sslh-main.c

/*
# main: processing of config file, command line options and start the main
# loop.
#
# Copyright (C) 2007-2018  Yves Rutschle
# 
# This program is free software; you can redistribute it
# and/or modify it under the terms of the GNU General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later
# version.
# 
# This program is distributed in the hope that it will be
# useful, but WITHOUT ANY WARRANTY; without even the implied
# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
# PURPOSE.  See the GNU General Public License for more
# details.
# 
# The full text for the General Public License is here:
# http://www.gnu.org/licenses/gpl.html

*/

#define _GNU_SOURCE
#ifdef LIBCONFIG
#include <libconfig.h>
#endif
#ifdef ENABLE_REGEX
#ifdef LIBPCRE
#include <pcreposix.h>
#else
#include <regex.h>
#endif
#endif

#ifdef LIBBSD
#include <bsd/unistd.h>
#endif

#include "common.h"
#include "probe.h"

const char* USAGE_STRING =
"sslh " VERSION "\n" \
"usage:\n" \
"\tsslh  [-v] [-i] [-V] [-f] [-n] [--transparent] [-F<file>]\n"
"\t[-t <timeout>] [-P <pidfile>] [-u <username>] [-C <chroot>] -p <addr> [-p <addr> ...] \n" \
"%s\n\n" /* Dynamically built list of builtin protocols */  \
"\t[--on-timeout <addr>]\n" \
"-v: verbose\n" \
"-V: version\n" \
"-f: foreground\n" \
"-n: numeric output\n" \
"-u: specify under which user to run\n" \
"-C: specify under which chroot path to run\n" \
"--transparent: behave as a transparent proxy\n" \
"-F: use configuration file (warning: no space between -F and file name!)\n" \
"--on-timeout: connect to specified address upon timeout (default: ssh address)\n" \
"-t: seconds to wait before connecting to --on-timeout address.\n" \
"-p: address and port to listen on.\n    Can be used several times to bind to several addresses.\n" \
"--[ssh,ssl,...]: where to connect connections from corresponding protocol.\n" \
"-P: PID file.\n" \
"-i: Run as a inetd service.\n" \
"";

/* Constants for options that have no one-character shorthand */
#define OPT_ONTIMEOUT   257

static void printcaps(void) {
#ifdef LIBCAP
    cap_t caps;
    char* desc;
    ssize_t len;

    caps = cap_get_proc();

    desc = cap_to_text(caps, &len);

    fprintf(stderr, "capabilities: %s\n", desc);

    cap_free(caps);
    cap_free(desc);
#endif
}

static void printsettings(void)
{
    char buf[NI_MAXHOST];
    struct addrinfo *a;
    int i;
    struct sslhcfg_protocols_item *p;
    
    for (i = 0; i < cfg.protocols_len; i++ ) {
        p = &cfg.protocols[i];
        fprintf(stderr,
                "%s addr: %s. libwrap service: %s log_level: %d family %d %d [%s] [%s]\n",
                p->name, 
                sprintaddr(buf, sizeof(buf), p->saddr), 
                p->service,
                p->log_level,
                p->saddr->ai_family,
                p->saddr->ai_addr->sa_family,
                p->keepalive ? "keepalive" : "",
                p->fork ? "fork" : "");
    }
    fprintf(stderr, "listening on:\n");
    for (a = addr_listen; a; a = a->ai_next) {
        fprintf(stderr, 
                "\t%s\t[%s]\n", 
                sprintaddr(buf, sizeof(buf), a), 
                a->ai_flags & SO_KEEPALIVE ? "keepalive" : "");
    }
    fprintf(stderr, "timeout: %d\non-timeout: %s\n", cfg.timeout,
            timeout_protocol()->name);
}


/* To be removed in v1.21 */
const char* ssl_err_msg = "Usage of 'ssl' setting is deprecated and will be removed in v1.21. Please use 'tls' instead\n";
void ssl_to_tls(char* setting)
{
    if (!strcmp(setting, "ssl")) {
        strcpy(setting, "tls"); /* legacy configuration */
        log_message(LOG_INFO, ssl_err_msg);
    }
}


/* Turn 'ssl' command line option to 'tls'. To be removed in v1.21 */
void cmd_ssl_to_tls(int argc, char* argv[])
{
    int i;
    for (i = 0; i < argc; i++) {
        if (!strcmp(argv[i], "--ssl")) {
            strcpy(argv[i], "--tls");
            /* foreground option not parsed yet, syslog not open, just print on
             * stderr and hope for the best */
            fprintf(stderr, "%s", ssl_err_msg);
        }
    }
}


/* Extract configuration on addresses and ports on which to listen.
 * out: newly allocated list of addrinfo to listen to
 */
#ifdef LIBCONFIG
static int config_resolve_listen(struct addrinfo **listen)
{
    int i;
    for (i = 0; i < cfg.listen_len; i++) {
        resolve_split_name(listen, cfg.listen[i].host, cfg.listen[i].port);

        /* getaddrinfo returned a list of addresses corresponding to the
         * specification; move the pointer to the end of that list before
         * processing the next specification, while setting flags for
         * start_listen_sockets() through ai_flags (which is not meant for
         * that, but is only used as hint in getaddrinfo, so it's OK) */
        for (; *listen; listen = &((*listen)->ai_next)) {
            if (cfg.listen[i].keepalive)
                (*listen)->ai_flags = SO_KEEPALIVE;
        }
    }
    return 0;
}
#endif



#ifdef LIBCONFIG
static void setup_regex_probe(struct sslhcfg_protocols_item *p)
{
    int num_patterns, i, res;
    regex_t** pattern_list;
    size_t errsize;
    char* err;

    num_patterns = p->regex_patterns_len;

    pattern_list = calloc(num_patterns + 1, sizeof(*pattern_list));
    CHECK_ALLOC(pattern_list, "calloc");
    p->data = (void*)pattern_list;

    for (i = 0; i < num_patterns; i++) {
        pattern_list[i] = malloc(sizeof(*(pattern_list[i])));
        CHECK_ALLOC(pattern_list[i], "malloc");
        res = regcomp(pattern_list[i], p->regex_patterns[i], REG_EXTENDED);
        if (res) {
            err = malloc(errsize = regerror(res, pattern_list[i], NULL, 0));
            CHECK_ALLOC(err, "malloc");
            regerror(res, pattern_list[i], err, errsize);
            fprintf(stderr, "%s:%s\n", p->regex_patterns[i], err);
            free(err);
            exit(1);
        }
    }
}
#endif

/* For each protocol in the configuration, resolve address and set up protocol
 * options if required
 */
static void config_protocols()
{
    int i;
    for (i = 0; i < cfg.protocols_len; i++) {
        struct sslhcfg_protocols_item* p = &(cfg.protocols[i]);
        if (resolve_split_name(&(p->saddr), p->host, p->port)) {
            fprintf(stderr, "cannot resolve %s:%s\n", p->host, p->port);
            exit(1);
        }

        p->probe = get_probe(p->name);
        if (!p->probe) {
            fprintf(stderr, "%s: probe unknown\n", p->name);
            exit(1);
        }

        if (!strcmp(cfg.protocols[i].name, "regex")) {
            setup_regex_probe(&cfg.protocols[i]);
        }

        if (!strcmp(cfg.protocols[i].name, "tls")) {
            cfg.protocols[i].data = (void*)new_tls_data();
            if (cfg.protocols[i].sni_hostnames_len)
                tls_data_set_list(cfg.protocols[i].data, 0,
                                  (const char**) cfg.protocols[i].sni_hostnames,
                                  cfg.protocols[i].sni_hostnames_len);
            if (cfg.protocols[i].alpn_protocols_len)
                tls_data_set_list(cfg.protocols[i].data, 1, 
                                  (const char**) cfg.protocols[i].alpn_protocols,
                                  cfg.protocols[i].alpn_protocols_len);
        }
    }
}


void config_sanity_check(struct sslhcfg_item* cfg) {
    if (!cfg->protocols_len) {
        fprintf(stderr, "At least one target protocol must be specified.\n");
        exit(2);
    }

/* If compiling with systemd socket support no need to require listen address */
#ifndef SYSTEMD
    if (!addr_listen && !cfg->inetd) {
        fprintf(stderr, "No listening address specified; use at least one -p option\n");
        exit(1);
    }
#endif
}


int main(int argc, char *argv[], char* envp[])
{

   extern char *optarg;
   extern int optind;
   int res, num_addr_listen;
   int *listen_sockets;

#ifdef LIBBSD
   setproctitle_init(argc, argv, envp);
#endif

   memset(&cfg, 0, sizeof(cfg));
   sslhcfg_cl_parse(argc, argv, &cfg);
   if (cfg.verbose > 3)
       sslhcfg_fprint(stderr, &cfg, 0);
   config_resolve_listen(&addr_listen);
   config_protocols();
   config_sanity_check(&cfg);

   if (cfg.inetd)
   {
       cfg.verbose = 0;
       start_shoveler(0);
       exit(0);
   }

   if (cfg.verbose)
       printsettings();

   num_addr_listen = start_listen_sockets(&listen_sockets, addr_listen);

#ifdef SYSTEMD
   if (num_addr_listen < 1) {
     fprintf(stderr, "No listening sockets found, restart sockets or specify addresses in config\n");
     exit(1);
    }
#endif

   if (!cfg.foreground) {
       if (fork() > 0) exit(0); /* Detach */

       /* New session -- become group leader */
       if (getuid() == 0) {
           res = setsid();
           CHECK_RES_DIE(res, "setsid: already process leader");
       }
   }

   setup_signals();

   if (cfg.pidfile)
       write_pid_file(cfg.pidfile);

   /* Open syslog connection before we drop privs/chroot */
   setup_syslog(argv[0]);

   if (cfg.user || cfg.chroot)
       drop_privileges(cfg.user, cfg.chroot);

   if (cfg.verbose)
       printcaps();

   main_loop(listen_sockets, num_addr_listen);

   return 0;
}