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 25 static 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 62 static 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 66 static void print_tcp_rst_data(register const u_char *sp, u_int length); 67 68 #define MAX_RST_DATA_LEN 30 69 70 71 struct 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 82 struct 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 94 static 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 646 113 114 static 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 146 static 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 189 190 void 191 tcp_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; 686 bad: 687 fputs("[bad opt]", stdout); 688 if (ch != '\0') 689 putchar('>'); 690 return; 691 trunc: 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 */ 711 712 static void 713 print_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 734 static int 735 tcp_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 */ 808
