text: /*
   * Copyright 2005-2016 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 <limits.h>
  #include <string.h>
  #include <stdio.h>
  #include "../ssl_locl.h"
  #include "statem_locl.h"
  #include "internal/cryptlib.h"
  #include <openssl/buffer.h>
  #include <openssl/objects.h>
  #include <openssl/evp.h>
  #include <openssl/x509.h>
  
  #define RSMBLY_BITMASK_SIZE(msg_len) (((msg_len) + 7) / 8)
  
  #define RSMBLY_BITMASK_MARK(bitmask, start, end) { \
                          if ((end) - (start) <= 8) { \
                                  long ii; \
                                  for (ii = (start); ii < (end); ii++) bitmask[((ii) >> 3)] |= (1 << ((ii) & 7)); \
                          } else { \
                                  long ii; \
                                  bitmask[((start) >> 3)] |= bitmask_start_values[((start) & 7)]; \
                                  for (ii = (((start) >> 3) + 1); ii < ((((end) - 1)) >> 3); ii++) bitmask[ii] = 0xff; \
                                  bitmask[(((end) - 1) >> 3)] |= bitmask_end_values[((end) & 7)]; \
                          } }
  
  #define RSMBLY_BITMASK_IS_COMPLETE(bitmask, msg_len, is_complete) { \
                          long ii; \
                          is_complete = 1; \
                          if (bitmask[(((msg_len) - 1) >> 3)] != bitmask_end_values[((msg_len) & 7)]) is_complete = 0; \
                          if (is_complete) for (ii = (((msg_len) - 1) >> 3) - 1; ii >= 0 ; ii--) \
                                  if (bitmask[ii] != 0xff) { is_complete = 0; break; } }
  
  static unsigned char bitmask_start_values[] =
      { 0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80 };
  static unsigned char bitmask_end_values[] =
      { 0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f };
  
  static void dtls1_fix_message_header(SSL *s, size_t frag_off,
                                       size_t frag_len);
  static unsigned char *dtls1_write_message_header(SSL *s, unsigned char *p);
  static void dtls1_set_message_header_int(SSL *s, unsigned char mt,
                                           size_t len,
                                           unsigned short seq_num,
                                           size_t frag_off,
                                           size_t frag_len);
  static int dtls_get_reassembled_message(SSL *s, int *errtype, size_t *len);
  
  static hm_fragment *dtls1_hm_fragment_new(size_t frag_len, int reassembly)
  {
      hm_fragment *frag = NULL;
      unsigned char *buf = NULL;
      unsigned char *bitmask = NULL;
  
      frag = OPENSSL_malloc(sizeof(*frag));
      if (frag == NULL)
          return NULL;
  
      if (frag_len) {
          buf = OPENSSL_malloc(frag_len);
          if (buf == NULL) {
              OPENSSL_free(frag);
              return NULL;
          }
      }
  
      /* zero length fragment gets zero frag->fragment */
      frag->fragment = buf;
  
      /* Initialize reassembly bitmask if necessary */
      if (reassembly) {
          bitmask = OPENSSL_zalloc(RSMBLY_BITMASK_SIZE(frag_len));
          if (bitmask == NULL) {
              OPENSSL_free(buf);
              OPENSSL_free(frag);
              return NULL;
          }
      }
  
      frag->reassembly = bitmask;
  
      return frag;
  }
  
  void dtls1_hm_fragment_free(hm_fragment *frag)
  {
      if (!frag)
          return;
      if (frag->msg_header.is_ccs) {
          EVP_CIPHER_CTX_free(frag->msg_header.
                              saved_retransmit_state.enc_write_ctx);
          EVP_MD_CTX_free(frag->msg_header.saved_retransmit_state.write_hash);
      }
      OPENSSL_free(frag->fragment);
      OPENSSL_free(frag->reassembly);
      OPENSSL_free(frag);
  }
  
  /*
   * send s->init_buf in records of type 'type' (SSL3_RT_HANDSHAKE or
   * SSL3_RT_CHANGE_CIPHER_SPEC)
   */
  int dtls1_do_write(SSL *s, int type)
  {
      int ret;
      size_t written;
      size_t curr_mtu;
      int retry = 1;
      size_t len, frag_off, mac_size, blocksize, used_len;
  
      if (!dtls1_query_mtu(s))
          return -1;
  
      if (s->d1->mtu < dtls1_min_mtu(s))
          /* should have something reasonable now */
          return -1;
  
      if (s->init_off == 0 && type == SSL3_RT_HANDSHAKE) {
          if (!ossl_assert(s->init_num ==
                           s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH))
              return -1;
      }
  
      if (s->write_hash) {
          if (s->enc_write_ctx
              && (EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(s->enc_write_ctx)) &
                  EVP_CIPH_FLAG_AEAD_CIPHER) != 0)
              mac_size = 0;
          else
              mac_size = EVP_MD_CTX_size(s->write_hash);
      } else
          mac_size = 0;
  
      if (s->enc_write_ctx &&
          (EVP_CIPHER_CTX_mode(s->enc_write_ctx) == EVP_CIPH_CBC_MODE))
          blocksize = 2 * EVP_CIPHER_CTX_block_size(s->enc_write_ctx);
      else
          blocksize = 0;
  
      frag_off = 0;
      s->rwstate = SSL_NOTHING;
  
      /* s->init_num shouldn't ever be < 0...but just in case */
      while (s->init_num > 0) {
          if (type == SSL3_RT_HANDSHAKE && s->init_off != 0) {
              /* We must be writing a fragment other than the first one */
  
              if (frag_off > 0) {
                  /* This is the first attempt at writing out this fragment */
  
                  if (s->init_off <= DTLS1_HM_HEADER_LENGTH) {
                      /*
                       * Each fragment that was already sent must at least have
                       * contained the message header plus one other byte.
                       * Therefore |init_off| must have progressed by at least
                       * |DTLS1_HM_HEADER_LENGTH + 1| bytes. If not something went
                       * wrong.
                       */
                      return -1;
                  }
  
                  /*
                   * Adjust |init_off| and |init_num| to allow room for a new
                   * message header for this fragment.
                   */
                  s->init_off -= DTLS1_HM_HEADER_LENGTH;
                  s->init_num += DTLS1_HM_HEADER_LENGTH;
              } else {
                  /*
                   * We must have been called again after a retry so use the
                   * fragment offset from our last attempt. We do not need
                   * to adjust |init_off| and |init_num| as above, because
                   * that should already have been done before the retry.
                   */
                  frag_off = s->d1->w_msg_hdr.frag_off;
              }
          }
  
          used_len = BIO_wpending(s->wbio) + DTLS1_RT_HEADER_LENGTH
              + mac_size + blocksize;
          if (s->d1->mtu > used_len)
              curr_mtu = s->d1->mtu - used_len;
          else
              curr_mtu = 0;
  
          if (curr_mtu <= DTLS1_HM_HEADER_LENGTH) {
              /*
               * grr.. we could get an error if MTU picked was wrong
               */
              ret = BIO_flush(s->wbio);
              if (ret <= 0) {
                  s->rwstate = SSL_WRITING;
                  return ret;
              }
              used_len = DTLS1_RT_HEADER_LENGTH + mac_size + blocksize;
              if (s->d1->mtu > used_len + DTLS1_HM_HEADER_LENGTH) {
                  curr_mtu = s->d1->mtu - used_len;
              } else {
                  /* Shouldn't happen */
                  return -1;
              }
          }
  
          /*
           * We just checked that s->init_num > 0 so this cast should be safe
           */
          if (((unsigned int)s->init_num) > curr_mtu)
              len = curr_mtu;
          else
              len = s->init_num;
  
          if (len > s->max_send_fragment)
              len = s->max_send_fragment;
  
          /*
           * XDTLS: this function is too long.  split out the CCS part
           */
          if (type == SSL3_RT_HANDSHAKE) {
              if (len < DTLS1_HM_HEADER_LENGTH) {
                  /*
                   * len is so small that we really can't do anything sensible
                   * so fail
                   */
                  return -1;
              }
              dtls1_fix_message_header(s, frag_off, len - DTLS1_HM_HEADER_LENGTH);
  
              dtls1_write_message_header(s,
                                         (unsigned char *)&s->init_buf->
                                         data[s->init_off]);
          }
  
          ret = dtls1_write_bytes(s, type, &s->init_buf->data[s->init_off], len,
                                  &written);
          if (ret < 0) {
              /*
               * might need to update MTU here, but we don't know which
               * previous packet caused the failure -- so can't really
               * retransmit anything.  continue as if everything is fine and
               * wait for an alert to handle the retransmit
               */
              if (retry && BIO_ctrl(SSL_get_wbio(s),
                                    BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0) {
                  if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
                      if (!dtls1_query_mtu(s))
                          return -1;
                      /* Have one more go */
                      retry = 0;
                  } else
                      return -1;
              } else {
                  return -1;
              }
          } else {
  
              /*
               * bad if this assert fails, only part of the handshake message
               * got sent.  but why would this happen?
               */
              if (!ossl_assert(len == written))
                  return -1;
  
              if (type == SSL3_RT_HANDSHAKE && !s->d1->retransmitting) {
                  /*
                   * should not be done for 'Hello Request's, but in that case
                   * we'll ignore the result anyway
                   */
                  unsigned char *p =
                      (unsigned char *)&s->init_buf->data[s->init_off];
                  const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
                  size_t xlen;
  
                  if (frag_off == 0 && s->version != DTLS1_BAD_VER) {
                      /*
                       * reconstruct message header is if it is being sent in
                       * single fragment
                       */
                      *p++ = msg_hdr->type;
                      l2n3(msg_hdr->msg_len, p);
                      s2n(msg_hdr->seq, p);
                      l2n3(0, p);
                      l2n3(msg_hdr->msg_len, p);
                      p -= DTLS1_HM_HEADER_LENGTH;
                      xlen = written;
                  } else {
                      p += DTLS1_HM_HEADER_LENGTH;
                      xlen = written - DTLS1_HM_HEADER_LENGTH;
                  }
  
                  if (!ssl3_finish_mac(s, p, xlen))
                      return -1;
              }
  
              if (written == s->init_num) {
                  if (s->msg_callback)
                      s->msg_callback(1, s->version, type, s->init_buf->data,
                                      (size_t)(s->init_off + s->init_num), s,
                                      s->msg_callback_arg);
  
                  s->init_off = 0; /* done writing this message */
                  s->init_num = 0;
  
                  return 1;
              }
              s->init_off += written;
              s->init_num -= written;
              written -= DTLS1_HM_HEADER_LENGTH;
              frag_off += written;
  
              /*
               * We save the fragment offset for the next fragment so we have it
               * available in case of an IO retry. We don't know the length of the
               * next fragment yet so just set that to 0 for now. It will be
               * updated again later.
               */
              dtls1_fix_message_header(s, frag_off, 0);
          }
      }
      return 0;
  }
  
  int dtls_get_message(SSL *s, int *mt, size_t *len)
  {
      struct hm_header_st *msg_hdr;
      unsigned char *p;
      size_t msg_len;
      size_t tmplen;
      int errtype;
  
      msg_hdr = &s->d1->r_msg_hdr;
      memset(msg_hdr, 0, sizeof(*msg_hdr));
  
   again:
      if (!dtls_get_reassembled_message(s, &errtype, &tmplen)) {
          if (errtype == DTLS1_HM_BAD_FRAGMENT
                  || errtype == DTLS1_HM_FRAGMENT_RETRY) {
              /* bad fragment received */
              goto again;
          }
          return 0;
      }
  
      *mt = s->s3->tmp.message_type;
  
      p = (unsigned char *)s->init_buf->data;
      *len = s->init_num;
  
      if (*mt == SSL3_MT_CHANGE_CIPHER_SPEC) {
          if (s->msg_callback) {
              s->msg_callback(0, s->version, SSL3_RT_CHANGE_CIPHER_SPEC,
                              p, 1, s, s->msg_callback_arg);
          }
          /*
           * This isn't a real handshake message so skip the processing below.
           */
          return 1;
      }
  
      msg_len = msg_hdr->msg_len;
  
      /* reconstruct message header */
      *(p++) = msg_hdr->type;
      l2n3(msg_len, p);
      s2n(msg_hdr->seq, p);
      l2n3(0, p);
      l2n3(msg_len, p);
      if (s->version != DTLS1_BAD_VER) {
          p -= DTLS1_HM_HEADER_LENGTH;
          msg_len += DTLS1_HM_HEADER_LENGTH;
      }
  
      if (!ssl3_finish_mac(s, p, msg_len))
          return 0;
      if (s->msg_callback)
          s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
                          p, msg_len, s, s->msg_callback_arg);
  
      memset(msg_hdr, 0, sizeof(*msg_hdr));
  
      s->d1->handshake_read_seq++;
  
      s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
  
      return 1;
  }
  
  /*
   * dtls1_max_handshake_message_len returns the maximum number of bytes
   * permitted in a DTLS handshake message for |s|. The minimum is 16KB, but
   * may be greater if the maximum certificate list size requires it.
   */
  static size_t dtls1_max_handshake_message_len(const SSL *s)
  {
      size_t max_len = DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH;
      if (max_len < s->max_cert_list)
          return s->max_cert_list;
      return max_len;
  }
  
  static int dtls1_preprocess_fragment(SSL *s, struct hm_header_st *msg_hdr)
  {
      size_t frag_off, frag_len, msg_len;
  
      msg_len = msg_hdr->msg_len;
      frag_off = msg_hdr->frag_off;
      frag_len = msg_hdr->frag_len;
  
      /* sanity checking */
      if ((frag_off + frag_len) > msg_len
              || msg_len > dtls1_max_handshake_message_len(s)) {
          SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_DTLS1_PREPROCESS_FRAGMENT,
                   SSL_R_EXCESSIVE_MESSAGE_SIZE);
          return 0;
      }
  
      if (s->d1->r_msg_hdr.frag_off == 0) { /* first fragment */
          /*
           * msg_len is limited to 2^24, but is effectively checked against
           * dtls_max_handshake_message_len(s) above
           */
          if (!BUF_MEM_grow_clean(s->init_buf, msg_len + DTLS1_HM_HEADER_LENGTH)) {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_PREPROCESS_FRAGMENT,
                       ERR_R_BUF_LIB);
              return 0;
          }
  
          s->s3->tmp.message_size = msg_len;
          s->d1->r_msg_hdr.msg_len = msg_len;
          s->s3->tmp.message_type = msg_hdr->type;
          s->d1->r_msg_hdr.type = msg_hdr->type;
          s->d1->r_msg_hdr.seq = msg_hdr->seq;
      } else if (msg_len != s->d1->r_msg_hdr.msg_len) {
          /*
           * They must be playing with us! BTW, failure to enforce upper limit
           * would open possibility for buffer overrun.
           */
          SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_DTLS1_PREPROCESS_FRAGMENT,
                   SSL_R_EXCESSIVE_MESSAGE_SIZE);
          return 0;
      }
  
      return 1;
  }
  
  /*
   * Returns 1 if there is a buffered fragment available, 0 if not, or -1 on a
   * fatal error.
   */
  static int dtls1_retrieve_buffered_fragment(SSL *s, size_t *len)
  {
      /*-
       * (0) check whether the desired fragment is available
       * if so:
       * (1) copy over the fragment to s->init_buf->data[]
       * (2) update s->init_num
       */
      pitem *item;
      hm_fragment *frag;
      int ret;
  
      do {
          item = pqueue_peek(s->d1->buffered_messages);
          if (item == NULL)
              return 0;
  
          frag = (hm_fragment *)item->data;
  
          if (frag->msg_header.seq < s->d1->handshake_read_seq) {
              /* This is a stale message that has been buffered so clear it */
              pqueue_pop(s->d1->buffered_messages);
              dtls1_hm_fragment_free(frag);
              pitem_free(item);
              item = NULL;
              frag = NULL;
          }
      } while (item == NULL);
  
      /* Don't return if reassembly still in progress */
      if (frag->reassembly != NULL)
          return 0;
  
      if (s->d1->handshake_read_seq == frag->msg_header.seq) {
          size_t frag_len = frag->msg_header.frag_len;
          pqueue_pop(s->d1->buffered_messages);
  
          /* Calls SSLfatal() as required */
          ret = dtls1_preprocess_fragment(s, &frag->msg_header);
  
          if (ret) {
              unsigned char *p =
                  (unsigned char *)s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
              memcpy(&p[frag->msg_header.frag_off], frag->fragment,
                     frag->msg_header.frag_len);
          }
  
          dtls1_hm_fragment_free(frag);
          pitem_free(item);
  
          if (ret) {
              *len = frag_len;
              return 1;
          }
  
          /* Fatal error */
          s->init_num = 0;
          return -1;
      } else {
          return 0;
      }
  }
  
  static int
  dtls1_reassemble_fragment(SSL *s, const struct hm_header_st *msg_hdr)
  {
      hm_fragment *frag = NULL;
      pitem *item = NULL;
      int i = -1, is_complete;
      unsigned char seq64be[8];
      size_t frag_len = msg_hdr->frag_len;
      size_t readbytes;
  
      if ((msg_hdr->frag_off + frag_len) > msg_hdr->msg_len ||
          msg_hdr->msg_len > dtls1_max_handshake_message_len(s))
          goto err;
  
      if (frag_len == 0) {
          return DTLS1_HM_FRAGMENT_RETRY;
      }
  
      /* Try to find item in queue */
      memset(seq64be, 0, sizeof(seq64be));
      seq64be[6] = (unsigned char)(msg_hdr->seq >> 8);
      seq64be[7] = (unsigned char)msg_hdr->seq;
      item = pqueue_find(s->d1->buffered_messages, seq64be);
  
      if (item == NULL) {
          frag = dtls1_hm_fragment_new(msg_hdr->msg_len, 1);
          if (frag == NULL)
              goto err;
          memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
          frag->msg_header.frag_len = frag->msg_header.msg_len;
          frag->msg_header.frag_off = 0;
      } else {
          frag = (hm_fragment *)item->data;
          if (frag->msg_header.msg_len != msg_hdr->msg_len) {
              item = NULL;
              frag = NULL;
              goto err;
          }
      }
  
      /*
       * If message is already reassembled, this must be a retransmit and can
       * be dropped. In this case item != NULL and so frag does not need to be
       * freed.
       */
      if (frag->reassembly == NULL) {
          unsigned char devnull[256];
  
          while (frag_len) {
              i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
                                            devnull,
                                            frag_len >
                                            sizeof(devnull) ? sizeof(devnull) :
                                            frag_len, 0, &readbytes);
              if (i <= 0)
                  goto err;
              frag_len -= readbytes;
          }
          return DTLS1_HM_FRAGMENT_RETRY;
      }
  
      /* read the body of the fragment (header has already been read */
      i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
                                    frag->fragment + msg_hdr->frag_off,
                                    frag_len, 0, &readbytes);
      if (i <= 0 || readbytes != frag_len)
          i = -1;
      if (i <= 0)
          goto err;
  
      RSMBLY_BITMASK_MARK(frag->reassembly, (long)msg_hdr->frag_off,
                          (long)(msg_hdr->frag_off + frag_len));
  
      if (!ossl_assert(msg_hdr->msg_len > 0))
          goto err;
      RSMBLY_BITMASK_IS_COMPLETE(frag->reassembly, (long)msg_hdr->msg_len,
                                 is_complete);
  
      if (is_complete) {
          OPENSSL_free(frag->reassembly);
          frag->reassembly = NULL;
      }
  
      if (item == NULL) {
          item = pitem_new(seq64be, frag);
          if (item == NULL) {
              i = -1;
              goto err;
          }
  
          item = pqueue_insert(s->d1->buffered_messages, item);
          /*
           * pqueue_insert fails iff a duplicate item is inserted. However,
           * |item| cannot be a duplicate. If it were, |pqueue_find|, above,
           * would have returned it and control would never have reached this
           * branch.
           */
          if (!ossl_assert(item != NULL))
              goto err;
      }
  
      return DTLS1_HM_FRAGMENT_RETRY;
  
   err:
      if (item == NULL)
          dtls1_hm_fragment_free(frag);
      return -1;
  }
  
  static int
  dtls1_process_out_of_seq_message(SSL *s, const struct hm_header_st *msg_hdr)
  {
      int i = -1;
      hm_fragment *frag = NULL;
      pitem *item = NULL;
      unsigned char seq64be[8];
      size_t frag_len = msg_hdr->frag_len;
      size_t readbytes;
  
      if ((msg_hdr->frag_off + frag_len) > msg_hdr->msg_len)
          goto err;
  
      /* Try to find item in queue, to prevent duplicate entries */
      memset(seq64be, 0, sizeof(seq64be));
      seq64be[6] = (unsigned char)(msg_hdr->seq >> 8);
      seq64be[7] = (unsigned char)msg_hdr->seq;
      item = pqueue_find(s->d1->buffered_messages, seq64be);
  
      /*
       * If we already have an entry and this one is a fragment, don't discard
       * it and rather try to reassemble it.
       */
      if (item != NULL && frag_len != msg_hdr->msg_len)
          item = NULL;
  
      /*
       * Discard the message if sequence number was already there, is too far
       * in the future, already in the queue or if we received a FINISHED
       * before the SERVER_HELLO, which then must be a stale retransmit.
       */
      if (msg_hdr->seq <= s->d1->handshake_read_seq ||
          msg_hdr->seq > s->d1->handshake_read_seq + 10 || item != NULL ||
          (s->d1->handshake_read_seq == 0 && msg_hdr->type == SSL3_MT_FINISHED)) {
          unsigned char devnull[256];
  
          while (frag_len) {
              i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
                                            devnull,
                                            frag_len >
                                            sizeof(devnull) ? sizeof(devnull) :
                                            frag_len, 0, &readbytes);
              if (i <= 0)
                  goto err;
              frag_len -= readbytes;
          }
      } else {
          if (frag_len != msg_hdr->msg_len) {
              return dtls1_reassemble_fragment(s, msg_hdr);
          }
  
          if (frag_len > dtls1_max_handshake_message_len(s))
              goto err;
  
          frag = dtls1_hm_fragment_new(frag_len, 0);
          if (frag == NULL)
              goto err;
  
          memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
  
          if (frag_len) {
              /*
               * read the body of the fragment (header has already been read
               */
              i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
                                            frag->fragment, frag_len, 0,
                                            &readbytes);
              if (i<=0 || readbytes != frag_len)
                  i = -1;
              if (i <= 0)
                  goto err;
          }
  
          item = pitem_new(seq64be, frag);
          if (item == NULL)
              goto err;
  
          item = pqueue_insert(s->d1->buffered_messages, item);
          /*
           * pqueue_insert fails iff a duplicate item is inserted. However,
           * |item| cannot be a duplicate. If it were, |pqueue_find|, above,
           * would have returned it. Then, either |frag_len| !=
           * |msg_hdr->msg_len| in which case |item| is set to NULL and it will
           * have been processed with |dtls1_reassemble_fragment|, above, or
           * the record will have been discarded.
           */
          if (!ossl_assert(item != NULL))
              goto err;
      }
  
      return DTLS1_HM_FRAGMENT_RETRY;
  
   err:
      if (item == NULL)
          dtls1_hm_fragment_free(frag);
      return 0;
  }
  
  static int dtls_get_reassembled_message(SSL *s, int *errtype, size_t *len)
  {
      unsigned char wire[DTLS1_HM_HEADER_LENGTH];
      size_t mlen, frag_off, frag_len;
      int i, ret, recvd_type;
      struct hm_header_st msg_hdr;
      size_t readbytes;
  
      *errtype = 0;
  
   redo:
      /* see if we have the required fragment already */
      ret = dtls1_retrieve_buffered_fragment(s, &frag_len);
      if (ret < 0) {
          /* SSLfatal() already called */
          return 0;
      }
      if (ret > 0) {
          s->init_num = frag_len;
          *len = frag_len;
          return 1;
      }
  
      /* read handshake message header */
      i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, &recvd_type, wire,
                                    DTLS1_HM_HEADER_LENGTH, 0, &readbytes);
      if (i <= 0) {               /* nbio, or an error */
          s->rwstate = SSL_READING;
          *len = 0;
          return 0;
      }
      if (recvd_type == SSL3_RT_CHANGE_CIPHER_SPEC) {
          if (wire[0] != SSL3_MT_CCS) {
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
                       SSL_F_DTLS_GET_REASSEMBLED_MESSAGE,
                       SSL_R_BAD_CHANGE_CIPHER_SPEC);
              goto f_err;
          }
  
          memcpy(s->init_buf->data, wire, readbytes);
          s->init_num = readbytes - 1;
          s->init_msg = s->init_buf->data + 1;
          s->s3->tmp.message_type = SSL3_MT_CHANGE_CIPHER_SPEC;
          s->s3->tmp.message_size = readbytes - 1;
          *len = readbytes - 1;
          return 1;
      }
  
      /* Handshake fails if message header is incomplete */
      if (readbytes != DTLS1_HM_HEADER_LENGTH) {
          SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
                   SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_UNEXPECTED_MESSAGE);
          goto f_err;
      }
  
      /* parse the message fragment header */
      dtls1_get_message_header(wire, &msg_hdr);
  
      mlen = msg_hdr.msg_len;
      frag_off = msg_hdr.frag_off;
      frag_len = msg_hdr.frag_len;
  
      /*
       * We must have at least frag_len bytes left in the record to be read.
       * Fragments must not span records.
       */
      if (frag_len > RECORD_LAYER_get_rrec_length(&s->rlayer)) {
          SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
                   SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_BAD_LENGTH);
          goto f_err;
      }
  
      /*
       * if this is a future (or stale) message it gets buffered
       * (or dropped)--no further processing at this time
       * While listening, we accept seq 1 (ClientHello with cookie)
       * although we're still expecting seq 0 (ClientHello)
       */
      if (msg_hdr.seq != s->d1->handshake_read_seq) {
          *errtype = dtls1_process_out_of_seq_message(s, &msg_hdr);
          return 0;
      }
  
      if (frag_len && frag_len < mlen) {
          *errtype = dtls1_reassemble_fragment(s, &msg_hdr);
          return 0;
      }
  
      if (!s->server
              && s->d1->r_msg_hdr.frag_off == 0
              && s->statem.hand_state != TLS_ST_OK
              && wire[0] == SSL3_MT_HELLO_REQUEST) {
          /*
           * The server may always send 'Hello Request' messages -- we are
           * doing a handshake anyway now, so ignore them if their format is
           * correct. Does not count for 'Finished' MAC.
           */
          if (wire[1] == 0 && wire[2] == 0 && wire[3] == 0) {
              if (s->msg_callback)
                  s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
                                  wire, DTLS1_HM_HEADER_LENGTH, s,
                                  s->msg_callback_arg);
  
              s->init_num = 0;
              goto redo;
          } else {                /* Incorrectly formatted Hello request */
  
              SSLfatal(s, SSL_AD_UNEXPECTED_MESSAGE,
                       SSL_F_DTLS_GET_REASSEMBLED_MESSAGE,
                       SSL_R_UNEXPECTED_MESSAGE);
              goto f_err;
          }
      }
  
      if (!dtls1_preprocess_fragment(s, &msg_hdr)) {
          /* SSLfatal() already called */
          goto f_err;
      }
  
      if (frag_len > 0) {
          unsigned char *p =
              (unsigned char *)s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
  
          i = s->method->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, NULL,
                                        &p[frag_off], frag_len, 0, &readbytes);
  
          /*
           * This shouldn't ever fail due to NBIO because we already checked
           * that we have enough data in the record
           */
          if (i <= 0) {
              s->rwstate = SSL_READING;
              *len = 0;
              return 0;
          }
      } else {
          readbytes = 0;
      }
  
      /*
       * XDTLS: an incorrectly formatted fragment should cause the handshake
       * to fail
       */
      if (readbytes != frag_len) {
          SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER,
                   SSL_F_DTLS_GET_REASSEMBLED_MESSAGE, SSL_R_BAD_LENGTH);
          goto f_err;
      }
  
      /*
       * Note that s->init_num is *not* used as current offset in
       * s->init_buf->data, but as a counter summing up fragments' lengths: as
       * soon as they sum up to handshake packet length, we assume we have got
       * all the fragments.
       */
      *len = s->init_num = frag_len;
      return 1;
  
   f_err:
      s->init_num = 0;
      *len = 0;
      return 0;
  }
  
  /*-
   * for these 2 messages, we need to
   * ssl->enc_read_ctx                    re-init
   * ssl->rlayer.read_sequence            zero
   * ssl->s3->read_mac_secret             re-init
   * ssl->session->read_sym_enc           assign
   * ssl->session->read_compression       assign
   * ssl->session->read_hash              assign
   */
  int dtls_construct_change_cipher_spec(SSL *s, WPACKET *pkt)
  {
      if (s->version == DTLS1_BAD_VER) {
          s->d1->next_handshake_write_seq++;
  
          if (!WPACKET_put_bytes_u16(pkt, s->d1->handshake_write_seq)) {
              SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                       SSL_F_DTLS_CONSTRUCT_CHANGE_CIPHER_SPEC,
                       ERR_R_INTERNAL_ERROR);
              return 0;
          }
      }
  
      return 1;
  }
  
  #ifndef OPENSSL_NO_SCTP
  WORK_STATE dtls_wait_for_dry(SSL *s)
  {
      int ret;
  
      /* read app data until dry event */
      ret = BIO_dgram_sctp_wait_for_dry(SSL_get_wbio(s));
      if (ret < 0) {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS_WAIT_FOR_DRY,
                   ERR_R_INTERNAL_ERROR);
          return WORK_ERROR;
      }
  
      if (ret == 0) {
          s->s3->in_read_app_data = 2;
          s->rwstate = SSL_READING;
          BIO_clear_retry_flags(SSL_get_rbio(s));
          BIO_set_retry_read(SSL_get_rbio(s));
          return WORK_MORE_A;
      }
      return WORK_FINISHED_CONTINUE;
  }
  #endif
  
  int dtls1_read_failed(SSL *s, int code)
  {
      if (code > 0) {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR,
                   SSL_F_DTLS1_READ_FAILED, ERR_R_INTERNAL_ERROR);
          return 0;
      }
  
      if (!dtls1_is_timer_expired(s)) {
          /*
           * not a timeout, none of our business, let higher layers handle
           * this.  in fact it's probably an error
           */
          return code;
      }
      /* done, no need to send a retransmit */
      if (!SSL_in_init(s))
      {
          BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
          return code;
      }
  
      return dtls1_handle_timeout(s);
  }
  
  int dtls1_get_queue_priority(unsigned short seq, int is_ccs)
  {
      /*
       * The index of the retransmission queue actually is the message sequence
       * number, since the queue only contains messages of a single handshake.
       * However, the ChangeCipherSpec has no message sequence number and so
       * using only the sequence will result in the CCS and Finished having the
       * same index. To prevent this, the sequence number is multiplied by 2.
       * In case of a CCS 1 is subtracted. This does not only differ CSS and
       * Finished, it also maintains the order of the index (important for
       * priority queues) and fits in the unsigned short variable.
       */
      return seq * 2 - is_ccs;
  }
  
  int dtls1_retransmit_buffered_messages(SSL *s)
  {
      pqueue *sent = s->d1->sent_messages;
      piterator iter;
      pitem *item;
      hm_fragment *frag;
      int found = 0;
  
      iter = pqueue_iterator(sent);
  
      for (item = pqueue_next(&iter); item != NULL; item = pqueue_next(&iter)) {
          frag = (hm_fragment *)item->data;
          if (dtls1_retransmit_message(s, (unsigned short)
                                       dtls1_get_queue_priority
                                       (frag->msg_header.seq,
                                        frag->msg_header.is_ccs), &found) <= 0)
              return -1;
      }
  
      return 1;
  }
  
  int dtls1_buffer_message(SSL *s, int is_ccs)
  {
      pitem *item;
      hm_fragment *frag;
      unsigned char seq64be[8];
  
      /*
       * this function is called immediately after a message has been
       * serialized
       */
      if (!ossl_assert(s->init_off == 0))
          return 0;
  
      frag = dtls1_hm_fragment_new(s->init_num, 0);
      if (frag == NULL)
          return 0;
  
      memcpy(frag->fragment, s->init_buf->data, s->init_num);
  
      if (is_ccs) {
          /* For DTLS1_BAD_VER the header length is non-standard */
          if (!ossl_assert(s->d1->w_msg_hdr.msg_len +
                           ((s->version ==
                             DTLS1_BAD_VER) ? 3 : DTLS1_CCS_HEADER_LENGTH)
                           == (unsigned int)s->init_num))
              return 0;
      } else {
          if (!ossl_assert(s->d1->w_msg_hdr.msg_len +
                           DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num))
              return 0;
      }
  
      frag->msg_header.msg_len = s->d1->w_msg_hdr.msg_len;
      frag->msg_header.seq = s->d1->w_msg_hdr.seq;
      frag->msg_header.type = s->d1->w_msg_hdr.type;
      frag->msg_header.frag_off = 0;
      frag->msg_header.frag_len = s->d1->w_msg_hdr.msg_len;
      frag->msg_header.is_ccs = is_ccs;
  
      /* save current state */
      frag->msg_header.saved_retransmit_state.enc_write_ctx = s->enc_write_ctx;
      frag->msg_header.saved_retransmit_state.write_hash = s->write_hash;
      frag->msg_header.saved_retransmit_state.compress = s->compress;
      frag->msg_header.saved_retransmit_state.session = s->session;
      frag->msg_header.saved_retransmit_state.epoch =
          DTLS_RECORD_LAYER_get_w_epoch(&s->rlayer);
  
      memset(seq64be, 0, sizeof(seq64be));
      seq64be[6] =
          (unsigned
           char)(dtls1_get_queue_priority(frag->msg_header.seq,
                                          frag->msg_header.is_ccs) >> 8);
      seq64be[7] =
          (unsigned
           char)(dtls1_get_queue_priority(frag->msg_header.seq,
                                          frag->msg_header.is_ccs));
  
      item = pitem_new(seq64be, frag);
      if (item == NULL) {
          dtls1_hm_fragment_free(frag);
          return 0;
      }
  
      pqueue_insert(s->d1->sent_messages, item);
      return 1;
  }
  
  int dtls1_retransmit_message(SSL *s, unsigned short seq, int *found)
  {
      int ret;
      /* XDTLS: for now assuming that read/writes are blocking */
      pitem *item;
      hm_fragment *frag;
      unsigned long header_length;
      unsigned char seq64be[8];
      struct dtls1_retransmit_state saved_state;
  
      /* XDTLS:  the requested message ought to be found, otherwise error */
      memset(seq64be, 0, sizeof(seq64be));
      seq64be[6] = (unsigned char)(seq >> 8);
      seq64be[7] = (unsigned char)seq;
  
      item = pqueue_find(s->d1->sent_messages, seq64be);
      if (item == NULL) {
          SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DTLS1_RETRANSMIT_MESSAGE,
                   ERR_R_INTERNAL_ERROR);
          *found = 0;
          return 0;
      }
  
      *found = 1;
      frag = (hm_fragment *)item->data;
  
      if (frag->msg_header.is_ccs)
          header_length = DTLS1_CCS_HEADER_LENGTH;
      else
          header_length = DTLS1_HM_HEADER_LENGTH;
  
      memcpy(s->init_buf->data, frag->fragment,
             frag->msg_header.msg_len + header_length);
      s->init_num = frag->msg_header.msg_len + header_length;
  
      dtls1_set_message_header_int(s, frag->msg_header.type,
                                   frag->msg_header.msg_len,
                                   frag->msg_header.seq, 0,
                                   frag->msg_header.frag_len);
  
      /* save current state */
      saved_state.enc_write_ctx = s->enc_write_ctx;
      saved_state.write_hash = s->write_hash;
      saved_state.compress = s->compress;
      saved_state.session = s->session;
      saved_state.epoch = DTLS_RECORD_LAYER_get_w_epoch(&s->rlayer);
  
      s->d1->retransmitting = 1;
  
      /* restore state in which the message was originally sent */
      s->enc_write_ctx = frag->msg_header.saved_retransmit_state.enc_write_ctx;
      s->write_hash = frag->msg_header.saved_retransmit_state.write_hash;
      s->compress = frag->msg_header.saved_retransmit_state.compress;
      s->session = frag->msg_header.saved_retransmit_state.session;
      DTLS_RECORD_LAYER_set_saved_w_epoch(&s->rlayer,
                                          frag->msg_header.
                                          saved_retransmit_state.epoch);
  
      ret = dtls1_do_write(s, frag->msg_header.is_ccs ?
                           SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
  
      /* restore current state */
      s->enc_write_ctx = saved_state.enc_write_ctx;
      s->write_hash = saved_state.write_hash;
      s->compress = saved_state.compress;
      s->session = saved_state.session;
      DTLS_RECORD_LAYER_set_saved_w_epoch(&s->rlayer, saved_state.epoch);
  
      s->d1->retransmitting = 0;
  
      (void)BIO_flush(s->wbio);
      return ret;
  }
  
  void dtls1_set_message_header(SSL *s,
                                unsigned char mt, size_t len,
                                size_t frag_off, size_t frag_len)
  {
      if (frag_off == 0) {
          s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
          s->d1->next_handshake_write_seq++;
      }
  
      dtls1_set_message_header_int(s, mt, len, s->d1->handshake_write_seq,
                                   frag_off, frag_len);
  }
  
  /* don't actually do the writing, wait till the MTU has been retrieved */
  static void
  dtls1_set_message_header_int(SSL *s, unsigned char mt,
                               size_t len, unsigned short seq_num,
                               size_t frag_off, size_t frag_len)
  {
      struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
  
      msg_hdr->type = mt;
      msg_hdr->msg_len = len;
      msg_hdr->seq = seq_num;
      msg_hdr->frag_off = frag_off;
      msg_hdr->frag_len = frag_len;
  }
  
  static void
  dtls1_fix_message_header(SSL *s, size_t frag_off, size_t frag_len)
  {
      struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
  
      msg_hdr->frag_off = frag_off;
      msg_hdr->frag_len = frag_len;
  }
  
  static unsigned char *dtls1_write_message_header(SSL *s, unsigned char *p)
  {
      struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
  
      *p++ = msg_hdr->type;
      l2n3(msg_hdr->msg_len, p);
  
      s2n(msg_hdr->seq, p);
      l2n3(msg_hdr->frag_off, p);
      l2n3(msg_hdr->frag_len, p);
  
      return p;
  }
  
  void dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
  {
      memset(msg_hdr, 0, sizeof(*msg_hdr));
      msg_hdr->type = *(data++);
      n2l3(data, msg_hdr->msg_len);
  
      n2s(data, msg_hdr->seq);
      n2l3(data, msg_hdr->frag_off);
      n2l3(data, msg_hdr->frag_len);
  }
  
  int dtls1_set_handshake_header(SSL *s, WPACKET *pkt, int htype)
  {
      unsigned char *header;
  
      if (htype == SSL3_MT_CHANGE_CIPHER_SPEC) {
          s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
          dtls1_set_message_header_int(s, SSL3_MT_CCS, 0,
                                       s->d1->handshake_write_seq, 0, 0);
          if (!WPACKET_put_bytes_u8(pkt, SSL3_MT_CCS))
              return 0;
      } else {
          dtls1_set_message_header(s, htype, 0, 0, 0);
          /*
           * We allocate space at the start for the message header. This gets
           * filled in later
           */
          if (!WPACKET_allocate_bytes(pkt, DTLS1_HM_HEADER_LENGTH, &header)
                  || !WPACKET_start_sub_packet(pkt))
              return 0;
      }
  
      return 1;
  }
  
  int dtls1_close_construct_packet(SSL *s, WPACKET *pkt, int htype)
  {
      size_t msglen;
  
      if ((htype != SSL3_MT_CHANGE_CIPHER_SPEC && !WPACKET_close(pkt))
              || !WPACKET_get_length(pkt, &msglen)
              || msglen > INT_MAX)
          return 0;
  
      if (htype != SSL3_MT_CHANGE_CIPHER_SPEC) {
          s->d1->w_msg_hdr.msg_len = msglen - DTLS1_HM_HEADER_LENGTH;
          s->d1->w_msg_hdr.frag_len = msglen - DTLS1_HM_HEADER_LENGTH;
      }
      s->init_num = (int)msglen;
      s->init_off = 0;
  
      if (htype != DTLS1_MT_HELLO_VERIFY_REQUEST) {
          /* Buffer the message to handle re-xmits */
          if (!dtls1_buffer_message(s, htype == SSL3_MT_CHANGE_CIPHER_SPEC
                                       ? 1 : 0))
              return 0;
      }
  
      return 1;
  }
  