xref: /openbsd-src/usr.sbin/tcpdump/tcpdump.c (revision 47911bd667ac77dc523b8a13ef40b012dbffa741) 
1 /*	$OpenBSD: tcpdump.c,v 1.30 2002/11/30 13:56:23 mickey Exp $	*/
2 
3 /*
4  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that: (1) source code distributions
9  * retain the above copyright notice and this paragraph in its entirety, (2)
10  * distributions including binary code include the above copyright notice and
11  * this paragraph in its entirety in the documentation or other materials
12  * provided with the distribution, and (3) all advertising materials mentioning
13  * features or use of this software display the following acknowledgement:
14  * ``This product includes software developed by the University of California,
15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
16  * the University nor the names of its contributors may be used to endorse
17  * or promote products derived from this software without specific prior
18  * written permission.
19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
22  */
23 
24 #ifndef lint
25 static const char copyright[] =
26     "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997\n\
27 The Regents of the University of California.  All rights reserved.\n";
28 static const char rcsid[] =
29     "@(#) $Header: /home/cvs/src/usr.sbin/tcpdump/tcpdump.c,v 1.30 2002/11/30 13:56:23 mickey Exp $ (LBL)";
30 #endif
31 
32 /*
33  * tcpdump - monitor tcp/ip traffic on an ethernet.
34  *
35  * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory.
36  * Mercilessly hacked and occasionally improved since then via the
37  * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
38  */
39 
40 #include <sys/types.h>
41 #include <sys/time.h>
42 
43 #include <netinet/in.h>
44 
45 #include <pcap.h>
46 #include <signal.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50 #include <unistd.h>
51 #include <ctype.h>
52 
53 #include "interface.h"
54 #include "addrtoname.h"
55 #include "machdep.h"
56 #include "setsignal.h"
57 #include "gmt2local.h"
58 
59 int aflag;			/* translate network and broadcast addresses */
60 int dflag;			/* print filter code */
61 int eflag;			/* print ethernet header */
62 int fflag;			/* don't translate "foreign" IP address */
63 int nflag;			/* leave addresses as numbers */
64 int Nflag;			/* remove domains from printed host names */
65 int Oflag = 1;			/* run filter code optimizer */
66 int pflag;			/* don't go promiscuous */
67 int qflag;			/* quick (shorter) output */
68 int Sflag;			/* print raw TCP sequence numbers */
69 int tflag = 1;			/* print packet arrival time */
70 int vflag;			/* verbose */
71 int xflag;			/* print packet in hex */
72 int Xflag;			/* print packet in emacs-hexl style */
73 
74 int packettype;
75 
76 
77 char *program_name;
78 
79 int32_t thiszone;		/* seconds offset from gmt to local time */
80 
81 /* Externs */
82 extern void bpf_dump(struct bpf_program *, int);
83 
84 /* Forwards */
85 RETSIGTYPE cleanup(int);
86 extern __dead void usage(void) __attribute__((volatile));
87 
88 /* Length of saved portion of packet. */
89 int snaplen = DEFAULT_SNAPLEN;
90 
91 struct printer {
92 	pcap_handler f;
93 	int type;
94 };
95 
96 /* XXX needed if using old bpf.h */
97 #ifndef DLT_ATM_RFC1483
98 #define DLT_ATM_RFC1483 11
99 #endif
100 
101 static struct printer printers[] = {
102 	{ ether_if_print,	DLT_EN10MB },
103 	{ ether_if_print,	DLT_IEEE802 },
104 	{ sl_if_print,		DLT_SLIP },
105 	{ sl_bsdos_if_print,	DLT_SLIP_BSDOS },
106 	{ ppp_if_print,		DLT_PPP },
107 	{ fddi_if_print,	DLT_FDDI },
108 	{ null_if_print,	DLT_NULL },
109 	{ raw_if_print,		DLT_RAW },
110 	{ atm_if_print,		DLT_ATM_RFC1483 },
111 	{ loop_if_print, 	DLT_LOOP },
112 	{ enc_if_print, 	DLT_ENC },
113 	{ pflog_if_print, 	DLT_PFLOG },
114 	{ pfsync_if_print, 	DLT_PFSYNC },
115 	{ NULL,			0 },
116 };
117 
118 static pcap_handler
119 lookup_printer(int type)
120 {
121 	struct printer *p;
122 
123 	for (p = printers; p->f; ++p)
124 		if (type == p->type)
125 			return p->f;
126 
127 	error("unknown data link type 0x%x", type);
128 	/* NOTREACHED */
129 }
130 
131 static pcap_t *pd;
132 
133 extern int optind;
134 extern int opterr;
135 extern char *optarg;
136 
137 int
138 main(int argc, char **argv)
139 {
140 	register int cnt, op, i;
141 	bpf_u_int32 localnet, netmask;
142 	register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
143 	pcap_handler printer;
144 	struct bpf_program fcode;
145 	RETSIGTYPE (*oldhandler)(int);
146 	u_char *pcap_userdata;
147 	char ebuf[PCAP_ERRBUF_SIZE];
148 
149 	cnt = -1;
150 	device = NULL;
151 	infile = NULL;
152 	RFileName = NULL;
153 	WFileName = NULL;
154 	if ((cp = strrchr(argv[0], '/')) != NULL)
155 		program_name = cp + 1;
156 	else
157 		program_name = argv[0];
158 
159 	if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
160 		error("%s", ebuf);
161 
162 	opterr = 0;
163 	while ((op = getopt(argc, argv, "ac:defF:i:lnNOpqr:s:StT:vw:xXY")) != -1)
164 		switch (op) {
165 
166 		case 'a':
167 			++aflag;
168 			break;
169 
170 		case 'c':
171 			cnt = atoi(optarg);
172 			if (cnt <= 0)
173 				error("invalid packet count %s", optarg);
174 			break;
175 
176 		case 'd':
177 			++dflag;
178 			break;
179 
180 		case 'e':
181 			++eflag;
182 			break;
183 
184 		case 'f':
185 			++fflag;
186 			break;
187 
188 		case 'F':
189 			infile = optarg;
190 			break;
191 
192 		case 'i':
193 			device = optarg;
194 			break;
195 
196 		case 'l':
197 #ifdef HAVE_SETLINEBUF
198 			setlinebuf(stdout);
199 #else
200 			setvbuf(stdout, NULL, _IOLBF, 0);
201 #endif
202 			break;
203 
204 		case 'n':
205 			++nflag;
206 			break;
207 
208 		case 'N':
209 			++Nflag;
210 			break;
211 
212 		case 'O':
213 			Oflag = 0;
214 			break;
215 
216 		case 'p':
217 			++pflag;
218 			break;
219 
220 		case 'q':
221 			++qflag;
222 			break;
223 
224 		case 'r':
225 			RFileName = optarg;
226 			break;
227 
228 		case 's':
229 			snaplen = atoi(optarg);
230 			if (snaplen <= 0)
231 				error("invalid snaplen %s", optarg);
232 			break;
233 
234 		case 'S':
235 			++Sflag;
236 			break;
237 
238 		case 't':
239 			--tflag;
240 			break;
241 
242 		case 'T':
243 			if (strcasecmp(optarg, "vat") == 0)
244 				packettype = PT_VAT;
245 			else if (strcasecmp(optarg, "wb") == 0)
246 				packettype = PT_WB;
247 			else if (strcasecmp(optarg, "rpc") == 0)
248 				packettype = PT_RPC;
249 			else if (strcasecmp(optarg, "rtp") == 0)
250 				packettype = PT_RTP;
251 			else if (strcasecmp(optarg, "rtcp") == 0)
252 				packettype = PT_RTCP;
253 			else if (strcasecmp(optarg, "cnfp") == 0)
254 				packettype = PT_CNFP;
255 			else if (strcasecmp(optarg, "sack") == 0)
256 				snaplen = SACK_SNAPLEN;
257 			else
258 				error("unknown packet type `%s'", optarg);
259 			break;
260 
261 		case 'v':
262 			++vflag;
263 			break;
264 
265 		case 'w':
266 			WFileName = optarg;
267 			break;
268 #ifdef YYDEBUG
269 		case 'Y':
270 			{
271 			/* Undocumented flag */
272 			extern int yydebug;
273 			yydebug = 1;
274 			}
275 			break;
276 #endif
277 		case 'x':
278 			++xflag;
279 			break;
280 
281 		case 'X':
282 			++Xflag;
283 			if (xflag == 0) ++xflag;
284 			break;
285 
286 		default:
287 			usage();
288 			/* NOTREACHED */
289 		}
290 
291 	if (aflag && nflag)
292 		error("-a and -n options are incompatible");
293 
294 	if (tflag > 0)
295 		thiszone = gmt2local(0);
296 
297 	if (RFileName != NULL) {
298 		/*
299 		 * We don't need network access, so set it back to the user id.
300 		 * Also, this prevents the user from reading anyone's
301 		 * trace file.
302 		 */
303 		seteuid(getuid());
304 		setuid(getuid());
305 
306 		pd = pcap_open_offline(RFileName, ebuf);
307 		if (pd == NULL)
308 			error("%s", ebuf);
309 		localnet = 0;
310 		netmask = 0;
311 		if (fflag != 0)
312 			error("-f and -r options are incompatible");
313 	} else {
314 		if (device == NULL) {
315 			device = pcap_lookupdev(ebuf);
316 			if (device == NULL)
317 				error("%s", ebuf);
318 		}
319 		pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
320 		if (pd == NULL)
321 			error("%s", ebuf);
322 		i = pcap_snapshot(pd);
323 		if (snaplen < i) {
324 			warning("snaplen raised from %d to %d", snaplen, i);
325 			snaplen = i;
326 		}
327 		if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
328 			warning("%s", ebuf);
329 			localnet = 0;
330 			netmask = 0;
331 		}
332 
333 		/*
334 		 * Let user own process after socket has been opened.
335 		 */
336 		seteuid(getuid());
337 		setuid(getuid());
338 	}
339 	if (infile)
340 		cmdbuf = read_infile(infile);
341 	else
342 		cmdbuf = copy_argv(&argv[optind]);
343 
344 	if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
345 		error("%s", pcap_geterr(pd));
346 	if (dflag) {
347 		bpf_dump(&fcode, dflag);
348 		exit(0);
349 	}
350 	init_addrtoname(localnet, netmask);
351 
352 	(void)setsignal(SIGTERM, cleanup);
353 	(void)setsignal(SIGINT, cleanup);
354 	/* Cooperate with nohup(1) */
355 	if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
356 		(void)setsignal(SIGHUP, oldhandler);
357 
358 	if (pcap_setfilter(pd, &fcode) < 0)
359 		error("%s", pcap_geterr(pd));
360 	if (WFileName) {
361 		pcap_dumper_t *p;
362 
363 		p = pcap_dump_open(pd, WFileName);
364 		if (p == NULL)
365 			error("%s", pcap_geterr(pd));
366 		{
367 			FILE *fp = (FILE *)p;	/* XXX touching pcap guts! */
368 			fflush(fp);
369 			setvbuf(fp, NULL, _IONBF, 0);
370 		}
371 		printer = pcap_dump;
372 		pcap_userdata = (u_char *)p;
373 	} else {
374 		printer = lookup_printer(pcap_datalink(pd));
375 		pcap_userdata = 0;
376 	}
377 	if (RFileName == NULL) {
378 		(void)fprintf(stderr, "%s: listening on %s\n",
379 		    program_name, device);
380 		(void)fflush(stderr);
381 	}
382 	if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
383 		(void)fprintf(stderr, "%s: pcap_loop: %s\n",
384 		    program_name, pcap_geterr(pd));
385 		exit(1);
386 	}
387 	pcap_close(pd);
388 	exit(0);
389 }
390 
391 /* make a clean exit on interrupts */
392 RETSIGTYPE
393 cleanup(int signo)
394 {
395 	struct pcap_stat stat;
396 	char buf[1024];
397 
398 	/* Can't print the summary if reading from a savefile */
399 	if (pd != NULL && pcap_file(pd) == NULL) {
400 #if 0
401 		(void)fflush(stdout);	/* XXX unsafe */
402 #endif
403 		(void)write(STDERR_FILENO, "\n", 1);
404 		if (pcap_stats(pd, &stat) < 0) {
405 			(void)snprintf(buf, sizeof buf,
406 			    "pcap_stats: %s\n", pcap_geterr(pd));
407 			write(STDOUT_FILENO, buf, strlen(buf));
408 		} else {
409 			(void)snprintf(buf, sizeof buf,
410 			    "%d packets received by filter\n", stat.ps_recv);
411 			write(STDOUT_FILENO, buf, strlen(buf));
412 			(void)snprintf(buf, sizeof buf,
413 			    "%d packets dropped by kernel\n", stat.ps_drop);
414 			write(STDOUT_FILENO, buf, strlen(buf));
415 		}
416 	}
417 	_exit(0);
418 }
419 
420 /* dump the buffer in `emacs-hexl' style */
421 void
422 default_print_hexl(const u_char *cp, unsigned int length, unsigned int offset)
423 {
424 	unsigned int i, j, jm;
425 	int c;
426 	char ln[128], buf[128];
427 
428 	printf("\n");
429 	for (i = 0; i < length; i += 0x10) {
430 		snprintf(ln, sizeof(ln), "  %04x: ",
431 		    (unsigned int)(i + offset));
432 		jm = length - i;
433 		jm = jm > 16 ? 16 : jm;
434 
435 		for (j = 0; j < jm; j++) {
436 			if ((j % 2) == 1)
437 				snprintf(buf, sizeof(buf), "%02x ",
438 				    (unsigned int)cp[i+j]);
439 			else
440 				snprintf(buf, sizeof(buf), "%02x",
441 				    (unsigned int)cp[i+j]);
442 			strlcat(ln, buf, sizeof ln);
443 		}
444 		for (; j < 16; j++) {
445 			if ((j % 2) == 1)
446 				snprintf(buf, sizeof buf, "   ");
447 			else
448 				snprintf(buf, sizeof buf, "  ");
449 			strlcat(ln, buf, sizeof ln);
450 		}
451 
452 		strlcat(ln, " ", sizeof ln);
453 		for (j = 0; j < jm; j++) {
454 			c = cp[i+j];
455 			c = isprint(c) ? c : '.';
456 			buf[0] = c;
457 			buf[1] = '\0';
458 			strlcat(ln, buf, sizeof ln);
459 		}
460 		printf("%s\n", ln);
461 	}
462 }
463 
464 /* Like default_print() but data need not be aligned */
465 void
466 default_print_unaligned(register const u_char *cp, register u_int length)
467 {
468 	register u_int i, s;
469 	register int nshorts;
470 
471 	if (Xflag) {
472 		/* dump the buffer in `emacs-hexl' style */
473 		default_print_hexl(cp, length, 0);
474 	} else {
475 		/* dump the buffer in old tcpdump style */
476 		nshorts = (u_int) length / sizeof(u_short);
477 		i = 0;
478 		while (--nshorts >= 0) {
479 			if ((i++ % 8) == 0)
480 				(void)printf("\n\t\t\t");
481 			s = *cp++;
482 			(void)printf(" %02x%02x", s, *cp++);
483 		}
484 		if (length & 1) {
485 			if ((i % 8) == 0)
486 				(void)printf("\n\t\t\t");
487 			(void)printf(" %02x", *cp);
488 		}
489 	}
490 }
491 
492 void
493 default_print(register const u_char *bp, register u_int length)
494 {
495 	register const u_short *sp;
496 	register u_int i;
497 	register int nshorts;
498 
499 	if (Xflag) {
500 		/* dump the buffer in `emacs-hexl' style */
501 		default_print_hexl(bp, length, 0);
502 	} else {
503 		/* dump the buffer in old tcpdump style */
504 		if ((long)bp & 1) {
505 			default_print_unaligned(bp, length);
506 			return;
507 		}
508 		sp = (u_short *)bp;
509 		nshorts = (u_int) length / sizeof(u_short);
510 		i = 0;
511 		while (--nshorts >= 0) {
512 			if ((i++ % 8) == 0)
513 				(void)printf("\n\t\t\t");
514 			(void)printf(" %04x", ntohs(*sp++));
515 		}
516 		if (length & 1) {
517 			if ((i % 8) == 0)
518 				(void)printf("\n\t\t\t");
519 			(void)printf(" %02x", *(u_char *)sp);
520 		}
521 	}
522 }
523 
524 __dead void
525 usage(void)
526 {
527 	extern char version[];
528 	extern char pcap_version[];
529 
530 	(void)fprintf(stderr, "%s version %s\n", program_name, version);
531 	(void)fprintf(stderr, "libpcap version %s\n", pcap_version);
532 	(void)fprintf(stderr,
533 "Usage: %s [-adeflnNOpqStvxX] [-c count] [ -F file ]\n", program_name);
534 	(void)fprintf(stderr,
535 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
536 	(void)fprintf(stderr,
537 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
538 	exit(1);
539 }
540