1 /*
2 * DTLS implementation written by Nagendra Modadugu
3 * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
4 */
5 /* ====================================================================
6 * Copyright (c) 1999-2005 The OpenSSL Project. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * openssl-core@OpenSSL.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 * acknowledgment:
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 *
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com). */
56
57 #include <openssl/ssl.h>
58
59 #include <limits.h>
60 #include <stdio.h>
61 #include <string.h>
62
63 #include <openssl/err.h>
64 #include <openssl/mem.h>
65 #include <openssl/obj.h>
66
67 #include "internal.h"
68
69 #if defined(OPENSSL_WINDOWS)
70 #include <sys/timeb.h>
71 #else
72 #include <sys/socket.h>
73 #include <sys/time.h>
74 #endif
75
76
77 /* DTLS1_MTU_TIMEOUTS is the maximum number of timeouts to expire
78 * before starting to decrease the MTU. */
79 #define DTLS1_MTU_TIMEOUTS 2
80
81 /* DTLS1_MAX_TIMEOUTS is the maximum number of timeouts to expire
82 * before failing the DTLS handshake. */
83 #define DTLS1_MAX_TIMEOUTS 12
84
85 static void get_current_time(const SSL *ssl, struct timeval *out_clock);
86
dtls1_new(SSL * ssl)87 int dtls1_new(SSL *ssl) {
88 DTLS1_STATE *d1;
89
90 if (!ssl3_new(ssl)) {
91 return 0;
92 }
93 d1 = OPENSSL_malloc(sizeof *d1);
94 if (d1 == NULL) {
95 ssl3_free(ssl);
96 return 0;
97 }
98 memset(d1, 0, sizeof *d1);
99
100 d1->buffered_messages = pqueue_new();
101 d1->sent_messages = pqueue_new();
102
103 if (!d1->buffered_messages || !d1->sent_messages) {
104 pqueue_free(d1->buffered_messages);
105 pqueue_free(d1->sent_messages);
106 OPENSSL_free(d1);
107 ssl3_free(ssl);
108 return 0;
109 }
110
111 ssl->d1 = d1;
112
113 /* Set the version to the highest version for DTLS. This controls the initial
114 * state of |ssl->enc_method| and what the API reports as the version prior to
115 * negotiation.
116 *
117 * TODO(davidben): This is fragile and confusing. */
118 ssl->version = DTLS1_2_VERSION;
119 return 1;
120 }
121
dtls1_clear_queues(SSL * ssl)122 static void dtls1_clear_queues(SSL *ssl) {
123 pitem *item = NULL;
124 hm_fragment *frag = NULL;
125
126 while ((item = pqueue_pop(ssl->d1->buffered_messages)) != NULL) {
127 frag = (hm_fragment *)item->data;
128 dtls1_hm_fragment_free(frag);
129 pitem_free(item);
130 }
131
132 while ((item = pqueue_pop(ssl->d1->sent_messages)) != NULL) {
133 frag = (hm_fragment *)item->data;
134 dtls1_hm_fragment_free(frag);
135 pitem_free(item);
136 }
137 }
138
dtls1_free(SSL * ssl)139 void dtls1_free(SSL *ssl) {
140 ssl3_free(ssl);
141
142 if (ssl == NULL || ssl->d1 == NULL) {
143 return;
144 }
145
146 dtls1_clear_queues(ssl);
147
148 pqueue_free(ssl->d1->buffered_messages);
149 pqueue_free(ssl->d1->sent_messages);
150
151 OPENSSL_free(ssl->d1);
152 ssl->d1 = NULL;
153 }
154
dtls1_supports_cipher(const SSL_CIPHER * cipher)155 int dtls1_supports_cipher(const SSL_CIPHER *cipher) {
156 /* DTLS does not support stream ciphers. The NULL cipher is rejected because
157 * it's not needed. */
158 return cipher->algorithm_enc != SSL_RC4 && cipher->algorithm_enc != SSL_eNULL;
159 }
160
dtls1_start_timer(SSL * ssl)161 void dtls1_start_timer(SSL *ssl) {
162 /* If timer is not set, initialize duration with 1 second */
163 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) {
164 ssl->d1->timeout_duration = 1;
165 }
166
167 /* Set timeout to current time */
168 get_current_time(ssl, &ssl->d1->next_timeout);
169
170 /* Add duration to current time */
171 ssl->d1->next_timeout.tv_sec += ssl->d1->timeout_duration;
172 BIO_ctrl(SSL_get_rbio(ssl), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
173 &ssl->d1->next_timeout);
174 }
175
DTLSv1_get_timeout(const SSL * ssl,struct timeval * out)176 int DTLSv1_get_timeout(const SSL *ssl, struct timeval *out) {
177 if (!SSL_IS_DTLS(ssl)) {
178 return 0;
179 }
180
181 /* If no timeout is set, just return NULL */
182 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) {
183 return 0;
184 }
185
186 /* Get current time */
187 struct timeval timenow;
188 get_current_time(ssl, &timenow);
189
190 /* If timer already expired, set remaining time to 0 */
191 if (ssl->d1->next_timeout.tv_sec < timenow.tv_sec ||
192 (ssl->d1->next_timeout.tv_sec == timenow.tv_sec &&
193 ssl->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
194 memset(out, 0, sizeof(struct timeval));
195 return 1;
196 }
197
198 /* Calculate time left until timer expires */
199 memcpy(out, &ssl->d1->next_timeout, sizeof(struct timeval));
200 out->tv_sec -= timenow.tv_sec;
201 out->tv_usec -= timenow.tv_usec;
202 if (out->tv_usec < 0) {
203 out->tv_sec--;
204 out->tv_usec += 1000000;
205 }
206
207 /* If remaining time is less than 15 ms, set it to 0 to prevent issues
208 * because of small devergences with socket timeouts. */
209 if (out->tv_sec == 0 && out->tv_usec < 15000) {
210 memset(out, 0, sizeof(struct timeval));
211 }
212
213 return 1;
214 }
215
dtls1_is_timer_expired(SSL * ssl)216 int dtls1_is_timer_expired(SSL *ssl) {
217 struct timeval timeleft;
218
219 /* Get time left until timeout, return false if no timer running */
220 if (!DTLSv1_get_timeout(ssl, &timeleft)) {
221 return 0;
222 }
223
224 /* Return false if timer is not expired yet */
225 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
226 return 0;
227 }
228
229 /* Timer expired, so return true */
230 return 1;
231 }
232
dtls1_double_timeout(SSL * ssl)233 void dtls1_double_timeout(SSL *ssl) {
234 ssl->d1->timeout_duration *= 2;
235 if (ssl->d1->timeout_duration > 60) {
236 ssl->d1->timeout_duration = 60;
237 }
238 dtls1_start_timer(ssl);
239 }
240
dtls1_stop_timer(SSL * ssl)241 void dtls1_stop_timer(SSL *ssl) {
242 /* Reset everything */
243 ssl->d1->num_timeouts = 0;
244 memset(&ssl->d1->next_timeout, 0, sizeof(struct timeval));
245 ssl->d1->timeout_duration = 1;
246 BIO_ctrl(SSL_get_rbio(ssl), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0,
247 &ssl->d1->next_timeout);
248 /* Clear retransmission buffer */
249 dtls1_clear_record_buffer(ssl);
250 }
251
dtls1_check_timeout_num(SSL * ssl)252 int dtls1_check_timeout_num(SSL *ssl) {
253 ssl->d1->num_timeouts++;
254
255 /* Reduce MTU after 2 unsuccessful retransmissions */
256 if (ssl->d1->num_timeouts > DTLS1_MTU_TIMEOUTS &&
257 !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
258 long mtu = BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0,
259 NULL);
260 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) {
261 ssl->d1->mtu = (unsigned)mtu;
262 }
263 }
264
265 if (ssl->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) {
266 /* fail the connection, enough alerts have been sent */
267 OPENSSL_PUT_ERROR(SSL, SSL_R_READ_TIMEOUT_EXPIRED);
268 return -1;
269 }
270
271 return 0;
272 }
273
DTLSv1_handle_timeout(SSL * ssl)274 int DTLSv1_handle_timeout(SSL *ssl) {
275 if (!SSL_IS_DTLS(ssl)) {
276 return -1;
277 }
278
279 /* if no timer is expired, don't do anything */
280 if (!dtls1_is_timer_expired(ssl)) {
281 return 0;
282 }
283
284 dtls1_double_timeout(ssl);
285
286 if (dtls1_check_timeout_num(ssl) < 0) {
287 return -1;
288 }
289
290 dtls1_start_timer(ssl);
291 return dtls1_retransmit_buffered_messages(ssl);
292 }
293
get_current_time(const SSL * ssl,struct timeval * out_clock)294 static void get_current_time(const SSL *ssl, struct timeval *out_clock) {
295 if (ssl->ctx->current_time_cb != NULL) {
296 ssl->ctx->current_time_cb(ssl, out_clock);
297 return;
298 }
299
300 #if defined(OPENSSL_WINDOWS)
301 struct _timeb time;
302 _ftime(&time);
303 out_clock->tv_sec = time.time;
304 out_clock->tv_usec = time.millitm * 1000;
305 #else
306 gettimeofday(out_clock, NULL);
307 #endif
308 }
309
dtls1_set_handshake_header(SSL * ssl,int htype,unsigned long len)310 int dtls1_set_handshake_header(SSL *ssl, int htype, unsigned long len) {
311 uint8_t *message = (uint8_t *)ssl->init_buf->data;
312 const struct hm_header_st *msg_hdr = &ssl->d1->w_msg_hdr;
313 uint8_t serialised_header[DTLS1_HM_HEADER_LENGTH];
314 uint8_t *p = serialised_header;
315
316 ssl->d1->handshake_write_seq = ssl->d1->next_handshake_write_seq;
317 ssl->d1->next_handshake_write_seq++;
318
319 dtls1_set_message_header(ssl, htype, len, ssl->d1->handshake_write_seq, 0,
320 len);
321 ssl->init_num = (int)len + DTLS1_HM_HEADER_LENGTH;
322 ssl->init_off = 0;
323
324 /* Buffer the message to handle re-xmits */
325 dtls1_buffer_message(ssl);
326
327 /* Add the new message to the handshake hash. Serialize the message
328 * header as if it were a single fragment. */
329 *p++ = msg_hdr->type;
330 l2n3(msg_hdr->msg_len, p);
331 s2n(msg_hdr->seq, p);
332 l2n3(0, p);
333 l2n3(msg_hdr->msg_len, p);
334 return ssl3_update_handshake_hash(ssl, serialised_header,
335 sizeof(serialised_header)) &&
336 ssl3_update_handshake_hash(ssl, message + DTLS1_HM_HEADER_LENGTH, len);
337 }
338
dtls1_handshake_write(SSL * ssl)339 int dtls1_handshake_write(SSL *ssl) {
340 return dtls1_do_handshake_write(ssl, dtls1_use_current_epoch);
341 }
342