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/* packet-carp.c
* Routines for the Common Address Redundancy Protocol (CARP)
* Copyright 2013, Uli Heilmeier <uh@heilmeier.eu>
* Based on packet-vrrp.c by Heikki Vatiainen <hessu@cs.tut.fi>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/ipproto.h>
#include <epan/expert.h>
#include <epan/in_cksum.h>
void proto_register_carp(void);
void proto_reg_handoff_carp(void);
static dissector_handle_t carp_handle;
static int proto_carp;
static int ett_carp;
static int ett_carp_ver_type;
static int hf_carp_ver_type;
static int hf_carp_version;
static int hf_carp_type;
static int hf_carp_vhid;
static int hf_carp_advskew;
static int hf_carp_authlen;
static int hf_carp_demotion;
static int hf_carp_advbase;
static int hf_carp_counter;
static int hf_carp_hmac;
static int hf_carp_checksum;
static int hf_carp_checksum_status;
static expert_field ei_carp_checksum;
#define CARP_VERSION_MASK 0xf0
#define CARP_TYPE_MASK 0x0f
#define CARP_TYPE_ADVERTISEMENT 1
static const value_string carp_type_vals[] = {
{CARP_TYPE_ADVERTISEMENT, "Advertisement"},
{0, NULL}
};
static bool
test_carp_packet(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree _U_, void *data _U_)
{
uint8_t ver_type, version, auth_length;
/* First some simple check if the data is
really CARP */
if (tvb_captured_length(tvb) < 36)
return false;
/* Version must be 1 or 2, type must be in carp_type_vals */
ver_type = tvb_get_uint8(tvb, 0);
version = hi_nibble(ver_type);
if ((version == 0) || (version > 2) ||
(try_val_to_str(lo_nibble(ver_type), carp_type_vals) == NULL))
return false;
auth_length = tvb_get_uint8(tvb, 3);
if ( auth_length != 7 )
return false;
return true;
}
static int
dissect_carp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
int offset = 0;
unsigned carp_len;
uint8_t vhid;
vec_t cksum_vec[4];
proto_item *ti, *tv;
proto_tree *carp_tree, *ver_type_tree;
uint8_t ver_type;
/* Make sure it's a CARP packet */
if (!test_carp_packet(tvb, pinfo, tree, data))
return 0;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CARP");
col_clear(pinfo->cinfo, COL_INFO);
vhid = tvb_get_uint8(tvb, 1);
col_add_fstr(pinfo->cinfo, COL_INFO, "%s (Virtual Host ID: %u)",
"Announcement", vhid);
ti = proto_tree_add_item(tree, proto_carp, tvb, 0, -1, ENC_NA);
carp_tree = proto_item_add_subtree(ti, ett_carp);
ver_type = tvb_get_uint8(tvb, 0);
tv = proto_tree_add_uint_format(carp_tree, hf_carp_ver_type,
tvb, offset, 1, ver_type,
"Version %u, Packet type %u (%s)",
hi_nibble(ver_type), lo_nibble(ver_type),
val_to_str_const(lo_nibble(ver_type), carp_type_vals, "Unknown"));
ver_type_tree = proto_item_add_subtree(tv, ett_carp_ver_type);
proto_tree_add_uint(ver_type_tree, hf_carp_version, tvb, offset, 1, ver_type);
proto_tree_add_uint(ver_type_tree, hf_carp_type, tvb, offset, 1, ver_type);
offset++;
proto_tree_add_item(carp_tree, hf_carp_vhid, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(carp_tree, hf_carp_advskew, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(carp_tree, hf_carp_authlen, tvb,
offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(carp_tree, hf_carp_demotion, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(carp_tree, hf_carp_advbase, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
carp_len = tvb_reported_length(tvb);
if (!pinfo->fragmented && tvb_captured_length(tvb) >= carp_len) {
/* The packet isn't part of a fragmented datagram
and isn't truncated, so we can checksum it. */
SET_CKSUM_VEC_TVB(cksum_vec[0], tvb, 0, carp_len);
proto_tree_add_checksum(carp_tree, tvb, offset, hf_carp_checksum, hf_carp_checksum_status, &ei_carp_checksum, pinfo, in_cksum(&cksum_vec[0], 1),
ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);
} else {
proto_tree_add_checksum(carp_tree, tvb, offset, hf_carp_checksum, hf_carp_checksum_status, &ei_carp_checksum, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
}
offset+=2;
/* Counter */
proto_tree_add_item(carp_tree, hf_carp_counter, tvb, offset, 8, ENC_BIG_ENDIAN);
offset+=8;
proto_tree_add_item(carp_tree, hf_carp_hmac, tvb, offset, 20, ENC_NA);
offset+=20;
return offset;
}
/* heuristic dissector */
static bool
dissect_carp_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
if (!test_carp_packet(tvb, pinfo, tree, data))
return false;
dissect_carp(tvb, pinfo, tree, data);
return true;
}
void proto_register_carp(void)
{
static hf_register_info hf[] = {
{ &hf_carp_ver_type,
{"CARP message version and type", "carp.typever",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_carp_version,
{"CARP protocol version", "carp.version",
FT_UINT8, BASE_DEC, NULL, CARP_VERSION_MASK,
NULL, HFILL }},
{ &hf_carp_type,
{"CARP packet type", "carp.type",
FT_UINT8, BASE_DEC, VALS(carp_type_vals), CARP_TYPE_MASK,
NULL, HFILL }},
{ &hf_carp_vhid,
{"Virtual Host ID", "carp.vhid",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_carp_advskew,
{"Advertisement Skew", "carp.advskew",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_carp_authlen,
{"Auth Len", "carp.authlen",
FT_UINT8, BASE_DEC, NULL, 0x0,
"Size of counter+hash in 32bit chunks", HFILL }},
{ &hf_carp_demotion,
{"Demotion indicator", "carp.demotion",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_carp_advbase,
{"Adver Int", "carp.adver_int",
FT_UINT8, BASE_DEC, NULL, 0x0,
"Time interval (in seconds) between ADVERTISEMENTS", HFILL }},
{ &hf_carp_counter, {"Counter", "carp.counter",
FT_UINT64, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_carp_hmac,
{"HMAC", "carp.hmac",
FT_BYTES, BASE_NONE, NULL, 0x0,
"SHA-1 HMAC", HFILL }},
{ &hf_carp_checksum,
{"Checksum", "carp.checksum",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }},
{ &hf_carp_checksum_status,
{"Checksum Status", "carp.checksum.status",
FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
NULL, HFILL }},
};
static int *ett[] = {
&ett_carp,
&ett_carp_ver_type
};
static ei_register_info ei[] = {
{ &ei_carp_checksum, { "carp.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},
};
expert_module_t* expert_carp;
proto_carp = proto_register_protocol("Common Address Redundancy Protocol", "CARP", "carp");
carp_handle = register_dissector("carp", dissect_carp, proto_carp);
proto_register_field_array(proto_carp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_carp = expert_register_protocol(proto_carp);
expert_register_field_array(expert_carp, ei, array_length(ei));
}
void
proto_reg_handoff_carp(void)
{
dissector_add_uint("ip.proto", IP_PROTO_VRRP, carp_handle);
heur_dissector_add( "ip", dissect_carp_heur, "CARP over IP", "carp_ip", proto_carp, HEURISTIC_ENABLE);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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