xref: /openbsd-src/usr.sbin/tcpdump/tcpdump.c (revision 3a3fbb3f2e2521ab7c4a56b7ff7462ebd9095ec5) 
1 /*	$OpenBSD: tcpdump.c,v 1.26 2001/12/07 22:34:28 deraadt 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 1.26 2001/12/07 22:34:28 deraadt 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 	{ null_if_print, 	DLT_LOOP },
112 	{ enc_if_print, 	DLT_ENC },
113 	{ pflog_if_print, 	DLT_PFLOG },
114 	{ NULL,			0 },
115 };
116 
117 static pcap_handler
118 lookup_printer(int type)
119 {
120 	struct printer *p;
121 
122 	for (p = printers; p->f; ++p)
123 		if (type == p->type)
124 			return p->f;
125 
126 	error("unknown data link type 0x%x", type);
127 	/* NOTREACHED */
128 }
129 
130 static pcap_t *pd;
131 
132 extern int optind;
133 extern int opterr;
134 extern char *optarg;
135 
136 int
137 main(int argc, char **argv)
138 {
139 	register int cnt, op, i;
140 	bpf_u_int32 localnet, netmask;
141 	register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
142 	pcap_handler printer;
143 	struct bpf_program fcode;
144 	RETSIGTYPE (*oldhandler)(int);
145 	u_char *pcap_userdata;
146 	char ebuf[PCAP_ERRBUF_SIZE];
147 
148 	cnt = -1;
149 	device = NULL;
150 	infile = NULL;
151 	RFileName = NULL;
152 	WFileName = NULL;
153 	if ((cp = strrchr(argv[0], '/')) != NULL)
154 		program_name = cp + 1;
155 	else
156 		program_name = argv[0];
157 
158 	if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
159 		error("%s", ebuf);
160 
161 	opterr = 0;
162 	while ((op = getopt(argc, argv, "ac:defF:i:lnNOpqr:s:StT:vw:xXY")) != -1)
163 		switch (op) {
164 
165 		case 'a':
166 			++aflag;
167 			break;
168 
169 		case 'c':
170 			cnt = atoi(optarg);
171 			if (cnt <= 0)
172 				error("invalid packet count %s", optarg);
173 			break;
174 
175 		case 'd':
176 			++dflag;
177 			break;
178 
179 		case 'e':
180 			++eflag;
181 			break;
182 
183 		case 'f':
184 			++fflag;
185 			break;
186 
187 		case 'F':
188 			infile = optarg;
189 			break;
190 
191 		case 'i':
192 			device = optarg;
193 			break;
194 
195 		case 'l':
196 #ifdef HAVE_SETLINEBUF
197 			setlinebuf(stdout);
198 #else
199 			setvbuf(stdout, NULL, _IOLBF, 0);
200 #endif
201 			break;
202 
203 		case 'n':
204 			++nflag;
205 			break;
206 
207 		case 'N':
208 			++Nflag;
209 			break;
210 
211 		case 'O':
212 			Oflag = 0;
213 			break;
214 
215 		case 'p':
216 			++pflag;
217 			break;
218 
219 		case 'q':
220 			++qflag;
221 			break;
222 
223 		case 'r':
224 			RFileName = optarg;
225 			break;
226 
227 		case 's':
228 			snaplen = atoi(optarg);
229 			if (snaplen <= 0)
230 				error("invalid snaplen %s", optarg);
231 			break;
232 
233 		case 'S':
234 			++Sflag;
235 			break;
236 
237 		case 't':
238 			--tflag;
239 			break;
240 
241 		case 'T':
242 			if (strcasecmp(optarg, "vat") == 0)
243 				packettype = PT_VAT;
244 			else if (strcasecmp(optarg, "wb") == 0)
245 				packettype = PT_WB;
246 			else if (strcasecmp(optarg, "rpc") == 0)
247 				packettype = PT_RPC;
248 			else if (strcasecmp(optarg, "rtp") == 0)
249 				packettype = PT_RTP;
250 			else if (strcasecmp(optarg, "rtcp") == 0)
251 				packettype = PT_RTCP;
252 			else if (strcasecmp(optarg, "cnfp") == 0)
253 				packettype = PT_CNFP;
254 			else if (strcasecmp(optarg, "sack") == 0)
255 				snaplen = SACK_SNAPLEN;
256 			else
257 				error("unknown packet type `%s'", optarg);
258 			break;
259 
260 		case 'v':
261 			++vflag;
262 			break;
263 
264 		case 'w':
265 			WFileName = optarg;
266 			break;
267 #ifdef YYDEBUG
268 		case 'Y':
269 			{
270 			/* Undocumented flag */
271 			extern int yydebug;
272 			yydebug = 1;
273 			}
274 			break;
275 #endif
276 		case 'x':
277 			++xflag;
278 			break;
279 
280 		case 'X':
281 			++Xflag;
282 			if (xflag == 0) ++xflag;
283 			break;
284 
285 		default:
286 			usage();
287 			/* NOTREACHED */
288 		}
289 
290 	if (aflag && nflag)
291 		error("-a and -n options are incompatible");
292 
293 	if (tflag > 0)
294 		thiszone = gmt2local(0);
295 
296 	if (RFileName != NULL) {
297 		/*
298 		 * We don't need network access, so set it back to the user id.
299 		 * Also, this prevents the user from reading anyone's
300 		 * trace file.
301 		 */
302 		seteuid(getuid());
303 		setuid(getuid());
304 
305 		pd = pcap_open_offline(RFileName, ebuf);
306 		if (pd == NULL)
307 			error("%s", ebuf);
308 		localnet = 0;
309 		netmask = 0;
310 		if (fflag != 0)
311 			error("-f and -r options are incompatible");
312 	} else {
313 		if (device == NULL) {
314 			device = pcap_lookupdev(ebuf);
315 			if (device == NULL)
316 				error("%s", ebuf);
317 		}
318 		pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
319 		if (pd == NULL)
320 			error("%s", ebuf);
321 		i = pcap_snapshot(pd);
322 		if (snaplen < i) {
323 			warning("snaplen raised from %d to %d", snaplen, i);
324 			snaplen = i;
325 		}
326 		if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
327 			warning("%s", ebuf);
328 			localnet = 0;
329 			netmask = 0;
330 		}
331 
332 		/*
333 		 * Let user own process after socket has been opened.
334 		 */
335 		seteuid(getuid());
336 		setuid(getuid());
337 	}
338 	if (infile)
339 		cmdbuf = read_infile(infile);
340 	else
341 		cmdbuf = copy_argv(&argv[optind]);
342 
343 	if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
344 		error("%s", pcap_geterr(pd));
345 	if (dflag) {
346 		bpf_dump(&fcode, dflag);
347 		exit(0);
348 	}
349 	init_addrtoname(localnet, netmask);
350 
351 	(void)setsignal(SIGTERM, cleanup);
352 	(void)setsignal(SIGINT, cleanup);
353 	/* Cooperate with nohup(1) */
354 	if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
355 		(void)setsignal(SIGHUP, oldhandler);
356 
357 	if (pcap_setfilter(pd, &fcode) < 0)
358 		error("%s", pcap_geterr(pd));
359 	if (WFileName) {
360 		pcap_dumper_t *p;
361 
362 		p = pcap_dump_open(pd, WFileName);
363 		if (p == NULL)
364 			error("%s", pcap_geterr(pd));
365 		{
366 			FILE *fp = (FILE *)p;	/* XXX touching pcap guts! */
367 			fflush(fp);
368 			setvbuf(fp, NULL, _IONBF, 0);
369 		}
370 		printer = pcap_dump;
371 		pcap_userdata = (u_char *)p;
372 	} else {
373 		printer = lookup_printer(pcap_datalink(pd));
374 		pcap_userdata = 0;
375 	}
376 	if (RFileName == NULL) {
377 		(void)fprintf(stderr, "%s: listening on %s\n",
378 		    program_name, device);
379 		(void)fflush(stderr);
380 	}
381 	if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
382 		(void)fprintf(stderr, "%s: pcap_loop: %s\n",
383 		    program_name, pcap_geterr(pd));
384 		exit(1);
385 	}
386 	pcap_close(pd);
387 	exit(0);
388 }
389 
390 /* make a clean exit on interrupts */
391 RETSIGTYPE
392 cleanup(int signo)
393 {
394 	struct pcap_stat stat;
395 	char buf[1024];
396 
397 	/* Can't print the summary if reading from a savefile */
398 	if (pd != NULL && pcap_file(pd) == NULL) {
399 #if 0
400 		(void)fflush(stdout);	/* XXX unsafe */
401 #endif
402 		(void)write(STDERR_FILENO, "\n", 1);
403 		if (pcap_stats(pd, &stat) < 0) {
404 			(void)snprintf(buf, sizeof buf,
405 			    "pcap_stats: %s\n", pcap_geterr(pd));
406 			write(STDOUT_FILENO, buf, strlen(buf));
407 		} else {
408 			(void)snprintf(buf, sizeof buf,
409 			    "%d packets received by filter\n", stat.ps_recv);
410 			write(STDOUT_FILENO, buf, strlen(buf));
411 			(void)snprintf(buf, sizeof buf,
412 			    "%d packets dropped by kernel\n", stat.ps_drop);
413 			write(STDOUT_FILENO, buf, strlen(buf));
414 		}
415 	}
416 	_exit(0);
417 }
418 
419 /* dump the buffer in `emacs-hexl' style */
420 void
421 default_print_hexl(const u_char *cp, unsigned int length, unsigned int offset)
422 {
423 	unsigned int i, j, jm;
424 	int c;
425 	char ln[128], buf[128];
426 
427 	printf("\n");
428 	for (i = 0; i < length; i += 0x10) {
429 		snprintf(ln, sizeof(ln), "  %04x: ",
430 		    (unsigned int)(i + offset));
431 		jm = length - i;
432 		jm = jm > 16 ? 16 : jm;
433 
434 		for (j = 0; j < jm; j++) {
435 			if ((j % 2) == 1)
436 				snprintf(buf, sizeof(buf), "%02x ",
437 				    (unsigned int)cp[i+j]);
438 			else
439 				snprintf(buf, sizeof(buf), "%02x",
440 				    (unsigned int)cp[i+j]);
441 			strlcat(ln, buf, sizeof ln);
442 		}
443 		for (; j < 16; j++) {
444 			if ((j % 2) == 1)
445 				snprintf(buf, sizeof buf, "   ");
446 			else
447 				snprintf(buf, sizeof buf, "  ");
448 			strlcat(ln, buf, sizeof ln);
449 		}
450 
451 		strlcat(ln, " ", sizeof ln);
452 		for (j = 0; j < jm; j++) {
453 			c = cp[i+j];
454 			c = isprint(c) ? c : '.';
455 			buf[0] = c;
456 			buf[1] = '\0';
457 			strlcat(ln, buf, sizeof ln);
458 		}
459 		printf("%s\n", ln);
460 	}
461 }
462 
463 /* Like default_print() but data need not be aligned */
464 void
465 default_print_unaligned(register const u_char *cp, register u_int length)
466 {
467 	register u_int i, s;
468 	register int nshorts;
469 
470 	if (Xflag) {
471 		/* dump the buffer in `emacs-hexl' style */
472 		default_print_hexl(cp, length, 0);
473 	} else {
474 		/* dump the buffer in old tcpdump style */
475 		nshorts = (u_int) length / sizeof(u_short);
476 		i = 0;
477 		while (--nshorts >= 0) {
478 			if ((i++ % 8) == 0)
479 				(void)printf("\n\t\t\t");
480 			s = *cp++;
481 			(void)printf(" %02x%02x", s, *cp++);
482 		}
483 		if (length & 1) {
484 			if ((i % 8) == 0)
485 				(void)printf("\n\t\t\t");
486 			(void)printf(" %02x", *cp);
487 		}
488 	}
489 }
490 
491 void
492 default_print(register const u_char *bp, register u_int length)
493 {
494 	register const u_short *sp;
495 	register u_int i;
496 	register int nshorts;
497 
498 	if (Xflag) {
499 		/* dump the buffer in `emacs-hexl' style */
500 		default_print_hexl(bp, length, 0);
501 	} else {
502 		/* dump the buffer in old tcpdump style */
503 		if ((long)bp & 1) {
504 			default_print_unaligned(bp, length);
505 			return;
506 		}
507 		sp = (u_short *)bp;
508 		nshorts = (u_int) length / sizeof(u_short);
509 		i = 0;
510 		while (--nshorts >= 0) {
511 			if ((i++ % 8) == 0)
512 				(void)printf("\n\t\t\t");
513 			(void)printf(" %04x", ntohs(*sp++));
514 		}
515 		if (length & 1) {
516 			if ((i % 8) == 0)
517 				(void)printf("\n\t\t\t");
518 			(void)printf(" %02x", *(u_char *)sp);
519 		}
520 	}
521 }
522 
523 __dead void
524 usage(void)
525 {
526 	extern char version[];
527 	extern char pcap_version[];
528 
529 	(void)fprintf(stderr, "%s version %s\n", program_name, version);
530 	(void)fprintf(stderr, "libpcap version %s\n", pcap_version);
531 	(void)fprintf(stderr,
532 "Usage: %s [-adeflnNOpqStvxX] [-c count] [ -F file ]\n", program_name);
533 	(void)fprintf(stderr,
534 "\t\t[ -i interface ] [ -r file ] [ -s snaplen ]\n");
535 	(void)fprintf(stderr,
536 "\t\t[ -T type ] [ -w file ] [ expression ]\n");
537 	exit(1);
538 }
539