1 /*
2 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 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
22 /* \summary: Linux cooked sockets capture printer */
23
24 #ifdef HAVE_CONFIG_H
25 #include "config.h"
26 #endif
27
28 #include <netdissect-stdinc.h>
29
30 #include "netdissect.h"
31 #include "addrtoname.h"
32 #include "ethertype.h"
33 #include "extract.h"
34
35 #include "ether.h"
36
37 /*
38 * For captures on Linux cooked sockets, we construct a fake header
39 * that includes:
40 *
41 * a 2-byte "packet type" which is one of:
42 *
43 * LINUX_SLL_HOST packet was sent to us
44 * LINUX_SLL_BROADCAST packet was broadcast
45 * LINUX_SLL_MULTICAST packet was multicast
46 * LINUX_SLL_OTHERHOST packet was sent to somebody else
47 * LINUX_SLL_OUTGOING packet was sent *by* us;
48 *
49 * a 2-byte Ethernet protocol field;
50 *
51 * a 2-byte link-layer type;
52 *
53 * a 2-byte link-layer address length;
54 *
55 * an 8-byte source link-layer address, whose actual length is
56 * specified by the previous value.
57 *
58 * All fields except for the link-layer address are in network byte order.
59 *
60 * DO NOT change the layout of this structure, or change any of the
61 * LINUX_SLL_ values below. If you must change the link-layer header
62 * for a "cooked" Linux capture, introduce a new DLT_ type (ask
63 * "tcpdump-workers@lists.tcpdump.org" for one, so that you don't give it
64 * a value that collides with a value already being used), and use the
65 * new header in captures of that type, so that programs that can
66 * handle DLT_LINUX_SLL captures will continue to handle them correctly
67 * without any change, and so that capture files with different headers
68 * can be told apart and programs that read them can dissect the
69 * packets in them.
70 *
71 * This structure, and the #defines below, must be the same in the
72 * libpcap and tcpdump versions of "sll.h".
73 */
74
75 /*
76 * A DLT_LINUX_SLL fake link-layer header.
77 */
78 #define SLL_HDR_LEN 16 /* total header length */
79 #define SLL_ADDRLEN 8 /* length of address field */
80
81 struct sll_header {
82 uint16_t sll_pkttype; /* packet type */
83 uint16_t sll_hatype; /* link-layer address type */
84 uint16_t sll_halen; /* link-layer address length */
85 uint8_t sll_addr[SLL_ADDRLEN]; /* link-layer address */
86 uint16_t sll_protocol; /* protocol */
87 };
88
89 /*
90 * The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
91 * PACKET_ values on Linux, but are defined here so that they're
92 * available even on systems other than Linux, and so that they
93 * don't change even if the PACKET_ values change.
94 */
95 #define LINUX_SLL_HOST 0
96 #define LINUX_SLL_BROADCAST 1
97 #define LINUX_SLL_MULTICAST 2
98 #define LINUX_SLL_OTHERHOST 3
99 #define LINUX_SLL_OUTGOING 4
100
101 /*
102 * The LINUX_SLL_ values for "sll_protocol"; these correspond to the
103 * ETH_P_ values on Linux, but are defined here so that they're
104 * available even on systems other than Linux. We assume, for now,
105 * that the ETH_P_ values won't change in Linux; if they do, then:
106 *
107 * if we don't translate them in "pcap-linux.c", capture files
108 * won't necessarily be readable if captured on a system that
109 * defines ETH_P_ values that don't match these values;
110 *
111 * if we do translate them in "pcap-linux.c", that makes life
112 * unpleasant for the BPF code generator, as the values you test
113 * for in the kernel aren't the values that you test for when
114 * reading a capture file, so the fixup code run on BPF programs
115 * handed to the kernel ends up having to do more work.
116 *
117 * Add other values here as necessary, for handling packet types that
118 * might show up on non-Ethernet, non-802.x networks. (Not all the ones
119 * in the Linux "if_ether.h" will, I suspect, actually show up in
120 * captures.)
121 */
122 #define LINUX_SLL_P_802_3 0x0001 /* Novell 802.3 frames without 802.2 LLC header */
123 #define LINUX_SLL_P_802_2 0x0004 /* 802.2 frames (not D/I/X Ethernet) */
124
125 static const struct tok sll_pkttype_values[] = {
126 { LINUX_SLL_HOST, "In" },
127 { LINUX_SLL_BROADCAST, "B" },
128 { LINUX_SLL_MULTICAST, "M" },
129 { LINUX_SLL_OTHERHOST, "P" },
130 { LINUX_SLL_OUTGOING, "Out" },
131 { 0, NULL}
132 };
133
134 static inline void
sll_print(netdissect_options * ndo,register const struct sll_header * sllp,u_int length)135 sll_print(netdissect_options *ndo, register const struct sll_header *sllp, u_int length)
136 {
137 u_short ether_type;
138
139 ND_PRINT((ndo, "%3s ",tok2str(sll_pkttype_values,"?",EXTRACT_16BITS(&sllp->sll_pkttype))));
140
141 /*
142 * XXX - check the link-layer address type value?
143 * For now, we just assume 6 means Ethernet.
144 * XXX - print others as strings of hex?
145 */
146 if (EXTRACT_16BITS(&sllp->sll_halen) == 6)
147 ND_PRINT((ndo, "%s ", etheraddr_string(ndo, sllp->sll_addr)));
148
149 if (!ndo->ndo_qflag) {
150 ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
151
152 if (ether_type <= ETHERMTU) {
153 /*
154 * Not an Ethernet type; what type is it?
155 */
156 switch (ether_type) {
157
158 case LINUX_SLL_P_802_3:
159 /*
160 * Ethernet_802.3 IPX frame.
161 */
162 ND_PRINT((ndo, "802.3"));
163 break;
164
165 case LINUX_SLL_P_802_2:
166 /*
167 * 802.2.
168 */
169 ND_PRINT((ndo, "802.2"));
170 break;
171
172 default:
173 /*
174 * What is it?
175 */
176 ND_PRINT((ndo, "ethertype Unknown (0x%04x)",
177 ether_type));
178 break;
179 }
180 } else {
181 ND_PRINT((ndo, "ethertype %s (0x%04x)",
182 tok2str(ethertype_values, "Unknown", ether_type),
183 ether_type));
184 }
185 ND_PRINT((ndo, ", length %u: ", length));
186 }
187 }
188
189 /*
190 * This is the top level routine of the printer. 'p' points to the
191 * Linux "cooked capture" header of the packet, 'h->ts' is the timestamp,
192 * 'h->len' is the length of the packet off the wire, and 'h->caplen'
193 * is the number of bytes actually captured.
194 */
195 u_int
sll_if_print(netdissect_options * ndo,const struct pcap_pkthdr * h,const u_char * p)196 sll_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
197 {
198 u_int caplen = h->caplen;
199 u_int length = h->len;
200 register const struct sll_header *sllp;
201 u_short ether_type;
202 int llc_hdrlen;
203 u_int hdrlen;
204
205 if (caplen < SLL_HDR_LEN) {
206 /*
207 * XXX - this "can't happen" because "pcap-linux.c" always
208 * adds this many bytes of header to every packet in a
209 * cooked socket capture.
210 */
211 ND_PRINT((ndo, "[|sll]"));
212 return (caplen);
213 }
214
215 sllp = (const struct sll_header *)p;
216
217 if (ndo->ndo_eflag)
218 sll_print(ndo, sllp, length);
219
220 /*
221 * Go past the cooked-mode header.
222 */
223 length -= SLL_HDR_LEN;
224 caplen -= SLL_HDR_LEN;
225 p += SLL_HDR_LEN;
226 hdrlen = SLL_HDR_LEN;
227
228 ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
229
230 recurse:
231 /*
232 * Is it (gag) an 802.3 encapsulation, or some non-Ethernet
233 * packet type?
234 */
235 if (ether_type <= ETHERMTU) {
236 /*
237 * Yes - what type is it?
238 */
239 switch (ether_type) {
240
241 case LINUX_SLL_P_802_3:
242 /*
243 * Ethernet_802.3 IPX frame.
244 */
245 ipx_print(ndo, p, length);
246 break;
247
248 case LINUX_SLL_P_802_2:
249 /*
250 * 802.2.
251 * Try to print the LLC-layer header & higher layers.
252 */
253 llc_hdrlen = llc_print(ndo, p, length, caplen, NULL, NULL);
254 if (llc_hdrlen < 0)
255 goto unknown; /* unknown LLC type */
256 hdrlen += llc_hdrlen;
257 break;
258
259 default:
260 /*FALLTHROUGH*/
261
262 unknown:
263 /* packet type not known, print raw packet */
264 if (!ndo->ndo_suppress_default_print)
265 ND_DEFAULTPRINT(p, caplen);
266 break;
267 }
268 } else if (ether_type == ETHERTYPE_8021Q) {
269 /*
270 * Print VLAN information, and then go back and process
271 * the enclosed type field.
272 */
273 if (caplen < 4) {
274 ND_PRINT((ndo, "[|vlan]"));
275 return (hdrlen + caplen);
276 }
277 if (length < 4) {
278 ND_PRINT((ndo, "[|vlan]"));
279 return (hdrlen + length);
280 }
281 if (ndo->ndo_eflag) {
282 uint16_t tag = EXTRACT_16BITS(p);
283
284 ND_PRINT((ndo, "%s, ", ieee8021q_tci_string(tag)));
285 }
286
287 ether_type = EXTRACT_16BITS(p + 2);
288 if (ether_type <= ETHERMTU)
289 ether_type = LINUX_SLL_P_802_2;
290 if (!ndo->ndo_qflag) {
291 ND_PRINT((ndo, "ethertype %s, ",
292 tok2str(ethertype_values, "Unknown", ether_type)));
293 }
294 p += 4;
295 length -= 4;
296 caplen -= 4;
297 hdrlen += 4;
298 goto recurse;
299 } else {
300 if (ethertype_print(ndo, ether_type, p, length, caplen, NULL, NULL) == 0) {
301 /* ether_type not known, print raw packet */
302 if (!ndo->ndo_eflag)
303 sll_print(ndo, sllp, length + SLL_HDR_LEN);
304 if (!ndo->ndo_suppress_default_print)
305 ND_DEFAULTPRINT(p, caplen);
306 }
307 }
308
309 return (hdrlen);
310 }
311