2 * Routines for ethernet packet disassembly
4 * $Id: packet-eth.c,v 1.21 1999/10/22 07:17:31 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>
39 extern const value_string etype_vals[];
41 /* protocols and header fields */
42 static int proto_eth = -1;
43 static int hf_eth_dst = -1;
44 static int hf_eth_src = -1;
45 static int hf_eth_len = -1;
46 static int hf_eth_type = -1;
48 #define ETH_HEADER_SIZE 14
50 /* These are the Netware-ish names for the different Ethernet frame types.
51 EthernetII: The ethernet with a Type field instead of a length field
52 Ethernet802.2: An 802.3 header followed by an 802.3 header
53 Ethernet802.3: A raw 802.3 packet. IPX/SPX can be the only payload.
54 There's not 802.2 hdr in this.
55 EthernetSNAP: Basically 802.2, just with 802.2SNAP. For our purposes,
56 there's no difference between 802.2 and 802.2SNAP, since we just
57 pass it down to dissect_llc(). -- Gilbert
60 #define ETHERNET_802_2 1
61 #define ETHERNET_802_3 2
62 #define ETHERNET_SNAP 3
65 capture_eth(const u_char *pd, guint32 cap_len, packet_counts *ld) {
67 int offset = ETH_HEADER_SIZE;
68 int ethhdr_type; /* the type of ethernet frame */
70 if (cap_len < ETH_HEADER_SIZE) {
75 etype = (pd[12] << 8) | pd[13];
77 /* either ethernet802.3 or ethernet802.2 */
78 if (etype <= IEEE_802_3_MAX_LEN) {
80 /* Is there an 802.2 layer? I can tell by looking at the first 2
81 bytes after the 802.3 header. If they are 0xffff, then what
82 follows the 802.3 header is an IPX payload, meaning no 802.2.
83 (IPX/SPX is they only thing that can be contained inside a
84 straight 802.3 packet). A non-0xffff value means that there's an
85 802.2 layer inside the 802.3 layer */
86 if (pd[14] == 0xff && pd[15] == 0xff) {
87 ethhdr_type = ETHERNET_802_3;
90 ethhdr_type = ETHERNET_802_2;
93 ethhdr_type = ETHERNET_II;
96 switch (ethhdr_type) {
98 ld->other++; /* IPX */
101 capture_llc(pd, offset, cap_len, ld);
104 capture_ethertype(etype, offset, pd, cap_len, ld);
110 dissect_eth(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) {
111 guint16 etype, length;
112 proto_tree *fh_tree = NULL;
114 int ethhdr_type; /* the type of ethernet frame */
116 if (fd->cap_len < ETH_HEADER_SIZE) {
117 dissect_data(pd, offset, fd, tree);
121 SET_ADDRESS(&pi.dl_src, AT_ETHER, 6, &pd[offset+6]);
122 SET_ADDRESS(&pi.src, AT_ETHER, 6, &pd[offset+6]);
123 SET_ADDRESS(&pi.dl_dst, AT_ETHER, 6, &pd[offset+0]);
124 SET_ADDRESS(&pi.dst, AT_ETHER, 6, &pd[offset+0]);
126 if (check_col(fd, COL_PROTOCOL))
127 col_add_str(fd, COL_PROTOCOL, "Ethernet");
129 etype = (pd[offset+12] << 8) | pd[offset+13];
131 /* either ethernet802.3 or ethernet802.2 */
132 if (etype <= IEEE_802_3_MAX_LEN) {
135 /* Is there an 802.2 layer? I can tell by looking at the first 2
136 bytes after the 802.3 header. If they are 0xffff, then what
137 follows the 802.3 header is an IPX payload, meaning no 802.2.
138 (IPX/SPX is they only thing that can be contained inside a
139 straight 802.3 packet). A non-0xffff value means that there's an
140 802.2 layer inside the 802.3 layer */
141 if (pd[offset+14] == 0xff && pd[offset+15] == 0xff) {
142 ethhdr_type = ETHERNET_802_3;
145 ethhdr_type = ETHERNET_802_2;
148 if (check_col(fd, COL_INFO)) {
149 col_add_fstr(fd, COL_INFO, "IEEE 802.3 %s",
150 (ethhdr_type == ETHERNET_802_3 ? "Raw " : ""));
154 ti = proto_tree_add_item_format(tree, proto_eth, 0, ETH_HEADER_SIZE,
155 NULL, "IEEE 802.3 %s", (ethhdr_type == ETHERNET_802_3 ? "Raw " : ""));
157 fh_tree = proto_item_add_subtree(ti, ETT_IEEE8023);
159 proto_tree_add_item(fh_tree, hf_eth_dst, 0, 6, &pd[offset+0]);
160 proto_tree_add_item(fh_tree, hf_eth_src, 6, 6, &pd[offset+6]);
161 proto_tree_add_item(fh_tree, hf_eth_len, 12, 2, length);
163 /* Convert the LLC length from the 802.3 header to a total
164 length, by adding in the Ethernet header size, and set
165 the payload and captured-payload lengths to the minima
166 of the total length and the frame lengths. */
167 length += ETH_HEADER_SIZE;
170 if (pi.captured_len > length)
171 pi.captured_len = length;
175 ethhdr_type = ETHERNET_II;
176 if (check_col(fd, COL_INFO))
177 col_add_str(fd, COL_INFO, "Ethernet II");
180 ti = proto_tree_add_item_format(tree, proto_eth, 0, ETH_HEADER_SIZE,
181 NULL, "Ethernet II");
183 fh_tree = proto_item_add_subtree(ti, ETT_ETHER2);
185 proto_tree_add_item_format(fh_tree, hf_eth_dst, 0, 6, &pd[offset+0],
186 "Destination: %s (%s)", ether_to_str((guint8 *) &pd[offset+0]),
187 get_ether_name((u_char *) &pd[offset+0]));
189 proto_tree_add_item_format(fh_tree, hf_eth_src, 6, 6, &pd[offset+6],
190 "Source: %s (%s)", ether_to_str((guint8 *) &pd[offset+6]),
191 get_ether_name((u_char *) &pd[offset+6]));
194 offset += ETH_HEADER_SIZE;
196 switch (ethhdr_type) {
198 dissect_ipx(pd, offset, fd, tree);
201 dissect_llc(pd, offset, fd, tree);
204 ethertype(etype, offset, pd, fd, tree, fh_tree, hf_eth_type);
210 proto_register_eth(void)
212 static hf_register_info hf[] = {
215 { "Destination", "eth.dst", FT_ETHER, BASE_NONE, NULL, 0x0,
216 "Destination Hardware Address" }},
219 { "Source", "eth.src", FT_ETHER, BASE_NONE, NULL, 0x0,
220 "Source Hardware Address" }},
223 { "Length", "eth.len", FT_UINT16, BASE_DEC, NULL, 0x0,
226 /* registered here but handled in ethertype.c */
228 { "Type", "eth.type", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0,
232 proto_eth = proto_register_protocol ("Ethernet", "eth" );
233 proto_register_field_array(proto_eth, hf, array_length(hf));