/*
 * SSLsplit - transparent and scalable SSL/TLS interception
 * Copyright (c) 2009-2014, Daniel Roethlisberger <daniel@roe.ch>
 * All rights reserved.
 * http://www.roe.ch/SSLsplit
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* silence daemon(3) deprecation warning on Mac OS X */
#if __APPLE__
#define daemon xdaemon
#endif /* __APPLE__ */

#include "opts.h"
#include "proxy.h"
#include "ssl.h"
#include "nat.h"
#include "cachemgr.h"
#include "sys.h"
#include "log.h"
#include "version.h"

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>

#ifndef __BSD__
#include <getopt.h>
#endif /* !__BSD__ */

#include <event2/event.h>

#include <openssl/ssl.h>
#include <openssl/x509.h>

#if __APPLE__
#undef daemon
extern int daemon(int, int);
#endif /* __APPLE__ */

/*
 * Print version information to stderr.
 */
static void
main_version(void)
{
	fprintf(stderr, "%s %s (built %s)\n", PNAME, version, build_date);
	fprintf(stderr, "Copyright (c) 2009-2014, "
	                "Daniel Roethlisberger <daniel@roe.ch>\n");
	fprintf(stderr, "http://www.roe.ch/SSLsplit\n");
	if (features[0]) {
		fprintf(stderr, "Features: %s\n", features);
	}
	nat_version();
	ssl_openssl_version();
	fprintf(stderr, "compiled against libevent %s\n", LIBEVENT_VERSION);
	fprintf(stderr, "rtlinked against libevent %s\n", event_get_version());
	fprintf(stderr, "%d CPU cores detected\n", sys_get_cpu_cores());
}

/*
 * Print usage to stderr.
 */
static void
main_usage(void)
{
	const char *dflt, *warn;

	if (!(dflt = nat_getdefaultname())) {
		dflt = "n/a";
		warn = "\nWarning: no supported NAT engine on this platform!\n"
		       "Only static and SNI proxyspecs are supported.\n";
	} else {
		warn = "";
	}

	fprintf(stderr,
"Usage: %s [options...] [proxyspecs...]\n"
"  -c pemfile  use CA cert (and key) from pemfile to sign forged certs\n"
"  -k pemfile  use CA key (and cert) from pemfile to sign forged certs\n"
"  -C pemfile  use CA chain from pemfile (intermediate and root CA certs)\n"
"  -K pemfile  use key from pemfile for leaf certs (default: generate)\n"
"  -t certdir  use cert+chain+key PEM files from certdir to target all sites\n"
"              matching the common names (non-matching: generate if CA)\n"
"  -O          deny all OCSP requests on all proxyspecs\n"
"  -P          passthrough SSL connections if they cannot be split because of\n"
"              client cert auth or no matching cert and no CA (default: drop)\n"
#ifndef OPENSSL_NO_DH
"  -g pemfile  use DH group params from pemfile (default: keyfiles or auto)\n"
#define OPT_g "g:"
#else /* OPENSSL_NO_DH */
#define OPT_g 
#endif /* !OPENSSL_NO_DH */
#ifndef OPENSSL_NO_ECDH
"  -G curve    use ECDH named curve (default: %s for non-RSA leafkey)\n"
#define OPT_G "G:"
#else /* OPENSSL_NO_ECDH */
#define OPT_G 
#endif /* OPENSSL_NO_ECDH */
#ifdef SSL_OP_NO_COMPRESSION
"  -Z          disable SSL/TLS compression on all connections\n"
#define OPT_Z "Z"
#else /* !SSL_OP_NO_COMPRESSION */
#define OPT_Z 
#endif /* !SSL_OP_NO_COMPRESSION */
"  -s ciphers  use the given OpenSSL cipher suite spec (default: ALL:-aNULL)\n"
"  -e engine   specify default NAT engine to use (default: %s)\n"
"  -E          list available NAT engines and exit\n"
"  -u user     drop privileges to user (default if run as root: nobody)\n"
"  -j jaildir  chroot() to jaildir (default if run as root: /var/empty)\n"
"  -p pidfile  write pid to pidfile (default: no pid file)\n"
"  -l logfile  connect log: log one line summary per connection to logfile\n"
"  -L logfile  content log: full data to file or named pipe (excludes -S)\n"
"  -S logdir   content log: full data to separate files in dir (excludes -L)\n"
"  -d          daemon mode: run in background, log error messages to syslog\n"
"  -D          debug mode: run in foreground, log debug messages on stderr\n"
"  -V          print version information and exit\n"
"  -h          print usage information and exit\n"
"  proxyspec = type listenaddr+port [natengine|targetaddr+port|\"sni\"+port]\n"
"  e.g.        http 0.0.0.0 8080 www.roe.ch 80  # http/4; static hostname dst\n"
"              https ::1 8443 2001:db8::1 443   # https/6; static address dst\n"
"              https 127.0.0.1 9443 sni 443     # https/4; SNI DNS lookups\n"
"              tcp 127.0.0.1 10025              # tcp/4; default NAT engine\n"
"              ssl 2001:db8::2 9999 pf          # ssl/6; NAT engine 'pf'\n"
"Example:\n"
"  %s -k ca.key -c ca.pem -P  https 127.0.0.1 8443  https ::1 8443\n"
	"%s", BNAME,
#ifndef OPENSSL_NO_ECDH
	SSL_EC_KEY_CURVE_DEFAULT,
#endif /* !OPENSSL_NO_ECDH */
	dflt, BNAME, warn);
}

/*
 * Callback to load a cert/chain/key combo from a single PEM file.
 */
static void
main_loadtgcrt(const char *filename, void *arg)
{
	opts_t *opts = arg;
	cert_t *cert;
	char **names;

	cert = cert_new_load(filename);
	if (!cert) {
		log_err_printf("Failed to load cert and key from PEM file "
		                "'%s'\n", filename);
		log_fini();
		exit(EXIT_FAILURE); /* XXX */
	}
	if (X509_check_private_key(cert->crt, cert->key) != 1) {
		log_err_printf("Cert does not match key in PEM file "
		                "'%s':\n", filename);
		ERR_print_errors_fp(stderr);
		log_fini();
		exit(EXIT_FAILURE); /* XXX */
	}

#ifdef DEBUG_CERTIFICATE
	log_dbg_printf("Loaded '%s':\n", filename);
	log_dbg_print_free(ssl_x509_to_str(cert->crt));
	log_dbg_print_free(ssl_x509_to_pem(cert->crt));
#endif /* DEBUG_CERTIFICATE */

	if (OPTS_DEBUG(opts)) {
		log_dbg_printf("Targets for '%s':", filename);
	}
	names = ssl_x509_names(cert->crt);
	for (char **p = names; *p; p++) {
		/* be deliberately vulnerable to NULL prefix attacks */
		char *sep;
		if ((sep = strchr(*p, '!'))) {
			*sep = '\0';
		}
		if (OPTS_DEBUG(opts)) {
			log_dbg_printf(" '%s'", *p);
		}
		cachemgr_tgcrt_set(*p, cert);
		free(*p);
	}
	if (OPTS_DEBUG(opts)) {
		log_dbg_printf("\n");
	}
	free(names);
	cert_free(cert);
}

/*
 * Main entry point.
 */
int
main(int argc, char *argv[])
{
	const char *argv0;
	int ch;
	opts_t *opts;
	char *natengine;
	int pidfd = -1;
	int rv = EXIT_FAILURE;

	argv0 = argv[0];
	opts = opts_new();
	natengine = strdup(nat_getdefaultname());

	while ((ch = getopt(argc, argv, OPT_g OPT_G OPT_Z
	                    "k:c:C:K:t:OPs:e:Eu:j:p:l:L:S:dDVh")) != -1) {
		switch (ch) {
			case 'c':
				if (opts->cacrt)
					X509_free(opts->cacrt);
				opts->cacrt = ssl_x509_load(optarg);
				if (!opts->cacrt) {
					fprintf(stderr, "%s: error loading CA "
					                "cert from '%s':\n",
					                argv0, optarg);
					if (errno) {
						fprintf(stderr, "%s\n",
						        strerror(errno));
					} else {
						ERR_print_errors_fp(stderr);
					}
					exit(EXIT_FAILURE);
				}
				ssl_x509_refcount_inc(opts->cacrt);
				sk_X509_insert(opts->chain, opts->cacrt, 0);
				if (!opts->cakey) {
					opts->cakey = ssl_key_load(optarg);
				}
#ifndef OPENSSL_NO_DH
				if (!opts->dh) {
					opts->dh = ssl_dh_load(optarg);
				}
#endif /* !OPENSSL_NO_DH */
				break;
			case 'k':
				if (opts->cakey)
					EVP_PKEY_free(opts->cakey);
				opts->cakey = ssl_key_load(optarg);
				if (!opts->cakey) {
					fprintf(stderr, "%s: error loading CA "
					                "key from '%s':\n",
					                argv0, optarg);
					if (errno) {
						fprintf(stderr, "%s\n",
						        strerror(errno));
					} else {
						ERR_print_errors_fp(stderr);
					}
					exit(EXIT_FAILURE);
				}
				if (!opts->cacrt) {
					opts->cacrt = ssl_x509_load(optarg);
					if (opts->cacrt) {
						ssl_x509_refcount_inc(
						               opts->cacrt);
						sk_X509_insert(opts->chain,
						               opts->cacrt, 0);
					}
				}
#ifndef OPENSSL_NO_DH
				if (!opts->dh) {
					opts->dh = ssl_dh_load(optarg);
				}
#endif /* !OPENSSL_NO_DH */
				break;
			case 'C':
				if (ssl_x509chain_load(NULL, &opts->chain,
				                       optarg) == -1) {
					fprintf(stderr, "%s: error loading "
					                "chain from '%s':\n",
					                argv0, optarg);
					if (errno) {
						fprintf(stderr, "%s\n",
						        strerror(errno));
					} else {
						ERR_print_errors_fp(stderr);
					}
					exit(EXIT_FAILURE);
				}
				break;
			case 'K':
				if (opts->key)
					EVP_PKEY_free(opts->key);
				opts->key = ssl_key_load(optarg);
				if (!opts->key) {
					fprintf(stderr, "%s: error loading lea"
					                "f key from '%s':\n",
					                argv0, optarg);
					if (errno) {
						fprintf(stderr, "%s\n",
						        strerror(errno));
					} else {
						ERR_print_errors_fp(stderr);
					}
					exit(EXIT_FAILURE);
				}
#ifndef OPENSSL_NO_DH
				if (!opts->dh) {
					opts->dh = ssl_dh_load(optarg);
				}
#endif /* !OPENSSL_NO_DH */
				break;
			case 't':
				if (!sys_isdir(optarg)) {
					fprintf(stderr, "%s: '%s' is not a "
					                "directory\n",
					                argv0, optarg);
					exit(EXIT_FAILURE);
				}
				if (opts->tgcrtdir)
					free(opts->tgcrtdir);
				opts->tgcrtdir = strdup(optarg);
				break;
			case 'O':
				opts->deny_ocsp = 1;
				break;
			case 'P':
				opts->passthrough = 1;
				break;
#ifndef OPENSSL_NO_DH
			case 'g':
				if (opts->dh)
					DH_free(opts->dh);
				opts->dh = ssl_dh_load(optarg);
				if (!opts->dh) {
					fprintf(stderr, "%s: error loading DH "
					                "params from '%s':\n",
					                argv0, optarg);
					if (errno) {
						fprintf(stderr, "%s\n",
						        strerror(errno));
					} else {
						ERR_print_errors_fp(stderr);
					}
					exit(EXIT_FAILURE);
				}
				break;
#endif /* !OPENSSL_NO_DH */
#ifndef OPENSSL_NO_ECDH
			case 'G':
			{
				EC_KEY *ec;
				if (opts->ecdhcurve)
					free(opts->ecdhcurve);
				if (!(ec = ssl_ec_by_name(optarg))) {
					fprintf(stderr, "%s: unknown curve "
					                "'%s'\n",
					                argv0, optarg);
					exit(EXIT_FAILURE);
				}
				EC_KEY_free(ec);
				opts->ecdhcurve = strdup(optarg);
				break;
			}
#endif /* !OPENSSL_NO_ECDH */
#ifdef SSL_OP_NO_COMPRESSION
			case 'Z':
				opts->sslcomp = 0;
				break;
#endif /* SSL_OP_NO_COMPRESSION */
			case 's':
				if (opts->ciphers)
					free(opts->ciphers);
				opts->ciphers = strdup(optarg);
				break;
			case 'e':
				free(natengine);
				natengine = strdup(optarg);
				break;
			case 'E':
				nat_list_engines();
				exit(EXIT_SUCCESS);
				break;
			case 'u':
				if (opts->dropuser)
					free(opts->dropuser);
				opts->dropuser = strdup(optarg);
				break;
			case 'p':
				if (opts->pidfile)
					free(opts->pidfile);
				opts->pidfile = strdup(optarg);
				break;
			case 'j':
				if (opts->jaildir)
					free(opts->jaildir);
				opts->jaildir = strdup(optarg);
				break;
			case 'l':
				if (opts->connectlog)
					free(opts->connectlog);
				opts->connectlog = strdup(optarg);
				break;
			case 'L':
				if (opts->contentlog)
					free(opts->contentlog);
				opts->contentlog = strdup(optarg);
				opts->contentlogdir = 0;
				break;
			case 'S':
				if (opts->contentlog)
					free(opts->contentlog);
				opts->contentlog = strdup(optarg);
				opts->contentlogdir = 1;
				break;
			case 'd':
				opts->detach = 1;
				break;
			case 'D':
				log_dbg_mode(LOG_DBG_MODE_ERRLOG);
				opts->debug = 1;
				break;
			case 'V':
				main_version();
				exit(EXIT_SUCCESS);
			case 'h':
				main_usage();
				exit(EXIT_SUCCESS);
			case '?':
				exit(EXIT_FAILURE);
			default:
				main_usage();
				exit(EXIT_FAILURE);
		}
	}
	argc -= optind;
	argv += optind;
	opts->spec = proxyspec_parse(&argc, &argv, natengine);

	/* usage checks */
	if (opts->detach && OPTS_DEBUG(opts)) {
		fprintf(stderr, "%s: -d and -D are mutually exclusive.\n",
		                argv0);
		exit(EXIT_FAILURE);
	}
	if (!opts->spec) {
		fprintf(stderr, "%s: no proxyspec specified.\n", argv0);
		exit(EXIT_FAILURE);
	}
	for (proxyspec_t *spec = opts->spec; spec; spec = spec->next) {
		if (spec->connect_addrlen || spec->sni_port)
			continue;
		if (!spec->natengine) {
			fprintf(stderr, "%s: no supported NAT engines "
			                "on this platform.\n"
			                "Only static addr and SNI proxyspecs "
			                "supported.\n", argv0);
			exit(EXIT_FAILURE);
		}
		if (spec->listen_addr.ss_family == AF_INET6 &&
		    !nat_ipv6ready(spec->natengine)) {
			fprintf(stderr, "%s: IPv6 not supported by '%s'\n",
			                argv0, spec->natengine);
			exit(EXIT_FAILURE);
		}
		spec->natlookup = nat_getlookupcb(spec->natengine);
		spec->natsocket = nat_getsocketcb(spec->natengine);
	}
	if (opts_has_ssl_spec(opts)) {
		if ((opts->cacrt || !opts->tgcrtdir) && !opts->cakey) {
			fprintf(stderr, "%s: no CA key specified (-k).\n",
			                argv0);
			exit(EXIT_FAILURE);
		}
		if (opts->cakey && !opts->cacrt) {
			fprintf(stderr, "%s: no CA cert specified (-c).\n",
			                argv0);
			exit(EXIT_FAILURE);
		}
		if (opts->cakey && opts->cacrt &&
		    (X509_check_private_key(opts->cacrt, opts->cakey) != 1)) {
			fprintf(stderr, "%s: CA cert does not match key.\n",
			                argv0);
			ERR_print_errors_fp(stderr);
			exit(EXIT_FAILURE);
		}
	}

	/* prevent multiple instances running */
	if (opts->pidfile) {
		pidfd = sys_pidf_open(opts->pidfile);
		if (pidfd == -1) {
			fprintf(stderr, "%s: cannot open PID file '%s' "
			                "- process already running?\n",
			                argv0, opts->pidfile);
			exit(EXIT_FAILURE);
		}
	}

	/* dynamic defaults */
	if (!opts->ciphers) {
		opts->ciphers = strdup("ALL:-aNULL");
		if (!opts->ciphers) {
			fprintf(stderr, "%s: out of memory.\n", argv0);
			exit(EXIT_FAILURE);
		}
	}
	if (!opts->jaildir && (geteuid() == 0) && !opts->contentlogdir) {
		opts->jaildir = strdup("/var/empty");
	}
	if (!opts->dropuser && !geteuid() && !getuid() &&
	    !opts->contentlogdir) {
		opts->dropuser = strdup("nobody");
	}
	if (opts_has_ssl_spec(opts) && opts->cakey && !opts->key) {
		opts->key = ssl_key_genrsa(1024);
		if (!opts->key) {
			fprintf(stderr, "%s: error generating RSA key:\n",
			                argv0);
			ERR_print_errors_fp(stderr);
			exit(EXIT_FAILURE);
		}
		if (OPTS_DEBUG(opts)) {
			log_dbg_printf("Generated RSA key for leaf certs.\n");
		}
	}

	/* debugging */
	if (OPTS_DEBUG(opts)) {
		main_version();
		log_dbg_printf("proxyspecs:\n");
		for (proxyspec_t *spec = opts->spec; spec; spec = spec->next) {
			char *lbuf, *cbuf = NULL;
			lbuf = sys_sockaddr_str((struct sockaddr *)
			                        &spec->listen_addr,
			                        spec->listen_addrlen);
			if (spec->connect_addrlen) {
				cbuf = sys_sockaddr_str((struct sockaddr *)
				                        &spec->connect_addr,
				                        spec->connect_addrlen);
			}
			if (spec->sni_port) {
				asprintf(&cbuf, "sni %i", spec->sni_port);
			}
			log_dbg_printf("- %s %s %s %s\n", lbuf,
			               (spec->ssl ? "ssl" : "tcp"),
			               (spec->http ? "http" : "plain"),
			               (spec->natengine ? spec->natengine
			                                : cbuf));
			if (lbuf)
				free(lbuf);
			if (cbuf)
				free(cbuf);
		}
		if (opts->cacrt) {
			char *subj = ssl_x509_subject(opts->cacrt);
			log_dbg_printf("Loaded CA: '%s'\n", subj);
			free(subj);
#ifdef DEBUG_CERTIFICATE
			log_dbg_print_free(ssl_x509_to_str(opts->cacrt));
			log_dbg_print_free(ssl_x509_to_pem(opts->cacrt));
#endif /* DEBUG_CERTIFICATE */
		} else {
			log_dbg_printf("No CA loaded.\n");
		}
	}

	/*
	 * Initialize as much as possible before daemon() in order to be
	 * able to provide direct feedback to the user when failing.
	 */
	if (cachemgr_preinit() == -1) {
		fprintf(stderr, "%s: failed to preinit cachemgr.\n", argv0);
		exit(EXIT_FAILURE);
	}
	if (log_preinit(opts) == -1) {
		fprintf(stderr, "%s: failed to preinit logging.\n", argv0);
		exit(EXIT_FAILURE);
	}
	if (nat_preinit() == -1) {
		fprintf(stderr, "%s: failed to preinit NAT lookup.\n", argv0);
		exit(EXIT_FAILURE);
	}

	/* Bind listeners before dropping privileges */
	proxy_ctx_t *proxy = proxy_new(opts);
	if (!proxy) {
		fprintf(stderr, "%s: failed to initialize proxy.\n", argv0);
		exit(EXIT_FAILURE);
	}

	/* Drop privs, chroot, detach from TTY */
	if (sys_privdrop(opts->dropuser, opts->jaildir) == -1) {
		fprintf(stderr, "%s: failed to drop privileges: %s\n",
		                argv0, strerror(errno));
		exit(EXIT_FAILURE);
	}
	if (opts->detach) {
		if (OPTS_DEBUG(opts)) {
			log_dbg_printf("Detaching from TTY, see syslog for "
			               "errors after this point\n");
		}
		if (daemon(1, 0) == -1) {
			fprintf(stderr, "%s: failed to detach from TTY: %s\n",
			                argv0, strerror(errno));
			exit(EXIT_FAILURE);
		}
		log_err_mode(LOG_ERR_MODE_SYSLOG);
		ssl_reinit();
	}

	/* Post-privdrop/chroot/detach initialization, thread spawning */
	if (log_init(opts) == -1) {
		fprintf(stderr, "%s: failed to init log facility: %s\n",
		                argv0, strerror(errno));
		goto out_log_failed;
	}
	if (opts->pidfile && (sys_pidf_write(pidfd) == -1)) {
		log_err_printf("Failed to write PID to PID file '%s': %s\n",
		               opts->pidfile, strerror(errno));
		goto out_pidwrite_failed;
	}
	if (cachemgr_init() == -1) {
		log_err_printf("Failed to init cache manager.\n");
		goto out_cachemgr_failed;
	}
	if (nat_init() == -1) {
		log_err_printf("Failed to init NAT state table lookup.\n");
		goto out_nat_failed;
	}

	if (opts->tgcrtdir) {
		sys_dir_eachfile(opts->tgcrtdir, main_loadtgcrt, opts);
	}

	rv = EXIT_SUCCESS;

	proxy_run(proxy);
	proxy_free(proxy);
	nat_fini();
out_nat_failed:
	cachemgr_fini();
out_cachemgr_failed:
	if (opts->pidfile) {
		sys_pidf_close(pidfd, opts->pidfile);
	}
out_pidwrite_failed:
	log_fini();
out_log_failed:
	opts_free(opts);
	ssl_fini();
	return rv;
}

/* vim: set noet ft=c: */