xref: /dragonfly/crypto/libressl/ssl/d1_both.c (revision 193f58b8)
1 /* $OpenBSD: d1_both.c,v 1.57 2019/02/10 16:42:35 phessler Exp $ */
2 /*
3  * DTLS implementation written by Nagendra Modadugu
4  * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
5  */
6 /* ====================================================================
7  * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in
18  *    the documentation and/or other materials provided with the
19  *    distribution.
20  *
21  * 3. All advertising materials mentioning features or use of this
22  *    software must display the following acknowledgment:
23  *    "This product includes software developed by the OpenSSL Project
24  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
25  *
26  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
27  *    endorse or promote products derived from this software without
28  *    prior written permission. For written permission, please contact
29  *    openssl-core@openssl.org.
30  *
31  * 5. Products derived from this software may not be called "OpenSSL"
32  *    nor may "OpenSSL" appear in their names without prior written
33  *    permission of the OpenSSL Project.
34  *
35  * 6. Redistributions of any form whatsoever must retain the following
36  *    acknowledgment:
37  *    "This product includes software developed by the OpenSSL Project
38  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
39  *
40  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
41  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
43  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
44  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
45  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
46  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
49  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
50  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
51  * OF THE POSSIBILITY OF SUCH DAMAGE.
52  * ====================================================================
53  *
54  * This product includes cryptographic software written by Eric Young
55  * (eay@cryptsoft.com).  This product includes software written by Tim
56  * Hudson (tjh@cryptsoft.com).
57  *
58  */
59 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
60  * All rights reserved.
61  *
62  * This package is an SSL implementation written
63  * by Eric Young (eay@cryptsoft.com).
64  * The implementation was written so as to conform with Netscapes SSL.
65  *
66  * This library is free for commercial and non-commercial use as long as
67  * the following conditions are aheared to.  The following conditions
68  * apply to all code found in this distribution, be it the RC4, RSA,
69  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
70  * included with this distribution is covered by the same copyright terms
71  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
72  *
73  * Copyright remains Eric Young's, and as such any Copyright notices in
74  * the code are not to be removed.
75  * If this package is used in a product, Eric Young should be given attribution
76  * as the author of the parts of the library used.
77  * This can be in the form of a textual message at program startup or
78  * in documentation (online or textual) provided with the package.
79  *
80  * Redistribution and use in source and binary forms, with or without
81  * modification, are permitted provided that the following conditions
82  * are met:
83  * 1. Redistributions of source code must retain the copyright
84  *    notice, this list of conditions and the following disclaimer.
85  * 2. Redistributions in binary form must reproduce the above copyright
86  *    notice, this list of conditions and the following disclaimer in the
87  *    documentation and/or other materials provided with the distribution.
88  * 3. All advertising materials mentioning features or use of this software
89  *    must display the following acknowledgement:
90  *    "This product includes cryptographic software written by
91  *     Eric Young (eay@cryptsoft.com)"
92  *    The word 'cryptographic' can be left out if the rouines from the library
93  *    being used are not cryptographic related :-).
94  * 4. If you include any Windows specific code (or a derivative thereof) from
95  *    the apps directory (application code) you must include an acknowledgement:
96  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
97  *
98  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
99  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
100  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
101  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
102  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
103  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
104  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
105  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
106  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
107  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
108  * SUCH DAMAGE.
109  *
110  * The licence and distribution terms for any publically available version or
111  * derivative of this code cannot be changed.  i.e. this code cannot simply be
112  * copied and put under another distribution licence
113  * [including the GNU Public Licence.]
114  */
115 
116 #include <limits.h>
117 #include <stdio.h>
118 #include <string.h>
119 
120 #include "ssl_locl.h"
121 
122 #include <openssl/buffer.h>
123 #include <openssl/evp.h>
124 #include <openssl/objects.h>
125 #include <openssl/x509.h>
126 
127 #include "pqueue.h"
128 #include "bytestring.h"
129 
130 #define RSMBLY_BITMASK_SIZE(msg_len) (((msg_len) + 7) / 8)
131 
132 #define RSMBLY_BITMASK_MARK(bitmask, start, end) { \
133 			if ((end) - (start) <= 8) { \
134 				long ii; \
135 				for (ii = (start); ii < (end); ii++) bitmask[((ii) >> 3)] |= (1 << ((ii) & 7)); \
136 			} else { \
137 				long ii; \
138 				bitmask[((start) >> 3)] |= bitmask_start_values[((start) & 7)]; \
139 				for (ii = (((start) >> 3) + 1); ii < ((((end) - 1)) >> 3); ii++) bitmask[ii] = 0xff; \
140 				bitmask[(((end) - 1) >> 3)] |= bitmask_end_values[((end) & 7)]; \
141 			} }
142 
143 #define RSMBLY_BITMASK_IS_COMPLETE(bitmask, msg_len, is_complete) { \
144 			long ii; \
145 			OPENSSL_assert((msg_len) > 0); \
146 			is_complete = 1; \
147 			if (bitmask[(((msg_len) - 1) >> 3)] != bitmask_end_values[((msg_len) & 7)]) is_complete = 0; \
148 			if (is_complete) for (ii = (((msg_len) - 1) >> 3) - 1; ii >= 0 ; ii--) \
149 				if (bitmask[ii] != 0xff) { is_complete = 0; break; } }
150 
151 static unsigned char bitmask_start_values[] = {
152 	0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80
153 };
154 static unsigned char bitmask_end_values[] = {
155 	0xff, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f
156 };
157 
158 /* XDTLS:  figure out the right values */
159 static unsigned int g_probable_mtu[] = {1500 - 28, 512 - 28, 256 - 28};
160 
161 static unsigned int dtls1_guess_mtu(unsigned int curr_mtu);
162 static void dtls1_fix_message_header(SSL *s, unsigned long frag_off,
163     unsigned long frag_len);
164 static int dtls1_write_message_header(const struct hm_header_st *msg_hdr,
165     unsigned long frag_off, unsigned long frag_len, unsigned char *p);
166 static long dtls1_get_message_fragment(SSL *s, int st1, int stn, long max,
167     int *ok);
168 
169 static hm_fragment *
170 dtls1_hm_fragment_new(unsigned long frag_len, int reassembly)
171 {
172 	hm_fragment *frag = NULL;
173 	unsigned char *buf = NULL;
174 	unsigned char *bitmask = NULL;
175 
176 	frag = malloc(sizeof(hm_fragment));
177 	if (frag == NULL)
178 		return NULL;
179 
180 	if (frag_len) {
181 		buf = malloc(frag_len);
182 		if (buf == NULL) {
183 			free(frag);
184 			return NULL;
185 		}
186 	}
187 
188 	/* zero length fragment gets zero frag->fragment */
189 	frag->fragment = buf;
190 
191 	/* Initialize reassembly bitmask if necessary */
192 	if (reassembly) {
193 		bitmask = malloc(RSMBLY_BITMASK_SIZE(frag_len));
194 		if (bitmask == NULL) {
195 			free(buf);
196 			free(frag);
197 			return NULL;
198 		}
199 		memset(bitmask, 0, RSMBLY_BITMASK_SIZE(frag_len));
200 	}
201 
202 	frag->reassembly = bitmask;
203 
204 	return frag;
205 }
206 
207 static void
208 dtls1_hm_fragment_free(hm_fragment *frag)
209 {
210 	if (frag == NULL)
211 		return;
212 
213 	if (frag->msg_header.is_ccs) {
214 		EVP_CIPHER_CTX_free(
215 		    frag->msg_header.saved_retransmit_state.enc_write_ctx);
216 		EVP_MD_CTX_free(
217 		    frag->msg_header.saved_retransmit_state.write_hash);
218 	}
219 	free(frag->fragment);
220 	free(frag->reassembly);
221 	free(frag);
222 }
223 
224 /* send s->internal->init_buf in records of type 'type' (SSL3_RT_HANDSHAKE or SSL3_RT_CHANGE_CIPHER_SPEC) */
225 int
226 dtls1_do_write(SSL *s, int type)
227 {
228 	int ret;
229 	int curr_mtu;
230 	unsigned int len, frag_off, mac_size, blocksize;
231 
232 	/* AHA!  Figure out the MTU, and stick to the right size */
233 	if (D1I(s)->mtu < dtls1_min_mtu() &&
234 	    !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU)) {
235 		D1I(s)->mtu = BIO_ctrl(SSL_get_wbio(s),
236 		    BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
237 
238 		/*
239 		 * I've seen the kernel return bogus numbers when it
240 		 * doesn't know the MTU (ie., the initial write), so just
241 		 * make sure we have a reasonable number
242 		 */
243 		if (D1I(s)->mtu < dtls1_min_mtu()) {
244 			D1I(s)->mtu = 0;
245 			D1I(s)->mtu = dtls1_guess_mtu(D1I(s)->mtu);
246 			BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SET_MTU,
247 			    D1I(s)->mtu, NULL);
248 		}
249 	}
250 
251 	OPENSSL_assert(D1I(s)->mtu >= dtls1_min_mtu());
252 	/* should have something reasonable now */
253 
254 	if (s->internal->init_off == 0  && type == SSL3_RT_HANDSHAKE)
255 		OPENSSL_assert(s->internal->init_num ==
256 		    (int)D1I(s)->w_msg_hdr.msg_len + DTLS1_HM_HEADER_LENGTH);
257 
258 	if (s->internal->write_hash)
259 		mac_size = EVP_MD_CTX_size(s->internal->write_hash);
260 	else
261 		mac_size = 0;
262 
263 	if (s->internal->enc_write_ctx &&
264 	    (EVP_CIPHER_mode( s->internal->enc_write_ctx->cipher) & EVP_CIPH_CBC_MODE))
265 		blocksize = 2 * EVP_CIPHER_block_size(s->internal->enc_write_ctx->cipher);
266 	else
267 		blocksize = 0;
268 
269 	frag_off = 0;
270 	while (s->internal->init_num) {
271 		curr_mtu = D1I(s)->mtu - BIO_wpending(SSL_get_wbio(s)) -
272 		    DTLS1_RT_HEADER_LENGTH - mac_size - blocksize;
273 
274 		if (curr_mtu <= DTLS1_HM_HEADER_LENGTH) {
275 			/* grr.. we could get an error if MTU picked was wrong */
276 			ret = BIO_flush(SSL_get_wbio(s));
277 			if (ret <= 0)
278 				return ret;
279 			curr_mtu = D1I(s)->mtu - DTLS1_RT_HEADER_LENGTH -
280 			    mac_size - blocksize;
281 		}
282 
283 		if (s->internal->init_num > curr_mtu)
284 			len = curr_mtu;
285 		else
286 			len = s->internal->init_num;
287 
288 
289 		/* XDTLS: this function is too long.  split out the CCS part */
290 		if (type == SSL3_RT_HANDSHAKE) {
291 			if (s->internal->init_off != 0) {
292 				OPENSSL_assert(s->internal->init_off > DTLS1_HM_HEADER_LENGTH);
293 				s->internal->init_off -= DTLS1_HM_HEADER_LENGTH;
294 				s->internal->init_num += DTLS1_HM_HEADER_LENGTH;
295 
296 				if (s->internal->init_num > curr_mtu)
297 					len = curr_mtu;
298 				else
299 					len = s->internal->init_num;
300 			}
301 
302 			dtls1_fix_message_header(s, frag_off,
303 			    len - DTLS1_HM_HEADER_LENGTH);
304 
305 			if (!dtls1_write_message_header(&D1I(s)->w_msg_hdr,
306 			    D1I(s)->w_msg_hdr.frag_off, D1I(s)->w_msg_hdr.frag_len,
307 			    (unsigned char *)&s->internal->init_buf->data[s->internal->init_off]))
308 				return -1;
309 
310 			OPENSSL_assert(len >= DTLS1_HM_HEADER_LENGTH);
311 		}
312 
313 		ret = dtls1_write_bytes(s, type,
314 		    &s->internal->init_buf->data[s->internal->init_off], len);
315 		if (ret < 0) {
316 			/*
317 			 * Might need to update MTU here, but we don't know
318 			 * which previous packet caused the failure -- so
319 			 * can't really retransmit anything.  continue as
320 			 * if everything is fine and wait for an alert to
321 			 * handle the retransmit
322 			 */
323 			if (BIO_ctrl(SSL_get_wbio(s),
324 			    BIO_CTRL_DGRAM_MTU_EXCEEDED, 0, NULL) > 0)
325 				D1I(s)->mtu = BIO_ctrl(SSL_get_wbio(s),
326 				    BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
327 			else
328 				return (-1);
329 		} else {
330 
331 			/*
332 			 * Bad if this assert fails, only part of the
333 			 * handshake message got sent.  but why would
334 			 * this happen?
335 			 */
336 			OPENSSL_assert(len == (unsigned int)ret);
337 
338 			if (type == SSL3_RT_HANDSHAKE &&
339 			    !D1I(s)->retransmitting) {
340 				/*
341 				 * Should not be done for 'Hello Request's,
342 				 * but in that case we'll ignore the result
343 				 * anyway
344 				 */
345 				unsigned char *p = (unsigned char *)&s->internal->init_buf->data[s->internal->init_off];
346 				const struct hm_header_st *msg_hdr = &D1I(s)->w_msg_hdr;
347 				int xlen;
348 
349 				if (frag_off == 0) {
350 					/*
351 					 * Reconstruct message header is if it
352 					 * is being sent in single fragment
353 					 */
354 					if (!dtls1_write_message_header(msg_hdr,
355 					    0, msg_hdr->msg_len, p))
356 						return (-1);
357 					xlen = ret;
358 				} else {
359 					p += DTLS1_HM_HEADER_LENGTH;
360 					xlen = ret - DTLS1_HM_HEADER_LENGTH;
361 				}
362 
363 				tls1_transcript_record(s, p, xlen);
364 			}
365 
366 			if (ret == s->internal->init_num) {
367 				if (s->internal->msg_callback)
368 					s->internal->msg_callback(1, s->version, type,
369 					    s->internal->init_buf->data,
370 					    (size_t)(s->internal->init_off + s->internal->init_num),
371 					    s, s->internal->msg_callback_arg);
372 
373 				s->internal->init_off = 0;
374 				/* done writing this message */
375 				s->internal->init_num = 0;
376 
377 				return (1);
378 			}
379 			s->internal->init_off += ret;
380 			s->internal->init_num -= ret;
381 			frag_off += (ret -= DTLS1_HM_HEADER_LENGTH);
382 		}
383 	}
384 	return (0);
385 }
386 
387 
388 /*
389  * Obtain handshake message of message type 'mt' (any if mt == -1),
390  * maximum acceptable body length 'max'.
391  * Read an entire handshake message.  Handshake messages arrive in
392  * fragments.
393  */
394 long
395 dtls1_get_message(SSL *s, int st1, int stn, int mt, long max, int *ok)
396 {
397 	int i, al;
398 	struct hm_header_st *msg_hdr;
399 	unsigned char *p;
400 	unsigned long msg_len;
401 
402 	/*
403 	 * s3->internal->tmp is used to store messages that are unexpected, caused
404 	 * by the absence of an optional handshake message
405 	 */
406 	if (S3I(s)->tmp.reuse_message) {
407 		S3I(s)->tmp.reuse_message = 0;
408 		if ((mt >= 0) && (S3I(s)->tmp.message_type != mt)) {
409 			al = SSL_AD_UNEXPECTED_MESSAGE;
410 			SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
411 			goto f_err;
412 		}
413 		*ok = 1;
414 		s->internal->init_msg = s->internal->init_buf->data + DTLS1_HM_HEADER_LENGTH;
415 		s->internal->init_num = (int)S3I(s)->tmp.message_size;
416 		return s->internal->init_num;
417 	}
418 
419 	msg_hdr = &D1I(s)->r_msg_hdr;
420 	memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
421 
422 again:
423 	i = dtls1_get_message_fragment(s, st1, stn, max, ok);
424 	if (i == DTLS1_HM_BAD_FRAGMENT ||
425 	    i == DTLS1_HM_FRAGMENT_RETRY)  /* bad fragment received */
426 		goto again;
427 	else if (i <= 0 && !*ok)
428 		return i;
429 
430 	p = (unsigned char *)s->internal->init_buf->data;
431 	msg_len = msg_hdr->msg_len;
432 
433 	/* reconstruct message header */
434 	if (!dtls1_write_message_header(msg_hdr, 0, msg_len, p))
435 		return -1;
436 
437 	msg_len += DTLS1_HM_HEADER_LENGTH;
438 
439 	tls1_transcript_record(s, p, msg_len);
440 	if (s->internal->msg_callback)
441 		s->internal->msg_callback(0, s->version, SSL3_RT_HANDSHAKE, p, msg_len,
442 		    s, s->internal->msg_callback_arg);
443 
444 	memset(msg_hdr, 0x00, sizeof(struct hm_header_st));
445 
446 	/* Don't change sequence numbers while listening */
447 	if (!D1I(s)->listen)
448 		D1I(s)->handshake_read_seq++;
449 
450 	s->internal->init_msg = s->internal->init_buf->data + DTLS1_HM_HEADER_LENGTH;
451 	return s->internal->init_num;
452 
453 f_err:
454 	ssl3_send_alert(s, SSL3_AL_FATAL, al);
455 	*ok = 0;
456 	return -1;
457 }
458 
459 
460 static int
461 dtls1_preprocess_fragment(SSL *s, struct hm_header_st *msg_hdr, int max)
462 {
463 	size_t frag_off, frag_len, msg_len;
464 
465 	msg_len = msg_hdr->msg_len;
466 	frag_off = msg_hdr->frag_off;
467 	frag_len = msg_hdr->frag_len;
468 
469 	/* sanity checking */
470 	if ((frag_off + frag_len) > msg_len) {
471 		SSLerror(s, SSL_R_EXCESSIVE_MESSAGE_SIZE);
472 		return SSL_AD_ILLEGAL_PARAMETER;
473 	}
474 
475 	if ((frag_off + frag_len) > (unsigned long)max) {
476 		SSLerror(s, SSL_R_EXCESSIVE_MESSAGE_SIZE);
477 		return SSL_AD_ILLEGAL_PARAMETER;
478 	}
479 
480 	if ( D1I(s)->r_msg_hdr.frag_off == 0) /* first fragment */
481 	{
482 		/*
483 		 * msg_len is limited to 2^24, but is effectively checked
484 		 * against max above
485 		 */
486 		if (!BUF_MEM_grow_clean(s->internal->init_buf,
487 		    msg_len + DTLS1_HM_HEADER_LENGTH)) {
488 			SSLerror(s, ERR_R_BUF_LIB);
489 			return SSL_AD_INTERNAL_ERROR;
490 		}
491 
492 		S3I(s)->tmp.message_size = msg_len;
493 		D1I(s)->r_msg_hdr.msg_len = msg_len;
494 		S3I(s)->tmp.message_type = msg_hdr->type;
495 		D1I(s)->r_msg_hdr.type = msg_hdr->type;
496 		D1I(s)->r_msg_hdr.seq = msg_hdr->seq;
497 	} else if (msg_len != D1I(s)->r_msg_hdr.msg_len) {
498 		/*
499 		 * They must be playing with us! BTW, failure to enforce
500 		 * upper limit would open possibility for buffer overrun.
501 		 */
502 		SSLerror(s, SSL_R_EXCESSIVE_MESSAGE_SIZE);
503 		return SSL_AD_ILLEGAL_PARAMETER;
504 	}
505 
506 	return 0; /* no error */
507 }
508 
509 static int
510 dtls1_retrieve_buffered_fragment(SSL *s, long max, int *ok)
511 {
512 	/*
513 	 * (0) check whether the desired fragment is available
514 	 * if so:
515 	 * (1) copy over the fragment to s->internal->init_buf->data[]
516 	 * (2) update s->internal->init_num
517 	 */
518 	pitem *item;
519 	hm_fragment *frag;
520 	int al;
521 
522 	*ok = 0;
523 	item = pqueue_peek(D1I(s)->buffered_messages);
524 	if (item == NULL)
525 		return 0;
526 
527 	frag = (hm_fragment *)item->data;
528 
529 	/* Don't return if reassembly still in progress */
530 	if (frag->reassembly != NULL)
531 		return 0;
532 
533 	if (D1I(s)->handshake_read_seq == frag->msg_header.seq) {
534 		unsigned long frag_len = frag->msg_header.frag_len;
535 		pqueue_pop(D1I(s)->buffered_messages);
536 
537 		al = dtls1_preprocess_fragment(s, &frag->msg_header, max);
538 
539 		if (al == 0) /* no alert */
540 		{
541 			unsigned char *p = (unsigned char *)s->internal->init_buf->data + DTLS1_HM_HEADER_LENGTH;
542 			memcpy(&p[frag->msg_header.frag_off],
543 			    frag->fragment, frag->msg_header.frag_len);
544 		}
545 
546 		dtls1_hm_fragment_free(frag);
547 		pitem_free(item);
548 
549 		if (al == 0) {
550 			*ok = 1;
551 			return frag_len;
552 		}
553 
554 		ssl3_send_alert(s, SSL3_AL_FATAL, al);
555 		s->internal->init_num = 0;
556 		*ok = 0;
557 		return -1;
558 	} else
559 		return 0;
560 }
561 
562 /*
563  * dtls1_max_handshake_message_len returns the maximum number of bytes
564  * permitted in a DTLS handshake message for |s|. The minimum is 16KB,
565  * but may be greater if the maximum certificate list size requires it.
566  */
567 static unsigned long
568 dtls1_max_handshake_message_len(const SSL *s)
569 {
570 	unsigned long max_len;
571 
572 	max_len = DTLS1_HM_HEADER_LENGTH + SSL3_RT_MAX_ENCRYPTED_LENGTH;
573 	if (max_len < (unsigned long)s->internal->max_cert_list)
574 		return s->internal->max_cert_list;
575 	return max_len;
576 }
577 
578 static int
579 dtls1_reassemble_fragment(SSL *s, struct hm_header_st* msg_hdr, int *ok)
580 {
581 	hm_fragment *frag = NULL;
582 	pitem *item = NULL;
583 	int i = -1, is_complete;
584 	unsigned char seq64be[8];
585 	unsigned long frag_len = msg_hdr->frag_len;
586 
587 	if ((msg_hdr->frag_off + frag_len) > msg_hdr->msg_len ||
588 	    msg_hdr->msg_len > dtls1_max_handshake_message_len(s))
589 		goto err;
590 
591 	if (frag_len == 0) {
592 		i = DTLS1_HM_FRAGMENT_RETRY;
593 		goto err;
594 	}
595 
596 	/* Try to find item in queue */
597 	memset(seq64be, 0, sizeof(seq64be));
598 	seq64be[6] = (unsigned char)(msg_hdr->seq >> 8);
599 	seq64be[7] = (unsigned char)msg_hdr->seq;
600 	item = pqueue_find(D1I(s)->buffered_messages, seq64be);
601 
602 	if (item == NULL) {
603 		frag = dtls1_hm_fragment_new(msg_hdr->msg_len, 1);
604 		if (frag == NULL)
605 			goto err;
606 		memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
607 		frag->msg_header.frag_len = frag->msg_header.msg_len;
608 		frag->msg_header.frag_off = 0;
609 	} else {
610 		frag = (hm_fragment*)item->data;
611 		if (frag->msg_header.msg_len != msg_hdr->msg_len) {
612 			item = NULL;
613 			frag = NULL;
614 			goto err;
615 		}
616 	}
617 
618 	/*
619 	 * If message is already reassembled, this must be a
620 	 * retransmit and can be dropped.
621 	 */
622 	if (frag->reassembly == NULL) {
623 		unsigned char devnull [256];
624 
625 		while (frag_len) {
626 			i = s->method->internal->ssl_read_bytes(s, SSL3_RT_HANDSHAKE,
627 			    devnull, frag_len > sizeof(devnull) ?
628 			    sizeof(devnull) : frag_len, 0);
629 			if (i <= 0)
630 				goto err;
631 			frag_len -= i;
632 		}
633 		i = DTLS1_HM_FRAGMENT_RETRY;
634 		goto err;
635 	}
636 
637 	/* read the body of the fragment (header has already been read */
638 	i = s->method->internal->ssl_read_bytes(s, SSL3_RT_HANDSHAKE,
639 	    frag->fragment + msg_hdr->frag_off, frag_len, 0);
640 	if (i <= 0 || (unsigned long)i != frag_len)
641 		goto err;
642 
643 	RSMBLY_BITMASK_MARK(frag->reassembly, (long)msg_hdr->frag_off,
644 	    (long)(msg_hdr->frag_off + frag_len));
645 
646 	RSMBLY_BITMASK_IS_COMPLETE(frag->reassembly, (long)msg_hdr->msg_len,
647 	    is_complete);
648 
649 	if (is_complete) {
650 		free(frag->reassembly);
651 		frag->reassembly = NULL;
652 	}
653 
654 	if (item == NULL) {
655 		memset(seq64be, 0, sizeof(seq64be));
656 		seq64be[6] = (unsigned char)(msg_hdr->seq >> 8);
657 		seq64be[7] = (unsigned char)(msg_hdr->seq);
658 
659 		item = pitem_new(seq64be, frag);
660 		if (item == NULL) {
661 			i = -1;
662 			goto err;
663 		}
664 
665 		pqueue_insert(D1I(s)->buffered_messages, item);
666 	}
667 
668 	return DTLS1_HM_FRAGMENT_RETRY;
669 
670 err:
671 	if (item == NULL && frag != NULL)
672 		dtls1_hm_fragment_free(frag);
673 	*ok = 0;
674 	return i;
675 }
676 
677 
678 static int
679 dtls1_process_out_of_seq_message(SSL *s, struct hm_header_st* msg_hdr, int *ok)
680 {
681 	int i = -1;
682 	hm_fragment *frag = NULL;
683 	pitem *item = NULL;
684 	unsigned char seq64be[8];
685 	unsigned long frag_len = msg_hdr->frag_len;
686 
687 	if ((msg_hdr->frag_off + frag_len) > msg_hdr->msg_len)
688 		goto err;
689 
690 	/* Try to find item in queue, to prevent duplicate entries */
691 	memset(seq64be, 0, sizeof(seq64be));
692 	seq64be[6] = (unsigned char) (msg_hdr->seq >> 8);
693 	seq64be[7] = (unsigned char) msg_hdr->seq;
694 	item = pqueue_find(D1I(s)->buffered_messages, seq64be);
695 
696 	/*
697 	 * If we already have an entry and this one is a fragment,
698 	 * don't discard it and rather try to reassemble it.
699 	 */
700 	if (item != NULL && frag_len < msg_hdr->msg_len)
701 		item = NULL;
702 
703 	/*
704 	 * Discard the message if sequence number was already there, is
705 	 * too far in the future, already in the queue or if we received
706 	 * a FINISHED before the SERVER_HELLO, which then must be a stale
707 	 * retransmit.
708 	 */
709 	if (msg_hdr->seq <= D1I(s)->handshake_read_seq ||
710 	    msg_hdr->seq > D1I(s)->handshake_read_seq + 10 || item != NULL ||
711 	    (D1I(s)->handshake_read_seq == 0 &&
712 	    msg_hdr->type == SSL3_MT_FINISHED)) {
713 		unsigned char devnull [256];
714 
715 		while (frag_len) {
716 			i = s->method->internal->ssl_read_bytes(s, SSL3_RT_HANDSHAKE,
717 			    devnull, frag_len > sizeof(devnull) ?
718 			    sizeof(devnull) : frag_len, 0);
719 			if (i <= 0)
720 				goto err;
721 			frag_len -= i;
722 		}
723 	} else {
724 		if (frag_len < msg_hdr->msg_len)
725 			return dtls1_reassemble_fragment(s, msg_hdr, ok);
726 
727 		if (frag_len > dtls1_max_handshake_message_len(s))
728 			goto err;
729 
730 		frag = dtls1_hm_fragment_new(frag_len, 0);
731 		if (frag == NULL)
732 			goto err;
733 
734 		memcpy(&(frag->msg_header), msg_hdr, sizeof(*msg_hdr));
735 
736 		if (frag_len) {
737 			/* read the body of the fragment (header has already been read */
738 			i = s->method->internal->ssl_read_bytes(s, SSL3_RT_HANDSHAKE,
739 			    frag->fragment, frag_len, 0);
740 			if (i <= 0 || (unsigned long)i != frag_len)
741 				goto err;
742 		}
743 
744 		memset(seq64be, 0, sizeof(seq64be));
745 		seq64be[6] = (unsigned char)(msg_hdr->seq >> 8);
746 		seq64be[7] = (unsigned char)(msg_hdr->seq);
747 
748 		item = pitem_new(seq64be, frag);
749 		if (item == NULL)
750 			goto err;
751 
752 		pqueue_insert(D1I(s)->buffered_messages, item);
753 	}
754 
755 	return DTLS1_HM_FRAGMENT_RETRY;
756 
757 err:
758 	if (item == NULL && frag != NULL)
759 		dtls1_hm_fragment_free(frag);
760 	*ok = 0;
761 	return i;
762 }
763 
764 
765 static long
766 dtls1_get_message_fragment(SSL *s, int st1, int stn, long max, int *ok)
767 {
768 	unsigned char wire[DTLS1_HM_HEADER_LENGTH];
769 	unsigned long len, frag_off, frag_len;
770 	int i, al;
771 	struct hm_header_st msg_hdr;
772 
773 again:
774 	/* see if we have the required fragment already */
775 	if ((frag_len = dtls1_retrieve_buffered_fragment(s, max, ok)) || *ok) {
776 		if (*ok)
777 			s->internal->init_num = frag_len;
778 		return frag_len;
779 	}
780 
781 	/* read handshake message header */
782 	i = s->method->internal->ssl_read_bytes(s, SSL3_RT_HANDSHAKE, wire,
783 	    DTLS1_HM_HEADER_LENGTH, 0);
784 	if (i <= 0) 	/* nbio, or an error */
785 	{
786 		s->internal->rwstate = SSL_READING;
787 		*ok = 0;
788 		return i;
789 	}
790 	/* Handshake fails if message header is incomplete */
791 	if (i != DTLS1_HM_HEADER_LENGTH ||
792 	    /* parse the message fragment header */
793 	    dtls1_get_message_header(wire, &msg_hdr) == 0) {
794 		al = SSL_AD_UNEXPECTED_MESSAGE;
795 		SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
796 		goto f_err;
797 	}
798 
799 	/*
800 	 * if this is a future (or stale) message it gets buffered
801 	 * (or dropped)--no further processing at this time
802 	 * While listening, we accept seq 1 (ClientHello with cookie)
803 	 * although we're still expecting seq 0 (ClientHello)
804 	 */
805 	if (msg_hdr.seq != D1I(s)->handshake_read_seq &&
806 	    !(D1I(s)->listen && msg_hdr.seq == 1))
807 		return dtls1_process_out_of_seq_message(s, &msg_hdr, ok);
808 
809 	len = msg_hdr.msg_len;
810 	frag_off = msg_hdr.frag_off;
811 	frag_len = msg_hdr.frag_len;
812 
813 	if (frag_len && frag_len < len)
814 		return dtls1_reassemble_fragment(s, &msg_hdr, ok);
815 
816 	if (!s->server && D1I(s)->r_msg_hdr.frag_off == 0 &&
817 	    wire[0] == SSL3_MT_HELLO_REQUEST) {
818 		/*
819 		 * The server may always send 'Hello Request' messages --
820 		 * we are doing a handshake anyway now, so ignore them
821 		 * if their format is correct. Does not count for
822 		 * 'Finished' MAC.
823 		 */
824 		if (wire[1] == 0 && wire[2] == 0 && wire[3] == 0) {
825 			if (s->internal->msg_callback)
826 				s->internal->msg_callback(0, s->version,
827 				    SSL3_RT_HANDSHAKE, wire,
828 				    DTLS1_HM_HEADER_LENGTH, s,
829 				    s->internal->msg_callback_arg);
830 
831 			s->internal->init_num = 0;
832 			goto again;
833 		}
834 		else /* Incorrectly formated Hello request */
835 		{
836 			al = SSL_AD_UNEXPECTED_MESSAGE;
837 			SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
838 			goto f_err;
839 		}
840 	}
841 
842 	if ((al = dtls1_preprocess_fragment(s, &msg_hdr, max)))
843 		goto f_err;
844 
845 	/* XDTLS:  ressurect this when restart is in place */
846 	S3I(s)->hs.state = stn;
847 
848 	if (frag_len > 0) {
849 		unsigned char *p = (unsigned char *)s->internal->init_buf->data + DTLS1_HM_HEADER_LENGTH;
850 
851 		i = s->method->internal->ssl_read_bytes(s, SSL3_RT_HANDSHAKE,
852 		    &p[frag_off], frag_len, 0);
853 		/* XDTLS:  fix this--message fragments cannot span multiple packets */
854 		if (i <= 0) {
855 			s->internal->rwstate = SSL_READING;
856 			*ok = 0;
857 			return i;
858 		}
859 	} else
860 		i = 0;
861 
862 	/*
863 	 * XDTLS:  an incorrectly formatted fragment should cause the
864 	 * handshake to fail
865 	 */
866 	if (i != (int)frag_len) {
867 		al = SSL3_AD_ILLEGAL_PARAMETER;
868 		SSLerror(s, SSL3_AD_ILLEGAL_PARAMETER);
869 		goto f_err;
870 	}
871 
872 	*ok = 1;
873 
874 	/*
875 	 * Note that s->internal->init_num is *not* used as current offset in
876 	 * s->internal->init_buf->data, but as a counter summing up fragments'
877 	 * lengths: as soon as they sum up to handshake packet
878 	 * length, we assume we have got all the fragments.
879 	 */
880 	s->internal->init_num = frag_len;
881 	return frag_len;
882 
883 f_err:
884 	ssl3_send_alert(s, SSL3_AL_FATAL, al);
885 	s->internal->init_num = 0;
886 
887 	*ok = 0;
888 	return (-1);
889 }
890 
891 int
892 dtls1_read_failed(SSL *s, int code)
893 {
894 	if (code > 0) {
895 #ifdef DEBUG
896 		fprintf(stderr, "invalid state reached %s:%d",
897 		    __FILE__, __LINE__);
898 #endif
899 		return 1;
900 	}
901 
902 	if (!dtls1_is_timer_expired(s)) {
903 		/*
904 		 * not a timeout, none of our business, let higher layers
905 		 * handle this.  in fact it's probably an error
906 		 */
907 		return code;
908 	}
909 
910 	if (!SSL_in_init(s))  /* done, no need to send a retransmit */
911 	{
912 		BIO_set_flags(SSL_get_rbio(s), BIO_FLAGS_READ);
913 		return code;
914 	}
915 
916 	return dtls1_handle_timeout(s);
917 }
918 
919 int
920 dtls1_get_queue_priority(unsigned short seq, int is_ccs)
921 {
922 	/*
923 	 * The index of the retransmission queue actually is the message
924 	 * sequence number, since the queue only contains messages of a
925 	 * single handshake. However, the ChangeCipherSpec has no message
926 	 * sequence number and so using only the sequence will result in
927 	 * the CCS and Finished having the same index. To prevent this, the
928 	 * sequence number is multiplied by 2. In case of a CCS 1 is
929 	 * subtracted.  This does not only differ CSS and Finished, it also
930 	 * maintains the order of the index (important for priority queues)
931 	 * and fits in the unsigned short variable.
932 	 */
933 	return seq * 2 - is_ccs;
934 }
935 
936 int
937 dtls1_retransmit_buffered_messages(SSL *s)
938 {
939 	pqueue sent = s->d1->sent_messages;
940 	piterator iter;
941 	pitem *item;
942 	hm_fragment *frag;
943 	int found = 0;
944 
945 	iter = pqueue_iterator(sent);
946 
947 	for (item = pqueue_next(&iter); item != NULL;
948 	    item = pqueue_next(&iter)) {
949 		frag = (hm_fragment *)item->data;
950 		if (dtls1_retransmit_message(s,
951 		    (unsigned short)dtls1_get_queue_priority(
952 		    frag->msg_header.seq, frag->msg_header.is_ccs), 0,
953 		    &found) <= 0 && found) {
954 #ifdef DEBUG
955 			fprintf(stderr, "dtls1_retransmit_message() failed\n");
956 #endif
957 			return -1;
958 		}
959 	}
960 
961 	return 1;
962 }
963 
964 int
965 dtls1_buffer_message(SSL *s, int is_ccs)
966 {
967 	pitem *item;
968 	hm_fragment *frag;
969 	unsigned char seq64be[8];
970 
971 	/* Buffer the messsage in order to handle DTLS retransmissions. */
972 
973 	/*
974 	 * This function is called immediately after a message has
975 	 * been serialized
976 	 */
977 	OPENSSL_assert(s->internal->init_off == 0);
978 
979 	frag = dtls1_hm_fragment_new(s->internal->init_num, 0);
980 	if (frag == NULL)
981 		return 0;
982 
983 	memcpy(frag->fragment, s->internal->init_buf->data, s->internal->init_num);
984 
985 	if (is_ccs) {
986 		OPENSSL_assert(D1I(s)->w_msg_hdr.msg_len +
987 		    ((s->version == DTLS1_VERSION) ?
988 		    DTLS1_CCS_HEADER_LENGTH : 3) == (unsigned int)s->internal->init_num);
989 	} else {
990 		OPENSSL_assert(D1I(s)->w_msg_hdr.msg_len +
991 		    DTLS1_HM_HEADER_LENGTH == (unsigned int)s->internal->init_num);
992 	}
993 
994 	frag->msg_header.msg_len = D1I(s)->w_msg_hdr.msg_len;
995 	frag->msg_header.seq = D1I(s)->w_msg_hdr.seq;
996 	frag->msg_header.type = D1I(s)->w_msg_hdr.type;
997 	frag->msg_header.frag_off = 0;
998 	frag->msg_header.frag_len = D1I(s)->w_msg_hdr.msg_len;
999 	frag->msg_header.is_ccs = is_ccs;
1000 
1001 	/* save current state*/
1002 	frag->msg_header.saved_retransmit_state.enc_write_ctx = s->internal->enc_write_ctx;
1003 	frag->msg_header.saved_retransmit_state.write_hash = s->internal->write_hash;
1004 	frag->msg_header.saved_retransmit_state.session = s->session;
1005 	frag->msg_header.saved_retransmit_state.epoch = D1I(s)->w_epoch;
1006 
1007 	memset(seq64be, 0, sizeof(seq64be));
1008 	seq64be[6] = (unsigned char)(dtls1_get_queue_priority(
1009 	    frag->msg_header.seq, frag->msg_header.is_ccs) >> 8);
1010 	seq64be[7] = (unsigned char)(dtls1_get_queue_priority(
1011 	    frag->msg_header.seq, frag->msg_header.is_ccs));
1012 
1013 	item = pitem_new(seq64be, frag);
1014 	if (item == NULL) {
1015 		dtls1_hm_fragment_free(frag);
1016 		return 0;
1017 	}
1018 
1019 	pqueue_insert(s->d1->sent_messages, item);
1020 	return 1;
1021 }
1022 
1023 int
1024 dtls1_retransmit_message(SSL *s, unsigned short seq, unsigned long frag_off,
1025     int *found)
1026 {
1027 	int ret;
1028 	/* XDTLS: for now assuming that read/writes are blocking */
1029 	pitem *item;
1030 	hm_fragment *frag;
1031 	unsigned long header_length;
1032 	unsigned char seq64be[8];
1033 	struct dtls1_retransmit_state saved_state;
1034 	unsigned char save_write_sequence[8];
1035 
1036 	/*
1037 	  OPENSSL_assert(s->internal->init_num == 0);
1038 	  OPENSSL_assert(s->internal->init_off == 0);
1039 	 */
1040 
1041 	/* XDTLS:  the requested message ought to be found, otherwise error */
1042 	memset(seq64be, 0, sizeof(seq64be));
1043 	seq64be[6] = (unsigned char)(seq >> 8);
1044 	seq64be[7] = (unsigned char)seq;
1045 
1046 	item = pqueue_find(s->d1->sent_messages, seq64be);
1047 	if (item == NULL) {
1048 #ifdef DEBUG
1049 		fprintf(stderr, "retransmit:  message %d non-existent\n", seq);
1050 #endif
1051 		*found = 0;
1052 		return 0;
1053 	}
1054 
1055 	*found = 1;
1056 	frag = (hm_fragment *)item->data;
1057 
1058 	if (frag->msg_header.is_ccs)
1059 		header_length = DTLS1_CCS_HEADER_LENGTH;
1060 	else
1061 		header_length = DTLS1_HM_HEADER_LENGTH;
1062 
1063 	memcpy(s->internal->init_buf->data, frag->fragment,
1064 	    frag->msg_header.msg_len + header_length);
1065 	s->internal->init_num = frag->msg_header.msg_len + header_length;
1066 
1067 	dtls1_set_message_header_int(s, frag->msg_header.type,
1068 	    frag->msg_header.msg_len, frag->msg_header.seq, 0,
1069 	    frag->msg_header.frag_len);
1070 
1071 	/* save current state */
1072 	saved_state.enc_write_ctx = s->internal->enc_write_ctx;
1073 	saved_state.write_hash = s->internal->write_hash;
1074 	saved_state.session = s->session;
1075 	saved_state.epoch = D1I(s)->w_epoch;
1076 
1077 	D1I(s)->retransmitting = 1;
1078 
1079 	/* restore state in which the message was originally sent */
1080 	s->internal->enc_write_ctx = frag->msg_header.saved_retransmit_state.enc_write_ctx;
1081 	s->internal->write_hash = frag->msg_header.saved_retransmit_state.write_hash;
1082 	s->session = frag->msg_header.saved_retransmit_state.session;
1083 	D1I(s)->w_epoch = frag->msg_header.saved_retransmit_state.epoch;
1084 
1085 	if (frag->msg_header.saved_retransmit_state.epoch ==
1086 	    saved_state.epoch - 1) {
1087 		memcpy(save_write_sequence, S3I(s)->write_sequence,
1088 		    sizeof(S3I(s)->write_sequence));
1089 		memcpy(S3I(s)->write_sequence, D1I(s)->last_write_sequence,
1090 		    sizeof(S3I(s)->write_sequence));
1091 	}
1092 
1093 	ret = dtls1_do_write(s, frag->msg_header.is_ccs ?
1094 	    SSL3_RT_CHANGE_CIPHER_SPEC : SSL3_RT_HANDSHAKE);
1095 
1096 	/* restore current state */
1097 	s->internal->enc_write_ctx = saved_state.enc_write_ctx;
1098 	s->internal->write_hash = saved_state.write_hash;
1099 	s->session = saved_state.session;
1100 	D1I(s)->w_epoch = saved_state.epoch;
1101 
1102 	if (frag->msg_header.saved_retransmit_state.epoch ==
1103 	    saved_state.epoch - 1) {
1104 		memcpy(D1I(s)->last_write_sequence, S3I(s)->write_sequence,
1105 		    sizeof(S3I(s)->write_sequence));
1106 		memcpy(S3I(s)->write_sequence, save_write_sequence,
1107 		    sizeof(S3I(s)->write_sequence));
1108 	}
1109 
1110 	D1I(s)->retransmitting = 0;
1111 
1112 	(void)BIO_flush(SSL_get_wbio(s));
1113 	return ret;
1114 }
1115 
1116 /* call this function when the buffered messages are no longer needed */
1117 void
1118 dtls1_clear_record_buffer(SSL *s)
1119 {
1120 	pitem *item;
1121 
1122 	for(item = pqueue_pop(s->d1->sent_messages); item != NULL;
1123 	    item = pqueue_pop(s->d1->sent_messages)) {
1124 		dtls1_hm_fragment_free((hm_fragment *)item->data);
1125 		pitem_free(item);
1126 	}
1127 }
1128 
1129 void
1130 dtls1_set_message_header(SSL *s, unsigned char mt, unsigned long len,
1131     unsigned long frag_off, unsigned long frag_len)
1132 {
1133 	/* Don't change sequence numbers while listening */
1134 	if (frag_off == 0 && !D1I(s)->listen) {
1135 		D1I(s)->handshake_write_seq = D1I(s)->next_handshake_write_seq;
1136 		D1I(s)->next_handshake_write_seq++;
1137 	}
1138 
1139 	dtls1_set_message_header_int(s, mt, len, D1I(s)->handshake_write_seq,
1140 	    frag_off, frag_len);
1141 }
1142 
1143 /* don't actually do the writing, wait till the MTU has been retrieved */
1144 void
1145 dtls1_set_message_header_int(SSL *s, unsigned char mt, unsigned long len,
1146     unsigned short seq_num, unsigned long frag_off, unsigned long frag_len)
1147 {
1148 	struct hm_header_st *msg_hdr = &D1I(s)->w_msg_hdr;
1149 
1150 	msg_hdr->type = mt;
1151 	msg_hdr->msg_len = len;
1152 	msg_hdr->seq = seq_num;
1153 	msg_hdr->frag_off = frag_off;
1154 	msg_hdr->frag_len = frag_len;
1155 }
1156 
1157 static void
1158 dtls1_fix_message_header(SSL *s, unsigned long frag_off, unsigned long frag_len)
1159 {
1160 	struct hm_header_st *msg_hdr = &D1I(s)->w_msg_hdr;
1161 
1162 	msg_hdr->frag_off = frag_off;
1163 	msg_hdr->frag_len = frag_len;
1164 }
1165 
1166 static int
1167 dtls1_write_message_header(const struct hm_header_st *msg_hdr,
1168     unsigned long frag_off, unsigned long frag_len, unsigned char *p)
1169 {
1170 	CBB cbb;
1171 
1172 	/* We assume DTLS1_HM_HEADER_LENGTH bytes are available for now... */
1173 	if (!CBB_init_fixed(&cbb, p, DTLS1_HM_HEADER_LENGTH))
1174 		return 0;
1175 	if (!CBB_add_u8(&cbb, msg_hdr->type))
1176 		goto err;
1177 	if (!CBB_add_u24(&cbb, msg_hdr->msg_len))
1178 		goto err;
1179 	if (!CBB_add_u16(&cbb, msg_hdr->seq))
1180 		goto err;
1181 	if (!CBB_add_u24(&cbb, frag_off))
1182 		goto err;
1183 	if (!CBB_add_u24(&cbb, frag_len))
1184 		goto err;
1185 	if (!CBB_finish(&cbb, NULL, NULL))
1186 		goto err;
1187 
1188 	return 1;
1189 
1190  err:
1191 	CBB_cleanup(&cbb);
1192 	return 0;
1193 }
1194 
1195 unsigned int
1196 dtls1_min_mtu(void)
1197 {
1198 	return (g_probable_mtu[(sizeof(g_probable_mtu) /
1199 	    sizeof(g_probable_mtu[0])) - 1]);
1200 }
1201 
1202 static unsigned int
1203 dtls1_guess_mtu(unsigned int curr_mtu)
1204 {
1205 	unsigned int i;
1206 
1207 	if (curr_mtu == 0)
1208 		return g_probable_mtu[0];
1209 
1210 	for (i = 0; i < sizeof(g_probable_mtu) / sizeof(g_probable_mtu[0]); i++)
1211 		if (curr_mtu > g_probable_mtu[i])
1212 			return g_probable_mtu[i];
1213 
1214 	return curr_mtu;
1215 }
1216 
1217 int
1218 dtls1_get_message_header(unsigned char *data, struct hm_header_st *msg_hdr)
1219 {
1220 	CBS header;
1221 	uint32_t msg_len, frag_off, frag_len;
1222 	uint16_t seq;
1223 	uint8_t type;
1224 
1225 	CBS_init(&header, data, sizeof(*msg_hdr));
1226 
1227 	memset(msg_hdr, 0, sizeof(*msg_hdr));
1228 
1229 	if (!CBS_get_u8(&header, &type))
1230 		return 0;
1231 	if (!CBS_get_u24(&header, &msg_len))
1232 		return 0;
1233 	if (!CBS_get_u16(&header, &seq))
1234 		return 0;
1235 	if (!CBS_get_u24(&header, &frag_off))
1236 		return 0;
1237 	if (!CBS_get_u24(&header, &frag_len))
1238 		return 0;
1239 
1240 	msg_hdr->type = type;
1241 	msg_hdr->msg_len = msg_len;
1242 	msg_hdr->seq = seq;
1243 	msg_hdr->frag_off = frag_off;
1244 	msg_hdr->frag_len = frag_len;
1245 
1246 	return 1;
1247 }
1248 
1249 void
1250 dtls1_get_ccs_header(unsigned char *data, struct ccs_header_st *ccs_hdr)
1251 {
1252 	memset(ccs_hdr, 0x00, sizeof(struct ccs_header_st));
1253 
1254 	ccs_hdr->type = *(data++);
1255 }
1256