xref: /openbsd/usr.sbin/tcpdump/print-ip.c (revision 78b63d65) 
1 /*	$OpenBSD: print-ip.c,v 1.15 2001/02/15 16:16:48 niklas 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 rcsid[] =
26     "@(#) $Header: /home/cvs/src/usr.sbin/tcpdump/print-ip.c,v 1.15 2001/02/15 16:16:48 niklas Exp $ (LBL)";
27 #endif
28 
29 #include <sys/param.h>
30 #include <sys/time.h>
31 #include <sys/socket.h>
32 
33 #include <netinet/in.h>
34 #include <netinet/in_systm.h>
35 #include <netinet/ip.h>
36 #include <netinet/ip_var.h>
37 #include <netinet/udp.h>
38 #include <netinet/udp_var.h>
39 #include <netinet/tcp.h>
40 #include <netinet/tcpip.h>
41 
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46 
47 #include "addrtoname.h"
48 #include "interface.h"
49 #include "extract.h"			/* must come after interface.h */
50 
51 /* Compatibility */
52 #ifndef	IPPROTO_ND
53 #define	IPPROTO_ND	77
54 #endif
55 
56 #ifndef IN_CLASSD
57 #define IN_CLASSD(i) (((int32_t)(i) & 0xf0000000) == 0xe0000000)
58 #endif
59 
60 /* Definitions required for ECN
61    for use if the OS running tcpdump does not have ECN */
62 #ifndef IPTOS_ECT
63 #define IPTOS_ECT	0x02	/* ECN Capable Transport in IP header*/
64 #endif
65 #ifndef IPTOS_CE
66 #define IPTOS_CE	0x01	/* ECN Cong. Experienced in IP header*/
67 #endif
68 
69 /* (following from ipmulti/mrouted/prune.h) */
70 
71 /*
72  * The packet format for a traceroute request.
73  */
74 struct tr_query {
75 	u_int  tr_src;			/* traceroute source */
76 	u_int  tr_dst;			/* traceroute destination */
77 	u_int  tr_raddr;		/* traceroute response address */
78 #if BYTE_ORDER == BIG_ENDIAN
79 	struct {
80 		u_int   ttl : 8;	/* traceroute response ttl */
81 		u_int   qid : 24;	/* traceroute query id */
82 	} q;
83 #else
84 	struct {
85 		u_int	qid : 24;	/* traceroute query id */
86 		u_int	ttl : 8;	/* traceroute response ttl */
87 	} q;
88 #endif
89 };
90 
91 #define tr_rttl q.ttl
92 #define tr_qid  q.qid
93 
94 /*
95  * Traceroute response format.  A traceroute response has a tr_query at the
96  * beginning, followed by one tr_resp for each hop taken.
97  */
98 struct tr_resp {
99 	u_int tr_qarr;			/* query arrival time */
100 	u_int tr_inaddr;		/* incoming interface address */
101 	u_int tr_outaddr;		/* outgoing interface address */
102 	u_int tr_rmtaddr;		/* parent address in source tree */
103 	u_int tr_vifin;			/* input packet count on interface */
104 	u_int tr_vifout;		/* output packet count on interface */
105 	u_int tr_pktcnt;		/* total incoming packets for src-grp */
106 	u_char  tr_rproto;		/* routing proto deployed on router */
107 	u_char  tr_fttl;		/* ttl required to forward on outvif */
108 	u_char  tr_smask;		/* subnet mask for src addr */
109 	u_char  tr_rflags;		/* forwarding error codes */
110 };
111 
112 /* defs within mtrace */
113 #define TR_QUERY 1
114 #define TR_RESP	2
115 
116 /* fields for tr_rflags (forwarding error codes) */
117 #define TR_NO_ERR	0
118 #define TR_WRONG_IF	1
119 #define TR_PRUNED	2
120 #define TR_OPRUNED	3
121 #define TR_SCOPED	4
122 #define TR_NO_RTE	5
123 #define TR_NO_FWD	7
124 #define TR_NO_SPACE	0x81
125 #define TR_OLD_ROUTER	0x82
126 
127 /* fields for tr_rproto (routing protocol) */
128 #define TR_PROTO_DVMRP	1
129 #define TR_PROTO_MOSPF	2
130 #define TR_PROTO_PIM	3
131 #define TR_PROTO_CBT	4
132 
133 static void print_mtrace(register const u_char *bp, register u_int len)
134 {
135 	register struct tr_query *tr = (struct tr_query *)(bp + 8);
136 
137 	printf("mtrace %d: %s to %s reply-to %s", tr->tr_qid,
138 		ipaddr_string(&tr->tr_src), ipaddr_string(&tr->tr_dst),
139 		ipaddr_string(&tr->tr_raddr));
140 	if (IN_CLASSD(ntohl(tr->tr_raddr)))
141 		printf(" with-ttl %d", tr->tr_rttl);
142 }
143 
144 static void print_mresp(register const u_char *bp, register u_int len)
145 {
146 	register struct tr_query *tr = (struct tr_query *)(bp + 8);
147 
148 	printf("mresp %d: %s to %s reply-to %s", tr->tr_qid,
149 		ipaddr_string(&tr->tr_src), ipaddr_string(&tr->tr_dst),
150 		ipaddr_string(&tr->tr_raddr));
151 	if (IN_CLASSD(ntohl(tr->tr_raddr)))
152 		printf(" with-ttl %d", tr->tr_rttl);
153 }
154 
155 static void
156 igmp_print(register const u_char *bp, register u_int len,
157 	   register const u_char *bp2)
158 {
159 	register const struct ip *ip;
160 
161 	ip = (const struct ip *)bp2;
162         (void)printf("%s > %s: ",
163 		ipaddr_string(&ip->ip_src),
164 		ipaddr_string(&ip->ip_dst));
165 
166 	TCHECK2(bp[0], 8);
167 	switch (bp[0]) {
168 	case 0x11:
169 		(void)printf("igmp query");
170 		if (*(int *)&bp[4])
171 			(void)printf(" [gaddr %s]", ipaddr_string(&bp[4]));
172 		if (len != 8)
173 			(void)printf(" [len %d]", len);
174 		break;
175 	case 0x12:
176 		(void)printf("igmp report %s", ipaddr_string(&bp[4]));
177 		if (len != 8)
178 			(void)printf(" [len %d]", len);
179 		break;
180 	case 0x16:
181 		(void)printf("igmp nreport %s", ipaddr_string(&bp[4]));
182 		break;
183 	case 0x17:
184 		(void)printf("igmp leave %s", ipaddr_string(&bp[4]));
185 		break;
186 	case 0x13:
187 		(void)printf("igmp dvmrp");
188 		if (len < 8)
189 			(void)printf(" [len %d]", len);
190 		else
191 			dvmrp_print(bp, len);
192 		break;
193 	case 0x14:
194 		(void)printf("igmp pim");
195 		pim_print(bp, len);
196   		break;
197 	case 0x1e:
198 		print_mresp(bp, len);
199 		break;
200 	case 0x1f:
201 		print_mtrace(bp, len);
202 		break;
203 	default:
204 		(void)printf("igmp-%d", bp[0] & 0xf);
205 		break;
206 	}
207 	if ((bp[0] >> 4) != 1)
208 		(void)printf(" [v%d]", bp[0] >> 4);
209 
210 	TCHECK2(bp[0], len);
211 	if (vflag) {
212 		/* Check the IGMP checksum */
213 		u_int32_t sum = 0;
214 		int count;
215 		const u_short *sp = (u_short *)bp;
216 
217 		for (count = len / 2; --count >= 0; )
218 			sum += *sp++;
219 		if (len & 1)
220 			sum += ntohs(*(u_char *) sp << 8);
221 		while (sum >> 16)
222 			sum = (sum & 0xffff) + (sum >> 16);
223 		sum = 0xffff & ~sum;
224 		if (sum != 0)
225 			printf(" bad igmp cksum %x!", EXTRACT_16BITS(&bp[2]));
226 	}
227 	return;
228 trunc:
229 	fputs("[|igmp]", stdout);
230 }
231 
232 /*
233  * print the recorded route in an IP RR, LSRR or SSRR option.
234  */
235 static void
236 ip_printroute(const char *type, register const u_char *cp, u_int length)
237 {
238 	register u_int ptr = cp[2] - 1;
239 	register u_int len;
240 
241 	printf(" %s{", type);
242 	if ((length + 1) & 3)
243 		printf(" [bad length %d]", length);
244 	if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1)
245 		printf(" [bad ptr %d]", cp[2]);
246 
247 	type = "";
248 	for (len = 3; len < length; len += 4) {
249 		if (ptr == len)
250 			type = "#";
251 		printf("%s%s", type, ipaddr_string(&cp[len]));
252 		type = " ";
253 	}
254 	printf("%s}", ptr == len? "#" : "");
255 }
256 
257 /*
258  * print IP options.
259  */
260 static void
261 ip_optprint(register const u_char *cp, u_int length)
262 {
263 	register u_int len;
264 
265 	for (; length > 0; cp += len, length -= len) {
266 		int tt = *cp;
267 
268 		len = (tt == IPOPT_NOP || tt == IPOPT_EOL) ? 1 : cp[1];
269 		if (len <= 0) {
270 			printf("[|ip op len %d]", len);
271 			return;
272 		}
273 		if (&cp[1] >= snapend || cp + len > snapend) {
274 			printf("[|ip]");
275 			return;
276 		}
277 		switch (tt) {
278 
279 		case IPOPT_EOL:
280 			printf(" EOL");
281 			if (length > 1)
282 				printf("-%d", length - 1);
283 			return;
284 
285 		case IPOPT_NOP:
286 			printf(" NOP");
287 			break;
288 
289 		case IPOPT_TS:
290 			printf(" TS{%d}", len);
291 			break;
292 
293 		case IPOPT_SECURITY:
294 			printf(" SECURITY{%d}", len);
295 			break;
296 
297 		case IPOPT_RR:
298 			printf(" RR{%d}=", len);
299 			ip_printroute("RR", cp, len);
300 			break;
301 
302 		case IPOPT_SSRR:
303 			ip_printroute("SSRR", cp, len);
304 			break;
305 
306 		case IPOPT_LSRR:
307 			ip_printroute("LSRR", cp, len);
308 			break;
309 
310 		default:
311 			printf(" IPOPT-%d{%d}", cp[0], len);
312 			break;
313 		}
314 	}
315 }
316 
317 /*
318  * compute an IP header checksum.
319  * don't modifiy the packet.
320  */
321 u_short
322 in_cksum(const u_short *addr, register int len, u_short csum)
323 {
324 	int nleft = len;
325 	const u_short *w = addr;
326 	u_short answer;
327 	int sum = csum;
328 
329  	/*
330 	 *  Our algorithm is simple, using a 32 bit accumulator (sum),
331 	 *  we add sequential 16 bit words to it, and at the end, fold
332 	 *  back all the carry bits from the top 16 bits into the lower
333 	 *  16 bits.
334  	 */
335 	while (nleft > 1)  {
336 		sum += *w++;
337 		nleft -= 2;
338 	}
339 	if (nleft == 1)
340 		sum += htons(*(u_char *)w<<8);
341 
342 	/*
343 	 * add back carry outs from top 16 bits to low 16 bits
344 	 */
345 	sum = (sum >> 16) + (sum & 0xffff);	/* add hi 16 to low 16 */
346 	sum += (sum >> 16);			/* add carry */
347 	answer = ~sum;				/* truncate to 16 bits */
348 	return (answer);
349 }
350 
351 /*
352  * print an IP datagram.
353  */
354 void
355 ip_print(register const u_char *bp, register u_int length)
356 {
357 	register const struct ip *ip;
358 	register u_int hlen, len, off;
359 	register const u_char *cp;
360 
361 	ip = (const struct ip *)bp;
362 #ifdef LBL_ALIGN
363 	/*
364 	 * If the IP header is not aligned, copy into abuf.
365 	 * This will never happen with BPF.  It does happen raw packet
366 	 * dumps from -r.
367 	 */
368 	if ((long)ip & 3) {
369 		static u_char *abuf = NULL;
370 		static int didwarn = 0;
371 
372 		if (abuf == NULL) {
373 			abuf = (u_char *)malloc(snaplen);
374 			if (abuf == NULL)
375 				error("ip_print: malloc");
376 		}
377 		memcpy((char *)abuf, (char *)ip, min(length, snaplen));
378 		snapend += abuf - (u_char *)ip;
379 		packetp = abuf;
380 		ip = (struct ip *)abuf;
381 		/* We really want libpcap to give us aligned packets */
382 		if (!didwarn) {
383 			warning("compensating for unaligned libpcap packets");
384 			++didwarn;
385 		}
386 	}
387 #endif
388 	if ((u_char *)(ip + 1) > snapend) {
389 		printf("[|ip]");
390 		return;
391 	}
392 	if (length < sizeof (struct ip)) {
393 		(void)printf("truncated-ip %d", length);
394 		return;
395 	}
396 	hlen = ip->ip_hl * 4;
397 
398 	len = ntohs(ip->ip_len);
399 	if (length < len)
400 		(void)printf("truncated-ip - %d bytes missing!",
401 			len - length);
402 	len -= hlen;
403 
404 	/*
405 	 * If this is fragment zero, hand it to the next higher
406 	 * level protocol.
407 	 */
408 	off = ntohs(ip->ip_off);
409 	if ((off & 0x1fff) == 0) {
410 		cp = (const u_char *)ip + hlen;
411 		switch (ip->ip_p) {
412 
413 		case IPPROTO_TCP:
414 			tcp_print(cp, len, (const u_char *)ip);
415 			break;
416 
417 		case IPPROTO_UDP:
418 			udp_print(cp, len, (const u_char *)ip);
419 			break;
420 
421 		case IPPROTO_ICMP:
422 			icmp_print(cp, (const u_char *)ip);
423 			break;
424 
425 #ifndef IPPROTO_IGRP
426 #define IPPROTO_IGRP 9
427 #endif
428 		case IPPROTO_IGRP:
429 			igrp_print(cp, len, (const u_char *)ip);
430 			break;
431 
432 		case IPPROTO_ND:
433 			(void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
434 				ipaddr_string(&ip->ip_dst));
435 			(void)printf(" nd %d", len);
436 			break;
437 
438 		case IPPROTO_EGP:
439 			egp_print(cp, len, (const u_char *)ip);
440 			break;
441 
442 #ifndef IPPROTO_OSPF
443 #define IPPROTO_OSPF 89
444 #endif
445 		case IPPROTO_OSPF:
446 			ospf_print(cp, len, (const u_char *)ip);
447 			break;
448 
449 #ifndef IPPROTO_IGMP
450 #define IPPROTO_IGMP 2
451 #endif
452 		case IPPROTO_IGMP:
453 			igmp_print(cp, len, (const u_char *)ip);
454 			break;
455 
456 #ifndef IPPROTO_IPIP
457 #define IPPROTO_IPIP 4
458 #endif
459 		case IPPROTO_IPIP:
460 			/* ip-in-ip encapsulation */
461 			if (vflag)
462 				(void)printf("%s > %s: ",
463 					     ipaddr_string(&ip->ip_src),
464 					     ipaddr_string(&ip->ip_dst));
465 			ip_print(cp, len);
466 			if (! vflag) {
467 				printf(" (encap)");
468 				return;
469 			}
470 			break;
471 
472 #ifdef INET6
473 #ifndef IPPROTO_IPV6
474 #define IPPROTO_IPV6
475 #endif
476 		case IPPROTO_IPV6:
477 			/* ip6-in-ip encapsulation */
478 			if (vflag)
479 				(void)printf("%s > %s: ",
480 					     ipaddr_string(&ip->ip_src),
481 					     ipaddr_string(&ip->ip_dst));
482 			ip6_print(cp, len);
483 			if (! vflag) {
484  				printf(" (encap)");
485  				return;
486  			}
487  			break;
488 #endif /*INET6*/
489 
490 #ifndef IPPROTO_GRE
491 #define IPPROTO_GRE 47
492 #endif
493 		case IPPROTO_GRE:
494 			if (vflag)
495 				(void)printf("gre %s > %s: ",
496 					     ipaddr_string(&ip->ip_src),
497 					     ipaddr_string(&ip->ip_dst));
498 			/* do it */
499 			gre_print(cp, len);
500 			if (! vflag) {
501 				printf(" (gre encap)");
502 				return;
503   			}
504   			break;
505 
506 #ifndef IPPROTO_ESP
507 #define IPPROTO_ESP 50
508 #endif
509 		case IPPROTO_ESP:
510 			esp_print(cp, len, (const u_char *)ip);
511 			break;
512 
513 #ifndef IPPROTO_AH
514 #define IPPROTO_AH 51
515 #endif
516 		case IPPROTO_AH:
517 			ah_print(cp, len, (const u_char *)ip);
518 			break;
519 
520 #ifndef IPPROTO_MOBILE
521 #define IPPROTO_MOBILE 55
522 #endif
523 		case IPPROTO_MOBILE:
524 			if (vflag)
525 				(void)printf("mobile %s > %s: ",
526 					     ipaddr_string(&ip->ip_src),
527 					     ipaddr_string(&ip->ip_dst));
528 			mobile_print(cp, len);
529 			if (! vflag) {
530 				printf(" (mobile encap)");
531 				return;
532 			}
533 			break;
534 
535 #ifndef IPPROTO_ETHERIP
536 #define IPPROTO_ETHERIP	97
537 #endif
538 		case IPPROTO_ETHERIP:
539 			etherip_print(cp, len, (const u_char *)ip);
540 			break;
541 
542 #ifndef IPPROTO_VRRP
543 #define IPPROTO_VRRP 112
544 #endif
545 		case IPPROTO_VRRP:
546 			if (vflag)
547 				(void)printf("vrrp %s > %s: ",
548 					     ipaddr_string(&ip->ip_src),
549 					     ipaddr_string(&ip->ip_dst));
550 			vrrp_print(cp, len, ip->ip_ttl);
551 			break;
552 
553 		default:
554 			(void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
555 				ipaddr_string(&ip->ip_dst));
556 			(void)printf(" ip-proto-%d %d", ip->ip_p, len);
557 			break;
558 		}
559 	}
560 	/*
561 	 * for fragmented datagrams, print id:size@offset.  On all
562 	 * but the last stick a "+".  For unfragmented datagrams, note
563 	 * the don't fragment flag.
564 	 */
565 	if (off & 0x3fff) {
566 		/*
567 		 * if this isn't the first frag, we're missing the
568 		 * next level protocol header.  print the ip addr.
569 		 */
570 		if (off & 0x1fff)
571 			(void)printf("%s > %s:", ipaddr_string(&ip->ip_src),
572 				      ipaddr_string(&ip->ip_dst));
573 		(void)printf(" (frag %d:%d@%d%s)", ntohs(ip->ip_id), len,
574 			(off & 0x1fff) * 8,
575 			(off & IP_MF)? "+" : "");
576 	} else if (off & IP_DF)
577 		(void)printf(" (DF)");
578 
579 	if (ip->ip_tos) {
580 		(void)printf(" [tos 0x%x", (int)ip->ip_tos);
581 		if (ip->ip_tos & (IPTOS_CE|IPTOS_ECT)) {
582 			(void)printf(" (");
583 			if (ip->ip_tos & IPTOS_ECT) {
584 				/* ECN-capable transport */
585 				putchar('E');
586 			}
587 			if (ip->ip_tos & IPTOS_CE) {
588 				/* _C_ongestion experienced (ECN) */
589 				putchar('C');
590 			}
591 			(void)printf(")");
592   		}
593 		(void)printf("]");
594 	}
595 
596 	if (ip->ip_ttl <= 1)
597 		(void)printf(" [ttl %d]", (int)ip->ip_ttl);
598 
599 	if (vflag) {
600 		int sum;
601 		char *sep = "";
602 
603 		printf(" (");
604 		if (ip->ip_ttl > 1) {
605 			(void)printf("%sttl %d", sep, (int)ip->ip_ttl);
606 			sep = ", ";
607 		}
608 		if ((off & 0x3fff) == 0) {
609 			(void)printf("%sid %d", sep, (int)ntohs(ip->ip_id));
610 			sep = ", ";
611 		}
612 		if ((u_char *)ip + hlen <= snapend) {
613 			sum = in_cksum((const u_short *)ip, hlen, 0);
614 			if (sum != 0) {
615 				(void)printf("%sbad cksum %x!", sep,
616 					     ntohs(ip->ip_sum));
617 				sep = ", ";
618 			}
619 		}
620 		if ((hlen -= sizeof(struct ip)) > 0) {
621 			(void)printf("%soptlen=%d", sep, hlen);
622 			ip_optprint((u_char *)(ip + 1), hlen);
623 		}
624 		printf(")");
625 	}
626 }
627