xref: /freebsd/contrib/tcpdump/tcpdump.c (revision 0b87f79976047c8f4332bbf7dc03146f6b0de79f) 
1 /*
2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that: (1) source code distributions
7  * retain the above copyright notice and this paragraph in its entirety, (2)
8  * distributions including binary code include the above copyright notice and
9  * this paragraph in its entirety in the documentation or other materials
10  * provided with the distribution, and (3) all advertising materials mentioning
11  * features or use of this software display the following acknowledgement:
12  * ``This product includes software developed by the University of California,
13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14  * the University nor the names of its contributors may be used to endorse
15  * or promote products derived from this software without specific prior
16  * written permission.
17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20  *
21  * Support for splitting captures into multiple files with a maximum
22  * file size:
23  *
24  * Copyright (c) 2001
25  *	Seth Webster <swebster@sst.ll.mit.edu>
26  */
27 
28 #ifndef lint
29 static const char copyright[] =
30     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
31 The Regents of the University of California.  All rights reserved.\n";
32 static const char rcsid[] =
33     "@(#) $Header: /tcpdump/master/tcpdump/tcpdump.c,v 1.173 2001/12/22 22:12:23 guy Exp $ (LBL)";
34 #endif
35 
36 /* $FreeBSD$ */
37 
38 /*
39  * tcpdump - monitor tcp/ip traffic on an ethernet.
40  *
41  * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory.
42  * Mercilessly hacked and occasionally improved since then via the
43  * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
44  */
45 
46 #ifdef HAVE_CONFIG_H
47 #include "config.h"
48 #endif
49 
50 #include <sys/types.h>
51 #include <sys/time.h>
52 
53 #include <netinet/in.h>
54 
55 #include <pcap.h>
56 #include <signal.h>
57 #include <stdio.h>
58 #include <stdlib.h>
59 #include <string.h>
60 #include <unistd.h>
61 #include <ctype.h>
62 
63 
64 #include "interface.h"
65 #include "addrtoname.h"
66 #include "machdep.h"
67 #include "setsignal.h"
68 #include "gmt2local.h"
69 
70 int aflag;			/* translate network and broadcast addresses */
71 int dflag;			/* print filter code */
72 int eflag;			/* print ethernet header */
73 int fflag;			/* don't translate "foreign" IP address */
74 int nflag;			/* leave addresses as numbers */
75 int Nflag;			/* remove domains from printed host names */
76 int Oflag = 1;			/* run filter code optimizer */
77 int pflag;			/* don't go promiscuous */
78 int qflag;			/* quick (shorter) output */
79 int Rflag = 1;			/* print sequence # field in AH/ESP*/
80 int sflag = 0;			/* use the libsmi to translate OIDs */
81 int Sflag;			/* print raw TCP sequence numbers */
82 int tflag = 1;			/* print packet arrival time */
83 int uflag = 0;			/* Print undecoded NFS handles */
84 int vflag;			/* verbose */
85 int xflag;			/* print packet in hex */
86 int Xflag;			/* print packet in ascii as well as hex */
87 off_t Cflag = 0;                /* rotate dump files after this many bytes */
88 
89 char *espsecret = NULL;		/* ESP secret key */
90 
91 int packettype;
92 
93 int infodelay;
94 int infoprint;
95 
96 char *program_name;
97 
98 int32_t thiszone;		/* seconds offset from gmt to local time */
99 
100 /* Forwards */
101 static RETSIGTYPE cleanup(int);
102 static void usage(void) __attribute__((noreturn));
103 
104 static void dump_and_trunc(u_char *, const struct pcap_pkthdr *, const u_char *);
105 
106 #ifdef SIGINFO
107 RETSIGTYPE requestinfo(int);
108 #endif
109 
110 /* Length of saved portion of packet. */
111 int snaplen = DEFAULT_SNAPLEN;
112 
113 struct printer {
114 	pcap_handler f;
115 	int type;
116 };
117 
118 static struct printer printers[] = {
119 	{ arcnet_if_print,	DLT_ARCNET },
120 	{ ether_if_print,	DLT_EN10MB },
121 	{ token_if_print,	DLT_IEEE802 },
122 #ifdef DLT_LANE8023
123 	{ lane_if_print,        DLT_LANE8023 },
124 #endif
125 #ifdef DLT_CIP
126 	{ cip_if_print,         DLT_CIP },
127 #endif
128 #ifdef DLT_ATM_CLIP
129 	{ cip_if_print,         DLT_ATM_CLIP },
130 #endif
131 	{ sl_if_print,		DLT_SLIP },
132 	{ sl_bsdos_if_print,	DLT_SLIP_BSDOS },
133 	{ ppp_if_print,		DLT_PPP },
134 	{ ppp_bsdos_if_print,	DLT_PPP_BSDOS },
135 	{ fddi_if_print,	DLT_FDDI },
136 	{ null_if_print,	DLT_NULL },
137 #ifdef DLT_LOOP
138 	{ null_if_print,	DLT_LOOP },
139 #endif
140 	{ raw_if_print,		DLT_RAW },
141 	{ atm_if_print,		DLT_ATM_RFC1483 },
142 #ifdef DLT_C_HDLC
143 	{ chdlc_if_print,	DLT_C_HDLC },
144 #endif
145 #ifdef DLT_HDLC
146 	{ chdlc_if_print,	DLT_HDLC },
147 #endif
148 #ifdef DLT_PPP_SERIAL
149 	{ ppp_hdlc_if_print,    DLT_PPP_SERIAL },
150 #endif
151 #ifdef DLT_PPP_ETHER
152 	{ pppoe_if_print,	DLT_PPP_ETHER },
153 #endif
154 #ifdef DLT_LINUX_SLL
155 	{ sll_if_print,		DLT_LINUX_SLL },
156 #endif
157 #ifdef DLT_IEEE802_11
158 	{ ieee802_11_if_print,	DLT_IEEE802_11},
159 #endif
160 #ifdef DLT_LTALK
161 	{ ltalk_if_print,	DLT_LTALK },
162 #endif
163 	{ NULL,			0 },
164 };
165 
166 static pcap_handler
167 lookup_printer(int type)
168 {
169 	struct printer *p;
170 
171 	for (p = printers; p->f; ++p)
172 		if (type == p->type)
173 			return p->f;
174 
175 	error("unknown data link type %d", type);
176 	/* NOTREACHED */
177 }
178 
179 static pcap_t *pd;
180 
181 extern int optind;
182 extern int opterr;
183 extern char *optarg;
184 
185 struct dump_info {
186 	char	*WFileName;
187 	pcap_t	*pd;
188 	pcap_dumper_t *p;
189 };
190 
191 int
192 main(int argc, char **argv)
193 {
194 	register int cnt, op, i;
195 	bpf_u_int32 localnet, netmask;
196 	register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
197 	pcap_handler printer;
198 	struct bpf_program fcode;
199 	RETSIGTYPE (*oldhandler)(int);
200 	struct dump_info dumpinfo;
201 	u_char *pcap_userdata;
202 	char ebuf[PCAP_ERRBUF_SIZE];
203 
204 	cnt = -1;
205 	device = NULL;
206 	infile = NULL;
207 	RFileName = NULL;
208 	WFileName = NULL;
209 	if ((cp = strrchr(argv[0], '/')) != NULL)
210 		program_name = cp + 1;
211 	else
212 		program_name = argv[0];
213 
214 	if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
215 		error("%s", ebuf);
216 
217 #ifdef LIBSMI
218 	smiInit("tcpdump");
219 #endif
220 
221 	opterr = 0;
222 	while (
223 	    (op = getopt(argc, argv, "ac:C:deE:fF:i:lm:nNOpqr:Rs:StT:uvw:xXY")) != -1)
224 		switch (op) {
225 
226 		case 'a':
227 			++aflag;
228 			break;
229 
230 		case 'c':
231 			cnt = atoi(optarg);
232 			if (cnt <= 0)
233 				error("invalid packet count %s", optarg);
234 			break;
235 
236 		case 'C':
237 			Cflag = atoi(optarg) * 1000000;
238 			if (Cflag < 0)
239 				error("invalid file size %s", optarg);
240 			break;
241 
242 		case 'd':
243 			++dflag;
244 			break;
245 
246 		case 'e':
247 			++eflag;
248 			break;
249 
250 		case 'E':
251 #ifndef HAVE_LIBCRYPTO
252 			warning("crypto code not compiled in");
253 #endif
254 			espsecret = optarg;
255 			break;
256 
257 		case 'f':
258 			++fflag;
259 			break;
260 
261 		case 'F':
262 			infile = optarg;
263 			break;
264 
265 		case 'i':
266 			device = optarg;
267 			break;
268 
269 		case 'l':
270 #ifdef HAVE_SETLINEBUF
271 			setlinebuf(stdout);
272 #else
273 			setvbuf(stdout, NULL, _IOLBF, 0);
274 #endif
275 			break;
276 
277 		case 'n':
278 			++nflag;
279 			break;
280 
281 		case 'N':
282 			++Nflag;
283 			break;
284 
285 		case 'm':
286 #ifdef LIBSMI
287 		        if (smiLoadModule(optarg) == 0) {
288 				error("could not load MIB module %s", optarg);
289 		        }
290 			sflag = 1;
291 #else
292 			(void)fprintf(stderr, "%s: ignoring option `-m %s' ",
293 				      program_name, optarg);
294 			(void)fprintf(stderr, "(no libsmi support)\n");
295 #endif
296 
297 		case 'O':
298 			Oflag = 0;
299 			break;
300 
301 		case 'p':
302 			++pflag;
303 			break;
304 
305 		case 'q':
306 			++qflag;
307 			break;
308 
309 		case 'r':
310 			RFileName = optarg;
311 			break;
312 
313 		case 'R':
314 			Rflag = 0;
315 			break;
316 
317 		case 's': {
318 			char *end;
319 
320 			snaplen = strtol(optarg, &end, 0);
321 			if (optarg == end || *end != '\0'
322 			    || snaplen < 0 || snaplen > 65535)
323 				error("invalid snaplen %s", optarg);
324 			else if (snaplen == 0)
325 				snaplen = 65535;
326 			break;
327 		}
328 
329 		case 'S':
330 			++Sflag;
331 			break;
332 
333 		case 't':
334 			--tflag;
335 			break;
336 
337 		case 'T':
338 			if (strcasecmp(optarg, "vat") == 0)
339 				packettype = PT_VAT;
340 			else if (strcasecmp(optarg, "wb") == 0)
341 				packettype = PT_WB;
342 			else if (strcasecmp(optarg, "rpc") == 0)
343 				packettype = PT_RPC;
344 			else if (strcasecmp(optarg, "rtp") == 0)
345 				packettype = PT_RTP;
346 			else if (strcasecmp(optarg, "rtcp") == 0)
347 				packettype = PT_RTCP;
348 			else if (strcasecmp(optarg, "snmp") == 0)
349 				packettype = PT_SNMP;
350 			else if (strcasecmp(optarg, "cnfp") == 0)
351 				packettype = PT_CNFP;
352 			else
353 				error("unknown packet type `%s'", optarg);
354 			break;
355 
356 		case 'u':
357 			++uflag;
358 			break;
359 
360 		case 'v':
361 			++vflag;
362 			break;
363 
364 		case 'w':
365 			WFileName = optarg;
366 			break;
367 
368 		case 'x':
369 			++xflag;
370 			break;
371 
372 		case 'X':
373     		        ++xflag;
374 			++Xflag;
375 			break;
376 
377 #ifdef YYDEBUG
378 		case 'Y':
379 			{
380 			/* Undocumented flag */
381 			extern int yydebug;
382 			yydebug = 1;
383 			}
384 			break;
385 #endif
386 		default:
387 			usage();
388 			/* NOTREACHED */
389 		}
390 
391 	if (aflag && nflag)
392 		error("-a and -n options are incompatible");
393 
394 	if (tflag > 0)
395 		thiszone = gmt2local(0);
396 
397 	if (RFileName != NULL) {
398 		/*
399 		 * We don't need network access, so set it back to the user id.
400 		 * Also, this prevents the user from reading anyone's
401 		 * trace file.
402 		 */
403 		setuid(getuid());
404 
405 		pd = pcap_open_offline(RFileName, ebuf);
406 		if (pd == NULL)
407 			error("%s", ebuf);
408 		localnet = 0;
409 		netmask = 0;
410 		if (fflag != 0)
411 			error("-f and -r options are incompatible");
412 	} else {
413 		if (device == NULL) {
414 			device = pcap_lookupdev(ebuf);
415 			if (device == NULL)
416 				error("%s", ebuf);
417 		}
418 		*ebuf = '\0';
419 		pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
420 		if (pd == NULL)
421 			error("%s", ebuf);
422 		else if (*ebuf)
423 			warning("%s", ebuf);
424 		i = pcap_snapshot(pd);
425 		if (snaplen < i) {
426 			warning("snaplen raised from %d to %d", snaplen, i);
427 			snaplen = i;
428 		}
429 		if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
430 			localnet = 0;
431 			netmask = 0;
432 			warning("%s", ebuf);
433 		}
434 		/*
435 		 * Let user own process after socket has been opened.
436 		 */
437 		setuid(getuid());
438 	}
439 	if (infile)
440 		cmdbuf = read_infile(infile);
441 	else
442 		cmdbuf = copy_argv(&argv[optind]);
443 
444 	if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
445 		error("%s", pcap_geterr(pd));
446 	if (dflag) {
447 		bpf_dump(&fcode, dflag);
448 		exit(0);
449 	}
450 	init_addrtoname(localnet, netmask);
451 
452 	(void)setsignal(SIGTERM, cleanup);
453 	(void)setsignal(SIGINT, cleanup);
454 	/* Cooperate with nohup(1) */
455 	if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
456 		(void)setsignal(SIGHUP, oldhandler);
457 
458 	if (pcap_setfilter(pd, &fcode) < 0)
459 		error("%s", pcap_geterr(pd));
460 	if (WFileName) {
461 		pcap_dumper_t *p = pcap_dump_open(pd, WFileName);
462 		if (p == NULL)
463 			error("%s", pcap_geterr(pd));
464 		if (Cflag != 0) {
465 			printer = dump_and_trunc;
466 			dumpinfo.WFileName = WFileName;
467 			dumpinfo.pd = pd;
468 			dumpinfo.p = p;
469 			pcap_userdata = (u_char *)&dumpinfo;
470 		} else {
471 			printer = pcap_dump;
472 			pcap_userdata = (u_char *)p;
473 		}
474 	} else {
475 		printer = lookup_printer(pcap_datalink(pd));
476 		pcap_userdata = 0;
477 #ifdef SIGINFO
478 		(void)setsignal(SIGINFO, requestinfo);
479 #endif
480 	}
481 	if (RFileName == NULL) {
482 		(void)fprintf(stderr, "%s: listening on %s\n",
483 		    program_name, device);
484 		(void)fflush(stderr);
485 	}
486 	if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
487 		(void)fprintf(stderr, "%s: pcap_loop: %s\n",
488 		    program_name, pcap_geterr(pd));
489 		exit(1);
490 	}
491 	if (RFileName == NULL)
492 		info(1);
493 	pcap_close(pd);
494 	exit(0);
495 }
496 
497 /* make a clean exit on interrupts */
498 static RETSIGTYPE
499 cleanup(int signo)
500 {
501 
502 	/* Can't print the summary if reading from a savefile */
503 	if (pd != NULL && pcap_file(pd) == NULL) {
504 		(void)fflush(stdout);
505 		putc('\n', stderr);
506 		info(1);
507 	}
508 	exit(0);
509 }
510 
511 void
512 info(register int verbose)
513 {
514 	struct pcap_stat stat;
515 
516 	if (pcap_stats(pd, &stat) < 0) {
517 		(void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
518 		return;
519 	}
520 	if (!verbose)
521 		fprintf(stderr, "%s: ", program_name);
522 	(void)fprintf(stderr, "%d packets received by filter", stat.ps_recv);
523 	if (!verbose)
524 		fputs(", ", stderr);
525 	else
526 		putc('\n', stderr);
527 	(void)fprintf(stderr, "%d packets dropped by kernel\n", stat.ps_drop);
528 	infoprint = 0;
529 }
530 
531 static void
532 reverse(char *s)
533 {
534 	int i, j, c;
535 
536 	for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
537 		c = s[i];
538 		s[i] = s[j];
539 		s[j] = c;
540 	}
541 }
542 
543 
544 static void
545 swebitoa(unsigned int n, char *s)
546 {
547 	unsigned int i;
548 
549 	i = 0;
550 	do {
551 		s[i++] = n % 10 + '0';
552 	} while ((n /= 10) > 0);
553 
554 	s[i] = '\0';
555 	reverse(s);
556 }
557 
558 static void
559 dump_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
560 {
561 	struct dump_info *info;
562 	static uint cnt = 2;
563 	char *name;
564 
565 	info = (struct dump_info *)user;
566 
567 	/*
568 	 * XXX - this won't prevent capture files from getting
569 	 * larger than Cflag - the last packet written to the
570 	 * file could put it over Cflag.
571 	 */
572 	if (ftell((FILE *)info->p) > Cflag) {
573 		name = (char *) malloc(strlen(info->WFileName) + 4);
574 		if (name == NULL)
575 			error("dump_and_trunc: malloc");
576 		strcpy(name, info->WFileName);
577 		swebitoa(cnt, name + strlen(info->WFileName));
578 		cnt++;
579 		pcap_dump_close(info->p);
580 		info->p = pcap_dump_open(info->pd, name);
581 		free(name);
582 		if (info->p == NULL)
583 			error("%s", pcap_geterr(pd));
584 	}
585 
586 	pcap_dump((u_char *)info->p, h, sp);
587 }
588 
589 /* Like default_print() but data need not be aligned */
590 void
591 default_print_unaligned(register const u_char *cp, register u_int length)
592 {
593 	register u_int i, s;
594 	register int nshorts;
595 
596 	if (Xflag) {
597 		ascii_print(cp, length);
598 		return;
599 	}
600 	nshorts = (u_int) length / sizeof(u_short);
601 	i = 0;
602 	while (--nshorts >= 0) {
603 		if ((i++ % 8) == 0)
604 			(void)printf("\n\t\t\t");
605 		s = *cp++;
606 		(void)printf(" %02x%02x", s, *cp++);
607 	}
608 	if (length & 1) {
609 		if ((i % 8) == 0)
610 			(void)printf("\n\t\t\t");
611 		(void)printf(" %02x", *cp);
612 	}
613 }
614 
615 /*
616  * By default, print the packet out in hex.
617  */
618 void
619 default_print(register const u_char *bp, register u_int length)
620 {
621 	default_print_unaligned(bp, length);
622 }
623 
624 #ifdef SIGINFO
625 RETSIGTYPE requestinfo(int signo)
626 {
627 	if (infodelay)
628 		++infoprint;
629 	else
630 		info(0);
631 }
632 #endif
633 
634 static void
635 usage(void)
636 {
637 	extern char version[];
638 	extern char pcap_version[];
639 
640 	(void)fprintf(stderr, "%s version %s\n", program_name, version);
641 	(void)fprintf(stderr, "libpcap version %s\n", pcap_version);
642 	(void)fprintf(stderr,
643 "Usage: %s [-adeflnNOpqRStuvxX] [ -c count ] [ -C file_size ]\n", program_name);
644 	(void)fprintf(stderr,
645 "\t\t[ -F file ] [ -i interface ] [ -r file ] [ -s snaplen ]\n");
646 	(void)fprintf(stderr,
647 "\t\t[ -T type ] [ -w file ] [ -E algo:secret ] [ expression ]\n");
648 	exit(1);
649 }
650