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[tcpdump] / print-tcp.c
1 /*
2 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
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
22 #ifndef lint
23 static const char rcsid[] =
24 "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.81 2000-12-23 20:55:22 guy Exp $ (LBL)";
25 #endif
26
27 #ifdef HAVE_CONFIG_H
28 #include "config.h"
29 #endif
30
31 #include <sys/param.h>
32 #include <sys/time.h>
33
34 #include <rpc/rpc.h>
35
36 #include <netinet/in.h>
37
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <ctype.h>
42 #include <unistd.h>
43
44 #include "interface.h"
45 #include "addrtoname.h"
46 #include "extract.h"
47
48 #include "tcp.h"
49
50 #include "ip.h"
51 #ifdef INET6
52 #include "ip6.h"
53 #endif
54
55 static void print_tcp_rst_data(register const u_char *sp, u_int length);
56
57 #define MAX_RST_DATA_LEN 30
58
59 /* Compatibility */
60 #ifndef TCPOPT_WSCALE
61 #define TCPOPT_WSCALE 3 /* window scale factor (rfc1072) */
62 #endif
63 #ifndef TCPOPT_SACKOK
64 #define TCPOPT_SACKOK 4 /* selective ack ok (rfc1072) */
65 #endif
66 #ifndef TCPOPT_SACK
67 #define TCPOPT_SACK 5 /* selective ack (rfc1072) */
68 #endif
69 #ifndef TCPOPT_ECHO
70 #define TCPOPT_ECHO 6 /* echo (rfc1072) */
71 #endif
72 #ifndef TCPOPT_ECHOREPLY
73 #define TCPOPT_ECHOREPLY 7 /* echo (rfc1072) */
74 #endif
75 #ifndef TCPOPT_TIMESTAMP
76 #define TCPOPT_TIMESTAMP 8 /* timestamps (rfc1323) */
77 #endif
78 #ifndef TCPOPT_CC
79 #define TCPOPT_CC 11 /* T/TCP CC options (rfc1644) */
80 #endif
81 #ifndef TCPOPT_CCNEW
82 #define TCPOPT_CCNEW 12 /* T/TCP CC options (rfc1644) */
83 #endif
84 #ifndef TCPOPT_CCECHO
85 #define TCPOPT_CCECHO 13 /* T/TCP CC options (rfc1644) */
86 #endif
87
88 /*
89 * Definitions required for ECN
90 * for use if the OS running tcpdump does not have ECN
91 */
92 #ifndef TH_ECNECHO
93 #define TH_ECNECHO 0x40 /* ECN Echo in tcp header */
94 #endif
95 #ifndef TH_CWR
96 #define TH_CWR 0x80 /* ECN Cwnd Reduced in tcp header*/
97 #endif
98
99 struct tha {
100 #ifndef INET6
101 struct in_addr src;
102 struct in_addr dst;
103 #else
104 struct in6_addr src;
105 struct in6_addr dst;
106 #endif /*INET6*/
107 u_int port;
108 };
109
110 struct tcp_seq_hash {
111 struct tcp_seq_hash *nxt;
112 struct tha addr;
113 tcp_seq seq;
114 tcp_seq ack;
115 };
116
117 #define TSEQ_HASHSIZE 919
118
119 /* These tcp optinos do not have the size octet */
120 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
121
122 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
123
124
125 #ifndef TELNET_PORT
126 #define TELNET_PORT 23
127 #endif
128 #ifndef BGP_PORT
129 #define BGP_PORT 179
130 #endif
131 #define NETBIOS_SSN_PORT 139
132 #define BXXP_PORT 10288
133 #ifndef NFS_PORT
134 #define NFS_PORT 2049
135 #endif
136
137 static int tcp_cksum(register const struct ip *ip,
138 register const struct tcphdr *tp,
139 register int len)
140 {
141 int i, tlen;
142 union phu {
143 struct phdr {
144 u_int32_t src;
145 u_int32_t dst;
146 u_char mbz;
147 u_char proto;
148 u_int16_t len;
149 } ph;
150 u_int16_t pa[6];
151 } phu;
152 register const u_int16_t *sp;
153 u_int32_t sum;
154 tlen = ntohs(ip->ip_len) - ((const char *)tp-(const char*)ip);
155
156 /* pseudo-header.. */
157 phu.ph.len = htons(tlen);
158 phu.ph.mbz = 0;
159 phu.ph.proto = IPPROTO_TCP;
160 memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
161 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
162
163 sp = &phu.pa[0];
164 sum = sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5];
165
166 sp = (const u_int16_t *)tp;
167
168 for (i=0; i<(tlen&~1); i+= 2)
169 sum += *sp++;
170
171 if (tlen & 1) {
172 sum += htons( (*(const u_int8_t *)sp) << 8);
173 }
174
175 while (sum > 0xffff)
176 sum = (sum & 0xffff) + (sum >> 16);
177 sum = ~sum & 0xffff;
178
179 return (sum);
180 }
181
182 #ifdef INET6
183 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
184 int len)
185 {
186 int i, tlen;
187 register const u_int16_t *sp;
188 u_int32_t sum;
189 union {
190 struct {
191 struct in6_addr ph_src;
192 struct in6_addr ph_dst;
193 u_int32_t ph_len;
194 u_int8_t ph_zero[3];
195 u_int8_t ph_nxt;
196 } ph;
197 u_int16_t pa[20];
198 } phu;
199
200 tlen = ntohs(ip6->ip6_plen) + sizeof(struct ip6_hdr) -
201 ((const char *)tp - (const char*)ip6);
202
203 /* pseudo-header */
204 memset(&phu, 0, sizeof(phu));
205 phu.ph.ph_src = ip6->ip6_src;
206 phu.ph.ph_dst = ip6->ip6_dst;
207 phu.ph.ph_len = htonl(tlen);
208 phu.ph.ph_nxt = IPPROTO_TCP;
209
210 sum = 0;
211 for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
212 sum += phu.pa[i];
213
214 sp = (const u_int16_t *)tp;
215
216 for (i = 0; i < (tlen & ~1); i += 2)
217 sum += *sp++;
218
219 if (tlen & 1)
220 sum += htons((*(const u_int8_t *)sp) << 8);
221
222 while (sum > 0xffff)
223 sum = (sum & 0xffff) + (sum >> 16);
224 sum = ~sum & 0xffff;
225
226 return (sum);
227 }
228 #endif
229
230 void
231 tcp_print(register const u_char *bp, register u_int length,
232 register const u_char *bp2, int fragmented)
233 {
234 register const struct tcphdr *tp;
235 register const struct ip *ip;
236 register u_char flags;
237 register int hlen;
238 register char ch;
239 u_int16_t sport, dport, win, urp;
240 u_int32_t seq, ack, thseq, thack;
241 int threv;
242 #ifdef INET6
243 register const struct ip6_hdr *ip6;
244 #endif
245
246 tp = (struct tcphdr *)bp;
247 ip = (struct ip *)bp2;
248 #ifdef INET6
249 if (IP_V(ip) == 6)
250 ip6 = (struct ip6_hdr *)bp2;
251 else
252 ip6 = NULL;
253 #endif /*INET6*/
254 ch = '\0';
255 if (!TTEST(tp->th_dport)) {
256 (void)printf("%s > %s: [|tcp]",
257 ipaddr_string(&ip->ip_src),
258 ipaddr_string(&ip->ip_dst));
259 return;
260 }
261
262 sport = ntohs(tp->th_sport);
263 dport = ntohs(tp->th_dport);
264
265
266 hlen = TH_OFF(tp) * 4;
267
268 /*
269 * If data present and NFS port used, assume NFS.
270 * Pass offset of data plus 4 bytes for RPC TCP msg length
271 * to NFS print routines.
272 */
273 if (!qflag) {
274 if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
275 dport == NFS_PORT) {
276 nfsreq_print((u_char *)tp + hlen + 4, length-hlen,
277 (u_char *)ip);
278 return;
279 } else if ((u_char *)tp + 4 + sizeof(struct rpc_msg)
280 <= snapend &&
281 sport == NFS_PORT) {
282 nfsreply_print((u_char *)tp + hlen + 4,length-hlen,
283 (u_char *)ip);
284 return;
285 }
286 }
287 #ifdef INET6
288 if (ip6) {
289 if (ip6->ip6_nxt == IPPROTO_TCP) {
290 (void)printf("%s.%s > %s.%s: ",
291 ip6addr_string(&ip6->ip6_src),
292 tcpport_string(sport),
293 ip6addr_string(&ip6->ip6_dst),
294 tcpport_string(dport));
295 } else {
296 (void)printf("%s > %s: ",
297 tcpport_string(sport), tcpport_string(dport));
298 }
299 } else
300 #endif /*INET6*/
301 {
302 if (ip->ip_p == IPPROTO_TCP) {
303 (void)printf("%s.%s > %s.%s: ",
304 ipaddr_string(&ip->ip_src),
305 tcpport_string(sport),
306 ipaddr_string(&ip->ip_dst),
307 tcpport_string(dport));
308 } else {
309 (void)printf("%s > %s: ",
310 tcpport_string(sport), tcpport_string(dport));
311 }
312 }
313
314 TCHECK(*tp);
315
316 seq = (u_int32_t)ntohl(tp->th_seq);
317 ack = (u_int32_t)ntohl(tp->th_ack);
318 win = ntohs(tp->th_win);
319 urp = ntohs(tp->th_urp);
320
321 if (qflag) {
322 (void)printf("tcp %d", length - TH_OFF(tp) * 4);
323 return;
324 }
325 if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
326 TH_ECNECHO|TH_CWR)) {
327 if (flags & TH_SYN)
328 putchar('S');
329 if (flags & TH_FIN)
330 putchar('F');
331 if (flags & TH_RST)
332 putchar('R');
333 if (flags & TH_PUSH)
334 putchar('P');
335 if (flags & TH_CWR)
336 putchar('W'); /* congestion _W_indow reduced (ECN) */
337 if (flags & TH_ECNECHO)
338 putchar('E'); /* ecn _E_cho sent (ECN) */
339 } else
340 putchar('.');
341
342 if (!Sflag && (flags & TH_ACK)) {
343 register struct tcp_seq_hash *th;
344 register int rev;
345 struct tha tha;
346 /*
347 * Find (or record) the initial sequence numbers for
348 * this conversation. (we pick an arbitrary
349 * collating order so there's only one entry for
350 * both directions).
351 */
352 #ifdef INET6
353 memset(&tha, 0, sizeof(tha));
354 rev = 0;
355 if (ip6) {
356 if (sport > dport) {
357 rev = 1;
358 } else if (sport == dport) {
359 int i;
360
361 for (i = 0; i < 4; i++) {
362 if (((u_int32_t *)(&ip6->ip6_src))[i] >
363 ((u_int32_t *)(&ip6->ip6_dst))[i]) {
364 rev = 1;
365 break;
366 }
367 }
368 }
369 if (rev) {
370 tha.src = ip6->ip6_dst;
371 tha.dst = ip6->ip6_src;
372 tha.port = dport << 16 | sport;
373 } else {
374 tha.dst = ip6->ip6_dst;
375 tha.src = ip6->ip6_src;
376 tha.port = sport << 16 | dport;
377 }
378 } else {
379 if (sport > dport ||
380 (sport == dport &&
381 ip->ip_src.s_addr > ip->ip_dst.s_addr)) {
382 rev = 1;
383 }
384 if (rev) {
385 *(struct in_addr *)&tha.src = ip->ip_dst;
386 *(struct in_addr *)&tha.dst = ip->ip_src;
387 tha.port = dport << 16 | sport;
388 } else {
389 *(struct in_addr *)&tha.dst = ip->ip_dst;
390 *(struct in_addr *)&tha.src = ip->ip_src;
391 tha.port = sport << 16 | dport;
392 }
393 }
394 #else
395 if (sport < dport ||
396 (sport == dport &&
397 ip->ip_src.s_addr < ip->ip_dst.s_addr)) {
398 tha.src = ip->ip_src, tha.dst = ip->ip_dst;
399 tha.port = sport << 16 | dport;
400 rev = 0;
401 } else {
402 tha.src = ip->ip_dst, tha.dst = ip->ip_src;
403 tha.port = dport << 16 | sport;
404 rev = 1;
405 }
406 #endif
407
408 threv = rev;
409 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
410 th->nxt; th = th->nxt)
411 if (!memcmp((char *)&tha, (char *)&th->addr,
412 sizeof(th->addr)))
413 break;
414
415 if (!th->nxt || (flags & TH_SYN)) {
416 /* didn't find it or new conversation */
417 if (th->nxt == NULL) {
418 th->nxt = (struct tcp_seq_hash *)
419 calloc(1, sizeof(*th));
420 if (th->nxt == NULL)
421 error("tcp_print: calloc");
422 }
423 th->addr = tha;
424 if (rev)
425 th->ack = seq, th->seq = ack - 1;
426 else
427 th->seq = seq, th->ack = ack - 1;
428
429 } else {
430 if (rev)
431 seq -= th->ack, ack -= th->seq;
432 else
433 seq -= th->seq, ack -= th->ack;
434 }
435
436 thseq = th->seq;
437 thack = th->ack;
438 } else {
439 /*fool gcc*/
440 thseq = thack = threv = 0;
441 }
442 if (hlen > length) {
443 (void)printf(" [bad hdr length]");
444 return;
445 }
446
447 if (IP_V(ip) == 4 && vflag && !fragmented) {
448 int sum;
449 if (TTEST2(tp->th_sport, length)) {
450 sum = tcp_cksum(ip, tp, length);
451 if (sum != 0)
452 (void)printf(" [bad tcp cksum %x!]", sum);
453 else
454 (void)printf(" [tcp sum ok]");
455 }
456 }
457 #ifdef INET6
458 if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
459 int sum;
460 if (TTEST2(tp->th_sport, length)) {
461 sum = tcp6_cksum(ip6, tp, length);
462 if (sum != 0)
463 (void)printf(" [bad tcp cksum %x!]", sum);
464 else
465 (void)printf(" [tcp sum ok]");
466 }
467 }
468 #endif
469
470 length -= hlen;
471 if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
472 (void)printf(" %u:%u(%d)", seq, seq + length, length);
473 if (flags & TH_ACK)
474 (void)printf(" ack %u", ack);
475
476 (void)printf(" win %d", win);
477
478 if (flags & TH_URG)
479 (void)printf(" urg %d", urp);
480 /*
481 * Handle any options.
482 */
483 if ((hlen -= sizeof(*tp)) > 0) {
484 register const u_char *cp;
485 register int i, opt, len, datalen;
486
487 cp = (const u_char *)tp + sizeof(*tp);
488 putchar(' ');
489 ch = '<';
490 while (hlen > 0) {
491 putchar(ch);
492 TCHECK(*cp);
493 opt = *cp++;
494 if (ZEROLENOPT(opt))
495 len = 1;
496 else {
497 TCHECK(*cp);
498 len = *cp++; /* total including type, len */
499 if (len < 2 || len > hlen)
500 goto bad;
501 --hlen; /* account for length byte */
502 }
503 --hlen; /* account for type byte */
504 datalen = 0;
505
506 /* Bail if "l" bytes of data are not left or were not captured */
507 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
508
509 switch (opt) {
510
511 case TCPOPT_MAXSEG:
512 (void)printf("mss");
513 datalen = 2;
514 LENCHECK(datalen);
515 (void)printf(" %u", EXTRACT_16BITS(cp));
516
517 break;
518
519 case TCPOPT_EOL:
520 (void)printf("eol");
521 break;
522
523 case TCPOPT_NOP:
524 (void)printf("nop");
525 break;
526
527 case TCPOPT_WSCALE:
528 (void)printf("wscale");
529 datalen = 1;
530 LENCHECK(datalen);
531 (void)printf(" %u", *cp);
532 break;
533
534 case TCPOPT_SACKOK:
535 (void)printf("sackOK");
536 break;
537
538 case TCPOPT_SACK:
539 (void)printf("sack");
540 datalen = len - 2;
541 if (datalen % 8 != 0) {
542 (void)printf(" malformed sack ");
543 } else {
544 u_int32_t s, e;
545
546 (void)printf(" sack %d ", datalen / 8);
547 for (i = 0; i < datalen; i += 8) {
548 LENCHECK(i + 4);
549 s = EXTRACT_32BITS(cp + i);
550 LENCHECK(i + 8);
551 e = EXTRACT_32BITS(cp + i + 4);
552 if (threv) {
553 s -= thseq;
554 e -= thseq;
555 } else {
556 s -= thack;
557 e -= thack;
558 }
559 (void)printf("{%u:%u}", s, e);
560 }
561 (void)printf(" ");
562 }
563 break;
564
565 case TCPOPT_ECHO:
566 (void)printf("echo");
567 datalen = 4;
568 LENCHECK(datalen);
569 (void)printf(" %u", EXTRACT_32BITS(cp));
570 break;
571
572 case TCPOPT_ECHOREPLY:
573 (void)printf("echoreply");
574 datalen = 4;
575 LENCHECK(datalen);
576 (void)printf(" %u", EXTRACT_32BITS(cp));
577 break;
578
579 case TCPOPT_TIMESTAMP:
580 (void)printf("timestamp");
581 datalen = 8;
582 LENCHECK(4);
583 (void)printf(" %u", EXTRACT_32BITS(cp));
584 LENCHECK(datalen);
585 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
586 break;
587
588 case TCPOPT_CC:
589 (void)printf("cc");
590 datalen = 4;
591 LENCHECK(datalen);
592 (void)printf(" %u", EXTRACT_32BITS(cp));
593 break;
594
595 case TCPOPT_CCNEW:
596 (void)printf("ccnew");
597 datalen = 4;
598 LENCHECK(datalen);
599 (void)printf(" %u", EXTRACT_32BITS(cp));
600 break;
601
602 case TCPOPT_CCECHO:
603 (void)printf("ccecho");
604 datalen = 4;
605 LENCHECK(datalen);
606 (void)printf(" %u", EXTRACT_32BITS(cp));
607 break;
608
609 default:
610 (void)printf("opt-%d:", opt);
611 datalen = len - 2;
612 for (i = 0; i < datalen; ++i) {
613 LENCHECK(i);
614 (void)printf("%02x", cp[i]);
615 }
616 break;
617 }
618
619 /* Account for data printed */
620 cp += datalen;
621 hlen -= datalen;
622
623 /* Check specification against observed length */
624 ++datalen; /* option octet */
625 if (!ZEROLENOPT(opt))
626 ++datalen; /* size octet */
627 if (datalen != len)
628 (void)printf("[len %d]", len);
629 ch = ',';
630 if (opt == TCPOPT_EOL)
631 break;
632 }
633 putchar('>');
634 }
635
636 if (length <= 0)
637 return;
638
639 /*
640 * Decode payload if necessary.
641 */
642 bp += TH_OFF(tp) * 4;
643 if (flags & TH_RST) {
644 if (vflag)
645 print_tcp_rst_data(bp, length);
646 } else {
647 if (sport == TELNET_PORT || dport == TELNET_PORT) {
648 if (!qflag && vflag)
649 telnet_print(bp, length);
650 } else if (sport == BGP_PORT || dport == BGP_PORT)
651 bgp_print(bp, length);
652 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
653 nbt_tcp_print(bp, length);
654 else if (sport == BXXP_PORT || dport == BXXP_PORT)
655 bxxp_print(bp, length);
656 }
657 return;
658 bad:
659 fputs("[bad opt]", stdout);
660 if (ch != '\0')
661 putchar('>');
662 return;
663 trunc:
664 fputs("[|tcp]", stdout);
665 if (ch != '\0')
666 putchar('>');
667 }
668
669 /*
670 * RFC1122 says the following on data in RST segments:
671 *
672 * 4.2.2.12 RST Segment: RFC-793 Section 3.4
673 *
674 * A TCP SHOULD allow a received RST segment to include data.
675 *
676 * DISCUSSION
677 * It has been suggested that a RST segment could contain
678 * ASCII text that encoded and explained the cause of the
679 * RST. No standard has yet been established for such
680 * data.
681 *
682 */
683
684 static void
685 print_tcp_rst_data(register const u_char *sp, u_int length)
686 {
687 int c;
688
689 if (TTEST2(*sp, length))
690 printf(" [RST");
691 else
692 printf(" [!RST");
693 if (length > MAX_RST_DATA_LEN) {
694 length = MAX_RST_DATA_LEN; /* can use -X for longer */
695 putchar('+'); /* indicate we truncate */
696 }
697 putchar(' ');
698 while (length-- && sp <= snapend) {
699 c = *sp++;
700 if (isprint(c))
701 putchar(c);
702 else
703 putchar('.');
704 }
705 putchar(']');
706 }
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