/*
 * tcping.c
 *
 * Copyright (c) 2002-2008 Marc Kirchner <mail(at)marc(dash)kirchner(dot)de>
 *
 * tcping is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * tcping 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with ms++. If not, see <http://www.gnu.org/licenses/>.
 *
 * tcping does a nonblocking connect to test if a port is reachable.
 * Its exit codes are:
 *     -1 an error occured
 *     0  port is open
 *     1  port is closed
 *     2  user timeout
 */

#define VERSION 1.3.5

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#include <unistd.h>
#include <sys/time.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <netdb.h>

void usage();

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

	int sockfd;
	struct sockaddr_in addr;
	struct hostent *host;
	int error = 0;
	int ret;
	socklen_t errlen;
	struct timeval timeout;
	fd_set fdrset, fdwset;
	int verbose=1;
	int c;
	char *cptr;
	long timeout_sec=0, timeout_usec=0;
	int port=0;

	if (argc < 3)  {
		usage(argv[0]);
	}
	
	while((c = getopt(argc, argv, "qt:u:")) != -1) {
		switch(c) {
			case 'q':
				verbose = 0;
				break;
			case 't':
				cptr = NULL;
				timeout_sec = strtol(optarg, &cptr, 10);
				if (cptr == optarg)
					usage(argv[0]);
				break;
			case 'u':
				cptr = NULL;
				timeout_usec = strtol(optarg, &cptr, 10);
				if (cptr == optarg)
					usage(argv[0]);
				break;
			default:
				usage(argv[0]);
				break;
		}
	}
	
	sockfd = socket (AF_INET, SOCK_STREAM, 0);

	memset(&addr, 0, sizeof(addr));

	if ((host = gethostbyname(argv[optind])) == NULL) {
		if (verbose)
#ifdef HAVE_HSTRERROR
			fprintf(stderr, "error: %s\n", hstrerror(h_errno));
#else
			fprintf(stderr, "error: host not found");
#endif
		exit(-1);
	}
	
	memcpy(&addr.sin_addr, host->h_addr_list[0], host->h_length);
	addr.sin_family = host->h_addrtype; /* always AF_INET */
	if (argv[optind+1]) {
		cptr = NULL;
		port = strtol(argv[optind+1], &cptr, 10);
		if (cptr == argv[optind+1])
			usage(argv[0]);
	} else {
		usage(argv[0]);
	}
	addr.sin_port = htons(port);

	fcntl(sockfd, F_SETFL, O_NONBLOCK);
	if ((ret = connect(sockfd, (struct sockaddr *) &addr, sizeof(addr))) != 0) {
		if (errno != EINPROGRESS) {
#ifdef HAVE_SOLARIS
			/* solaris immediately returns ECONNREFUSED on local ports */
			if (errno == ECONNREFUSED) {
				if (verbose) 
					fprintf(stdout, "%s port %s closed.\n", argv[optind], argv[optind+1]);
				close(sockfd);
				return(1);
			} else {
#endif	
				if (verbose)
					fprintf(stderr, "error: %s port %s: %s\n", argv[optind], argv[optind+1], strerror(errno));
				return (-1);
#ifdef HAVE_SOLARIS
			}
#endif	
		}

		FD_ZERO(&fdrset);
		FD_SET(sockfd, &fdrset);
		fdwset = fdrset;

		timeout.tv_sec=timeout_sec + timeout_usec / 1000000;
		timeout.tv_usec=timeout_usec % 1000000;

		if ((ret = select(sockfd+1, &fdrset, &fdwset, NULL, timeout.tv_sec+timeout.tv_usec > 0 ? &timeout : NULL)) == 0) {
			/* timeout */
			close(sockfd);
			if (verbose)
				fprintf(stdout, "%s port %s user timeout.\n", argv[optind], argv[optind+1]);
			return(2);
		}
		if (FD_ISSET(sockfd, &fdrset) || FD_ISSET(sockfd, &fdwset)) {
			errlen = sizeof(error);
			if ((ret=getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, &errlen)) != 0) {
				/* getsockopt error */
				if (verbose)
					fprintf(stderr, "error: %s port %s: getsockopt: %s\n", argv[optind], argv[optind+1], strerror(errno));
				close(sockfd);
				return(-1);
			}
			if (error != 0) {
				if (verbose) 
					fprintf(stdout, "%s port %s closed.\n", argv[optind], argv[optind+1]);
				close(sockfd);
				return(1);
			}
		} else {
			if (verbose)
				fprintf(stderr, "error: select: sockfd not set\n");
			exit(-1);
		}
	}
	/* OK, connection established */
	close(sockfd);
	if (verbose)
		fprintf(stdout, "%s port %s open.\n", argv[optind], argv[optind+1]);
	return 0;
}

void usage(char *prog) {
	fprintf(stderr, "error: Usage: %s [-q] [-t timeout_sec] [-u timeout_usec] <host> <port>\n", prog);
		exit(-1);
}