/*
 * $Id: tcping.c,v 1.17 2004/11/02 09:10:10 mkirchner Exp $
 * 
 * tcping.c
 *
 * Marc Kirchner <mail(at)marc(dash)kirchner(dot)de>
 *
 * 2003-03-14
 *
 * use nonblocking connect to test if a port is reachable
 * exit codes are:
 * -1 an error occured
 * 0  port is open
 * 1  port is closed
 * 2  user timeout
 *
 * This code may be freely redistributed under the terms of the
 * GNU General Public License.
 */

#define VERSION 1.3.4

#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);
}