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d1_both.c

/* ssl/d1_both.c */
/* 
 * DTLS implementation written by Nagendra Modadugu
 * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.  
 */
/* ====================================================================
 * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <limits.h>
#include <string.h>
#include <stdio.h>
#include "ssl_locl.h"
#include <openssl/buffer.h>
#include <openssl/rand.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; \
                  OPENSSL_assert((msg_len) > 0); \
                  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; } }

#if 0
#define RSMBLY_BITMASK_PRINT(bitmask, msg_len) { \
                  long ii; \
                  printf("bitmask: "); for (ii = 0; ii < (msg_len); ii++) \
                  printf("%d ", (bitmask[ii >> 3] & (1 << (ii & 7))) >> (ii & 7)); \
                  printf("\n"); }
#endif

static unsigned char bitmask_start_values[] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80};
static unsigned char bitmask_end_values[]   = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f};

/* XDTLS:  figure out the right values */
static unsigned int g_probable_mtu[] = {1500 - 28, 512 - 28, 256 - 28};

static unsigned int dtls1_min_mtu(void);
static unsigned int dtls1_guess_mtu(unsigned int curr_mtu);
static void dtls1_fix_message_header(SSL *s, unsigned long frag_off, 
      unsigned long 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,
      unsigned long len, unsigned short seq_num, unsigned long frag_off, 
      unsigned long frag_len);
static long dtls1_get_message_fragment(SSL *s, int st1, int stn, 
      long max, int *ok);

static hm_fragment *
dtls1_hm_fragment_new(unsigned long frag_len, int reassembly)
      {
      hm_fragment *frag = NULL;
      unsigned char *buf = NULL;
      unsigned char *bitmask = NULL;

      frag = (hm_fragment *)OPENSSL_malloc(sizeof(hm_fragment));
      if ( frag == NULL)
            return NULL;

      if (frag_len)
            {
            buf = (unsigned char *)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 = (unsigned char *)OPENSSL_malloc(RSMBLY_BITMASK_SIZE(frag_len));
            if (bitmask == NULL)
                  {
                  if (buf != NULL) OPENSSL_free(buf);
                  OPENSSL_free(frag);
                  return NULL;
                  }
            memset(bitmask, 0, RSMBLY_BITMASK_SIZE(frag_len));
            }

      frag->reassembly = bitmask;

      return frag;
      }

static void
dtls1_hm_fragment_free(hm_fragment *frag)
      {
      if (frag->fragment) OPENSSL_free(frag->fragment);
      if (frag->reassembly) 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;
      int curr_mtu;
      unsigned int len, frag_off, mac_size, blocksize;

      /* AHA!  Figure out the MTU, and stick to the right size */
      if ( ! (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
            {
            s->d1->mtu = 
                  BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);

            /* I've seen the kernel return bogus numbers when it doesn't know
             * (initial write), so just make sure we have a reasonable number */
            if ( s->d1->mtu < dtls1_min_mtu())
                  {
                  s->d1->mtu = 0;
                  s->d1->mtu = dtls1_guess_mtu(s->d1->mtu);
                  BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU, 
                        s->d1->mtu, NULL);
                  }
            }
#if 0 
      mtu = s->d1->mtu;

      fprintf(stderr, "using MTU = %d\n", mtu);

      mtu -= (DTLS1_HM_HEADER_LENGTH + DTLS1_RT_HEADER_LENGTH);

      curr_mtu = mtu - BIO_wpending(SSL_get_wbio(s));

      if ( curr_mtu > 0)
            mtu = curr_mtu;
      else if ( ( ret = BIO_flush(SSL_get_wbio(s))) <= 0)
            return ret;

      if ( BIO_wpending(SSL_get_wbio(s)) + s->init_num >= mtu)
            {
            ret = BIO_flush(SSL_get_wbio(s));
            if ( ret <= 0)
                  return ret;
            mtu = s->d1->mtu - (DTLS1_HM_HEADER_LENGTH + DTLS1_RT_HEADER_LENGTH);
            }

      OPENSSL_assert(mtu > 0);  /* should have something reasonable now */

#endif

      if ( s->init_off == 0  && type == SSL3_RT_HANDSHAKE)
            OPENSSL_assert(s->init_num == 
                  (int)s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH);

      if (s->write_hash)
            mac_size = EVP_MD_size(s->write_hash);
      else
            mac_size = 0;

      if (s->enc_write_ctx && 
            (EVP_CIPHER_mode( s->enc_write_ctx->cipher) & EVP_CIPH_CBC_MODE))
            blocksize = 2 * EVP_CIPHER_block_size(s->enc_write_ctx->cipher);
      else
            blocksize = 0;

      frag_off = 0;
      while( s->init_num)
            {
            curr_mtu = s->d1->mtu - BIO_wpending(SSL_get_wbio(s)) - 
                  DTLS1_RT_HEADER_LENGTH - mac_size - blocksize;

            if ( curr_mtu <= DTLS1_HM_HEADER_LENGTH)
                  {
                  /* grr.. we could get an error if MTU picked was wrong */
                  ret = BIO_flush(SSL_get_wbio(s));
                  if ( ret <= 0)
                        return ret;
                  curr_mtu = s->d1->mtu - DTLS1_RT_HEADER_LENGTH -
                        mac_size - blocksize;
                  }

            if ( s->init_num > curr_mtu)
                  len = curr_mtu;
            else
                  len = s->init_num;


            /* XDTLS: this function is too long.  split out the CCS part */
            if ( type == SSL3_RT_HANDSHAKE)
                  {
                  if ( s->init_off != 0)
                        {
                        OPENSSL_assert(s->init_off > DTLS1_HM_HEADER_LENGTH);
                        s->init_off -= DTLS1_HM_HEADER_LENGTH;
                        s->init_num += DTLS1_HM_HEADER_LENGTH;

                        /* write atleast DTLS1_HM_HEADER_LENGTH bytes */
                        if ( len <= DTLS1_HM_HEADER_LENGTH)  
                              len += DTLS1_HM_HEADER_LENGTH;
                        }

                  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]);

                  OPENSSL_assert(len >= DTLS1_HM_HEADER_LENGTH);
                  }

            ret=dtls1_write_bytes(s,type,&s->init_buf->data[s->init_off],
                  len);
            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 ( BIO_ctrl(SSL_get_wbio(s),
                        BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0 )
                        s->d1->mtu = BIO_ctrl(SSL_get_wbio(s),
                              BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
                  else
                        return(-1);
                  }
            else
                  {

                  /* bad if this assert fails, only part of the handshake
                   * message got sent.  but why would this happen? */
                  OPENSSL_assert(len == (unsigned int)ret);

                  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;
                        int xlen;

                        if (frag_off == 0 && s->client_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 = ret;
                              }
                        else
                              {
                              p  += DTLS1_HM_HEADER_LENGTH;
                              xlen = ret - DTLS1_HM_HEADER_LENGTH;
                              }

                        ssl3_finish_mac(s, p, xlen);
                        }

                  if (ret == 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+=ret;
                  s->init_num-=ret;
                  frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
                  }
            }
      return(0);
      }


/* Obtain handshake message of message type 'mt' (any if mt == -1),
 * maximum acceptable body length 'max'.
 * Read an entire handshake message.  Handshake messages arrive in
 * fragments.
 */
long dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
      {
      int i, al;
      struct hm_header_st *msg_hdr;
      unsigned char *p;
      unsigned long msg_len;

      /* s3->tmp is used to store messages that are unexpected, caused
       * by the absence of an optional handshake message */
      if (s->s3->tmp.reuse_message)
            {
            s->s3->tmp.reuse_message=0;
            if ((mt >= 0) && (s->s3->tmp.message_type != mt))
                  {
                  al=SSL_AD_UNEXPECTED_MESSAGE;
                  SSLerr(SSL_F_DTLS1_GET_MESSAGE,SSL_R_UNEXPECTED_MESSAGE);
                  goto f_err;
                  }
            *ok=1;
            s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
            s->init_num = (int)s->s3->tmp.message_size;
            return s->init_num;
            }

      msg_hdr = &s->d1->r_msg_hdr;
      memset(msg_hdr, 0x00, sizeof(struct hm_header_st));

again:
      i = dtls1_get_message_fragment(s, st1, stn, max, ok);
      if ( i == DTLS1_HM_BAD_FRAGMENT ||
            i == DTLS1_HM_FRAGMENT_RETRY)  /* bad fragment received */
            goto again;
      else if ( i <= 0 && !*ok)
            return i;

      p = (unsigned char *)s->init_buf->data;
      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;
      }

      ssl3_finish_mac(s, p, msg_len);
      if (s->msg_callback)
            s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
                  p, msg_len,
                  s, s->msg_callback_arg);

      memset(msg_hdr, 0x00, sizeof(struct hm_header_st));

      s->d1->handshake_read_seq++;
      /* we just read a handshake message from the other side:
       * this means that we don't need to retransmit of the
       * buffered messages.  
       * XDTLS: may be able clear out this
       * buffer a little sooner (i.e if an out-of-order
       * handshake message/record is received at the record
       * layer.  
       * XDTLS: exception is that the server needs to
       * know that change cipher spec and finished messages
       * have been received by the client before clearing this
       * buffer.  this can simply be done by waiting for the
       * first data  segment, but is there a better way?  */
      dtls1_clear_record_buffer(s);

      s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
      return s->init_num;

f_err:
      ssl3_send_alert(s,SSL3_AL_FATAL,al);
      *ok = 0;
      return -1;
      }


static int dtls1_preprocess_fragment(SSL *s,struct hm_header_st *msg_hdr,int max)
      {
      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)
            {
            SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
            return SSL_AD_ILLEGAL_PARAMETER;
            }

      if ( (frag_off+frag_len) > (unsigned long)max)
            {
            SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
            return SSL_AD_ILLEGAL_PARAMETER;
            }

      if ( s->d1->r_msg_hdr.frag_off == 0) /* first fragment */
            {
            /* msg_len is limited to 2^24, but is effectively checked
             * against max above */
            if (!BUF_MEM_grow_clean(s->init_buf,(int)msg_len+DTLS1_HM_HEADER_LENGTH))
                  {
                  SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,ERR_R_BUF_LIB);
                  return SSL_AD_INTERNAL_ERROR;
                  }

            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. */
            SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
            return SSL_AD_ILLEGAL_PARAMETER;
            }

      return 0; /* no error */
      }


static int
dtls1_retrieve_buffered_fragment(SSL *s, long max, int *ok)
      {
      /* (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 al;

      *ok = 0;
      item = pqueue_peek(s->d1->buffered_messages);
      if ( item == NULL)
            return 0;

      frag = (hm_fragment *)item->data;
      
      /* Don't return if reassembly still in progress */
      if (frag->reassembly != NULL)
            return 0;

      if ( s->d1->handshake_read_seq == frag->msg_header.seq)
            {
            unsigned long frag_len = frag->msg_header.frag_len;
            pqueue_pop(s->d1->buffered_messages);

            al=dtls1_preprocess_fragment(s,&frag->msg_header,max);

            if (al==0) /* no alert */
                  {
                  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 (al==0)
                  {
                  *ok = 1;
                  return frag_len;
                  }

            ssl3_send_alert(s,SSL3_AL_FATAL,al);
            s->init_num = 0;
            *ok = 0;
            return -1;
            }
      else
            return 0;
      }


static int
dtls1_reassemble_fragment(SSL *s, struct hm_header_st* msg_hdr, int *ok)
      {
      hm_fragment *frag = NULL;
      pitem *item = NULL;
      int i = -1, is_complete;
      PQ_64BIT seq64;
      unsigned long frag_len = msg_hdr->frag_len, max_len;

      if ((msg_hdr->frag_off+frag_len) > msg_hdr->msg_len)
            goto err;

      /* Determine maximum allowed message size. Depends on (user set)
       * maximum certificate length, but 16k is minimum.
       */
      if (DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH < s->max_cert_list)
            max_len = s->max_cert_list;
      else
            max_len = DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH;

      if ((msg_hdr->frag_off+frag_len) > max_len)
            goto err;

      /* Try to find item in queue */
      pq_64bit_init(&seq64);
      pq_64bit_assign_word(&seq64, msg_hdr->seq);
      item = pqueue_find(s->d1->buffered_messages, seq64);
      pq_64bit_free(&seq64);

      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 message is already reassembled, this must be a
       * retransmit and can be dropped.
       */
      if (frag->reassembly == NULL)
            {
            unsigned char devnull [256];

            while (frag_len)
                  {
                  i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
                        devnull,
                        frag_len>sizeof(devnull)?sizeof(devnull):frag_len,0);
                  if (i<=0) goto err;
                  frag_len -= i;
                  }
            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,
            frag->fragment + msg_hdr->frag_off,frag_len,0);
      if (i<=0 || (unsigned long)i!=frag_len)
            goto err;

      RSMBLY_BITMASK_MARK(frag->reassembly, (long)msg_hdr->frag_off,
                          (long)(msg_hdr->frag_off + frag_len));

      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)
            {
            pq_64bit_init(&seq64);
            pq_64bit_assign_word(&seq64, msg_hdr->seq);
            item = pitem_new(seq64, frag);
            pq_64bit_free(&seq64);

            if (item == NULL)
                  {
                  goto err;
                  i = -1;
                  }

            pqueue_insert(s->d1->buffered_messages, item);
            }

      return DTLS1_HM_FRAGMENT_RETRY;

err:
      if (frag != NULL) dtls1_hm_fragment_free(frag);
      if (item != NULL) OPENSSL_free(item);
      *ok = 0;
      return i;
      }


static int
dtls1_process_out_of_seq_message(SSL *s, struct hm_header_st* msg_hdr, int *ok)
{
      int i=-1;
      hm_fragment *frag = NULL;
      pitem *item = NULL;
      PQ_64BIT seq64;
      unsigned long frag_len = msg_hdr->frag_len;

      if ((msg_hdr->frag_off+frag_len) > msg_hdr->msg_len)
            goto err;

      /* Try to find item in queue, to prevent duplicate entries */
      pq_64bit_init(&seq64);
      pq_64bit_assign_word(&seq64, msg_hdr->seq);
      item = pqueue_find(s->d1->buffered_messages, seq64);
      pq_64bit_free(&seq64);

      /* 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,
                        devnull,
                        frag_len>sizeof(devnull)?sizeof(devnull):frag_len,0);
                  if (i<=0) goto err;
                  frag_len -= i;
                  }
            }
      else
            {
            if (frag_len && frag_len < msg_hdr->msg_len)
                  return dtls1_reassemble_fragment(s, msg_hdr, ok);

            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,
                        frag->fragment,frag_len,0);
                  if (i<=0 || (unsigned long)i!=frag_len)
                        goto err;
                  }

            pq_64bit_init(&seq64);
            pq_64bit_assign_word(&seq64, msg_hdr->seq);

            item = pitem_new(seq64, frag);
            pq_64bit_free(&seq64);
            if ( item == NULL)
                  goto err;

            pqueue_insert(s->d1->buffered_messages, item);
            }

      return DTLS1_HM_FRAGMENT_RETRY;

err:
      if ( frag != NULL) dtls1_hm_fragment_free(frag);
      if ( item != NULL) OPENSSL_free(item);
      *ok = 0;
      return i;
      }


static long
dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
      {
      unsigned char wire[DTLS1_HM_HEADER_LENGTH];
      unsigned long len, frag_off, frag_len;
      int i,al;
      struct hm_header_st msg_hdr;

      /* see if we have the required fragment already */
      if ((frag_len = dtls1_retrieve_buffered_fragment(s,max,ok)) || *ok)
            {
            if (*ok)    s->init_num = frag_len;
            return frag_len;
            }

      /* read handshake message header */
      i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,wire,
            DTLS1_HM_HEADER_LENGTH, 0);
      if (i <= 0)       /* nbio, or an error */
            {
            s->rwstate=SSL_READING;
            *ok = 0;
            return i;
            }
      OPENSSL_assert(i == DTLS1_HM_HEADER_LENGTH);

      /* parse the message fragment header */
      dtls1_get_message_header(wire, &msg_hdr);

      /* 
       * if this is a future (or stale) message it gets buffered
       * (or dropped)--no further processing at this time 
       */
      if ( msg_hdr.seq != s->d1->handshake_read_seq)
            return dtls1_process_out_of_seq_message(s, &msg_hdr, ok);

      len = msg_hdr.msg_len;
      frag_off = msg_hdr.frag_off;
      frag_len = msg_hdr.frag_len;

      if (frag_len && frag_len < len)
            return dtls1_reassemble_fragment(s, &msg_hdr, ok);

      if (!s->server && s->d1->r_msg_hdr.frag_off == 0 &&
            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;
                  return dtls1_get_message_fragment(s, st1, stn,
                        max, ok);
                  }
            else /* Incorrectly formated Hello request */
                  {
                  al=SSL_AD_UNEXPECTED_MESSAGE;
                  SSLerr(SSL_F_DTLS1_GET_MESSAGE_FRAGMENT,SSL_R_UNEXPECTED_MESSAGE);
                  goto f_err;
                  }
            }

      if ((al=dtls1_preprocess_fragment(s,&msg_hdr,max)))
            goto f_err;

      /* XDTLS:  ressurect this when restart is in place */
      s->state=stn;

      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,
                  &p[frag_off],frag_len,0);
            /* XDTLS:  fix this--message fragments cannot span multiple packets */
            if (i <= 0)
                  {
                  s->rwstate=SSL_READING;
                  *ok = 0;
                  return i;
                  }
            }
      else
            i = 0;

      /* XDTLS:  an incorrectly formatted fragment should cause the 
       * handshake to fail */
      OPENSSL_assert(i == (int)frag_len);

      *ok = 1;

      /* 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. */
      s->init_num = frag_len;
      return frag_len;

f_err:
      ssl3_send_alert(s,SSL3_AL_FATAL,al);
      s->init_num = 0;

      *ok=0;
      return(-1);
      }

int dtls1_send_finished(SSL *s, int a, int b, const char *sender, int slen)
      {
      unsigned char *p,*d;
      int i;
      unsigned long l;

      if (s->state == a)
            {
            d=(unsigned char *)s->init_buf->data;
            p= &(d[DTLS1_HM_HEADER_LENGTH]);

            i=s->method->ssl3_enc->final_finish_mac(s,
                  &(s->s3->finish_dgst1),
                  &(s->s3->finish_dgst2),
                  sender,slen,s->s3->tmp.finish_md);
            s->s3->tmp.finish_md_len = i;
            memcpy(p, s->s3->tmp.finish_md, i);
            p+=i;
            l=i;

      /* Copy the finished so we can use it for
       * renegotiation checks
       */
      if(s->type == SSL_ST_CONNECT)
            {
            OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
            memcpy(s->s3->previous_client_finished, 
                   s->s3->tmp.finish_md, i);
            s->s3->previous_client_finished_len=i;
            }
      else
            {
            OPENSSL_assert(i <= EVP_MAX_MD_SIZE);
            memcpy(s->s3->previous_server_finished, 
                   s->s3->tmp.finish_md, i);
            s->s3->previous_server_finished_len=i;
            }

#ifdef OPENSSL_SYS_WIN16
            /* MSVC 1.5 does not clear the top bytes of the word unless
             * I do this.
             */
            l&=0xffff;
#endif

            d = dtls1_set_message_header(s, d, SSL3_MT_FINISHED, l, 0, l);
            s->init_num=(int)l+DTLS1_HM_HEADER_LENGTH;
            s->init_off=0;

            /* buffer the message to handle re-xmits */
            dtls1_buffer_message(s, 0);

            s->state=b;
            }

      /* SSL3_ST_SEND_xxxxxx_HELLO_B */
      return(dtls1_do_write(s,SSL3_RT_HANDSHAKE));
      }

/* for these 2 messages, we need to
 * ssl->enc_read_ctx                re-init
 * ssl->s3->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 dtls1_send_change_cipher_spec(SSL *s, int a, int b)
      { 
      unsigned char *p;

      if (s->state == a)
            {
            p=(unsigned char *)s->init_buf->data;
            *p++=SSL3_MT_CCS;
            s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
            s->init_num=DTLS1_CCS_HEADER_LENGTH;

            if (s->client_version == DTLS1_BAD_VER)
                  {
                  s->d1->next_handshake_write_seq++;
                  s2n(s->d1->handshake_write_seq,p);
                  s->init_num+=2;
                  }

            s->init_off=0;

            dtls1_set_message_header_int(s, SSL3_MT_CCS, 0, 
                  s->d1->handshake_write_seq, 0, 0);

            /* buffer the message to handle re-xmits */
            dtls1_buffer_message(s, 1);

            s->state=b;
            }

      /* SSL3_ST_CW_CHANGE_B */
      return(dtls1_do_write(s,SSL3_RT_CHANGE_CIPHER_SPEC));
      }

static int dtls1_add_cert_to_buf(BUF_MEM *buf, unsigned long *l, X509 *x)
      {
            int n;
            unsigned char *p;

            n=i2d_X509(x,NULL);
            if (!BUF_MEM_grow_clean(buf,(int)(n+(*l)+3)))
                  {
                  SSLerr(SSL_F_DTLS1_ADD_CERT_TO_BUF,ERR_R_BUF_LIB);
                  return 0;
                  }
            p=(unsigned char *)&(buf->data[*l]);
            l2n3(n,p);
            i2d_X509(x,&p);
            *l+=n+3;

            return 1;
      }
unsigned long dtls1_output_cert_chain(SSL *s, X509 *x)
      {
      unsigned char *p;
      int i;
      unsigned long l= 3 + DTLS1_HM_HEADER_LENGTH;
      BUF_MEM *buf;

      /* TLSv1 sends a chain with nothing in it, instead of an alert */
      buf=s->init_buf;
      if (!BUF_MEM_grow_clean(buf,10))
            {
            SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_BUF_LIB);
            return(0);
            }
      if (x != NULL)
            {
            X509_STORE_CTX xs_ctx;
  
            if (!X509_STORE_CTX_init(&xs_ctx,s->ctx->cert_store,x,NULL))
                  {
                  SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_X509_LIB);
                  return(0);
                  }
  
            X509_verify_cert(&xs_ctx);
            /* Don't leave errors in the queue */
            ERR_clear_error();
            for (i=0; i < sk_X509_num(xs_ctx.chain); i++)
                  {
                  x = sk_X509_value(xs_ctx.chain, i);

                  if (!dtls1_add_cert_to_buf(buf, &l, x))
                        {
                        X509_STORE_CTX_cleanup(&xs_ctx);
                        return 0;
                        }
                  }
            X509_STORE_CTX_cleanup(&xs_ctx);
            }
      /* Thawte special :-) */
      for (i=0; i<sk_X509_num(s->ctx->extra_certs); i++)
            {
            x=sk_X509_value(s->ctx->extra_certs,i);
            if (!dtls1_add_cert_to_buf(buf, &l, x))
                  return 0;
            }

      l-= (3 + DTLS1_HM_HEADER_LENGTH);

      p=(unsigned char *)&(buf->data[DTLS1_HM_HEADER_LENGTH]);
      l2n3(l,p);
      l+=3;
      p=(unsigned char *)&(buf->data[0]);
      p = dtls1_set_message_header(s, p, SSL3_MT_CERTIFICATE, l, 0, l);

      l+=DTLS1_HM_HEADER_LENGTH;
      return(l);
      }

int dtls1_read_failed(SSL *s, int code)
      {
      if ( code > 0)
            {
            fprintf( stderr, "invalid state reached %s:%d", __FILE__, __LINE__);
            return 1;
            }

      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;
            }

      if ( ! SSL_in_init(s))  /* done, no need to send a retransmit */
            {
            BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
            return code;
            }

#if 0 /* for now, each alert contains only one record number */
      item = pqueue_peek(state->rcvd_records);
      if ( item )
            {
            /* send an alert immediately for all the missing records */
            }
      else
#endif

#if 0  /* no more alert sending, just retransmit the last set of messages */
      if ( state->timeout.read_timeouts >= DTLS1_TMO_READ_COUNT)
            ssl3_send_alert(s,SSL3_AL_WARNING,
                  DTLS1_AD_MISSING_HANDSHAKE_MESSAGE);
#endif

      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),
                        0, &found) <= 0 && found)
                  {
                  fprintf(stderr, "dtls1_retransmit_message() failed\n");
                  return -1;
                  }
            }

      return 1;
      }

int
dtls1_buffer_message(SSL *s, int is_ccs)
      {
      pitem *item;
      hm_fragment *frag;
      PQ_64BIT seq64;

      /* this function is called immediately after a message has 
       * been serialized */
      OPENSSL_assert(s->init_off == 0);

      frag = dtls1_hm_fragment_new(s->init_num, 0);

      memcpy(frag->fragment, s->init_buf->data, s->init_num);

      if ( is_ccs)
            {
            OPENSSL_assert(s->d1->w_msg_hdr.msg_len + 
                  DTLS1_CCS_HEADER_LENGTH <= (unsigned int)s->init_num);
            }
      else
            {
            OPENSSL_assert(s->d1->w_msg_hdr.msg_len + 
                  DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num);
            }

      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 = s->d1->w_epoch;

      pq_64bit_init(&seq64);

      pq_64bit_assign_word(&seq64,
                                     dtls1_get_queue_priority(frag->msg_header.seq,
                                                                          frag->msg_header.is_ccs));
            
      item = pitem_new(seq64, frag);
      pq_64bit_free(&seq64);
      if ( item == NULL)
            {
            dtls1_hm_fragment_free(frag);
            return 0;
            }

#if 0
      fprintf( stderr, "buffered messge: \ttype = %xx\n", msg_buf->type);
      fprintf( stderr, "\t\t\t\t\tlen = %d\n", msg_buf->len);
      fprintf( stderr, "\t\t\t\t\tseq_num = %d\n", msg_buf->seq_num);
#endif

      pqueue_insert(s->d1->sent_messages, item);
      return 1;
      }

int
dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
      int *found)
      {
      int ret;
      /* XDTLS: for now assuming that read/writes are blocking */
      pitem *item;
      hm_fragment *frag ;
      unsigned long header_length;
      PQ_64BIT seq64;
      struct dtls1_retransmit_state saved_state;
      unsigned char save_write_sequence[8];

      /*
        OPENSSL_assert(s->init_num == 0);
        OPENSSL_assert(s->init_off == 0);
       */

      /* XDTLS:  the requested message ought to be found, otherwise error */
      pq_64bit_init(&seq64);
      pq_64bit_assign_word(&seq64, seq);

      item = pqueue_find(s->d1->sent_messages, seq64);
      pq_64bit_free(&seq64);
      if ( item == NULL)
            {
            fprintf(stderr, "retransmit:  message %d non-existant\n", seq);
            *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 = s->d1->w_epoch;
      saved_state.epoch = s->d1->w_epoch;
      
      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;
      s->d1->w_epoch = frag->msg_header.saved_retransmit_state.epoch;
      
      if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
      {
            memcpy(save_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
            memcpy(s->s3->write_sequence, s->d1->last_write_sequence, sizeof(s->s3->write_sequence));
      }
      
      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;
      s->d1->w_epoch = saved_state.epoch;
      
      if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
      {
            memcpy(s->d1->last_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
            memcpy(s->s3->write_sequence, save_write_sequence, sizeof(s->s3->write_sequence));
      }

      s->d1->retransmitting = 0;

      (void)BIO_flush(SSL_get_wbio(s));
      return ret;
      }

/* call this function when the buffered messages are no longer needed */
void
dtls1_clear_record_buffer(SSL *s)
      {
      pitem *item;

      for(item = pqueue_pop(s->d1->sent_messages);
            item != NULL; item = pqueue_pop(s->d1->sent_messages))
            {
            dtls1_hm_fragment_free((hm_fragment *)item->data);
            pitem_free(item);
            }
      }


unsigned char *
dtls1_set_message_header(SSL *s, unsigned char *p, unsigned char mt,
                  unsigned long len, unsigned long frag_off, unsigned long 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);

      return p += DTLS1_HM_HEADER_LENGTH;
      }


/* 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,
                      unsigned long len, unsigned short seq_num, unsigned long frag_off,
                      unsigned long 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, unsigned long frag_off,
                  unsigned long 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;
      }

static unsigned int 
dtls1_min_mtu(void)
      {
      return (g_probable_mtu[(sizeof(g_probable_mtu) / 
            sizeof(g_probable_mtu[0])) - 1]);
      }

static unsigned int 
dtls1_guess_mtu(unsigned int curr_mtu)
      {
      size_t i;

      if ( curr_mtu == 0 )
            return g_probable_mtu[0] ;

      for ( i = 0; i < sizeof(g_probable_mtu)/sizeof(g_probable_mtu[0]); i++)
            if ( curr_mtu > g_probable_mtu[i])
                  return g_probable_mtu[i];

      return curr_mtu;
      }

void
dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
      {
      memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
      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);
      }

void
dtls1_get_ccs_header(unsigned char *data, struct ccs_header_st *ccs_hdr)
      {
      memset(ccs_hdr, 0x00, sizeof(struct ccs_header_st));

      ccs_hdr->type = *(data++);
      }

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