1/*
2 * DTLS implementation written by Nagendra Modadugu
3 * (nagendra@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@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@cryptsoft.com).  This product includes software written by Tim
55 * Hudson (tjh@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
84static void get_current_time(const SSL *ssl, struct timeval *out_clock);
85
86int 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
121static 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
138void 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
154int dtls1_supports_cipher(const SSL_CIPHER *cipher) {
155  /* DTLS does not support stream ciphers. */
156  return cipher->algorithm_enc != SSL_RC4;
157}
158
159void 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
174int 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
214int 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
231void 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
239void 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
250int 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
272int 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
292static 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
308int 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
335int dtls1_handshake_write(SSL *s) {
336  return dtls1_do_write(s, SSL3_RT_HANDSHAKE, dtls1_use_current_epoch);
337}
338