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 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 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 } 101 102 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 } 115 116 void DTLSv1_set_initial_timeout_duration(SSL *ssl, unsigned int duration_ms) { 117 ssl->initial_timeout_duration_ms = duration_ms; 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 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 } 187 188 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 } 204 205 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 } 212 213 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 } 222 223 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 } 243 244 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
