3 * $Id: libpcap.c,v 1.48 2001/03/15 09:11:03 guy Exp $
6 * Copyright (c) 1998 by Gilbert Ramirez <gram@xiexie.org>
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version 2
11 * of the License, or (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 #include "file_wrappers.h"
33 /* See source to the "libpcap" library for information on the "libpcap"
36 /* On some systems, the FDDI MAC addresses are bit-swapped. */
37 #if !defined(ultrix) && !defined(__alpha) && !defined(__bsdi__)
38 #define BIT_SWAPPED_MAC_ADDRS
42 /* Try to read the first two records of the capture file. */
44 THIS_FORMAT, /* the reads succeeded, assume it's this format */
45 BAD_READ, /* the file is probably not valid */
46 OTHER_FORMAT /* the file may be valid, but not in this format */
48 static libpcap_try_t libpcap_try(wtap *wth, int *err);
50 static gboolean libpcap_read(wtap *wth, int *err, int *data_offset);
51 static int libpcap_read_header(wtap *wth, int *err,
52 struct pcaprec_ss990915_hdr *hdr, gboolean silent);
53 static void adjust_header(wtap *wth, struct pcaprec_hdr *hdr);
54 static void libpcap_close(wtap *wth);
55 static gboolean libpcap_dump(wtap_dumper *wdh, const struct wtap_pkthdr *phdr,
56 const union wtap_pseudo_header *pseudo_header, const u_char *pd, int *err);
59 * Either LBL NRG wasn't an adequate central registry (e.g., because of
60 * the slow rate of releases from them), or nobody bothered using them
61 * as a central registry, as many different groups have patched libpcap
62 * (and BPF, on the BSDs) to add new encapsulation types, and have ended
63 * up using the same DLT_ values for different encapsulation types.
65 * For those numerical encapsulation type values that everybody uses for
66 * the same encapsulation type (which inclues those that some platforms
67 * specify different DLT_ names for but don't appear to use), we map
68 * those values to the appropriate Wiretap values.
70 * For those numerical encapsulation type values that different libpcap
71 * variants use for different encapsulation types, we check what
72 * <pcap.h> defined to determine how to interpret them, so that we
73 * interpret them the way the libpcap with which we're building
74 * Ethereal/Wiretap interprets them (which, if it doesn't support
75 * them at all, means we don't support them either - any capture files
76 * using them are foreign, and we don't hazard a guess as to which
77 * platform they came from; we could, I guess, choose the most likely
88 } pcap_to_wtap_map[] = {
90 * These are the values that are almost certainly the same
91 * in all libpcaps (I've yet to find one where the values
92 * in question are used for some purpose other than the
93 * one below, but...), and that Wiretap and Ethereal
96 { 0, WTAP_ENCAP_NULL }, /* null encapsulation */
97 { 1, WTAP_ENCAP_ETHERNET },
98 { 6, WTAP_ENCAP_TOKEN_RING }, /* IEEE 802 Networks - assume token ring */
99 { 7, WTAP_ENCAP_ARCNET },
100 { 8, WTAP_ENCAP_SLIP },
101 { 9, WTAP_ENCAP_PPP },
102 #ifdef BIT_SWAPPED_MAC_ADDRS
103 { 10, WTAP_ENCAP_FDDI_BITSWAPPED },
105 { 10, WTAP_ENCAP_FDDI },
109 * 11 is DLT_ATM_RFC1483 on most platforms; the only libpcaps I've
110 * seen that define anything other than DLT_ATM_RFC1483 as 11 are
111 * the BSD/OS one, which defines DLT_FR as 11, and libpcap 0.5,
112 * which define it as 100, mapping the kernel's value to 100, in
113 * an attempt to hide the different values used on different
116 * If this is a platform where DLT_FR is defined as 11, we
117 * don't handle 11 at all; otherwise, we handle it as
118 * DLT_ATM_RFC1483 (this means we'd misinterpret Frame Relay
119 * captures from BSD/OS if running on platforms other than BSD/OS,
122 * 1) we don't yet support DLT_FR
126 * 2) nothing short of a heuristic would let us interpret
129 #if defined(DLT_FR) && (DLT_FR == 11)
130 /* Put entry for Frame Relay here */
132 { 11, WTAP_ENCAP_ATM_RFC1483 },
136 * 12 is DLT_RAW on most platforms, but it's DLT_C_HDLC on
137 * BSD/OS, and DLT_LOOP on OpenBSD.
139 * We don't yet handle DLT_C_HDLC, but we can handle DLT_LOOP
140 * (it's just like DLT_NULL, only with the AF_ value in network
141 * rather than host byte order - Ethereal figures out the
142 * byte order from the data, so we don't care what byte order
143 * it's in), so if DLT_LOOP is defined as 12, interpret 12
144 * as WTAP_ENCAP_NULL, otherwise, unless DLT_C_HDLC is defined
145 * as 12, interpret it as WTAP_ENCAP_RAW_IP.
147 #if defined(DLT_LOOP) && (DLT_LOOP == 12)
148 { 12, WTAP_ENCAP_NULL },
149 #elif defined(DLT_C_HDLC) && (DLT_C_HDLC == 12)
151 * Put entry for Cisco HDLC here.
152 * XXX - is this just WTAP_ENCAP_CHDLC, i.e. does the frame
153 * start with a 4-byte Cisco HDLC header?
156 { 12, WTAP_ENCAP_RAW_IP },
160 * 13 is DLT_SLIP_BSDOS on FreeBSD and NetBSD, but those OSes
161 * don't actually generate it. I infer that BSD/OS translates
162 * DLT_SLIP from the kernel BPF code to DLT_SLIP_BSDOS in
163 * libpcap, as the BSD/OS link-layer header is different;
164 * however, in BSD/OS, DLT_SLIP_BSDOS is 15.
166 * From this, I infer that there's no point in handling 13
169 * 13 is DLT_ATM_RFC1483 on BSD/OS.
171 * 13 is DLT_ENC in OpenBSD, which is, I suspect, some kind
172 * of decrypted IPSEC traffic.
174 #if defined(DLT_ATM_RFC1483) && (DLT_ATM_RFC1483 == 13)
175 { 13, WTAP_ENCAP_ATM_RFC1483 },
176 #elif defined(DLT_ENC) && (DLT_ENC == 13)
177 /* Put entry for DLT_ENC here */
181 * 14 is DLT_PPP_BSDOS on FreeBSD and NetBSD, but those OSes
182 * don't actually generate it. I infer that BSD/OS translates
183 * DLT_PPP from the kernel BPF code to DLT_PPP_BSDOS in
184 * libpcap, as the BSD/OS link-layer header is different;
185 * however, in BSD/OS, DLT_PPP_BSDOS is 16.
187 * From this, I infer that there's no point in handling 14
190 * 14 is DLT_RAW on BSD/OS and OpenBSD.
192 { 14, WTAP_ENCAP_RAW_IP },
197 * DLT_SLIP_BSDOS on BSD/OS;
199 * DLT_HIPPI on NetBSD;
201 * DLT_LANE8023 with Alexey Kuznetzov's patches for
204 * DLT_I4L_RAWIP with the ISDN4Linux patches for libpcap
207 * but we don't currently handle any of those.
213 * DLT_PPP_BSDOS on BSD/OS;
215 * DLT_HDLC on NetBSD (Cisco HDLC);
217 * DLT_CIP with Alexey Kuznetzov's patches for
218 * Linux libpcap - this is WTAP_ENCAP_LINUX_ATM_CLIP;
220 * DLT_I4L_IP with the ISDN4Linux patches for libpcap
223 #if defined(DLT_CIP) && (DLT_CIP == 16)
224 { 16, WTAP_ENCAP_LINUX_ATM_CLIP },
226 #if defined(DLT_HDLC) && (DLT_HDLC == 16)
227 { 16, WTAP_ENCAP_CHDLC },
231 * 17 is DLT_LANE8023 in SuSE 6.3 libpcap; we don't currently
236 * 18 is DLT_CIP in SuSE 6.3 libpcap; if it's the same as the
237 * DLT_CIP of 16 that the Alexey Kuznetzov patches for
238 * libpcap/tcpdump define, it's WTAP_ENCAP_LINUX_ATM_CLIP.
239 * I've not found any libpcap that uses it for any other purpose -
240 * hopefully nobody will do so in the future.
242 { 18, WTAP_ENCAP_LINUX_ATM_CLIP },
245 * 19 is DLT_ATM_CLIP in the libpcap/tcpdump patches in the
246 * recent versions I've seen of the Linux ATM distribution;
247 * I've not yet found any libpcap that uses it for any other
248 * purpose - hopefully nobody will do so in the future.
250 { 19, WTAP_ENCAP_LINUX_ATM_CLIP },
253 * 50 is DLT_PPP_SERIAL in NetBSD; it appears that DLT_PPP
254 * on BSD (at least according to standard tcpdump) has, as
255 * the first octet, an indication of whether the packet was
256 * transmitted or received (rather than having the standard
257 * PPP address value of 0xff), but that DLT_PPP_SERIAL puts
258 * a real live PPP header there, or perhaps a Cisco PPP header
259 * as per section 4.3.1 of RFC 1547 (implementations of this
260 * exist in various BSDs in "sys/net/if_spppsubr.c", and
261 * I think also exist either in standard Linux or in
262 * various Linux patches; the implementations show how to handle
263 * Cisco keepalive packets).
265 * However, I don't see any obvious place in FreeBSD "if_ppp.c"
266 * where anything other than the standard PPP header would be
267 * passed up. I see some stuff that sets the first octet
268 * to 0 for incoming and 1 for outgoing packets before applying
269 * a BPF filter to see whether to drop packets whose protocol
270 * field has the 0x8000 bit set, i.e. network control protocols -
271 * those are handed up to userland - but that code puts the
272 * address field back before passing the packet up.
274 * I also don't see anything immediately obvious that munges
275 * the address field for sync PPP, either.
277 * Ethereal currently assumes that if the first octet of a
278 * PPP frame is 0xFF, it's the address field and is followed
279 * by a control field and a 2-byte protocol, otherwise the
280 * address and control fields are absent and the frame begins
281 * with a protocol field. If we ever see a BSD/OS PPP
282 * capture, we'll have to handle it differently, and we may
283 * have to handle standard BSD captures differently if, in fact,
284 * they don't have 0xff 0x03 as the first two bytes - but, as per
285 * the two paragraphs preceding this, it's not clear that
286 * the address field *is* munged into an incoming/outgoing
287 * field when the packet is handed to the BPF device.
289 * For now, we just map DLT_PPP_SERIAL to WTAP_ENCAP_PPP, as
290 * we treat WTAP_ENCAP_PPP packets as if those beginning with
291 * 0xff have the standard RFC 1662 "PPP in HDLC-like Framing"
292 * 0xff 0x03 address/control header, and DLT_PPP_SERIAL frames
293 * appear to contain that unless they're Cisco frames (if we
294 * ever see a capture with them, we'd need to implement the
295 * RFC 1547 stuff, and the keepalive protocol stuff).
297 * We may have to distinguish between "PPP where if it doesn't
298 * begin with 0xff there's no HDLC encapsulation and the frame
299 * begins with the protocol field" (which is how we handle
300 * WTAP_ENCAP_PPP now) and "PPP where there's either HDLC
301 * encapsulation or Cisco PPP" (which is what DLT_PPP_SERIAL
304 * XXX - NetBSD has DLT_HDLC, which appears to be used for
305 * Cisco HDLC. Ideally, they should use DLT_PPP_SERIAL
306 * only for real live HDLC-encapsulated PPP, not for Cisco
309 { 50, WTAP_ENCAP_PPP },
312 * These are the values that libpcap 0.5 uses, in an attempt
313 * to work around the confusion decried above, and that Wiretap
314 * and Ethereal currently support.
316 * The next version of libpcap will probably not use them as
317 * DLT_ values in its API, but will probably use them in capture
320 { 100, WTAP_ENCAP_ATM_RFC1483 },
321 { 101, WTAP_ENCAP_RAW_IP },
324 * More values used by libpcap 0.5 as DLT_ values and used by the
325 * current CVS version of libpcap in capture file headers.
326 * They are not yet handled in Ethereal.
327 * If we get a capture that contains them, we'll implement them.
329 { 102, WTAP_ENCAP_SLIP_BSDOS },
330 { 103, WTAP_ENCAP_PPP_BSDOS },
334 * These ones are handled in Ethereal, though.
336 { 104, WTAP_ENCAP_CHDLC }, /* Cisco HDLC */
337 { 106, WTAP_ENCAP_LINUX_ATM_CLIP },
340 * Values not yet used by the current CVS version of libpcap,
341 * but reserved for future use; the IEEE 802.11 value is
342 * there for use with a capture program from Axis Communications.
344 { 105, WTAP_ENCAP_IEEE_802_11 },
347 * Not yet handled in Ethereal; we don't know what encapsulation
348 * BSD/OS uses, so we don't know whether it can be handed to
349 * the Frame Relay dissector or not.
351 { 107, WTAP_ENCAP_FR }, /* Frame Relay */
353 { 108, WTAP_ENCAP_NULL }, /* OpenBSD loopback */
355 { 109, WTAP_ENCAP_ENC }, /* OpenBSD IPSEC enc */
356 { 110, WTAP_ENCAP_LANE_802_3 },/* ATM LANE 802.3 */
357 { 111, WTAP_ENCAP_HIPPI }, /* NetBSD HIPPI */
359 { 112, WTAP_ENCAP_CHDLC }, /* NetBSD HDLC framing */
362 * Linux "cooked mode" captures, used by the current CVS version
365 { 113, WTAP_ENCAP_SLL }, /* Linux cooked capture */
367 #define NUM_PCAP_ENCAPS (sizeof pcap_to_wtap_map / sizeof pcap_to_wtap_map[0])
369 int libpcap_open(wtap *wth, int *err)
374 gboolean byte_swapped;
378 /* Read in the number that should be at the start of a "libpcap" file */
379 errno = WTAP_ERR_CANT_READ;
380 bytes_read = file_read(&magic, 1, sizeof magic, wth->fh);
381 if (bytes_read != sizeof magic) {
382 *err = file_error(wth->fh);
387 wth->data_offset += sizeof magic;
392 /* Host that wrote it has our byte order, and was running
393 a program using either standard or ss990417 libpcap. */
394 byte_swapped = FALSE;
398 case PCAP_MODIFIED_MAGIC:
399 /* Host that wrote it has our byte order, and was running
400 a program using either ss990915 or ss991029 libpcap. */
401 byte_swapped = FALSE;
405 case PCAP_SWAPPED_MAGIC:
406 /* Host that wrote it has a byte order opposite to ours,
407 and was running a program using either standard or
413 case PCAP_SWAPPED_MODIFIED_MAGIC:
414 /* Host that wrote it out has a byte order opposite to
415 ours, and was running a program using either ss990915
416 or ss991029 libpcap. */
422 /* Not a "libpcap" type we know about. */
426 /* Read the rest of the header. */
427 errno = WTAP_ERR_CANT_READ;
428 bytes_read = file_read(&hdr, 1, sizeof hdr, wth->fh);
429 if (bytes_read != sizeof hdr) {
430 *err = file_error(wth->fh);
435 wth->data_offset += sizeof hdr;
438 /* Byte-swap the header fields about which we care. */
439 hdr.version_major = BSWAP16(hdr.version_major);
440 hdr.version_minor = BSWAP16(hdr.version_minor);
441 hdr.snaplen = BSWAP32(hdr.snaplen);
442 hdr.network = BSWAP32(hdr.network);
444 if (hdr.version_major < 2) {
445 /* We only support version 2.0 and later. */
446 g_message("pcap: major version %u unsupported",
448 *err = WTAP_ERR_UNSUPPORTED;
451 file_encap = wtap_pcap_encap_to_wtap_encap(hdr.network);
452 if (file_encap == WTAP_ENCAP_UNKNOWN) {
453 g_message("pcap: network type %u unknown or unsupported",
455 *err = WTAP_ERR_UNSUPPORTED_ENCAP;
459 /* This is a libpcap file */
460 wth->capture.pcap = g_malloc(sizeof(libpcap_t));
461 wth->capture.pcap->byte_swapped = byte_swapped;
462 wth->capture.pcap->version_major = hdr.version_major;
463 wth->capture.pcap->version_minor = hdr.version_minor;
464 wth->subtype_read = libpcap_read;
465 wth->subtype_seek_read = wtap_def_seek_read;
466 wth->subtype_close = libpcap_close;
467 wth->file_encap = file_encap;
468 wth->snapshot_length = hdr.snaplen;
471 * Yes. Let's look at the header for the first record,
472 * and see if, interpreting it as a standard header (if the
473 * magic number was standard) or a modified header (if the
474 * magic number was modified), the position where it says the
475 * header for the *second* record is contains a corrupted header.
479 * If this file had the standard magic number, it may be
480 * an ss990417 capture file - in that version of Alexey's
481 * patch, the packet header format was changed but the
482 * magic number wasn't, and, alas, Red Hat appear to have
483 * picked up that version of the patch for RH 6.1, meaning
484 * RH 6.1 has a tcpdump that writes out files that can't
485 * be read by any software that expects non-modified headers
486 * if the magic number isn't the modified magic number (e.g.,
487 * any normal version of tcpdump, and Ethereal if we don't
488 * do this gross heuristic).
490 * If this file had the modified magic number, it may be
491 * an ss990915 capture file - in that version of Alexey's
492 * patch, the magic number was changed, but the record
493 * header had some extra fields, and, alas, SuSE appear
494 * to have picked up that version of the patch for SuSE
495 * 6.3, meaning that programs expecting the standard per-
496 * packet header in captures with the modified magic number
497 * can't read dumps from its tcpdump.
499 * Oh, and if it has the standard magic number, it might, instead,
500 * be a Nokia libpcap file, so we may need to try that if
501 * neither normal nor ss990417 headers work.
505 * Well, we have the magic number from Alexey's
508 * Try ss991029, the last of his patches, first.
510 wth->file_type = WTAP_FILE_PCAP_SS991029;
511 switch (libpcap_try(wth, err)) {
515 * Well, we couldn't even read it.
522 * Well, it looks as if it might be 991029.
523 * Put the seek pointer back, and return success.
525 file_seek(wth->fh, wth->data_offset, SEEK_SET);
530 * Try the next format.
536 * Well, it's not completely unreadable,
537 * but it's not ss991029. Try ss990915;
538 * there are no other types to try after that,
539 * so we put the seek pointer back and treat
542 wth->file_type = WTAP_FILE_PCAP_SS990915;
543 file_seek(wth->fh, wth->data_offset, SEEK_SET);
546 * Well, we have the standard magic number.
548 * Try the standard format first.
550 wth->file_type = WTAP_FILE_PCAP;
551 switch (libpcap_try(wth, err)) {
555 * Well, we couldn't even read it.
562 * Well, it looks as if it might be a standard
564 * Put the seek pointer back, and return success.
566 file_seek(wth->fh, wth->data_offset, SEEK_SET);
571 * Try the next format.
577 * Well, it's not completely unreadable, but it's not
578 * a standard file. Put the seek pointer back and try
581 wth->file_type = WTAP_FILE_PCAP_SS990417;
582 file_seek(wth->fh, wth->data_offset, SEEK_SET);
583 switch (libpcap_try(wth, err)) {
587 * Well, we couldn't even read it.
594 * Well, it looks as if it might be ss990417.
595 * Put the seek pointer back, and return success.
597 file_seek(wth->fh, wth->data_offset, SEEK_SET);
602 * Try the next format.
608 * Well, it's not completely unreadable,
609 * but it's not a standard file *nor* is it ss990417.
610 * Try it as a Nokia file; there are no other types
611 * to try after that, so we put the seek pointer back
612 * and treat it as a Nokia file.
614 wth->file_type = WTAP_FILE_PCAP_NOKIA;
615 file_seek(wth->fh, wth->data_offset, SEEK_SET);
621 /* Try to read the first two records of the capture file. */
622 static libpcap_try_t libpcap_try(wtap *wth, int *err)
625 * pcaprec_ss990915_hdr is the largest header type.
627 struct pcaprec_ss990915_hdr first_rec_hdr, second_rec_hdr;
630 * Attempt to read the first record's header.
632 if (libpcap_read_header(wth, err, &first_rec_hdr, TRUE) == -1) {
633 if (*err == 0 || *err == WTAP_ERR_SHORT_READ) {
635 * EOF or short read - assume the file is in this
637 * When our client tries to read the first packet
638 * they will presumably get the same EOF or short
644 if (*err == WTAP_ERR_BAD_RECORD) {
646 * The first record is bogus, so this is probably
647 * a corrupt file. Assume the file is in this
648 * format. When our client tries to read the
649 * first packet they will presumably get the
656 * Some other error, e.g. an I/O error; just give up.
662 * Now skip over the first record's data, under the assumption
663 * that the header is sane.
665 file_seek(wth->fh, first_rec_hdr.hdr.incl_len, SEEK_CUR);
668 * Now attempt to read the second record's header.
670 if (libpcap_read_header(wth, err, &second_rec_hdr, TRUE) == -1) {
671 if (*err == 0 || *err == WTAP_ERR_SHORT_READ) {
673 * EOF or short read - assume the file is in this
675 * When our client tries to read the second packet
676 * they will presumably get the same EOF or short
682 if (*err == WTAP_ERR_BAD_RECORD) {
684 * The second record is bogus; maybe it's a
685 * Capture File From Hell, and what looks like
686 * the "header" of the next packet is actually
687 * random junk from the middle of a packet.
688 * Try the next format; if we run out of formats,
689 * it probably *is* a corrupt file.
695 * Some other error, e.g. an I/O error; just give up.
701 * OK, the first two records look OK; assume this is the
707 /* Read the next packet */
708 static gboolean libpcap_read(wtap *wth, int *err, int *data_offset)
710 struct pcaprec_ss990915_hdr hdr;
714 bytes_read = libpcap_read_header(wth, err, &hdr, FALSE);
715 if (bytes_read == -1) {
717 * We failed to read the header.
722 wth->data_offset += bytes_read;
723 packet_size = hdr.hdr.incl_len;
725 buffer_assure_space(wth->frame_buffer, packet_size);
726 *data_offset = wth->data_offset;
727 errno = WTAP_ERR_CANT_READ;
728 bytes_read = file_read(buffer_start_ptr(wth->frame_buffer), 1,
729 packet_size, wth->fh);
731 if (bytes_read != packet_size) {
732 *err = file_error(wth->fh);
734 *err = WTAP_ERR_SHORT_READ;
737 wth->data_offset += packet_size;
739 wth->phdr.ts.tv_sec = hdr.hdr.ts_sec;
740 wth->phdr.ts.tv_usec = hdr.hdr.ts_usec;
741 wth->phdr.caplen = packet_size;
742 wth->phdr.len = hdr.hdr.orig_len;
743 wth->phdr.pkt_encap = wth->file_encap;
748 /* Read the header of the next packet; if "silent" is TRUE, don't complain
749 to the console, as we're testing to see if the file appears to be of a
752 Return -1 on an error, or the number of bytes of header read on success. */
753 static int libpcap_read_header(wtap *wth, int *err,
754 struct pcaprec_ss990915_hdr *hdr, gboolean silent)
756 int bytes_to_read, bytes_read;
758 /* Read record header. */
759 errno = WTAP_ERR_CANT_READ;
760 switch (wth->file_type) {
763 bytes_to_read = sizeof (struct pcaprec_hdr);
766 case WTAP_FILE_PCAP_SS990417:
767 case WTAP_FILE_PCAP_SS991029:
768 bytes_to_read = sizeof (struct pcaprec_modified_hdr);
771 case WTAP_FILE_PCAP_SS990915:
772 bytes_to_read = sizeof (struct pcaprec_ss990915_hdr);
775 case WTAP_FILE_PCAP_NOKIA:
776 bytes_to_read = sizeof (struct pcaprec_nokia_hdr);
780 g_assert_not_reached();
783 bytes_read = file_read(hdr, 1, bytes_to_read, wth->fh);
784 if (bytes_read != bytes_to_read) {
785 *err = file_error(wth->fh);
786 if (*err == 0 && bytes_read != 0) {
787 *err = WTAP_ERR_SHORT_READ;
792 adjust_header(wth, &hdr->hdr);
794 if (hdr->hdr.incl_len > WTAP_MAX_PACKET_SIZE) {
796 * Probably a corrupt capture file; return an error,
797 * so that our caller doesn't blow up trying to allocate
798 * space for an immensely-large packet, and so that
799 * the code to try to guess what type of libpcap file
800 * this is can tell when it's not the type we're guessing
804 g_message("pcap: File has %u-byte packet, bigger than maximum of %u",
805 hdr->hdr.incl_len, WTAP_MAX_PACKET_SIZE);
807 *err = WTAP_ERR_BAD_RECORD;
811 if (hdr->hdr.orig_len > WTAP_MAX_PACKET_SIZE) {
813 * Probably a corrupt capture file; return an error,
814 * so that our caller doesn't blow up trying to
815 * cope with a huge "real" packet length, and so that
816 * the code to try to guess what type of libpcap file
817 * this is can tell when it's not the type we're guessing
821 g_message("pcap: File has %u-byte packet, bigger than maximum of %u",
822 hdr->hdr.orig_len, WTAP_MAX_PACKET_SIZE);
824 *err = WTAP_ERR_BAD_RECORD;
832 adjust_header(wtap *wth, struct pcaprec_hdr *hdr)
834 if (wth->capture.pcap->byte_swapped) {
835 /* Byte-swap the record header fields. */
836 hdr->ts_sec = BSWAP32(hdr->ts_sec);
837 hdr->ts_usec = BSWAP32(hdr->ts_usec);
838 hdr->incl_len = BSWAP32(hdr->incl_len);
839 hdr->orig_len = BSWAP32(hdr->orig_len);
842 /* In file format version 2.3, the "incl_len" and "orig_len" fields
843 were swapped, in order to match the BPF header layout.
845 Unfortunately, some files were, according to a comment in the
846 "libpcap" source, written with version 2.3 in their headers
847 but without the interchanged fields, so if "incl_len" is
848 greater than "orig_len" - which would make no sense - we
849 assume that we need to swap them. */
850 if (wth->capture.pcap->version_major == 2 &&
851 (wth->capture.pcap->version_minor < 3 ||
852 (wth->capture.pcap->version_minor == 3 &&
853 hdr->incl_len > hdr->orig_len))) {
856 temp = hdr->orig_len;
857 hdr->orig_len = hdr->incl_len;
858 hdr->incl_len = temp;
863 libpcap_close(wtap *wth)
865 g_free(wth->capture.pcap);
868 int wtap_pcap_encap_to_wtap_encap(int encap)
872 for (i = 0; i < NUM_PCAP_ENCAPS; i++) {
873 if (pcap_to_wtap_map[i].dlt_value == encap)
874 return pcap_to_wtap_map[i].wtap_encap_value;
876 return WTAP_ENCAP_UNKNOWN;
879 static int wtap_wtap_encap_to_pcap_encap(int encap)
884 * Special-case WTAP_ENCAP_FDDI and WTAP_ENCAP_FDDI_BITSWAPPED;
885 * both of them get mapped to DLT_FDDI (even though that may
886 * mean that the bit order in the FDDI MAC addresses is wrong;
887 * so it goes - libpcap format doesn't record the byte order,
888 * so that's not fixable).
890 if (encap == WTAP_ENCAP_FDDI || encap == WTAP_ENCAP_FDDI_BITSWAPPED)
891 return 10; /* that's DLT_FDDI */
892 for (i = 0; i < NUM_PCAP_ENCAPS; i++) {
893 if (pcap_to_wtap_map[i].wtap_encap_value == encap)
894 return pcap_to_wtap_map[i].dlt_value;
899 /* Returns 0 if we could write the specified encapsulation type,
900 an error indication otherwise. */
901 int libpcap_dump_can_write_encap(int filetype, int encap)
903 /* Per-packet encapsulations aren't supported. */
904 if (encap == WTAP_ENCAP_PER_PACKET)
905 return WTAP_ERR_ENCAP_PER_PACKET_UNSUPPORTED;
907 if (wtap_wtap_encap_to_pcap_encap(encap) == -1)
908 return WTAP_ERR_UNSUPPORTED_ENCAP;
913 /* Returns TRUE on success, FALSE on failure; sets "*err" to an error code on
915 gboolean libpcap_dump_open(wtap_dumper *wdh, int *err)
918 struct pcap_hdr file_hdr;
921 /* This is a libpcap file */
922 wdh->subtype_write = libpcap_dump;
923 wdh->subtype_close = NULL;
925 /* Write the file header. */
926 switch (wdh->file_type) {
929 case WTAP_FILE_PCAP_SS990417: /* modified, but with the old magic, sigh */
930 case WTAP_FILE_PCAP_NOKIA: /* Nokia libpcap of some sort */
934 case WTAP_FILE_PCAP_SS990915: /* new magic, extra crap */
935 case WTAP_FILE_PCAP_SS991029:
936 magic = PCAP_MODIFIED_MAGIC;
940 /* We should never get here - our open routine
941 should only get called for the types above. */
942 *err = WTAP_ERR_UNSUPPORTED_FILE_TYPE;
946 nwritten = fwrite(&magic, 1, sizeof magic, wdh->fh);
947 if (nwritten != sizeof magic) {
951 *err = WTAP_ERR_SHORT_WRITE;
955 /* current "libpcap" format is 2.4 */
956 file_hdr.version_major = 2;
957 file_hdr.version_minor = 4;
958 file_hdr.thiszone = 0; /* XXX - current offset? */
959 file_hdr.sigfigs = 0; /* unknown, but also apparently unused */
960 file_hdr.snaplen = wdh->snaplen;
961 file_hdr.network = wtap_wtap_encap_to_pcap_encap(wdh->encap);
962 nwritten = fwrite(&file_hdr, 1, sizeof file_hdr, wdh->fh);
963 if (nwritten != sizeof file_hdr) {
967 *err = WTAP_ERR_SHORT_WRITE;
974 /* Write a record for a packet to a dump file.
975 Returns TRUE on success, FALSE on failure. */
976 static gboolean libpcap_dump(wtap_dumper *wdh, const struct wtap_pkthdr *phdr,
977 const union wtap_pseudo_header *pseudo_header, const u_char *pd, int *err)
979 struct pcaprec_ss990915_hdr rec_hdr;
983 rec_hdr.hdr.ts_sec = phdr->ts.tv_sec;
984 rec_hdr.hdr.ts_usec = phdr->ts.tv_usec;
985 rec_hdr.hdr.incl_len = phdr->caplen;
986 rec_hdr.hdr.orig_len = phdr->len;
987 switch (wdh->file_type) {
990 hdr_size = sizeof (struct pcaprec_hdr);
993 case WTAP_FILE_PCAP_SS990417: /* modified, but with the old magic, sigh */
994 case WTAP_FILE_PCAP_SS991029:
995 /* XXX - what should we supply here?
997 Alexey's "libpcap" looks up the interface in the system's
998 interface list if "ifindex" is non-zero, and prints
999 the interface name. It ignores "protocol", and uses
1000 "pkt_type" to tag the packet as "host", "broadcast",
1001 "multicast", "other host", "outgoing", or "none of the
1002 above", but that's it.
1004 If the capture we're writing isn't a modified or
1005 RH 6.1 capture, we'd have to do some work to
1006 generate the packet type and interface index - and
1007 we can't generate the interface index unless we
1008 just did the capture ourselves in any case.
1010 I'm inclined to continue to punt; systems other than
1011 those with the older patch can read standard "libpcap"
1012 files, and systems with the older patch, e.g. RH 6.1,
1013 will just have to live with this. */
1014 rec_hdr.ifindex = 0;
1015 rec_hdr.protocol = 0;
1016 rec_hdr.pkt_type = 0;
1017 hdr_size = sizeof (struct pcaprec_modified_hdr);
1020 case WTAP_FILE_PCAP_SS990915: /* new magic, extra crap at the end */
1021 rec_hdr.ifindex = 0;
1022 rec_hdr.protocol = 0;
1023 rec_hdr.pkt_type = 0;
1026 hdr_size = sizeof (struct pcaprec_ss990915_hdr);
1029 case WTAP_FILE_PCAP_NOKIA: /* old magic, extra crap at the end */
1030 rec_hdr.ifindex = 0;
1031 rec_hdr.protocol = 0;
1032 rec_hdr.pkt_type = 0;
1035 hdr_size = sizeof (struct pcaprec_nokia_hdr);
1039 /* We should never get here - our open routine
1040 should only get called for the types above. */
1041 g_assert_not_reached();
1042 *err = WTAP_ERR_UNSUPPORTED_FILE_TYPE;
1046 nwritten = fwrite(&rec_hdr, 1, hdr_size, wdh->fh);
1047 if (nwritten != hdr_size) {
1051 *err = WTAP_ERR_SHORT_WRITE;
1054 nwritten = fwrite(pd, 1, phdr->caplen, wdh->fh);
1055 if (nwritten != phdr->caplen) {
1059 *err = WTAP_ERR_SHORT_WRITE;