tcpdump.c

/*
 * 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.
 *
 * Support for splitting captures into multiple files with a maximum
 * file size:
 *
 * Copyright (c) 2001
 *	Seth Webster <swebster@sst.ll.mit.edu>
 */

#ifndef lint
static const char copyright[] =
    "@(#) 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";
static const char rcsid[] =
    "@(#) $Header: /tcpdump/master/tcpdump/tcpdump.c,v 1.176 2002-05-16 10:25:58 guy Exp $ (LBL)";
#endif

/*
 * tcpdump - monitor tcp/ip traffic on an ethernet.
 *
 * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory.
 * Mercilessly hacked and occasionally improved since then via the
 * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>
#include <sys/time.h>

#include <netinet/in.h>

#include <pcap.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>


#include "interface.h"
#include "addrtoname.h"
#include "machdep.h"
#include "setsignal.h"
#include "gmt2local.h"

int aflag;			/* translate network and broadcast addresses */
int dflag;			/* print filter code */
int eflag;			/* print ethernet header */
int fflag;			/* don't translate "foreign" IP address */
int nflag;			/* leave addresses as numbers */
int Nflag;			/* remove domains from printed host names */
int Oflag = 1;			/* run filter code optimizer */
int pflag;			/* don't go promiscuous */
int qflag;			/* quick (shorter) output */
int Rflag = 1;			/* print sequence # field in AH/ESP*/
int sflag = 0;			/* use the libsmi to translate OIDs */
int Sflag;			/* print raw TCP sequence numbers */
int tflag = 1;			/* print packet arrival time */
int uflag = 0;			/* Print undecoded NFS handles */
int vflag;			/* verbose */
int xflag;			/* print packet in hex */
int Xflag;			/* print packet in ascii as well as hex */
off_t Cflag = 0;                /* rotate dump files after this many bytes */
int Aflag = 0;                  /* print packet only in ascii observing LF, CR, TAB, SPACE */

char *espsecret = NULL;		/* ESP secret key */

int packettype;

int infodelay;
int infoprint;

char *program_name;

int32_t thiszone;		/* seconds offset from gmt to local time */

/* Forwards */
static RETSIGTYPE cleanup(int);
static void usage(void) __attribute__((noreturn));

static void dump_and_trunc(u_char *, const struct pcap_pkthdr *, const u_char *);

#ifdef SIGINFO
RETSIGTYPE requestinfo(int);
#endif

/* Length of saved portion of packet. */
int snaplen = DEFAULT_SNAPLEN;

struct printer {
	pcap_handler f;
	int type;
};

static struct printer printers[] = {
	{ arcnet_if_print,	DLT_ARCNET },
	{ ether_if_print,	DLT_EN10MB },
	{ token_if_print,	DLT_IEEE802 },
#ifdef DLT_LANE8023
	{ lane_if_print,        DLT_LANE8023 },
#endif
#ifdef DLT_CIP
	{ cip_if_print,         DLT_CIP },
#endif
#ifdef DLT_ATM_CLIP
	{ cip_if_print,         DLT_ATM_CLIP },
#endif
	{ sl_if_print,		DLT_SLIP },
	{ sl_bsdos_if_print,	DLT_SLIP_BSDOS },
	{ ppp_if_print,		DLT_PPP },
	{ ppp_bsdos_if_print,	DLT_PPP_BSDOS },
	{ fddi_if_print,	DLT_FDDI },
	{ null_if_print,	DLT_NULL },
#ifdef DLT_LOOP
	{ null_if_print,	DLT_LOOP },
#endif
	{ raw_if_print,		DLT_RAW },
	{ atm_if_print,		DLT_ATM_RFC1483 },
#ifdef DLT_C_HDLC
	{ chdlc_if_print,	DLT_C_HDLC },
#endif
#ifdef DLT_HDLC
	{ chdlc_if_print,	DLT_HDLC },
#endif
#ifdef DLT_PPP_SERIAL
	{ ppp_hdlc_if_print,    DLT_PPP_SERIAL },
#endif
#ifdef DLT_PPP_ETHER
	{ pppoe_if_print,	DLT_PPP_ETHER },
#endif
#ifdef DLT_LINUX_SLL
	{ sll_if_print,		DLT_LINUX_SLL },
#endif
#ifdef DLT_IEEE802_11
	{ ieee802_11_if_print,	DLT_IEEE802_11},
#endif
#ifdef DLT_LTALK
	{ ltalk_if_print,	DLT_LTALK },
#endif
#ifdef DLT_PFLOG
	{ pflog_if_print, 	DLT_PFLOG },
#endif
	{ NULL,			0 },
};

static pcap_handler
lookup_printer(int type)
{
	struct printer *p;

	for (p = printers; p->f; ++p)
		if (type == p->type)
			return p->f;

	error("unknown data link type %d", type);
	/* NOTREACHED */
}

static pcap_t *pd;

extern int optind;
extern int opterr;
extern char *optarg;

struct dump_info {
	char	*WFileName;
	pcap_t	*pd;
	pcap_dumper_t *p;
};

int
main(int argc, char **argv)
{
	register int cnt, op, i;
	bpf_u_int32 localnet, netmask;
	register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
	pcap_handler printer;
	struct bpf_program fcode;
	RETSIGTYPE (*oldhandler)(int);
	struct dump_info dumpinfo;
	u_char *pcap_userdata;
	char ebuf[PCAP_ERRBUF_SIZE];

	cnt = -1;
	device = NULL;
	infile = NULL;
	RFileName = NULL;
	WFileName = NULL;
	if ((cp = strrchr(argv[0], '/')) != NULL)
		program_name = cp + 1;
	else
		program_name = argv[0];

	if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
		error("%s", ebuf);

#ifdef LIBSMI
	smiInit("tcpdump");
#endif
	
	opterr = 0;
	while (
	    (op = getopt(argc, argv, "aAc:C:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
		switch (op) {

		case 'a':
			++aflag;
			break;

               case 'A':
                       ++xflag;
                       ++Xflag;
                       ++Aflag;
                       break; 

		case 'c':
			cnt = atoi(optarg);
			if (cnt <= 0)
				error("invalid packet count %s", optarg);
			break;

		case 'C':
			Cflag = atoi(optarg) * 1000000;
			if (Cflag < 0) 
				error("invalid file size %s", optarg);
			break;

		case 'd':
			++dflag;
			break;

		case 'e':
			++eflag;
			break;

		case 'E':
#ifndef HAVE_LIBCRYPTO
			warning("crypto code not compiled in");
#endif
			espsecret = optarg;
			break;

		case 'f':
			++fflag;
			break;

		case 'F':
			infile = optarg;
			break;

		case 'i':
			device = optarg;
			break;

		case 'l':
#ifdef HAVE_SETLINEBUF
			setlinebuf(stdout);
#else
			setvbuf(stdout, NULL, _IOLBF, 0);
#endif
			break;

		case 'n':
			++nflag;
			break;

		case 'N':
			++Nflag;
			break;

		case 'm':
#ifdef LIBSMI
		        if (smiLoadModule(optarg) == 0) {
				error("could not load MIB module %s", optarg);
		        }
			sflag = 1;
#else
			(void)fprintf(stderr, "%s: ignoring option `-m %s' ",
				      program_name, optarg);
			(void)fprintf(stderr, "(no libsmi support)\n");
#endif
			
		case 'O':
			Oflag = 0;
			break;

		case 'p':
			++pflag;
			break;

		case 'q':
			++qflag;
			break;

		case 'r':
			RFileName = optarg;
			break;

		case 'R':
			Rflag = 0;
			break;

		case 's': {
			char *end;

			snaplen = strtol(optarg, &end, 0);
			if (optarg == end || *end != '\0'
			    || snaplen < 0 || snaplen > 65535)
				error("invalid snaplen %s", optarg);
			else if (snaplen == 0)
				snaplen = 65535;
			break;
		}

		case 'S':
			++Sflag;
			break;

		case 't':
			--tflag;
			break;

		case 'T':
			if (strcasecmp(optarg, "vat") == 0)
				packettype = PT_VAT;
			else if (strcasecmp(optarg, "wb") == 0)
				packettype = PT_WB;
			else if (strcasecmp(optarg, "rpc") == 0)
				packettype = PT_RPC;
			else if (strcasecmp(optarg, "rtp") == 0)
				packettype = PT_RTP;
			else if (strcasecmp(optarg, "rtcp") == 0)
				packettype = PT_RTCP;
			else if (strcasecmp(optarg, "snmp") == 0)
				packettype = PT_SNMP;
			else if (strcasecmp(optarg, "cnfp") == 0)
				packettype = PT_CNFP;
			else
				error("unknown packet type `%s'", optarg);
			break;

		case 'u':
			++uflag;
			break;
			
		case 'v':
			++vflag;
			break;

		case 'w':
			WFileName = optarg;
			break;

		case 'x':
			++xflag;
			break;

		case 'X':
    		        ++xflag;
			++Xflag;
			break;

#ifdef YYDEBUG
		case 'Y':
			{
			/* Undocumented flag */
			extern int yydebug;
			yydebug = 1;
			}
			break;
#endif
		default:
			usage();
			/* NOTREACHED */
		}

	if (aflag && nflag)
		error("-a and -n options are incompatible");

	if (tflag > 0)
		thiszone = gmt2local(0);

	if (RFileName != NULL) {
		/*
		 * We don't need network access, so set it back to the user id.
		 * Also, this prevents the user from reading anyone's
		 * trace file.
		 */
		setuid(getuid());

		pd = pcap_open_offline(RFileName, ebuf);
		if (pd == NULL)
			error("%s", ebuf);
		localnet = 0;
		netmask = 0;
		if (fflag != 0)
			error("-f and -r options are incompatible");
	} else {
		if (device == NULL) {
			device = pcap_lookupdev(ebuf);
			if (device == NULL)
				error("%s", ebuf);
		}
		*ebuf = '\0';
		pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
		if (pd == NULL)
			error("%s", ebuf);
		else if (*ebuf)
			warning("%s", ebuf);
		i = pcap_snapshot(pd);
		if (snaplen < i) {
			warning("snaplen raised from %d to %d", snaplen, i);
			snaplen = i;
		}
		if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
			localnet = 0;
			netmask = 0;
			warning("%s", ebuf);
		}
		/*
		 * Let user own process after socket has been opened.
		 */
		setuid(getuid());
	}
	if (infile)
		cmdbuf = read_infile(infile);
	else
		cmdbuf = copy_argv(&argv[optind]);

	if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
		error("%s", pcap_geterr(pd));
	if (dflag) {
		bpf_dump(&fcode, dflag);
		exit(0);
	}
	init_addrtoname(localnet, netmask);

	(void)setsignal(SIGTERM, cleanup);
	(void)setsignal(SIGINT, cleanup);
	/* Cooperate with nohup(1) */
	if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
		(void)setsignal(SIGHUP, oldhandler);

	if (pcap_setfilter(pd, &fcode) < 0)
		error("%s", pcap_geterr(pd));
	if (WFileName) {
		pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
		if (p == NULL)
			error("%s", pcap_geterr(pd));
		if (Cflag != 0) {
			printer = dump_and_trunc;
			dumpinfo.WFileName = WFileName;
			dumpinfo.pd = pd;
			dumpinfo.p = p;
			pcap_userdata = (u_char *)&dumpinfo;
		} else {
			printer = pcap_dump;
			pcap_userdata = (u_char *)p;
		}
	} else {
		printer = lookup_printer(pcap_datalink(pd));
		pcap_userdata = 0;
#ifdef SIGINFO
		(void)setsignal(SIGINFO, requestinfo);
#endif
	}
	if (RFileName == NULL) {
		(void)fprintf(stderr, "%s: listening on %s\n",
		    program_name, device);
		(void)fflush(stderr);
	}
	if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
		(void)fprintf(stderr, "%s: pcap_loop: %s\n",
		    program_name, pcap_geterr(pd));
		cleanup(0);
		pcap_close(pd);
		exit(1);
	}
	if (RFileName == NULL)
		info(1);
	pcap_close(pd);
	exit(0);
}

/* make a clean exit on interrupts */
static RETSIGTYPE
cleanup(int signo)
{

	/* Can't print the summary if reading from a savefile */
	if (pd != NULL && pcap_file(pd) == NULL) {
		(void)fflush(stdout);
		putc('\n', stderr);
		info(1);
	}
	if (signo)
		exit(0);
}

void
info(register int verbose)
{
	struct pcap_stat stat;

	if (pcap_stats(pd, &stat) < 0) {
		(void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
		return;
	}
	if (!verbose)
		fprintf(stderr, "%s: ", program_name);
	(void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
	if (!verbose)
		fputs(", ", stderr);
	else
		putc('\n', stderr);
	(void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
	infoprint = 0;
}

static void
reverse(char *s)
{
	int i, j, c;

	for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
		c = s[i];
		s[i] = s[j];
		s[j] = c;
	}
}


static void
swebitoa(unsigned int n, char *s)
{
	unsigned int i;

	i = 0;
	do {
		s[i++] = n % 10 + '0';
	} while ((n /= 10) > 0);

	s[i] = '\0';
	reverse(s);
}

static void
dump_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
	struct dump_info *info;
	static uint cnt = 2;
	char *name;

	info = (struct dump_info *)user;
	
	/*
	 * XXX - this won't prevent capture files from getting
	 * larger than Cflag - the last packet written to the
	 * file could put it over Cflag.
	 */
	if (ftell((FILE *)info->p) > Cflag) {
		name = (char *) malloc(strlen(info->WFileName) + 4);
		if (name == NULL)
			error("dump_and_trunc: malloc");
		strcpy(name, info->WFileName);
		swebitoa(cnt, name + strlen(info->WFileName));
		cnt++;
		pcap_dump_close(info->p);
		info->p = pcap_dump_open(info->pd, name);
		free(name);
		if (info->p == NULL)
			error("%s", pcap_geterr(pd));
	}

	pcap_dump((u_char *)info->p, h, sp);
}

/* Like default_print() but data need not be aligned */
void
default_print_unaligned(register const u_char *cp, register u_int length)
{
	register u_int i, s;
	register int nshorts;

	if (Xflag) {
		ascii_print(cp, length);
		return;
	}
	nshorts = (u_int) length / sizeof(u_short);
	i = 0;
	while (--nshorts >= 0) {
		if ((i++ % 8) == 0)
			(void)printf("\n\t\t\t");
		s = *cp++;
		(void)printf(" %02x%02x", s, *cp++);
	}
	if (length & 1) {
		if ((i % 8) == 0)
			(void)printf("\n\t\t\t");
		(void)printf(" %02x", *cp);
	}
}

/*
 * By default, print the packet out in hex.
 */
void
default_print(register const u_char *bp, register u_int length)
{
	default_print_unaligned(bp, length);
}

#ifdef SIGINFO
RETSIGTYPE requestinfo(int signo)
{
	if (infodelay)
		++infoprint;
	else
		info(0);
}
#endif

static void
usage(void)
{
	extern char version[];
	extern char pcap_version[];

	(void)fprintf(stderr, "%s version %s\n", program_name, version);
	(void)fprintf(stderr, "libpcap version %s\n", pcap_version);
	(void)fprintf(stderr,
"Usage: %s [-aAdeflnNOpqRStuvxX] [ -c count ] [ -C file_size ]\n", program_name);
	(void)fprintf(stderr,
"\t\t[ -F file ] [ -i interface ] [ -r file ] [ -s snaplen ]\n");
	(void)fprintf(stderr,
"\t\t[ -T type ] [ -w file ] [ -E algo:secret ] [ expression ]\n");
	exit(1);
}