print-tcp.c revision 214478 
1/*	$NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky 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 * Copyright (c) 1999-2004 The tcpdump.org project
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that: (1) source code distributions
11 * retain the above copyright notice and this paragraph in its entirety, (2)
12 * distributions including binary code include the above copyright notice and
13 * this paragraph in its entirety in the documentation or other materials
14 * provided with the distribution, and (3) all advertising materials mentioning
15 * features or use of this software display the following acknowledgement:
16 * ``This product includes software developed by the University of California,
17 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
18 * the University nor the names of its contributors may be used to endorse
19 * or promote products derived from this software without specific prior
20 * written permission.
21 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
22 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
24 */
25
26#ifndef lint
27static const char rcsid[] _U_ =
28"@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.135 2008-11-09 23:35:03 mcr Exp $ (LBL)";
29#else
30__RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $");
31#endif
32
33#ifdef HAVE_CONFIG_H
34#include "config.h"
35#endif
36
37#include <tcpdump-stdinc.h>
38
39#include <stdio.h>
40#include <stdlib.h>
41#include <string.h>
42
43#include "interface.h"
44#include "addrtoname.h"
45#include "extract.h"
46
47#include "tcp.h"
48
49#include "ip.h"
50#ifdef INET6
51#include "ip6.h"
52#endif
53#include "ipproto.h"
54#include "rpc_auth.h"
55#include "rpc_msg.h"
56
57#include "nameser.h"
58
59#ifdef HAVE_LIBCRYPTO
60#include <openssl/md5.h>
61#include <signature.h>
62
63static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
64                                const u_char *data, int length, const u_char *rcvsig);
65#endif
66
67static void print_tcp_rst_data(register const u_char *sp, u_int length);
68
69#define MAX_RST_DATA_LEN	30
70
71
72struct tha {
73#ifndef INET6
74        struct in_addr src;
75        struct in_addr dst;
76#else
77        struct in6_addr src;
78        struct in6_addr dst;
79#endif /*INET6*/
80        u_int port;
81};
82
83struct tcp_seq_hash {
84        struct tcp_seq_hash *nxt;
85        struct tha addr;
86        tcp_seq seq;
87        tcp_seq ack;
88};
89
90#define TSEQ_HASHSIZE 919
91
92/* These tcp optinos do not have the size octet */
93#define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
94
95static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
96
97struct tok tcp_flag_values[] = {
98        { TH_FIN, "F" },
99        { TH_SYN, "S" },
100        { TH_RST, "R" },
101        { TH_PUSH, "P" },
102        { TH_ACK, "." },
103        { TH_URG, "U" },
104        { TH_ECNECHO, "E" },
105        { TH_CWR, "W" },
106        { 0, NULL }
107};
108
109struct tok tcp_option_values[] = {
110        { TCPOPT_EOL, "eol" },
111        { TCPOPT_NOP, "nop" },
112        { TCPOPT_MAXSEG, "mss" },
113        { TCPOPT_WSCALE, "wscale" },
114        { TCPOPT_SACKOK, "sackOK" },
115        { TCPOPT_SACK, "sack" },
116        { TCPOPT_ECHO, "echo" },
117        { TCPOPT_ECHOREPLY, "echoreply" },
118        { TCPOPT_TIMESTAMP, "TS" },
119        { TCPOPT_CC, "cc" },
120        { TCPOPT_CCNEW, "ccnew" },
121        { TCPOPT_CCECHO, "" },
122        { TCPOPT_SIGNATURE, "md5" },
123        { TCPOPT_AUTH, "enhanced auth" },
124        { TCPOPT_UTO, "uto" },
125        { 0, NULL }
126};
127
128static int tcp_cksum(register const struct ip *ip,
129		     register const struct tcphdr *tp,
130		     register u_int len)
131{
132        union phu {
133                struct phdr {
134                        u_int32_t src;
135                        u_int32_t dst;
136                        u_char mbz;
137                        u_char proto;
138                        u_int16_t len;
139                } ph;
140                u_int16_t pa[6];
141        } phu;
142        const u_int16_t *sp;
143
144        /* pseudo-header.. */
145        phu.ph.len = htons((u_int16_t)len);
146        phu.ph.mbz = 0;
147        phu.ph.proto = IPPROTO_TCP;
148        memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
149        if (IP_HL(ip) == 5)
150                memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
151        else
152                phu.ph.dst = ip_finddst(ip);
153
154        sp = &phu.pa[0];
155        return in_cksum((u_short *)tp, len,
156                        sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
157}
158
159void
160tcp_print(register const u_char *bp, register u_int length,
161	  register const u_char *bp2, int fragmented)
162{
163        register const struct tcphdr *tp;
164        register const struct ip *ip;
165        register u_char flags;
166        register u_int hlen;
167        register char ch;
168        u_int16_t sport, dport, win, urp;
169        u_int32_t seq, ack, thseq, thack;
170        u_int utoval;
171        int threv;
172#ifdef INET6
173        register const struct ip6_hdr *ip6;
174#endif
175
176        tp = (struct tcphdr *)bp;
177        ip = (struct ip *)bp2;
178#ifdef INET6
179        if (IP_V(ip) == 6)
180                ip6 = (struct ip6_hdr *)bp2;
181        else
182                ip6 = NULL;
183#endif /*INET6*/
184        ch = '\0';
185        if (!TTEST(tp->th_dport)) {
186                (void)printf("%s > %s: [|tcp]",
187                             ipaddr_string(&ip->ip_src),
188                             ipaddr_string(&ip->ip_dst));
189                return;
190        }
191
192        sport = EXTRACT_16BITS(&tp->th_sport);
193        dport = EXTRACT_16BITS(&tp->th_dport);
194
195        hlen = TH_OFF(tp) * 4;
196
197        /*
198	 * If data present, header length valid, and NFS port used,
199	 * assume NFS.
200	 * Pass offset of data plus 4 bytes for RPC TCP msg length
201	 * to NFS print routines.
202	 */
203	if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
204	    (length - hlen) >= 4) {
205		u_char *fraglenp;
206		u_int32_t fraglen;
207		register struct sunrpc_msg *rp;
208		enum sunrpc_msg_type direction;
209
210		fraglenp = (u_char *)tp + hlen;
211		if (TTEST2(*fraglenp, 4)) {
212			fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
213			if (fraglen > (length - hlen) - 4)
214				fraglen = (length - hlen) - 4;
215			rp = (struct sunrpc_msg *)(fraglenp + 4);
216			if (TTEST(rp->rm_direction)) {
217				direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
218				if (dport == NFS_PORT &&
219				    direction == SUNRPC_CALL) {
220					nfsreq_print((u_char *)rp, fraglen,
221					    (u_char *)ip);
222					return;
223				}
224				if (sport == NFS_PORT &&
225				    direction == SUNRPC_REPLY) {
226					nfsreply_print((u_char *)rp, fraglen,
227					    (u_char *)ip);
228					return;
229				}
230			}
231                }
232        }
233#ifdef INET6
234        if (ip6) {
235                if (ip6->ip6_nxt == IPPROTO_TCP) {
236                        (void)printf("%s.%s > %s.%s: ",
237                                     ip6addr_string(&ip6->ip6_src),
238                                     tcpport_string(sport),
239                                     ip6addr_string(&ip6->ip6_dst),
240                                     tcpport_string(dport));
241                } else {
242                        (void)printf("%s > %s: ",
243                                     tcpport_string(sport), tcpport_string(dport));
244                }
245        } else
246#endif /*INET6*/
247        {
248                if (ip->ip_p == IPPROTO_TCP) {
249                        (void)printf("%s.%s > %s.%s: ",
250                                     ipaddr_string(&ip->ip_src),
251                                     tcpport_string(sport),
252                                     ipaddr_string(&ip->ip_dst),
253                                     tcpport_string(dport));
254                } else {
255                        (void)printf("%s > %s: ",
256                                     tcpport_string(sport), tcpport_string(dport));
257                }
258        }
259
260        if (hlen < sizeof(*tp)) {
261                (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
262                             length - hlen, hlen, (unsigned long)sizeof(*tp));
263                return;
264        }
265
266        TCHECK(*tp);
267
268        seq = EXTRACT_32BITS(&tp->th_seq);
269        ack = EXTRACT_32BITS(&tp->th_ack);
270        win = EXTRACT_16BITS(&tp->th_win);
271        urp = EXTRACT_16BITS(&tp->th_urp);
272
273        if (qflag) {
274                (void)printf("tcp %d", length - hlen);
275                if (hlen > length) {
276                        (void)printf(" [bad hdr length %u - too long, > %u]",
277                                     hlen, length);
278                }
279                return;
280        }
281
282        flags = tp->th_flags;
283        printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
284
285        if (!Sflag && (flags & TH_ACK)) {
286                register struct tcp_seq_hash *th;
287                const void *src, *dst;
288                register int rev;
289                struct tha tha;
290                /*
291                 * Find (or record) the initial sequence numbers for
292                 * this conversation.  (we pick an arbitrary
293                 * collating order so there's only one entry for
294                 * both directions).
295                 */
296#ifdef INET6
297                memset(&tha, 0, sizeof(tha));
298                rev = 0;
299                if (ip6) {
300                        src = &ip6->ip6_src;
301                        dst = &ip6->ip6_dst;
302                        if (sport > dport)
303                                rev = 1;
304                        else if (sport == dport) {
305                                if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
306                                        rev = 1;
307                        }
308                        if (rev) {
309                                memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
310                                memcpy(&tha.dst, src, sizeof ip6->ip6_src);
311                                tha.port = dport << 16 | sport;
312                        } else {
313                                memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
314                                memcpy(&tha.src, src, sizeof ip6->ip6_src);
315                                tha.port = sport << 16 | dport;
316                        }
317                } else {
318                        src = &ip->ip_src;
319                        dst = &ip->ip_dst;
320                        if (sport > dport)
321                                rev = 1;
322                        else if (sport == dport) {
323                                if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
324                                        rev = 1;
325                        }
326                        if (rev) {
327                                memcpy(&tha.src, dst, sizeof ip->ip_dst);
328                                memcpy(&tha.dst, src, sizeof ip->ip_src);
329                                tha.port = dport << 16 | sport;
330                        } else {
331                                memcpy(&tha.dst, dst, sizeof ip->ip_dst);
332                                memcpy(&tha.src, src, sizeof ip->ip_src);
333                                tha.port = sport << 16 | dport;
334                        }
335                }
336#else
337                rev = 0;
338                src = &ip->ip_src;
339                dst = &ip->ip_dst;
340                if (sport > dport)
341                        rev = 1;
342                else if (sport == dport) {
343                        if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
344                                rev = 1;
345                }
346                if (rev) {
347                        memcpy(&tha.src, dst, sizeof ip->ip_dst);
348                        memcpy(&tha.dst, src, sizeof ip->ip_src);
349                        tha.port = dport << 16 | sport;
350                } else {
351                        memcpy(&tha.dst, dst, sizeof ip->ip_dst);
352                        memcpy(&tha.src, src, sizeof ip->ip_src);
353                        tha.port = sport << 16 | dport;
354                }
355#endif
356
357                threv = rev;
358                for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
359                     th->nxt; th = th->nxt)
360                        if (memcmp((char *)&tha, (char *)&th->addr,
361                                   sizeof(th->addr)) == 0)
362                                break;
363
364                if (!th->nxt || (flags & TH_SYN)) {
365                        /* didn't find it or new conversation */
366                        if (th->nxt == NULL) {
367                                th->nxt = (struct tcp_seq_hash *)
368                                        calloc(1, sizeof(*th));
369                                if (th->nxt == NULL)
370                                        error("tcp_print: calloc");
371                        }
372                        th->addr = tha;
373                        if (rev)
374                                th->ack = seq, th->seq = ack - 1;
375                        else
376                                th->seq = seq, th->ack = ack - 1;
377                } else {
378                        if (rev)
379                                seq -= th->ack, ack -= th->seq;
380                        else
381                                seq -= th->seq, ack -= th->ack;
382                }
383
384                thseq = th->seq;
385                thack = th->ack;
386        } else {
387                /*fool gcc*/
388                thseq = thack = threv = 0;
389        }
390        if (hlen > length) {
391                (void)printf(" [bad hdr length %u - too long, > %u]",
392                             hlen, length);
393                return;
394        }
395
396        if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
397                u_int16_t sum, tcp_sum;
398                if (TTEST2(tp->th_sport, length)) {
399                        sum = tcp_cksum(ip, tp, length);
400
401                        (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
402                        if (sum != 0) {
403                                tcp_sum = EXTRACT_16BITS(&tp->th_sum);
404                                (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
405                        } else
406                                (void)printf(" (correct)");
407                }
408        }
409#ifdef INET6
410        if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
411                u_int16_t sum,tcp_sum;
412                if (TTEST2(tp->th_sport, length)) {
413                        sum = nextproto6_cksum(ip6, (u_short *)tp, length, IPPROTO_TCP);
414                        (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
415                        if (sum != 0) {
416                                tcp_sum = EXTRACT_16BITS(&tp->th_sum);
417                                (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
418                        } else
419                                (void)printf(" (correct)");
420
421                }
422        }
423#endif
424
425        length -= hlen;
426        if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
427                (void)printf(", seq %u", seq);
428
429                if (length > 0) {
430                        (void)printf(":%u", seq + length);
431                }
432        }
433
434        if (flags & TH_ACK) {
435                (void)printf(", ack %u", ack);
436        }
437
438        (void)printf(", win %d", win);
439
440        if (flags & TH_URG)
441                (void)printf(", urg %d", urp);
442        /*
443         * Handle any options.
444         */
445        if (hlen > sizeof(*tp)) {
446                register const u_char *cp;
447                register u_int i, opt, datalen;
448                register u_int len;
449
450                hlen -= sizeof(*tp);
451                cp = (const u_char *)tp + sizeof(*tp);
452                printf(", options [");
453                while (hlen > 0) {
454                        if (ch != '\0')
455                                putchar(ch);
456                        TCHECK(*cp);
457                        opt = *cp++;
458                        if (ZEROLENOPT(opt))
459                                len = 1;
460                        else {
461                                TCHECK(*cp);
462                                len = *cp++;	/* total including type, len */
463                                if (len < 2 || len > hlen)
464                                        goto bad;
465                                --hlen;		/* account for length byte */
466                        }
467                        --hlen;			/* account for type byte */
468                        datalen = 0;
469
470/* Bail if "l" bytes of data are not left or were not captured  */
471#define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
472
473
474                        printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
475
476                        switch (opt) {
477
478                        case TCPOPT_MAXSEG:
479                                datalen = 2;
480                                LENCHECK(datalen);
481                                (void)printf(" %u", EXTRACT_16BITS(cp));
482                                break;
483
484                        case TCPOPT_WSCALE:
485                                datalen = 1;
486                                LENCHECK(datalen);
487                                (void)printf(" %u", *cp);
488                                break;
489
490                        case TCPOPT_SACK:
491                                datalen = len - 2;
492                                if (datalen % 8 != 0) {
493                                        (void)printf("malformed sack");
494                                } else {
495                                        u_int32_t s, e;
496
497                                        (void)printf(" %d ", datalen / 8);
498                                        for (i = 0; i < datalen; i += 8) {
499                                                LENCHECK(i + 4);
500                                                s = EXTRACT_32BITS(cp + i);
501                                                LENCHECK(i + 8);
502                                                e = EXTRACT_32BITS(cp + i + 4);
503                                                if (threv) {
504                                                        s -= thseq;
505                                                        e -= thseq;
506                                                } else {
507                                                        s -= thack;
508                                                        e -= thack;
509                                                }
510                                                (void)printf("{%u:%u}", s, e);
511                                        }
512                                }
513                                break;
514
515                        case TCPOPT_CC:
516                        case TCPOPT_CCNEW:
517                        case TCPOPT_CCECHO:
518                        case TCPOPT_ECHO:
519                        case TCPOPT_ECHOREPLY:
520
521                                /*
522                                 * those options share their semantics.
523                                 * fall through
524                                 */
525                                datalen = 4;
526                                LENCHECK(datalen);
527                                (void)printf(" %u", EXTRACT_32BITS(cp));
528                                break;
529
530                        case TCPOPT_TIMESTAMP:
531                                datalen = 8;
532                                LENCHECK(datalen);
533                                (void)printf(" val %u ecr %u",
534                                             EXTRACT_32BITS(cp),
535                                             EXTRACT_32BITS(cp + 4));
536                                break;
537
538                        case TCPOPT_SIGNATURE:
539                                datalen = TCP_SIGLEN;
540                                LENCHECK(datalen);
541#ifdef HAVE_LIBCRYPTO
542                                switch (tcp_verify_signature(ip, tp,
543                                                             bp + TH_OFF(tp) * 4, length, cp)) {
544
545                                case SIGNATURE_VALID:
546                                        (void)printf("valid");
547                                        break;
548
549                                case SIGNATURE_INVALID:
550                                        (void)printf("invalid");
551                                        break;
552
553                                case CANT_CHECK_SIGNATURE:
554                                        (void)printf("can't check - ");
555                                        for (i = 0; i < TCP_SIGLEN; ++i)
556                                                (void)printf("%02x", cp[i]);
557                                        break;
558                                }
559#else
560                                for (i = 0; i < TCP_SIGLEN; ++i)
561                                        (void)printf("%02x", cp[i]);
562#endif
563                                break;
564
565                        case TCPOPT_AUTH:
566                                (void)printf("keyid %d", *cp++);
567                                datalen = len - 3;
568                                for (i = 0; i < datalen; ++i) {
569                                        LENCHECK(i);
570                                        (void)printf("%02x", cp[i]);
571                                }
572                                break;
573
574
575                        case TCPOPT_EOL:
576                        case TCPOPT_NOP:
577                        case TCPOPT_SACKOK:
578                                /*
579                                 * Nothing interesting.
580                                 * fall through
581                                 */
582                                break;
583
584                        case TCPOPT_UTO:
585                                datalen = 2;
586                                LENCHECK(datalen);
587                                utoval = EXTRACT_16BITS(cp);
588                                (void)printf("0x%x", utoval);
589                                if (utoval & 0x0001)
590                                        utoval = (utoval >> 1) * 60;
591                                else
592                                        utoval >>= 1;
593                                (void)printf(" %u", utoval);
594                                break;
595
596                        default:
597                                datalen = len - 2;
598                                for (i = 0; i < datalen; ++i) {
599                                        LENCHECK(i);
600                                        (void)printf("%02x", cp[i]);
601                                }
602                                break;
603                        }
604
605                        /* Account for data printed */
606                        cp += datalen;
607                        hlen -= datalen;
608
609                        /* Check specification against observed length */
610                        ++datalen;			/* option octet */
611                        if (!ZEROLENOPT(opt))
612                                ++datalen;		/* size octet */
613                        if (datalen != len)
614                                (void)printf("[len %d]", len);
615                        ch = ',';
616                        if (opt == TCPOPT_EOL)
617                                break;
618                }
619                putchar(']');
620        }
621
622        /*
623         * Print length field before crawling down the stack.
624         */
625        printf(", length %u", length);
626
627        if (length <= 0)
628                return;
629
630        /*
631         * Decode payload if necessary.
632         */
633        bp += TH_OFF(tp) * 4;
634        if ((flags & TH_RST) && vflag) {
635                print_tcp_rst_data(bp, length);
636                return;
637        }
638
639        if (sport == TELNET_PORT || dport == TELNET_PORT) {
640                if (!qflag && vflag)
641                        telnet_print(bp, length);
642        } else if (sport == BGP_PORT || dport == BGP_PORT)
643                bgp_print(bp, length);
644        else if (sport == PPTP_PORT || dport == PPTP_PORT)
645                pptp_print(bp);
646#ifdef TCPDUMP_DO_SMB
647        else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
648                nbt_tcp_print(bp, length);
649	else if (sport == SMB_PORT || dport == SMB_PORT)
650		smb_tcp_print(bp, length);
651#endif
652        else if (sport == BEEP_PORT || dport == BEEP_PORT)
653                beep_print(bp, length);
654        else if (length > 2 &&
655                 (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
656                  sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
657                /*
658                 * TCP DNS query has 2byte length at the head.
659                 * XXX packet could be unaligned, it can go strange
660                 */
661                ns_print(bp + 2, length - 2, 0);
662        } else if (sport == MSDP_PORT || dport == MSDP_PORT) {
663                msdp_print(bp, length);
664        }
665        else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
666                ldp_print(bp, length);
667        }
668
669        return;
670 bad:
671        fputs("[bad opt]", stdout);
672        if (ch != '\0')
673                putchar('>');
674        return;
675 trunc:
676        fputs("[|tcp]", stdout);
677        if (ch != '\0')
678                putchar('>');
679}
680
681/*
682 * RFC1122 says the following on data in RST segments:
683 *
684 *         4.2.2.12  RST Segment: RFC-793 Section 3.4
685 *
686 *            A TCP SHOULD allow a received RST segment to include data.
687 *
688 *            DISCUSSION
689 *                 It has been suggested that a RST segment could contain
690 *                 ASCII text that encoded and explained the cause of the
691 *                 RST.  No standard has yet been established for such
692 *                 data.
693 *
694 */
695
696static void
697print_tcp_rst_data(register const u_char *sp, u_int length)
698{
699        int c;
700
701        if (TTEST2(*sp, length))
702                printf(" [RST");
703        else
704                printf(" [!RST");
705        if (length > MAX_RST_DATA_LEN) {
706                length = MAX_RST_DATA_LEN;	/* can use -X for longer */
707                putchar('+');			/* indicate we truncate */
708        }
709        putchar(' ');
710        while (length-- && sp <= snapend) {
711                c = *sp++;
712                safeputchar(c);
713        }
714        putchar(']');
715}
716
717#ifdef HAVE_LIBCRYPTO
718static int
719tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
720                     const u_char *data, int length, const u_char *rcvsig)
721{
722        struct tcphdr tp1;
723        u_char sig[TCP_SIGLEN];
724        char zero_proto = 0;
725        MD5_CTX ctx;
726        u_int16_t savecsum, tlen;
727#ifdef INET6
728        struct ip6_hdr *ip6;
729        u_int32_t len32;
730        u_int8_t nxt;
731#endif
732
733	if (data + length > snapend) {
734		printf("snaplen too short, ");
735		return (CANT_CHECK_SIGNATURE);
736	}
737
738        tp1 = *tp;
739
740        if (sigsecret == NULL) {
741		printf("shared secret not supplied with -M, ");
742                return (CANT_CHECK_SIGNATURE);
743        }
744
745        MD5_Init(&ctx);
746        /*
747         * Step 1: Update MD5 hash with IP pseudo-header.
748         */
749        if (IP_V(ip) == 4) {
750                MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
751                MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
752                MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
753                MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
754                tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
755                tlen = htons(tlen);
756                MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
757#ifdef INET6
758        } else if (IP_V(ip) == 6) {
759                ip6 = (struct ip6_hdr *)ip;
760                MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
761                MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
762                len32 = htonl(EXTRACT_16BITS(&ip6->ip6_plen));
763                MD5_Update(&ctx, (char *)&len32, sizeof(len32));
764                nxt = 0;
765                MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
766                MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
767                MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
768                nxt = IPPROTO_TCP;
769                MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
770#endif
771        } else {
772#ifdef INET6
773		printf("IP version not 4 or 6, ");
774#else
775		printf("IP version not 4, ");
776#endif
777                return (CANT_CHECK_SIGNATURE);
778        }
779
780        /*
781         * Step 2: Update MD5 hash with TCP header, excluding options.
782         * The TCP checksum must be set to zero.
783         */
784        savecsum = tp1.th_sum;
785        tp1.th_sum = 0;
786        MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
787        tp1.th_sum = savecsum;
788        /*
789         * Step 3: Update MD5 hash with TCP segment data, if present.
790         */
791        if (length > 0)
792                MD5_Update(&ctx, data, length);
793        /*
794         * Step 4: Update MD5 hash with shared secret.
795         */
796        MD5_Update(&ctx, sigsecret, strlen(sigsecret));
797        MD5_Final(sig, &ctx);
798
799        if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
800                return (SIGNATURE_VALID);
801        else
802                return (SIGNATURE_INVALID);
803}
804#endif /* HAVE_LIBCRYPTO */
805
806/*
807 * Local Variables:
808 * c-style: whitesmith
809 * c-basic-offset: 8
810 * End:
811 */
812