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/* packet-mrdisc.c 2001 Ronnie Sahlberg <See AUTHORS for email>
* Routines for IGMP/MRDISC packet disassembly
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
MRDISC
code
0x24 x
0x25 x
0x26 x
MRDISC : IGMP Multicast Router DISCovery
Defined in draft-ietf-idmr-igmp-mrdisc-06.txt
TTL==1 and IP.DST==224.0.0.2 for all packets.
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include "packet-igmp.h"
void proto_register_mrdisc(void);
void proto_reg_handoff_mrdisc(void);
static dissector_handle_t mrdisc_handle;
static int proto_mrdisc;
static int hf_checksum;
static int hf_checksum_status;
static int hf_type;
static int hf_advint;
static int hf_numopts;
static int hf_options;
static int hf_option;
static int hf_option_len;
static int hf_qi;
static int hf_rv;
static int hf_option_bytes;
static int ett_mrdisc;
static int ett_options;
static expert_field ei_checksum;
#define MC_ALL_ROUTERS 0xe0000002
#define MRDISC_MRA 0x24
#define MRDISC_MRS 0x25
#define MRDISC_MRT 0x26
static const value_string mrdisc_types[] = {
{MRDISC_MRA, "Multicast Router Advertisement"},
{MRDISC_MRS, "Multicast Router Solicitation"},
{MRDISC_MRT, "Multicast Router Termination"},
{0, NULL}
};
#define MRDISC_QI 0x01
#define MRDISC_RV 0x02
static const value_string mrdisc_options[] = {
{MRDISC_QI, "Query Interval"},
{MRDISC_RV, "Robustness Variable"},
{0, NULL}
};
static int
dissect_mrdisc_mra(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
{
uint16_t num;
/* Advertising Interval */
proto_tree_add_item(parent_tree, hf_advint, tvb, offset, 1, ENC_BIG_ENDIAN);
offset += 1;
/* checksum */
igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_status, &ei_checksum, pinfo, 0);
offset += 2;
/* skip unused bytes */
offset += 2;
/* number of options */
num = tvb_get_ntohs(tvb, offset);
proto_tree_add_uint(parent_tree, hf_numopts, tvb,
offset, 2, num);
offset += 2;
/* process any options */
while (num--) {
proto_tree *tree;
proto_item *item;
uint8_t type,len;
int old_offset = offset;
item = proto_tree_add_item(parent_tree, hf_options,
tvb, offset, -1, ENC_NA);
tree = proto_item_add_subtree(item, ett_options);
type = tvb_get_uint8(tvb, offset);
proto_tree_add_uint(tree, hf_option, tvb, offset, 1, type);
offset += 1;
len = tvb_get_uint8(tvb, offset);
proto_tree_add_uint(tree, hf_option_len, tvb, offset, 1, len);
offset += 1;
switch (type) {
case MRDISC_QI:
proto_item_set_text(item,"Option: %s == %d",
val_to_str(type, mrdisc_options, "unknown %x"),
tvb_get_ntohs(tvb, offset));
proto_tree_add_item(tree, hf_qi, tvb, offset, len,
ENC_BIG_ENDIAN);
offset += len;
break;
case MRDISC_RV:
proto_item_set_text(item,"Option: %s == %d",
val_to_str(type, mrdisc_options, "unknown %x"),
tvb_get_ntohs(tvb, offset));
proto_tree_add_item(tree, hf_rv, tvb, offset, len,
ENC_BIG_ENDIAN);
offset += len;
break;
default:
proto_item_set_text(item,"Option: unknown");
proto_tree_add_item(tree, hf_option_bytes,
tvb, offset, len, ENC_NA);
offset += len;
}
proto_item_set_len(item, offset-old_offset);
}
return offset;
}
static int
dissect_mrdisc_mrst(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, int offset)
{
/* skip reserved byte */
offset += 1;
/* checksum */
igmp_checksum(parent_tree, tvb, hf_checksum, hf_checksum_status, &ei_checksum, pinfo, 0);
offset += 2;
return offset;
}
/* This function is only called from the IGMP dissector */
static int
dissect_mrdisc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_)
{
proto_tree *tree;
proto_item *item;
uint8_t type;
int offset = 0;
uint32_t dst = g_htonl(MC_ALL_ROUTERS);
/* Shouldn't be destined for us */
if ((pinfo->dst.type != AT_IPv4) || memcmp(pinfo->dst.data, &dst, 4))
return 0;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "MRDISC");
col_clear(pinfo->cinfo, COL_INFO);
item = proto_tree_add_item(parent_tree, proto_mrdisc, tvb, offset, 0, ENC_NA);
tree = proto_item_add_subtree(item, ett_mrdisc);
type = tvb_get_uint8(tvb, offset);
col_add_str(pinfo->cinfo, COL_INFO,
val_to_str(type, mrdisc_types,
"Unknown Type:0x%02x"));
/* type of command */
proto_tree_add_uint(tree, hf_type, tvb, offset, 1, type);
offset += 1;
switch (type) {
case MRDISC_MRA:
offset = dissect_mrdisc_mra(tvb, pinfo, tree, offset);
break;
case MRDISC_MRS:
case MRDISC_MRT:
/* MRS and MRT packets looks the same */
offset = dissect_mrdisc_mrst(tvb, pinfo, tree, offset);
break;
}
return offset;
}
void
proto_register_mrdisc(void)
{
static hf_register_info hf[] = {
{ &hf_type,
{ "Type", "mrdisc.type", FT_UINT8, BASE_HEX,
VALS(mrdisc_types), 0, "MRDISC Packet Type", HFILL }},
{ &hf_checksum,
{ "Checksum", "mrdisc.checksum", FT_UINT16, BASE_HEX,
NULL, 0, "MRDISC Checksum", HFILL }},
{ &hf_checksum_status,
{ "Checksum Status", "mrdisc.checksum.status", FT_UINT8, BASE_NONE,
VALS(proto_checksum_vals), 0x0, NULL, HFILL }},
{ &hf_advint,
{ "Advertising Interval", "mrdisc.adv_int", FT_UINT8, BASE_DEC,
NULL, 0, "MRDISC Advertising Interval in seconds", HFILL }},
{ &hf_numopts,
{ "Number Of Options", "mrdisc.num_opts", FT_UINT16, BASE_DEC,
NULL, 0, "MRDISC Number Of Options", HFILL }},
{ &hf_options,
{ "Options", "mrdisc.options", FT_NONE, BASE_NONE,
NULL, 0, "MRDISC Options", HFILL }},
{ &hf_option,
{ "Option", "mrdisc.option", FT_UINT8, BASE_DEC,
VALS(mrdisc_options), 0, "MRDISC Option Type", HFILL }},
{ &hf_option_len,
{ "Length", "mrdisc.opt_len", FT_UINT8, BASE_DEC,
NULL, 0, "MRDISC Option Length", HFILL }},
{ &hf_qi,
{ "Query Interval", "mrdisc.query_int", FT_UINT16, BASE_DEC,
NULL, 0, "MRDISC Query Interval", HFILL }},
{ &hf_rv,
{ "Robustness Variable", "mrdisc.rob_var", FT_UINT16, BASE_DEC,
NULL, 0, "MRDISC Robustness Variable", HFILL }},
{ &hf_option_bytes,
{ "Data", "mrdisc.option_data", FT_BYTES, BASE_NONE,
NULL, 0, "MRDISC Unknown Option Data", HFILL }},
};
static int *ett[] = {
&ett_mrdisc,
&ett_options,
};
static ei_register_info ei[] = {
{ &ei_checksum, { "mrdisc.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},
};
expert_module_t* expert_mrdisc;
proto_mrdisc = proto_register_protocol("Multicast Router DISCovery protocol", "MRDISC", "mrdisc");
proto_register_field_array(proto_mrdisc, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_mrdisc = expert_register_protocol(proto_mrdisc);
expert_register_field_array(expert_mrdisc, ei, array_length(ei));
mrdisc_handle = register_dissector("mrdisc", dissect_mrdisc, proto_mrdisc);
}
void
proto_reg_handoff_mrdisc(void)
{
dissector_add_uint("igmp.type", IGMP_TYPE_0x24, mrdisc_handle);
dissector_add_uint("igmp.type", IGMP_TYPE_0x25, mrdisc_handle);
dissector_add_uint("igmp.type", IGMP_TYPE_0x26, mrdisc_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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