2 * Routines for MPLS data packet disassembly
4 * (c) Copyright Ashok Narayanan <ashokn@cisco.com>
6 * $Id: packet-mpls.c,v 1.19 2001/04/19 23:02:44 guy Exp $
8 * Ethereal - Network traffic analyzer
9 * By Gerald Combs <gerald@zing.org>
10 * Copyright 1998 Gerald Combs
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version 2
16 * of the License, or (at your option) any later version.
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software
25 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
31 * This module defines routines to handle Ethernet-encapsulated MPLS IP packets.
32 * It should implement all the functionality in <draft-ietf-mpls-label-encaps-07.txt>
33 * Multicast MPLS support is not tested yet
41 #ifdef HAVE_SYS_TYPES_H
42 # include <sys/types.h>
47 #include "packet-ip.h"
51 static gint proto_mpls = -1;
53 static gint ett_mpls = -1;
55 /* Special labels in MPLS */
57 IP4_EXPLICIT_NULL = 0,
65 static const value_string special_labels[] = {
66 {IP4_EXPLICIT_NULL, "IPv4 Explicit-Null"},
67 {ROUTER_ALERT, "Router Alert"},
68 {IP6_EXPLICIT_NULL, "IPv6 Explicit-Null"},
69 {IMPLICIT_NULL, "Implicit-Null"},
73 /* MPLS filter values */
74 enum mpls_filter_keys {
76 /* Is the packet MPLS-encapsulated? */
79 /* MPLS encap properties */
82 MPLSF_BOTTOM_OF_STACK,
88 static int mpls_filter[MPLSF_MAX];
89 static hf_register_info mplsf_info[] = {
91 /* {&mpls_filter[MPLSF_PACKET],
92 {"MPLS Label Switched Packet", "mpls", FT_UINT8, BASE_DEC, NULL, 0x0,
95 {&mpls_filter[MPLSF_LABEL],
96 {"MPLS Label", "mpls.label", FT_UINT32, BASE_DEC, VALS(special_labels), 0x0,
99 {&mpls_filter[MPLSF_EXP],
100 {"MPLS Experimental Bits", "mpls.exp", FT_UINT8, BASE_DEC, NULL, 0x0,
103 {&mpls_filter[MPLSF_BOTTOM_OF_STACK],
104 {"MPLS Bottom Of Label Stack", "mpls.bottom", FT_UINT8, BASE_DEC, NULL, 0x0,
107 {&mpls_filter[MPLSF_TTL],
108 {"MPLS TTL", "mpls.ttl", FT_UINT8, BASE_DEC, NULL, 0x0,
112 static dissector_handle_t ip_handle;
115 * Given a 4-byte MPLS label starting at offset "offset", in tvbuff "tvb",
117 * Return the label in "label", EXP bits in "exp",
118 * bottom_of_stack in "bos", and TTL in "ttl"
120 void decode_mpls_label(tvbuff_t *tvb, int offset,
121 guint32 *label, guint8 *exp,
122 guint8 *bos, guint8 *ttl)
124 guint8 octet0 = tvb_get_guint8(tvb, offset+0);
125 guint8 octet1 = tvb_get_guint8(tvb, offset+1);
126 guint8 octet2 = tvb_get_guint8(tvb, offset+2);
128 *label = (octet0 << 12) + (octet1 << 4) + ((octet2 >> 4) & 0xff);
129 *exp = (octet2 >> 1) & 0x7;
130 *bos = (octet2 & 0x1);
131 *ttl = tvb_get_guint8(tvb, offset+3);
135 dissect_mpls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
143 proto_tree *mpls_tree;
147 if (check_col(pinfo->fd, COL_PROTOCOL)) {
148 col_set_str(pinfo->fd,COL_PROTOCOL, "MPLS");
151 if (check_col(pinfo->fd,COL_INFO)) {
152 col_add_fstr(pinfo->fd,COL_INFO,"MPLS Label Switched Packet");
155 /* Start Decoding Here. */
156 while (tvb_reported_length_remaining(tvb, offset) > 0) {
157 decode_mpls_label(tvb, offset, &label, &exp, &bos, &ttl);
161 ti = proto_tree_add_item(tree, proto_mpls, tvb, offset, 4, FALSE);
162 mpls_tree = proto_item_add_subtree(ti, ett_mpls);
164 if (label <= MAX_RESERVED)
165 proto_tree_add_uint_format(mpls_tree, mpls_filter[MPLSF_LABEL], tvb,
166 offset, 3, label, "Label: %u (%s)",
167 label, val_to_str(label, special_labels,
168 "Reserved - Unknown"));
170 proto_tree_add_uint(mpls_tree, mpls_filter[MPLSF_LABEL], tvb,
173 proto_tree_add_uint(mpls_tree,mpls_filter[MPLSF_EXP], tvb,
175 proto_tree_add_uint(mpls_tree,mpls_filter[MPLSF_BOTTOM_OF_STACK], tvb,
177 proto_tree_add_uint(mpls_tree,mpls_filter[MPLSF_TTL], tvb,
183 next_tvb = tvb_new_subset(tvb, offset, -1, -1);
184 call_dissector(ip_handle, next_tvb, pinfo, tree);
188 proto_register_mpls(void)
190 static gint *ett[] = {
194 proto_mpls = proto_register_protocol("MultiProtocol Label Switching Header",
196 proto_register_field_array(proto_mpls, mplsf_info, array_length(mplsf_info));
197 proto_register_subtree_array(ett, array_length(ett));
201 proto_reg_handoff_mpls(void)
204 * Get a handle for the IP dissector.
206 ip_handle = find_dissector("ip");
208 dissector_add("ethertype", ETHERTYPE_MPLS, dissect_mpls, proto_mpls);
209 dissector_add("ppp.protocol", PPP_MPLS_UNI, dissect_mpls, proto_mpls);