ssl/d1_lib.c

   1 /*
   2  * Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (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 <stdio.h>
  11 #define USE_SOCKETS
  12 #include <openssl/objects.h>
  13 #include <openssl/rand.h>
  14 #include "ssl_locl.h"
  15
  16 #if defined(OPENSSL_SYS_VMS)
  17 # include <sys/timeb.h>
  18 #elif defined(OPENSSL_SYS_VXWORKS)
  19 # include <sys/times.h>
  20 #elif !defined(OPENSSL_SYS_WIN32)
  21 # include <sys/time.h>
  22 #endif
  23
  24 static void get_current_time(struct timeval *t);
  25 static int dtls1_set_handshake_header(SSL *s, int type, unsigned long len);
  26 static int dtls1_handshake_write(SSL *s);
  27 static unsigned int dtls1_link_min_mtu(void);
  28
  29 /* XDTLS:  figure out the right values */
  30 static const unsigned int g_probable_mtu[] = { 1500, 512, 256 };
  31
  32 const SSL3_ENC_METHOD DTLSv1_enc_data = {
  33     tls1_enc,
  34     tls1_mac,
  35     tls1_setup_key_block,
  36     tls1_generate_master_secret,
  37     tls1_change_cipher_state,
  38     tls1_final_finish_mac,
  39     TLS1_FINISH_MAC_LENGTH,
  40     TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
  41     TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
  42     tls1_alert_code,
  43     tls1_export_keying_material,
  44     SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV,
  45     DTLS1_HM_HEADER_LENGTH,
  46     dtls1_set_handshake_header,
  47     dtls1_handshake_write
  48 };
  49
  50 const SSL3_ENC_METHOD DTLSv1_2_enc_data = {
  51     tls1_enc,
  52     tls1_mac,
  53     tls1_setup_key_block,
  54     tls1_generate_master_secret,
  55     tls1_change_cipher_state,
  56     tls1_final_finish_mac,
  57     TLS1_FINISH_MAC_LENGTH,
  58     TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE,
  59     TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE,
  60     tls1_alert_code,
  61     tls1_export_keying_material,
  62     SSL_ENC_FLAG_DTLS | SSL_ENC_FLAG_EXPLICIT_IV | SSL_ENC_FLAG_SIGALGS
  63         | SSL_ENC_FLAG_SHA256_PRF | SSL_ENC_FLAG_TLS1_2_CIPHERS,
  64     DTLS1_HM_HEADER_LENGTH,
  65     dtls1_set_handshake_header,
  66     dtls1_handshake_write
  67 };
  68
  69 long dtls1_default_timeout(void)
  70 {
  71     /*
  72      * 2 hours, the 24 hours mentioned in the DTLSv1 spec is way too long for
  73      * http, the cache would over fill
  74      */
  75     return (60 * 60 * 2);
  76 }
  77
  78 int dtls1_new(SSL *s)
  79 {
  80     DTLS1_STATE *d1;
  81
  82     if (!DTLS_RECORD_LAYER_new(&s->rlayer)) {
  83         return 0;
  84     }
  85
  86     if (!ssl3_new(s))
  87         return (0);
  88     if ((d1 = OPENSSL_zalloc(sizeof(*d1))) == NULL) {
  89         ssl3_free(s);
  90         return (0);
  91     }
  92
  93     d1->buffered_messages = pqueue_new();
  94     d1->sent_messages = pqueue_new();
  95
  96     if (s->server) {
  97         d1->cookie_len = sizeof(s->d1->cookie);
  98     }
  99
 100     d1->link_mtu = 0;
 101     d1->mtu = 0;
 102
 103     if (d1->buffered_messages == NULL || d1->sent_messages == NULL) {
 104         pqueue_free(d1->buffered_messages);
 105         pqueue_free(d1->sent_messages);
 106         OPENSSL_free(d1);
 107         ssl3_free(s);
 108         return (0);
 109     }
 110
 111     s->d1 = d1;
 112     s->method->ssl_clear(s);
 113     return (1);
 114 }
 115
 116 static void dtls1_clear_queues(SSL *s)
 117 {
 118     pitem *item = NULL;
 119     hm_fragment *frag = NULL;
 120
 121     while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) {
 122         frag = (hm_fragment *)item->data;
 123         dtls1_hm_fragment_free(frag);
 124         pitem_free(item);
 125     }
 126
 127     while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) {
 128         frag = (hm_fragment *)item->data;
 129         dtls1_hm_fragment_free(frag);
 130         pitem_free(item);
 131     }
 132 }
 133
 134 void dtls1_free(SSL *s)
 135 {
 136     DTLS_RECORD_LAYER_free(&s->rlayer);
 137
 138     ssl3_free(s);
 139
 140     dtls1_clear_queues(s);
 141
 142     pqueue_free(s->d1->buffered_messages);
 143     pqueue_free(s->d1->sent_messages);
 144
 145     OPENSSL_free(s->d1);
 146     s->d1 = NULL;
 147 }
 148
 149 void dtls1_clear(SSL *s)
 150 {
 151     pqueue *buffered_messages;
 152     pqueue *sent_messages;
 153     unsigned int mtu;
 154     unsigned int link_mtu;
 155
 156     DTLS_RECORD_LAYER_clear(&s->rlayer);
 157
 158     if (s->d1) {
 159         buffered_messages = s->d1->buffered_messages;
 160         sent_messages = s->d1->sent_messages;
 161         mtu = s->d1->mtu;
 162         link_mtu = s->d1->link_mtu;
 163
 164         dtls1_clear_queues(s);
 165
 166         memset(s->d1, 0, sizeof(*s->d1));
 167
 168         if (s->server) {
 169             s->d1->cookie_len = sizeof(s->d1->cookie);
 170         }
 171
 172         if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
 173             s->d1->mtu = mtu;
 174             s->d1->link_mtu = link_mtu;
 175         }
 176
 177         s->d1->buffered_messages = buffered_messages;
 178         s->d1->sent_messages = sent_messages;
 179     }
 180
 181     ssl3_clear(s);
 182
 183     if (s->method->version == DTLS_ANY_VERSION)
 184         s->version = DTLS_MAX_VERSION;
 185 #ifndef OPENSSL_NO_DTLS1_METHOD
 186     else if (s->options & SSL_OP_CISCO_ANYCONNECT)
 187         s->client_version = s->version = DTLS1_BAD_VER;
 188 #endif
 189     else
 190         s->version = s->method->version;
 191 }
 192
 193 long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
 194 {
 195     int ret = 0;
 196
 197     switch (cmd) {
 198     case DTLS_CTRL_GET_TIMEOUT:
 199         if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) {
 200             ret = 1;
 201         }
 202         break;
 203     case DTLS_CTRL_HANDLE_TIMEOUT:
 204         ret = dtls1_handle_timeout(s);
 205         break;
 206     case DTLS_CTRL_SET_LINK_MTU:
 207         if (larg < (long)dtls1_link_min_mtu())
 208             return 0;
 209         s->d1->link_mtu = larg;
 210         return 1;
 211     case DTLS_CTRL_GET_LINK_MIN_MTU:
 212         return (long)dtls1_link_min_mtu();
 213     case SSL_CTRL_SET_MTU:
 214         /*
 215          *  We may not have a BIO set yet so can't call dtls1_min_mtu()
 216          *  We'll have to make do with dtls1_link_min_mtu() and max overhead
 217          */
 218         if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
 219             return 0;
 220         s->d1->mtu = larg;
 221         return larg;
 222     default:
 223         ret = ssl3_ctrl(s, cmd, larg, parg);
 224         break;
 225     }
 226     return (ret);
 227 }
 228
 229 void dtls1_start_timer(SSL *s)
 230 {
 231 #ifndef OPENSSL_NO_SCTP
 232     /* Disable timer for SCTP */
 233     if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
 234         memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
 235         return;
 236     }
 237 #endif
 238
 239     /* If timer is not set, initialize duration with 1 second */
 240     if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
 241         s->d1->timeout_duration = 1;
 242     }
 243
 244     /* Set timeout to current time */
 245     get_current_time(&(s->d1->next_timeout));
 246
 247     /* Add duration to current time */
 248     s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
 249     BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
 250              &(s->d1->next_timeout));
 251 }
 252
 253 struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft)
 254 {
 255     struct timeval timenow;
 256
 257     /* If no timeout is set, just return NULL */
 258     if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
 259         return NULL;
 260     }
 261
 262     /* Get current time */
 263     get_current_time(&timenow);
 264
 265     /* If timer already expired, set remaining time to 0 */
 266     if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
 267         (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
 268          s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
 269         memset(timeleft, 0, sizeof(*timeleft));
 270         return timeleft;
 271     }
 272
 273     /* Calculate time left until timer expires */
 274     memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
 275     timeleft->tv_sec -= timenow.tv_sec;
 276     timeleft->tv_usec -= timenow.tv_usec;
 277     if (timeleft->tv_usec < 0) {
 278         timeleft->tv_sec--;
 279         timeleft->tv_usec += 1000000;
 280     }
 281
 282     /*
 283      * If remaining time is less than 15 ms, set it to 0 to prevent issues
 284      * because of small divergences with socket timeouts.
 285      */
 286     if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
 287         memset(timeleft, 0, sizeof(*timeleft));
 288     }
 289
 290     return timeleft;
 291 }
 292
 293 int dtls1_is_timer_expired(SSL *s)
 294 {
 295     struct timeval timeleft;
 296
 297     /* Get time left until timeout, return false if no timer running */
 298     if (dtls1_get_timeout(s, &timeleft) == NULL) {
 299         return 0;
 300     }
 301
 302     /* Return false if timer is not expired yet */
 303     if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
 304         return 0;
 305     }
 306
 307     /* Timer expired, so return true */
 308     return 1;
 309 }
 310
 311 void dtls1_double_timeout(SSL *s)
 312 {
 313     s->d1->timeout_duration *= 2;
 314     if (s->d1->timeout_duration > 60)
 315         s->d1->timeout_duration = 60;
 316     dtls1_start_timer(s);
 317 }
 318
 319 void dtls1_stop_timer(SSL *s)
 320 {
 321     /* Reset everything */
 322     memset(&s->d1->timeout, 0, sizeof(s->d1->timeout));
 323     memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
 324     s->d1->timeout_duration = 1;
 325     BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
 326              &(s->d1->next_timeout));
 327     /* Clear retransmission buffer */
 328     dtls1_clear_record_buffer(s);
 329 }
 330
 331 int dtls1_check_timeout_num(SSL *s)
 332 {
 333     unsigned int mtu;
 334
 335     s->d1->timeout.num_alerts++;
 336
 337     /* Reduce MTU after 2 unsuccessful retransmissions */
 338     if (s->d1->timeout.num_alerts > 2
 339         && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
 340         mtu =
 341             BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
 342         if (mtu < s->d1->mtu)
 343             s->d1->mtu = mtu;
 344     }
 345
 346     if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT) {
 347         /* fail the connection, enough alerts have been sent */
 348         SSLerr(SSL_F_DTLS1_CHECK_TIMEOUT_NUM, SSL_R_READ_TIMEOUT_EXPIRED);
 349         return -1;
 350     }
 351
 352     return 0;
 353 }
 354
 355 int dtls1_handle_timeout(SSL *s)
 356 {
 357     /* if no timer is expired, don't do anything */
 358     if (!dtls1_is_timer_expired(s)) {
 359         return 0;
 360     }
 361
 362     dtls1_double_timeout(s);
 363
 364     if (dtls1_check_timeout_num(s) < 0)
 365         return -1;
 366
 367     s->d1->timeout.read_timeouts++;
 368     if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT) {
 369         s->d1->timeout.read_timeouts = 1;
 370     }
 371 #ifndef OPENSSL_NO_HEARTBEATS
 372     if (s->tlsext_hb_pending) {
 373         s->tlsext_hb_pending = 0;
 374         return dtls1_heartbeat(s);
 375     }
 376 #endif
 377
 378     dtls1_start_timer(s);
 379     return dtls1_retransmit_buffered_messages(s);
 380 }
 381
 382 static void get_current_time(struct timeval *t)
 383 {
 384 #if defined(_WIN32)
 385     SYSTEMTIME st;
 386     union {
 387         unsigned __int64 ul;
 388         FILETIME ft;
 389     } now;
 390
 391     GetSystemTime(&st);
 392     SystemTimeToFileTime(&st, &now.ft);
 393     /* re-bias to 1/1/1970 */
 394 # ifdef  __MINGW32__
 395     now.ul -= 116444736000000000ULL;
 396 # else
 397     /* *INDENT-OFF* */
 398     now.ul -= 116444736000000000UI64;
 399     /* *INDENT-ON* */
 400 # endif
 401     t->tv_sec = (long)(now.ul / 10000000);
 402     t->tv_usec = ((int)(now.ul % 10000000)) / 10;
 403 #elif defined(OPENSSL_SYS_VMS)
 404     struct timeb tb;
 405     ftime(&tb);
 406     t->tv_sec = (long)tb.time;
 407     t->tv_usec = (long)tb.millitm * 1000;
 408 #else
 409     gettimeofday(t, NULL);
 410 #endif
 411 }
 412
 413 #define LISTEN_SUCCESS              2
 414 #define LISTEN_SEND_VERIFY_REQUEST  1
 415
 416 #ifndef OPENSSL_NO_SOCK
 417 int DTLSv1_listen(SSL *s, BIO_ADDR *client)
 418 {
 419     int next, n, ret = 0, clearpkt = 0;
 420     unsigned char cookie[DTLS1_COOKIE_LENGTH];
 421     unsigned char seq[SEQ_NUM_SIZE];
 422     const unsigned char *data;
 423     unsigned char *p, *buf;
 424     unsigned long reclen, fragoff, fraglen, msglen;
 425     unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen;
 426     BIO *rbio, *wbio;
 427     BUF_MEM *bufm;
 428     BIO_ADDR *tmpclient = NULL;
 429     PACKET pkt, msgpkt, msgpayload, session, cookiepkt;
 430
 431     /* Ensure there is no state left over from a previous invocation */
 432     if (!SSL_clear(s))
 433         return -1;
 434
 435     ERR_clear_error();
 436
 437     rbio = SSL_get_rbio(s);
 438     wbio = SSL_get_wbio(s);
 439
 440     if (!rbio || !wbio) {
 441         SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BIO_NOT_SET);
 442         return -1;
 443     }
 444
 445     /*
 446      * We only peek at incoming ClientHello's until we're sure we are going to
 447      * to respond with a HelloVerifyRequest. If its a ClientHello with a valid
 448      * cookie then we leave it in the BIO for accept to handle.
 449      */
 450     BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 1, NULL);
 451
 452     /*
 453      * Note: This check deliberately excludes DTLS1_BAD_VER because that version
 454      * requires the MAC to be calculated *including* the first ClientHello
 455      * (without the cookie). Since DTLSv1_listen is stateless that cannot be
 456      * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via
 457      * SSL_accept)
 458      */
 459     if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) {
 460         SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNSUPPORTED_SSL_VERSION);
 461         return -1;
 462     }
 463
 464     if (s->init_buf == NULL) {
 465         if ((bufm = BUF_MEM_new()) == NULL) {
 466             SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
 467             return -1;
 468         }
 469
 470         if (!BUF_MEM_grow(bufm, SSL3_RT_MAX_PLAIN_LENGTH)) {
 471             BUF_MEM_free(bufm);
 472             SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
 473             return -1;
 474         }
 475         s->init_buf = bufm;
 476     }
 477     buf = (unsigned char *)s->init_buf->data;
 478
 479     do {
 480         /* Get a packet */
 481
 482         clear_sys_error();
 483         /*
 484          * Technically a ClientHello could be SSL3_RT_MAX_PLAIN_LENGTH
 485          * + DTLS1_RT_HEADER_LENGTH bytes long. Normally init_buf does not store
 486          * the record header as well, but we do here. We've set up init_buf to
 487          * be the standard size for simplicity. In practice we shouldn't ever
 488          * receive a ClientHello as long as this. If we do it will get dropped
 489          * in the record length check below.
 490          */
 491         n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
 492
 493         if (n <= 0) {
 494             if (BIO_should_retry(rbio)) {
 495                 /* Non-blocking IO */
 496                 goto end;
 497             }
 498             return -1;
 499         }
 500
 501         /* If we hit any problems we need to clear this packet from the BIO */
 502         clearpkt = 1;
 503
 504         if (!PACKET_buf_init(&pkt, buf, n)) {
 505             SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_INTERNAL_ERROR);
 506             return -1;
 507         }
 508
 509         /*
 510          * Parse the received record. If there are any problems with it we just
 511          * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is
 512          * resilient in the face of invalid records (e.g., invalid formatting,
 513          * length, MAC, etc.).  In general, invalid records SHOULD be silently
 514          * discarded, thus preserving the association; however, an error MAY be
 515          * logged for diagnostic purposes."
 516          */
 517
 518         /* this packet contained a partial record, dump it */
 519         if (n < DTLS1_RT_HEADER_LENGTH) {
 520             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_RECORD_TOO_SMALL);
 521             goto end;
 522         }
 523
 524         if (s->msg_callback)
 525             s->msg_callback(0, 0, SSL3_RT_HEADER, buf,
 526                             DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
 527
 528         /* Get the record header */
 529         if (!PACKET_get_1(&pkt, &rectype)
 530             || !PACKET_get_1(&pkt, &versmajor)) {
 531             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 532             goto end;
 533         }
 534
 535         if (rectype != SSL3_RT_HANDSHAKE) {
 536             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
 537             goto end;
 538         }
 539
 540         /*
 541          * Check record version number. We only check that the major version is
 542          * the same.
 543          */
 544         if (versmajor != DTLS1_VERSION_MAJOR) {
 545             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
 546             goto end;
 547         }
 548
 549         if (!PACKET_forward(&pkt, 1)
 550             /* Save the sequence number: 64 bits, with top 2 bytes = epoch */
 551             || !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE)
 552             || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) {
 553             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 554             goto end;
 555         }
 556         /*
 557          * We allow data remaining at the end of the packet because there could
 558          * be a second record (but we ignore it)
 559          */
 560
 561         /* This is an initial ClientHello so the epoch has to be 0 */
 562         if (seq[0] != 0 || seq[1] != 0) {
 563             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
 564             goto end;
 565         }
 566
 567         /* Get a pointer to the raw message for the later callback */
 568         data = PACKET_data(&msgpkt);
 569
 570         /* Finished processing the record header, now process the message */
 571         if (!PACKET_get_1(&msgpkt, &msgtype)
 572             || !PACKET_get_net_3(&msgpkt, &msglen)
 573             || !PACKET_get_net_2(&msgpkt, &msgseq)
 574             || !PACKET_get_net_3(&msgpkt, &fragoff)
 575             || !PACKET_get_net_3(&msgpkt, &fraglen)
 576             || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen)
 577             || PACKET_remaining(&msgpkt) != 0) {
 578             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 579             goto end;
 580         }
 581
 582         if (msgtype != SSL3_MT_CLIENT_HELLO) {
 583             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_UNEXPECTED_MESSAGE);
 584             goto end;
 585         }
 586
 587         /* Message sequence number can only be 0 or 1 */
 588         if (msgseq > 2) {
 589             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_INVALID_SEQUENCE_NUMBER);
 590             goto end;
 591         }
 592
 593         /*
 594          * We don't support fragment reassembly for ClientHellos whilst
 595          * listening because that would require server side state (which is
 596          * against the whole point of the ClientHello/HelloVerifyRequest
 597          * mechanism). Instead we only look at the first ClientHello fragment
 598          * and require that the cookie must be contained within it.
 599          */
 600         if (fragoff != 0 || fraglen > msglen) {
 601             /* Non initial ClientHello fragment (or bad fragment) */
 602             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_FRAGMENTED_CLIENT_HELLO);
 603             goto end;
 604         }
 605
 606         if (s->msg_callback)
 607             s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data,
 608                             fraglen + DTLS1_HM_HEADER_LENGTH, s,
 609                             s->msg_callback_arg);
 610
 611         if (!PACKET_get_net_2(&msgpayload, &clientvers)) {
 612             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 613             goto end;
 614         }
 615
 616         /*
 617          * Verify client version is supported
 618          */
 619         if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) &&
 620             s->method->version != DTLS_ANY_VERSION) {
 621             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_WRONG_VERSION_NUMBER);
 622             goto end;
 623         }
 624
 625         if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE)
 626             || !PACKET_get_length_prefixed_1(&msgpayload, &session)
 627             || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) {
 628             /*
 629              * Could be malformed or the cookie does not fit within the initial
 630              * ClientHello fragment. Either way we can't handle it.
 631              */
 632             SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_LENGTH_MISMATCH);
 633             goto end;
 634         }
 635
 636         /*
 637          * Check if we have a cookie or not. If not we need to send a
 638          * HelloVerifyRequest.
 639          */
 640         if (PACKET_remaining(&cookiepkt) == 0) {
 641             next = LISTEN_SEND_VERIFY_REQUEST;
 642         } else {
 643             /*
 644              * We have a cookie, so lets check it.
 645              */
 646             if (s->ctx->app_verify_cookie_cb == NULL) {
 647                 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_NO_VERIFY_COOKIE_CALLBACK);
 648                 /* This is fatal */
 649                 return -1;
 650             }
 651             if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt),
 652                                              PACKET_remaining(&cookiepkt)) ==
 653                 0) {
 654                 /*
 655                  * We treat invalid cookies in the same was as no cookie as
 656                  * per RFC6347
 657                  */
 658                 next = LISTEN_SEND_VERIFY_REQUEST;
 659             } else {
 660                 /* Cookie verification succeeded */
 661                 next = LISTEN_SUCCESS;
 662             }
 663         }
 664
 665         if (next == LISTEN_SEND_VERIFY_REQUEST) {
 666             /*
 667              * There was no cookie in the ClientHello so we need to send a
 668              * HelloVerifyRequest. If this fails we do not worry about trying
 669              * to resend, we just drop it.
 670              */
 671
 672             /*
 673              * Dump the read packet, we don't need it any more. Ignore return
 674              * value
 675              */
 676             BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL);
 677             BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
 678             BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 1, NULL);
 679
 680             /* Generate the cookie */
 681             if (s->ctx->app_gen_cookie_cb == NULL ||
 682                 s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 ||
 683                 cookielen > 255) {
 684                 SSLerr(SSL_F_DTLSV1_LISTEN, SSL_R_COOKIE_GEN_CALLBACK_FAILURE);
 685                 /* This is fatal */
 686                 return -1;
 687             }
 688
 689             p = &buf[DTLS1_RT_HEADER_LENGTH];
 690             msglen = dtls_raw_hello_verify_request(p + DTLS1_HM_HEADER_LENGTH,
 691                                                    cookie, cookielen);
 692
 693             *p++ = DTLS1_MT_HELLO_VERIFY_REQUEST;
 694
 695             /* Message length */
 696             l2n3(msglen, p);
 697
 698             /* Message sequence number is always 0 for a HelloVerifyRequest */
 699             s2n(0, p);
 700
 701             /*
 702              * We never fragment a HelloVerifyRequest, so fragment offset is 0
 703              * and fragment length is message length
 704              */
 705             l2n3(0, p);
 706             l2n3(msglen, p);
 707
 708             /* Set reclen equal to length of whole handshake message */
 709             reclen = msglen + DTLS1_HM_HEADER_LENGTH;
 710
 711             /* Add the record header */
 712             p = buf;
 713
 714             *(p++) = SSL3_RT_HANDSHAKE;
 715             /*
 716              * Special case: for hello verify request, client version 1.0 and we
 717              * haven't decided which version to use yet send back using version
 718              * 1.0 header: otherwise some clients will ignore it.
 719              */
 720             if (s->method->version == DTLS_ANY_VERSION) {
 721                 *(p++) = DTLS1_VERSION >> 8;
 722                 *(p++) = DTLS1_VERSION & 0xff;
 723             } else {
 724                 *(p++) = s->version >> 8;
 725                 *(p++) = s->version & 0xff;
 726             }
 727
 728             /*
 729              * Record sequence number is always the same as in the received
 730              * ClientHello
 731              */
 732             memcpy(p, seq, SEQ_NUM_SIZE);
 733             p += SEQ_NUM_SIZE;
 734
 735             /* Length */
 736             s2n(reclen, p);
 737
 738             /*
 739              * Set reclen equal to length of whole record including record
 740              * header
 741              */
 742             reclen += DTLS1_RT_HEADER_LENGTH;
 743
 744             if (s->msg_callback)
 745                 s->msg_callback(1, 0, SSL3_RT_HEADER, buf,
 746                                 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
 747
 748             if ((tmpclient = BIO_ADDR_new()) == NULL) {
 749                 SSLerr(SSL_F_DTLSV1_LISTEN, ERR_R_MALLOC_FAILURE);
 750                 goto end;
 751             }
 752
 753             /*
 754              * This is unnecessary if rbio and wbio are one and the same - but
 755              * maybe they're not. We ignore errors here - some BIOs do not
 756              * support this.
 757              */
 758             if (BIO_dgram_get_peer(rbio, tmpclient) > 0) {
 759                 (void)BIO_dgram_set_peer(wbio, tmpclient);
 760             }
 761             BIO_ADDR_free(tmpclient);
 762             tmpclient = NULL;
 763
 764             if (BIO_write(wbio, buf, reclen) < (int)reclen) {
 765                 if (BIO_should_retry(wbio)) {
 766                     /*
 767                      * Non-blocking IO...but we're stateless, so we're just
 768                      * going to drop this packet.
 769                      */
 770                     goto end;
 771                 }
 772                 return -1;
 773             }
 774
 775             if (BIO_flush(wbio) <= 0) {
 776                 if (BIO_should_retry(wbio)) {
 777                     /*
 778                      * Non-blocking IO...but we're stateless, so we're just
 779                      * going to drop this packet.
 780                      */
 781                     goto end;
 782                 }
 783                 return -1;
 784             }
 785         }
 786     } while (next != LISTEN_SUCCESS);
 787
 788     /*
 789      * Set expected sequence numbers to continue the handshake.
 790      */
 791     s->d1->handshake_read_seq = 1;
 792     s->d1->handshake_write_seq = 1;
 793     s->d1->next_handshake_write_seq = 1;
 794     DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq);
 795
 796     /*
 797      * We are doing cookie exchange, so make sure we set that option in the
 798      * SSL object
 799      */
 800     SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
 801
 802     /*
 803      * Tell the state machine that we've done the initial hello verify
 804      * exchange
 805      */
 806     ossl_statem_set_hello_verify_done(s);
 807
 808     /*
 809      * Some BIOs may not support this. If we fail we clear the client address
 810      */
 811     if (BIO_dgram_get_peer(rbio, client) <= 0)
 812         BIO_ADDR_clear(client);
 813
 814     ret = 1;
 815     clearpkt = 0;
 816  end:
 817     BIO_ADDR_free(tmpclient);
 818     BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_PEEK_MODE, 0, NULL);
 819     if (clearpkt) {
 820         /* Dump this packet. Ignore return value */
 821         BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH);
 822     }
 823     return ret;
 824 }
 825 #endif
 826
 827 static int dtls1_set_handshake_header(SSL *s, int htype, unsigned long len)
 828 {
 829     dtls1_set_message_header(s, htype, len, 0, len);
 830     s->init_num = (int)len + DTLS1_HM_HEADER_LENGTH;
 831     s->init_off = 0;
 832     /* Buffer the message to handle re-xmits */
 833
 834     if (!dtls1_buffer_message(s, 0))
 835         return 0;
 836
 837     return 1;
 838 }
 839
 840 static int dtls1_handshake_write(SSL *s)
 841 {
 842     return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
 843 }
 844
 845 #ifndef OPENSSL_NO_HEARTBEATS
 846
 847 # define HEARTBEAT_SIZE(payload, padding) ( \
 848     1 /* heartbeat type */ + \
 849     2 /* heartbeat length */ + \
 850     (payload) + (padding))
 851
 852 # define HEARTBEAT_SIZE_STD(payload) HEARTBEAT_SIZE(payload, 16)
 853
 854 int dtls1_process_heartbeat(SSL *s, unsigned char *p, unsigned int length)
 855 {
 856     unsigned char *pl;
 857     unsigned short hbtype;
 858     unsigned int payload;
 859     unsigned int padding = 16;  /* Use minimum padding */
 860
 861     if (s->msg_callback)
 862         s->msg_callback(0, s->version, DTLS1_RT_HEARTBEAT,
 863                         p, length, s, s->msg_callback_arg);
 864
 865     /* Read type and payload length */
 866     if (HEARTBEAT_SIZE_STD(0) > length)
 867         return 0;               /* silently discard */
 868     if (length > SSL3_RT_MAX_PLAIN_LENGTH)
 869         return 0;               /* silently discard per RFC 6520 sec. 4 */
 870
 871     hbtype = *p++;
 872     n2s(p, payload);
 873     if (HEARTBEAT_SIZE_STD(payload) > length)
 874         return 0;               /* silently discard per RFC 6520 sec. 4 */
 875     pl = p;
 876
 877     if (hbtype == TLS1_HB_REQUEST) {
 878         unsigned char *buffer, *bp;
 879         unsigned int write_length = HEARTBEAT_SIZE(payload, padding);
 880         int r;
 881
 882         if (write_length > SSL3_RT_MAX_PLAIN_LENGTH)
 883             return 0;
 884
 885         /* Allocate memory for the response. */
 886         buffer = OPENSSL_malloc(write_length);
 887         if (buffer == NULL)
 888             return -1;
 889         bp = buffer;
 890
 891         /* Enter response type, length and copy payload */
 892         *bp++ = TLS1_HB_RESPONSE;
 893         s2n(payload, bp);
 894         memcpy(bp, pl, payload);
 895         bp += payload;
 896         /* Random padding */
 897         if (RAND_bytes(bp, padding) <= 0) {
 898             OPENSSL_free(buffer);
 899             return -1;
 900         }
 901
 902         r = dtls1_write_bytes(s, DTLS1_RT_HEARTBEAT, buffer, write_length);
 903
 904         if (r >= 0 && s->msg_callback)
 905             s->msg_callback(1, s->version, DTLS1_RT_HEARTBEAT,
 906                             buffer, write_length, s, s->msg_callback_arg);
 907
 908         OPENSSL_free(buffer);
 909
 910         if (r < 0)
 911             return r;
 912     } else if (hbtype == TLS1_HB_RESPONSE) {
 913         unsigned int seq;
 914
 915         /*
 916          * We only send sequence numbers (2 bytes unsigned int), and 16
 917          * random bytes, so we just try to read the sequence number
 918          */
 919         n2s(pl, seq);
 920
 921         if (payload == 18 && seq == s->tlsext_hb_seq) {
 922             dtls1_stop_timer(s);
 923             s->tlsext_hb_seq++;
 924             s->tlsext_hb_pending = 0;
 925         }
 926     }
 927
 928     return 0;
 929 }
 930
 931 int dtls1_heartbeat(SSL *s)
 932 {
 933     unsigned char *buf, *p;
 934     int ret = -1;
 935     unsigned int payload = 18;  /* Sequence number + random bytes */
 936     unsigned int padding = 16;  /* Use minimum padding */
 937     unsigned int size;
 938
 939     /* Only send if peer supports and accepts HB requests... */
 940     if (!(s->tlsext_heartbeat & SSL_DTLSEXT_HB_ENABLED) ||
 941         s->tlsext_heartbeat & SSL_DTLSEXT_HB_DONT_SEND_REQUESTS) {
 942         SSLerr(SSL_F_DTLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PEER_DOESNT_ACCEPT);
 943         return -1;
 944     }
 945
 946     /* ...and there is none in flight yet... */
 947     if (s->tlsext_hb_pending) {
 948         SSLerr(SSL_F_DTLS1_HEARTBEAT, SSL_R_TLS_HEARTBEAT_PENDING);
 949         return -1;
 950     }
 951
 952     /* ...and no handshake in progress. */
 953     if (SSL_in_init(s) || ossl_statem_get_in_handshake(s)) {
 954         SSLerr(SSL_F_DTLS1_HEARTBEAT, SSL_R_UNEXPECTED_MESSAGE);
 955         return -1;
 956     }
 957
 958     /*-
 959      * Create HeartBeat message, we just use a sequence number
 960      * as payload to distinguish different messages and add
 961      * some random stuff.
 962      */
 963     size = HEARTBEAT_SIZE(payload, padding);
 964     buf = OPENSSL_malloc(size);
 965     if (buf == NULL) {
 966         SSLerr(SSL_F_DTLS1_HEARTBEAT, ERR_R_MALLOC_FAILURE);
 967         return -1;
 968     }
 969     p = buf;
 970     /* Message Type */
 971     *p++ = TLS1_HB_REQUEST;
 972     /* Payload length (18 bytes here) */
 973     s2n(payload, p);
 974     /* Sequence number */
 975     s2n(s->tlsext_hb_seq, p);
 976     /* 16 random bytes */
 977     if (RAND_bytes(p, 16) <= 0) {
 978         SSLerr(SSL_F_DTLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
 979         goto err;
 980     }
 981     p += 16;
 982     /* Random padding */
 983     if (RAND_bytes(p, padding) <= 0) {
 984         SSLerr(SSL_F_DTLS1_HEARTBEAT, ERR_R_INTERNAL_ERROR);
 985         goto err;
 986     }
 987
 988     ret = dtls1_write_bytes(s, DTLS1_RT_HEARTBEAT, buf, size);
 989     if (ret >= 0) {
 990         if (s->msg_callback)
 991             s->msg_callback(1, s->version, DTLS1_RT_HEARTBEAT,
 992                             buf, size, s, s->msg_callback_arg);
 993
 994         dtls1_start_timer(s);
 995         s->tlsext_hb_pending = 1;
 996     }
 997
 998  err:
 999     OPENSSL_free(buf);
1000
1001     return ret;
1002 }
1003 #endif
1004
1005 int dtls1_shutdown(SSL *s)
1006 {
1007     int ret;
1008 #ifndef OPENSSL_NO_SCTP
1009     BIO *wbio;
1010
1011     wbio = SSL_get_wbio(s);
1012     if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
1013         !(s->shutdown & SSL_SENT_SHUTDOWN)) {
1014         ret = BIO_dgram_sctp_wait_for_dry(wbio);
1015         if (ret < 0)
1016             return -1;
1017
1018         if (ret == 0)
1019             BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1,
1020                      NULL);
1021     }
1022 #endif
1023     ret = ssl3_shutdown(s);
1024 #ifndef OPENSSL_NO_SCTP
1025     BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
1026 #endif
1027     return ret;
1028 }
1029
1030 int dtls1_query_mtu(SSL *s)
1031 {
1032     if (s->d1->link_mtu) {
1033         s->d1->mtu =
1034             s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
1035         s->d1->link_mtu = 0;
1036     }
1037
1038     /* AHA!  Figure out the MTU, and stick to the right size */
1039     if (s->d1->mtu < dtls1_min_mtu(s)) {
1040         if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
1041             s->d1->mtu =
1042                 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
1043
1044             /*
1045              * I've seen the kernel return bogus numbers when it doesn't know
1046              * (initial write), so just make sure we have a reasonable number
1047              */
1048             if (s->d1->mtu < dtls1_min_mtu(s)) {
1049                 /* Set to min mtu */
1050                 s->d1->mtu = dtls1_min_mtu(s);
1051                 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
1052                          s->d1->mtu, NULL);
1053             }
1054         } else
1055             return 0;
1056     }
1057     return 1;
1058 }
1059
1060 static unsigned int dtls1_link_min_mtu(void)
1061 {
1062     return (g_probable_mtu[(sizeof(g_probable_mtu) /
1063                             sizeof(g_probable_mtu[0])) - 1]);
1064 }
1065
1066 unsigned int dtls1_min_mtu(SSL *s)
1067 {
1068     return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
1069 }