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 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that: (1) source code distributions 7 * retain the above copyright notice and this paragraph in its entirety, (2) 8 * distributions including binary code include the above copyright notice and 9 * this paragraph in its entirety in the documentation or other materials 10 * provided with the distribution, and (3) all advertising materials mentioning 11 * features or use of this software display the following acknowledgement: 12 * ``This product includes software developed by the University of California, 13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 14 * the University nor the names of its contributors may be used to endorse 15 * or promote products derived from this software without specific prior 16 * written permission. 17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 20 */ 21 22 #ifndef lint 23 static const char rcsid[] _U_ = 24 "@(#) $Header: /tcpdump/master/tcpdump/print-ip.c,v 1.159 2007-09-14 01:29:28 guy Exp $ (LBL)"; 25 #endif 26 27 #ifdef HAVE_CONFIG_H 28 #include "config.h" 29 #endif 30 31 #include <tcpdump-stdinc.h> 32 33 #include <stdio.h> 34 #include <stdlib.h> 35 #include <string.h> 36 37 #include "addrtoname.h" 38 #include "interface.h" 39 #include "extract.h" /* must come after interface.h */ 40 41 #include "ip.h" 42 #include "ipproto.h" 43 44 struct tok ip_option_values[] = { 45 { IPOPT_EOL, "EOL" }, 46 { IPOPT_NOP, "NOP" }, 47 { IPOPT_TS, "timestamp" }, 48 { IPOPT_SECURITY, "security" }, 49 { IPOPT_RR, "RR" }, 50 { IPOPT_SSRR, "SSRR" }, 51 { IPOPT_LSRR, "LSRR" }, 52 { IPOPT_RA, "RA" }, 53 { IPOPT_RFC1393, "traceroute" }, 54 { 0, NULL } 55 }; 56 57 /* 58 * print the recorded route in an IP RR, LSRR or SSRR option. 59 */ 60 static void 61 ip_printroute(register const u_char *cp, u_int length) 62 { 63 register u_int ptr; 64 register u_int len; 65 66 if (length < 3) { 67 printf(" [bad length %u]", length); 68 return; 69 } 70 if ((length + 1) & 3) 71 printf(" [bad length %u]", length); 72 ptr = cp[2] - 1; 73 if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1) 74 printf(" [bad ptr %u]", cp[2]); 75 76 for (len = 3; len < length; len += 4) { 77 printf(" %s", ipaddr_string(&cp[len])); 78 if (ptr > len) 79 printf(","); 80 } 81 } 82 83 /* 84 * If source-routing is present and valid, return the final destination. 85 * Otherwise, return IP destination. 86 * 87 * This is used for UDP and TCP pseudo-header in the checksum 88 * calculation. 89 */ 90 u_int32_t 91 ip_finddst(const struct ip *ip) 92 { 93 int length; 94 int len; 95 const u_char *cp; 96 u_int32_t retval; 97 98 cp = (const u_char *)(ip + 1); 99 length = (IP_HL(ip) << 2) - sizeof(struct ip); 100 101 for (; length > 0; cp += len, length -= len) { 102 int tt; 103 104 TCHECK(*cp); 105 tt = *cp; 106 if (tt == IPOPT_EOL) 107 break; 108 else if (tt == IPOPT_NOP) 109 len = 1; 110 else { 111 TCHECK(cp[1]); 112 len = cp[1]; 113 if (len < 2) 114 break; 115 } 116 TCHECK2(*cp, len); 117 switch (tt) { 118 119 case IPOPT_SSRR: 120 case IPOPT_LSRR: 121 if (len < 7) 122 break; 123 memcpy(&retval, cp + len - 4, 4); 124 return retval; 125 } 126 } 127 trunc: 128 memcpy(&retval, &ip->ip_dst.s_addr, sizeof(u_int32_t)); 129 return retval; 130 } 131 132 static void 133 ip_printts(register const u_char *cp, u_int length) 134 { 135 register u_int ptr; 136 register u_int len; 137 int hoplen; 138 const char *type; 139 140 if (length < 4) { 141 printf("[bad length %u]", length); 142 return; 143 } 144 printf(" TS{"); 145 hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4; 146 if ((length - 4) & (hoplen-1)) 147 printf("[bad length %u]", length); 148 ptr = cp[2] - 1; 149 len = 0; 150 if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1) 151 printf("[bad ptr %u]", cp[2]); 152 switch (cp[3]&0xF) { 153 case IPOPT_TS_TSONLY: 154 printf("TSONLY"); 155 break; 156 case IPOPT_TS_TSANDADDR: 157 printf("TS+ADDR"); 158 break; 159 /* 160 * prespecified should really be 3, but some ones might send 2 161 * instead, and the IPOPT_TS_PRESPEC constant can apparently 162 * have both values, so we have to hard-code it here. 163 */ 164 165 case 2: 166 printf("PRESPEC2.0"); 167 break; 168 case 3: /* IPOPT_TS_PRESPEC */ 169 printf("PRESPEC"); 170 break; 171 default: 172 printf("[bad ts type %d]", cp[3]&0xF); 173 goto done; 174 } 175 176 type = " "; 177 for (len = 4; len < length; len += hoplen) { 178 if (ptr == len) 179 type = " ^ "; 180 printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]), 181 hoplen!=8 ? "" : ipaddr_string(&cp[len])); 182 type = " "; 183 } 184 185 done: 186 printf("%s", ptr == len ? " ^ " : ""); 187 188 if (cp[3]>>4) 189 printf(" [%d hops not recorded]} ", cp[3]>>4); 190 else 191 printf("}"); 192 } 193 194 /* 195 * print IP options. 196 */ 197 static void 198 ip_optprint(register const u_char *cp, u_int length) 199 { 200 register u_int option_len; 201 const char *sep = ""; 202 203 for (; length > 0; cp += option_len, length -= option_len) { 204 u_int option_code; 205 206 printf("%s", sep); 207 sep = ","; 208 209 TCHECK(*cp); 210 option_code = *cp; 211 212 printf("%s", 213 tok2str(ip_option_values,"unknown %u",option_code)); 214 215 if (option_code == IPOPT_NOP || 216 option_code == IPOPT_EOL) 217 option_len = 1; 218 219 else { 220 TCHECK(cp[1]); 221 option_len = cp[1]; 222 if (option_len < 2) { 223 printf(" [bad length %u]", option_len); 224 return; 225 } 226 } 227 228 if (option_len > length) { 229 printf(" [bad length %u]", option_len); 230 return; 231 } 232 233 TCHECK2(*cp, option_len); 234 235 switch (option_code) { 236 case IPOPT_EOL: 237 return; 238 239 case IPOPT_TS: 240 ip_printts(cp, option_len); 241 break; 242 243 case IPOPT_RR: /* fall through */ 244 case IPOPT_SSRR: 245 case IPOPT_LSRR: 246 ip_printroute(cp, option_len); 247 break; 248 249 case IPOPT_RA: 250 if (option_len < 4) { 251 printf(" [bad length %u]", option_len); 252 break; 253 } 254 TCHECK(cp[3]); 255 if (EXTRACT_16BITS(&cp[2]) != 0) 256 printf(" value %u", EXTRACT_16BITS(&cp[2])); 257 break; 258 259 case IPOPT_NOP: /* nothing to print - fall through */ 260 case IPOPT_SECURITY: 261 default: 262 break; 263 } 264 } 265 return; 266 267 trunc: 268 printf("[|ip]"); 269 } 270 271 /* 272 * compute an IP header checksum. 273 * don't modifiy the packet. 274 */ 275 u_short 276 in_cksum(const u_short *addr, register u_int len, int csum) 277 { 278 int nleft = len; 279 const u_short *w = addr; 280 u_short answer; 281 int sum = csum; 282 283 /* 284 * Our algorithm is simple, using a 32 bit accumulator (sum), 285 * we add sequential 16 bit words to it, and at the end, fold 286 * back all the carry bits from the top 16 bits into the lower 287 * 16 bits. 288 */ 289 while (nleft > 1) { 290 sum += *w++; 291 nleft -= 2; 292 } 293 if (nleft == 1) 294 sum += htons(*(u_char *)w<<8); 295 296 /* 297 * add back carry outs from top 16 bits to low 16 bits 298 */ 299 sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ 300 sum += (sum >> 16); /* add carry */ 301 answer = ~sum; /* truncate to 16 bits */ 302 return (answer); 303 } 304 305 /* 306 * Given the host-byte-order value of the checksum field in a packet 307 * header, and the network-byte-order computed checksum of the data 308 * that the checksum covers (including the checksum itself), compute 309 * what the checksum field *should* have been. 310 */ 311 u_int16_t 312 in_cksum_shouldbe(u_int16_t sum, u_int16_t computed_sum) 313 { 314 u_int32_t shouldbe; 315 316 /* 317 * The value that should have gone into the checksum field 318 * is the negative of the value gotten by summing up everything 319 * *but* the checksum field. 320 * 321 * We can compute that by subtracting the value of the checksum 322 * field from the sum of all the data in the packet, and then 323 * computing the negative of that value. 324 * 325 * "sum" is the value of the checksum field, and "computed_sum" 326 * is the negative of the sum of all the data in the packets, 327 * so that's -(-computed_sum - sum), or (sum + computed_sum). 328 * 329 * All the arithmetic in question is one's complement, so the 330 * addition must include an end-around carry; we do this by 331 * doing the arithmetic in 32 bits (with no sign-extension), 332 * and then adding the upper 16 bits of the sum, which contain 333 * the carry, to the lower 16 bits of the sum, and then do it 334 * again in case *that* sum produced a carry. 335 * 336 * As RFC 1071 notes, the checksum can be computed without 337 * byte-swapping the 16-bit words; summing 16-bit words 338 * on a big-endian machine gives a big-endian checksum, which 339 * can be directly stuffed into the big-endian checksum fields 340 * in protocol headers, and summing words on a little-endian 341 * machine gives a little-endian checksum, which must be 342 * byte-swapped before being stuffed into a big-endian checksum 343 * field. 344 * 345 * "computed_sum" is a network-byte-order value, so we must put 346 * it in host byte order before subtracting it from the 347 * host-byte-order value from the header; the adjusted checksum 348 * will be in host byte order, which is what we'll return. 349 */ 350 shouldbe = sum; 351 shouldbe += ntohs(computed_sum); 352 shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); 353 shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); 354 return shouldbe; 355 } 356 357 #define IP_RES 0x8000 358 359 static struct tok ip_frag_values[] = { 360 { IP_MF, "+" }, 361 { IP_DF, "DF" }, 362 { IP_RES, "rsvd" }, /* The RFC3514 evil ;-) bit */ 363 { 0, NULL } 364 }; 365 366 struct ip_print_demux_state { 367 const struct ip *ip; 368 const u_char *cp; 369 u_int len, off; 370 u_char nh; 371 int advance; 372 }; 373 374 static void 375 ip_print_demux(netdissect_options *ndo, 376 struct ip_print_demux_state *ipds) 377 { 378 struct protoent *proto; 379 380 again: 381 switch (ipds->nh) { 382 383 case IPPROTO_AH: 384 ipds->nh = *ipds->cp; 385 ipds->advance = ah_print(ipds->cp); 386 if (ipds->advance <= 0) 387 break; 388 ipds->cp += ipds->advance; 389 ipds->len -= ipds->advance; 390 goto again; 391 392 case IPPROTO_ESP: 393 { 394 int enh, padlen; 395 ipds->advance = esp_print(ndo, ipds->cp, ipds->len, 396 (const u_char *)ipds->ip, 397 &enh, &padlen); 398 if (ipds->advance <= 0) 399 break; 400 ipds->cp += ipds->advance; 401 ipds->len -= ipds->advance + padlen; 402 ipds->nh = enh & 0xff; 403 goto again; 404 } 405 406 case IPPROTO_IPCOMP: 407 { 408 int enh; 409 ipds->advance = ipcomp_print(ipds->cp, &enh); 410 if (ipds->advance <= 0) 411 break; 412 ipds->cp += ipds->advance; 413 ipds->len -= ipds->advance; 414 ipds->nh = enh & 0xff; 415 goto again; 416 } 417 418 case IPPROTO_SCTP: 419 sctp_print(ipds->cp, (const u_char *)ipds->ip, ipds->len); 420 break; 421 422 case IPPROTO_DCCP: 423 dccp_print(ipds->cp, (const u_char *)ipds->ip, ipds->len); 424 break; 425 426 case IPPROTO_TCP: 427 /* pass on the MF bit plus the offset to detect fragments */ 428 tcp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip, 429 ipds->off & (IP_MF|IP_OFFMASK)); 430 break; 431 432 case IPPROTO_UDP: 433 /* pass on the MF bit plus the offset to detect fragments */ 434 udp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip, 435 ipds->off & (IP_MF|IP_OFFMASK)); 436 break; 437 438 case IPPROTO_ICMP: 439 /* pass on the MF bit plus the offset to detect fragments */ 440 icmp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip, 441 ipds->off & (IP_MF|IP_OFFMASK)); 442 break; 443 444 case IPPROTO_PIGP: 445 /* 446 * XXX - the current IANA protocol number assignments 447 * page lists 9 as "any private interior gateway 448 * (used by Cisco for their IGRP)" and 88 as 449 * "EIGRP" from Cisco. 450 * 451 * Recent BSD <netinet/in.h> headers define 452 * IP_PROTO_PIGP as 9 and IP_PROTO_IGRP as 88. 453 * We define IP_PROTO_PIGP as 9 and 454 * IP_PROTO_EIGRP as 88; those names better 455 * match was the current protocol number 456 * assignments say. 457 */ 458 igrp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip); 459 break; 460 461 case IPPROTO_EIGRP: 462 eigrp_print(ipds->cp, ipds->len); 463 break; 464 465 case IPPROTO_ND: 466 ND_PRINT((ndo, " nd %d", ipds->len)); 467 break; 468 469 case IPPROTO_EGP: 470 egp_print(ipds->cp, ipds->len); 471 break; 472 473 case IPPROTO_OSPF: 474 ospf_print(ipds->cp, ipds->len, (const u_char *)ipds->ip); 475 break; 476 477 case IPPROTO_IGMP: 478 igmp_print(ipds->cp, ipds->len); 479 break; 480 481 case IPPROTO_IPV4: 482 /* DVMRP multicast tunnel (ip-in-ip encapsulation) */ 483 ip_print(gndo, ipds->cp, ipds->len); 484 if (! vflag) { 485 ND_PRINT((ndo, " (ipip-proto-4)")); 486 return; 487 } 488 break; 489 490 #ifdef INET6 491 case IPPROTO_IPV6: 492 /* ip6-in-ip encapsulation */ 493 ip6_print(ipds->cp, ipds->len); 494 break; 495 #endif /*INET6*/ 496 497 case IPPROTO_RSVP: 498 rsvp_print(ipds->cp, ipds->len); 499 break; 500 501 case IPPROTO_GRE: 502 /* do it */ 503 gre_print(ipds->cp, ipds->len); 504 break; 505 506 case IPPROTO_MOBILE: 507 mobile_print(ipds->cp, ipds->len); 508 break; 509 510 case IPPROTO_PIM: 511 pim_print(ipds->cp, ipds->len); 512 break; 513 514 case IPPROTO_VRRP: 515 vrrp_print(ipds->cp, ipds->len, ipds->ip->ip_ttl); 516 break; 517 518 case IPPROTO_PGM: 519 pgm_print(ipds->cp, ipds->len, (const u_char *)ipds->ip); 520 break; 521 522 default: 523 if ((proto = getprotobynumber(ipds->nh)) != NULL) 524 ND_PRINT((ndo, " %s", proto->p_name)); 525 else 526 ND_PRINT((ndo, " ip-proto-%d", ipds->nh)); 527 ND_PRINT((ndo, " %d", ipds->len)); 528 break; 529 } 530 } 531 532 void 533 ip_print_inner(netdissect_options *ndo, 534 const u_char *bp, 535 u_int length, u_int nh, 536 const u_char *bp2) 537 { 538 struct ip_print_demux_state ipd; 539 540 ipd.ip = (const struct ip *)bp2; 541 ipd.cp = bp; 542 ipd.len = length; 543 ipd.off = 0; 544 ipd.nh = nh; 545 ipd.advance = 0; 546 547 ip_print_demux(ndo, &ipd); 548 } 549 550 551 /* 552 * print an IP datagram. 553 */ 554 void 555 ip_print(netdissect_options *ndo, 556 const u_char *bp, 557 u_int length) 558 { 559 struct ip_print_demux_state ipd; 560 struct ip_print_demux_state *ipds=&ipd; 561 const u_char *ipend; 562 u_int hlen; 563 u_int16_t sum, ip_sum; 564 struct protoent *proto; 565 566 ipds->ip = (const struct ip *)bp; 567 if (IP_V(ipds->ip) != 4) { /* print version if != 4 */ 568 printf("IP%u ", IP_V(ipds->ip)); 569 if (IP_V(ipds->ip) == 6) 570 printf(", wrong link-layer encapsulation"); 571 } 572 else if (!eflag) 573 printf("IP "); 574 575 if ((u_char *)(ipds->ip + 1) > snapend) { 576 printf("[|ip]"); 577 return; 578 } 579 if (length < sizeof (struct ip)) { 580 (void)printf("truncated-ip %u", length); 581 return; 582 } 583 hlen = IP_HL(ipds->ip) * 4; 584 if (hlen < sizeof (struct ip)) { 585 (void)printf("bad-hlen %u", hlen); 586 return; 587 } 588 589 ipds->len = EXTRACT_16BITS(&ipds->ip->ip_len); 590 if (length < ipds->len) 591 (void)printf("truncated-ip - %u bytes missing! ", 592 ipds->len - length); 593 if (ipds->len < hlen) { 594 #ifdef GUESS_TSO 595 if (ipds->len) { 596 (void)printf("bad-len %u", ipds->len); 597 return; 598 } 599 else { 600 /* we guess that it is a TSO send */ 601 ipds->len = length; 602 } 603 #else 604 (void)printf("bad-len %u", ipds->len); 605 return; 606 #endif /* GUESS_TSO */ 607 } 608 609 /* 610 * Cut off the snapshot length to the end of the IP payload. 611 */ 612 ipend = bp + ipds->len; 613 if (ipend < snapend) 614 snapend = ipend; 615 616 ipds->len -= hlen; 617 618 ipds->off = EXTRACT_16BITS(&ipds->ip->ip_off); 619 620 if (vflag) { 621 (void)printf("(tos 0x%x", (int)ipds->ip->ip_tos); 622 /* ECN bits */ 623 if (ipds->ip->ip_tos & 0x03) { 624 switch (ipds->ip->ip_tos & 0x03) { 625 case 1: 626 (void)printf(",ECT(1)"); 627 break; 628 case 2: 629 (void)printf(",ECT(0)"); 630 break; 631 case 3: 632 (void)printf(",CE"); 633 } 634 } 635 636 if (ipds->ip->ip_ttl >= 1) 637 (void)printf(", ttl %u", ipds->ip->ip_ttl); 638 639 /* 640 * for the firewall guys, print id, offset. 641 * On all but the last stick a "+" in the flags portion. 642 * For unfragmented datagrams, note the don't fragment flag. 643 */ 644 645 (void)printf(", id %u, offset %u, flags [%s], proto %s (%u)", 646 EXTRACT_16BITS(&ipds->ip->ip_id), 647 (ipds->off & 0x1fff) * 8, 648 bittok2str(ip_frag_values, "none", ipds->off&0xe000), 649 tok2str(ipproto_values,"unknown",ipds->ip->ip_p), 650 ipds->ip->ip_p); 651 652 (void)printf(", length %u", EXTRACT_16BITS(&ipds->ip->ip_len)); 653 654 if ((hlen - sizeof(struct ip)) > 0) { 655 printf(", options ("); 656 ip_optprint((u_char *)(ipds->ip + 1), hlen - sizeof(struct ip)); 657 printf(")"); 658 } 659 660 if ((u_char *)ipds->ip + hlen <= snapend) { 661 sum = in_cksum((const u_short *)ipds->ip, hlen, 0); 662 if (sum != 0) { 663 ip_sum = EXTRACT_16BITS(&ipds->ip->ip_sum); 664 (void)printf(", bad cksum %x (->%x)!", ip_sum, 665 in_cksum_shouldbe(ip_sum, sum)); 666 } 667 } 668 669 printf(")\n "); 670 } 671 672 /* 673 * If this is fragment zero, hand it to the next higher 674 * level protocol. 675 */ 676 if ((ipds->off & 0x1fff) == 0) { 677 ipds->cp = (const u_char *)ipds->ip + hlen; 678 ipds->nh = ipds->ip->ip_p; 679 680 if (ipds->nh != IPPROTO_TCP && ipds->nh != IPPROTO_UDP && 681 ipds->nh != IPPROTO_SCTP && ipds->nh != IPPROTO_DCCP) { 682 (void)printf("%s > %s: ", 683 ipaddr_string(&ipds->ip->ip_src), 684 ipaddr_string(&ipds->ip->ip_dst)); 685 } 686 ip_print_demux(ndo, ipds); 687 } else { 688 /* Ultra quiet now means that all this stuff should be suppressed */ 689 if (qflag > 1) return; 690 691 /* 692 * if this isn't the first frag, we're missing the 693 * next level protocol header. print the ip addr 694 * and the protocol. 695 */ 696 if (ipds->off & 0x1fff) { 697 (void)printf("%s > %s:", ipaddr_string(&ipds->ip->ip_src), 698 ipaddr_string(&ipds->ip->ip_dst)); 699 if ((proto = getprotobynumber(ipds->ip->ip_p)) != NULL) 700 (void)printf(" %s", proto->p_name); 701 else 702 (void)printf(" ip-proto-%d", ipds->ip->ip_p); 703 } 704 } 705 } 706 707 void 708 ipN_print(register const u_char *bp, register u_int length) 709 { 710 struct ip *ip, hdr; 711 712 ip = (struct ip *)bp; 713 if (length < 4) { 714 (void)printf("truncated-ip %d", length); 715 return; 716 } 717 memcpy (&hdr, (char *)ip, 4); 718 switch (IP_V(&hdr)) { 719 case 4: 720 ip_print (gndo, bp, length); 721 return; 722 #ifdef INET6 723 case 6: 724 ip6_print (bp, length); 725 return; 726 #endif 727 default: 728 (void)printf("unknown ip %d", IP_V(&hdr)); 729 return; 730 } 731 } 732 733 /* 734 * Local Variables: 735 * c-style: whitesmith 736 * c-basic-offset: 8 737 * End: 738 */ 739 740 741