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 DTLS1_STATE *d1;
82
83 if (!ssl3_new(ssl)) {
84 return 0;
85 }
86 d1 = OPENSSL_malloc(sizeof *d1);
87 if (d1 == NULL) {
88 ssl3_free(ssl);
89 return 0;
90 }
91 OPENSSL_memset(d1, 0, sizeof *d1);
92
93 ssl->d1 = d1;
94
95 /* Set the version to the highest supported version.
96 *
97 * TODO(davidben): Move this field into |s3|, have it store the normalized
98 * protocol version, and implement this pre-negotiation quirk in |SSL_version|
99 * at the API boundary rather than in internal state. */
100 ssl->version = DTLS1_2_VERSION;
101 return 1;
102 }
103
dtls1_free(SSL * ssl)104 void dtls1_free(SSL *ssl) {
105 ssl3_free(ssl);
106
107 if (ssl == NULL || ssl->d1 == NULL) {
108 return;
109 }
110
111 dtls_clear_incoming_messages(ssl);
112 dtls_clear_outgoing_messages(ssl);
113
114 OPENSSL_free(ssl->d1);
115 ssl->d1 = NULL;
116 }
117
DTLSv1_set_initial_timeout_duration(SSL * ssl,unsigned int duration_ms)118 void DTLSv1_set_initial_timeout_duration(SSL *ssl, unsigned int duration_ms) {
119 ssl->initial_timeout_duration_ms = duration_ms;
120 }
121
dtls1_start_timer(SSL * ssl)122 void dtls1_start_timer(SSL *ssl) {
123 /* If timer is not set, initialize duration (by default, 1 second) */
124 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) {
125 ssl->d1->timeout_duration_ms = ssl->initial_timeout_duration_ms;
126 }
127
128 /* Set timeout to current time */
129 ssl_get_current_time(ssl, &ssl->d1->next_timeout);
130
131 /* Add duration to current time */
132 ssl->d1->next_timeout.tv_sec += ssl->d1->timeout_duration_ms / 1000;
133 ssl->d1->next_timeout.tv_usec += (ssl->d1->timeout_duration_ms % 1000) * 1000;
134 if (ssl->d1->next_timeout.tv_usec >= 1000000) {
135 ssl->d1->next_timeout.tv_sec++;
136 ssl->d1->next_timeout.tv_usec -= 1000000;
137 }
138 }
139
DTLSv1_get_timeout(const SSL * ssl,struct timeval * out)140 int DTLSv1_get_timeout(const SSL *ssl, struct timeval *out) {
141 if (!SSL_is_dtls(ssl)) {
142 return 0;
143 }
144
145 /* If no timeout is set, just return NULL */
146 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) {
147 return 0;
148 }
149
150 struct OPENSSL_timeval timenow;
151 ssl_get_current_time(ssl, &timenow);
152
153 /* If timer already expired, set remaining time to 0 */
154 if (ssl->d1->next_timeout.tv_sec < timenow.tv_sec ||
155 (ssl->d1->next_timeout.tv_sec == timenow.tv_sec &&
156 ssl->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
157 OPENSSL_memset(out, 0, sizeof(*out));
158 return 1;
159 }
160
161 /* Calculate time left until timer expires */
162 struct OPENSSL_timeval ret;
163 OPENSSL_memcpy(&ret, &ssl->d1->next_timeout, sizeof(ret));
164 ret.tv_sec -= timenow.tv_sec;
165 if (ret.tv_usec >= timenow.tv_usec) {
166 ret.tv_usec -= timenow.tv_usec;
167 } else {
168 ret.tv_usec = 1000000 + ret.tv_usec - timenow.tv_usec;
169 ret.tv_sec--;
170 }
171
172 /* If remaining time is less than 15 ms, set it to 0 to prevent issues
173 * because of small divergences with socket timeouts. */
174 if (ret.tv_sec == 0 && ret.tv_usec < 15000) {
175 OPENSSL_memset(&ret, 0, sizeof(ret));
176 }
177
178 /* Clamp the result in case of overflow. */
179 if (ret.tv_sec > INT_MAX) {
180 assert(0);
181 out->tv_sec = INT_MAX;
182 } else {
183 out->tv_sec = ret.tv_sec;
184 }
185
186 out->tv_usec = ret.tv_usec;
187 return 1;
188 }
189
dtls1_is_timer_expired(SSL * ssl)190 int dtls1_is_timer_expired(SSL *ssl) {
191 struct timeval timeleft;
192
193 /* Get time left until timeout, return false if no timer running */
194 if (!DTLSv1_get_timeout(ssl, &timeleft)) {
195 return 0;
196 }
197
198 /* Return false if timer is not expired yet */
199 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
200 return 0;
201 }
202
203 /* Timer expired, so return true */
204 return 1;
205 }
206
dtls1_double_timeout(SSL * ssl)207 void dtls1_double_timeout(SSL *ssl) {
208 ssl->d1->timeout_duration_ms *= 2;
209 if (ssl->d1->timeout_duration_ms > 60000) {
210 ssl->d1->timeout_duration_ms = 60000;
211 }
212 dtls1_start_timer(ssl);
213 }
214
dtls1_stop_timer(SSL * ssl)215 void dtls1_stop_timer(SSL *ssl) {
216 /* Reset everything */
217 ssl->d1->num_timeouts = 0;
218 OPENSSL_memset(&ssl->d1->next_timeout, 0, sizeof(ssl->d1->next_timeout));
219 ssl->d1->timeout_duration_ms = ssl->initial_timeout_duration_ms;
220
221 /* Clear retransmission buffer */
222 dtls_clear_outgoing_messages(ssl);
223 }
224
dtls1_check_timeout_num(SSL * ssl)225 int dtls1_check_timeout_num(SSL *ssl) {
226 ssl->d1->num_timeouts++;
227
228 /* Reduce MTU after 2 unsuccessful retransmissions */
229 if (ssl->d1->num_timeouts > DTLS1_MTU_TIMEOUTS &&
230 !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
231 long mtu = BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
232 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) {
233 ssl->d1->mtu = (unsigned)mtu;
234 }
235 }
236
237 if (ssl->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) {
238 /* fail the connection, enough alerts have been sent */
239 OPENSSL_PUT_ERROR(SSL, SSL_R_READ_TIMEOUT_EXPIRED);
240 return -1;
241 }
242
243 return 0;
244 }
245
DTLSv1_handle_timeout(SSL * ssl)246 int DTLSv1_handle_timeout(SSL *ssl) {
247 ssl_reset_error_state(ssl);
248
249 if (!SSL_is_dtls(ssl)) {
250 return -1;
251 }
252
253 /* if no timer is expired, don't do anything */
254 if (!dtls1_is_timer_expired(ssl)) {
255 return 0;
256 }
257
258 dtls1_double_timeout(ssl);
259
260 if (dtls1_check_timeout_num(ssl) < 0) {
261 return -1;
262 }
263
264 dtls1_start_timer(ssl);
265 return dtls1_retransmit_outgoing_messages(ssl);
266 }
267