2 * Routines for ethernet packet disassembly
4 * $Id: packet-eth.c,v 1.63 2001/04/03 05:42:11 guy Exp $
6 * Ethereal - Network traffic analyzer
7 * By Gerald Combs <gerald@zing.org>
8 * Copyright 1998 Gerald Combs
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version 2
14 * of the License, or (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
30 #ifdef HAVE_SYS_TYPES_H
31 # include <sys/types.h>
38 #include "packet-eth.h"
39 #include "packet-ieee8023.h"
40 #include "packet-ipx.h"
41 #include "packet-isl.h"
42 #include "packet-llc.h"
44 extern const value_string etype_vals[];
46 /* protocols and header fields */
47 static int proto_eth = -1;
48 static int hf_eth_dst = -1;
49 static int hf_eth_src = -1;
50 static int hf_eth_len = -1;
51 static int hf_eth_type = -1;
52 static int hf_eth_addr = -1;
53 static int hf_eth_trailer = -1;
55 static gint ett_ieee8023 = -1;
56 static gint ett_ether2 = -1;
58 static dissector_handle_t isl_handle;
60 #define ETH_HEADER_SIZE 14
62 /* These are the Netware-ish names for the different Ethernet frame types.
63 EthernetII: The ethernet with a Type field instead of a length field
64 Ethernet802.2: An 802.3 header followed by an 802.2 header
65 Ethernet802.3: A raw 802.3 packet. IPX/SPX can be the only payload.
66 There's no 802.2 hdr in this.
67 EthernetSNAP: Basically 802.2, just with 802.2SNAP. For our purposes,
68 there's no difference between 802.2 and 802.2SNAP, since we just
69 pass it down to the LLC dissector. -- Gilbert
72 #define ETHERNET_802_2 1
73 #define ETHERNET_802_3 2
74 #define ETHERNET_SNAP 3
77 capture_eth(const u_char *pd, int offset, packet_counts *ld)
79 guint16 etype, length;
80 int ethhdr_type; /* the type of ethernet frame */
82 if (!BYTES_ARE_IN_FRAME(offset, ETH_HEADER_SIZE)) {
87 etype = pntohs(&pd[offset+12]);
89 /* either ethernet802.3 or ethernet802.2 */
90 if (etype <= IEEE_802_3_MAX_LEN) {
93 /* Is there an 802.2 layer? I can tell by looking at the first 2
94 bytes after the 802.3 header. If they are 0xffff, then what
95 follows the 802.3 header is an IPX payload, meaning no 802.2.
96 (IPX/SPX is they only thing that can be contained inside a
97 straight 802.3 packet). A non-0xffff value means that there's an
98 802.2 layer inside the 802.3 layer */
99 if (pd[offset+14] == 0xff && pd[offset+15] == 0xff) {
100 ethhdr_type = ETHERNET_802_3;
103 ethhdr_type = ETHERNET_802_2;
106 /* Oh, yuck. Cisco ISL frames require special interpretation of the
107 destination address field; fortunately, they can be recognized by
108 checking the first 5 octets of the destination address, which are
109 01-00-0C-00-00 for ISL frames. */
110 if (pd[offset] == 0x01 && pd[offset+1] == 0x00 && pd[offset+2] == 0x0C
111 && pd[offset+3] == 0x00 && pd[offset+4] == 0x00) {
112 capture_isl(pd, offset, ld);
116 /* Convert the LLC length from the 802.3 header to a total
117 frame length, by adding in the size of any data that preceded
118 the Ethernet header, and adding in the Ethernet header size,
119 and set the payload and captured-payload lengths to the minima
120 of the total length and the frame lengths. */
121 length += offset + ETH_HEADER_SIZE;
124 if (pi.captured_len > length)
125 pi.captured_len = length;
127 ethhdr_type = ETHERNET_II;
129 offset += ETH_HEADER_SIZE;
131 switch (ethhdr_type) {
133 capture_ipx(pd, offset, ld);
136 capture_llc(pd, offset, ld);
139 capture_ethertype(etype, offset, pd, ld);
145 dissect_eth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
147 int orig_captured_len;
149 const guint8 *dst, *src;
153 volatile gboolean is_802_2;
155 volatile guint16 length;
156 proto_tree *volatile fh_tree = NULL;
158 tvb_compat(tvb, &pd, (int*)ð_offset);
160 orig_captured_len = pinfo->captured_len;
162 if (check_col(pinfo->fd, COL_PROTOCOL))
163 col_set_str(pinfo->fd, COL_PROTOCOL, "Ethernet");
165 src = tvb_get_ptr(tvb, 6, 6);
166 dst = tvb_get_ptr(tvb, 0, 6);
167 SET_ADDRESS(&pinfo->dl_src, AT_ETHER, 6, src);
168 SET_ADDRESS(&pinfo->src, AT_ETHER, 6, src);
169 SET_ADDRESS(&pinfo->dl_dst, AT_ETHER, 6, dst);
170 SET_ADDRESS(&pinfo->dst, AT_ETHER, 6, dst);
172 etype = tvb_get_ntohs(tvb, 12);
174 /* either ethernet802.3 or ethernet802.2 */
175 if (etype <= IEEE_802_3_MAX_LEN) {
178 /* Oh, yuck. Cisco ISL frames require special interpretation of the
179 destination address field; fortunately, they can be recognized by
180 checking the first 5 octets of the destination address, which are
181 01-00-0C-00-00 for ISL frames. */
182 if ( tvb_get_guint8(tvb, 0) == 0x01 &&
183 tvb_get_guint8(tvb, 1) == 0x00 &&
184 tvb_get_guint8(tvb, 2) == 0x0C &&
185 tvb_get_guint8(tvb, 3) == 0x00 &&
186 tvb_get_guint8(tvb, 4) == 0x00 ) {
187 call_dissector(isl_handle, tvb, pinfo, tree);
191 /* Is there an 802.2 layer? I can tell by looking at the first 2
192 bytes after the 802.3 header. If they are 0xffff, then what
193 follows the 802.3 header is an IPX payload, meaning no 802.2.
194 (IPX/SPX is they only thing that can be contained inside a
195 straight 802.3 packet). A non-0xffff value means that there's an
196 802.2 layer inside the 802.3 layer */
199 if (tvb_get_ntohs(tvb, 14) == 0xffff) {
203 CATCH2(BoundsError, ReportedBoundsError) {
209 if (check_col(pinfo->fd, COL_INFO)) {
210 col_add_fstr(pinfo->fd, COL_INFO, "IEEE 802.3 Ethernet %s",
211 (is_802_2 ? "" : "Raw "));
214 ti = proto_tree_add_protocol_format(tree, proto_eth, tvb, 0, ETH_HEADER_SIZE,
215 "IEEE 802.3 Ethernet %s", (is_802_2 ? "" : "Raw "));
217 fh_tree = proto_item_add_subtree(ti, ett_ieee8023);
219 proto_tree_add_ether(fh_tree, hf_eth_dst, tvb, 0, 6, dst);
220 proto_tree_add_ether(fh_tree, hf_eth_src, tvb, 6, 6, src);
222 /* add items for eth.addr filter */
223 proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 0, 6, dst);
224 proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src);
227 /* Convert the LLC length from the 802.3 header to a total
228 frame length, by adding in the size of any data that preceded
229 the Ethernet header, and adding in the Ethernet header size,
230 and set the payload and captured-payload lengths to the minima
231 of the total length and the frame lengths.
233 XXX - when all dissectors are tvbuffified we shouldn't have to
235 length += eth_offset + ETH_HEADER_SIZE;
236 if (pinfo->len > length)
238 if (pinfo->captured_len > length)
239 pinfo->captured_len = length;
241 dissect_802_3(etype, is_802_2, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree,
242 hf_eth_len, hf_eth_trailer);
244 if (check_col(pinfo->fd, COL_INFO))
245 col_set_str(pinfo->fd, COL_INFO, "Ethernet II");
247 ti = proto_tree_add_protocol_format(tree, proto_eth, tvb, 0, ETH_HEADER_SIZE,
250 fh_tree = proto_item_add_subtree(ti, ett_ether2);
252 proto_tree_add_ether(fh_tree, hf_eth_dst, tvb, 0, 6, dst);
253 proto_tree_add_ether(fh_tree, hf_eth_src, tvb, 6, 6, src);
254 /* add items for eth.addr filter */
255 proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 0, 6, dst);
256 proto_tree_add_ether_hidden(fh_tree, hf_eth_addr, tvb, 6, 6, src);
259 ethertype(etype, tvb, ETH_HEADER_SIZE, pinfo, tree, fh_tree, hf_eth_type,
265 proto_register_eth(void)
267 static hf_register_info hf[] = {
270 { "Destination", "eth.dst", FT_ETHER, BASE_NONE, NULL, 0x0,
271 "Destination Hardware Address" }},
274 { "Source", "eth.src", FT_ETHER, BASE_NONE, NULL, 0x0,
275 "Source Hardware Address" }},
278 { "Length", "eth.len", FT_UINT16, BASE_DEC, NULL, 0x0,
281 /* registered here but handled in ethertype.c */
283 { "Type", "eth.type", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0,
286 { "Source or Destination Address", "eth.addr", FT_ETHER, BASE_NONE, NULL, 0x0,
287 "Source or Destination Hardware Address" }},
290 { "Trailer", "eth.trailer", FT_BYTES, BASE_NONE, NULL, 0x0,
291 "Ethernet Trailer or Checksum" }},
294 static gint *ett[] = {
299 proto_eth = proto_register_protocol("Ethernet", "Ethernet", "eth");
300 proto_register_field_array(proto_eth, hf, array_length(hf));
301 proto_register_subtree_array(ett, array_length(ett));
303 register_dissector("eth", dissect_eth, proto_eth);
307 proto_reg_handoff_eth(void)
310 * Get a handle for the ISL dissector.
312 isl_handle = find_dissector("isl");
314 dissector_add("wtap_encap", WTAP_ENCAP_ETHERNET, dissect_eth,
316 dissector_add("ethertype", ETHERTYPE_ETHBRIDGE, dissect_eth,
318 dissector_add("chdlctype", ETHERTYPE_ETHBRIDGE, dissect_eth,
320 dissector_add("gre.proto", ETHERTYPE_ETHBRIDGE, dissect_eth,