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256)
                  return NID_X9_62_prime256v1; /* P-256 */
              if (cid == TLS1_CK_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384)
                  return NID_secp384r1; /* P-384 */
              /* Should never happen */
              return NID_undef;
          }
          /* If not Suite B just return first preference shared curve */
          nmatch = 0;
      }
      /*
       * Avoid truncation. tls1_get_curvelist takes an int
       * but s->options is a long...
       */
      if (!tls1_get_curvelist
          (s, (s->options & SSL_OP_CIPHER_SERVER_PREFERENCE) != 0, &supp,
           &num_supp))
          /* In practice, NID_undef == 0 but let's be precise. */
          return nmatch == -1 ? 0 : NID_undef;
      if (!tls1_get_curvelist
          (s, !(s->options & SSL_OP_CIPHER_SERVER_PREFERENCE), &pref,
           &num_pref))
          return nmatch == -1 ? 0 : NID_undef;
  
      /*
       * If the client didn't send the elliptic_curves extension all of them
       * are allowed.
       */
      if (num_supp == 0 && (s->options & SSL_OP_CIPHER_SERVER_PREFERENCE) != 0) {
          supp = eccurves_all;
          num_supp = sizeof(eccurves_all) / 2;
      } else if (num_pref == 0 &&
          (s->options & SSL_OP_CIPHER_SERVER_PREFERENCE) == 0) {
          pref = eccurves_all;
          num_pref = sizeof(eccurves_all) / 2;
      }
  
      k = 0;
      for (i = 0; i < num_pref; i++, pref += 2) {
          const unsigned char *tsupp = supp;
          for (j = 0; j < num_supp; j++, tsupp += 2) {
              if (pref[0] == tsupp[0] && pref[1] == tsupp[1]) {
                  if (nmatch == k) {
                      int id = (pref[0] << 8) | pref[1];
                      return tls1_ec_curve_id2nid(id);
                  }
                  k++;
              }
          }
      }
      if (nmatch == -1)
          return k;
      /* Out of range (nmatch > k). */
      return NID_undef;
  }
  
  int tls1_set_curves(unsigned char **pext, size_t *pextlen,
                      int *curves, size_t ncurves)
  {
      unsigned char *clist, *p;
      size_t i;
      /*
       * Bitmap of curves included to detect duplicates: only works while curve
       * ids < 32
       */
      unsigned long dup_list = 0;
  # ifdef OPENSSL_NO_EC2M
      EC_GROUP *curve;
  # endif
  
      clist = OPENSSL_malloc(ncurves * 2);
      if (!clist)
          return 0;
      for (i = 0, p = clist; i < ncurves; i++) {
          unsigned long idmask;
          int id;
          id = tls1_ec_nid2curve_id(curves[i]);
  # ifdef OPENSSL_FIPS
          /* NB: 25 is last curve ID supported by FIPS module */
          if (FIPS_mode() && id > 25) {
              OPENSSL_free(clist);
              return 0;
          }
  # endif
  # ifdef OPENSSL_NO_EC2M
          curve = EC_GROUP_new_by_curve_name(curves[i]);
          if (!curve || EC_METHOD_get_field_type(EC_GROUP_method_of(curve))
              == NID_X9_62_characteristic_two_field) {
              if (curve)
                  EC_GROUP_free(curve);
              OPENSSL_free(clist);
              return 0;
          } else
              EC_GROUP_free(curve);
  # endif
          idmask = 1L << id;
          if (!id || (dup_list & idmask)) {
              OPENSSL_free(clist);
              return 0;
          }
          dup_list |= idmask;
          s2n(id, p);
      }
      if (*pext)
          OPENSSL_free(*pext);
      *pext = clist;
      *pextlen = ncurves * 2;
      return 1;
  }
  
  # define MAX_CURVELIST   28
  
  typedef struct {
      size_t nidcnt;
      int nid_arr[MAX_CURVELIST];
  } nid_cb_st;
  
  static int nid_cb(const char *elem, int len, void *arg)
  {
      nid_cb_st *narg = arg;
      size_t i;
      int nid;
      char etmp[20];
      if (elem == NULL)
          return 0;
      if (narg->nidcnt == MAX_CURVELIST)
          return 0;
      if (len > (int)(sizeof(etmp) - 1))
          return 0;
      memcpy(etmp, elem, len);
      etmp[len] = 0;
      nid = EC_curve_nist2nid(etmp);
      if (nid == NID_undef)
          nid = OBJ_sn2nid(etmp);
      if (nid == NID_undef)
          nid = OBJ_ln2nid(etmp);
      if (nid == NID_undef)
          return 0;
      for (i = 0; i < narg->nidcnt; i++)
          if (narg->nid_arr[i] == nid)
              return 0;
      narg->nid_arr[narg->nidcnt++] = nid;
      return 1;
  }
  
  /* Set curves based on a colon separate list */
  int tls1_set_curves_list(unsigned char **pext, size_t *pextlen,
                           const char *str)
  {
      nid_cb_st ncb;
      ncb.nidcnt = 0;
      if (!CONF_parse_list(str, ':', 1, nid_cb, &ncb))
          return 0;
      if (pext == NULL)
          return 1;
      return tls1_set_curves(pext, pextlen, ncb.nid_arr, ncb.nidcnt);
  }
  
  /* For an EC key set TLS id and required compression based on parameters */
  static int tls1_set_ec_id(unsigned char *curve_id, unsigned char *comp_id,
                            EC_KEY *ec)
  {
      int is_prime, id;
      const EC_GROUP *grp;
      const EC_METHOD *meth;
      if (!ec)
          return 0;
      /* Determine if it is a prime field */
      grp = EC_KEY_get0_group(ec);
      if (!grp)
          return 0;
      meth = EC_GROUP_method_of(grp);
      if (!meth)
          return 0;
      if (EC_METHOD_get_field_type(meth) == NID_X9_62_prime_field)
          is_prime = 1;
      else
          is_prime = 0;
      /* Determine curve ID */
      id = EC_GROUP_get_curve_name(grp);
      id = tls1_ec_nid2curve_id(id);
      /* If we have an ID set it, otherwise set arbitrary explicit curve */
      if (id) {
          curve_id[0] = 0;
          curve_id[1] = (unsigned char)id;
      } else {
          curve_id[0] = 0xff;
          if (is_prime)
              curve_id[1] = 0x01;
          else
              curve_id[1] = 0x02;
      }
      if (comp_id) {
          if (EC_KEY_get0_public_key(ec) == NULL)
              return 0;
          if (EC_KEY_get_conv_form(ec) == POINT_CONVERSION_COMPRESSED) {
              if (is_prime)
                  *comp_id = TLSEXT_ECPOINTFORMAT_ansiX962_compressed_prime;
              else
                  *comp_id = TLSEXT_ECPOINTFORMAT_ansiX962_compressed_char2;
          } else
              *comp_id = TLSEXT_ECPOINTFORMAT_uncompressed;
      }
      return 1;
  }
  
  /* Check an EC key is compatible with extensions */
  static int tls1_check_ec_key(SSL *s,
                               unsigned char *curve_id, unsigned char *comp_id)
  {
      const unsigned char *pformats, *pcurves;
      size_t num_formats, num_curves, i;
      int j;
      /*
       * If point formats extension present check it, otherwise everything is
       * supported (see RFC4492).
       */
      if (comp_id && s->session->tlsext_ecpointformatlist) {
          pformats = s->session->tlsext_ecpointformatlist;
          num_formats = s->session->tlsext_ecpointformatlist_length;
          for (i = 0; i < num_formats; i++, pformats++) {
              if (*comp_id == *pformats)
                  break;
          }
          if (i == num_formats)
              return 0;
      }
      if (!curve_id)
          return 1;
      /* Check curve is consistent with client and server preferences */
      for (j = 0; j <= 1; j++) {
          if (!tls1_get_curvelist(s, j, &pcurves, &num_curves))
              return 0;
          if (j == 1 && num_curves == 0) {
              /*
               * If we've not received any curves then skip this check.
               * RFC 4492 does not require the supported elliptic curves extension
               * so if it is not sent we can just choose any curve.
               * It is invalid to send an empty list in the elliptic curves
               * extension, so num_curves == 0 always means no extension.
               */
              break;
          }
          for (i = 0; i < num_curves; i++, pcurves += 2) {
              if (pcurves[0] == curve_id[0] && pcurves[1] == curve_id[1])
                  break;
          }
          if (i == num_curves)
              return 0;
          /* For clients can only check sent curve list */
          if (!s->server)
              return 1;
      }
      return 1;
  }
  
  static void tls1_get_formatlist(SSL *s, const unsigned char **pformats,
                                  size_t *num_formats)
  {
      /*
       * If we have a custom point format list use it otherwise use default
       */
      if (s->tlsext_ecpointformatlist) {
          *pformats = s->tlsext_ecpointformatlist;
          *num_formats = s->tlsext_ecpointformatlist_length;
      } else {
          *pformats = ecformats_default;
          /* For Suite B we don't support char2 fields */
          if (tls1_suiteb(s))
              *num_formats = sizeof(ecformats_default) - 1;
          else
              *num_formats = sizeof(ecformats_default);
      }
  }
  
  /*
   * Check cert parameters compatible with extensions: currently just checks EC
   * certificates have compatible curves and compression.
   */
  static int tls1_check_cert_param(SSL *s, X509 *x, int set_ee_md)
  {
      unsigned char comp_id, curve_id[2];
      EVP_PKEY *pkey;
      int rv;
      pkey = X509_get_pubkey(x);
      if (!pkey)
          return 0;
      /* If not EC nothing to do */
      if (pkey->type != EVP_PKEY_EC) {
          EVP_PKEY_free(pkey);
          return 1;
      }
      rv = tls1_set_ec_id(curve_id, &comp_id, pkey->pkey.ec);
      EVP_PKEY_free(pkey);
      if (!rv)
          return 0;
      /*
       * Can't check curve_id for client certs as we don't have a supported
       * curves extension.
       */
      rv = tls1_check_ec_key(s, s->server ? curve_id : NULL, &comp_id);
      if (!rv)
          return 0;
      /*
       * Special case for suite B. We *MUST* sign using SHA256+P-256 or
       * SHA384+P-384, adjust digest if necessary.
       */
      if (set_ee_md && tls1_suiteb(s)) {
          int check_md;
          size_t i;
          CERT *c = s->cert;
          if (curve_id[0])
              return 0;
          /* Check to see we have necessary signing algorithm */
          if (curve_id[1] == TLSEXT_curve_P_256)
              check_md = NID_ecdsa_with_SHA256;
          else if (curve_id[1] == TLSEXT_curve_P_384)
              check_md = NID_ecdsa_with_SHA384;
          else
              return 0;           /* Should never happen */
          for (i = 0; i < c->shared_sigalgslen; i++)
              if (check_md == c->shared_sigalgs[i].signandhash_nid)
                  break;
          if (i == c->shared_sigalgslen)
              return 0;
          if (set_ee_md == 2) {
              if (check_md == NID_ecdsa_with_SHA256)
                  c->pkeys[SSL_PKEY_ECC].digest = EVP_sha256();
              else
                  c->pkeys[SSL_PKEY_ECC].digest = EVP_sha384();
          }
      }
      return rv;
  }
  
  # ifndef OPENSSL_NO_ECDH
  /* Check EC temporary key is compatible with client extensions */
  int tls1_check_ec_tmp_key(SSL *s, unsigned long cid)
  {
      unsigned char curve_id[2];
      EC_KEY *ec = s->cert->ecdh_tmp;
  #  ifdef OPENSSL_SSL_DEBUG_BROKEN_PROTOCOL
      /* Allow any curve: not just those peer supports */
      if (s->cert->cert_flags & SSL_CERT_FLAG_BROKEN_PROTOCOL)
          return 1;
  #  endif
      /*
       * If Suite B, AES128 MUST use P-256 and AES256 MUST use P-384, no other
       * curves permitted.
       */
      if (tls1_suiteb(s)) {
          /* Curve to check determined by ciphersuite */
          if (cid == TLS1_CK_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256)
              curve_id[1] = TLSEXT_curve_P_256;
          else if (cid == TLS1_CK_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384)
              curve_id[1] = TLSEXT_curve_P_384;
          else
              return 0;
          curve_id[0] = 0;
          /* Check this curve is acceptable */
          if (!tls1_check_ec_key(s, curve_id, NULL))
              return 0;
          /* If auto or setting curve from callback assume OK */
          if (s->cert->ecdh_tmp_auto || s->cert->ecdh_tmp_cb)
              return 1;
          /* Otherwise check curve is acceptable */
          else {
              unsigned char curve_tmp[2];
              if (!ec)
                  return 0;
              if (!tls1_set_ec_id(curve_tmp, NULL, ec))
                  return 0;
              if (!curve_tmp[0] || curve_tmp[1] == curve_id[1])
                  return 1;
              return 0;
          }
  
      }
      if (s->cert->ecdh_tmp_auto) {
          /* Need a shared curve */
          if (tls1_shared_curve(s, 0))
              return 1;
          else
              return 0;
      }
      if (!ec) {
          if (s->cert->ecdh_tmp_cb)
              return 1;
          else
              return 0;
      }
      if (!tls1_set_ec_id(curve_id, NULL, ec))
          return 0;
  /* Set this to allow use of invalid curves for testing */
  #  if 0
      return 1;
  #  else
      return tls1_check_ec_key(s, curve_id, NULL);
  #  endif
  }
  # endif                         /* OPENSSL_NO_ECDH */
  
  #else
  
  static int tls1_check_cert_param(SSL *s, X509 *x, int set_ee_md)
  {
      return 1;
  }
  
  #endif                          /* OPENSSL_NO_EC */
  
  #ifndef OPENSSL_NO_TLSEXT
  
  /*
   * List of supported signature algorithms and hashes. Should make this
   * customisable at some point, for now include everything we support.
   */
  
  # ifdef OPENSSL_NO_RSA
  #  define tlsext_sigalg_rsa(md) /* */
  # else
  #  define tlsext_sigalg_rsa(md) md, TLSEXT_signature_rsa,
  # endif
  
  # ifdef OPENSSL_NO_DSA
  #  define tlsext_sigalg_dsa(md) /* */
  # else
  #  define tlsext_sigalg_dsa(md) md, TLSEXT_signature_dsa,
  # endif
  
  # ifdef OPENSSL_NO_ECDSA
  #  define tlsext_sigalg_ecdsa(md)
                                  /* */
  # else
  #  define tlsext_sigalg_ecdsa(md) md, TLSEXT_signature_ecdsa,
  # endif
  
  # define tlsext_sigalg(md) \
                  tlsext_sigalg_rsa(md) \
                  tlsext_sigalg_dsa(md) \
                  tlsext_sigalg_ecdsa(md)
  
  static unsigned char tls12_sigalgs[] = {
  # ifndef OPENSSL_NO_SHA512
      tlsext_sigalg(TLSEXT_hash_sha512)
          tlsext_sigalg(TLSEXT_hash_sha384)
  # endif
  # ifndef OPENSSL_NO_SHA256
          tlsext_sigalg(TLSEXT_hash_sha256)
          tlsext_sigalg(TLSEXT_hash_sha224)
  # endif
  # ifndef OPENSSL_NO_SHA
          tlsext_sigalg(TLSEXT_hash_sha1)
  # endif
  };
  
  # ifndef OPENSSL_NO_ECDSA
  static unsigned char suiteb_sigalgs[] = {
      tlsext_sigalg_ecdsa(TLSEXT_hash_sha256)
          tlsext_sigalg_ecdsa(TLSEXT_hash_sha384)
  };
  # endif
  size_t tls12_get_psigalgs(SSL *s, const unsigned char **psigs)
  {
      /*
       * If Suite B mode use Suite B sigalgs only, ignore any other
       * preferences.
       */
  # ifndef OPENSSL_NO_EC
      switch (tls1_suiteb(s)) {
      case SSL_CERT_FLAG_SUITEB_128_LOS:
          *psigs = suiteb_sigalgs;
          return sizeof(suiteb_sigalgs);
  
      case SSL_CERT_FLAG_SUITEB_128_LOS_ONLY:
          *psigs = suiteb_sigalgs;
          return 2;
  
      case SSL_CERT_FLAG_SUITEB_192_LOS:
          *psigs = suiteb_sigalgs + 2;
          return 2;
      }
  # endif
      /* If server use client authentication sigalgs if not NULL */
      if (s->server && s->cert->client_sigalgs) {
          *psigs = s->cert->client_sigalgs;
          return s->cert->client_sigalgslen;
      } else if (s->cert->conf_sigalgs) {
          *psigs = s->cert->conf_sigalgs;
          return s->cert->conf_sigalgslen;
      } else {
          *psigs = tls12_sigalgs;
          return sizeof(tls12_sigalgs);
      }
  }
  
  /*
   * Check signature algorithm is consistent with sent supported signature
   * algorithms and if so return relevant digest.
   */
  int tls12_check_peer_sigalg(const EVP_MD **pmd, SSL *s,
                              const unsigned char *sig, EVP_PKEY *pkey)
  {
      const unsigned char *sent_sigs;
      size_t sent_sigslen, i;
      int sigalg = tls12_get_sigid(pkey);
      /* Should never happen */
      if (sigalg == -1)
          return -1;
      /* Check key type is consistent with signature */
      if (sigalg != (int)sig[1]) {
          SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_WRONG_SIGNATURE_TYPE);
          return 0;
      }
  # ifndef OPENSSL_NO_EC
      if (pkey->type == EVP_PKEY_EC) {
          unsigned char curve_id[2], comp_id;
          /* Check compression and curve matches extensions */
          if (!tls1_set_ec_id(curve_id, &comp_id, pkey->pkey.ec))
              return 0;
          if (!s->server && !tls1_check_ec_key(s, curve_id, &comp_id)) {
              SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_WRONG_CURVE);
              return 0;
          }
          /* If Suite B only P-384+SHA384 or P-256+SHA-256 allowed */
          if (tls1_suiteb(s)) {
              if (curve_id[0])
                  return 0;
              if (curve_id[1] == TLSEXT_curve_P_256) {
                  if (sig[0] != TLSEXT_hash_sha256) {
                      SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG,
                             SSL_R_ILLEGAL_SUITEB_DIGEST);
                      return 0;
                  }
              } else if (curve_id[1] == TLSEXT_curve_P_384) {
                  if (sig[0] != TLSEXT_hash_sha384) {
                      SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG,
                             SSL_R_ILLEGAL_SUITEB_DIGEST);
                      return 0;
                  }
              } else
                  return 0;
          }
      } else if (tls1_suiteb(s))
          return 0;
  # endif
  
      /* Check signature matches a type we sent */
      sent_sigslen = tls12_get_psigalgs(s, &sent_sigs);
      for (i = 0; i < sent_sigslen; i += 2, sent_sigs += 2) {
          if (sig[0] == sent_sigs[0] && sig[1] == sent_sigs[1])
              break;
      }
      /* Allow fallback to SHA1 if not strict mode */
      if (i == sent_sigslen
          && (sig[0] != TLSEXT_hash_sha1
              || s->cert->cert_flags & SSL_CERT_FLAGS_CHECK_TLS_STRICT)) {
          SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_WRONG_SIGNATURE_TYPE);
          return 0;
      }
      *pmd = tls12_get_hash(sig[0]);
      if (*pmd == NULL) {
          SSLerr(SSL_F_TLS12_CHECK_PEER_SIGALG, SSL_R_UNKNOWN_DIGEST);
          return 0;
      }
      /*
       * Store the digest used so applications can retrieve it if they wish.
       */
      if (s->session && s->session->sess_cert)
          s->session->sess_cert->peer_key->digest = *pmd;
      return 1;
  }
  
  /*
   * Get a mask of disabled algorithms: an algorithm is disabled if it isn't
   * supported or doesn't appear in supported signature algorithms. Unlike
   * ssl_cipher_get_disabled this applies to a specific session and not global
   * settings.
   */
  void ssl_set_client_disabled(SSL *s)
  {
      CERT *c = s->cert;
      const unsigned char *sigalgs;
      size_t i, sigalgslen;
      int have_rsa = 0, have_dsa = 0, have_ecdsa = 0;
      c->mask_a = 0;
      c->mask_k = 0;
      /* Don't allow TLS 1.2 only ciphers if we don't suppport them */
      if (!SSL_CLIENT_USE_TLS1_2_CIPHERS(s))
          c->mask_ssl = SSL_TLSV1_2;
      else
          c->mask_ssl = 0;
      /*
       * Now go through all signature algorithms seeing if we support any for
       * RSA, DSA, ECDSA. Do this for all versions not just TLS 1.2.
       */
      sigalgslen = tls12_get_psigalgs(s, &sigalgs);
      for (i = 0; i < sigalgslen; i += 2, sigalgs += 2) {
          switch (sigalgs[1]) {
  # ifndef OPENSSL_NO_RSA
          case TLSEXT_signature_rsa:
              have_rsa = 1;
              break;
  # endif
  # ifndef OPENSSL_NO_DSA
          case TLSEXT_signature_dsa:
              have_dsa = 1;
              break;
  # endif
  # ifndef OPENSSL_NO_ECDSA
          case TLSEXT_signature_ecdsa:
              have_ecdsa = 1;
              break;
  # endif
          }
      }
      /*
       * Disable auth and static DH if we don't include any appropriate
       * signature algorithms.
       */
      if (!have_rsa) {
          c->mask_a |= SSL_aRSA;
          c->mask_k |= SSL_kDHr | SSL_kECDHr;
      }
      if (!have_dsa) {
          c->mask_a |= SSL_aDSS;
          c->mask_k |= SSL_kDHd;
      }
      if (!have_ecdsa) {
          c->mask_a |= SSL_aECDSA;
          c->mask_k |= SSL_kECDHe;
      }
  # ifndef OPENSSL_NO_KRB5
      if (!kssl_tgt_is_available(s->kssl_ctx)) {
          c->mask_a |= SSL_aKRB5;
          c->mask_k |= SSL_kKRB5;
      }
  # endif
  # ifndef OPENSSL_NO_PSK
      /* with PSK there must be client callback set */
      if (!s->psk_client_callback) {
          c->mask_a |= SSL_aPSK;
          c->mask_k |= SSL_kPSK;
      }
  # endif                         /* OPENSSL_NO_PSK */
  # ifndef OPENSSL_NO_SRP
      if (!(s->srp_ctx.srp_Mask & SSL_kSRP)) {
          c->mask_a |= SSL_aSRP;
          c->mask_k |= SSL_kSRP;
      }
  # endif
      c->valid = 1;
  }
  
  unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *buf,
                                            unsigned char *limit, int *al)
  {
      int extdatalen = 0;
      unsigned char *orig = buf;
      unsigned char *ret = buf;
  # ifndef OPENSSL_NO_EC
      /* See if we support any ECC ciphersuites */
      int using_ecc = 0;
      if (s->version >= TLS1_VERSION || SSL_IS_DTLS(s)) {
          int i;
          unsigned long alg_k, alg_a;
          STACK_OF(SSL_CIPHER) *cipher_stack = SSL_get_ciphers(s);
  
          for (i = 0; i < sk_SSL_CIPHER_num(cipher_stack); i++) {
              SSL_CIPHER *c = sk_SSL_CIPHER_value(cipher_stack, i);
  
              alg_k = c->algorithm_mkey;
              alg_a = c->algorithm_auth;
              if ((alg_k & (SSL_kEECDH | SSL_kECDHr | SSL_kECDHe)
                   || (alg_a & SSL_aECDSA))) {
                  using_ecc = 1;
                  break;
              }
          }
      }
  # endif
  
      /* don't add extensions for SSLv3 unless doing secure renegotiation */
      if (s->client_version == SSL3_VERSION && !s->s3->send_connection_binding)
          return orig;
  
      ret += 2;
  
      if (ret >= limit)
          return NULL;            /* this really never occurs, but ... */
  
      if (s->tlsext_hostname != NULL) {
          /* Add TLS extension servername to the Client Hello message */
          unsigned long size_str;
          long lenmax;
  
          /*-
           * check for enough space.
           * 4 for the servername type and entension length
           * 2 for servernamelist length
           * 1 for the hostname type
           * 2 for hostname length
           * + hostname length
           */
  
          if ((lenmax = limit - ret - 9) < 0
              || (size_str =
                  strlen(s->tlsext_hostname)) > (unsigned long)lenmax)
              return NULL;
  
          /* extension type and length */
          s2n(TLSEXT_TYPE_server_name, ret);
          s2n(size_str + 5, ret);
  
          /* length of servername list */
          s2n(size_str + 3, ret);
  
          /* hostname type, length and hostname */
          *(ret++) = (unsigned char)TLSEXT_NAMETYPE_host_name;
          s2n(size_str, ret);
          memcpy(ret, s->tlsext_hostname, size_str);
          ret += size_str;
      }
  
      /* Add RI if renegotiating */
      if (s->renegotiate) {
          int el;
  
          if (!ssl_add_clienthello_renegotiate_ext(s, 0, &el, 0)) {
              SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
  
          if ((limit - ret - 4 - el) < 0)
              return NULL;
  
          s2n(TLSEXT_TYPE_renegotiate, ret);
          s2n(el, ret);
  
          if (!ssl_add_clienthello_renegotiate_ext(s, ret, &el, el)) {
              SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
  
          ret += el;
      }
  # ifndef OPENSSL_NO_SRP
      /* Add SRP username if there is one */
      if (s->srp_ctx.login != NULL) { /* Add TLS extension SRP username to the
                                       * Client Hello message */
  
          int login_len = strlen(s->srp_ctx.login);
          if (login_len > 255 || login_len == 0) {
              SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
  
          /*-
           * check for enough space.
           * 4 for the srp type type and entension length
           * 1 for the srp user identity
           * + srp user identity length
           */
          if ((limit - ret - 5 - login_len) < 0)
              return NULL;
  
          /* fill in the extension */
          s2n(TLSEXT_TYPE_srp, ret);
          s2n(login_len + 1, ret);
          (*ret++) = (unsigned char)login_len;
          memcpy(ret, s->srp_ctx.login, login_len);
          ret += login_len;
      }
  # endif
  
  # ifndef OPENSSL_NO_EC
      if (using_ecc) {
          /*
           * Add TLS extension ECPointFormats to the ClientHello message
           */
          long lenmax;
          const unsigned char *pcurves, *pformats;
          size_t num_curves, num_formats, curves_list_len;
  
          tls1_get_formatlist(s, &pformats, &num_formats);
  
          if ((lenmax = limit - ret - 5) < 0)
              return NULL;
          if (num_formats > (size_t)lenmax)
              return NULL;
          if (num_formats > 255) {
              SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
  
          s2n(TLSEXT_TYPE_ec_point_formats, ret);
          /* The point format list has 1-byte length. */
          s2n(num_formats + 1, ret);
          *(ret++) = (unsigned char)num_formats;
          memcpy(ret, pformats, num_formats);
          ret += num_formats;
  
          /*
           * Add TLS extension EllipticCurves to the ClientHello message
           */
          pcurves = s->tlsext_ellipticcurvelist;
          if (!tls1_get_curvelist(s, 0, &pcurves, &num_curves))
              return NULL;
  
          if ((lenmax = limit - ret - 6) < 0)
              return NULL;
          if (num_curves > (size_t)lenmax / 2)
              return NULL;
          if (num_curves > 65532 / 2) {
              SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
          curves_list_len = 2 * num_curves;
          s2n(TLSEXT_TYPE_elliptic_curves, ret);
          s2n(curves_list_len + 2, ret);
          s2n(curves_list_len, ret);
          memcpy(ret, pcurves, curves_list_len);
          ret += curves_list_len;
      }
  # endif                         /* OPENSSL_NO_EC */
  
      if (!(SSL_get_options(s) & SSL_OP_NO_TICKET)) {
          int ticklen;
          if (!s->new_session && s->session && s->session->tlsext_tick)
              ticklen = s->session->tlsext_ticklen;
          else if (s->session && s->tlsext_session_ticket &&
                   s->tlsext_session_ticket->data) {
              ticklen = s->tlsext_session_ticket->length;
              s->session->tlsext_tick = OPENSSL_malloc(ticklen);
              if (!s->session->tlsext_tick)
                  return NULL;
              memcpy(s->session->tlsext_tick,
                     s->tlsext_session_ticket->data, ticklen);
              s->session->tlsext_ticklen = ticklen;
          } else
              ticklen = 0;
          if (ticklen == 0 && s->tlsext_session_ticket &&
              s->tlsext_session_ticket->data == NULL)
              goto skip_ext;
          /*
           * Check for enough room 2 for extension type, 2 for len rest for
           * ticket
           */
          if ((long)(limit - ret - 4 - ticklen) < 0)
              return NULL;
          s2n(TLSEXT_TYPE_session_ticket, ret);
          s2n(ticklen, ret);
          if (ticklen) {
              memcpy(ret, s->session->tlsext_tick, ticklen);
              ret += ticklen;
          }
      }
   skip_ext:
  
      if (SSL_CLIENT_USE_SIGALGS(s)) {
          size_t salglen;
          const unsigned char *salg;
          salglen = tls12_get_psigalgs(s, &salg);
          if ((size_t)(limit - ret) < salglen + 6)
              return NULL;
          s2n(TLSEXT_TYPE_signature_algorithms, ret);
          s2n(salglen + 2, ret);
          s2n(salglen, ret);
          memcpy(ret, salg, salglen);
          ret += salglen;
      }
  # ifdef TLSEXT_TYPE_opaque_prf_input
      if (s->s3->client_opaque_prf_input != NULL) {
          size_t col = s->s3->client_opaque_prf_input_len;
  
          if ((long)(limit - ret - 6 - col < 0))
              return NULL;
          if (col > 0xFFFD)       /* can't happen */
              return NULL;
  
          s2n(TLSEXT_TYPE_opaque_prf_input, ret);
          s2n(col + 2, ret);
          s2n(col, ret);
          memcpy(ret, s->s3->client_opaque_prf_input, col);
          ret += col;
      }
  # endif
  
      if (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp) {
          int i;
          long extlen, idlen, itmp;
          OCSP_RESPID *id;
  
          idlen = 0;
          for (i = 0; i < sk_OCSP_RESPID_num(s->tlsext_ocsp_ids); i++) {
              id = sk_OCSP_RESPID_value(s->tlsext_ocsp_ids, i);
              itmp = i2d_OCSP_RESPID(id, NULL);
              if (itmp <= 0)
                  return NULL;
              idlen += itmp + 2;
          }
  
          if (s->tlsext_ocsp_exts) {
              extlen = i2d_X509_EXTENSIONS(s->tlsext_ocsp_exts, NULL);
              if (extlen < 0)
                  return NULL;
          } else
              extlen = 0;
  
          if ((long)(limit - ret - 7 - extlen - idlen) < 0)
              return NULL;
          s2n(TLSEXT_TYPE_status_request, ret);
          if (extlen + idlen > 0xFFF0)
              return NULL;
          s2n(extlen + idlen + 5, ret);
          *(ret++) = TLSEXT_STATUSTYPE_ocsp;
          s2n(idlen, ret);
          for (i = 0; i < sk_OCSP_RESPID_num(s->tlsext_ocsp_ids); i++) {
              /* save position of id len */
              unsigned char *q = ret;
              id = sk_OCSP_RESPID_value(s->tlsext_ocsp_ids, i);
              /* skip over id len */
              ret += 2;
              itmp = i2d_OCSP_RESPID(id, &ret);
              /* write id len */
              s2n(itmp, q);
          }
          s2n(extlen, ret);
          if (extlen > 0)
              i2d_X509_EXTENSIONS(s->tlsext_ocsp_exts, &ret);
      }
  # ifndef OPENSSL_NO_HEARTBEATS
      /* Add Heartbeat extension */
      if ((limit - ret - 4 - 1) < 0)
          return NULL;
      s2n(TLSEXT_TYPE_heartbeat, ret);
      s2n(1, ret);
      /*-
       * Set mode:
       * 1: peer may send requests
       * 2: peer not allowed to send requests
       */
      if (s->tlsext_heartbeat & SSL_TLSEXT_HB_DONT_RECV_REQUESTS)
          *(ret++) = SSL_TLSEXT_HB_DONT_SEND_REQUESTS;
      else
          *(ret++) = SSL_TLSEXT_HB_ENABLED;
  # endif
  
  # ifndef OPENSSL_NO_NEXTPROTONEG
      if (s->ctx->next_proto_select_cb && !s->s3->tmp.finish_md_len) {
          /*
           * The client advertises an emtpy extension to indicate its support
           * for Next Protocol Negotiation
           */
          if (limit - ret - 4 < 0)
              return NULL;
          s2n(TLSEXT_TYPE_next_proto_neg, ret);
          s2n(0, ret);
      }
  # endif
  
      if (s->alpn_client_proto_list && !s->s3->tmp.finish_md_len) {
          if ((size_t)(limit - ret) < 6 + s->alpn_client_proto_list_len)
              return NULL;
          s2n(TLSEXT_TYPE_application_layer_protocol_negotiation, ret);
          s2n(2 + s->alpn_client_proto_list_len, ret);
          s2n(s->alpn_client_proto_list_len, ret);
          memcpy(ret, s->alpn_client_proto_list, s->alpn_client_proto_list_len);
          ret += s->alpn_client_proto_list_len;
          s->cert->alpn_sent = 1;
      }
  # ifndef OPENSSL_NO_SRTP
      if (SSL_IS_DTLS(s) && SSL_get_srtp_profiles(s)) {
          int el;
  
          ssl_add_clienthello_use_srtp_ext(s, 0, &el, 0);
  
          if ((limit - ret - 4 - el) < 0)
              return NULL;
  
          s2n(TLSEXT_TYPE_use_srtp, ret);
          s2n(el, ret);
  
          if (ssl_add_clienthello_use_srtp_ext(s, ret, &el, el)) {
              SSLerr(SSL_F_SSL_ADD_CLIENTHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
          ret += el;
      }
  # endif
      custom_ext_init(&s->cert->cli_ext);
      /* Add custom TLS Extensions to ClientHello */
      if (!custom_ext_add(s, 0, &ret, limit, al))
          return NULL;
  
      /*
       * Add padding to workaround bugs in F5 terminators. See
       * https://tools.ietf.org/html/draft-agl-tls-padding-03 NB: because this
       * code works out the length of all existing extensions it MUST always
       * appear last.
       */
      if (s->options & SSL_OP_TLSEXT_PADDING) {
          int hlen = ret - (unsigned char *)s->init_buf->data;
          /*
           * The code in s23_clnt.c to build ClientHello messages includes the
           * 5-byte record header in the buffer, while the code in s3_clnt.c
           * does not.
           */
          if (s->state == SSL23_ST_CW_CLNT_HELLO_A)
              hlen -= 5;
          if (hlen > 0xff && hlen < 0x200) {
              hlen = 0x200 - hlen;
              if (hlen >= 4)
                  hlen -= 4;
              else
                  hlen = 0;
  
              s2n(TLSEXT_TYPE_padding, ret);
              s2n(hlen, ret);
              memset(ret, 0, hlen);
              ret += hlen;
          }
      }
  
      if ((extdatalen = ret - orig - 2) == 0)
          return orig;
  
      s2n(extdatalen, orig);
      return ret;
  }
  
  unsigned char *ssl_add_serverhello_tlsext(SSL *s, unsigned char *buf,
                                            unsigned char *limit, int *al)
  {
      int extdatalen = 0;
      unsigned char *orig = buf;
      unsigned char *ret = buf;
  # ifndef OPENSSL_NO_NEXTPROTONEG
      int next_proto_neg_seen;
  # endif
  # ifndef OPENSSL_NO_EC
      unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
      unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
      int using_ecc = (alg_k & (SSL_kEECDH | SSL_kECDHr | SSL_kECDHe))
          || (alg_a & SSL_aECDSA);
      using_ecc = using_ecc && (s->session->tlsext_ecpointformatlist != NULL);
  # endif
      /*
       * don't add extensions for SSLv3, unless doing secure renegotiation
       */
      if (s->version == SSL3_VERSION && !s->s3->send_connection_binding)
          return orig;
  
      ret += 2;
      if (ret >= limit)
          return NULL;            /* this really never occurs, but ... */
  
      if (!s->hit && s->servername_done == 1
          && s->session->tlsext_hostname != NULL) {
          if ((long)(limit - ret - 4) < 0)
              return NULL;
  
          s2n(TLSEXT_TYPE_server_name, ret);
          s2n(0, ret);
      }
  
      if (s->s3->send_connection_binding) {
          int el;
  
          if (!ssl_add_serverhello_renegotiate_ext(s, 0, &el, 0)) {
              SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
  
          if ((limit - ret - 4 - el) < 0)
              return NULL;
  
          s2n(TLSEXT_TYPE_renegotiate, ret);
          s2n(el, ret);
  
          if (!ssl_add_serverhello_renegotiate_ext(s, ret, &el, el)) {
              SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
  
          ret += el;
      }
  # ifndef OPENSSL_NO_EC
      if (using_ecc) {
          const unsigned char *plist;
          size_t plistlen;
          /*
           * Add TLS extension ECPointFormats to the ServerHello message
           */
          long lenmax;
  
          tls1_get_formatlist(s, &plist, &plistlen);
  
          if ((lenmax = limit - ret - 5) < 0)
              return NULL;
          if (plistlen > (size_t)lenmax)
              return NULL;
          if (plistlen > 255) {
              SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
  
          s2n(TLSEXT_TYPE_ec_point_formats, ret);
          s2n(plistlen + 1, ret);
          *(ret++) = (unsigned char)plistlen;
          memcpy(ret, plist, plistlen);
          ret += plistlen;
  
      }
      /*
       * Currently the server should not respond with a SupportedCurves
       * extension
       */
  # endif                         /* OPENSSL_NO_EC */
  
      if (s->tlsext_ticket_expected && !(SSL_get_options(s) & SSL_OP_NO_TICKET)) {
          if ((long)(limit - ret - 4) < 0)
              return NULL;
          s2n(TLSEXT_TYPE_session_ticket, ret);
          s2n(0, ret);
      }
  
      if (s->tlsext_status_expected) {
          if ((long)(limit - ret - 4) < 0)
              return NULL;
          s2n(TLSEXT_TYPE_status_request, ret);
          s2n(0, ret);
      }
  # ifdef TLSEXT_TYPE_opaque_prf_input
      if (s->s3->server_opaque_prf_input != NULL) {
          size_t sol = s->s3->server_opaque_prf_input_len;
  
          if ((long)(limit - ret - 6 - sol) < 0)
              return NULL;
          if (sol > 0xFFFD)       /* can't happen */
              return NULL;
  
          s2n(TLSEXT_TYPE_opaque_prf_input, ret);
          s2n(sol + 2, ret);
          s2n(sol, ret);
          memcpy(ret, s->s3->server_opaque_prf_input, sol);
          ret += sol;
      }
  # endif
  
  # ifndef OPENSSL_NO_SRTP
      if (SSL_IS_DTLS(s) && s->srtp_profile) {
          int el;
  
          ssl_add_serverhello_use_srtp_ext(s, 0, &el, 0);
  
          if ((limit - ret - 4 - el) < 0)
              return NULL;
  
          s2n(TLSEXT_TYPE_use_srtp, ret);
          s2n(el, ret);
  
          if (ssl_add_serverhello_use_srtp_ext(s, ret, &el, el)) {
              SSLerr(SSL_F_SSL_ADD_SERVERHELLO_TLSEXT, ERR_R_INTERNAL_ERROR);
              return NULL;
          }
          ret += el;
      }
  # endif
  
      if (((s->s3->tmp.new_cipher->id & 0xFFFF) == 0x80
           || (s->s3->tmp.new_cipher->id & 0xFFFF) == 0x81)
          && (SSL_get_options(s) & SSL_OP_CRYPTOPRO_TLSEXT_BUG)) {
          const unsigned char cryptopro_ext[36] = {
              0xfd, 0xe8,         /* 65000 */
              0x00, 0x20,         /* 32 bytes length */
              0x30, 0x1e, 0x30, 0x08, 0x06, 0x06, 0x2a, 0x85,
              0x03, 0x02, 0x02, 0x09, 0x30, 0x08, 0x06, 0x06,
              0x2a, 0x85, 0x03, 0x02, 0x02, 0x16, 0x30, 0x08,
              0x06, 0x06, 0x2a, 0x85, 0x03, 0x02, 0x02, 0x17
          };
          if (limit - ret < 36)
              return NULL;
          memcpy(ret, cryptopro_ext, 36);
          ret += 36;
  
      }
  # ifndef OPENSSL_NO_HEARTBEATS
      /* Add Heartbeat extension if we've received one */
      if (s->tlsext_heartbeat & SSL_TLSEXT_HB_ENABLED) {
          if ((limit - ret - 4 - 1) < 0)
              return NULL;
          s2n(TLSEXT_TYPE_heartbeat, ret);
          s2n(1, ret);
          /*-
           * Set mode:
           * 1: peer may send requests
           * 2: peer not allowed to send requests
           */
          if (s->tlsext_heartbeat & SSL_TLSEXT_HB_DONT_RECV_REQUESTS)
              *(ret++) = SSL_TLSEXT_HB_DONT_SEND_REQUESTS;
          else
              *(ret++) = SSL_TLSEXT_HB_ENABLED;
  
      }
  # endif
  
  # ifndef OPENSSL_NO_NEXTPROTONEG
      next_proto_neg_seen = s->s3->next_proto_neg_seen;
      s->s3->next_proto_neg_seen = 0;
      if (next_proto_neg_seen && s->ctx->next_protos_advertised_cb) {
          const unsigned char *npa;
          unsigned int npalen;
          int r;
  
          r = s->ctx->next_protos_advertised_cb(s, &npa, &npalen,
                                                s->
                                                ctx->next_protos_advertised_cb_arg);
          if (r == SSL_TLSEXT_ERR_OK) {
              if ((long)(limit - ret - 4 - npalen) < 0)
                  return NULL;
              s2n(TLSEXT_TYPE_next_proto_neg, ret);
              s2n(npalen, ret);
              memcpy(ret, npa, npalen);
              ret += npalen;
              s->s3->next_proto_neg_seen = 1;
          }
      }
  # endif
      if (!custom_ext_add(s, 1, &ret, limit, al))
          return NULL;
  
      if (s->s3->alpn_selected) {
          const unsigned char *selected = s->s3->alpn_selected;
          unsigned len = s->s3->alpn_selected_len;
  
          if ((long)(limit - ret - 4 - 2 - 1 - len) < 0)
              return NULL;
          s2n(TLSEXT_TYPE_application_layer_protocol_negotiation, ret);
          s2n(3 + len, ret);
          s2n(1 + len, ret);
          *ret++ = len;
          memcpy(ret, selected, len);
          ret += len;
      }
  
      if ((extdatalen = ret - orig - 2) == 0)
          return orig;
  
      s2n(extdatalen, orig);
      return ret;
  }
  
  # ifndef OPENSSL_NO_EC
  /*-
   * ssl_check_for_safari attempts to fingerprint Safari using OS X
   * SecureTransport using the TLS extension block in |d|, of length |n|.
   * Safari, since 10.6, sends exactly these extensions, in this order:
   *   SNI,
   *   elliptic_curves
   *   ec_point_formats
   *
   * We wish to fingerprint Safari because they broke ECDHE-ECDSA support in 10.8,
   * but they advertise support. So enabling ECDHE-ECDSA ciphers breaks them.
   * Sadly we cannot differentiate 10.6, 10.7 and 10.8.4 (which work), from
   * 10.8..10.8.3 (which don't work).
   */
  static void ssl_check_for_safari(SSL *s, const unsigned char *data,
                                   const unsigned char *limit)
  {
      unsigned short type, size;
      static const unsigned char kSafariExtensionsBlock[] = {
          0x00, 0x0a,             /* elliptic_curves extension */
          0x00, 0x08,             /* 8 bytes */
          0x00, 0x06,             /* 6 bytes of curve ids */
          0x00, 0x17,             /* P-256 */
          0x00, 0x18,             /* P-384 */
          0x00, 0x19,             /* P-521 */
  
          0x00, 0x0b,             /* ec_point_formats */
          0x00, 0x02,             /* 2 bytes */
          0x01,                   /* 1 point format */
          0x00,                   /* uncompressed */
      };
  
      /* The following is only present in TLS 1.2 */
      static const unsigned char kSafariTLS12ExtensionsBlock[] = {
          0x00, 0x0d,             /* signature_algorithms */
          0x00, 0x0c,             /* 12 bytes */
          0x00, 0x0a,             /* 10 bytes */
          0x05, 0x01,             /* SHA-384/RSA */
          0x04, 0x01,             /* SHA-256/RSA */
          0x02, 0x01,             /* SHA-1/RSA */
          0x04, 0x03,             /* SHA-256/ECDSA */
          0x02, 0x03,             /* SHA-1/ECDSA */
      };
  
      if (limit - data <= 2)
          return;
      data += 2;
  
      if (limit - data < 4)
          return;
      n2s(data, type);
      n2s(data, size);
  
      if (type != TLSEXT_TYPE_server_name)
          return;
  
      if (limit - data < size)
          return;
      data += size;
  
      if (TLS1_get_client_version(s) >= TLS1_2_VERSION) {
          const size_t len1 = sizeof(kSafariExtensionsBlock);
          const size_t len2 = sizeof(kSafariTLS12ExtensionsBlock);
  
          if (limit - data != (int)(len1 + len2))
              return;
          if (memcmp(data, kSafariExtensionsBlock, len1) != 0)
              return;
          if (memcmp(data + len1, kSafariTLS12ExtensionsBlock, len2) != 0)
              return;
      } else {
          const size_t len = sizeof(kSafariExtensionsBlock);
  
          if (limit - data != (int)(len))
              return;
          if (memcmp(data, kSafariExtensionsBlock, len) != 0)
              return;
      }
  
      s->s3->is_probably_safari = 1;
  }
  # endif                         /* !OPENSSL_NO_EC */
  
  /*
   * tls1_alpn_handle_client_hello is called to save the ALPN extension in a
   * ClientHello.  data: the contents of the extension, not including the type
   * and length.  data_len: the number of bytes in |data| al: a pointer to the
   * alert value to send in the event of a non-zero return.  returns: 0 on
   * success.
   */
  static int tls1_alpn_handle_client_hello(SSL *s, const unsigned char *data,
                                           unsigned data_len, int *al)
  {
      unsigned i;
      unsigned proto_len;
  
      if (data_len < 2)
          goto parse_error;
  
      /*
       * data should contain a uint16 length followed by a series of 8-bit,
       * length-prefixed strings.
       */
      i = ((unsigned)data[0]) << 8 | ((unsigned)data[1]);
      data_len -= 2;
      data += 2;
      if (data_len != i)
          goto parse_error;
  
      if (data_len < 2)
          goto parse_error;
  
      for (i = 0; i < data_len;) {
          proto_len = data[i];
          i++;
  
          if (proto_len == 0)
              goto parse_error;
  
          if (i + proto_len < i || i + proto_len > data_len)
              goto parse_error;
  
          i += proto_len;
      }
  
      if (s->cert->alpn_proposed != NULL)
          OPENSSL_free(s->cert->alpn_proposed);
      s->cert->alpn_proposed = OPENSSL_malloc(data_len);
      if (s->cert->alpn_proposed == NULL) {
          *al = SSL_AD_INTERNAL_ERROR;
          return -1;
      }
      memcpy(s->cert->alpn_proposed, data, data_len);
      s->cert->alpn_proposed_len = data_len;
      return 0;
  
   parse_error:
      *al = SSL_AD_DECODE_ERROR;
      return -1;
  }
  
  /*
   * Process the ALPN extension in a ClientHello.
   * ret: a pointer to the TLSEXT return value: SSL_TLSEXT_ERR_*
   * al: a pointer to the alert value to send in the event of a failure.
   * returns 1 on success, 0 on failure: al/ret set only on failure
   */
  static int tls1_alpn_handle_client_hello_late(SSL *s, int *ret, int *al)
  {
      const unsigned char *selected = NULL;
      unsigned char selected_len = 0;
  
      if (s->ctx->alpn_select_cb != NULL && s->cert->alpn_proposed != NULL) {
          int r = s->ctx->alpn_select_cb(s, &selected, &selected_len,
                                         s->cert->alpn_proposed,
                                         s->cert->alpn_proposed_len,
                                         s->ctx->alpn_select_cb_arg);
  
          if (r == SSL_TLSEXT_ERR_OK) {
              OPENSSL_free(s->s3->alpn_selected);
              s->s3->alpn_selected = OPENSSL_malloc(selected_len);
              if (s->s3->alpn_selected == NULL) {
                  *al = SSL_AD_INTERNAL_ERROR;
                  *ret = SSL_TLSEXT_ERR_ALERT_FATAL;
                  return 0;
              }
              memcpy(s->s3->alpn_selected, selected, selected_len);
              s->s3->alpn_selected_len = selected_len;
  # ifndef OPENSSL_NO_NEXTPROTONEG
              /* ALPN takes precedence over NPN. */
              s->s3->next_proto_neg_seen = 0;
  # endif
          }
      }
  
      return 1;
  }
  
  static int ssl_scan_clienthello_tlsext(SSL *s, unsigned char **p,
                                         unsigned char *limit, int *al)
  {
      unsigned short type;
      unsigned short size;
      unsigned short len;
      unsigned char *data = *p;
      int renegotiate_seen = 0;
  
      s->servername_done = 0;
      s->tlsext_status_type = -1;
  # ifndef OPENSSL_NO_NEXTPROTONEG
      s->s3->next_proto_neg_seen = 0;
  # endif
  
      if (s->s3->alpn_selected) {
          OPENSSL_free(s->s3->alpn_selected);
          s->s3->alpn_selected = NULL;
      }
      s->s3->alpn_selected_len = 0;
      if (s->cert->alpn_proposed) {
          OPENSSL_free(s->cert->alpn_proposed);
          s->cert->alpn_proposed = NULL;
      }
      s->cert->alpn_proposed_len = 0;
  # ifndef OPENSSL_NO_HEARTBEATS
      s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED |
                               SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
  # endif
  
  # ifndef OPENSSL_NO_EC
      if (s->options & SSL_OP_SAFARI_ECDHE_ECDSA_BUG)
          ssl_check_for_safari(s, data, limit);
  # endif                         /* !OPENSSL_NO_EC */
  
      /* Clear any signature algorithms extension received */
      if (s->cert->peer_sigalgs) {
          OPENSSL_free(s->cert->peer_sigalgs);
          s->cert->peer_sigalgs = NULL;
      }
  # ifndef OPENSSL_NO_SRP
      if (s->srp_ctx.login != NULL) {
          OPENSSL_free(s->srp_ctx.login);
          s->srp_ctx.login = NULL;
      }
  # endif
  
      s->srtp_profile = NULL;
  
      if (data == limit)
          goto ri_check;
  
      if (limit - data < 2)
          goto err;
  
      n2s(data, len);
  
      if (limit - data != len)
          goto err;
  
      while (limit - data >= 4) {
          n2s(data, type);
          n2s(data, size);
  
          if (limit - data < size)
              goto err;
  # if 0
          fprintf(stderr, "Received extension type %d size %d\n", type, size);
  # endif
          if (s->tlsext_debug_cb)
              s->tlsext_debug_cb(s, 0, type, data, size, s->tlsext_debug_arg);
  /*-
   * The servername extension is treated as follows:
   *
   * - Only the hostname type is supported with a maximum length of 255.
   * - The servername is rejected if too long or if it contains zeros,
   *   in which case an fatal alert is generated.
   * - The servername field is maintained together with the session cache.
   * - When a session is resumed, the servername call back invoked in order
   *   to allow the application to position itself to the right context.
   * - The servername is acknowledged if it is new for a session or when
   *   it is identical to a previously used for the same session.
   *   Applications can control the behaviour.  They can at any time
   *   set a 'desirable' servername for a new SSL object. This can be the
   *   case for example with HTTPS when a Host: header field is received and
   *   a renegotiation is requested. In this case, a possible servername
   *   presented in the new client hello is only acknowledged if it matches
   *   the value of the Host: field.
   * - Applications must  use SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
   *   if they provide for changing an explicit servername context for the
   *   session, i.e. when the session has been established with a servername
   *   extension.
   * - On session reconnect, the servername extension may be absent.
   *
   */
  
          if (type == TLSEXT_TYPE_server_name) {
              unsigned char *sdata;
              int servname_type;
              int dsize;
  
              if (size < 2)
                  goto err;
              n2s(data, dsize);
              size -= 2;
              if (dsize > size)
                  goto err;
  
              sdata = data;
              while (dsize > 3) {
                  servname_type = *(sdata++);
                  n2s(sdata, len);
                  dsize -= 3;
  
                  if (len > dsize)
                      goto err;
  
                  if (s->servername_done == 0)
                      switch (servname_type) {
                      case TLSEXT_NAMETYPE_host_name:
                          if (!s->hit) {
                              if (s->session->tlsext_hostname)
                                  goto err;
  
                              if (len > TLSEXT_MAXLEN_host_name) {
                                  *al = TLS1_AD_UNRECOGNIZED_NAME;
                                  return 0;
                              }
                              if ((s->session->tlsext_hostname =
                                   OPENSSL_malloc(len + 1)) == NULL) {
                                  *al = TLS1_AD_INTERNAL_ERROR;
                                  return 0;
                              }
                              memcpy(s->session->tlsext_hostname, sdata, len);
                              s->session->tlsext_hostname[len] = '\0';
                              if (strlen(s->session->tlsext_hostname) != len) {
                                  OPENSSL_free(s->session->tlsext_hostname);
                                  s->session->tlsext_hostname = NULL;
                                  *al = TLS1_AD_UNRECOGNIZED_NAME;
                                  return 0;
                              }
                              s->servername_done = 1;
  
                          } else
                              s->servername_done = s->session->tlsext_hostname
                                  && strlen(s->session->tlsext_hostname) == len
                                  && strncmp(s->session->tlsext_hostname,
                                             (char *)sdata, len) == 0;
  
                          break;
  
                      default:
                          break;
                      }
  
                  dsize -= len;
              }
              if (dsize != 0)
                  goto err;
  
          }
  # ifndef OPENSSL_NO_SRP
          else if (type == TLSEXT_TYPE_srp) {
              if (size == 0 || ((len = data[0])) != (size - 1))
                  goto err;
              if (s->srp_ctx.login != NULL)
                  goto err;
              if ((s->srp_ctx.login = OPENSSL_malloc(len + 1)) == NULL)
                  return -1;
              memcpy(s->srp_ctx.login, &data[1], len);
              s->srp_ctx.login[len] = '\0';
  
              if (strlen(s->srp_ctx.login) != len)
                  goto err;
          }
  # endif
  
  # ifndef OPENSSL_NO_EC
          else if (type == TLSEXT_TYPE_ec_point_formats) {
              unsigned char *sdata = data;
              int ecpointformatlist_length = *(sdata++);
  
              if (ecpointformatlist_length != size - 1 ||
                  ecpointformatlist_length < 1)
                  goto err;
              if (!s->hit) {
                  if (s->session->tlsext_ecpointformatlist) {
                      OPENSSL_free(s->session->tlsext_ecpointformatlist);
                      s->session->tlsext_ecpointformatlist = NULL;
                  }
                  s->session->tlsext_ecpointformatlist_length = 0;
                  if ((s->session->tlsext_ecpointformatlist =
                       OPENSSL_malloc(ecpointformatlist_length)) == NULL) {
                      *al = TLS1_AD_INTERNAL_ERROR;
                      return 0;
                  }
                  s->session->tlsext_ecpointformatlist_length =
                      ecpointformatlist_length;
                  memcpy(s->session->tlsext_ecpointformatlist, sdata,
                         ecpointformatlist_length);
              }
  #  if 0
              fprintf(stderr,
                      "ssl_parse_clienthello_tlsext s->session->tlsext_ecpointformatlist (length=%i) ",
                      s->session->tlsext_ecpointformatlist_length);
              sdata = s->session->tlsext_ecpointformatlist;
              for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++)
                  fprintf(stderr, "%i ", *(sdata++));
              fprintf(stderr, "\n");
  #  endif
          } else if (type == TLSEXT_TYPE_elliptic_curves) {
              unsigned char *sdata = data;
              int ellipticcurvelist_length = (*(sdata++) << 8);
              ellipticcurvelist_length += (*(sdata++));
  
              if (ellipticcurvelist_length != size - 2 ||
                  ellipticcurvelist_length < 1 ||
                  /* Each NamedCurve is 2 bytes. */
                  ellipticcurvelist_length & 1)
                      goto err;
  
              if (!s->hit) {
                  if (s->session->tlsext_ellipticcurvelist)
                      goto err;
  
                  s->session->tlsext_ellipticcurvelist_length = 0;
                  if ((s->session->tlsext_ellipticcurvelist =
                       OPENSSL_malloc(ellipticcurvelist_length)) == NULL) {
                      *al = TLS1_AD_INTERNAL_ERROR;
                      return 0;
                  }
                  s->session->tlsext_ellipticcurvelist_length =
                      ellipticcurvelist_length;
                  memcpy(s->session->tlsext_ellipticcurvelist, sdata,
                         ellipticcurvelist_length);
              }
  #  if 0
              fprintf(stderr,
                      "ssl_parse_clienthello_tlsext s->session->tlsext_ellipticcurvelist (length=%i) ",
                      s->session->tlsext_ellipticcurvelist_length);
              sdata = s->session->tlsext_ellipticcurvelist;
              for (i = 0; i < s->session->tlsext_ellipticcurvelist_length; i++)
                  fprintf(stderr, "%i ", *(sdata++));
              fprintf(stderr, "\n");
  #  endif
          }
  # endif                         /* OPENSSL_NO_EC */
  # ifdef TLSEXT_TYPE_opaque_prf_input
          else if (type == TLSEXT_TYPE_opaque_prf_input) {
              unsigned char *sdata = data;
  
              if (size < 2) {
                  *al = SSL_AD_DECODE_ERROR;
                  return 0;
              }
              n2s(sdata, s->s3->client_opaque_prf_input_len);
              if (s->s3->client_opaque_prf_input_len != size - 2) {
                  *al = SSL_AD_DECODE_ERROR;
                  return 0;
              }
  
              if (s->s3->client_opaque_prf_input != NULL) {
                  /* shouldn't really happen */
                  OPENSSL_free(s->s3->client_opaque_prf_input);
              }
  
              /* dummy byte just to get non-NULL */
              if (s->s3->client_opaque_prf_input_len == 0)
                  s->s3->client_opaque_prf_input = OPENSSL_malloc(1);
              else
                  s->s3->client_opaque_prf_input =
                      BUF_memdup(sdata, s->s3->client_opaque_prf_input_len);
              if (s->s3->client_opaque_prf_input == NULL) {
                  *al = TLS1_AD_INTERNAL_ERROR;
                  return 0;
              }
          }
  # endif
          else if (type == TLSEXT_TYPE_session_ticket) {
              if (s->tls_session_ticket_ext_cb &&
                  !s->tls_session_ticket_ext_cb(s, data, size,
                                                s->tls_session_ticket_ext_cb_arg))
              {
                  *al = TLS1_AD_INTERNAL_ERROR;
                  return 0;
              }
          } else if (type == TLSEXT_TYPE_renegotiate) {
              if (!ssl_parse_clienthello_renegotiate_ext(s, data, size, al))
                  return 0;
              renegotiate_seen = 1;
          } else if (type == TLSEXT_TYPE_signature_algorithms) {
              int dsize;
              if (s->cert->peer_sigalgs || size < 2)
                  goto err;
              n2s(data, dsize);
              size -= 2;
              if (dsize != size || dsize & 1 || !dsize)
                  goto err;
              if (!tls1_save_sigalgs(s, data, dsize))
                  goto err;
          } else if (type == TLSEXT_TYPE_status_request) {
  
              if (size < 5)
                  goto err;
  
              s->tlsext_status_type = *data++;
              size--;
              if (s->tlsext_status_type == TLSEXT_STATUSTYPE_ocsp) {
                  const unsigned char *sdata;
                  int dsize;
                  /* Read in responder_id_list */
                  n2s(data, dsize);
                  size -= 2;
                  if (dsize > size)
                      goto err;
                  while (dsize > 0) {
                      OCSP_RESPID *id;
                      int idsize;
                      if (dsize < 4)
                          goto err;
                      n2s(data, idsize);
                      dsize -= 2 + idsize;
                      size -= 2 + idsize;
                      if (dsize < 0)
                          goto err;
                      sdata = data;
                      data += idsize;
                      id = d2i_OCSP_RESPID(NULL, &sdata, idsize);
                      if (!id)
                          goto err;
                      if (data != sdata) {
                          OCSP_RESPID_free(id);
                          goto err;
                      }
                      if (!s->tlsext_ocsp_ids
                          && !(s->tlsext_ocsp_ids =
                               sk_OCSP_RESPID_new_null())) {
                          OCSP_RESPID_free(id);
                          *al = SSL_AD_INTERNAL_ERROR;
                          return 0;
                      }
                      if (!sk_OCSP_RESPID_push(s->tlsext_ocsp_ids, id)) {
                          OCSP_RESPID_free(id);
                          *al = SSL_AD_INTERNAL_ERROR;
                          return 0;
                      }
                  }
  
                  /* Read in request_extensions */
                  if (size < 2)
                      goto err;
                  n2s(data, dsize);
                  size -= 2;
                  if (dsize != size)
                      goto err;
                  sdata = data;
                  if (dsize > 0) {
                      if (s->tlsext_ocsp_exts) {
                          sk_X509_EXTENSION_pop_free(s->tlsext_ocsp_exts,
                                                     X509_EXTENSION_free);
                      }
  
                      s->tlsext_ocsp_exts =
                          d2i_X509_EXTENSIONS(NULL, &sdata, dsize);
                      if (!s->tlsext_ocsp_exts || (data + dsize != sdata))
                          goto err;
                  }
              }
              /*
               * We don't know what to do with any other type * so ignore it.
               */
              else
                  s->tlsext_status_type = -1;
          }
  # ifndef OPENSSL_NO_HEARTBEATS
          else if (type == TLSEXT_TYPE_heartbeat) {
              switch (data[0]) {
              case 0x01:         /* Client allows us to send HB requests */
                  s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                  break;
              case 0x02:         /* Client doesn't accept HB requests */
                  s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                  s->tlsext_heartbeat |= SSL_TLSEXT_HB_DONT_SEND_REQUESTS;
                  break;
              default:
                  *al = SSL_AD_ILLEGAL_PARAMETER;
                  return 0;
              }
          }
  # endif
  # ifndef OPENSSL_NO_NEXTPROTONEG
          else if (type == TLSEXT_TYPE_next_proto_neg &&
                   s->s3->tmp.finish_md_len == 0) {
              /*-
               * We shouldn't accept this extension on a
               * renegotiation.
               *
               * s->new_session will be set on renegotiation, but we
               * probably shouldn't rely that it couldn't be set on
               * the initial renegotation too in certain cases (when
               * there's some other reason to disallow resuming an
               * earlier session -- the current code won't be doing
               * anything like that, but this might change).
               *
               * A valid sign that there's been a previous handshake
               * in this connection is if s->s3->tmp.finish_md_len >
               * 0.  (We are talking about a check that will happen
               * in the Hello protocol round, well before a new
               * Finished message could have been computed.)
               */
              s->s3->next_proto_neg_seen = 1;
          }
  # endif
  
          else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation &&
                   s->s3->tmp.finish_md_len == 0) {
              if (tls1_alpn_handle_client_hello(s, data, size, al) != 0)
                  return 0;
          }
  
          /* session ticket processed earlier */
  # ifndef OPENSSL_NO_SRTP
          else if (SSL_IS_DTLS(s) && SSL_get_srtp_profiles(s)
                   && type == TLSEXT_TYPE_use_srtp) {
              if (ssl_parse_clienthello_use_srtp_ext(s, data, size, al))
                  return 0;
          }
  # endif
  
          data += size;
      }
  
      /* Spurious data on the end */
      if (data != limit)
          goto err;
  
      *p = data;
  
   ri_check:
  
      /* Need RI if renegotiating */
  
      if (!renegotiate_seen && s->renegotiate &&
          !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
          *al = SSL_AD_HANDSHAKE_FAILURE;
          SSLerr(SSL_F_SSL_SCAN_CLIENTHELLO_TLSEXT,
                 SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
          return 0;
      }
  
      return 1;
  err:
      *al = SSL_AD_DECODE_ERROR;
      return 0;
  }
  
  /*
   * Parse any custom extensions found.  "data" is the start of the extension data
   * and "limit" is the end of the record. TODO: add strict syntax checking.
   */
  
  static int ssl_scan_clienthello_custom_tlsext(SSL *s,
                                                const unsigned char *data,
                                                const unsigned char *limit,
                                                int *al)
  {
      unsigned short type, size, len;
      /* If resumed session or no custom extensions nothing to do */
      if (s->hit || s->cert->srv_ext.meths_count == 0)
          return 1;
  
      if (limit - data <= 2)
          return 1;
      n2s(data, len);
  
      if (limit - data < len)
          return 1;
  
      while (limit - data >= 4) {
          n2s(data, type);
          n2s(data, size);
  
          if (limit - data < size)
              return 1;
          if (custom_ext_parse(s, 1 /* server */ , type, data, size, al) <= 0)
              return 0;
  
          data += size;
      }
  
      return 1;
  }
  
  int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p,
                                   unsigned char *limit)
  {
      int al = -1;
      unsigned char *ptmp = *p;
      /*
       * Internally supported extensions are parsed first so SNI can be handled
       * before custom extensions. An application processing SNI will typically
       * switch the parent context using SSL_set_SSL_CTX and custom extensions
       * need to be handled by the new SSL_CTX structure.
       */
      if (ssl_scan_clienthello_tlsext(s, p, limit, &al) <= 0) {
          ssl3_send_alert(s, SSL3_AL_FATAL, al);
          return 0;
      }
  
      if (ssl_check_clienthello_tlsext_early(s) <= 0) {
          SSLerr(SSL_F_SSL_PARSE_CLIENTHELLO_TLSEXT, SSL_R_CLIENTHELLO_TLSEXT);
          return 0;
      }
  
      custom_ext_init(&s->cert->srv_ext);
      if (ssl_scan_clienthello_custom_tlsext(s, ptmp, limit, &al) <= 0) {
          ssl3_send_alert(s, SSL3_AL_FATAL, al);
          return 0;
      }
  
      return 1;
  }
  
  # ifndef OPENSSL_NO_NEXTPROTONEG
  /*
   * ssl_next_proto_validate validates a Next Protocol Negotiation block. No
   * elements of zero length are allowed and the set of elements must exactly
   * fill the length of the block.
   */
  static char ssl_next_proto_validate(unsigned char *d, unsigned len)
  {
      unsigned int off = 0;
  
      while (off < len) {
          if (d[off] == 0)
              return 0;
          off += d[off];
          off++;
      }
  
      return off == len;
  }
  # endif
  
  static int ssl_scan_serverhello_tlsext(SSL *s, unsigned char **p,
                                         unsigned char *d, int n, int *al)
  {
      unsigned short length;
      unsigned short type;
      unsigned short size;
      unsigned char *data = *p;
      int tlsext_servername = 0;
      int renegotiate_seen = 0;
  
  # ifndef OPENSSL_NO_NEXTPROTONEG
      s->s3->next_proto_neg_seen = 0;
  # endif
      s->tlsext_ticket_expected = 0;
  
      if (s->s3->alpn_selected) {
          OPENSSL_free(s->s3->alpn_selected);
          s->s3->alpn_selected = NULL;
      }
  # ifndef OPENSSL_NO_HEARTBEATS
      s->tlsext_heartbeat &= ~(SSL_TLSEXT_HB_ENABLED |
                               SSL_TLSEXT_HB_DONT_SEND_REQUESTS);
  # endif
  
      if ((d + n) - data <= 2)
          goto ri_check;
  
      n2s(data, length);
      if ((d + n) - data != length) {
          *al = SSL_AD_DECODE_ERROR;
          return 0;
      }
  
      while ((d + n) - data >= 4) {
          n2s(data, type);
          n2s(data, size);
  
          if ((d + n) - data < size)
              goto ri_check;
  
          if (s->tlsext_debug_cb)
              s->tlsext_debug_cb(s, 1, type, data, size, s->tlsext_debug_arg);
  
          if (type == TLSEXT_TYPE_server_name) {
              if (s->tlsext_hostname == NULL || size > 0) {
                  *al = TLS1_AD_UNRECOGNIZED_NAME;
                  return 0;
              }
              tlsext_servername = 1;
          }
  # ifndef OPENSSL_NO_EC
          else if (type == TLSEXT_TYPE_ec_point_formats) {
              unsigned char *sdata = data;
              int ecpointformatlist_length = *(sdata++);
  
              if (ecpointformatlist_length != size - 1) {
                  *al = TLS1_AD_DECODE_ERROR;
                  return 0;
              }
              if (!s->hit) {
                  s->session->tlsext_ecpointformatlist_length = 0;
                  if (s->session->tlsext_ecpointformatlist != NULL)
                      OPENSSL_free(s->session->tlsext_ecpointformatlist);
                  if ((s->session->tlsext_ecpointformatlist =
                       OPENSSL_malloc(ecpointformatlist_length)) == NULL) {
                      *al = TLS1_AD_INTERNAL_ERROR;
                      return 0;
                  }
                  s->session->tlsext_ecpointformatlist_length =
                      ecpointformatlist_length;
                  memcpy(s->session->tlsext_ecpointformatlist, sdata,
                         ecpointformatlist_length);
              }
  #  if 0
              fprintf(stderr,
                      "ssl_parse_serverhello_tlsext s->session->tlsext_ecpointformatlist ");
              sdata = s->session->tlsext_ecpointformatlist;
              for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++)
                  fprintf(stderr, "%i ", *(sdata++));
              fprintf(stderr, "\n");
  #  endif
          }
  # endif                         /* OPENSSL_NO_EC */
  
          else if (type == TLSEXT_TYPE_session_ticket) {
              if (s->tls_session_ticket_ext_cb &&
                  !s->tls_session_ticket_ext_cb(s, data, size,
                                                s->tls_session_ticket_ext_cb_arg))
              {
                  *al = TLS1_AD_INTERNAL_ERROR;
                  return 0;
              }
              if ((SSL_get_options(s) & SSL_OP_NO_TICKET)
                  || (size > 0)) {
                  *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                  return 0;
              }
              s->tlsext_ticket_expected = 1;
          }
  # ifdef TLSEXT_TYPE_opaque_prf_input
          else if (type == TLSEXT_TYPE_opaque_prf_input) {
              unsigned char *sdata = data;
  
              if (size < 2) {
                  *al = SSL_AD_DECODE_ERROR;
                  return 0;
              }
              n2s(sdata, s->s3->server_opaque_prf_input_len);
              if (s->s3->server_opaque_prf_input_len != size - 2) {
                  *al = SSL_AD_DECODE_ERROR;
                  return 0;
              }
  
              if (s->s3->server_opaque_prf_input != NULL) {
                  /* shouldn't really happen */
                  OPENSSL_free(s->s3->server_opaque_prf_input);
              }
              if (s->s3->server_opaque_prf_input_len == 0) {
                  /* dummy byte just to get non-NULL */
                  s->s3->server_opaque_prf_input = OPENSSL_malloc(1);
              } else {
                  s->s3->server_opaque_prf_input =
                      BUF_memdup(sdata, s->s3->server_opaque_prf_input_len);
              }
  
              if (s->s3->server_opaque_prf_input == NULL) {
                  *al = TLS1_AD_INTERNAL_ERROR;
                  return 0;
              }
          }
  # endif
          else if (type == TLSEXT_TYPE_status_request) {
              /*
               * MUST be empty and only sent if we've requested a status
               * request message.
               */
              if ((s->tlsext_status_type == -1) || (size > 0)) {
                  *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                  return 0;
              }
              /* Set flag to expect CertificateStatus message */
              s->tlsext_status_expected = 1;
          }
  # ifndef OPENSSL_NO_NEXTPROTONEG
          else if (type == TLSEXT_TYPE_next_proto_neg &&
                   s->s3->tmp.finish_md_len == 0) {
              unsigned char *selected;
              unsigned char selected_len;
  
              /* We must have requested it. */
              if (s->ctx->next_proto_select_cb == NULL) {
                  *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                  return 0;
              }
              /* The data must be valid */
              if (!ssl_next_proto_validate(data, size)) {
                  *al = TLS1_AD_DECODE_ERROR;
                  return 0;
              }
              if (s->
                  ctx->next_proto_select_cb(s, &selected, &selected_len, data,
                                            size,
                                            s->ctx->next_proto_select_cb_arg) !=
                  SSL_TLSEXT_ERR_OK) {
                  *al = TLS1_AD_INTERNAL_ERROR;
                  return 0;
              }
              s->next_proto_negotiated = OPENSSL_malloc(selected_len);
              if (!s->next_proto_negotiated) {
                  *al = TLS1_AD_INTERNAL_ERROR;
                  return 0;
              }
              memcpy(s->next_proto_negotiated, selected, selected_len);
              s->next_proto_negotiated_len = selected_len;
              s->s3->next_proto_neg_seen = 1;
          }
  # endif
  
          else if (type == TLSEXT_TYPE_application_layer_protocol_negotiation) {
              unsigned len;
  
              /* We must have requested it. */
              if (!s->cert->alpn_sent) {
                  *al = TLS1_AD_UNSUPPORTED_EXTENSION;
                  return 0;
              }
              if (size < 4) {
                  *al = TLS1_AD_DECODE_ERROR;
                  return 0;
              }
              /*-
               * The extension data consists of:
               *   uint16 list_length
               *   uint8 proto_length;
               *   uint8 proto[proto_length];
               */
              len = data[0];
              len <<= 8;
              len |= data[1];
              if (len != (unsigned)size - 2) {
                  *al = TLS1_AD_DECODE_ERROR;
                  return 0;
              }
              len = data[2];
              if (len != (unsigned)size - 3) {
                  *al = TLS1_AD_DECODE_ERROR;
                  return 0;
              }
              if (s->s3->alpn_selected)
                  OPENSSL_free(s->s3->alpn_selected);
              s->s3->alpn_selected = OPENSSL_malloc(len);
              if (!s->s3->alpn_selected) {
                  *al = TLS1_AD_INTERNAL_ERROR;
                  return 0;
              }
              memcpy(s->s3->alpn_selected, data + 3, len);
              s->s3->alpn_selected_len = len;
          }
  
          else if (type == TLSEXT_TYPE_renegotiate) {
              if (!ssl_parse_serverhello_renegotiate_ext(s, data, size, al))
                  return 0;
              renegotiate_seen = 1;
          }
  # ifndef OPENSSL_NO_HEARTBEATS
          else if (type == TLSEXT_TYPE_heartbeat) {
              switch (data[0]) {
              case 0x01:         /* Server allows us to send HB requests */
                  s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                  break;
              case 0x02:         /* Server doesn't accept HB requests */
                  s->tlsext_heartbeat |= SSL_TLSEXT_HB_ENABLED;
                  s->tlsext_heartbeat |= SSL_TLSEXT_HB_DONT_SEND_REQUESTS;
                  break;
              default:
                  *al = SSL_AD_ILLEGAL_PARAMETER;
                  return 0;
              }
          }
  # endif
  # ifndef OPENSSL_NO_SRTP
          else if (SSL_IS_DTLS(s) && type == TLSEXT_TYPE_use_srtp) {
              if (ssl_parse_serverhello_use_srtp_ext(s, data, size, al))
                  return 0;
          }
  # endif
          /*
           * If this extension type was not otherwise handled, but matches a
           * custom_cli_ext_record, then send it to the c callback
           */
          else if (custom_ext_parse(s, 0, type, data, size, al) <= 0)
              return 0;
  
          data += size;
      }
  
      if (data != d + n) {
          *al = SSL_AD_DECODE_ERROR;
          return 0;
      }
  
      if (!s->hit && tlsext_servername == 1) {
          if (s->tlsext_hostname) {
              if (s->session->tlsext_hostname == NULL) {
                  s->session->tlsext_hostname = BUF_strdup(s->tlsext_hostname);
                  if (!s->session->tlsext_hostname) {
                      *al = SSL_AD_UNRECOGNIZED_NAME;
                      return 0;
                  }
              } else {
                  *al = SSL_AD_DECODE_ERROR;
                  return 0;
              }
          }
      }
  
      *p = data;
  
   ri_check:
  
      /*
       * Determine if we need to see RI. Strictly speaking if we want to avoid
       * an attack we should *always* see RI even on initial server hello
       * because the client doesn't see any renegotiation during an attack.
       * However this would mean we could not connect to any server which
       * doesn't support RI so for the immediate future tolerate RI absence on
       * initial connect only.
       */
      if (!renegotiate_seen && !(s->options & SSL_OP_LEGACY_SERVER_CONNECT)
          && !(s->options & SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
          *al = SSL_AD_HANDSHAKE_FAILURE;
          SSLerr(SSL_F_SSL_SCAN_SERVERHELLO_TLSEXT,
                 SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
          return 0;
      }
  
      return 1;
  }
  
  int ssl_prepare_clienthello_tlsext(SSL *s)
  {
  
  # ifdef TLSEXT_TYPE_opaque_prf_input
      {
          int r = 1;
  
          if (s->ctx->tlsext_opaque_prf_input_callback != 0) {
              r = s->ctx->tlsext_opaque_prf_input_callback(s, NULL, 0,
                                                           s->
                                                           ctx->tlsext_opaque_prf_input_callback_arg);
              if (!r)
                  return -1;
          }
  
          if (s->tlsext_opaque_prf_input != NULL) {
              if (s->s3->client_opaque_prf_input != NULL) {
                  /* shouldn't really happen */
                  OPENSSL_free(s->s3->client_opaque_prf_input);
              }
  
              if (s->tlsext_opaque_prf_input_len == 0) {
                  /* dummy byte just to get non-NULL */
                  s->s3->client_opaque_prf_input = OPENSSL_malloc(1);
              } else {
                  s->s3->client_opaque_prf_input =
                      BUF_memdup(s->tlsext_opaque_prf_input,
                                 s->tlsext_opaque_prf_input_len);
              }
              if (s->s3->client_opaque_prf_input == NULL) {
                  SSLerr(SSL_F_SSL_PREPARE_CLIENTHELLO_TLSEXT,
                         ERR_R_MALLOC_FAILURE);
                  return -1;
              }
              s->s3->client_opaque_prf_input_len =
                  s->tlsext_opaque_prf_input_len;
          }
  
          if (r == 2)
              /*
               * at callback's request, insist on receiving an appropriate
               * server opaque PRF input
               */
              s->s3->server_opaque_prf_input_len =
                  s->tlsext_opaque_prf_input_len;
      }
  # endif
  
      s->cert->alpn_sent = 0;
      return 1;
  }
  
  int ssl_prepare_serverhello_tlsext(SSL *s)
  {
      return 1;
  }
  
  static int ssl_check_clienthello_tlsext_early(SSL *s)
  {
      int ret = SSL_TLSEXT_ERR_NOACK;
      int al = SSL_AD_UNRECOGNIZED_NAME;
  
  # ifndef OPENSSL_NO_EC
      /*
       * The handling of the ECPointFormats extension is done elsewhere, namely
       * in ssl3_choose_cipher in s3_lib.c.
       */
      /*
       * The handling of the EllipticCurves extension is done elsewhere, namely
       * in ssl3_choose_cipher in s3_lib.c.
       */
  # endif
  
      if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
          ret =
              s->ctx->tlsext_servername_callback(s, &al,
                                                 s->ctx->tlsext_servername_arg);
      else if (s->initial_ctx != NULL
               && s->initial_ctx->tlsext_servername_callback != 0)
          ret =
              s->initial_ctx->tlsext_servername_callback(s, &al,
                                                         s->
                                                         initial_ctx->tlsext_servername_arg);
  
  # ifdef TLSEXT_TYPE_opaque_prf_input
      {
          /*
           * This sort of belongs into ssl_prepare_serverhello_tlsext(), but we
           * might be sending an alert in response to the client hello, so this
           * has to happen here in ssl_check_clienthello_tlsext_early().
           */
  
          int r = 1;
  
          if (s->ctx->tlsext_opaque_prf_input_callback != 0) {
              r = s->ctx->tlsext_opaque_prf_input_callback(s, NULL, 0,
                                                           s->
                                                           ctx->tlsext_opaque_prf_input_callback_arg);
              if (!r) {
                  ret = SSL_TLSEXT_ERR_ALERT_FATAL;
                  al = SSL_AD_INTERNAL_ERROR;
                  goto err;
              }
          }
  
          if (s->s3->server_opaque_prf_input != NULL) {
              /* shouldn't really happen */
              OPENSSL_free(s->s3->server_opaque_prf_input);
          }
          s->s3->server_opaque_prf_input = NULL;
  
          if (s->tlsext_opaque_prf_input != NULL) {
              if (s->s3->client_opaque_prf_input != NULL &&
                  s->s3->client_opaque_prf_input_len ==
                  s->tlsext_opaque_prf_input_len) {
                  /*
                   * can only use this extension if we have a server opaque PRF
                   * input of the same length as the client opaque PRF input!
                   */
  
                  if (s->tlsext_opaque_prf_input_len == 0) {
                      /* dummy byte just to get non-NULL */
                      s->s3->server_opaque_prf_input = OPENSSL_malloc(1);
                  } else {
                      s->s3->server_opaque_prf_input =
                          BUF_memdup(s->tlsext_opaque_prf_input,
                                     s->tlsext_opaque_prf_input_len);
                  }
                  if (s->s3->server_opaque_prf_input == NULL) {
                      ret = SSL_TLSEXT_ERR_ALERT_FATAL;
                      al = SSL_AD_INTERNAL_ERROR;
                      goto err;
                  }
                  s->s3->server_opaque_prf_input_len =
                      s->tlsext_opaque_prf_input_len;
              }
          }
  
          if (r == 2 && s->s3->server_opaque_prf_input == NULL) {
              /*
               * The callback wants to enforce use of the extension, but we
               * can't do that with the client opaque PRF input; abort the
               * handshake.
               */
              ret = SSL_TLSEXT_ERR_ALERT_FATAL;
              al = SSL_AD_HANDSHAKE_FAILURE;
          }
      }
  
   err:
  # endif
      switch (ret) {
      case SSL_TLSEXT_ERR_ALERT_FATAL:
          ssl3_send_alert(s, SSL3_AL_FATAL, al);
          return -1;
  
      case SSL_TLSEXT_ERR_ALERT_WARNING:
          ssl3_send_alert(s, SSL3_AL_WARNING, al);
          return 1;
  
      case SSL_TLSEXT_ERR_NOACK:
          s->servername_done = 0;
      default:
          return 1;
      }
  }
  
  int tls1_set_server_sigalgs(SSL *s)
  {
      int al;
      size_t i;
      /* Clear any shared sigtnature algorithms */
      if (s->cert->shared_sigalgs) {
          OPENSSL_free(s->cert->shared_sigalgs);
          s->cert->shared_sigalgs = NULL;
          s->cert->shared_sigalgslen = 0;
      }
      /* Clear certificate digests and validity flags */
      for (i = 0; i < SSL_PKEY_NUM; i++) {
          s->cert->pkeys[i].digest = NULL;
          s->cert->pkeys[i].valid_flags = 0;
      }
  
      /* If sigalgs received process it. */
      if (s->cert->peer_sigalgs) {
          if (!tls1_process_sigalgs(s)) {
              SSLerr(SSL_F_TLS1_SET_SERVER_SIGALGS, ERR_R_MALLOC_FAILURE);
              al = SSL_AD_INTERNAL_ERROR;
              goto err;
          }
          /* Fatal error is no shared signature algorithms */
          if (!s->cert->shared_sigalgs) {
              SSLerr(SSL_F_TLS1_SET_SERVER_SIGALGS,
                     SSL_R_NO_SHARED_SIGATURE_ALGORITHMS);
              al = SSL_AD_ILLEGAL_PARAMETER;
              goto err;
          }
      } else
          ssl_cert_set_default_md(s->cert);
      return 1;
   err:
      ssl3_send_alert(s, SSL3_AL_FATAL, al);
      return 0;
  }
  
  int ssl_check_clienthello_tlsext_late(SSL *s)
  {
      int ret = SSL_TLSEXT_ERR_OK;
      int al;
  
      /*
       * If status request then ask callback what to do. Note: this must be
       * called after servername callbacks in case the certificate has changed,
       * and must be called after the cipher has been chosen because this may
       * influence which certificate is sent
       */
      if ((s->tlsext_status_type != -1) && s->ctx && s->ctx->tlsext_status_cb) {
          int r;
          CERT_PKEY *certpkey;
          certpkey = ssl_get_server_send_pkey(s);
          /* If no certificate can't return certificate status */
          if (certpkey == NULL) {
              s->tlsext_status_expected = 0;
              return 1;
          }
          /*
           * Set current certificate to one we will use so SSL_get_certificate
           * et al can pick it up.
           */
          s->cert->key = certpkey;
          r = s->ctx->tlsext_status_cb(s, s->ctx->tlsext_status_arg);
          switch (r) {
              /* We don't want to send a status request response */
          case SSL_TLSEXT_ERR_NOACK:
              s->tlsext_status_expected = 0;
              break;
              /* status request response should be sent */
          case SSL_TLSEXT_ERR_OK:
              if (s->tlsext_ocsp_resp)
                  s->tlsext_status_expected = 1;
              else
                  s->tlsext_status_expected = 0;
              break;
              /* something bad happened */
          case SSL_TLSEXT_ERR_ALERT_FATAL:
              ret = SSL_TLSEXT_ERR_ALERT_FATAL;
              al = SSL_AD_INTERNAL_ERROR;
              goto err;
          }
      } else
          s->tlsext_status_expected = 0;
  
      if (!tls1_alpn_handle_client_hello_late(s, &ret, &al)) {
          goto err;
      }
  
   err:
      switch (ret) {
      case SSL_TLSEXT_ERR_ALERT_FATAL:
          ssl3_send_alert(s, SSL3_AL_FATAL, al);
          return -1;
  
      case SSL_TLSEXT_ERR_ALERT_WARNING:
          ssl3_send_alert(s, SSL3_AL_WARNING, al);
          return 1;
  
      default:
          return 1;
      }
  }
  
  int ssl_check_serverhello_tlsext(SSL *s)
  {
      int ret = SSL_TLSEXT_ERR_NOACK;
      int al = SSL_AD_UNRECOGNIZED_NAME;
  
  # ifndef OPENSSL_NO_EC
      /*
       * If we are client and using an elliptic curve cryptography cipher
       * suite, then if server returns an EC point formats lists extension it
       * must contain uncompressed.
       */
      unsigned long alg_k = s->s3->tmp.new_cipher->algorithm_mkey;
      unsigned long alg_a = s->s3->tmp.new_cipher->algorithm_auth;
      if ((s->tlsext_ecpointformatlist != NULL)
          && (s->tlsext_ecpointformatlist_length > 0)
          && (s->session->tlsext_ecpointformatlist != NULL)
          && (s->session->tlsext_ecpointformatlist_length > 0)
          && ((alg_k & (SSL_kEECDH | SSL_kECDHr | SSL_kECDHe))
              || (alg_a & SSL_aECDSA))) {
          /* we are using an ECC cipher */
          size_t i;
          unsigned char *list;
          int found_uncompressed = 0;
          list = s->session->tlsext_ecpointformatlist;
          for (i = 0; i < s->session->tlsext_ecpointformatlist_length; i++) {
              if (*(list++) == TLSEXT_ECPOINTFORMAT_uncompressed) {
                  found_uncompressed = 1;
                  break;
              }
          }
          if (!found_uncompressed) {
              SSLerr(SSL_F_SSL_CHECK_SERVERHELLO_TLSEXT,
                     SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST);
              return -1;
          }
      }
      ret = SSL_TLSEXT_ERR_OK;
  # endif                         /* OPENSSL_NO_EC */
  
      if (s->ctx != NULL && s->ctx->tlsext_servername_callback != 0)
          ret =
              s->ctx->tlsext_servername_callback(s, &al,
                                                 s->ctx->tlsext_servername_arg);
      else if (s->initial_ctx != NULL
               && s->initial_ctx->tlsext_servername_callback != 0)
          ret =
              s->initial_ctx->tlsext_servername_callback(s, &al,
                                                         s->
                                                         initial_ctx->tlsext_servername_arg);
  
  # ifdef TLSEXT_TYPE_opaque_prf_input
      if (s->s3->server_opaque_prf_input_len > 0) {
          /*
           * This case may indicate that we, as a client, want to insist on
           * using opaque PRF inputs. So first verify that we really have a
           * value from the server too.
           */
  
          if (s->s3->server_opaque_prf_input == NULL) {
              ret = SSL_TLSEXT_ERR_ALERT_FATAL;
              al = SSL_AD_HANDSHAKE_FAILURE;
          }
  
          /*
           * Anytime the server *has* sent an opaque PRF input, we need to
           * check that we have a client opaque PRF input of the same size.
           */
          if (s->s3->client_opaque_prf_input == NULL ||
              s->s3->client_opaque_prf_input_len !=
              s->s3->server_opaque_prf_input_len) {
              ret = SSL_TLSEXT_ERR_ALERT_FATAL;
              al = SSL_AD_ILLEGAL_PARAMETER;
          }
      }
  # endif
  
      OPENSSL_free(s->tlsext_ocsp_resp);
      s->tlsext_ocsp_resp = NULL;
      s->tlsext_ocsp_resplen = -1;
      /*
       * If we've requested certificate status and we wont get one tell the
       * callback
       */
      if ((s->tlsext_status_type != -1) && !(s->tlsext_status_expected)
          && !(s->hit) && s->ctx && s->ctx->tlsext_status_cb) {
          int r;
          /*
           * Call callback with resp == NULL and resplen == -1 so callback
           * knows there is no response
           */
          r = s->ctx->tlsext_status_cb(s, s->ctx->tlsext_status_arg);
          if (r == 0) {
              al = SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE;
              ret = SSL_TLSEXT_ERR_ALERT_FATAL;
          }
          if (r < 0) {
              al = SSL_AD_INTERNAL_ERROR;
              ret = SSL_TLSEXT_ERR_ALERT_FATAL;
          }
      }
  
      switch (ret) {
      case SSL_TLSEXT_ERR_ALERT_FATAL:
          ssl3_send_alert(s, SSL3_AL_FATAL, al);
          return -1;
  
      case SSL_TLSEXT_ERR_ALERT_WARNING:
          ssl3_send_alert(s, SSL3_AL_WARNING, al);
          return 1;
  
      case SSL_TLSEXT_ERR_NOACK:
          s->servername_done = 0;
      default:
          return 1;
      }
  }
  
  int ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
                                   int n)
  {
      int al = -1;
      if (s->version < SSL3_VERSION)
          return 1;
      if (ssl_scan_serverhello_tlsext(s, p, d, n, &al) <= 0) {
          ssl3_send_alert(s, SSL3_AL_FATAL, al);
          return 0;
      }
  
      if (ssl_check_serverhello_tlsext(s) <= 0) {
          SSLerr(SSL_F_SSL_PARSE_SERVERHELLO_TLSEXT, SSL_R_SERVERHELLO_TLSEXT);
          return 0;
      }
      return 1;
  }
  
  /*-
   * Since the server cache lookup is done early on in the processing of the
   * ClientHello, and other operations depend on the result, we need to handle
   * any TLS session ticket extension at the same time.
   *
   *   session_id: points at the session ID in the ClientHello. This code will
   *       read past the end of this in order to parse out the session ticket
   *       extension, if any.
   *   len: the length of the session ID.
   *   limit: a pointer to the first byte after the ClientHello.
   *   ret: (output) on return, if a ticket was decrypted, then this is set to
   *       point to the resulting session.
   *
   * If s->tls_session_secret_cb is set then we are expecting a pre-shared key
   * ciphersuite, in which case we have no use for session tickets and one will
   * never be decrypted, nor will s->tlsext_ticket_expected be set to 1.
   *
   * Returns:
   *   -1: fatal error, either from parsing or decrypting the ticket.
   *    0: no ticket was found (or was ignored, based on settings).
   *    1: a zero length extension was found, indicating that the client supports
   *       session tickets but doesn't currently have one to offer.
   *    2: either s->tls_session_secret_cb was set, or a ticket was offered but
   *       couldn't be decrypted because of a non-fatal error.
   *    3: a ticket was successfully decrypted and *ret was set.
   *
   * Side effects:
   *   Sets s->tlsext_ticket_expected to 1 if the server will have to issue
   *   a new session ticket to the client because the client indicated support
   *   (and s->tls_session_secret_cb is NULL) but the client either doesn't have
   *   a session ticket or we couldn't use the one it gave us, or if
   *   s->ctx->tlsext_ticket_key_cb asked to renew the client's ticket.
   *   Otherwise, s->tlsext_ticket_expected is set to 0.
   */
  int tls1_process_ticket(SSL *s, unsigned char *session_id, int len,
                          const unsigned char *limit, SSL_SESSION **ret)
  {
      /* Point after session ID in client hello */
      const unsigned char *p = session_id + len;
      unsigned short i;
  
      *ret = NULL;
      s->tlsext_ticket_expected = 0;
  
      /*
       * If tickets disabled behave as if no ticket present to permit stateful
       * resumption.
       */
      if (SSL_get_options(s) & SSL_OP_NO_TICKET)
          return 0;
      if ((s->version <= SSL3_VERSION) || !limit)
          return 0;
      if (p >= limit)
          return -1;
      /* Skip past DTLS cookie */
      if (SSL_IS_DTLS(s)) {
          i = *(p++);
  
          if (limit - p <= i)
              return -1;
  
          p += i;
      }
      /* Skip past cipher list */
      n2s(p, i);
      if (limit - p <= i)
          return -1;
      p += i;
  
      /* Skip past compression algorithm list */
      i = *(p++);
      if (limit - p < i)
          return -1;
      p += i;
  
      /* Now at start of extensions */
      if (limit - p <= 2)
          return 0;
      n2s(p, i);
      while (limit - p >= 4) {
          unsigned short type, size;
          n2s(p, type);
          n2s(p, size);
          if (limit - p < size)
              return 0;
          if (type == TLSEXT_TYPE_session_ticket) {
              int r;
              if (size == 0) {
                  /*
                   * The client will accept a ticket but doesn't currently have
                   * one.
                   */
                  s->tlsext_ticket_expected = 1;
                  return 1;
              }
              if (s->tls_session_secret_cb) {
                  /*
                   * Indicate that the ticket couldn't be decrypted rather than
                   * generating the session from ticket now, trigger
                   * abbreviated handshake based on external mechanism to
                   * calculate the master secret later.
                   */
                  return 2;
              }
              r = tls_decrypt_ticket(s, p, size, session_id, len, ret);
              switch (r) {
              case 2:            /* ticket couldn't be decrypted */
                  s->tlsext_ticket_expected = 1;
                  return 2;
              case 3:            /* ticket was decrypted */
                  return r;
              case 4:            /* ticket decrypted but need to renew */
                  s->tlsext_ticket_expected = 1;
                  return 3;
              default:           /* fatal error */
                  return -1;
              }
          }
          p += size;
      }
      return 0;
  }
  
  /*-
   * tls_decrypt_ticket attempts to decrypt a session ticket.
   *
   *   etick: points to the body of the session ticket extension.
   *   eticklen: the length of the session tickets extenion.
   *   sess_id: points at the session ID.
   *   sesslen: the length of the session ID.
   *   psess: (output) on return, if a ticket was decrypted, then this is set to
   *       point to the resulting session.
   *
   * Returns:
   *   -1: fatal error, either from parsing or decrypting the ticket.
   *    2: the ticket couldn't be decrypted.
   *    3: a ticket was successfully decrypted and *psess was set.
   *    4: same as 3, but the ticket needs to be renewed.
   */
  static int tls_decrypt_ticket(SSL *s, const unsigned char *etick,
                                int eticklen, const unsigned char *sess_id,
                                int sesslen, SSL_SESSION **psess)
  {
      SSL_SESSION *sess;
      unsigned char *sdec;
      const unsigned char *p;
      int slen, mlen, renew_ticket = 0;
      unsigned char tick_hmac[EVP_MAX_MD_SIZE];
      HMAC_CTX hctx;
      EVP_CIPHER_CTX ctx;
      SSL_CTX *tctx = s->initial_ctx;
      /* Need at least keyname + iv + some encrypted data */
      if (eticklen < 48)
          return 2;
      /* Initialize session ticket encryption and HMAC contexts */
      HMAC_CTX_init(&hctx);
      EVP_CIPHER_CTX_init(&ctx);
      if (tctx->tlsext_ticket_key_cb) {
          unsigned char *nctick = (unsigned char *)etick;
          int rv = tctx->tlsext_ticket_key_cb(s, nctick, nctick + 16,
                                              &ctx, &hctx, 0);
          if (rv < 0)
              return -1;
          if (rv == 0)
              return 2;
          if (rv == 2)
              renew_ticket = 1;
      } else {
          /* Check key name matches */
          if (memcmp(etick, tctx->tlsext_tick_key_name, 16))
              return 2;
          if (HMAC_Init_ex(&hctx, tctx->tlsext_tick_hmac_key, 16,
                           tlsext_tick_md(), NULL) <= 0
                  || EVP_DecryptInit_ex(&ctx, EVP_aes_128_cbc(), NULL,
                                        tctx->tlsext_tick_aes_key,
                                        etick + 16) <= 0) {
              goto err;
         }
      }
      /*
       * Attempt to process session ticket, first conduct sanity and integrity
       * checks on ticket.
       */
      mlen = HMAC_size(&hctx);
      if (mlen < 0) {
          goto err;
      }
      eticklen -= mlen;
      /* Check HMAC of encrypted ticket */
      if (HMAC_Update(&hctx, etick, eticklen) <= 0
              || HMAC_Final(&hctx, tick_hmac, NULL) <= 0) {
          goto err;
      }
      HMAC_CTX_cleanup(&hctx);
      if (CRYPTO_memcmp(tick_hmac, etick + eticklen, mlen)) {
          EVP_CIPHER_CTX_cleanup(&ctx);
          return 2;
      }
      /* Attempt to decrypt session data */
      /* Move p after IV to start of encrypted ticket, update length */
      p = etick + 16 + EVP_CIPHER_CTX_iv_length(&ctx);
      eticklen -= 16 + EVP_CIPHER_CTX_iv_length(&ctx);
      sdec = OPENSSL_malloc(eticklen);
      if (sdec == NULL
              || EVP_DecryptUpdate(&ctx, sdec, &slen, p, eticklen) <= 0) {
          EVP_CIPHER_CTX_cleanup(&ctx);
          OPENSSL_free(sdec);
          return -1;
      }
      if (EVP_DecryptFinal(&ctx, sdec + slen, &mlen) <= 0) {
          EVP_CIPHER_CTX_cleanup(&ctx);
          OPENSSL_free(sdec);
          return 2;
      }
      slen += mlen;
      EVP_CIPHER_CTX_cleanup(&ctx);
      p = sdec;
  
      sess = d2i_SSL_SESSION(NULL, &p, slen);
      OPENSSL_free(sdec);
      if (sess) {
          /*
           * The session ID, if non-empty, is used by some clients to detect
           * that the ticket has been accepted. So we copy it to the session
           * structure. If it is empty set length to zero as required by
           * standard.
           */
          if (sesslen)
              memcpy(sess->session_id, sess_id, sesslen);
          sess->session_id_length = sesslen;
          *psess = sess;
          if (renew_ticket)
              return 4;
          else
              return 3;
      }
      ERR_clear_error();
      /*
       * For session parse failure, indicate that we need to send a new ticket.
       */
      return 2;
  err:
      EVP_CIPHER_CTX_cleanup(&ctx);
      HMAC_CTX_cleanup(&hctx);
      return -1;
  }
  
  /* Tables to translate from NIDs to TLS v1.2 ids */
  
  typedef struct {
      int nid;
      int id;
  } tls12_lookup;
  
  static tls12_lookup tls12_md[] = {
      {NID_md5, TLSEXT_hash_md5},
      {NID_sha1, TLSEXT_hash_sha1},
      {NID_sha224, TLSEXT_hash_sha224},
      {NID_sha256, TLSEXT_hash_sha256},
      {NID_sha384, TLSEXT_hash_sha384},
      {NID_sha512, TLSEXT_hash_sha512}
  };
  
  static tls12_lookup tls12_sig[] = {
      {EVP_PKEY_RSA, TLSEXT_signature_rsa},
      {EVP_PKEY_DSA, TLSEXT_signature_dsa},
      {EVP_PKEY_EC, TLSEXT_signature_ecdsa}
  };
  
  static int tls12_find_id(int nid, tls12_lookup *table, size_t tlen)
  {
      size_t i;
      for (i = 0; i < tlen; i++) {
          if (table[i].nid == nid)
              return table[i].id;
      }
      return -1;
  }
  
  static int tls12_find_nid(int id, tls12_lookup *table, size_t tlen)
  {
      size_t i;
      for (i = 0; i < tlen; i++) {
          if ((table[i].id) == id)
              return table[i].nid;
      }
      return NID_undef;
  }
  
  int tls12_get_sigandhash(unsigned char *p, const EVP_PKEY *pk,
                           const EVP_MD *md)
  {
      int sig_id, md_id;
      if (!md)
          return 0;
      md_id = tls12_find_id(EVP_MD_type(md), tls12_md,
                            sizeof(tls12_md) / sizeof(tls12_lookup));
      if (md_id == -1)
          return 0;
      sig_id = tls12_get_sigid(pk);
      if (sig_id == -1)
          return 0;
      p[0] = (unsigned char)md_id;
      p[1] = (unsigned char)sig_id;
      return 1;
  }
  
  int tls12_get_sigid(const EVP_PKEY *pk)
  {
      return tls12_find_id(pk->type, tls12_sig,
                           sizeof(tls12_sig) / sizeof(tls12_lookup));
  }
  
  const EVP_MD *tls12_get_hash(unsigned char hash_alg)
  {
      switch (hash_alg) {
  # ifndef OPENSSL_NO_MD5
      case TLSEXT_hash_md5:
  #  ifdef OPENSSL_FIPS
          if (FIPS_mode())
              return NULL;
  #  endif
          return EVP_md5();
  # endif
  # ifndef OPENSSL_NO_SHA
      case TLSEXT_hash_sha1:
          return EVP_sha1();
  # endif
  # ifndef OPENSSL_NO_SHA256
      case TLSEXT_hash_sha224:
          return EVP_sha224();
  
      case TLSEXT_hash_sha256:
          return EVP_sha256();
  # endif
  # ifndef OPENSSL_NO_SHA512
      case TLSEXT_hash_sha384:
          return EVP_sha384();
  
      case TLSEXT_hash_sha512:
          return EVP_sha512();
  # endif
      default:
          return NULL;
  
      }
  }
  
  static int tls12_get_pkey_idx(unsigned char sig_alg)
  {
      switch (sig_alg) {
  # ifndef OPENSSL_NO_RSA
      case TLSEXT_signature_rsa:
          return SSL_PKEY_RSA_SIGN;
  # endif
  # ifndef OPENSSL_NO_DSA
      case TLSEXT_signature_dsa:
          return SSL_PKEY_DSA_SIGN;
  # endif
  # ifndef OPENSSL_NO_ECDSA
      case TLSEXT_signature_ecdsa:
          return SSL_PKEY_ECC;
  # endif
      }
      return -1;
  }
  
  /* Convert TLS 1.2 signature algorithm extension values into NIDs */
  static void tls1_lookup_sigalg(int *phash_nid, int *psign_nid,
                                 int *psignhash_nid, const unsigned char *data)
  {
      int sign_nid = NID_undef, hash_nid = NID_undef;
      if (!phash_nid && !psign_nid && !psignhash_nid)
          return;
      if (phash_nid || psignhash_nid) {
          hash_nid = tls12_find_nid(data[0], tls12_md,
                                    sizeof(tls12_md) / sizeof(tls12_lookup));
          if (phash_nid)
              *phash_nid = hash_nid;
      }
      if (psign_nid || psignhash_nid) {
          sign_nid = tls12_find_nid(data[1], tls12_sig,
                                    sizeof(tls12_sig) / sizeof(tls12_lookup));
          if (psign_nid)
              *psign_nid = sign_nid;
      }
      if (psignhash_nid) {
          if (sign_nid == NID_undef || hash_nid == NID_undef
                  || OBJ_find_sigid_by_algs(psignhash_nid, hash_nid,
                                            sign_nid) <= 0)
              *psignhash_nid = NID_undef;
      }
  }
  
  /* Given preference and allowed sigalgs set shared sigalgs */
  static int tls12_do_shared_sigalgs(TLS_SIGALGS *shsig,
                                     const unsigned char *pref, size_t preflen,
                                     const unsigned char *allow,
                                     size_t allowlen)
  {
      const unsigned char *ptmp, *atmp;
      size_t i, j, nmatch = 0;
      for (i = 0, ptmp = pref; i < preflen; i += 2, ptmp += 2) {
          /* Skip disabled hashes or signature algorithms */
          if (tls12_get_hash(ptmp[0]) == NULL)
              continue;
          if (tls12_get_pkey_idx(ptmp[1]) == -1)
              continue;
          for (j = 0, atmp = allow; j < allowlen; j += 2, atmp += 2) {
              if (ptmp[0] == atmp[0] && ptmp[1] == atmp[1]) {
                  nmatch++;
                  if (shsig) {
                      shsig->rhash = ptmp[0];
                      shsig->rsign = ptmp[1];
                      tls1_lookup_sigalg(&shsig->hash_nid,
                                         &shsig->sign_nid,
                                         &shsig->signandhash_nid, ptmp);
                      shsig++;
                  }
                  break;
              }
          }
      }
      return nmatch;
  }
  
  /* Set shared signature algorithms for SSL structures */
  static int tls1_set_shared_sigalgs(SSL *s)
  {
      const unsigned char *pref, *allow, *conf;
      size_t preflen, allowlen, conflen;
      size_t nmatch;
      TLS_SIGALGS *salgs = NULL;
      CERT *c = s->cert;
      unsigned int is_suiteb = tls1_suiteb(s);
      if (c->shared_sigalgs) {
          OPENSSL_free(c->shared_sigalgs);
          c->shared_sigalgs = NULL;
          c->shared_sigalgslen = 0;
      }
      /* If client use client signature algorithms if not NULL */
      if (!s->server && c->client_sigalgs && !is_suiteb) {
          conf = c->client_sigalgs;
          conflen = c->client_sigalgslen;
      } else if (c->conf_sigalgs && !is_suiteb) {
          conf = c->conf_sigalgs;
          conflen = c->conf_sigalgslen;
      } else
          conflen = tls12_get_psigalgs(s, &conf);
      if (s->options & SSL_OP_CIPHER_SERVER_PREFERENCE || is_suiteb) {
          pref = conf;
          preflen = conflen;
          allow = c->peer_sigalgs;
          allowlen = c->peer_sigalgslen;
      } else {
          allow = conf;
          allowlen = conflen;
          pref = c->peer_sigalgs;
          preflen = c->peer_sigalgslen;
      }
      nmatch = tls12_do_shared_sigalgs(NULL, pref, preflen, allow, allowlen);
      if (nmatch) {
          salgs = OPENSSL_malloc(nmatch * sizeof(TLS_SIGALGS));
          if (!salgs)
              return 0;
          nmatch = tls12_do_shared_sigalgs(salgs, pref, preflen, allow, allowlen);
      } else {
          salgs = NULL;
      }
      c->shared_sigalgs = salgs;
      c->shared_sigalgslen = nmatch;
      return 1;
  }
  
  /* Set preferred digest for each key type */
  
  int tls1_save_sigalgs(SSL *s, const unsigned char *data, int dsize)
  {
      CERT *c = s->cert;
      /* Extension ignored for inappropriate versions */
      if (!SSL_USE_SIGALGS(s))
          return 1;
      /* Should never happen */
      if (!c)
          return 0;
  
      if (c->peer_sigalgs)
          OPENSSL_free(c->peer_sigalgs);
      c->peer_sigalgs = OPENSSL_malloc(dsize);
      if (!c->peer_sigalgs)
          return 0;
      c->peer_sigalgslen = dsize;
      memcpy(c->peer_sigalgs, data, dsize);
      return 1;
  }
  
  int tls1_process_sigalgs(SSL *s)
  {
      int idx;
      size_t i;
      const EVP_MD *md;
      CERT *c = s->cert;
      TLS_SIGALGS *sigptr;
      if (!tls1_set_shared_sigalgs(s))
          return 0;
  
  # ifdef OPENSSL_SSL_DEBUG_BROKEN_PROTOCOL
      if (s->cert->cert_flags & SSL_CERT_FLAG_BROKEN_PROTOCOL) {
          /*
           * Use first set signature preference to force message digest,
           * ignoring any peer preferences.
           */
          const unsigned char *sigs = NULL;
          if (s->server)
              sigs = c->conf_sigalgs;
          else
              sigs = c->client_sigalgs;
          if (sigs) {
              idx = tls12_get_pkey_idx(sigs[1]);
              md = tls12_get_hash(sigs[0]);
              c->pkeys[idx].digest = md;
              c->pkeys[idx].valid_flags = CERT_PKEY_EXPLICIT_SIGN;
              if (idx == SSL_PKEY_RSA_SIGN) {
                  c->pkeys[SSL_PKEY_RSA_ENC].valid_flags =
                      CERT_PKEY_EXPLICIT_SIGN;
                  c->pkeys[SSL_PKEY_RSA_ENC].digest = md;
              }
          }
      }
  # endif
  
      for (i = 0, sigptr = c->shared_sigalgs;
           i < c->shared_sigalgslen; i++, sigptr++) {
          idx = tls12_get_pkey_idx(sigptr->rsign);
          if (idx > 0 && c->pkeys[idx].digest == NULL) {
              md = tls12_get_hash(sigptr->rhash);
              c->pkeys[idx].digest = md;
              c->pkeys[idx].valid_flags = CERT_PKEY_EXPLICIT_SIGN;
              if (idx == SSL_PKEY_RSA_SIGN) {
                  c->pkeys[SSL_PKEY_RSA_ENC].valid_flags =
                      CERT_PKEY_EXPLICIT_SIGN;
                  c->pkeys[SSL_PKEY_RSA_ENC].digest = md;
              }
          }
  
      }
      /*
       * In strict mode leave unset digests as NULL to indicate we can't use
       * the certificate for signing.
       */
      if (!(s->cert->cert_flags & SSL_CERT_FLAGS_CHECK_TLS_STRICT)) {
          /*
           * Set any remaining keys to default values. NOTE: if alg is not
           * supported it stays as NULL.
           */
  # ifndef OPENSSL_NO_DSA
          if (!c->pkeys[SSL_PKEY_DSA_SIGN].digest)
              c->pkeys[SSL_PKEY_DSA_SIGN].digest = EVP_sha1();
  # endif
  # ifndef OPENSSL_NO_RSA
          if (!c->pkeys[SSL_PKEY_RSA_SIGN].digest) {
              c->pkeys[SSL_PKEY_RSA_SIGN].digest = EVP_sha1();
              c->pkeys[SSL_PKEY_RSA_ENC].digest = EVP_sha1();
          }
  # endif
  # ifndef OPENSSL_NO_ECDSA
          if (!c->pkeys[SSL_PKEY_ECC].digest)
              c->pkeys[SSL_PKEY_ECC].digest = EVP_sha1();
  # endif
      }
      return 1;
  }
  
  int SSL_get_sigalgs(SSL *s, int idx,
                      int *psign, int *phash, int *psignhash,
                      unsigned char *rsig, unsigned char *rhash)
  {
      const unsigned char *psig = s->cert->peer_sigalgs;
      if (psig == NULL)
          return 0;
      if (idx >= 0) {
          idx <<= 1;
          if (idx >= (int)s->cert->peer_sigalgslen)
              return 0;
          psig += idx;
          if (rhash)
              *rhash = psig[0];
          if (rsig)
              *rsig = psig[1];
          tls1_lookup_sigalg(phash, psign, psignhash, psig);
      }
      return s->cert->peer_sigalgslen / 2;
  }
  
  int SSL_get_shared_sigalgs(SSL *s, int idx,
                             int *psign, int *phash, int *psignhash,
                             unsigned char *rsig, unsigned char *rhash)
  {
      TLS_SIGALGS *shsigalgs = s->cert->shared_sigalgs;
      if (!shsigalgs || idx >= (int)s->cert->shared_sigalgslen)
          return 0;
      shsigalgs += idx;
      if (phash)
          *phash = shsigalgs->hash_nid;
      if (psign)
          *psign = shsigalgs->sign_nid;
      if (psignhash)
          *psignhash = shsigalgs->signandhash_nid;
      if (rsig)
          *rsig = shsigalgs->rsign;
      if (rhash)
          *rhash = shsigalgs->rhash;
      return s->cert->shared_sigalgslen;
  }
  
  # ifndef OPENSSL_NO_HEARTBEATS
  int tls1_process_heartbeat(SSL *s)
  {
      unsigned char *p = &s->s3->rrec.data[0], *pl;
      unsigned short hbtype;
      unsigned int payload;
      unsigned int padding = 16;  /* Use minimum padding */
  
      if (s->msg_callback)
          s->msg_callback(0, s->version, TLS1_RT_HEARTBEAT,
                          &s->s3->rrec.data[0], s->s3->rrec.length,
                          s, s->msg_callback_arg);
  
      /* Read type and payload length first */
      if (1 + 2 + 16 > s->s3->rrec.length)
          return 0;               /* silently discard */
      hbtype = *p++;
      n2s(p, payload);
      if (1 + 2 + payload + 16 > s->s3->rrec.length)
          return 0;               /* silently discard per RFC 6520 sec. 4 */
      pl = p;
  
      if (hbtype == TLS1_HB_REQUEST) {
          unsigned char *buffer, *bp;
          int r;
  
          /*
           * Allocate memory for the response, size is 1 bytes message type,
           * plus 2 bytes payload length, plus payload, plus padding
           */
          buffer = OPENSSL_malloc(1 + 2 + payload + padding);
          if (buffer == NULL)
              return -1;
          bp = buffer;
  
          /* Enter response type, length and copy payload */
          *bp++ = TLS1_HB_RESPONSE;
          s2n(payload, bp);
          memcpy(bp, pl, payload);
          bp += payload;
          /* Random padding */
          if (RAND_pseudo_bytes(bp, padding) < 0) {
              OPENSSL_free(buffer);
              return -1;
          }
  
          r = ssl3_write_bytes(s, TLS1_RT_HEARTBEAT, buffer,
                               3 + payload + padding);
  
          if (r >= 0 && s->msg_callback)
              s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
                              buffer, 3 + payload + padding,
                              s, s->msg_callback_arg);
  
          OPENSSL_free(buffer);
  
          if (r < 0)
              return r;
      } else if (hbtype == TLS1_HB_RESPONSE) {
          unsigned int seq;
  
          /*
           * We only send sequence numbers (2 bytes unsigned int), and 16
           * random bytes, so we just try to read the sequence number
           */
          n2s(pl, seq);
  
          if (payload == 18 && seq == s->tlsext_hb_seq) {
              s->tlsext_hb_seq++;
              s->tlsext_hb_pending = 0;
          }
      }
  
      return 0;
  }
  
  int tls1_heartbeat(SSL *s)
  {
      unsigned char *buf, *p;
      int ret = -1;
      unsigned int payload = 18;  /* Sequence number + random bytes */
      unsigned int padding = 16;  /* Use minimum padding */
  
      /* Only send if peer supports and accepts HB requests... */
      if (!(s->tlsext_heartbeat & SSL_TLSEXT_HB_ENABLED) ||
          s->tlsext_heartbeat & SSL_TLSEXT_HB_DONT_SEND_REQUESTS) {
          SSLerr(SSL_F_TLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PEER_DOESNT_ACCEPT);
          return -1;
      }
  
      /* ...and there is none in flight yet... */
      if (s->tlsext_hb_pending) {
          SSLerr(SSL_F_TLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PENDING);
          return -1;
      }
  
      /* ...and no handshake in progress. */
      if (SSL_in_init(s) || s->in_handshake) {
          SSLerr(SSL_F_TLS1_HEARTBEAT, SSL_R_UNEXPECTED_MESSAGE);
          return -1;
      }
  
      /*
       * Check if padding is too long, payload and padding must not exceed 2^14
       * - 3 = 16381 bytes in total.
       */
      OPENSSL_assert(payload + padding <= 16381);
  
      /*-
       * Create HeartBeat message, we just use a sequence number
       * as payload to distuingish different messages and add
       * some random stuff.
       *  - Message Type, 1 byte
       *  - Payload Length, 2 bytes (unsigned int)
       *  - Payload, the sequence number (2 bytes uint)
       *  - Payload, random bytes (16 bytes uint)
       *  - Padding
       */
      buf = OPENSSL_malloc(1 + 2 + payload + padding);
      p = buf;
      /* Message Type */
      *p++ = TLS1_HB_REQUEST;
      /* Payload length (18 bytes here) */
      s2n(payload, p);
      /* Sequence number */
      s2n(s->tlsext_hb_seq, p);
      /* 16 random bytes */
      if (RAND_pseudo_bytes(p, 16) < 0) {
          SSLerr(SSL_F_TLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
          goto err;
      }
      p += 16;
      /* Random padding */
      if (RAND_pseudo_bytes(p, padding) < 0) {
          SSLerr(SSL_F_TLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
          goto err;
      }
  
      ret = ssl3_write_bytes(s, TLS1_RT_HEARTBEAT, buf, 3 + payload + padding);
      if (ret >= 0) {
          if (s->msg_callback)
              s->msg_callback(1, s->version, TLS1_RT_HEARTBEAT,
                              buf, 3 + payload + padding,
                              s, s->msg_callback_arg);
  
          s->tlsext_hb_pending = 1;
      }
  
  err:
      OPENSSL_free(buf);
  
      return ret;
  }
  # endif
  
  # define MAX_SIGALGLEN   (TLSEXT_hash_num * TLSEXT_signature_num * 2)
  
  typedef struct {
      size_t sigalgcnt;
      int sigalgs[MAX_SIGALGLEN];
  } sig_cb_st;
  
  static int sig_cb(const char *elem, int len, void *arg)
  {
      sig_cb_st *sarg = arg;
      size_t i;
      char etmp[20], *p;
      int sig_alg, hash_alg;
      if (elem == NULL)
          return 0;
      if (sarg->sigalgcnt == MAX_SIGALGLEN)
          return 0;
      if (len > (int)(sizeof(etmp) - 1))
          return 0;
      memcpy(etmp, elem, len);
      etmp[len] = 0;
      p = strchr(etmp, '+');
      if (!p)
          return 0;
      *p = 0;
      p++;
      if (!*p)
          return 0;
  
      if (!strcmp(etmp, "RSA"))
          sig_alg = EVP_PKEY_RSA;
      else if (!strcmp(etmp, "DSA"))
          sig_alg = EVP_PKEY_DSA;
      else if (!strcmp(etmp, "ECDSA"))
          sig_alg = EVP_PKEY_EC;
      else
          return 0;
  
      hash_alg = OBJ_sn2nid(p);
      if (hash_alg == NID_undef)
          hash_alg = OBJ_ln2nid(p);
      if (hash_alg == NID_undef)
          return 0;
  
      for (i = 0; i < sarg->sigalgcnt; i += 2) {
          if (sarg->sigalgs[i] == sig_alg && sarg->sigalgs[i + 1] == hash_alg)
              return 0;
      }
      sarg->sigalgs[sarg->sigalgcnt++] = hash_alg;
      sarg->sigalgs[sarg->sigalgcnt++] = sig_alg;
      return 1;
  }
  
  /*
   * Set suppored signature algorithms based on a colon separated list of the
   * form sig+hash e.g. RSA+SHA512:DSA+SHA512
   */
  int tls1_set_sigalgs_list(CERT *c, const char *str, int client)
  {
      sig_cb_st sig;
      sig.sigalgcnt = 0;
      if (!CONF_parse_list(str, ':', 1, sig_cb, &sig))
          return 0;
      if (c == NULL)
          return 1;
      return tls1_set_sigalgs(c, sig.sigalgs, sig.sigalgcnt, client);
  }
  
  int tls1_set_sigalgs(CERT *c, const int *psig_nids, size_t salglen,
                       int client)
  {
      unsigned char *sigalgs, *sptr;
      int rhash, rsign;
      size_t i;
      if (salglen & 1)
          return 0;
      sigalgs = OPENSSL_malloc(salglen);
      if (sigalgs == NULL)
          return 0;
      for (i = 0, sptr = sigalgs; i < salglen; i += 2) {
          rhash = tls12_find_id(*psig_nids++, tls12_md,
                                sizeof(tls12_md) / sizeof(tls12_lookup));
          rsign = tls12_find_id(*psig_nids++, tls12_sig,
                                sizeof(tls12_sig) / sizeof(tls12_lookup));
  
          if (rhash == -1 || rsign == -1)
              goto err;
          *sptr++ = rhash;
          *sptr++ = rsign;
      }
  
      if (client) {
          if (c->client_sigalgs)
              OPENSSL_free(c->client_sigalgs);
          c->client_sigalgs = sigalgs;
          c->client_sigalgslen = salglen;
      } else {
          if (c->conf_sigalgs)
              OPENSSL_free(c->conf_sigalgs);
          c->conf_sigalgs = sigalgs;
          c->conf_sigalgslen = salglen;
      }
  
      return 1;
  
   err:
      OPENSSL_free(sigalgs);
      return 0;
  }
  
  static int tls1_check_sig_alg(CERT *c, X509 *x, int default_nid)
  {
      int sig_nid;
      size_t i;
      if (default_nid == -1)
          return 1;
      sig_nid = X509_get_signature_nid(x);
      if (default_nid)
          return sig_nid == default_nid ? 1 : 0;
      for (i = 0; i < c->shared_sigalgslen; i++)
          if (sig_nid == c->shared_sigalgs[i].signandhash_nid)
              return 1;
      return 0;
  }
  
  /* Check to see if a certificate issuer name matches list of CA names */
  static int ssl_check_ca_name(STACK_OF(X509_NAME) *names, X509 *x)
  {
      X509_NAME *nm;
      int i;
      nm = X509_get_issuer_name(x);
      for (i = 0; i < sk_X509_NAME_num(names); i++) {
          if (!X509_NAME_cmp(nm, sk_X509_NAME_value(names, i)))
              return 1;
      }
      return 0;
  }
  
  /*
   * Check certificate chain is consistent with TLS extensions and is usable by
   * server. This servers two purposes: it allows users to check chains before
   * passing them to the server and it allows the server to check chains before
   * attempting to use them.
   */
  
  /* Flags which need to be set for a certificate when stict mode not set */
  
  # define CERT_PKEY_VALID_FLAGS \
          (CERT_PKEY_EE_SIGNATURE|CERT_PKEY_EE_PARAM)
  /* Strict mode flags */
  # define CERT_PKEY_STRICT_FLAGS \
           (CERT_PKEY_VALID_FLAGS|CERT_PKEY_CA_SIGNATURE|CERT_PKEY_CA_PARAM \
           | CERT_PKEY_ISSUER_NAME|CERT_PKEY_CERT_TYPE)
  
  int tls1_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain,
                       int idx)
  {
      int i;
      int rv = 0;
      int check_flags = 0, strict_mode;
      CERT_PKEY *cpk = NULL;
      CERT *c = s->cert;
      unsigned int suiteb_flags = tls1_suiteb(s);
      /* idx == -1 means checking server chains */
      if (idx != -1) {
          /* idx == -2 means checking client certificate chains */
          if (idx == -2) {
              cpk = c->key;
              idx = cpk - c->pkeys;
          } else
              cpk = c->pkeys + idx;
          x = cpk->x509;
          pk = cpk->privatekey;
          chain = cpk->chain;
          strict_mode = c->cert_flags & SSL_CERT_FLAGS_CHECK_TLS_STRICT;
          /* If no cert or key, forget it */
          if (!x || !pk)
              goto end;
  # ifdef OPENSSL_SSL_DEBUG_BROKEN_PROTOCOL
          /* Allow any certificate to pass test */
          if (s->cert->cert_flags & SSL_CERT_FLAG_BROKEN_PROTOCOL) {
              rv = CERT_PKEY_STRICT_FLAGS | CERT_PKEY_EXPLICIT_SIGN |
                  CERT_PKEY_VALID | CERT_PKEY_SIGN;
              cpk->valid_flags = rv;
              return rv;
          }
  # endif
      } else {
          if (!x || !pk)
              return 0;
          idx = ssl_cert_type(x, pk);
          if (idx == -1)
              return 0;
          cpk = c->pkeys + idx;
          if (c->cert_flags & SSL_CERT_FLAGS_CHECK_TLS_STRICT)
              check_flags = CERT_PKEY_STRICT_FLAGS;
          else
              check_flags = CERT_PKEY_VALID_FLAGS;
          strict_mode = 1;
      }
  
      if (suiteb_flags) {
          int ok;
          if (check_flags)
              check_flags |= CERT_PKEY_SUITEB;
          ok = X509_chain_check_suiteb(NULL, x, chain, suiteb_flags);
          if (ok == X509_V_OK)
              rv |= CERT_PKEY_SUITEB;
          else if (!check_flags)
              goto end;
      }
  
      /*
       * Check all signature algorithms are consistent with signature
       * algorithms extension if TLS 1.2 or later and strict mode.
       */
      if (TLS1_get_version(s) >= TLS1_2_VERSION && strict_mode) {
          int default_nid;
          unsigned char rsign = 0;
          if (c->peer_sigalgs)
              default_nid = 0;
          /* If no sigalgs extension use defaults from RFC5246 */
          else {
              switch (idx) {
              case SSL_PKEY_RSA_ENC:
              case SSL_PKEY_RSA_SIGN:
              case SSL_PKEY_DH_RSA:
                  rsign = TLSEXT_signature_rsa;
                  default_nid = NID_sha1WithRSAEncryption;
                  break;
  
              case SSL_PKEY_DSA_SIGN:
              case SSL_PKEY_DH_DSA:
                  rsign = TLSEXT_signature_dsa;
                  default_nid = NID_dsaWithSHA1;
                  break;
  
              case SSL_PKEY_ECC:
                  rsign = TLSEXT_signature_ecdsa;
                  default_nid = NID_ecdsa_with_SHA1;
                  break;
  
              default:
                  default_nid = -1;
                  break;
              }
          }
          /*
           * If peer sent no signature algorithms extension and we have set
           * preferred signature algorithms check we support sha1.
           */
          if (default_nid > 0 && c->conf_sigalgs) {
              size_t j;
              const unsigned char *p = c->conf_sigalgs;
              for (j = 0; j < c->conf_sigalgslen; j += 2, p += 2) {
                  if (p[0] == TLSEXT_hash_sha1 && p[1] == rsign)
                      break;
              }
              if (j == c->conf_sigalgslen) {
                  if (check_flags)
                      goto skip_sigs;
                  else
                      goto end;
              }
          }
          /* Check signature algorithm of each cert in chain */
          if (!tls1_check_sig_alg(c, x, default_nid)) {
              if (!check_flags)
                  goto end;
          } else
              rv |= CERT_PKEY_EE_SIGNATURE;
          rv |= CERT_PKEY_CA_SIGNATURE;
          for (i = 0; i < sk_X509_num(chain); i++) {
              if (!tls1_check_sig_alg(c, sk_X509_value(chain, i), default_nid)) {
                  if (check_flags) {
                      rv &= ~CERT_PKEY_CA_SIGNATURE;
                      break;
                  } else
                      goto end;
              }
          }
      }
      /* Else not TLS 1.2, so mark EE and CA signing algorithms OK */
      else if (check_flags)
          rv |= CERT_PKEY_EE_SIGNATURE | CERT_PKEY_CA_SIGNATURE;
   skip_sigs:
      /* Check cert parameters are consistent */
      if (tls1_check_cert_param(s, x, check_flags ? 1 : 2))
          rv |= CERT_PKEY_EE_PARAM;
      else if (!check_flags)
          goto end;
      if (!s->server)
          rv |= CERT_PKEY_CA_PARAM;
      /* In strict mode check rest of chain too */
      else if (strict_mode) {
          rv |= CERT_PKEY_CA_PARAM;
          for (i = 0; i < sk_X509_num(chain); i++) {
              X509 *ca = sk_X509_value(chain, i);
              if (!tls1_check_cert_param(s, ca, 0)) {
                  if (check_flags) {
                      rv &= ~CERT_PKEY_CA_PARAM;
                      break;
                  } else
                      goto end;
              }
          }
      }
      if (!s->server && strict_mode) {
          STACK_OF(X509_NAME) *ca_dn;
          int check_type = 0;
          switch (pk->type) {
          case EVP_PKEY_RSA:
              check_type = TLS_CT_RSA_SIGN;
              break;
          case EVP_PKEY_DSA:
              check_type = TLS_CT_DSS_SIGN;
              break;
          case EVP_PKEY_EC:
              check_type = TLS_CT_ECDSA_SIGN;
              break;
          case EVP_PKEY_DH:
          case EVP_PKEY_DHX:
              {
                  int cert_type = X509_certificate_type(x, pk);
                  if (cert_type & EVP_PKS_RSA)
                      check_type = TLS_CT_RSA_FIXED_DH;
                  if (cert_type & EVP_PKS_DSA)
                      check_type = TLS_CT_DSS_FIXED_DH;
              }
          }
          if (check_type) {
              const unsigned char *ctypes;
              int ctypelen;
              if (c->ctypes) {
                  ctypes = c->ctypes;
                  ctypelen = (int)c->ctype_num;
              } else {
                  ctypes = (unsigned char *)s->s3->tmp.ctype;
                  ctypelen = s->s3->tmp.ctype_num;
              }
              for (i = 0; i < ctypelen; i++) {
                  if (ctypes[i] == check_type) {
                      rv |= CERT_PKEY_CERT_TYPE;
                      break;
                  }
              }
              if (!(rv & CERT_PKEY_CERT_TYPE) && !check_flags)
                  goto end;
          } else
              rv |= CERT_PKEY_CERT_TYPE;
  
          ca_dn = s->s3->tmp.ca_names;
  
          if (!sk_X509_NAME_num(ca_dn))
              rv |= CERT_PKEY_ISSUER_NAME;
  
          if (!(rv & CERT_PKEY_ISSUER_NAME)) {
              if (ssl_check_ca_name(ca_dn, x))
                  rv |= CERT_PKEY_ISSUER_NAME;
          }
          if (!(rv & CERT_PKEY_ISSUER_NAME)) {
              for (i = 0; i < sk_X509_num(chain); i++) {
                  X509 *xtmp = sk_X509_value(chain, i);
                  if (ssl_check_ca_name(ca_dn, xtmp)) {
                      rv |= CERT_PKEY_ISSUER_NAME;
                      break;
                  }
              }
          }
          if (!check_flags && !(rv & CERT_PKEY_ISSUER_NAME))
              goto end;
      } else
          rv |= CERT_PKEY_ISSUER_NAME | CERT_PKEY_CERT_TYPE;
  
      if (!check_flags || (rv & check_flags) == check_flags)
          rv |= CERT_PKEY_VALID;
  
   end:
  
      if (TLS1_get_version(s) >= TLS1_2_VERSION) {
          if (cpk->valid_flags & CERT_PKEY_EXPLICIT_SIGN)
              rv |= CERT_PKEY_EXPLICIT_SIGN | CERT_PKEY_SIGN;
          else if (cpk->digest)
              rv |= CERT_PKEY_SIGN;
      } else
          rv |= CERT_PKEY_SIGN | CERT_PKEY_EXPLICIT_SIGN;
  
      /*
       * When checking a CERT_PKEY structure all flags are irrelevant if the
       * chain is invalid.
       */
      if (!check_flags) {
          if (rv & CERT_PKEY_VALID)
              cpk->valid_flags = rv;
          else {
              /* Preserve explicit sign flag, clear rest */
              cpk->valid_flags &= CERT_PKEY_EXPLICIT_SIGN;
              return 0;
          }
      }
      return rv;
  }
  
  /* Set validity of certificates in an SSL structure */
  void tls1_set_cert_validity(SSL *s)
  {
      tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_RSA_ENC);
      tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_RSA_SIGN);
      tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_DSA_SIGN);
      tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_DH_RSA);
      tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_DH_DSA);
      tls1_check_chain(s, NULL, NULL, NULL, SSL_PKEY_ECC);
  }
  
  /* User level utiity function to check a chain is suitable */
  int SSL_check_chain(SSL *s, X509 *x, EVP_PKEY *pk, STACK_OF(X509) *chain)
  {
      return tls1_check_chain(s, x, pk, chain, -1);
  }
  
  #endif
  