testprogs/selpolltest.c - platform/external/libpcap - Git at Google

 /*
  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
  *	The Regents of the University of California.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that: (1) source code distributions
  * retain the above copyright notice and this paragraph in its entirety, (2)
  * distributions including binary code include the above copyright notice and
  * this paragraph in its entirety in the documentation or other materials
  * provided with the distribution, and (3) all advertising materials mentioning
  * features or use of this software display the following acknowledgement:
  * ``This product includes software developed by the University of California,
  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  * the University 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  */

 #include "varattrs.h"

 #ifndef lint
 static const char copyright[] _U_ =
     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
 The Regents of the University of California.  All rights reserved.\n";
 #endif

 /*
  * Tests how select() and poll() behave on the selectable file descriptor
  * for a pcap_t.
  *
  * This would be significantly different on Windows, as it'd test
  * how WaitForMultipleObjects() would work on the event handle for a
  * pcap_t.
  */
 #include <pcap.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdarg.h>
 #include <unistd.h>
 #include <errno.h>
 #include <sys/types.h>
 #ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
 #else
 #include <sys/time.h>	/* older UN*Xes */
 #endif
 #include <poll.h>

 #include "pcap/funcattrs.h"

 static char *program_name;

 /* Forwards */
 static void countme(u_char *, const struct pcap_pkthdr *, const u_char *);
 static void PCAP_NORETURN usage(void);
 static void PCAP_NORETURN error(const char *, ...) PCAP_PRINTFLIKE(1, 2);
 static void warning(const char *, ...) PCAP_PRINTFLIKE(1, 2);
 static char *copy_argv(char **);

 static pcap_t *pd;

 int
 main(int argc, char **argv)
 {
 	register int op;
 	bpf_u_int32 localnet, netmask;
 	register char *cp, *cmdbuf, *device;
 	int doselect, dopoll, dotimeout, dononblock, quiet;
 	const char *mechanism;
 	struct bpf_program fcode;
 	char ebuf[PCAP_ERRBUF_SIZE];
 	pcap_if_t *devlist;
 	int selectable_fd = -1;
 	const struct timeval *required_timeout;
 	int status;
 	int packet_count;

 	device = NULL;
 	doselect = 0;
 	dopoll = 0;
 	mechanism = NULL;
 	dotimeout = 0;
 	dononblock = 0;
 	quiet = 0;
 	if ((cp = strrchr(argv[0], '/')) != NULL)
 		program_name = cp + 1;
 	else
 		program_name = argv[0];

 	opterr = 0;
 	while ((op = getopt(argc, argv, "i:sptnq")) != -1) {
 		switch (op) {

 		case 'i':
 			device = optarg;
 			break;

 		case 's':
 			doselect = 1;
 			mechanism = "select() and pcap_dispatch()";
 			break;

 		case 'p':
 			dopoll = 1;
 			mechanism = "poll() and pcap_dispatch()";
 			break;

 		case 't':
 			dotimeout = 1;
 			break;

 		case 'n':
 			dononblock = 1;
 			break;

 		case 'q':
 			quiet = 1;
 			break;

 		default:
 			usage();
 			/* NOTREACHED */
 		}
 	}

 	if (doselect && dopoll) {
 		fprintf(stderr, "selpolltest: choose select (-s) or poll (-p), but not both\n");
 		return 1;
 	}
 	if (dotimeout && !doselect && !dopoll) {
 		fprintf(stderr, "selpolltest: timeout (-t) requires select (-s) or poll (-p)\n");
 		return 1;
 	}
 	if (device == NULL) {
 		if (pcap_findalldevs(&devlist, ebuf) == -1)
 			error("%s", ebuf);
 		if (devlist == NULL)
 			error("no interfaces available for capture");
 		device = strdup(devlist->name);
 		pcap_freealldevs(devlist);
 	}
 	*ebuf = '\0';
 	pd = pcap_open_live(device, 65535, 0, 1000, ebuf);
 	if (pd == NULL)
 		error("%s", ebuf);
 	else if (*ebuf)
 		warning("%s", ebuf);
 	if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
 		localnet = 0;
 		netmask = 0;
 		warning("%s", ebuf);
 	}
 	cmdbuf = copy_argv(&argv[optind]);

 	if (pcap_compile(pd, &fcode, cmdbuf, 1, netmask) < 0)
 		error("%s", pcap_geterr(pd));
 	if (pcap_setfilter(pd, &fcode) < 0)
 		error("%s", pcap_geterr(pd));

 	if (doselect || dopoll) {
 		/*
 		 * We need either an FD on which to do select()/poll()
 		 * or, if there isn't one, a timeout to use in select()/
 		 * poll().
 		 */
 		selectable_fd = pcap_get_selectable_fd(pd);
 		if (selectable_fd == -1) {
 			printf("Listening on %s, using %s, with a timeout\n",
 			    device, mechanism);
 			required_timeout = pcap_get_required_select_timeout(pd);
 			if (required_timeout == NULL)
 				error("select()/poll() isn't supported on %s, even with a timeout",
 				    device);

 			/*
 			 * As we won't be notified by select() or poll()
 			 * that a read can be done, we'll have to periodically
 			 * try reading from the device every time the required
 			 * timeout expires, and we don't want those attempts
 			 * to block if nothing has arrived in that interval,
 			 * so we want to force non-blocking mode.
 			 */
 			dononblock = 1;
 		} else {
 			printf("Listening on %s, using %s\n", device,
 			    mechanism);
 			required_timeout = NULL;
 		}
 	} else
 		printf("Listening on %s, using pcap_dispatch()\n", device);

 	if (dononblock) {
 		if (pcap_setnonblock(pd, 1, ebuf) == -1)
 			error("pcap_setnonblock failed: %s", ebuf);
 	}
 	if (doselect) {
 		for (;;) {
 			fd_set setread, setexcept;
 			struct timeval seltimeout;
 			struct timeval *timeoutp;

 			FD_ZERO(&setread);
 			if (selectable_fd != -1) {
 				FD_SET(selectable_fd, &setread);
 				FD_ZERO(&setexcept);
 				FD_SET(selectable_fd, &setexcept);
 			}
 			required_timeout = pcap_get_required_select_timeout(pd);
 			if (dotimeout) {
 				seltimeout.tv_sec = 0;
 				if (required_timeout != NULL &&
 				    required_timeout->tv_usec < 1000)
 					seltimeout.tv_usec = required_timeout->tv_usec;
 				else
 					seltimeout.tv_usec = 1000;
 				timeoutp = &seltimeout;
 			} else if (required_timeout != NULL) {
 				seltimeout = *required_timeout;
 				timeoutp = &seltimeout;
 			} else {
 				timeoutp = NULL;
 			}
 			status = select((selectable_fd == -1) ?
 			    0 : selectable_fd + 1, &setread, NULL, &setexcept,
 			    timeoutp);
 			if (status == -1) {
 				printf("Select returns error (%s)\n",
 				    strerror(errno));
 			} else {
 				if (!quiet) {
 					if (status == 0)
 						printf("Select timed out: ");
 					else{
 						printf("Select returned a descriptor: ");
 						if (FD_ISSET(selectable_fd, &setread))
 							printf("readable, ");
 						else
 							printf("not readable, ");
 						if (FD_ISSET(selectable_fd, &setexcept))
 							printf("exceptional condition\n");
 						else
 							printf("no exceptional condition\n");
 					}
 				}
 				packet_count = 0;
 				status = pcap_dispatch(pd, -1, countme,
 				    (u_char *)&packet_count);
 				if (status < 0)
 					break;
 				/*
 				 * Don't report this if we're using a
 				 * required timeout and we got no packets,
 				 * because that could be a very short timeout,
 				 * and we don't want to spam the user with
 				 * a ton of "no packets" reports.
 				 */
 				if (status != 0 || packet_count != 0 ||
 				    required_timeout != NULL) {
 					printf("%d packets seen, %d packets counted after select returns\n",
 					    status, packet_count);
 				}
 			}
 		}
 	} else if (dopoll) {
 		for (;;) {
 			struct pollfd fd;
 			int polltimeout;

 			fd.fd = selectable_fd;
 			fd.events = POLLIN;
 			required_timeout = pcap_get_required_select_timeout(pd);
 			if (dotimeout)
 				polltimeout = 1;
 			else if (required_timeout != NULL &&
 			    required_timeout->tv_usec >= 1000)
 				polltimeout = (int)(required_timeout->tv_usec/1000);
 			else
 				polltimeout = -1;
 			status = poll(&fd, (selectable_fd == -1) ? 0 : 1, polltimeout);
 			if (status == -1) {
 				printf("Poll returns error (%s)\n",
 				    strerror(errno));
 			} else {
 				if (!quiet) {
 					if (status == 0)
 						printf("Poll timed out\n");
 					else {
 						printf("Poll returned a descriptor: ");
 						if (fd.revents & POLLIN)
 							printf("readable, ");
 						else
 							printf("not readable, ");
 						if (fd.revents & POLLERR)
 							printf("exceptional condition, ");
 						else
 							printf("no exceptional condition, ");
 						if (fd.revents & POLLHUP)
 							printf("disconnect, ");
 						else
 							printf("no disconnect, ");
 						if (fd.revents & POLLNVAL)
 							printf("invalid\n");
 						else
 							printf("not invalid\n");
 					}
 				}
 				packet_count = 0;
 				status = pcap_dispatch(pd, -1, countme,
 				    (u_char *)&packet_count);
 				if (status < 0)
 					break;
 				/*
 				 * Don't report this if we're using a
 				 * required timeout and we got no packets,
 				 * because that could be a very short timeout,
 				 * and we don't want to spam the user with
 				 * a ton of "no packets" reports.
 				 */
 				if (status != 0 || packet_count != 0 ||
 				    required_timeout != NULL) {
 					printf("%d packets seen, %d packets counted after poll returns\n",
 					    status, packet_count);
 				}
 			}
 		}
 	} else {
 		for (;;) {
 			packet_count = 0;
 			status = pcap_dispatch(pd, -1, countme,
 			    (u_char *)&packet_count);
 			if (status < 0)
 				break;
 			printf("%d packets seen, %d packets counted after pcap_dispatch returns\n",
 			    status, packet_count);
 		}
 	}
 	if (status == -2) {
 		/*
 		 * We got interrupted, so perhaps we didn't
 		 * manage to finish a line we were printing.
 		 * Print an extra newline, just in case.
 		 */
 		putchar('\n');
 	}
 	(void)fflush(stdout);
 	if (status == -1) {
 		/*
 		 * Error.  Report it.
 		 */
 		(void)fprintf(stderr, "%s: pcap_dispatch: %s\n",
 		    program_name, pcap_geterr(pd));
 	}
 	pcap_close(pd);
 	exit(status == -1 ? 1 : 0);
 }

 static void
 countme(u_char *user, const struct pcap_pkthdr *h _U_, const u_char *sp _U_)
 {
 	int *counterp = (int *)user;

 	(*counterp)++;
 }

 static void
 usage(void)
 {
 	(void)fprintf(stderr, "Usage: %s [ -sptnq ] [ -i interface ] [expression]\n",
 	    program_name);
 	exit(1);
 }

 /* VARARGS */
 static void
 error(const char *fmt, ...)
 {
 	va_list ap;

 	(void)fprintf(stderr, "%s: ", program_name);
 	va_start(ap, fmt);
 	(void)vfprintf(stderr, fmt, ap);
 	va_end(ap);
 	if (*fmt) {
 		fmt += strlen(fmt);
 		if (fmt[-1] != '\n')
 			(void)fputc('\n', stderr);
 	}
 	exit(1);
 	/* NOTREACHED */
 }

 /* VARARGS */
 static void
 warning(const char *fmt, ...)
 {
 	va_list ap;

 	(void)fprintf(stderr, "%s: WARNING: ", program_name);
 	va_start(ap, fmt);
 	(void)vfprintf(stderr, fmt, ap);
 	va_end(ap);
 	if (*fmt) {
 		fmt += strlen(fmt);
 		if (fmt[-1] != '\n')
 			(void)fputc('\n', stderr);
 	}
 }

 /*
  * Copy arg vector into a new buffer, concatenating arguments with spaces.
  */
 static char *
 copy_argv(register char **argv)
 {
 	register char **p;
 	register size_t len = 0;
 	char *buf;
 	char *src, *dst;

 	p = argv;
 	if (*p == 0)
 		return 0;

 	while (*p)
 		len += strlen(*p++) + 1;

 	buf = (char *)malloc(len);
 	if (buf == NULL)
 		error("copy_argv: malloc");

 	p = argv;
 	dst = buf;
 	while ((src = *p++) != NULL) {
 		while ((*dst++ = *src++) != '\0')
 			;
 		dst[-1] = ' ';
 	}
 	dst[-1] = '\0';

 	return buf;
 }
	/*
	* Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
	* The Regents of the University of California. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that: (1) source code distributions
	* retain the above copyright notice and this paragraph in its entirety, (2)
	* distributions including binary code include the above copyright notice and
	* this paragraph in its entirety in the documentation or other materials
	* provided with the distribution, and (3) all advertising materials mentioning
	* features or use of this software display the following acknowledgement:
	* ``This product includes software developed by the University of California,
	* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
	* the University 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	*/

	#include "varattrs.h"

	#ifndef lint
	static const char copyright[] _U_ =
	"@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
	The Regents of the University of California. All rights reserved.\n";
	#endif

	/*
	* Tests how select() and poll() behave on the selectable file descriptor
	* for a pcap_t.
	*
	* This would be significantly different on Windows, as it'd test
	* how WaitForMultipleObjects() would work on the event handle for a
	* pcap_t.
	*/
	#include <pcap.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <stdarg.h>
	#include <unistd.h>
	#include <errno.h>
	#include <sys/types.h>
	#ifdef HAVE_SYS_SELECT_H
	#include <sys/select.h>
	#else
	#include <sys/time.h> /* older UNXes /
	#endif
	#include <poll.h>

	#include "pcap/funcattrs.h"

	static char *program_name;

	/* Forwards */
	static void countme(u_char , const struct pcap_pkthdr , const u_char *);
	static void PCAP_NORETURN usage(void);
	static void PCAP_NORETURN error(const char *, ...) PCAP_PRINTFLIKE(1, 2);
	static void warning(const char *, ...) PCAP_PRINTFLIKE(1, 2);
	static char copy_argv(char *);

	static pcap_t *pd;

	int
	main(int argc, char **argv)
	{
	register int op;
	bpf_u_int32 localnet, netmask;
	register char cp, cmdbuf, *device;
	int doselect, dopoll, dotimeout, dononblock, quiet;
	const char *mechanism;
	struct bpf_program fcode;
	char ebuf[PCAP_ERRBUF_SIZE];
	pcap_if_t *devlist;
	int selectable_fd = -1;
	const struct timeval *required_timeout;
	int status;
	int packet_count;

	device = NULL;
	doselect = 0;
	dopoll = 0;
	mechanism = NULL;
	dotimeout = 0;
	dononblock = 0;
	quiet = 0;
	if ((cp = strrchr(argv[0], '/')) != NULL)
	program_name = cp + 1;
	else
	program_name = argv[0];

	opterr = 0;
	while ((op = getopt(argc, argv, "i:sptnq")) != -1) {
	switch (op) {

	case 'i':
	device = optarg;
	break;

	case 's':
	doselect = 1;
	mechanism = "select() and pcap_dispatch()";
	break;

	case 'p':
	dopoll = 1;
	mechanism = "poll() and pcap_dispatch()";
	break;

	case 't':
	dotimeout = 1;
	break;

	case 'n':
	dononblock = 1;
	break;

	case 'q':
	quiet = 1;
	break;

	default:
	usage();
	/* NOTREACHED */
	}
	}

	if (doselect && dopoll) {
	fprintf(stderr, "selpolltest: choose select (-s) or poll (-p), but not both\n");
	return 1;
	}
	if (dotimeout && !doselect && !dopoll) {
	fprintf(stderr, "selpolltest: timeout (-t) requires select (-s) or poll (-p)\n");
	return 1;
	}
	if (device == NULL) {
	if (pcap_findalldevs(&devlist, ebuf) == -1)
	error("%s", ebuf);
	if (devlist == NULL)
	error("no interfaces available for capture");
	device = strdup(devlist->name);
	pcap_freealldevs(devlist);
	}
	*ebuf = '\0';
	pd = pcap_open_live(device, 65535, 0, 1000, ebuf);
	if (pd == NULL)
	error("%s", ebuf);
	else if (*ebuf)
	warning("%s", ebuf);
	if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
	localnet = 0;
	netmask = 0;
	warning("%s", ebuf);
	}
	cmdbuf = copy_argv(&argv[optind]);

	if (pcap_compile(pd, &fcode, cmdbuf, 1, netmask) < 0)
	error("%s", pcap_geterr(pd));
	if (pcap_setfilter(pd, &fcode) < 0)
	error("%s", pcap_geterr(pd));

	if (doselect \|\| dopoll) {
	/*
	* We need either an FD on which to do select()/poll()
	* or, if there isn't one, a timeout to use in select()/
	* poll().
	*/
	selectable_fd = pcap_get_selectable_fd(pd);
	if (selectable_fd == -1) {
	printf("Listening on %s, using %s, with a timeout\n",
	device, mechanism);
	required_timeout = pcap_get_required_select_timeout(pd);
	if (required_timeout == NULL)
	error("select()/poll() isn't supported on %s, even with a timeout",
	device);

	/*
	* As we won't be notified by select() or poll()
	* that a read can be done, we'll have to periodically
	* try reading from the device every time the required
	* timeout expires, and we don't want those attempts
	* to block if nothing has arrived in that interval,
	* so we want to force non-blocking mode.
	*/
	dononblock = 1;
	} else {
	printf("Listening on %s, using %s\n", device,
	mechanism);
	required_timeout = NULL;
	}
	} else
	printf("Listening on %s, using pcap_dispatch()\n", device);

	if (dononblock) {
	if (pcap_setnonblock(pd, 1, ebuf) == -1)
	error("pcap_setnonblock failed: %s", ebuf);
	}
	if (doselect) {
	for (;;) {
	fd_set setread, setexcept;
	struct timeval seltimeout;
	struct timeval *timeoutp;

	FD_ZERO(&setread);
	if (selectable_fd != -1) {
	FD_SET(selectable_fd, &setread);
	FD_ZERO(&setexcept);
	FD_SET(selectable_fd, &setexcept);
	}
	required_timeout = pcap_get_required_select_timeout(pd);
	if (dotimeout) {
	seltimeout.tv_sec = 0;
	if (required_timeout != NULL &&
	required_timeout->tv_usec < 1000)
	seltimeout.tv_usec = required_timeout->tv_usec;
	else
	seltimeout.tv_usec = 1000;
	timeoutp = &seltimeout;
	} else if (required_timeout != NULL) {
	seltimeout = *required_timeout;
	timeoutp = &seltimeout;
	} else {
	timeoutp = NULL;
	}
	status = select((selectable_fd == -1) ?
	0 : selectable_fd + 1, &setread, NULL, &setexcept,
	timeoutp);
	if (status == -1) {
	printf("Select returns error (%s)\n",
	strerror(errno));
	} else {
	if (!quiet) {
	if (status == 0)
	printf("Select timed out: ");
	else{
	printf("Select returned a descriptor: ");
	if (FD_ISSET(selectable_fd, &setread))
	printf("readable, ");
	else
	printf("not readable, ");
	if (FD_ISSET(selectable_fd, &setexcept))
	printf("exceptional condition\n");
	else
	printf("no exceptional condition\n");
	}
	}
	packet_count = 0;
	status = pcap_dispatch(pd, -1, countme,
	(u_char *)&packet_count);
	if (status < 0)
	break;
	/*
	* Don't report this if we're using a
	* required timeout and we got no packets,
	* because that could be a very short timeout,
	* and we don't want to spam the user with
	* a ton of "no packets" reports.
	*/
	if (status != 0 \|\| packet_count != 0 \|\|
	required_timeout != NULL) {
	printf("%d packets seen, %d packets counted after select returns\n",
	status, packet_count);
	}
	}
	}
	} else if (dopoll) {
	for (;;) {
	struct pollfd fd;
	int polltimeout;

	fd.fd = selectable_fd;
	fd.events = POLLIN;
	required_timeout = pcap_get_required_select_timeout(pd);
	if (dotimeout)
	polltimeout = 1;
	else if (required_timeout != NULL &&
	required_timeout->tv_usec >= 1000)
	polltimeout = (int)(required_timeout->tv_usec/1000);
	else
	polltimeout = -1;
	status = poll(&fd, (selectable_fd == -1) ? 0 : 1, polltimeout);
	if (status == -1) {
	printf("Poll returns error (%s)\n",
	strerror(errno));
	} else {
	if (!quiet) {
	if (status == 0)
	printf("Poll timed out\n");
	else {
	printf("Poll returned a descriptor: ");
	if (fd.revents & POLLIN)
	printf("readable, ");
	else
	printf("not readable, ");
	if (fd.revents & POLLERR)
	printf("exceptional condition, ");
	else
	printf("no exceptional condition, ");
	if (fd.revents & POLLHUP)
	printf("disconnect, ");
	else
	printf("no disconnect, ");
	if (fd.revents & POLLNVAL)
	printf("invalid\n");
	else
	printf("not invalid\n");
	}
	}
	packet_count = 0;
	status = pcap_dispatch(pd, -1, countme,
	(u_char *)&packet_count);
	if (status < 0)
	break;
	/*
	* Don't report this if we're using a
	* required timeout and we got no packets,
	* because that could be a very short timeout,
	* and we don't want to spam the user with
	* a ton of "no packets" reports.
	*/
	if (status != 0 \|\| packet_count != 0 \|\|
	required_timeout != NULL) {
	printf("%d packets seen, %d packets counted after poll returns\n",
	status, packet_count);
	}
	}
	}
	} else {
	for (;;) {
	packet_count = 0;
	status = pcap_dispatch(pd, -1, countme,
	(u_char *)&packet_count);
	if (status < 0)
	break;
	printf("%d packets seen, %d packets counted after pcap_dispatch returns\n",
	status, packet_count);
	}
	}
	if (status == -2) {
	/*
	* We got interrupted, so perhaps we didn't
	* manage to finish a line we were printing.
	* Print an extra newline, just in case.
	*/
	putchar('\n');
	}
	(void)fflush(stdout);
	if (status == -1) {
	/*
	* Error. Report it.
	*/
	(void)fprintf(stderr, "%s: pcap_dispatch: %s\n",
	program_name, pcap_geterr(pd));
	}
	pcap_close(pd);
	exit(status == -1 ? 1 : 0);
	}

	static void
	countme(u_char user, const struct pcap_pkthdr h _U_, const u_char *sp _U_)
	{
	int counterp = (int )user;

	(*counterp)++;
	}

	static void
	usage(void)
	{
	(void)fprintf(stderr, "Usage: %s [ -sptnq ] [ -i interface ] [expression]\n",
	program_name);
	exit(1);
	}

	/* VARARGS */
	static void
	error(const char *fmt, ...)
	{
	va_list ap;

	(void)fprintf(stderr, "%s: ", program_name);
	va_start(ap, fmt);
	(void)vfprintf(stderr, fmt, ap);
	va_end(ap);
	if (*fmt) {
	fmt += strlen(fmt);
	if (fmt[-1] != '\n')
	(void)fputc('\n', stderr);
	}
	exit(1);
	/* NOTREACHED */
	}

	/* VARARGS */
	static void
	warning(const char *fmt, ...)
	{
	va_list ap;

	(void)fprintf(stderr, "%s: WARNING: ", program_name);
	va_start(ap, fmt);
	(void)vfprintf(stderr, fmt, ap);
	va_end(ap);
	if (*fmt) {
	fmt += strlen(fmt);
	if (fmt[-1] != '\n')
	(void)fputc('\n', stderr);
	}
	}

	/*
	* Copy arg vector into a new buffer, concatenating arguments with spaces.
	*/
	static char *
	copy_argv(register char **argv)
	{
	register char **p;
	register size_t len = 0;
	char *buf;
	char src, dst;

	p = argv;
	if (*p == 0)
	return 0;

	while (*p)
	len += strlen(*p++) + 1;

	buf = (char *)malloc(len);
	if (buf == NULL)
	error("copy_argv: malloc");

	p = argv;
	dst = buf;
	while ((src = *p++) != NULL) {
	while ((dst++ = src++) != '\0')
	;
	dst[-1] = ' ';
	}
	dst[-1] = '\0';

	return buf;
	}