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 <assert.h>
60 #include <limits.h>
61 #include <string.h>
62
63 #include <openssl/err.h>
64 #include <openssl/mem.h>
65 #include <openssl/nid.h>
66
67 #include "../crypto/internal.h"
68 #include "internal.h"
69
70
71
72 /* DTLS1_MTU_TIMEOUTS is the maximum number of timeouts to expire
73 * before starting to decrease the MTU. */
74 #define DTLS1_MTU_TIMEOUTS 2
75
76 /* DTLS1_MAX_TIMEOUTS is the maximum number of timeouts to expire
77 * before failing the DTLS handshake. */
78 #define DTLS1_MAX_TIMEOUTS 12
79
dtls1_new(SSL * ssl)80 int dtls1_new(SSL *ssl) {
81 if (!ssl3_new(ssl)) {
82 return 0;
83 }
84 DTLS1_STATE *d1 = (DTLS1_STATE *)OPENSSL_malloc(sizeof *d1);
85 if (d1 == NULL) {
86 ssl3_free(ssl);
87 return 0;
88 }
89 OPENSSL_memset(d1, 0, sizeof *d1);
90
91 ssl->d1 = d1;
92
93 /* Set the version to the highest supported version.
94 *
95 * TODO(davidben): Move this field into |s3|, have it store the normalized
96 * protocol version, and implement this pre-negotiation quirk in |SSL_version|
97 * at the API boundary rather than in internal state. */
98 ssl->version = DTLS1_2_VERSION;
99 return 1;
100 }
101
dtls1_free(SSL * ssl)102 void dtls1_free(SSL *ssl) {
103 ssl3_free(ssl);
104
105 if (ssl == NULL || ssl->d1 == NULL) {
106 return;
107 }
108
109 dtls_clear_incoming_messages(ssl);
110 dtls_clear_outgoing_messages(ssl);
111
112 OPENSSL_free(ssl->d1);
113 ssl->d1 = NULL;
114 }
115
DTLSv1_set_initial_timeout_duration(SSL * ssl,unsigned int duration_ms)116 void DTLSv1_set_initial_timeout_duration(SSL *ssl, unsigned int duration_ms) {
117 ssl->initial_timeout_duration_ms = duration_ms;
118 }
119
dtls1_start_timer(SSL * ssl)120 void dtls1_start_timer(SSL *ssl) {
121 /* If timer is not set, initialize duration (by default, 1 second) */
122 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) {
123 ssl->d1->timeout_duration_ms = ssl->initial_timeout_duration_ms;
124 }
125
126 /* Set timeout to current time */
127 ssl_get_current_time(ssl, &ssl->d1->next_timeout);
128
129 /* Add duration to current time */
130 ssl->d1->next_timeout.tv_sec += ssl->d1->timeout_duration_ms / 1000;
131 ssl->d1->next_timeout.tv_usec += (ssl->d1->timeout_duration_ms % 1000) * 1000;
132 if (ssl->d1->next_timeout.tv_usec >= 1000000) {
133 ssl->d1->next_timeout.tv_sec++;
134 ssl->d1->next_timeout.tv_usec -= 1000000;
135 }
136 }
137
DTLSv1_get_timeout(const SSL * ssl,struct timeval * out)138 int DTLSv1_get_timeout(const SSL *ssl, struct timeval *out) {
139 if (!SSL_is_dtls(ssl)) {
140 return 0;
141 }
142
143 /* If no timeout is set, just return NULL */
144 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) {
145 return 0;
146 }
147
148 struct OPENSSL_timeval timenow;
149 ssl_get_current_time(ssl, &timenow);
150
151 /* If timer already expired, set remaining time to 0 */
152 if (ssl->d1->next_timeout.tv_sec < timenow.tv_sec ||
153 (ssl->d1->next_timeout.tv_sec == timenow.tv_sec &&
154 ssl->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
155 OPENSSL_memset(out, 0, sizeof(*out));
156 return 1;
157 }
158
159 /* Calculate time left until timer expires */
160 struct OPENSSL_timeval ret;
161 OPENSSL_memcpy(&ret, &ssl->d1->next_timeout, sizeof(ret));
162 ret.tv_sec -= timenow.tv_sec;
163 if (ret.tv_usec >= timenow.tv_usec) {
164 ret.tv_usec -= timenow.tv_usec;
165 } else {
166 ret.tv_usec = 1000000 + ret.tv_usec - timenow.tv_usec;
167 ret.tv_sec--;
168 }
169
170 /* If remaining time is less than 15 ms, set it to 0 to prevent issues
171 * because of small divergences with socket timeouts. */
172 if (ret.tv_sec == 0 && ret.tv_usec < 15000) {
173 OPENSSL_memset(&ret, 0, sizeof(ret));
174 }
175
176 /* Clamp the result in case of overflow. */
177 if (ret.tv_sec > INT_MAX) {
178 assert(0);
179 out->tv_sec = INT_MAX;
180 } else {
181 out->tv_sec = ret.tv_sec;
182 }
183
184 out->tv_usec = ret.tv_usec;
185 return 1;
186 }
187
dtls1_is_timer_expired(SSL * ssl)188 int dtls1_is_timer_expired(SSL *ssl) {
189 struct timeval timeleft;
190
191 /* Get time left until timeout, return false if no timer running */
192 if (!DTLSv1_get_timeout(ssl, &timeleft)) {
193 return 0;
194 }
195
196 /* Return false if timer is not expired yet */
197 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
198 return 0;
199 }
200
201 /* Timer expired, so return true */
202 return 1;
203 }
204
dtls1_double_timeout(SSL * ssl)205 void dtls1_double_timeout(SSL *ssl) {
206 ssl->d1->timeout_duration_ms *= 2;
207 if (ssl->d1->timeout_duration_ms > 60000) {
208 ssl->d1->timeout_duration_ms = 60000;
209 }
210 dtls1_start_timer(ssl);
211 }
212
dtls1_stop_timer(SSL * ssl)213 void dtls1_stop_timer(SSL *ssl) {
214 /* Reset everything */
215 ssl->d1->num_timeouts = 0;
216 OPENSSL_memset(&ssl->d1->next_timeout, 0, sizeof(ssl->d1->next_timeout));
217 ssl->d1->timeout_duration_ms = ssl->initial_timeout_duration_ms;
218
219 /* Clear retransmission buffer */
220 dtls_clear_outgoing_messages(ssl);
221 }
222
dtls1_check_timeout_num(SSL * ssl)223 int dtls1_check_timeout_num(SSL *ssl) {
224 ssl->d1->num_timeouts++;
225
226 /* Reduce MTU after 2 unsuccessful retransmissions */
227 if (ssl->d1->num_timeouts > DTLS1_MTU_TIMEOUTS &&
228 !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
229 long mtu = BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
230 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) {
231 ssl->d1->mtu = (unsigned)mtu;
232 }
233 }
234
235 if (ssl->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) {
236 /* fail the connection, enough alerts have been sent */
237 OPENSSL_PUT_ERROR(SSL, SSL_R_READ_TIMEOUT_EXPIRED);
238 return -1;
239 }
240
241 return 0;
242 }
243
DTLSv1_handle_timeout(SSL * ssl)244 int DTLSv1_handle_timeout(SSL *ssl) {
245 ssl_reset_error_state(ssl);
246
247 if (!SSL_is_dtls(ssl)) {
248 return -1;
249 }
250
251 /* if no timer is expired, don't do anything */
252 if (!dtls1_is_timer_expired(ssl)) {
253 return 0;
254 }
255
256 dtls1_double_timeout(ssl);
257
258 if (dtls1_check_timeout_num(ssl) < 0) {
259 return -1;
260 }
261
262 dtls1_start_timer(ssl);
263 return dtls1_retransmit_outgoing_messages(ssl);
264 }
265