/* ssl/ssl_sess.c */

/* 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.]

 */

#include <stdio.h>

#include <openssl/lhash.h>

#include <openssl/rand.h>

#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);

EXPORT_C SSL_SESSION *SSL_get_session(const SSL *ssl)

/* aka SSL_get0_session; gets 0 objects, just returns a copy of the pointer */

	{

	return(ssl->session);

	}

EXPORT_C SSL_SESSION *SSL_get1_session(SSL *ssl)

/* variant of SSL_get_session: caller really gets something */

	{

	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);

	}

EXPORT_C 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);

	}

EXPORT_C int SSL_SESSION_set_ex_data(SSL_SESSION *s, int idx, void *arg)

	{

	return(CRYPTO_set_ex_data(&s->ex_data,idx,arg));

	}

EXPORT_C void *SSL_SESSION_get_ex_data(const SSL_SESSION *s, int idx)

	{

	return(CRYPTO_get_ex_data(&s->ex_data,idx));

	}

EXPORT_C SSL_SESSION *SSL_SESSION_new(void)

	{

	SSL_SESSION *ss;

	ss=(SSL_SESSION *)OPENSSL_malloc(sizeof(SSL_SESSION));

	if (ss == NULL)

		{

		SSLerr(SSL_F_SSL_SESSION_NEW,ERR_R_MALLOC_FAILURE);

		return(0);

		}

	memset(ss,0,sizeof(SSL_SESSION));

	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=(unsigned long)time(NULL);

	ss->prev=NULL;

	ss->next=NULL;

	ss->compress_meth=0;

	CRYPTO_new_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->ex_data);

	return(ss);

	}

EXPORT_C const unsigned char *SSL_SESSION_get_id(const SSL_SESSION *s, unsigned int *len)

	{

	if(len)

		*len = s->session_id_length;

	return s->session_id;

	}

/* Even with SSLv2, we have 16 bytes (128 bits) of session ID space. SSLv3/TLSv1

 * has 32 bytes (256 bits). 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 RAND 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

		if (RAND_pseudo_bytes(id, *id_len) <= 0)

			return 0;

	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)

	{

	/* This gets used by clients and servers. */

	unsigned int tmp;

	SSL_SESSION *ss=NULL;

	GEN_SESSION_CB cb = def_generate_session_id;

	if ((ss=SSL_SESSION_new()) == NULL) return(0);

	/* If the context has a default timeout, use it */

	if (s->ctx->session_timeout == 0)

		ss->timeout=SSL_get_default_timeout(s);

	else

		ss->timeout=s->ctx->session_timeout;

	if (s->session != NULL)

		{

		SSL_SESSION_free(s->session);

		s->session=NULL;

		}

	if (session)

		{

		if (s->version == SSL2_VERSION)

			{

			ss->ssl_version=SSL2_VERSION;

			ss->session_id_length=SSL2_SSL_SESSION_ID_LENGTH;

			}

		else if (s->version == SSL3_VERSION)

			{

			ss->ssl_version=SSL3_VERSION;

			ss->session_id_length=SSL3_SSL_SESSION_ID_LENGTH;

			}

		else if (s->version == TLS1_VERSION)

			{

			ss->ssl_version=TLS1_VERSION;

			ss->session_id_length=SSL3_SSL_SESSION_ID_LENGTH;

			}

		else if (s->version == DTLS1_VERSION)

			{

			ss->ssl_version=DTLS1_VERSION;

			ss->session_id_length=SSL3_SSL_SESSION_ID_LENGTH;

			}

		else

			{

			SSLerr(SSL_F_SSL_GET_NEW_SESSION,SSL_R_UNSUPPORTED_SSL_VERSION);

			SSL_SESSION_free(ss);

			return(0);

			}

		/* Choose which callback will set the session ID */

		CRYPTO_r_lock(CRYPTO_LOCK_SSL_CTX);

		if(s->generate_session_id)

			cb = s->generate_session_id;

		else if(s->ctx->generate_session_id)

			cb = s->ctx->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 */

			SSLerr(SSL_F_SSL_GET_NEW_SESSION,

				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 */

			SSLerr(SSL_F_SSL_GET_NEW_SESSION,

				SSL_R_SSL_SESSION_ID_HAS_BAD_LENGTH);

			SSL_SESSION_free(ss);

			return(0);

			}

		/* If the session length was shrunk and we're SSLv2, pad it */

		if((tmp < ss->session_id_length) && (s->version == SSL2_VERSION))

			memset(ss->session_id + tmp, 0, ss->session_id_length - tmp);

		else

			ss->session_id_length = tmp;

		/* Finally, check for a conflict */

		if(SSL_has_matching_session_id(s, ss->session_id,

						ss->session_id_length))

			{

			SSLerr(SSL_F_SSL_GET_NEW_SESSION,

				SSL_R_SSL_SESSION_ID_CONFLICT);

			SSL_SESSION_free(ss);

			return(0);

			}

		}

	else

		{

		ss->session_id_length=0;

		}

	if (s->sid_ctx_length > sizeof ss->sid_ctx)

		{

		SSLerr(SSL_F_SSL_GET_NEW_SESSION, 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);

	}

int ssl_get_prev_session(SSL *s, unsigned char *session_id, int len,

			const unsigned char *limit)

	{

	/* This is used only by servers. */

	SSL_SESSION *ret=NULL;

	int fatal = 0;

	if (len > SSL_MAX_SSL_SESSION_ID_LENGTH)

		goto err;

	if (!(s->ctx->session_cache_mode & SSL_SESS_CACHE_NO_INTERNAL_LOOKUP))

		{

		SSL_SESSION data;

		data.ssl_version=s->version;

		data.session_id_length=len;

		if (len == 0)

			return 0;

 		memcpy(data.session_id,session_id,len);

		CRYPTO_r_lock(CRYPTO_LOCK_SSL_CTX);

		ret=(SSL_SESSION *)lh_retrieve(s->ctx->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)

		{

		int copy=1;

		s->ctx->stats.sess_miss++;

		ret=NULL;

		if (s->ctx->get_session_cb != NULL

		    && (ret=s->ctx->get_session_cb(s,session_id,len,&copy))

		       != NULL)

			{

			s->ctx->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->ctx->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->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

	    || memcmp(ret->sid_ctx,s->sid_ctx,ret->sid_ctx_length))

		{

		/* We've found the session named by the client, but we don't

		 * want to use it in this context. */

#if 0 /* The client cannot always know when a session is not appropriate,

       * so we shouldn't generate an error message. */

		SSLerr(SSL_F_SSL_GET_PREV_SESSION,SSL_R_ATTEMPT_TO_REUSE_SESSION_IN_DIFFERENT_CONTEXT);

#endif

		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).

		 */

		SSLerr(SSL_F_SSL_GET_PREV_SESSION,SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);

		fatal = 1;

		goto err;

		}

	if (ret->cipher == NULL)

		{

		unsigned char buf[5],*p;

		unsigned long l;

		p=buf;

		l=ret->cipher_id;

		l2n(l,p);

		if ((ret->ssl_version>>8) == SSL3_VERSION_MAJOR)

			ret->cipher=ssl_get_cipher_by_char(s,&(buf[2]));

		else 

			ret->cipher=ssl_get_cipher_by_char(s,&(buf[1]));

		if (ret->cipher == NULL)

			goto err;

		}

#if 0 /* This is way too late. */

	/* If a thread got the session, then 'swaped', and another got

	 * it and then due to a time-out decided to 'OPENSSL_free' it we could

	 * be in trouble.  So I'll increment it now, then double decrement

	 * later - am I speaking rubbish?. */

	CRYPTO_add(&ret->references,1,CRYPTO_LOCK_SSL_SESSION);

#endif

	if (ret->timeout < (long)(time(NULL) - ret->time)) /* timeout */

		{

		s->ctx->stats.sess_timeout++;

		/* remove it from the cache */

		SSL_CTX_remove_session(s->ctx,ret);

		goto err;

		}

	s->ctx->stats.sess_hit++;

	/* ret->time=time(NULL); */ /* rezero timeout? */

	/* again, just leave the session 

	 * if it is the same session, we have just incremented and

	 * then decremented the reference count :-) */

	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 (fatal)

		return -1;

	else

		return 0;

	}

EXPORT_C 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=(SSL_SESSION *)lh_insert(ctx->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->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->session_cache_tail, 0))

					break;

				else

					ctx->stats.sess_cache_full++;

				}

			}

		}

	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);

	return(ret);

	}

EXPORT_C 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 = (SSL_SESSION *)lh_retrieve(ctx->sessions,c)) == c)

			{

			ret=1;

			r=(SSL_SESSION *)lh_delete(ctx->sessions,c);

			SSL_SESSION_list_remove(ctx,c);

			}

		if(lck) CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);

		if (ret)

			{

			r->not_resumable=1;

			if (ctx->remove_session_cb != NULL)

				ctx->remove_session_cb(ctx,r);

			SSL_SESSION_free(r);

			}

		}

	else

		ret=0;

	return(ret);

	}

EXPORT_C void SSL_SESSION_free(SSL_SESSION *ss)