xref: /freebsd/contrib/libpcap/pcap-common.c (revision 0957b409a90fd597c1e9124cbaf3edd2b488f4ac)
1 /*
2  * Copyright (c) 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  * pcap-common.c - common code for pcap and pcapng files
22  */
23 
24 #ifdef HAVE_CONFIG_H
25 #include <config.h>
26 #endif
27 
28 #include <pcap-types.h>
29 
30 #include "pcap-int.h"
31 #include "extract.h"
32 #include "pcap/sll.h"
33 #include "pcap/usb.h"
34 #include "pcap/nflog.h"
35 #include "pcap/can_socketcan.h"
36 
37 #include "pcap-common.h"
38 
39 /*
40  * We don't write DLT_* values to capture files, because they're not the
41  * same on all platforms.
42  *
43  * Unfortunately, the various flavors of BSD have not always used the same
44  * numerical values for the same data types, and various patches to
45  * libpcap for non-BSD OSes have added their own DLT_* codes for link
46  * layer encapsulation types seen on those OSes, and those codes have had,
47  * in some cases, values that were also used, on other platforms, for other
48  * link layer encapsulation types.
49  *
50  * This means that capture files of a type whose numerical DLT_* code
51  * means different things on different BSDs, or with different versions
52  * of libpcap, can't always be read on systems other than those like
53  * the one running on the machine on which the capture was made.
54  *
55  * Instead, we define here a set of LINKTYPE_* codes, and map DLT_* codes
56  * to LINKTYPE_* codes when writing a savefile header, and map LINKTYPE_*
57  * codes to DLT_* codes when reading a savefile header.
58  *
59  * For those DLT_* codes that have, as far as we know, the same values on
60  * all platforms (DLT_NULL through DLT_FDDI), we define LINKTYPE_xxx as
61  * DLT_xxx; that way, captures of those types can still be read by
62  * versions of libpcap that map LINKTYPE_* values to DLT_* values, and
63  * captures of those types written by versions of libpcap that map DLT_
64  * values to LINKTYPE_ values can still be read by older versions
65  * of libpcap.
66  *
67  * The other LINKTYPE_* codes are given values starting at 100, in the
68  * hopes that no DLT_* code will be given one of those values.
69  *
70  * In order to ensure that a given LINKTYPE_* code's value will refer to
71  * the same encapsulation type on all platforms, you should not allocate
72  * a new LINKTYPE_* value without consulting
73  * "tcpdump-workers@lists.tcpdump.org".  The tcpdump developers will
74  * allocate a value for you, and will not subsequently allocate it to
75  * anybody else; that value will be added to the "pcap.h" in the
76  * tcpdump.org Git repository, so that a future libpcap release will
77  * include it.
78  *
79  * You should, if possible, also contribute patches to libpcap and tcpdump
80  * to handle the new encapsulation type, so that they can also be checked
81  * into the tcpdump.org Git repository and so that they will appear in
82  * future libpcap and tcpdump releases.
83  *
84  * Do *NOT* assume that any values after the largest value in this file
85  * are available; you might not have the most up-to-date version of this
86  * file, and new values after that one might have been assigned.  Also,
87  * do *NOT* use any values below 100 - those might already have been
88  * taken by one (or more!) organizations.
89  *
90  * Any platform that defines additional DLT_* codes should:
91  *
92  *	request a LINKTYPE_* code and value from tcpdump.org,
93  *	as per the above;
94  *
95  *	add, in their version of libpcap, an entry to map
96  *	those DLT_* codes to the corresponding LINKTYPE_*
97  *	code;
98  *
99  *	redefine, in their "net/bpf.h", any DLT_* values
100  *	that collide with the values used by their additional
101  *	DLT_* codes, to remove those collisions (but without
102  *	making them collide with any of the LINKTYPE_*
103  *	values equal to 50 or above; they should also avoid
104  *	defining DLT_* values that collide with those
105  *	LINKTYPE_* values, either).
106  */
107 #define LINKTYPE_NULL		DLT_NULL
108 #define LINKTYPE_ETHERNET	DLT_EN10MB	/* also for 100Mb and up */
109 #define LINKTYPE_EXP_ETHERNET	DLT_EN3MB	/* 3Mb experimental Ethernet */
110 #define LINKTYPE_AX25		DLT_AX25
111 #define LINKTYPE_PRONET		DLT_PRONET
112 #define LINKTYPE_CHAOS		DLT_CHAOS
113 #define LINKTYPE_IEEE802_5	DLT_IEEE802	/* DLT_IEEE802 is used for 802.5 Token Ring */
114 #define LINKTYPE_ARCNET_BSD	DLT_ARCNET	/* BSD-style headers */
115 #define LINKTYPE_SLIP		DLT_SLIP
116 #define LINKTYPE_PPP		DLT_PPP
117 #define LINKTYPE_FDDI		DLT_FDDI
118 
119 /*
120  * LINKTYPE_PPP is for use when there might, or might not, be an RFC 1662
121  * PPP in HDLC-like framing header (with 0xff 0x03 before the PPP protocol
122  * field) at the beginning of the packet.
123  *
124  * This is for use when there is always such a header; the address field
125  * might be 0xff, for regular PPP, or it might be an address field for Cisco
126  * point-to-point with HDLC framing as per section 4.3.1 of RFC 1547 ("Cisco
127  * HDLC").  This is, for example, what you get with NetBSD's DLT_PPP_SERIAL.
128  *
129  * We give it the same value as NetBSD's DLT_PPP_SERIAL, in the hopes that
130  * nobody else will choose a DLT_ value of 50, and so that DLT_PPP_SERIAL
131  * captures will be written out with a link type that NetBSD's tcpdump
132  * can read.
133  */
134 #define LINKTYPE_PPP_HDLC	50		/* PPP in HDLC-like framing */
135 
136 #define LINKTYPE_PPP_ETHER	51		/* NetBSD PPP-over-Ethernet */
137 
138 #define LINKTYPE_SYMANTEC_FIREWALL 99		/* Symantec Enterprise Firewall */
139 
140 /*
141  * These correspond to DLT_s that have different values on different
142  * platforms; we map between these values in capture files and
143  * the DLT_ values as returned by pcap_datalink() and passed to
144  * pcap_open_dead().
145  */
146 #define LINKTYPE_ATM_RFC1483	100		/* LLC/SNAP-encapsulated ATM */
147 #define LINKTYPE_RAW		101		/* raw IP */
148 #define LINKTYPE_SLIP_BSDOS	102		/* BSD/OS SLIP BPF header */
149 #define LINKTYPE_PPP_BSDOS	103		/* BSD/OS PPP BPF header */
150 
151 /*
152  * Values starting with 104 are used for newly-assigned link-layer
153  * header type values; for those link-layer header types, the DLT_
154  * value returned by pcap_datalink() and passed to pcap_open_dead(),
155  * and the LINKTYPE_ value that appears in capture files, are the
156  * same.
157  *
158  * LINKTYPE_MATCHING_MIN is the lowest such value; LINKTYPE_MATCHING_MAX
159  * is the highest such value.
160  */
161 #define LINKTYPE_MATCHING_MIN	104		/* lowest value in the "matching" range */
162 
163 #define LINKTYPE_C_HDLC		104		/* Cisco HDLC */
164 #define LINKTYPE_IEEE802_11	105		/* IEEE 802.11 (wireless) */
165 #define LINKTYPE_ATM_CLIP	106		/* Linux Classical IP over ATM */
166 #define LINKTYPE_FRELAY		107		/* Frame Relay */
167 #define LINKTYPE_LOOP		108		/* OpenBSD loopback */
168 #define LINKTYPE_ENC		109		/* OpenBSD IPSEC enc */
169 
170 /*
171  * These three types are reserved for future use.
172  */
173 #define LINKTYPE_LANE8023	110		/* ATM LANE + 802.3 */
174 #define LINKTYPE_HIPPI		111		/* NetBSD HIPPI */
175 #define LINKTYPE_HDLC		112		/* NetBSD HDLC framing */
176 
177 #define LINKTYPE_LINUX_SLL	113		/* Linux cooked socket capture */
178 #define LINKTYPE_LTALK		114		/* Apple LocalTalk hardware */
179 #define LINKTYPE_ECONET		115		/* Acorn Econet */
180 
181 /*
182  * Reserved for use with OpenBSD ipfilter.
183  */
184 #define LINKTYPE_IPFILTER	116
185 
186 #define LINKTYPE_PFLOG		117		/* OpenBSD DLT_PFLOG */
187 #define LINKTYPE_CISCO_IOS	118		/* For Cisco-internal use */
188 #define LINKTYPE_IEEE802_11_PRISM 119		/* 802.11 plus Prism II monitor mode radio metadata header */
189 #define LINKTYPE_IEEE802_11_AIRONET 120		/* 802.11 plus FreeBSD Aironet driver radio metadata header */
190 
191 /*
192  * Reserved for Siemens HiPath HDLC.
193  */
194 #define LINKTYPE_HHDLC		121
195 
196 #define LINKTYPE_IP_OVER_FC	122		/* RFC 2625 IP-over-Fibre Channel */
197 #define LINKTYPE_SUNATM		123		/* Solaris+SunATM */
198 
199 /*
200  * Reserved as per request from Kent Dahlgren <kent@praesum.com>
201  * for private use.
202  */
203 #define LINKTYPE_RIO		124		/* RapidIO */
204 #define LINKTYPE_PCI_EXP	125		/* PCI Express */
205 #define LINKTYPE_AURORA		126		/* Xilinx Aurora link layer */
206 
207 #define LINKTYPE_IEEE802_11_RADIOTAP 127	/* 802.11 plus radiotap radio metadata header */
208 
209 /*
210  * Reserved for the TZSP encapsulation, as per request from
211  * Chris Waters <chris.waters@networkchemistry.com>
212  * TZSP is a generic encapsulation for any other link type,
213  * which includes a means to include meta-information
214  * with the packet, e.g. signal strength and channel
215  * for 802.11 packets.
216  */
217 #define LINKTYPE_TZSP		128		/* Tazmen Sniffer Protocol */
218 
219 #define LINKTYPE_ARCNET_LINUX	129		/* Linux-style headers */
220 
221 /*
222  * Juniper-private data link types, as per request from
223  * Hannes Gredler <hannes@juniper.net>.  The corresponding
224  * DLT_s are used for passing on chassis-internal
225  * metainformation such as QOS profiles, etc..
226  */
227 #define LINKTYPE_JUNIPER_MLPPP  130
228 #define LINKTYPE_JUNIPER_MLFR   131
229 #define LINKTYPE_JUNIPER_ES     132
230 #define LINKTYPE_JUNIPER_GGSN   133
231 #define LINKTYPE_JUNIPER_MFR    134
232 #define LINKTYPE_JUNIPER_ATM2   135
233 #define LINKTYPE_JUNIPER_SERVICES 136
234 #define LINKTYPE_JUNIPER_ATM1   137
235 
236 #define LINKTYPE_APPLE_IP_OVER_IEEE1394 138	/* Apple IP-over-IEEE 1394 cooked header */
237 
238 #define LINKTYPE_MTP2_WITH_PHDR	139
239 #define LINKTYPE_MTP2		140
240 #define LINKTYPE_MTP3		141
241 #define LINKTYPE_SCCP		142
242 
243 #define LINKTYPE_DOCSIS		143		/* DOCSIS MAC frames */
244 
245 #define LINKTYPE_LINUX_IRDA	144		/* Linux-IrDA */
246 
247 /*
248  * Reserved for IBM SP switch and IBM Next Federation switch.
249  */
250 #define LINKTYPE_IBM_SP		145
251 #define LINKTYPE_IBM_SN		146
252 
253 /*
254  * Reserved for private use.  If you have some link-layer header type
255  * that you want to use within your organization, with the capture files
256  * using that link-layer header type not ever be sent outside your
257  * organization, you can use these values.
258  *
259  * No libpcap release will use these for any purpose, nor will any
260  * tcpdump release use them, either.
261  *
262  * Do *NOT* use these in capture files that you expect anybody not using
263  * your private versions of capture-file-reading tools to read; in
264  * particular, do *NOT* use them in products, otherwise you may find that
265  * people won't be able to use tcpdump, or snort, or Ethereal, or... to
266  * read capture files from your firewall/intrusion detection/traffic
267  * monitoring/etc. appliance, or whatever product uses that LINKTYPE_ value,
268  * and you may also find that the developers of those applications will
269  * not accept patches to let them read those files.
270  *
271  * Also, do not use them if somebody might send you a capture using them
272  * for *their* private type and tools using them for *your* private type
273  * would have to read them.
274  *
275  * Instead, in those cases, ask "tcpdump-workers@lists.tcpdump.org" for a
276  * new DLT_ and LINKTYPE_ value, as per the comment in pcap/bpf.h, and use
277  * the type you're given.
278  */
279 #define LINKTYPE_USER0		147
280 #define LINKTYPE_USER1		148
281 #define LINKTYPE_USER2		149
282 #define LINKTYPE_USER3		150
283 #define LINKTYPE_USER4		151
284 #define LINKTYPE_USER5		152
285 #define LINKTYPE_USER6		153
286 #define LINKTYPE_USER7		154
287 #define LINKTYPE_USER8		155
288 #define LINKTYPE_USER9		156
289 #define LINKTYPE_USER10		157
290 #define LINKTYPE_USER11		158
291 #define LINKTYPE_USER12		159
292 #define LINKTYPE_USER13		160
293 #define LINKTYPE_USER14		161
294 #define LINKTYPE_USER15		162
295 
296 /*
297  * For future use with 802.11 captures - defined by AbsoluteValue
298  * Systems to store a number of bits of link-layer information
299  * including radio information:
300  *
301  *	http://www.shaftnet.org/~pizza/software/capturefrm.txt
302  */
303 #define LINKTYPE_IEEE802_11_AVS	163	/* 802.11 plus AVS radio metadata header */
304 
305 /*
306  * Juniper-private data link type, as per request from
307  * Hannes Gredler <hannes@juniper.net>.  The corresponding
308  * DLT_s are used for passing on chassis-internal
309  * metainformation such as QOS profiles, etc..
310  */
311 #define LINKTYPE_JUNIPER_MONITOR 164
312 
313 /*
314  * BACnet MS/TP frames.
315  */
316 #define LINKTYPE_BACNET_MS_TP	165
317 
318 /*
319  * Another PPP variant as per request from Karsten Keil <kkeil@suse.de>.
320  *
321  * This is used in some OSes to allow a kernel socket filter to distinguish
322  * between incoming and outgoing packets, on a socket intended to
323  * supply pppd with outgoing packets so it can do dial-on-demand and
324  * hangup-on-lack-of-demand; incoming packets are filtered out so they
325  * don't cause pppd to hold the connection up (you don't want random
326  * input packets such as port scans, packets from old lost connections,
327  * etc. to force the connection to stay up).
328  *
329  * The first byte of the PPP header (0xff03) is modified to accomodate
330  * the direction - 0x00 = IN, 0x01 = OUT.
331  */
332 #define LINKTYPE_PPP_PPPD	166
333 
334 /*
335  * Juniper-private data link type, as per request from
336  * Hannes Gredler <hannes@juniper.net>.  The DLT_s are used
337  * for passing on chassis-internal metainformation such as
338  * QOS profiles, cookies, etc..
339  */
340 #define LINKTYPE_JUNIPER_PPPOE     167
341 #define LINKTYPE_JUNIPER_PPPOE_ATM 168
342 
343 #define LINKTYPE_GPRS_LLC	169		/* GPRS LLC */
344 #define LINKTYPE_GPF_T		170		/* GPF-T (ITU-T G.7041/Y.1303) */
345 #define LINKTYPE_GPF_F		171		/* GPF-F (ITU-T G.7041/Y.1303) */
346 
347 /*
348  * Requested by Oolan Zimmer <oz@gcom.com> for use in Gcom's T1/E1 line
349  * monitoring equipment.
350  */
351 #define LINKTYPE_GCOM_T1E1	172
352 #define LINKTYPE_GCOM_SERIAL	173
353 
354 /*
355  * Juniper-private data link type, as per request from
356  * Hannes Gredler <hannes@juniper.net>.  The DLT_ is used
357  * for internal communication to Physical Interface Cards (PIC)
358  */
359 #define LINKTYPE_JUNIPER_PIC_PEER    174
360 
361 /*
362  * Link types requested by Gregor Maier <gregor@endace.com> of Endace
363  * Measurement Systems.  They add an ERF header (see
364  * http://www.endace.com/support/EndaceRecordFormat.pdf) in front of
365  * the link-layer header.
366  */
367 #define LINKTYPE_ERF_ETH	175	/* Ethernet */
368 #define LINKTYPE_ERF_POS	176	/* Packet-over-SONET */
369 
370 /*
371  * Requested by Daniele Orlandi <daniele@orlandi.com> for raw LAPD
372  * for vISDN (http://www.orlandi.com/visdn/).  Its link-layer header
373  * includes additional information before the LAPD header, so it's
374  * not necessarily a generic LAPD header.
375  */
376 #define LINKTYPE_LINUX_LAPD	177
377 
378 /*
379  * Juniper-private data link type, as per request from
380  * Hannes Gredler <hannes@juniper.net>.
381  * The Link Types are used for prepending meta-information
382  * like interface index, interface name
383  * before standard Ethernet, PPP, Frelay & C-HDLC Frames
384  */
385 #define LINKTYPE_JUNIPER_ETHER  178
386 #define LINKTYPE_JUNIPER_PPP    179
387 #define LINKTYPE_JUNIPER_FRELAY 180
388 #define LINKTYPE_JUNIPER_CHDLC  181
389 
390 /*
391  * Multi Link Frame Relay (FRF.16)
392  */
393 #define LINKTYPE_MFR            182
394 
395 /*
396  * Juniper-private data link type, as per request from
397  * Hannes Gredler <hannes@juniper.net>.
398  * The DLT_ is used for internal communication with a
399  * voice Adapter Card (PIC)
400  */
401 #define LINKTYPE_JUNIPER_VP     183
402 
403 /*
404  * Arinc 429 frames.
405  * DLT_ requested by Gianluca Varenni <gianluca.varenni@cacetech.com>.
406  * Every frame contains a 32bit A429 label.
407  * More documentation on Arinc 429 can be found at
408  * http://www.condoreng.com/support/downloads/tutorials/ARINCTutorial.pdf
409  */
410 #define LINKTYPE_A429           184
411 
412 /*
413  * Arinc 653 Interpartition Communication messages.
414  * DLT_ requested by Gianluca Varenni <gianluca.varenni@cacetech.com>.
415  * Please refer to the A653-1 standard for more information.
416  */
417 #define LINKTYPE_A653_ICM       185
418 
419 /*
420  * This used to be "USB packets, beginning with a USB setup header;
421  * requested by Paolo Abeni <paolo.abeni@email.it>."
422  *
423  * However, that header didn't work all that well - it left out some
424  * useful information - and was abandoned in favor of the DLT_USB_LINUX
425  * header.
426  *
427  * This is now used by FreeBSD for its BPF taps for USB; that has its
428  * own headers.  So it is written, so it is done.
429  */
430 #define LINKTYPE_USB_FREEBSD	186
431 
432 /*
433  * Bluetooth HCI UART transport layer (part H:4); requested by
434  * Paolo Abeni.
435  */
436 #define LINKTYPE_BLUETOOTH_HCI_H4	187
437 
438 /*
439  * IEEE 802.16 MAC Common Part Sublayer; requested by Maria Cruz
440  * <cruz_petagay@bah.com>.
441  */
442 #define LINKTYPE_IEEE802_16_MAC_CPS	188
443 
444 /*
445  * USB packets, beginning with a Linux USB header; requested by
446  * Paolo Abeni <paolo.abeni@email.it>.
447  */
448 #define LINKTYPE_USB_LINUX		189
449 
450 /*
451  * Controller Area Network (CAN) v. 2.0B packets.
452  * DLT_ requested by Gianluca Varenni <gianluca.varenni@cacetech.com>.
453  * Used to dump CAN packets coming from a CAN Vector board.
454  * More documentation on the CAN v2.0B frames can be found at
455  * http://www.can-cia.org/downloads/?269
456  */
457 #define LINKTYPE_CAN20B         190
458 
459 /*
460  * IEEE 802.15.4, with address fields padded, as is done by Linux
461  * drivers; requested by Juergen Schimmer.
462  */
463 #define LINKTYPE_IEEE802_15_4_LINUX	191
464 
465 /*
466  * Per Packet Information encapsulated packets.
467  * LINKTYPE_ requested by Gianluca Varenni <gianluca.varenni@cacetech.com>.
468  */
469 #define LINKTYPE_PPI			192
470 
471 /*
472  * Header for 802.16 MAC Common Part Sublayer plus a radiotap radio header;
473  * requested by Charles Clancy.
474  */
475 #define LINKTYPE_IEEE802_16_MAC_CPS_RADIO	193
476 
477 /*
478  * Juniper-private data link type, as per request from
479  * Hannes Gredler <hannes@juniper.net>.
480  * The DLT_ is used for internal communication with a
481  * integrated service module (ISM).
482  */
483 #define LINKTYPE_JUNIPER_ISM    194
484 
485 /*
486  * IEEE 802.15.4, exactly as it appears in the spec (no padding, no
487  * nothing), and with the FCS at the end of the frame; requested by
488  * Mikko Saarnivala <mikko.saarnivala@sensinode.com>.
489  *
490  * This should only be used if the FCS is present at the end of the
491  * frame; if the frame has no FCS, DLT_IEEE802_15_4_NOFCS should be
492  * used.
493  */
494 #define LINKTYPE_IEEE802_15_4_WITHFCS	195
495 
496 /*
497  * Various link-layer types, with a pseudo-header, for SITA
498  * (http://www.sita.aero/); requested by Fulko Hew (fulko.hew@gmail.com).
499  */
500 #define LINKTYPE_SITA		196
501 
502 /*
503  * Various link-layer types, with a pseudo-header, for Endace DAG cards;
504  * encapsulates Endace ERF records.  Requested by Stephen Donnelly
505  * <stephen@endace.com>.
506  */
507 #define LINKTYPE_ERF		197
508 
509 /*
510  * Special header prepended to Ethernet packets when capturing from a
511  * u10 Networks board.  Requested by Phil Mulholland
512  * <phil@u10networks.com>.
513  */
514 #define LINKTYPE_RAIF1		198
515 
516 /*
517  * IPMB packet for IPMI, beginning with the I2C slave address, followed
518  * by the netFn and LUN, etc..  Requested by Chanthy Toeung
519  * <chanthy.toeung@ca.kontron.com>.
520  */
521 #define LINKTYPE_IPMB		199
522 
523 /*
524  * Juniper-private data link type, as per request from
525  * Hannes Gredler <hannes@juniper.net>.
526  * The DLT_ is used for capturing data on a secure tunnel interface.
527  */
528 #define LINKTYPE_JUNIPER_ST     200
529 
530 /*
531  * Bluetooth HCI UART transport layer (part H:4), with pseudo-header
532  * that includes direction information; requested by Paolo Abeni.
533  */
534 #define LINKTYPE_BLUETOOTH_HCI_H4_WITH_PHDR	201
535 
536 /*
537  * AX.25 packet with a 1-byte KISS header; see
538  *
539  *	http://www.ax25.net/kiss.htm
540  *
541  * as per Richard Stearn <richard@rns-stearn.demon.co.uk>.
542  */
543 #define LINKTYPE_AX25_KISS	202
544 
545 /*
546  * LAPD packets from an ISDN channel, starting with the address field,
547  * with no pseudo-header.
548  * Requested by Varuna De Silva <varunax@gmail.com>.
549  */
550 #define LINKTYPE_LAPD		203
551 
552 /*
553  * Variants of various link-layer headers, with a one-byte direction
554  * pseudo-header prepended - zero means "received by this host",
555  * non-zero (any non-zero value) means "sent by this host" - as per
556  * Will Barker <w.barker@zen.co.uk>.
557  */
558 #define LINKTYPE_PPP_WITH_DIR	204	/* PPP */
559 #define LINKTYPE_C_HDLC_WITH_DIR 205	/* Cisco HDLC */
560 #define LINKTYPE_FRELAY_WITH_DIR 206	/* Frame Relay */
561 #define LINKTYPE_LAPB_WITH_DIR	207	/* LAPB */
562 
563 /*
564  * 208 is reserved for an as-yet-unspecified proprietary link-layer
565  * type, as requested by Will Barker.
566  */
567 
568 /*
569  * IPMB with a Linux-specific pseudo-header; as requested by Alexey Neyman
570  * <avn@pigeonpoint.com>.
571  */
572 #define LINKTYPE_IPMB_LINUX	209
573 
574 /*
575  * FlexRay automotive bus - http://www.flexray.com/ - as requested
576  * by Hannes Kaelber <hannes.kaelber@x2e.de>.
577  */
578 #define LINKTYPE_FLEXRAY	210
579 
580 /*
581  * Media Oriented Systems Transport (MOST) bus for multimedia
582  * transport - http://www.mostcooperation.com/ - as requested
583  * by Hannes Kaelber <hannes.kaelber@x2e.de>.
584  */
585 #define LINKTYPE_MOST		211
586 
587 /*
588  * Local Interconnect Network (LIN) bus for vehicle networks -
589  * http://www.lin-subbus.org/ - as requested by Hannes Kaelber
590  * <hannes.kaelber@x2e.de>.
591  */
592 #define LINKTYPE_LIN		212
593 
594 /*
595  * X2E-private data link type used for serial line capture,
596  * as requested by Hannes Kaelber <hannes.kaelber@x2e.de>.
597  */
598 #define LINKTYPE_X2E_SERIAL	213
599 
600 /*
601  * X2E-private data link type used for the Xoraya data logger
602  * family, as requested by Hannes Kaelber <hannes.kaelber@x2e.de>.
603  */
604 #define LINKTYPE_X2E_XORAYA	214
605 
606 /*
607  * IEEE 802.15.4, exactly as it appears in the spec (no padding, no
608  * nothing), but with the PHY-level data for non-ASK PHYs (4 octets
609  * of 0 as preamble, one octet of SFD, one octet of frame length+
610  * reserved bit, and then the MAC-layer data, starting with the
611  * frame control field).
612  *
613  * Requested by Max Filippov <jcmvbkbc@gmail.com>.
614  */
615 #define LINKTYPE_IEEE802_15_4_NONASK_PHY	215
616 
617 /*
618  * David Gibson <david@gibson.dropbear.id.au> requested this for
619  * captures from the Linux kernel /dev/input/eventN devices. This
620  * is used to communicate keystrokes and mouse movements from the
621  * Linux kernel to display systems, such as Xorg.
622  */
623 #define LINKTYPE_LINUX_EVDEV	216
624 
625 /*
626  * GSM Um and Abis interfaces, preceded by a "gsmtap" header.
627  *
628  * Requested by Harald Welte <laforge@gnumonks.org>.
629  */
630 #define LINKTYPE_GSMTAP_UM	217
631 #define LINKTYPE_GSMTAP_ABIS	218
632 
633 /*
634  * MPLS, with an MPLS label as the link-layer header.
635  * Requested by Michele Marchetto <michele@openbsd.org> on behalf
636  * of OpenBSD.
637  */
638 #define LINKTYPE_MPLS		219
639 
640 /*
641  * USB packets, beginning with a Linux USB header, with the USB header
642  * padded to 64 bytes; required for memory-mapped access.
643  */
644 #define LINKTYPE_USB_LINUX_MMAPPED		220
645 
646 /*
647  * DECT packets, with a pseudo-header; requested by
648  * Matthias Wenzel <tcpdump@mazzoo.de>.
649  */
650 #define LINKTYPE_DECT		221
651 
652 /*
653  * From: "Lidwa, Eric (GSFC-582.0)[SGT INC]" <eric.lidwa-1@nasa.gov>
654  * Date: Mon, 11 May 2009 11:18:30 -0500
655  *
656  * DLT_AOS. We need it for AOS Space Data Link Protocol.
657  *   I have already written dissectors for but need an OK from
658  *   legal before I can submit a patch.
659  *
660  */
661 #define LINKTYPE_AOS		222
662 
663 /*
664  * Wireless HART (Highway Addressable Remote Transducer)
665  * From the HART Communication Foundation
666  * IES/PAS 62591
667  *
668  * Requested by Sam Roberts <vieuxtech@gmail.com>.
669  */
670 #define LINKTYPE_WIHART		223
671 
672 /*
673  * Fibre Channel FC-2 frames, beginning with a Frame_Header.
674  * Requested by Kahou Lei <kahou82@gmail.com>.
675  */
676 #define LINKTYPE_FC_2		224
677 
678 /*
679  * Fibre Channel FC-2 frames, beginning with an encoding of the
680  * SOF, and ending with an encoding of the EOF.
681  *
682  * The encodings represent the frame delimiters as 4-byte sequences
683  * representing the corresponding ordered sets, with K28.5
684  * represented as 0xBC, and the D symbols as the corresponding
685  * byte values; for example, SOFi2, which is K28.5 - D21.5 - D1.2 - D21.2,
686  * is represented as 0xBC 0xB5 0x55 0x55.
687  *
688  * Requested by Kahou Lei <kahou82@gmail.com>.
689  */
690 #define LINKTYPE_FC_2_WITH_FRAME_DELIMS		225
691 
692 /*
693  * Solaris ipnet pseudo-header; requested by Darren Reed <Darren.Reed@Sun.COM>.
694  *
695  * The pseudo-header starts with a one-byte version number; for version 2,
696  * the pseudo-header is:
697  *
698  * struct dl_ipnetinfo {
699  *     uint8_t   dli_version;
700  *     uint8_t   dli_family;
701  *     uint16_t  dli_htype;
702  *     uint32_t  dli_pktlen;
703  *     uint32_t  dli_ifindex;
704  *     uint32_t  dli_grifindex;
705  *     uint32_t  dli_zsrc;
706  *     uint32_t  dli_zdst;
707  * };
708  *
709  * dli_version is 2 for the current version of the pseudo-header.
710  *
711  * dli_family is a Solaris address family value, so it's 2 for IPv4
712  * and 26 for IPv6.
713  *
714  * dli_htype is a "hook type" - 0 for incoming packets, 1 for outgoing
715  * packets, and 2 for packets arriving from another zone on the same
716  * machine.
717  *
718  * dli_pktlen is the length of the packet data following the pseudo-header
719  * (so the captured length minus dli_pktlen is the length of the
720  * pseudo-header, assuming the entire pseudo-header was captured).
721  *
722  * dli_ifindex is the interface index of the interface on which the
723  * packet arrived.
724  *
725  * dli_grifindex is the group interface index number (for IPMP interfaces).
726  *
727  * dli_zsrc is the zone identifier for the source of the packet.
728  *
729  * dli_zdst is the zone identifier for the destination of the packet.
730  *
731  * A zone number of 0 is the global zone; a zone number of 0xffffffff
732  * means that the packet arrived from another host on the network, not
733  * from another zone on the same machine.
734  *
735  * An IPv4 or IPv6 datagram follows the pseudo-header; dli_family indicates
736  * which of those it is.
737  */
738 #define LINKTYPE_IPNET		226
739 
740 /*
741  * CAN (Controller Area Network) frames, with a pseudo-header as supplied
742  * by Linux SocketCAN, and with multi-byte numerical fields in that header
743  * in big-endian byte order.
744  *
745  * See Documentation/networking/can.txt in the Linux source.
746  *
747  * Requested by Felix Obenhuber <felix@obenhuber.de>.
748  */
749 #define LINKTYPE_CAN_SOCKETCAN	227
750 
751 /*
752  * Raw IPv4/IPv6; different from DLT_RAW in that the DLT_ value specifies
753  * whether it's v4 or v6.  Requested by Darren Reed <Darren.Reed@Sun.COM>.
754  */
755 #define LINKTYPE_IPV4		228
756 #define LINKTYPE_IPV6		229
757 
758 /*
759  * IEEE 802.15.4, exactly as it appears in the spec (no padding, no
760  * nothing), and with no FCS at the end of the frame; requested by
761  * Jon Smirl <jonsmirl@gmail.com>.
762  */
763 #define LINKTYPE_IEEE802_15_4_NOFCS		230
764 
765 /*
766  * Raw D-Bus:
767  *
768  *	http://www.freedesktop.org/wiki/Software/dbus
769  *
770  * messages:
771  *
772  *	http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-messages
773  *
774  * starting with the endianness flag, followed by the message type, etc.,
775  * but without the authentication handshake before the message sequence:
776  *
777  *	http://dbus.freedesktop.org/doc/dbus-specification.html#auth-protocol
778  *
779  * Requested by Martin Vidner <martin@vidner.net>.
780  */
781 #define LINKTYPE_DBUS		231
782 
783 /*
784  * Juniper-private data link type, as per request from
785  * Hannes Gredler <hannes@juniper.net>.
786  */
787 #define LINKTYPE_JUNIPER_VS			232
788 #define LINKTYPE_JUNIPER_SRX_E2E		233
789 #define LINKTYPE_JUNIPER_FIBRECHANNEL		234
790 
791 /*
792  * DVB-CI (DVB Common Interface for communication between a PC Card
793  * module and a DVB receiver).  See
794  *
795  *	http://www.kaiser.cx/pcap-dvbci.html
796  *
797  * for the specification.
798  *
799  * Requested by Martin Kaiser <martin@kaiser.cx>.
800  */
801 #define LINKTYPE_DVB_CI		235
802 
803 /*
804  * Variant of 3GPP TS 27.010 multiplexing protocol.  Requested
805  * by Hans-Christoph Schemmel <hans-christoph.schemmel@cinterion.com>.
806  */
807 #define LINKTYPE_MUX27010	236
808 
809 /*
810  * STANAG 5066 D_PDUs.  Requested by M. Baris Demiray
811  * <barisdemiray@gmail.com>.
812  */
813 #define LINKTYPE_STANAG_5066_D_PDU		237
814 
815 /*
816  * Juniper-private data link type, as per request from
817  * Hannes Gredler <hannes@juniper.net>.
818  */
819 #define LINKTYPE_JUNIPER_ATM_CEMIC		238
820 
821 /*
822  * NetFilter LOG messages
823  * (payload of netlink NFNL_SUBSYS_ULOG/NFULNL_MSG_PACKET packets)
824  *
825  * Requested by Jakub Zawadzki <darkjames-ws@darkjames.pl>
826  */
827 #define LINKTYPE_NFLOG		239
828 
829 /*
830  * Hilscher Gesellschaft fuer Systemautomation mbH link-layer type
831  * for Ethernet packets with a 4-byte pseudo-header and always
832  * with the payload including the FCS, as supplied by their
833  * netANALYZER hardware and software.
834  *
835  * Requested by Holger P. Frommer <HPfrommer@hilscher.com>
836  */
837 #define LINKTYPE_NETANALYZER	240
838 
839 /*
840  * Hilscher Gesellschaft fuer Systemautomation mbH link-layer type
841  * for Ethernet packets with a 4-byte pseudo-header and FCS and
842  * 1 byte of SFD, as supplied by their netANALYZER hardware and
843  * software.
844  *
845  * Requested by Holger P. Frommer <HPfrommer@hilscher.com>
846  */
847 #define LINKTYPE_NETANALYZER_TRANSPARENT	241
848 
849 /*
850  * IP-over-InfiniBand, as specified by RFC 4391.
851  *
852  * Requested by Petr Sumbera <petr.sumbera@oracle.com>.
853  */
854 #define LINKTYPE_IPOIB		242
855 
856 /*
857  * MPEG-2 transport stream (ISO 13818-1/ITU-T H.222.0).
858  *
859  * Requested by Guy Martin <gmsoft@tuxicoman.be>.
860  */
861 #define LINKTYPE_MPEG_2_TS	243
862 
863 /*
864  * ng4T GmbH's UMTS Iub/Iur-over-ATM and Iub/Iur-over-IP format as
865  * used by their ng40 protocol tester.
866  *
867  * Requested by Jens Grimmer <jens.grimmer@ng4t.com>.
868  */
869 #define LINKTYPE_NG40		244
870 
871 /*
872  * Pseudo-header giving adapter number and flags, followed by an NFC
873  * (Near-Field Communications) Logical Link Control Protocol (LLCP) PDU,
874  * as specified by NFC Forum Logical Link Control Protocol Technical
875  * Specification LLCP 1.1.
876  *
877  * Requested by Mike Wakerly <mikey@google.com>.
878  */
879 #define LINKTYPE_NFC_LLCP	245
880 
881 /*
882  * pfsync output; DLT_PFSYNC is 18, which collides with DLT_CIP in
883  * SuSE 6.3, on OpenBSD, NetBSD, DragonFly BSD, and macOS, and
884  * is 121, which collides with DLT_HHDLC, in FreeBSD.  We pick a
885  * shiny new link-layer header type value that doesn't collide with
886  * anything, in the hopes that future pfsync savefiles, if any,
887  * won't require special hacks to distinguish from other savefiles.
888  *
889  */
890 #define LINKTYPE_PFSYNC		246
891 
892 /*
893  * Raw InfiniBand packets, starting with the Local Routing Header.
894  *
895  * Requested by Oren Kladnitsky <orenk@mellanox.com>.
896  */
897 #define LINKTYPE_INFINIBAND	247
898 
899 /*
900  * SCTP, with no lower-level protocols (i.e., no IPv4 or IPv6).
901  *
902  * Requested by Michael Tuexen <Michael.Tuexen@lurchi.franken.de>.
903  */
904 #define LINKTYPE_SCTP		248
905 
906 /*
907  * USB packets, beginning with a USBPcap header.
908  *
909  * Requested by Tomasz Mon <desowin@gmail.com>
910  */
911 #define LINKTYPE_USBPCAP	249
912 
913 /*
914  * Schweitzer Engineering Laboratories "RTAC" product serial-line
915  * packets.
916  *
917  * Requested by Chris Bontje <chris_bontje@selinc.com>.
918  */
919 #define DLT_RTAC_SERIAL		250
920 
921 /*
922  * Bluetooth Low Energy air interface link-layer packets.
923  *
924  * Requested by Mike Kershaw <dragorn@kismetwireless.net>.
925  */
926 #define LINKTYPE_BLUETOOTH_LE_LL	251
927 
928 /*
929  * Link-layer header type for upper-protocol layer PDU saves from wireshark.
930  *
931  * the actual contents are determined by two TAGs stored with each
932  * packet:
933  *   EXP_PDU_TAG_LINKTYPE          the link type (LINKTYPE_ value) of the
934  *				   original packet.
935  *
936  *   EXP_PDU_TAG_PROTO_NAME        the name of the wireshark dissector
937  * 				   that can make sense of the data stored.
938  */
939 #define LINKTYPE_WIRESHARK_UPPER_PDU	252
940 
941 /*
942  * Link-layer header type for the netlink protocol (nlmon devices).
943  */
944 #define LINKTYPE_NETLINK		253
945 
946 /*
947  * Bluetooth Linux Monitor headers for the BlueZ stack.
948  */
949 #define LINKTYPE_BLUETOOTH_LINUX_MONITOR	254
950 
951 /*
952  * Bluetooth Basic Rate/Enhanced Data Rate baseband packets, as
953  * captured by Ubertooth.
954  */
955 #define LINKTYPE_BLUETOOTH_BREDR_BB	255
956 
957 /*
958  * Bluetooth Low Energy link layer packets, as captured by Ubertooth.
959  */
960 #define LINKTYPE_BLUETOOTH_LE_LL_WITH_PHDR	256
961 
962 /*
963  * PROFIBUS data link layer.
964  */
965 #define LINKTYPE_PROFIBUS_DL		257
966 
967 /*
968  * Apple's DLT_PKTAP headers.
969  *
970  * Sadly, the folks at Apple either had no clue that the DLT_USERn values
971  * are for internal use within an organization and partners only, and
972  * didn't know that the right way to get a link-layer header type is to
973  * ask tcpdump.org for one, or knew and didn't care, so they just
974  * used DLT_USER2, which causes problems for everything except for
975  * their version of tcpdump.
976  *
977  * So I'll just give them one; hopefully this will show up in a
978  * libpcap release in time for them to get this into 10.10 Big Sur
979  * or whatever Mavericks' successor is called.  LINKTYPE_PKTAP
980  * will be 258 *even on macOS*; that is *intentional*, so that
981  * PKTAP files look the same on *all* OSes (different OSes can have
982  * different numerical values for a given DLT_, but *MUST NOT* have
983  * different values for what goes in a file, as files can be moved
984  * between OSes!).
985  */
986 #define LINKTYPE_PKTAP		258
987 
988 /*
989  * Ethernet packets preceded by a header giving the last 6 octets
990  * of the preamble specified by 802.3-2012 Clause 65, section
991  * 65.1.3.2 "Transmit".
992  */
993 #define LINKTYPE_EPON		259
994 
995 /*
996  * IPMI trace packets, as specified by Table 3-20 "Trace Data Block Format"
997  * in the PICMG HPM.2 specification.
998  */
999 #define LINKTYPE_IPMI_HPM_2	260
1000 
1001 /*
1002  * per  Joshua Wright <jwright@hasborg.com>, formats for Zwave captures.
1003  */
1004 #define LINKTYPE_ZWAVE_R1_R2	261
1005 #define LINKTYPE_ZWAVE_R3	262
1006 
1007 /*
1008  * per Steve Karg <skarg@users.sourceforge.net>, formats for Wattstopper
1009  * Digital Lighting Management room bus serial protocol captures.
1010  */
1011 #define LINKTYPE_WATTSTOPPER_DLM 263
1012 
1013 /*
1014  * ISO 14443 contactless smart card messages.
1015  */
1016 #define LINKTYPE_ISO_14443      264
1017 
1018 /*
1019  * Radio data system (RDS) groups.  IEC 62106.
1020  * Per Jonathan Brucker <jonathan.brucke@gmail.com>.
1021  */
1022 #define LINKTYPE_RDS		265
1023 
1024 /*
1025  * USB packets, beginning with a Darwin (macOS, etc.) header.
1026  */
1027 #define LINKTYPE_USB_DARWIN	266
1028 
1029 /*
1030  * OpenBSD DLT_OPENFLOW.
1031  */
1032 #define LINKTYPE_OPENFLOW	267
1033 
1034 /*
1035  * SDLC frames containing SNA PDUs.
1036  */
1037 #define LINKTYPE_SDLC		268
1038 
1039 /*
1040  * per "Selvig, Bjorn" <b.selvig@ti.com> used for
1041  * TI protocol sniffer.
1042  */
1043 #define LINKTYPE_TI_LLN_SNIFFER	269
1044 
1045 /*
1046  * per: Erik de Jong <erikdejong at gmail.com> for
1047  *   https://github.com/eriknl/LoRaTap/releases/tag/v0.1
1048  */
1049 #define LINKTYPE_LORATAP        270
1050 
1051 /*
1052  * per: Stefanha at gmail.com for
1053  *   http://lists.sandelman.ca/pipermail/tcpdump-workers/2017-May/000772.html
1054  * and: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/vsockmon.h
1055  * for: http://qemu-project.org/Features/VirtioVsock
1056  */
1057 #define LINKTYPE_VSOCK          271
1058 
1059 /*
1060  * Nordic Semiconductor Bluetooth LE sniffer.
1061  */
1062 #define LINKTYPE_NORDIC_BLE	272
1063 
1064 /*
1065  * Excentis DOCSIS 3.1 RF sniffer (XRA-31)
1066  *   per: bruno.verstuyft at excentis.com
1067  *        http://www.xra31.com/xra-header
1068  */
1069 #define LINKTYPE_DOCSIS31_XRA31	273
1070 
1071 /*
1072  * mPackets, as specified by IEEE 802.3br Figure 99-4, starting
1073  * with the preamble and always ending with a CRC field.
1074  */
1075 #define LINKTYPE_ETHERNET_MPACKET	274
1076 
1077 /*
1078  * DisplayPort AUX channel monitoring data as specified by VESA
1079  * DisplayPort(DP) Standard preceeded by a pseudo-header.
1080  *    per dirk.eibach at gdsys.cc
1081  */
1082 #define LINKTYPE_DISPLAYPORT_AUX	275
1083 
1084 #define LINKTYPE_MATCHING_MAX	275		/* highest value in the "matching" range */
1085 
1086 static struct linktype_map {
1087 	int	dlt;
1088 	int	linktype;
1089 } map[] = {
1090 	/*
1091 	 * These DLT_* codes have LINKTYPE_* codes with values identical
1092 	 * to the values of the corresponding DLT_* code.
1093 	 */
1094 	{ DLT_NULL,		LINKTYPE_NULL },
1095 	{ DLT_EN10MB,		LINKTYPE_ETHERNET },
1096 	{ DLT_EN3MB,		LINKTYPE_EXP_ETHERNET },
1097 	{ DLT_AX25,		LINKTYPE_AX25 },
1098 	{ DLT_PRONET,		LINKTYPE_PRONET },
1099 	{ DLT_CHAOS,		LINKTYPE_CHAOS },
1100 	{ DLT_IEEE802,		LINKTYPE_IEEE802_5 },
1101 	{ DLT_ARCNET,		LINKTYPE_ARCNET_BSD },
1102 	{ DLT_SLIP,		LINKTYPE_SLIP },
1103 	{ DLT_PPP,		LINKTYPE_PPP },
1104 	{ DLT_FDDI,	 	LINKTYPE_FDDI },
1105 	{ DLT_SYMANTEC_FIREWALL, LINKTYPE_SYMANTEC_FIREWALL },
1106 
1107 	/*
1108 	 * These DLT_* codes have different values on different
1109 	 * platforms; we map them to LINKTYPE_* codes that
1110 	 * have values that should never be equal to any DLT_*
1111 	 * code.
1112 	 */
1113 #ifdef DLT_FR
1114 	/* BSD/OS Frame Relay */
1115 	{ DLT_FR,		LINKTYPE_FRELAY },
1116 #endif
1117 
1118 	{ DLT_ATM_RFC1483, 	LINKTYPE_ATM_RFC1483 },
1119 	{ DLT_RAW,		LINKTYPE_RAW },
1120 	{ DLT_SLIP_BSDOS,	LINKTYPE_SLIP_BSDOS },
1121 	{ DLT_PPP_BSDOS,	LINKTYPE_PPP_BSDOS },
1122 
1123 	/* BSD/OS Cisco HDLC */
1124 	{ DLT_C_HDLC,		LINKTYPE_C_HDLC },
1125 
1126 	/*
1127 	 * These DLT_* codes are not on all platforms, but, so far,
1128 	 * there don't appear to be any platforms that define
1129 	 * other codes with those values; we map them to
1130 	 * different LINKTYPE_* values anyway, just in case.
1131 	 */
1132 
1133 	/* Linux ATM Classical IP */
1134 	{ DLT_ATM_CLIP,		LINKTYPE_ATM_CLIP },
1135 
1136 	/* NetBSD sync/async serial PPP (or Cisco HDLC) */
1137 	{ DLT_PPP_SERIAL,	LINKTYPE_PPP_HDLC },
1138 
1139 	/* NetBSD PPP over Ethernet */
1140 	{ DLT_PPP_ETHER,	LINKTYPE_PPP_ETHER },
1141 
1142 	/*
1143 	 * All LINKTYPE_ values between LINKTYPE_MATCHING_MIN
1144 	 * and LINKTYPE_MATCHING_MAX are mapped to identical
1145 	 * DLT_ values.
1146 	 */
1147 
1148 	{ -1,			-1 }
1149 };
1150 
1151 int
1152 dlt_to_linktype(int dlt)
1153 {
1154 	int i;
1155 
1156 	/*
1157 	 * DLTs that, on some platforms, have values in the matching range
1158 	 * but that *don't* have the same value as the corresponding
1159 	 * LINKTYPE because, for some reason, not all OSes have the
1160 	 * same value for that DLT (note that the DLT's value might be
1161 	 * outside the matching range on some of those OSes).
1162 	 */
1163 	if (dlt == DLT_PFSYNC)
1164 		return (LINKTYPE_PFSYNC);
1165 	if (dlt == DLT_PKTAP)
1166 		return (LINKTYPE_PKTAP);
1167 
1168 	/*
1169 	 * For all other values in the matching range, the DLT
1170 	 * value is the same as the LINKTYPE value.
1171 	 */
1172 	if (dlt >= DLT_MATCHING_MIN && dlt <= DLT_MATCHING_MAX)
1173 		return (dlt);
1174 
1175 	/*
1176 	 * Map the values outside that range.
1177 	 */
1178 	for (i = 0; map[i].dlt != -1; i++) {
1179 		if (map[i].dlt == dlt)
1180 			return (map[i].linktype);
1181 	}
1182 
1183 	/*
1184 	 * If we don't have a mapping for this DLT, return an
1185 	 * error; that means that this is a value with no corresponding
1186 	 * LINKTYPE, and we need to assign one.
1187 	 */
1188 	return (-1);
1189 }
1190 
1191 int
1192 linktype_to_dlt(int linktype)
1193 {
1194 	int i;
1195 
1196 	/*
1197 	 * LINKTYPEs in the matching range that *don't*
1198 	 * have the same value as the corresponding DLTs
1199 	 * because, for some reason, not all OSes have the
1200 	 * same value for that DLT.
1201 	 */
1202 	if (linktype == LINKTYPE_PFSYNC)
1203 		return (DLT_PFSYNC);
1204 	if (linktype == LINKTYPE_PKTAP)
1205 		return (DLT_PKTAP);
1206 
1207 	/*
1208 	 * For all other values in the matching range, the LINKTYPE
1209 	 * value is the same as the DLT value.
1210 	 */
1211 	if (linktype >= LINKTYPE_MATCHING_MIN &&
1212 	    linktype <= LINKTYPE_MATCHING_MAX)
1213 		return (linktype);
1214 
1215 	/*
1216 	 * Map the values outside that range.
1217 	 */
1218 	for (i = 0; map[i].linktype != -1; i++) {
1219 		if (map[i].linktype == linktype)
1220 			return (map[i].dlt);
1221 	}
1222 
1223 	/*
1224 	 * If we don't have an entry for this LINKTYPE, return
1225 	 * the link type value; it may be a DLT from an older
1226 	 * version of libpcap.
1227 	 */
1228 	return linktype;
1229 }
1230 
1231 /*
1232  * Return the maximum snapshot length for a given DLT_ value.
1233  *
1234  * For most link-layer types, we use MAXIMUM_SNAPLEN, but for DLT_DBUS,
1235  * the maximum is 134217728, as per
1236  *
1237  *    https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-messages
1238  */
1239 u_int
1240 max_snaplen_for_dlt(int dlt)
1241 {
1242 	if (dlt == DLT_DBUS)
1243 		return 134217728;
1244 	else
1245 		return MAXIMUM_SNAPLEN;
1246 }
1247 
1248 /*
1249  * DLT_LINUX_SLL packets with a protocol type of LINUX_SLL_P_CAN or
1250  * LINUX_SLL_P_CANFD have SocketCAN headers in front of the payload,
1251  * with the CAN ID being in host byte order.
1252  *
1253  * When reading a DLT_LINUX_SLL capture file, we need to check for those
1254  * packets and convert the CAN ID from the byte order of the host that
1255  * wrote the file to this host's byte order.
1256  */
1257 static void
1258 swap_linux_sll_header(const struct pcap_pkthdr *hdr, u_char *buf)
1259 {
1260 	u_int caplen = hdr->caplen;
1261 	u_int length = hdr->len;
1262 	struct sll_header *shdr = (struct sll_header *)buf;
1263 	uint16_t protocol;
1264 	pcap_can_socketcan_hdr *chdr;
1265 
1266 	if (caplen < (u_int) sizeof(struct sll_header) ||
1267 	    length < (u_int) sizeof(struct sll_header)) {
1268 		/* Not enough data to have the protocol field */
1269 		return;
1270 	}
1271 
1272 	protocol = EXTRACT_16BITS(&shdr->sll_protocol);
1273 	if (protocol != LINUX_SLL_P_CAN && protocol != LINUX_SLL_P_CANFD)
1274 		return;
1275 
1276 	/*
1277 	 * SocketCAN packet; fix up the packet's header.
1278 	 */
1279 	chdr = (pcap_can_socketcan_hdr *)(buf + sizeof(struct sll_header));
1280 	if (caplen < (u_int) sizeof(struct sll_header) + sizeof(chdr->can_id) ||
1281 	    length < (u_int) sizeof(struct sll_header) + sizeof(chdr->can_id)) {
1282 		/* Not enough data to have the CAN ID */
1283 		return;
1284 	}
1285 	chdr->can_id = SWAPLONG(chdr->can_id);
1286 }
1287 
1288 /*
1289  * The DLT_USB_LINUX and DLT_USB_LINUX_MMAPPED headers are in host
1290  * byte order when capturing (it's supplied directly from a
1291  * memory-mapped buffer shared by the kernel).
1292  *
1293  * When reading a DLT_USB_LINUX or DLT_USB_LINUX_MMAPPED capture file,
1294  * we need to convert it from the byte order of the host that wrote
1295  * the file to this host's byte order.
1296  */
1297 static void
1298 swap_linux_usb_header(const struct pcap_pkthdr *hdr, u_char *buf,
1299     int header_len_64_bytes)
1300 {
1301 	pcap_usb_header_mmapped *uhdr = (pcap_usb_header_mmapped *)buf;
1302 	bpf_u_int32 offset = 0;
1303 
1304 	/*
1305 	 * "offset" is the offset *past* the field we're swapping;
1306 	 * we skip the field *before* checking to make sure
1307 	 * the captured data length includes the entire field.
1308 	 */
1309 
1310 	/*
1311 	 * The URB id is a totally opaque value; do we really need to
1312 	 * convert it to the reading host's byte order???
1313 	 */
1314 	offset += 8;			/* skip past id */
1315 	if (hdr->caplen < offset)
1316 		return;
1317 	uhdr->id = SWAPLL(uhdr->id);
1318 
1319 	offset += 4;			/* skip past various 1-byte fields */
1320 
1321 	offset += 2;			/* skip past bus_id */
1322 	if (hdr->caplen < offset)
1323 		return;
1324 	uhdr->bus_id = SWAPSHORT(uhdr->bus_id);
1325 
1326 	offset += 2;			/* skip past various 1-byte fields */
1327 
1328 	offset += 8;			/* skip past ts_sec */
1329 	if (hdr->caplen < offset)
1330 		return;
1331 	uhdr->ts_sec = SWAPLL(uhdr->ts_sec);
1332 
1333 	offset += 4;			/* skip past ts_usec */
1334 	if (hdr->caplen < offset)
1335 		return;
1336 	uhdr->ts_usec = SWAPLONG(uhdr->ts_usec);
1337 
1338 	offset += 4;			/* skip past status */
1339 	if (hdr->caplen < offset)
1340 		return;
1341 	uhdr->status = SWAPLONG(uhdr->status);
1342 
1343 	offset += 4;			/* skip past urb_len */
1344 	if (hdr->caplen < offset)
1345 		return;
1346 	uhdr->urb_len = SWAPLONG(uhdr->urb_len);
1347 
1348 	offset += 4;			/* skip past data_len */
1349 	if (hdr->caplen < offset)
1350 		return;
1351 	uhdr->data_len = SWAPLONG(uhdr->data_len);
1352 
1353 	if (uhdr->transfer_type == URB_ISOCHRONOUS) {
1354 		offset += 4;			/* skip past s.iso.error_count */
1355 		if (hdr->caplen < offset)
1356 			return;
1357 		uhdr->s.iso.error_count = SWAPLONG(uhdr->s.iso.error_count);
1358 
1359 		offset += 4;			/* skip past s.iso.numdesc */
1360 		if (hdr->caplen < offset)
1361 			return;
1362 		uhdr->s.iso.numdesc = SWAPLONG(uhdr->s.iso.numdesc);
1363 	} else
1364 		offset += 8;			/* skip USB setup header */
1365 
1366 	/*
1367 	 * With the old header, there are no isochronous descriptors
1368 	 * after the header.
1369 	 *
1370 	 * With the new header, the actual number of descriptors in
1371 	 * the header is not s.iso.numdesc, it's ndesc - only the
1372 	 * first N descriptors, for some value of N, are put into
1373 	 * the header, and ndesc is set to the actual number copied.
1374 	 * In addition, if s.iso.numdesc is negative, no descriptors
1375 	 * are captured, and ndesc is set to 0.
1376 	 */
1377 	if (header_len_64_bytes) {
1378 		/*
1379 		 * This is either the "version 1" header, with
1380 		 * 16 bytes of additional fields at the end, or
1381 		 * a "version 0" header from a memory-mapped
1382 		 * capture, with 16 bytes of zeroed-out padding
1383 		 * at the end.  Byte swap them as if this were
1384 		 * a "version 1" header.
1385 		 */
1386 		offset += 4;			/* skip past interval */
1387 		if (hdr->caplen < offset)
1388 			return;
1389 		uhdr->interval = SWAPLONG(uhdr->interval);
1390 
1391 		offset += 4;			/* skip past start_frame */
1392 		if (hdr->caplen < offset)
1393 			return;
1394 		uhdr->start_frame = SWAPLONG(uhdr->start_frame);
1395 
1396 		offset += 4;			/* skip past xfer_flags */
1397 		if (hdr->caplen < offset)
1398 			return;
1399 		uhdr->xfer_flags = SWAPLONG(uhdr->xfer_flags);
1400 
1401 		offset += 4;			/* skip past ndesc */
1402 		if (hdr->caplen < offset)
1403 			return;
1404 		uhdr->ndesc = SWAPLONG(uhdr->ndesc);
1405 
1406 		if (uhdr->transfer_type == URB_ISOCHRONOUS) {
1407 			/* swap the values in struct linux_usb_isodesc */
1408 			usb_isodesc *pisodesc;
1409 			uint32_t i;
1410 
1411 			pisodesc = (usb_isodesc *)(void *)(buf+offset);
1412 			for (i = 0; i < uhdr->ndesc; i++) {
1413 				offset += 4;		/* skip past status */
1414 				if (hdr->caplen < offset)
1415 					return;
1416 				pisodesc->status = SWAPLONG(pisodesc->status);
1417 
1418 				offset += 4;		/* skip past offset */
1419 				if (hdr->caplen < offset)
1420 					return;
1421 				pisodesc->offset = SWAPLONG(pisodesc->offset);
1422 
1423 				offset += 4;		/* skip past len */
1424 				if (hdr->caplen < offset)
1425 					return;
1426 				pisodesc->len = SWAPLONG(pisodesc->len);
1427 
1428 				offset += 4;		/* skip past padding */
1429 
1430 				pisodesc++;
1431 			}
1432 		}
1433 	}
1434 }
1435 
1436 /*
1437  * The DLT_NFLOG "packets" have a mixture of big-endian and host-byte-order
1438  * data.  They begin with a fixed-length header with big-endian fields,
1439  * followed by a set of TLVs, where the type and length are in host
1440  * byte order but the values are either big-endian or are a raw byte
1441  * sequence that's the same regardless of the host's byte order.
1442  *
1443  * When reading a DLT_NFLOG capture file, we need to convert the type
1444  * and length values from the byte order of the host that wrote the
1445  * file to the byte order of this host.
1446  */
1447 static void
1448 swap_nflog_header(const struct pcap_pkthdr *hdr, u_char *buf)
1449 {
1450 	u_char *p = buf;
1451 	nflog_hdr_t *nfhdr = (nflog_hdr_t *)buf;
1452 	nflog_tlv_t *tlv;
1453 	u_int caplen = hdr->caplen;
1454 	u_int length = hdr->len;
1455 	uint16_t size;
1456 
1457 	if (caplen < (u_int) sizeof(nflog_hdr_t) ||
1458 	    length < (u_int) sizeof(nflog_hdr_t)) {
1459 		/* Not enough data to have any TLVs. */
1460 		return;
1461 	}
1462 
1463 	if (nfhdr->nflog_version != 0) {
1464 		/* Unknown NFLOG version */
1465 		return;
1466 	}
1467 
1468 	length -= sizeof(nflog_hdr_t);
1469 	caplen -= sizeof(nflog_hdr_t);
1470 	p += sizeof(nflog_hdr_t);
1471 
1472 	while (caplen >= sizeof(nflog_tlv_t)) {
1473 		tlv = (nflog_tlv_t *) p;
1474 
1475 		/* Swap the type and length. */
1476 		tlv->tlv_type = SWAPSHORT(tlv->tlv_type);
1477 		tlv->tlv_length = SWAPSHORT(tlv->tlv_length);
1478 
1479 		/* Get the length of the TLV. */
1480 		size = tlv->tlv_length;
1481 		if (size % 4 != 0)
1482 			size += 4 - size % 4;
1483 
1484 		/* Is the TLV's length less than the minimum? */
1485 		if (size < sizeof(nflog_tlv_t)) {
1486 			/* Yes. Give up now. */
1487 			return;
1488 		}
1489 
1490 		/* Do we have enough data for the full TLV? */
1491 		if (caplen < size || length < size) {
1492 			/* No. */
1493 			return;
1494 		}
1495 
1496 		/* Skip over the TLV. */
1497 		length -= size;
1498 		caplen -= size;
1499 		p += size;
1500 	}
1501 }
1502 
1503 void
1504 swap_pseudo_headers(int linktype, struct pcap_pkthdr *hdr, u_char *data)
1505 {
1506 	/*
1507 	 * Convert pseudo-headers from the byte order of
1508 	 * the host on which the file was saved to our
1509 	 * byte order, as necessary.
1510 	 */
1511 	switch (linktype) {
1512 
1513 	case DLT_LINUX_SLL:
1514 		swap_linux_sll_header(hdr, data);
1515 		break;
1516 
1517 	case DLT_USB_LINUX:
1518 		swap_linux_usb_header(hdr, data, 0);
1519 		break;
1520 
1521 	case DLT_USB_LINUX_MMAPPED:
1522 		swap_linux_usb_header(hdr, data, 1);
1523 		break;
1524 
1525 	case DLT_NFLOG:
1526 		swap_nflog_header(hdr, data);
1527 		break;
1528 	}
1529 }
1530