1 /* 2 * DTLS implementation written by Nagendra Modadugu 3 * (nagendra (at) 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 (at) 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 (at) cryptsoft.com). This product includes software written by Tim 55 * Hudson (tjh (at) 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 namespace bssl { 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 81 DTLS1_STATE::DTLS1_STATE() 82 : has_change_cipher_spec(false), 83 outgoing_messages_complete(false), 84 flight_has_reply(false) {} 85 86 DTLS1_STATE::~DTLS1_STATE() {} 87 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 } 108 109 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 } 119 120 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 } 137 138 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 } 154 155 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 } 161 162 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 } 167 168 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 = BIO_ctrl(ssl->wbio, BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL); 175 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) { 176 ssl->d1->mtu = (unsigned)mtu; 177 } 178 } 179 180 if (ssl->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) { 181 // fail the connection, enough alerts have been sent 182 OPENSSL_PUT_ERROR(SSL, SSL_R_READ_TIMEOUT_EXPIRED); 183 return false; 184 } 185 186 return true; 187 } 188 189 } // namespace bssl 190 191 using namespace bssl; 192 193 void DTLSv1_set_initial_timeout_duration(SSL *ssl, unsigned int duration_ms) { 194 ssl->initial_timeout_duration_ms = duration_ms; 195 } 196 197 int DTLSv1_get_timeout(const SSL *ssl, struct timeval *out) { 198 if (!SSL_is_dtls(ssl)) { 199 return 0; 200 } 201 202 // If no timeout is set, just return 0. 203 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) { 204 return 0; 205 } 206 207 struct OPENSSL_timeval timenow; 208 ssl_get_current_time(ssl, &timenow); 209 210 // If timer already expired, set remaining time to 0. 211 if (ssl->d1->next_timeout.tv_sec < timenow.tv_sec || 212 (ssl->d1->next_timeout.tv_sec == timenow.tv_sec && 213 ssl->d1->next_timeout.tv_usec <= timenow.tv_usec)) { 214 OPENSSL_memset(out, 0, sizeof(*out)); 215 return 1; 216 } 217 218 // Calculate time left until timer expires. 219 struct OPENSSL_timeval ret; 220 OPENSSL_memcpy(&ret, &ssl->d1->next_timeout, sizeof(ret)); 221 ret.tv_sec -= timenow.tv_sec; 222 if (ret.tv_usec >= timenow.tv_usec) { 223 ret.tv_usec -= timenow.tv_usec; 224 } else { 225 ret.tv_usec = 1000000 + ret.tv_usec - timenow.tv_usec; 226 ret.tv_sec--; 227 } 228 229 // If remaining time is less than 15 ms, set it to 0 to prevent issues 230 // because of small divergences with socket timeouts. 231 if (ret.tv_sec == 0 && ret.tv_usec < 15000) { 232 OPENSSL_memset(&ret, 0, sizeof(ret)); 233 } 234 235 // Clamp the result in case of overflow. 236 if (ret.tv_sec > INT_MAX) { 237 assert(0); 238 out->tv_sec = INT_MAX; 239 } else { 240 out->tv_sec = ret.tv_sec; 241 } 242 243 out->tv_usec = ret.tv_usec; 244 return 1; 245 } 246 247 int DTLSv1_handle_timeout(SSL *ssl) { 248 ssl_reset_error_state(ssl); 249 250 if (!SSL_is_dtls(ssl)) { 251 OPENSSL_PUT_ERROR(SSL, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED); 252 return -1; 253 } 254 255 // If no timer is expired, don't do anything. 256 if (!dtls1_is_timer_expired(ssl)) { 257 return 0; 258 } 259 260 if (!dtls1_check_timeout_num(ssl)) { 261 return -1; 262 } 263 264 dtls1_double_timeout(ssl); 265 dtls1_start_timer(ssl); 266 return dtls1_retransmit_outgoing_messages(ssl); 267 } 268
