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 <limits.h> 60 #include <stdio.h> 61 #include <string.h> 62 63 #include <openssl/err.h> 64 #include <openssl/mem.h> 65 #include <openssl/obj.h> 66 67 #include "internal.h" 68 69 #if defined(OPENSSL_WINDOWS) 70 #include <sys/timeb.h> 71 #else 72 #include <sys/socket.h> 73 #include <sys/time.h> 74 #endif 75 76 77 /* DTLS1_MTU_TIMEOUTS is the maximum number of timeouts to expire 78 * before starting to decrease the MTU. */ 79 #define DTLS1_MTU_TIMEOUTS 2 80 81 /* DTLS1_MAX_TIMEOUTS is the maximum number of timeouts to expire 82 * before failing the DTLS handshake. */ 83 #define DTLS1_MAX_TIMEOUTS 12 84 85 static void get_current_time(const SSL *ssl, struct timeval *out_clock); 86 87 int dtls1_new(SSL *ssl) { 88 DTLS1_STATE *d1; 89 90 if (!ssl3_new(ssl)) { 91 return 0; 92 } 93 d1 = OPENSSL_malloc(sizeof *d1); 94 if (d1 == NULL) { 95 ssl3_free(ssl); 96 return 0; 97 } 98 memset(d1, 0, sizeof *d1); 99 100 d1->buffered_messages = pqueue_new(); 101 d1->sent_messages = pqueue_new(); 102 103 if (!d1->buffered_messages || !d1->sent_messages) { 104 pqueue_free(d1->buffered_messages); 105 pqueue_free(d1->sent_messages); 106 OPENSSL_free(d1); 107 ssl3_free(ssl); 108 return 0; 109 } 110 111 ssl->d1 = d1; 112 113 /* Set the version to the highest version for DTLS. This controls the initial 114 * state of |ssl->enc_method| and what the API reports as the version prior to 115 * negotiation. 116 * 117 * TODO(davidben): This is fragile and confusing. */ 118 ssl->version = DTLS1_2_VERSION; 119 return 1; 120 } 121 122 static void dtls1_clear_queues(SSL *ssl) { 123 pitem *item = NULL; 124 hm_fragment *frag = NULL; 125 126 while ((item = pqueue_pop(ssl->d1->buffered_messages)) != NULL) { 127 frag = (hm_fragment *)item->data; 128 dtls1_hm_fragment_free(frag); 129 pitem_free(item); 130 } 131 132 while ((item = pqueue_pop(ssl->d1->sent_messages)) != NULL) { 133 frag = (hm_fragment *)item->data; 134 dtls1_hm_fragment_free(frag); 135 pitem_free(item); 136 } 137 } 138 139 void dtls1_free(SSL *ssl) { 140 ssl3_free(ssl); 141 142 if (ssl == NULL || ssl->d1 == NULL) { 143 return; 144 } 145 146 dtls1_clear_queues(ssl); 147 148 pqueue_free(ssl->d1->buffered_messages); 149 pqueue_free(ssl->d1->sent_messages); 150 151 OPENSSL_free(ssl->d1); 152 ssl->d1 = NULL; 153 } 154 155 int dtls1_supports_cipher(const SSL_CIPHER *cipher) { 156 /* DTLS does not support stream ciphers. The NULL cipher is rejected because 157 * it's not needed. */ 158 return cipher->algorithm_enc != SSL_RC4 && cipher->algorithm_enc != SSL_eNULL; 159 } 160 161 void dtls1_start_timer(SSL *ssl) { 162 /* If timer is not set, initialize duration with 1 second */ 163 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) { 164 ssl->d1->timeout_duration = 1; 165 } 166 167 /* Set timeout to current time */ 168 get_current_time(ssl, &ssl->d1->next_timeout); 169 170 /* Add duration to current time */ 171 ssl->d1->next_timeout.tv_sec += ssl->d1->timeout_duration; 172 BIO_ctrl(SSL_get_rbio(ssl), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 173 &ssl->d1->next_timeout); 174 } 175 176 int DTLSv1_get_timeout(const SSL *ssl, struct timeval *out) { 177 if (!SSL_IS_DTLS(ssl)) { 178 return 0; 179 } 180 181 /* If no timeout is set, just return NULL */ 182 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) { 183 return 0; 184 } 185 186 /* Get current time */ 187 struct timeval timenow; 188 get_current_time(ssl, &timenow); 189 190 /* If timer already expired, set remaining time to 0 */ 191 if (ssl->d1->next_timeout.tv_sec < timenow.tv_sec || 192 (ssl->d1->next_timeout.tv_sec == timenow.tv_sec && 193 ssl->d1->next_timeout.tv_usec <= timenow.tv_usec)) { 194 memset(out, 0, sizeof(struct timeval)); 195 return 1; 196 } 197 198 /* Calculate time left until timer expires */ 199 memcpy(out, &ssl->d1->next_timeout, sizeof(struct timeval)); 200 out->tv_sec -= timenow.tv_sec; 201 out->tv_usec -= timenow.tv_usec; 202 if (out->tv_usec < 0) { 203 out->tv_sec--; 204 out->tv_usec += 1000000; 205 } 206 207 /* If remaining time is less than 15 ms, set it to 0 to prevent issues 208 * because of small devergences with socket timeouts. */ 209 if (out->tv_sec == 0 && out->tv_usec < 15000) { 210 memset(out, 0, sizeof(struct timeval)); 211 } 212 213 return 1; 214 } 215 216 int dtls1_is_timer_expired(SSL *ssl) { 217 struct timeval timeleft; 218 219 /* Get time left until timeout, return false if no timer running */ 220 if (!DTLSv1_get_timeout(ssl, &timeleft)) { 221 return 0; 222 } 223 224 /* Return false if timer is not expired yet */ 225 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) { 226 return 0; 227 } 228 229 /* Timer expired, so return true */ 230 return 1; 231 } 232 233 void dtls1_double_timeout(SSL *ssl) { 234 ssl->d1->timeout_duration *= 2; 235 if (ssl->d1->timeout_duration > 60) { 236 ssl->d1->timeout_duration = 60; 237 } 238 dtls1_start_timer(ssl); 239 } 240 241 void dtls1_stop_timer(SSL *ssl) { 242 /* Reset everything */ 243 ssl->d1->num_timeouts = 0; 244 memset(&ssl->d1->next_timeout, 0, sizeof(struct timeval)); 245 ssl->d1->timeout_duration = 1; 246 BIO_ctrl(SSL_get_rbio(ssl), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 247 &ssl->d1->next_timeout); 248 /* Clear retransmission buffer */ 249 dtls1_clear_record_buffer(ssl); 250 } 251 252 int dtls1_check_timeout_num(SSL *ssl) { 253 ssl->d1->num_timeouts++; 254 255 /* Reduce MTU after 2 unsuccessful retransmissions */ 256 if (ssl->d1->num_timeouts > DTLS1_MTU_TIMEOUTS && 257 !(SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) { 258 long mtu = BIO_ctrl(SSL_get_wbio(ssl), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, 259 NULL); 260 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) { 261 ssl->d1->mtu = (unsigned)mtu; 262 } 263 } 264 265 if (ssl->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) { 266 /* fail the connection, enough alerts have been sent */ 267 OPENSSL_PUT_ERROR(SSL, SSL_R_READ_TIMEOUT_EXPIRED); 268 return -1; 269 } 270 271 return 0; 272 } 273 274 int DTLSv1_handle_timeout(SSL *ssl) { 275 if (!SSL_IS_DTLS(ssl)) { 276 return -1; 277 } 278 279 /* if no timer is expired, don't do anything */ 280 if (!dtls1_is_timer_expired(ssl)) { 281 return 0; 282 } 283 284 dtls1_double_timeout(ssl); 285 286 if (dtls1_check_timeout_num(ssl) < 0) { 287 return -1; 288 } 289 290 dtls1_start_timer(ssl); 291 return dtls1_retransmit_buffered_messages(ssl); 292 } 293 294 static void get_current_time(const SSL *ssl, struct timeval *out_clock) { 295 if (ssl->ctx->current_time_cb != NULL) { 296 ssl->ctx->current_time_cb(ssl, out_clock); 297 return; 298 } 299 300 #if defined(OPENSSL_WINDOWS) 301 struct _timeb time; 302 _ftime(&time); 303 out_clock->tv_sec = time.time; 304 out_clock->tv_usec = time.millitm * 1000; 305 #else 306 gettimeofday(out_clock, NULL); 307 #endif 308 } 309 310 int dtls1_set_handshake_header(SSL *ssl, int htype, unsigned long len) { 311 uint8_t *message = (uint8_t *)ssl->init_buf->data; 312 const struct hm_header_st *msg_hdr = &ssl->d1->w_msg_hdr; 313 uint8_t serialised_header[DTLS1_HM_HEADER_LENGTH]; 314 uint8_t *p = serialised_header; 315 316 ssl->d1->handshake_write_seq = ssl->d1->next_handshake_write_seq; 317 ssl->d1->next_handshake_write_seq++; 318 319 dtls1_set_message_header(ssl, htype, len, ssl->d1->handshake_write_seq, 0, 320 len); 321 ssl->init_num = (int)len + DTLS1_HM_HEADER_LENGTH; 322 ssl->init_off = 0; 323 324 /* Buffer the message to handle re-xmits */ 325 dtls1_buffer_message(ssl); 326 327 /* Add the new message to the handshake hash. Serialize the message 328 * header as if it were a single fragment. */ 329 *p++ = msg_hdr->type; 330 l2n3(msg_hdr->msg_len, p); 331 s2n(msg_hdr->seq, p); 332 l2n3(0, p); 333 l2n3(msg_hdr->msg_len, p); 334 return ssl3_update_handshake_hash(ssl, serialised_header, 335 sizeof(serialised_header)) && 336 ssl3_update_handshake_hash(ssl, message + DTLS1_HM_HEADER_LENGTH, len); 337 } 338 339 int dtls1_handshake_write(SSL *ssl) { 340 return dtls1_do_handshake_write(ssl, dtls1_use_current_epoch); 341 } 342
