text: /*
   * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the OpenSSL license (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #include "../ssl_locl.h"
  #include "internal/constant_time_locl.h"
  #include <openssl/rand.h>
  #include "record_locl.h"
  #include "internal/cryptlib.h"
  
  static const unsigned char ssl3_pad_1[48] = {
      0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
      0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
      0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
      0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
      0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36,
      0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36, 0x36
  };
  
  static const unsigned char ssl3_pad_2[48] = {
      0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
      0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
      0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
      0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
      0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c,
      0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c, 0x5c
  };
  
  /*
   * Clear the contents of an SSL3_RECORD but retain any memory allocated
   */
  void SSL3_RECORD_clear(SSL3_RECORD *r, size_t num_recs)
  {
      unsigned char *comp;
      size_t i;
  
      for (i = 0; i < num_recs; i++) {
          comp = r[i].comp;
  
          memset(&r[i], 0, sizeof(*r));
          r[i].comp = comp;
      }
  }
  
  void SSL3_RECORD_release(SSL3_RECORD *r, size_t num_recs)
  {
      size_t i;
  
      for (i = 0; i < num_recs; i++) {
          OPENSSL_free(r[i].comp);
          r[i].comp = NULL;
      }
  }
  
  void SSL3_RECORD_set_seq_num(SSL3_RECORD *r, const unsigned char *seq_num)
  {
      memcpy(r->seq_num, seq_num, SEQ_NUM_SIZE);
  }
  
  /*
   * Peeks ahead into "read_ahead" data to see if we have a whole record waiting
   * for us in the buffer.
   */
  static int ssl3_record_app_data_waiting(SSL *s)
  {
      SSL3_BUFFER *rbuf;
      size_t left, len;
      unsigned char *p;
  
      rbuf = RECORD_LAYER_get_rbuf(&s->rlayer);
  
      p = SSL3_BUFFER_get_buf(rbuf);
      if (p == NULL)
          return 0;
  
      left = SSL3_BUFFER_get_left(rbuf);
  
      if (left < SSL3_RT_HEADER_LENGTH)
          return 0;
  
      p += SSL3_BUFFER_get_offset(rbuf);
  
      /*
       * We only check the type and record length, we will sanity check version
       * etc later
       */
      if (*p != SSL3_RT_APPLICATION_DATA)
          return 0;
  
      p += 3;
      n2s(p, len);
  
      if (left < SSL3_RT_HEADER_LENGTH + len)
          return 0;
  
      return 1;
  }
  
  int early_data_count_ok(SSL *s, size_t length, size_t overhead, int send)
  {
      uint32_t max_early_data = s->max_early_data;
      SSL_SESSION *sess = s->session;
  
      /*
       * If we are a client then we always use the max_early_data from the
       * session/psksession. Otherwise we go with the lowest out of the max early
       * data set in the session and the configured max_early_data.
       */
      if (!s->server && sess->ext.max_early_data == 0) {
          if (!ossl_assert(s->psksession != NULL
                           && s->psksession->ext.max_early_data > 0)) {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_EARLY_DATA_COUNT_OK,
                       ERR_R_INTERNAL_ERROR);
              return 0;
          }
          sess = s->psksession;
      }
      if (!s->server
              || (s->hit && sess->ext.max_early_data < s->max_early_data))
          max_early_data = sess->ext.max_early_data;
  
      if (max_early_data == 0) {
          SSLfatal(s, send ? SSL_AD_INTERNAL_ERROR : SSL_AD_UNEXPECTED_MESSAGE,
                   SSL_F_EARLY_DATA_COUNT_OK, SSL_R_TOO_MUCH_EARLY_DATA);
          return 0;
      }
  
      /* If we are dealing with ciphertext we need to allow for the overhead */
      max_early_data += overhead;
  
      if (s->early_data_count + length > max_early_data) {
          SSLfatal(s, send ? SSL_AD_INTERNAL_ERROR : SSL_AD_UNEXPECTED_MESSAGE,
                   SSL_F_EARLY_DATA_COUNT_OK, SSL_R_TOO_MUCH_EARLY_DATA);
          return 0;
      }
      s->early_data_count += length;
  
      return 1;
  }
  
  /*
   * MAX_EMPTY_RECORDS defines the number of consecutive, empty records that
   * will be processed per call to ssl3_get_record. Without this limit an
   * attacker could send empty records at a faster rate than we can process and
   * cause ssl3_get_record to loop forever.
   */
  #define MAX_EMPTY_RECORDS 32
  
  #define SSL2_RT_HEADER_LENGTH   2
  /*-
   * Call this to get new input records.
   * It will return <= 0 if more data is needed, normally due to an error
   * or non-blocking IO.
   * When it finishes, |numrpipes| records have been decoded. For each record 'i':
   * rr[i].type    - is the type of record
   * rr[i].data,   - data
   * rr[i].length, - number of bytes
   * Multiple records will only be returned if the record types are all
   * SSL3_RT_APPLICATION_DATA. The number of records returned will always be <=
   * |max_pipelines|
   */
  /* used only by ssl3_read_bytes */
  int ssl3_get_record(SSL *s)
  {
      int enc_err, rret;
      int i;
      size_t more, n;
      SSL3_RECORD *rr, *thisrr;
      SSL3_BUFFER *rbuf;
      SSL_SESSION *sess;
      unsigned char *p;
      unsigned char md[EVP_MAX_MD_SIZE];
      unsigned int version;
      size_t mac_size;
      int imac_size;
      size_t num_recs = 0, max_recs, j;
      PACKET pkt, sslv2pkt;
      size_t first_rec_len;
  
      rr = RECORD_LAYER_get_rrec(&s->rlayer);
      rbuf = RECORD_LAYER_get_rbuf(&s->rlayer);
      max_recs = s->max_pipelines;
      if (max_recs == 0)
          max_recs = 1;
      sess = s->session;
  
      do {
          thisrr = &rr[num_recs];
  
          /* check if we have the header */
          if ((RECORD_LAYER_get_rstate(&s->rlayer) != SSL_ST_READ_BODY) ||
              (RECORD_LAYER_get_packet_length(&s->rlayer)
               < SSL3_RT_HEADER_LENGTH)) {
              size_t sslv2len;
              unsigned int type;
  
              rret = ssl3_read_n(s, SSL3_RT_HEADER_LENGTH,
                                 SSL3_BUFFER_get_len(rbuf), 0,
                                 num_recs == 0 ? 1 : 0, &n);
              if (rret <= 0)
                  return rret;     /* error or non-blocking */
              RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_BODY);
  
              p = RECORD_LAYER_get_packet(&s->rlayer);
              if (!PACKET_buf_init(&pkt, RECORD_LAYER_get_packet(&s->rlayer),
                                   RECORD_LAYER_get_packet_length(&s->rlayer))) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD,
                           ERR_R_INTERNAL_ERROR);
                  return -1;
              }
              sslv2pkt = pkt;
              if (!PACKET_get_net_2_len(&sslv2pkt, &sslv2len)
                      || !PACKET_get_1(&sslv2pkt, &type)) {
                  SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD,
                           ERR_R_INTERNAL_ERROR);
                  return -1;
              }
              /*
               * The first record received by the server may be a V2ClientHello.
               */
              if (s->server && RECORD_LAYER_is_first_record(&s->rlayer)
                      && (sslv2len & 0x8000) != 0
                      && (type == SSL2_MT_CLIENT_HELLO)) {
                  /*
                   *  SSLv2 style record
                   *
                   * |num_recs| here will actually always be 0 because
                   * |num_recs > 0| only ever occurs when we are processing
                   * multiple app data records - which we know isn't the case here
                   * because it is an SSLv2ClientHello. We keep it using
                   * |num_recs| for the sake of consistency
                   */
                  thisrr->type = SSL3_RT_HANDSHAKE;
                  thisrr->rec_version = SSL2_VERSION;
  
                  thisrr->length = sslv2len & 0x7fff;
  
                  if (thisrr->length > SSL3_BUFFER_get_len(rbuf)
                      - SSL2_RT_HEADER_LENGTH) {
                      SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD,
                               SSL_R_PACKET_LENGTH_TOO_LONG);
                      return -1;
                  }
  
                  if (thisrr->length < MIN_SSL2_RECORD_LEN) {
                      SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD,
                               SSL_R_LENGTH_TOO_SHORT);
                      return -1;
                  }
              } else {
                  /* SSLv3+ style record */
                  if (s->msg_callback)
                      s->msg_callback(0, 0, SSL3_RT_HEADER, p, 5, s,
                                      s->msg_callback_arg);
  
                  /* Pull apart the header into the SSL3_RECORD */
                  if (!PACKET_get_1(&pkt, &type)
                          || !PACKET_get_net_2(&pkt, &version)
                          || !PACKET_get_net_2_len(&pkt, &thisrr->length)) {
                      SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD,
                               ERR_R_INTERNAL_ERROR);
                      return -1;
                  }
                  thisrr->type = type;
                  thisrr->rec_version = version;
  
                  /*
                   * Lets check version. In TLSv1.3 we ignore this field. For the
                   * ServerHello after an HRR we haven't actually selected TLSv1.3
                   * yet, but we still treat it as TLSv1.3, so we must check for
                   * that explicitly
                   */
                  if (!s->first_packet && !SSL_IS_TLS13(s)
                          && s->hello_retry_request != SSL_HRR_PENDING
                          && version != (unsigned int)s->version) {
                      if ((s->version & 0xFF00) == (version & 0xFF00)
                          && !s->enc_write_ctx && !s->write_hash) {
                          if (thisrr->type == SSL3_RT_ALERT) {
                              /*
                               * The record is using an incorrect version number,
                               * but what we've got appears to be an alert. We
                               * haven't read the body yet to check whether its a
                               * fatal or not - but chances are it is. We probably
                               * shouldn't send a fatal alert back. We'll just
                               * end.
                               */
                              SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD,
                                       SSL_R_WRONG_VERSION_NUMBER);
                              return -1;
                          }
                          /*
                           * Send back error using their minor version number :-)
                           */
                          s->version = (unsigned short)version;
                      }
                      SSLfatal(s, SSL_AD_PROTOCOL_VERSION, SSL_F_SSL3_GET_RECORD,
                               SSL_R_WRONG_VERSION_NUMBER);
                      return -1;
                  }
  
                  if ((version >> 8) != SSL3_VERSION_MAJOR) {
                      if (RECORD_LAYER_is_first_record(&s->rlayer)) {
                          /* Go back to start of packet, look at the five bytes
                           * that we have. */
                          p = RECORD_LAYER_get_packet(&s->rlayer);
                          if (strncmp((char *)p, "GET ", 4) == 0 ||
                              strncmp((char *)p, "POST ", 5) == 0 ||
                              strncmp((char *)p, "HEAD ", 5) == 0 ||
                              strncmp((char *)p, "PUT ", 4) == 0) {
                              SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD,
                                       SSL_R_HTTP_REQUEST);
                              return -1;
                          } else if (strncmp((char *)p, "CONNE", 5) == 0) {
                              SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD,
                                       SSL_R_HTTPS_PROXY_REQUEST);
                              return -1;
                          }
  
                          /* Doesn't look like TLS - don't send an alert */
                          SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_SSL3_GET_RECORD,
                                   SSL_R_WRONG_VERSION_NUMBER);
                          return -1;
                      } else {
                          SSLfatal(s, SSL_AD_PROTOCOL_VERSION,
                                   SSL_F_SSL3_GET_RECORD,
                                   SSL_R_WRONG_VERSION_NUMBER);
                          return -1;
                      }
                  }
  
                  if (SSL_IS_TLS13(s)
                          && s->enc_read_ctx != NULL
                          && thisrr->type != SSL3_RT_APPLICATION_DATA
                          && (thisrr->type != SSL3_RT_CHANGE_CIPHER_SPEC
                              || !SSL_IS_FIRST_HANDSHAKE(s))) {
                      SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
                               SSL_F_SSL3_GET_RECORD, SSL_R_BAD_RECORD_TYPE);
                      return -1;
                  }
  
                  if (thisrr->length >
                      SSL3_BUFFER_get_len(rbuf) - SSL3_RT_HEADER_LENGTH) {
                      SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD,
                               SSL_R_PACKET_LENGTH_TOO_LONG);
                      return -1;
                  }
              }
  
              /* now s->rlayer.rstate == SSL_ST_READ_BODY */
          }
  
          if (SSL_IS_TLS13(s)) {
              if (thisrr->length > SSL3_RT_MAX_TLS13_ENCRYPTED_LENGTH) {
                  SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD,
                           SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
                  return -1;
              }
          } else {
              size_t len = SSL3_RT_MAX_ENCRYPTED_LENGTH;
  
  #ifndef OPENSSL_NO_COMP
              /*
               * If OPENSSL_NO_COMP is defined then SSL3_RT_MAX_ENCRYPTED_LENGTH
               * does not include the compression overhead anyway.
               */
              if (s->expand == NULL)
                  len -= SSL3_RT_MAX_COMPRESSED_OVERHEAD;
  #endif
  
              if (thisrr->length > len) {
                  SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD,
                           SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
                  return -1;
              }
          }
  
          /*
           * s->rlayer.rstate == SSL_ST_READ_BODY, get and decode the data.
           * Calculate how much more data we need to read for the rest of the
           * record
           */
          if (thisrr->rec_version == SSL2_VERSION) {
              more = thisrr->length + SSL2_RT_HEADER_LENGTH
                  - SSL3_RT_HEADER_LENGTH;
          } else {
              more = thisrr->length;
          }
          if (more > 0) {
              /* now s->packet_length == SSL3_RT_HEADER_LENGTH */
  
              rret = ssl3_read_n(s, more, more, 1, 0, &n);
              if (rret <= 0)
                  return rret;     /* error or non-blocking io */
          }
  
          /* set state for later operations */
          RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_HEADER);
  
          /*
           * At this point, s->packet_length == SSL3_RT_HEADER_LENGTH
           * + thisrr->length, or s->packet_length == SSL2_RT_HEADER_LENGTH
           * + thisrr->length and we have that many bytes in s->packet
           */
          if (thisrr->rec_version == SSL2_VERSION) {
              thisrr->input =
                  &(RECORD_LAYER_get_packet(&s->rlayer)[SSL2_RT_HEADER_LENGTH]);
          } else {
              thisrr->input =
                  &(RECORD_LAYER_get_packet(&s->rlayer)[SSL3_RT_HEADER_LENGTH]);
          }
  
          /*
           * ok, we can now read from 's->packet' data into 'thisrr' thisrr->input
           * points at thisrr->length bytes, which need to be copied into
           * thisrr->data by either the decryption or by the decompression When
           * the data is 'copied' into the thisrr->data buffer, thisrr->input will
           * be pointed at the new buffer
           */
  
          /*
           * We now have - encrypted [ MAC [ compressed [ plain ] ] ]
           * thisrr->length bytes of encrypted compressed stuff.
           */
  
          /* decrypt in place in 'thisrr->input' */
          thisrr->data = thisrr->input;
          thisrr->orig_len = thisrr->length;
  
          /* Mark this record as not read by upper layers yet */
          thisrr->read = 0;
  
          num_recs++;
  
          /* we have pulled in a full packet so zero things */
          RECORD_LAYER_reset_packet_length(&s->rlayer);
          RECORD_LAYER_clear_first_record(&s->rlayer);
      } while (num_recs < max_recs
               && thisrr->type == SSL3_RT_APPLICATION_DATA
               && SSL_USE_EXPLICIT_IV(s)
               && s->enc_read_ctx != NULL
               && (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_read_ctx))
                   & EVP_CIPH_FLAG_PIPELINE)
               && ssl3_record_app_data_waiting(s));
  
      if (num_recs == 1
              && thisrr->type == SSL3_RT_CHANGE_CIPHER_SPEC
              && (SSL_IS_TLS13(s) || s->hello_retry_request != SSL_HRR_NONE)
              && SSL_IS_FIRST_HANDSHAKE(s)) {
          /*
           * CCS messages must be exactly 1 byte long, containing the value 0x01
           */
          if (thisrr->length != 1 || thisrr->data[0] != 0x01) {
              SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_SSL3_GET_RECORD,
                       SSL_R_INVALID_CCS_MESSAGE);
              return -1;
          }
          /*
           * CCS messages are ignored in TLSv1.3. We treat it like an empty
           * handshake record
           */
          thisrr->type = SSL3_RT_HANDSHAKE;
          RECORD_LAYER_inc_empty_record_count(&s->rlayer);
          if (RECORD_LAYER_get_empty_record_count(&s->rlayer)
              > MAX_EMPTY_RECORDS) {
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD,
                       SSL_R_UNEXPECTED_CCS_MESSAGE);
              return -1;
          }
          thisrr->read = 1;
          RECORD_LAYER_set_numrpipes(&s->rlayer, 1);
  
          return 1;
      }
  
      /*
       * If in encrypt-then-mac mode calculate mac from encrypted record. All
       * the details below are public so no timing details can leak.
       */
      if (SSL_READ_ETM(s) && s->read_hash) {
          unsigned char *mac;
          /* TODO(size_t): convert this to do size_t properly */
          imac_size = EVP_MD_CTX_size(s->read_hash);
          if (!ossl_assert(imac_size >= 0 && imac_size <= EVP_MAX_MD_SIZE)) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD,
                           ERR_LIB_EVP);
                  return -1;
          }
          mac_size = (size_t)imac_size;
          for (j = 0; j < num_recs; j++) {
              thisrr = &rr[j];
  
              if (thisrr->length < mac_size) {
                  SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD,
                           SSL_R_LENGTH_TOO_SHORT);
                  return -1;
              }
              thisrr->length -= mac_size;
              mac = thisrr->data + thisrr->length;
              i = s->method->ssl3_enc->mac(s, thisrr, md, 0 /* not send */ );
              if (i == 0 || CRYPTO_memcmp(md, mac, mac_size) != 0) {
                  SSLfatal(s, SSL_AD_BAD_RECORD_MAC, SSL_F_SSL3_GET_RECORD,
                         SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
                  return -1;
              }
          }
      }
  
      first_rec_len = rr[0].length;
  
      enc_err = s->method->ssl3_enc->enc(s, rr, num_recs, 0);
  
      /*-
       * enc_err is:
       *    0: (in non-constant time) if the record is publicly invalid.
       *    1: if the padding is valid
       *    -1: if the padding is invalid
       */
      if (enc_err == 0) {
          if (ossl_statem_in_error(s)) {
              /* SSLfatal() already got called */
              return -1;
          }
          if (num_recs == 1 && ossl_statem_skip_early_data(s)) {
              /*
               * Valid early_data that we cannot decrypt might fail here as
               * publicly invalid. We treat it like an empty record.
               */
  
              thisrr = &rr[0];
  
              if (!early_data_count_ok(s, thisrr->length,
                                       EARLY_DATA_CIPHERTEXT_OVERHEAD, 0)) {
                  /* SSLfatal() already called */
                  return -1;
              }
  
              thisrr->length = 0;
              thisrr->read = 1;
              RECORD_LAYER_set_numrpipes(&s->rlayer, 1);
              RECORD_LAYER_reset_read_sequence(&s->rlayer);
              return 1;
          }
          SSLfatal(s, SSL_AD_DECRYPTION_FAILED, SSL_F_SSL3_GET_RECORD,
                   SSL_R_BLOCK_CIPHER_PAD_IS_WRONG);
          return -1;
      }
  #ifdef SSL_DEBUG
      printf("dec %"OSSLzu"\n", rr[0].length);
      {
          size_t z;
          for (z = 0; z < rr[0].length; z++)
              printf("%02X%c", rr[0].data[z], ((z + 1) % 16) ? ' ' : '\n');
      }
      printf("\n");
  #endif
  
      /* r->length is now the compressed data plus mac */
      if ((sess != NULL) &&
          (s->enc_read_ctx != NULL) &&
          (!SSL_READ_ETM(s) && EVP_MD_CTX_md(s->read_hash) != NULL)) {
          /* s->read_hash != NULL => mac_size != -1 */
          unsigned char *mac = NULL;
          unsigned char mac_tmp[EVP_MAX_MD_SIZE];
  
          mac_size = EVP_MD_CTX_size(s->read_hash);
          if (!ossl_assert(mac_size <= EVP_MAX_MD_SIZE)) {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD,
                       ERR_R_INTERNAL_ERROR);
              return -1;
          }
  
          for (j = 0; j < num_recs; j++) {
              thisrr = &rr[j];
              /*
               * orig_len is the length of the record before any padding was
               * removed. This is public information, as is the MAC in use,
               * therefore we can safely process the record in a different amount
               * of time if it's too short to possibly contain a MAC.
               */
              if (thisrr->orig_len < mac_size ||
                  /* CBC records must have a padding length byte too. */
                  (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
                   thisrr->orig_len < mac_size + 1)) {
                  SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_SSL3_GET_RECORD,
                           SSL_R_LENGTH_TOO_SHORT);
                  return -1;
              }
  
              if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE) {
                  /*
                   * We update the length so that the TLS header bytes can be
                   * constructed correctly but we need to extract the MAC in
                   * constant time from within the record, without leaking the
                   * contents of the padding bytes.
                   */
                  mac = mac_tmp;
                  if (!ssl3_cbc_copy_mac(mac_tmp, thisrr, mac_size)) {
                      SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_GET_RECORD,
                               ERR_R_INTERNAL_ERROR);
                      return -1;
                  }
                  thisrr->length -= mac_size;
              } else {
                  /*
                   * In this case there's no padding, so |rec->orig_len| equals
                   * |rec->length| and we checked that there's enough bytes for
                   * |mac_size| above.
                   */
                  thisrr->length -= mac_size;
                  mac = &thisrr->data[thisrr->length];
              }
  
              i = s->method->ssl3_enc->mac(s, thisrr, md, 0 /* not send */ );
              if (i == 0 || mac == NULL
                  || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0)
                  enc_err = -1;
              if (thisrr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
                  enc_err = -1;
          }
      }
  
      if (enc_err < 0) {
          if (ossl_statem_in_error(s)) {
              /* We already called SSLfatal() */
              return -1;
          }
          if (num_recs == 1 && ossl_statem_skip_early_data(s)) {
              /*
               * We assume this is unreadable early_data - we treat it like an
               * empty record
               */
  
              /*
               * The record length may have been modified by the mac check above
               * so we use the previously saved value
               */
              if (!early_data_count_ok(s, first_rec_len,
                                       EARLY_DATA_CIPHERTEXT_OVERHEAD, 0)) {
                  /* SSLfatal() already called */
                  return -1;
              }
  
              thisrr = &rr[0];
              thisrr->length = 0;
              thisrr->read = 1;
              RECORD_LAYER_set_numrpipes(&s->rlayer, 1);
              RECORD_LAYER_reset_read_sequence(&s->rlayer);
              return 1;
          }
          /*
           * A separate 'decryption_failed' alert was introduced with TLS 1.0,
           * SSL 3.0 only has 'bad_record_mac'.  But unless a decryption
           * failure is directly visible from the ciphertext anyway, we should
           * not reveal which kind of error occurred -- this might become
           * visible to an attacker (e.g. via a logfile)
           */
          SSLfatal(s, SSL_AD_BAD_RECORD_MAC, SSL_F_SSL3_GET_RECORD,
                   SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
          return -1;
      }
  
      for (j = 0; j < num_recs; j++) {
          thisrr = &rr[j];
  
          /* thisrr->length is now just compressed */
          if (s->expand != NULL) {
              if (thisrr->length > SSL3_RT_MAX_COMPRESSED_LENGTH) {
                  SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD,
                           SSL_R_COMPRESSED_LENGTH_TOO_LONG);
                  return -1;
              }
              if (!ssl3_do_uncompress(s, thisrr)) {
                  SSLfatal(s, SSL_AD_DECOMPRESSION_FAILURE, SSL_F_SSL3_GET_RECORD,
                           SSL_R_BAD_DECOMPRESSION);
                  return -1;
              }
          }
  
          if (SSL_IS_TLS13(s) && s->enc_read_ctx != NULL) {
              size_t end;
  
              if (thisrr->length == 0
                      || thisrr->type != SSL3_RT_APPLICATION_DATA) {
                  SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD,
                           SSL_R_BAD_RECORD_TYPE);
                  return -1;
              }
  
              /* Strip trailing padding */
              for (end = thisrr->length - 1; end > 0 && thisrr->data[end] == 0;
                   end--)
                  continue;
  
              thisrr->length = end;
              thisrr->type = thisrr->data[end];
              if (thisrr->type != SSL3_RT_APPLICATION_DATA
                      && thisrr->type != SSL3_RT_ALERT
                      && thisrr->type != SSL3_RT_HANDSHAKE) {
                  SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD,
                           SSL_R_BAD_RECORD_TYPE);
                  return -1;
              }
              if (s->msg_callback)
                  s->msg_callback(0, s->version, SSL3_RT_INNER_CONTENT_TYPE,
                                  &thisrr->data[end], 1, s, s->msg_callback_arg);
          }
  
          /*
           * TLSv1.3 alert and handshake records are required to be non-zero in
           * length.
           */
          if (SSL_IS_TLS13(s)
                  && (thisrr->type == SSL3_RT_HANDSHAKE
                      || thisrr->type == SSL3_RT_ALERT)
                  && thisrr->length == 0) {
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD,
                       SSL_R_BAD_LENGTH);
              return -1;
          }
  
          if (thisrr->length > SSL3_RT_MAX_PLAIN_LENGTH) {
              SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD,
                       SSL_R_DATA_LENGTH_TOO_LONG);
              return -1;
          }
  
          /* If received packet overflows current Max Fragment Length setting */
          if (s->session != NULL && USE_MAX_FRAGMENT_LENGTH_EXT(s->session)
                  && thisrr->length > GET_MAX_FRAGMENT_LENGTH(s->session)) {
              SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_SSL3_GET_RECORD,
                       SSL_R_DATA_LENGTH_TOO_LONG);
              return -1;
          }
  
          thisrr->off = 0;
          /*-
           * So at this point the following is true
           * thisrr->type   is the type of record
           * thisrr->length == number of bytes in record
           * thisrr->off    == offset to first valid byte
           * thisrr->data   == where to take bytes from, increment after use :-).
           */
  
          /* just read a 0 length packet */
          if (thisrr->length == 0) {
              RECORD_LAYER_inc_empty_record_count(&s->rlayer);
              if (RECORD_LAYER_get_empty_record_count(&s->rlayer)
                  > MAX_EMPTY_RECORDS) {
                  SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_SSL3_GET_RECORD,
                           SSL_R_RECORD_TOO_SMALL);
                  return -1;
              }
          } else {
              RECORD_LAYER_reset_empty_record_count(&s->rlayer);
          }
      }
  
      if (s->early_data_state == SSL_EARLY_DATA_READING) {
          thisrr = &rr[0];
          if (thisrr->type == SSL3_RT_APPLICATION_DATA
                  && !early_data_count_ok(s, thisrr->length, 0, 0)) {
              /* SSLfatal already called */
              return -1;
          }
      }
  
      RECORD_LAYER_set_numrpipes(&s->rlayer, num_recs);
      return 1;
  }
  
  int ssl3_do_uncompress(SSL *ssl, SSL3_RECORD *rr)
  {
  #ifndef OPENSSL_NO_COMP
      int i;
  
      if (rr->comp == NULL) {
          rr->comp = (unsigned char *)
              OPENSSL_malloc(SSL3_RT_MAX_ENCRYPTED_LENGTH);
      }
      if (rr->comp == NULL)
          return 0;
  
      /* TODO(size_t): Convert this call */
      i = COMP_expand_block(ssl->expand, rr->comp,
                            SSL3_RT_MAX_PLAIN_LENGTH, rr->data, (int)rr->length);
      if (i < 0)
          return 0;
      else
          rr->length = i;
      rr->data = rr->comp;
  #endif
      return 1;
  }
  
  int ssl3_do_compress(SSL *ssl, SSL3_RECORD *wr)
  {
  #ifndef OPENSSL_NO_COMP
      int i;
  
      /* TODO(size_t): Convert this call */
      i = COMP_compress_block(ssl->compress, wr->data,
                              (int)(wr->length + SSL3_RT_MAX_COMPRESSED_OVERHEAD),
                              wr->input, (int)wr->length);
      if (i < 0)
          return 0;
      else
          wr->length = i;
  
      wr->input = wr->data;
  #endif
      return 1;
  }
  
  /*-
   * ssl3_enc encrypts/decrypts |n_recs| records in |inrecs|.  Will call
   * SSLfatal() for internal errors, but not otherwise.
   *
   * Returns:
   *   0: (in non-constant time) if the record is publically invalid (i.e. too
   *       short etc).
   *   1: if the record's padding is valid / the encryption was successful.
   *   -1: if the record's padding is invalid or, if sending, an internal error
   *       occurred.
   */
  int ssl3_enc(SSL *s, SSL3_RECORD *inrecs, size_t n_recs, int sending)
  {
      SSL3_RECORD *rec;
      EVP_CIPHER_CTX *ds;
      size_t l, i;
      size_t bs, mac_size = 0;
      int imac_size;
      const EVP_CIPHER *enc;
  
      rec = inrecs;
      /*
       * We shouldn't ever be called with more than one record in the SSLv3 case
       */
      if (n_recs != 1)
          return 0;
      if (sending) {
          ds = s->enc_write_ctx;
          if (s->enc_write_ctx == NULL)
              enc = NULL;
          else
              enc = EVP_CIPHER_CTX_cipher(s->enc_write_ctx);
      } else {
          ds = s->enc_read_ctx;
          if (s->enc_read_ctx == NULL)
              enc = NULL;
          else
              enc = EVP_CIPHER_CTX_cipher(s->enc_read_ctx);
      }
  
      if ((s->session == NULL) || (ds == NULL) || (enc == NULL)) {
          memmove(rec->data, rec->input, rec->length);
          rec->input = rec->data;
      } else {
          l = rec->length;
          /* TODO(size_t): Convert this call */
          bs = EVP_CIPHER_CTX_block_size(ds);
  
          /* COMPRESS */
  
          if ((bs != 1) && sending) {
              i = bs - (l % bs);
  
              /* we need to add 'i-1' padding bytes */
              l += i;
              /*
               * the last of these zero bytes will be overwritten with the
               * padding length.
               */
              memset(&rec->input[rec->length], 0, i);
              rec->length += i;
              rec->input[l - 1] = (unsigned char)(i - 1);
          }
  
          if (!sending) {
              if (l == 0 || l % bs != 0)
                  return 0;
              /* otherwise, rec->length >= bs */
          }
  
          /* TODO(size_t): Convert this call */
          if (EVP_Cipher(ds, rec->data, rec->input, (unsigned int)l) < 1)
              return -1;
  
          if (EVP_MD_CTX_md(s->read_hash) != NULL) {
              /* TODO(size_t): convert me */
              imac_size = EVP_MD_CTX_size(s->read_hash);
              if (imac_size < 0) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL3_ENC,
                           ERR_R_INTERNAL_ERROR);
                  return -1;
              }
              mac_size = (size_t)imac_size;
          }
          if ((bs != 1) && !sending)
              return ssl3_cbc_remove_padding(rec, bs, mac_size);
      }
      return 1;
  }
  
  #define MAX_PADDING 256
  /*-
   * tls1_enc encrypts/decrypts |n_recs| in |recs|.  Will call SSLfatal() for
   * internal errors, but not otherwise.
   *
   * Returns:
   *   0: (in non-constant time) if the record is publically invalid (i.e. too
   *       short etc).
   *   1: if the record's padding is valid / the encryption was successful.
   *   -1: if the record's padding/AEAD-authenticator is invalid or, if sending,
   *       an internal error occurred.
   */
  int tls1_enc(SSL *s, SSL3_RECORD *recs, size_t n_recs, int sending)
  {
      EVP_CIPHER_CTX *ds;
      size_t reclen[SSL_MAX_PIPELINES];
      unsigned char buf[SSL_MAX_PIPELINES][EVP_AEAD_TLS1_AAD_LEN];
      int i, pad = 0, ret, tmpr;
      size_t bs, mac_size = 0, ctr, padnum, loop;
      unsigned char padval;
      int imac_size;
      const EVP_CIPHER *enc;
  
      if (n_recs == 0) {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                   ERR_R_INTERNAL_ERROR);
          return 0;
      }
  
      if (sending) {
          if (EVP_MD_CTX_md(s->write_hash)) {
              int n = EVP_MD_CTX_size(s->write_hash);
              if (!ossl_assert(n >= 0)) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                           ERR_R_INTERNAL_ERROR);
                  return -1;
              }
          }
          ds = s->enc_write_ctx;
          if (s->enc_write_ctx == NULL)
              enc = NULL;
          else {
              int ivlen;
              enc = EVP_CIPHER_CTX_cipher(s->enc_write_ctx);
              /* For TLSv1.1 and later explicit IV */
              if (SSL_USE_EXPLICIT_IV(s)
                  && EVP_CIPHER_mode(enc) == EVP_CIPH_CBC_MODE)
                  ivlen = EVP_CIPHER_iv_length(enc);
              else
                  ivlen = 0;
              if (ivlen > 1) {
                  for (ctr = 0; ctr < n_recs; ctr++) {
                      if (recs[ctr].data != recs[ctr].input) {
                          /*
                           * we can't write into the input stream: Can this ever
                           * happen?? (steve)
                           */
                          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                                   ERR_R_INTERNAL_ERROR);
                          return -1;
                      } else if (ssl_randbytes(s, recs[ctr].input, ivlen) <= 0) {
                          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                                   ERR_R_INTERNAL_ERROR);
                          return -1;
                      }
                  }
              }
          }
      } else {
          if (EVP_MD_CTX_md(s->read_hash)) {
              int n = EVP_MD_CTX_size(s->read_hash);
              if (!ossl_assert(n >= 0)) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                           ERR_R_INTERNAL_ERROR);
                  return -1;
              }
          }
          ds = s->enc_read_ctx;
          if (s->enc_read_ctx == NULL)
              enc = NULL;
          else
              enc = EVP_CIPHER_CTX_cipher(s->enc_read_ctx);
      }
  
      if ((s->session == NULL) || (ds == NULL) || (enc == NULL)) {
          for (ctr = 0; ctr < n_recs; ctr++) {
              memmove(recs[ctr].data, recs[ctr].input, recs[ctr].length);
              recs[ctr].input = recs[ctr].data;
          }
          ret = 1;
      } else {
          bs = EVP_CIPHER_block_size(EVP_CIPHER_CTX_cipher(ds));
  
          if (n_recs > 1) {
              if (!(EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds))
                    & EVP_CIPH_FLAG_PIPELINE)) {
                  /*
                   * We shouldn't have been called with pipeline data if the
                   * cipher doesn't support pipelining
                   */
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                           SSL_R_PIPELINE_FAILURE);
                  return -1;
              }
          }
          for (ctr = 0; ctr < n_recs; ctr++) {
              reclen[ctr] = recs[ctr].length;
  
              if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds))
                  & EVP_CIPH_FLAG_AEAD_CIPHER) {
                  unsigned char *seq;
  
                  seq = sending ? RECORD_LAYER_get_write_sequence(&s->rlayer)
                      : RECORD_LAYER_get_read_sequence(&s->rlayer);
  
                  if (SSL_IS_DTLS(s)) {
                      /* DTLS does not support pipelining */
                      unsigned char dtlsseq[9], *p = dtlsseq;
  
                      s2n(sending ? DTLS_RECORD_LAYER_get_w_epoch(&s->rlayer) :
                          DTLS_RECORD_LAYER_get_r_epoch(&s->rlayer), p);
                      memcpy(p, &seq[2], 6);
                      memcpy(buf[ctr], dtlsseq, 8);
                  } else {
                      memcpy(buf[ctr], seq, 8);
                      for (i = 7; i >= 0; i--) { /* increment */
                          ++seq[i];
                          if (seq[i] != 0)
                              break;
                      }
                  }
  
                  buf[ctr][8] = recs[ctr].type;
                  buf[ctr][9] = (unsigned char)(s->version >> 8);
                  buf[ctr][10] = (unsigned char)(s->version);
                  buf[ctr][11] = (unsigned char)(recs[ctr].length >> 8);
                  buf[ctr][12] = (unsigned char)(recs[ctr].length & 0xff);
                  pad = EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_AEAD_TLS1_AAD,
                                            EVP_AEAD_TLS1_AAD_LEN, buf[ctr]);
                  if (pad <= 0) {
                      SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                               ERR_R_INTERNAL_ERROR);
                      return -1;
                  }
  
                  if (sending) {
                      reclen[ctr] += pad;
                      recs[ctr].length += pad;
                  }
  
              } else if ((bs != 1) && sending) {
                  padnum = bs - (reclen[ctr] % bs);
  
                  /* Add weird padding of upto 256 bytes */
  
                  if (padnum > MAX_PADDING) {
                      SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                               ERR_R_INTERNAL_ERROR);
                      return -1;
                  }
                  /* we need to add 'padnum' padding bytes of value padval */
                  padval = (unsigned char)(padnum - 1);
                  for (loop = reclen[ctr]; loop < reclen[ctr] + padnum; loop++)
                      recs[ctr].input[loop] = padval;
                  reclen[ctr] += padnum;
                  recs[ctr].length += padnum;
              }
  
              if (!sending) {
                  if (reclen[ctr] == 0 || reclen[ctr] % bs != 0)
                      return 0;
              }
          }
          if (n_recs > 1) {
              unsigned char *data[SSL_MAX_PIPELINES];
  
              /* Set the output buffers */
              for (ctr = 0; ctr < n_recs; ctr++) {
                  data[ctr] = recs[ctr].data;
              }
              if (EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_OUTPUT_BUFS,
                                      (int)n_recs, data) <= 0) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                           SSL_R_PIPELINE_FAILURE);
                  return -1;
              }
              /* Set the input buffers */
              for (ctr = 0; ctr < n_recs; ctr++) {
                  data[ctr] = recs[ctr].input;
              }
              if (EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_INPUT_BUFS,
                                      (int)n_recs, data) <= 0
                  || EVP_CIPHER_CTX_ctrl(ds, EVP_CTRL_SET_PIPELINE_INPUT_LENS,
                                         (int)n_recs, reclen) <= 0) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                           SSL_R_PIPELINE_FAILURE);
                  return -1;
              }
          }
  
          /* TODO(size_t): Convert this call */
          tmpr = EVP_Cipher(ds, recs[0].data, recs[0].input,
                            (unsigned int)reclen[0]);
          if ((EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(ds))
               & EVP_CIPH_FLAG_CUSTOM_CIPHER)
              ? (tmpr < 0)
              : (tmpr == 0))
              return -1;          /* AEAD can fail to verify MAC */
  
          if (sending == 0) {
              if (EVP_CIPHER_mode(enc) == EVP_CIPH_GCM_MODE) {
                  for (ctr = 0; ctr < n_recs; ctr++) {
                      recs[ctr].data += EVP_GCM_TLS_EXPLICIT_IV_LEN;
                      recs[ctr].input += EVP_GCM_TLS_EXPLICIT_IV_LEN;
                      recs[ctr].length -= EVP_GCM_TLS_EXPLICIT_IV_LEN;
                  }
              } else if (EVP_CIPHER_mode(enc) == EVP_CIPH_CCM_MODE) {
                  for (ctr = 0; ctr < n_recs; ctr++) {
                      recs[ctr].data += EVP_CCM_TLS_EXPLICIT_IV_LEN;
                      recs[ctr].input += EVP_CCM_TLS_EXPLICIT_IV_LEN;
                      recs[ctr].length -= EVP_CCM_TLS_EXPLICIT_IV_LEN;
                  }
              }
          }
  
          ret = 1;
          if (!SSL_READ_ETM(s) && EVP_MD_CTX_md(s->read_hash) != NULL) {
              imac_size = EVP_MD_CTX_size(s->read_hash);
              if (imac_size < 0) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS1_ENC,
                           ERR_R_INTERNAL_ERROR);
                  return -1;
              }
              mac_size = (size_t)imac_size;
          }
          if ((bs != 1) && !sending) {
              int tmpret;
              for (ctr = 0; ctr < n_recs; ctr++) {
                  tmpret = tls1_cbc_remove_padding(s, &recs[ctr], bs, mac_size);
                  /*
                   * If tmpret == 0 then this means publicly invalid so we can
                   * short circuit things here. Otherwise we must respect constant
                   * time behaviour.
                   */
                  if (tmpret == 0)
                      return 0;
                  ret = constant_time_select_int(constant_time_eq_int(tmpret, 1),
                                                 ret, -1);
              }
          }
          if (pad && !sending) {
              for (ctr = 0; ctr < n_recs; ctr++) {
                  recs[ctr].length -= pad;
              }
          }
      }
      return ret;
  }
  
  int n_ssl3_mac(SSL *ssl, SSL3_RECORD *rec, unsigned char *md, int sending)
  {
      unsigned char *mac_sec, *seq;
      const EVP_MD_CTX *hash;
      unsigned char *p, rec_char;
      size_t md_size;
      size_t npad;
      int t;
  
      if (sending) {
          mac_sec = &(ssl->s3->write_mac_secret[0]);
          seq = RECORD_LAYER_get_write_sequence(&ssl->rlayer);
          hash = ssl->write_hash;
      } else {
          mac_sec = &(ssl->s3->read_mac_secret[0]);
          seq = RECORD_LAYER_get_read_sequence(&ssl->rlayer);
          hash = ssl->read_hash;
      }
  
      t = EVP_MD_CTX_size(hash);
      if (t < 0)
          return 0;
      md_size = t;
      npad = (48 / md_size) * md_size;
  
      if (!sending &&
          EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
          ssl3_cbc_record_digest_supported(hash)) {
          /*
           * This is a CBC-encrypted record. We must avoid leaking any
           * timing-side channel information about how many blocks of data we
           * are hashing because that gives an attacker a timing-oracle.
           */
  
          /*-
           * npad is, at most, 48 bytes and that's with MD5:
           *   16 + 48 + 8 (sequence bytes) + 1 + 2 = 75.
           *
           * With SHA-1 (the largest hash speced for SSLv3) the hash size
           * goes up 4, but npad goes down by 8, resulting in a smaller
           * total size.
           */
          unsigned char header[75];
          size_t j = 0;
          memcpy(header + j, mac_sec, md_size);
          j += md_size;
          memcpy(header + j, ssl3_pad_1, npad);
          j += npad;
          memcpy(header + j, seq, 8);
          j += 8;
          header[j++] = rec->type;
          header[j++] = (unsigned char)(rec->length >> 8);
          header[j++] = (unsigned char)(rec->length & 0xff);
  
          /* Final param == is SSLv3 */
          if (ssl3_cbc_digest_record(hash,
                                     md, &md_size,
                                     header, rec->input,
                                     rec->length + md_size, rec->orig_len,
                                     mac_sec, md_size, 1) <= 0)
              return 0;
      } else {
          unsigned int md_size_u;
          /* Chop the digest off the end :-) */
          EVP_MD_CTX *md_ctx = EVP_MD_CTX_new();
  
          if (md_ctx == NULL)
              return 0;
  
          rec_char = rec->type;
          p = md;
          s2n(rec->length, p);
          if (EVP_MD_CTX_copy_ex(md_ctx, hash) <= 0
              || EVP_DigestUpdate(md_ctx, mac_sec, md_size) <= 0
              || EVP_DigestUpdate(md_ctx, ssl3_pad_1, npad) <= 0
              || EVP_DigestUpdate(md_ctx, seq, 8) <= 0
              || EVP_DigestUpdate(md_ctx, &rec_char, 1) <= 0
              || EVP_DigestUpdate(md_ctx, md, 2) <= 0
              || EVP_DigestUpdate(md_ctx, rec->input, rec->length) <= 0
              || EVP_DigestFinal_ex(md_ctx, md, NULL) <= 0
              || EVP_MD_CTX_copy_ex(md_ctx, hash) <= 0
              || EVP_DigestUpdate(md_ctx, mac_sec, md_size) <= 0
              || EVP_DigestUpdate(md_ctx, ssl3_pad_2, npad) <= 0
              || EVP_DigestUpdate(md_ctx, md, md_size) <= 0
              || EVP_DigestFinal_ex(md_ctx, md, &md_size_u) <= 0) {
              EVP_MD_CTX_reset(md_ctx);
              return 0;
          }
  
          EVP_MD_CTX_free(md_ctx);
      }
  
      ssl3_record_sequence_update(seq);
      return 1;
  }
  
  int tls1_mac(SSL *ssl, SSL3_RECORD *rec, unsigned char *md, int sending)
  {
      unsigned char *seq;
      EVP_MD_CTX *hash;
      size_t md_size;
      int i;
      EVP_MD_CTX *hmac = NULL, *mac_ctx;
      unsigned char header[13];
      int stream_mac = (sending ? (ssl->mac_flags & SSL_MAC_FLAG_WRITE_MAC_STREAM)
                        : (ssl->mac_flags & SSL_MAC_FLAG_READ_MAC_STREAM));
      int t;
  
      if (sending) {
          seq = RECORD_LAYER_get_write_sequence(&ssl->rlayer);
          hash = ssl->write_hash;
      } else {
          seq = RECORD_LAYER_get_read_sequence(&ssl->rlayer);
          hash = ssl->read_hash;
      }
  
      t = EVP_MD_CTX_size(hash);
      if (!ossl_assert(t >= 0))
          return 0;
      md_size = t;
  
      /* I should fix this up TLS TLS TLS TLS TLS XXXXXXXX */
      if (stream_mac) {
          mac_ctx = hash;
      } else {
          hmac = EVP_MD_CTX_new();
          if (hmac == NULL || !EVP_MD_CTX_copy(hmac, hash))
              return 0;
          mac_ctx = hmac;
      }
  
      if (SSL_IS_DTLS(ssl)) {
          unsigned char dtlsseq[8], *p = dtlsseq;
  
          s2n(sending ? DTLS_RECORD_LAYER_get_w_epoch(&ssl->rlayer) :
              DTLS_RECORD_LAYER_get_r_epoch(&ssl->rlayer), p);
          memcpy(p, &seq[2], 6);
  
          memcpy(header, dtlsseq, 8);
      } else
          memcpy(header, seq, 8);
  
      header[8] = rec->type;
      header[9] = (unsigned char)(ssl->version >> 8);
      header[10] = (unsigned char)(ssl->version);
      header[11] = (unsigned char)(rec->length >> 8);
      header[12] = (unsigned char)(rec->length & 0xff);
  
      if (!sending && !SSL_READ_ETM(ssl) &&
          EVP_CIPHER_CTX_mode(ssl->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
          ssl3_cbc_record_digest_supported(mac_ctx)) {
          /*
           * This is a CBC-encrypted record. We must avoid leaking any
           * timing-side channel information about how many blocks of data we
           * are hashing because that gives an attacker a timing-oracle.
           */
          /* Final param == not SSLv3 */
          if (ssl3_cbc_digest_record(mac_ctx,
                                     md, &md_size,
                                     header, rec->input,
                                     rec->length + md_size, rec->orig_len,
                                     ssl->s3->read_mac_secret,
                                     ssl->s3->read_mac_secret_size, 0) <= 0) {
              EVP_MD_CTX_free(hmac);
              return 0;
          }
      } else {
          /* TODO(size_t): Convert these calls */
          if (EVP_DigestSignUpdate(mac_ctx, header, sizeof(header)) <= 0
              || EVP_DigestSignUpdate(mac_ctx, rec->input, rec->length) <= 0
              || EVP_DigestSignFinal(mac_ctx, md, &md_size) <= 0) {
              EVP_MD_CTX_free(hmac);
              return 0;
          }
      }
  
      EVP_MD_CTX_free(hmac);
  
  #ifdef SSL_DEBUG
      fprintf(stderr, "seq=");
      {
          int z;
          for (z = 0; z < 8; z++)
              fprintf(stderr, "%02X ", seq[z]);
          fprintf(stderr, "\n");
      }
      fprintf(stderr, "rec=");
      {
          size_t z;
          for (z = 0; z < rec->length; z++)
              fprintf(stderr, "%02X ", rec->data[z]);
          fprintf(stderr, "\n");
      }
  #endif
  
      if (!SSL_IS_DTLS(ssl)) {
          for (i = 7; i >= 0; i--) {
              ++seq[i];
              if (seq[i] != 0)
                  break;
          }
      }
  #ifdef SSL_DEBUG
      {
          unsigned int z;
          for (z = 0; z < md_size; z++)
              fprintf(stderr, "%02X ", md[z]);
          fprintf(stderr, "\n");
      }
  #endif
      return 1;
  }
  
  /*-
   * ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC
   * record in |rec| by updating |rec->length| in constant time.
   *
   * block_size: the block size of the cipher used to encrypt the record.
   * returns:
   *   0: (in non-constant time) if the record is publicly invalid.
   *   1: if the padding was valid
   *  -1: otherwise.
   */
  int ssl3_cbc_remove_padding(SSL3_RECORD *rec,
                              size_t block_size, size_t mac_size)
  {
      size_t padding_length;
      size_t good;
      const size_t overhead = 1 /* padding length byte */  + mac_size;
  
      /*
       * These lengths are all public so we can test them in non-constant time.
       */
      if (overhead > rec->length)
          return 0;
  
      padding_length = rec->data[rec->length - 1];
      good = constant_time_ge_s(rec->length, padding_length + overhead);
      /* SSLv3 requires that the padding is minimal. */
      good &= constant_time_ge_s(block_size, padding_length + 1);
      rec->length -= good & (padding_length + 1);
      return constant_time_select_int_s(good, 1, -1);
  }
  
  /*-
   * tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC
   * record in |rec| in constant time and returns 1 if the padding is valid and
   * -1 otherwise. It also removes any explicit IV from the start of the record
   * without leaking any timing about whether there was enough space after the
   * padding was removed.
   *
   * block_size: the block size of the cipher used to encrypt the record.
   * returns:
   *   0: (in non-constant time) if the record is publicly invalid.
   *   1: if the padding was valid
   *  -1: otherwise.
   */
  int tls1_cbc_remove_padding(const SSL *s,
                              SSL3_RECORD *rec,
                              size_t block_size, size_t mac_size)
  {
      size_t good;
      size_t padding_length, to_check, i;
      const size_t overhead = 1 /* padding length byte */  + mac_size;
      /* Check if version requires explicit IV */
      if (SSL_USE_EXPLICIT_IV(s)) {
          /*
           * These lengths are all public so we can test them in non-constant
           * time.
           */
          if (overhead + block_size > rec->length)
              return 0;
          /* We can now safely skip explicit IV */
          rec->data += block_size;
          rec->input += block_size;
          rec->length -= block_size;
          rec->orig_len -= block_size;
      } else if (overhead > rec->length)
          return 0;
  
      padding_length = rec->data[rec->length - 1];
  
      if (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_read_ctx)) &
          EVP_CIPH_FLAG_AEAD_CIPHER) {
          /* padding is already verified */
          rec->length -= padding_length + 1;
          return 1;
      }
  
      good = constant_time_ge_s(rec->length, overhead + padding_length);
      /*
       * The padding consists of a length byte at the end of the record and
       * then that many bytes of padding, all with the same value as the length
       * byte. Thus, with the length byte included, there are i+1 bytes of
       * padding. We can't check just |padding_length+1| bytes because that
       * leaks decrypted information. Therefore we always have to check the
       * maximum amount of padding possible. (Again, the length of the record
       * is public information so we can use it.)
       */
      to_check = 256;            /* maximum amount of padding, inc length byte. */
      if (to_check > rec->length)
          to_check = rec->length;
  
      for (i = 0; i < to_check; i++) {
          unsigned char mask = constant_time_ge_8_s(padding_length, i);
          unsigned char b = rec->data[rec->length - 1 - i];
          /*
           * The final |padding_length+1| bytes should all have the value
           * |padding_length|. Therefore the XOR should be zero.
           */
          good &= ~(mask & (padding_length ^ b));
      }
  
      /*
       * If any of the final |padding_length+1| bytes had the wrong value, one
       * or more of the lower eight bits of |good| will be cleared.
       */
      good = constant_time_eq_s(0xff, good & 0xff);
      rec->length -= good & (padding_length + 1);
  
      return constant_time_select_int_s(good, 1, -1);
  }
  
  /*-
   * ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in
   * constant time (independent of the concrete value of rec->length, which may
   * vary within a 256-byte window).
   *
   * ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to
   * this function.
   *
   * On entry:
   *   rec->orig_len >= md_size
   *   md_size <= EVP_MAX_MD_SIZE
   *
   * If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with
   * variable accesses in a 64-byte-aligned buffer. Assuming that this fits into
   * a single or pair of cache-lines, then the variable memory accesses don't
   * actually affect the timing. CPUs with smaller cache-lines [if any] are
   * not multi-core and are not considered vulnerable to cache-timing attacks.
   */
  #define CBC_MAC_ROTATE_IN_PLACE
  
  int ssl3_cbc_copy_mac(unsigned char *out,
                         const SSL3_RECORD *rec, size_t md_size)
  {
  #if defined(CBC_MAC_ROTATE_IN_PLACE)
      unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE];
      unsigned char *rotated_mac;
  #else
      unsigned char rotated_mac[EVP_MAX_MD_SIZE];
  #endif
  
      /*
       * mac_end is the index of |rec->data| just after the end of the MAC.
       */
      size_t mac_end = rec->length;
      size_t mac_start = mac_end - md_size;
      size_t in_mac;
      /*
       * scan_start contains the number of bytes that we can ignore because the
       * MAC's position can only vary by 255 bytes.
       */
      size_t scan_start = 0;
      size_t i, j;
      size_t rotate_offset;
  
      if (!ossl_assert(rec->orig_len >= md_size
                       && md_size <= EVP_MAX_MD_SIZE))
          return 0;
  
  #if defined(CBC_MAC_ROTATE_IN_PLACE)
      rotated_mac = rotated_mac_buf + ((0 - (size_t)rotated_mac_buf) & 63);
  #endif
  
      /* This information is public so it's safe to branch based on it. */
      if (rec->orig_len > md_size + 255 + 1)
          scan_start = rec->orig_len - (md_size + 255 + 1);
  
      in_mac = 0;
      rotate_offset = 0;
      memset(rotated_mac, 0, md_size);
      for (i = scan_start, j = 0; i < rec->orig_len; i++) {
          size_t mac_started = constant_time_eq_s(i, mac_start);
          size_t mac_ended = constant_time_lt_s(i, mac_end);
          unsigned char b = rec->data[i];
  
          in_mac |= mac_started;
          in_mac &= mac_ended;
          rotate_offset |= j & mac_started;
          rotated_mac[j++] |= b & in_mac;
          j &= constant_time_lt_s(j, md_size);
      }
  
      /* Now rotate the MAC */
  #if defined(CBC_MAC_ROTATE_IN_PLACE)
      j = 0;
      for (i = 0; i < md_size; i++) {
          /* in case cache-line is 32 bytes, touch second line */
          ((volatile unsigned char *)rotated_mac)[rotate_offset ^ 32];
          out[j++] = rotated_mac[rotate_offset++];
          rotate_offset &= constant_time_lt_s(rotate_offset, md_size);
      }
  #else
      memset(out, 0, md_size);
      rotate_offset = md_size - rotate_offset;
      rotate_offset &= constant_time_lt_s(rotate_offset, md_size);
      for (i = 0; i < md_size; i++) {
          for (j = 0; j < md_size; j++)
              out[j] |= rotated_mac[i] & constant_time_eq_8_s(j, rotate_offset);
          rotate_offset++;
          rotate_offset &= constant_time_lt_s(rotate_offset, md_size);
      }
  #endif
  
      return 1;
  }
  
  int dtls1_process_record(SSL *s, DTLS1_BITMAP *bitmap)
  {
      int i;
      int enc_err;
      SSL_SESSION *sess;
      SSL3_RECORD *rr;
      int imac_size;
      size_t mac_size;
      unsigned char md[EVP_MAX_MD_SIZE];
  
      rr = RECORD_LAYER_get_rrec(&s->rlayer);
      sess = s->session;
  
      /*
       * At this point, s->packet_length == SSL3_RT_HEADER_LNGTH + rr->length,
       * and we have that many bytes in s->packet
       */
      rr->input = &(RECORD_LAYER_get_packet(&s->rlayer)[DTLS1_RT_HEADER_LENGTH]);
  
      /*
       * ok, we can now read from 's->packet' data into 'rr' rr->input points
       * at rr->length bytes, which need to be copied into rr->data by either
       * the decryption or by the decompression When the data is 'copied' into
       * the rr->data buffer, rr->input will be pointed at the new buffer
       */
  
      /*
       * We now have - encrypted [ MAC [ compressed [ plain ] ] ] rr->length
       * bytes of encrypted compressed stuff.
       */
  
      /* check is not needed I believe */
      if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
          SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_DTLS1_PROCESS_RECORD,
                   SSL_R_ENCRYPTED_LENGTH_TOO_LONG);
          return 0;
      }
  
      /* decrypt in place in 'rr->input' */
      rr->data = rr->input;
      rr->orig_len = rr->length;
  
      if (SSL_READ_ETM(s) && s->read_hash) {
          unsigned char *mac;
          mac_size = EVP_MD_CTX_size(s->read_hash);
          if (!ossl_assert(mac_size <= EVP_MAX_MD_SIZE)) {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD,
                       ERR_R_INTERNAL_ERROR);
              return 0;
          }
          if (rr->orig_len < mac_size) {
              SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_DTLS1_PROCESS_RECORD,
                       SSL_R_LENGTH_TOO_SHORT);
              return 0;
          }
          rr->length -= mac_size;
          mac = rr->data + rr->length;
          i = s->method->ssl3_enc->mac(s, rr, md, 0 /* not send */ );
          if (i == 0 || CRYPTO_memcmp(md, mac, (size_t)mac_size) != 0) {
              SSLfatal(s, SSL_AD_BAD_RECORD_MAC, SSL_F_DTLS1_PROCESS_RECORD,
                     SSL_R_DECRYPTION_FAILED_OR_BAD_RECORD_MAC);
              return 0;
          }
      }
  
      enc_err = s->method->ssl3_enc->enc(s, rr, 1, 0);
      /*-
       * enc_err is:
       *    0: (in non-constant time) if the record is publically invalid.
       *    1: if the padding is valid
       *   -1: if the padding is invalid
       */
      if (enc_err == 0) {
          if (ossl_statem_in_error(s)) {
              /* SSLfatal() got called */
              return 0;
          }
          /* For DTLS we simply ignore bad packets. */
          rr->length = 0;
          RECORD_LAYER_reset_packet_length(&s->rlayer);
          return 0;
      }
  #ifdef SSL_DEBUG
      printf("dec %ld\n", rr->length);
      {
          size_t z;
          for (z = 0; z < rr->length; z++)
              printf("%02X%c", rr->data[z], ((z + 1) % 16) ? ' ' : '\n');
      }
      printf("\n");
  #endif
  
      /* r->length is now the compressed data plus mac */
      if ((sess != NULL) && !SSL_READ_ETM(s) &&
          (s->enc_read_ctx != NULL) && (EVP_MD_CTX_md(s->read_hash) != NULL)) {
          /* s->read_hash != NULL => mac_size != -1 */
          unsigned char *mac = NULL;
          unsigned char mac_tmp[EVP_MAX_MD_SIZE];
  
          /* TODO(size_t): Convert this to do size_t properly */
          imac_size = EVP_MD_CTX_size(s->read_hash);
          if (imac_size < 0) {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD,
                       ERR_LIB_EVP);
              return 0;
          }
          mac_size = (size_t)imac_size;
          if (!ossl_assert(mac_size <= EVP_MAX_MD_SIZE)) {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD,
                       ERR_R_INTERNAL_ERROR);
              return 0;
          }
  
          /*
           * orig_len is the length of the record before any padding was
           * removed. This is public information, as is the MAC in use,
           * therefore we can safely process the record in a different amount
           * of time if it's too short to possibly contain a MAC.
           */
          if (rr->orig_len < mac_size ||
              /* CBC records must have a padding length byte too. */
              (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE &&
               rr->orig_len < mac_size + 1)) {
              SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_F_DTLS1_PROCESS_RECORD,
                       SSL_R_LENGTH_TOO_SHORT);
              return 0;
          }
  
          if (EVP_CIPHER_CTX_mode(s->enc_read_ctx) == EVP_CIPH_CBC_MODE) {
              /*
               * We update the length so that the TLS header bytes can be
               * constructed correctly but we need to extract the MAC in
               * constant time from within the record, without leaking the
               * contents of the padding bytes.
               */
              mac = mac_tmp;
              if (!ssl3_cbc_copy_mac(mac_tmp, rr, mac_size)) {
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PROCESS_RECORD,
                           ERR_R_INTERNAL_ERROR);
                  return 0;
              }
              rr->length -= mac_size;
          } else {
              /*
               * In this case there's no padding, so |rec->orig_len| equals
               * |rec->length| and we checked that there's enough bytes for
               * |mac_size| above.
               */
              rr->length -= mac_size;
              mac = &rr->data[rr->length];
          }
  
          i = s->method->ssl3_enc->mac(s, rr, md, 0 /* not send */ );
          if (i == 0 || mac == NULL
              || CRYPTO_memcmp(md, mac, mac_size) != 0)
              enc_err = -1;
          if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH + mac_size)
              enc_err = -1;
      }
  
      if (enc_err < 0) {
          /* decryption failed, silently discard message */
          rr->length = 0;
          RECORD_LAYER_reset_packet_length(&s->rlayer);
          return 0;
      }
  
      /* r->length is now just compressed */
      if (s->expand != NULL) {
          if (rr->length > SSL3_RT_MAX_COMPRESSED_LENGTH) {
              SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_DTLS1_PROCESS_RECORD,
                       SSL_R_COMPRESSED_LENGTH_TOO_LONG);
              return 0;
          }
          if (!ssl3_do_uncompress(s, rr)) {
              SSLfatal(s, SSL_AD_DECOMPRESSION_FAILURE,
                       SSL_F_DTLS1_PROCESS_RECORD, SSL_R_BAD_DECOMPRESSION);
              return 0;
          }
      }
  
      if (rr->length > SSL3_RT_MAX_PLAIN_LENGTH) {
          SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_F_DTLS1_PROCESS_RECORD,
                   SSL_R_DATA_LENGTH_TOO_LONG);
          return 0;
      }
  
      rr->off = 0;
      /*-
       * So at this point the following is true
       * ssl->s3->rrec.type   is the type of record
       * ssl->s3->rrec.length == number of bytes in record
       * ssl->s3->rrec.off    == offset to first valid byte
       * ssl->s3->rrec.data   == where to take bytes from, increment
       *                         after use :-).
       */
  
      /* we have pulled in a full packet so zero things */
      RECORD_LAYER_reset_packet_length(&s->rlayer);
  
      /* Mark receipt of record. */
      dtls1_record_bitmap_update(s, bitmap);
  
      return 1;
  }
  
  /*
   * Retrieve a buffered record that belongs to the current epoch, i.e. processed
   */
  #define dtls1_get_processed_record(s) \
                     dtls1_retrieve_buffered_record((s), \
                     &(DTLS_RECORD_LAYER_get_processed_rcds(&s->rlayer)))
  
  /*-
   * Call this to get a new input record.
   * It will return <= 0 if more data is needed, normally due to an error
   * or non-blocking IO.
   * When it finishes, one packet has been decoded and can be found in
   * ssl->s3->rrec.type    - is the type of record
   * ssl->s3->rrec.data,   - data
   * ssl->s3->rrec.length, - number of bytes
   */
  /* used only by dtls1_read_bytes */
  int dtls1_get_record(SSL *s)
  {
      int ssl_major, ssl_minor;
      int rret;
      size_t more, n;
      SSL3_RECORD *rr;
      unsigned char *p = NULL;
      unsigned short version;
      DTLS1_BITMAP *bitmap;
      unsigned int is_next_epoch;
  
      rr = RECORD_LAYER_get_rrec(&s->rlayer);
  
   again:
      /*
       * The epoch may have changed.  If so, process all the pending records.
       * This is a non-blocking operation.
       */
      if (!dtls1_process_buffered_records(s)) {
          /* SSLfatal() already called */
          return -1;
      }
  
      /* if we're renegotiating, then there may be buffered records */
      if (dtls1_get_processed_record(s))
          return 1;
  
      /* get something from the wire */
  
      /* check if we have the header */
      if ((RECORD_LAYER_get_rstate(&s->rlayer) != SSL_ST_READ_BODY) ||
          (RECORD_LAYER_get_packet_length(&s->rlayer) < DTLS1_RT_HEADER_LENGTH)) {
          rret = ssl3_read_n(s, DTLS1_RT_HEADER_LENGTH,
                             SSL3_BUFFER_get_len(&s->rlayer.rbuf), 0, 1, &n);
          /* read timeout is handled by dtls1_read_bytes */
          if (rret <= 0) {
              /* SSLfatal() already called if appropriate */
              return rret;         /* error or non-blocking */
          }
  
          /* this packet contained a partial record, dump it */
          if (RECORD_LAYER_get_packet_length(&s->rlayer) !=
              DTLS1_RT_HEADER_LENGTH) {
              RECORD_LAYER_reset_packet_length(&s->rlayer);
              goto again;
          }
  
          RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_BODY);
  
          p = RECORD_LAYER_get_packet(&s->rlayer);
  
          if (s->msg_callback)
              s->msg_callback(0, 0, SSL3_RT_HEADER, p, DTLS1_RT_HEADER_LENGTH,
                              s, s->msg_callback_arg);
  
          /* Pull apart the header into the DTLS1_RECORD */
          rr->type = *(p++);
          ssl_major = *(p++);
          ssl_minor = *(p++);
          version = (ssl_major << 8) | ssl_minor;
  
          /* sequence number is 64 bits, with top 2 bytes = epoch */
          n2s(p, rr->epoch);
  
          memcpy(&(RECORD_LAYER_get_read_sequence(&s->rlayer)[2]), p, 6);
          p += 6;
  
          n2s(p, rr->length);
  
          /*
           * Lets check the version. We tolerate alerts that don't have the exact
           * version number (e.g. because of protocol version errors)
           */
          if (!s->first_packet && rr->type != SSL3_RT_ALERT) {
              if (version != s->version) {
                  /* unexpected version, silently discard */
                  rr->length = 0;
                  RECORD_LAYER_reset_packet_length(&s->rlayer);
                  goto again;
              }
          }
  
          if ((version & 0xff00) != (s->version & 0xff00)) {
              /* wrong version, silently discard record */
              rr->length = 0;
              RECORD_LAYER_reset_packet_length(&s->rlayer);
              goto again;
          }
  
          if (rr->length > SSL3_RT_MAX_ENCRYPTED_LENGTH) {
              /* record too long, silently discard it */
              rr->length = 0;
              RECORD_LAYER_reset_packet_length(&s->rlayer);
              goto again;
          }
  
          /* If received packet overflows own-client Max Fragment Length setting */
          if (s->session != NULL && USE_MAX_FRAGMENT_LENGTH_EXT(s->session)
                  && rr->length > GET_MAX_FRAGMENT_LENGTH(s->session)) {
              /* record too long, silently discard it */
              rr->length = 0;
              RECORD_LAYER_reset_packet_length(&s->rlayer);
              goto again;
          }
  
          /* now s->rlayer.rstate == SSL_ST_READ_BODY */
      }
  
      /* s->rlayer.rstate == SSL_ST_READ_BODY, get and decode the data */
  
      if (rr->length >
          RECORD_LAYER_get_packet_length(&s->rlayer) - DTLS1_RT_HEADER_LENGTH) {
          /* now s->packet_length == DTLS1_RT_HEADER_LENGTH */
          more = rr->length;
          rret = ssl3_read_n(s, more, more, 1, 1, &n);
          /* this packet contained a partial record, dump it */
          if (rret <= 0 || n != more) {
              if (ossl_statem_in_error(s)) {
                  /* ssl3_read_n() called SSLfatal() */
                  return -1;
              }
              rr->length = 0;
              RECORD_LAYER_reset_packet_length(&s->rlayer);
              goto again;
          }
  
          /*
           * now n == rr->length, and s->packet_length ==
           * DTLS1_RT_HEADER_LENGTH + rr->length
           */
      }
      /* set state for later operations */
      RECORD_LAYER_set_rstate(&s->rlayer, SSL_ST_READ_HEADER);
  
      /* match epochs.  NULL means the packet is dropped on the floor */
      bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch);
      if (bitmap == NULL) {
          rr->length = 0;
          RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */
          goto again;             /* get another record */
      }
  #ifndef OPENSSL_NO_SCTP
      /* Only do replay check if no SCTP bio */
      if (!BIO_dgram_is_sctp(SSL_get_rbio(s))) {
  #endif
          /* Check whether this is a repeat, or aged record. */
          /*
           * TODO: Does it make sense to have replay protection in epoch 0 where
           * we have no integrity negotiated yet?
           */
          if (!dtls1_record_replay_check(s, bitmap)) {
              rr->length = 0;
              RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */
              goto again;         /* get another record */
          }
  #ifndef OPENSSL_NO_SCTP
      }
  #endif
  
      /* just read a 0 length packet */
      if (rr->length == 0)
          goto again;
  
      /*
       * If this record is from the next epoch (either HM or ALERT), and a
       * handshake is currently in progress, buffer it since it cannot be
       * processed at this time.
       */
      if (is_next_epoch) {
          if ((SSL_in_init(s) || ossl_statem_get_in_handshake(s))) {
              if (dtls1_buffer_record (s,
                      &(DTLS_RECORD_LAYER_get_unprocessed_rcds(&s->rlayer)),
                      rr->seq_num) < 0) {
                  /* SSLfatal() already called */
                  return -1;
              }
          }
          rr->length = 0;
          RECORD_LAYER_reset_packet_length(&s->rlayer);
          goto again;
      }
  
      if (!dtls1_process_record(s, bitmap)) {
          if (ossl_statem_in_error(s)) {
              /* dtls1_process_record() called SSLfatal */
              return -1;
          }
          rr->length = 0;
          RECORD_LAYER_reset_packet_length(&s->rlayer); /* dump this record */
          goto again;             /* get another record */
      }
  
      return 1;
  
  }
  