print-tcp.c revision 236192
15992SN/A/* $NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky Exp $ */ 25992SN/A 35992SN/A/* 45992SN/A * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997 55992SN/A * The Regents of the University of California. All rights reserved. 65992SN/A * 75992SN/A * Copyright (c) 1999-2004 The tcpdump.org project 85992SN/A * 95992SN/A * Redistribution and use in source and binary forms, with or without 105992SN/A * modification, are permitted provided that: (1) source code distributions 115992SN/A * retain the above copyright notice and this paragraph in its entirety, (2) 125992SN/A * distributions including binary code include the above copyright notice and 135992SN/A * this paragraph in its entirety in the documentation or other materials 145992SN/A * provided with the distribution, and (3) all advertising materials mentioning 155992SN/A * features or use of this software display the following acknowledgement: 165992SN/A * ``This product includes software developed by the University of California, 175992SN/A * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 185992SN/A * the University nor the names of its contributors may be used to endorse 195992SN/A * or promote products derived from this software without specific prior 205992SN/A * written permission. 215992SN/A * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 225992SN/A * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 235992SN/A * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 245992SN/A */ 255992SN/A 265992SN/A#ifndef lint 275992SN/Astatic const char rcsid[] _U_ = 285992SN/A"@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.135 2008-11-09 23:35:03 mcr Exp $ (LBL)"; 295992SN/A#else 305992SN/A__RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $"); 315992SN/A#endif 325992SN/A 335992SN/A#ifdef HAVE_CONFIG_H 345992SN/A#include "config.h" 355992SN/A#endif 365992SN/A 375992SN/A#include <tcpdump-stdinc.h> 385992SN/A 395992SN/A#include <stdio.h> 405992SN/A#include <stdlib.h> 415992SN/A#include <string.h> 425992SN/A 435992SN/A#include "interface.h" 445992SN/A#include "addrtoname.h" 455992SN/A#include "extract.h" 465992SN/A 475992SN/A#include "tcp.h" 485992SN/A 495992SN/A#include "ip.h" 505992SN/A#ifdef INET6 515992SN/A#include "ip6.h" 525992SN/A#endif 535992SN/A#include "ipproto.h" 545992SN/A#include "rpc_auth.h" 555992SN/A#include "rpc_msg.h" 565992SN/A 575992SN/A#include "nameser.h" 585992SN/A 595992SN/A#ifdef HAVE_LIBCRYPTO 605992SN/A#include <openssl/md5.h> 615992SN/A#include <signature.h> 625992SN/A 635992SN/Astatic int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp, 645992SN/A const u_char *data, int length, const u_char *rcvsig); 655992SN/A#endif 665992SN/A 675992SN/Astatic void print_tcp_rst_data(register const u_char *sp, u_int length); 685992SN/A 695992SN/A#define MAX_RST_DATA_LEN 30 705992SN/A 715992SN/A 725992SN/Astruct tha { 735992SN/A#ifndef INET6 745992SN/A struct in_addr src; 755992SN/A struct in_addr dst; 765992SN/A#else 775992SN/A struct in6_addr src; 785992SN/A struct in6_addr dst; 795992SN/A#endif /*INET6*/ 805992SN/A u_int port; 815992SN/A}; 825992SN/A 835992SN/Astruct tcp_seq_hash { 845992SN/A struct tcp_seq_hash *nxt; 855992SN/A struct tha addr; 867084SN/A tcp_seq seq; 877084SN/A tcp_seq ack; 887084SN/A}; 897084SN/A 905992SN/A#define TSEQ_HASHSIZE 919 915992SN/A 925992SN/A/* These tcp optinos do not have the size octet */ 935992SN/A#define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP) 945992SN/A 955992SN/Astatic struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE]; 965992SN/A 975992SN/Astruct tok tcp_flag_values[] = { 985992SN/A { TH_FIN, "F" }, 995992SN/A { TH_SYN, "S" }, 1005992SN/A { TH_RST, "R" }, 1015992SN/A { TH_PUSH, "P" }, 1025992SN/A { TH_ACK, "." }, 1035992SN/A { TH_URG, "U" }, 1045992SN/A { TH_ECNECHO, "E" }, 1057084SN/A { TH_CWR, "W" }, 1065992SN/A { 0, NULL } 1075992SN/A}; 1085992SN/A 1095992SN/Astruct tok tcp_option_values[] = { 1107084SN/A { TCPOPT_EOL, "eol" }, 1115992SN/A { TCPOPT_NOP, "nop" }, 1125992SN/A { 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 return (nextproto4_cksum(ip, (const u_int8_t *)tp, len, 133 IPPROTO_TCP)); 134} 135 136void 137tcp_print(register const u_char *bp, register u_int length, 138 register const u_char *bp2, int fragmented) 139{ 140 register const struct tcphdr *tp; 141 register const struct ip *ip; 142 register u_char flags; 143 register u_int hlen; 144 register char ch; 145 u_int16_t sport, dport, win, urp; 146 u_int32_t seq, ack, thseq, thack; 147 u_int utoval; 148 int threv; 149#ifdef INET6 150 register const struct ip6_hdr *ip6; 151#endif 152 153 tp = (struct tcphdr *)bp; 154 ip = (struct ip *)bp2; 155#ifdef INET6 156 if (IP_V(ip) == 6) 157 ip6 = (struct ip6_hdr *)bp2; 158 else 159 ip6 = NULL; 160#endif /*INET6*/ 161 ch = '\0'; 162 if (!TTEST(tp->th_dport)) { 163 (void)printf("%s > %s: [|tcp]", 164 ipaddr_string(&ip->ip_src), 165 ipaddr_string(&ip->ip_dst)); 166 return; 167 } 168 169 sport = EXTRACT_16BITS(&tp->th_sport); 170 dport = EXTRACT_16BITS(&tp->th_dport); 171 172 hlen = TH_OFF(tp) * 4; 173 174 /* 175 * If data present, header length valid, and NFS port used, 176 * assume NFS. 177 * Pass offset of data plus 4 bytes for RPC TCP msg length 178 * to NFS print routines. 179 */ 180 if (!qflag && hlen >= sizeof(*tp) && hlen <= length && 181 (length - hlen) >= 4) { 182 u_char *fraglenp; 183 u_int32_t fraglen; 184 register struct sunrpc_msg *rp; 185 enum sunrpc_msg_type direction; 186 187 fraglenp = (u_char *)tp + hlen; 188 if (TTEST2(*fraglenp, 4)) { 189 fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF; 190 if (fraglen > (length - hlen) - 4) 191 fraglen = (length - hlen) - 4; 192 rp = (struct sunrpc_msg *)(fraglenp + 4); 193 if (TTEST(rp->rm_direction)) { 194 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction); 195 if (dport == NFS_PORT && 196 direction == SUNRPC_CALL) { 197 nfsreq_print((u_char *)rp, fraglen, 198 (u_char *)ip); 199 return; 200 } 201 if (sport == NFS_PORT && 202 direction == SUNRPC_REPLY) { 203 nfsreply_print((u_char *)rp, fraglen, 204 (u_char *)ip); 205 return; 206 } 207 } 208 } 209 } 210#ifdef INET6 211 if (ip6) { 212 if (ip6->ip6_nxt == IPPROTO_TCP) { 213 (void)printf("%s.%s > %s.%s: ", 214 ip6addr_string(&ip6->ip6_src), 215 tcpport_string(sport), 216 ip6addr_string(&ip6->ip6_dst), 217 tcpport_string(dport)); 218 } else { 219 (void)printf("%s > %s: ", 220 tcpport_string(sport), tcpport_string(dport)); 221 } 222 } else 223#endif /*INET6*/ 224 { 225 if (ip->ip_p == IPPROTO_TCP) { 226 (void)printf("%s.%s > %s.%s: ", 227 ipaddr_string(&ip->ip_src), 228 tcpport_string(sport), 229 ipaddr_string(&ip->ip_dst), 230 tcpport_string(dport)); 231 } else { 232 (void)printf("%s > %s: ", 233 tcpport_string(sport), tcpport_string(dport)); 234 } 235 } 236 237 if (hlen < sizeof(*tp)) { 238 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]", 239 length - hlen, hlen, (unsigned long)sizeof(*tp)); 240 return; 241 } 242 243 TCHECK(*tp); 244 245 seq = EXTRACT_32BITS(&tp->th_seq); 246 ack = EXTRACT_32BITS(&tp->th_ack); 247 win = EXTRACT_16BITS(&tp->th_win); 248 urp = EXTRACT_16BITS(&tp->th_urp); 249 250 if (qflag) { 251 (void)printf("tcp %d", length - hlen); 252 if (hlen > length) { 253 (void)printf(" [bad hdr length %u - too long, > %u]", 254 hlen, length); 255 } 256 return; 257 } 258 259 flags = tp->th_flags; 260 printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags)); 261 262 if (!Sflag && (flags & TH_ACK)) { 263 register struct tcp_seq_hash *th; 264 const void *src, *dst; 265 register int rev; 266 struct tha tha; 267 /* 268 * Find (or record) the initial sequence numbers for 269 * this conversation. (we pick an arbitrary 270 * collating order so there's only one entry for 271 * both directions). 272 */ 273#ifdef INET6 274 rev = 0; 275 if (ip6) { 276 src = &ip6->ip6_src; 277 dst = &ip6->ip6_dst; 278 if (sport > dport) 279 rev = 1; 280 else if (sport == dport) { 281 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0) 282 rev = 1; 283 } 284 if (rev) { 285 memcpy(&tha.src, dst, sizeof ip6->ip6_dst); 286 memcpy(&tha.dst, src, sizeof ip6->ip6_src); 287 tha.port = dport << 16 | sport; 288 } else { 289 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst); 290 memcpy(&tha.src, src, sizeof ip6->ip6_src); 291 tha.port = sport << 16 | dport; 292 } 293 } else { 294 /* 295 * Zero out the tha structure; the src and dst 296 * fields are big enough to hold an IPv6 297 * address, but we only have IPv4 addresses 298 * and thus must clear out the remaining 124 299 * bits. 300 * 301 * XXX - should we just clear those bytes after 302 * copying the IPv4 addresses, rather than 303 * zeroing out the entire structure and then 304 * overwriting some of the zeroes? 305 * 306 * XXX - this could fail if we see TCP packets 307 * with an IPv6 address with the lower 124 bits 308 * all zero and also see TCP packes with an 309 * IPv4 address with the same 32 bits as the 310 * upper 32 bits of the IPv6 address in question. 311 * Can that happen? Is it likely enough to be 312 * an issue? 313 */ 314 memset(&tha, 0, sizeof(tha)); 315 src = &ip->ip_src; 316 dst = &ip->ip_dst; 317 if (sport > dport) 318 rev = 1; 319 else if (sport == dport) { 320 if (memcmp(src, dst, sizeof ip->ip_dst) > 0) 321 rev = 1; 322 } 323 if (rev) { 324 memcpy(&tha.src, dst, sizeof ip->ip_dst); 325 memcpy(&tha.dst, src, sizeof ip->ip_src); 326 tha.port = dport << 16 | sport; 327 } else { 328 memcpy(&tha.dst, dst, sizeof ip->ip_dst); 329 memcpy(&tha.src, src, sizeof ip->ip_src); 330 tha.port = sport << 16 | dport; 331 } 332 } 333#else 334 rev = 0; 335 src = &ip->ip_src; 336 dst = &ip->ip_dst; 337 if (sport > dport) 338 rev = 1; 339 else if (sport == dport) { 340 if (memcmp(src, dst, sizeof ip->ip_dst) > 0) 341 rev = 1; 342 } 343 if (rev) { 344 memcpy(&tha.src, dst, sizeof ip->ip_dst); 345 memcpy(&tha.dst, src, sizeof ip->ip_src); 346 tha.port = dport << 16 | sport; 347 } else { 348 memcpy(&tha.dst, dst, sizeof ip->ip_dst); 349 memcpy(&tha.src, src, sizeof ip->ip_src); 350 tha.port = sport << 16 | dport; 351 } 352#endif 353 354 threv = rev; 355 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE]; 356 th->nxt; th = th->nxt) 357 if (memcmp((char *)&tha, (char *)&th->addr, 358 sizeof(th->addr)) == 0) 359 break; 360 361 if (!th->nxt || (flags & TH_SYN)) { 362 /* didn't find it or new conversation */ 363 if (th->nxt == NULL) { 364 th->nxt = (struct tcp_seq_hash *) 365 calloc(1, sizeof(*th)); 366 if (th->nxt == NULL) 367 error("tcp_print: calloc"); 368 } 369 th->addr = tha; 370 if (rev) 371 th->ack = seq, th->seq = ack - 1; 372 else 373 th->seq = seq, th->ack = ack - 1; 374 } else { 375 if (rev) 376 seq -= th->ack, ack -= th->seq; 377 else 378 seq -= th->seq, ack -= th->ack; 379 } 380 381 thseq = th->seq; 382 thack = th->ack; 383 } else { 384 /*fool gcc*/ 385 thseq = thack = threv = 0; 386 } 387 if (hlen > length) { 388 (void)printf(" [bad hdr length %u - too long, > %u]", 389 hlen, length); 390 return; 391 } 392 393 if (vflag && !Kflag && !fragmented) { 394 /* Check the checksum, if possible. */ 395 u_int16_t sum, tcp_sum; 396 397 if (IP_V(ip) == 4) { 398 if (TTEST2(tp->th_sport, length)) { 399 sum = tcp_cksum(ip, tp, length); 400 tcp_sum = EXTRACT_16BITS(&tp->th_sum); 401 402 (void)printf(", cksum 0x%04x", tcp_sum); 403 if (sum != 0) 404 (void)printf(" (incorrect -> 0x%04x)", 405 in_cksum_shouldbe(tcp_sum, sum)); 406 else 407 (void)printf(" (correct)"); 408 } 409 } 410#ifdef INET6 411 else if (IP_V(ip) == 6 && ip6->ip6_plen) { 412 if (TTEST2(tp->th_sport, length)) { 413 sum = nextproto6_cksum(ip6, (const u_int8_t *)tp, length, IPPROTO_TCP); 414 tcp_sum = EXTRACT_16BITS(&tp->th_sum); 415 416 (void)printf(", cksum 0x%04x", tcp_sum); 417 if (sum != 0) 418 (void)printf(" (incorrect -> 0x%04x)", 419 in_cksum_shouldbe(tcp_sum, sum)); 420 else 421 (void)printf(" (correct)"); 422 423 } 424 } 425#endif 426 } 427 428 length -= hlen; 429 if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) { 430 (void)printf(", seq %u", seq); 431 432 if (length > 0) { 433 (void)printf(":%u", seq + length); 434 } 435 } 436 437 if (flags & TH_ACK) { 438 (void)printf(", ack %u", ack); 439 } 440 441 (void)printf(", win %d", win); 442 443 if (flags & TH_URG) 444 (void)printf(", urg %d", urp); 445 /* 446 * Handle any options. 447 */ 448 if (hlen > sizeof(*tp)) { 449 register const u_char *cp; 450 register u_int i, opt, datalen; 451 register u_int len; 452 453 hlen -= sizeof(*tp); 454 cp = (const u_char *)tp + sizeof(*tp); 455 printf(", options ["); 456 while (hlen > 0) { 457 if (ch != '\0') 458 putchar(ch); 459 TCHECK(*cp); 460 opt = *cp++; 461 if (ZEROLENOPT(opt)) 462 len = 1; 463 else { 464 TCHECK(*cp); 465 len = *cp++; /* total including type, len */ 466 if (len < 2 || len > hlen) 467 goto bad; 468 --hlen; /* account for length byte */ 469 } 470 --hlen; /* account for type byte */ 471 datalen = 0; 472 473/* Bail if "l" bytes of data are not left or were not captured */ 474#define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); } 475 476 477 printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt)); 478 479 switch (opt) { 480 481 case TCPOPT_MAXSEG: 482 datalen = 2; 483 LENCHECK(datalen); 484 (void)printf(" %u", EXTRACT_16BITS(cp)); 485 break; 486 487 case TCPOPT_WSCALE: 488 datalen = 1; 489 LENCHECK(datalen); 490 (void)printf(" %u", *cp); 491 break; 492 493 case TCPOPT_SACK: 494 datalen = len - 2; 495 if (datalen % 8 != 0) { 496 (void)printf("malformed sack"); 497 } else { 498 u_int32_t s, e; 499 500 (void)printf(" %d ", datalen / 8); 501 for (i = 0; i < datalen; i += 8) { 502 LENCHECK(i + 4); 503 s = EXTRACT_32BITS(cp + i); 504 LENCHECK(i + 8); 505 e = EXTRACT_32BITS(cp + i + 4); 506 if (threv) { 507 s -= thseq; 508 e -= thseq; 509 } else { 510 s -= thack; 511 e -= thack; 512 } 513 (void)printf("{%u:%u}", s, e); 514 } 515 } 516 break; 517 518 case TCPOPT_CC: 519 case TCPOPT_CCNEW: 520 case TCPOPT_CCECHO: 521 case TCPOPT_ECHO: 522 case TCPOPT_ECHOREPLY: 523 524 /* 525 * those options share their semantics. 526 * fall through 527 */ 528 datalen = 4; 529 LENCHECK(datalen); 530 (void)printf(" %u", EXTRACT_32BITS(cp)); 531 break; 532 533 case TCPOPT_TIMESTAMP: 534 datalen = 8; 535 LENCHECK(datalen); 536 (void)printf(" val %u ecr %u", 537 EXTRACT_32BITS(cp), 538 EXTRACT_32BITS(cp + 4)); 539 break; 540 541 case TCPOPT_SIGNATURE: 542 datalen = TCP_SIGLEN; 543 LENCHECK(datalen); 544#ifdef HAVE_LIBCRYPTO 545 switch (tcp_verify_signature(ip, tp, 546 bp + TH_OFF(tp) * 4, length, cp)) { 547 548 case SIGNATURE_VALID: 549 (void)printf("valid"); 550 break; 551 552 case SIGNATURE_INVALID: 553 (void)printf("invalid"); 554 break; 555 556 case CANT_CHECK_SIGNATURE: 557 (void)printf("can't check - "); 558 for (i = 0; i < TCP_SIGLEN; ++i) 559 (void)printf("%02x", cp[i]); 560 break; 561 } 562#else 563 for (i = 0; i < TCP_SIGLEN; ++i) 564 (void)printf("%02x", cp[i]); 565#endif 566 break; 567 568 case TCPOPT_AUTH: 569 (void)printf("keyid %d", *cp++); 570 datalen = len - 3; 571 for (i = 0; i < datalen; ++i) { 572 LENCHECK(i); 573 (void)printf("%02x", cp[i]); 574 } 575 break; 576 577 578 case TCPOPT_EOL: 579 case TCPOPT_NOP: 580 case TCPOPT_SACKOK: 581 /* 582 * Nothing interesting. 583 * fall through 584 */ 585 break; 586 587 case TCPOPT_UTO: 588 datalen = 2; 589 LENCHECK(datalen); 590 utoval = EXTRACT_16BITS(cp); 591 (void)printf("0x%x", utoval); 592 if (utoval & 0x0001) 593 utoval = (utoval >> 1) * 60; 594 else 595 utoval >>= 1; 596 (void)printf(" %u", utoval); 597 break; 598 599 default: 600 datalen = len - 2; 601 for (i = 0; i < datalen; ++i) { 602 LENCHECK(i); 603 (void)printf("%02x", cp[i]); 604 } 605 break; 606 } 607 608 /* Account for data printed */ 609 cp += datalen; 610 hlen -= datalen; 611 612 /* Check specification against observed length */ 613 ++datalen; /* option octet */ 614 if (!ZEROLENOPT(opt)) 615 ++datalen; /* size octet */ 616 if (datalen != len) 617 (void)printf("[len %d]", len); 618 ch = ','; 619 if (opt == TCPOPT_EOL) 620 break; 621 } 622 putchar(']'); 623 } 624 625 /* 626 * Print length field before crawling down the stack. 627 */ 628 printf(", length %u", length); 629 630 if (length <= 0) 631 return; 632 633 /* 634 * Decode payload if necessary. 635 */ 636 bp += TH_OFF(tp) * 4; 637 if ((flags & TH_RST) && vflag) { 638 print_tcp_rst_data(bp, length); 639 return; 640 } 641 642 if (sport == TELNET_PORT || dport == TELNET_PORT) { 643 if (!qflag && vflag) 644 telnet_print(bp, length); 645 } else if (sport == BGP_PORT || dport == BGP_PORT) 646 bgp_print(bp, length); 647 else if (sport == PPTP_PORT || dport == PPTP_PORT) 648 pptp_print(bp); 649#ifdef TCPDUMP_DO_SMB 650 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT) 651 nbt_tcp_print(bp, length); 652 else if (sport == SMB_PORT || dport == SMB_PORT) 653 smb_tcp_print(bp, length); 654#endif 655 else if (sport == BEEP_PORT || dport == BEEP_PORT) 656 beep_print(bp, length); 657 else if (length > 2 && 658 (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT || 659 sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) { 660 /* 661 * TCP DNS query has 2byte length at the head. 662 * XXX packet could be unaligned, it can go strange 663 */ 664 ns_print(bp + 2, length - 2, 0); 665 } else if (sport == MSDP_PORT || dport == MSDP_PORT) { 666 msdp_print(bp, length); 667 } else if (sport == RPKI_RTR_PORT || dport == RPKI_RTR_PORT) { 668 rpki_rtr_print(bp, length); 669 } 670 else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) { 671 ldp_print(bp, length); 672 } 673 674 return; 675 bad: 676 fputs("[bad opt]", stdout); 677 if (ch != '\0') 678 putchar('>'); 679 return; 680 trunc: 681 fputs("[|tcp]", stdout); 682 if (ch != '\0') 683 putchar('>'); 684} 685 686/* 687 * RFC1122 says the following on data in RST segments: 688 * 689 * 4.2.2.12 RST Segment: RFC-793 Section 3.4 690 * 691 * A TCP SHOULD allow a received RST segment to include data. 692 * 693 * DISCUSSION 694 * It has been suggested that a RST segment could contain 695 * ASCII text that encoded and explained the cause of the 696 * RST. No standard has yet been established for such 697 * data. 698 * 699 */ 700 701static void 702print_tcp_rst_data(register const u_char *sp, u_int length) 703{ 704 int c; 705 706 if (TTEST2(*sp, length)) 707 printf(" [RST"); 708 else 709 printf(" [!RST"); 710 if (length > MAX_RST_DATA_LEN) { 711 length = MAX_RST_DATA_LEN; /* can use -X for longer */ 712 putchar('+'); /* indicate we truncate */ 713 } 714 putchar(' '); 715 while (length-- && sp <= snapend) { 716 c = *sp++; 717 safeputchar(c); 718 } 719 putchar(']'); 720} 721 722#ifdef HAVE_LIBCRYPTO 723static int 724tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp, 725 const u_char *data, int length, const u_char *rcvsig) 726{ 727 struct tcphdr tp1; 728 u_char sig[TCP_SIGLEN]; 729 char zero_proto = 0; 730 MD5_CTX ctx; 731 u_int16_t savecsum, tlen; 732#ifdef INET6 733 struct ip6_hdr *ip6; 734 u_int32_t len32; 735 u_int8_t nxt; 736#endif 737 738 if (data + length > snapend) { 739 printf("snaplen too short, "); 740 return (CANT_CHECK_SIGNATURE); 741 } 742 743 tp1 = *tp; 744 745 if (sigsecret == NULL) { 746 printf("shared secret not supplied with -M, "); 747 return (CANT_CHECK_SIGNATURE); 748 } 749 750 MD5_Init(&ctx); 751 /* 752 * Step 1: Update MD5 hash with IP pseudo-header. 753 */ 754 if (IP_V(ip) == 4) { 755 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src)); 756 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst)); 757 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto)); 758 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p)); 759 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4; 760 tlen = htons(tlen); 761 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen)); 762#ifdef INET6 763 } else if (IP_V(ip) == 6) { 764 ip6 = (struct ip6_hdr *)ip; 765 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src)); 766 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst)); 767 len32 = htonl(EXTRACT_16BITS(&ip6->ip6_plen)); 768 MD5_Update(&ctx, (char *)&len32, sizeof(len32)); 769 nxt = 0; 770 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 771 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 772 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 773 nxt = IPPROTO_TCP; 774 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 775#endif 776 } else { 777#ifdef INET6 778 printf("IP version not 4 or 6, "); 779#else 780 printf("IP version not 4, "); 781#endif 782 return (CANT_CHECK_SIGNATURE); 783 } 784 785 /* 786 * Step 2: Update MD5 hash with TCP header, excluding options. 787 * The TCP checksum must be set to zero. 788 */ 789 savecsum = tp1.th_sum; 790 tp1.th_sum = 0; 791 MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr)); 792 tp1.th_sum = savecsum; 793 /* 794 * Step 3: Update MD5 hash with TCP segment data, if present. 795 */ 796 if (length > 0) 797 MD5_Update(&ctx, data, length); 798 /* 799 * Step 4: Update MD5 hash with shared secret. 800 */ 801 MD5_Update(&ctx, sigsecret, strlen(sigsecret)); 802 MD5_Final(sig, &ctx); 803 804 if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0) 805 return (SIGNATURE_VALID); 806 else 807 return (SIGNATURE_INVALID); 808} 809#endif /* HAVE_LIBCRYPTO */ 810 811/* 812 * Local Variables: 813 * c-style: whitesmith 814 * c-basic-offset: 8 815 * End: 816 */ 817