Move tcpdump-3.9/ to tcpdump/. No need for a versioned dir.
[dragonfly.git] / contrib / tcpdump / print-tcp.c
CommitLineData
c8cf0f94
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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 * Copyright (c) 1999-2004 The tcpdump.org project
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
25static const char rcsid[] _U_ =
26 "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.120.2.3 2005/10/16 06:05:46 guy Exp $ (LBL)";
27#endif
28
29#ifdef HAVE_CONFIG_H
30#include "config.h"
31#endif
32
33#include <tcpdump-stdinc.h>
34
35#include <stdio.h>
36#include <stdlib.h>
37#include <string.h>
38
39#include "interface.h"
40#include "addrtoname.h"
41#include "extract.h"
42
43#include "tcp.h"
44
45#include "ip.h"
46#ifdef INET6
47#include "ip6.h"
48#endif
49#include "ipproto.h"
50#include "rpc_auth.h"
51#include "rpc_msg.h"
52
53#include "nameser.h"
54
55#ifdef HAVE_LIBCRYPTO
56#include <openssl/md5.h>
57
58#define SIGNATURE_VALID 0
59#define SIGNATURE_INVALID 1
60#define CANT_CHECK_SIGNATURE 2
61
62static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
63 const u_char *data, int length, const u_char *rcvsig);
64#endif
65
66static void print_tcp_rst_data(register const u_char *sp, u_int length);
67
68#define MAX_RST_DATA_LEN 30
69
70
71struct tha {
72#ifndef INET6
73 struct in_addr src;
74 struct in_addr dst;
75#else
76 struct in6_addr src;
77 struct in6_addr dst;
78#endif /*INET6*/
79 u_int port;
80};
81
82struct tcp_seq_hash {
83 struct tcp_seq_hash *nxt;
84 struct tha addr;
85 tcp_seq seq;
86 tcp_seq ack;
87};
88
89#define TSEQ_HASHSIZE 919
90
91/* These tcp optinos do not have the size octet */
92#define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
93
94static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
95
96
97#ifndef TELNET_PORT
98#define TELNET_PORT 23
99#endif
100#ifndef BGP_PORT
101#define BGP_PORT 179
102#endif
103#define NETBIOS_SSN_PORT 139
104#ifndef PPTP_PORT
105#define PPTP_PORT 1723
106#endif
107#define BEEP_PORT 10288
108#ifndef NFS_PORT
109#define NFS_PORT 2049
110#endif
111#define MSDP_PORT 639
112#define LDP_PORT 646
113
114static int tcp_cksum(register const struct ip *ip,
115 register const struct tcphdr *tp,
116 register u_int len)
117{
118 union phu {
119 struct phdr {
120 u_int32_t src;
121 u_int32_t dst;
122 u_char mbz;
123 u_char proto;
124 u_int16_t len;
125 } ph;
126 u_int16_t pa[6];
127 } phu;
128 const u_int16_t *sp;
129
130 /* pseudo-header.. */
131 phu.ph.len = htons((u_int16_t)len);
132 phu.ph.mbz = 0;
133 phu.ph.proto = IPPROTO_TCP;
134 memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
135 if (IP_HL(ip) == 5)
136 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
137 else
138 phu.ph.dst = ip_finddst(ip);
139
140 sp = &phu.pa[0];
141 return in_cksum((u_short *)tp, len,
142 sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
143}
144
145#ifdef INET6
146static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
147 u_int len)
148{
149 size_t i;
150 register const u_int16_t *sp;
151 u_int32_t sum;
152 union {
153 struct {
154 struct in6_addr ph_src;
155 struct in6_addr ph_dst;
156 u_int32_t ph_len;
157 u_int8_t ph_zero[3];
158 u_int8_t ph_nxt;
159 } ph;
160 u_int16_t pa[20];
161 } phu;
162
163 /* pseudo-header */
164 memset(&phu, 0, sizeof(phu));
165 phu.ph.ph_src = ip6->ip6_src;
166 phu.ph.ph_dst = ip6->ip6_dst;
167 phu.ph.ph_len = htonl(len);
168 phu.ph.ph_nxt = IPPROTO_TCP;
169
170 sum = 0;
171 for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
172 sum += phu.pa[i];
173
174 sp = (const u_int16_t *)tp;
175
176 for (i = 0; i < (len & ~1); i += 2)
177 sum += *sp++;
178
179 if (len & 1)
180 sum += htons((*(const u_int8_t *)sp) << 8);
181
182 while (sum > 0xffff)
183 sum = (sum & 0xffff) + (sum >> 16);
184 sum = ~sum & 0xffff;
185
186 return (sum);
187}
188#endif
189
190void
191tcp_print(register const u_char *bp, register u_int length,
192 register const u_char *bp2, int fragmented)
193{
194 register const struct tcphdr *tp;
195 register const struct ip *ip;
196 register u_char flags;
197 register u_int hlen;
198 register char ch;
199 u_int16_t sport, dport, win, urp;
200 u_int32_t seq, ack, thseq, thack;
201 int threv;
202#ifdef INET6
203 register const struct ip6_hdr *ip6;
204#endif
205
206 tp = (struct tcphdr *)bp;
207 ip = (struct ip *)bp2;
208#ifdef INET6
209 if (IP_V(ip) == 6)
210 ip6 = (struct ip6_hdr *)bp2;
211 else
212 ip6 = NULL;
213#endif /*INET6*/
214 ch = '\0';
215 if (!TTEST(tp->th_dport)) {
216 (void)printf("%s > %s: [|tcp]",
217 ipaddr_string(&ip->ip_src),
218 ipaddr_string(&ip->ip_dst));
219 return;
220 }
221
222 sport = EXTRACT_16BITS(&tp->th_sport);
223 dport = EXTRACT_16BITS(&tp->th_dport);
224
225 hlen = TH_OFF(tp) * 4;
226
227 /*
228 * If data present, header length valid, and NFS port used,
229 * assume NFS.
230 * Pass offset of data plus 4 bytes for RPC TCP msg length
231 * to NFS print routines.
232 */
233 if (!qflag && hlen >= sizeof(*tp) && hlen <= length) {
234 if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg) <= snapend &&
235 dport == NFS_PORT) {
236 nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
237 (u_char *)ip);
238 return;
239 } else if ((u_char *)tp + 4 + sizeof(struct sunrpc_msg)
240 <= snapend &&
241 sport == NFS_PORT) {
242 nfsreply_print((u_char *)tp + hlen + 4, length - hlen,
243 (u_char *)ip);
244 return;
245 }
246 }
247#ifdef INET6
248 if (ip6) {
249 if (ip6->ip6_nxt == IPPROTO_TCP) {
250 (void)printf("%s.%s > %s.%s: ",
251 ip6addr_string(&ip6->ip6_src),
252 tcpport_string(sport),
253 ip6addr_string(&ip6->ip6_dst),
254 tcpport_string(dport));
255 } else {
256 (void)printf("%s > %s: ",
257 tcpport_string(sport), tcpport_string(dport));
258 }
259 } else
260#endif /*INET6*/
261 {
262 if (ip->ip_p == IPPROTO_TCP) {
263 (void)printf("%s.%s > %s.%s: ",
264 ipaddr_string(&ip->ip_src),
265 tcpport_string(sport),
266 ipaddr_string(&ip->ip_dst),
267 tcpport_string(dport));
268 } else {
269 (void)printf("%s > %s: ",
270 tcpport_string(sport), tcpport_string(dport));
271 }
272 }
273
274 if (hlen < sizeof(*tp)) {
275 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
276 length - hlen, hlen, (unsigned long)sizeof(*tp));
277 return;
278 }
279
280 TCHECK(*tp);
281
282 seq = EXTRACT_32BITS(&tp->th_seq);
283 ack = EXTRACT_32BITS(&tp->th_ack);
284 win = EXTRACT_16BITS(&tp->th_win);
285 urp = EXTRACT_16BITS(&tp->th_urp);
286
287 if (qflag) {
288 (void)printf("tcp %d", length - hlen);
289 if (hlen > length) {
290 (void)printf(" [bad hdr length %u - too long, > %u]",
291 hlen, length);
292 }
293 return;
294 }
295 if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
296 TH_ECNECHO|TH_CWR)) {
297 if (flags & TH_SYN)
298 putchar('S');
299 if (flags & TH_FIN)
300 putchar('F');
301 if (flags & TH_RST)
302 putchar('R');
303 if (flags & TH_PUSH)
304 putchar('P');
305 if (flags & TH_CWR)
306 putchar('W'); /* congestion _W_indow reduced (ECN) */
307 if (flags & TH_ECNECHO)
308 putchar('E'); /* ecn _E_cho sent (ECN) */
309 } else
310 putchar('.');
311
312 if (!Sflag && (flags & TH_ACK)) {
313 register struct tcp_seq_hash *th;
314 const void *src, *dst;
315 register int rev;
316 struct tha tha;
317 /*
318 * Find (or record) the initial sequence numbers for
319 * this conversation. (we pick an arbitrary
320 * collating order so there's only one entry for
321 * both directions).
322 */
323#ifdef INET6
324 memset(&tha, 0, sizeof(tha));
325 rev = 0;
326 if (ip6) {
327 src = &ip6->ip6_src;
328 dst = &ip6->ip6_dst;
329 if (sport > dport)
330 rev = 1;
331 else if (sport == dport) {
332 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
333 rev = 1;
334 }
335 if (rev) {
336 memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
337 memcpy(&tha.dst, src, sizeof ip6->ip6_src);
338 tha.port = dport << 16 | sport;
339 } else {
340 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
341 memcpy(&tha.src, src, sizeof ip6->ip6_src);
342 tha.port = sport << 16 | dport;
343 }
344 } else {
345 src = &ip->ip_src;
346 dst = &ip->ip_dst;
347 if (sport > dport)
348 rev = 1;
349 else if (sport == dport) {
350 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
351 rev = 1;
352 }
353 if (rev) {
354 memcpy(&tha.src, dst, sizeof ip->ip_dst);
355 memcpy(&tha.dst, src, sizeof ip->ip_src);
356 tha.port = dport << 16 | sport;
357 } else {
358 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
359 memcpy(&tha.src, src, sizeof ip->ip_src);
360 tha.port = sport << 16 | dport;
361 }
362 }
363#else
364 rev = 0;
365 src = &ip->ip_src;
366 dst = &ip->ip_dst;
367 if (sport > dport)
368 rev = 1;
369 else if (sport == dport) {
370 if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
371 rev = 1;
372 }
373 if (rev) {
374 memcpy(&tha.src, dst, sizeof ip->ip_dst);
375 memcpy(&tha.dst, src, sizeof ip->ip_src);
376 tha.port = dport << 16 | sport;
377 } else {
378 memcpy(&tha.dst, dst, sizeof ip->ip_dst);
379 memcpy(&tha.src, src, sizeof ip->ip_src);
380 tha.port = sport << 16 | dport;
381 }
382#endif
383
384 threv = rev;
385 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
386 th->nxt; th = th->nxt)
387 if (memcmp((char *)&tha, (char *)&th->addr,
388 sizeof(th->addr)) == 0)
389 break;
390
391 if (!th->nxt || (flags & TH_SYN)) {
392 /* didn't find it or new conversation */
393 if (th->nxt == NULL) {
394 th->nxt = (struct tcp_seq_hash *)
395 calloc(1, sizeof(*th));
396 if (th->nxt == NULL)
397 error("tcp_print: calloc");
398 }
399 th->addr = tha;
400 if (rev)
401 th->ack = seq, th->seq = ack - 1;
402 else
403 th->seq = seq, th->ack = ack - 1;
404 } else {
405 if (rev)
406 seq -= th->ack, ack -= th->seq;
407 else
408 seq -= th->seq, ack -= th->ack;
409 }
410
411 thseq = th->seq;
412 thack = th->ack;
413 } else {
414 /*fool gcc*/
415 thseq = thack = threv = 0;
416 }
417 if (hlen > length) {
418 (void)printf(" [bad hdr length %u - too long, > %u]",
419 hlen, length);
420 return;
421 }
422
423 if (IP_V(ip) == 4 && vflag && !fragmented) {
424 u_int16_t sum, tcp_sum;
425 if (TTEST2(tp->th_sport, length)) {
426 sum = tcp_cksum(ip, tp, length);
427
428 (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
429 if (sum != 0) {
430 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
431 (void)printf(" (incorrect (-> 0x%04x),",in_cksum_shouldbe(tcp_sum, sum));
432 } else
433 (void)printf(" (correct),");
434 }
435 }
436#ifdef INET6
437 if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
438 u_int16_t sum,tcp_sum;
439 if (TTEST2(tp->th_sport, length)) {
440 sum = tcp6_cksum(ip6, tp, length);
441 (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
442 if (sum != 0) {
443 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
444 (void)printf(" (incorrect (-> 0x%04x),",in_cksum_shouldbe(tcp_sum, sum));
445 } else
446 (void)printf(" (correct),");
447
448 }
449 }
450#endif
451
452 length -= hlen;
453 if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
454 (void)printf(" %u:%u(%u)", seq, seq + length, length);
455 if (flags & TH_ACK)
456 (void)printf(" ack %u", ack);
457
458 (void)printf(" win %d", win);
459
460 if (flags & TH_URG)
461 (void)printf(" urg %d", urp);
462 /*
463 * Handle any options.
464 */
465 if (hlen > sizeof(*tp)) {
466 register const u_char *cp;
467 register u_int i, opt, datalen;
468 register u_int len;
469
470 hlen -= sizeof(*tp);
471 cp = (const u_char *)tp + sizeof(*tp);
472 putchar(' ');
473 ch = '<';
474 while (hlen > 0) {
475 putchar(ch);
476 TCHECK(*cp);
477 opt = *cp++;
478 if (ZEROLENOPT(opt))
479 len = 1;
480 else {
481 TCHECK(*cp);
482 len = *cp++; /* total including type, len */
483 if (len < 2 || len > hlen)
484 goto bad;
485 --hlen; /* account for length byte */
486 }
487 --hlen; /* account for type byte */
488 datalen = 0;
489
490/* Bail if "l" bytes of data are not left or were not captured */
491#define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
492
493 switch (opt) {
494
495 case TCPOPT_MAXSEG:
496 (void)printf("mss");
497 datalen = 2;
498 LENCHECK(datalen);
499 (void)printf(" %u", EXTRACT_16BITS(cp));
500
501 break;
502
503 case TCPOPT_EOL:
504 (void)printf("eol");
505 break;
506
507 case TCPOPT_NOP:
508 (void)printf("nop");
509 break;
510
511 case TCPOPT_WSCALE:
512 (void)printf("wscale");
513 datalen = 1;
514 LENCHECK(datalen);
515 (void)printf(" %u", *cp);
516 break;
517
518 case TCPOPT_SACKOK:
519 (void)printf("sackOK");
520 break;
521
522 case TCPOPT_SACK:
523 datalen = len - 2;
524 if (datalen % 8 != 0) {
525 (void)printf("malformed sack");
526 } else {
527 u_int32_t s, e;
528
529 (void)printf("sack %d ", datalen / 8);
530 for (i = 0; i < datalen; i += 8) {
531 LENCHECK(i + 4);
532 s = EXTRACT_32BITS(cp + i);
533 LENCHECK(i + 8);
534 e = EXTRACT_32BITS(cp + i + 4);
535 if (threv) {
536 s -= thseq;
537 e -= thseq;
538 } else {
539 s -= thack;
540 e -= thack;
541 }
542 (void)printf("{%u:%u}", s, e);
543 }
544 }
545 break;
546
547 case TCPOPT_ECHO:
548 (void)printf("echo");
549 datalen = 4;
550 LENCHECK(datalen);
551 (void)printf(" %u", EXTRACT_32BITS(cp));
552 break;
553
554 case TCPOPT_ECHOREPLY:
555 (void)printf("echoreply");
556 datalen = 4;
557 LENCHECK(datalen);
558 (void)printf(" %u", EXTRACT_32BITS(cp));
559 break;
560
561 case TCPOPT_TIMESTAMP:
562 (void)printf("timestamp");
563 datalen = 8;
564 LENCHECK(4);
565 (void)printf(" %u", EXTRACT_32BITS(cp));
566 LENCHECK(datalen);
567 (void)printf(" %u", EXTRACT_32BITS(cp + 4));
568 break;
569
570 case TCPOPT_CC:
571 (void)printf("cc");
572 datalen = 4;
573 LENCHECK(datalen);
574 (void)printf(" %u", EXTRACT_32BITS(cp));
575 break;
576
577 case TCPOPT_CCNEW:
578 (void)printf("ccnew");
579 datalen = 4;
580 LENCHECK(datalen);
581 (void)printf(" %u", EXTRACT_32BITS(cp));
582 break;
583
584 case TCPOPT_CCECHO:
585 (void)printf("ccecho");
586 datalen = 4;
587 LENCHECK(datalen);
588 (void)printf(" %u", EXTRACT_32BITS(cp));
589 break;
590
591 case TCPOPT_SIGNATURE:
592 (void)printf("md5:");
593 datalen = TCP_SIGLEN;
594 LENCHECK(datalen);
595#ifdef HAVE_LIBCRYPTO
596 switch (tcp_verify_signature(ip, tp,
597 bp + TH_OFF(tp) * 4, length, cp)) {
598
599 case SIGNATURE_VALID:
600 (void)printf("valid");
601 break;
602
603 case SIGNATURE_INVALID:
604 (void)printf("invalid");
605 break;
606
607 case CANT_CHECK_SIGNATURE:
608 (void)printf("can't check - ");
609 for (i = 0; i < TCP_SIGLEN; ++i)
610 (void)printf("%02x", cp[i]);
611 break;
612 }
613#else
614 for (i = 0; i < TCP_SIGLEN; ++i)
615 (void)printf("%02x", cp[i]);
616#endif
617 break;
618
619 default:
620 (void)printf("opt-%u:", opt);
621 datalen = len - 2;
622 for (i = 0; i < datalen; ++i) {
623 LENCHECK(i);
624 (void)printf("%02x", cp[i]);
625 }
626 break;
627 }
628
629 /* Account for data printed */
630 cp += datalen;
631 hlen -= datalen;
632
633 /* Check specification against observed length */
634 ++datalen; /* option octet */
635 if (!ZEROLENOPT(opt))
636 ++datalen; /* size octet */
637 if (datalen != len)
638 (void)printf("[len %d]", len);
639 ch = ',';
640 if (opt == TCPOPT_EOL)
641 break;
642 }
643 putchar('>');
644 }
645
646 if (length <= 0)
647 return;
648
649 /*
650 * Decode payload if necessary.
651 */
652 bp += TH_OFF(tp) * 4;
653 if (flags & TH_RST) {
654 if (vflag)
655 print_tcp_rst_data(bp, length);
656 } else {
657 if (sport == TELNET_PORT || dport == TELNET_PORT) {
658 if (!qflag && vflag)
659 telnet_print(bp, length);
660 } else if (sport == BGP_PORT || dport == BGP_PORT)
661 bgp_print(bp, length);
662 else if (sport == PPTP_PORT || dport == PPTP_PORT)
663 pptp_print(bp);
664#ifdef TCPDUMP_DO_SMB
665 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
666 nbt_tcp_print(bp, length);
667#endif
668 else if (sport == BEEP_PORT || dport == BEEP_PORT)
669 beep_print(bp, length);
670 else if (length > 2 &&
671 (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
672 sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
673 /*
674 * TCP DNS query has 2byte length at the head.
675 * XXX packet could be unaligned, it can go strange
676 */
677 ns_print(bp + 2, length - 2, 0);
678 } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
679 msdp_print(bp, length);
680 }
681 else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
682 ldp_print(bp, length);
683 }
684 }
685 return;
686bad:
687 fputs("[bad opt]", stdout);
688 if (ch != '\0')
689 putchar('>');
690 return;
691trunc:
692 fputs("[|tcp]", stdout);
693 if (ch != '\0')
694 putchar('>');
695}
696
697/*
698 * RFC1122 says the following on data in RST segments:
699 *
700 * 4.2.2.12 RST Segment: RFC-793 Section 3.4
701 *
702 * A TCP SHOULD allow a received RST segment to include data.
703 *
704 * DISCUSSION
705 * It has been suggested that a RST segment could contain
706 * ASCII text that encoded and explained the cause of the
707 * RST. No standard has yet been established for such
708 * data.
709 *
710 */
711
712static void
713print_tcp_rst_data(register const u_char *sp, u_int length)
714{
715 int c;
716
717 if (TTEST2(*sp, length))
718 printf(" [RST");
719 else
720 printf(" [!RST");
721 if (length > MAX_RST_DATA_LEN) {
722 length = MAX_RST_DATA_LEN; /* can use -X for longer */
723 putchar('+'); /* indicate we truncate */
724 }
725 putchar(' ');
726 while (length-- && sp <= snapend) {
727 c = *sp++;
728 safeputchar(c);
729 }
730 putchar(']');
731}
732
733#ifdef HAVE_LIBCRYPTO
734static int
735tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
736 const u_char *data, int length, const u_char *rcvsig)
737{
738 struct tcphdr tp1;
739 u_char sig[TCP_SIGLEN];
740 char zero_proto = 0;
741 MD5_CTX ctx;
742 u_int16_t savecsum, tlen;
743#ifdef INET6
744 struct ip6_hdr *ip6;
745#endif
746 u_int32_t len32;
747 u_int8_t nxt;
748
749 tp1 = *tp;
750
751 if (tcpmd5secret == NULL)
752 return (CANT_CHECK_SIGNATURE);
753
754 MD5_Init(&ctx);
755 /*
756 * Step 1: Update MD5 hash with IP pseudo-header.
757 */
758 if (IP_V(ip) == 4) {
759 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
760 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
761 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
762 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
763 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
764 tlen = htons(tlen);
765 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
766#ifdef INET6
767 } else if (IP_V(ip) == 6) {
768 ip6 = (struct ip6_hdr *)ip;
769 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
770 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
771 len32 = htonl(ntohs(ip6->ip6_plen));
772 MD5_Update(&ctx, (char *)&len32, sizeof(len32));
773 nxt = 0;
774 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
775 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
776 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
777 nxt = IPPROTO_TCP;
778 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
779#endif
780 } else
781 return (CANT_CHECK_SIGNATURE);
782
783 /*
784 * Step 2: Update MD5 hash with TCP header, excluding options.
785 * The TCP checksum must be set to zero.
786 */
787 savecsum = tp1.th_sum;
788 tp1.th_sum = 0;
789 MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
790 tp1.th_sum = savecsum;
791 /*
792 * Step 3: Update MD5 hash with TCP segment data, if present.
793 */
794 if (length > 0)
795 MD5_Update(&ctx, data, length);
796 /*
797 * Step 4: Update MD5 hash with shared secret.
798 */
799 MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
800 MD5_Final(sig, &ctx);
801
802 if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
803 return (SIGNATURE_VALID);
804 else
805 return (SIGNATURE_INVALID);
806}
807#endif /* HAVE_LIBCRYPTO */