[thirdparty/openssl.git] / ssl / ssl_sess.c

/* 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>
#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);

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);
}

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);
}

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->ex_data, idx, arg));
}

void *SSL_SESSION_get_ex_data(const SSL_SESSION *s, int idx)
{
    return (CRYPTO_get_ex_data(&s->ex_data, idx));
}

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;
#ifndef OPENSSL_NO_TLSEXT
    ss->tlsext_hostname = NULL;
#endif
    CRYPTO_new_ex_data(CRYPTO_EX_INDEX_SSL_SESSION, ss, &ss->ex_data);
    return (ss);
}

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_BAD_VER) {
            ss->ssl_version = DTLS1_BAD_VER;
            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);
        }
#ifndef OPENSSL_NO_TLSEXT
        /* If RFC4507 ticket use empty session ID */
        if (s->tlsext_ticket_expected) {
            ss->session_id_length = 0;
            goto sess_id_done;
        }
#endif
        /* 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);
        }
#ifndef OPENSSL_NO_TLSEXT
 sess_id_done:
        if (s->tlsext_hostname) {
            ss->tlsext_hostname = BUF_strdup(s->tlsext_hostname);
            if (ss->tlsext_hostname == NULL) {
                SSLerr(SSL_F_SSL_GET_NEW_SESSION, ERR_R_INTERNAL_ERROR);
                SSL_SESSION_free(ss);
                return 0;
            }
        }
#endif
    } 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;
#ifndef OPENSSL_NO_TLSEXT
    int r;
#endif

    if (len > SSL_MAX_SSL_SESSION_ID_LENGTH)
        goto err;
#ifndef OPENSSL_NO_TLSEXT
    r = tls1_process_ticket(s, session_id, len, limit, &ret);
    if (r == -1) {
        fatal = 1;
        goto err;
    } else if (r == 0 || (!ret && !len))
        goto err;
    else if (!ret
             && !(s->session_ctx->session_cache_mode &
                  SSL_SESS_CACHE_NO_INTERNAL_LOOKUP))
#else
    if (len == 0)
        goto err;
    if (!(s->ctx->session_cache_mode & SSL_SESS_CACHE_NO_INTERNAL_LOOKUP))
#endif
    {
        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;
}

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);
}

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);
}

void SSL_SESSION_free(SSL_SESSION *ss)
{
    int i;

    if (ss == NULL)
        return;

    i = CRYPTO_add(&ss->references, -1, CRYPTO_LOCK_SSL_SESSION);
#ifdef REF_PRINT
    REF_PRINT("SSL_SESSION", ss);
#endif
    if (i > 0)
        return;
#ifdef REF_CHECK
    if (i < 0) {
        fprintf(stderr, "SSL_SESSION_free, bad reference count\n");
        abort();                /* ok */
    }
#endif

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

    OPENSSL_cleanse(ss->key_arg, sizeof ss->key_arg);
    OPENSSL_cleanse(ss->master_key, sizeof ss->master_key);
    OPENSSL_cleanse(ss->session_id, sizeof ss->session_id);
    if (ss->sess_cert != NULL)
        ssl_sess_cert_free(ss->sess_cert);
    if (ss->peer != NULL)
        X509_free(ss->peer);
    if (ss->ciphers != NULL)
        sk_SSL_CIPHER_free(ss->ciphers);
#ifndef OPENSSL_NO_TLSEXT
    if (ss->tlsext_hostname != NULL)
        OPENSSL_free(ss->tlsext_hostname);
    if (ss->tlsext_tick != NULL)
        OPENSSL_free(ss->tlsext_tick);
#endif
    OPENSSL_cleanse(ss, sizeof(*ss));
    OPENSSL_free(ss);
}

int SSL_set_session(SSL *s, SSL_SESSION *session)
{
    int ret = 0;
    SSL_METHOD *meth;

    if (session != NULL) {
        meth = s->ctx->method->get_ssl_method(session->ssl_version);
        if (meth == NULL)
            meth = s->method->get_ssl_method(session->ssl_version);
        if (meth == NULL) {
            SSLerr(SSL_F_SSL_SET_SESSION, SSL_R_UNABLE_TO_FIND_SSL_METHOD);
            return (0);
        }

        if (meth != s->method) {
            if (!SSL_set_ssl_method(s, meth))
                return (0);
            if (s->ctx->session_timeout == 0)
                session->timeout = SSL_get_default_timeout(s);
            else
                session->timeout = s->ctx->session_timeout;
        }
#ifndef OPENSSL_NO_KRB5
        if (s->kssl_ctx && !s->kssl_ctx->client_princ &&
            session->krb5_client_princ_len > 0) {
            s->kssl_ctx->client_princ =
                (char *)OPENSSL_malloc(session->krb5_client_princ_len + 1);
            memcpy(s->kssl_ctx->client_princ, session->krb5_client_princ,
                   session->krb5_client_princ_len);
            s->kssl_ctx->client_princ[session->krb5_client_princ_len] = '\0';
        }
#endif                          /* OPENSSL_NO_KRB5 */

        /* 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);
}

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);
}

long SSL_SESSION_get_time(const SSL_SESSION *s)
{
    if (s == NULL)
        return (0);
    return (s->time);
}

long SSL_SESSION_set_time(SSL_SESSION *s, long t)
{
    if (s == NULL)
        return (0);
    s->time = t;
    return (t);
}

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);
}

typedef struct timeout_param_st {
    SSL_CTX *ctx;
    long time;
    LHASH *cache;
} TIMEOUT_PARAM;

static void timeout(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
         */
        lh_delete(p->cache, s);
        SSL_SESSION_list_remove(p->ctx, s);
        s->not_resumable = 1;
        if (p->ctx->remove_session_cb != NULL)
            p->ctx->remove_session_cb(p->ctx, s);
        SSL_SESSION_free(s);
    }
}

static IMPLEMENT_LHASH_DOALL_ARG_FN(timeout, SSL_SESSION *, TIMEOUT_PARAM *)

void SSL_CTX_flush_sessions(SSL_CTX *s, long t)
{
    unsigned long i;
    TIMEOUT_PARAM tp;

    tp.ctx = s;
    tp.cache = s->sessions;
    if (tp.cache == NULL)
        return;
    tp.time = t;
    CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
    i = tp.cache->down_load;
    tp.cache->down_load = 0;
    lh_doall_arg(tp.cache, LHASH_DOALL_ARG_FN(timeout), &tp);
    tp.cache->down_load = i;
    CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
}

int ssl_clear_bad_session(SSL *s)
{
    if ((s->session != NULL) &&
        !(s->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->next == NULL) || (s->prev == NULL))
        return;

    if (s->next == (SSL_SESSION *)&(ctx->session_cache_tail)) {
        /* last element in list */
        if (s->prev == (SSL_SESSION *)&(ctx->session_cache_head)) {
            /* only one element in list */
            ctx->session_cache_head = NULL;
            ctx->session_cache_tail = NULL;
        } else {
            ctx->session_cache_tail = s->prev;
            s->prev->next = (SSL_SESSION *)&(ctx->session_cache_tail);
        }
    } else {
        if (s->prev == (SSL_SESSION *)&(ctx->session_cache_head)) {
            /* first element in list */
            ctx->session_cache_head = s->next;
            s->next->prev = (SSL_SESSION *)&(ctx->session_cache_head);
        } else {
            /* middle of list */
            s->next->prev = s->prev;
            s->prev->next = s->next;
        }
    }
    s->prev = s->next = NULL;
}

static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s)
{
    if ((s->next != NULL) && (s->prev != NULL))
        SSL_SESSION_list_remove(ctx, s);

    if (ctx->session_cache_head == NULL) {
        ctx->session_cache_head = s;
        ctx->session_cache_tail = s;
        s->prev = (SSL_SESSION *)&(ctx->session_cache_head);
        s->next = (SSL_SESSION *)&(ctx->session_cache_tail);
    } else {
        s->next = ctx->session_cache_head;
        s->next->prev = s;
        s->prev = (SSL_SESSION *)&(ctx->session_cache_head);
        ctx->session_cache_head = s;
    }
}

void SSL_CTX_sess_set_new_cb(SSL_CTX *ctx,
                             int (*cb) (struct ssl_st *ssl,
                                        SSL_SESSION *sess))
{
    ctx->new_session_cb = cb;
}

int (*SSL_CTX_sess_get_new_cb(SSL_CTX *ctx)) (SSL *ssl, SSL_SESSION *sess) {
    return ctx->new_session_cb;
}

void SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx,
                                void (*cb) (SSL_CTX *ctx, SSL_SESSION *sess))
{
    ctx->remove_session_cb = cb;
}

void (*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx)) (SSL_CTX *ctx,
                                                  SSL_SESSION *sess) {
    return ctx->remove_session_cb;
}

void SSL_CTX_sess_set_get_cb(SSL_CTX *ctx,
                             SSL_SESSION *(*cb) (struct ssl_st *ssl,
                                                 unsigned char *data, int len,
                                                 int *copy))
{
    ctx->get_session_cb = cb;
}

SSL_SESSION *(*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx)) (SSL *ssl,
                                                       unsigned char *data,
                                                       int len, int *copy) {
    return ctx->get_session_cb;
}

void SSL_CTX_set_info_callback(SSL_CTX *ctx,
                               void (*cb) (const SSL *ssl, int type, int val))
{
    ctx->info_callback = cb;
}

void (*SSL_CTX_get_info_callback(SSL_CTX *ctx)) (const SSL *ssl, int type,
                                                 int val) {
    return ctx->info_callback;
}

void SSL_CTX_set_client_cert_cb(SSL_CTX *ctx,
                                int (*cb) (SSL *ssl, X509 **x509,
                                           EVP_PKEY **pkey))
{
    ctx->client_cert_cb = cb;
}

int (*SSL_CTX_get_client_cert_cb(SSL_CTX *ctx)) (SSL *ssl, X509 **x509,
                                                 EVP_PKEY **pkey) {
    return ctx->client_cert_cb;
}

#ifndef OPENSSL_NO_ENGINE
int SSL_CTX_set_client_cert_engine(SSL_CTX *ctx, ENGINE *e)
{
    if (!ENGINE_init(e)) {
        SSLerr(SSL_F_SSL_CTX_SET_CLIENT_CERT_ENGINE, ERR_R_ENGINE_LIB);
        return 0;
    }
    if (!ENGINE_get_ssl_client_cert_function(e)) {
        SSLerr(SSL_F_SSL_CTX_SET_CLIENT_CERT_ENGINE,
               SSL_R_NO_CLIENT_CERT_METHOD);
        ENGINE_finish(e);
        return 0;
    }
    ctx->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->app_gen_cookie_cb = cb;
}

void SSL_CTX_set_cookie_verify_cb(SSL_CTX *ctx,
                                  int (*cb) (SSL *ssl, unsigned char *cookie,
                                             unsigned int cookie_len))
{
    ctx->app_verify_cookie_cb = cb;
}