text: /*
   * Copyright 2005-2019 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 <errno.h>
  #include <openssl/buffer.h>
  #include <openssl/evp.h>
  #include <stdio.h>
  
  #include "../packet_locl.h"
  #include "../ssl_locl.h"
  #include "internal/cryptlib.h"
  #include "record_locl.h"
  
  int DTLS_RECORD_LAYER_new(RECORD_LAYER* rl)
  {
      DTLS_RECORD_LAYER* d;
  
      if ((d = OPENSSL_malloc(sizeof(*d))) == NULL)
      {
          SSLerr(SSL_F_DTLS_RECORD_LAYER_NEW, ERR_R_MALLOC_FAILURE);
          return 0;
      }
  
      rl->d = d;
  
      d->unprocessed_rcds.q = pqueue_new();
      d->processed_rcds.q = pqueue_new();
      d->buffered_app_data.q = pqueue_new();
  
      if (d->unprocessed_rcds.q == NULL || d->processed_rcds.q == NULL ||
          d->buffered_app_data.q == NULL)
      {
          pqueue_free(d->unprocessed_rcds.q);
          pqueue_free(d->processed_rcds.q);
          pqueue_free(d->buffered_app_data.q);
          OPENSSL_free(d);
          rl->d = NULL;
          return 0;
      }
  
      return 1;
  }
  
  void DTLS_RECORD_LAYER_free(RECORD_LAYER* rl)
  {
      DTLS_RECORD_LAYER_clear(rl);
      pqueue_free(rl->d->unprocessed_rcds.q);
      pqueue_free(rl->d->processed_rcds.q);
      pqueue_free(rl->d->buffered_app_data.q);
      OPENSSL_free(rl->d);
      rl->d = NULL;
  }
  
  void DTLS_RECORD_LAYER_clear(RECORD_LAYER* rl)
  {
      DTLS_RECORD_LAYER* d;
      pitem* item = NULL;
      DTLS1_RECORD_DATA* rdata;
      pqueue* unprocessed_rcds;
      pqueue* processed_rcds;
      pqueue* buffered_app_data;
  
      d = rl->d;
  
      while ((item = pqueue_pop(d->unprocessed_rcds.q)) != NULL)
      {
          rdata = (DTLS1_RECORD_DATA*)item->data;
          OPENSSL_free(rdata->rbuf.buf);
          OPENSSL_free(item->data);
          pitem_free(item);
      }
  
      while ((item = pqueue_pop(d->processed_rcds.q)) != NULL)
      {
          rdata = (DTLS1_RECORD_DATA*)item->data;
          OPENSSL_free(rdata->rbuf.buf);
          OPENSSL_free(item->data);
          pitem_free(item);
      }
  
      while ((item = pqueue_pop(d->buffered_app_data.q)) != NULL)
      {
          rdata = (DTLS1_RECORD_DATA*)item->data;
          OPENSSL_free(rdata->rbuf.buf);
          OPENSSL_free(item->data);
          pitem_free(item);
      }
  
      unprocessed_rcds = d->unprocessed_rcds.q;
      processed_rcds = d->processed_rcds.q;
      buffered_app_data = d->buffered_app_data.q;
      memset(d, 0, sizeof(*d));
      d->unprocessed_rcds.q = unprocessed_rcds;
      d->processed_rcds.q = processed_rcds;
      d->buffered_app_data.q = buffered_app_data;
  }
  
  void DTLS_RECORD_LAYER_set_saved_w_epoch(RECORD_LAYER* rl, unsigned short e)
  {
      if (e == rl->d->w_epoch - 1)
      {
          memcpy(rl->d->curr_write_sequence, rl->write_sequence,
                 sizeof(rl->write_sequence));
          memcpy(rl->write_sequence, rl->d->last_write_sequence,
                 sizeof(rl->write_sequence));
      }
      else if (e == rl->d->w_epoch + 1)
      {
          memcpy(rl->d->last_write_sequence, rl->write_sequence,
                 sizeof(unsigned char[8]));
          memcpy(rl->write_sequence, rl->d->curr_write_sequence,
                 sizeof(rl->write_sequence));
      }
      rl->d->w_epoch = e;
  }
  
  void DTLS_RECORD_LAYER_set_write_sequence(RECORD_LAYER* rl, unsigned char* seq)
  {
      memcpy(rl->write_sequence, seq, SEQ_NUM_SIZE);
  }
  
  /* copy buffered record into SSL structure */
  static int dtls1_copy_record(SSL* s, pitem* item)
  {
      DTLS1_RECORD_DATA* rdata;
  
      rdata = (DTLS1_RECORD_DATA*)item->data;
  
      SSL3_BUFFER_release(&s->rlayer.rbuf);
  
      s->rlayer.packet = rdata->packet;
      s->rlayer.packet_length = rdata->packet_length;
      memcpy(&s->rlayer.rbuf, &(rdata->rbuf), sizeof(SSL3_BUFFER));
      memcpy(&s->rlayer.rrec, &(rdata->rrec), sizeof(SSL3_RECORD));
  
      /* Set proper sequence number for mac calculation */
      memcpy(&(s->rlayer.read_sequence[2]), &(rdata->packet[5]), 6);
  
      return 1;
  }
  
  int dtls1_buffer_record(SSL* s, record_pqueue* queue, unsigned char* priority)
  {
      DTLS1_RECORD_DATA* rdata;
      pitem* item;
  
      /* Limit the size of the queue to prevent DOS attacks */
      if (pqueue_size(queue->q) >= 100)
          return 0;
  
      rdata = OPENSSL_malloc(sizeof(*rdata));
      item = pitem_new(priority, rdata);
      if (rdata == NULL || item == NULL)
      {
          OPENSSL_free(rdata);
          pitem_free(item);
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_BUFFER_RECORD,
                   ERR_R_INTERNAL_ERROR);
          return -1;
      }
  
      rdata->packet = s->rlayer.packet;
      rdata->packet_length = s->rlayer.packet_length;
      memcpy(&(rdata->rbuf), &s->rlayer.rbuf, sizeof(SSL3_BUFFER));
      memcpy(&(rdata->rrec), &s->rlayer.rrec, sizeof(SSL3_RECORD));
  
      item->data = rdata;
  
  #ifndef OPENSSL_NO_SCTP
      /* Store bio_dgram_sctp_rcvinfo struct */
      if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
          (SSL_get_state(s) == TLS_ST_SR_FINISHED ||
           SSL_get_state(s) == TLS_ST_CR_FINISHED))
      {
          BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_GET_RCVINFO,
                   sizeof(rdata->recordinfo), &rdata->recordinfo);
      }
  #endif
  
      s->rlayer.packet = NULL;
      s->rlayer.packet_length = 0;
      memset(&s->rlayer.rbuf, 0, sizeof(s->rlayer.rbuf));
      memset(&s->rlayer.rrec, 0, sizeof(s->rlayer.rrec));
  
      if (!ssl3_setup_buffers(s))
      {
          /* SSLfatal() already called */
          OPENSSL_free(rdata->rbuf.buf);
          OPENSSL_free(rdata);
          pitem_free(item);
          return -1;
      }
  
      if (pqueue_insert(queue->q, item) == NULL)
      {
          /* Must be a duplicate so ignore it */
          OPENSSL_free(rdata->rbuf.buf);
          OPENSSL_free(rdata);
          pitem_free(item);
      }
  
      return 1;
  }
  
  int dtls1_retrieve_buffered_record(SSL* s, record_pqueue* queue)
  {
      pitem* item;
  
      item = pqueue_pop(queue->q);
      if (item)
      {
          dtls1_copy_record(s, item);
  
          OPENSSL_free(item->data);
          pitem_free(item);
  
          return 1;
      }
  
      return 0;
  }
  
  /*
   * retrieve a buffered record that belongs to the new epoch, i.e., not
   * processed yet
   */
  #define dtls1_get_unprocessed_record(s)                                        \
      dtls1_retrieve_buffered_record((s), &((s)->rlayer.d->unprocessed_rcds))
  
  int dtls1_process_buffered_records(SSL* s)
  {
      pitem* item;
      SSL3_BUFFER* rb;
      SSL3_RECORD* rr;
      DTLS1_BITMAP* bitmap;
      unsigned int is_next_epoch;
      int replayok = 1;
  
      item = pqueue_peek(s->rlayer.d->unprocessed_rcds.q);
      if (item)
      {
          /* Check if epoch is current. */
          if (s->rlayer.d->unprocessed_rcds.epoch != s->rlayer.d->r_epoch)
              return 1; /* Nothing to do. */
  
          rr = RECORD_LAYER_get_rrec(&s->rlayer);
  
          rb = RECORD_LAYER_get_rbuf(&s->rlayer);
  
          if (SSL3_BUFFER_get_left(rb) > 0)
          {
              /*
               * We've still got data from the current packet to read. There could
               * be a record from the new epoch in it - so don't overwrite it
               * with the unprocessed records yet (we'll do it when we've
               * finished reading the current packet).
               */
              return 1;
          }
  
          /* Process all the records. */
          while (pqueue_peek(s->rlayer.d->unprocessed_rcds.q))
          {
              dtls1_get_unprocessed_record(s);
              bitmap = dtls1_get_bitmap(s, rr, &is_next_epoch);
              if (bitmap == NULL)
              {
                  /*
                   * Should not happen. This will only ever be NULL when the
                   * current record is from a different epoch. But that cannot
                   * be the case because we already checked the epoch above
                   */
                  SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                           SSL_F_DTLS1_PROCESS_BUFFERED_RECORDS,
                           ERR_R_INTERNAL_ERROR);
                  return 0;
              }
  #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. We did this
                   * check once already when we first received the record - but
                   * we might have updated the window since then due to
                   * records we subsequently processed.
                   */
                  replayok = dtls1_record_replay_check(s, bitmap);
              }
  
              if (!replayok || !dtls1_process_record(s, bitmap))
              {
                  if (ossl_statem_in_error(s))
                  {
                      /* dtls1_process_record called SSLfatal() */
                      return -1;
                  }
                  /* dump this record */
                  rr->length = 0;
                  RECORD_LAYER_reset_packet_length(&s->rlayer);
                  continue;
              }
  
              if (dtls1_buffer_record(s, &(s->rlayer.d->processed_rcds),
                                      SSL3_RECORD_get_seq_num(s->rlayer.rrec)) <
                  0)
              {
                  /* SSLfatal() already called */
                  return 0;
              }
          }
      }
  
      /*
       * sync epoch numbers once all the unprocessed records have been
       * processed
       */
      s->rlayer.d->processed_rcds.epoch = s->rlayer.d->r_epoch;
      s->rlayer.d->unprocessed_rcds.epoch = s->rlayer.d->r_epoch + 1;
  
      return 1;
  }
  
  /*-
   * Return up to 'len' payload bytes received in 'type' records.
   * 'type' is one of the following:
   *
   *   -  SSL3_RT_HANDSHAKE (when ssl3_get_message calls us)
   *   -  SSL3_RT_APPLICATION_DATA (when ssl3_read calls us)
   *   -  0 (during a shutdown, no data has to be returned)
   *
   * If we don't have stored data to work from, read a SSL/TLS record first
   * (possibly multiple records if we still don't have anything to return).
   *
   * This function must handle any surprises the peer may have for us, such as
   * Alert records (e.g. close_notify) or renegotiation requests. ChangeCipherSpec
   * messages are treated as if they were handshake messages *if* the |recd_type|
   * argument is non NULL.
   * Also if record payloads contain fragments too small to process, we store
   * them until there is enough for the respective protocol (the record protocol
   * may use arbitrary fragmentation and even interleaving):
   *     Change cipher spec protocol
   *             just 1 byte needed, no need for keeping anything stored
   *     Alert protocol
   *             2 bytes needed (AlertLevel, AlertDescription)
   *     Handshake protocol
   *             4 bytes needed (HandshakeType, uint24 length) -- we just have
   *             to detect unexpected Client Hello and Hello Request messages
   *             here, anything else is handled by higher layers
   *     Application data protocol
   *             none of our business
   */
  int dtls1_read_bytes(SSL* s, int type, int* recvd_type, unsigned char* buf,
                       size_t len, int peek, size_t* readbytes)
  {
      int i, j, iret;
      size_t n;
      SSL3_RECORD* rr;
      void (*cb)(const SSL* ssl, int type2, int val) = NULL;
  
      if (!SSL3_BUFFER_is_initialised(&s->rlayer.rbuf))
      {
          /* Not initialized yet */
          if (!ssl3_setup_buffers(s))
          {
              /* SSLfatal() already called */
              return -1;
          }
      }
  
      if ((type && (type != SSL3_RT_APPLICATION_DATA) &&
           (type != SSL3_RT_HANDSHAKE)) ||
          (peek && (type != SSL3_RT_APPLICATION_DATA)))
      {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_READ_BYTES,
                   ERR_R_INTERNAL_ERROR);
          return -1;
      }
  
      if (!ossl_statem_get_in_handshake(s) && SSL_in_init(s))
      {
          /* type == SSL3_RT_APPLICATION_DATA */
          i = s->handshake_func(s);
          /* SSLfatal() already called if appropriate */
          if (i < 0)
              return i;
          if (i == 0)
              return -1;
      }
  
  start:
      s->rwstate = SSL_NOTHING;
  
      /*-
       * s->s3->rrec.type         - is the type of record
       * s->s3->rrec.data,    - data
       * s->s3->rrec.off,     - offset into 'data' for next read
       * s->s3->rrec.length,  - number of bytes.
       */
      rr = s->rlayer.rrec;
  
      /*
       * We are not handshaking and have no data yet, so process data buffered
       * during the last handshake in advance, if any.
       */
      if (SSL_is_init_finished(s) && SSL3_RECORD_get_length(rr) == 0)
      {
          pitem* item;
          item = pqueue_pop(s->rlayer.d->buffered_app_data.q);
          if (item)
          {
  #ifndef OPENSSL_NO_SCTP
              /* Restore bio_dgram_sctp_rcvinfo struct */
              if (BIO_dgram_is_sctp(SSL_get_rbio(s)))
              {
                  DTLS1_RECORD_DATA* rdata = (DTLS1_RECORD_DATA*)item->data;
                  BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SCTP_SET_RCVINFO,
                           sizeof(rdata->recordinfo), &rdata->recordinfo);
              }
  #endif
  
              dtls1_copy_record(s, item);
  
              OPENSSL_free(item->data);
              pitem_free(item);
          }
      }
  
      /* Check for timeout */
      if (dtls1_handle_timeout(s) > 0)
      {
          goto start;
      }
      else if (ossl_statem_in_error(s))
      {
          /* dtls1_handle_timeout() has failed with a fatal error */
          return -1;
      }
  
      /* get new packet if necessary */
      if ((SSL3_RECORD_get_length(rr) == 0) ||
          (s->rlayer.rstate == SSL_ST_READ_BODY))
      {
          RECORD_LAYER_set_numrpipes(&s->rlayer, 0);
          iret = dtls1_get_record(s);
          if (iret <= 0)
          {
              iret = dtls1_read_failed(s, iret);
              /*
               * Anything other than a timeout is an error. SSLfatal() already
               * called if appropriate.
               */
              if (iret <= 0)
                  return iret;
              else
                  goto start;
          }
          RECORD_LAYER_set_numrpipes(&s->rlayer, 1);
      }
  
      /*
       * Reset the count of consecutive warning alerts if we've got a non-empty
       * record that isn't an alert.
       */
      if (SSL3_RECORD_get_type(rr) != SSL3_RT_ALERT &&
          SSL3_RECORD_get_length(rr) != 0)
          s->rlayer.alert_count = 0;
  
      /* we now have a packet which can be read and processed */
  
      if (s->s3->change_cipher_spec /* set when we receive ChangeCipherSpec,
                                     * reset by ssl3_get_finished */
          && (SSL3_RECORD_get_type(rr) != SSL3_RT_HANDSHAKE))
      {
          /*
           * We now have application data between CCS and Finished. Most likely
           * the packets were reordered on their way, so buffer the application
           * data for later processing rather than dropping the connection.
           */
          if (dtls1_buffer_record(s, &(s->rlayer.d->buffered_app_data),
                                  SSL3_RECORD_get_seq_num(rr)) < 0)
          {
              /* SSLfatal() already called */
              return -1;
          }
          SSL3_RECORD_set_length(rr, 0);
          SSL3_RECORD_set_read(rr);
          goto start;
      }
  
      /*
       * If the other end has shut down, throw anything we read away (even in
       * 'peek' mode)
       */
      if (s->shutdown & SSL_RECEIVED_SHUTDOWN)
      {
          SSL3_RECORD_set_length(rr, 0);
          SSL3_RECORD_set_read(rr);
          s->rwstate = SSL_NOTHING;
          return 0;
      }
  
      if (type == SSL3_RECORD_get_type(rr) ||
          (SSL3_RECORD_get_type(rr) == SSL3_RT_CHANGE_CIPHER_SPEC &&
           type == SSL3_RT_HANDSHAKE && recvd_type != NULL))
      {
          /*
           * SSL3_RT_APPLICATION_DATA or
           * SSL3_RT_HANDSHAKE or
           * SSL3_RT_CHANGE_CIPHER_SPEC
           */
          /*
           * make sure that we are not getting application data when we are
           * doing a handshake for the first time
           */
          if (SSL_in_init(s) && (type == SSL3_RT_APPLICATION_DATA) &&
              (s->enc_read_ctx == NULL))
          {
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                       SSL_R_APP_DATA_IN_HANDSHAKE);
              return -1;
          }
  
          if (recvd_type != NULL)
              *recvd_type = SSL3_RECORD_get_type(rr);
  
          if (len == 0)
          {
              /*
               * Mark a zero length record as read. This ensures multiple calls to
               * SSL_read() with a zero length buffer will eventually cause
               * SSL_pending() to report data as being available.
               */
              if (SSL3_RECORD_get_length(rr) == 0)
                  SSL3_RECORD_set_read(rr);
              return 0;
          }
  
          if (len > SSL3_RECORD_get_length(rr))
              n = SSL3_RECORD_get_length(rr);
          else
              n = len;
  
          memcpy(buf, &(SSL3_RECORD_get_data(rr)[SSL3_RECORD_get_off(rr)]), n);
          if (peek)
          {
              if (SSL3_RECORD_get_length(rr) == 0)
                  SSL3_RECORD_set_read(rr);
          }
          else
          {
              SSL3_RECORD_sub_length(rr, n);
              SSL3_RECORD_add_off(rr, n);
              if (SSL3_RECORD_get_length(rr) == 0)
              {
                  s->rlayer.rstate = SSL_ST_READ_HEADER;
                  SSL3_RECORD_set_off(rr, 0);
                  SSL3_RECORD_set_read(rr);
              }
          }
  #ifndef OPENSSL_NO_SCTP
          /*
           * We might had to delay a close_notify alert because of reordered
           * app data. If there was an alert and there is no message to read
           * anymore, finally set shutdown.
           */
          if (BIO_dgram_is_sctp(SSL_get_rbio(s)) && s->d1->shutdown_received &&
              !BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s)))
          {
              s->shutdown |= SSL_RECEIVED_SHUTDOWN;
              return 0;
          }
  #endif
          *readbytes = n;
          return 1;
      }
  
      /*
       * If we get here, then type != rr->type; if we have a handshake message,
       * then it was unexpected (Hello Request or Client Hello).
       */
  
      if (SSL3_RECORD_get_type(rr) == SSL3_RT_ALERT)
      {
          unsigned int alert_level, alert_descr;
          unsigned char* alert_bytes =
              SSL3_RECORD_get_data(rr) + SSL3_RECORD_get_off(rr);
          PACKET alert;
  
          if (!PACKET_buf_init(&alert, alert_bytes, SSL3_RECORD_get_length(rr)) ||
              !PACKET_get_1(&alert, &alert_level) ||
              !PACKET_get_1(&alert, &alert_descr) ||
              PACKET_remaining(&alert) != 0)
          {
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                       SSL_R_INVALID_ALERT);
              return -1;
          }
  
          if (s->msg_callback)
              s->msg_callback(0, s->version, SSL3_RT_ALERT, alert_bytes, 2, s,
                              s->msg_callback_arg);
  
          if (s->info_callback != NULL)
              cb = s->info_callback;
          else if (s->ctx->info_callback != NULL)
              cb = s->ctx->info_callback;
  
          if (cb != NULL)
          {
              j = (alert_level << 8) | alert_descr;
              cb(s, SSL_CB_READ_ALERT, j);
          }
  
          if (alert_level == SSL3_AL_WARNING)
          {
              s->s3->warn_alert = alert_descr;
              SSL3_RECORD_set_read(rr);
  
              s->rlayer.alert_count++;
              if (s->rlayer.alert_count == MAX_WARN_ALERT_COUNT)
              {
                  SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                           SSL_R_TOO_MANY_WARN_ALERTS);
                  return -1;
              }
  
              if (alert_descr == SSL_AD_CLOSE_NOTIFY)
              {
  #ifndef OPENSSL_NO_SCTP
                  /*
                   * With SCTP and streams the socket may deliver app data
                   * after a close_notify alert. We have to check this first so
                   * that nothing gets discarded.
                   */
                  if (BIO_dgram_is_sctp(SSL_get_rbio(s)) &&
                      BIO_dgram_sctp_msg_waiting(SSL_get_rbio(s)))
                  {
                      s->d1->shutdown_received = 1;
                      s->rwstate = SSL_READING;
                      BIO_clear_retry_flags(SSL_get_rbio(s));
                      BIO_set_retry_read(SSL_get_rbio(s));
                      return -1;
                  }
  #endif
                  s->shutdown |= SSL_RECEIVED_SHUTDOWN;
                  return 0;
              }
          }
          else if (alert_level == SSL3_AL_FATAL)
          {
              char tmp[16];
  
              s->rwstate = SSL_NOTHING;
              s->s3->fatal_alert = alert_descr;
              SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_DTLS1_READ_BYTES,
                       SSL_AD_REASON_OFFSET + alert_descr);
              BIO_snprintf(tmp, sizeof tmp, "%d", alert_descr);
              ERR_add_error_data(2, "SSL alert number ", tmp);
              s->shutdown |= SSL_RECEIVED_SHUTDOWN;
              SSL3_RECORD_set_read(rr);
              SSL_CTX_remove_session(s->session_ctx, s->session);
              return 0;
          }
          else
          {
              SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_DTLS1_READ_BYTES,
                       SSL_R_UNKNOWN_ALERT_TYPE);
              return -1;
          }
  
          goto start;
      }
  
      if (s->shutdown & SSL_SENT_SHUTDOWN)
      { /* but we have not received a
         * shutdown */
          s->rwstate = SSL_NOTHING;
          SSL3_RECORD_set_length(rr, 0);
          SSL3_RECORD_set_read(rr);
          return 0;
      }
  
      if (SSL3_RECORD_get_type(rr) == SSL3_RT_CHANGE_CIPHER_SPEC)
      {
          /*
           * We can't process a CCS now, because previous handshake messages
           * are still missing, so just drop it.
           */
          SSL3_RECORD_set_length(rr, 0);
          SSL3_RECORD_set_read(rr);
          goto start;
      }
  
      /*
       * Unexpected handshake message (Client Hello, or protocol violation)
       */
      if ((SSL3_RECORD_get_type(rr) == SSL3_RT_HANDSHAKE) &&
          !ossl_statem_get_in_handshake(s))
      {
          struct hm_header_st msg_hdr;
  
          /*
           * This may just be a stale retransmit. Also sanity check that we have
           * at least enough record bytes for a message header
           */
          if (SSL3_RECORD_get_epoch(rr) != s->rlayer.d->r_epoch ||
              SSL3_RECORD_get_length(rr) < DTLS1_HM_HEADER_LENGTH)
          {
              SSL3_RECORD_set_length(rr, 0);
              SSL3_RECORD_set_read(rr);
              goto start;
          }
  
          dtls1_get_message_header(rr->data, &msg_hdr);
  
          /*
           * If we are server, we may have a repeated FINISHED of the client
           * here, then retransmit our CCS and FINISHED.
           */
          if (msg_hdr.type == SSL3_MT_FINISHED)
          {
              if (dtls1_check_timeout_num(s) < 0)
              {
                  /* SSLfatal) already called */
                  return -1;
              }
  
              if (dtls1_retransmit_buffered_messages(s) <= 0)
              {
                  /* Fail if we encountered a fatal error */
                  if (ossl_statem_in_error(s))
                      return -1;
              }
              SSL3_RECORD_set_length(rr, 0);
              SSL3_RECORD_set_read(rr);
              if (!(s->mode & SSL_MODE_AUTO_RETRY))
              {
                  if (SSL3_BUFFER_get_left(&s->rlayer.rbuf) == 0)
                  {
                      /* no read-ahead left? */
                      BIO* bio;
  
                      s->rwstate = SSL_READING;
                      bio = SSL_get_rbio(s);
                      BIO_clear_retry_flags(bio);
                      BIO_set_retry_read(bio);
                      return -1;
                  }
              }
              goto start;
          }
  
          /*
           * To get here we must be trying to read app data but found handshake
           * data. But if we're trying to read app data, and we're not in init
           * (which is tested for at the top of this function) then init must be
           * finished
           */
          if (!ossl_assert(SSL_is_init_finished(s)))
          {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_READ_BYTES,
                       ERR_R_INTERNAL_ERROR);
              return -1;
          }
  
          /* We found handshake data, so we're going back into init */
          ossl_statem_set_in_init(s, 1);
  
          i = s->handshake_func(s);
          /* SSLfatal() called if appropriate */
          if (i < 0)
              return i;
          if (i == 0)
              return -1;
  
          if (!(s->mode & SSL_MODE_AUTO_RETRY))
          {
              if (SSL3_BUFFER_get_left(&s->rlayer.rbuf) == 0)
              {
                  /* no read-ahead left? */
                  BIO* bio;
                  /*
                   * In the case where we try to read application data, but we
                   * trigger an SSL handshake, we return -1 with the retry
                   * option set.  Otherwise renegotiation may cause nasty
                   * problems in the blocking world
                   */
                  s->rwstate = SSL_READING;
                  bio = SSL_get_rbio(s);
                  BIO_clear_retry_flags(bio);
                  BIO_set_retry_read(bio);
                  return -1;
              }
          }
          goto start;
      }
  
      switch (SSL3_RECORD_get_type(rr))
      {
          default:
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                       SSL_R_UNEXPECTED_RECORD);
              return -1;
          case SSL3_RT_CHANGE_CIPHER_SPEC:
          case SSL3_RT_ALERT:
          case SSL3_RT_HANDSHAKE:
              /*
               * we already handled all of these, with the possible exception of
               * SSL3_RT_HANDSHAKE when ossl_statem_get_in_handshake(s) is true,
               * but that should not happen when type != rr->type
               */
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                       ERR_R_INTERNAL_ERROR);
              return -1;
          case SSL3_RT_APPLICATION_DATA:
              /*
               * At this point, we were expecting handshake data, but have
               * application data.  If the library was running inside ssl3_read()
               * (i.e. in_read_app_data is set) and it makes sense to read
               * application data at this point (session renegotiation not yet
               * started), we will indulge it.
               */
              if (s->s3->in_read_app_data && (s->s3->total_renegotiations != 0) &&
                  ossl_statem_app_data_allowed(s))
              {
                  s->s3->in_read_app_data = 2;
                  return -1;
              }
              else
              {
                  SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE, SSL_F_DTLS1_READ_BYTES,
                           SSL_R_UNEXPECTED_RECORD);
                  return -1;
              }
      }
      /* not reached */
  }
  
  /*
   * Call this to write data in records of type 'type' It will return <= 0 if
   * not all data has been sent or non-blocking IO.
   */
  int dtls1_write_bytes(SSL* s, int type, const void* buf, size_t len,
                        size_t* written)
  {
      int i;
  
      if (!ossl_assert(len <= SSL3_RT_MAX_PLAIN_LENGTH))
      {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_WRITE_BYTES,
                   ERR_R_INTERNAL_ERROR);
          return -1;
      }
      s->rwstate = SSL_NOTHING;
      i = do_dtls1_write(s, type, buf, len, 0, written);
      return i;
  }
  
  int do_dtls1_write(SSL* s, int type, const unsigned char* buf, size_t len,
                     int create_empty_fragment, size_t* written)
  {
      unsigned char *p, *pseq;
      int i, mac_size, clear = 0;
      size_t prefix_len = 0;
      int eivlen;
      SSL3_RECORD wr;
      SSL3_BUFFER* wb;
      SSL_SESSION* sess;
  
      wb = &s->rlayer.wbuf[0];
  
      /*
       * first check if there is a SSL3_BUFFER still being written out.  This
       * will happen with non blocking IO
       */
      if (!ossl_assert(SSL3_BUFFER_get_left(wb) == 0))
      {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DO_DTLS1_WRITE,
                   ERR_R_INTERNAL_ERROR);
          return 0;
      }
  
      /* If we have an alert to send, lets send it */
      if (s->s3->alert_dispatch)
      {
          i = s->method->ssl_dispatch_alert(s);
          if (i <= 0)
              return i;
          /* if it went, fall through and send more stuff */
      }
  
      if (len == 0 && !create_empty_fragment)
          return 0;
  
      if (len > ssl_get_max_send_fragment(s))
      {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DO_DTLS1_WRITE,
                   SSL_R_EXCEEDS_MAX_FRAGMENT_SIZE);
          return 0;
      }
  
      sess = s->session;
  
      if ((sess == NULL) || (s->enc_write_ctx == NULL) ||
          (EVP_MD_CTX_md(s->write_hash) == NULL))
          clear = 1;
  
      if (clear)
          mac_size = 0;
      else
      {
          mac_size = EVP_MD_CTX_size(s->write_hash);
          if (mac_size < 0)
          {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DO_DTLS1_WRITE,
                       SSL_R_EXCEEDS_MAX_FRAGMENT_SIZE);
              return -1;
          }
      }
  
      p = SSL3_BUFFER_get_buf(wb) + prefix_len;
  
      /* write the header */
  
      *(p++) = type & 0xff;
      SSL3_RECORD_set_type(&wr, type);
      /*
       * Special case: for hello verify request, client version 1.0 and we
       * haven't decided which version to use yet send back using version 1.0
       * header: otherwise some clients will ignore it.
       */
      if (s->method->version == DTLS_ANY_VERSION &&
          s->max_proto_version != DTLS1_BAD_VER)
      {
          *(p++) = DTLS1_VERSION >> 8;
          *(p++) = DTLS1_VERSION & 0xff;
      }
      else
      {
          *(p++) = s->version >> 8;
          *(p++) = s->version & 0xff;
      }
  
      /* field where we are to write out packet epoch, seq num and len */
      pseq = p;
      p += 10;
  
      /* Explicit IV length, block ciphers appropriate version flag */
      if (s->enc_write_ctx)
      {
          int mode = EVP_CIPHER_CTX_mode(s->enc_write_ctx);
          if (mode == EVP_CIPH_CBC_MODE)
          {
              eivlen = EVP_CIPHER_CTX_iv_length(s->enc_write_ctx);
              if (eivlen <= 1)
                  eivlen = 0;
          }
          /* Need explicit part of IV for GCM mode */
          else if (mode == EVP_CIPH_GCM_MODE)
              eivlen = EVP_GCM_TLS_EXPLICIT_IV_LEN;
          else if (mode == EVP_CIPH_CCM_MODE)
              eivlen = EVP_CCM_TLS_EXPLICIT_IV_LEN;
          else
              eivlen = 0;
      }
      else
          eivlen = 0;
  
      /* lets setup the record stuff. */
      SSL3_RECORD_set_data(&wr, p + eivlen); /* make room for IV in case of CBC */
      SSL3_RECORD_set_length(&wr, len);
      SSL3_RECORD_set_input(&wr, (unsigned char*)buf);
  
      /*
       * we now 'read' from wr.input, wr.length bytes into wr.data
       */
  
      /* first we compress */
      if (s->compress != NULL)
      {
          if (!ssl3_do_compress(s, &wr))
          {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DO_DTLS1_WRITE,
                       SSL_R_COMPRESSION_FAILURE);
              return -1;
          }
      }
      else
      {
          memcpy(SSL3_RECORD_get_data(&wr), SSL3_RECORD_get_input(&wr),
                 SSL3_RECORD_get_length(&wr));
          SSL3_RECORD_reset_input(&wr);
      }
  
      /*
       * we should still have the output to wr.data and the input from
       * wr.input.  Length should be wr.length. wr.data still points in the
       * wb->buf
       */
  
      if (!SSL_WRITE_ETM(s) && mac_size != 0)
      {
          if (!s->method->ssl3_enc->mac(
                  s, &wr, &(p[SSL3_RECORD_get_length(&wr) + eivlen]), 1))
          {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DO_DTLS1_WRITE,
                       ERR_R_INTERNAL_ERROR);
              return -1;
          }
          SSL3_RECORD_add_length(&wr, mac_size);
      }
  
      /* this is true regardless of mac size */
      SSL3_RECORD_set_data(&wr, p);
      SSL3_RECORD_reset_input(&wr);
  
      if (eivlen)
          SSL3_RECORD_add_length(&wr, eivlen);
  
      if (s->method->ssl3_enc->enc(s, &wr, 1, 1) < 1)
      {
          if (!ossl_statem_in_error(s))
          {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DO_DTLS1_WRITE,
                       ERR_R_INTERNAL_ERROR);
          }
          return -1;
      }
  
      if (SSL_WRITE_ETM(s) && mac_size != 0)
      {
          if (!s->method->ssl3_enc->mac(s, &wr, &(p[SSL3_RECORD_get_length(&wr)]),
                                        1))
          {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DO_DTLS1_WRITE,
                       ERR_R_INTERNAL_ERROR);
              return -1;
          }
          SSL3_RECORD_add_length(&wr, mac_size);
      }
  
      /* record length after mac and block padding */
  
      /* there's only one epoch between handshake and app data */
  
      s2n(s->rlayer.d->w_epoch, pseq);
  
      memcpy(pseq, &(s->rlayer.write_sequence[2]), 6);
      pseq += 6;
      s2n(SSL3_RECORD_get_length(&wr), pseq);
  
      if (s->msg_callback)
          s->msg_callback(1, 0, SSL3_RT_HEADER, pseq - DTLS1_RT_HEADER_LENGTH,
                          DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
  
      /*
       * we should now have wr.data pointing to the encrypted data, which is
       * wr->length long
       */
      SSL3_RECORD_set_type(&wr, type); /* not needed but helps for debugging */
      SSL3_RECORD_add_length(&wr, DTLS1_RT_HEADER_LENGTH);
  
      ssl3_record_sequence_update(&(s->rlayer.write_sequence[0]));
  
      if (create_empty_fragment)
      {
          /*
           * we are in a recursive call; just return the length, don't write
           * out anything here
           */
          *written = wr.length;
          return 1;
      }
  
      /* now let's set up wb */
      SSL3_BUFFER_set_left(wb, prefix_len + SSL3_RECORD_get_length(&wr));
      SSL3_BUFFER_set_offset(wb, 0);
  
      /*
       * memorize arguments so that ssl3_write_pending can detect bad write
       * retries later
       */
      s->rlayer.wpend_tot = len;
      s->rlayer.wpend_buf = buf;
      s->rlayer.wpend_type = type;
      s->rlayer.wpend_ret = len;
  
      /* we now just need to write the buffer. Calls SSLfatal() as required. */
      return ssl3_write_pending(s, type, buf, len, written);
  }
  
  DTLS1_BITMAP* dtls1_get_bitmap(SSL* s, SSL3_RECORD* rr,
                                 unsigned int* is_next_epoch)
  {
  
      *is_next_epoch = 0;
  
      /* In current epoch, accept HM, CCS, DATA, & ALERT */
      if (rr->epoch == s->rlayer.d->r_epoch)
          return &s->rlayer.d->bitmap;
  
      /*
       * Only HM and ALERT messages can be from the next epoch and only if we
       * have already processed all of the unprocessed records from the last
       * epoch
       */
      else if (rr->epoch == (unsigned long)(s->rlayer.d->r_epoch + 1) &&
               s->rlayer.d->unprocessed_rcds.epoch != s->rlayer.d->r_epoch &&
               (rr->type == SSL3_RT_HANDSHAKE || rr->type == SSL3_RT_ALERT))
      {
          *is_next_epoch = 1;
          return &s->rlayer.d->next_bitmap;
      }
  
      return NULL;
  }
  
  void dtls1_reset_seq_numbers(SSL* s, int rw)
  {
      unsigned char* seq;
      unsigned int seq_bytes = sizeof(s->rlayer.read_sequence);
  
      if (rw & SSL3_CC_READ)
      {
          seq = s->rlayer.read_sequence;
          s->rlayer.d->r_epoch++;
          memcpy(&s->rlayer.d->bitmap, &s->rlayer.d->next_bitmap,
                 sizeof(s->rlayer.d->bitmap));
          memset(&s->rlayer.d->next_bitmap, 0, sizeof(s->rlayer.d->next_bitmap));
  
          /*
           * We must not use any buffered messages received from the previous
           * epoch
           */
          dtls1_clear_received_buffer(s);
      }
      else
      {
          seq = s->rlayer.write_sequence;
          memcpy(s->rlayer.d->last_write_sequence, seq,
                 sizeof(s->rlayer.write_sequence));
          s->rlayer.d->w_epoch++;
      }
  
      memset(seq, 0, seq_bytes);
  }
  