ssl/d1_lib.c

   1 /*
   2  * Copyright 2005-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include "e_os.h"
  11 #include <stdio.h>
  12 #include <openssl/objects.h>
  13 #include <openssl/rand.h>
  14 #include "ssl_locl.h"
  15
  16 static void get_current_time(struct timeval *t);
  17 static int dtls1_handshake_write(SSL *s);
  18 static size_t dtls1_link_min_mtu(void);
  19
  20 /* XDTLS:  figure out the right values */
  21 static const size_t g_probable_mtu[] = { 1500, 512, 256 };
  22
  23 const SSL3_ENC_METHOD DTLSv1_enc_data = {
  24     tls1_enc,
  25     tls1_mac,
  26     tls1_setup_key_block,
  27     tls1_generate_master_secret,
  28     tls1_change_cipher_state,
  29     tls1_final_finish_mac,
  30     TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
  31     TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
  32     tls1_alert_code,
  33     tls1_export_keying_material,
  34     SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV,
  35     dtls1_set_handshake_header,
  36     dtls1_close_construct_packet,
  37     dtls1_handshake_write
  38 };
  39
  40 const SSL3_ENC_METHOD DTLSv1_2_enc_data = {
  41     tls1_enc,
  42     tls1_mac,
  43     tls1_setup_key_block,
  44     tls1_generate_master_secret,
  45     tls1_change_cipher_state,
  46     tls1_final_finish_mac,
  47     TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
  48     TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
  49     tls1_alert_code,
  50     tls1_export_keying_material,
  51     SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV | SSL_ENC_FLAG_SIGALGS
  52         | SSL_ENC_FLAG_SHA256_PRF | SSL_ENC_FLAG_TLS1_2_CIPHERS,
  53     dtls1_set_handshake_header,
  54     dtls1_close_construct_packet,
  55     dtls1_handshake_write
  56 };
  57
  58 long dtls1_default_timeout(void)
  59 {
  60     /*
  61      * 2 hours, the 24 hours mentioned in the DTLSv1 spec is way too long for
  62      * http, the cache would over fill
  63      */
  64     return (60 * 60 * 2);
  65 }
  66
  67 int dtls1_new(SSL *s)
  68 {
  69     DTLS1_STATE *d1;
  70
  71     if (!DTLS_RECORD_LAYER_new(&s->rlayer)) {
  72         return 0;
  73     }
  74
  75     if (!ssl3_new(s))
  76         return 0;
  77     if ((d1 = OPENSSL_zalloc(sizeof(*d1))) == NULL) {
  78         ssl3_free(s);
  79         return 0;
  80     }
  81
  82     d1->buffered_messages = pqueue_new();
  83     d1->sent_messages = pqueue_new();
  84
  85     if (s->server) {
  86         d1->cookie_len = sizeof(s->d1->cookie);
  87     }
  88
  89     d1->link_mtu = 0;
  90     d1->mtu = 0;
  91
  92     if (d1->buffered_messages == NULL || d1->sent_messages == NULL) {
  93         pqueue_free(d1->buffered_messages);
  94         pqueue_free(d1->sent_messages);
  95         OPENSSL_free(d1);
  96         ssl3_free(s);
  97         return 0;
  98     }
  99
 100     s->d1 = d1;
 101
 102     if (!s->method->ssl_clear(s))
 103         return 0;
 104
 105     return 1;
 106 }
 107
 108 static void dtls1_clear_queues(SSL *s)
 109 {
 110     dtls1_clear_received_buffer(s);
 111     dtls1_clear_sent_buffer(s);
 112 }
 113
 114 void dtls1_clear_received_buffer(SSL *s)
 115 {
 116     pitem *item = NULL;
 117     hm_fragment *frag = NULL;
 118
 119     while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) {
 120         frag = (hm_fragment *)item->data;
 121         dtls1_hm_fragment_free(frag);
 122         pitem_free(item);
 123     }
 124 }
 125
 126 void dtls1_clear_sent_buffer(SSL *s)
 127 {
 128     pitem *item = NULL;
 129     hm_fragment *frag = NULL;
 130
 131     while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
 132         frag = (hm_fragment *)item->data;
 133         dtls1_hm_fragment_free(frag);
 134         pitem_free(item);
 135     }
 136 }
 137
 138
 139 void dtls1_free(SSL *s)
 140 {
 141     DTLS_RECORD_LAYER_free(&s->rlayer);
 142
 143     ssl3_free(s);
 144
 145     dtls1_clear_queues(s);
 146
 147     pqueue_free(s->d1->buffered_messages);
 148     pqueue_free(s->d1->sent_messages);
 149
 150     OPENSSL_free(s->d1);
 151     s->d1 = NULL;
 152 }
 153
 154 int dtls1_clear(SSL *s)
 155 {
 156     pqueue *buffered_messages;
 157     pqueue *sent_messages;
 158     size_t mtu;
 159     size_t link_mtu;
 160
 161     DTLS_RECORD_LAYER_clear(&s->rlayer);
 162
 163     if (s->d1) {
 164         DTLS_timer_cb timer_cb = s->d1->timer_cb;
 165
 166         buffered_messages = s->d1->buffered_messages;
 167         sent_messages = s->d1->sent_messages;
 168         mtu = s->d1->mtu;
 169         link_mtu = s->d1->link_mtu;
 170
 171         dtls1_clear_queues(s);
 172
 173         memset(s->d1, 0, sizeof(*s->d1));
 174
 175         /* Restore the timer callback from previous state */
 176         s->d1->timer_cb = timer_cb;
 177
 178         if (s->server) {
 179             s->d1->cookie_len = sizeof(s->d1->cookie);
 180         }
 181
 182         if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
 183             s->d1->mtu = mtu;
 184             s->d1->link_mtu = link_mtu;
 185         }
 186
 187         s->d1->buffered_messages = buffered_messages;
 188         s->d1->sent_messages = sent_messages;
 189     }
 190
 191     if (!ssl3_clear(s))
 192         return 0;
 193
 194     if (s->method->version == DTLS_ANY_VERSION)
 195         s->version = DTLS_MAX_VERSION_INTERNAL;
 196 #ifndef OPENSSL_NO_DTLS1_METHOD
 197     else if (s->options & SSL_OP_CISCO_ANYCONNECT)
 198         s->client_version = s->version = DTLS1_BAD_VER;
 199 #endif
 200     else
 201         s->version = s->method->version;
 202
 203     return 1;
 204 }
 205
 206 long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
 207 {
 208     int ret = 0;
 209
 210     switch (cmd) {
 211     case DTLS_CTRL_GET_TIMEOUT:
 212         if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) {
 213             ret = 1;
 214         }
 215         break;
 216     case DTLS_CTRL_HANDLE_TIMEOUT:
 217         ret = dtls1_handle_timeout(s);
 218         break;
 219     case DTLS_CTRL_SET_LINK_MTU:
 220         if (larg < (long)dtls1_link_min_mtu())
 221             return 0;
 222         s->d1->link_mtu = larg;
 223         return 1;
 224     case DTLS_CTRL_GET_LINK_MIN_MTU:
 225         return (long)dtls1_link_min_mtu();
 226     case SSL_CTRL_SET_MTU:
 227         /*
 228          *  We may not have a BIO set yet so can't call dtls1_min_mtu()
 229          *  We'll have to make do with dtls1_link_min_mtu() and max overhead
 230          */
 231         if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
 232             return 0;
 233         s->d1->mtu = larg;
 234         return larg;
 235     default:
 236         ret = ssl3_ctrl(s, cmd, larg, parg);
 237         break;
 238     }
 239     return ret;
 240 }
 241
 242 void dtls1_start_timer(SSL *s)
 243 {
 244     unsigned int sec, usec;
 245
 246 #ifndef OPENSSL_NO_SCTP
 247     /* Disable timer for SCTP */
 248     if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
 249         memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
 250         return;
 251     }
 252 #endif
 253
 254     /*
 255      * If timer is not set, initialize duration with 1 second or
 256      * a user-specified value if the timer callback is installed.
 257      */
 258     if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
 259
 260         if (s->d1->timer_cb != NULL)
 261             s->d1->timeout_duration_us = s->d1->timer_cb(s, 0);
 262         else
 263             s->d1->timeout_duration_us = 1000000;
 264     }
 265
 266     /* Set timeout to current time */
 267     get_current_time(&(s->d1->next_timeout));
 268
 269     /* Add duration to current time */
 270
 271     sec  = s->d1->timeout_duration_us / 1000000;
 272     usec = s->d1->timeout_duration_us - (sec * 1000000);
 273
 274     s->d1->next_timeout.tv_sec  += sec;
 275     s->d1->next_timeout.tv_usec += usec;
 276
 277     if (s->d1->next_timeout.tv_usec >= 1000000) {
 278         s->d1->next_timeout.tv_sec++;
 279         s->d1->next_timeout.tv_usec -= 1000000;
 280     }
 281
 282     BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
 283              &(s->d1->next_timeout));
 284 }
 285
 286 struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft)
 287 {
 288     struct timeval timenow;
 289
 290     /* If no timeout is set, just return NULL */
 291     if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
 292         return NULL;
 293     }
 294
 295     /* Get current time */
 296     get_current_time(&timenow);
 297
 298     /* If timer already expired, set remaining time to 0 */
 299     if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
 300         (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
 301          s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
 302         memset(timeleft, 0, sizeof(*timeleft));
 303         return timeleft;
 304     }
 305
 306     /* Calculate time left until timer expires */
 307     memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
 308     timeleft->tv_sec -= timenow.tv_sec;
 309     timeleft->tv_usec -= timenow.tv_usec;
 310     if (timeleft->tv_usec < 0) {
 311         timeleft->tv_sec--;
 312         timeleft->tv_usec += 1000000;
 313     }
 314
 315     /*
 316      * If remaining time is less than 15 ms, set it to 0 to prevent issues
 317      * because of small divergences with socket timeouts.
 318      */
 319     if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
 320         memset(timeleft, 0, sizeof(*timeleft));
 321     }
 322
 323     return timeleft;
 324 }
 325
 326 int dtls1_is_timer_expired(SSL *s)
 327 {
 328     struct timeval timeleft;
 329
 330     /* Get time left until timeout, return false if no timer running */
 331     if (dtls1_get_timeout(s, &timeleft) == NULL) {
 332         return 0;
 333     }
 334
 335     /* Return false if timer is not expired yet */
 336     if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
 337         return 0;
 338     }
 339
 340     /* Timer expired, so return true */
 341     return 1;
 342 }
 343
 344 void dtls1_double_timeout(SSL *s)
 345 {
 346     s->d1->timeout_duration_us *= 2;
 347     if (s->d1->timeout_duration_us > 60000000)
 348         s->d1->timeout_duration_us = 60000000;
 349     dtls1_start_timer(s);
 350 }
 351
 352 void dtls1_stop_timer(SSL *s)
 353 {
 354     /* Reset everything */
 355     memset(&s->d1->timeout, 0, sizeof(s->d1->timeout));
 356     memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
 357     s->d1->timeout_duration_us = 1000000;
 358     BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
 359              &(s->d1->next_timeout));
 360     /* Clear retransmission buffer */
 361     dtls1_clear_sent_buffer(s);
 362 }
 363
 364 int dtls1_check_timeout_num(SSL *s)
 365 {
 366     size_t mtu;
 367
 368     s->d1->timeout.num_alerts++;
 369
 370     /* Reduce MTU after 2 unsuccessful retransmissions */
 371     if (s->d1->timeout.num_alerts > 2
 372         && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
 373         mtu =
 374             BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
 375         if (mtu < s->d1->mtu)
 376             s->d1->mtu = mtu;
 377     }
 378
 379     if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) {
 380         /* fail the connection, enough alerts have been sent */
 381         SSLfatal(s, SSL_AD_NO_ALERT, 0,
 382                  SSL_R_READ_TIMEOUT_EXPIRED);
 383         return -1;
 384     }
 385
 386     return 0;
 387 }
 388
 389 int dtls1_handle_timeout(SSL *s)
 390 {
 391     /* if no timer is expired, don't do anything */
 392     if (!dtls1_is_timer_expired(s)) {
 393         return 0;
 394     }
 395
 396     if (s->d1->timer_cb != NULL)
 397         s->d1->timeout_duration_us = s->d1->timer_cb(s, s->d1->timeout_duration_us);
 398     else
 399         dtls1_double_timeout(s);
 400
 401     if (dtls1_check_timeout_num(s) < 0) {
 402         /* SSLfatal() already called */
 403         return -1;
 404     }
 405
 406     s->d1->timeout.read_timeouts++;
 407     if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) {
 408         s->d1->timeout.read_timeouts = 1;
 409     }
 410
 411     dtls1_start_timer(s);
 412     /* Calls SSLfatal() if required */
 413     return dtls1_retransmit_buffered_messages(s);
 414 }
 415
 416 static void get_current_time(struct timeval *t)
 417 {
 418 #if defined(_WIN32)
 419     SYSTEMTIME st;
 420     union {
 421         unsigned __int64 ul;
 422         FILETIME ft;
 423     } now;
 424
 425     GetSystemTime(&st);
 426     SystemTimeToFileTime(&st, &now.ft);
 427     /* re-bias to 1/1/1970 */
 428 # ifdef  __MINGW32__
 429     now.ul -= 116444736000000000ULL;
 430 # else
 431     /* *INDENT-OFF* */
 432     now.ul -= 116444736000000000UI64;
 433     /* *INDENT-ON* */
 434 # endif
 435     t->tv_sec = (long)(now.ul / 10000000);
 436     t->tv_usec = ((int)(now.ul % 10000000)) / 10;
 437 #else
 438     gettimeofday(t, NULL);
 439 #endif
 440 }
 441
 442 #define LISTEN_SUCCESS              2
 443 #define LISTEN_SEND_VERIFY_REQUEST  1
 444
 445 #ifndef OPENSSL_NO_SOCK
 446 int DTLSv1_listen(SSL *s, BIO_ADDR *client)
 447 {
 448     int next, n, ret = 0;
 449     unsigned char cookie[DTLS1_COOKIE_LENGTH];
 450     unsigned char seq[SEQ_NUM_SIZE];
 451     const unsigned char *data;
 452     unsigned char *buf, *wbuf;
 453     size_t fragoff, fraglen, msglen, reclen, align = 0;
 454     unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen;
 455     BIO *rbio, *wbio;
 456     BIO_ADDR *tmpclient = NULL;
 457     PACKET pkt, msgpkt, msgpayload, session, cookiepkt;
 458
 459     if (s->handshake_func == NULL) {
 460         /* Not properly initialized yet */
 461         SSL_set_accept_state(s);
 462     }
 463
 464     /* Ensure there is no state left over from a previous invocation */
 465     if (!SSL_clear(s))
 466         return -1;
 467
 468     ERR_clear_error();
 469
 470     rbio = SSL_get_rbio(s);
 471     wbio = SSL_get_wbio(s);
 472
 473     if (!rbio || !wbio) {
 474         SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BIO_NOT_SET);
 475         return -1;
 476     }
 477
 478     /*
 479      * Note: This check deliberately excludes DTLS1_BAD_VER because that version
 480      * requires the MAC to be calculated *including* the first ClientHello
 481      * (without the cookie). Since DTLSv1_listen is stateless that cannot be
 482      * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via
 483      * SSL_accept)
 484      */
 485     if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) {
 486         SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNSUPPORTED_SSL_VERSION);
 487         return -1;
 488     }
 489
 490     if (!ssl3_setup_buffers(s)) {
 491         /* SSLerr already called */
 492         return -1;
 493     }
 494     buf = RECORD_LAYER_get_rbuf(&s->rlayer)->buf;
 495     wbuf = RECORD_LAYER_get_wbuf(&s->rlayer)[0].buf;
 496 #if defined(SSL3_ALIGN_PAYLOAD)
 497 # if SSL3_ALIGN_PAYLOAD != 0
 498     /*
 499      * Using SSL3_RT_HEADER_LENGTH here instead of DTLS1_RT_HEADER_LENGTH for
 500      * consistency with ssl3_read_n. In practice it should make no difference
 501      * for sensible values of SSL3_ALIGN_PAYLOAD because the difference between
 502      * SSL3_RT_HEADER_LENGTH and DTLS1_RT_HEADER_LENGTH is exactly 8
 503      */
 504     align = (size_t)buf + SSL3_RT_HEADER_LENGTH;
 505     align = SSL3_ALIGN_PAYLOAD - 1 - ((align - 1) % SSL3_ALIGN_PAYLOAD);
 506 # endif
 507 #endif
 508     buf += align;
 509
 510     do {
 511         /* Get a packet */
 512
 513         clear_sys_error();
 514         n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH
 515                                 + DTLS1_RT_HEADER_LENGTH);
 516         if (n <= 0) {
 517             if (BIO_should_retry(rbio)) {
 518                 /* Non-blocking IO */
 519                 goto end;
 520             }
 521             return -1;
 522         }
 523
 524         if (!PACKET_buf_init(&pkt, buf, n)) {
 525             SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
 526             return -1;
 527         }
 528
 529         /*
 530          * Parse the received record. If there are any problems with it we just
 531          * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is
 532          * resilient in the face of invalid records (e.g., invalid formatting,
 533          * length, MAC, etc.).  In general, invalid records SHOULD be silently
 534          * discarded, thus preserving the association; however, an error MAY be
 535          * logged for diagnostic purposes."
 536          */
 537
 538         /* this packet contained a partial record, dump it */
 539         if (n < DTLS1_RT_HEADER_LENGTH) {
 540             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_RECORD_TOO_SMALL);
 541             goto end;
 542         }
 543
 544         if (s->msg_callback)
 545             s->msg_callback(0, 0, SSL3_RT_HEADER, buf,
 546                             DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
 547
 548         /* Get the record header */
 549         if (!PACKET_get_1(&pkt, &rectype)
 550             || !PACKET_get_1(&pkt, &versmajor)) {
 551             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 552             goto end;
 553         }
 554
 555         if (rectype != SSL3_RT_HANDSHAKE) {
 556             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
 557             goto end;
 558         }
 559
 560         /*
 561          * Check record version number. We only check that the major version is
 562          * the same.
 563          */
 564         if (versmajor != DTLS1_VERSION_MAJOR) {
 565             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
 566             goto end;
 567         }
 568
 569         if (!PACKET_forward(&pkt, 1)
 570             /* Save the sequence number: 64 bits, with top 2 bytes = epoch */
 571             || !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE)
 572             || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) {
 573             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 574             goto end;
 575         }
 576         reclen = PACKET_remaining(&msgpkt);
 577         /*
 578          * We allow data remaining at the end of the packet because there could
 579          * be a second record (but we ignore it)
 580          */
 581
 582         /* This is an initial ClientHello so the epoch has to be 0 */
 583         if (seq[0] != 0 || seq[1] != 0) {
 584             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
 585             goto end;
 586         }
 587
 588         /* Get a pointer to the raw message for the later callback */
 589         data = PACKET_data(&msgpkt);
 590
 591         /* Finished processing the record header, now process the message */
 592         if (!PACKET_get_1(&msgpkt, &msgtype)
 593             || !PACKET_get_net_3_len(&msgpkt, &msglen)
 594             || !PACKET_get_net_2(&msgpkt, &msgseq)
 595             || !PACKET_get_net_3_len(&msgpkt, &fragoff)
 596             || !PACKET_get_net_3_len(&msgpkt, &fraglen)
 597             || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen)
 598             || PACKET_remaining(&msgpkt) != 0) {
 599             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 600             goto end;
 601         }
 602
 603         if (msgtype != SSL3_MT_CLIENT_HELLO) {
 604             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
 605             goto end;
 606         }
 607
 608         /* Message sequence number can only be 0 or 1 */
 609         if (msgseq > 2) {
 610             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_INVALID_SEQUENCE_NUMBER);
 611             goto end;
 612         }
 613
 614         /*
 615          * We don't support fragment reassembly for ClientHellos whilst
 616          * listening because that would require server side state (which is
 617          * against the whole point of the ClientHello/HelloVerifyRequest
 618          * mechanism). Instead we only look at the first ClientHello fragment
 619          * and require that the cookie must be contained within it.
 620          */
 621         if (fragoff != 0 || fraglen > msglen) {
 622             /* Non initial ClientHello fragment (or bad fragment) */
 623             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_FRAGMENTED_CLIENT_HELLO);
 624             goto end;
 625         }
 626
 627         if (s->msg_callback)
 628             s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data,
 629                             fraglen + DTLS1_HM_HEADER_LENGTH, s,
 630                             s->msg_callback_arg);
 631
 632         if (!PACKET_get_net_2(&msgpayload, &clientvers)) {
 633             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 634             goto end;
 635         }
 636
 637         /*
 638          * Verify client version is supported
 639          */
 640         if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) &&
 641             s->method->version != DTLS_ANY_VERSION) {
 642             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_WRONG_VERSION_NUMBER);
 643             goto end;
 644         }
 645
 646         if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE)
 647             || !PACKET_get_length_prefixed_1(&msgpayload, &session)
 648             || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) {
 649             /*
 650              * Could be malformed or the cookie does not fit within the initial
 651              * ClientHello fragment. Either way we can't handle it.
 652              */
 653             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 654             goto end;
 655         }
 656
 657         /*
 658          * Check if we have a cookie or not. If not we need to send a
 659          * HelloVerifyRequest.
 660          */
 661         if (PACKET_remaining(&cookiepkt) == 0) {
 662             next = LISTEN_SEND_VERIFY_REQUEST;
 663         } else {
 664             /*
 665              * We have a cookie, so lets check it.
 666              */
 667             if (s->ctx->app_verify_cookie_cb == NULL) {
 668                 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_NO_VERIFY_COOKIE_CALLBACK);
 669                 /* This is fatal */
 670                 return -1;
 671             }
 672             if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt),
 673                     (unsigned int)PACKET_remaining(&cookiepkt)) == 0) {
 674                 /*
 675                  * We treat invalid cookies in the same was as no cookie as
 676                  * per RFC6347
 677                  */
 678                 next = LISTEN_SEND_VERIFY_REQUEST;
 679             } else {
 680                 /* Cookie verification succeeded */
 681                 next = LISTEN_SUCCESS;
 682             }
 683         }
 684
 685         if (next == LISTEN_SEND_VERIFY_REQUEST) {
 686             WPACKET wpkt;
 687             unsigned int version;
 688             size_t wreclen;
 689
 690             /*
 691              * There was no cookie in the ClientHello so we need to send a
 692              * HelloVerifyRequest. If this fails we do not worry about trying
 693              * to resend, we just drop it.
 694              */
 695
 696             /* Generate the cookie */
 697             if (s->ctx->app_gen_cookie_cb == NULL ||
 698                 s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 ||
 699                 cookielen > 255) {
 700                 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_COOKIE_GEN_CALLBACK_FAILURE);
 701                 /* This is fatal */
 702                 return -1;
 703             }
 704
 705             /*
 706              * Special case: for hello verify request, client version 1.0 and we
 707              * haven't decided which version to use yet send back using version
 708              * 1.0 header: otherwise some clients will ignore it.
 709              */
 710             version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION
 711                                                                : s->version;
 712
 713             /* Construct the record and message headers */
 714             if (!WPACKET_init_static_len(&wpkt,
 715                                          wbuf,
 716                                          ssl_get_max_send_fragment(s)
 717                                          + DTLS1_RT_HEADER_LENGTH,
 718                                          0)
 719                     || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE)
 720                     || !WPACKET_put_bytes_u16(&wpkt, version)
 721                        /*
 722                         * Record sequence number is always the same as in the
 723                         * received ClientHello
 724                         */
 725                     || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE)
 726                        /* End of record, start sub packet for message */
 727                     || !WPACKET_start_sub_packet_u16(&wpkt)
 728                        /* Message type */
 729                     || !WPACKET_put_bytes_u8(&wpkt,
 730                                              DTLS1_MT_HELLO_VERIFY_REQUEST)
 731                        /*
 732                         * Message length - doesn't follow normal TLS convention:
 733                         * the length isn't the last thing in the message header.
 734                         * We'll need to fill this in later when we know the
 735                         * length. Set it to zero for now
 736                         */
 737                     || !WPACKET_put_bytes_u24(&wpkt, 0)
 738                        /*
 739                         * Message sequence number is always 0 for a
 740                         * HelloVerifyRequest
 741                         */
 742                     || !WPACKET_put_bytes_u16(&wpkt, 0)
 743                        /*
 744                         * We never fragment a HelloVerifyRequest, so fragment
 745                         * offset is 0
 746                         */
 747                     || !WPACKET_put_bytes_u24(&wpkt, 0)
 748                        /*
 749                         * Fragment length is the same as message length, but
 750                         * this *is* the last thing in the message header so we
 751                         * can just start a sub-packet. No need to come back
 752                         * later for this one.
 753                         */
 754                     || !WPACKET_start_sub_packet_u24(&wpkt)
 755                        /* Create the actual HelloVerifyRequest body */
 756                     || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen)
 757                        /* Close message body */
 758                     || !WPACKET_close(&wpkt)
 759                        /* Close record body */
 760                     || !WPACKET_close(&wpkt)
 761                     || !WPACKET_get_total_written(&wpkt, &wreclen)
 762                     || !WPACKET_finish(&wpkt)) {
 763                 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
 764                 WPACKET_cleanup(&wpkt);
 765                 /* This is fatal */
 766                 return -1;
 767             }
 768
 769             /*
 770              * Fix up the message len in the message header. Its the same as the
 771              * fragment len which has been filled in by WPACKET, so just copy
 772              * that. Destination for the message len is after the record header
 773              * plus one byte for the message content type. The source is the
 774              * last 3 bytes of the message header
 775              */
 776             memcpy(&wbuf[DTLS1_RT_HEADER_LENGTH + 1],
 777                    &wbuf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3],
 778                    3);
 779
 780             if (s->msg_callback)
 781                 s->msg_callback(1, 0, SSL3_RT_HEADER, buf,
 782                                 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
 783
 784             if ((tmpclient = BIO_ADDR_new()) == NULL) {
 785                 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
 786                 goto end;
 787             }
 788
 789             /*
 790              * This is unnecessary if rbio and wbio are one and the same - but
 791              * maybe they're not. We ignore errors here - some BIOs do not
 792              * support this.
 793              */
 794             if (BIO_dgram_get_peer(rbio, tmpclient) > 0) {
 795                 (void)BIO_dgram_set_peer(wbio, tmpclient);
 796             }
 797             BIO_ADDR_free(tmpclient);
 798             tmpclient = NULL;
 799
 800             /* TODO(size_t): convert this call */
 801             if (BIO_write(wbio, wbuf, wreclen) < (int)wreclen) {
 802                 if (BIO_should_retry(wbio)) {
 803                     /*
 804                      * Non-blocking IO...but we're stateless, so we're just
 805                      * going to drop this packet.
 806                      */
 807                     goto end;
 808                 }
 809                 return -1;
 810             }
 811
 812             if (BIO_flush(wbio) <= 0) {
 813                 if (BIO_should_retry(wbio)) {
 814                     /*
 815                      * Non-blocking IO...but we're stateless, so we're just
 816                      * going to drop this packet.
 817                      */
 818                     goto end;
 819                 }
 820                 return -1;
 821             }
 822         }
 823     } while (next != LISTEN_SUCCESS);
 824
 825     /*
 826      * Set expected sequence numbers to continue the handshake.
 827      */
 828     s->d1->handshake_read_seq = 1;
 829     s->d1->handshake_write_seq = 1;
 830     s->d1->next_handshake_write_seq = 1;
 831     DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq);
 832
 833     /*
 834      * We are doing cookie exchange, so make sure we set that option in the
 835      * SSL object
 836      */
 837     SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
 838
 839     /*
 840      * Tell the state machine that we've done the initial hello verify
 841      * exchange
 842      */
 843     ossl_statem_set_hello_verify_done(s);
 844
 845     /*
 846      * Some BIOs may not support this. If we fail we clear the client address
 847      */
 848     if (BIO_dgram_get_peer(rbio, client) <= 0)
 849         BIO_ADDR_clear(client);
 850
 851     /* Buffer the record in the processed_rcds queue */
 852     if (!dtls_buffer_listen_record(s, reclen, seq, align))
 853         return -1;
 854
 855     ret = 1;
 856  end:
 857     BIO_ADDR_free(tmpclient);
 858     return ret;
 859 }
 860 #endif
 861
 862 static int dtls1_handshake_write(SSL *s)
 863 {
 864     return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
 865 }
 866
 867 int dtls1_shutdown(SSL *s)
 868 {
 869     int ret;
 870 #ifndef OPENSSL_NO_SCTP
 871     BIO *wbio;
 872
 873     wbio = SSL_get_wbio(s);
 874     if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
 875         !(s->shutdown & SSL_SENT_SHUTDOWN)) {
 876         ret = BIO_dgram_sctp_wait_for_dry(wbio);
 877         if (ret < 0)
 878             return -1;
 879
 880         if (ret == 0)
 881             BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1,
 882                      NULL);
 883     }
 884 #endif
 885     ret = ssl3_shutdown(s);
 886 #ifndef OPENSSL_NO_SCTP
 887     BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
 888 #endif
 889     return ret;
 890 }
 891
 892 int dtls1_query_mtu(SSL *s)
 893 {
 894     if (s->d1->link_mtu) {
 895         s->d1->mtu =
 896             s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
 897         s->d1->link_mtu = 0;
 898     }
 899
 900     /* AHA!  Figure out the MTU, and stick to the right size */
 901     if (s->d1->mtu < dtls1_min_mtu(s)) {
 902         if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
 903             s->d1->mtu =
 904                 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
 905
 906             /*
 907              * I've seen the kernel return bogus numbers when it doesn't know
 908              * (initial write), so just make sure we have a reasonable number
 909              */
 910             if (s->d1->mtu < dtls1_min_mtu(s)) {
 911                 /* Set to min mtu */
 912                 s->d1->mtu = dtls1_min_mtu(s);
 913                 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
 914                          (long)s->d1->mtu, NULL);
 915             }
 916         } else
 917             return 0;
 918     }
 919     return 1;
 920 }
 921
 922 static size_t dtls1_link_min_mtu(void)
 923 {
 924     return (g_probable_mtu[(sizeof(g_probable_mtu) /
 925                             sizeof(g_probable_mtu[0])) - 1]);
 926 }
 927
 928 size_t dtls1_min_mtu(SSL *s)
 929 {
 930     return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
 931 }
 932
 933 size_t DTLS_get_data_mtu(const SSL *s)
 934 {
 935     size_t mac_overhead, int_overhead, blocksize, ext_overhead;
 936     const SSL_CIPHER *ciph = SSL_get_current_cipher(s);
 937     size_t mtu = s->d1->mtu;
 938
 939     if (ciph == NULL)
 940         return 0;
 941
 942     if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead,
 943                                  &blocksize, &ext_overhead))
 944         return 0;
 945
 946     if (SSL_READ_ETM(s))
 947         ext_overhead += mac_overhead;
 948     else
 949         int_overhead += mac_overhead;
 950
 951     /* Subtract external overhead (e.g. IV/nonce, separate MAC) */
 952     if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu)
 953         return 0;
 954     mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH;
 955
 956     /* Round encrypted payload down to cipher block size (for CBC etc.)
 957      * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */
 958     if (blocksize)
 959         mtu -= (mtu % blocksize);
 960
 961     /* Subtract internal overhead (e.g. CBC padding len byte) */
 962     if (int_overhead >= mtu)
 963         return 0;
 964     mtu -= int_overhead;
 965
 966     return mtu;
 967 }
 968
 969 void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb)
 970 {
 971     s->d1->timer_cb = cb;
 972 }