path: root/packet-igmp.c

/* packet-igmp.c   2001 Ronnie Sahlberg <rsahlber@bigpond.net.au>
 * Routines for IGMP packet disassembly
 *
 * $Id: packet-igmp.c,v 1.7 2001/06/29 18:55:49 guy Exp $
 *
 * Ethereal - Network traffic analyzer
 * By Gerald Combs <gerald@ethereal.com>
 * Copyright 1998 Gerald Combs
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
/*
	IGMP is defined in the following RFCs
	RFC988	Version 0	Obsolete
	RFC1054	Version 1
	RFC1112	Version 1	(same as RFC1054 as far as we are concerned)
	RFC2236	Version 2
	draft-ietf-idmr-igmp-v3-07	Version 3

	Size in bytes for each packet
	type	RFC988	RFC1054	RFC2236 RFC????  DVMRP  MRDISC  MSNIP
	        v0      v1      v2      v3       v1/v3
	0x01      20
	0x02      20
	0x03      20
	0x04      20
	0x05      20
	0x06      20
	0x07      20
	0x08      20
	0x11               8*     8*     >=12
        0x12               8*     8* 
	0x13                                     x
	0x16                      8
	0x17                      8
	0x22                            >=8
	0x23                                                    >=8b      
	0x24                                            >=8a    8b
	0x25                                            4a      >=8b
	0x26                                            4a


   * Differs in second byte of protocol. Always 0 in V1

   x DVMRP Protocol  see packet-dvmrp.c

	DVMRP is defined in the following RFCs
	RFC1075 Version 1
	draft-ietf-idmr-dvmrp-v3-10.txt Version 3

	V1 and V3 can be distinguished by looking at bytes 6 and 7 in the 
	IGMP header.
	If header[6]==0xff and header[7]==0x03 we have version 3.

   a MRDISC Protocol  see packet-mrdisc.c

	MRDISC : IGMP Multicast Router DISCovery
	draft-ietf-idmr-igmp-mrdisc-06.txt
	TTL == 1 and IP.DST==224.0.0.2 for all packets

   b MSNIP Protocol  see packet-msnip.c

	MSNIP : Multicast Source Notification of Interest Protocol
	draft-ietf-idmr-msnip-00.txt
	0x23, 0x24 are sent with ip.dst==224.0.0.22
	0x25 is sent as unicast.

*/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif

#include <stdio.h>
#include <string.h>
#include <glib.h>

#include "packet.h"
#include "ipproto.h"
#include "in_cksum.h"
#include "packet-dvmrp.h"
#include "packet-mrdisc.h"
#include "packet-msnip.h"

static int proto_igmp = -1;
static int hf_type = -1;
static int hf_version = -1;
static int hf_group_type = -1;
static int hf_reply_code = -1;
static int hf_reply_pending = -1;
static int hf_checksum = -1;
static int hf_checksum_bad = -1;
static int hf_identifier = -1;
static int hf_access_key = -1;
static int hf_max_resp = -1;
static int hf_max_resp_exp = -1;
static int hf_max_resp_mant = -1;
static int hf_supress = -1;
static int hf_qrv = -1;
static int hf_qqic = -1;
static int hf_num_src = -1;
static int hf_saddr = -1;
static int hf_num_grp_recs = -1;
static int hf_record_type = -1;
static int hf_aux_data_len = -1;
static int hf_maddr = -1;
static int hf_aux_data = -1;

static int ett_igmp = -1;
static int ett_group_record = -1;
static int ett_sqrv_bits = -1;
static int ett_max_resp = -1;

#define MC_ALL_ROUTERS		0xe0000002
#define MC_ALL_IGMPV3_ROUTERS	0xe0000016


#define IGMP_V0_CREATE_GROUP_REQUEST	0x01
#define IGMP_V0_CREATE_GROUP_REPLY	0x02
#define IGMP_V0_JOIN_GROUP_REQUEST	0x03
#define IGMP_V0_JOIN_GROUP_REPLY	0x04
#define IGMP_V0_LEAVE_GROUP_REQUEST	0x05
#define IGMP_V0_LEAVE_GROUP_REPLY	0x06
#define IGMP_V0_CONFIRM_GROUP_REQUEST	0x07
#define IGMP_V0_CONFIRM_GROUP_REPLY	0x08
#define IGMP_V1_HOST_MEMBERSHIP_QUERY	0x11
#define IGMP_V1_HOST_MEMBERSHIP_REPORT	0x12
#define IGMP_DVMRP			0x13
#define IGMP_V1_PIM_ROUTING_MESSAGE	0x14
#define IGMP_V2_MEMBERSHIP_REPORT	0x16
#define IGMP_V2_LEAVE_GROUP		0x17
#define IGMP_V1_TRACEROUTE_RESPONSE	0x1e	/* XXX */
#define IGMP_V1_TRACEROUTE_MESSAGE	0x1f	/* XXX */
#define IGMP_V3_MEMBERSHIP_REPORT	0x22
#define IGMP_TYPE_0x23			0x23
#define IGMP_TYPE_0x24			0x24
#define IGMP_TYPE_0x25			0x25
#define IGMP_TYPE_0x26			0x26
	
static const value_string commands[] = {
	{IGMP_V0_CREATE_GROUP_REQUEST,	"Create Group Request"		},
	{IGMP_V0_CREATE_GROUP_REPLY,	"Create Group Reply"		},
	{IGMP_V0_JOIN_GROUP_REQUEST,	"Join Group Request"		},
	{IGMP_V0_JOIN_GROUP_REPLY,	"Join Group Reply"		},
	{IGMP_V0_LEAVE_GROUP_REQUEST,	"Leave Group Request"		},
	{IGMP_V0_LEAVE_GROUP_REPLY,	"Leave Group Reply"		},
	{IGMP_V0_CONFIRM_GROUP_REQUEST,	"Confirm Group Request"		},
	{IGMP_V0_CONFIRM_GROUP_REPLY,	"Confirm Group Reply"		},
	{IGMP_V1_HOST_MEMBERSHIP_QUERY,	"Membership Query"		},
	{IGMP_V1_HOST_MEMBERSHIP_REPORT,"Membership Report"		},
	{IGMP_DVMRP,			"DVMRP Protocol"		},
	{IGMP_V1_PIM_ROUTING_MESSAGE,	"PIM Routing Message"		},
	{IGMP_V2_MEMBERSHIP_REPORT,	"Membership Report"		},
	{IGMP_V2_LEAVE_GROUP,		"Leave Group"			},
	{IGMP_V1_TRACEROUTE_RESPONSE,	"Traceroute Response"		},
	{IGMP_V1_TRACEROUTE_MESSAGE,	"Traceroute Message"		},
	{IGMP_V3_MEMBERSHIP_REPORT,	"Membership Report"		},
	{0,		NULL}
};

#define IGMP_V3_S		0x08
#define IGMP_V3_QRV_MASK	0x07

#define IGMP_MAX_RESP_EXP	0x70
#define IGMP_MAX_RESP_MANT	0x0f

#define IGMP_V0_GROUP_PUBLIC	0x00
#define IGMP_V0_GROUP_PRIVATE	0x01

static const value_string vs_group_type[] = {
	{IGMP_V0_GROUP_PUBLIC,		"Public Group"			},
	{IGMP_V0_GROUP_PRIVATE,		"Private Group"			},
	{0,		NULL}
};

#define IGMP_V0_REPLY_GRANTED	0x00
#define IGMP_V0_REPLY_NO_RESOURCES	0x01
#define IGMP_V0_REPLY_INVALID_CODE	0x02
#define IGMP_V0_REPLY_INVALID_GROUP	0x03
#define IGMP_V0_REPLY_INVALID_KEY	0x04

static const value_string vs_reply_code[] = {
	{IGMP_V0_REPLY_GRANTED,	"Request Granted"	},
	{IGMP_V0_REPLY_NO_RESOURCES,	"Request Denied, No Resources"	},
	{IGMP_V0_REPLY_INVALID_CODE,	"Request Denied, Invalid Code"	},
	{IGMP_V0_REPLY_INVALID_GROUP,	"Request Denied, Invalid Group"	},
	{IGMP_V0_REPLY_INVALID_KEY,	"Request Denied, Invalid Key"	},
	{0,		NULL}
};

static const true_false_string tfs_s = {
	"SUPRESS router side processing",
	"Do not supress router side processing"
};

#define IGMP_V3_MODE_IS_INCLUDE		1
#define IGMP_V3_MODE_IS_EXCLUDE		2
#define IGMP_V3_CHANGE_TO_INCLUDE_MODE	3
#define IGMP_V3_CHANGE_TO_EXCLUDE_MODE	4
#define IGMP_V3_ALLOW_NEW_SOURCES	5
#define IGMP_V3_BLOCK_OLD_SOURCES	6

static const value_string vs_record_type[] = {
	{IGMP_V3_MODE_IS_INCLUDE, 	"Mode Is Include"		},
	{IGMP_V3_MODE_IS_EXCLUDE, 	"Mode Is Exclude"		},
	{IGMP_V3_CHANGE_TO_INCLUDE_MODE,"Change To Include Mode"	},
	{IGMP_V3_CHANGE_TO_EXCLUDE_MODE,"Change To Exclude Mode"	},
	{IGMP_V3_ALLOW_NEW_SOURCES, 	"Allow New Sources"		},
	{IGMP_V3_BLOCK_OLD_SOURCES, 	"Block Old Sources"		},
	{ 0,	NULL}
};

#define PRINT_IGMP_VERSION(version) 					\
	if (check_col(pinfo->fd, COL_INFO)) {				\
		col_add_fstr(pinfo->fd, COL_INFO,			\
			"V%d %s",version,val_to_str(type, commands, 	\
				"Unknown Type:0x%02x"));		\
	}								\
	/* version of IGMP protocol */					\
	proto_tree_add_uint(tree, hf_version, tvb, 0, 0, version);	\
	/* type of command */						\
	proto_tree_add_uint(tree, hf_type, tvb, offset, 1, type);	\
	offset += 1;

static void igmp_checksum(proto_tree *tree,tvbuff_t *tvb, int len)
{
	guint16 cksum,hdrcksum;
	vec_t cksum_vec[1];

	cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, len);
	cksum_vec[0].len = len;

	hdrcksum = tvb_get_ntohs(tvb, 2);
	cksum = in_cksum(&cksum_vec[0],1);

	if (cksum==0) {
		proto_tree_add_uint_format(tree, hf_checksum, tvb, 2, 2, hdrcksum, "Header checksum: 0x%04x (correct)", hdrcksum);
	} else {
		proto_tree_add_item_hidden(tree, hf_checksum_bad, tvb, 2, 2, TRUE);
		proto_tree_add_uint_format(tree, hf_checksum, tvb, 2, 2, hdrcksum, "Header checksum: 0x%04x (incorrect, should be 0x%04x)", hdrcksum,in_cksum_shouldbe(hdrcksum,cksum));
	}

	return;
}


/* Unknown IGMP message type */
static int
dissect_igmp_unknown(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, int offset)
{
	int len;

	if (check_col(pinfo->fd, COL_INFO)) {
		col_add_str(pinfo->fd, COL_INFO,
			val_to_str(type, commands, "Unknown Type:0x%02x"));
	}

	/* type of command */
	proto_tree_add_uint(tree, hf_type, tvb, offset, 1, type);
	offset += 1;

	/* Just call the rest of it "data" */
	len = tvb_length_remaining(tvb, offset);
	proto_tree_add_text(tree, tvb, offset, len, "Data");
	offset += len;

	return offset;
}



/*************************************************************
 * IGMP Protocol dissectors
 *************************************************************/
static int
dissect_v3_max_resp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
{
	proto_tree *tree;
	proto_item *item;
	guint8 bits;
	guint32 tsecs;

	bits = tvb_get_guint8(tvb, offset);
	if (bits&0x80) {
		tsecs = ((bits&IGMP_MAX_RESP_MANT)|0x10);
		tsecs = tsecs << ( ((bits&IGMP_MAX_RESP_EXP)>>4) + 3);
	} else {
		tsecs = bits;
	}		

	item = proto_tree_add_uint_format(parent_tree, hf_max_resp, tvb,
			offset, 1, tsecs, "Max Response Time: %.1f sec (0x%02x)",tsecs*0.1,bits);

	if (bits&0x80) {
		tree = proto_item_add_subtree(item, ett_max_resp);

		proto_tree_add_uint(tree, hf_max_resp_exp, tvb, offset, 1,
			bits);
		proto_tree_add_uint(tree, hf_max_resp_mant, tvb, offset, 1,
			bits);
	}

	offset += 1;

	return offset;
}

static int
dissect_v3_sqrv_bits(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
{
	proto_tree *tree;
	proto_item *item;
	guint8 bits;

	bits = tvb_get_guint8(tvb, offset);

	item = proto_tree_add_text(parent_tree, tvb, offset, 1, 
		"QRV=%d S=%s", bits&IGMP_V3_QRV_MASK,
			(bits&IGMP_V3_S)?tfs_s.true_string:tfs_s.false_string);
	tree = proto_item_add_subtree(item, ett_sqrv_bits);

	/* S flag */
	proto_tree_add_boolean(tree, hf_supress, tvb, offset, 1, bits);
	/* QRV */
	proto_tree_add_uint(tree, hf_qrv, tvb, offset, 1, bits);
	offset += 1;

	return offset;
}

static int
dissect_v3_group_record(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
{
	proto_tree *tree;
	proto_item *item;
	int old_offset = offset;
	guint8	adl;
	guint16 num;
	guint32 ip;

	ip = tvb_get_letohl(tvb, offset+4);
	item = proto_tree_add_text(parent_tree, tvb, offset, 0, 
		"Group Record : %s  %s", 
			ip_to_str((gchar*)&ip), 
			val_to_str(tvb_get_guint8(tvb, offset), vs_record_type,"")
		);
	tree = proto_item_add_subtree(item, ett_group_record);

	/* record type */
	proto_tree_add_uint(tree, hf_record_type, tvb, offset, 1, tvb_get_guint8(tvb, offset));
	offset += 1;

	/* aux data len */
	adl = tvb_get_guint8(tvb, offset);
	proto_tree_add_uint(tree, hf_aux_data_len, tvb, offset, 1, adl);
	offset += 1;

	/*number of sources*/
	num = tvb_get_ntohs(tvb, offset);
	proto_tree_add_uint(tree, hf_num_src, tvb, offset, 2, num);
	offset += 2;

	/* multicast address */
	proto_tree_add_ipv4(tree, hf_maddr, tvb, 
		offset, 4, tvb_get_letohl(tvb, offset));
	offset += 4;

	/* source addresses */
	while(num--){
		proto_tree_add_ipv4(tree, hf_saddr, tvb, 
			offset, 4, tvb_get_letohl(tvb, offset));
		offset += 4;
	}

	/* aux data */
	if(adl){
		proto_tree_add_bytes(tree, hf_aux_data, tvb, offset, adl*4, tvb_get_ptr(tvb, offset, adl*4));
		offset += adl*4;
	}

	proto_item_set_len(item, offset-old_offset);
	return offset;
}

/* dissectors for version 3, rfc???? */
static int
dissect_igmp_v3_response(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, int offset)
{
	guint16 num;

	PRINT_IGMP_VERSION(3);

	/* skip reserved field*/
	offset += 1;

	/* checksum */
	igmp_checksum(tree, tvb, pinfo->iplen-pinfo->iphdrlen*4);
	offset +=2;

	/* skip reserved field */
	offset += 2;

	/* number of group records */
	num = tvb_get_ntohs(tvb, offset);
	proto_tree_add_uint(tree, hf_num_grp_recs, tvb, offset, 2, num);
	offset += 2;
	
	while (num--) {
		offset = dissect_v3_group_record(tvb,pinfo,tree,offset);
	}

	return offset;
}

static int
dissect_igmp_v3_query(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, int offset)
{
	guint16 num;

	PRINT_IGMP_VERSION(3);

	num = tvb_get_ntohs(tvb, offset+9);
	/* max resp code */
	offset = dissect_v3_max_resp(tvb, pinfo, tree, offset);

	/* checksum */
	igmp_checksum(tree, tvb, pinfo->iplen-pinfo->iphdrlen*4);
	offset += 2;

	/* group address */
	proto_tree_add_ipv4(tree, hf_maddr, tvb, offset, 4, tvb_get_letohl(tvb, offset));
	offset +=4;

	/* bitmask for S and QRV */
	offset = dissect_v3_sqrv_bits(tvb, pinfo, tree, offset);

	/* qqic */
	proto_tree_add_uint(tree, hf_qqic, tvb, offset, 1, tvb_get_guint8(tvb, offset));
	offset += 1;

	/*number of sources*/
	proto_tree_add_uint(tree, hf_num_src, tvb, offset, 2, num);
	offset += 2;

	while(num--){
		proto_tree_add_ipv4(tree, hf_saddr, tvb, 
			offset, 4, tvb_get_letohl(tvb, offset));
		offset += 4;
	}

	return offset;
}

/* dissector for version 2, rfc2236 */
static int
dissect_igmp_v2(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, int offset)
{
	guint8 tsecs;

	PRINT_IGMP_VERSION(2);

	/* max resp time */
	tsecs = tvb_get_guint8(tvb, offset);
	proto_tree_add_uint_format(tree, hf_max_resp, tvb,
		offset, 1, tsecs, "Max Response Time: %.1f sec (0x%02x)", tsecs*0.1,tsecs);
	offset += 1;

	/* checksum */
	igmp_checksum(tree, tvb, 8);
	offset += 2;

	/* group address */
	proto_tree_add_ipv4(tree, hf_maddr, tvb, offset, 4, tvb_get_letohl(tvb, offset));
	offset +=4;

	return offset;
}

/* dissector for version 1, rfc1054 */
static int
dissect_igmp_v1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, int offset)
{
	PRINT_IGMP_VERSION(1);

	/* skip unused byte */
	offset += 1;

	/* checksum */
	igmp_checksum(tree, tvb, 8);
	offset += 2;

	/* group address */
	proto_tree_add_ipv4(tree, hf_maddr, tvb, offset, 4, tvb_get_letohl(tvb, offset));
	offset +=4;

	return offset;
}

/*
 * Dissector for V1 PIM messages.
 *
 * XXX - are these just PIM V1 messages (which we don't dissect in the PIM
 * dissector)?  Where is PIM V1 documented?  I'm inferring some of this
 * from the tcpdump IGMP dissector.
 */
#define PIMV1_QUERY		0
#define PIMV1_REGISTER		1
#define PIMV1_REGISTER_STOP	2
#define PIMV1_JOIN_PRUNE	3
#define PIMV1_RP_REACHABLE	4
#define PIMV1_ASSERT		5
#define PIMV1_GRAFT		6
#define PIMV1_GRAFT_ACK		7
#define PIMV1_MODE		8

static const value_string pim_routing_type[] = {
	{ PIMV1_QUERY,		"Query" },
	{ PIMV1_REGISTER,	"Register" },
	{ PIMV1_REGISTER_STOP,	"Register-Stop" },
	{ PIMV1_JOIN_PRUNE,	"Join/Prune" },
	{ PIMV1_RP_REACHABLE,	"RP-reachable" },
	{ PIMV1_ASSERT,		"Assert" },
	{ PIMV1_GRAFT,		"Graft" },
	{ PIMV1_GRAFT_ACK,	"Graft-ACK" },
	{ PIMV1_MODE,		"Mode" },
	{ 0,			NULL }
};

static int
dissect_igmp_v1_pim_routing(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, int offset)
{
	guint8 pimv1_type;

	PRINT_IGMP_VERSION(1);

	pimv1_type = tvb_get_guint8(tvb, offset);
	proto_tree_add_text(tree, tvb, offset, 2, "Message type: %s",
	    val_to_str(pimv1_type, pim_routing_type, "Unknown (%u)"));

	/* XXX - dissect the rest of it */
	return offset;
}

/* dissector for version 0, rfc988 */
static int
dissect_igmp_v0(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int type, int offset)
{
	unsigned char code;

	PRINT_IGMP_VERSION(0);

	/* Code */
	code = tvb_get_guint8(tvb, offset);
	if (type==IGMP_V0_CREATE_GROUP_REQUEST) {
		proto_tree_add_uint(tree, hf_group_type, tvb, offset, 1, code);
	} else if (!(type&0x01)) {
		if (code <5) {
			proto_tree_add_uint(tree, hf_reply_code, tvb, offset, 1, code);
		} else {
			proto_tree_add_uint(tree, hf_reply_pending, tvb, offset, 1, code);
		}
	}
	offset += 1;

	/* checksum */
	igmp_checksum(tree, tvb, 20);
	offset += 2;

	/* identifier */
	proto_tree_add_uint(tree, hf_identifier, tvb, offset, 4, tvb_get_ntohl(tvb, offset));
	offset += 4;

	/* group address */
	proto_tree_add_ipv4(tree, hf_maddr, tvb, offset, 4, tvb_get_letohl(tvb, offset));
	offset +=4;

	/* access key */
	proto_tree_add_bytes(tree, hf_access_key, tvb, offset, 8, tvb_get_ptr(tvb, offset, 8));
	offset +=8;

	return offset;		
} 

static void
dissect_igmp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree)
{
	proto_tree *tree;
	proto_item *item;
	int offset = 0;
	unsigned char type;
	guint32 dst;

	item = proto_tree_add_item(parent_tree, proto_igmp, tvb, offset, 0, FALSE);
	tree = proto_item_add_subtree(item, ett_igmp);


	if (check_col(pinfo->fd, COL_PROTOCOL)) {
		col_set_str(pinfo->fd, COL_PROTOCOL, "IGMP");
	}
	if (check_col(pinfo->fd, COL_INFO)) {
		col_clear(pinfo->fd, COL_INFO);
	}


	type = tvb_get_guint8(tvb, offset);


	/* version 0 */
	if ((type&0xf0)==0){
		offset = dissect_igmp_v0(tvb, pinfo, tree, type, offset);
	}


	switch (type) {

	case IGMP_V1_HOST_MEMBERSHIP_QUERY:	/* 0x11 v1/v2/v3 */
		if ( (pinfo->iplen-pinfo->iphdrlen*4)>=12 ) {
			/* version 3 */
			offset = dissect_igmp_v3_query(tvb, pinfo, tree, type, offset);
		} else {
			/* v1 and v2 differs in second byte of header */
			if (tvb_get_guint8(tvb, offset)) {
				offset = dissect_igmp_v2(tvb, pinfo, tree, type, offset);
			} else {
				offset = dissect_igmp_v1(tvb, pinfo, tree, type, offset);
			}
		}
		break;

	case IGMP_V1_HOST_MEMBERSHIP_REPORT:	/* 0x12  v1/v2 */
		/* v1 and v2 differs in second byte of header */
		if (tvb_get_guint8(tvb, offset)) {
			offset = dissect_igmp_v2(tvb, pinfo, tree, type, offset);
		} else {
			offset = dissect_igmp_v1(tvb, pinfo, tree, type, offset);
		}
		break;

	case IGMP_DVMRP:
		offset = dissect_dvmrp(tvb, pinfo, parent_tree, offset);
		break;

	case IGMP_V1_PIM_ROUTING_MESSAGE:
		offset = dissect_igmp_v1_pim_routing(tvb, pinfo, tree, type, offset);
		break;

	case IGMP_V2_MEMBERSHIP_REPORT:
	case IGMP_V2_LEAVE_GROUP:
		offset = dissect_igmp_v2(tvb, pinfo, tree, type, offset);
		break;

	case IGMP_V1_TRACEROUTE_RESPONSE:
		/* XXX - V1 or V2? */
		offset = dissect_igmp_v1(tvb, pinfo, tree, type, offset);
		/*
		 * XXX - dissect the rest as traceroute response; see the
		 * tcpdump IGMP dissector.
		 */
		break;

	case IGMP_V1_TRACEROUTE_MESSAGE:
		/* XXX - V1 or V2? */
		offset = dissect_igmp_v1(tvb, pinfo, tree, type, offset);
		/*
		 * XXX - dissect the rest as traceroute message; see the
		 * tcpdump IGMP dissector.
		 */
		break;

	case IGMP_V3_MEMBERSHIP_REPORT:
		offset = dissect_igmp_v3_response(tvb, pinfo, tree, type, offset);
		break;
	case IGMP_TYPE_0x23:
		dst = htonl(MC_ALL_IGMPV3_ROUTERS);
		if (!memcmp(pinfo->dst.data, &dst, 4)) {
			offset = dissect_msnip(tvb, pinfo, parent_tree, offset);
		}
		break;
	case IGMP_TYPE_0x24:
		dst = htonl(MC_ALL_ROUTERS);
		if (!memcmp(pinfo->dst.data, &dst, 4)) {
			offset = dissect_mrdisc(tvb, pinfo, parent_tree, offset);
		}  
		dst = htonl(MC_ALL_IGMPV3_ROUTERS);
		if (!memcmp(pinfo->dst.data, &dst, 4)) {
			offset = dissect_msnip(tvb, pinfo, parent_tree, offset);
		}
		break;
	case IGMP_TYPE_0x25:
		if ( (pinfo->iplen-pinfo->iphdrlen*4)>=8 ) {
			/* if len of igmp packet>=8 we assume it is MSNIP */
			offset = dissect_msnip(tvb, pinfo, parent_tree, offset);
		} else {
			/* ok its not MSNIP, check if it might be MRDISC */
			dst = htonl(MC_ALL_ROUTERS);
			if (!memcmp(pinfo->dst.data, &dst, 4)) {
				offset = dissect_mrdisc(tvb, pinfo, parent_tree, offset);
			}
		}
		break;
	case IGMP_TYPE_0x26:
		dst = htonl(MC_ALL_ROUTERS);
		if (!memcmp(pinfo->dst.data, &dst, 4)) {
			offset = dissect_mrdisc(tvb, pinfo, parent_tree, offset);
		}
		break;

	default:
		offset = dissect_igmp_unknown(tvb, pinfo, tree, type, offset);
		break;
	}


	proto_item_set_len(item, offset);
}

void
proto_register_igmp(void)
{
	static hf_register_info hf[] = {
		{ &hf_type,
			{ "Type", "igmp.type", FT_UINT8, BASE_HEX,
			  VALS(commands), 0, "IGMP Packet Type", HFILL }},

		{ &hf_version,
			{ "IGMP Version", "igmp.version", FT_UINT8, BASE_DEC,
			  NULL, 0, "IGMP Version", HFILL }},

		{ &hf_group_type,
			{ "Type Of Group", "igmp.group_type", FT_UINT8, BASE_DEC,
			  VALS(vs_group_type), 0, "IGMP V0 Type Of Group", HFILL }},

		{ &hf_reply_code,
			{ "Reply", "igmp.reply", FT_UINT8, BASE_DEC,
			  VALS(vs_reply_code), 0, "IGMP V0 Reply", HFILL }},

		{ &hf_reply_pending,
			{ "Reply Pending", "igmp.reply.pending", FT_UINT8, BASE_DEC,
			  NULL, 0, "IGMP V0 Reply Pending, Retry in this many seconds", HFILL }},

		{ &hf_checksum,
			{ "Checksum", "igmp.checksum", FT_UINT16, BASE_HEX,
			  NULL, 0, "IGMP Checksum", HFILL }},

		{ &hf_checksum_bad,
			{ "Bad Checksum", "igmp.checksum_bad", FT_BOOLEAN, BASE_NONE,
			  NULL, 0, "Bad IGMP Checksum", HFILL }},

		{ &hf_identifier,
			{ "Identifier", "igmp.identifier", FT_UINT32, BASE_DEC,
			  NULL, 0, "IGMP V0 Identifier", HFILL }},

		{ &hf_access_key,
			{ "Access Key", "igmp.access_key", FT_BYTES, BASE_HEX,
			  NULL, 0, "IGMP V0 Access Key", HFILL }},

		{ &hf_max_resp,
			{ "Max Resp Time", "igmp.max_resp", FT_UINT8, BASE_DEC,
			  NULL, 0, "Max Response Time", HFILL }},

		{ &hf_supress,
			{ "S", "igmp.s", FT_BOOLEAN, 8,
			  TFS(&tfs_s), IGMP_V3_S, "Supress Router Side Processing", HFILL }},

		{ &hf_qrv,
			{ "QRV", "igmp.qrv", FT_UINT8, BASE_DEC,
			NULL, IGMP_V3_QRV_MASK, "Querier's Robustness Value", HFILL }},

		{ &hf_qqic,
			{ "QQIC", "igmp.qqic", FT_UINT8, BASE_DEC,
			  NULL, 0, "Querier's Query Interval Code", HFILL }},

		{ &hf_num_src,
			{ "Num Src", "igmp.num_src", FT_UINT16, BASE_DEC,
			  NULL, 0, "Number Of Sources", HFILL }},

		{ &hf_saddr,
			{ "Source Address", "igmp.saddr", FT_IPv4, BASE_NONE,
			  NULL, 0, "Source Address", HFILL }},

		{ &hf_num_grp_recs,
			{ "Num Group Records", "igmp.num_grp_recs", FT_UINT16, BASE_DEC,
			  NULL, 0, "Number Of Group Records", HFILL }},

		{ &hf_record_type,
			{ "Record Type", "igmp.record_type", FT_UINT8, BASE_DEC,
			VALS(vs_record_type), 0, "Record Type", HFILL }},

		{ &hf_aux_data_len,
			{ "Aux Data Len", "igmp.aux_data_len", FT_UINT8, BASE_DEC,
			NULL, 0, "Aux Data Len, In units of 32bit words", HFILL }},

		{ &hf_maddr,
			{ "Multicast Address", "igmp.maddr", FT_IPv4, BASE_NONE,
			  NULL, 0, "Multicast Address", HFILL }},

		{ &hf_aux_data,
			{ "Aux Data", "igmp.aux_data", FT_BYTES, BASE_HEX,
			  NULL, 0, "IGMP V3 Auxiliary Data", HFILL }},

		{ &hf_max_resp_exp,
			{ "Exponent", "igmp.max_resp.exp", FT_UINT8, BASE_HEX,
			NULL, IGMP_MAX_RESP_EXP, "Maxmimum Response Time, Exponent", HFILL }},

		{ &hf_max_resp_mant,
			{ "Mantissa", "igmp.max_resp.mant", FT_UINT8, BASE_HEX,
			NULL, IGMP_MAX_RESP_MANT, "Maxmimum Response Time, Mantissa", HFILL }},

	};
	static gint *ett[] = {
		&ett_igmp,
		&ett_group_record,
		&ett_sqrv_bits,
		&ett_max_resp,
	};

	proto_igmp = proto_register_protocol("Internet Group Management Protocol",
	    "IGMP", "igmp");
	proto_register_field_array(proto_igmp, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
}

void
proto_reg_handoff_igmp(void)
{
	dissector_add("ip.proto", IP_PROTO_IGMP, dissect_igmp, proto_igmp);
}