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.
35 #include <pcap-types.h>
46 #include <limits.h> /* for INT_MAX */
50 #include "pcap-common.h"
52 #ifdef HAVE_OS_PROTO_H
59 * Setting O_BINARY on DOS/Windows is a bit tricky
62 #define SET_BINMODE(f) _setmode(_fileno(f), _O_BINARY)
64 #if defined(__HIGHC__)
65 #define SET_BINMODE(f) setmode(f, O_BINARY)
67 #define SET_BINMODE(f) setmode(fileno(f), O_BINARY)
72 * Standard libpcap format.
74 #define TCPDUMP_MAGIC 0xa1b2c3d4
77 * Alexey Kuznetzov's modified libpcap format.
79 #define KUZNETZOV_TCPDUMP_MAGIC 0xa1b2cd34
82 * Reserved for Francisco Mesquita <francisco.mesquita@radiomovel.pt>
83 * for another modified format.
85 #define FMESQUITA_TCPDUMP_MAGIC 0xa1b234cd
88 * Navtel Communcations' format, with nanosecond timestamps,
89 * as per a request from Dumas Hwang <dumas.hwang@navtelcom.com>.
91 #define NAVTEL_TCPDUMP_MAGIC 0xa12b3c4d
94 * Normal libpcap format, except for seconds/nanoseconds timestamps,
95 * as per a request by Ulf Lamping <ulf.lamping@web.de>
97 #define NSEC_TCPDUMP_MAGIC 0xa1b23c4d
100 * Mechanism for storing information about a capture in the upper
101 * 6 bits of a linktype value in a capture file.
103 * LT_LINKTYPE_EXT(x) extracts the additional information.
105 * The rest of the bits are for a value describing the link-layer
106 * value. LT_LINKTYPE(x) extracts that value.
108 #define LT_LINKTYPE(x) ((x) & 0x03FFFFFF)
109 #define LT_LINKTYPE_EXT(x) ((x) & 0xFC000000)
111 static int pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **datap);
115 * This isn't exported on Windows, because it would only work if both
116 * libpcap and the code using it were using the same C runtime; otherwise they
117 * would be using different definitions of a FILE structure.
119 * Instead we define this as a macro in pcap/pcap.h that wraps the hopen
120 * version that we do export, passing it a raw OS HANDLE, as defined by the
121 * Win32 / Win64 ABI, obtained from the _fileno() and _get_osfhandle()
122 * functions of the appropriate CRT.
124 static pcap_dumper_t *pcap_dump_fopen(pcap_t *p, FILE *f);
128 * Private data for reading pcap savefiles.
140 } tstamp_scale_type_t;
144 swapped_type_t lengths_swapped;
145 tstamp_scale_type_t scale_type;
149 * Check whether this is a pcap savefile and, if it is, extract the
150 * relevant information from the header.
153 pcap_check_header(const uint8_t *magic, FILE *fp, u_int precision, char *errbuf,
156 bpf_u_int32 magic_int;
157 struct pcap_file_header hdr;
164 * Assume no read errors.
169 * Check whether the first 4 bytes of the file are the magic
170 * number for a pcap savefile, or for a byte-swapped pcap
173 memcpy(&magic_int, magic, sizeof(magic_int));
174 if (magic_int != TCPDUMP_MAGIC &&
175 magic_int != KUZNETZOV_TCPDUMP_MAGIC &&
176 magic_int != NSEC_TCPDUMP_MAGIC) {
177 magic_int = SWAPLONG(magic_int);
178 if (magic_int != TCPDUMP_MAGIC &&
179 magic_int != KUZNETZOV_TCPDUMP_MAGIC &&
180 magic_int != NSEC_TCPDUMP_MAGIC)
181 return (NULL); /* nope */
186 * They are. Put the magic number in the header, and read
187 * the rest of the header.
189 hdr.magic = magic_int;
190 amt_read = fread(((char *)&hdr) + sizeof hdr.magic, 1,
191 sizeof(hdr) - sizeof(hdr.magic), fp);
192 if (amt_read != sizeof(hdr) - sizeof(hdr.magic)) {
194 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
195 errno, "error reading dump file");
197 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
198 "truncated dump file; tried to read %" PRIsize " file header bytes, only got %" PRIsize,
199 sizeof(hdr), amt_read);
206 * If it's a byte-swapped capture file, byte-swap the header.
209 hdr.version_major = SWAPSHORT(hdr.version_major);
210 hdr.version_minor = SWAPSHORT(hdr.version_minor);
211 hdr.thiszone = SWAPLONG(hdr.thiszone);
212 hdr.sigfigs = SWAPLONG(hdr.sigfigs);
213 hdr.snaplen = SWAPLONG(hdr.snaplen);
214 hdr.linktype = SWAPLONG(hdr.linktype);
217 if (hdr.version_major < PCAP_VERSION_MAJOR) {
218 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
219 "archaic pcap savefile format");
225 * currently only versions 2.[0-4] are supported with
226 * the exception of 543.0 for DG/UX tcpdump.
228 if (! ((hdr.version_major == PCAP_VERSION_MAJOR &&
229 hdr.version_minor <= PCAP_VERSION_MINOR) ||
230 (hdr.version_major == 543 &&
231 hdr.version_minor == 0))) {
232 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
233 "unsupported pcap savefile version %u.%u",
234 hdr.version_major, hdr.version_minor);
240 * OK, this is a good pcap file.
241 * Allocate a pcap_t for it.
243 p = pcap_open_offline_common(errbuf, sizeof (struct pcap_sf));
245 /* Allocation failed. */
249 p->swapped = swapped;
250 p->version_major = hdr.version_major;
251 p->version_minor = hdr.version_minor;
252 p->tzoff = hdr.thiszone;
253 p->linktype = linktype_to_dlt(LT_LINKTYPE(hdr.linktype));
254 p->linktype_ext = LT_LINKTYPE_EXT(hdr.linktype);
255 p->snapshot = pcap_adjust_snapshot(p->linktype, hdr.snaplen);
257 p->next_packet_op = pcap_next_packet;
261 p->opt.tstamp_precision = precision;
264 * Will we need to scale the timestamps to match what the
269 case PCAP_TSTAMP_PRECISION_MICRO:
270 if (magic_int == NSEC_TCPDUMP_MAGIC) {
272 * The file has nanoseconds, the user
273 * wants microseconds; scale the
276 ps->scale_type = SCALE_DOWN;
279 * The file has microseconds, the
280 * user wants microseconds; nothing to do.
282 ps->scale_type = PASS_THROUGH;
286 case PCAP_TSTAMP_PRECISION_NANO:
287 if (magic_int == NSEC_TCPDUMP_MAGIC) {
289 * The file has nanoseconds, the
290 * user wants nanoseconds; nothing to do.
292 ps->scale_type = PASS_THROUGH;
295 * The file has microoseconds, the user
296 * wants nanoseconds; scale the
299 ps->scale_type = SCALE_UP;
304 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
305 "unknown time stamp resolution %u", precision);
312 * We interchanged the caplen and len fields at version 2.3,
313 * in order to match the bpf header layout. But unfortunately
314 * some files were written with version 2.3 in their headers
315 * but without the interchanged fields.
317 * In addition, DG/UX tcpdump writes out files with a version
318 * number of 543.0, and with the caplen and len fields in the
321 switch (hdr.version_major) {
324 if (hdr.version_minor < 3)
325 ps->lengths_swapped = SWAPPED;
326 else if (hdr.version_minor == 3)
327 ps->lengths_swapped = MAYBE_SWAPPED;
329 ps->lengths_swapped = NOT_SWAPPED;
333 ps->lengths_swapped = SWAPPED;
337 ps->lengths_swapped = NOT_SWAPPED;
341 if (magic_int == KUZNETZOV_TCPDUMP_MAGIC) {
343 * XXX - the patch that's in some versions of libpcap
344 * changes the packet header but not the magic number,
345 * and some other versions with this magic number have
346 * some extra debugging information in the packet header;
347 * we'd have to use some hacks^H^H^H^H^Hheuristics to
348 * detect those variants.
350 * Ethereal does that, but it does so by trying to read
351 * the first two packets of the file with each of the
352 * record header formats. That currently means it seeks
353 * backwards and retries the reads, which doesn't work
354 * on pipes. We want to be able to read from a pipe, so
355 * that strategy won't work; we'd have to buffer some
356 * data ourselves and read from that buffer in order to
359 ps->hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
361 if (p->linktype == DLT_EN10MB) {
363 * This capture might have been done in raw mode
366 * If it was done in cooked mode, p->snapshot was
367 * passed to recvfrom() as the buffer size, meaning
368 * that the most packet data that would be copied
369 * would be p->snapshot. However, a faked Ethernet
370 * header would then have been added to it, so the
371 * most data that would be in a packet in the file
372 * would be p->snapshot + 14.
374 * We can't easily tell whether the capture was done
375 * in raw mode or cooked mode, so we'll assume it was
376 * cooked mode, and add 14 to the snapshot length.
377 * That means that, for a raw capture, the snapshot
378 * length will be misleading if you use it to figure
379 * out why a capture doesn't have all the packet data,
380 * but there's not much we can do to avoid that.
382 * But don't grow the snapshot length past the
383 * maximum value of an int.
385 if (p->snapshot <= INT_MAX - 14)
388 p->snapshot = INT_MAX;
391 ps->hdrsize = sizeof(struct pcap_sf_pkthdr);
394 * Allocate a buffer for the packet data.
395 * Choose the minimum of the file's snapshot length and 2K bytes;
396 * that should be enough for most network packets - we'll grow it
397 * if necessary. That way, we don't allocate a huge chunk of
398 * memory just because there's a huge snapshot length, as the
399 * snapshot length might be larger than the size of the largest
402 p->bufsize = p->snapshot;
403 if (p->bufsize > 2048)
405 p->buffer = malloc(p->bufsize);
406 if (p->buffer == NULL) {
407 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
413 p->cleanup_op = sf_cleanup;
419 * Grow the packet buffer to the specified size.
422 grow_buffer(pcap_t *p, u_int bufsize)
426 bigger_buffer = realloc(p->buffer, bufsize);
427 if (bigger_buffer == NULL) {
428 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "out of memory");
431 p->buffer = bigger_buffer;
432 p->bufsize = bufsize;
437 * Read and return the next packet from the savefile. Return the header
438 * in hdr and a pointer to the contents in data. Return 0 on success, 1
439 * if there were no more packets, and -1 on an error.
442 pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
444 struct pcap_sf *ps = p->priv;
445 struct pcap_sf_patched_pkthdr sf_hdr;
451 * Read the packet header; the structure we use as a buffer
452 * is the longer structure for files generated by the patched
453 * libpcap, but if the file has the magic number for an
454 * unpatched libpcap we only read as many bytes as the regular
457 amt_read = fread(&sf_hdr, 1, ps->hdrsize, fp);
458 if (amt_read != ps->hdrsize) {
460 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
461 errno, "error reading dump file");
465 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
466 "truncated dump file; tried to read %" PRIsize " header bytes, only got %" PRIsize,
467 ps->hdrsize, amt_read);
476 /* these were written in opposite byte order */
477 hdr->caplen = SWAPLONG(sf_hdr.caplen);
478 hdr->len = SWAPLONG(sf_hdr.len);
479 hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
480 hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
482 hdr->caplen = sf_hdr.caplen;
483 hdr->len = sf_hdr.len;
484 hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
485 hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
488 switch (ps->scale_type) {
492 * Just pass the time stamp through.
498 * File has microseconds, user wants nanoseconds; convert
501 hdr->ts.tv_usec = hdr->ts.tv_usec * 1000;
506 * File has nanoseconds, user wants microseconds; convert
509 hdr->ts.tv_usec = hdr->ts.tv_usec / 1000;
513 /* Swap the caplen and len fields, if necessary. */
514 switch (ps->lengths_swapped) {
520 if (hdr->caplen <= hdr->len) {
522 * The captured length is <= the actual length,
523 * so presumably they weren't swapped.
531 hdr->caplen = hdr->len;
537 * Is the packet bigger than we consider sane?
539 if (hdr->caplen > max_snaplen_for_dlt(p->linktype)) {
541 * Yes. This may be a damaged or fuzzed file.
543 * Is it bigger than the snapshot length?
544 * (We don't treat that as an error if it's not
545 * bigger than the maximum we consider sane; see
548 if (hdr->caplen > (bpf_u_int32)p->snapshot) {
549 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
550 "invalid packet capture length %u, bigger than "
551 "snaplen of %d", hdr->caplen, p->snapshot);
553 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
554 "invalid packet capture length %u, bigger than "
555 "maximum of %u", hdr->caplen,
556 max_snaplen_for_dlt(p->linktype));
561 if (hdr->caplen > (bpf_u_int32)p->snapshot) {
563 * The packet is bigger than the snapshot length
566 * This can happen due to Solaris 2.3 systems tripping
567 * over the BUFMOD problem and not setting the snapshot
568 * length correctly in the savefile header.
570 * libpcap 0.4 and later on Solaris 2.3 should set the
571 * snapshot length correctly in the pcap file header,
572 * even though they don't set a snapshot length in bufmod
573 * (the buggy bufmod chops off the *beginning* of the
574 * packet if a snapshot length is specified); they should
575 * also reduce the captured length, as supplied to the
576 * per-packet callback, to the snapshot length if it's
577 * greater than the snapshot length, so the code using
578 * libpcap should see the packet cut off at the snapshot
579 * length, even though the full packet is copied up to
582 * However, perhaps some versions of libpcap failed to
583 * set the snapshot length currectly in the file header
584 * or the per-packet header, or perhaps this is a
585 * corrupted safefile or a savefile built/modified by a
586 * fuzz tester, so we check anyway. We grow the buffer
587 * to be big enough for the snapshot length, read up
588 * to the snapshot length, discard the rest of the
589 * packet, and report the snapshot length as the captured
590 * length; we don't want to hand our caller a packet
591 * bigger than the snapshot length, because they might
592 * be assuming they'll never be handed such a packet,
593 * and might copy the packet into a snapshot-length-
594 * sized buffer, assuming it'll fit.
596 size_t bytes_to_discard;
597 size_t bytes_to_read, bytes_read;
598 char discard_buf[4096];
600 if (hdr->caplen > p->bufsize) {
602 * Grow the buffer to the snapshot length.
604 if (!grow_buffer(p, p->snapshot))
609 * Read the first p->snapshot bytes into the buffer.
611 amt_read = fread(p->buffer, 1, p->snapshot, fp);
612 if (amt_read != (bpf_u_int32)p->snapshot) {
614 pcap_fmt_errmsg_for_errno(p->errbuf,
615 PCAP_ERRBUF_SIZE, errno,
616 "error reading dump file");
619 * Yes, this uses hdr->caplen; technically,
620 * it's true, because we would try to read
621 * and discard the rest of those bytes, and
622 * that would fail because we got EOF before
625 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
626 "truncated dump file; tried to read %u captured bytes, only got %" PRIsize,
627 p->snapshot, amt_read);
633 * Now read and discard what's left.
635 bytes_to_discard = hdr->caplen - p->snapshot;
636 bytes_read = amt_read;
637 while (bytes_to_discard != 0) {
638 bytes_to_read = bytes_to_discard;
639 if (bytes_to_read > sizeof (discard_buf))
640 bytes_to_read = sizeof (discard_buf);
641 amt_read = fread(discard_buf, 1, bytes_to_read, fp);
642 bytes_read += amt_read;
643 if (amt_read != bytes_to_read) {
645 pcap_fmt_errmsg_for_errno(p->errbuf,
646 PCAP_ERRBUF_SIZE, errno,
647 "error reading dump file");
649 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
650 "truncated dump file; tried to read %u captured bytes, only got %" PRIsize,
651 hdr->caplen, bytes_read);
655 bytes_to_discard -= amt_read;
659 * Adjust caplen accordingly, so we don't get confused later
660 * as to how many bytes we have to play with.
662 hdr->caplen = p->snapshot;
665 * The packet is within the snapshot length for this file.
667 if (hdr->caplen > p->bufsize) {
669 * Grow the buffer to the next power of 2, or
670 * the snaplen, whichever is lower.
674 new_bufsize = hdr->caplen;
676 * http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
679 new_bufsize |= new_bufsize >> 1;
680 new_bufsize |= new_bufsize >> 2;
681 new_bufsize |= new_bufsize >> 4;
682 new_bufsize |= new_bufsize >> 8;
683 new_bufsize |= new_bufsize >> 16;
686 if (new_bufsize > (u_int)p->snapshot)
687 new_bufsize = p->snapshot;
689 if (!grow_buffer(p, new_bufsize))
693 /* read the packet itself */
694 amt_read = fread(p->buffer, 1, hdr->caplen, fp);
695 if (amt_read != hdr->caplen) {
697 pcap_fmt_errmsg_for_errno(p->errbuf,
698 PCAP_ERRBUF_SIZE, errno,
699 "error reading dump file");
701 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
702 "truncated dump file; tried to read %u captured bytes, only got %" PRIsize,
703 hdr->caplen, amt_read);
711 swap_pseudo_headers(p->linktype, hdr, *data);
717 sf_write_header(pcap_t *p, FILE *fp, int linktype, int thiszone, int snaplen)
719 struct pcap_file_header hdr;
721 hdr.magic = p->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? NSEC_TCPDUMP_MAGIC : TCPDUMP_MAGIC;
722 hdr.version_major = PCAP_VERSION_MAJOR;
723 hdr.version_minor = PCAP_VERSION_MINOR;
725 hdr.thiszone = thiszone;
726 hdr.snaplen = snaplen;
728 hdr.linktype = linktype;
730 if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
737 * Output a packet to the initialized dump file.
740 pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
743 struct pcap_sf_pkthdr sf_hdr;
746 sf_hdr.ts.tv_sec = h->ts.tv_sec;
747 sf_hdr.ts.tv_usec = h->ts.tv_usec;
748 sf_hdr.caplen = h->caplen;
750 /* XXX we should check the return status */
751 (void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
752 (void)fwrite(sp, h->caplen, 1, f);
755 static pcap_dumper_t *
756 pcap_setup_dump(pcap_t *p, int linktype, FILE *f, const char *fname)
759 #if defined(_WIN32) || defined(MSDOS)
761 * If we're writing to the standard output, put it in binary
762 * mode, as savefiles are binary files.
764 * Otherwise, we turn off buffering.
765 * XXX - why? And why not on the standard output?
770 setvbuf(f, NULL, _IONBF, 0);
772 if (sf_write_header(p, f, linktype, p->tzoff, p->snapshot) == -1) {
773 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
774 errno, "Can't write to %s", fname);
779 return ((pcap_dumper_t *)f);
783 * Initialize so that sf_write() will output to the file named 'fname'.
786 pcap_dump_open(pcap_t *p, const char *fname)
792 * If this pcap_t hasn't been activated, it doesn't have a
793 * link-layer type, so we can't use it.
796 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
797 "%s: not-yet-activated pcap_t passed to pcap_dump_open",
801 linktype = dlt_to_linktype(p->linktype);
802 if (linktype == -1) {
803 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
804 "%s: link-layer type %d isn't supported in savefiles",
808 linktype |= p->linktype_ext;
811 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
812 "A null pointer was supplied as the file name");
815 if (fname[0] == '-' && fname[1] == '\0') {
817 fname = "standard output";
820 * "b" is supported as of C90, so *all* UN*Xes should
821 * support it, even though it does nothing. It's
822 * required on Windows, as the file is a binary file
823 * and must be written in binary mode.
825 f = fopen(fname, "wb");
827 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
832 return (pcap_setup_dump(p, linktype, f, fname));
837 * Initialize so that sf_write() will output to a stream wrapping the given raw
841 pcap_dump_hopen(pcap_t *p, intptr_t osfd)
846 fd = _open_osfhandle(osfd, _O_APPEND);
848 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
849 errno, "_open_osfhandle");
853 file = _fdopen(fd, "wb");
855 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
861 return pcap_dump_fopen(p, file);
866 * Initialize so that sf_write() will output to the given stream.
872 pcap_dump_fopen(pcap_t *p, FILE *f)
876 linktype = dlt_to_linktype(p->linktype);
877 if (linktype == -1) {
878 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
879 "stream: link-layer type %d isn't supported in savefiles",
883 linktype |= p->linktype_ext;
885 return (pcap_setup_dump(p, linktype, f, "stream"));
889 pcap_dump_open_append(pcap_t *p, const char *fname)
894 struct pcap_file_header ph;
896 linktype = dlt_to_linktype(p->linktype);
897 if (linktype == -1) {
898 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
899 "%s: link-layer type %d isn't supported in savefiles",
905 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
906 "A null pointer was supplied as the file name");
909 if (fname[0] == '-' && fname[1] == '\0')
910 return (pcap_setup_dump(p, linktype, stdout, "standard output"));
913 * "a" will cause the file *not* to be truncated if it exists
914 * but will cause it to be created if it doesn't. It will
915 * also cause all writes to be done at the end of the file,
916 * but will allow reads to be done anywhere in the file. This
917 * is what we need, because we need to read from the beginning
918 * of the file to see if it already has a header and packets
921 * "b" is supported as of C90, so *all* UN*Xes should support it,
922 * even though it does nothing. It's required on Windows, as the
923 * file is a binary file and must be read in binary mode.
925 f = fopen(fname, "ab+");
927 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
933 * Try to read a pcap header.
935 * We do not assume that the file will be positioned at the
936 * beginning immediately after we've opened it - we seek to
937 * the beginning. ISO C says it's implementation-defined
938 * whether the file position indicator is at the beginning
939 * or the end of the file after an append-mode open, and
940 * it wasn't obvious from the Single UNIX Specification
941 * or the Microsoft documentation how that works on SUS-
942 * compliant systems or on Windows.
944 if (fseek(f, 0, SEEK_SET) == -1) {
945 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
946 errno, "Can't seek to the beginning of %s", fname);
950 amt_read = fread(&ph, 1, sizeof (ph), f);
951 if (amt_read != sizeof (ph)) {
953 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
957 } else if (feof(f) && amt_read > 0) {
958 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
959 "%s: truncated pcap file header", fname);
965 #if defined(_WIN32) || defined(MSDOS)
967 * We turn off buffering.
968 * XXX - why? And why not on the standard output?
970 setvbuf(f, NULL, _IONBF, 0);
974 * If a header is already present and:
976 * it's not for a pcap file of the appropriate resolution
977 * and the right byte order for this machine;
979 * the link-layer header types don't match;
981 * the snapshot lengths don't match;
987 * A header is already present.
993 if (p->opt.tstamp_precision != PCAP_TSTAMP_PRECISION_MICRO) {
994 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
995 "%s: different time stamp precision, cannot append to file", fname);
1001 case NSEC_TCPDUMP_MAGIC:
1002 if (p->opt.tstamp_precision != PCAP_TSTAMP_PRECISION_NANO) {
1003 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
1004 "%s: different time stamp precision, cannot append to file", fname);
1010 case SWAPLONG(TCPDUMP_MAGIC):
1011 case SWAPLONG(NSEC_TCPDUMP_MAGIC):
1012 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
1013 "%s: different byte order, cannot append to file", fname);
1017 case KUZNETZOV_TCPDUMP_MAGIC:
1018 case SWAPLONG(KUZNETZOV_TCPDUMP_MAGIC):
1019 case NAVTEL_TCPDUMP_MAGIC:
1020 case SWAPLONG(NAVTEL_TCPDUMP_MAGIC):
1021 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
1022 "%s: not a pcap file to which we can append", fname);
1027 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
1028 "%s: not a pcap file", fname);
1036 if (ph.version_major != PCAP_VERSION_MAJOR ||
1037 ph.version_minor != PCAP_VERSION_MINOR) {
1038 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
1039 "%s: version is %u.%u, cannot append to file", fname,
1040 ph.version_major, ph.version_minor);
1044 if ((bpf_u_int32)linktype != ph.linktype) {
1045 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
1046 "%s: different linktype, cannot append to file", fname);
1050 if ((bpf_u_int32)p->snapshot != ph.snaplen) {
1051 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
1052 "%s: different snaplen, cannot append to file", fname);
1058 * A header isn't present; attempt to write it.
1060 if (sf_write_header(p, f, linktype, p->tzoff, p->snapshot) == -1) {
1061 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
1062 errno, "Can't write to %s", fname);
1069 * Start writing at the end of the file.
1071 * XXX - this shouldn't be necessary, given that we're opening
1072 * the file in append mode, and ISO C specifies that all writes
1073 * are done at the end of the file in that mode.
1075 if (fseek(f, 0, SEEK_END) == -1) {
1076 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
1077 errno, "Can't seek to the end of %s", fname);
1081 return ((pcap_dumper_t *)f);
1085 pcap_dump_file(pcap_dumper_t *p)
1091 pcap_dump_ftell(pcap_dumper_t *p)
1093 return (ftell((FILE *)p));
1096 #if defined(HAVE_FSEEKO)
1098 * We have fseeko(), so we have ftello().
1099 * If we have large file support (files larger than 2^31-1 bytes),
1100 * ftello() will give us a current file position with more than 32
1104 pcap_dump_ftell64(pcap_dumper_t *p)
1106 return (ftello((FILE *)p));
1108 #elif defined(_MSC_VER)
1110 * We have Visual Studio; we support only 2005 and later, so we have
1114 pcap_dump_ftell64(pcap_dumper_t *p)
1116 return (_ftelli64((FILE *)p));
1120 * We don't have ftello() or _ftelli64(), so fall back on ftell().
1121 * Either long is 64 bits, in which case ftell() should suffice,
1122 * or this is probably an older 32-bit UN*X without large file
1123 * support, which means you'll probably get errors trying to
1124 * write files > 2^31-1, so it won't matter anyway.
1126 * XXX - what about MinGW?
1129 pcap_dump_ftell64(pcap_dumper_t *p)
1131 return (ftell((FILE *)p));
1136 pcap_dump_flush(pcap_dumper_t *p)
1139 if (fflush((FILE *)p) == EOF)
1146 pcap_dump_close(pcap_dumper_t *p)
1150 if (ferror((FILE *)p))
1152 /* XXX should check return from fclose() too */
1154 (void)fclose((FILE *)p);