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wireshark/epan/dissectors/packet-igrp.c

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/* packet-igrp.c
* Routines for IGRP dissection
* Copyright 2000, Paul Ionescu <paul@acorp.ro>
*
* See
*
* http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a00800c8ae1.shtml
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* Copied from packet-syslog.c
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/to_str.h>
#include <epan/ipproto.h>
void proto_register_igrp(void);
void proto_reg_handoff_igrp(void);
#define IGRP_HEADER_LENGTH 12
#define IGRP_ENTRY_LENGTH 14
static dissector_handle_t igrp_handle;
static gint proto_igrp = -1;
static gint hf_igrp_update = -1;
static gint hf_igrp_as = -1;
/* Generated from convert_proto_tree_add_text.pl */
static int hf_igrp_load = -1;
static int hf_igrp_bandwidth = -1;
static int hf_igrp_command = -1;
static int hf_igrp_reliability = -1;
static int hf_igrp_network = -1;
static int hf_igrp_version = -1;
static int hf_igrp_interior_routes = -1;
static int hf_igrp_mtu = -1;
static int hf_igrp_hop_count = -1;
static int hf_igrp_exterior_routes = -1;
static int hf_igrp_delay = -1;
static int hf_igrp_checksum = -1;
static int hf_igrp_system_routes = -1;
static gint ett_igrp = -1;
static gint ett_igrp_vektor = -1;
static gint ett_igrp_net = -1;
static expert_field ei_igrp_version = EI_INIT;
static void dissect_vektor_igrp (packet_info *pinfo, tvbuff_t *tvb, proto_tree *igrp_vektor_tree, guint8 network);
static int dissect_igrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
guint8 ver_and_opcode,version,opcode,network;
gint offset=IGRP_HEADER_LENGTH;
guint16 ninterior,nsystem,nexterior;
const guint8 *ipsrc;
proto_item *ti;
proto_tree *igrp_tree, *igrp_vektor_tree;
tvbuff_t *next_tvb;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "IGRP");
col_clear(pinfo->cinfo, COL_INFO);
ver_and_opcode = tvb_get_guint8(tvb,0);
switch (ver_and_opcode) {
case 0x11:
col_set_str(pinfo->cinfo, COL_INFO, "Response" );
break;
case 0x12:
col_set_str(pinfo->cinfo, COL_INFO, "Request" );
break;
default:
col_set_str(pinfo->cinfo, COL_INFO, "Unknown version or opcode");
}
if (tree) {
ti = proto_tree_add_protocol_format(tree, proto_igrp, tvb, 0, -1,
"Cisco IGRP");
igrp_tree = proto_item_add_subtree(ti, ett_igrp);
version = (ver_and_opcode&0xf0)>>4 ; /* version is the fist half of the byte */
opcode = ver_and_opcode&0x0f ; /* opcode is the last half of the byte */
ti = proto_tree_add_item(igrp_tree, hf_igrp_version, tvb, 0, 1, ENC_BIG_ENDIAN);
if (version != 1)
expert_add_info(pinfo, ti, &ei_igrp_version);
ti = proto_tree_add_item(igrp_tree, hf_igrp_command, tvb, 0, 1, ENC_BIG_ENDIAN);
if (opcode==1)
proto_item_append_text(ti, " (Response)");
else
proto_item_append_text(ti, " (Request)");
proto_tree_add_item(igrp_tree, hf_igrp_update, tvb, 1,1, ENC_BIG_ENDIAN);
proto_tree_add_item(igrp_tree, hf_igrp_as, tvb, 2,2, ENC_BIG_ENDIAN);
ninterior = tvb_get_ntohs(tvb,4);
nsystem = tvb_get_ntohs(tvb,6);
nexterior = tvb_get_ntohs(tvb,8);
/* this is a ugly hack to find the first byte of the IP source address */
if (pinfo->net_src.type == AT_IPv4) {
ipsrc = (const guint8 *)pinfo->net_src.data;
network = ipsrc[0];
} else
network = 0; /* XXX - shouldn't happen */
ti = proto_tree_add_item(igrp_tree, hf_igrp_interior_routes, tvb, 4, 2, ENC_BIG_ENDIAN);
for( ; ninterior>0 ; ninterior-- ) {
igrp_vektor_tree = proto_item_add_subtree(ti,ett_igrp_vektor);
next_tvb = tvb_new_subset_length_caplen(tvb, offset, IGRP_ENTRY_LENGTH, -1);
dissect_vektor_igrp (pinfo,next_tvb,igrp_vektor_tree,network);
offset+=IGRP_ENTRY_LENGTH;
}
ti = proto_tree_add_item(igrp_tree, hf_igrp_system_routes, tvb, 6, 2, ENC_BIG_ENDIAN);
for( ; nsystem>0 ; nsystem-- ) {
igrp_vektor_tree = proto_item_add_subtree(ti,ett_igrp_vektor);
next_tvb = tvb_new_subset_length_caplen(tvb, offset, IGRP_ENTRY_LENGTH, -1);
dissect_vektor_igrp (pinfo,next_tvb,igrp_vektor_tree,0);
offset+=IGRP_ENTRY_LENGTH;
}
ti = proto_tree_add_item(igrp_tree, hf_igrp_exterior_routes, tvb, 8, 2, ENC_BIG_ENDIAN);
for( ; nexterior>0 ; nexterior-- ) {
igrp_vektor_tree = proto_item_add_subtree(ti,ett_igrp_vektor);
next_tvb = tvb_new_subset_length_caplen(tvb, offset, IGRP_ENTRY_LENGTH, -1);
dissect_vektor_igrp (pinfo,next_tvb,igrp_vektor_tree,0);
offset+=IGRP_ENTRY_LENGTH;
}
proto_tree_add_checksum(igrp_tree, tvb, 10, hf_igrp_checksum, -1, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
}
return tvb_captured_length(tvb);
}
static void dissect_vektor_igrp (packet_info *pinfo, tvbuff_t *tvb, proto_tree *igrp_vektor_tree, guint8 network)
{
union {
guint8 addr_bytes[4];
guint32 addr_word;
} addr;
address ip_addr;
if (network != 0) {
/*
* Interior route; network is the high-order byte, and the three
* bytes in the vector are the lower 3 bytes.
*/
addr.addr_bytes[0]=network;
addr.addr_bytes[1]=tvb_get_guint8(tvb,0);
addr.addr_bytes[2]=tvb_get_guint8(tvb,1);
addr.addr_bytes[3]=tvb_get_guint8(tvb,2);
} else {
/*
* System or exterior route; the three bytes in the vector are
* the three high-order bytes, and the low-order byte is 0.
*/
addr.addr_bytes[0]=tvb_get_guint8(tvb,0);
addr.addr_bytes[1]=tvb_get_guint8(tvb,1);
addr.addr_bytes[2]=tvb_get_guint8(tvb,2);
addr.addr_bytes[3]=0;
}
set_address(&ip_addr, AT_IPv4, 4, &addr);
igrp_vektor_tree = proto_tree_add_subtree_format(igrp_vektor_tree, tvb, 0 ,14,
ett_igrp_net, NULL, "Entry for network %s", address_to_str(pinfo->pool, &ip_addr));
proto_tree_add_ipv4(igrp_vektor_tree, hf_igrp_network, tvb, 0, 3, addr.addr_word);
proto_tree_add_item(igrp_vektor_tree, hf_igrp_delay, tvb, 3, 3, ENC_BIG_ENDIAN);
proto_tree_add_item(igrp_vektor_tree, hf_igrp_bandwidth, tvb, 6, 3, ENC_BIG_ENDIAN);
proto_tree_add_item(igrp_vektor_tree, hf_igrp_mtu, tvb, 9, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(igrp_vektor_tree, hf_igrp_reliability, tvb, 11, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(igrp_vektor_tree, hf_igrp_load, tvb, 12, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(igrp_vektor_tree, hf_igrp_hop_count, tvb, 13, 1, ENC_BIG_ENDIAN);
}
/* Register the protocol with Wireshark */
void proto_register_igrp(void)
{
/* Setup list of header fields */
static hf_register_info hf[] = {
{ &hf_igrp_update,
{ "Update Release", "igrp.update",
FT_UINT8, BASE_DEC, NULL, 0x0 ,
"Update Release number", HFILL }
},
{ &hf_igrp_as,
{ "Autonomous System", "igrp.as",
FT_UINT16, BASE_DEC, NULL, 0x0 ,
"Autonomous System number", HFILL }
},
/* Generated from convert_proto_tree_add_text.pl */
{ &hf_igrp_version, { "IGRP Version", "igrp.version", FT_UINT8, BASE_DEC, NULL, 0xF0, NULL, HFILL }},
{ &hf_igrp_command, { "Command", "igrp.command", FT_UINT8, BASE_DEC, NULL, 0x0F, NULL, HFILL }},
{ &hf_igrp_interior_routes, { "Interior routes", "igrp.interior_routes", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_system_routes, { "System routes", "igrp.system_routes", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_exterior_routes, { "Exterior routes", "igrp.exterior_routes", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_checksum, { "Checksum", "igrp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_network, { "Network", "igrp.network", FT_IPv4, BASE_NONE, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_delay, { "Delay", "igrp.delay", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_bandwidth, { "Bandwidth", "igrp.bandwidth", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_mtu, { "MTU", "igrp.mtu", FT_UINT16, BASE_DEC|BASE_UNIT_STRING, &units_byte_bytes, 0x0, NULL, HFILL }},
{ &hf_igrp_reliability, { "Reliability", "igrp.reliability", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_load, { "Load", "igrp.load", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
{ &hf_igrp_hop_count, { "Hop count", "igrp.hop_count", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_igrp,
&ett_igrp_vektor,
&ett_igrp_net
};
static ei_register_info ei[] = {
{ &ei_igrp_version, { "igrp.version.invalid", PI_PROTOCOL, PI_WARN, "Unknown Version, The dissection may be inaccurate", EXPFILL }},
};
expert_module_t* expert_igrp;
/* Register the protocol name and description */
proto_igrp = proto_register_protocol("Cisco Interior Gateway Routing Protocol",
"IGRP", "igrp");
igrp_handle = register_dissector("igrp", dissect_igrp, proto_igrp);
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_igrp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_igrp = expert_register_protocol(proto_igrp);
expert_register_field_array(expert_igrp, ei, array_length(ei));
}
void
proto_reg_handoff_igrp(void)
{
dissector_add_uint("ip.proto", IP_PROTO_IGRP, igrp_handle);
}
/* IGRP Packet structure:
HEADER structure + k * VECTOR structure
where: k = (Number of Interior routes) + (Number of System routes) + (Number of Exterior routes)
HEADER structure is 12 bytes as follows :
4 bits Version (only version 1 is defined)
4 bits Opcode (1=Replay, 2=Request)
8 bits Update Release
16 bits Autonomous system number
16 bits Number of Interior routes
16 bits Number of System routes
16 bits Number of Exterior routes
16 bits Checksum
-------
12 bytes in header
VECTOR structure is 14 bytes as follows :
24 bits Network
24 bits Delay
24 bits Bandwidth
16 bits MTU
8 bits Reliability
8 bits Load
8 bits Hop count
-------
14 bytes in 1 vector
It is interesting how is coded an ip network address in 3 bytes because IGRP is a classful routing protocol:
If it is a interior route then this 3 bytes are the final bytes, and the first one is taken from the source ip address of the ip packet
If it is a system route or a exterior route then this 3 bytes are the first three and the last byte is not important
If the Delay is 0xFFFFFF then the network is unreachable
*/
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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