int main(int argc, char * * argv)
{
	int ret = 0;
	int pid;
	struct sigaction sa;
	char buf[1500];
	ssize_t n;
	int s_ssdp = -1;	/* udp socket receiving ssdp packets */
#ifdef ENABLE_IPV6
	int s_ssdp6 = -1;	/* udp socket receiving ssdp packets IPv6*/
#else	/* ENABLE_IPV6 */
#define s_ssdp6 (-1)
#endif	/* ENABLE_IPV6 */
	int s_unix = -1;	/* unix socket communicating with clients */
	int s_ifacewatch = -1;	/* socket to receive Route / network interface config changes */
	struct reqelem * req;
	struct reqelem * reqnext;
	fd_set readfds;
	fd_set writefds;
	struct timeval now;
	int max_fd;
	struct lan_addr_s * lan_addr;
	int i;
	const char * sockpath = "/var/run/minissdpd.sock";
	const char * pidfilename = "/var/run/minissdpd.pid";
	int debug_flag = 0;
#ifdef ENABLE_IPV6
	int ipv6 = 0;
#endif /* ENABLE_IPV6 */
	int deltadev = 0;
	struct sockaddr_in sendername;
	socklen_t sendername_len;
#ifdef ENABLE_IPV6
	struct sockaddr_in6 sendername6;
	socklen_t sendername6_len;
#endif	/* ENABLE_IPV6 */
	unsigned char ttl = 2;	/* UDA says it should default to 2 */
	const char * searched_device = NULL;	/* if not NULL, search/filter a specific device type */

	LIST_INIT(&reqlisthead);
	LIST_INIT(&servicelisthead);
	LIST_INIT(&lan_addrs);
	/* process command line */
	for(i=1; i<argc; i++)
	{
 		if(0==strcmp(argv[i], "-d"))
			debug_flag = 1;
#ifdef ENABLE_IPV6
		else if(0==strcmp(argv[i], "-6"))
			ipv6 = 1;
#endif	/* ENABLE_IPV6 */
		else {
			if((i + 1) >= argc) {
				fprintf(stderr, "option %s needs an argument.\n", argv[i]);
				break;
			}
			if(0==strcmp(argv[i], "-i")) {
				lan_addr = malloc(sizeof(struct lan_addr_s));
				if(lan_addr == NULL) {
					fprintf(stderr, "malloc(%d) FAILED\n", (int)sizeof(struct lan_addr_s));
					break;
				}
				if(parselanaddr(lan_addr, argv[++i]) != 0) {
					fprintf(stderr, "can't parse \"%s\" as a valid address or interface name\n", argv[i]);
					free(lan_addr);
				} else {
					LIST_INSERT_HEAD(&lan_addrs, lan_addr, list);
				}
			} else if(0==strcmp(argv[i], "-s"))
				sockpath = argv[++i];
			else if(0==strcmp(argv[i], "-p"))
				pidfilename = argv[++i];
			else if(0==strcmp(argv[i], "-t"))
				ttl = (unsigned char)atoi(argv[++i]);
			else if(0==strcmp(argv[i], "-f"))
				searched_device = argv[++i];
			else
				fprintf(stderr, "unknown commandline option %s.\n", argv[i]);
		}
	}
	if(lan_addrs.lh_first == NULL)
	{
		fprintf(stderr,
		        "Usage: %s [-d] "
#ifdef ENABLE_IPV6
		        "[-6] "
#endif /* ENABLE_IPV6 */
		        "[-s socket] [-p pidfile] [-t TTL] "
		        "[-f device] "
		        "-i <interface> [-i <interface2>] ...\n",
		        argv[0]);
		fprintf(stderr,
		        "\n  <interface> is either an IPv4 address with mask such as\n"
		        "  192.168.1.42/255.255.255.0, or an interface name such as eth0.\n");
		fprintf(stderr,
		        "\n  By default, socket will be open as %s\n"
		        "  and pid written to file %s\n",
		        sockpath, pidfilename);
		return 1;
	}

	/* open log */
	openlog("minissdpd",
	        LOG_CONS|LOG_PID|(debug_flag?LOG_PERROR:0),
			LOG_MINISSDPD);
	if(!debug_flag) /* speed things up and ignore LOG_INFO and LOG_DEBUG */
		setlogmask(LOG_UPTO(LOG_NOTICE));

	if(checkforrunning(pidfilename) < 0)
	{
		syslog(LOG_ERR, "MiniSSDPd is already running. EXITING");
		return 1;
	}

	upnp_bootid = (unsigned int)time(NULL);

	/* set signal handlers */
	memset(&sa, 0, sizeof(struct sigaction));
	sa.sa_handler = sigterm;
	if(sigaction(SIGTERM, &sa, NULL))
	{
		syslog(LOG_ERR, "Failed to set SIGTERM handler. EXITING");
		ret = 1;
		goto quit;
	}
	if(sigaction(SIGINT, &sa, NULL))
	{
		syslog(LOG_ERR, "Failed to set SIGINT handler. EXITING");
		ret = 1;
		goto quit;
	}
	/* open route/interface config changes socket */
	s_ifacewatch = OpenAndConfInterfaceWatchSocket();
	/* open UDP socket(s) for receiving SSDP packets */
	s_ssdp = OpenAndConfSSDPReceiveSocket(0, ttl);
	if(s_ssdp < 0)
	{
		syslog(LOG_ERR, "Cannot open socket for receiving SSDP messages, exiting");
		ret = 1;
		goto quit;
	}
#ifdef ENABLE_IPV6
	if(ipv6) {
		s_ssdp6 = OpenAndConfSSDPReceiveSocket(1, ttl);
		if(s_ssdp6 < 0)
		{
			syslog(LOG_ERR, "Cannot open socket for receiving SSDP messages (IPv6), exiting");
			ret = 1;
			goto quit;
		}
	}
#endif	/* ENABLE_IPV6 */
	/* Open Unix socket to communicate with other programs on
	 * the same machine */
	s_unix = OpenUnixSocket(sockpath);
	if(s_unix < 0)
	{
		syslog(LOG_ERR, "Cannot open unix socket for communicating with clients. Exiting");
		ret = 1;
		goto quit;
	}

	/* drop privileges */
#if 0
	/* if we drop privileges, how to unlink(/var/run/minissdpd.sock) ? */
	if(getuid() == 0) {
		struct passwd * user;
		struct group * group;
		user = getpwnam("nobody");
		if(!user) {
			syslog(LOG_ERR, "getpwnam(\"%s\") : %m", "nobody");
			ret = 1;
			goto quit;
		}
		group = getgrnam("nogroup");
		if(!group) {
			syslog(LOG_ERR, "getgrnam(\"%s\") : %m", "nogroup");
			ret = 1;
			goto quit;
		}
		if(setgid(group->gr_gid) < 0) {
			syslog(LOG_ERR, "setgit(%d) : %m", group->gr_gid);
			ret = 1;
			goto quit;
		}
		if(setuid(user->pw_uid) < 0) {
			syslog(LOG_ERR, "setuid(%d) : %m", user->pw_uid);
			ret = 1;
			goto quit;
		}
	}
#endif

	/* daemonize or in any case get pid ! */
	if(debug_flag)
		pid = getpid();
	else {
#ifdef USE_DAEMON
		if(daemon(0, 0) < 0)
			perror("daemon()");
		pid = getpid();
#else  /* USE_DAEMON */
		pid = daemonize();
#endif /* USE_DAEMON */
	}

	writepidfile(pidfilename, pid);

	/* send M-SEARCH ssdp:all Requests */
	if(s_ssdp >= 0)
		ssdpDiscover(s_ssdp, 0, searched_device);
	if(s_ssdp6 >= 0)
		ssdpDiscover(s_ssdp6, 1, searched_device);

	/* Main loop */
	while(!quitting) {
		/* fill readfds fd_set */
		FD_ZERO(&readfds);
		FD_ZERO(&writefds);

		FD_SET(s_unix, &readfds);
		max_fd = s_unix;
		if(s_ssdp >= 0) {
			FD_SET(s_ssdp, &readfds);
			SET_MAX(max_fd, s_ssdp);
		}
#ifdef ENABLE_IPV6
		if(s_ssdp6 >= 0) {
			FD_SET(s_ssdp6, &readfds);
			SET_MAX(max_fd, s_ssdp6);
		}
#endif /* ENABLE_IPV6 */
		if(s_ifacewatch >= 0) {
			FD_SET(s_ifacewatch, &readfds);
			SET_MAX(max_fd, s_ifacewatch);
		}
		for(req = reqlisthead.lh_first; req; req = req->entries.le_next) {
			if(req->socket >= 0) {
				FD_SET(req->socket, &readfds);
				SET_MAX(max_fd, req->socket);
			}
			if(req->output_buffer_len > 0) {
				FD_SET(req->socket, &writefds);
				SET_MAX(max_fd, req->socket);
			}
		}
		gettimeofday(&now, NULL);
		i = get_sendto_fds(&writefds, &max_fd, &now);
		/* select call */
		if(select(max_fd + 1, &readfds, &writefds, 0, 0) < 0) {
			if(errno != EINTR) {
				syslog(LOG_ERR, "select: %m");
				break;	/* quit */
			}
			continue;	/* try again */
		}
		if(try_sendto(&writefds) < 0) {
			syslog(LOG_ERR, "try_sendto: %m");
			break;
		}
#ifdef ENABLE_IPV6
		if((s_ssdp6 >= 0) && FD_ISSET(s_ssdp6, &readfds))
		{
			sendername6_len = sizeof(struct sockaddr_in6);
			n = recvfrom(s_ssdp6, buf, sizeof(buf), 0,
			             (struct sockaddr *)&sendername6, &sendername6_len);
			if(n<0)
			{
				 /* EAGAIN, EWOULDBLOCK, EINTR : silently ignore (try again next time)
				  * other errors : log to LOG_ERR */
				if(errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR)
					syslog(LOG_ERR, "recvfrom: %m");
			}
			else
			{
				/* Parse and process the packet received */
				/*printf("%.*s", n, buf);*/
				i = ParseSSDPPacket(s_ssdp6, buf, n,
				                    (struct sockaddr *)&sendername6, searched_device);
				syslog(LOG_DEBUG, "** i=%d deltadev=%d **", i, deltadev);
				if(i==0 || (i*deltadev < 0))
				{
					if(deltadev > 0)
						syslog(LOG_NOTICE, "%d new devices added", deltadev);
					else if(deltadev < 0)
						syslog(LOG_NOTICE, "%d devices removed (good-bye!)", -deltadev);
					deltadev = i;
				}
				else if((i*deltadev) >= 0)
				{
					deltadev += i;
				}
			}
		}
#endif	/* ENABLE_IPV6 */
		if((s_ssdp >= 0) && FD_ISSET(s_ssdp, &readfds))
		{
			sendername_len = sizeof(struct sockaddr_in);
			n = recvfrom(s_ssdp, buf, sizeof(buf), 0,
			             (struct sockaddr *)&sendername, &sendername_len);
			if(n<0)
			{
				 /* EAGAIN, EWOULDBLOCK, EINTR : silently ignore (try again next time)
				  * other errors : log to LOG_ERR */
				if(errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR)
					syslog(LOG_ERR, "recvfrom: %m");
			}
			else
			{
				/* Parse and process the packet received */
				/*printf("%.*s", n, buf);*/
				i = ParseSSDPPacket(s_ssdp, buf, n,
				                    (struct sockaddr *)&sendername, searched_device);
				syslog(LOG_DEBUG, "** i=%d deltadev=%d **", i, deltadev);
				if(i==0 || (i*deltadev < 0))
				{
					if(deltadev > 0)
						syslog(LOG_NOTICE, "%d new devices added", deltadev);
					else if(deltadev < 0)
						syslog(LOG_NOTICE, "%d devices removed (good-bye!)", -deltadev);
					deltadev = i;
				}
				else if((i*deltadev) >= 0)
				{
					deltadev += i;
				}
			}
		}
		/* processing unix socket requests */
		for(req = reqlisthead.lh_first; req;) {
			reqnext = req->entries.le_next;
			if((req->socket >= 0) && FD_ISSET(req->socket, &readfds)) {
				processRequest(req);
			}
			if((req->socket >= 0) && FD_ISSET(req->socket, &writefds)) {
				write_buffer(req);
			}
			if(req->socket < 0) {
				LIST_REMOVE(req, entries);
				free(req->output_buffer);
				free(req);
			}
			req = reqnext;
		}
		/* processing new requests */
		if(FD_ISSET(s_unix, &readfds))
		{
			struct reqelem * tmp;
			int s = accept(s_unix, NULL, NULL);
			if(s < 0) {
				syslog(LOG_ERR, "accept(s_unix): %m");
			} else {
				syslog(LOG_INFO, "(s=%d) new request connection", s);
				if(!set_non_blocking(s))
					syslog(LOG_WARNING, "Failed to set new socket non blocking : %m");
				tmp = malloc(sizeof(struct reqelem));
				if(!tmp) {
					syslog(LOG_ERR, "cannot allocate memory for request");
					close(s);
				} else {
					memset(tmp, 0, sizeof(struct reqelem));
					tmp->socket = s;
					LIST_INSERT_HEAD(&reqlisthead, tmp, entries);
				}
			}
		}
		/* processing route/network interface config changes */
		if((s_ifacewatch >= 0) && FD_ISSET(s_ifacewatch, &readfds)) {
			ProcessInterfaceWatch(s_ifacewatch, s_ssdp, s_ssdp6);
		}
	}
	syslog(LOG_DEBUG, "quitting...");
	finalize_sendto();

	/* closing and cleaning everything */
quit:
	if(s_ssdp >= 0) {
		close(s_ssdp);
		s_ssdp = -1;
	}
#ifdef ENABLE_IPV6
	if(s_ssdp6 >= 0) {
		close(s_ssdp6);
		s_ssdp6 = -1;
	}
#endif	/* ENABLE_IPV6 */
	if(s_unix >= 0) {
		close(s_unix);
		s_unix = -1;
		if(unlink(sockpath) < 0)
			syslog(LOG_ERR, "unlink(%s): %m", sockpath);
	}
	if(s_ifacewatch >= 0) {
		close(s_ifacewatch);
		s_ifacewatch = -1;
	}
	/* empty LAN interface/address list */
	while(lan_addrs.lh_first != NULL) {
		lan_addr = lan_addrs.lh_first;
		LIST_REMOVE(lan_addrs.lh_first, list);
		free(lan_addr);
	}
	/* empty device list */
	while(devlist != NULL) {
		struct device * next = devlist->next;
		free(devlist);
		devlist = next;
	}
	/* empty service list */
	while(servicelisthead.lh_first != NULL) {
		struct service * serv = servicelisthead.lh_first;
		LIST_REMOVE(servicelisthead.lh_first, entries);
		free(serv->st);
		free(serv->usn);
		free(serv->server);
		free(serv->location);
		free(serv);
	}
	if(unlink(pidfilename) < 0)
		syslog(LOG_ERR, "unlink(%s): %m", pidfilename);
	closelog();
	return ret;
}

The product reads data past the end, or before the beginning, of the intended buffer.