ssl_engine_init.c

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*                      _             _
 *  _ __ ___   ___   __| |    ___ ___| |  mod_ssl
 * | '_ ` _ \ / _ \ / _` |   / __/ __| |  Apache Interface to OpenSSL
 * | | | | | | (_) | (_| |   \__ \__ \ |
 * |_| |_| |_|\___/ \__,_|___|___/___/_|
 *                      |_____|
 *  ssl_engine_init.c
 *  Initialization of Servers
 */
                             /* ``Recursive, adj.;
                                  see Recursive.''
                                        -- Unknown   */
#include "ssl_private.h"
#include "mod_ssl.h"
#include "mod_ssl_openssl.h"
#include "mpm_common.h"

APR_IMPLEMENT_OPTIONAL_HOOK_RUN_ALL(ssl, SSL, int, init_server,
                                    (server_rec *s,apr_pool_t *p,int is_proxy,SSL_CTX *ctx),
                                    (s,p,is_proxy,ctx), OK, DECLINED)

/*  _________________________________________________________________
**
**  Module Initialization
**  _________________________________________________________________
*/

#ifdef HAVE_ECC
#define KEYTYPES "RSA, DSA or ECC"
#else 
#define KEYTYPES "RSA or DSA"
#endif

#if MODSSL_USE_OPENSSL_PRE_1_1_API
/* OpenSSL Pre-1.1.0 compatibility */
/* Taken from OpenSSL 1.1.0 snapshot 20160410 */
static int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g)
{
    /* q is optional */
    if (p == NULL || g == NULL)
        return 0;
    BN_free(dh->p);
    BN_free(dh->q);
    BN_free(dh->g);
    dh->p = p;
    dh->q = q;
    dh->g = g;

    if (q != NULL) {
        dh->length = BN_num_bits(q);
    }

    return 1;
}
#endif

/*
 * Grab well-defined DH parameters from OpenSSL, see the BN_get_rfc*
 * functions in <openssl/bn.h> for all available primes.
 */
static DH *make_dh_params(BIGNUM *(*prime)(BIGNUM *))
{
    DH *dh = DH_new();
    BIGNUM *p, *g;

    if (!dh) {
        return NULL;
    }
    p = prime(NULL);
    g = BN_new();
    if (g != NULL) {
        BN_set_word(g, 2);
    }
    if (!p || !g || !DH_set0_pqg(dh, p, NULL, g)) {
        DH_free(dh);
        BN_free(p);
        BN_free(g);
        return NULL;
    }
    return dh;
}

/* Storage and initialization for DH parameters. */
static struct dhparam {
    BIGNUM *(*const prime)(BIGNUM *); /* function to generate... */
    DH *dh;                           /* ...this, used for keys.... */
    const unsigned int min;           /* ...of length >= this. */
} dhparams[] = {
    { BN_get_rfc3526_prime_8192, NULL, 6145 },
    { BN_get_rfc3526_prime_6144, NULL, 4097 },
    { BN_get_rfc3526_prime_4096, NULL, 3073 },
    { BN_get_rfc3526_prime_3072, NULL, 2049 },
    { BN_get_rfc3526_prime_2048, NULL, 1025 },
    { BN_get_rfc2409_prime_1024, NULL, 0 }
};

static void init_dh_params(void)
{
    unsigned n;

    for (n = 0; n < sizeof(dhparams)/sizeof(dhparams[0]); n++)
        dhparams[n].dh = make_dh_params(dhparams[n].prime);
}

static void free_dh_params(void)
{
    unsigned n;

    /* DH_free() is a noop for a NULL parameter, so these are harmless
     * in the (unexpected) case where these variables are already
     * NULL. */
    for (n = 0; n < sizeof(dhparams)/sizeof(dhparams[0]); n++) {
        DH_free(dhparams[n].dh);
        dhparams[n].dh = NULL;
    }
}

/* Hand out the same DH structure though once generated as we leak
 * memory otherwise and freeing the structure up after use would be
 * hard to track and in fact is not needed at all as it is safe to
 * use the same parameters over and over again security wise (in
 * contrast to the keys itself) and code safe as the returned structure
 * is duplicated by OpenSSL anyway. Hence no modification happens
 * to our copy. */
DH *modssl_get_dh_params(unsigned keylen)
{
    unsigned n;

    for (n = 0; n < sizeof(dhparams)/sizeof(dhparams[0]); n++)
        if (keylen >= dhparams[n].min)
            return dhparams[n].dh;
        
    return NULL; /* impossible to reach. */
}

static void ssl_add_version_components(apr_pool_t *p,
                                       server_rec *s)
{
    char *modver = ssl_var_lookup(p, s, NULL, NULL, "SSL_VERSION_INTERFACE");
    char *libver = ssl_var_lookup(p, s, NULL, NULL, "SSL_VERSION_LIBRARY");
    char *incver = ssl_var_lookup(p, s, NULL, NULL,
                                  "SSL_VERSION_LIBRARY_INTERFACE");

    ap_add_version_component(p, libver);

    ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, APLOGNO(01876)
                 "%s compiled against Server: %s, Library: %s",
                 modver, AP_SERVER_BASEVERSION, incver);
}

/*
 *  Per-module initialization
 */
apr_status_t ssl_init_Module(apr_pool_t *p, apr_pool_t *plog,
                             apr_pool_t *ptemp,
                             server_rec *base_server)
{
    SSLModConfigRec *mc = myModConfig(base_server);
    SSLSrvConfigRec *sc;
    server_rec *s;
    apr_status_t rv;
    apr_array_header_t *pphrases;

    if (SSLeay() < MODSSL_LIBRARY_VERSION) {
        ap_log_error(APLOG_MARK, APLOG_WARNING, 0, base_server, APLOGNO(01882)
                     "Init: this version of mod_ssl was compiled against "
                     "a newer library (%s, version currently loaded is %s)"
                     " - may result in undefined or erroneous behavior",
                     MODSSL_LIBRARY_TEXT, MODSSL_LIBRARY_DYNTEXT);
    }

    /* We initialize mc->pid per-process in the child init,
     * but it should be initialized for startup before we
     * call ssl_rand_seed() below.
     */
    mc->pid = getpid();

    /*
     * Let us cleanup on restarts and exits
     */
    apr_pool_cleanup_register(p, base_server,
                              ssl_init_ModuleKill,
                              apr_pool_cleanup_null);

    /*
     * Any init round fixes the global config
     */
    ssl_config_global_create(base_server); /* just to avoid problems */
    ssl_config_global_fix(mc);

    /*
     *  try to fix the configuration and open the dedicated SSL
     *  logfile as early as possible
     */
    for (s = base_server; s; s = s->next) {
        sc = mySrvConfig(s);

        if (sc->server) {
            sc->server->sc = sc;
        }

        if (sc->proxy) {
            sc->proxy->sc = sc;
        }

        /*
         * Create the server host:port string because we need it a lot
         */
        sc->vhost_id = ssl_util_vhostid(p, s);
        sc->vhost_id_len = strlen(sc->vhost_id);

        /* Default to enabled if SSLEngine is not set explicitly, and
         * the protocol is https. */
        if (ap_get_server_protocol(s) 
            && strcmp("https", ap_get_server_protocol(s)) == 0
            && sc->enabled == SSL_ENABLED_UNSET) {
            sc->enabled = SSL_ENABLED_TRUE;
        }

        /* Fix up stuff that may not have been set.  If sc->enabled is
         * UNSET, then SSL is disabled on this vhost.  */
        if (sc->enabled == SSL_ENABLED_UNSET) {
            sc->enabled = SSL_ENABLED_FALSE;
        }
        if (sc->proxy_enabled == UNSET) {
            sc->proxy_enabled = FALSE;
        }

        if (sc->session_cache_timeout == UNSET) {
            sc->session_cache_timeout = SSL_SESSION_CACHE_TIMEOUT;
        }

        if (sc->server && sc->server->pphrase_dialog_type == SSL_PPTYPE_UNSET) {
            sc->server->pphrase_dialog_type = SSL_PPTYPE_BUILTIN;
        }

#ifdef HAVE_FIPS
        if (sc->fips == UNSET) {
            sc->fips = FALSE;
        }
#endif
    }

#if APR_HAS_THREADS && MODSSL_USE_OPENSSL_PRE_1_1_API
    ssl_util_thread_setup(p);
#endif

    /*
     * SSL external crypto device ("engine") support
     */
#if defined(HAVE_OPENSSL_ENGINE_H) && defined(HAVE_ENGINE_INIT)
    if ((rv = ssl_init_Engine(base_server, p)) != APR_SUCCESS) {
        return rv;
    }
#endif

    ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, APLOGNO(01883)
                 "Init: Initialized %s library", MODSSL_LIBRARY_NAME);

    /*
     * Seed the Pseudo Random Number Generator (PRNG)
     * only need ptemp here; nothing inside allocated from the pool
     * needs to live once we return from ssl_rand_seed().
     */
    ssl_rand_seed(base_server, ptemp, SSL_RSCTX_STARTUP, "Init: ");

#ifdef HAVE_FIPS
    if(sc->fips) {
        if (!FIPS_mode()) {
            if (FIPS_mode_set(1)) {
                ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, s, APLOGNO(01884)
                             "Operating in SSL FIPS mode");
            }
            else {
                ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01885) "FIPS mode failed");
                ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
                return ssl_die(s);
            }
        }
    }
    else {
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01886)
                     "SSL FIPS mode disabled");
    }
#endif

    /*
     * initialize the mutex handling
     */
    if (!ssl_mutex_init(base_server, p)) {
        return HTTP_INTERNAL_SERVER_ERROR;
    }
#ifdef HAVE_OCSP_STAPLING
    ssl_stapling_certinfo_hash_init(p);
#endif

    /*
     * initialize session caching
     */
    if ((rv = ssl_scache_init(base_server, p)) != APR_SUCCESS) {
        return rv;
    }

    pphrases = apr_array_make(ptemp, 2, sizeof(char *));

    /*
     *  initialize servers
     */
    ap_log_error(APLOG_MARK, APLOG_INFO, 0, base_server, APLOGNO(01887)
                 "Init: Initializing (virtual) servers for SSL");

    for (s = base_server; s; s = s->next) {
        sc = mySrvConfig(s);
        /*
         * Either now skip this server when SSL is disabled for
         * it or give out some information about what we're
         * configuring.
         */

        /*
         * Read the server certificate and key
         */
        if ((rv = ssl_init_ConfigureServer(s, p, ptemp, sc, pphrases))
            != APR_SUCCESS) {
            return rv;
        }
    }

    if (pphrases->nelts > 0) {
        memset(pphrases->elts, 0, pphrases->elt_size * pphrases->nelts);
        pphrases->nelts = 0;
        ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, APLOGNO(02560)
                     "Init: Wiped out the queried pass phrases from memory");
    }

    /*
     * Configuration consistency checks
     */
    if ((rv = ssl_init_CheckServers(base_server, ptemp)) != APR_SUCCESS) {
        return rv;
    }

    for (s = base_server; s; s = s->next) {
        sc = mySrvConfig(s);

        if (sc->enabled == SSL_ENABLED_TRUE || sc->enabled == SSL_ENABLED_OPTIONAL) {
            if ((rv = ssl_run_init_server(s, p, 0, sc->server->ssl_ctx)) != APR_SUCCESS) {
                return rv;
            }
        }
        else if (sc->proxy_enabled == SSL_ENABLED_TRUE) {
            if ((rv = ssl_run_init_server(s, p, 1, sc->proxy->ssl_ctx)) != APR_SUCCESS) {
                return rv;
            }
        }
    }

    /*
     *  Announce mod_ssl and SSL library in HTTP Server field
     *  as ``mod_ssl/X.X.X OpenSSL/X.X.X''
     */
    ssl_add_version_components(p, base_server);

    modssl_init_app_data2_idx(); /* for modssl_get_app_data2() at request time */

    init_dh_params();
#if !MODSSL_USE_OPENSSL_PRE_1_1_API
    init_bio_methods();
#endif

    return OK;
}

/*
 * Support for external a Crypto Device ("engine"), usually
 * a hardware accellerator card for crypto operations.
 */
#if defined(HAVE_OPENSSL_ENGINE_H) && defined(HAVE_ENGINE_INIT)
apr_status_t ssl_init_Engine(server_rec *s, apr_pool_t *p)
{
    SSLModConfigRec *mc = myModConfig(s);
    ENGINE *e;

    if (mc->szCryptoDevice) {
        if (!(e = ENGINE_by_id(mc->szCryptoDevice))) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01888)
                         "Init: Failed to load Crypto Device API `%s'",
                         mc->szCryptoDevice);
            ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
            return ssl_die(s);
        }

#ifdef ENGINE_CTRL_CHIL_SET_FORKCHECK
        if (strEQ(mc->szCryptoDevice, "chil")) {
            ENGINE_ctrl(e, ENGINE_CTRL_CHIL_SET_FORKCHECK, 1, 0, 0);
        }
#endif

        if (!ENGINE_set_default(e, ENGINE_METHOD_ALL)) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01889)
                         "Init: Failed to enable Crypto Device API `%s'",
                         mc->szCryptoDevice);
            ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
            return ssl_die(s);
        }
        ap_log_error(APLOG_MARK, APLOG_INFO, 0, s, APLOGNO(01890)
                     "Init: loaded Crypto Device API `%s'",
                     mc->szCryptoDevice);

        ENGINE_free(e);
    }

    return APR_SUCCESS;
}
#endif

#ifdef HAVE_TLSEXT
static apr_status_t ssl_init_ctx_tls_extensions(server_rec *s,
                                                apr_pool_t *p,
                                                apr_pool_t *ptemp,
                                                modssl_ctx_t *mctx)
{
    apr_status_t rv;

    /*
     * Configure TLS extensions support
     */
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01893)
                 "Configuring TLS extension handling");

    /*
     * Server name indication (SNI)
     */
    if (!SSL_CTX_set_tlsext_servername_callback(mctx->ssl_ctx,
                          ssl_callback_ServerNameIndication) ||
        !SSL_CTX_set_tlsext_servername_arg(mctx->ssl_ctx, mctx)) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01894)
                     "Unable to initialize TLS servername extension "
                     "callback (incompatible OpenSSL version?)");
        ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
        return ssl_die(s);
    }

#ifdef HAVE_OCSP_STAPLING
    /*
     * OCSP Stapling support, status_request extension
     */
    if ((mctx->pkp == FALSE) && (mctx->stapling_enabled == TRUE)) {
        if ((rv = modssl_init_stapling(s, p, ptemp, mctx)) != APR_SUCCESS) {
            return rv;
        }
    }
#endif

#ifdef HAVE_SRP
    /*
     * TLS-SRP support
     */
    if (mctx->srp_vfile != NULL) {
        int err;
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02308)
                     "Using SRP verifier file [%s]", mctx->srp_vfile);

        if (!(mctx->srp_vbase = SRP_VBASE_new(mctx->srp_unknown_user_seed))) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(02309)
                         "Unable to initialize SRP verifier structure "
                         "[%s seed]",
                         mctx->srp_unknown_user_seed ? "with" : "without");
            ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
            return ssl_die(s);
        }

        err = SRP_VBASE_init(mctx->srp_vbase, mctx->srp_vfile);
        if (err != SRP_NO_ERROR) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(02310)
                         "Unable to load SRP verifier file [error %d]", err);
            ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
            return ssl_die(s);
        }

        SSL_CTX_set_srp_username_callback(mctx->ssl_ctx,
                                          ssl_callback_SRPServerParams);
        SSL_CTX_set_srp_cb_arg(mctx->ssl_ctx, mctx);
    }
#endif
    return APR_SUCCESS;
}
#endif

static apr_status_t ssl_init_ctx_protocol(server_rec *s,
                                          apr_pool_t *p,
                                          apr_pool_t *ptemp,
                                          modssl_ctx_t *mctx)
{
    SSL_CTX *ctx = NULL;
    MODSSL_SSL_METHOD_CONST SSL_METHOD *method = NULL;
    char *cp;
    int protocol = mctx->protocol;
    SSLSrvConfigRec *sc = mySrvConfig(s);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
    int prot;
#endif

    /*
     *  Create the new per-server SSL context
     */
    if (protocol == SSL_PROTOCOL_NONE) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(02231)
                "No SSL protocols available [hint: SSLProtocol]");
        return ssl_die(s);
    }

    cp = apr_pstrcat(p,
#ifndef OPENSSL_NO_SSL3
                     (protocol & SSL_PROTOCOL_SSLV3 ? "SSLv3, " : ""),
#endif
                     (protocol & SSL_PROTOCOL_TLSV1 ? "TLSv1, " : ""),
#ifdef HAVE_TLSV1_X
                     (protocol & SSL_PROTOCOL_TLSV1_1 ? "TLSv1.1, " : ""),
                     (protocol & SSL_PROTOCOL_TLSV1_2 ? "TLSv1.2, " : ""),
#endif
                     NULL);
    cp[strlen(cp)-2] = NUL;

    ap_log_error(APLOG_MARK, APLOG_TRACE3, 0, s,
                 "Creating new SSL context (protocols: %s)", cp);

#if OPENSSL_VERSION_NUMBER < 0x10100000L
#ifndef OPENSSL_NO_SSL3
    if (protocol == SSL_PROTOCOL_SSLV3) {
        method = mctx->pkp ?
            SSLv3_client_method() : /* proxy */
            SSLv3_server_method();  /* server */
    }
    else
#endif
    if (protocol == SSL_PROTOCOL_TLSV1) {
        method = mctx->pkp ?
            TLSv1_client_method() : /* proxy */
            TLSv1_server_method();  /* server */
    }
#ifdef HAVE_TLSV1_X
    else if (protocol == SSL_PROTOCOL_TLSV1_1) {
        method = mctx->pkp ?
            TLSv1_1_client_method() : /* proxy */
            TLSv1_1_server_method();  /* server */
    }
    else if (protocol == SSL_PROTOCOL_TLSV1_2) {
        method = mctx->pkp ?
            TLSv1_2_client_method() : /* proxy */
            TLSv1_2_server_method();  /* server */
    }
#endif
#ifdef HAVE_MCTLS
    else if (protocol == SSL_PROTOCOL_MCTLS) {
    	method = mctx->pkp ?
    		/*was SPP_client_method()*/
    		SPP_proxy_method() : /* proxy */
			SPP_server_method();  /* server */
    }
#endif
    else { /* For multiple protocols, we need a flexible method */
        method = mctx->pkp ?
            SSLv23_client_method() : /* proxy */
            SSLv23_server_method();  /* server */
    }
#else
    method = mctx->pkp ?
        TLS_client_method() : /* proxy */
        TLS_server_method();  /* server */
#endif
    ctx = SSL_CTX_new(method);

    mctx->ssl_ctx = ctx;

    SSL_CTX_set_options(ctx, SSL_OP_ALL);

#if OPENSSL_VERSION_NUMBER < 0x10100000L
    /* always disable SSLv2, as per RFC 6176 */
    SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2);

#ifndef OPENSSL_NO_SSL3
    if (!(protocol & SSL_PROTOCOL_SSLV3)) {
        SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv3);
    }
#endif

    if (!(protocol & SSL_PROTOCOL_TLSV1)) {
        SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1);
    }

#ifdef HAVE_TLSV1_X
    if (!(protocol & SSL_PROTOCOL_TLSV1_1)) {
        SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_1);
    }

    if (!(protocol & SSL_PROTOCOL_TLSV1_2)) {
        SSL_CTX_set_options(ctx, SSL_OP_NO_TLSv1_2);
    }
#endif

#else /* #if OPENSSL_VERSION_NUMBER < 0x10100000L */
    /* We first determine the maximum protocol version we should provide */
    if (protocol & SSL_PROTOCOL_TLSV1_2) {
        prot = TLS1_2_VERSION;
    } else if (protocol & SSL_PROTOCOL_TLSV1_1) {
        prot = TLS1_1_VERSION;
    } else if (protocol & SSL_PROTOCOL_TLSV1) {
        prot = TLS1_VERSION;
#ifndef OPENSSL_NO_SSL3
    } else if (protocol & SSL_PROTOCOL_SSLV3) {
        prot = SSL3_VERSION;
#endif
    } else {
        SSL_CTX_free(ctx);
        mctx->ssl_ctx = NULL;
        ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(03378)
                "No SSL protocols available [hint: SSLProtocol]");
        return ssl_die(s);
    }
    SSL_CTX_set_max_proto_version(ctx, prot);

    /* Next we scan for the minimal protocol version we should provide,
     * but we do not allow holes between max and min */
    if (prot == TLS1_2_VERSION && protocol & SSL_PROTOCOL_TLSV1_1) {
        prot = TLS1_1_VERSION;
    }
    if (prot == TLS1_1_VERSION && protocol & SSL_PROTOCOL_TLSV1) {
        prot = TLS1_VERSION;
    }
#ifndef OPENSSL_NO_SSL3
    if (prot == TLS1_VERSION && protocol & SSL_PROTOCOL_SSLV3) {
        prot = SSL3_VERSION;
    }
#endif
    SSL_CTX_set_min_proto_version(ctx, prot);
#endif /* if OPENSSL_VERSION_NUMBER < 0x10100000L */

#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
    if (sc->cipher_server_pref == TRUE) {
        SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
    }
#endif
#ifdef HAVE_MCTLS
    if(protocol==SSL_PROTOCOL_MCTLS) {
        if (!SSL_CTX_set_cipher_list(ctx, "DHE-RSA-AES128-SHA256")) {
            SSL_CTX_free(ctx);
            mctx->ssl_ctx = NULL;
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(03378)
                    "DHS-RSA-AES128-SHA256 not available for mcTLS");
            return ssl_die(s);
        }

    }
#endif


#ifndef OPENSSL_NO_COMP
    if (sc->compression != TRUE) {
#ifdef SSL_OP_NO_COMPRESSION
        /* OpenSSL >= 1.0 only */
        SSL_CTX_set_options(ctx, SSL_OP_NO_COMPRESSION);
#else
        sk_SSL_COMP_zero(SSL_COMP_get_compression_methods());
#endif
    }
#endif

#ifdef SSL_OP_NO_TICKET
    /*
     * Configure using RFC 5077 TLS session tickets
     * for session resumption.
     */
    if (sc->session_tickets == FALSE) {
        SSL_CTX_set_options(ctx, SSL_OP_NO_TICKET);
    }
#endif

#ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
    if (sc->insecure_reneg == TRUE) {
        SSL_CTX_set_options(ctx, SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION);
    }
#endif

    SSL_CTX_set_app_data(ctx, s);

    /*
     * Configure additional context ingredients
     */
    SSL_CTX_set_options(ctx, SSL_OP_SINGLE_DH_USE);
#ifdef HAVE_ECC
    SSL_CTX_set_options(ctx, SSL_OP_SINGLE_ECDH_USE);
#endif

#ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
    /*
     * Disallow a session from being resumed during a renegotiation,
     * so that an acceptable cipher suite can be negotiated.
     */
    SSL_CTX_set_options(ctx, SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION);
#endif

#ifdef SSL_MODE_RELEASE_BUFFERS
    /* If httpd is configured to reduce mem usage, ask openssl to do so, too */
    if (ap_max_mem_free != APR_ALLOCATOR_MAX_FREE_UNLIMITED)
        SSL_CTX_set_mode(ctx, SSL_MODE_RELEASE_BUFFERS);
#endif

    return APR_SUCCESS;
}

static void ssl_init_ctx_session_cache(server_rec *s,
                                       apr_pool_t *p,
                                       apr_pool_t *ptemp,
                                       modssl_ctx_t *mctx)
{
    SSL_CTX *ctx = mctx->ssl_ctx;
    SSLModConfigRec *mc = myModConfig(s);

    SSL_CTX_set_session_cache_mode(ctx, mc->sesscache_mode);

    if (mc->sesscache) {
        SSL_CTX_sess_set_new_cb(ctx,    ssl_callback_NewSessionCacheEntry);
        SSL_CTX_sess_set_get_cb(ctx,    ssl_callback_GetSessionCacheEntry);
        SSL_CTX_sess_set_remove_cb(ctx, ssl_callback_DelSessionCacheEntry);
    }
}

static void ssl_init_ctx_callbacks(server_rec *s,
                                   apr_pool_t *p,
                                   apr_pool_t *ptemp,
                                   modssl_ctx_t *mctx)
{
    SSL_CTX *ctx = mctx->ssl_ctx;

    SSL_CTX_set_tmp_dh_callback(ctx,  ssl_callback_TmpDH);

    SSL_CTX_set_info_callback(ctx, ssl_callback_Info);

#ifdef HAVE_TLS_ALPN
    SSL_CTX_set_alpn_select_cb(ctx, ssl_callback_alpn_select, NULL);
#endif
}

static apr_status_t ssl_init_ctx_verify(server_rec *s,
                                        apr_pool_t *p,
                                        apr_pool_t *ptemp,
                                        modssl_ctx_t *mctx)
{
    SSL_CTX *ctx = mctx->ssl_ctx;

    int verify = SSL_VERIFY_NONE;
    STACK_OF(X509_NAME) *ca_list;

    if (mctx->auth.verify_mode == SSL_CVERIFY_UNSET) {
        mctx->auth.verify_mode = SSL_CVERIFY_NONE;
    }

    if (mctx->auth.verify_depth == UNSET) {
        mctx->auth.verify_depth = 1;
    }

    /*
     *  Configure callbacks for SSL context
     */
    if (mctx->auth.verify_mode == SSL_CVERIFY_REQUIRE) {
        verify |= SSL_VERIFY_PEER_STRICT;
    }

    if ((mctx->auth.verify_mode == SSL_CVERIFY_OPTIONAL) ||
        (mctx->auth.verify_mode == SSL_CVERIFY_OPTIONAL_NO_CA))
    {
        verify |= SSL_VERIFY_PEER;
    }

    SSL_CTX_set_verify(ctx, verify, ssl_callback_SSLVerify);

    /*
     * Configure Client Authentication details
     */
    if (mctx->auth.ca_cert_file || mctx->auth.ca_cert_path) {
        ap_log_error(APLOG_MARK, APLOG_TRACE1, 0, s,
                     "Configuring client authentication");

        if (!SSL_CTX_load_verify_locations(ctx,
                                           mctx->auth.ca_cert_file,
                                           mctx->auth.ca_cert_path))
        {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01895)
                    "Unable to configure verify locations "
                    "for client authentication");
            ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
            return ssl_die(s);
        }

        if (mctx->pks && (mctx->pks->ca_name_file || mctx->pks->ca_name_path)) {
            ca_list = ssl_init_FindCAList(s, ptemp,
                                          mctx->pks->ca_name_file,
                                          mctx->pks->ca_name_path);
        } else
            ca_list = ssl_init_FindCAList(s, ptemp,
                                          mctx->auth.ca_cert_file,
                                          mctx->auth.ca_cert_path);
        if (sk_X509_NAME_num(ca_list) <= 0) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01896)
                    "Unable to determine list of acceptable "
                    "CA certificates for client authentication");
            return ssl_die(s);
        }

        SSL_CTX_set_client_CA_list(ctx, ca_list);
    }

    /*
     * Give a warning when no CAs were configured but client authentication
     * should take place. This cannot work.
     */
    if (mctx->auth.verify_mode == SSL_CVERIFY_REQUIRE) {
        ca_list = SSL_CTX_get_client_CA_list(ctx);

        if (sk_X509_NAME_num(ca_list) == 0) {
            ap_log_error(APLOG_MARK, APLOG_WARNING, 0, s, APLOGNO(01897)
                         "Init: Oops, you want to request client "
                         "authentication, but no CAs are known for "
                         "verification!?  [Hint: SSLCACertificate*]");
        }
    }

    return APR_SUCCESS;
}

static apr_status_t ssl_init_ctx_cipher_suite(server_rec *s,
                                              apr_pool_t *p,
                                              apr_pool_t *ptemp,
                                              modssl_ctx_t *mctx)
{
    SSL_CTX *ctx = mctx->ssl_ctx;
    const char *suite;

    /*
     *  Configure SSL Cipher Suite. Always disable NULL and export ciphers,
     *  see also ssl_engine_config.c:ssl_cmd_SSLCipherSuite().
     *  OpenSSL's SSL_DEFAULT_CIPHER_LIST includes !aNULL:!eNULL from 0.9.8f,
     *  and !EXP from 0.9.8zf/1.0.1m/1.0.2a, so append them while we support
     *  earlier versions.
     */
    suite = mctx->auth.cipher_suite ? mctx->auth.cipher_suite :
            apr_pstrcat(ptemp, SSL_DEFAULT_CIPHER_LIST, ":!aNULL:!eNULL:!EXP",
                        NULL);

    ap_log_error(APLOG_MARK, APLOG_TRACE1, 0, s,
                 "Configuring permitted SSL ciphers [%s]",
                 suite);

    if (!SSL_CTX_set_cipher_list(ctx, suite)) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01898)
                "Unable to configure permitted SSL ciphers");
        ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
        return ssl_die(s);
    }

    return APR_SUCCESS;
}

static apr_status_t ssl_init_ctx_crl(server_rec *s,
                                     apr_pool_t *p,
                                     apr_pool_t *ptemp,
                                     modssl_ctx_t *mctx)
{
    X509_STORE *store = SSL_CTX_get_cert_store(mctx->ssl_ctx);
    unsigned long crlflags = 0;
    char *cfgp = mctx->pkp ? "SSLProxy" : "SSL";
    int crl_check_mode;

    if (mctx->crl_check_mask == UNSET) {
        mctx->crl_check_mask = SSL_CRLCHECK_NONE;
    }
    crl_check_mode = mctx->crl_check_mask & ~SSL_CRLCHECK_FLAGS;

    /*
     * Configure Certificate Revocation List (CRL) Details
     */

    if (!(mctx->crl_file || mctx->crl_path)) {
        if (crl_check_mode == SSL_CRLCHECK_LEAF ||
            crl_check_mode == SSL_CRLCHECK_CHAIN) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01899)
                         "Host %s: CRL checking has been enabled, but "
                         "neither %sCARevocationFile nor %sCARevocationPath "
                         "is configured", mctx->sc->vhost_id, cfgp, cfgp);
            return ssl_die(s);
        }
        return APR_SUCCESS;
    }

    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(01900)
                 "Configuring certificate revocation facility");

    if (!store || !X509_STORE_load_locations(store, mctx->crl_file,
                                             mctx->crl_path)) {
        ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(01901)
                     "Host %s: unable to configure X.509 CRL storage "
                     "for certificate revocation", mctx->sc->vhost_id);
        ssl_log_ssl_error(SSLLOG_MARK, APLOG_EMERG, s);
        return ssl_die(s);
    }

    switch (crl_check_mode) {
       case SSL_CRLCHECK_LEAF:
           crlflags = X509_V_FLAG_CRL_CHECK;
           break;
       case SSL_CRLCHECK_CHAIN:
           crlflags = X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL;
           break;
       default:
           crlflags = 0;
    }

    if (crlflags) {
        X509_STORE_set_flags(store, crlflags);
    } else {
        ap_log_error(APLOG_MARK, APLOG_WARNING, 0, s, APLOGNO(01902)
                     "Host %s: X.509 CRL storage locations configured, "
                     "but CRL checking (%sCARevocationCheck) is not "
                     "enabled", mctx->sc->vhost_id, cfgp);
    }

    return APR_SUCCESS;
}

/*
 * Read a file that optionally contains the server certificate in PEM
 * format, possibly followed by a sequence of CA certificates that
 * should be sent to the peer in the SSL Certificate message.
 */
static int use_certificate_chain(
    SSL_CTX *ctx, char *file, int skipfirst, pem_password_cb *cb)
{
    BIO *bio;
    X509 *x509;
    unsigned long err;
    int n;

    if ((bio = BIO_new(BIO_s_file())) == NULL)
        return -1;
    if (BIO_read_filename(bio, file) <= 0) {
        BIO_free(bio);
        return -1;
    }
    /* optionally skip a leading server certificate */
    if (skipfirst) {
        if ((x509 = PEM_read_bio_X509(bio, NULL, cb, NULL)) == NULL) {
            BIO_free(bio);
            return -1;
        }
        X509_free(x509);
    }
    /* free a perhaps already configured extra chain */
#ifdef OPENSSL_NO_SSL_INTERN
    SSL_CTX_clear_extra_chain_certs(ctx);
#else
    if (ctx->extra_certs != NULL) {
        sk_X509_pop_free((STACK_OF(X509) *)ctx->extra_certs, X509_free);
        ctx->extra_certs = NULL;
    }
#endif
    /* create new extra chain by loading the certs */
    n = 0;
    while ((x509 = PEM_read_bio_X509(bio, NULL, cb, NULL)) != NULL) {
        if (!SSL_CTX_add_extra_chain_cert(ctx, x509)) {
            X509_free(x509);
            BIO_free(bio);
            return -1;
        }
        n++;
    }
    /* Make sure that only the error is just an EOF */
    if ((err = ERR_peek_error()) > 0) {
        if (!(   ERR_GET_LIB(err) == ERR_LIB_PEM
              && ERR_GET_REASON(err) == PEM_R_NO_START_LINE)) {
            BIO_free(bio);
            return -1;
        }
        while (ERR_get_error() > 0) ;