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 27 static const char rcsid[] _U_ = 28 "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.130.2.3 2007-12-22 03:08:45 guy 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 62 #define SIGNATURE_VALID 0 63 #define SIGNATURE_INVALID 1 64 #define CANT_CHECK_SIGNATURE 2 65 66 static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp, 67 const u_char *data, int length, const u_char *rcvsig); 68 #endif 69 70 static void print_tcp_rst_data(register const u_char *sp, u_int length); 71 72 #define MAX_RST_DATA_LEN 30 73 74 75 struct tha { 76 #ifndef INET6 77 struct in_addr src; 78 struct in_addr dst; 79 #else 80 struct in6_addr src; 81 struct in6_addr dst; 82 #endif /*INET6*/ 83 u_int port; 84 }; 85 86 struct tcp_seq_hash { 87 struct tcp_seq_hash *nxt; 88 struct tha addr; 89 tcp_seq seq; 90 tcp_seq ack; 91 }; 92 93 #define TSEQ_HASHSIZE 919 94 95 /* These tcp optinos do not have the size octet */ 96 #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP) 97 98 static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE]; 99 100 struct tok tcp_flag_values[] = { 101 { TH_FIN, "F" }, 102 { TH_SYN, "S" }, 103 { TH_RST, "R" }, 104 { TH_PUSH, "P" }, 105 { TH_ACK, "." }, 106 { TH_URG, "U" }, 107 { TH_ECNECHO, "E" }, 108 { TH_CWR, "W" }, 109 { 0, NULL } 110 }; 111 112 struct tok tcp_option_values[] = { 113 { TCPOPT_EOL, "eol" }, 114 { TCPOPT_NOP, "nop" }, 115 { TCPOPT_MAXSEG, "mss" }, 116 { TCPOPT_WSCALE, "wscale" }, 117 { TCPOPT_SACKOK, "sackOK" }, 118 { TCPOPT_SACK, "sack" }, 119 { TCPOPT_ECHO, "echo" }, 120 { TCPOPT_ECHOREPLY, "echoreply" }, 121 { TCPOPT_TIMESTAMP, "TS" }, 122 { TCPOPT_CC, "cc" }, 123 { TCPOPT_CCNEW, "ccnew" }, 124 { TCPOPT_CCECHO, "" }, 125 { TCPOPT_SIGNATURE, "md5" }, 126 { TCPOPT_AUTH, "enhanced auth" }, 127 { TCPOPT_UTO, "uto" }, 128 { 0, NULL } 129 }; 130 131 static int tcp_cksum(register const struct ip *ip, 132 register const struct tcphdr *tp, 133 register u_int len) 134 { 135 union phu { 136 struct phdr { 137 u_int32_t src; 138 u_int32_t dst; 139 u_char mbz; 140 u_char proto; 141 u_int16_t len; 142 } ph; 143 u_int16_t pa[6]; 144 } phu; 145 const u_int16_t *sp; 146 147 /* pseudo-header.. */ 148 phu.ph.len = htons((u_int16_t)len); 149 phu.ph.mbz = 0; 150 phu.ph.proto = IPPROTO_TCP; 151 memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t)); 152 if (IP_HL(ip) == 5) 153 memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t)); 154 else 155 phu.ph.dst = ip_finddst(ip); 156 157 sp = &phu.pa[0]; 158 return in_cksum((u_short *)tp, len, 159 sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]); 160 } 161 162 #ifdef INET6 163 static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp, 164 u_int len) 165 { 166 size_t i; 167 u_int32_t sum = 0; 168 union { 169 struct { 170 struct in6_addr ph_src; 171 struct in6_addr ph_dst; 172 u_int32_t ph_len; 173 u_int8_t ph_zero[3]; 174 u_int8_t ph_nxt; 175 } ph; 176 u_int16_t pa[20]; 177 } phu; 178 179 /* pseudo-header */ 180 memset(&phu, 0, sizeof(phu)); 181 phu.ph.ph_src = ip6->ip6_src; 182 phu.ph.ph_dst = ip6->ip6_dst; 183 phu.ph.ph_len = htonl(len); 184 phu.ph.ph_nxt = IPPROTO_TCP; 185 186 for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++) 187 sum += phu.pa[i]; 188 189 return in_cksum((u_short *)tp, len, sum); 190 } 191 #endif 192 193 void 194 tcp_print(register const u_char *bp, register u_int length, 195 register const u_char *bp2, int fragmented) 196 { 197 register const struct tcphdr *tp; 198 register const struct ip *ip; 199 register u_char flags; 200 register u_int hlen; 201 register char ch; 202 u_int16_t sport, dport, win, urp; 203 u_int32_t seq, ack, thseq, thack; 204 int threv; 205 #ifdef INET6 206 register const struct ip6_hdr *ip6; 207 #endif 208 209 tp = (struct tcphdr *)bp; 210 ip = (struct ip *)bp2; 211 #ifdef INET6 212 if (IP_V(ip) == 6) 213 ip6 = (struct ip6_hdr *)bp2; 214 else 215 ip6 = NULL; 216 #endif /*INET6*/ 217 ch = '\0'; 218 if (!TTEST(tp->th_dport)) { 219 (void)printf("%s > %s: [|tcp]", 220 ipaddr_string(&ip->ip_src), 221 ipaddr_string(&ip->ip_dst)); 222 return; 223 } 224 225 sport = EXTRACT_16BITS(&tp->th_sport); 226 dport = EXTRACT_16BITS(&tp->th_dport); 227 228 hlen = TH_OFF(tp) * 4; 229 230 /* 231 * If data present, header length valid, and NFS port used, 232 * assume NFS. 233 * Pass offset of data plus 4 bytes for RPC TCP msg length 234 * to NFS print routines. 235 */ 236 if (!qflag && hlen >= sizeof(*tp) && hlen <= length && 237 (length - hlen) >= 4) { 238 u_char *fraglenp; 239 u_int32_t fraglen; 240 register struct sunrpc_msg *rp; 241 enum sunrpc_msg_type direction; 242 243 fraglenp = (u_char *)tp + hlen; 244 if (TTEST2(*fraglenp, 4)) { 245 fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF; 246 if (fraglen > (length - hlen) - 4) 247 fraglen = (length - hlen) - 4; 248 rp = (struct sunrpc_msg *)(fraglenp + 4); 249 if (TTEST(rp->rm_direction)) { 250 direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction); 251 if (dport == NFS_PORT && 252 direction == SUNRPC_CALL) { 253 nfsreq_print((u_char *)rp, fraglen, 254 (u_char *)ip); 255 return; 256 } 257 if (sport == NFS_PORT && 258 direction == SUNRPC_REPLY) { 259 nfsreply_print((u_char *)rp, fraglen, 260 (u_char *)ip); 261 return; 262 } 263 } 264 } 265 } 266 #ifdef INET6 267 if (ip6) { 268 if (ip6->ip6_nxt == IPPROTO_TCP) { 269 (void)printf("%s.%s > %s.%s: ", 270 ip6addr_string(&ip6->ip6_src), 271 tcpport_string(sport), 272 ip6addr_string(&ip6->ip6_dst), 273 tcpport_string(dport)); 274 } else { 275 (void)printf("%s > %s: ", 276 tcpport_string(sport), tcpport_string(dport)); 277 } 278 } else 279 #endif /*INET6*/ 280 { 281 if (ip->ip_p == IPPROTO_TCP) { 282 (void)printf("%s.%s > %s.%s: ", 283 ipaddr_string(&ip->ip_src), 284 tcpport_string(sport), 285 ipaddr_string(&ip->ip_dst), 286 tcpport_string(dport)); 287 } else { 288 (void)printf("%s > %s: ", 289 tcpport_string(sport), tcpport_string(dport)); 290 } 291 } 292 293 if (hlen < sizeof(*tp)) { 294 (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]", 295 length - hlen, hlen, (unsigned long)sizeof(*tp)); 296 return; 297 } 298 299 TCHECK(*tp); 300 301 seq = EXTRACT_32BITS(&tp->th_seq); 302 ack = EXTRACT_32BITS(&tp->th_ack); 303 win = EXTRACT_16BITS(&tp->th_win); 304 urp = EXTRACT_16BITS(&tp->th_urp); 305 306 if (qflag) { 307 (void)printf("tcp %d", length - hlen); 308 if (hlen > length) { 309 (void)printf(" [bad hdr length %u - too long, > %u]", 310 hlen, length); 311 } 312 return; 313 } 314 315 flags = tp->th_flags; 316 printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags)); 317 318 if (!Sflag && (flags & TH_ACK)) { 319 register struct tcp_seq_hash *th; 320 const void *src, *dst; 321 register int rev; 322 struct tha tha; 323 /* 324 * Find (or record) the initial sequence numbers for 325 * this conversation. (we pick an arbitrary 326 * collating order so there's only one entry for 327 * both directions). 328 */ 329 #ifdef INET6 330 memset(&tha, 0, sizeof(tha)); 331 rev = 0; 332 if (ip6) { 333 src = &ip6->ip6_src; 334 dst = &ip6->ip6_dst; 335 if (sport > dport) 336 rev = 1; 337 else if (sport == dport) { 338 if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0) 339 rev = 1; 340 } 341 if (rev) { 342 memcpy(&tha.src, dst, sizeof ip6->ip6_dst); 343 memcpy(&tha.dst, src, sizeof ip6->ip6_src); 344 tha.port = dport << 16 | sport; 345 } else { 346 memcpy(&tha.dst, dst, sizeof ip6->ip6_dst); 347 memcpy(&tha.src, src, sizeof ip6->ip6_src); 348 tha.port = sport << 16 | dport; 349 } 350 } else { 351 src = &ip->ip_src; 352 dst = &ip->ip_dst; 353 if (sport > dport) 354 rev = 1; 355 else if (sport == dport) { 356 if (memcmp(src, dst, sizeof ip->ip_dst) > 0) 357 rev = 1; 358 } 359 if (rev) { 360 memcpy(&tha.src, dst, sizeof ip->ip_dst); 361 memcpy(&tha.dst, src, sizeof ip->ip_src); 362 tha.port = dport << 16 | sport; 363 } else { 364 memcpy(&tha.dst, dst, sizeof ip->ip_dst); 365 memcpy(&tha.src, src, sizeof ip->ip_src); 366 tha.port = sport << 16 | dport; 367 } 368 } 369 #else 370 rev = 0; 371 src = &ip->ip_src; 372 dst = &ip->ip_dst; 373 if (sport > dport) 374 rev = 1; 375 else if (sport == dport) { 376 if (memcmp(src, dst, sizeof ip->ip_dst) > 0) 377 rev = 1; 378 } 379 if (rev) { 380 memcpy(&tha.src, dst, sizeof ip->ip_dst); 381 memcpy(&tha.dst, src, sizeof ip->ip_src); 382 tha.port = dport << 16 | sport; 383 } else { 384 memcpy(&tha.dst, dst, sizeof ip->ip_dst); 385 memcpy(&tha.src, src, sizeof ip->ip_src); 386 tha.port = sport << 16 | dport; 387 } 388 #endif 389 390 threv = rev; 391 for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE]; 392 th->nxt; th = th->nxt) 393 if (memcmp((char *)&tha, (char *)&th->addr, 394 sizeof(th->addr)) == 0) 395 break; 396 397 if (!th->nxt || (flags & TH_SYN)) { 398 /* didn't find it or new conversation */ 399 if (th->nxt == NULL) { 400 th->nxt = (struct tcp_seq_hash *) 401 calloc(1, sizeof(*th)); 402 if (th->nxt == NULL) 403 error("tcp_print: calloc"); 404 } 405 th->addr = tha; 406 if (rev) 407 th->ack = seq, th->seq = ack - 1; 408 else 409 th->seq = seq, th->ack = ack - 1; 410 } else { 411 if (rev) 412 seq -= th->ack, ack -= th->seq; 413 else 414 seq -= th->seq, ack -= th->ack; 415 } 416 417 thseq = th->seq; 418 thack = th->ack; 419 } else { 420 /*fool gcc*/ 421 thseq = thack = threv = 0; 422 } 423 if (hlen > length) { 424 (void)printf(" [bad hdr length %u - too long, > %u]", 425 hlen, length); 426 return; 427 } 428 429 if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) { 430 u_int16_t sum, tcp_sum; 431 if (TTEST2(tp->th_sport, length)) { 432 sum = tcp_cksum(ip, tp, length); 433 434 (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum)); 435 if (sum != 0) { 436 tcp_sum = EXTRACT_16BITS(&tp->th_sum); 437 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum)); 438 } else 439 (void)printf(" (correct)"); 440 } 441 } 442 #ifdef INET6 443 if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) { 444 u_int16_t sum,tcp_sum; 445 if (TTEST2(tp->th_sport, length)) { 446 sum = tcp6_cksum(ip6, tp, length); 447 (void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum)); 448 if (sum != 0) { 449 tcp_sum = EXTRACT_16BITS(&tp->th_sum); 450 (void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum)); 451 } else 452 (void)printf(" (correct)"); 453 454 } 455 } 456 #endif 457 458 length -= hlen; 459 if (vflag > 1 || flags & (TH_SYN | TH_FIN | TH_RST)) { 460 (void)printf(", seq %u", seq); 461 462 if (length > 0) { 463 (void)printf(":%u", seq + length); 464 } 465 } 466 467 if (flags & TH_ACK) { 468 (void)printf(", ack %u", ack); 469 } 470 471 (void)printf(", win %d", win); 472 473 if (flags & TH_URG) 474 (void)printf(", urg %d", urp); 475 /* 476 * Handle any options. 477 */ 478 if (hlen > sizeof(*tp)) { 479 register const u_char *cp; 480 register u_int i, opt, datalen; 481 register u_int len; 482 483 hlen -= sizeof(*tp); 484 cp = (const u_char *)tp + sizeof(*tp); 485 printf(", options ["); 486 while (hlen > 0) { 487 if (ch != '\0') 488 putchar(ch); 489 TCHECK(*cp); 490 opt = *cp++; 491 if (ZEROLENOPT(opt)) 492 len = 1; 493 else { 494 TCHECK(*cp); 495 len = *cp++; /* total including type, len */ 496 if (len < 2 || len > hlen) 497 goto bad; 498 --hlen; /* account for length byte */ 499 } 500 --hlen; /* account for type byte */ 501 datalen = 0; 502 503 /* Bail if "l" bytes of data are not left or were not captured */ 504 #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); } 505 506 507 printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt)); 508 509 switch (opt) { 510 511 case TCPOPT_MAXSEG: 512 datalen = 2; 513 LENCHECK(datalen); 514 (void)printf(" %u", EXTRACT_16BITS(cp)); 515 break; 516 517 case TCPOPT_WSCALE: 518 datalen = 1; 519 LENCHECK(datalen); 520 (void)printf(" %u", *cp); 521 break; 522 523 case TCPOPT_SACK: 524 datalen = len - 2; 525 if (datalen % 8 != 0) { 526 (void)printf("malformed sack"); 527 } else { 528 u_int32_t s, e; 529 530 (void)printf(" %d ", datalen / 8); 531 for (i = 0; i < datalen; i += 8) { 532 LENCHECK(i + 4); 533 s = EXTRACT_32BITS(cp + i); 534 LENCHECK(i + 8); 535 e = EXTRACT_32BITS(cp + i + 4); 536 if (threv) { 537 s -= thseq; 538 e -= thseq; 539 } else { 540 s -= thack; 541 e -= thack; 542 } 543 (void)printf("{%u:%u}", s, e); 544 } 545 } 546 break; 547 548 case TCPOPT_CC: 549 case TCPOPT_CCNEW: 550 case TCPOPT_CCECHO: 551 case TCPOPT_ECHO: 552 case TCPOPT_ECHOREPLY: 553 554 /* 555 * those options share their semantics. 556 * fall through 557 */ 558 datalen = 4; 559 LENCHECK(datalen); 560 (void)printf(" %u", EXTRACT_32BITS(cp)); 561 break; 562 563 case TCPOPT_TIMESTAMP: 564 datalen = 8; 565 LENCHECK(datalen); 566 (void)printf(" val %u ecr %u", 567 EXTRACT_32BITS(cp), 568 EXTRACT_32BITS(cp + 4)); 569 break; 570 571 case TCPOPT_SIGNATURE: 572 datalen = TCP_SIGLEN; 573 LENCHECK(datalen); 574 #ifdef HAVE_LIBCRYPTO 575 switch (tcp_verify_signature(ip, tp, 576 bp + TH_OFF(tp) * 4, length, cp)) { 577 578 case SIGNATURE_VALID: 579 (void)printf("valid"); 580 break; 581 582 case SIGNATURE_INVALID: 583 (void)printf("invalid"); 584 break; 585 586 case CANT_CHECK_SIGNATURE: 587 (void)printf("can't check - "); 588 for (i = 0; i < TCP_SIGLEN; ++i) 589 (void)printf("%02x", cp[i]); 590 break; 591 } 592 #else 593 for (i = 0; i < TCP_SIGLEN; ++i) 594 (void)printf("%02x", cp[i]); 595 #endif 596 break; 597 598 case TCPOPT_AUTH: 599 (void)printf("keyid %d", *cp++); 600 datalen = len - 3; 601 for (i = 0; i < datalen; ++i) { 602 LENCHECK(i); 603 (void)printf("%02x", cp[i]); 604 } 605 break; 606 607 608 case TCPOPT_EOL: 609 case TCPOPT_NOP: 610 case TCPOPT_SACKOK: 611 /* 612 * Nothing interesting. 613 * fall through 614 */ 615 break; 616 617 case TCPOPT_UTO: 618 datalen = 2; 619 LENCHECK(datalen); 620 uint utoval = EXTRACT_16BITS(cp); 621 if (utoval & 0x0001) 622 utoval = (utoval >> 1) * 60; 623 else 624 utoval >>= 1; 625 (void)printf(" %u", utoval); 626 break; 627 628 default: 629 datalen = len - 2; 630 for (i = 0; i < datalen; ++i) { 631 LENCHECK(i); 632 (void)printf("%02x", cp[i]); 633 } 634 break; 635 } 636 637 /* Account for data printed */ 638 cp += datalen; 639 hlen -= datalen; 640 641 /* Check specification against observed length */ 642 ++datalen; /* option octet */ 643 if (!ZEROLENOPT(opt)) 644 ++datalen; /* size octet */ 645 if (datalen != len) 646 (void)printf("[len %d]", len); 647 ch = ','; 648 if (opt == TCPOPT_EOL) 649 break; 650 } 651 putchar(']'); 652 } 653 654 /* 655 * Print length field before crawling down the stack. 656 */ 657 printf(", length %u", length); 658 659 if (length <= 0) 660 return; 661 662 /* 663 * Decode payload if necessary. 664 */ 665 bp += TH_OFF(tp) * 4; 666 if ((flags & TH_RST) && vflag) { 667 print_tcp_rst_data(bp, length); 668 return; 669 } 670 671 if (sport == TELNET_PORT || dport == TELNET_PORT) { 672 if (!qflag && vflag) 673 telnet_print(bp, length); 674 } else if (sport == BGP_PORT || dport == BGP_PORT) 675 bgp_print(bp, length); 676 else if (sport == PPTP_PORT || dport == PPTP_PORT) 677 pptp_print(bp); 678 #ifdef TCPDUMP_DO_SMB 679 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT) 680 nbt_tcp_print(bp, length); 681 else if (sport == SMB_PORT || dport == SMB_PORT) 682 smb_tcp_print(bp, length); 683 #endif 684 else if (sport == BEEP_PORT || dport == BEEP_PORT) 685 beep_print(bp, length); 686 else if (length > 2 && 687 (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT || 688 sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) { 689 /* 690 * TCP DNS query has 2byte length at the head. 691 * XXX packet could be unaligned, it can go strange 692 */ 693 ns_print(bp + 2, length - 2, 0); 694 } else if (sport == MSDP_PORT || dport == MSDP_PORT) { 695 msdp_print(bp, length); 696 } 697 else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) { 698 ldp_print(bp, length); 699 } 700 701 return; 702 bad: 703 fputs("[bad opt]", stdout); 704 if (ch != '\0') 705 putchar('>'); 706 return; 707 trunc: 708 fputs("[|tcp]", stdout); 709 if (ch != '\0') 710 putchar('>'); 711 } 712 713 /* 714 * RFC1122 says the following on data in RST segments: 715 * 716 * 4.2.2.12 RST Segment: RFC-793 Section 3.4 717 * 718 * A TCP SHOULD allow a received RST segment to include data. 719 * 720 * DISCUSSION 721 * It has been suggested that a RST segment could contain 722 * ASCII text that encoded and explained the cause of the 723 * RST. No standard has yet been established for such 724 * data. 725 * 726 */ 727 728 static void 729 print_tcp_rst_data(register const u_char *sp, u_int length) 730 { 731 int c; 732 733 if (TTEST2(*sp, length)) 734 printf(" [RST"); 735 else 736 printf(" [!RST"); 737 if (length > MAX_RST_DATA_LEN) { 738 length = MAX_RST_DATA_LEN; /* can use -X for longer */ 739 putchar('+'); /* indicate we truncate */ 740 } 741 putchar(' '); 742 while (length-- && sp <= snapend) { 743 c = *sp++; 744 safeputchar(c); 745 } 746 putchar(']'); 747 } 748 749 #ifdef HAVE_LIBCRYPTO 750 static int 751 tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp, 752 const u_char *data, int length, const u_char *rcvsig) 753 { 754 struct tcphdr tp1; 755 u_char sig[TCP_SIGLEN]; 756 char zero_proto = 0; 757 MD5_CTX ctx; 758 u_int16_t savecsum, tlen; 759 #ifdef INET6 760 struct ip6_hdr *ip6; 761 u_int32_t len32; 762 u_int8_t nxt; 763 #endif 764 765 tp1 = *tp; 766 767 if (tcpmd5secret == NULL) 768 return (CANT_CHECK_SIGNATURE); 769 770 MD5_Init(&ctx); 771 /* 772 * Step 1: Update MD5 hash with IP pseudo-header. 773 */ 774 if (IP_V(ip) == 4) { 775 MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src)); 776 MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst)); 777 MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto)); 778 MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p)); 779 tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4; 780 tlen = htons(tlen); 781 MD5_Update(&ctx, (char *)&tlen, sizeof(tlen)); 782 #ifdef INET6 783 } else if (IP_V(ip) == 6) { 784 ip6 = (struct ip6_hdr *)ip; 785 MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src)); 786 MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst)); 787 len32 = htonl(ntohs(ip6->ip6_plen)); 788 MD5_Update(&ctx, (char *)&len32, sizeof(len32)); 789 nxt = 0; 790 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 791 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 792 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 793 nxt = IPPROTO_TCP; 794 MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); 795 #endif 796 } else 797 return (CANT_CHECK_SIGNATURE); 798 799 /* 800 * Step 2: Update MD5 hash with TCP header, excluding options. 801 * The TCP checksum must be set to zero. 802 */ 803 savecsum = tp1.th_sum; 804 tp1.th_sum = 0; 805 MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr)); 806 tp1.th_sum = savecsum; 807 /* 808 * Step 3: Update MD5 hash with TCP segment data, if present. 809 */ 810 if (length > 0) 811 MD5_Update(&ctx, data, length); 812 /* 813 * Step 4: Update MD5 hash with shared secret. 814 */ 815 MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret)); 816 MD5_Final(sig, &ctx); 817 818 if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0) 819 return (SIGNATURE_VALID); 820 else 821 return (SIGNATURE_INVALID); 822 } 823 #endif /* HAVE_LIBCRYPTO */ 824 825 /* 826 * Local Variables: 827 * c-style: whitesmith 828 * c-basic-offset: 8 829 * End: 830 */ 831