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 BSSL_NAMESPACE_BEGIN
72
73 // DTLS1_MTU_TIMEOUTS is the maximum number of timeouts to expire
74 // before starting to decrease the MTU.
75 #define DTLS1_MTU_TIMEOUTS 2
76
77 // DTLS1_MAX_TIMEOUTS is the maximum number of timeouts to expire
78 // before failing the DTLS handshake.
79 #define DTLS1_MAX_TIMEOUTS 12
80
DTLS1_STATE()81 DTLS1_STATE::DTLS1_STATE()
82 : has_change_cipher_spec(false),
83 outgoing_messages_complete(false),
84 flight_has_reply(false) {}
85
~DTLS1_STATE()86 DTLS1_STATE::~DTLS1_STATE() {}
87
dtls1_new(SSL * ssl)88 bool dtls1_new(SSL *ssl) {
89 if (!ssl3_new(ssl)) {
90 return false;
91 }
92 UniquePtr<DTLS1_STATE> d1 = MakeUnique<DTLS1_STATE>();
93 if (!d1) {
94 ssl3_free(ssl);
95 return false;
96 }
97
98 ssl->d1 = d1.release();
99
100 // Set the version to the highest supported version.
101 //
102 // TODO(davidben): Move this field into |s3|, have it store the normalized
103 // protocol version, and implement this pre-negotiation quirk in |SSL_version|
104 // at the API boundary rather than in internal state.
105 ssl->version = DTLS1_2_VERSION;
106 return true;
107 }
108
dtls1_free(SSL * ssl)109 void dtls1_free(SSL *ssl) {
110 ssl3_free(ssl);
111
112 if (ssl == NULL) {
113 return;
114 }
115
116 Delete(ssl->d1);
117 ssl->d1 = NULL;
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
dtls1_is_timer_expired(SSL * ssl)138 bool dtls1_is_timer_expired(SSL *ssl) {
139 struct timeval timeleft;
140
141 // Get time left until timeout, return false if no timer running
142 if (!DTLSv1_get_timeout(ssl, &timeleft)) {
143 return false;
144 }
145
146 // Return false if timer is not expired yet
147 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) {
148 return false;
149 }
150
151 // Timer expired, so return true
152 return true;
153 }
154
dtls1_double_timeout(SSL * ssl)155 static void dtls1_double_timeout(SSL *ssl) {
156 ssl->d1->timeout_duration_ms *= 2;
157 if (ssl->d1->timeout_duration_ms > 60000) {
158 ssl->d1->timeout_duration_ms = 60000;
159 }
160 }
161
dtls1_stop_timer(SSL * ssl)162 void dtls1_stop_timer(SSL *ssl) {
163 ssl->d1->num_timeouts = 0;
164 OPENSSL_memset(&ssl->d1->next_timeout, 0, sizeof(ssl->d1->next_timeout));
165 ssl->d1->timeout_duration_ms = ssl->initial_timeout_duration_ms;
166 }
167
dtls1_check_timeout_num(SSL * ssl)168 bool dtls1_check_timeout_num(SSL *ssl) {
169 ssl->d1->num_timeouts++;
170
171 // Reduce MTU after 2 unsuccessful retransmissions
172 if (ssl->d1->num_timeouts > DTLS1_MTU_TIMEOUTS &&
173 !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
174 long mtu =
175 BIO_ctrl(ssl->wbio.get(), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, nullptr);
176 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) {
177 ssl->d1->mtu = (unsigned)mtu;
178 }
179 }
180
181 if (ssl->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) {
182 // fail the connection, enough alerts have been sent
183 OPENSSL_PUT_ERROR(SSL, SSL_R_READ_TIMEOUT_EXPIRED);
184 return false;
185 }
186
187 return true;
188 }
189
190 BSSL_NAMESPACE_END
191
192 using namespace bssl;
193
DTLSv1_set_initial_timeout_duration(SSL * ssl,unsigned int duration_ms)194 void DTLSv1_set_initial_timeout_duration(SSL *ssl, unsigned int duration_ms) {
195 ssl->initial_timeout_duration_ms = duration_ms;
196 }
197
DTLSv1_get_timeout(const SSL * ssl,struct timeval * out)198 int DTLSv1_get_timeout(const SSL *ssl, struct timeval *out) {
199 if (!SSL_is_dtls(ssl)) {
200 return 0;
201 }
202
203 // If no timeout is set, just return 0.
204 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) {
205 return 0;
206 }
207
208 struct OPENSSL_timeval timenow;
209 ssl_get_current_time(ssl, &timenow);
210
211 // If timer already expired, set remaining time to 0.
212 if (ssl->d1->next_timeout.tv_sec < timenow.tv_sec ||
213 (ssl->d1->next_timeout.tv_sec == timenow.tv_sec &&
214 ssl->d1->next_timeout.tv_usec <= timenow.tv_usec)) {
215 OPENSSL_memset(out, 0, sizeof(*out));
216 return 1;
217 }
218
219 // Calculate time left until timer expires.
220 struct OPENSSL_timeval ret;
221 OPENSSL_memcpy(&ret, &ssl->d1->next_timeout, sizeof(ret));
222 ret.tv_sec -= timenow.tv_sec;
223 if (ret.tv_usec >= timenow.tv_usec) {
224 ret.tv_usec -= timenow.tv_usec;
225 } else {
226 ret.tv_usec = 1000000 + ret.tv_usec - timenow.tv_usec;
227 ret.tv_sec--;
228 }
229
230 // If remaining time is less than 15 ms, set it to 0 to prevent issues
231 // because of small divergences with socket timeouts.
232 if (ret.tv_sec == 0 && ret.tv_usec < 15000) {
233 OPENSSL_memset(&ret, 0, sizeof(ret));
234 }
235
236 // Clamp the result in case of overflow.
237 if (ret.tv_sec > INT_MAX) {
238 assert(0);
239 out->tv_sec = INT_MAX;
240 } else {
241 out->tv_sec = ret.tv_sec;
242 }
243
244 out->tv_usec = ret.tv_usec;
245 return 1;
246 }
247
DTLSv1_handle_timeout(SSL * ssl)248 int DTLSv1_handle_timeout(SSL *ssl) {
249 ssl_reset_error_state(ssl);
250
251 if (!SSL_is_dtls(ssl)) {
252 OPENSSL_PUT_ERROR(SSL, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
253 return -1;
254 }
255
256 // If no timer is expired, don't do anything.
257 if (!dtls1_is_timer_expired(ssl)) {
258 return 0;
259 }
260
261 if (!dtls1_check_timeout_num(ssl)) {
262 return -1;
263 }
264
265 dtls1_double_timeout(ssl);
266 dtls1_start_timer(ssl);
267 return dtls1_retransmit_outgoing_messages(ssl);
268 }
269