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1 /*
2  * Copyright 2005-2021 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 
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 
dtls1_default_timeout(void)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 
dtls1_new(SSL * s)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 
dtls1_clear_queues(SSL * s)108 static void dtls1_clear_queues(SSL *s)
109 {
110     dtls1_clear_received_buffer(s);
111     dtls1_clear_sent_buffer(s);
112 }
113 
dtls1_clear_received_buffer(SSL * s)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 
dtls1_clear_sent_buffer(SSL * s)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 
dtls1_free(SSL * s)139 void dtls1_free(SSL *s)
140 {
141     DTLS_RECORD_LAYER_free(&s->rlayer);
142 
143     ssl3_free(s);
144 
145     if (s->d1 != NULL) {
146         dtls1_clear_queues(s);
147         pqueue_free(s->d1->buffered_messages);
148         pqueue_free(s->d1->sent_messages);
149     }
150 
151     OPENSSL_free(s->d1);
152     s->d1 = NULL;
153 }
154 
dtls1_clear(SSL * s)155 int dtls1_clear(SSL *s)
156 {
157     pqueue *buffered_messages;
158     pqueue *sent_messages;
159     size_t mtu;
160     size_t link_mtu;
161 
162     DTLS_RECORD_LAYER_clear(&s->rlayer);
163 
164     if (s->d1) {
165         DTLS_timer_cb timer_cb = s->d1->timer_cb;
166 
167         buffered_messages = s->d1->buffered_messages;
168         sent_messages = s->d1->sent_messages;
169         mtu = s->d1->mtu;
170         link_mtu = s->d1->link_mtu;
171 
172         dtls1_clear_queues(s);
173 
174         memset(s->d1, 0, sizeof(*s->d1));
175 
176         /* Restore the timer callback from previous state */
177         s->d1->timer_cb = timer_cb;
178 
179         if (s->server) {
180             s->d1->cookie_len = sizeof(s->d1->cookie);
181         }
182 
183         if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU) {
184             s->d1->mtu = mtu;
185             s->d1->link_mtu = link_mtu;
186         }
187 
188         s->d1->buffered_messages = buffered_messages;
189         s->d1->sent_messages = sent_messages;
190     }
191 
192     if (!ssl3_clear(s))
193         return 0;
194 
195     if (s->method->version == DTLS_ANY_VERSION)
196         s->version = DTLS_MAX_VERSION_INTERNAL;
197 #ifndef OPENSSL_NO_DTLS1_METHOD
198     else if (s->options & SSL_OP_CISCO_ANYCONNECT)
199         s->client_version = s->version = DTLS1_BAD_VER;
200 #endif
201     else
202         s->version = s->method->version;
203 
204     return 1;
205 }
206 
dtls1_ctrl(SSL * s,int cmd,long larg,void * parg)207 long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
208 {
209     int ret = 0;
210 
211     switch (cmd) {
212     case DTLS_CTRL_GET_TIMEOUT:
213         if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) {
214             ret = 1;
215         }
216         break;
217     case DTLS_CTRL_HANDLE_TIMEOUT:
218         ret = dtls1_handle_timeout(s);
219         break;
220     case DTLS_CTRL_SET_LINK_MTU:
221         if (larg < (long)dtls1_link_min_mtu())
222             return 0;
223         s->d1->link_mtu = larg;
224         return 1;
225     case DTLS_CTRL_GET_LINK_MIN_MTU:
226         return (long)dtls1_link_min_mtu();
227     case SSL_CTRL_SET_MTU:
228         /*
229          *  We may not have a BIO set yet so can't call dtls1_min_mtu()
230          *  We'll have to make do with dtls1_link_min_mtu() and max overhead
231          */
232         if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
233             return 0;
234         s->d1->mtu = larg;
235         return larg;
236     default:
237         ret = ssl3_ctrl(s, cmd, larg, parg);
238         break;
239     }
240     return ret;
241 }
242 
dtls1_start_timer(SSL * s)243 void dtls1_start_timer(SSL *s)
244 {
245     unsigned int sec, usec;
246 
247 #ifndef OPENSSL_NO_SCTP
248     /* Disable timer for SCTP */
249     if (BIO_dgram_is_sctp(SSL_get_wbio(s))) {
250         memset(&s->d1->next_timeout, 0, sizeof(s->d1->next_timeout));
251         return;
252     }
253 #endif
254 
255     /*
256      * If timer is not set, initialize duration with 1 second or
257      * a user-specified value if the timer callback is installed.
258      */
259     if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
260 
261         if (s->d1->timer_cb != NULL)
262             s->d1->timeout_duration_us = s->d1->timer_cb(s, 0);
263         else
264             s->d1->timeout_duration_us = 1000000;
265     }
266 
267     /* Set timeout to current time */
268     get_current_time(&(s->d1->next_timeout));
269 
270     /* Add duration to current time */
271 
272     sec  = s->d1->timeout_duration_us / 1000000;
273     usec = s->d1->timeout_duration_us - (sec * 1000000);
274 
275     s->d1->next_timeout.tv_sec  += sec;
276     s->d1->next_timeout.tv_usec += usec;
277 
278     if (s->d1->next_timeout.tv_usec >= 1000000) {
279         s->d1->next_timeout.tv_sec++;
280         s->d1->next_timeout.tv_usec -= 1000000;
281     }
282 
283     BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
284              &(s->d1->next_timeout));
285 }
286 
dtls1_get_timeout(SSL * s,struct timeval * timeleft)287 struct timeval *dtls1_get_timeout(SSL *s, struct timeval *timeleft)
288 {
289     struct timeval timenow;
290 
291     /* If no timeout is set, just return NULL */
292     if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) {
293         return NULL;
294     }
295 
296     /* Get current time */
297     get_current_time(&timenow);
298 
299     /* If timer already expired, set remaining time to 0 */
300     if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
301         (s->d1->next_timeout.tv_sec == timenow.tv_sec &&
302          s->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
303         memset(timeleft, 0, sizeof(*timeleft));
304         return timeleft;
305     }
306 
307     /* Calculate time left until timer expires */
308     memcpy(timeleft, &(s->d1->next_timeout), sizeof(struct timeval));
309     timeleft->tv_sec -= timenow.tv_sec;
310     timeleft->tv_usec -= timenow.tv_usec;
311     if (timeleft->tv_usec < 0) {
312         timeleft->tv_sec--;
313         timeleft->tv_usec += 1000000;
314     }
315 
316     /*
317      * If remaining time is less than 15 ms, set it to 0 to prevent issues
318      * because of small divergences with socket timeouts.
319      */
320     if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000) {
321         memset(timeleft, 0, sizeof(*timeleft));
322     }
323 
324     return timeleft;
325 }
326 
dtls1_is_timer_expired(SSL * s)327 int dtls1_is_timer_expired(SSL *s)
328 {
329     struct timeval timeleft;
330 
331     /* Get time left until timeout, return false if no timer running */
332     if (dtls1_get_timeout(s, &timeleft) == NULL) {
333         return 0;
334     }
335 
336     /* Return false if timer is not expired yet */
337     if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
338         return 0;
339     }
340 
341     /* Timer expired, so return true */
342     return 1;
343 }
344 
dtls1_double_timeout(SSL * s)345 static void dtls1_double_timeout(SSL *s)
346 {
347     s->d1->timeout_duration_us *= 2;
348     if (s->d1->timeout_duration_us > 60000000)
349         s->d1->timeout_duration_us = 60000000;
350 }
351 
dtls1_stop_timer(SSL * s)352 void dtls1_stop_timer(SSL *s)
353 {
354     /* Reset everything */
355     s->d1->timeout_num_alerts = 0;
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 
dtls1_check_timeout_num(SSL * s)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, SSL_R_READ_TIMEOUT_EXPIRED);
382         return -1;
383     }
384 
385     return 0;
386 }
387 
dtls1_handle_timeout(SSL * s)388 int dtls1_handle_timeout(SSL *s)
389 {
390     /* if no timer is expired, don't do anything */
391     if (!dtls1_is_timer_expired(s)) {
392         return 0;
393     }
394 
395     if (s->d1->timer_cb != NULL)
396         s->d1->timeout_duration_us = s->d1->timer_cb(s, s->d1->timeout_duration_us);
397     else
398         dtls1_double_timeout(s);
399 
400     if (dtls1_check_timeout_num(s) < 0) {
401         /* SSLfatal() already called */
402         return -1;
403     }
404 
405     dtls1_start_timer(s);
406     /* Calls SSLfatal() if required */
407     return dtls1_retransmit_buffered_messages(s);
408 }
409 
get_current_time(struct timeval * t)410 static void get_current_time(struct timeval *t)
411 {
412 #if defined(_WIN32)
413     SYSTEMTIME st;
414     union {
415         unsigned __int64 ul;
416         FILETIME ft;
417     } now;
418 
419     GetSystemTime(&st);
420     SystemTimeToFileTime(&st, &now.ft);
421     /* re-bias to 1/1/1970 */
422 # ifdef  __MINGW32__
423     now.ul -= 116444736000000000ULL;
424 # else
425     /* *INDENT-OFF* */
426     now.ul -= 116444736000000000UI64;
427     /* *INDENT-ON* */
428 # endif
429     t->tv_sec = (long)(now.ul / 10000000);
430     t->tv_usec = ((int)(now.ul % 10000000)) / 10;
431 #else
432     gettimeofday(t, NULL);
433 #endif
434 }
435 
436 #define LISTEN_SUCCESS              2
437 #define LISTEN_SEND_VERIFY_REQUEST  1
438 
439 #ifndef OPENSSL_NO_SOCK
DTLSv1_listen(SSL * s,BIO_ADDR * client)440 int DTLSv1_listen(SSL *s, BIO_ADDR *client)
441 {
442     int next, n, ret = 0;
443     unsigned char cookie[DTLS1_COOKIE_LENGTH];
444     unsigned char seq[SEQ_NUM_SIZE];
445     const unsigned char *data;
446     unsigned char *buf, *wbuf;
447     size_t fragoff, fraglen, msglen, reclen, align = 0;
448     unsigned int rectype, versmajor, msgseq, msgtype, clientvers, cookielen;
449     BIO *rbio, *wbio;
450     BIO_ADDR *tmpclient = NULL;
451     PACKET pkt, msgpkt, msgpayload, session, cookiepkt;
452 
453     if (s->handshake_func == NULL) {
454         /* Not properly initialized yet */
455         SSL_set_accept_state(s);
456     }
457 
458     /* Ensure there is no state left over from a previous invocation */
459     if (!SSL_clear(s))
460         return -1;
461 
462     ERR_clear_error();
463 
464     rbio = SSL_get_rbio(s);
465     wbio = SSL_get_wbio(s);
466 
467     if (!rbio || !wbio) {
468         ERR_raise(ERR_LIB_SSL, SSL_R_BIO_NOT_SET);
469         return -1;
470     }
471 
472     /*
473      * Note: This check deliberately excludes DTLS1_BAD_VER because that version
474      * requires the MAC to be calculated *including* the first ClientHello
475      * (without the cookie). Since DTLSv1_listen is stateless that cannot be
476      * supported. DTLS1_BAD_VER must use cookies in a stateful manner (e.g. via
477      * SSL_accept)
478      */
479     if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00)) {
480         ERR_raise(ERR_LIB_SSL, SSL_R_UNSUPPORTED_SSL_VERSION);
481         return -1;
482     }
483 
484     if (!ssl3_setup_buffers(s)) {
485         /* ERR_raise() already called */
486         return -1;
487     }
488     buf = RECORD_LAYER_get_rbuf(&s->rlayer)->buf;
489     wbuf = RECORD_LAYER_get_wbuf(&s->rlayer)[0].buf;
490 #if defined(SSL3_ALIGN_PAYLOAD)
491 # if SSL3_ALIGN_PAYLOAD != 0
492     /*
493      * Using SSL3_RT_HEADER_LENGTH here instead of DTLS1_RT_HEADER_LENGTH for
494      * consistency with ssl3_read_n. In practice it should make no difference
495      * for sensible values of SSL3_ALIGN_PAYLOAD because the difference between
496      * SSL3_RT_HEADER_LENGTH and DTLS1_RT_HEADER_LENGTH is exactly 8
497      */
498     align = (size_t)buf + SSL3_RT_HEADER_LENGTH;
499     align = SSL3_ALIGN_PAYLOAD - 1 - ((align - 1) % SSL3_ALIGN_PAYLOAD);
500 # endif
501 #endif
502     buf += align;
503 
504     do {
505         /* Get a packet */
506 
507         clear_sys_error();
508         n = BIO_read(rbio, buf, SSL3_RT_MAX_PLAIN_LENGTH
509                                 + DTLS1_RT_HEADER_LENGTH);
510         if (n <= 0) {
511             if (BIO_should_retry(rbio)) {
512                 /* Non-blocking IO */
513                 goto end;
514             }
515             return -1;
516         }
517 
518         if (!PACKET_buf_init(&pkt, buf, n)) {
519             ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);
520             return -1;
521         }
522 
523         /*
524          * Parse the received record. If there are any problems with it we just
525          * dump it - with no alert. RFC6347 says this "Unlike TLS, DTLS is
526          * resilient in the face of invalid records (e.g., invalid formatting,
527          * length, MAC, etc.).  In general, invalid records SHOULD be silently
528          * discarded, thus preserving the association; however, an error MAY be
529          * logged for diagnostic purposes."
530          */
531 
532         /* this packet contained a partial record, dump it */
533         if (n < DTLS1_RT_HEADER_LENGTH) {
534             ERR_raise(ERR_LIB_SSL, SSL_R_RECORD_TOO_SMALL);
535             goto end;
536         }
537 
538         if (s->msg_callback)
539             s->msg_callback(0, 0, SSL3_RT_HEADER, buf,
540                             DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
541 
542         /* Get the record header */
543         if (!PACKET_get_1(&pkt, &rectype)
544             || !PACKET_get_1(&pkt, &versmajor)) {
545             ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
546             goto end;
547         }
548 
549         if (rectype != SSL3_RT_HANDSHAKE) {
550             ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE);
551             goto end;
552         }
553 
554         /*
555          * Check record version number. We only check that the major version is
556          * the same.
557          */
558         if (versmajor != DTLS1_VERSION_MAJOR) {
559             ERR_raise(ERR_LIB_SSL, SSL_R_BAD_PROTOCOL_VERSION_NUMBER);
560             goto end;
561         }
562 
563         if (!PACKET_forward(&pkt, 1)
564             /* Save the sequence number: 64 bits, with top 2 bytes = epoch */
565             || !PACKET_copy_bytes(&pkt, seq, SEQ_NUM_SIZE)
566             || !PACKET_get_length_prefixed_2(&pkt, &msgpkt)) {
567             ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
568             goto end;
569         }
570         reclen = PACKET_remaining(&msgpkt);
571         /*
572          * We allow data remaining at the end of the packet because there could
573          * be a second record (but we ignore it)
574          */
575 
576         /* This is an initial ClientHello so the epoch has to be 0 */
577         if (seq[0] != 0 || seq[1] != 0) {
578             ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE);
579             goto end;
580         }
581 
582         /* Get a pointer to the raw message for the later callback */
583         data = PACKET_data(&msgpkt);
584 
585         /* Finished processing the record header, now process the message */
586         if (!PACKET_get_1(&msgpkt, &msgtype)
587             || !PACKET_get_net_3_len(&msgpkt, &msglen)
588             || !PACKET_get_net_2(&msgpkt, &msgseq)
589             || !PACKET_get_net_3_len(&msgpkt, &fragoff)
590             || !PACKET_get_net_3_len(&msgpkt, &fraglen)
591             || !PACKET_get_sub_packet(&msgpkt, &msgpayload, fraglen)
592             || PACKET_remaining(&msgpkt) != 0) {
593             ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
594             goto end;
595         }
596 
597         if (msgtype != SSL3_MT_CLIENT_HELLO) {
598             ERR_raise(ERR_LIB_SSL, SSL_R_UNEXPECTED_MESSAGE);
599             goto end;
600         }
601 
602         /* Message sequence number can only be 0 or 1 */
603         if (msgseq > 2) {
604             ERR_raise(ERR_LIB_SSL, SSL_R_INVALID_SEQUENCE_NUMBER);
605             goto end;
606         }
607 
608         /*
609          * We don't support fragment reassembly for ClientHellos whilst
610          * listening because that would require server side state (which is
611          * against the whole point of the ClientHello/HelloVerifyRequest
612          * mechanism). Instead we only look at the first ClientHello fragment
613          * and require that the cookie must be contained within it.
614          */
615         if (fragoff != 0 || fraglen > msglen) {
616             /* Non initial ClientHello fragment (or bad fragment) */
617             ERR_raise(ERR_LIB_SSL, SSL_R_FRAGMENTED_CLIENT_HELLO);
618             goto end;
619         }
620 
621         if (s->msg_callback)
622             s->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, data,
623                             fraglen + DTLS1_HM_HEADER_LENGTH, s,
624                             s->msg_callback_arg);
625 
626         if (!PACKET_get_net_2(&msgpayload, &clientvers)) {
627             ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
628             goto end;
629         }
630 
631         /*
632          * Verify client version is supported
633          */
634         if (DTLS_VERSION_LT(clientvers, (unsigned int)s->method->version) &&
635             s->method->version != DTLS_ANY_VERSION) {
636             ERR_raise(ERR_LIB_SSL, SSL_R_WRONG_VERSION_NUMBER);
637             goto end;
638         }
639 
640         if (!PACKET_forward(&msgpayload, SSL3_RANDOM_SIZE)
641             || !PACKET_get_length_prefixed_1(&msgpayload, &session)
642             || !PACKET_get_length_prefixed_1(&msgpayload, &cookiepkt)) {
643             /*
644              * Could be malformed or the cookie does not fit within the initial
645              * ClientHello fragment. Either way we can't handle it.
646              */
647             ERR_raise(ERR_LIB_SSL, SSL_R_LENGTH_MISMATCH);
648             goto end;
649         }
650 
651         /*
652          * Check if we have a cookie or not. If not we need to send a
653          * HelloVerifyRequest.
654          */
655         if (PACKET_remaining(&cookiepkt) == 0) {
656             next = LISTEN_SEND_VERIFY_REQUEST;
657         } else {
658             /*
659              * We have a cookie, so lets check it.
660              */
661             if (s->ctx->app_verify_cookie_cb == NULL) {
662                 ERR_raise(ERR_LIB_SSL, SSL_R_NO_VERIFY_COOKIE_CALLBACK);
663                 /* This is fatal */
664                 return -1;
665             }
666             if (s->ctx->app_verify_cookie_cb(s, PACKET_data(&cookiepkt),
667                     (unsigned int)PACKET_remaining(&cookiepkt)) == 0) {
668                 /*
669                  * We treat invalid cookies in the same was as no cookie as
670                  * per RFC6347
671                  */
672                 next = LISTEN_SEND_VERIFY_REQUEST;
673             } else {
674                 /* Cookie verification succeeded */
675                 next = LISTEN_SUCCESS;
676             }
677         }
678 
679         if (next == LISTEN_SEND_VERIFY_REQUEST) {
680             WPACKET wpkt;
681             unsigned int version;
682             size_t wreclen;
683 
684             /*
685              * There was no cookie in the ClientHello so we need to send a
686              * HelloVerifyRequest. If this fails we do not worry about trying
687              * to resend, we just drop it.
688              */
689 
690             /* Generate the cookie */
691             if (s->ctx->app_gen_cookie_cb == NULL ||
692                 s->ctx->app_gen_cookie_cb(s, cookie, &cookielen) == 0 ||
693                 cookielen > 255) {
694                 ERR_raise(ERR_LIB_SSL, SSL_R_COOKIE_GEN_CALLBACK_FAILURE);
695                 /* This is fatal */
696                 return -1;
697             }
698 
699             /*
700              * Special case: for hello verify request, client version 1.0 and we
701              * haven't decided which version to use yet send back using version
702              * 1.0 header: otherwise some clients will ignore it.
703              */
704             version = (s->method->version == DTLS_ANY_VERSION) ? DTLS1_VERSION
705                                                                : s->version;
706 
707             /* Construct the record and message headers */
708             if (!WPACKET_init_static_len(&wpkt,
709                                          wbuf,
710                                          ssl_get_max_send_fragment(s)
711                                          + DTLS1_RT_HEADER_LENGTH,
712                                          0)
713                     || !WPACKET_put_bytes_u8(&wpkt, SSL3_RT_HANDSHAKE)
714                     || !WPACKET_put_bytes_u16(&wpkt, version)
715                        /*
716                         * Record sequence number is always the same as in the
717                         * received ClientHello
718                         */
719                     || !WPACKET_memcpy(&wpkt, seq, SEQ_NUM_SIZE)
720                        /* End of record, start sub packet for message */
721                     || !WPACKET_start_sub_packet_u16(&wpkt)
722                        /* Message type */
723                     || !WPACKET_put_bytes_u8(&wpkt,
724                                              DTLS1_MT_HELLO_VERIFY_REQUEST)
725                        /*
726                         * Message length - doesn't follow normal TLS convention:
727                         * the length isn't the last thing in the message header.
728                         * We'll need to fill this in later when we know the
729                         * length. Set it to zero for now
730                         */
731                     || !WPACKET_put_bytes_u24(&wpkt, 0)
732                        /*
733                         * Message sequence number is always 0 for a
734                         * HelloVerifyRequest
735                         */
736                     || !WPACKET_put_bytes_u16(&wpkt, 0)
737                        /*
738                         * We never fragment a HelloVerifyRequest, so fragment
739                         * offset is 0
740                         */
741                     || !WPACKET_put_bytes_u24(&wpkt, 0)
742                        /*
743                         * Fragment length is the same as message length, but
744                         * this *is* the last thing in the message header so we
745                         * can just start a sub-packet. No need to come back
746                         * later for this one.
747                         */
748                     || !WPACKET_start_sub_packet_u24(&wpkt)
749                        /* Create the actual HelloVerifyRequest body */
750                     || !dtls_raw_hello_verify_request(&wpkt, cookie, cookielen)
751                        /* Close message body */
752                     || !WPACKET_close(&wpkt)
753                        /* Close record body */
754                     || !WPACKET_close(&wpkt)
755                     || !WPACKET_get_total_written(&wpkt, &wreclen)
756                     || !WPACKET_finish(&wpkt)) {
757                 ERR_raise(ERR_LIB_SSL, ERR_R_INTERNAL_ERROR);
758                 WPACKET_cleanup(&wpkt);
759                 /* This is fatal */
760                 return -1;
761             }
762 
763             /*
764              * Fix up the message len in the message header. Its the same as the
765              * fragment len which has been filled in by WPACKET, so just copy
766              * that. Destination for the message len is after the record header
767              * plus one byte for the message content type. The source is the
768              * last 3 bytes of the message header
769              */
770             memcpy(&wbuf[DTLS1_RT_HEADER_LENGTH + 1],
771                    &wbuf[DTLS1_RT_HEADER_LENGTH + DTLS1_HM_HEADER_LENGTH - 3],
772                    3);
773 
774             if (s->msg_callback)
775                 s->msg_callback(1, 0, SSL3_RT_HEADER, buf,
776                                 DTLS1_RT_HEADER_LENGTH, s, s->msg_callback_arg);
777 
778             if ((tmpclient = BIO_ADDR_new()) == NULL) {
779                 ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
780                 goto end;
781             }
782 
783             /*
784              * This is unnecessary if rbio and wbio are one and the same - but
785              * maybe they're not. We ignore errors here - some BIOs do not
786              * support this.
787              */
788             if (BIO_dgram_get_peer(rbio, tmpclient) > 0) {
789                 (void)BIO_dgram_set_peer(wbio, tmpclient);
790             }
791             BIO_ADDR_free(tmpclient);
792             tmpclient = NULL;
793 
794             if (BIO_write(wbio, wbuf, wreclen) < (int)wreclen) {
795                 if (BIO_should_retry(wbio)) {
796                     /*
797                      * Non-blocking IO...but we're stateless, so we're just
798                      * going to drop this packet.
799                      */
800                     goto end;
801                 }
802                 return -1;
803             }
804 
805             if (BIO_flush(wbio) <= 0) {
806                 if (BIO_should_retry(wbio)) {
807                     /*
808                      * Non-blocking IO...but we're stateless, so we're just
809                      * going to drop this packet.
810                      */
811                     goto end;
812                 }
813                 return -1;
814             }
815         }
816     } while (next != LISTEN_SUCCESS);
817 
818     /*
819      * Set expected sequence numbers to continue the handshake.
820      */
821     s->d1->handshake_read_seq = 1;
822     s->d1->handshake_write_seq = 1;
823     s->d1->next_handshake_write_seq = 1;
824     DTLS_RECORD_LAYER_set_write_sequence(&s->rlayer, seq);
825 
826     /*
827      * We are doing cookie exchange, so make sure we set that option in the
828      * SSL object
829      */
830     SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
831 
832     /*
833      * Tell the state machine that we've done the initial hello verify
834      * exchange
835      */
836     ossl_statem_set_hello_verify_done(s);
837 
838     /*
839      * Some BIOs may not support this. If we fail we clear the client address
840      */
841     if (BIO_dgram_get_peer(rbio, client) <= 0)
842         BIO_ADDR_clear(client);
843 
844     /* Buffer the record in the processed_rcds queue */
845     if (!dtls_buffer_listen_record(s, reclen, seq, align))
846         return -1;
847 
848     ret = 1;
849  end:
850     BIO_ADDR_free(tmpclient);
851     return ret;
852 }
853 #endif
854 
dtls1_handshake_write(SSL * s)855 static int dtls1_handshake_write(SSL *s)
856 {
857     return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
858 }
859 
dtls1_shutdown(SSL * s)860 int dtls1_shutdown(SSL *s)
861 {
862     int ret;
863 #ifndef OPENSSL_NO_SCTP
864     BIO *wbio;
865 
866     wbio = SSL_get_wbio(s);
867     if (wbio != NULL && BIO_dgram_is_sctp(wbio) &&
868         !(s->shutdown & SSL_SENT_SHUTDOWN)) {
869         ret = BIO_dgram_sctp_wait_for_dry(wbio);
870         if (ret < 0)
871             return -1;
872 
873         if (ret == 0)
874             BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 1,
875                      NULL);
876     }
877 #endif
878     ret = ssl3_shutdown(s);
879 #ifndef OPENSSL_NO_SCTP
880     BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SAVE_SHUTDOWN, 0, NULL);
881 #endif
882     return ret;
883 }
884 
dtls1_query_mtu(SSL * s)885 int dtls1_query_mtu(SSL *s)
886 {
887     if (s->d1->link_mtu) {
888         s->d1->mtu =
889             s->d1->link_mtu - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
890         s->d1->link_mtu = 0;
891     }
892 
893     /* AHA!  Figure out the MTU, and stick to the right size */
894     if (s->d1->mtu < dtls1_min_mtu(s)) {
895         if (!(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
896             s->d1->mtu =
897                 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
898 
899             /*
900              * I've seen the kernel return bogus numbers when it doesn't know
901              * (initial write), so just make sure we have a reasonable number
902              */
903             if (s->d1->mtu < dtls1_min_mtu(s)) {
904                 /* Set to min mtu */
905                 s->d1->mtu = dtls1_min_mtu(s);
906                 BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
907                          (long)s->d1->mtu, NULL);
908             }
909         } else
910             return 0;
911     }
912     return 1;
913 }
914 
dtls1_link_min_mtu(void)915 static size_t dtls1_link_min_mtu(void)
916 {
917     return (g_probable_mtu[(sizeof(g_probable_mtu) /
918                             sizeof(g_probable_mtu[0])) - 1]);
919 }
920 
dtls1_min_mtu(SSL * s)921 size_t dtls1_min_mtu(SSL *s)
922 {
923     return dtls1_link_min_mtu() - BIO_dgram_get_mtu_overhead(SSL_get_wbio(s));
924 }
925 
DTLS_get_data_mtu(const SSL * s)926 size_t DTLS_get_data_mtu(const SSL *s)
927 {
928     size_t mac_overhead, int_overhead, blocksize, ext_overhead;
929     const SSL_CIPHER *ciph = SSL_get_current_cipher(s);
930     size_t mtu = s->d1->mtu;
931 
932     if (ciph == NULL)
933         return 0;
934 
935     if (!ssl_cipher_get_overhead(ciph, &mac_overhead, &int_overhead,
936                                  &blocksize, &ext_overhead))
937         return 0;
938 
939     if (SSL_READ_ETM(s))
940         ext_overhead += mac_overhead;
941     else
942         int_overhead += mac_overhead;
943 
944     /* Subtract external overhead (e.g. IV/nonce, separate MAC) */
945     if (ext_overhead + DTLS1_RT_HEADER_LENGTH >= mtu)
946         return 0;
947     mtu -= ext_overhead + DTLS1_RT_HEADER_LENGTH;
948 
949     /* Round encrypted payload down to cipher block size (for CBC etc.)
950      * No check for overflow since 'mtu % blocksize' cannot exceed mtu. */
951     if (blocksize)
952         mtu -= (mtu % blocksize);
953 
954     /* Subtract internal overhead (e.g. CBC padding len byte) */
955     if (int_overhead >= mtu)
956         return 0;
957     mtu -= int_overhead;
958 
959     return mtu;
960 }
961 
DTLS_set_timer_cb(SSL * s,DTLS_timer_cb cb)962 void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb)
963 {
964     s->d1->timer_cb = cb;
965 }
966