xref: /openbsd-src/usr.sbin/tcpdump/tcpdump.c (revision db3296cf5c1dd9058ceecc3a29fe4aaa0bd26000) 
1 /*	$OpenBSD: tcpdump.c,v 1.32 2003/07/17 08:45:37 markus 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 1.32 2003/07/17 08:45:37 markus 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 extern int esp_init(char *);
84 
85 /* Forwards */
86 RETSIGTYPE cleanup(int);
87 extern __dead void usage(void) __attribute__((volatile));
88 
89 /* Length of saved portion of packet. */
90 int snaplen = DEFAULT_SNAPLEN;
91 
92 struct printer {
93 	pcap_handler f;
94 	int type;
95 };
96 
97 /* XXX needed if using old bpf.h */
98 #ifndef DLT_ATM_RFC1483
99 #define DLT_ATM_RFC1483 11
100 #endif
101 
102 static struct printer printers[] = {
103 	{ ether_if_print,	DLT_EN10MB },
104 	{ ether_if_print,	DLT_IEEE802 },
105 	{ sl_if_print,		DLT_SLIP },
106 	{ sl_bsdos_if_print,	DLT_SLIP_BSDOS },
107 	{ ppp_if_print,		DLT_PPP },
108 	{ fddi_if_print,	DLT_FDDI },
109 	{ null_if_print,	DLT_NULL },
110 	{ raw_if_print,		DLT_RAW },
111 	{ atm_if_print,		DLT_ATM_RFC1483 },
112 	{ loop_if_print, 	DLT_LOOP },
113 	{ enc_if_print, 	DLT_ENC },
114 	{ pflog_if_print, 	DLT_PFLOG },
115 	{ pflog_old_if_print, 	DLT_OLD_PFLOG },
116 	{ pfsync_if_print, 	DLT_PFSYNC },
117 	{ NULL,			0 },
118 };
119 
120 static pcap_handler
121 lookup_printer(int type)
122 {
123 	struct printer *p;
124 
125 	for (p = printers; p->f; ++p)
126 		if (type == p->type)
127 			return p->f;
128 
129 	error("unknown data link type 0x%x", type);
130 	/* NOTREACHED */
131 }
132 
133 static pcap_t *pd;
134 
135 extern int optind;
136 extern int opterr;
137 extern char *optarg;
138 
139 int
140 main(int argc, char **argv)
141 {
142 	register int cnt, op, i;
143 	bpf_u_int32 localnet, netmask;
144 	register char *cp, *infile, *cmdbuf, *device, *RFileName, *WFileName;
145 	pcap_handler printer;
146 	struct bpf_program fcode;
147 	RETSIGTYPE (*oldhandler)(int);
148 	u_char *pcap_userdata;
149 	char ebuf[PCAP_ERRBUF_SIZE];
150 
151 	cnt = -1;
152 	device = NULL;
153 	infile = NULL;
154 	RFileName = NULL;
155 	WFileName = NULL;
156 	if ((cp = strrchr(argv[0], '/')) != NULL)
157 		program_name = cp + 1;
158 	else
159 		program_name = argv[0];
160 
161 	if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
162 		error("%s", ebuf);
163 
164 	opterr = 0;
165 	while ((op = getopt(argc, argv, "ac:deE:fF:i:lnNOpqr:s:StT:vw:xXY")) != -1)
166 		switch (op) {
167 
168 		case 'a':
169 			++aflag;
170 			break;
171 
172 		case 'c':
173 			cnt = atoi(optarg);
174 			if (cnt <= 0)
175 				error("invalid packet count %s", optarg);
176 			break;
177 
178 		case 'd':
179 			++dflag;
180 			break;
181 
182 		case 'e':
183 			++eflag;
184 			break;
185 
186 		case 'f':
187 			++fflag;
188 			break;
189 
190 		case 'F':
191 			infile = optarg;
192 			break;
193 
194 		case 'i':
195 			device = optarg;
196 			break;
197 
198 		case 'l':
199 #ifdef HAVE_SETLINEBUF
200 			setlinebuf(stdout);
201 #else
202 			setvbuf(stdout, NULL, _IOLBF, 0);
203 #endif
204 			break;
205 
206 		case 'n':
207 			++nflag;
208 			break;
209 
210 		case 'N':
211 			++Nflag;
212 			break;
213 
214 		case 'O':
215 			Oflag = 0;
216 			break;
217 
218 		case 'p':
219 			++pflag;
220 			break;
221 
222 		case 'q':
223 			++qflag;
224 			break;
225 
226 		case 'r':
227 			RFileName = optarg;
228 			break;
229 
230 		case 's':
231 			snaplen = atoi(optarg);
232 			if (snaplen <= 0)
233 				error("invalid snaplen %s", optarg);
234 			break;
235 
236 		case 'S':
237 			++Sflag;
238 			break;
239 
240 		case 't':
241 			--tflag;
242 			break;
243 
244 		case 'T':
245 			if (strcasecmp(optarg, "vat") == 0)
246 				packettype = PT_VAT;
247 			else if (strcasecmp(optarg, "wb") == 0)
248 				packettype = PT_WB;
249 			else if (strcasecmp(optarg, "rpc") == 0)
250 				packettype = PT_RPC;
251 			else if (strcasecmp(optarg, "rtp") == 0)
252 				packettype = PT_RTP;
253 			else if (strcasecmp(optarg, "rtcp") == 0)
254 				packettype = PT_RTCP;
255 			else if (strcasecmp(optarg, "cnfp") == 0)
256 				packettype = PT_CNFP;
257 			else if (strcasecmp(optarg, "sack") == 0)
258 				snaplen = SACK_SNAPLEN;
259 			else
260 				error("unknown packet type `%s'", optarg);
261 			break;
262 
263 		case 'v':
264 			++vflag;
265 			break;
266 
267 		case 'w':
268 			WFileName = optarg;
269 			break;
270 #ifdef YYDEBUG
271 		case 'Y':
272 			{
273 			/* Undocumented flag */
274 			extern int yydebug;
275 			yydebug = 1;
276 			}
277 			break;
278 #endif
279 		case 'x':
280 			++xflag;
281 			break;
282 
283 		case 'X':
284 			++Xflag;
285 			if (xflag == 0) ++xflag;
286 			break;
287 
288 		case 'E':
289 			if (esp_init(optarg) < 0)
290 				error("bad esp specification `%s'", optarg);
291 			break;
292 
293 		default:
294 			usage();
295 			/* NOTREACHED */
296 		}
297 
298 	if (aflag && nflag)
299 		error("-a and -n options are incompatible");
300 
301 	if (tflag > 0)
302 		thiszone = gmt2local(0);
303 
304 	if (RFileName != NULL) {
305 		/*
306 		 * We don't need network access, so set it back to the user id.
307 		 * Also, this prevents the user from reading anyone's
308 		 * trace file.
309 		 */
310 		seteuid(getuid());
311 		setuid(getuid());
312 
313 		pd = pcap_open_offline(RFileName, ebuf);
314 		if (pd == NULL)
315 			error("%s", ebuf);
316 		localnet = 0;
317 		netmask = 0;
318 		if (fflag != 0)
319 			error("-f and -r options are incompatible");
320 	} else {
321 		if (device == NULL) {
322 			device = pcap_lookupdev(ebuf);
323 			if (device == NULL)
324 				error("%s", ebuf);
325 		}
326 		pd = pcap_open_live(device, snaplen, !pflag, 1000, ebuf);
327 		if (pd == NULL)
328 			error("%s", ebuf);
329 		i = pcap_snapshot(pd);
330 		if (snaplen < i) {
331 			warning("snaplen raised from %d to %d", snaplen, i);
332 			snaplen = i;
333 		}
334 		if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
335 			warning("%s", ebuf);
336 			localnet = 0;
337 			netmask = 0;
338 		}
339 
340 		/*
341 		 * Let user own process after socket has been opened.
342 		 */
343 		seteuid(getuid());
344 		setuid(getuid());
345 	}
346 	if (infile)
347 		cmdbuf = read_infile(infile);
348 	else
349 		cmdbuf = copy_argv(&argv[optind]);
350 
351 	if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
352 		error("%s", pcap_geterr(pd));
353 	if (dflag) {
354 		bpf_dump(&fcode, dflag);
355 		exit(0);
356 	}
357 	init_addrtoname(localnet, netmask);
358 
359 	(void)setsignal(SIGTERM, cleanup);
360 	(void)setsignal(SIGINT, cleanup);
361 	/* Cooperate with nohup(1) */
362 	if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
363 		(void)setsignal(SIGHUP, oldhandler);
364 
365 	if (pcap_setfilter(pd, &fcode) < 0)
366 		error("%s", pcap_geterr(pd));
367 	if (WFileName) {
368 		pcap_dumper_t *p;
369 
370 		p = pcap_dump_open(pd, WFileName);
371 		if (p == NULL)
372 			error("%s", pcap_geterr(pd));
373 		{
374 			FILE *fp = (FILE *)p;	/* XXX touching pcap guts! */
375 			fflush(fp);
376 			setvbuf(fp, NULL, _IONBF, 0);
377 		}
378 		printer = pcap_dump;
379 		pcap_userdata = (u_char *)p;
380 	} else {
381 		printer = lookup_printer(pcap_datalink(pd));
382 		pcap_userdata = 0;
383 	}
384 	if (RFileName == NULL) {
385 		(void)fprintf(stderr, "%s: listening on %s\n",
386 		    program_name, device);
387 		(void)fflush(stderr);
388 	}
389 	if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) {
390 		(void)fprintf(stderr, "%s: pcap_loop: %s\n",
391 		    program_name, pcap_geterr(pd));
392 		exit(1);
393 	}
394 	pcap_close(pd);
395 	exit(0);
396 }
397 
398 /* make a clean exit on interrupts */
399 RETSIGTYPE
400 cleanup(int signo)
401 {
402 	struct pcap_stat stat;
403 	char buf[1024];
404 
405 	/* Can't print the summary if reading from a savefile */
406 	if (pd != NULL && pcap_file(pd) == NULL) {
407 #if 0
408 		(void)fflush(stdout);	/* XXX unsafe */
409 #endif
410 		(void)write(STDERR_FILENO, "\n", 1);
411 		if (pcap_stats(pd, &stat) < 0) {
412 			(void)snprintf(buf, sizeof buf,
413 			    "pcap_stats: %s\n", pcap_geterr(pd));
414 			write(STDOUT_FILENO, buf, strlen(buf));
415 		} else {
416 			(void)snprintf(buf, sizeof buf,
417 			    "%d packets received by filter\n", stat.ps_recv);
418 			write(STDOUT_FILENO, buf, strlen(buf));
419 			(void)snprintf(buf, sizeof buf,
420 			    "%d packets dropped by kernel\n", stat.ps_drop);
421 			write(STDOUT_FILENO, buf, strlen(buf));
422 		}
423 	}
424 	_exit(0);
425 }
426 
427 /* dump the buffer in `emacs-hexl' style */
428 void
429 default_print_hexl(const u_char *cp, unsigned int length, unsigned int offset)
430 {
431 	unsigned int i, j, jm;
432 	int c;
433 	char ln[128], buf[128];
434 
435 	printf("\n");
436 	for (i = 0; i < length; i += 0x10) {
437 		snprintf(ln, sizeof(ln), "  %04x: ",
438 		    (unsigned int)(i + offset));
439 		jm = length - i;
440 		jm = jm > 16 ? 16 : jm;
441 
442 		for (j = 0; j < jm; j++) {
443 			if ((j % 2) == 1)
444 				snprintf(buf, sizeof(buf), "%02x ",
445 				    (unsigned int)cp[i+j]);
446 			else
447 				snprintf(buf, sizeof(buf), "%02x",
448 				    (unsigned int)cp[i+j]);
449 			strlcat(ln, buf, sizeof ln);
450 		}
451 		for (; j < 16; j++) {
452 			if ((j % 2) == 1)
453 				snprintf(buf, sizeof buf, "   ");
454 			else
455 				snprintf(buf, sizeof buf, "  ");
456 			strlcat(ln, buf, sizeof ln);
457 		}
458 
459 		strlcat(ln, " ", sizeof ln);
460 		for (j = 0; j < jm; j++) {
461 			c = cp[i+j];
462 			c = isprint(c) ? c : '.';
463 			buf[0] = c;
464 			buf[1] = '\0';
465 			strlcat(ln, buf, sizeof ln);
466 		}
467 		printf("%s\n", ln);
468 	}
469 }
470 
471 /* Like default_print() but data need not be aligned */
472 void
473 default_print_unaligned(register const u_char *cp, register u_int length)
474 {
475 	register u_int i, s;
476 	register int nshorts;
477 
478 	if (Xflag) {
479 		/* dump the buffer in `emacs-hexl' style */
480 		default_print_hexl(cp, length, 0);
481 	} else {
482 		/* dump the buffer in old tcpdump style */
483 		nshorts = (u_int) length / sizeof(u_short);
484 		i = 0;
485 		while (--nshorts >= 0) {
486 			if ((i++ % 8) == 0)
487 				(void)printf("\n\t\t\t");
488 			s = *cp++;
489 			(void)printf(" %02x%02x", s, *cp++);
490 		}
491 		if (length & 1) {
492 			if ((i % 8) == 0)
493 				(void)printf("\n\t\t\t");
494 			(void)printf(" %02x", *cp);
495 		}
496 	}
497 }
498 
499 void
500 default_print(register const u_char *bp, register u_int length)
501 {
502 	register const u_short *sp;
503 	register u_int i;
504 	register int nshorts;
505 
506 	if (Xflag) {
507 		/* dump the buffer in `emacs-hexl' style */
508 		default_print_hexl(bp, length, 0);
509 	} else {
510 		/* dump the buffer in old tcpdump style */
511 		if ((long)bp & 1) {
512 			default_print_unaligned(bp, length);
513 			return;
514 		}
515 		sp = (u_short *)bp;
516 		nshorts = (u_int) length / sizeof(u_short);
517 		i = 0;
518 		while (--nshorts >= 0) {
519 			if ((i++ % 8) == 0)
520 				(void)printf("\n\t\t\t");
521 			(void)printf(" %04x", ntohs(*sp++));
522 		}
523 		if (length & 1) {
524 			if ((i % 8) == 0)
525 				(void)printf("\n\t\t\t");
526 			(void)printf(" %02x", *(u_char *)sp);
527 		}
528 	}
529 }
530 
531 __dead void
532 usage(void)
533 {
534 	extern char version[];
535 	extern char pcap_version[];
536 
537 	(void)fprintf(stderr, "%s version %s\n", program_name, version);
538 	(void)fprintf(stderr, "libpcap version %s\n", pcap_version);
539 	(void)fprintf(stderr,
540 "Usage: %s [-adeflnNOpqStvxX] [-c count] [-F file] [-i interface] [-r file]\n",
541 	    program_name);
542 	(void)fprintf(stderr,
543 "\t\t[-s snaplen] [-T type] [-w file] [-E [espalg:]espkey]\n");
544 	(void)fprintf(stderr,
545 "\t\t[expression]\n");
546 	exit(1);
547 }
548