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_local.h"
15
16static void get_current_time(struct timeval *t);
17static int dtls1_handshake_write(SSL *s);
18static size_t dtls1_link_min_mtu(void);
19
20/* XDTLS: figure out the right values */
21static const size_t g_probable_mtu[] = { 1500, 512, 256 };
22
23const 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
40const 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
58long 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
67int 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
108static void dtls1_clear_queues(SSL *s)
109{
110 dtls1_clear_received_buffer(s);
111 dtls1_clear_sent_buffer(s);
112}
113
114void 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
126void 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
139void 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
154int 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
206long 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
242void 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
286struct 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
326int 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
344void 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
352void 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
364int 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
389int 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
416static 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
446int 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
862static int dtls1_handshake_write(SSL *s)
863{
864 return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
865}
866
867int 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
892int 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
922static 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
928size_t dtls1_min_mtu(SSL *s)
929{
930 return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
931}
932
933size_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
969void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb)
970{
971 s->d1->timer_cb = cb;
972}
973