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;
 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         frag_off = 0;
 229         while( s->init_num)
 230                 {
 231                 curr_mtu = s->d1->mtu - BIO_wpending(SSL_get_wbio(s)) -
 232                         DTLS1_RT_HEADER_LENGTH;
 233
 234                 if ( curr_mtu <= DTLS1_HM_HEADER_LENGTH)
 235                         {
 236                         /* grr.. we could get an error if MTU picked was wrong */
 237                         ret = BIO_flush(SSL_get_wbio(s));
 238                         if ( ret <= 0)
 239                                 return ret;
 240                         curr_mtu = s->d1->mtu - DTLS1_RT_HEADER_LENGTH;
 241                         }
 242
 243                 if ( s->init_num > curr_mtu)
 244                         len = curr_mtu;
 245                 else
 246                         len = s->init_num;
 247
 248
 249                 /* XDTLS: this function is too long.  split out the CCS part */
 250                 if ( type == SSL3_RT_HANDSHAKE)
 251                         {
 252                         if ( s->init_off != 0)
 253                                 {
 254                                 OPENSSL_assert(s->init_off > DTLS1_HM_HEADER_LENGTH);
 255                                 s->init_off -= DTLS1_HM_HEADER_LENGTH;
 256                                 s->init_num += DTLS1_HM_HEADER_LENGTH;
 257
 258                                 /* write atleast DTLS1_HM_HEADER_LENGTH bytes */
 259                                 if ( len <= DTLS1_HM_HEADER_LENGTH)
 260                                         len += DTLS1_HM_HEADER_LENGTH;
 261                                 }
 262
 263                         dtls1_fix_message_header(s, frag_off,
 264                                 len - DTLS1_HM_HEADER_LENGTH);
 265
 266                         dtls1_write_message_header(s, (unsigned char *)&s->init_buf->data[s->init_off]);
 267
 268                         OPENSSL_assert(len >= DTLS1_HM_HEADER_LENGTH);
 269                         }
 270
 271                 ret=dtls1_write_bytes(s,type,&s->init_buf->data[s->init_off],
 272                         len);
 273                 if (ret < 0)
 274                         {
 275                         /* might need to update MTU here, but we don't know
 276                          * which previous packet caused the failure -- so can't
 277                          * really retransmit anything.  continue as if everything
 278                          * is fine and wait for an alert to handle the
 279                          * retransmit
 280                          */
 281                         if ( BIO_ctrl(SSL_get_wbio(s),
 282                                 BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL))
 283                                 s->d1->mtu = BIO_ctrl(SSL_get_wbio(s),
 284                                         BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
 285                         else
 286                                 return(-1);
 287                         }
 288                 else
 289                         {
 290
 291                         /* bad if this assert fails, only part of the handshake
 292                          * message got sent.  but why would this happen? */
 293                         OPENSSL_assert(len == (unsigned int)ret);
 294
 295                         if (type == SSL3_RT_HANDSHAKE && ! s->d1->retransmitting)
 296                                 {
 297                                 /* should not be done for 'Hello Request's, but in that case
 298                                  * we'll ignore the result anyway */
 299                                 unsigned char *p = (unsigned char *)&s->init_buf->data[s->init_off];
 300                                 const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
 301                                 int xlen;
 302
 303                                 if (frag_off == 0 && s->version != DTLS1_BAD_VER)
 304                                         {
 305                                         /* reconstruct message header is if it
 306                                          * is being sent in single fragment */
 307                                         *p++ = msg_hdr->type;
 308                                         l2n3(msg_hdr->msg_len,p);
 309                                         s2n (msg_hdr->seq,p);
 310                                         l2n3(0,p);
 311                                         l2n3(msg_hdr->msg_len,p);
 312                                         p  -= DTLS1_HM_HEADER_LENGTH;
 313                                         xlen = ret;
 314                                         }
 315                                 else
 316                                         {
 317                                         p  += DTLS1_HM_HEADER_LENGTH;
 318                                         xlen = ret - DTLS1_HM_HEADER_LENGTH;
 319                                         }
 320
 321                                 ssl3_finish_mac(s, p, xlen);
 322                                 }
 323
 324                         if (ret == s->init_num)
 325                                 {
 326                                 if (s->msg_callback)
 327                                         s->msg_callback(1, s->version, type, s->init_buf->data,
 328                                                 (size_t)(s->init_off + s->init_num), s,
 329                                                 s->msg_callback_arg);
 330
 331                                 s->init_off = 0;  /* done writing this message */
 332                                 s->init_num = 0;
 333
 334                                 return(1);
 335                                 }
 336                         s->init_off+=ret;
 337                         s->init_num-=ret;
 338                         frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
 339                         }
 340                 }
 341         return(0);
 342         }
 343
 344
 345 /* Obtain handshake message of message type 'mt' (any if mt == -1),
 346  * maximum acceptable body length 'max'.
 347  * Read an entire handshake message.  Handshake messages arrive in
 348  * fragments.
 349  */
 350 long dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
 351         {
 352         int i, al;
 353         struct hm_header_st *msg_hdr;
 354
 355         /* s3->tmp is used to store messages that are unexpected, caused
 356          * by the absence of an optional handshake message */
 357         if (s->s3->tmp.reuse_message)
 358                 {
 359                 s->s3->tmp.reuse_message=0;
 360                 if ((mt >= 0) && (s->s3->tmp.message_type != mt))
 361                         {
 362                         al=SSL_AD_UNEXPECTED_MESSAGE;
 363                         SSLerr(SSL_F_DTLS1_GET_MESSAGE,SSL_R_UNEXPECTED_MESSAGE);
 364                         goto f_err;
 365                         }
 366                 *ok=1;
 367                 s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
 368                 s->init_num = (int)s->s3->tmp.message_size;
 369                 return s->init_num;
 370                 }
 371
 372         msg_hdr = &s->d1->r_msg_hdr;
 373         do
 374                 {
 375                 if ( msg_hdr->frag_off == 0)
 376                         {
 377                         /* s->d1->r_message_header.msg_len = 0; */
 378                         memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
 379                         }
 380
 381                 i = dtls1_get_message_fragment(s, st1, stn, max, ok);
 382                 if ( i == DTLS1_HM_BAD_FRAGMENT ||
 383                         i == DTLS1_HM_FRAGMENT_RETRY)  /* bad fragment received */
 384                         continue;
 385                 else if ( i <= 0 && !*ok)
 386                         return i;
 387
 388                 /* Note that s->init_sum is used as a counter summing
 389                  * up fragments' lengths: as soon as they sum up to
 390                  * handshake packet length, we assume we have got all
 391                  * the fragments. Overlapping fragments would cause
 392                  * premature termination, so we don't expect overlaps.
 393                  * Well, handling overlaps would require something more
 394                  * drastic. Indeed, as it is now there is no way to
 395                  * tell if out-of-order fragment from the middle was
 396                  * the last. '>=' is the best/least we can do to control
 397                  * the potential damage caused by malformed overlaps. */
 398                 if ((unsigned int)s->init_num >= msg_hdr->msg_len)
 399                         {
 400                         unsigned char *p = (unsigned char *)s->init_buf->data;
 401                         unsigned long msg_len = msg_hdr->msg_len;
 402
 403                         /* reconstruct message header as if it was
 404                          * sent in single fragment */
 405                         *(p++) = msg_hdr->type;
 406                         l2n3(msg_len,p);
 407                         s2n (msg_hdr->seq,p);
 408                         l2n3(0,p);
 409                         l2n3(msg_len,p);
 410                         if (s->version != DTLS1_BAD_VER) {
 411                                 p       -= DTLS1_HM_HEADER_LENGTH;
 412                                 msg_len += DTLS1_HM_HEADER_LENGTH;
 413                         }
 414
 415                         ssl3_finish_mac(s, p, msg_len);
 416                         if (s->msg_callback)
 417                                 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
 418                                         p, msg_len,
 419                                         s, s->msg_callback_arg);
 420
 421                         memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
 422
 423                         s->d1->handshake_read_seq++;
 424                         /* we just read a handshake message from the other side:
 425                          * this means that we don't need to retransmit of the
 426                          * buffered messages.
 427                          * XDTLS: may be able clear out this
 428                          * buffer a little sooner (i.e if an out-of-order
 429                          * handshake message/record is received at the record
 430                          * layer.
 431                          * XDTLS: exception is that the server needs to
 432                          * know that change cipher spec and finished messages
 433                          * have been received by the client before clearing this
 434                          * buffer.  this can simply be done by waiting for the
 435                          * first data  segment, but is there a better way?  */
 436                         dtls1_clear_record_buffer(s);
 437
 438                         s->init_msg = s->init_buf->data + DTLS1_HM_HEADER_LENGTH;
 439                         return s->init_num;
 440                         }
 441                 else
 442                         msg_hdr->frag_off = i;
 443                 } while(1) ;
 444
 445 f_err:
 446         ssl3_send_alert(s,SSL3_AL_FATAL,al);
 447         *ok = 0;
 448         return -1;
 449         }
 450
 451
 452 static int dtls1_preprocess_fragment(SSL *s,struct hm_header_st *msg_hdr,int max)
 453         {
 454         size_t frag_off,frag_len,msg_len;
 455
 456         msg_len  = msg_hdr->msg_len;
 457         frag_off = msg_hdr->frag_off;
 458         frag_len = msg_hdr->frag_len;
 459
 460         /* sanity checking */
 461         if ( (frag_off+frag_len) > msg_len)
 462                 {
 463                 SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
 464                 return SSL_AD_ILLEGAL_PARAMETER;
 465                 }
 466
 467         if ( (frag_off+frag_len) > (unsigned long)max)
 468                 {
 469                 SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
 470                 return SSL_AD_ILLEGAL_PARAMETER;
 471                 }
 472
 473         if ( s->d1->r_msg_hdr.frag_off == 0) /* first fragment */
 474                 {
 475                 /* msg_len is limited to 2^24, but is effectively checked
 476                  * against max above */
 477                 if (!BUF_MEM_grow_clean(s->init_buf,msg_len+DTLS1_HM_HEADER_LENGTH))
 478                         {
 479                         SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,ERR_R_BUF_LIB);
 480                         return SSL_AD_INTERNAL_ERROR;
 481                         }
 482
 483                 s->s3->tmp.message_size  = msg_len;
 484                 s->d1->r_msg_hdr.msg_len = msg_len;
 485                 s->s3->tmp.message_type  = msg_hdr->type;
 486                 s->d1->r_msg_hdr.type    = msg_hdr->type;
 487                 s->d1->r_msg_hdr.seq     = msg_hdr->seq;
 488                 }
 489         else if (msg_len != s->d1->r_msg_hdr.msg_len)
 490                 {
 491                 /* They must be playing with us! BTW, failure to enforce
 492                  * upper limit would open possibility for buffer overrun. */
 493                 SSLerr(SSL_F_DTLS1_PREPROCESS_FRAGMENT,SSL_R_EXCESSIVE_MESSAGE_SIZE);
 494                 return SSL_AD_ILLEGAL_PARAMETER;
 495                 }
 496
 497         return 0; /* no error */
 498         }
 499
 500
 501 static int
 502 dtls1_retrieve_buffered_fragment(SSL *s, long max, int *ok)
 503         {
 504         /* (0) check whether the desired fragment is available
 505          * if so:
 506          * (1) copy over the fragment to s->init_buf->data[]
 507          * (2) update s->init_num
 508          */
 509         pitem *item;
 510         hm_fragment *frag;
 511         int al;
 512
 513         *ok = 0;
 514         item = pqueue_peek(s->d1->buffered_messages);
 515         if ( item == NULL)
 516                 return 0;
 517
 518         frag = (hm_fragment *)item->data;
 519
 520         if ( s->d1->handshake_read_seq == frag->msg_header.seq)
 521                 {
 522                 unsigned long frag_len = frag->msg_header.frag_len;
 523                 pqueue_pop(s->d1->buffered_messages);
 524
 525                 al=dtls1_preprocess_fragment(s,&frag->msg_header,max);
 526
 527                 if (al==0) /* no alert */
 528                         {
 529                         unsigned char *p = (unsigned char *)s->init_buf->data+DTLS1_HM_HEADER_LENGTH;
 530                         memcpy(&p[frag->msg_header.frag_off],
 531                                 frag->fragment,frag->msg_header.frag_len);
 532                         }
 533
 534                 dtls1_hm_fragment_free(frag);
 535                 pitem_free(item);
 536
 537                 if (al==0)
 538                         {
 539                         *ok = 1;
 540                         return frag_len;
 541                         }
 542
 543                 ssl3_send_alert(s,SSL3_AL_FATAL,al);
 544                 s->init_num = 0;
 545                 *ok = 0;
 546                 return -1;
 547                 }
 548         else
 549                 return 0;
 550         }
 551
 552
 553 static int
 554 dtls1_process_out_of_seq_message(SSL *s, struct hm_header_st* msg_hdr, int *ok)
 555 {
 556         int i=-1;
 557         hm_fragment *frag = NULL;
 558         pitem *item = NULL;
 559         unsigned char seq64be[8];
 560         unsigned long frag_len = msg_hdr->frag_len;
 561
 562         if ((msg_hdr->frag_off+frag_len) > msg_hdr->msg_len)
 563                 goto err;
 564
 565         if (msg_hdr->seq <= s->d1->handshake_read_seq)
 566                 {
 567                 unsigned char devnull [256];
 568
 569                 while (frag_len)
 570                         {
 571                         i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
 572                                 devnull,
 573                                 frag_len>sizeof(devnull)?sizeof(devnull):frag_len,0);
 574                         if (i<=0) goto err;
 575                         frag_len -= i;
 576                         }
 577                 }
 578
 579         if (frag_len)
 580                 {
 581                 frag = dtls1_hm_fragment_new(frag_len);
 582                 if ( frag == NULL)
 583                         goto err;
 584
 585                 memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
 586
 587                 /* read the body of the fragment (header has already been read */
 588                 i = s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
 589                         frag->fragment,frag_len,0);
 590                 if (i<=0 || (unsigned long)i!=frag_len)
 591                         goto err;
 592
 593                 memset(seq64be,0,sizeof(seq64be));
 594                 seq64be[6] = (unsigned char)(msg_hdr->seq>>8);
 595                 seq64be[7] = (unsigned char)(msg_hdr->seq);
 596
 597                 item = pitem_new(seq64be, frag);
 598                 if ( item == NULL)
 599                         goto err;
 600
 601                 pqueue_insert(s->d1->buffered_messages, item);
 602                 }
 603
 604         return DTLS1_HM_FRAGMENT_RETRY;
 605
 606 err:
 607         if ( frag != NULL) dtls1_hm_fragment_free(frag);
 608         if ( item != NULL) OPENSSL_free(item);
 609         *ok = 0;
 610         return i;
 611         }
 612
 613
 614 static long
 615 dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
 616         {
 617         unsigned char wire[DTLS1_HM_HEADER_LENGTH];
 618         unsigned long l, frag_off, frag_len;
 619         int i,al;
 620         struct hm_header_st msg_hdr;
 621
 622         /* see if we have the required fragment already */
 623         if ((frag_len = dtls1_retrieve_buffered_fragment(s,max,ok)) || *ok)
 624                 {
 625                 if (*ok)        s->init_num += frag_len;
 626                 return frag_len;
 627                 }
 628
 629         /* read handshake message header */
 630         i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,wire,
 631                 DTLS1_HM_HEADER_LENGTH, 0);
 632         if (i <= 0)     /* nbio, or an error */
 633                 {
 634                 s->rwstate=SSL_READING;
 635                 *ok = 0;
 636                 return i;
 637                 }
 638         OPENSSL_assert(i == DTLS1_HM_HEADER_LENGTH);
 639
 640         /* parse the message fragment header */
 641         dtls1_get_message_header(wire, &msg_hdr);
 642
 643         /*
 644          * if this is a future (or stale) message it gets buffered
 645          * (or dropped)--no further processing at this time
 646          */
 647         if ( msg_hdr.seq != s->d1->handshake_read_seq)
 648                 return dtls1_process_out_of_seq_message(s, &msg_hdr, ok);
 649
 650         l = msg_hdr.msg_len;
 651         frag_off = msg_hdr.frag_off;
 652         frag_len = msg_hdr.frag_len;
 653
 654         if (!s->server && s->d1->r_msg_hdr.frag_off == 0 &&
 655                 wire[0] == SSL3_MT_HELLO_REQUEST)
 656                 {
 657                 /* The server may always send 'Hello Request' messages --
 658                  * we are doing a handshake anyway now, so ignore them
 659                  * if their format is correct. Does not count for
 660                  * 'Finished' MAC. */
 661                 if (wire[1] == 0 && wire[2] == 0 && wire[3] == 0)
 662                         {
 663                         if (s->msg_callback)
 664                                 s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE,
 665                                         wire, DTLS1_HM_HEADER_LENGTH, s,
 666                                         s->msg_callback_arg);
 667
 668                         s->init_num = 0;
 669                         return dtls1_get_message_fragment(s, st1, stn,
 670                                 max, ok);
 671                         }
 672                 else /* Incorrectly formated Hello request */
 673                         {
 674                         al=SSL_AD_UNEXPECTED_MESSAGE;
 675                         SSLerr(SSL_F_DTLS1_GET_MESSAGE_FRAGMENT,SSL_R_UNEXPECTED_MESSAGE);
 676                         goto f_err;
 677                         }
 678                 }
 679
 680         if ((al=dtls1_preprocess_fragment(s,&msg_hdr,max)))
 681                 goto f_err;
 682
 683         /* XDTLS:  ressurect this when restart is in place */
 684         s->state=stn;
 685
 686         if ( frag_len > 0)
 687                 {
 688                 unsigned char *p=(unsigned char *)s->init_buf->data+DTLS1_HM_HEADER_LENGTH;
 689
 690                 i=s->method->ssl_read_bytes(s,SSL3_RT_HANDSHAKE,
 691                         &p[frag_off],frag_len,0);
 692                 /* XDTLS:  fix this--message fragments cannot span multiple packets */
 693                 if (i <= 0)
 694                         {
 695                         s->rwstate=SSL_READING;
 696                         *ok = 0;
 697                         return i;
 698                         }
 699                 }
 700         else
 701                 i = 0;
 702
 703         /* XDTLS:  an incorrectly formatted fragment should cause the
 704          * handshake to fail */
 705         OPENSSL_assert(i == (int)frag_len);
 706
 707         *ok = 1;
 708
 709         /* Note that s->init_num is *not* used as current offset in
 710          * s->init_buf->data, but as a counter summing up fragments'
 711          * lengths: as soon as they sum up to handshake packet
 712          * length, we assume we have got all the fragments. */
 713         s->init_num += frag_len;
 714         return frag_len;
 715
 716 f_err:
 717         ssl3_send_alert(s,SSL3_AL_FATAL,al);
 718         s->init_num = 0;
 719
 720         *ok=0;
 721         return(-1);
 722         }
 723
 724 int dtls1_send_finished(SSL *s, int a, int b, const char *sender, int slen)
 725         {
 726         unsigned char *p,*d;
 727         int i;
 728         unsigned long l;
 729
 730         if (s->state == a)
 731                 {
 732                 d=(unsigned char *)s->init_buf->data;
 733                 p= &(d[DTLS1_HM_HEADER_LENGTH]);
 734
 735                 i=s->method->ssl3_enc->final_finish_mac(s,
 736                         sender,slen,s->s3->tmp.finish_md);
 737                 s->s3->tmp.finish_md_len = i;
 738                 memcpy(p, s->s3->tmp.finish_md, i);
 739                 p+=i;
 740                 l=i;
 741
 742 #ifdef OPENSSL_SYS_WIN16
 743                 /* MSVC 1.5 does not clear the top bytes of the word unless
 744                  * I do this.
 745                  */
 746                 l&=0xffff;
 747 #endif
 748
 749                 d = dtls1_set_message_header(s, d, SSL3_MT_FINISHED, l, 0, l);
 750                 s->init_num=(int)l+DTLS1_HM_HEADER_LENGTH;
 751                 s->init_off=0;
 752
 753                 /* buffer the message to handle re-xmits */
 754                 dtls1_buffer_message(s, 0);
 755
 756                 s->state=b;
 757                 }
 758
 759         /* SSL3_ST_SEND_xxxxxx_HELLO_B */
 760         return(dtls1_do_write(s,SSL3_RT_HANDSHAKE));
 761         }
 762
 763 /* for these 2 messages, we need to
 764  * ssl->enc_read_ctx                    re-init
 765  * ssl->s3->read_sequence               zero
 766  * ssl->s3->read_mac_secret             re-init
 767  * ssl->session->read_sym_enc           assign
 768  * ssl->session->read_compression       assign
 769  * ssl->session->read_hash              assign
 770  */
 771 int dtls1_send_change_cipher_spec(SSL *s, int a, int b)
 772         {
 773         unsigned char *p;
 774
 775         if (s->state == a)
 776                 {
 777                 p=(unsigned char *)s->init_buf->data;
 778                 *p++=SSL3_MT_CCS;
 779                 s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
 780                 s->init_num=DTLS1_CCS_HEADER_LENGTH;
 781
 782                 if (s->version == DTLS1_BAD_VER) {
 783                         s->d1->next_handshake_write_seq++;
 784                         s2n(s->d1->handshake_write_seq,p);
 785                         s->init_num+=2;
 786                 }
 787
 788                 s->init_off=0;
 789
 790                 dtls1_set_message_header_int(s, SSL3_MT_CCS, 0,
 791                         s->d1->handshake_write_seq, 0, 0);
 792
 793                 /* buffer the message to handle re-xmits */
 794                 dtls1_buffer_message(s, 1);
 795
 796                 s->state=b;
 797                 }
 798
 799         /* SSL3_ST_CW_CHANGE_B */
 800         return(dtls1_do_write(s,SSL3_RT_CHANGE_CIPHER_SPEC));
 801         }
 802
 803 unsigned long dtls1_output_cert_chain(SSL *s, X509 *x)
 804         {
 805         unsigned char *p;
 806         int n,i;
 807         unsigned long l= 3 + DTLS1_HM_HEADER_LENGTH;
 808         BUF_MEM *buf;
 809         X509_STORE_CTX xs_ctx;
 810         X509_OBJECT obj;
 811
 812         /* TLSv1 sends a chain with nothing in it, instead of an alert */
 813         buf=s->init_buf;
 814         if (!BUF_MEM_grow_clean(buf,10))
 815                 {
 816                 SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_BUF_LIB);
 817                 return(0);
 818                 }
 819         if (x != NULL)
 820                 {
 821                 if(!X509_STORE_CTX_init(&xs_ctx,s->ctx->cert_store,NULL,NULL))
 822                         {
 823                         SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_X509_LIB);
 824                         return(0);
 825                         }
 826
 827                 for (;;)
 828                         {
 829                         n=i2d_X509(x,NULL);
 830                         if (!BUF_MEM_grow_clean(buf,(n+l+3)))
 831                                 {
 832                                 SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_BUF_LIB);
 833                                 return(0);
 834                                 }
 835                         p=(unsigned char *)&(buf->data[l]);
 836                         l2n3(n,p);
 837                         i2d_X509(x,&p);
 838                         l+=n+3;
 839                         if (X509_NAME_cmp(X509_get_subject_name(x),
 840                                 X509_get_issuer_name(x)) == 0) break;
 841
 842                         i=X509_STORE_get_by_subject(&xs_ctx,X509_LU_X509,
 843                                 X509_get_issuer_name(x),&obj);
 844                         if (i <= 0) break;
 845                         x=obj.data.x509;
 846                         /* Count is one too high since the X509_STORE_get uped the
 847                          * ref count */
 848                         X509_free(x);
 849                         }
 850
 851                 X509_STORE_CTX_cleanup(&xs_ctx);
 852                 }
 853
 854         /* Thawte special :-) */
 855         if (s->ctx->extra_certs != NULL)
 856         for (i=0; i<sk_X509_num(s->ctx->extra_certs); i++)
 857                 {
 858                 x=sk_X509_value(s->ctx->extra_certs,i);
 859                 n=i2d_X509(x,NULL);
 860                 if (!BUF_MEM_grow_clean(buf,(n+l+3)))
 861                         {
 862                         SSLerr(SSL_F_DTLS1_OUTPUT_CERT_CHAIN,ERR_R_BUF_LIB);
 863                         return(0);
 864                         }
 865                 p=(unsigned char *)&(buf->data[l]);
 866                 l2n3(n,p);
 867                 i2d_X509(x,&p);
 868                 l+=n+3;
 869                 }
 870
 871         l-= (3 + DTLS1_HM_HEADER_LENGTH);
 872
 873         p=(unsigned char *)&(buf->data[DTLS1_HM_HEADER_LENGTH]);
 874         l2n3(l,p);
 875         l+=3;
 876         p=(unsigned char *)&(buf->data[0]);
 877         p = dtls1_set_message_header(s, p, SSL3_MT_CERTIFICATE, l, 0, l);
 878
 879         l+=DTLS1_HM_HEADER_LENGTH;
 880         return(l);
 881         }
 882
 883 int dtls1_read_failed(SSL *s, int code)
 884         {
 885         DTLS1_STATE *state;
 886         int send_alert = 0;
 887
 888         if ( code > 0)
 889                 {
 890                 fprintf( stderr, "invalid state reached %s:%d", __FILE__, __LINE__);
 891                 return 1;
 892                 }
 893
 894         if (!dtls1_is_timer_expired(s))
 895                 {
 896                 /* not a timeout, none of our business,
 897                    let higher layers handle this.  in fact it's probably an error */
 898                 return code;
 899                 }
 900
 901         if ( ! SSL_in_init(s))  /* done, no need to send a retransmit */
 902                 {
 903                 BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
 904                 return code;
 905                 }
 906
 907         dtls1_double_timeout(s);
 908         state = s->d1;
 909         state->timeout.num_alerts++;
 910         if ( state->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT)
 911                 {
 912                 /* fail the connection, enough alerts have been sent */
 913                 SSLerr(SSL_F_DTLS1_READ_FAILED,SSL_R_READ_TIMEOUT_EXPIRED);
 914                 return 0;
 915                 }
 916
 917         state->timeout.read_timeouts++;
 918         if ( state->timeout.read_timeouts > DTLS1_TMO_READ_COUNT)
 919                 {
 920                 send_alert = 1;
 921                 state->timeout.read_timeouts = 1;
 922                 }
 923
 924
 925 #if 0 /* for now, each alert contains only one record number */
 926         item = pqueue_peek(state->rcvd_records);
 927         if ( item )
 928                 {
 929                 /* send an alert immediately for all the missing records */
 930                 }
 931         else
 932 #endif
 933
 934 #if 0  /* no more alert sending, just retransmit the last set of messages */
 935                 if ( send_alert)
 936                         ssl3_send_alert(s,SSL3_AL_WARNING,
 937                                 DTLS1_AD_MISSING_HANDSHAKE_MESSAGE);
 938 #endif
 939
 940         return dtls1_retransmit_buffered_messages(s) ;
 941         }
 942
 943 int
 944 dtls1_get_queue_priority(unsigned short seq, int is_ccs)
 945         {
 946         /* The index of the retransmission queue actually is the message sequence number,
 947          * since the queue only contains messages of a single handshake. However, the
 948          * ChangeCipherSpec has no message sequence number and so using only the sequence
 949          * will result in the CCS and Finished having the same index. To prevent this,
 950          * the sequence number is multiplied by 2. In case of a CCS 1 is subtracted.
 951          * This does not only differ CSS and Finished, it also maintains the order of the
 952          * index (important for priority queues) and fits in the unsigned short variable.
 953          */
 954         return seq * 2 - is_ccs;
 955         }
 956
 957 int
 958 dtls1_retransmit_buffered_messages(SSL *s)
 959         {
 960         pqueue sent = s->d1->sent_messages;
 961         piterator iter;
 962         pitem *item;
 963         hm_fragment *frag;
 964         int found = 0;
 965
 966         iter = pqueue_iterator(sent);
 967
 968         for ( item = pqueue_next(&iter); item != NULL; item = pqueue_next(&iter))
 969                 {
 970                 frag = (hm_fragment *)item->data;
 971                         if ( dtls1_retransmit_message(s,
 972                                 (unsigned short)dtls1_get_queue_priority(frag->msg_header.seq, frag->msg_header.is_ccs),
 973                                 0, &found) <= 0 && found)
 974                         {
 975                         fprintf(stderr, "dtls1_retransmit_message() failed\n");
 976                         return -1;
 977                         }
 978                 }
 979
 980         return 1;
 981         }
 982
 983 int
 984 dtls1_buffer_message(SSL *s, int is_ccs)
 985         {
 986         pitem *item;
 987         hm_fragment *frag;
 988         unsigned char seq64be[8];
 989
 990         /* this function is called immediately after a message has
 991          * been serialized */
 992         OPENSSL_assert(s->init_off == 0);
 993
 994         frag = dtls1_hm_fragment_new(s->init_num);
 995
 996         memcpy(frag->fragment, s->init_buf->data, s->init_num);
 997
 998         if ( is_ccs)
 999                 {
1000                 OPENSSL_assert(s->d1->w_msg_hdr.msg_len +
1001                                ((s->version==DTLS1_VERSION)?DTLS1_CCS_HEADER_LENGTH:3) == (unsigned int)s->init_num);
1002                 }
1003         else
1004                 {
1005                 OPENSSL_assert(s->d1->w_msg_hdr.msg_len +
1006                         DTLS1_HM_HEADER_LENGTH == (unsigned int)s->init_num);
1007                 }
1008
1009         frag->msg_header.msg_len = s->d1->w_msg_hdr.msg_len;
1010         frag->msg_header.seq = s->d1->w_msg_hdr.seq;
1011         frag->msg_header.type = s->d1->w_msg_hdr.type;
1012         frag->msg_header.frag_off = 0;
1013         frag->msg_header.frag_len = s->d1->w_msg_hdr.msg_len;
1014         frag->msg_header.is_ccs = is_ccs;
1015
1016         /* save current state*/
1017         frag->msg_header.saved_retransmit_state.enc_write_ctx = s->enc_write_ctx;
1018         frag->msg_header.saved_retransmit_state.write_hash = s->write_hash;
1019         frag->msg_header.saved_retransmit_state.compress = s->compress;
1020         frag->msg_header.saved_retransmit_state.session = s->session;
1021         frag->msg_header.saved_retransmit_state.epoch = s->d1->w_epoch;
1022
1023         memset(seq64be,0,sizeof(seq64be));
1024         seq64be[6] = (unsigned char)(dtls1_get_queue_priority(frag->msg_header.seq,
1025                                                                                                                   frag->msg_header.is_ccs)>>8);
1026         seq64be[7] = (unsigned char)(dtls1_get_queue_priority(frag->msg_header.seq,
1027                                                                                                                   frag->msg_header.is_ccs));
1028
1029         item = pitem_new(seq64be, frag);
1030         if ( item == NULL)
1031                 {
1032                 dtls1_hm_fragment_free(frag);
1033                 return 0;
1034                 }
1035
1036 #if 0
1037         fprintf( stderr, "buffered messge: \ttype = %xx\n", msg_buf->type);
1038         fprintf( stderr, "\t\t\t\t\tlen = %d\n", msg_buf->len);
1039         fprintf( stderr, "\t\t\t\t\tseq_num = %d\n", msg_buf->seq_num);
1040 #endif
1041
1042         pqueue_insert(s->d1->sent_messages, item);
1043         return 1;
1044         }
1045
1046 int
1047 dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
1048         int *found)
1049         {
1050         int ret;
1051         /* XDTLS: for now assuming that read/writes are blocking */
1052         pitem *item;
1053         hm_fragment *frag ;
1054         unsigned long header_length;
1055         unsigned char seq64be[8];
1056         struct dtls1_retransmit_state saved_state;
1057         unsigned char save_write_sequence[8];
1058
1059         /*
1060           OPENSSL_assert(s->init_num == 0);
1061           OPENSSL_assert(s->init_off == 0);
1062          */
1063
1064         /* XDTLS:  the requested message ought to be found, otherwise error */
1065         memset(seq64be,0,sizeof(seq64be));
1066         seq64be[6] = (unsigned char)(seq>>8);
1067         seq64be[7] = (unsigned char)seq;
1068
1069         item = pqueue_find(s->d1->sent_messages, seq64be);
1070         if ( item == NULL)
1071                 {
1072                 fprintf(stderr, "retransmit:  message %d non-existant\n", seq);
1073                 *found = 0;
1074                 return 0;
1075                 }
1076
1077         *found = 1;
1078         frag = (hm_fragment *)item->data;
1079
1080         if ( frag->msg_header.is_ccs)
1081                 header_length = DTLS1_CCS_HEADER_LENGTH;
1082         else
1083                 header_length = DTLS1_HM_HEADER_LENGTH;
1084
1085         memcpy(s->init_buf->data, frag->fragment,
1086                 frag->msg_header.msg_len + header_length);
1087                 s->init_num = frag->msg_header.msg_len + header_length;
1088
1089         dtls1_set_message_header_int(s, frag->msg_header.type,
1090                 frag->msg_header.msg_len, frag->msg_header.seq, 0,
1091                 frag->msg_header.frag_len);
1092
1093         /* save current state */
1094         saved_state.enc_write_ctx = s->enc_write_ctx;
1095         saved_state.write_hash = s->write_hash;
1096         saved_state.compress = s->compress;
1097         saved_state.session = s->session;
1098         saved_state.epoch = s->d1->w_epoch;
1099         saved_state.epoch = s->d1->w_epoch;
1100
1101         s->d1->retransmitting = 1;
1102
1103         /* restore state in which the message was originally sent */
1104         s->enc_write_ctx = frag->msg_header.saved_retransmit_state.enc_write_ctx;
1105         s->write_hash = frag->msg_header.saved_retransmit_state.write_hash;
1106         s->compress = frag->msg_header.saved_retransmit_state.compress;
1107         s->session = frag->msg_header.saved_retransmit_state.session;
1108         s->d1->w_epoch = frag->msg_header.saved_retransmit_state.epoch;
1109
1110         if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
1111         {
1112                 memcpy(save_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
1113                 memcpy(s->s3->write_sequence, s->d1->last_write_sequence, sizeof(s->s3->write_sequence));
1114         }
1115
1116         ret = dtls1_do_write(s, frag->msg_header.is_ccs ?
1117                                                  SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
1118
1119         /* restore current state */
1120         s->enc_write_ctx = saved_state.enc_write_ctx;
1121         s->write_hash = saved_state.write_hash;
1122         s->compress = saved_state.compress;
1123         s->session = saved_state.session;
1124         s->d1->w_epoch = saved_state.epoch;
1125
1126         if (frag->msg_header.saved_retransmit_state.epoch == saved_state.epoch - 1)
1127         {
1128                 memcpy(s->d1->last_write_sequence, s->s3->write_sequence, sizeof(s->s3->write_sequence));
1129                 memcpy(s->s3->write_sequence, save_write_sequence, sizeof(s->s3->write_sequence));
1130         }
1131
1132         s->d1->retransmitting = 0;
1133
1134         (void)BIO_flush(SSL_get_wbio(s));
1135         return ret;
1136         }
1137
1138 /* call this function when the buffered messages are no longer needed */
1139 void
1140 dtls1_clear_record_buffer(SSL *s)
1141         {
1142         pitem *item;
1143
1144         for(item = pqueue_pop(s->d1->sent_messages);
1145                 item != NULL; item = pqueue_pop(s->d1->sent_messages))
1146                 {
1147                 dtls1_hm_fragment_free((hm_fragment *)item->data);
1148                 pitem_free(item);
1149                 }
1150         }
1151
1152
1153 unsigned char *
1154 dtls1_set_message_header(SSL *s, unsigned char *p, unsigned char mt,
1155                         unsigned long len, unsigned long frag_off, unsigned long frag_len)
1156         {
1157         if ( frag_off == 0)
1158                 {
1159                 s->d1->handshake_write_seq = s->d1->next_handshake_write_seq;
1160                 s->d1->next_handshake_write_seq++;
1161                 }
1162
1163         dtls1_set_message_header_int(s, mt, len, s->d1->handshake_write_seq,
1164                 frag_off, frag_len);
1165
1166         return p += DTLS1_HM_HEADER_LENGTH;
1167         }
1168
1169
1170 /* don't actually do the writing, wait till the MTU has been retrieved */
1171 static void
1172 dtls1_set_message_header_int(SSL *s, unsigned char mt,
1173                             unsigned long len, unsigned short seq_num, unsigned long frag_off,
1174                             unsigned long frag_len)
1175         {
1176         struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
1177
1178         msg_hdr->type = mt;
1179         msg_hdr->msg_len = len;
1180         msg_hdr->seq = seq_num;
1181         msg_hdr->frag_off = frag_off;
1182         msg_hdr->frag_len = frag_len;
1183         }
1184
1185 static void
1186 dtls1_fix_message_header(SSL *s, unsigned long frag_off,
1187                         unsigned long frag_len)
1188         {
1189         struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
1190
1191         msg_hdr->frag_off = frag_off;
1192         msg_hdr->frag_len = frag_len;
1193         }
1194
1195 static unsigned char *
1196 dtls1_write_message_header(SSL *s, unsigned char *p)
1197         {
1198         struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr;
1199
1200         *p++ = msg_hdr->type;
1201         l2n3(msg_hdr->msg_len, p);
1202
1203         s2n(msg_hdr->seq, p);
1204         l2n3(msg_hdr->frag_off, p);
1205         l2n3(msg_hdr->frag_len, p);
1206
1207         return p;
1208         }
1209
1210 static unsigned int
1211 dtls1_min_mtu(void)
1212         {
1213         return (g_probable_mtu[(sizeof(g_probable_mtu) /
1214                 sizeof(g_probable_mtu[0])) - 1]);
1215         }
1216
1217 static unsigned int
1218 dtls1_guess_mtu(unsigned int curr_mtu)
1219         {
1220         unsigned int i;
1221
1222         if ( curr_mtu == 0 )
1223                 return g_probable_mtu[0] ;
1224
1225         for ( i = 0; i < sizeof(g_probable_mtu)/sizeof(g_probable_mtu[0]); i++)
1226                 if ( curr_mtu > g_probable_mtu[i])
1227                         return g_probable_mtu[i];
1228
1229         return curr_mtu;
1230         }
1231
1232 void
1233 dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
1234         {
1235         memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
1236         msg_hdr->type = *(data++);
1237         n2l3(data, msg_hdr->msg_len);
1238
1239         n2s(data, msg_hdr->seq);
1240         n2l3(data, msg_hdr->frag_off);
1241         n2l3(data, msg_hdr->frag_len);
1242         }
1243
1244 void
1245 dtls1_get_ccs_header(unsigned char *data, struct ccs_header_st *ccs_hdr)
1246         {
1247         memset(ccs_hdr, 0x00, sizeof(struct ccs_header_st));
1248
1249         ccs_hdr->type = *(data++);
1250         }