tcptls.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007 - 2008, Digium, Inc.
 *
 * Luigi Rizzo (TCP and TLS server code)
 * Brett Bryant <brettbryant@gmail.com> (updated for client support)
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*!
 * \file
 * \brief Code to support TCP and TLS server/client
 *
 * \author Luigi Rizzo
 * \author Brett Bryant <brettbryant@gmail.com>
 */
 
#include "asterisk.h"
 
#include "asterisk/tcptls.h"            /* for ast_tls_config, ast_tcptls_se... */
#include "asterisk/iostream.h"          /* for DO_SSL, ast_iostream_close, a... */
 
#ifdef HAVE_FCNTL_H
#include <fcntl.h>                      /* for O_NONBLOCK */
#endif /* HAVE_FCNTL_H */
#include <netinet/in.h>                 /* for IPPROTO_TCP */
#ifdef DO_SSL
#include <openssl/asn1.h>               /* for ASN1_STRING_to_UTF8 */
#include <openssl/crypto.h>             /* for OPENSSL_free */
#include <openssl/err.h>                /* for ERR_print_errors_fp */
#include <openssl/opensslconf.h>        /* for OPENSSL_NO_SSL3_METHOD, OPENS... */
#include <openssl/opensslv.h>           /* for OPENSSL_VERSION_NUMBER */
#include <openssl/safestack.h>          /* for STACK_OF */
#include <openssl/ssl.h>                /* for SSL_CTX_free, SSL_get_error, ... */
#include <openssl/x509.h>               /* for X509_free, X509_NAME_ENTRY_ge... */
#include <openssl/x509v3.h>             /* for GENERAL_NAME, sk_GENERAL_NAME... */
#ifndef OPENSSL_NO_DH
#include <openssl/bio.h>                /* for BIO_free, BIO_new_file */
#include <openssl/dh.h>                 /* for DH_free */
#include <openssl/pem.h>                /* for PEM_read_bio_DHparams */
#endif /* OPENSSL_NO_DH */
#ifndef OPENSSL_NO_EC
#include <openssl/ec.h>                 /* for EC_KEY_free, EC_KEY_new_by_cu... */
#endif /* OPENSSL_NO_EC */
#endif /* DO_SSL */
#include <pthread.h>                    /* for pthread_cancel, pthread_join */
#include <signal.h>                     /* for pthread_kill, SIGURG */
#include <sys/socket.h>                 /* for setsockopt, shutdown, socket */
#include <sys/stat.h>                   /* for stat */
 
#include "asterisk/app.h"               /* for ast_read_textfile */
#include "asterisk/astobj2.h"           /* for ao2_ref, ao2_t_ref, ao2_alloc */
#include "asterisk/compat.h"            /* for strcasecmp */
#include "asterisk/config.h"            /* for ast_parse_arg, ast_parse_flag... */
#include "asterisk/io.h"                /* for ast_sd_get_fd */
#include "asterisk/lock.h"              /* for AST_PTHREADT_NULL */
#include "asterisk/logger.h"            /* for ast_log, LOG_ERROR, ast_debug */
#include "asterisk/netsock2.h"          /* for ast_sockaddr_copy, ast_sockad... */
#include "asterisk/pbx.h"               /* for ast_thread_inhibit_escalations */
#include "asterisk/utils.h"             /* for ast_true, ast_free, ast_wait_... */
 
static void session_instance_destructor(void *obj)
{
    struct ast_tcptls_session_instance *i = obj;
 
    if (i->stream) {
        ast_iostream_close(i->stream);
        i->stream = NULL;
    }
    ast_free(i->overflow_buf);
    ao2_cleanup(i->private_data);
}
 
#ifdef DO_SSL
static int check_tcptls_cert_name(ASN1_STRING *cert_str, const char *hostname, const char *desc)
{
    unsigned char *str;
    int ret;
 
    ret = ASN1_STRING_to_UTF8(&str, cert_str);
    if (ret < 0 || !str) {
        return -1;
    }
 
    if (strlen((char *) str) != ret) {
        ast_log(LOG_WARNING, "Invalid certificate %s length (contains NULL bytes?)\n", desc);
 
        ret = -1;
    } else if (!strcasecmp(hostname, (char *) str)) {
        ret = 0;
    } else {
        ret = -1;
    }
 
    ast_debug(3, "SSL %s compare s1='%s' s2='%s'\n", desc, hostname, str);
    OPENSSL_free(str);
 
    return ret;
}
 
static void write_openssl_error_to_log(void)
{
    FILE *fp;
    char *buffer;
    size_t length;
 
    fp = open_memstream(&buffer, &length);
    if (!fp) {
        return;
    }
 
    ERR_print_errors_fp(fp);
    fclose(fp);
 
    if (length) {
        ast_log(LOG_ERROR, "%.*s\n", (int) length, buffer);
    }
 
    ast_std_free(buffer);
}
#endif
 
/*! \brief
* creates a FILE * from the fd passed by the accept thread.
* This operation is potentially expensive (certificate verification),
* so we do it in the child thread context.
*
* \note must decrement ref count before returning NULL on error
*/
static void *handle_tcptls_connection(void *data)
{
    struct ast_tcptls_session_instance *tcptls_session = data;
#ifdef DO_SSL
    SSL *ssl;
#endif
 
    /* TCP/TLS connections are associated with external protocols, and
     * should not be allowed to execute 'dangerous' functions. This may
     * need to be pushed down into the individual protocol handlers, but
     * this seems like a good general policy.
     */
    if (ast_thread_inhibit_escalations()) {
        ast_log(LOG_ERROR, "Failed to inhibit privilege escalations; killing connection from peer '%s'\n",
            ast_sockaddr_stringify(&tcptls_session->remote_address));
        ast_tcptls_close_session_file(tcptls_session);
        ao2_ref(tcptls_session, -1);
        return NULL;
    }
 
    /*
     * TCP/TLS connections are associated with external protocols which can
     * be considered to be user interfaces (even for SIP messages), and
     * will not handle channel media.  This may need to be pushed down into
     * the individual protocol handlers, but this seems like a good start.
     */
    if (ast_thread_user_interface_set(1)) {
        ast_log(LOG_ERROR, "Failed to set user interface status; killing connection from peer '%s'\n",
            ast_sockaddr_stringify(&tcptls_session->remote_address));
        ast_tcptls_close_session_file(tcptls_session);
        ao2_ref(tcptls_session, -1);
        return NULL;
    }
 
    if (tcptls_session->parent->tls_cfg) {
#ifdef DO_SSL
        if (ast_iostream_start_tls(&tcptls_session->stream, tcptls_session->parent->tls_cfg->ssl_ctx, tcptls_session->client) < 0) {
            SSL *ssl = ast_iostream_get_ssl(tcptls_session->stream);
            if (ssl) {
                ast_log(LOG_ERROR, "Unable to set up ssl connection with peer '%s'\n",
                    ast_sockaddr_stringify(&tcptls_session->remote_address));
            }
            ast_tcptls_close_session_file(tcptls_session);
            ao2_ref(tcptls_session, -1);
            return NULL;
        }
 
        ssl = ast_iostream_get_ssl(tcptls_session->stream);
        if ((tcptls_session->client && !ast_test_flag(&tcptls_session->parent->tls_cfg->flags, AST_SSL_DONT_VERIFY_SERVER))
            || (!tcptls_session->client && ast_test_flag(&tcptls_session->parent->tls_cfg->flags, AST_SSL_VERIFY_CLIENT))) {
            X509 *peer;
            long res;
            peer = SSL_get_peer_certificate(ssl);
            if (!peer) {
                ast_log(LOG_ERROR, "No SSL certificate to verify from peer '%s'\n",
                    ast_sockaddr_stringify(&tcptls_session->remote_address));
                ast_tcptls_close_session_file(tcptls_session);
                ao2_ref(tcptls_session, -1);
                return NULL;
            }
 
            res = SSL_get_verify_result(ssl);
            if (res != X509_V_OK) {
                ast_log(LOG_ERROR, "Certificate from peer '%s' did not verify: %s\n",
                    ast_sockaddr_stringify(&tcptls_session->remote_address),
                    X509_verify_cert_error_string(res));
                X509_free(peer);
                ast_tcptls_close_session_file(tcptls_session);
                ao2_ref(tcptls_session, -1);
                return NULL;
            }
            if (!ast_test_flag(&tcptls_session->parent->tls_cfg->flags, AST_SSL_IGNORE_COMMON_NAME)) {
                ASN1_STRING *str;
                X509_NAME *name = X509_get_subject_name(peer);
                STACK_OF(GENERAL_NAME) *alt_names;
                int pos = -1;
                int found = 0;
 
                for (;;) {
                    /* Walk the certificate to check all available "Common Name" */
                    /* XXX Probably should do a gethostbyname on the hostname and compare that as well */
                    pos = X509_NAME_get_index_by_NID(name, NID_commonName, pos);
                    if (pos < 0) {
                        break;
                    }
                    str = X509_NAME_ENTRY_get_data(X509_NAME_get_entry(name, pos));
                    if (!check_tcptls_cert_name(str, tcptls_session->parent->hostname, "common name")) {
                        found = 1;
                        break;
                    }
                }
 
                if (!found) {
                    alt_names = X509_get_ext_d2i(peer, NID_subject_alt_name, NULL, NULL);
                    if (alt_names != NULL) {
                        int alt_names_count = sk_GENERAL_NAME_num(alt_names);
 
                        for (pos = 0; pos < alt_names_count; pos++) {
                            const GENERAL_NAME *alt_name = sk_GENERAL_NAME_value(alt_names, pos);
 
                            if (alt_name->type != GEN_DNS) {
                                continue;
                            }
 
                            if (!check_tcptls_cert_name(alt_name->d.dNSName, tcptls_session->parent->hostname, "alt name")) {
                                found = 1;
                                break;
                            }
                        }
 
                        sk_GENERAL_NAME_pop_free(alt_names, GENERAL_NAME_free);
                    }
                }
 
                if (!found) {
                    ast_log(LOG_ERROR, "Certificate common name from peer '%s' did not match (%s)\n",
                        ast_sockaddr_stringify(&tcptls_session->remote_address), tcptls_session->parent->hostname);
                    X509_free(peer);
                    ast_tcptls_close_session_file(tcptls_session);
                    ao2_ref(tcptls_session, -1);
                    return NULL;
                }
            }
            X509_free(peer);
        }
#else
        ast_log(LOG_ERROR, "TLS client failed: Asterisk is compiled without OpenSSL support. Install OpenSSL development headers and rebuild Asterisk after running ./configure\n");
        ast_tcptls_close_session_file(tcptls_session);
        ao2_ref(tcptls_session, -1);
        return NULL;
#endif /* DO_SSL */
    }
 
    if (tcptls_session->parent->worker_fn) {
        return tcptls_session->parent->worker_fn(tcptls_session);
    } else {
        return tcptls_session;
    }
}
 
void *ast_tcptls_server_root(void *data)
{
    struct ast_tcptls_session_args *desc = data;
    int fd;
    struct ast_sockaddr addr;
    struct ast_tcptls_session_instance *tcptls_session;
    pthread_t launched;
 
    for (;;) {
        int i;
 
        if (desc->periodic_fn) {
            desc->periodic_fn(desc);
        }
        i = ast_wait_for_input(desc->accept_fd, desc->poll_timeout);
        if (i <= 0) {
            /* Prevent tight loop from hogging CPU */
            usleep(1);
            continue;
        }
        fd = ast_accept(desc->accept_fd, &addr);
        if (fd < 0) {
            if (errno != EAGAIN
                && errno != EWOULDBLOCK
                && errno != EINTR
                && errno != ECONNABORTED) {
                ast_log(LOG_ERROR, "TCP/TLS accept failed: %s\n", strerror(errno));
                if (errno != EMFILE) {
                    break;
                }
            }
            /* Prevent tight loop from hogging CPU */
            usleep(1);
            continue;
        }
        tcptls_session = ao2_alloc(sizeof(*tcptls_session), session_instance_destructor);
        if (!tcptls_session) {
            close(fd);
            continue;
        }
 
        tcptls_session->overflow_buf = ast_str_create(128);
        if (!tcptls_session->overflow_buf) {
            ao2_ref(tcptls_session, -1);
            close(fd);
            continue;
        }
        ast_fd_clear_flags(fd, O_NONBLOCK);
 
        tcptls_session->stream = ast_iostream_from_fd(&fd);
        if (!tcptls_session->stream) {
            ao2_ref(tcptls_session, -1);
            close(fd);
            continue;
        }
 
        tcptls_session->parent = desc;
        ast_sockaddr_copy(&tcptls_session->remote_address, &addr);
 
        tcptls_session->client = 0;
 
        /* This thread is now the only place that controls the single ref to tcptls_session */
        if (ast_pthread_create_detached_background(&launched, NULL, handle_tcptls_connection, tcptls_session)) {
            ast_log(LOG_ERROR, "TCP/TLS unable to launch helper thread for peer '%s': %s\n",
                ast_sockaddr_stringify(&tcptls_session->remote_address),
                strerror(errno));
            ao2_ref(tcptls_session, -1);
        }
    }
 
    ast_log(LOG_ERROR, "TCP/TLS listener thread ended abnormally\n");
 
    /* Close the listener socket so Asterisk doesn't appear dead. */
    fd = desc->accept_fd;
    desc->accept_fd = -1;
    if (0 <= fd) {
        close(fd);
    }
    return NULL;
}
 
#ifdef DO_SSL
static void __ssl_setup_certs(struct ast_tls_config *cfg, const size_t cert_file_len, const char *key_type_extension, const char *key_type)
{
    char *cert_file = ast_strdupa(cfg->certfile);
 
    memcpy(cert_file + cert_file_len - 8, key_type_extension, 5);
    if (access(cert_file, F_OK) == 0) {
        if (SSL_CTX_use_certificate_chain_file(cfg->ssl_ctx, cert_file) == 0) {
            ast_log(LOG_WARNING, "TLS/SSL error loading public %s key (certificate) from <%s>.\n", key_type, cert_file);
            write_openssl_error_to_log();
        } else if (SSL_CTX_use_PrivateKey_file(cfg->ssl_ctx, cert_file, SSL_FILETYPE_PEM) == 0) {
            ast_log(LOG_WARNING, "TLS/SSL error loading private %s key from <%s>.\n", key_type, cert_file);
            write_openssl_error_to_log();
        } else if (SSL_CTX_check_private_key(cfg->ssl_ctx) == 0) {
            ast_log(LOG_WARNING, "TLS/SSL error matching private %s key and certificate in <%s>.\n", key_type, cert_file);
            write_openssl_error_to_log();
        }
    }
}
#endif
 
static int __ssl_setup(struct ast_tls_config *cfg, int client,
    int suppress_progress_msgs)
{
#ifndef DO_SSL
    if (cfg->enabled) {
        ast_log(LOG_ERROR, "TLS server failed: Asterisk is compiled without OpenSSL support. Install OpenSSL development headers and rebuild Asterisk after running ./configure\n");
        cfg->enabled = 0;
    }
    return 0;
#else
    int disable_ssl = 0;
    long ssl_opts = 0;
 
    if (!cfg->enabled) {
        return 0;
    }
 
    /* Get rid of an old SSL_CTX since we're about to
     * allocate a new one
     */
    if (cfg->ssl_ctx) {
        SSL_CTX_free(cfg->ssl_ctx);
        cfg->ssl_ctx = NULL;
    }
 
    if (client) {
#if !defined(OPENSSL_NO_SSL2) && (OPENSSL_VERSION_NUMBER < 0x10100000L)
        if (ast_test_flag(&cfg->flags, AST_SSL_SSLV2_CLIENT)) {
            ast_log(LOG_WARNING, "Usage of SSLv2 is discouraged due to known vulnerabilities. Please use 'tlsv1' or leave the TLS method unspecified!\n");
            cfg->ssl_ctx = SSL_CTX_new(SSLv2_client_method());
        } else
#endif
#if !defined(OPENSSL_NO_SSL3_METHOD) && !(defined(OPENSSL_API_COMPAT) && (OPENSSL_API_COMPAT >= 0x10100000L))
        if (ast_test_flag(&cfg->flags, AST_SSL_SSLV3_CLIENT)) {
            ast_log(LOG_WARNING, "Usage of SSLv3 is discouraged due to known vulnerabilities. Please use 'tlsv1' or leave the TLS method unspecified!\n");
            cfg->ssl_ctx = SSL_CTX_new(SSLv3_client_method());
        } else
#endif
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
        cfg->ssl_ctx = SSL_CTX_new(TLS_client_method());
#else
        if (ast_test_flag(&cfg->flags, AST_SSL_TLSV1_CLIENT)) {
            cfg->ssl_ctx = SSL_CTX_new(TLSv1_client_method());
        } else {
            disable_ssl = 1;
            cfg->ssl_ctx = SSL_CTX_new(SSLv23_client_method());
        }
#endif
    } else {
        disable_ssl = 1;
        cfg->ssl_ctx = SSL_CTX_new(SSLv23_server_method());
    }
 
    if (!cfg->ssl_ctx) {
        ast_debug(1, "Sorry, SSL_CTX_new call returned null...\n");
        cfg->enabled = 0;
        return 0;
    }
 
    /* Due to the POODLE vulnerability, completely disable
     * SSLv2 and SSLv3 if we are not explicitly told to use
     * them. SSLv23_*_method supports TLSv1+.
     */
    if (disable_ssl) {
        ssl_opts |= SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3;
    }
 
    if (ast_test_flag(&cfg->flags, AST_SSL_SERVER_CIPHER_ORDER)) {
        ssl_opts |= SSL_OP_CIPHER_SERVER_PREFERENCE;
    }
 
    if (ast_test_flag(&cfg->flags, AST_SSL_DISABLE_TLSV1)) {
        ssl_opts |= SSL_OP_NO_TLSv1;
    }
#if defined(SSL_OP_NO_TLSv1_1) && defined(SSL_OP_NO_TLSv1_2)
    if (ast_test_flag(&cfg->flags, AST_SSL_DISABLE_TLSV11)) {
        ssl_opts |= SSL_OP_NO_TLSv1_1;
    }
    if (ast_test_flag(&cfg->flags, AST_SSL_DISABLE_TLSV12)) {
        ssl_opts |= SSL_OP_NO_TLSv1_2;
    }
#else
    ast_log(LOG_WARNING, "Your version of OpenSSL leaves you potentially vulnerable "
            "to the SSL BEAST attack. Please upgrade to OpenSSL 1.0.1 or later\n");
#endif
 
    SSL_CTX_set_options(cfg->ssl_ctx, ssl_opts);
 
    SSL_CTX_set_verify(cfg->ssl_ctx,
        ast_test_flag(&cfg->flags, AST_SSL_VERIFY_CLIENT) ? SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT : SSL_VERIFY_NONE,
        NULL);
 
    if (!ast_strlen_zero(cfg->certfile)) {
        char *tmpprivate = ast_strlen_zero(cfg->pvtfile) ? cfg->certfile : cfg->pvtfile;
        if (SSL_CTX_use_certificate_chain_file(cfg->ssl_ctx, cfg->certfile) == 0) {
            if (!client) {
                /* Clients don't need a certificate, but if its setup we can use it */
                ast_log(LOG_ERROR, "TLS/SSL error loading cert file. <%s>\n", cfg->certfile);
                write_openssl_error_to_log();
                cfg->enabled = 0;
                SSL_CTX_free(cfg->ssl_ctx);
                cfg->ssl_ctx = NULL;
                return 0;
            }
        }
        if ((SSL_CTX_use_PrivateKey_file(cfg->ssl_ctx, tmpprivate, SSL_FILETYPE_PEM) == 0) || (SSL_CTX_check_private_key(cfg->ssl_ctx) == 0 )) {
            if (!client) {
                /* Clients don't need a private key, but if its setup we can use it */
                ast_log(LOG_ERROR, "TLS/SSL error loading private key file. <%s>\n", tmpprivate);
                write_openssl_error_to_log();
                cfg->enabled = 0;
                SSL_CTX_free(cfg->ssl_ctx);
                cfg->ssl_ctx = NULL;
                return 0;
            }
        }
        if (!client) {
            size_t certfile_len = strlen(cfg->certfile);
 
            /* expects a file name which contains _rsa. like asterisk_rsa.pem
             * ignores any 3-character file-extension like .pem, .cer, .crt
             */
            if (certfile_len >= 8 && !strncmp(cfg->certfile + certfile_len - 8, "_rsa.", 5)) {
                __ssl_setup_certs(cfg, certfile_len, "_ecc.", "ECC");
                __ssl_setup_certs(cfg, certfile_len, "_dsa.", "DSA");
            }
        }
    }
    if (!ast_strlen_zero(cfg->cipher)) {
        if (SSL_CTX_set_cipher_list(cfg->ssl_ctx, cfg->cipher) == 0 ) {
            if (!client) {
                ast_log(LOG_ERROR, "TLS/SSL cipher error <%s>\n", cfg->cipher);
                write_openssl_error_to_log();
                cfg->enabled = 0;
                SSL_CTX_free(cfg->ssl_ctx);
                cfg->ssl_ctx = NULL;
                return 0;
            }
        }
    }
    if (!ast_strlen_zero(cfg->cafile) || !ast_strlen_zero(cfg->capath)) {
        if (SSL_CTX_load_verify_locations(cfg->ssl_ctx, S_OR(cfg->cafile, NULL), S_OR(cfg->capath,NULL)) == 0) {
            ast_log(LOG_ERROR, "TLS/SSL CA file(%s)/path(%s) error\n", cfg->cafile, cfg->capath);
            write_openssl_error_to_log();
        }
    }
 
#ifndef OPENSSL_NO_DH
    if (!ast_strlen_zero(cfg->pvtfile)) {
        BIO *bio = BIO_new_file(cfg->pvtfile, "r");
        if (bio != NULL) {
            DH *dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
            if (dh != NULL) {
                if (SSL_CTX_set_tmp_dh(cfg->ssl_ctx, dh)) {
                    long options = SSL_OP_CIPHER_SERVER_PREFERENCE | SSL_OP_SINGLE_DH_USE | SSL_OP_SINGLE_ECDH_USE;
                    options = SSL_CTX_set_options(cfg->ssl_ctx, options);
                    if (!suppress_progress_msgs) {
                        ast_verb(2, "TLS/SSL DH initialized, PFS cipher-suites enabled\n");
                    }
                }
                DH_free(dh);
            }
            BIO_free(bio);
        }
    }
#endif
 
    #ifndef SSL_CTRL_SET_ECDH_AUTO
        #define SSL_CTRL_SET_ECDH_AUTO 94
    #endif
    /* SSL_CTX_set_ecdh_auto(cfg->ssl_ctx, on); requires OpenSSL 1.0.2 which wraps: */
    if (SSL_CTX_ctrl(cfg->ssl_ctx, SSL_CTRL_SET_ECDH_AUTO, 1, NULL)) {
        if (!suppress_progress_msgs) {
            ast_verb(2, "TLS/SSL ECDH initialized (automatic), faster PFS ciphers enabled\n");
        }
#if !defined(OPENSSL_NO_ECDH) && (OPENSSL_VERSION_NUMBER >= 0x10000000L) && (OPENSSL_VERSION_NUMBER < 0x10100000L)
    } else {
        /* enables AES-128 ciphers, to get AES-256 use NID_secp384r1 */
        EC_KEY *ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
        if (ecdh != NULL) {
            if (SSL_CTX_set_tmp_ecdh(cfg->ssl_ctx, ecdh)) {
                ast_verb(2, "TLS/SSL ECDH initialized (secp256r1), faster PFS cipher-suites enabled\n");
            }
            EC_KEY_free(ecdh);
        }
#endif
    }
 
    if (!suppress_progress_msgs) {
        ast_verb(2, "TLS/SSL certificate ok\n");    /* We should log which one that is ok. This message doesn't really make sense in production use */
    }
    return 1;
#endif
}
 
int ast_ssl_setup(struct ast_tls_config *cfg)
{
    return __ssl_setup(cfg, 0, 0);
}
 
void ast_ssl_teardown(struct ast_tls_config *cfg)
{
#ifdef DO_SSL
    if (cfg && cfg->ssl_ctx) {
        SSL_CTX_free(cfg->ssl_ctx);
        cfg->ssl_ctx = NULL;
    }
#endif
}
 
/*!
 * \internal
 * \brief Connect a socket
 *
 * Attempt to connect to a given address for up to 'timeout' milliseconds. A negative
 * timeout value equates to an infinite wait time.
 *
 * A -1 is returned on error, and an appropriate errno value is set based on the
 * type of error.
 *
 * \param sockfd The socket file descriptor
 * \param addr The address to connect to
 * \param timeout How long, in milliseconds, to attempt to connect
 *
 * \return 0 if successfully connected, -1 otherwise
 */
static int socket_connect(int sockfd, const struct ast_sockaddr *addr, int timeout)
{
    int optval = 0;
    socklen_t optlen = sizeof(int);
 
    errno = 0;
 
    if (ast_connect(sockfd, addr)) {
        int res;
 
        /*
         * A connect failure could mean things are still in progress.
         * If so wait for it to complete.
         */
 
        if (errno != EINPROGRESS) {
            return -1;
        }
 
        while ((res = ast_wait_for_output(sockfd, timeout)) != 1) {
            if (res == 0) {
                errno = ETIMEDOUT;
                return -1;
            }
 
            if (errno != EINTR) {
                return -1;
            }
        }
    }
 
    /* Check the status to ensure it actually connected successfully */
    if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) < 0) {
        return -1;
    }
 
    if (optval) {
        errno = optval;
        return -1;
    }
 
    return 0;
}
 
struct ast_tcptls_session_instance *ast_tcptls_client_start_timeout(
    struct ast_tcptls_session_instance *tcptls_session, int timeout)
{
    struct ast_tcptls_session_args *desc;
 
    if (!(desc = tcptls_session->parent)) {
        ao2_ref(tcptls_session, -1);
        return NULL;
    }
 
    if (socket_connect(desc->accept_fd, &desc->remote_address, timeout)) {
        if (!desc->suppress_connection_msgs) {
            ast_log(LOG_WARNING, "Unable to connect %s to %s: %s\n", desc->name,
                    ast_sockaddr_stringify(&desc->remote_address), strerror(errno));
        }
 
        ao2_ref(tcptls_session, -1);
        return NULL;
    }
 
    ast_fd_clear_flags(desc->accept_fd, O_NONBLOCK);
 
    if (desc->tls_cfg) {
        __ssl_setup(desc->tls_cfg, 1, desc->suppress_connection_msgs);
    }
 
    return handle_tcptls_connection(tcptls_session);
}
 
struct ast_tcptls_session_instance *ast_tcptls_client_start(struct ast_tcptls_session_instance *tcptls_session)
{
    return ast_tcptls_client_start_timeout(tcptls_session, -1);
}
 
struct ast_tcptls_session_instance *ast_tcptls_client_create(struct ast_tcptls_session_args *desc)
{
    int fd, x = 1;
    struct ast_tcptls_session_instance *tcptls_session = NULL;
 
    ast_assert(!desc->tls_cfg
            || ast_test_flag(&desc->tls_cfg->flags, AST_SSL_DONT_VERIFY_SERVER)
            || !ast_strlen_zero(desc->hostname));
 
    /* Do nothing if nothing has changed */
    if (!ast_sockaddr_cmp(&desc->old_address, &desc->remote_address)) {
        ast_debug(1, "Nothing changed in %s\n", desc->name);
        return NULL;
    }
 
    /* If we return early, there is no connection */
    ast_sockaddr_setnull(&desc->old_address);
 
    fd = desc->accept_fd = ast_socket_nonblock(ast_sockaddr_is_ipv6(&desc->remote_address) ?
                      AF_INET6 : AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (desc->accept_fd < 0) {
        ast_log(LOG_ERROR, "Unable to allocate socket for %s: %s\n",
            desc->name, strerror(errno));
        return NULL;
    }
 
    /* if a local address was specified, bind to it so the connection will
       originate from the desired address */
    if (!ast_sockaddr_isnull(&desc->local_address) &&
        !ast_sockaddr_is_any(&desc->local_address)) {
        setsockopt(desc->accept_fd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof(x));
        if (ast_bind(desc->accept_fd, &desc->local_address)) {
            ast_log(LOG_ERROR, "Unable to bind %s to %s: %s\n",
                desc->name,
                ast_sockaddr_stringify(&desc->local_address),
                strerror(errno));
            goto error;
        }
    }
 
    tcptls_session = ao2_alloc(sizeof(*tcptls_session), session_instance_destructor);
    if (!tcptls_session) {
        goto error;
    }
 
    tcptls_session->overflow_buf = ast_str_create(128);
    if (!tcptls_session->overflow_buf) {
        goto error;
    }
    tcptls_session->client = 1;
    tcptls_session->stream = ast_iostream_from_fd(&fd);
    if (!tcptls_session->stream) {
        goto error;
    }
 
    /* From here on out, the iostream owns the accept_fd and it will take
     * care of closing it when the iostream is closed */
 
    tcptls_session->parent = desc;
    tcptls_session->parent->worker_fn = NULL;
    ast_sockaddr_copy(&tcptls_session->remote_address,
              &desc->remote_address);
 
    /* Set current info */
    ast_sockaddr_copy(&desc->old_address, &desc->remote_address);
 
    if (!ast_strlen_zero(desc->hostname)) {
        if (ast_iostream_set_sni_hostname(tcptls_session->stream, desc->hostname) != 0) {
            ast_log(LOG_WARNING, "Unable to set SNI hostname '%s' on connection '%s'\n",
                desc->hostname, desc->name);
        }
    }
 
    return tcptls_session;
 
error:
    close(desc->accept_fd);
    desc->accept_fd = -1;
    ao2_cleanup(tcptls_session);
    return NULL;
}
 
void ast_tcptls_server_start(struct ast_tcptls_session_args *desc)
{
    int x = 1;
    int tls_changed = 0;
    int sd_socket;
 
    if (desc->tls_cfg) {
        char hash[41];
        char *str = NULL;
        struct stat st;
 
        /* Store the hashes of the TLS certificate etc. */
        if (stat(desc->tls_cfg->certfile, &st) || NULL == (str = ast_read_textfile(desc->tls_cfg->certfile))) {
            memset(hash, 0, 41);
        } else {
            ast_sha1_hash(hash, str);
        }
        ast_free(str);
        str = NULL;
        memcpy(desc->tls_cfg->certhash, hash, 41);
        if (stat(desc->tls_cfg->pvtfile, &st) || NULL == (str = ast_read_textfile(desc->tls_cfg->pvtfile))) {
            memset(hash, 0, 41);
        } else {
            ast_sha1_hash(hash, str);
        }
        ast_free(str);
        str = NULL;
        memcpy(desc->tls_cfg->pvthash, hash, 41);
        if (stat(desc->tls_cfg->cafile, &st) || NULL == (str = ast_read_textfile(desc->tls_cfg->cafile))) {
            memset(hash, 0, 41);
        } else {
            ast_sha1_hash(hash, str);
        }
        ast_free(str);
        str = NULL;
        memcpy(desc->tls_cfg->cahash, hash, 41);
 
        /* Check whether TLS configuration has changed */
        if (!desc->old_tls_cfg) { /* No previous configuration */
            tls_changed = 1;
            desc->old_tls_cfg = ast_calloc(1, sizeof(*desc->old_tls_cfg));
        } else if (memcmp(desc->tls_cfg->certhash, desc->old_tls_cfg->certhash, 41)) {
            tls_changed = 1;
        } else if (memcmp(desc->tls_cfg->pvthash, desc->old_tls_cfg->pvthash, 41)) {
            tls_changed = 1;
        } else if (strcmp(desc->tls_cfg->cipher, desc->old_tls_cfg->cipher)) {
            tls_changed = 1;
        } else if (memcmp(desc->tls_cfg->cahash, desc->old_tls_cfg->cahash, 41)) {
            tls_changed = 1;
        } else if (strcmp(desc->tls_cfg->capath, desc->old_tls_cfg->capath)) {
            tls_changed = 1;
        } else if (memcmp(&desc->tls_cfg->flags, &desc->old_tls_cfg->flags, sizeof(desc->tls_cfg->flags))) {
            tls_changed = 1;
        }
 
        if (tls_changed) {
            ast_debug(1, "Changed parameters for %s found\n", desc->name);
        }
    }
 
    /* Do nothing if nothing has changed */
    if (!tls_changed && !ast_sockaddr_cmp(&desc->old_address, &desc->local_address)) {
        ast_debug(1, "Nothing changed in %s\n", desc->name);
        return;
    }
 
    /* If we return early, there is no one listening */
    ast_sockaddr_setnull(&desc->old_address);
 
    /* Shutdown a running server if there is one */
    if (desc->master != AST_PTHREADT_NULL) {
        pthread_cancel(desc->master);
        pthread_kill(desc->master, SIGURG);
        pthread_join(desc->master, NULL);
    }
 
    sd_socket = ast_sd_get_fd(SOCK_STREAM, &desc->local_address);
 
    if (sd_socket != -1) {
        if (desc->accept_fd != sd_socket) {
            if (desc->accept_fd != -1) {
                close(desc->accept_fd);
            }
            desc->accept_fd = sd_socket;
        }
 
        goto systemd_socket_activation;
    }
 
    if (desc->accept_fd != -1) {
        close(desc->accept_fd);
        desc->accept_fd = -1;
    }
 
    /* If there's no new server, stop here */
    if (ast_sockaddr_isnull(&desc->local_address)) {
        ast_debug(2, "Server disabled:  %s\n", desc->name);
        return;
    }
 
    desc->accept_fd = ast_socket_nonblock(ast_sockaddr_is_ipv6(&desc->local_address) ?
                 AF_INET6 : AF_INET, SOCK_STREAM, 0);
    if (desc->accept_fd < 0) {
        ast_log(LOG_ERROR, "Unable to allocate socket for %s: %s\n", desc->name, strerror(errno));
        return;
    }
 
    setsockopt(desc->accept_fd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof(x));
    if (ast_bind(desc->accept_fd, &desc->local_address)) {
        ast_log(LOG_ERROR, "Unable to bind %s to %s: %s\n",
            desc->name,
            ast_sockaddr_stringify(&desc->local_address),
            strerror(errno));
        goto error;
    }
    if (listen(desc->accept_fd, 10)) {
        ast_log(LOG_ERROR, "Unable to listen for %s!\n", desc->name);
        goto error;
    }
 
systemd_socket_activation:
    if (ast_pthread_create_background(&desc->master, NULL, desc->accept_fn, desc)) {
        ast_log(LOG_ERROR, "Unable to launch thread for %s on %s: %s\n",
            desc->name,
            ast_sockaddr_stringify(&desc->local_address),
            strerror(errno));
        goto error;
    }
 
    /* Set current info */
    ast_sockaddr_copy(&desc->old_address, &desc->local_address);
    if (desc->old_tls_cfg) {
        ast_free(desc->old_tls_cfg->certfile);
        ast_free(desc->old_tls_cfg->pvtfile);
        ast_free(desc->old_tls_cfg->cipher);
        ast_free(desc->old_tls_cfg->cafile);
        ast_free(desc->old_tls_cfg->capath);
        desc->old_tls_cfg->certfile = ast_strdup(desc->tls_cfg->certfile);
        desc->old_tls_cfg->pvtfile = ast_strdup(desc->tls_cfg->pvtfile);
        desc->old_tls_cfg->cipher = ast_strdup(desc->tls_cfg->cipher);
        desc->old_tls_cfg->cafile = ast_strdup(desc->tls_cfg->cafile);
        desc->old_tls_cfg->capath = ast_strdup(desc->tls_cfg->capath);
        memcpy(desc->old_tls_cfg->certhash, desc->tls_cfg->certhash, 41);
        memcpy(desc->old_tls_cfg->pvthash, desc->tls_cfg->pvthash, 41);
        memcpy(desc->old_tls_cfg->cahash, desc->tls_cfg->cahash, 41);
        memcpy(&desc->old_tls_cfg->flags, &desc->tls_cfg->flags, sizeof(desc->old_tls_cfg->flags));
    }
 
    return;
 
error:
    close(desc->accept_fd);
    desc->accept_fd = -1;
}
 
void ast_tcptls_close_session_file(struct ast_tcptls_session_instance *tcptls_session)
{
    if (tcptls_session->stream) {
        ast_iostream_close(tcptls_session->stream);
        tcptls_session->stream = NULL;
    } else {
        ast_debug(1, "ast_tcptls_close_session_file invoked on session instance without file or file descriptor\n");
    }
}
 
void ast_tcptls_server_stop(struct ast_tcptls_session_args *desc)
{
    if (desc->master != AST_PTHREADT_NULL) {
        pthread_cancel(desc->master);
        pthread_kill(desc->master, SIGURG);
        pthread_join(desc->master, NULL);
        desc->master = AST_PTHREADT_NULL;
    }
    if (desc->accept_fd != -1) {
        close(desc->accept_fd);
    }
    desc->accept_fd = -1;
 
    if (desc->old_tls_cfg) {
        ast_free(desc->old_tls_cfg->certfile);
        ast_free(desc->old_tls_cfg->pvtfile);
        ast_free(desc->old_tls_cfg->cipher);
        ast_free(desc->old_tls_cfg->cafile);
        ast_free(desc->old_tls_cfg->capath);
        ast_free(desc->old_tls_cfg);
        desc->old_tls_cfg = NULL;
    }
 
    ast_debug(2, "Stopped server :: %s\n", desc->name);
}
 
int ast_tls_read_conf(struct ast_tls_config *tls_cfg, struct ast_tcptls_session_args *tls_desc, const char *varname, const char *value)
{
    if (!strcasecmp(varname, "tlsenable") || !strcasecmp(varname, "sslenable")) {
        tls_cfg->enabled = ast_true(value) ? 1 : 0;
    } else if (!strcasecmp(varname, "tlscertfile") || !strcasecmp(varname, "sslcert") || !strcasecmp(varname, "tlscert")) {
        ast_free(tls_cfg->certfile);
        tls_cfg->certfile = ast_strdup(value);
    } else if (!strcasecmp(varname, "tlsprivatekey") || !strcasecmp(varname, "sslprivatekey")) {
        ast_free(tls_cfg->pvtfile);
        tls_cfg->pvtfile = ast_strdup(value);
    } else if (!strcasecmp(varname, "tlscipher") || !strcasecmp(varname, "sslcipher")) {
        ast_free(tls_cfg->cipher);
        tls_cfg->cipher = ast_strdup(value);
    } else if (!strcasecmp(varname, "tlscafile")) {
        ast_free(tls_cfg->cafile);
        tls_cfg->cafile = ast_strdup(value);
    } else if (!strcasecmp(varname, "tlscapath") || !strcasecmp(varname, "tlscadir")) {
        ast_free(tls_cfg->capath);
        tls_cfg->capath = ast_strdup(value);
    } else if (!strcasecmp(varname, "tlsverifyclient")) {
        ast_set2_flag(&tls_cfg->flags, ast_true(value), AST_SSL_VERIFY_CLIENT);
    } else if (!strcasecmp(varname, "tlsdontverifyserver")) {
        ast_set2_flag(&tls_cfg->flags, ast_true(value), AST_SSL_DONT_VERIFY_SERVER);
    } else if (!strcasecmp(varname, "tlsbindaddr") || !strcasecmp(varname, "sslbindaddr")) {
        if (ast_parse_arg(value, PARSE_ADDR, &tls_desc->local_address))
            ast_log(LOG_ERROR, "Invalid %s '%s'\n", varname, value);
    } else if (!strcasecmp(varname, "tlsclientmethod") || !strcasecmp(varname, "sslclientmethod")) {
        if (!strcasecmp(value, "tlsv1")) {
            ast_set_flag(&tls_cfg->flags, AST_SSL_TLSV1_CLIENT);
            ast_clear_flag(&tls_cfg->flags, AST_SSL_SSLV3_CLIENT);
            ast_clear_flag(&tls_cfg->flags, AST_SSL_SSLV2_CLIENT);
        } else if (!strcasecmp(value, "sslv3")) {
            ast_set_flag(&tls_cfg->flags, AST_SSL_SSLV3_CLIENT);
            ast_clear_flag(&tls_cfg->flags, AST_SSL_SSLV2_CLIENT);
            ast_clear_flag(&tls_cfg->flags, AST_SSL_TLSV1_CLIENT);
        } else if (!strcasecmp(value, "sslv2")) {
            ast_set_flag(&tls_cfg->flags, AST_SSL_SSLV2_CLIENT);
            ast_clear_flag(&tls_cfg->flags, AST_SSL_TLSV1_CLIENT);
            ast_clear_flag(&tls_cfg->flags, AST_SSL_SSLV3_CLIENT);
        }
    } else if (!strcasecmp(varname, "tlsservercipherorder")) {
        ast_set2_flag(&tls_cfg->flags, ast_true(value), AST_SSL_SERVER_CIPHER_ORDER);
    } else if (!strcasecmp(varname, "tlsdisablev1")) {
        ast_set2_flag(&tls_cfg->flags, ast_true(value), AST_SSL_DISABLE_TLSV1);
    } else if (!strcasecmp(varname, "tlsdisablev11")) {
        ast_set2_flag(&tls_cfg->flags, ast_true(value), AST_SSL_DISABLE_TLSV11);
    } else if (!strcasecmp(varname, "tlsdisablev12")) {
        ast_set2_flag(&tls_cfg->flags, ast_true(value), AST_SSL_DISABLE_TLSV12);
    } else {
        return -1;
    }
 
    return 0;
}