ssl/d1_both.c

   1 /* ssl/d1_both.c */
   2 /*
   3  * DTLS implementation written by Nagendra Modadugu
   4  * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
   5  */
   6 /* ====================================================================
   7  * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  *
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in
  18  *    the documentation and/or other materials provided with the
  19  *    distribution.
  20  *
  21  * 3. All advertising materials mentioning features or use of this
  22  *    software must display the following acknowledgment:
  23  *    "This product includes software developed by the OpenSSL Project
  24  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  25  *
  26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  27  *    endorse or promote products derived from this software without
  28  *    prior written permission. For written permission, please contact
  29  *    openssl-core@openssl.org.
  30  *
  31  * 5. Products derived from this software may not be called "OpenSSL"
  32  *    nor may "OpenSSL" appear in their names without prior written
  33  *    permission of the OpenSSL Project.
  34  *
  35  * 6. Redistributions of any form whatsoever must retain the following
  36  *    acknowledgment:
  37  *    "This product includes software developed by the OpenSSL Project
  38  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  51  * OF THE POSSIBILITY OF SUCH DAMAGE.
  52  * ====================================================================
  53  *
  54  * This product includes cryptographic software written by Eric Young
  55  * (eay@cryptsoft.com).  This product includes software written by Tim
  56  * Hudson (tjh@cryptsoft.com).
  57  *
  58  */
  59 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  60  * All rights reserved.
  61  *
  62  * This package is an SSL implementation written
  63  * by Eric Young (eay@cryptsoft.com).
  64  * The implementation was written so as to conform with Netscapes SSL.
  65  *
  66  * This library is free for commercial and non-commercial use as long as
  67  * the following conditions are aheared to.  The following conditions
  68  * apply to all code found in this distribution, be it the RC4, RSA,
  69  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  70  * included with this distribution is covered by the same copyright terms
  71  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  72  *
  73  * Copyright remains Eric Young's, and as such any Copyright notices in
  74  * the code are not to be removed.
  75  * If this package is used in a product, Eric Young should be given attribution
  76  * as the author of the parts of the library used.
  77  * This can be in the form of a textual message at program startup or
  78  * in documentation (online or textual) provided with the package.
  79  *
  80  * Redistribution and use in source and binary forms, with or without
  81  * modification, are permitted provided that the following conditions
  82  * are met:
  83  * 1. Redistributions of source code must retain the copyright
  84  *    notice, this list of conditions and the following disclaimer.
  85  * 2. Redistributions in binary form must reproduce the above copyright
  86  *    notice, this list of conditions and the following disclaimer in the
  87  *    documentation and/or other materials provided with the distribution.
  88  * 3. All advertising materials mentioning features or use of this software
  89  *    must display the following acknowledgement:
  90  *    "This product includes cryptographic software written by
  91  *     Eric Young (eay@cryptsoft.com)"
  92  *    The word 'cryptographic' can be left out if the rouines from the library
  93  *    being used are not cryptographic related :-).
  94  * 4. If you include any Windows specific code (or a derivative thereof) from
  95  *    the apps directory (application code) you must include an acknowledgement:
  96  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  97  *
  98  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  99  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 100  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 101  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 102  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 103  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 104  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 105  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 106  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 107  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 108  * SUCH DAMAGE.
 109  *
 110  * The licence and distribution terms for any publically available version or
 111  * derivative of this code cannot be changed.  i.e. this code cannot simply be
 112  * copied and put under another distribution licence
 113  * [including the GNU Public Licence.]
 114  */
 115
 116 #include <limits.h>
 117 #include <string.h>
 118 #include <stdio.h>
 119 #include "ssl_locl.h"
 120 #include <openssl/buffer.h>
 121 #include <openssl/rand.h>
 122 #include <openssl/objects.h>
 123 #include <openssl/evp.h>
 124 #include <openssl/x509.h>
 125
 126
 127 /* XDTLS:  figure out the right values */
 128 static unsigned int g_probable_mtu[] = {1500 - 28, 512 - 28, 256 - 28};
 129
 130 static unsigned int dtls1_min_mtu(void);
 131 static unsigned int dtls1_guess_mtu(unsigned int curr_mtu);
 132 static void dtls1_fix_message_header(SSL *s, unsigned long frag_off,
 133         unsigned long frag_len);
 134 static unsigned char *dtls1_write_message_header(SSL *s,
 135         unsigned char *p);
 136 static void dtls1_set_message_header_int(SSL *s, unsigned char mt,
 137         unsigned long len, unsigned short seq_num, unsigned long frag_off,
 138         unsigned long frag_len);
 139 static long dtls1_get_message_fragment(SSL *s, int st1, int stn,
 140         long max, int *ok);
 141
 142 static hm_fragment *
 143 dtls1_hm_fragment_new(unsigned long frag_len)
 144         {
 145         hm_fragment *frag = NULL;
 146         unsigned char *buf = NULL;
 147
 148         frag = (hm_fragment *)OPENSSL_malloc(sizeof(hm_fragment));
 149         if ( frag == NULL)
 150                 return NULL;
 151
 152         if (frag_len)
 153                 {
 154                 buf = (unsigned char *)OPENSSL_malloc(frag_len);
 155                 if ( buf == NULL)
 156                         {
 157                         OPENSSL_free(frag);
 158                         return NULL;
 159                         }
 160                 }
 161
 162         /* zero length fragment gets zero frag->fragment */
 163         frag->fragment = buf;
 164
 165         return frag;
 166         }
 167
 168 static void
 169 dtls1_hm_fragment_free(hm_fragment *frag)
 170         {
 171         if (frag->fragment) OPENSSL_free(frag->fragment);
 172         OPENSSL_free(frag);
 173         }
 174
 175 /* send s->init_buf in records of type 'type' (SSL3_RT_HANDSHAKE or SSL3_RT_CHANGE_CIPHER_SPEC) */
 176 int dtls1_do_write(SSL *s, int type)
 177         {
 178         int ret;
 179         int curr_mtu;
 180         unsigned int len, frag_off, mac_size, blocksize;
 181
 182         /* AHA!  Figure out the MTU, and stick to the right size */
 183         if ( ! (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
 184                 {
 185                 s->d1->mtu =
 186                         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
 187
 188                 /* I've seen the kernel return bogus numbers when it doesn't know
 189                  * (initial write), so just make sure we have a reasonable number */
 190                 if ( s->d1->mtu < dtls1_min_mtu())
 191                         {
 192                         s->d1->mtu = 0;
 193                         s->d1->mtu = dtls1_guess_mtu(s->d1->mtu);
 194                         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
 195                                 s->d1->mtu, NULL);
 196                         }
 197                 }
 198 #if 0
 199         mtu = s->d1->mtu;
 200
 201         fprintf(stderr, "using MTU = %d\n", mtu);
 202
 203         mtu -= (DTLS1_HM_HEADER_LENGTH + DTLS1_RT_HEADER_LENGTH);
 204
 205         curr_mtu = mtu - BIO_wpending(SSL_get_wbio(s));
 206
 207         if ( curr_mtu > 0)
 208                 mtu = curr_mtu;
 209         else if ( ( ret = BIO_flush(SSL_get_wbio(s))) <= 0)
 210                 return ret;
 211
 212         if ( BIO_wpending(SSL_get_wbio(s)) + s->init_num >= mtu)
 213                 {
 214                 ret = BIO_flush(SSL_get_wbio(s));
 215                 if ( ret <= 0)
 216                         return ret;
 217                 mtu = s->d1->mtu - (DTLS1_HM_HEADER_LENGTH + DTLS1_RT_HEADER_LENGTH);
 218                 }
 219
 220         OPENSSL_assert(mtu > 0);  /* should have something reasonable now */
 221
 222 #endif
 223
 224         if ( s->init_off == 0  && type == SSL3_RT_HANDSHAKE)
 225                 OPENSSL_assert(s->init_num ==
 226                         (int)s->d1->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH);
 227
 228         if (s->write_hash)
 229                 mac_size = EVP_MD_size(s->write_hash);
 230         else
 231                 mac_size = 0;
 232
 233         if (s->enc_write_ctx &&
 234                 (EVP_CIPHER_mode( s->enc_write_ctx->cipher) & EVP_CIPH_CBC_MODE))
 235                 blocksize = 2 * EVP_CIPHER_block_size(s->enc_write_ctx->cipher);
 236         else
 237                 blocksize = 0;
 238
 239         frag_off = 0;
 240         while( s->init_num)
 241                 {
 242                 curr_mtu = s->d1->mtu - BIO_wpending(SSL_get_wbio(s)) -
 243                         DTLS1_RT_HEADER_LENGTH - mac_size - blocksize;
 244
 245                 if ( curr_mtu <= DTLS1_HM_HEADER_LENGTH)
 246                         {
 247                         /* grr.. we could get an error if MTU picked was wrong */
 248                         ret = BIO_flush(SSL_get_wbio(s));
 249                         if ( ret <= 0)
 250                                 return ret;
 251                         curr_mtu = s->d1->mtu - DTLS1_RT_HEADER_LENGTH -
 252                                 mac_size - blocksize;
 253                         }
 254
 255                 if ( s->init_num > curr_mtu)
 256                         len = curr_mtu;
 257                 else
 258                         len = s->init_num;
 259
 260
 261                 /* XDTLS: this function is too long.  split out the CCS part */
 262                 if ( type == SSL3_RT_HANDSHAKE)
 263                         {
 264                         if ( s->init_off != 0)
 265                                 {
 266                                 OPENSSL_assert(s->init_off > DTLS1_HM_HEADER_LENGTH);
 267                                 s->init_off -= DTLS1_HM_HEADER_LENGTH;
 268                                 s->init_num += DTLS1_HM_HEADER_LENGTH;
 269
 270                                 /* write atleast DTLS1_HM_HEADER_LENGTH bytes */
 271                                 if ( len <= DTLS1_HM_HEADER_LENGTH)
 272                                         len += DTLS1_HM_HEADER_LENGTH;
 273                                 }
 274
 275                         dtls1_fix_message_header(s, frag_off,
 276                                 len - DTLS1_HM_HEADER_LENGTH);
 277
 278                         dtls1_write_message_header(s, (unsigned char *)&s->init_buf->data[s->init_off]);
 279
 280                         OPENSSL_assert(len >= DTLS1_HM_HEADER_LENGTH);
 281                         }
 282
 283                 ret=dtls1_write_bytes(s,type,&s->init_buf->data[s->init_off],
 284                         len);
 285                 if (ret < 0)
 286                         {
 287                         /* might need to update MTU here, but we don't know
 288                          * which previous packet caused the failure -- so can't
 289                          * really retransmit anything.  continue as if everything
 290                          * is fine and wait for an alert to handle the
 291                          * retransmit
 292                          */
 293                         if ( BIO_ctrl(SSL_get_wbio(s),
 294                                 BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0 )
 295                                 s->d1->mtu = BIO_ctrl(SSL_get_wbio(s),
 296                                         BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
 297                         else
 298                                 return(-1);
 299                         }
 300                 else
 301                         {
 302
 303                         /* bad if this assert fails, only part of the handshake
 304                          * message got sent.  but why would this happen? */
 305                         OPENSSL_assert(len == (unsigned int)ret);
 306
 307                         if (type == SSL3_RT_HANDSHAKE && ! s->d1->retransmitting)
 308                                 {
 309                                 /* should not be done for 'Hello Request's, but in that case
 310                                  * we'll ignore the result anyway */
 311                                 unsigned char *p = (unsigned char *)&s->init_buf->data[s->init_off];
 312                                 const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
 313                                 int xlen;
 314
 315                                 if (frag_off == 0 && s->client_version != DTLS1_BAD_VER)
 316                                         {
 317                                         /* reconstruct message header is if it
 318                                          * is being sent in single fragment */
 319                                         *p++ = msg_hdr->type;
 320                                         l2n3(msg_hdr->msg_len,p);
 321                                         s2n (msg_hdr->seq,p);
 322                                         l2n3(0,p);
 323                                         l2n3(msg_hdr->msg_len,p);
 324                                         p  -= DTLS1_HM_HEADER_LENGTH;
 325                                         xlen = ret;
 326                                         }
 327                                 else
 328                                         {
 329                                         p  += DTLS1_HM_HEADER_LENGTH;
 330                                         xlen = ret - DTLS1_HM_HEADER_LENGTH;
 331                                         }
 332
 333                                 ssl3_finish_mac(s, p, xlen);
 334                                 }
 335
 336                         if (ret == s->init_num)
 337                                 {
 338                                 if (s->msg_callback)
 339                                         s->msg_callback(1, s->version, type, s->init_buf->data,
 340                                                 (size_t)(s->init_off + s->init_num), s,
 341                                                 s->msg_callback_arg);
 342
 343                                 s->init_off = 0;  /* done writing this message */
 344                                 s->init_num = 0;
 345
 346                                 return(1);
 347                                 }
 348                         s->init_off+=ret;
 349                         s->init_num-=ret;
 350                         frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
 351                         }
 352                 }
 353         return(0);
 354         }
 355
 356
 357 /* Obtain handshake message of message type 'mt' (any if mt == -1),
 358  * maximum acceptable body length 'max'.
 359  * Read an entire handshake message.  Handshake messages arrive in
 360  * fragments.
 361  */
 362 long dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
 363         {
 364         int i, al;
 365         struct hm_header_st *msg_hdr;
 366
 367         /* s3->tmp is used to store messages that are unexpected, caused
 368          * by the absence of an optional handshake message */
 369         if (s->s3->tmp.reuse_message)
 370                 {
 371                 s->s3->tmp.reuse_message=0;
 372                 if ((mt >= 0) && (s->s3->tmp.message_type != mt))
 373                         {
 374                         al=SSL_AD_UNEXPECTED_MESSAGE;
 375                         SSLerr(SSL_F_DTLS1_GET_MESSAGE,SSL_R_UNEXPECTED_MESSAGE);
 376                         goto f_err;
 377                         }
 378                 *ok=1;
 379                 s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
 380                 s->init_num = (int)s->s3->tmp.message_size;
 381                 return s->init_num;
 382                 }
 383
 384         msg_hdr = &s->d1->r_msg_hdr;
 385         do
 386                 {
 387                 if ( msg_hdr->frag_off == 0)
 388                         {
 389                         /* s->d1->r_message_header.msg_len = 0; */
 390                         memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
 391                         }
 392
 393                 i = dtls1_get_message_fragment(s, st1, stn, max, ok);
 394                 if ( i == DTLS1_HM_BAD_FRAGMENT ||
 395                         i == DTLS1_HM_FRAGMENT_RETRY)  /* bad fragment received */
 396                         continue;
 397                 else if ( i <= 0 && !*ok)
 398                         return i;
 399
 400                 /* Note that s->init_sum is used as a counter summing
 401                  * up fragments' lengths: as soon as they sum up to
 402                  * handshake packet length, we assume we have got all
 403                  * the fragments. Overlapping fragments would cause
 404                  * premature termination, so we don't expect overlaps.
 405                  * Well, handling overlaps would require something more
 406                  * drastic. Indeed, as it is now there is no way to
 407                  * tell if out-of-order fragment from the middle was
 408                  * the last. '>=' is the best/least we can do to control
 409                  * the potential damage caused by malformed overlaps. */
 410                 if ((unsigned int)s->init_num >= msg_hdr->msg_len)
 411                         {
 412                         unsigned char *p = (unsigned char *)s->init_buf->data;
 413                         unsigned long msg_len = msg_hdr->msg_len;
 414
 415                         /* reconstruct message header as if it was
 416                          * sent in single fragment */
 417                         *(p++) = msg_hdr->type;
 418                         l2n3(msg_len,p);
 419                         s2n (msg_hdr->seq,p);
 420                         l2n3(0,p);
 421                         l2n3(msg_len,p);
 422                         if (s->client_version != DTLS1_BAD_VER)
 423                                 p       -= DTLS1_HM_HEADER_LENGTH,
 424                                 msg_len += DTLS1_HM_HEADER_LENGTH;
 425
 426                         ssl3_finish_mac(s, p, msg_len);
 427                         if (s->msg_callback)
 428                                 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
 429                                         p, msg_len,
 430                                         s, s->msg_callback_arg);
 431
 432                         memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
 433
 434                         s->d1->handshake_read_seq++;
 435                         /* we just read a handshake message from the other side:
 436                          * this means that we don't need to retransmit of the
 437                          * buffered messages.
 438                          * XDTLS: may be able clear out this
 439                          * buffer a little sooner (i.e if an out-of-order
 440                          * handshake message/record is received at the record
 441                          * layer.
 442                          * XDTLS: exception is that the server needs to
 443                          * know that change cipher spec and finished messages
 444                          * have been received by the client before clearing this
 445                          * buffer.  this can simply be done by waiting for the
 446                          * first data  segment, but is there a better way?  */
 447                         dtls1_clear_record_buffer(s);
 448
 449                         s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
 450                         return s->init_num;
 451                         }
 452                 else
 453                         msg_hdr->frag_off = i;
 454                 } while(1) ;
 455
 456 f_err:
 457         ssl3_send_alert(s,SSL3_AL_FATAL,al);
 458         *ok = 0;
 459         return -1;
 460         }
 461
 462
 463 static int dtls1_preprocess_fragment(SSL *s,struct hm_header_st *msg_hdr,int max)
 464         {
 465         size_t frag_off,frag_len,msg_len;
 466
 467         msg_len  = msg_hdr->msg_len;
 468         frag_off = msg_hdr->frag_off;
 469         frag_len = msg_hdr->frag_len;
 470
 471         /* sanity checking */
 472         if ( (frag_off+frag_len) > msg_len)
 473                 {
 474                 SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
 475                 return SSL_AD_ILLEGAL_PARAMETER;
 476                 }
 477
 478         if ( (frag_off+frag_len) > (unsigned long)max)
 479                 {
 480                 SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
 481                 return SSL_AD_ILLEGAL_PARAMETER;
 482                 }
 483
 484         if ( s->d1->r_msg_hdr.frag_off == 0) /* first fragment */
 485                 {
 486                 /* msg_len is limited to 2^24, but is effectively checked
 487                  * against max above */
 488                 if (!BUF_MEM_grow_clean(s->init_buf,(int)msg_len+DTLS1_HM_HEADER_LENGTH))
 489                         {
 490                         SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,ERR_R_BUF_LIB);
 491                         return SSL_AD_INTERNAL_ERROR;
 492                         }
 493
 494                 s->s3->tmp.message_size  = msg_len;
 495                 s->d1->r_msg_hdr.msg_len = msg_len;
 496                 s->s3->tmp.message_type  = msg_hdr->type;
 497                 s->d1->r_msg_hdr.type    = msg_hdr->type;
 498                 s->d1->r_msg_hdr.seq     = msg_hdr->seq;
 499                 }
 500         else if (msg_len != s->d1->r_msg_hdr.msg_len)
 501                 {
 502                 /* They must be playing with us! BTW, failure to enforce
 503                  * upper limit would open possibility for buffer overrun. */
 504                 SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
 505                 return SSL_AD_ILLEGAL_PARAMETER;
 506                 }
 507
 508         return 0; /* no error */
 509         }
 510
 511
 512 static int
 513 dtls1_retrieve_buffered_fragment(SSL *s, long max, int *ok)
 514         {
 515         /* (0) check whether the desired fragment is available
 516          * if so:
 517          * (1) copy over the fragment to s->init_buf->data[]
 518          * (2) update s->init_num
 519          */
 520         pitem *item;
 521         hm_fragment *frag;
 522         int al;
 523
 524         *ok = 0;
 525         item = pqueue_peek(s->d1->buffered_messages);
 526         if ( item == NULL)
 527                 return 0;
 528
 529         frag = (hm_fragment *)item->data;
 530
 531         if ( s->d1->handshake_read_seq == frag->msg_header.seq)
 532                 {
 533                 unsigned long frag_len = frag->msg_header.frag_len;
 534                 pqueue_pop(s->d1->buffered_messages);
 535
 536                 al=dtls1_preprocess_fragment(s,&frag->msg_header,max);
 537
 538                 if (al==0) /* no alert */
 539                         {
 540                         unsigned char *p = (unsigned char *)s->init_buf->data+DTLS1_HM_HEADER_LENGTH;
 541                         memcpy(&p[frag->msg_header.frag_off],
 542                                 frag->fragment,frag->msg_header.frag_len);
 543                         }
 544
 545                 dtls1_hm_fragment_free(frag);
 546                 pitem_free(item);
 547
 548                 if (al==0)
 549                         {
 550                         *ok = 1;
 551                         return frag_len;
 552                         }
 553
 554                 ssl3_send_alert(s,SSL3_AL_FATAL,al);
 555                 s->init_num = 0;
 556                 *ok = 0;
 557                 return -1;
 558                 }
 559         else
 560                 return 0;
 561         }
 562
 563
 564 static int
 565 dtls1_process_out_of_seq_message(SSL *s, struct hm_header_st* msg_hdr, int *ok)
 566 {
 567         int i=-1;
 568         hm_fragment *frag = NULL;
 569         pitem *item = NULL;
 570         PQ_64BIT seq64;
 571         unsigned long frag_len = msg_hdr->frag_len;
 572
 573         if ((msg_hdr->frag_off+frag_len) > msg_hdr->msg_len)
 574                 goto err;
 575
 576         /* Try to find item in queue, to prevent duplicate entries */
 577         pq_64bit_init(&seq64);
 578         pq_64bit_assign_word(&seq64, msg_hdr->seq);
 579         item = pqueue_find(s->d1->buffered_messages, seq64);
 580         pq_64bit_free(&seq64);
 581
 582         /* Discard the message if sequence number was already there, is
 583          * too far in the future, already in the queue or if we received
 584          * a FINISHED before the SERVER_HELLO, which then must be a stale
 585          * retransmit.
 586          */
 587         if (msg_hdr->seq <= s->d1->handshake_read_seq ||
 588                 msg_hdr->seq > s->d1->handshake_read_seq + 10 || item != NULL ||
 589                 (s->d1->handshake_read_seq == 0 && msg_hdr->type == SSL3_MT_FINISHED))
 590                 {
 591                 unsigned char devnull [256];
 592
 593                 while (frag_len)
 594                         {
 595                         i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
 596                                 devnull,
 597                                 frag_len>sizeof(devnull)?sizeof(devnull):frag_len,0);
 598                         if (i<=0) goto err;
 599                         frag_len -= i;
 600                         }
 601                 }
 602
 603         if (frag_len)
 604         {
 605                 frag = dtls1_hm_fragment_new(frag_len);
 606                 if ( frag == NULL)
 607                         goto err;
 608
 609                 memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
 610
 611                 /* read the body of the fragment (header has already been read) */
 612                 i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
 613                         frag->fragment,frag_len,0);
 614                 if (i<=0 || (unsigned long)i!=frag_len)
 615                         goto err;
 616
 617                 pq_64bit_init(&seq64);
 618                 pq_64bit_assign_word(&seq64, msg_hdr->seq);
 619
 620                 item = pitem_new(seq64, frag);
 621                 pq_64bit_free(&seq64);
 622                 if ( item == NULL)
 623                         goto err;
 624
 625                 pqueue_insert(s->d1->buffered_messages, item);
 626         }
 627
 628         return DTLS1_HM_FRAGMENT_RETRY;
 629
 630 err:
 631         if ( frag != NULL) dtls1_hm_fragment_free(frag);
 632         if ( item != NULL) OPENSSL_free(item);
 633         *ok = 0;
 634         return i;
 635         }
 636
 637
 638 static long
 639 dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
 640         {
 641         unsigned char wire[DTLS1_HM_HEADER_LENGTH];
 642         unsigned long l, frag_off, frag_len;
 643         int i,al;
 644         struct hm_header_st msg_hdr;
 645
 646         /* see if we have the required fragment already */
 647         if ((frag_len = dtls1_retrieve_buffered_fragment(s,max,ok)) || *ok)
 648                 {
 649                 if (*ok)        s->init_num += frag_len;
 650                 return frag_len;
 651                 }
 652
 653         /* read handshake message header */
 654         i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,wire,
 655                 DTLS1_HM_HEADER_LENGTH, 0);
 656         if (i <= 0)     /* nbio, or an error */
 657                 {
 658                 s->rwstate=SSL_READING;
 659                 *ok = 0;
 660                 return i;
 661                 }
 662         OPENSSL_assert(i == DTLS1_HM_HEADER_LENGTH);
 663
 664         /* parse the message fragment header */
 665         dtls1_get_message_header(wire, &msg_hdr);
 666
 667         /*
 668          * if this is a future (or stale) message it gets buffered
 669          * (or dropped)--no further processing at this time
 670          */
 671         if ( msg_hdr.seq != s->d1->handshake_read_seq)
 672                 return dtls1_process_out_of_seq_message(s, &msg_hdr, ok);
 673
 674         l = msg_hdr.msg_len;
 675         frag_off = msg_hdr.frag_off;
 676         frag_len = msg_hdr.frag_len;
 677
 678         if (!s->server && s->d1->r_msg_hdr.frag_off == 0 &&
 679                 wire[0] == SSL3_MT_HELLO_REQUEST)
 680                 {
 681                 /* The server may always send 'Hello Request' messages --
 682                  * we are doing a handshake anyway now, so ignore them
 683                  * if their format is correct. Does not count for
 684                  * 'Finished' MAC. */
 685                 if (wire[1] == 0 && wire[2] == 0 && wire[3] == 0)
 686                         {
 687                         if (s->msg_callback)
 688                                 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
 689                                         wire, DTLS1_HM_HEADER_LENGTH, s,
 690                                         s->msg_callback_arg);
 691
 692                         s->init_num = 0;
 693                         return dtls1_get_message_fragment(s, st1, stn,
 694                                 max, ok);
 695                         }
 696                 else /* Incorrectly formated Hello request */
 697                         {
 698                         al=SSL_AD_UNEXPECTED_MESSAGE;
 699                         SSLerr(SSL_F_DTLS1_GET_MESSAGE_FRAGMENT,SSL_R_UNEXPECTED_MESSAGE);
 700                         goto f_err;
 701                         }
 702                 }
 703
 704         if ((al=dtls1_preprocess_fragment(s,&msg_hdr,max)))
 705                 goto f_err;
 706
 707         /* XDTLS:  ressurect this when restart is in place */
 708         s->state=stn;
 709
 710         if ( frag_len > 0)
 711                 {
 712                 unsigned char *p=(unsigned char *)s->init_buf->data+DTLS1_HM_HEADER_LENGTH;
 713
 714                 i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
 715                         &p[frag_off],frag_len,0);
 716                 /* XDTLS:  fix this--message fragments cannot span multiple packets */
 717                 if (i <= 0)
 718                         {
 719                         s->rwstate=SSL_READING;
 720                         *ok = 0;
 721                         return i;
 722                         }
 723                 }
 724         else
 725                 i = 0;
 726
 727         /* XDTLS:  an incorrectly formatted fragment should cause the
 728          * handshake to fail */
 729         OPENSSL_assert(i == (int)frag_len);
 730
 731         *ok = 1;
 732
 733         /* Note that s->init_num is *not* used as current offset in
 734          * s->init_buf->data, but as a counter summing up fragments'
 735          * lengths: as soon as they sum up to handshake packet
 736          * length, we assume we have got all the fragments. */
 737         s->init_num += frag_len;
 738         return frag_len;
 739
 740 f_err:
 741         ssl3_send_alert(s,SSL3_AL_FATAL,al);
 742         s->init_num = 0;
 743
 744         *ok=0;
 745         return(-1);
 746         }
 747
 748 int dtls1_send_finished(SSL *s, int a, int b, const char *sender, int slen)
 749         {
 750         unsigned char *p,*d;
 751         int i;
 752         unsigned long l;
 753
 754         if (s->state == a)
 755                 {
 756                 d=(unsigned char *)s->init_buf->data;
 757                 p= &(d[DTLS1_HM_HEADER_LENGTH]);
 758
 759                 i=s->method->ssl3_enc->final_finish_mac(s,
 760                         &(s->s3->finish_dgst1),
 761                         &(s->s3->finish_dgst2),
 762                         sender,slen,s->s3->tmp.finish_md);
 763                 s->s3->tmp.finish_md_len = i;
 764                 memcpy(p, s->s3->tmp.finish_md, i);
 765                 p+=i;
 766                 l=i;
 767
 768 #ifdef OPENSSL_SYS_WIN16
 769                 /* MSVC 1.5 does not clear the top bytes of the word unless
 770                  * I do this.
 771                  */
 772                 l&=0xffff;
 773 #endif
 774
 775                 d = dtls1_set_message_header(s, d, SSL3_MT_FINISHED, l, 0, l);
 776                 s->init_num=(int)l+DTLS1_HM_HEADER_LENGTH;
 777                 s->init_off=0;
 778
 779                 /* buffer the message to handle re-xmits */
 780                 dtls1_buffer_message(s, 0);
 781
 782                 s->state=b;
 783                 }
 784
 785         /* SSL3_ST_SEND_xxxxxx_HELLO_B */
 786         return(dtls1_do_write(s,SSL3_RT_HANDSHAKE));
 787         }
 788
 789 /* for these 2 messages, we need to
 790  * ssl->enc_read_ctx                    re-init
 791  * ssl->s3->read_sequence               zero
 792  * ssl->s3->read_mac_secret             re-init
 793  * ssl->session->read_sym_enc           assign
 794  * ssl->session->read_compression       assign
 795  * ssl->session->read_hash              assign
 796  */
 797 int dtls1_send_change_cipher_spec(SSL *s, int a, int b)
 798         {
 799         unsigned char *p;
 800
 801         if (s->state == a)
 802                 {
 803                 p=(unsigned char *)s->init_buf->data;
 804                 *p++=SSL3_MT_CCS;
 805                 s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
 806                 s->init_num=DTLS1_CCS_HEADER_LENGTH;
 807
 808                 if (s->client_version == DTLS1_BAD_VER)
 809                         {
 810                         s->d1->next_handshake_write_seq++;
 811                         s2n(s->d1->handshake_write_seq,p);
 812                         s->init_num+=2;
 813                         }
 814
 815                 s->init_off=0;
 816
 817                 dtls1_set_message_header_int(s, SSL3_MT_CCS, 0,
 818                         s->d1->handshake_write_seq, 0, 0);
 819
 820                 /* buffer the message to handle re-xmits */
 821                 dtls1_buffer_message(s, 1);
 822
 823                 s->state=b;
 824                 }
 825
 826         /* SSL3_ST_CW_CHANGE_B */
 827         return(dtls1_do_write(s,SSL3_RT_CHANGE_CIPHER_SPEC));
 828         }
 829
 830 static int dtls1_add_cert_to_buf(BUF_MEM *buf, unsigned long *l, X509 *x)
 831         {
 832                 int n;
 833                 unsigned char *p;
 834
 835                 n=i2d_X509(x,NULL);
 836                 if (!BUF_MEM_grow_clean(buf,(int)(n+(*l)+3)))
 837                         {
 838                         SSLerr(SSL_F_DTLS1_ADD_CERT_TO_BUF,ERR_R_BUF_LIB);
 839                         return 0;
 840                         }
 841                 p=(unsigned char *)&(buf->data[*l]);
 842                 l2n3(n,p);
 843                 i2d_X509(x,&p);
 844                 *l+=n+3;
 845
 846                 return 1;
 847         }
 848 unsigned long dtls1_output_cert_chain(SSL *s, X509 *x)
 849         {
 850         unsigned char *p;
 851         int i;
 852         unsigned long l= 3 + DTLS1_HM_HEADER_LENGTH;
 853         BUF_MEM *buf;
 854
 855         /* TLSv1 sends a chain with nothing in it, instead of an alert */
 856         buf=s->init_buf;
 857         if (!BUF_MEM_grow_clean(buf,10))
 858                 {
 859                 SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_BUF_LIB);
 860                 return(0);
 861                 }
 862         if (x != NULL)
 863                 {
 864                 X509_STORE_CTX xs_ctx;
 865
 866                 if (!X509_STORE_CTX_init(&xs_ctx,s->ctx->cert_store,x,NULL))
 867                         {
 868                         SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_X509_LIB);
 869                         return(0);
 870                         }
 871
 872                 X509_verify_cert(&xs_ctx);
 873                 for (i=0; i < sk_X509_num(xs_ctx.chain); i++)
 874                         {
 875                         x = sk_X509_value(xs_ctx.chain, i);
 876
 877                         if (!dtls1_add_cert_to_buf(buf, &l, x))
 878                                 {
 879                                 X509_STORE_CTX_cleanup(&xs_ctx);
 880                                 return 0;
 881                                 }
 882                         }
 883                 X509_STORE_CTX_cleanup(&xs_ctx);
 884                 }
 885         /* Thawte special :-) */
 886         for (i=0; i<sk_X509_num(s->ctx->extra_certs); i++)
 887                 {
 888                 x=sk_X509_value(s->ctx->extra_certs,i);
 889                 if (!dtls1_add_cert_to_buf(buf, &l, x))
 890                         return 0;
 891                 }
 892
 893         l-= (3 + DTLS1_HM_HEADER_LENGTH);
 894
 895         p=(unsigned char *)&(buf->data[DTLS1_HM_HEADER_LENGTH]);
 896         l2n3(l,p);
 897         l+=3;
 898         p=(unsigned char *)&(buf->data[0]);
 899         p = dtls1_set_message_header(s, p, SSL3_MT_CERTIFICATE, l, 0, l);
 900
 901         l+=DTLS1_HM_HEADER_LENGTH;
 902         return(l);
 903         }
 904
 905 int dtls1_read_failed(SSL *s, int code)
 906         {
 907         if ( code > 0)
 908                 {
 909                 fprintf( stderr, "invalid state reached %s:%d", __FILE__, __LINE__);
 910                 return 1;
 911                 }
 912
 913         if (!dtls1_is_timer_expired(s))
 914                 {
 915                 /* not a timeout, none of our business,
 916                    let higher layers handle this.  in fact it's probably an error */
 917                 return code;
 918                 }
 919
 920         if ( ! SSL_in_init(s))  /* done, no need to send a retransmit */
 921                 {
 922                 BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
 923                 return code;
 924                 }
 925
 926 #if 0 /* for now, each alert contains only one record number */
 927         item = pqueue_peek(state->rcvd_records);
 928         if ( item )
 929                 {
 930                 /* send an alert immediately for all the missing records */
 931                 }
 932         else
 933 #endif
 934
 935 #if 0  /* no more alert sending, just retransmit the last set of messages */
 936         if ( state->timeout.read_timeouts >= DTLS1_TMO_READ_COUNT)
 937                 ssl3_send_alert(s,SSL3_AL_WARNING,
 938                         DTLS1_AD_MISSING_HANDSHAKE_MESSAGE);
 939 #endif
 940
 941         return dtls1_handle_timeout(s);
 942         }
 943
 944 int
 945 dtls1_get_queue_priority(unsigned short seq, int is_ccs)
 946         {
 947         /* The index of the retransmission queue actually is the message sequence number,
 948          * since the queue only contains messages of a single handshake. However, the
 949          * ChangeCipherSpec has no message sequence number and so using only the sequence
 950          * will result in the CCS and Finished having the same index. To prevent this,
 951          * the sequence number is multiplied by 2. In case of a CCS 1 is subtracted.
 952          * This does not only differ CSS and Finished, it also maintains the order of the
 953          * index (important for priority queues) and fits in the unsigned short variable.
 954          */
 955         return seq * 2 - is_ccs;
 956         }
 957
 958 int
 959 dtls1_retransmit_buffered_messages(SSL *s)
 960         {
 961         pqueue sent = s->d1->sent_messages;
 962         piterator iter;
 963         pitem *item;
 964         hm_fragment *frag;
 965         int found = 0;
 966
 967         iter = pqueue_iterator(sent);
 968
 969         for ( item = pqueue_next(&iter); item != NULL; item = pqueue_next(&iter))
 970                 {
 971                 frag = (hm_fragment *)item->data;
 972                         if ( dtls1_retransmit_message(s,
 973                                 dtls1_get_queue_priority(frag->msg_header.seq, frag->msg_header.is_ccs),
 974                                 0, &found) <= 0 && found)
 975                         {
 976                         fprintf(stderr, "dtls1_retransmit_message() failed\n");
 977                         return -1;
 978                         }
 979                 }
 980
 981         return 1;
 982         }
 983
 984 int
 985 dtls1_buffer_message(SSL *s, int is_ccs)
 986         {
 987         pitem *item;
 988         hm_fragment *frag;
 989         PQ_64BIT seq64;
 990
 991         /* this function is called immediately after a message has
 992          * been serialized */
 993         OPENSSL_assert(s->init_off == 0);
 994
 995         frag = dtls1_hm_fragment_new(s->init_num);
 996
 997         memcpy(frag->fragment, s->init_buf->data, s->init_num);
 998
 999         if ( is_ccs)
1000                 {
1001                 OPENSSL_assert(s->d1->w_msg_hdr.msg_len +
1002                         DTLS1_CCS_HEADER_LENGTH <= (unsigned int)s->init_num);
1003                 }
1004         else
1005                 {
1006                 OPENSSL_assert(s->d1->w_msg_hdr.msg_len +
1007                         DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num);
1008                 }
1009
1010         frag->msg_header.msg_len = s->d1->w_msg_hdr.msg_len;
1011         frag->msg_header.seq = s->d1->w_msg_hdr.seq;
1012         frag->msg_header.type = s->d1->w_msg_hdr.type;
1013         frag->msg_header.frag_off = 0;
1014         frag->msg_header.frag_len = s->d1->w_msg_hdr.msg_len;
1015         frag->msg_header.is_ccs = is_ccs;
1016
1017         /* save current state*/
1018         frag->msg_header.saved_retransmit_state.enc_write_ctx = s->enc_write_ctx;
1019         frag->msg_header.saved_retransmit_state.write_hash = s->write_hash;
1020         frag->msg_header.saved_retransmit_state.compress = s->compress;
1021         frag->msg_header.saved_retransmit_state.session = s->session;
1022         frag->msg_header.saved_retransmit_state.epoch = s->d1->w_epoch;
1023
1024         pq_64bit_init(&seq64);
1025
1026         pq_64bit_assign_word(&seq64,
1027                                                  dtls1_get_queue_priority(frag->msg_header.seq,
1028                                                                                                   frag->msg_header.is_ccs));
1029
1030         item = pitem_new(seq64, frag);
1031         pq_64bit_free(&seq64);
1032         if ( item == NULL)
1033                 {
1034                 dtls1_hm_fragment_free(frag);
1035                 return 0;
1036                 }
1037
1038 #if 0
1039         fprintf( stderr, "buffered messge: \ttype = %xx\n", msg_buf->type);
1040         fprintf( stderr, "\t\t\t\t\tlen = %d\n", msg_buf->len);
1041         fprintf( stderr, "\t\t\t\t\tseq_num = %d\n", msg_buf->seq_num);
1042 #endif
1043
1044         pqueue_insert(s->d1->sent_messages, item);
1045         return 1;
1046         }
1047
1048 int
1049 dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
1050         int *found)
1051         {
1052         int ret;
1053         /* XDTLS: for now assuming that read/writes are blocking */
1054         pitem *item;
1055         hm_fragment *frag ;
1056         unsigned long header_length;
1057         PQ_64BIT seq64;
1058         struct dtls1_retransmit_state saved_state;
1059         unsigned char save_write_sequence[8];
1060
1061         /*
1062           OPENSSL_assert(s->init_num == 0);
1063           OPENSSL_assert(s->init_off == 0);
1064          */
1065
1066         /* XDTLS:  the requested message ought to be found, otherwise error */
1067         pq_64bit_init(&seq64);
1068         pq_64bit_assign_word(&seq64, seq);
1069
1070         item = pqueue_find(s->d1->sent_messages, seq64);
1071         pq_64bit_free(&seq64);
1072         if ( item == NULL)
1073                 {
1074                 fprintf(stderr, "retransmit:  message %d non-existant\n", seq);
1075                 *found = 0;
1076                 return 0;
1077                 }
1078
1079         *found = 1;
1080         frag = (hm_fragment *)item->data;
1081
1082         if ( frag->msg_header.is_ccs)
1083                 header_length = DTLS1_CCS_HEADER_LENGTH;
1084         else
1085                 header_length = DTLS1_HM_HEADER_LENGTH;
1086
1087         memcpy(s->init_buf->data, frag->fragment,
1088                 frag->msg_header.msg_len + header_length);
1089                 s->init_num = frag->msg_header.msg_len + header_length;
1090
1091         dtls1_set_message_header_int(s, frag->msg_header.type,
1092                 frag->msg_header.msg_len, frag->msg_header.seq, 0,
1093                 frag->msg_header.frag_len);
1094
1095         /* save current state */
1096         saved_state.enc_write_ctx = s->enc_write_ctx;
1097         saved_state.write_hash = s->write_hash;
1098         saved_state.compress = s->compress;
1099         saved_state.session = s->session;
1100         saved_state.epoch = s->d1->w_epoch;
1101         saved_state.epoch = s->d1->w_epoch;
1102
1103         s->d1->retransmitting = 1;
1104
1105         /* restore state in which the message was originally sent */
1106         s->enc_write_ctx = frag->msg_header.saved_retransmit_state.enc_write_ctx;
1107         s->write_hash = frag->msg_header.saved_retransmit_state.write_hash;
1108         s->compress = frag->msg_header.saved_retransmit_state.compress;
1109         s->session = frag->msg_header.saved_retransmit_state.session;
1110         s->d1->w_epoch = frag->msg_header.saved_retransmit_state.epoch;
1111
1112         if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
1113         {
1114                 memcpy(save_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
1115                 memcpy(s->s3->write_sequence, s->d1->last_write_sequence, sizeof(s->s3->write_sequence));
1116         }
1117
1118         ret = dtls1_do_write(s, frag->msg_header.is_ccs ?
1119                                                  SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
1120
1121         /* restore current state */
1122         s->enc_write_ctx = saved_state.enc_write_ctx;
1123         s->write_hash = saved_state.write_hash;
1124         s->compress = saved_state.compress;
1125         s->session = saved_state.session;
1126         s->d1->w_epoch = saved_state.epoch;
1127
1128         if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
1129         {
1130                 memcpy(s->d1->last_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
1131                 memcpy(s->s3->write_sequence, save_write_sequence, sizeof(s->s3->write_sequence));
1132         }
1133
1134         s->d1->retransmitting = 0;
1135
1136         (void)BIO_flush(SSL_get_wbio(s));
1137         return ret;
1138         }
1139
1140 /* call this function when the buffered messages are no longer needed */
1141 void
1142 dtls1_clear_record_buffer(SSL *s)
1143         {
1144         pitem *item;
1145
1146         for(item = pqueue_pop(s->d1->sent_messages);
1147                 item != NULL; item = pqueue_pop(s->d1->sent_messages))
1148                 {
1149                 dtls1_hm_fragment_free((hm_fragment *)item->data);
1150                 pitem_free(item);
1151                 }
1152         }
1153
1154
1155 unsigned char *
1156 dtls1_set_message_header(SSL *s, unsigned char *p, unsigned char mt,
1157                         unsigned long len, unsigned long frag_off, unsigned long frag_len)
1158         {
1159         if ( frag_off == 0)
1160                 {
1161                 s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
1162                 s->d1->next_handshake_write_seq++;
1163                 }
1164
1165         dtls1_set_message_header_int(s, mt, len, s->d1->handshake_write_seq,
1166                 frag_off, frag_len);
1167
1168         return p += DTLS1_HM_HEADER_LENGTH;
1169         }
1170
1171
1172 /* don't actually do the writing, wait till the MTU has been retrieved */
1173 static void
1174 dtls1_set_message_header_int(SSL *s, unsigned char mt,
1175                             unsigned long len, unsigned short seq_num, unsigned long frag_off,
1176                             unsigned long frag_len)
1177         {
1178         struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
1179
1180         msg_hdr->type = mt;
1181         msg_hdr->msg_len = len;
1182         msg_hdr->seq = seq_num;
1183         msg_hdr->frag_off = frag_off;
1184         msg_hdr->frag_len = frag_len;
1185         }
1186
1187 static void
1188 dtls1_fix_message_header(SSL *s, unsigned long frag_off,
1189                         unsigned long frag_len)
1190         {
1191         struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
1192
1193         msg_hdr->frag_off = frag_off;
1194         msg_hdr->frag_len = frag_len;
1195         }
1196
1197 static unsigned char *
1198 dtls1_write_message_header(SSL *s, unsigned char *p)
1199         {
1200         struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
1201
1202         *p++ = msg_hdr->type;
1203         l2n3(msg_hdr->msg_len, p);
1204
1205         s2n(msg_hdr->seq, p);
1206         l2n3(msg_hdr->frag_off, p);
1207         l2n3(msg_hdr->frag_len, p);
1208
1209         return p;
1210         }
1211
1212 static unsigned int
1213 dtls1_min_mtu(void)
1214         {
1215         return (g_probable_mtu[(sizeof(g_probable_mtu) /
1216                 sizeof(g_probable_mtu[0])) - 1]);
1217         }
1218
1219 static unsigned int
1220 dtls1_guess_mtu(unsigned int curr_mtu)
1221         {
1222         size_t i;
1223
1224         if ( curr_mtu == 0 )
1225                 return g_probable_mtu[0] ;
1226
1227         for ( i = 0; i < sizeof(g_probable_mtu)/sizeof(g_probable_mtu[0]); i++)
1228                 if ( curr_mtu > g_probable_mtu[i])
1229                         return g_probable_mtu[i];
1230
1231         return curr_mtu;
1232         }
1233
1234 void
1235 dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
1236         {
1237         memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
1238         msg_hdr->type = *(data++);
1239         n2l3(data, msg_hdr->msg_len);
1240
1241         n2s(data, msg_hdr->seq);
1242         n2l3(data, msg_hdr->frag_off);
1243         n2l3(data, msg_hdr->frag_len);
1244         }
1245
1246 void
1247 dtls1_get_ccs_header(unsigned char *data, struct ccs_header_st *ccs_hdr)
1248         {
1249         memset(ccs_hdr, 0x00, sizeof(struct ccs_header_st));
1250
1251         ccs_hdr->type = *(data++);
1252         }