da785cee2e
Ethernet-over-MPLS, from Aamer Akhter. svn path=/trunk/; revision=4971
225 lines
6 KiB
C
225 lines
6 KiB
C
/* packet-mpls.c
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* Routines for MPLS data packet disassembly
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*
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* (c) Copyright Ashok Narayanan <ashokn@cisco.com>
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*
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* $Id: packet-mpls.c,v 1.26 2002/03/18 18:56:53 guy Exp $
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/*
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* NOTES
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*
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* This module defines routines to handle Ethernet-encapsulated MPLS IP packets.
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* It should implement all the functionality in <draft-ietf-mpls-label-encaps-07.txt>
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* Multicast MPLS support is not tested yet
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#ifdef HAVE_SYS_TYPES_H
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# include <sys/types.h>
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#endif
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#include <glib.h>
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#include <epan/packet.h>
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#include "ppptypes.h"
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#include "etypes.h"
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static gint proto_mpls = -1;
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static gint ett_mpls = -1;
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/* Special labels in MPLS */
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enum {
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IP4_EXPLICIT_NULL = 0,
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ROUTER_ALERT,
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IP6_EXPLICIT_NULL,
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IMPLICIT_NULL,
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MAX_RESERVED = 15
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};
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static const value_string special_labels[] = {
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{IP4_EXPLICIT_NULL, "IPv4 Explicit-Null"},
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{ROUTER_ALERT, "Router Alert"},
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{IP6_EXPLICIT_NULL, "IPv6 Explicit-Null"},
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{IMPLICIT_NULL, "Implicit-Null"},
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{0, NULL }
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};
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/* MPLS filter values */
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enum mpls_filter_keys {
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/* Is the packet MPLS-encapsulated? */
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/* MPLSF_PACKET,*/
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/* MPLS encap properties */
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MPLSF_LABEL,
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MPLSF_EXP,
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MPLSF_BOTTOM_OF_STACK,
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MPLSF_TTL,
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MPLSF_MAX
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};
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static int mpls_filter[MPLSF_MAX];
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static hf_register_info mplsf_info[] = {
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/* {&mpls_filter[MPLSF_PACKET],
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{"MPLS Label Switched Packet", "mpls", FT_UINT8, BASE_DEC, NULL, 0x0,
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"", HFILL }},*/
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{&mpls_filter[MPLSF_LABEL],
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{"MPLS Label", "mpls.label", FT_UINT32, BASE_DEC, VALS(special_labels), 0x0,
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"", HFILL }},
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{&mpls_filter[MPLSF_EXP],
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{"MPLS Experimental Bits", "mpls.exp", FT_UINT8, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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{&mpls_filter[MPLSF_BOTTOM_OF_STACK],
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{"MPLS Bottom Of Label Stack", "mpls.bottom", FT_UINT8, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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{&mpls_filter[MPLSF_TTL],
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{"MPLS TTL", "mpls.ttl", FT_UINT8, BASE_DEC, NULL, 0x0,
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"", HFILL }},
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};
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static dissector_handle_t ipv4_handle;
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static dissector_handle_t ipv6_handle;
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static dissector_handle_t eth_handle;
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/*
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* Given a 4-byte MPLS label starting at offset "offset", in tvbuff "tvb",
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* decode it.
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* Return the label in "label", EXP bits in "exp",
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* bottom_of_stack in "bos", and TTL in "ttl"
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*/
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void decode_mpls_label(tvbuff_t *tvb, int offset,
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guint32 *label, guint8 *exp,
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guint8 *bos, guint8 *ttl)
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{
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guint8 octet0 = tvb_get_guint8(tvb, offset+0);
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guint8 octet1 = tvb_get_guint8(tvb, offset+1);
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guint8 octet2 = tvb_get_guint8(tvb, offset+2);
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*label = (octet0 << 12) + (octet1 << 4) + ((octet2 >> 4) & 0xff);
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*exp = (octet2 >> 1) & 0x7;
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*bos = (octet2 & 0x1);
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*ttl = tvb_get_guint8(tvb, offset+3);
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}
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static void
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dissect_mpls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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int offset = 0;
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guint32 label;
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guint8 exp;
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guint8 bos;
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guint8 ttl;
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guint8 ipvers;
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proto_tree *mpls_tree;
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proto_item *ti;
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tvbuff_t *next_tvb;
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if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
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col_set_str(pinfo->cinfo,COL_PROTOCOL, "MPLS");
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}
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if (check_col(pinfo->cinfo,COL_INFO)) {
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col_add_fstr(pinfo->cinfo,COL_INFO,"MPLS Label Switched Packet");
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}
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/* Start Decoding Here. */
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while (tvb_reported_length_remaining(tvb, offset) > 0) {
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decode_mpls_label(tvb, offset, &label, &exp, &bos, &ttl);
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if (tree) {
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ti = proto_tree_add_item(tree, proto_mpls, tvb, offset, 4, FALSE);
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mpls_tree = proto_item_add_subtree(ti, ett_mpls);
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if (label <= MAX_RESERVED)
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proto_tree_add_uint_format(mpls_tree, mpls_filter[MPLSF_LABEL], tvb,
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offset, 3, label, "Label: %u (%s)",
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label, val_to_str(label, special_labels,
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"Reserved - Unknown"));
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else
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proto_tree_add_uint(mpls_tree, mpls_filter[MPLSF_LABEL], tvb,
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offset, 3, label);
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proto_tree_add_uint(mpls_tree,mpls_filter[MPLSF_EXP], tvb,
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offset+2,1, exp);
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proto_tree_add_uint(mpls_tree,mpls_filter[MPLSF_BOTTOM_OF_STACK], tvb,
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offset+2,1, bos);
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proto_tree_add_uint(mpls_tree,mpls_filter[MPLSF_TTL], tvb,
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offset+3,1, ttl);
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}
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offset += 4;
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if (bos) break;
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}
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next_tvb = tvb_new_subset(tvb, offset, -1, -1);
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ipvers = (tvb_get_guint8(tvb, offset) >> 4) & 0x0F;
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if (ipvers == 6) {
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call_dissector(ipv6_handle, next_tvb, pinfo, tree);
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} else if (ipvers == 4) {
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call_dissector(ipv4_handle, next_tvb, pinfo, tree);
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} else {
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call_dissector(eth_handle, next_tvb, pinfo, tree);
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}
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}
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void
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proto_register_mpls(void)
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{
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static gint *ett[] = {
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&ett_mpls,
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};
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proto_mpls = proto_register_protocol("MultiProtocol Label Switching Header",
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"MPLS", "mpls");
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proto_register_field_array(proto_mpls, mplsf_info, array_length(mplsf_info));
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proto_register_subtree_array(ett, array_length(ett));
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}
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void
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proto_reg_handoff_mpls(void)
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{
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dissector_handle_t mpls_handle;
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/*
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* Get a handle for the IPv4 and IPv6 dissectors.
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*/
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ipv4_handle = find_dissector("ip");
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ipv6_handle = find_dissector("ipv6");
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eth_handle = find_dissector("eth");
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mpls_handle = create_dissector_handle(dissect_mpls, proto_mpls);
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dissector_add("ethertype", ETHERTYPE_MPLS, mpls_handle);
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dissector_add("ppp.protocol", PPP_MPLS_UNI, mpls_handle);
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}
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