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/base.h> 58 59 #include <limits.h> 60 #include <stdio.h> 61 #include <string.h> 62 63 #if defined(OPENSSL_WINDOWS) 64 #include <sys/timeb.h> 65 #else 66 #include <sys/socket.h> 67 #include <sys/time.h> 68 #endif 69 70 #include <openssl/err.h> 71 #include <openssl/mem.h> 72 #include <openssl/obj.h> 73 74 #include "internal.h" 75 76 /* DTLS1_MTU_TIMEOUTS is the maximum number of timeouts to expire 77 * before starting to decrease the MTU. */ 78 #define DTLS1_MTU_TIMEOUTS 2 79 80 /* DTLS1_MAX_TIMEOUTS is the maximum number of timeouts to expire 81 * before failing the DTLS handshake. */ 82 #define DTLS1_MAX_TIMEOUTS 12 83 84 static void get_current_time(const SSL *ssl, struct timeval *out_clock); 85 86 int dtls1_new(SSL *s) { 87 DTLS1_STATE *d1; 88 89 if (!ssl3_new(s)) { 90 return 0; 91 } 92 d1 = OPENSSL_malloc(sizeof *d1); 93 if (d1 == NULL) { 94 ssl3_free(s); 95 return 0; 96 } 97 memset(d1, 0, sizeof *d1); 98 99 d1->buffered_messages = pqueue_new(); 100 d1->sent_messages = pqueue_new(); 101 102 if (!d1->buffered_messages || !d1->sent_messages) { 103 pqueue_free(d1->buffered_messages); 104 pqueue_free(d1->sent_messages); 105 OPENSSL_free(d1); 106 ssl3_free(s); 107 return 0; 108 } 109 110 s->d1 = d1; 111 112 /* Set the version to the highest version for DTLS. This controls the initial 113 * state of |s->enc_method| and what the API reports as the version prior to 114 * negotiation. 115 * 116 * TODO(davidben): This is fragile and confusing. */ 117 s->version = DTLS1_2_VERSION; 118 return 1; 119 } 120 121 static void dtls1_clear_queues(SSL *s) { 122 pitem *item = NULL; 123 hm_fragment *frag = NULL; 124 125 while ((item = pqueue_pop(s->d1->buffered_messages)) != NULL) { 126 frag = (hm_fragment *)item->data; 127 dtls1_hm_fragment_free(frag); 128 pitem_free(item); 129 } 130 131 while ((item = pqueue_pop(s->d1->sent_messages)) != NULL) { 132 frag = (hm_fragment *)item->data; 133 dtls1_hm_fragment_free(frag); 134 pitem_free(item); 135 } 136 } 137 138 void dtls1_free(SSL *s) { 139 ssl3_free(s); 140 141 if (s == NULL || s->d1 == NULL) { 142 return; 143 } 144 145 dtls1_clear_queues(s); 146 147 pqueue_free(s->d1->buffered_messages); 148 pqueue_free(s->d1->sent_messages); 149 150 OPENSSL_free(s->d1); 151 s->d1 = NULL; 152 } 153 154 int dtls1_supports_cipher(const SSL_CIPHER *cipher) { 155 /* DTLS does not support stream ciphers. */ 156 return cipher->algorithm_enc != SSL_RC4; 157 } 158 159 void dtls1_start_timer(SSL *s) { 160 /* If timer is not set, initialize duration with 1 second */ 161 if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0) { 162 s->d1->timeout_duration = 1; 163 } 164 165 /* Set timeout to current time */ 166 get_current_time(s, &s->d1->next_timeout); 167 168 /* Add duration to current time */ 169 s->d1->next_timeout.tv_sec += s->d1->timeout_duration; 170 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 171 &s->d1->next_timeout); 172 } 173 174 int DTLSv1_get_timeout(const SSL *ssl, struct timeval *out) { 175 if (!SSL_IS_DTLS(ssl)) { 176 return 0; 177 } 178 179 /* If no timeout is set, just return NULL */ 180 if (ssl->d1->next_timeout.tv_sec == 0 && ssl->d1->next_timeout.tv_usec == 0) { 181 return 0; 182 } 183 184 /* Get current time */ 185 struct timeval timenow; 186 get_current_time(ssl, &timenow); 187 188 /* If timer already expired, set remaining time to 0 */ 189 if (ssl->d1->next_timeout.tv_sec < timenow.tv_sec || 190 (ssl->d1->next_timeout.tv_sec == timenow.tv_sec && 191 ssl->d1->next_timeout.tv_usec <= timenow.tv_usec)) { 192 memset(out, 0, sizeof(struct timeval)); 193 return 1; 194 } 195 196 /* Calculate time left until timer expires */ 197 memcpy(out, &ssl->d1->next_timeout, sizeof(struct timeval)); 198 out->tv_sec -= timenow.tv_sec; 199 out->tv_usec -= timenow.tv_usec; 200 if (out->tv_usec < 0) { 201 out->tv_sec--; 202 out->tv_usec += 1000000; 203 } 204 205 /* If remaining time is less than 15 ms, set it to 0 to prevent issues 206 * because of small devergences with socket timeouts. */ 207 if (out->tv_sec == 0 && out->tv_usec < 15000) { 208 memset(out, 0, sizeof(struct timeval)); 209 } 210 211 return 1; 212 } 213 214 int dtls1_is_timer_expired(SSL *s) { 215 struct timeval timeleft; 216 217 /* Get time left until timeout, return false if no timer running */ 218 if (!DTLSv1_get_timeout(s, &timeleft)) { 219 return 0; 220 } 221 222 /* Return false if timer is not expired yet */ 223 if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0) { 224 return 0; 225 } 226 227 /* Timer expired, so return true */ 228 return 1; 229 } 230 231 void dtls1_double_timeout(SSL *s) { 232 s->d1->timeout_duration *= 2; 233 if (s->d1->timeout_duration > 60) { 234 s->d1->timeout_duration = 60; 235 } 236 dtls1_start_timer(s); 237 } 238 239 void dtls1_stop_timer(SSL *s) { 240 /* Reset everything */ 241 s->d1->num_timeouts = 0; 242 memset(&s->d1->next_timeout, 0, sizeof(struct timeval)); 243 s->d1->timeout_duration = 1; 244 BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, 245 &s->d1->next_timeout); 246 /* Clear retransmission buffer */ 247 dtls1_clear_record_buffer(s); 248 } 249 250 int dtls1_check_timeout_num(SSL *s) { 251 s->d1->num_timeouts++; 252 253 /* Reduce MTU after 2 unsuccessful retransmissions */ 254 if (s->d1->num_timeouts > DTLS1_MTU_TIMEOUTS && 255 !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) { 256 long mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, 257 NULL); 258 if (mtu >= 0 && mtu <= (1 << 30) && (unsigned)mtu >= dtls1_min_mtu()) { 259 s->d1->mtu = (unsigned)mtu; 260 } 261 } 262 263 if (s->d1->num_timeouts > DTLS1_MAX_TIMEOUTS) { 264 /* fail the connection, enough alerts have been sent */ 265 OPENSSL_PUT_ERROR(SSL, dtls1_check_timeout_num, SSL_R_READ_TIMEOUT_EXPIRED); 266 return -1; 267 } 268 269 return 0; 270 } 271 272 int DTLSv1_handle_timeout(SSL *ssl) { 273 if (!SSL_IS_DTLS(ssl)) { 274 return -1; 275 } 276 277 /* if no timer is expired, don't do anything */ 278 if (!dtls1_is_timer_expired(ssl)) { 279 return 0; 280 } 281 282 dtls1_double_timeout(ssl); 283 284 if (dtls1_check_timeout_num(ssl) < 0) { 285 return -1; 286 } 287 288 dtls1_start_timer(ssl); 289 return dtls1_retransmit_buffered_messages(ssl); 290 } 291 292 static void get_current_time(const SSL *ssl, struct timeval *out_clock) { 293 if (ssl->ctx->current_time_cb != NULL) { 294 ssl->ctx->current_time_cb(ssl, out_clock); 295 return; 296 } 297 298 #if defined(OPENSSL_WINDOWS) 299 struct _timeb time; 300 _ftime(&time); 301 out_clock->tv_sec = time.time; 302 out_clock->tv_usec = time.millitm * 1000; 303 #else 304 gettimeofday(out_clock, NULL); 305 #endif 306 } 307 308 int dtls1_set_handshake_header(SSL *s, int htype, unsigned long len) { 309 uint8_t *message = (uint8_t *)s->init_buf->data; 310 const struct hm_header_st *msg_hdr = &s->d1->w_msg_hdr; 311 uint8_t serialised_header[DTLS1_HM_HEADER_LENGTH]; 312 uint8_t *p = serialised_header; 313 314 s->d1->handshake_write_seq = s->d1->next_handshake_write_seq; 315 s->d1->next_handshake_write_seq++; 316 317 dtls1_set_message_header(s, htype, len, s->d1->handshake_write_seq, 0, len); 318 s->init_num = (int)len + DTLS1_HM_HEADER_LENGTH; 319 s->init_off = 0; 320 321 /* Buffer the message to handle re-xmits */ 322 dtls1_buffer_message(s, 0); 323 324 /* Add the new message to the handshake hash. Serialize the message 325 * header as if it were a single fragment. */ 326 *p++ = msg_hdr->type; 327 l2n3(msg_hdr->msg_len, p); 328 s2n(msg_hdr->seq, p); 329 l2n3(0, p); 330 l2n3(msg_hdr->msg_len, p); 331 return ssl3_finish_mac(s, serialised_header, sizeof(serialised_header)) && 332 ssl3_finish_mac(s, message + DTLS1_HM_HEADER_LENGTH, len); 333 } 334 335 int dtls1_handshake_write(SSL *s) { 336 return dtls1_do_write(s, SSL3_RT_HANDSHAKE, dtls1_use_current_epoch); 337 } 338
