source: mod_gnutls/src/gnutls_hooks.c @ 2d0f6cf

/**
 *  Copyright 2004-2005 Paul Querna
 *  Copyright 2008 Nikos Mavrogiannopoulos
 *  Copyright 2011 Dash Shendy
 *
 *  Licensed 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.
 *
 */

#include "mod_gnutls.h"
#include "http_vhost.h"
#include "ap_mpm.h"


#if !USING_2_1_RECENT
extern server_rec *ap_server_conf;
#endif

#if MOD_GNUTLS_DEBUG
static apr_file_t *debug_log_fp;
#endif

static gnutls_datum_t session_ticket_key = {NULL, 0};

static int mgs_cert_verify(request_rec * r, mgs_handle_t * ctxt);
/* use side==0 for server and side==1 for client */
static void mgs_add_common_cert_vars(request_rec * r, gnutls_x509_crt_t cert, int side);
static void mgs_add_common_pgpcert_vars(request_rec * r, gnutls_openpgp_crt_t cert, int side);

/* Pool Cleanup Function */
apr_status_t mgs_cleanup_pre_config(void *data) {
        /* Free all session data */
    gnutls_free(session_ticket_key.data);
    session_ticket_key.data = NULL;
    session_ticket_key.size = 0;
        /* Deinitialize GnuTLS Library */
    gnutls_global_deinit();
    return APR_SUCCESS;
}

/* Logging Function for Maintainers */
#if MOD_GNUTLS_DEBUG
static void gnutls_debug_log_all(int level, const char *str) {
    apr_file_printf(debug_log_fp, "<%d> %s\n", level, str);
}
#define _gnutls_log apr_file_printf
#else
#define _gnutls_log(...)
#endif

/* Pre-Configuration HOOK: Runs First */
int mgs_hook_pre_config(apr_pool_t * pconf, apr_pool_t * plog, apr_pool_t * ptemp) {

/* Maintainer Logging */
#if MOD_GNUTLS_DEBUG
    apr_file_open(&debug_log_fp, "/tmp/gnutls_debug", APR_APPEND | APR_WRITE | APR_CREATE, APR_OS_DEFAULT, pconf);
    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    gnutls_global_set_log_level(9);
    gnutls_global_set_log_function(gnutls_debug_log_all);
    _gnutls_log(debug_log_fp, "gnutls: %s\n", gnutls_check_version(NULL));
#endif    

    int ret;
        const char * req_GnuTLSVer = "2.12.0";

        /* Check for required GnuTLS Library Version */
    if (gnutls_check_version(req_GnuTLSVer) == NULL) {
                ap_log_perror(APLOG_MARK, APLOG_DEBUG, 0, plog, "gnutls_check_version() failed. Required: "
                                        "gnutls-%s Found: gnutls-%s\n", LIBGNUTLS_VERSION, gnutls_check_version(NULL));
                exit(-1);
    }

        /* Initialize GnuTLS Library */
    ret = gnutls_global_init();
    if (ret < 0) {
                ap_log_perror(APLOG_MARK, APLOG_DEBUG, 0, plog, "gnutls_global_init: %s\n", gnutls_strerror(ret));
                exit(-1);
    }

        /* Generate a Session Key */
    ret = gnutls_session_ticket_key_generate(&session_ticket_key);
    if (ret < 0) {
                ap_log_perror(APLOG_MARK, APLOG_DEBUG, 0, plog, "gnutls_session_ticket_key_generate: %s\n", gnutls_strerror(ret));
                exit(-1);
    }

        /* Register a pool clean-up function */
    apr_pool_cleanup_register(pconf, NULL, mgs_cleanup_pre_config, apr_pool_cleanup_null);\

    return OK;
}

static int mgs_select_virtual_server_cb(gnutls_session_t session) {

    mgs_handle_t *ctxt = NULL;
    mgs_srvconf_rec *tsc = NULL;
    int ret = 0;

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);

    ctxt = gnutls_transport_get_ptr(session);

    /* find the virtual server */
    tsc = mgs_find_sni_server(session);

    if (tsc == NULL) {
        // No TLS vhost configured!
                return GNUTLS_E_NO_CERTIFICATE_FOUND;
        } else {
        // Found a TLS vhost
        ctxt->sc = tsc;
        }

    gnutls_certificate_server_set_request(session, ctxt->sc->client_verify_mode);

    /* Set Anon credentials */
    gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, ctxt->sc->certs);
        /* Set x509 credentials */
    gnutls_credentials_set(session, GNUTLS_CRD_ANON, ctxt->sc->anon_creds);

#ifdef ENABLE_SRP
        /* Set SRP credentials */
    if (ctxt->sc->srp_tpasswd_conf_file != NULL && ctxt->sc->srp_tpasswd_file != NULL) {
        gnutls_credentials_set(session, GNUTLS_CRD_SRP, ctxt->sc->srp_creds);
    }
#endif

    /* update the priorities - to avoid negotiating a ciphersuite that is not
     * enabled on this virtual server. Note that here we ignore the version
     * negotiation.
     */

        ret = gnutls_priority_set_direct(session, "NORMAL", NULL);
    //ret = gnutls_priority_set(session, ctxt->sc->priorities);
    /* actually it shouldn't fail since we have checked at startup */
    return ret;

}

static int cert_retrieve_fn(gnutls_session_t session, 
                                                        const gnutls_datum_t * req_ca_rdn, int nreqs, 
                                                        const gnutls_pk_algorithm_t * pk_algos, int pk_algos_length, 
                                                        gnutls_retr2_st *ret) {
    
    
        _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);

        mgs_handle_t *ctxt = gnutls_transport_get_ptr(session);

    if (session == NULL) {
                // ERROR INVALID SESSION
                ret->ncerts = 0;
                ret->deinit_all = 1;
        return -1;
        } else if (gnutls_certificate_type_get(session) == GNUTLS_CRT_X509) {
                // X509 CERTIFICATE
                ret->cert_type = GNUTLS_CRT_X509;
                ret->key_type = GNUTLS_PRIVKEY_X509;
        ret->ncerts = ctxt->sc->certs_x509_chain_num;
        ret->deinit_all = 0;
        ret->cert.x509 = ctxt->sc->certs_x509_chain;
        ret->key.x509 = ctxt->sc->privkey_x509;
        return 0;
    } else if (gnutls_certificate_type_get(session) == GNUTLS_CRT_OPENPGP) {
                // OPENPGP CERTIFICATE
                ret->cert_type = GNUTLS_CRT_OPENPGP;
                ret->key_type = GNUTLS_PRIVKEY_OPENPGP;        
        ret->ncerts = 1;
        ret->deinit_all = 0;
        ret->cert.pgp = ctxt->sc->cert_pgp;
        ret->key.pgp = ctxt->sc->privkey_pgp;
        return 0;
    } else {
                // UNKNOWN CERTIFICATE
                ret->ncerts = 0;
                ret->deinit_all = 1;
            return -1;
        }
}

/* 2048-bit group parameters from SRP specification */
const char static_dh_params[] = "-----BEGIN DH PARAMETERS-----\n"
        "MIIBBwKCAQCsa9tBMkqam/Fm3l4TiVgvr3K2ZRmH7gf8MZKUPbVgUKNzKcu0oJnt\n"
        "gZPgdXdnoT3VIxKrSwMxDc1/SKnaBP1Q6Ag5ae23Z7DPYJUXmhY6s2YaBfvV+qro\n"
        "KRipli8Lk7hV+XmT7Jde6qgNdArb9P90c1nQQdXDPqcdKB5EaxR3O8qXtDoj+4AW\n"
        "dr0gekNsZIHx0rkHhxdGGludMuaI+HdIVEUjtSSw1X1ep3onddLs+gMs+9v1L7N4\n"
        "YWAnkATleuavh05zA85TKZzMBBx7wwjYKlaY86jQw4JxrjX46dv7tpS1yAPYn3rk\n"
        "Nd4jbVJfVHWbZeNy/NaO8g+nER+eSv9zAgEC\n"
        "-----END DH PARAMETERS-----\n";

/* Read the common name or the alternative name of the certificate.
 * We only support a single name per certificate.
 *
 * Returns negative on error.
 */
static int read_crt_cn(server_rec * s, apr_pool_t * p, gnutls_x509_crt_t cert, char **cert_cn) {

    int rv = 0, i;
    size_t data_len;


    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    *cert_cn = NULL;

    data_len = 0;
    rv = gnutls_x509_crt_get_dn_by_oid(cert, GNUTLS_OID_X520_COMMON_NAME, 0, 0, NULL, &data_len);

    if (rv == GNUTLS_E_SHORT_MEMORY_BUFFER && data_len > 1) {
        *cert_cn = apr_palloc(p, data_len);
        rv = gnutls_x509_crt_get_dn_by_oid(cert,
                GNUTLS_OID_X520_COMMON_NAME,
                0, 0, *cert_cn,
                &data_len);
    } else { /* No CN return subject alternative name */
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                "No common name found in certificate for '%s:%d'. Looking for subject alternative name...",
                s->server_hostname, s->port);
        rv = 0;
        /* read subject alternative name */
        for (i = 0; !(rv < 0); i++) {
            data_len = 0;
            rv = gnutls_x509_crt_get_subject_alt_name(cert, i,
                    NULL,
                    &data_len,
                    NULL);

            if (rv == GNUTLS_E_SHORT_MEMORY_BUFFER
                    && data_len > 1) {
                /* FIXME: not very efficient. What if we have several alt names
                 * before DNSName?
                 */
                *cert_cn = apr_palloc(p, data_len + 1);

                rv = gnutls_x509_crt_get_subject_alt_name
                        (cert, i, *cert_cn, &data_len, NULL);
                (*cert_cn)[data_len] = 0;

                if (rv == GNUTLS_SAN_DNSNAME)
                    break;
            }
        }
    }

    return rv;
}

static int read_pgpcrt_cn(server_rec * s, apr_pool_t * p,
        gnutls_openpgp_crt_t cert, char **cert_cn) {
    int rv = 0;
    size_t data_len;


    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    *cert_cn = NULL;

    data_len = 0;
    rv = gnutls_openpgp_crt_get_name(cert, 0, NULL, &data_len);

    if (rv == GNUTLS_E_SHORT_MEMORY_BUFFER && data_len > 1) {
        *cert_cn = apr_palloc(p, data_len);
        rv = gnutls_openpgp_crt_get_name(cert, 0, *cert_cn,
                &data_len);
    } else { /* No CN return subject alternative name */
        ap_log_error(APLOG_MARK, APLOG_INFO, 0, s,
                "No name found in PGP certificate for '%s:%d'.",
                s->server_hostname, s->port);
    }

    return rv;
}

int mgs_hook_post_config(apr_pool_t * p, apr_pool_t * plog, apr_pool_t * ptemp, server_rec * base_server) {

    int rv;
    server_rec *s;
    gnutls_dh_params_t dh_params = NULL;
    mgs_srvconf_rec *sc;
    mgs_srvconf_rec *sc_base;
    void *data = NULL;
    const char *userdata_key = "mgs_init";

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);

    apr_pool_userdata_get(&data, userdata_key, base_server->process->pool);
    if (data == NULL) {
        apr_pool_userdata_set((const void *) 1, userdata_key, apr_pool_cleanup_null, base_server->process->pool);
    }


    s = base_server;
    sc_base = (mgs_srvconf_rec *) ap_get_module_config(s->module_config, &gnutls_module);

    gnutls_dh_params_init(&dh_params);

    if (sc_base->dh_params == NULL) {
        gnutls_datum_t pdata = {
            (void *) static_dh_params,
            sizeof(static_dh_params)
        };
        rv = gnutls_dh_params_import_pkcs3(dh_params, &pdata, GNUTLS_X509_FMT_PEM);       
        /* Generate DH Params 
        int dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH,
                GNUTLS_SEC_PARAM_NORMAL);
        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, s,
            "GnuTLS: Generating DH Params of %i bits.  "
            "To avoid this use GnuTLSDHFile to specify DH Params for this host",
            dh_bits);                
#if MOD_GNUTLS_DEBUG
            ap_log_error(APLOG_MARK, APLOG_INFO, 0, s,
                    "GnuTLS: Generated DH Params of %i bits",dh_bits);
#endif  
        rv = gnutls_dh_params_generate2 (dh_params,dh_bits);
        */
        if (rv < 0) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, s,
                    "GnuTLS: Unable to generate or load DH Params: (%d) %s",
                    rv, gnutls_strerror(rv));
            exit(rv);
        }               
    } else {
        dh_params = sc_base->dh_params;
    }

    rv = mgs_cache_post_config(p, s, sc_base);
    if (rv != 0) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP, rv, s,
                "GnuTLS: Post Config for GnuTLSCache Failed."
                " Shutting Down.");
        exit(-1);
    }

    for (s = base_server; s; s = s->next) {
        sc = (mgs_srvconf_rec *) ap_get_module_config(s->module_config, &gnutls_module);
        sc->cache_type = sc_base->cache_type;
        sc->cache_config = sc_base->cache_config;

        /* Check if the priorities have been set */
        if (sc->priorities == NULL && sc->enabled == GNUTLS_ENABLED_TRUE) {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, s,
                    "GnuTLS: Host '%s:%d' is missing the GnuTLSPriorities directive!",
                    s->server_hostname, s->port);
            exit(-1);
        }

        /* Check if DH params have been set per host */
        if (sc->dh_params != NULL) {
            gnutls_certificate_set_dh_params(sc->certs, sc->dh_params);
            gnutls_anon_set_server_dh_params(sc->anon_creds, sc->dh_params);        
        } else if (dh_params) {
            gnutls_certificate_set_dh_params(sc->certs, dh_params);
            gnutls_anon_set_server_dh_params(sc->anon_creds, dh_params);                    
        }

        gnutls_certificate_set_retrieve_function(sc->certs, cert_retrieve_fn);

#ifdef ENABLE_SRP
        if (sc->srp_tpasswd_conf_file != NULL
                && sc->srp_tpasswd_file != NULL) {
            rv = gnutls_srp_set_server_credentials_file
                    (sc->srp_creds, sc->srp_tpasswd_file,
                    sc->srp_tpasswd_conf_file);

            if (rv < 0 && sc->enabled == GNUTLS_ENABLED_TRUE) {
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0,
                        s,
                        "[GnuTLS] - Host '%s:%d' is missing a "
                        "SRP password or conf File!",
                        s->server_hostname, s->port);
                exit(-1);
            }
        }
#endif

        if ((sc->certs_x509_chain == NULL || sc->certs_x509_chain_num < 1) &&
            sc->cert_pgp == NULL && sc->enabled == GNUTLS_ENABLED_TRUE) {
                        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, s, 
                                                "[GnuTLS] - Host '%s:%d' is missing a Certificate File!", 
                                                s->server_hostname, s->port);
            exit(-1);
        }

        if (sc->enabled == GNUTLS_ENABLED_TRUE &&
            ((sc->certs_x509_chain != NULL && sc->certs_x509_chain_num > 0 && sc->privkey_x509 == NULL) ||
             (sc->cert_pgp != NULL && sc->privkey_pgp == NULL))) {
                        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, s, 
                                                "[GnuTLS] - Host '%s:%d' is missing a Private Key File!", 
                                                s->server_hostname, s->port);
            exit(-1);
        }

        if (sc->enabled == GNUTLS_ENABLED_TRUE) {
            rv = -1;
            if (sc->certs_x509_chain_num > 0) {
                rv = read_crt_cn(s, p, sc->certs_x509_chain[0], &sc->cert_cn);
            }
            if (rv < 0 && sc->cert_pgp != NULL) { 
                rv = read_pgpcrt_cn(s, p, sc->cert_pgp, &sc->cert_cn);
                        }

            if (rv < 0) {
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, s, 
                                                        "[GnuTLS] - Cannot find a certificate for host '%s:%d'!", 
                                                        s->server_hostname, s->port);
                sc->cert_cn = NULL;
                continue;
            }
        }
    }


    ap_add_version_component(p, "mod_gnutls/" MOD_GNUTLS_VERSION);

    return OK;
}

void mgs_hook_child_init(apr_pool_t * p, server_rec * s) {
    apr_status_t rv = APR_SUCCESS;
    mgs_srvconf_rec *sc = ap_get_module_config(s->module_config,
            &gnutls_module);

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    if (sc->cache_type != mgs_cache_none) {
        rv = mgs_cache_child_init(p, s, sc);
        if (rv != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s,
                    "[GnuTLS] - Failed to run Cache Init");
        }
    }
    /* Block SIGPIPE Signals */
    rv = apr_signal_block(SIGPIPE); 
    if(rv != APR_SUCCESS) {
        /* error sending output */
        ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s,
                "GnuTLS: Error Blocking SIGPIPE Signal!");        
    }    
}

const char *mgs_hook_http_scheme(const request_rec * r) {
    mgs_srvconf_rec *sc;

    if (r == NULL)
        return NULL;

    sc = (mgs_srvconf_rec *) ap_get_module_config(r->
            server->module_config,
            &gnutls_module);

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    if (sc->enabled == GNUTLS_ENABLED_FALSE) {
        return NULL;
    }

    return "https";
}

apr_port_t mgs_hook_default_port(const request_rec * r) {
    mgs_srvconf_rec *sc;

    if (r == NULL)
        return 0;

    sc = (mgs_srvconf_rec *) ap_get_module_config(r->
            server->module_config,
            &gnutls_module);

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    if (sc->enabled == GNUTLS_ENABLED_FALSE) {
        return 0;
    }

    return 443;
}

#define MAX_HOST_LEN 255

#if USING_2_1_RECENT

typedef struct {
    mgs_handle_t *ctxt;
    mgs_srvconf_rec *sc;
    const char *sni_name;
} vhost_cb_rec;

/**
 * Matches the current vhost's ServerAlias directives
 *
 * @param x vhost callback record
 * @param s server record
 * @return true if a match, false otherwise
 *
 */
int check_server_aliases(vhost_cb_rec *x, server_rec * s, mgs_srvconf_rec *tsc) {
        apr_array_header_t *names;
        int i,rv = 0;
        char ** name;

        /* Check ServerName First! */
        if(apr_strnatcasecmp(x->sni_name, s->server_hostname) == 0) {
                // We have a match, save this server configuration
                x->sc = tsc;
                rv = 1;
        /* Check any ServerAlias directives */
        } else if(s->names->nelts) {
                names = s->names;
                name = (char **)names->elts;
                for (i = 0; i < names->nelts; ++i) {
                        if (!name[i]) { continue; } 
                                if (apr_strnatcasecmp(x->sni_name, name[i]) == 0) { 
                                        // We have a match, save this server configuration
                                        x->sc = tsc;
                                        rv = 1;
                        }                       
                }
        /* Wild any ServerAlias Directives */
        } else if(s->wild_names->nelts) {
                names = s->wild_names;
        name = (char **)names->elts;
                for (i = 0; i < names->nelts; ++i) {
                        if (!name[i]) { continue; }
                                if(apr_fnmatch(name[i], x->sni_name , 
                                                                APR_FNM_CASE_BLIND|
                                                                APR_FNM_PERIOD|
                                                                APR_FNM_PATHNAME|
                                                                APR_FNM_NOESCAPE) == APR_SUCCESS) { 
                                x->sc = tsc;
                                rv = 1; 
                        }
                }
        }
        return rv;
}

static int vhost_cb(void *baton, conn_rec * conn, server_rec * s) {
    mgs_srvconf_rec *tsc;
    vhost_cb_rec *x = baton;
    
    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    tsc = (mgs_srvconf_rec *) ap_get_module_config(s->module_config,
            &gnutls_module);

    if (tsc->enabled != GNUTLS_ENABLED_TRUE || tsc->cert_cn == NULL) {
        return 0;
    }
   
        int ret = gnutls_x509_crt_check_hostname(tsc->certs_x509_chain[0], s->server_hostname);
    if (0 == ret)
        ap_log_error(APLOG_MARK, APLOG_INFO, 0, s,
                     "GnuTLS: Error checking certificate for hostname "
                     "'%s'", s->server_hostname);
        return check_server_aliases(x, s, tsc);
}
#endif

mgs_srvconf_rec *mgs_find_sni_server(gnutls_session_t session) {
    int rv;
    unsigned int sni_type;
    size_t data_len = MAX_HOST_LEN;
    char sni_name[MAX_HOST_LEN];
    mgs_handle_t *ctxt;
#if USING_2_1_RECENT
    vhost_cb_rec cbx;
#else
    server_rec *s;
    mgs_srvconf_rec *tsc;
#endif

    if (session == NULL)
        return NULL;

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    ctxt = gnutls_transport_get_ptr(session);

    rv = gnutls_server_name_get(ctxt->session, sni_name,
            &data_len, &sni_type, 0);

    if (rv != 0) {
        return NULL;
    }

    if (sni_type != GNUTLS_NAME_DNS) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, 0,
                ctxt->c->base_server,
                "GnuTLS: Unknown type '%d' for SNI: "
                "'%s'", sni_type, sni_name);
        return NULL;
    }

    /**
     * Code in the Core already sets up the c->base_server as the base
     * for this IP/Port combo.  Trust that the core did the 'right' thing.
     */
#if USING_2_1_RECENT
    cbx.ctxt = ctxt;
    cbx.sc = NULL;
    cbx.sni_name = sni_name;

    rv = ap_vhost_iterate_given_conn(ctxt->c, vhost_cb, &cbx);
    if (rv == 1) {
        return cbx.sc;
    }
#else
    for (s = ap_server_conf; s; s = s->next) {

        tsc = (mgs_srvconf_rec *) ap_get_module_config(s->module_config, 
                &gnutls_module);
        
        if (tsc->enabled != GNUTLS_ENABLED_TRUE) { continue; }
                                
                                if(check_server_aliases(x, s, tsc)) {
                                        return tsc;
                                }
#endif
    return NULL;
}

static void create_gnutls_handle(conn_rec * c) {
    mgs_handle_t *ctxt;
    /* Get mod_gnutls Configuration Record */
    mgs_srvconf_rec *sc =(mgs_srvconf_rec *) 
            ap_get_module_config(c->base_server->module_config,&gnutls_module);

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    ctxt = apr_pcalloc(c->pool, sizeof (*ctxt));
    ctxt->c = c;
    ctxt->sc = sc;
    ctxt->status = 0;
    ctxt->input_rc = APR_SUCCESS;
    ctxt->input_bb = apr_brigade_create(c->pool, c->bucket_alloc);
    ctxt->input_cbuf.length = 0;
    ctxt->output_rc = APR_SUCCESS;
    ctxt->output_bb = apr_brigade_create(c->pool, c->bucket_alloc);
    ctxt->output_blen = 0;
    ctxt->output_length = 0;
    /* Initialize GnuTLS Library */
    gnutls_init(&ctxt->session, GNUTLS_SERVER);
    /* Initialize Session Tickets */
    if (session_ticket_key.data != NULL && ctxt->sc->tickets != 0) {
        gnutls_session_ticket_enable_server(ctxt->session,&session_ticket_key);
    }

    /* Set Default Priority */
        gnutls_priority_set_direct (ctxt->session, "NORMAL", NULL);
    /* Set Handshake function */
    gnutls_handshake_set_post_client_hello_function(ctxt->session,
            mgs_select_virtual_server_cb);
    /* Initialize Session Cache */
    mgs_cache_session_init(ctxt);
    
    /* Set this config for this connection */
    ap_set_module_config(c->conn_config, &gnutls_module, ctxt);
    /* Set pull, push & ptr functions */
    gnutls_transport_set_pull_function(ctxt->session,
            mgs_transport_read);
    gnutls_transport_set_push_function(ctxt->session,
            mgs_transport_write);
    gnutls_transport_set_ptr(ctxt->session, ctxt);
    /* Add IO filters */
    ctxt->input_filter = ap_add_input_filter(GNUTLS_INPUT_FILTER_NAME, 
            ctxt, NULL, c);
    ctxt->output_filter = ap_add_output_filter(GNUTLS_OUTPUT_FILTER_NAME, 
            ctxt, NULL, c);    
}

int mgs_hook_pre_connection(conn_rec * c, void *csd) {
    mgs_srvconf_rec *sc;

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);

    sc = (mgs_srvconf_rec *) ap_get_module_config(c->base_server->module_config,
            &gnutls_module);

    if (sc && (!sc->enabled || sc->proxy_enabled == GNUTLS_ENABLED_TRUE)) {
        return DECLINED;
    }

    create_gnutls_handle(c);
    return OK;
}

int mgs_hook_fixups(request_rec * r) {
    unsigned char sbuf[GNUTLS_MAX_SESSION_ID];
    char buf[AP_IOBUFSIZE];
    const char *tmp;
    size_t len;
    mgs_handle_t *ctxt;
    int rv = OK;

    if (r == NULL)
        return DECLINED;

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    apr_table_t *env = r->subprocess_env;

    ctxt =
            ap_get_module_config(r->connection->conn_config,
            &gnutls_module);

    if (!ctxt || ctxt->session == NULL) {
        return DECLINED;
    }

    apr_table_setn(env, "HTTPS", "on");

    apr_table_setn(env, "SSL_VERSION_LIBRARY",
            "GnuTLS/" LIBGNUTLS_VERSION);
    apr_table_setn(env, "SSL_VERSION_INTERFACE",
            "mod_gnutls/" MOD_GNUTLS_VERSION);

    apr_table_setn(env, "SSL_PROTOCOL",
            gnutls_protocol_get_name(gnutls_protocol_get_version
            (ctxt->session)));

    /* should have been called SSL_CIPHERSUITE instead */
    apr_table_setn(env, "SSL_CIPHER",
            gnutls_cipher_suite_get_name(gnutls_kx_get
            (ctxt->session),
            gnutls_cipher_get
            (ctxt->session),
            gnutls_mac_get
            (ctxt->session)));

    apr_table_setn(env, "SSL_COMPRESS_METHOD",
            gnutls_compression_get_name(gnutls_compression_get
            (ctxt->session)));

#ifdef ENABLE_SRP
    if (ctxt->sc->srp_tpasswd_conf_file != NULL && ctxt->sc->srp_tpasswd_file != NULL) {
        tmp = gnutls_srp_server_get_username(ctxt->session);
        apr_table_setn(env, "SSL_SRP_USER", (tmp != NULL) ? tmp : "");
    } else {
        apr_table_unset(env, "SSL_SRP_USER");
    }
#endif

    if (apr_table_get(env, "SSL_CLIENT_VERIFY") == NULL)
        apr_table_setn(env, "SSL_CLIENT_VERIFY", "NONE");

    unsigned int key_size =
            8 *
            gnutls_cipher_get_key_size(gnutls_cipher_get(ctxt->session));
    tmp = apr_psprintf(r->pool, "%u", key_size);

    apr_table_setn(env, "SSL_CIPHER_USEKEYSIZE", tmp);

    apr_table_setn(env, "SSL_CIPHER_ALGKEYSIZE", tmp);

    apr_table_setn(env, "SSL_CIPHER_EXPORT",
            (key_size <= 40) ? "true" : "false");

    len = sizeof (sbuf);
    gnutls_session_get_id(ctxt->session, sbuf, &len);
    tmp = mgs_session_id2sz(sbuf, len, buf, sizeof (buf));
    apr_table_setn(env, "SSL_SESSION_ID", apr_pstrdup(r->pool, tmp));

    if (gnutls_certificate_type_get(ctxt->session) == GNUTLS_CRT_X509) {
                mgs_add_common_cert_vars(r, ctxt->sc->certs_x509_chain[0], 0);
        } else if (gnutls_certificate_type_get(ctxt->session) == GNUTLS_CRT_OPENPGP) {
        mgs_add_common_pgpcert_vars(r, ctxt->sc->cert_pgp, 0);
        }

    return rv;
}

int mgs_hook_authz(request_rec * r) {
    int rv;
    mgs_handle_t *ctxt;
    mgs_dirconf_rec *dc;

    if (r == NULL)
        return DECLINED;

    dc = ap_get_module_config(r->per_dir_config, &gnutls_module);

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    ctxt =
            ap_get_module_config(r->connection->conn_config,
            &gnutls_module);

    if (!ctxt || ctxt->session == NULL) {
        return DECLINED;
    }

    if (dc->client_verify_mode == GNUTLS_CERT_IGNORE) {
        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                "GnuTLS: Directory set to Ignore Client Certificate!");
    } else {
        if (ctxt->sc->client_verify_mode < dc->client_verify_mode) {
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                    "GnuTLS: Attempting to rehandshake with peer. %d %d",
                    ctxt->sc->client_verify_mode,
                    dc->client_verify_mode);

            /* If we already have a client certificate, there's no point in
             * re-handshaking... */
            rv = mgs_cert_verify(r, ctxt);
            if (rv != DECLINED && rv != HTTP_FORBIDDEN)
                return rv;

            gnutls_certificate_server_set_request
                    (ctxt->session, dc->client_verify_mode);

            if (mgs_rehandshake(ctxt) != 0) {
                return HTTP_FORBIDDEN;
            }
        } else if (ctxt->sc->client_verify_mode ==
                GNUTLS_CERT_IGNORE) {
#if MOD_GNUTLS_DEBUG
            ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                    "GnuTLS: Peer is set to IGNORE");
#endif
            return DECLINED;
        }
        rv = mgs_cert_verify(r, ctxt);
        if (rv != DECLINED &&
                (rv != HTTP_FORBIDDEN ||
                dc->client_verify_mode == GNUTLS_CERT_REQUIRE)) {
            return rv;
        }
    }

    return DECLINED;
}

/* variables that are not sent by default:
 *
 * SSL_CLIENT_CERT      string  PEM-encoded client certificate
 * SSL_SERVER_CERT      string  PEM-encoded client certificate
 */

/* side is either 0 for SERVER or 1 for CLIENT
 */
#define MGS_SIDE ((side==0)?"SSL_SERVER":"SSL_CLIENT")

static void mgs_add_common_cert_vars(request_rec * r, gnutls_x509_crt_t cert, int side) {
    unsigned char sbuf[64]; /* buffer to hold serials */
    char buf[AP_IOBUFSIZE];
    const char *tmp;
    char *tmp2;
    size_t len;
    int ret, i;

    if (r == NULL)
        return;

    apr_table_t *env = r->subprocess_env;

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);

    len = sizeof (buf);
    gnutls_x509_crt_get_dn(cert, buf, &len);
    apr_table_setn(env, apr_pstrcat(r->pool, MGS_SIDE, "_S_DN", NULL),
            apr_pstrmemdup(r->pool, buf, len));

    len = sizeof (buf);
    gnutls_x509_crt_get_issuer_dn(cert, buf, &len);
    apr_table_setn(env, apr_pstrcat(r->pool, MGS_SIDE, "_I_DN", NULL),
            apr_pstrmemdup(r->pool, buf, len));

    len = sizeof (sbuf);
    gnutls_x509_crt_get_serial(cert, sbuf, &len);
    tmp = mgs_session_id2sz(sbuf, len, buf, sizeof (buf));
    apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_M_SERIAL", NULL),
            apr_pstrdup(r->pool, tmp));

    ret = gnutls_x509_crt_get_version(cert);
    if (ret > 0)
        apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_M_VERSION",
            NULL), apr_psprintf(r->pool,
            "%u", ret));

    apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_CERT_TYPE", NULL),
            "X.509");

    tmp =
            mgs_time2sz(gnutls_x509_crt_get_expiration_time
            (cert), buf, sizeof (buf));
    apr_table_setn(env, apr_pstrcat(r->pool, MGS_SIDE, "_V_END", NULL),
            apr_pstrdup(r->pool, tmp));

    tmp =
            mgs_time2sz(gnutls_x509_crt_get_activation_time
            (cert), buf, sizeof (buf));
    apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_V_START", NULL),
            apr_pstrdup(r->pool, tmp));

    ret = gnutls_x509_crt_get_signature_algorithm(cert);
    if (ret >= 0) {
        apr_table_setn(env,
                apr_pstrcat(r->pool, MGS_SIDE, "_A_SIG",
                NULL),
                gnutls_sign_algorithm_get_name(ret));
    }

    ret = gnutls_x509_crt_get_pk_algorithm(cert, NULL);
    if (ret >= 0) {
        apr_table_setn(env,
                apr_pstrcat(r->pool, MGS_SIDE, "_A_KEY",
                NULL),
                gnutls_pk_algorithm_get_name(ret));
    }

    /* export all the alternative names (DNS, RFC822 and URI) */
    for (i = 0; !(ret < 0); i++) {
        len = 0;
        ret = gnutls_x509_crt_get_subject_alt_name(cert, i,
                NULL, &len,
                NULL);

        if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER && len > 1) {
            tmp2 = apr_palloc(r->pool, len + 1);

            ret =
                    gnutls_x509_crt_get_subject_alt_name(cert, i,
                    tmp2,
                    &len,
                    NULL);
            tmp2[len] = 0;

            if (ret == GNUTLS_SAN_DNSNAME) {
                apr_table_setn(env,
                        apr_psprintf(r->pool,
                        "%s_S_AN%u",
                        MGS_SIDE, i),
                        apr_psprintf(r->pool,
                        "DNSNAME:%s",
                        tmp2));
            } else if (ret == GNUTLS_SAN_RFC822NAME) {
                apr_table_setn(env,
                        apr_psprintf(r->pool,
                        "%s_S_AN%u",
                        MGS_SIDE, i),
                        apr_psprintf(r->pool,
                        "RFC822NAME:%s",
                        tmp2));
            } else if (ret == GNUTLS_SAN_URI) {
                apr_table_setn(env,
                        apr_psprintf(r->pool,
                        "%s_S_AN%u",
                        MGS_SIDE, i),
                        apr_psprintf(r->pool,
                        "URI:%s",
                        tmp2));
            } else {
                apr_table_setn(env,
                        apr_psprintf(r->pool,
                        "%s_S_AN%u",
                        MGS_SIDE, i),
                        "UNSUPPORTED");
            }
        }
    }
}

static void mgs_add_common_pgpcert_vars(request_rec * r, gnutls_openpgp_crt_t cert, int side) {

        unsigned char sbuf[64]; /* buffer to hold serials */
    char buf[AP_IOBUFSIZE];
    const char *tmp;
    size_t len;
    int ret;

    if (r == NULL)
        return;

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    apr_table_t *env = r->subprocess_env;

    len = sizeof (buf);
    gnutls_openpgp_crt_get_name(cert, 0, buf, &len);
    apr_table_setn(env, apr_pstrcat(r->pool, MGS_SIDE, "_NAME", NULL),
            apr_pstrmemdup(r->pool, buf, len));

    len = sizeof (sbuf);
    gnutls_openpgp_crt_get_fingerprint(cert, sbuf, &len);
    tmp = mgs_session_id2sz(sbuf, len, buf, sizeof (buf));
    apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_FINGERPRINT",
            NULL), apr_pstrdup(r->pool, tmp));

    ret = gnutls_openpgp_crt_get_version(cert);
    if (ret > 0)
        apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_M_VERSION",
            NULL), apr_psprintf(r->pool,
            "%u", ret));

    apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_CERT_TYPE", NULL),
            "OPENPGP");

    tmp =
            mgs_time2sz(gnutls_openpgp_crt_get_expiration_time
            (cert), buf, sizeof (buf));
    apr_table_setn(env, apr_pstrcat(r->pool, MGS_SIDE, "_V_END", NULL),
            apr_pstrdup(r->pool, tmp));

    tmp =
            mgs_time2sz(gnutls_openpgp_crt_get_creation_time
            (cert), buf, sizeof (buf));
    apr_table_setn(env,
            apr_pstrcat(r->pool, MGS_SIDE, "_V_START", NULL),
            apr_pstrdup(r->pool, tmp));

    ret = gnutls_openpgp_crt_get_pk_algorithm(cert, NULL);
    if (ret >= 0) {
        apr_table_setn(env,
                apr_pstrcat(r->pool, MGS_SIDE, "_A_KEY",
                NULL),
                gnutls_pk_algorithm_get_name(ret));
    }

}

/* TODO: Allow client sending a X.509 certificate chain */
static int mgs_cert_verify(request_rec * r, mgs_handle_t * ctxt) {
    const gnutls_datum_t *cert_list;
    unsigned int cert_list_size, status;
    int rv = GNUTLS_E_NO_CERTIFICATE_FOUND, ret;
    unsigned int ch_size = 0;

    union {
        gnutls_x509_crt_t x509[MAX_CHAIN_SIZE];
        gnutls_openpgp_crt_t pgp;
    } cert;
    apr_time_t expiration_time, cur_time;

    if (r == NULL || ctxt == NULL || ctxt->session == NULL)
        return HTTP_FORBIDDEN;

    _gnutls_log(debug_log_fp, "%s: %d\n", __func__, __LINE__);
    cert_list =
            gnutls_certificate_get_peers(ctxt->session, &cert_list_size);

    if (cert_list == NULL || cert_list_size == 0) {
        /* It is perfectly OK for a client not to send a certificate if on REQUEST mode
         */
        if (ctxt->sc->client_verify_mode == GNUTLS_CERT_REQUEST)
            return OK;

        /* no certificate provided by the client, but one was required. */
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Failed to Verify Peer: "
                "Client did not submit a certificate");
        return HTTP_FORBIDDEN;
    }

    if (gnutls_certificate_type_get(ctxt->session) == GNUTLS_CRT_X509) {
        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                "GnuTLS: A Chain of %d certificate(s) was provided for validation",
                cert_list_size);

        for (ch_size = 0; ch_size < cert_list_size; ch_size++) {
            gnutls_x509_crt_init(&cert.x509[ch_size]);
            rv = gnutls_x509_crt_import(cert.x509[ch_size],
                    &cert_list[ch_size],
                    GNUTLS_X509_FMT_DER);
            // When failure to import, leave the loop
            if (rv != GNUTLS_E_SUCCESS) {
                if (ch_size < 1) {
                    ap_log_rerror(APLOG_MARK,
                            APLOG_INFO, 0, r,
                            "GnuTLS: Failed to Verify Peer: "
                            "Failed to import peer certificates.");
                    ret = HTTP_FORBIDDEN;
                    goto exit;
                }
                ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                        "GnuTLS: Failed to import some peer certificates. Using %d certificates",
                        ch_size);
                rv = GNUTLS_E_SUCCESS;
                break;
            }
        }
    } else if (gnutls_certificate_type_get(ctxt->session) ==
            GNUTLS_CRT_OPENPGP) {
        if (cert_list_size > 1) {
            ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                    "GnuTLS: Failed to Verify Peer: "
                    "Chained Client Certificates are not supported.");
            return HTTP_FORBIDDEN;
        }

        gnutls_openpgp_crt_init(&cert.pgp);
        rv = gnutls_openpgp_crt_import(cert.pgp, &cert_list[0],
                GNUTLS_OPENPGP_FMT_RAW);

    } else
        return HTTP_FORBIDDEN;

    if (rv < 0) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Failed to Verify Peer: "
                "Failed to import peer certificates.");
        ret = HTTP_FORBIDDEN;
        goto exit;
    }

    if (gnutls_certificate_type_get(ctxt->session) == GNUTLS_CRT_X509) {
        apr_time_ansi_put(&expiration_time,
                gnutls_x509_crt_get_expiration_time
                (cert.x509[0]));

        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                "GnuTLS: Verifying list of  %d certificate(s)",
                ch_size);
        rv = gnutls_x509_crt_list_verify(cert.x509, ch_size,
                ctxt->sc->ca_list,
                ctxt->sc->ca_list_size,
                NULL, 0, 0, &status);
    } else {
        apr_time_ansi_put(&expiration_time,
                gnutls_openpgp_crt_get_expiration_time
                (cert.pgp));

        rv = gnutls_openpgp_crt_verify_ring(cert.pgp,
                ctxt->sc->pgp_list, 0,
                &status);
    }

    if (rv < 0) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Failed to Verify Peer certificate: (%d) %s",
                rv, gnutls_strerror(rv));
        if (rv == GNUTLS_E_NO_CERTIFICATE_FOUND)
            ap_log_rerror(APLOG_MARK, APLOG_EMERG, 0, r,
                "GnuTLS: No certificate was found for verification. Did you set the GnuTLSX509CAFile or GnuTLSPGPKeyringFile directives?");
        ret = HTTP_FORBIDDEN;
        goto exit;
    }

    /* TODO: X509 CRL Verification. */
    /* May add later if anyone needs it.
     */
    /* ret = gnutls_x509_crt_check_revocation(crt, crl_list, crl_list_size); */

    cur_time = apr_time_now();

    if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Could not find Signer for Peer Certificate");
    }

    if (status & GNUTLS_CERT_SIGNER_NOT_CA) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Peer's Certificate signer is not a CA");
    }

    if (status & GNUTLS_CERT_INSECURE_ALGORITHM) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Peer's Certificate is using insecure algorithms");
    }

    if (status & GNUTLS_CERT_EXPIRED
            || status & GNUTLS_CERT_NOT_ACTIVATED) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Peer's Certificate signer is expired or not yet activated");
    }

    if (status & GNUTLS_CERT_INVALID) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Peer Certificate is invalid.");
    } else if (status & GNUTLS_CERT_REVOKED) {
        ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                "GnuTLS: Peer Certificate is revoked.");
    }

    if (gnutls_certificate_type_get(ctxt->session) == GNUTLS_CRT_X509)
        mgs_add_common_cert_vars(r, cert.x509[0], 1);
    else if (gnutls_certificate_type_get(ctxt->session) ==
            GNUTLS_CRT_OPENPGP)
        mgs_add_common_pgpcert_vars(r, cert.pgp, 1);

    {
        /* days remaining */
        unsigned long remain =
                (apr_time_sec(expiration_time) -
                apr_time_sec(cur_time)) / 86400;
        apr_table_setn(r->subprocess_env, "SSL_CLIENT_V_REMAIN",
                apr_psprintf(r->pool, "%lu", remain));
    }

    if (status == 0) {
        apr_table_setn(r->subprocess_env, "SSL_CLIENT_VERIFY",
                "SUCCESS");
        ret = OK;
    } else {
        apr_table_setn(r->subprocess_env, "SSL_CLIENT_VERIFY",
                "FAILED");
        if (ctxt->sc->client_verify_mode == GNUTLS_CERT_REQUEST)
            ret = OK;
        else
            ret = HTTP_FORBIDDEN;
    }

exit:
    if (gnutls_certificate_type_get(ctxt->session) == GNUTLS_CRT_X509) {
        int i;
        for (i = 0; i < ch_size; i++) {
            gnutls_x509_crt_deinit(cert.x509[i]);
        }
    } else if (gnutls_certificate_type_get(ctxt->session) ==
            GNUTLS_CRT_OPENPGP)
        gnutls_openpgp_crt_deinit(cert.pgp);
    return ret;


}