xref: /openbsd-src/lib/libssl/ssl_sess.c (revision 47911bd667ac77dc523b8a13ef40b012dbffa741)
1 /* ssl/ssl_sess.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3  * All rights reserved.
4  *
5  * This package is an SSL implementation written
6  * by Eric Young (eay@cryptsoft.com).
7  * The implementation was written so as to conform with Netscapes SSL.
8  *
9  * This library is free for commercial and non-commercial use as long as
10  * the following conditions are aheared to.  The following conditions
11  * apply to all code found in this distribution, be it the RC4, RSA,
12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
13  * included with this distribution is covered by the same copyright terms
14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15  *
16  * Copyright remains Eric Young's, and as such any Copyright notices in
17  * the code are not to be removed.
18  * If this package is used in a product, Eric Young should be given attribution
19  * as the author of the parts of the library used.
20  * This can be in the form of a textual message at program startup or
21  * in documentation (online or textual) provided with the package.
22  *
23  * Redistribution and use in source and binary forms, with or without
24  * modification, are permitted provided that the following conditions
25  * are met:
26  * 1. Redistributions of source code must retain the copyright
27  *    notice, this list of conditions and the following disclaimer.
28  * 2. Redistributions in binary form must reproduce the above copyright
29  *    notice, this list of conditions and the following disclaimer in the
30  *    documentation and/or other materials provided with the distribution.
31  * 3. All advertising materials mentioning features or use of this software
32  *    must display the following acknowledgement:
33  *    "This product includes cryptographic software written by
34  *     Eric Young (eay@cryptsoft.com)"
35  *    The word 'cryptographic' can be left out if the rouines from the library
36  *    being used are not cryptographic related :-).
37  * 4. If you include any Windows specific code (or a derivative thereof) from
38  *    the apps directory (application code) you must include an acknowledgement:
39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40  *
41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51  * SUCH DAMAGE.
52  *
53  * The licence and distribution terms for any publically available version or
54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
55  * copied and put under another distribution licence
56  * [including the GNU Public Licence.]
57  */
58 
59 #include <stdio.h>
60 #include <openssl/lhash.h>
61 #include <openssl/rand.h>
62 #include "ssl_locl.h"
63 
64 static void SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s);
65 static void SSL_SESSION_list_add(SSL_CTX *ctx,SSL_SESSION *s);
66 static int remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck);
67 
68 SSL_SESSION *SSL_get_session(SSL *ssl)
69 /* aka SSL_get0_session; gets 0 objects, just returns a copy of the pointer */
70 	{
71 	return(ssl->session);
72 	}
73 
74 SSL_SESSION *SSL_get1_session(SSL *ssl)
75 /* variant of SSL_get_session: caller really gets something */
76 	{
77 	SSL_SESSION *sess;
78 	/* Need to lock this all up rather than just use CRYPTO_add so that
79 	 * somebody doesn't free ssl->session between when we check it's
80 	 * non-null and when we up the reference count. */
81 	CRYPTO_r_lock(CRYPTO_LOCK_SSL_SESSION);
82 	sess = ssl->session;
83 	if(sess)
84 		sess->references++;
85 	CRYPTO_r_unlock(CRYPTO_LOCK_SSL_SESSION);
86 	return(sess);
87 	}
88 
89 int SSL_SESSION_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func,
90 	     CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func)
91 	{
92 	return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_SSL_SESSION, argl, argp,
93 			new_func, dup_func, free_func);
94 	}
95 
96 int SSL_SESSION_set_ex_data(SSL_SESSION *s, int idx, void *arg)
97 	{
98 	return(CRYPTO_set_ex_data(&s->ex_data,idx,arg));
99 	}
100 
101 void *SSL_SESSION_get_ex_data(SSL_SESSION *s, int idx)
102 	{
103 	return(CRYPTO_get_ex_data(&s->ex_data,idx));
104 	}
105 
106 SSL_SESSION *SSL_SESSION_new(void)
107 	{
108 	SSL_SESSION *ss;
109 
110 	ss=(SSL_SESSION *)OPENSSL_malloc(sizeof(SSL_SESSION));
111 	if (ss == NULL)
112 		{
113 		SSLerr(SSL_F_SSL_SESSION_NEW,ERR_R_MALLOC_FAILURE);
114 		return(0);
115 		}
116 	memset(ss,0,sizeof(SSL_SESSION));
117 
118 	ss->verify_result = 1; /* avoid 0 (= X509_V_OK) just in case */
119 	ss->references=1;
120 	ss->timeout=60*5+4; /* 5 minute timeout by default */
121 	ss->time=time(NULL);
122 	ss->prev=NULL;
123 	ss->next=NULL;
124 	ss->compress_meth=0;
125 	CRYPTO_new_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->ex_data);
126 	return(ss);
127 	}
128 
129 /* Even with SSLv2, we have 16 bytes (128 bits) of session ID space. SSLv3/TLSv1
130  * has 32 bytes (256 bits). As such, filling the ID with random gunk repeatedly
131  * until we have no conflict is going to complete in one iteration pretty much
132  * "most" of the time (btw: understatement). So, if it takes us 10 iterations
133  * and we still can't avoid a conflict - well that's a reasonable point to call
134  * it quits. Either the RAND code is broken or someone is trying to open roughly
135  * very close to 2^128 (or 2^256) SSL sessions to our server. How you might
136  * store that many sessions is perhaps a more interesting question ... */
137 
138 #define MAX_SESS_ID_ATTEMPTS 10
139 static int def_generate_session_id(const SSL *ssl, unsigned char *id,
140 				unsigned int *id_len)
141 {
142 	unsigned int retry = 0;
143 	do
144 		RAND_pseudo_bytes(id, *id_len);
145 	while(SSL_has_matching_session_id(ssl, id, *id_len) &&
146 		(++retry < MAX_SESS_ID_ATTEMPTS));
147 	if(retry < MAX_SESS_ID_ATTEMPTS)
148 		return 1;
149 	/* else - woops a session_id match */
150 	/* XXX We should also check the external cache --
151 	 * but the probability of a collision is negligible, and
152 	 * we could not prevent the concurrent creation of sessions
153 	 * with identical IDs since we currently don't have means
154 	 * to atomically check whether a session ID already exists
155 	 * and make a reservation for it if it does not
156 	 * (this problem applies to the internal cache as well).
157 	 */
158 	return 0;
159 }
160 
161 int ssl_get_new_session(SSL *s, int session)
162 	{
163 	/* This gets used by clients and servers. */
164 
165 	unsigned int tmp;
166 	SSL_SESSION *ss=NULL;
167 	GEN_SESSION_CB cb = def_generate_session_id;
168 
169 	if ((ss=SSL_SESSION_new()) == NULL) return(0);
170 
171 	/* If the context has a default timeout, use it */
172 	if (s->ctx->session_timeout == 0)
173 		ss->timeout=SSL_get_default_timeout(s);
174 	else
175 		ss->timeout=s->ctx->session_timeout;
176 
177 	if (s->session != NULL)
178 		{
179 		SSL_SESSION_free(s->session);
180 		s->session=NULL;
181 		}
182 
183 	if (session)
184 		{
185 		if (s->version == SSL2_VERSION)
186 			{
187 			ss->ssl_version=SSL2_VERSION;
188 			ss->session_id_length=SSL2_SSL_SESSION_ID_LENGTH;
189 			}
190 		else if (s->version == SSL3_VERSION)
191 			{
192 			ss->ssl_version=SSL3_VERSION;
193 			ss->session_id_length=SSL3_SSL_SESSION_ID_LENGTH;
194 			}
195 		else if (s->version == TLS1_VERSION)
196 			{
197 			ss->ssl_version=TLS1_VERSION;
198 			ss->session_id_length=SSL3_SSL_SESSION_ID_LENGTH;
199 			}
200 		else
201 			{
202 			SSLerr(SSL_F_SSL_GET_NEW_SESSION,SSL_R_UNSUPPORTED_SSL_VERSION);
203 			SSL_SESSION_free(ss);
204 			return(0);
205 			}
206 		/* Choose which callback will set the session ID */
207 		CRYPTO_r_lock(CRYPTO_LOCK_SSL_CTX);
208 		if(s->generate_session_id)
209 			cb = s->generate_session_id;
210 		else if(s->ctx->generate_session_id)
211 			cb = s->ctx->generate_session_id;
212 		CRYPTO_r_unlock(CRYPTO_LOCK_SSL_CTX);
213 		/* Choose a session ID */
214 		tmp = ss->session_id_length;
215 		if(!cb(s, ss->session_id, &tmp))
216 			{
217 			/* The callback failed */
218 			SSLerr(SSL_F_SSL_GET_NEW_SESSION,
219 				SSL_R_SSL_SESSION_ID_CALLBACK_FAILED);
220 			SSL_SESSION_free(ss);
221 			return(0);
222 			}
223 		/* Don't allow the callback to set the session length to zero.
224 		 * nor set it higher than it was. */
225 		if(!tmp || (tmp > ss->session_id_length))
226 			{
227 			/* The callback set an illegal length */
228 			SSLerr(SSL_F_SSL_GET_NEW_SESSION,
229 				SSL_R_SSL_SESSION_ID_HAS_BAD_LENGTH);
230 			SSL_SESSION_free(ss);
231 			return(0);
232 			}
233 		/* If the session length was shrunk and we're SSLv2, pad it */
234 		if((tmp < ss->session_id_length) && (s->version == SSL2_VERSION))
235 			memset(ss->session_id + tmp, 0, ss->session_id_length - tmp);
236 		else
237 			ss->session_id_length = tmp;
238 		/* Finally, check for a conflict */
239 		if(SSL_has_matching_session_id(s, ss->session_id,
240 						ss->session_id_length))
241 			{
242 			SSLerr(SSL_F_SSL_GET_NEW_SESSION,
243 				SSL_R_SSL_SESSION_ID_CONFLICT);
244 			SSL_SESSION_free(ss);
245 			return(0);
246 			}
247 		}
248 	else
249 		{
250 		ss->session_id_length=0;
251 		}
252 
253 	if (s->sid_ctx_length > sizeof ss->sid_ctx)
254 		{
255 		SSLerr(SSL_F_SSL_GET_NEW_SESSION, ERR_R_INTERNAL_ERROR);
256 		SSL_SESSION_free(ss);
257 		return 0;
258 		}
259 	memcpy(ss->sid_ctx,s->sid_ctx,s->sid_ctx_length);
260 	ss->sid_ctx_length=s->sid_ctx_length;
261 	s->session=ss;
262 	ss->ssl_version=s->version;
263 	ss->verify_result = X509_V_OK;
264 
265 	return(1);
266 	}
267 
268 int ssl_get_prev_session(SSL *s, unsigned char *session_id, int len)
269 	{
270 	/* This is used only by servers. */
271 
272 	SSL_SESSION *ret=NULL,data;
273 	int fatal = 0;
274 
275 	data.ssl_version=s->version;
276 	data.session_id_length=len;
277 	if (len > SSL_MAX_SSL_SESSION_ID_LENGTH)
278 		goto err;
279 	memcpy(data.session_id,session_id,len);
280 
281 	if (!(s->ctx->session_cache_mode & SSL_SESS_CACHE_NO_INTERNAL_LOOKUP))
282 		{
283 		CRYPTO_r_lock(CRYPTO_LOCK_SSL_CTX);
284 		ret=(SSL_SESSION *)lh_retrieve(s->ctx->sessions,&data);
285 		if (ret != NULL)
286 		    /* don't allow other threads to steal it: */
287 		    CRYPTO_add(&ret->references,1,CRYPTO_LOCK_SSL_SESSION);
288 		CRYPTO_r_unlock(CRYPTO_LOCK_SSL_CTX);
289 		}
290 
291 	if (ret == NULL)
292 		{
293 		int copy=1;
294 
295 		s->ctx->stats.sess_miss++;
296 		ret=NULL;
297 		if (s->ctx->get_session_cb != NULL
298 		    && (ret=s->ctx->get_session_cb(s,session_id,len,&copy))
299 		       != NULL)
300 			{
301 			s->ctx->stats.sess_cb_hit++;
302 
303 			/* Increment reference count now if the session callback
304 			 * asks us to do so (note that if the session structures
305 			 * returned by the callback are shared between threads,
306 			 * it must handle the reference count itself [i.e. copy == 0],
307 			 * or things won't be thread-safe). */
308 			if (copy)
309 				CRYPTO_add(&ret->references,1,CRYPTO_LOCK_SSL_SESSION);
310 
311 			/* The following should not return 1, otherwise,
312 			 * things are very strange */
313 			SSL_CTX_add_session(s->ctx,ret);
314 			}
315 		if (ret == NULL)
316 			goto err;
317 		}
318 
319 	/* Now ret is non-NULL, and we own one of its reference counts. */
320 
321 	if((s->verify_mode&SSL_VERIFY_PEER)
322 	   && (!s->sid_ctx_length || ret->sid_ctx_length != s->sid_ctx_length
323 	       || memcmp(ret->sid_ctx,s->sid_ctx,ret->sid_ctx_length)))
324 	    {
325 		/* We've found the session named by the client, but we don't
326 		 * want to use it in this context. */
327 
328 		if (s->sid_ctx_length == 0)
329 			{
330 			/* application should have used SSL[_CTX]_set_session_id_context
331 			 * -- we could tolerate this and just pretend we never heard
332 			 * of this session, but then applications could effectively
333 			 * disable the session cache by accident without anyone noticing */
334 
335 			SSLerr(SSL_F_SSL_GET_PREV_SESSION,SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);
336 			fatal = 1;
337 			goto err;
338 			}
339 		else
340 			{
341 #if 0 /* The client cannot always know when a session is not appropriate,
342 	   * so we shouldn't generate an error message. */
343 
344 			SSLerr(SSL_F_SSL_GET_PREV_SESSION,SSL_R_ATTEMPT_TO_REUSE_SESSION_IN_DIFFERENT_CONTEXT);
345 #endif
346 			goto err; /* treat like cache miss */
347 			}
348 		}
349 
350 	if (ret->cipher == NULL)
351 		{
352 		unsigned char buf[5],*p;
353 		unsigned long l;
354 
355 		p=buf;
356 		l=ret->cipher_id;
357 		l2n(l,p);
358 		if ((ret->ssl_version>>8) == SSL3_VERSION_MAJOR)
359 			ret->cipher=ssl_get_cipher_by_char(s,&(buf[2]));
360 		else
361 			ret->cipher=ssl_get_cipher_by_char(s,&(buf[1]));
362 		if (ret->cipher == NULL)
363 			goto err;
364 		}
365 
366 
367 #if 0 /* This is way too late. */
368 
369 	/* If a thread got the session, then 'swaped', and another got
370 	 * it and then due to a time-out decided to 'OPENSSL_free' it we could
371 	 * be in trouble.  So I'll increment it now, then double decrement
372 	 * later - am I speaking rubbish?. */
373 	CRYPTO_add(&ret->references,1,CRYPTO_LOCK_SSL_SESSION);
374 #endif
375 
376 	if ((long)(ret->time+ret->timeout) < (long)time(NULL)) /* timeout */
377 		{
378 		s->ctx->stats.sess_timeout++;
379 		/* remove it from the cache */
380 		SSL_CTX_remove_session(s->ctx,ret);
381 		goto err;
382 		}
383 
384 	s->ctx->stats.sess_hit++;
385 
386 	/* ret->time=time(NULL); */ /* rezero timeout? */
387 	/* again, just leave the session
388 	 * if it is the same session, we have just incremented and
389 	 * then decremented the reference count :-) */
390 	if (s->session != NULL)
391 		SSL_SESSION_free(s->session);
392 	s->session=ret;
393 	s->verify_result = s->session->verify_result;
394 	return(1);
395 
396  err:
397 	if (ret != NULL)
398 		SSL_SESSION_free(ret);
399 	if (fatal)
400 		return -1;
401 	else
402 		return 0;
403 	}
404 
405 int SSL_CTX_add_session(SSL_CTX *ctx, SSL_SESSION *c)
406 	{
407 	int ret=0;
408 	SSL_SESSION *s;
409 
410 	/* add just 1 reference count for the SSL_CTX's session cache
411 	 * even though it has two ways of access: each session is in a
412 	 * doubly linked list and an lhash */
413 	CRYPTO_add(&c->references,1,CRYPTO_LOCK_SSL_SESSION);
414 	/* if session c is in already in cache, we take back the increment later */
415 
416 	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
417 	s=(SSL_SESSION *)lh_insert(ctx->sessions,c);
418 
419 	/* s != NULL iff we already had a session with the given PID.
420 	 * In this case, s == c should hold (then we did not really modify
421 	 * ctx->sessions), or we're in trouble. */
422 	if (s != NULL && s != c)
423 		{
424 		/* We *are* in trouble ... */
425 		SSL_SESSION_list_remove(ctx,s);
426 		SSL_SESSION_free(s);
427 		/* ... so pretend the other session did not exist in cache
428 		 * (we cannot handle two SSL_SESSION structures with identical
429 		 * session ID in the same cache, which could happen e.g. when
430 		 * two threads concurrently obtain the same session from an external
431 		 * cache) */
432 		s = NULL;
433 		}
434 
435  	/* Put at the head of the queue unless it is already in the cache */
436 	if (s == NULL)
437 		SSL_SESSION_list_add(ctx,c);
438 
439 	if (s != NULL)
440 		{
441 		/* existing cache entry -- decrement previously incremented reference
442 		 * count because it already takes into account the cache */
443 
444 		SSL_SESSION_free(s); /* s == c */
445 		ret=0;
446 		}
447 	else
448 		{
449 		/* new cache entry -- remove old ones if cache has become too large */
450 
451 		ret=1;
452 
453 		if (SSL_CTX_sess_get_cache_size(ctx) > 0)
454 			{
455 			while (SSL_CTX_sess_number(ctx) >
456 				SSL_CTX_sess_get_cache_size(ctx))
457 				{
458 				if (!remove_session_lock(ctx,
459 					ctx->session_cache_tail, 0))
460 					break;
461 				else
462 					ctx->stats.sess_cache_full++;
463 				}
464 			}
465 		}
466 	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
467 	return(ret);
468 	}
469 
470 int SSL_CTX_remove_session(SSL_CTX *ctx, SSL_SESSION *c)
471 {
472 	return remove_session_lock(ctx, c, 1);
473 }
474 
475 static int remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck)
476 	{
477 	SSL_SESSION *r;
478 	int ret=0;
479 
480 	if ((c != NULL) && (c->session_id_length != 0))
481 		{
482 		if(lck) CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
483 		if ((r = (SSL_SESSION *)lh_retrieve(ctx->sessions,c)) == c)
484 			{
485 			ret=1;
486 			r=(SSL_SESSION *)lh_delete(ctx->sessions,c);
487 			SSL_SESSION_list_remove(ctx,c);
488 			}
489 
490 		if(lck) CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
491 
492 		if (ret)
493 			{
494 			r->not_resumable=1;
495 			if (ctx->remove_session_cb != NULL)
496 				ctx->remove_session_cb(ctx,r);
497 			SSL_SESSION_free(r);
498 			}
499 		}
500 	else
501 		ret=0;
502 	return(ret);
503 	}
504 
505 void SSL_SESSION_free(SSL_SESSION *ss)
506 	{
507 	int i;
508 
509 	if(ss == NULL)
510 	    return;
511 
512 	i=CRYPTO_add(&ss->references,-1,CRYPTO_LOCK_SSL_SESSION);
513 #ifdef REF_PRINT
514 	REF_PRINT("SSL_SESSION",ss);
515 #endif
516 	if (i > 0) return;
517 #ifdef REF_CHECK
518 	if (i < 0)
519 		{
520 		fprintf(stderr,"SSL_SESSION_free, bad reference count\n");
521 		abort(); /* ok */
522 		}
523 #endif
524 
525 	CRYPTO_free_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->ex_data);
526 
527 	memset(ss->key_arg,0,SSL_MAX_KEY_ARG_LENGTH);
528 	memset(ss->master_key,0,SSL_MAX_MASTER_KEY_LENGTH);
529 	memset(ss->session_id,0,SSL_MAX_SSL_SESSION_ID_LENGTH);
530 	if (ss->sess_cert != NULL) ssl_sess_cert_free(ss->sess_cert);
531 	if (ss->peer != NULL) X509_free(ss->peer);
532 	if (ss->ciphers != NULL) sk_SSL_CIPHER_free(ss->ciphers);
533 	memset(ss,0,sizeof(*ss));
534 	OPENSSL_free(ss);
535 	}
536 
537 int SSL_set_session(SSL *s, SSL_SESSION *session)
538 	{
539 	int ret=0;
540 	SSL_METHOD *meth;
541 
542 	if (session != NULL)
543 		{
544 		meth=s->ctx->method->get_ssl_method(session->ssl_version);
545 		if (meth == NULL)
546 			meth=s->method->get_ssl_method(session->ssl_version);
547 		if (meth == NULL)
548 			{
549 			SSLerr(SSL_F_SSL_SET_SESSION,SSL_R_UNABLE_TO_FIND_SSL_METHOD);
550 			return(0);
551 			}
552 
553 		if (meth != s->method)
554 			{
555 			if (!SSL_set_ssl_method(s,meth))
556 				return(0);
557 			if (s->ctx->session_timeout == 0)
558 				session->timeout=SSL_get_default_timeout(s);
559 			else
560 				session->timeout=s->ctx->session_timeout;
561 			}
562 
563 #ifndef OPENSSL_NO_KRB5
564                 if (s->kssl_ctx && !s->kssl_ctx->client_princ &&
565                     session->krb5_client_princ_len > 0)
566                 {
567                     s->kssl_ctx->client_princ = (char *)malloc(session->krb5_client_princ_len + 1);
568                     memcpy(s->kssl_ctx->client_princ,session->krb5_client_princ,
569                             session->krb5_client_princ_len);
570                     s->kssl_ctx->client_princ[session->krb5_client_princ_len] = '\0';
571                 }
572 #endif /* OPENSSL_NO_KRB5 */
573 
574 		/* CRYPTO_w_lock(CRYPTO_LOCK_SSL);*/
575 		CRYPTO_add(&session->references,1,CRYPTO_LOCK_SSL_SESSION);
576 		if (s->session != NULL)
577 			SSL_SESSION_free(s->session);
578 		s->session=session;
579 		s->verify_result = s->session->verify_result;
580 		/* CRYPTO_w_unlock(CRYPTO_LOCK_SSL);*/
581 		ret=1;
582 		}
583 	else
584 		{
585 		if (s->session != NULL)
586 			{
587 			SSL_SESSION_free(s->session);
588 			s->session=NULL;
589 			}
590 
591 		meth=s->ctx->method;
592 		if (meth != s->method)
593 			{
594 			if (!SSL_set_ssl_method(s,meth))
595 				return(0);
596 			}
597 		ret=1;
598 		}
599 	return(ret);
600 	}
601 
602 long SSL_SESSION_set_timeout(SSL_SESSION *s, long t)
603 	{
604 	if (s == NULL) return(0);
605 	s->timeout=t;
606 	return(1);
607 	}
608 
609 long SSL_SESSION_get_timeout(SSL_SESSION *s)
610 	{
611 	if (s == NULL) return(0);
612 	return(s->timeout);
613 	}
614 
615 long SSL_SESSION_get_time(SSL_SESSION *s)
616 	{
617 	if (s == NULL) return(0);
618 	return(s->time);
619 	}
620 
621 long SSL_SESSION_set_time(SSL_SESSION *s, long t)
622 	{
623 	if (s == NULL) return(0);
624 	s->time=t;
625 	return(t);
626 	}
627 
628 long SSL_CTX_set_timeout(SSL_CTX *s, long t)
629 	{
630 	long l;
631 	if (s == NULL) return(0);
632 	l=s->session_timeout;
633 	s->session_timeout=t;
634 	return(l);
635 	}
636 
637 long SSL_CTX_get_timeout(SSL_CTX *s)
638 	{
639 	if (s == NULL) return(0);
640 	return(s->session_timeout);
641 	}
642 
643 typedef struct timeout_param_st
644 	{
645 	SSL_CTX *ctx;
646 	long time;
647 	LHASH *cache;
648 	} TIMEOUT_PARAM;
649 
650 static void timeout(SSL_SESSION *s, TIMEOUT_PARAM *p)
651 	{
652 	if ((p->time == 0) || (p->time > (s->time+s->timeout))) /* timeout */
653 		{
654 		/* The reason we don't call SSL_CTX_remove_session() is to
655 		 * save on locking overhead */
656 		lh_delete(p->cache,s);
657 		SSL_SESSION_list_remove(p->ctx,s);
658 		s->not_resumable=1;
659 		if (p->ctx->remove_session_cb != NULL)
660 			p->ctx->remove_session_cb(p->ctx,s);
661 		SSL_SESSION_free(s);
662 		}
663 	}
664 
665 static IMPLEMENT_LHASH_DOALL_ARG_FN(timeout, SSL_SESSION *, TIMEOUT_PARAM *)
666 
667 void SSL_CTX_flush_sessions(SSL_CTX *s, long t)
668 	{
669 	unsigned long i;
670 	TIMEOUT_PARAM tp;
671 
672 	tp.ctx=s;
673 	tp.cache=s->sessions;
674 	if (tp.cache == NULL) return;
675 	tp.time=t;
676 	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
677 	i=tp.cache->down_load;
678 	tp.cache->down_load=0;
679 	lh_doall_arg(tp.cache, LHASH_DOALL_ARG_FN(timeout), &tp);
680 	tp.cache->down_load=i;
681 	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
682 	}
683 
684 int ssl_clear_bad_session(SSL *s)
685 	{
686 	if (	(s->session != NULL) &&
687 		!(s->shutdown & SSL_SENT_SHUTDOWN) &&
688 		!(SSL_in_init(s) || SSL_in_before(s)))
689 		{
690 		SSL_CTX_remove_session(s->ctx,s->session);
691 		return(1);
692 		}
693 	else
694 		return(0);
695 	}
696 
697 /* locked by SSL_CTX in the calling function */
698 static void SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s)
699 	{
700 	if ((s->next == NULL) || (s->prev == NULL)) return;
701 
702 	if (s->next == (SSL_SESSION *)&(ctx->session_cache_tail))
703 		{ /* last element in list */
704 		if (s->prev == (SSL_SESSION *)&(ctx->session_cache_head))
705 			{ /* only one element in list */
706 			ctx->session_cache_head=NULL;
707 			ctx->session_cache_tail=NULL;
708 			}
709 		else
710 			{
711 			ctx->session_cache_tail=s->prev;
712 			s->prev->next=(SSL_SESSION *)&(ctx->session_cache_tail);
713 			}
714 		}
715 	else
716 		{
717 		if (s->prev == (SSL_SESSION *)&(ctx->session_cache_head))
718 			{ /* first element in list */
719 			ctx->session_cache_head=s->next;
720 			s->next->prev=(SSL_SESSION *)&(ctx->session_cache_head);
721 			}
722 		else
723 			{ /* middle of list */
724 			s->next->prev=s->prev;
725 			s->prev->next=s->next;
726 			}
727 		}
728 	s->prev=s->next=NULL;
729 	}
730 
731 static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s)
732 	{
733 	if ((s->next != NULL) && (s->prev != NULL))
734 		SSL_SESSION_list_remove(ctx,s);
735 
736 	if (ctx->session_cache_head == NULL)
737 		{
738 		ctx->session_cache_head=s;
739 		ctx->session_cache_tail=s;
740 		s->prev=(SSL_SESSION *)&(ctx->session_cache_head);
741 		s->next=(SSL_SESSION *)&(ctx->session_cache_tail);
742 		}
743 	else
744 		{
745 		s->next=ctx->session_cache_head;
746 		s->next->prev=s;
747 		s->prev=(SSL_SESSION *)&(ctx->session_cache_head);
748 		ctx->session_cache_head=s;
749 		}
750 	}
751 
752