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IABSD.fr/src/lib/libssl/ssl_sess.c

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  • Author : jsing
    Date : 2019-04-22 15:12:20
    Hash : 8890443a
    Message : Pass the session ID down to the session/ticket handling code as a CBS. Convert ssl_get_prev_session(), tls1_process_ticket() and tls1_decrypt_ticket() to handle the session ID from the client hello as a CBS. While here also swap the order of arguments for tls1_decrypt_ticket() so that it is consistent with the other functions. ok tb@

  • lib/libssl/ssl_sess.c
  • /* $OpenBSD: ssl_sess.c,v 1.85 2019/04/22 15:12:20 jsing Exp $ */
    /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
     * All rights reserved.
     *
     * This package is an SSL implementation written
     * by Eric Young (eay@cryptsoft.com).
     * The implementation was written so as to conform with Netscapes SSL.
     *
     * This library is free for commercial and non-commercial use as long as
     * the following conditions are aheared to.  The following conditions
     * apply to all code found in this distribution, be it the RC4, RSA,
     * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
     * included with this distribution is covered by the same copyright terms
     * except that the holder is Tim Hudson (tjh@cryptsoft.com).
     *
     * Copyright remains Eric Young's, and as such any Copyright notices in
     * the code are not to be removed.
     * If this package is used in a product, Eric Young should be given attribution
     * as the author of the parts of the library used.
     * This can be in the form of a textual message at program startup or
     * in documentation (online or textual) provided with the package.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *    "This product includes cryptographic software written by
     *     Eric Young (eay@cryptsoft.com)"
     *    The word 'cryptographic' can be left out if the rouines from the library
     *    being used are not cryptographic related :-).
     * 4. If you include any Windows specific code (or a derivative thereof) from
     *    the apps directory (application code) you must include an acknowledgement:
     *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
     *
     * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * The licence and distribution terms for any publically available version or
     * derivative of this code cannot be changed.  i.e. this code cannot simply be
     * copied and put under another distribution licence
     * [including the GNU Public Licence.]
     */
    /* ====================================================================
     * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     *
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     *
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in
     *    the documentation and/or other materials provided with the
     *    distribution.
     *
     * 3. All advertising materials mentioning features or use of this
     *    software must display the following acknowledgment:
     *    "This product includes software developed by the OpenSSL Project
     *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
     *
     * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
     *    endorse or promote products derived from this software without
     *    prior written permission. For written permission, please contact
     *    openssl-core@openssl.org.
     *
     * 5. Products derived from this software may not be called "OpenSSL"
     *    nor may "OpenSSL" appear in their names without prior written
     *    permission of the OpenSSL Project.
     *
     * 6. Redistributions of any form whatsoever must retain the following
     *    acknowledgment:
     *    "This product includes software developed by the OpenSSL Project
     *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
     *
     * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
     * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
     * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
     * OF THE POSSIBILITY OF SUCH DAMAGE.
     * ====================================================================
     *
     * This product includes cryptographic software written by Eric Young
     * (eay@cryptsoft.com).  This product includes software written by Tim
     * Hudson (tjh@cryptsoft.com).
     *
     */
    /* ====================================================================
     * Copyright 2005 Nokia. All rights reserved.
     *
     * The portions of the attached software ("Contribution") is developed by
     * Nokia Corporation and is licensed pursuant to the OpenSSL open source
     * license.
     *
     * The Contribution, originally written by Mika Kousa and Pasi Eronen of
     * Nokia Corporation, consists of the "PSK" (Pre-Shared Key) ciphersuites
     * support (see RFC 4279) to OpenSSL.
     *
     * No patent licenses or other rights except those expressly stated in
     * the OpenSSL open source license shall be deemed granted or received
     * expressly, by implication, estoppel, or otherwise.
     *
     * No assurances are provided by Nokia that the Contribution does not
     * infringe the patent or other intellectual property rights of any third
     * party or that the license provides you with all the necessary rights
     * to make use of the Contribution.
     *
     * THE SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. IN
     * ADDITION TO THE DISCLAIMERS INCLUDED IN THE LICENSE, NOKIA
     * SPECIFICALLY DISCLAIMS ANY LIABILITY FOR CLAIMS BROUGHT BY YOU OR ANY
     * OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OR
     * OTHERWISE.
     */
    
    #include <openssl/lhash.h>
    
    #ifndef OPENSSL_NO_ENGINE
    #include <openssl/engine.h>
    #endif
    
    #include "ssl_locl.h"
    
    static void SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s);
    static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s);
    static int remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck);
    
    /* aka SSL_get0_session; gets 0 objects, just returns a copy of the pointer */
    SSL_SESSION *
    SSL_get_session(const SSL *ssl)
    {
    	return (ssl->session);
    }
    
    /* variant of SSL_get_session: caller really gets something */
    SSL_SESSION *
    SSL_get1_session(SSL *ssl)
    {
    	SSL_SESSION *sess;
    
    	/*
    	 * Need to lock this all up rather than just use CRYPTO_add so that
    	 * somebody doesn't free ssl->session between when we check it's
    	 * non-null and when we up the reference count.
    	 */
    	CRYPTO_w_lock(CRYPTO_LOCK_SSL_SESSION);
    	sess = ssl->session;
    	if (sess)
    		sess->references++;
    	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_SESSION);
    
    	return (sess);
    }
    
    int
    SSL_SESSION_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func,
        CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func)
    {
    	return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_SSL_SESSION,
    	    argl, argp, new_func, dup_func, free_func);
    }
    
    int
    SSL_SESSION_set_ex_data(SSL_SESSION *s, int idx, void *arg)
    {
    	return (CRYPTO_set_ex_data(&s->internal->ex_data, idx, arg));
    }
    
    void *
    SSL_SESSION_get_ex_data(const SSL_SESSION *s, int idx)
    {
    	return (CRYPTO_get_ex_data(&s->internal->ex_data, idx));
    }
    
    SSL_SESSION *
    SSL_SESSION_new(void)
    {
    	SSL_SESSION *ss;
    
    	if (!OPENSSL_init_ssl(0, NULL)) {
    		SSLerrorx(SSL_R_LIBRARY_BUG);
    		return(NULL);
    	}
    
    	if ((ss = calloc(1, sizeof(*ss))) == NULL) {
    		SSLerrorx(ERR_R_MALLOC_FAILURE);
    		return (NULL);
    	}
    	if ((ss->internal = calloc(1, sizeof(*ss->internal))) == NULL) {
    		free(ss);
    		SSLerrorx(ERR_R_MALLOC_FAILURE);
    		return (NULL);
    	}
    
    	ss->verify_result = 1; /* avoid 0 (= X509_V_OK) just in case */
    	ss->references = 1;
    	ss->timeout=60*5+4; /* 5 minute timeout by default */
    	ss->time = time(NULL);
    	ss->internal->prev = NULL;
    	ss->internal->next = NULL;
    	ss->tlsext_hostname = NULL;
    
    	ss->internal->tlsext_ecpointformatlist_length = 0;
    	ss->internal->tlsext_ecpointformatlist = NULL;
    	ss->internal->tlsext_supportedgroups_length = 0;
    	ss->internal->tlsext_supportedgroups = NULL;
    
    	CRYPTO_new_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->internal->ex_data);
    
    	return (ss);
    }
    
    const unsigned char *
    SSL_SESSION_get_id(const SSL_SESSION *ss, unsigned int *len)
    {
    	if (len != NULL)
    		*len = ss->session_id_length;
    	return ss->session_id;
    }
    
    const unsigned char *
    SSL_SESSION_get0_id_context(const SSL_SESSION *ss, unsigned int *len)
    {
    	if (len != NULL)
    		*len = (unsigned int)ss->sid_ctx_length;
    	return ss->sid_ctx;
    }
    
    unsigned int
    SSL_SESSION_get_compress_id(const SSL_SESSION *ss)
    {
    	return 0;
    }
    
    unsigned long
    SSL_SESSION_get_ticket_lifetime_hint(const SSL_SESSION *s)
    {
    	return s->tlsext_tick_lifetime_hint;
    }
    
    int
    SSL_SESSION_has_ticket(const SSL_SESSION *s)
    {
    	return (s->tlsext_ticklen > 0) ? 1 : 0;
    }
    
    /*
     * SSLv3/TLSv1 has 32 bytes (256 bits) of session ID space. As such, filling
     * the ID with random gunk repeatedly until we have no conflict is going to
     * complete in one iteration pretty much "most" of the time (btw:
     * understatement). So, if it takes us 10 iterations and we still can't avoid
     * a conflict - well that's a reasonable point to call it quits. Either the
     * arc4random code is broken or someone is trying to open roughly very close to
     * 2^128 (or 2^256) SSL sessions to our server. How you might store that many
     * sessions is perhaps a more interesting question...
     */
    
    #define MAX_SESS_ID_ATTEMPTS 10
    
    static int
    def_generate_session_id(const SSL *ssl, unsigned char *id, unsigned int *id_len)
    {
    	unsigned int retry = 0;
    
    	do {
    		arc4random_buf(id, *id_len);
    	} while (SSL_has_matching_session_id(ssl, id, *id_len) &&
    	    (++retry < MAX_SESS_ID_ATTEMPTS));
    
    	if (retry < MAX_SESS_ID_ATTEMPTS)
    		return 1;
    
    	/* else - woops a session_id match */
    	/* XXX We should also check the external cache --
    	 * but the probability of a collision is negligible, and
    	 * we could not prevent the concurrent creation of sessions
    	 * with identical IDs since we currently don't have means
    	 * to atomically check whether a session ID already exists
    	 * and make a reservation for it if it does not
    	 * (this problem applies to the internal cache as well).
    	 */
    	return 0;
    }
    
    int
    ssl_get_new_session(SSL *s, int session)
    {
    	unsigned int tmp;
    	SSL_SESSION *ss = NULL;
    	GEN_SESSION_CB cb = def_generate_session_id;
    
    	/* This gets used by clients and servers. */
    
    	if ((ss = SSL_SESSION_new()) == NULL)
    		return (0);
    
    	/* If the context has a default timeout, use it */
    	if (s->session_ctx->session_timeout == 0)
    		ss->timeout = SSL_get_default_timeout(s);
    	else
    		ss->timeout = s->session_ctx->session_timeout;
    
    	if (s->session != NULL) {
    		SSL_SESSION_free(s->session);
    		s->session = NULL;
    	}
    
    	if (session) {
    		switch (s->version) {
    		case TLS1_VERSION:
    		case TLS1_1_VERSION:
    		case TLS1_2_VERSION:
    		case DTLS1_VERSION:
    			ss->ssl_version = s->version;
    			ss->session_id_length = SSL3_SSL_SESSION_ID_LENGTH;
    			break;
    		default:
    			SSLerror(s, SSL_R_UNSUPPORTED_SSL_VERSION);
    			SSL_SESSION_free(ss);
    			return (0);
    		}
    
    		/* If RFC4507 ticket use empty session ID. */
    		if (s->internal->tlsext_ticket_expected) {
    			ss->session_id_length = 0;
    			goto sess_id_done;
    		}
    
    		/* Choose which callback will set the session ID. */
    		CRYPTO_r_lock(CRYPTO_LOCK_SSL_CTX);
    		if (s->internal->generate_session_id)
    			cb = s->internal->generate_session_id;
    		else if (s->session_ctx->internal->generate_session_id)
    			cb = s->session_ctx->internal->generate_session_id;
    		CRYPTO_r_unlock(CRYPTO_LOCK_SSL_CTX);
    
    		/* Choose a session ID. */
    		tmp = ss->session_id_length;
    		if (!cb(s, ss->session_id, &tmp)) {
    			/* The callback failed */
    			SSLerror(s, SSL_R_SSL_SESSION_ID_CALLBACK_FAILED);
    			SSL_SESSION_free(ss);
    			return (0);
    		}
    
    		/*
    		 * Don't allow the callback to set the session length to zero.
    		 * nor set it higher than it was.
    		 */
    		if (!tmp || (tmp > ss->session_id_length)) {
    			/* The callback set an illegal length */
    			SSLerror(s, SSL_R_SSL_SESSION_ID_HAS_BAD_LENGTH);
    			SSL_SESSION_free(ss);
    			return (0);
    		}
    		ss->session_id_length = tmp;
    
    		/* Finally, check for a conflict. */
    		if (SSL_has_matching_session_id(s, ss->session_id,
    			ss->session_id_length)) {
    			SSLerror(s, SSL_R_SSL_SESSION_ID_CONFLICT);
    			SSL_SESSION_free(ss);
    			return (0);
    		}
    
    sess_id_done:
    		if (s->tlsext_hostname) {
    			ss->tlsext_hostname = strdup(s->tlsext_hostname);
    			if (ss->tlsext_hostname == NULL) {
    				SSLerror(s, ERR_R_INTERNAL_ERROR);
    				SSL_SESSION_free(ss);
    				return 0;
    			}
    		}
    	} else {
    		ss->session_id_length = 0;
    	}
    
    	if (s->sid_ctx_length > sizeof ss->sid_ctx) {
    		SSLerror(s, ERR_R_INTERNAL_ERROR);
    		SSL_SESSION_free(ss);
    		return 0;
    	}
    
    	memcpy(ss->sid_ctx, s->sid_ctx, s->sid_ctx_length);
    	ss->sid_ctx_length = s->sid_ctx_length;
    	s->session = ss;
    	ss->ssl_version = s->version;
    	ss->verify_result = X509_V_OK;
    
    	return (1);
    }
    
    /*
     * ssl_get_prev attempts to find an SSL_SESSION to be used to resume this
     * connection. It is only called by servers.
     *
     *   session_id: points at the session ID in the ClientHello. This code will
     *       read past the end of this in order to parse out the session ticket
     *       extension, if any.
     *   session_id_len: the length of the session ID.
     *   ext_block: a CBS for the ClientHello extensions block.
     *
     * Returns:
     *   -1: error
     *    0: a session may have been found.
     *
     * Side effects:
     *   - If a session is found then s->session is pointed at it (after freeing
     *     an existing session if need be) and s->verify_result is set from the
     *     session.
     *   - Both for new and resumed sessions, s->internal->tlsext_ticket_expected is set
     *     to 1 if the server should issue a new session ticket (to 0 otherwise).
     */
    int
    ssl_get_prev_session(SSL *s, CBS *session_id, CBS *ext_block)
    {
    	SSL_SESSION *ret = NULL;
    	int fatal = 0;
    	int try_session_cache = 1;
    	int r;
    
    	/* This is used only by servers. */
    
    	if (CBS_len(session_id) > SSL_MAX_SSL_SESSION_ID_LENGTH)
    		goto err;
    
    	if (CBS_len(session_id) == 0)
    		try_session_cache = 0;
    
    	/* Sets s->internal->tlsext_ticket_expected. */
    	r = tls1_process_ticket(s, session_id, ext_block, &ret);
    	switch (r) {
    	case -1: /* Error during processing */
    		fatal = 1;
    		goto err;
    	case 0: /* No ticket found */
    	case 1: /* Zero length ticket found */
    		break; /* Ok to carry on processing session id. */
    	case 2: /* Ticket found but not decrypted. */
    	case 3: /* Ticket decrypted, *ret has been set. */
    		try_session_cache = 0;
    		break;
    	default:
    		SSLerror(s, ERR_R_INTERNAL_ERROR);
    		fatal = 1;
    		goto err;
    	}
    
    	if (try_session_cache && ret == NULL &&
    	    !(s->session_ctx->internal->session_cache_mode &
    	     SSL_SESS_CACHE_NO_INTERNAL_LOOKUP)) {
    		SSL_SESSION data;
    
    		data.ssl_version = s->version;
    		data.session_id_length = CBS_len(session_id);
    		memcpy(data.session_id, CBS_data(session_id),
    		    CBS_len(session_id));
    
    		CRYPTO_r_lock(CRYPTO_LOCK_SSL_CTX);
    		ret = lh_SSL_SESSION_retrieve(s->session_ctx->internal->sessions, &data);
    		if (ret != NULL) {
    			/* Don't allow other threads to steal it. */
    			CRYPTO_add(&ret->references, 1,
    			    CRYPTO_LOCK_SSL_SESSION);
    		}
    		CRYPTO_r_unlock(CRYPTO_LOCK_SSL_CTX);
    
    		if (ret == NULL)
    			s->session_ctx->internal->stats.sess_miss++;
    	}
    
    	if (try_session_cache && ret == NULL &&
    	    s->session_ctx->internal->get_session_cb != NULL) {
    		int copy = 1;
    
    		if ((ret = s->session_ctx->internal->get_session_cb(s,
    		    CBS_data(session_id), CBS_len(session_id), &copy))) {
    			s->session_ctx->internal->stats.sess_cb_hit++;
    
    			/*
    			 * Increment reference count now if the session
    			 * callback asks us to do so (note that if the session
    			 * structures returned by the callback are shared
    			 * between threads, it must handle the reference count
    			 * itself [i.e. copy == 0], or things won't be
    			 * thread-safe).
    			 */
    			if (copy)
    				CRYPTO_add(&ret->references, 1,
    				    CRYPTO_LOCK_SSL_SESSION);
    
    			/*
    			 * Add the externally cached session to the internal
    			 * cache as well if and only if we are supposed to.
    			 */
    			if (!(s->session_ctx->internal->session_cache_mode &
    			    SSL_SESS_CACHE_NO_INTERNAL_STORE))
    				/*
    				 * The following should not return 1,
    				 * otherwise, things are very strange.
    				 */
    				SSL_CTX_add_session(s->session_ctx, ret);
    		}
    	}
    
    	if (ret == NULL)
    		goto err;
    
    	/* Now ret is non-NULL and we own one of its reference counts. */
    
    	if (ret->sid_ctx_length != s->sid_ctx_length ||
    	    timingsafe_memcmp(ret->sid_ctx,
    		s->sid_ctx, ret->sid_ctx_length) != 0) {
    		/* We have the session requested by the client, but we don't
    		 * want to use it in this context. */
    		goto err; /* treat like cache miss */
    	}
    
    	if ((s->verify_mode & SSL_VERIFY_PEER) && s->sid_ctx_length == 0) {
    		/*
    		 * We can't be sure if this session is being used out of
    		 * context, which is especially important for SSL_VERIFY_PEER.
    		 * The application should have used
    		 * SSL[_CTX]_set_session_id_context.
    		 *
    		 * For this error case, we generate an error instead of treating
    		 * the event like a cache miss (otherwise it would be easy for
    		 * applications to effectively disable the session cache by
    		 * accident without anyone noticing).
    		 */
    		SSLerror(s, SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);
    		fatal = 1;
    		goto err;
    	}
    
    	if (ret->cipher == NULL) {
    		ret->cipher = ssl3_get_cipher_by_id(ret->cipher_id);
    		if (ret->cipher == NULL)
    			goto err;
    	}
    
    	if (ret->timeout < (time(NULL) - ret->time)) {
    		/* timeout */
    		s->session_ctx->internal->stats.sess_timeout++;
    		if (try_session_cache) {
    			/* session was from the cache, so remove it */
    			SSL_CTX_remove_session(s->session_ctx, ret);
    		}
    		goto err;
    	}
    
    	s->session_ctx->internal->stats.sess_hit++;
    
    	if (s->session != NULL)
    		SSL_SESSION_free(s->session);
    	s->session = ret;
    	s->verify_result = s->session->verify_result;
    	return 1;
    
    err:
    	if (ret != NULL) {
    		SSL_SESSION_free(ret);
    		if (!try_session_cache) {
    			/*
    			 * The session was from a ticket, so we should
    			 * issue a ticket for the new session.
    			 */
    			s->internal->tlsext_ticket_expected = 1;
    		}
    	}
    	if (fatal)
    		return -1;
    	else
    		return 0;
    }
    
    int
    SSL_CTX_add_session(SSL_CTX *ctx, SSL_SESSION *c)
    {
    	int ret = 0;
    	SSL_SESSION *s;
    
    	/*
    	 * Add just 1 reference count for the SSL_CTX's session cache
    	 * even though it has two ways of access: each session is in a
    	 * doubly linked list and an lhash.
    	 */
    	CRYPTO_add(&c->references, 1, CRYPTO_LOCK_SSL_SESSION);
    
    	/*
    	 * If session c is in already in cache, we take back the increment
    	 * later.
    	 */
    	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
    	s = lh_SSL_SESSION_insert(ctx->internal->sessions, c);
    
    	/*
    	 * s != NULL iff we already had a session with the given PID.
    	 * In this case, s == c should hold (then we did not really modify
    	 * ctx->internal->sessions), or we're in trouble.
    	 */
    	if (s != NULL && s != c) {
    		/* We *are* in trouble ... */
    		SSL_SESSION_list_remove(ctx, s);
    		SSL_SESSION_free(s);
    		/*
    		 * ... so pretend the other session did not exist in cache
    		 * (we cannot handle two SSL_SESSION structures with identical
    		 * session ID in the same cache, which could happen e.g. when
    		 * two threads concurrently obtain the same session from an
    		 * external cache).
    		 */
    		s = NULL;
    	}
    
    	/* Put at the head of the queue unless it is already in the cache */
    	if (s == NULL)
    		SSL_SESSION_list_add(ctx, c);
    
    	if (s != NULL) {
    		/*
    		 * existing cache entry -- decrement previously incremented
    		 * reference count because it already takes into account the
    		 * cache.
    		 */
    		SSL_SESSION_free(s); /* s == c */
    		ret = 0;
    	} else {
    		/*
    		 * New cache entry -- remove old ones if cache has become
    		 * too large.
    		 */
    
    		ret = 1;
    
    		if (SSL_CTX_sess_get_cache_size(ctx) > 0) {
    			while (SSL_CTX_sess_number(ctx) >
    			    SSL_CTX_sess_get_cache_size(ctx)) {
    				if (!remove_session_lock(ctx,
    				    ctx->internal->session_cache_tail, 0))
    					break;
    				else
    					ctx->internal->stats.sess_cache_full++;
    			}
    		}
    	}
    	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
    	return (ret);
    }
    
    int
    SSL_CTX_remove_session(SSL_CTX *ctx, SSL_SESSION *c)
    {
    	return remove_session_lock(ctx, c, 1);
    }
    
    static int
    remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck)
    {
    	SSL_SESSION *r;
    	int ret = 0;
    
    	if ((c != NULL) && (c->session_id_length != 0)) {
    		if (lck)
    			CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
    		if ((r = lh_SSL_SESSION_retrieve(ctx->internal->sessions, c)) == c) {
    			ret = 1;
    			r = lh_SSL_SESSION_delete(ctx->internal->sessions, c);
    			SSL_SESSION_list_remove(ctx, c);
    		}
    		if (lck)
    			CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
    
    		if (ret) {
    			r->internal->not_resumable = 1;
    			if (ctx->internal->remove_session_cb != NULL)
    				ctx->internal->remove_session_cb(ctx, r);
    			SSL_SESSION_free(r);
    		}
    	} else
    		ret = 0;
    	return (ret);
    }
    
    void
    SSL_SESSION_free(SSL_SESSION *ss)
    {
    	int i;
    
    	if (ss == NULL)
    		return;
    
    	i = CRYPTO_add(&ss->references, -1, CRYPTO_LOCK_SSL_SESSION);
    	if (i > 0)
    		return;
    
    	CRYPTO_free_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->internal->ex_data);
    
    	explicit_bzero(ss->master_key, sizeof ss->master_key);
    	explicit_bzero(ss->session_id, sizeof ss->session_id);
    
    	ssl_sess_cert_free(ss->internal->sess_cert);
    
    	X509_free(ss->peer);
    
    	sk_SSL_CIPHER_free(ss->ciphers);
    
    	free(ss->tlsext_hostname);
    	free(ss->tlsext_tick);
    	free(ss->internal->tlsext_ecpointformatlist);
    	free(ss->internal->tlsext_supportedgroups);
    
    	freezero(ss->internal, sizeof(*ss->internal));
    	freezero(ss, sizeof(*ss));
    }
    
    int
    SSL_SESSION_up_ref(SSL_SESSION *ss)
    {
    	int refs = CRYPTO_add(&ss->references, 1, CRYPTO_LOCK_SSL_SESSION);
    	return (refs > 1) ? 1 : 0;
    }
    
    int
    SSL_set_session(SSL *s, SSL_SESSION *session)
    {
    	int ret = 0;
    	const SSL_METHOD *meth;
    
    	if (session != NULL) {
    		meth = s->ctx->method->internal->get_ssl_method(session->ssl_version);
    		if (meth == NULL)
    			meth = s->method->internal->get_ssl_method(session->ssl_version);
    		if (meth == NULL) {
    			SSLerror(s, SSL_R_UNABLE_TO_FIND_SSL_METHOD);
    			return (0);
    		}
    
    		if (meth != s->method) {
    			if (!SSL_set_ssl_method(s, meth))
    				return (0);
    		}
    
    		/* CRYPTO_w_lock(CRYPTO_LOCK_SSL);*/
    		CRYPTO_add(&session->references, 1, CRYPTO_LOCK_SSL_SESSION);
    		if (s->session != NULL)
    			SSL_SESSION_free(s->session);
    		s->session = session;
    		s->verify_result = s->session->verify_result;
    		/* CRYPTO_w_unlock(CRYPTO_LOCK_SSL);*/
    		ret = 1;
    	} else {
    		if (s->session != NULL) {
    			SSL_SESSION_free(s->session);
    			s->session = NULL;
    		}
    
    		meth = s->ctx->method;
    		if (meth != s->method) {
    			if (!SSL_set_ssl_method(s, meth))
    				return (0);
    		}
    		ret = 1;
    	}
    	return (ret);
    }
    
    size_t
    SSL_SESSION_get_master_key(const SSL_SESSION *ss, unsigned char *out,
        size_t max_out)
    {
    	size_t len = ss->master_key_length;
    
    	if (out == NULL)
    		return len;
    
    	if (len > max_out)
    		len = max_out;
    
    	memcpy(out, ss->master_key, len);
    
    	return len;
    }
    
    long
    SSL_SESSION_set_timeout(SSL_SESSION *s, long t)
    {
    	if (s == NULL)
    		return (0);
    	s->timeout = t;
    	return (1);
    }
    
    long
    SSL_SESSION_get_timeout(const SSL_SESSION *s)
    {
    	if (s == NULL)
    		return (0);
    	return (s->timeout);
    }
    
    /* XXX 2038 */
    long
    SSL_SESSION_get_time(const SSL_SESSION *s)
    {
    	if (s == NULL)
    		return (0);
    	return (s->time);
    }
    
    /* XXX 2038 */
    long
    SSL_SESSION_set_time(SSL_SESSION *s, long t)
    {
    	if (s == NULL)
    		return (0);
    	s->time = t;
    	return (t);
    }
    
    int
    SSL_SESSION_get_protocol_version(const SSL_SESSION *s)
    {
    	return s->ssl_version;
    }
    
    X509 *
    SSL_SESSION_get0_peer(SSL_SESSION *s)
    {
    	return s->peer;
    }
    
    int
    SSL_SESSION_set1_id(SSL_SESSION *s, const unsigned char *sid,
        unsigned int sid_len)
    {
    	if (sid_len > SSL_MAX_SSL_SESSION_ID_LENGTH) {
    		SSLerrorx(SSL_R_SSL_SESSION_ID_TOO_LONG);
    		return 0;
    	}
    	s->session_id_length = sid_len;
    	memmove(s->session_id, sid, sid_len);
    	return 1;
    }
    
    int
    SSL_SESSION_set1_id_context(SSL_SESSION *s, const unsigned char *sid_ctx,
        unsigned int sid_ctx_len)
    {
    	if (sid_ctx_len > SSL_MAX_SID_CTX_LENGTH) {
    		SSLerrorx(SSL_R_SSL_SESSION_ID_CONTEXT_TOO_LONG);
    		return 0;
    	}
    	s->sid_ctx_length = sid_ctx_len;
    	memcpy(s->sid_ctx, sid_ctx, sid_ctx_len);
    
    	return 1;
    }
    
    long
    SSL_CTX_set_timeout(SSL_CTX *s, long t)
    {
    	long l;
    
    	if (s == NULL)
    		return (0);
    	l = s->session_timeout;
    	s->session_timeout = t;
    
    	return (l);
    }
    
    long
    SSL_CTX_get_timeout(const SSL_CTX *s)
    {
    	if (s == NULL)
    		return (0);
    	return (s->session_timeout);
    }
    
    int
    SSL_set_session_secret_cb(SSL *s, int (*tls_session_secret_cb)(SSL *s,
        void *secret, int *secret_len, STACK_OF(SSL_CIPHER) *peer_ciphers,
        SSL_CIPHER **cipher, void *arg), void *arg)
    {
    	if (s == NULL)
    		return (0);
    	s->internal->tls_session_secret_cb = tls_session_secret_cb;
    	s->internal->tls_session_secret_cb_arg = arg;
    	return (1);
    }
    
    int
    SSL_set_session_ticket_ext_cb(SSL *s, tls_session_ticket_ext_cb_fn cb,
        void *arg)
    {
    	if (s == NULL)
    		return (0);
    	s->internal->tls_session_ticket_ext_cb = cb;
    	s->internal->tls_session_ticket_ext_cb_arg = arg;
    	return (1);
    }
    
    int
    SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len)
    {
    	if (s->version >= TLS1_VERSION) {
    		free(s->internal->tlsext_session_ticket);
    		s->internal->tlsext_session_ticket =
    		    malloc(sizeof(TLS_SESSION_TICKET_EXT) + ext_len);
    		if (!s->internal->tlsext_session_ticket) {
    			SSLerror(s, ERR_R_MALLOC_FAILURE);
    			return 0;
    		}
    
    		if (ext_data) {
    			s->internal->tlsext_session_ticket->length = ext_len;
    			s->internal->tlsext_session_ticket->data =
    			    s->internal->tlsext_session_ticket + 1;
    			memcpy(s->internal->tlsext_session_ticket->data,
    			    ext_data, ext_len);
    		} else {
    			s->internal->tlsext_session_ticket->length = 0;
    			s->internal->tlsext_session_ticket->data = NULL;
    		}
    
    		return 1;
    	}
    
    	return 0;
    }
    
    typedef struct timeout_param_st {
    	SSL_CTX *ctx;
    	long time;
    	struct lhash_st_SSL_SESSION *cache;
    } TIMEOUT_PARAM;
    
    static void
    timeout_doall_arg(SSL_SESSION *s, TIMEOUT_PARAM *p)
    {
    	if ((p->time == 0) || (p->time > (s->time + s->timeout))) {
    		/* timeout */
    		/* The reason we don't call SSL_CTX_remove_session() is to
    		 * save on locking overhead */
    		(void)lh_SSL_SESSION_delete(p->cache, s);
    		SSL_SESSION_list_remove(p->ctx, s);
    		s->internal->not_resumable = 1;
    		if (p->ctx->internal->remove_session_cb != NULL)
    			p->ctx->internal->remove_session_cb(p->ctx, s);
    		SSL_SESSION_free(s);
    	}
    }
    
    static void
    timeout_LHASH_DOALL_ARG(void *arg1, void *arg2)
    {
    	SSL_SESSION *a = arg1;
    	TIMEOUT_PARAM *b = arg2;
    
    	timeout_doall_arg(a, b);
    }
    
    /* XXX 2038 */
    void
    SSL_CTX_flush_sessions(SSL_CTX *s, long t)
    {
    	unsigned long i;
    	TIMEOUT_PARAM tp;
    
    	tp.ctx = s;
    	tp.cache = s->internal->sessions;
    	if (tp.cache == NULL)
    		return;
    	tp.time = t;
    	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
    	i = CHECKED_LHASH_OF(SSL_SESSION, tp.cache)->down_load;
    	CHECKED_LHASH_OF(SSL_SESSION, tp.cache)->down_load = 0;
    	lh_SSL_SESSION_doall_arg(tp.cache, timeout_LHASH_DOALL_ARG,
    	TIMEOUT_PARAM, &tp);
    	CHECKED_LHASH_OF(SSL_SESSION, tp.cache)->down_load = i;
    	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
    }
    
    int
    ssl_clear_bad_session(SSL *s)
    {
    	if ((s->session != NULL) && !(s->internal->shutdown & SSL_SENT_SHUTDOWN) &&
    	    !(SSL_in_init(s) || SSL_in_before(s))) {
    		SSL_CTX_remove_session(s->ctx, s->session);
    		return (1);
    	} else
    		return (0);
    }
    
    /* locked by SSL_CTX in the calling function */
    static void
    SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s)
    {
    	if ((s->internal->next == NULL) || (s->internal->prev == NULL))
    		return;
    
    	if (s->internal->next == (SSL_SESSION *)&(ctx->internal->session_cache_tail)) {
    		/* last element in list */
    		if (s->internal->prev == (SSL_SESSION *)&(ctx->internal->session_cache_head)) {
    			/* only one element in list */
    			ctx->internal->session_cache_head = NULL;
    			ctx->internal->session_cache_tail = NULL;
    		} else {
    			ctx->internal->session_cache_tail = s->internal->prev;
    			s->internal->prev->internal->next =
    			    (SSL_SESSION *)&(ctx->internal->session_cache_tail);
    		}
    	} else {
    		if (s->internal->prev == (SSL_SESSION *)&(ctx->internal->session_cache_head)) {
    			/* first element in list */
    			ctx->internal->session_cache_head = s->internal->next;
    			s->internal->next->internal->prev =
    			    (SSL_SESSION *)&(ctx->internal->session_cache_head);
    		} else {
    			/* middle of list */
    			s->internal->next->internal->prev = s->internal->prev;
    			s->internal->prev->internal->next = s->internal->next;
    		}
    	}
    	s->internal->prev = s->internal->next = NULL;
    }
    
    static void
    SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s)
    {
    	if ((s->internal->next != NULL) && (s->internal->prev != NULL))
    		SSL_SESSION_list_remove(ctx, s);
    
    	if (ctx->internal->session_cache_head == NULL) {
    		ctx->internal->session_cache_head = s;
    		ctx->internal->session_cache_tail = s;
    		s->internal->prev = (SSL_SESSION *)&(ctx->internal->session_cache_head);
    		s->internal->next = (SSL_SESSION *)&(ctx->internal->session_cache_tail);
    	} else {
    		s->internal->next = ctx->internal->session_cache_head;
    		s->internal->next->internal->prev = s;
    		s->internal->prev = (SSL_SESSION *)&(ctx->internal->session_cache_head);
    		ctx->internal->session_cache_head = s;
    	}
    }
    
    void
    SSL_CTX_sess_set_new_cb(SSL_CTX *ctx,
        int (*cb)(struct ssl_st *ssl, SSL_SESSION *sess)) {
    	ctx->internal->new_session_cb = cb;
    }
    
    int
    (*SSL_CTX_sess_get_new_cb(SSL_CTX *ctx))(SSL *ssl, SSL_SESSION *sess)
    {
    	return ctx->internal->new_session_cb;
    }
    
    void
    SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx,
        void (*cb)(SSL_CTX *ctx, SSL_SESSION *sess))
    {
    	ctx->internal->remove_session_cb = cb;
    }
    
    void
    (*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx))(SSL_CTX * ctx, SSL_SESSION *sess)
    {
    	return ctx->internal->remove_session_cb;
    }
    
    void
    SSL_CTX_sess_set_get_cb(SSL_CTX *ctx, SSL_SESSION *(*cb)(struct ssl_st *ssl,
        const unsigned char *data, int len, int *copy))
    {
    	ctx->internal->get_session_cb = cb;
    }
    
    SSL_SESSION *
    (*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx))(SSL *ssl, const unsigned char *data,
        int len, int *copy)
    {
    	return ctx->internal->get_session_cb;
    }
    
    void
    SSL_CTX_set_info_callback(SSL_CTX *ctx,
        void (*cb)(const SSL *ssl, int type, int val))
    {
    	ctx->internal->info_callback = cb;
    }
    
    void
    (*SSL_CTX_get_info_callback(SSL_CTX *ctx))(const SSL *ssl, int type, int val)
    {
    	return ctx->internal->info_callback;
    }
    
    void
    SSL_CTX_set_client_cert_cb(SSL_CTX *ctx,
        int (*cb)(SSL *ssl, X509 **x509, EVP_PKEY **pkey))
    {
    	ctx->internal->client_cert_cb = cb;
    }
    
    int
    (*SSL_CTX_get_client_cert_cb(SSL_CTX *ctx))(SSL * ssl, X509 ** x509,
        EVP_PKEY **pkey)
    {
    	return ctx->internal->client_cert_cb;
    }
    
    #ifndef OPENSSL_NO_ENGINE
    int
    SSL_CTX_set_client_cert_engine(SSL_CTX *ctx, ENGINE *e)
    {
    	if (!ENGINE_init(e)) {
    		SSLerrorx(ERR_R_ENGINE_LIB);
    		return 0;
    	}
    	if (!ENGINE_get_ssl_client_cert_function(e)) {
    		SSLerrorx(SSL_R_NO_CLIENT_CERT_METHOD);
    		ENGINE_finish(e);
    		return 0;
    	}
    	ctx->internal->client_cert_engine = e;
    	return 1;
    }
    #endif
    
    void
    SSL_CTX_set_cookie_generate_cb(SSL_CTX *ctx,
        int (*cb)(SSL *ssl, unsigned char *cookie, unsigned int *cookie_len))
    {
    	ctx->internal->app_gen_cookie_cb = cb;
    }
    
    void
    SSL_CTX_set_cookie_verify_cb(SSL_CTX *ctx,
        int (*cb)(SSL *ssl, const unsigned char *cookie, unsigned int cookie_len))
    {
    	ctx->internal->app_verify_cookie_cb = cb;
    }
    
    int
    PEM_write_SSL_SESSION(FILE *fp, SSL_SESSION *x)
    {
    	return PEM_ASN1_write((i2d_of_void *)i2d_SSL_SESSION,
    	    PEM_STRING_SSL_SESSION, fp, x, NULL, NULL, 0, NULL, NULL);
    }
    
    SSL_SESSION *
    PEM_read_SSL_SESSION(FILE *fp, SSL_SESSION **x, pem_password_cb *cb, void *u)
    {
    	return PEM_ASN1_read((d2i_of_void *)d2i_SSL_SESSION,
    	    PEM_STRING_SSL_SESSION, fp, (void **)x, cb, u);
    }
    
    SSL_SESSION *
    PEM_read_bio_SSL_SESSION(BIO *bp, SSL_SESSION **x, pem_password_cb *cb, void *u)
    {
    	return PEM_ASN1_read_bio((d2i_of_void *)d2i_SSL_SESSION,
    	    PEM_STRING_SSL_SESSION, bp, (void **)x, cb, u);
    }
    
    int
    PEM_write_bio_SSL_SESSION(BIO *bp, SSL_SESSION *x)
    {
    	return PEM_ASN1_write_bio((i2d_of_void *)i2d_SSL_SESSION,
    	    PEM_STRING_SSL_SESSION, bp, x, NULL, NULL, 0, NULL, NULL);
    }