unbound/daemon/unbound.c

/*
 * daemon/unbound.c - main program for unbound DNS resolver daemon.
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * 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.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 REGENTS OR CONTRIBUTORS 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.
 *
 */

/**
 * \file
 *
 * Main program to start the DNS resolver daemon.
 */

#include "config.h"
#include "util/log.h"
#include "daemon/daemon.h"
#include "util/config_file.h"
#include <fcntl.h>
#include <pwd.h>

/** print usage. */
static void usage()
{
	printf("usage: unbound [options]\n");
	printf("	start unbound daemon DNS resolver.\n");
	printf("-h	this help\n");
	printf("-c file	config file to read, unbound.conf(5).\n");
	printf("-v	verbose (multiple times increase verbosity)\n");
	printf("Version %s\n", PACKAGE_VERSION);
	printf("BSD licensed, see LICENSE in source package for details.\n");
	printf("Report bugs to %s\n", PACKAGE_BUGREPORT);
}

/** daemonize, drop user priviliges and chroot if needed */
static void
do_chroot(struct config_file* cfg)
{
	log_assert(cfg);

	/* daemonize last to be able to print error to user */
	if(cfg->chrootdir && cfg->chrootdir[0])
		if(chroot(cfg->chrootdir))
			fatal_exit("unable to chroot: %s", strerror(errno));
	if(cfg->username && cfg->username[0]) {
		struct passwd *pwd;
		if((pwd = getpwnam(cfg->username)) == NULL)
			fatal_exit("user '%s' does not exist.", cfg->username);
		if(setgid(pwd->pw_gid) != 0)
			fatal_exit("unable to set group id: %s", strerror(errno));
		if(setuid(pwd->pw_uid) != 0)
			fatal_exit("unable to set user id: %s", strerror(errno));
		endpwent();
	}
	if(cfg->do_daemonize) {
		int fd;
		/* Take off... */
		switch (fork()) {
			case 0:
				break;
			case -1:
				fatal_exit("fork failed: %s", strerror(errno));
			default:
				/* exit interactive session */
				exit(0);
		}
		/* detach */
		if(setsid() == -1)
			fatal_exit("setsid() failed: %s", strerror(errno));
		if ((fd = open("/dev/null", O_RDWR, 0)) != -1) {
			(void)dup2(fd, STDIN_FILENO);
			(void)dup2(fd, STDOUT_FILENO);
			(void)dup2(fd, STDERR_FILENO);
			if (fd > 2)
				(void)close(fd);
		}
	}
}

/**
 * Run the daemon. 
 * @param cfgfile: the config file name.
 * @param cmdline_verbose: verbosity resulting from commandline -v.
 *    These increase verbosity as specified in the config file.
 */
static void run_daemon(const char* cfgfile, int cmdline_verbose)
{
	struct config_file* cfg = NULL;
	struct daemon* daemon = NULL;
	int done_chroot = 0;

	if(!(daemon = daemon_init()))
		fatal_exit("alloc failure");
	while(!daemon->need_to_exit) {
		if(done_chroot)
			log_info("Restart of %s.", PACKAGE_STRING);
		else	log_info("Start of %s.", PACKAGE_STRING);

		/* config stuff */
		if(!(cfg = config_create()))
			fatal_exit("Could not alloc config defaults");
		if(!config_read(cfg, cfgfile))
			fatal_exit("Could not read config file: %s", cfgfile);
		verbosity = cmdline_verbose + cfg->verbosity;
	
		/* prepare */
		if(!daemon_open_shared_ports(daemon, cfg))
			fatal_exit("could not open ports");
		if(!done_chroot) { 
			do_chroot(cfg); 
			done_chroot = 1; 
		}
		/* work */
		daemon_fork(daemon);

		/* clean up for restart */
		verbose(VERB_ALGO, "cleanup.");
		daemon_cleanup(daemon);
		config_delete(cfg);
	}
	verbose(VERB_ALGO, "Exit cleanup.");
	daemon_delete(daemon);
}

/** getopt global, in case header files fail to declare it. */
extern int optind;
/** getopt global, in case header files fail to declare it. */
extern char* optarg;

/**
 * main program. Set options given commandline arguments.
 * @param argc: number of commandline arguments.
 * @param argv: array of commandline arguments.
 * @return: exit status of the program.
 */
int 
main(int argc, char* argv[])
{
	int c;
	const char* cfgfile = NULL;
	int cmdline_verbose = 0;

	log_init();
	/* parse the options */
	while( (c=getopt(argc, argv, "c:hv")) != -1) {
		switch(c) {
		case 'c':
			cfgfile = optarg;
			break;
		case 'v':
			cmdline_verbose ++;
			verbosity++;
			break;
		case '?':
		case 'h':
		default:
			usage();
			return 1;
		}
	}
	argc -= optind;
	argv += optind;

	if(argc != 0) {
		usage();
		return 1;
	}

	run_daemon(cfgfile, cmdline_verbose);
	return 0;
}