2 * Copyright (c) 1993, 1994, 1995, 1996, 1997
3 * The Regents of the University of California. All rights reserved.
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
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.
21 * sf-pcap.c - libpcap-file-format-specific code from savefile.c
22 * Extraction/creation by Jeffrey Mogul, DECWRL
23 * Modified by Steve McCanne, LBL.
25 * Used to save the received packet headers, after filtering, to
26 * a file, and then read them later.
27 * The first record in the file contains saved values for the machine
28 * dependent values so we can print the dump file on any architecture.
32 static const char rcsid[] _U_ =
33 "@(#) $Header$ (LBL)";
41 #include <pcap-stdinc.h>
48 #ifdef HAVE_SYS_BITYPES_H
49 #include <sys/bitypes.h>
51 #include <sys/types.h>
62 #include "pcap-common.h"
64 #ifdef HAVE_OS_PROTO_H
71 * Setting O_BINARY on DOS/Windows is a bit tricky
74 #define SET_BINMODE(f) _setmode(_fileno(f), _O_BINARY)
76 #if defined(__HIGHC__)
77 #define SET_BINMODE(f) setmode(f, O_BINARY)
79 #define SET_BINMODE(f) setmode(fileno(f), O_BINARY)
84 * Standard libpcap format.
86 #define TCPDUMP_MAGIC 0xa1b2c3d4
89 * Alexey Kuznetzov's modified libpcap format.
91 #define KUZNETZOV_TCPDUMP_MAGIC 0xa1b2cd34
94 * Reserved for Francisco Mesquita <francisco.mesquita@radiomovel.pt>
95 * for another modified format.
97 #define FMESQUITA_TCPDUMP_MAGIC 0xa1b234cd
100 * Navtel Communcations' format, with nanosecond timestamps,
101 * as per a request from Dumas Hwang <dumas.hwang@navtelcom.com>.
103 #define NAVTEL_TCPDUMP_MAGIC 0xa12b3c4d
106 * Normal libpcap format, except for seconds/nanoseconds timestamps,
107 * as per a request by Ulf Lamping <ulf.lamping@web.de>
109 #define NSEC_TCPDUMP_MAGIC 0xa1b23c4d
112 * Mechanism for storing information about a capture in the upper
113 * 6 bits of a linktype value in a capture file.
115 * LT_LINKTYPE_EXT(x) extracts the additional information.
117 * The rest of the bits are for a value describing the link-layer
118 * value. LT_LINKTYPE(x) extracts that value.
120 #define LT_LINKTYPE(x) ((x) & 0x03FFFFFF)
121 #define LT_LINKTYPE_EXT(x) ((x) & 0xFC000000)
123 static int pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **datap);
126 * Private data for reading pcap savefiles.
138 } tstamp_scale_type_t;
142 swapped_type_t lengths_swapped;
143 tstamp_scale_type_t scale_type;
147 * Check whether this is a pcap savefile and, if it is, extract the
148 * relevant information from the header.
151 pcap_check_header(bpf_u_int32 magic, FILE *fp, u_int precision, char *errbuf,
154 struct pcap_file_header hdr;
161 * Assume no read errors.
166 * Check whether the first 4 bytes of the file are the magic
167 * number for a pcap savefile, or for a byte-swapped pcap
170 if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC &&
171 magic != NSEC_TCPDUMP_MAGIC) {
172 magic = SWAPLONG(magic);
173 if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC &&
174 magic != NSEC_TCPDUMP_MAGIC)
175 return (NULL); /* nope */
180 * They are. Put the magic number in the header, and read
181 * the rest of the header.
184 amt_read = fread(((char *)&hdr) + sizeof hdr.magic, 1,
185 sizeof(hdr) - sizeof(hdr.magic), fp);
186 if (amt_read != sizeof(hdr) - sizeof(hdr.magic)) {
188 snprintf(errbuf, PCAP_ERRBUF_SIZE,
189 "error reading dump file: %s",
190 pcap_strerror(errno));
192 snprintf(errbuf, PCAP_ERRBUF_SIZE,
193 "truncated dump file; tried to read %lu file header bytes, only got %lu",
194 (unsigned long)sizeof(hdr),
195 (unsigned long)amt_read);
202 * If it's a byte-swapped capture file, byte-swap the header.
205 hdr.version_major = SWAPSHORT(hdr.version_major);
206 hdr.version_minor = SWAPSHORT(hdr.version_minor);
207 hdr.thiszone = SWAPLONG(hdr.thiszone);
208 hdr.sigfigs = SWAPLONG(hdr.sigfigs);
209 hdr.snaplen = SWAPLONG(hdr.snaplen);
210 hdr.linktype = SWAPLONG(hdr.linktype);
213 if (hdr.version_major < PCAP_VERSION_MAJOR) {
214 snprintf(errbuf, PCAP_ERRBUF_SIZE,
215 "archaic pcap savefile format");
221 * OK, this is a good pcap file.
222 * Allocate a pcap_t for it.
224 p = pcap_open_offline_common(errbuf, sizeof (struct pcap_sf));
226 /* Allocation failed. */
230 p->swapped = swapped;
231 p->version_major = hdr.version_major;
232 p->version_minor = hdr.version_minor;
233 p->tzoff = hdr.thiszone;
234 p->snapshot = hdr.snaplen;
235 p->linktype = linktype_to_dlt(LT_LINKTYPE(hdr.linktype));
236 p->linktype_ext = LT_LINKTYPE_EXT(hdr.linktype);
238 p->next_packet_op = pcap_next_packet;
242 p->opt.tstamp_precision = precision;
245 * Will we need to scale the timestamps to match what the
250 case PCAP_TSTAMP_PRECISION_MICRO:
251 if (magic == NSEC_TCPDUMP_MAGIC) {
253 * The file has nanoseconds, the user
254 * wants microseconds; scale the
257 ps->scale_type = SCALE_DOWN;
260 * The file has microseconds, the
261 * user wants microseconds; nothing to do.
263 ps->scale_type = PASS_THROUGH;
267 case PCAP_TSTAMP_PRECISION_NANO:
268 if (magic == NSEC_TCPDUMP_MAGIC) {
270 * The file has nanoseconds, the
271 * user wants nanoseconds; nothing to do.
273 ps->scale_type = PASS_THROUGH;
276 * The file has microoseconds, the user
277 * wants nanoseconds; scale the
280 ps->scale_type = SCALE_UP;
285 snprintf(errbuf, PCAP_ERRBUF_SIZE,
286 "unknown time stamp resolution %u", precision);
293 * We interchanged the caplen and len fields at version 2.3,
294 * in order to match the bpf header layout. But unfortunately
295 * some files were written with version 2.3 in their headers
296 * but without the interchanged fields.
298 * In addition, DG/UX tcpdump writes out files with a version
299 * number of 543.0, and with the caplen and len fields in the
302 switch (hdr.version_major) {
305 if (hdr.version_minor < 3)
306 ps->lengths_swapped = SWAPPED;
307 else if (hdr.version_minor == 3)
308 ps->lengths_swapped = MAYBE_SWAPPED;
310 ps->lengths_swapped = NOT_SWAPPED;
314 ps->lengths_swapped = SWAPPED;
318 ps->lengths_swapped = NOT_SWAPPED;
322 if (magic == KUZNETZOV_TCPDUMP_MAGIC) {
324 * XXX - the patch that's in some versions of libpcap
325 * changes the packet header but not the magic number,
326 * and some other versions with this magic number have
327 * some extra debugging information in the packet header;
328 * we'd have to use some hacks^H^H^H^H^Hheuristics to
329 * detect those variants.
331 * Ethereal does that, but it does so by trying to read
332 * the first two packets of the file with each of the
333 * record header formats. That currently means it seeks
334 * backwards and retries the reads, which doesn't work
335 * on pipes. We want to be able to read from a pipe, so
336 * that strategy won't work; we'd have to buffer some
337 * data ourselves and read from that buffer in order to
340 ps->hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
342 if (p->linktype == DLT_EN10MB) {
344 * This capture might have been done in raw mode
347 * If it was done in cooked mode, p->snapshot was
348 * passed to recvfrom() as the buffer size, meaning
349 * that the most packet data that would be copied
350 * would be p->snapshot. However, a faked Ethernet
351 * header would then have been added to it, so the
352 * most data that would be in a packet in the file
353 * would be p->snapshot + 14.
355 * We can't easily tell whether the capture was done
356 * in raw mode or cooked mode, so we'll assume it was
357 * cooked mode, and add 14 to the snapshot length.
358 * That means that, for a raw capture, the snapshot
359 * length will be misleading if you use it to figure
360 * out why a capture doesn't have all the packet data,
361 * but there's not much we can do to avoid that.
366 ps->hdrsize = sizeof(struct pcap_sf_pkthdr);
369 * Allocate a buffer for the packet data.
371 p->bufsize = p->snapshot;
372 if (p->bufsize <= 0) {
374 * Bogus snapshot length; use the maximum as a fallback.
376 p->bufsize = MAXIMUM_SNAPLEN;
378 p->buffer = malloc(p->bufsize);
379 if (p->buffer == NULL) {
380 snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
386 p->cleanup_op = sf_cleanup;
392 * Read and return the next packet from the savefile. Return the header
393 * in hdr and a pointer to the contents in data. Return 0 on success, 1
394 * if there were no more packets, and -1 on an error.
397 pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
399 struct pcap_sf *ps = p->priv;
400 struct pcap_sf_patched_pkthdr sf_hdr;
406 * Read the packet header; the structure we use as a buffer
407 * is the longer structure for files generated by the patched
408 * libpcap, but if the file has the magic number for an
409 * unpatched libpcap we only read as many bytes as the regular
412 amt_read = fread(&sf_hdr, 1, ps->hdrsize, fp);
413 if (amt_read != ps->hdrsize) {
415 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
416 "error reading dump file: %s",
417 pcap_strerror(errno));
421 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
422 "truncated dump file; tried to read %lu header bytes, only got %lu",
423 (unsigned long)ps->hdrsize,
424 (unsigned long)amt_read);
433 /* these were written in opposite byte order */
434 hdr->caplen = SWAPLONG(sf_hdr.caplen);
435 hdr->len = SWAPLONG(sf_hdr.len);
436 hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
437 hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
439 hdr->caplen = sf_hdr.caplen;
440 hdr->len = sf_hdr.len;
441 hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
442 hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
445 switch (ps->scale_type) {
449 * Just pass the time stamp through.
455 * File has microseconds, user wants nanoseconds; convert
458 hdr->ts.tv_usec = hdr->ts.tv_usec * 1000;
463 * File has nanoseconds, user wants microseconds; convert
466 hdr->ts.tv_usec = hdr->ts.tv_usec / 1000;
470 /* Swap the caplen and len fields, if necessary. */
471 switch (ps->lengths_swapped) {
477 if (hdr->caplen <= hdr->len) {
479 * The captured length is <= the actual length,
480 * so presumably they weren't swapped.
488 hdr->caplen = hdr->len;
493 if (hdr->caplen > p->bufsize) {
495 * This can happen due to Solaris 2.3 systems tripping
496 * over the BUFMOD problem and not setting the snapshot
497 * correctly in the savefile header. If the caplen isn't
498 * grossly wrong, try to salvage.
500 static u_char *tp = NULL;
501 static size_t tsize = 0;
503 if (hdr->caplen > MAXIMUM_SNAPLEN) {
504 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
505 "bogus savefile header");
509 if (tsize < hdr->caplen) {
510 tsize = ((hdr->caplen + 1023) / 1024) * 1024;
513 tp = (u_char *)malloc(tsize);
516 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
517 "BUFMOD hack malloc");
521 amt_read = fread((char *)tp, 1, hdr->caplen, fp);
522 if (amt_read != hdr->caplen) {
524 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
525 "error reading dump file: %s",
526 pcap_strerror(errno));
528 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
529 "truncated dump file; tried to read %u captured bytes, only got %lu",
530 hdr->caplen, (unsigned long)amt_read);
535 * We can only keep up to p->bufsize bytes. Since
536 * caplen > p->bufsize is exactly how we got here,
537 * we know we can only keep the first p->bufsize bytes
538 * and must drop the remainder. Adjust caplen accordingly,
539 * so we don't get confused later as to how many bytes we
542 hdr->caplen = p->bufsize;
543 memcpy(p->buffer, (char *)tp, p->bufsize);
545 /* read the packet itself */
546 amt_read = fread(p->buffer, 1, hdr->caplen, fp);
547 if (amt_read != hdr->caplen) {
549 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
550 "error reading dump file: %s",
551 pcap_strerror(errno));
553 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
554 "truncated dump file; tried to read %u captured bytes, only got %lu",
555 hdr->caplen, (unsigned long)amt_read);
563 swap_pseudo_headers(p->linktype, hdr, *data);
569 sf_write_header(pcap_t *p, FILE *fp, int linktype, int thiszone, int snaplen)
571 struct pcap_file_header hdr;
573 hdr.magic = p->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? NSEC_TCPDUMP_MAGIC : TCPDUMP_MAGIC;
574 hdr.version_major = PCAP_VERSION_MAJOR;
575 hdr.version_minor = PCAP_VERSION_MINOR;
577 hdr.thiszone = thiszone;
578 hdr.snaplen = snaplen;
580 hdr.linktype = linktype;
582 if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
589 * Output a packet to the initialized dump file.
592 pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
595 struct pcap_sf_pkthdr sf_hdr;
598 sf_hdr.ts.tv_sec = h->ts.tv_sec;
599 sf_hdr.ts.tv_usec = h->ts.tv_usec;
600 sf_hdr.caplen = h->caplen;
602 /* XXX we should check the return status */
603 (void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
604 (void)fwrite(sp, h->caplen, 1, f);
607 static pcap_dumper_t *
608 pcap_setup_dump(pcap_t *p, int linktype, FILE *f, const char *fname)
611 #if defined(WIN32) || defined(MSDOS)
613 * If we're writing to the standard output, put it in binary
614 * mode, as savefiles are binary files.
616 * Otherwise, we turn off buffering.
617 * XXX - why? And why not on the standard output?
624 if (sf_write_header(p, f, linktype, p->tzoff, p->snapshot) == -1) {
625 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "Can't write to %s: %s",
626 fname, pcap_strerror(errno));
631 return ((pcap_dumper_t *)f);
635 * Initialize so that sf_write() will output to the file named 'fname'.
638 pcap_dump_open(pcap_t *p, const char *fname)
644 * If this pcap_t hasn't been activated, it doesn't have a
645 * link-layer type, so we can't use it.
648 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
649 "%s: not-yet-activated pcap_t passed to pcap_dump_open",
653 linktype = dlt_to_linktype(p->linktype);
654 if (linktype == -1) {
655 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
656 "%s: link-layer type %d isn't supported in savefiles",
660 linktype |= p->linktype_ext;
662 if (fname[0] == '-' && fname[1] == '\0') {
664 fname = "standard output";
666 #if !defined(WIN32) && !defined(MSDOS)
667 f = fopen(fname, "w");
669 f = fopen(fname, "wb");
672 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s: %s",
673 fname, pcap_strerror(errno));
677 return (pcap_setup_dump(p, linktype, f, fname));
681 * Initialize so that sf_write() will output to the given stream.
684 pcap_dump_fopen(pcap_t *p, FILE *f)
688 linktype = dlt_to_linktype(p->linktype);
689 if (linktype == -1) {
690 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
691 "stream: link-layer type %d isn't supported in savefiles",
695 linktype |= p->linktype_ext;
697 return (pcap_setup_dump(p, linktype, f, "stream"));
701 pcap_dump_file(pcap_dumper_t *p)
707 pcap_dump_ftell(pcap_dumper_t *p)
709 return (ftell((FILE *)p));
713 pcap_dump_flush(pcap_dumper_t *p)
716 if (fflush((FILE *)p) == EOF)
723 pcap_dump_close(pcap_dumper_t *p)
727 if (ferror((FILE *)p))
729 /* XXX should check return from fclose() too */
731 (void)fclose((FILE *)p);