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      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 <stdio.h>
     60 
     61 #if defined(OPENSSL_WINDOWS)
     62 #include <sys/timeb.h>
     63 #else
     64 #include <sys/socket.h>
     65 #include <sys/time.h>
     66 #endif
     67 
     68 #include <openssl/err.h>
     69 #include <openssl/mem.h>
     70 #include <openssl/obj.h>
     71 
     72 #include "ssl_locl.h"
     73 
     74 static void get_current_time(OPENSSL_timeval *t);
     75 static OPENSSL_timeval* dtls1_get_timeout(SSL *s, OPENSSL_timeval* timeleft);
     76 static void dtls1_set_handshake_header(SSL *s, int type, unsigned long len);
     77 static int dtls1_handshake_write(SSL *s);
     78 int dtls1_listen(SSL *s, struct sockaddr *client);
     79 
     80 SSL3_ENC_METHOD DTLSv1_enc_data={
     81     	tls1_enc,
     82 	tls1_mac,
     83 	tls1_setup_key_block,
     84 	tls1_generate_master_secret,
     85 	tls1_change_cipher_state,
     86 	tls1_final_finish_mac,
     87 	TLS1_FINISH_MAC_LENGTH,
     88 	tls1_cert_verify_mac,
     89 	TLS_MD_CLIENT_FINISH_CONST,TLS_MD_CLIENT_FINISH_CONST_SIZE,
     90 	TLS_MD_SERVER_FINISH_CONST,TLS_MD_SERVER_FINISH_CONST_SIZE,
     91 	tls1_alert_code,
     92 	tls1_export_keying_material,
     93 	SSL_ENC_FLAG_DTLS|SSL_ENC_FLAG_EXPLICIT_IV,
     94 	DTLS1_HM_HEADER_LENGTH,
     95 	dtls1_set_handshake_header,
     96 	dtls1_handshake_write
     97 	};
     98 
     99 SSL3_ENC_METHOD DTLSv1_2_enc_data={
    100     	tls1_enc,
    101 	tls1_mac,
    102 	tls1_setup_key_block,
    103 	tls1_generate_master_secret,
    104 	tls1_change_cipher_state,
    105 	tls1_final_finish_mac,
    106 	TLS1_FINISH_MAC_LENGTH,
    107 	tls1_cert_verify_mac,
    108 	TLS_MD_CLIENT_FINISH_CONST,TLS_MD_CLIENT_FINISH_CONST_SIZE,
    109 	TLS_MD_SERVER_FINISH_CONST,TLS_MD_SERVER_FINISH_CONST_SIZE,
    110 	tls1_alert_code,
    111 	tls1_export_keying_material,
    112 	SSL_ENC_FLAG_DTLS|SSL_ENC_FLAG_EXPLICIT_IV|SSL_ENC_FLAG_SIGALGS
    113 		|SSL_ENC_FLAG_SHA256_PRF|SSL_ENC_FLAG_TLS1_2_CIPHERS,
    114 	DTLS1_HM_HEADER_LENGTH,
    115 	dtls1_set_handshake_header,
    116 	dtls1_handshake_write
    117 	};
    118 
    119 int dtls1_new(SSL *s)
    120 	{
    121 	DTLS1_STATE *d1;
    122 
    123 	if (!ssl3_new(s)) return(0);
    124 	if ((d1=OPENSSL_malloc(sizeof *d1)) == NULL)
    125 		{
    126 		ssl3_free(s);
    127 		return (0);
    128 		}
    129 	memset(d1,0, sizeof *d1);
    130 
    131 	/* d1->handshake_epoch=0; */
    132 
    133 	d1->unprocessed_rcds.q=pqueue_new();
    134 	d1->processed_rcds.q=pqueue_new();
    135 	d1->buffered_messages = pqueue_new();
    136 	d1->sent_messages=pqueue_new();
    137 	d1->buffered_app_data.q=pqueue_new();
    138 
    139 	if ( s->server)
    140 		{
    141 		d1->cookie_len = sizeof(s->d1->cookie);
    142 		}
    143 
    144 	if( ! d1->unprocessed_rcds.q || ! d1->processed_rcds.q
    145         || ! d1->buffered_messages || ! d1->sent_messages || ! d1->buffered_app_data.q)
    146 		{
    147         if ( d1->unprocessed_rcds.q) pqueue_free(d1->unprocessed_rcds.q);
    148         if ( d1->processed_rcds.q) pqueue_free(d1->processed_rcds.q);
    149         if ( d1->buffered_messages) pqueue_free(d1->buffered_messages);
    150 		if ( d1->sent_messages) pqueue_free(d1->sent_messages);
    151 		if ( d1->buffered_app_data.q) pqueue_free(d1->buffered_app_data.q);
    152 		OPENSSL_free(d1);
    153 		ssl3_free(s);
    154 		return (0);
    155 		}
    156 
    157 	s->d1=d1;
    158 	s->method->ssl_clear(s);
    159 	return(1);
    160 	}
    161 
    162 static void dtls1_clear_queues(SSL *s)
    163 	{
    164     pitem *item = NULL;
    165     hm_fragment *frag = NULL;
    166 	DTLS1_RECORD_DATA *rdata;
    167 
    168     while( (item = pqueue_pop(s->d1->unprocessed_rcds.q)) != NULL)
    169         {
    170 		rdata = (DTLS1_RECORD_DATA *) item->data;
    171 		if (rdata->rbuf.buf)
    172 			{
    173 			OPENSSL_free(rdata->rbuf.buf);
    174 			}
    175         OPENSSL_free(item->data);
    176         pitem_free(item);
    177         }
    178 
    179     while( (item = pqueue_pop(s->d1->processed_rcds.q)) != NULL)
    180         {
    181 		rdata = (DTLS1_RECORD_DATA *) item->data;
    182 		if (rdata->rbuf.buf)
    183 			{
    184 			OPENSSL_free(rdata->rbuf.buf);
    185 			}
    186         OPENSSL_free(item->data);
    187         pitem_free(item);
    188         }
    189 
    190     while( (item = pqueue_pop(s->d1->buffered_messages)) != NULL)
    191         {
    192         frag = (hm_fragment *)item->data;
    193         OPENSSL_free(frag->fragment);
    194         OPENSSL_free(frag);
    195         pitem_free(item);
    196         }
    197 
    198     while ( (item = pqueue_pop(s->d1->sent_messages)) != NULL)
    199         {
    200         frag = (hm_fragment *)item->data;
    201         OPENSSL_free(frag->fragment);
    202         OPENSSL_free(frag);
    203         pitem_free(item);
    204         }
    205 
    206 	while ( (item = pqueue_pop(s->d1->buffered_app_data.q)) != NULL)
    207 		{
    208 		rdata = (DTLS1_RECORD_DATA *) item->data;
    209 		if (rdata->rbuf.buf)
    210 			{
    211 			OPENSSL_free(rdata->rbuf.buf);
    212 			}
    213 		OPENSSL_free(item->data);
    214 		pitem_free(item);
    215 		}
    216 	}
    217 
    218 void dtls1_free(SSL *s)
    219 	{
    220 	ssl3_free(s);
    221 
    222 	dtls1_clear_queues(s);
    223 
    224     pqueue_free(s->d1->unprocessed_rcds.q);
    225     pqueue_free(s->d1->processed_rcds.q);
    226     pqueue_free(s->d1->buffered_messages);
    227 	pqueue_free(s->d1->sent_messages);
    228 	pqueue_free(s->d1->buffered_app_data.q);
    229 
    230 	OPENSSL_free(s->d1);
    231 	s->d1 = NULL;
    232 	}
    233 
    234 void dtls1_clear(SSL *s)
    235 	{
    236     pqueue unprocessed_rcds;
    237     pqueue processed_rcds;
    238     pqueue buffered_messages;
    239 	pqueue sent_messages;
    240 	pqueue buffered_app_data;
    241 	unsigned int mtu;
    242 
    243 	if (s->d1)
    244 		{
    245 		unprocessed_rcds = s->d1->unprocessed_rcds.q;
    246 		processed_rcds = s->d1->processed_rcds.q;
    247 		buffered_messages = s->d1->buffered_messages;
    248 		sent_messages = s->d1->sent_messages;
    249 		buffered_app_data = s->d1->buffered_app_data.q;
    250 		mtu = s->d1->mtu;
    251 
    252 		dtls1_clear_queues(s);
    253 
    254 		memset(s->d1, 0, sizeof(*(s->d1)));
    255 
    256 		if (s->server)
    257 			{
    258 			s->d1->cookie_len = sizeof(s->d1->cookie);
    259 			}
    260 
    261 		if (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)
    262 			{
    263 			s->d1->mtu = mtu;
    264 			}
    265 
    266 		s->d1->unprocessed_rcds.q = unprocessed_rcds;
    267 		s->d1->processed_rcds.q = processed_rcds;
    268 		s->d1->buffered_messages = buffered_messages;
    269 		s->d1->sent_messages = sent_messages;
    270 		s->d1->buffered_app_data.q = buffered_app_data;
    271 		}
    272 
    273 	ssl3_clear(s);
    274 	if (s->method->version == DTLS_ANY_VERSION)
    275 		s->version=DTLS1_2_VERSION;
    276 	else
    277 		s->version=s->method->version;
    278 	}
    279 
    280 long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
    281 	{
    282 	int ret=0;
    283 
    284 	switch (cmd)
    285 		{
    286 	case DTLS_CTRL_GET_TIMEOUT:
    287 		if (dtls1_get_timeout(s, (OPENSSL_timeval*) parg) != NULL)
    288 			{
    289 			ret = 1;
    290 			}
    291 		break;
    292 	case DTLS_CTRL_HANDLE_TIMEOUT:
    293 		ret = dtls1_handle_timeout(s);
    294 		break;
    295 	case DTLS_CTRL_LISTEN:
    296 		ret = dtls1_listen(s, parg);
    297 		break;
    298 
    299 	default:
    300 		ret = ssl3_ctrl(s, cmd, larg, parg);
    301 		break;
    302 		}
    303 	return(ret);
    304 	}
    305 
    306 /*
    307  * As it's impossible to use stream ciphers in "datagram" mode, this
    308  * simple filter is designed to disengage them in DTLS. Unfortunately
    309  * there is no universal way to identify stream SSL_CIPHER, so we have
    310  * to explicitly list their SSL_* codes. Currently RC4 is the only one
    311  * available, but if new ones emerge, they will have to be added...
    312  */
    313 const SSL_CIPHER *dtls1_get_cipher(unsigned int u)
    314 	{
    315 	const SSL_CIPHER *ciph = ssl3_get_cipher(u);
    316 
    317 	if (ciph != NULL)
    318 		{
    319 		if (ciph->algorithm_enc == SSL_RC4)
    320 			return NULL;
    321 		}
    322 
    323 	return ciph;
    324 	}
    325 
    326 void dtls1_start_timer(SSL *s)
    327 	{
    328 	/* If timer is not set, initialize duration with 1 second */
    329 	if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0)
    330 		{
    331 		s->d1->timeout_duration = 1;
    332 		}
    333 
    334 	/* Set timeout to current time */
    335 	get_current_time(&s->d1->next_timeout);
    336 
    337 	/* Add duration to current time */
    338 	s->d1->next_timeout.tv_sec += s->d1->timeout_duration;
    339 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, &s->d1->next_timeout);
    340 	}
    341 
    342 static OPENSSL_timeval* dtls1_get_timeout(SSL *s, OPENSSL_timeval* timeleft)
    343 	{
    344 	OPENSSL_timeval timenow;
    345 
    346 	/* If no timeout is set, just return NULL */
    347 	if (s->d1->next_timeout.tv_sec == 0 && s->d1->next_timeout.tv_usec == 0)
    348 		{
    349 		return NULL;
    350 		}
    351 
    352 	/* Get current time */
    353 	get_current_time(&timenow);
    354 
    355 	/* If timer already expired, set remaining time to 0 */
    356 	if (s->d1->next_timeout.tv_sec < timenow.tv_sec ||
    357 		(s->d1->next_timeout.tv_sec == timenow.tv_sec &&
    358 		 s->d1->next_timeout.tv_usec <= timenow.tv_usec))
    359 		{
    360 		memset(timeleft, 0, sizeof(OPENSSL_timeval));
    361 		return timeleft;
    362 		}
    363 
    364 	/* Calculate time left until timer expires */
    365 	memcpy(timeleft, &s->d1->next_timeout, sizeof(OPENSSL_timeval));
    366 	timeleft->tv_sec -= timenow.tv_sec;
    367 	timeleft->tv_usec -= timenow.tv_usec;
    368 	if (timeleft->tv_usec < 0)
    369 		{
    370 		timeleft->tv_sec--;
    371 		timeleft->tv_usec += 1000000;
    372 		}
    373 
    374 	/* If remaining time is less than 15 ms, set it to 0
    375 	 * to prevent issues because of small devergences with
    376 	 * socket timeouts.
    377 	 */
    378 	if (timeleft->tv_sec == 0 && timeleft->tv_usec < 15000)
    379 		{
    380 		memset(timeleft, 0, sizeof(OPENSSL_timeval));
    381 		}
    382 
    383 
    384 	return timeleft;
    385 	}
    386 
    387 int dtls1_is_timer_expired(SSL *s)
    388 	{
    389 	OPENSSL_timeval timeleft;
    390 
    391 	/* Get time left until timeout, return false if no timer running */
    392 	if (dtls1_get_timeout(s, &timeleft) == NULL)
    393 		{
    394 		return 0;
    395 		}
    396 
    397 	/* Return false if timer is not expired yet */
    398 	if (timeleft.tv_sec > 0 || timeleft.tv_usec > 0)
    399 		{
    400 		return 0;
    401 		}
    402 
    403 	/* Timer expired, so return true */
    404 	return 1;
    405 	}
    406 
    407 void dtls1_double_timeout(SSL *s)
    408 	{
    409 	s->d1->timeout_duration *= 2;
    410 	if (s->d1->timeout_duration > 60)
    411 		s->d1->timeout_duration = 60;
    412 	dtls1_start_timer(s);
    413 	}
    414 
    415 void dtls1_stop_timer(SSL *s)
    416 	{
    417 	/* Reset everything */
    418 	memset(&(s->d1->timeout), 0, sizeof(struct dtls1_timeout_st));
    419 	memset(&s->d1->next_timeout, 0, sizeof(OPENSSL_timeval));
    420 	s->d1->timeout_duration = 1;
    421 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_SET_NEXT_TIMEOUT, 0, &s->d1->next_timeout);
    422 	/* Clear retransmission buffer */
    423 	dtls1_clear_record_buffer(s);
    424 	}
    425 
    426 int dtls1_check_timeout_num(SSL *s)
    427 	{
    428 	s->d1->timeout.num_alerts++;
    429 
    430 	/* Reduce MTU after 2 unsuccessful retransmissions */
    431 	if (s->d1->timeout.num_alerts > 2)
    432 		{
    433 		s->d1->mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
    434 		}
    435 
    436 	if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT)
    437 		{
    438 		/* fail the connection, enough alerts have been sent */
    439 		OPENSSL_PUT_ERROR(SSL, dtls1_check_timeout_num, SSL_R_READ_TIMEOUT_EXPIRED);
    440 		return -1;
    441 		}
    442 
    443 	return 0;
    444 	}
    445 
    446 int dtls1_handle_timeout(SSL *s)
    447 	{
    448 	/* if no timer is expired, don't do anything */
    449 	if (!dtls1_is_timer_expired(s))
    450 		{
    451 		return 0;
    452 		}
    453 
    454 	dtls1_double_timeout(s);
    455 
    456 	if (dtls1_check_timeout_num(s) < 0)
    457 		return -1;
    458 
    459 	s->d1->timeout.read_timeouts++;
    460 	if (s->d1->timeout.read_timeouts > DTLS1_TMO_READ_COUNT)
    461 		{
    462 		s->d1->timeout.read_timeouts = 1;
    463 		}
    464 
    465 	dtls1_start_timer(s);
    466 	return dtls1_retransmit_buffered_messages(s);
    467 	}
    468 
    469 static void get_current_time(OPENSSL_timeval *t)
    470 {
    471 #if defined(OPENSSL_WINDOWS)
    472 	struct _timeb time;
    473 	_ftime(&time);
    474 	t->tv_sec = time.time;
    475 	t->tv_usec = time.millitm * 1000;
    476 #else
    477 	gettimeofday(t, NULL);
    478 #endif
    479 }
    480 
    481 int dtls1_listen(SSL *s, struct sockaddr *client)
    482 	{
    483 	int ret;
    484 
    485 	SSL_set_options(s, SSL_OP_COOKIE_EXCHANGE);
    486 	s->d1->listen = 1;
    487 
    488 	ret = SSL_accept(s);
    489 	if (ret <= 0) return ret;
    490 
    491 	BIO_ctrl(SSL_get_rbio(s), BIO_CTRL_DGRAM_GET_PEER, 0, &client);
    492 	return 1;
    493 	}
    494 
    495 static void dtls1_set_handshake_header(SSL *s, int htype, unsigned long len)
    496 	{
    497 	unsigned char *p = (unsigned char *)s->init_buf->data;
    498 	dtls1_set_message_header(s, p, htype, len, 0, len);
    499 	s->init_num = (int)len + DTLS1_HM_HEADER_LENGTH;
    500 	s->init_off = 0;
    501 	/* Buffer the message to handle re-xmits */
    502 	dtls1_buffer_message(s, 0);
    503 	}
    504 
    505 static int dtls1_handshake_write(SSL *s)
    506 	{
    507 	return dtls1_do_write(s, SSL3_RT_HANDSHAKE);
    508 	}
    509