1 /* $OpenBSD: tcpdump.c,v 1.93 2020/06/21 05:00:18 dlg 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 * 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 /* 25 * tcpdump - monitor tcp/ip traffic on an ethernet. 26 * 27 * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory. 28 * Mercilessly hacked and occasionally improved since then via the 29 * combined efforts of Van, Steve McCanne and Craig Leres of LBL. 30 */ 31 32 #include <sys/types.h> 33 #include <sys/time.h> 34 #include <sys/ioctl.h> 35 #include <sys/wait.h> 36 37 #include <netinet/in.h> 38 39 #include <pcap.h> 40 #include <signal.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include <limits.h> 46 #include <ctype.h> 47 #include <err.h> 48 #include <errno.h> 49 50 #include "interface.h" 51 #include "addrtoname.h" 52 #include "setsignal.h" 53 #include "gmt2local.h" 54 55 #include <sys/socket.h> 56 #include <net/if.h> 57 #include <net/pfvar.h> 58 #include "pfctl.h" 59 #include "pfctl_parser.h" 60 #include "privsep.h" 61 62 int Aflag; /* dump ascii */ 63 int aflag; /* translate network and broadcast addresses */ 64 int Bflag; /* BPF fildrop setting */ 65 int dflag; /* print filter code */ 66 int eflag; /* print ethernet header */ 67 int fflag; /* don't translate "foreign" IP address */ 68 int Iflag; /* include interface in output */ 69 int Lflag; /* List available link types */ 70 int nflag; /* leave addresses as numbers */ 71 int Nflag; /* remove domains from printed host names */ 72 int Oflag = 1; /* run filter code optimizer */ 73 int oflag; /* print passive OS fingerprints */ 74 int pflag; /* don't go promiscuous */ 75 int qflag; /* quick (shorter) output */ 76 int Sflag; /* print raw TCP sequence numbers */ 77 int tflag = 1; /* print packet arrival time */ 78 int vflag; /* verbose */ 79 int xflag; /* print packet in hex */ 80 int Xflag; /* print packet in emacs-hexl style */ 81 82 int packettype; 83 84 char *program_name; 85 char *device = NULL; 86 87 int32_t thiszone; /* seconds offset from gmt to local time */ 88 89 extern volatile pid_t child_pid; 90 91 /* Externs */ 92 extern void bpf_dump(struct bpf_program *, int); 93 extern int esp_init(char *); 94 95 /* Forwards */ 96 void cleanup(int); 97 void gotchld(int); 98 extern __dead void usage(void); 99 100 /* Length of saved portion of packet. */ 101 int snaplen = 0; 102 103 struct printer { 104 pcap_handler f; 105 int type; 106 }; 107 108 /* XXX needed if using old bpf.h */ 109 #ifndef DLT_ATM_RFC1483 110 #define DLT_ATM_RFC1483 11 111 #endif 112 113 static struct printer printers[] = { 114 { ether_if_print, DLT_EN10MB }, 115 { ether_if_print, DLT_IEEE802 }, 116 { sl_if_print, DLT_SLIP }, 117 { sl_bsdos_if_print, DLT_SLIP_BSDOS }, 118 { ppp_if_print, DLT_PPP }, 119 { ppp_hdlc_if_print, DLT_PPP_SERIAL }, 120 { fddi_if_print, DLT_FDDI }, 121 { null_if_print, DLT_NULL }, 122 { raw_if_print, DLT_RAW }, 123 { atm_if_print, DLT_ATM_RFC1483 }, 124 { loop_if_print, DLT_LOOP }, 125 { enc_if_print, DLT_ENC }, 126 { pflog_if_print, DLT_PFLOG }, 127 { pfsync_if_print, DLT_PFSYNC }, 128 { ppp_ether_if_print, DLT_PPP_ETHER }, 129 { ieee802_11_if_print, DLT_IEEE802_11 }, 130 { ieee802_11_radio_if_print, DLT_IEEE802_11_RADIO }, 131 { ofp_if_print, DLT_OPENFLOW }, 132 { usbpcap_if_print, DLT_USBPCAP }, 133 { NULL, 0 }, 134 }; 135 136 static pcap_handler 137 lookup_printer(int type) 138 { 139 struct printer *p; 140 141 for (p = printers; p->f; ++p) { 142 if (type == p->type) 143 return p->f; 144 } 145 146 error("unknown data link type 0x%x", type); 147 /* NOTREACHED */ 148 } 149 150 static int 151 init_pfosfp(void) 152 { 153 pf_osfp_initialize(); 154 if (pfctl_file_fingerprints(-1, 155 PF_OPT_QUIET|PF_OPT_NOACTION, PF_OSFP_FILE) == 0) 156 return 1; 157 return 0; 158 } 159 160 static pcap_t *pd; 161 162 /* Multiple DLT support */ 163 void pcap_list_linktypes(pcap_t *); 164 void pcap_print_linktype(u_int); 165 166 void 167 pcap_print_linktype(u_int dlt) 168 { 169 const char *name; 170 171 if ((name = pcap_datalink_val_to_name(dlt)) != NULL) 172 fprintf(stderr, "%s\n", name); 173 else 174 fprintf(stderr, "<unknown: %u>\n", dlt); 175 } 176 177 void 178 pcap_list_linktypes(pcap_t *p) 179 { 180 int fd = p->fd; 181 u_int n; 182 183 #define MAXDLT 100 184 185 u_int dltlist[MAXDLT]; 186 struct bpf_dltlist dl = {MAXDLT, dltlist}; 187 188 if (fd < 0) 189 error("Invalid bpf descriptor"); 190 191 if (ioctl(fd, BIOCGDLTLIST, &dl) == -1) 192 err(1, "BIOCGDLTLIST"); 193 194 if (dl.bfl_len > MAXDLT) 195 error("Invalid number of linktypes: %u", dl.bfl_len); 196 197 fprintf(stderr, "%d link type%s supported:\n", dl.bfl_len, 198 dl.bfl_len == 1 ? "" : "s"); 199 200 for (n = 0; n < dl.bfl_len; n++) { 201 fprintf(stderr, "\t"); 202 pcap_print_linktype(dltlist[n]); 203 } 204 } 205 206 int 207 main(int argc, char **argv) 208 { 209 int cnt = -1, op, i; 210 bpf_u_int32 localnet, netmask; 211 char *cp, *infile = NULL, *RFileName = NULL; 212 char ebuf[PCAP_ERRBUF_SIZE], *WFileName = NULL; 213 pcap_handler printer; 214 struct bpf_program *fcode; 215 u_char *pcap_userdata; 216 u_int dirfilt = 0, dlt = (u_int) -1; 217 const char *errstr; 218 219 if ((cp = strrchr(argv[0], '/')) != NULL) 220 program_name = cp + 1; 221 else 222 program_name = argv[0]; 223 224 /* '-P' used internally, exec privileged portion */ 225 if (argc >= 2 && strcmp("-P", argv[1]) == 0) 226 priv_exec(argc, argv); 227 228 if (priv_init(argc, argv)) 229 error("Failed to setup privsep"); 230 231 /* state: STATE_INIT */ 232 233 opterr = 0; 234 while ((op = getopt(argc, argv, 235 "AaB:c:D:deE:fF:i:IlLnNOopqr:s:StT:vw:xXy:Y")) != -1) 236 switch (op) { 237 238 case 'A': 239 xflag = 1; 240 Aflag = 1; 241 break; 242 243 case 'a': 244 aflag = 1; 245 break; 246 247 case 'B': 248 if (strcasecmp(optarg, "pass") == 0) 249 Bflag = BPF_FILDROP_PASS; 250 else if (strcasecmp(optarg, "capture") == 0) 251 Bflag = BPF_FILDROP_CAPTURE; 252 else if (strcasecmp(optarg, "drop") == 0) 253 Bflag = BPF_FILDROP_DROP; 254 else { 255 error("invalid BPF fildrop option: %s", 256 optarg); 257 } 258 break; 259 260 case 'c': 261 cnt = strtonum(optarg, 1, INT_MAX, &errstr); 262 if (errstr) 263 error("invalid packet count %s: %s", 264 optarg, errstr); 265 break; 266 267 case 'D': 268 if (strcasecmp(optarg, "in") == 0) 269 dirfilt = BPF_DIRECTION_OUT; 270 else if (strcasecmp(optarg, "out") == 0) 271 dirfilt = BPF_DIRECTION_IN; 272 else 273 error("invalid traffic direction %s", optarg); 274 break; 275 276 case 'd': 277 ++dflag; 278 break; 279 case 'e': 280 eflag = 1; 281 break; 282 283 case 'f': 284 fflag = 1; 285 break; 286 287 case 'F': 288 infile = optarg; 289 break; 290 291 case 'i': 292 device = optarg; 293 break; 294 295 case 'I': 296 Iflag = 1; 297 break; 298 299 case 'l': 300 setvbuf(stdout, NULL, _IOLBF, 0); 301 break; 302 case 'L': 303 Lflag = 1; 304 break; 305 case 'n': 306 nflag = 1; 307 break; 308 309 case 'N': 310 Nflag = 1; 311 break; 312 313 case 'O': 314 Oflag = 0; 315 break; 316 317 case 'o': 318 oflag = 1; 319 break; 320 321 case 'p': 322 pflag = 1; 323 break; 324 325 case 'q': 326 qflag = 1; 327 break; 328 329 case 'r': 330 RFileName = optarg; 331 break; 332 333 case 's': 334 snaplen = strtonum(optarg, 1, INT_MAX, &errstr); 335 if (errstr) 336 error("invalid snaplen %s: %s", optarg, errstr); 337 break; 338 339 case 'S': 340 Sflag = 1; 341 break; 342 343 case 't': 344 --tflag; 345 break; 346 347 case 'T': 348 if (strcasecmp(optarg, "vat") == 0) 349 packettype = PT_VAT; 350 else if (strcasecmp(optarg, "wb") == 0) 351 packettype = PT_WB; 352 else if (strcasecmp(optarg, "rpc") == 0) 353 packettype = PT_RPC; 354 else if (strcasecmp(optarg, "rtp") == 0) 355 packettype = PT_RTP; 356 else if (strcasecmp(optarg, "rtcp") == 0) 357 packettype = PT_RTCP; 358 else if (strcasecmp(optarg, "cnfp") == 0) 359 packettype = PT_CNFP; 360 else if (strcasecmp(optarg, "vrrp") == 0) 361 packettype = PT_VRRP; 362 else if (strcasecmp(optarg, "tcp") == 0) 363 packettype = PT_TCP; 364 else if (strcasecmp(optarg, "gre") == 0) 365 packettype = PT_GRE; 366 else if (strcasecmp(optarg, "vxlan") == 0) 367 packettype = PT_VXLAN; 368 else if (strcasecmp(optarg, "erspan") == 0) 369 packettype = PT_ERSPAN; 370 else if (strcasecmp(optarg, "mpls") == 0) 371 packettype = PT_MPLS; 372 else if (strcasecmp(optarg, "tftp") == 0) 373 packettype = PT_TFTP; 374 else if (strcasecmp(optarg, "wg") == 0) 375 packettype = PT_WIREGUARD; 376 else if (strcasecmp(optarg, "sack") == 0) 377 /* 378 * kept for compatibility; DEFAULT_SNAPLEN 379 * used to be too short to capture SACK. 380 */ 381 ; 382 else 383 error("unknown packet type `%s'", optarg); 384 break; 385 386 case 'v': 387 ++vflag; 388 break; 389 390 case 'w': 391 WFileName = optarg; 392 break; 393 #ifdef YYDEBUG 394 case 'Y': 395 { 396 /* Undocumented flag */ 397 extern int yydebug; 398 yydebug = 1; 399 } 400 break; 401 #endif 402 case 'y': 403 i = pcap_datalink_name_to_val(optarg); 404 if (i < 0) 405 error("invalid data link type: %s", optarg); 406 dlt = (u_int)i; 407 break; 408 409 case 'x': 410 xflag = 1; 411 break; 412 413 case 'X': 414 Xflag = 1; 415 xflag = 1; 416 break; 417 418 case 'E': 419 if (esp_init(optarg) < 0) 420 error("bad esp specification `%s'", optarg); 421 break; 422 423 default: 424 usage(); 425 /* NOTREACHED */ 426 } 427 428 if (snaplen == 0) { 429 switch (dlt) { 430 case DLT_IEEE802_11: 431 snaplen = IEEE802_11_SNAPLEN; 432 break; 433 case DLT_IEEE802_11_RADIO: 434 snaplen = IEEE802_11_RADIO_SNAPLEN; 435 break; 436 default: 437 snaplen = DEFAULT_SNAPLEN; 438 break; 439 } 440 } 441 442 if (aflag && nflag) 443 error("-a and -n options are incompatible"); 444 445 if (RFileName != NULL) { 446 pd = priv_pcap_offline(RFileName, ebuf); 447 if (pd == NULL) 448 error("%s", ebuf); 449 /* state: STATE_BPF */ 450 localnet = 0; 451 netmask = 0; 452 if (fflag != 0) 453 error("-f and -r options are incompatible"); 454 } else { 455 if (device == NULL) { 456 device = pcap_lookupdev(ebuf); 457 if (device == NULL) 458 error("%s", ebuf); 459 } 460 pd = priv_pcap_live(device, snaplen, !pflag, 1000, ebuf, 461 dlt, dirfilt, Bflag); 462 if (pd == NULL) 463 error("%s", ebuf); 464 465 /* state: STATE_BPF */ 466 if (pcap_lookupnet(device, &localnet, &netmask, ebuf)) { 467 if (fflag) 468 warning("%s", ebuf); 469 localnet = 0; 470 netmask = 0; 471 } 472 } 473 i = pcap_snapshot(pd); 474 if (snaplen < i) { 475 warning("snaplen raised from %d to %d", snaplen, i); 476 snaplen = i; 477 } 478 479 if (Lflag) { 480 pcap_list_linktypes(pd); 481 exit(0); 482 } 483 484 fcode = priv_pcap_setfilter(pd, Oflag, netmask); 485 /* state: STATE_FILTER */ 486 if (fcode == NULL) 487 error("%s", pcap_geterr(pd)); 488 if (dflag) { 489 bpf_dump(fcode, dflag); 490 exit(0); 491 } 492 if (oflag) 493 oflag = init_pfosfp(); 494 init_addrtoname(localnet, netmask); 495 496 if (WFileName) { 497 pcap_dumper_t *p; 498 499 p = priv_pcap_dump_open(pd, WFileName); 500 /* state: STATE_RUN */ 501 if (p == NULL) 502 error("%s", pcap_geterr(pd)); 503 { 504 FILE *fp = (FILE *)p; /* XXX touching pcap guts! */ 505 fflush(fp); 506 setvbuf(fp, NULL, _IONBF, 0); 507 } 508 printer = pcap_dump; 509 pcap_userdata = (u_char *)p; 510 } else { 511 printer = lookup_printer(pcap_datalink(pd)); 512 pcap_userdata = NULL; 513 priv_init_done(); 514 /* state: STATE_RUN */ 515 } 516 if (RFileName == NULL) { 517 (void)fprintf(stderr, "%s: listening on %s, link-type ", 518 program_name, device); 519 pcap_print_linktype(pd->linktype); 520 (void)fflush(stderr); 521 } 522 523 if (tflag > 0) 524 thiszone = gmt2local(0); 525 526 if (pledge("stdio", NULL) == -1) 527 err(1, "pledge"); 528 529 if (pcap_loop(pd, cnt, printer, pcap_userdata) < 0) { 530 (void)fprintf(stderr, "%s: pcap_loop: %s\n", 531 program_name, pcap_geterr(pd)); 532 exit(1); 533 } 534 pcap_close(pd); 535 exit(0); 536 } 537 538 /* make a clean exit on interrupts */ 539 void 540 cleanup(int signo) 541 { 542 struct pcap_stat stat; 543 sigset_t allsigs; 544 545 sigfillset(&allsigs); 546 sigprocmask(SIG_BLOCK, &allsigs, NULL); 547 548 /* Can't print the summary if reading from a savefile */ 549 dprintf(STDERR_FILENO, "\n"); 550 if (pd != NULL && pcap_file(pd) == NULL) { 551 if (priv_pcap_stats(&stat) < 0) { 552 dprintf(STDERR_FILENO, 553 "pcap_stats: %s\n", pcap_geterr(pd)); 554 } else { 555 dprintf(STDERR_FILENO, 556 "%u packets received by filter\n", stat.ps_recv); 557 dprintf(STDERR_FILENO, 558 "%u packets dropped by kernel\n", stat.ps_drop); 559 } 560 } 561 _exit(0); 562 } 563 564 void 565 gotchld(int signo) 566 { 567 pid_t pid; 568 int status; 569 int save_err = errno; 570 571 do { 572 pid = waitpid(child_pid, &status, WNOHANG); 573 if (pid > 0 && (WIFEXITED(status) || WIFSIGNALED(status))) 574 cleanup(0); 575 } while (pid == -1 && errno == EINTR); 576 577 if (pid == -1) 578 _exit(1); 579 580 errno = save_err; 581 } 582 583 /* dump the buffer in `emacs-hexl' style */ 584 void 585 default_print_hexl(const u_char *cp, unsigned int length) 586 { 587 unsigned int i, j, jm; 588 int c; 589 char ln[128], buf[128]; 590 591 printf("\n"); 592 for (i = 0; i < length; i += 0x10) { 593 snprintf(ln, sizeof(ln), " %04x: ", (unsigned int)i); 594 jm = length - i; 595 jm = jm > 16 ? 16 : jm; 596 597 for (j = 0; j < jm; j++) { 598 if ((j % 2) == 1) 599 snprintf(buf, sizeof(buf), "%02x ", 600 (unsigned int)cp[i+j]); 601 else 602 snprintf(buf, sizeof(buf), "%02x", 603 (unsigned int)cp[i+j]); 604 strlcat(ln, buf, sizeof ln); 605 } 606 for (; j < 16; j++) { 607 if ((j % 2) == 1) 608 snprintf(buf, sizeof buf, " "); 609 else 610 snprintf(buf, sizeof buf, " "); 611 strlcat(ln, buf, sizeof ln); 612 } 613 614 strlcat(ln, " ", sizeof ln); 615 for (j = 0; j < jm; j++) { 616 c = cp[i+j]; 617 c = isprint(c) ? c : '.'; 618 buf[0] = c; 619 buf[1] = '\0'; 620 strlcat(ln, buf, sizeof ln); 621 } 622 printf("%s\n", ln); 623 } 624 } 625 626 /* dump the text from the buffer */ 627 void 628 default_print_ascii(const u_char *cp, unsigned int length) 629 { 630 int c, i; 631 632 printf("\n"); 633 for (i = 0; i < length; i++) { 634 c = cp[i]; 635 if (isprint(c) || c == '\t' || c == '\n' || c == '\r') 636 putchar(c); 637 else 638 putchar('.'); 639 } 640 } 641 642 /* Like default_print() but data need not be aligned */ 643 void 644 default_print_unaligned(const u_char *cp, u_int length) 645 { 646 u_int i, s; 647 int nshorts; 648 649 if (Xflag) { 650 /* dump the buffer in `emacs-hexl' style */ 651 default_print_hexl(cp, length); 652 } else if (Aflag) { 653 /* dump the text in the buffer */ 654 default_print_ascii(cp, length); 655 } else { 656 /* dump the buffer in old tcpdump style */ 657 nshorts = (u_int) length / sizeof(u_short); 658 i = 0; 659 while (--nshorts >= 0) { 660 if ((i++ % 8) == 0) 661 printf("\n\t\t\t"); 662 s = *cp++; 663 printf(" %02x%02x", s, *cp++); 664 } 665 if (length & 1) { 666 if ((i % 8) == 0) 667 printf("\n\t\t\t"); 668 printf(" %02x", *cp); 669 } 670 } 671 } 672 673 void 674 default_print(const u_char *bp, u_int length) 675 { 676 const u_short *sp; 677 u_int i; 678 int nshorts; 679 680 if (Xflag) { 681 /* dump the buffer in `emacs-hexl' style */ 682 default_print_hexl(bp, length); 683 } else if (Aflag) { 684 /* dump the text in the buffer */ 685 default_print_ascii(bp, length); 686 } else { 687 /* dump the buffer in old tcpdump style */ 688 if ((long)bp & 1) { 689 default_print_unaligned(bp, length); 690 return; 691 } 692 sp = (u_short *)bp; 693 nshorts = (u_int) length / sizeof(u_short); 694 i = 0; 695 while (--nshorts >= 0) { 696 if ((i++ % 8) == 0) 697 printf("\n\t\t\t"); 698 printf(" %04x", ntohs(*sp++)); 699 } 700 if (length & 1) { 701 if ((i % 8) == 0) 702 printf("\n\t\t\t"); 703 printf(" %02x", *(u_char *)sp); 704 } 705 } 706 } 707 708 void 709 set_slave_signals(void) 710 { 711 setsignal(SIGTERM, cleanup); 712 setsignal(SIGINT, cleanup); 713 setsignal(SIGCHLD, gotchld); 714 setsignal(SIGHUP, cleanup); 715 } 716 717 __dead void 718 usage(void) 719 { 720 (void)fprintf(stderr, 721 "Usage: %s [-AadefILlNnOopqStvXx] [-B fildrop] [-c count] [-D direction]\n", 722 program_name); 723 (void)fprintf(stderr, 724 "\t [-E [espalg:]espkey] [-F file] [-i interface] [-r file]\n"); 725 (void)fprintf(stderr, 726 "\t [-s snaplen] [-T type] [-w file] [-y datalinktype] [expression]\n"); 727 exit(1); 728 } 729