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/* packet-rlm.c
* Routines for RLM dissection
* Copyright 2004, Duncan Sargeant <dunc-ethereal@rcpt.to>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* RLM is a proprietary Cisco protocol used for centralling managing
* many redundant NASes. I don't know much about the format, but you
* can read about the feature here:
*
* http://www.cisco.com/en/US/docs/ios/12_0t/12_0t3/feature/guide/rlm_123.html
*
* RLM runs on a UDP port (default 3000) between the MGC and the NAS.
* On port N+1 (default 3001), a Q.931/LAPD/UDP connection is maintained.
* Both sides use the same local port number for the connection, so source
* and dest port are always the same.
*
* In large networks, the links are typically split onto higher ports,
* so anything up to 3015 (or higher) could either be RLM or Q.931 traffic,
* although always the RLM has the one lower port number for that RLM group.
*
* Multiple RLM groups are possible on a single NAS.
*
* I haven't been able to find the protocol documented, so I've
* guessed some of the fields based on the output of debug commands on
* cisco NASes.
*
*/
#include "config.h"
#include <epan/packet.h>
void proto_register_rlm(void);
void proto_reg_handoff_rlm(void);
/* Initialize the protocol and registered fields */
static int proto_rlm;
static int hf_rlm_version;
static int hf_rlm_type;
static int hf_rlm_unknown;
static int hf_rlm_tid;
static int hf_rlm_unknown2;
/* Initialize the subtree pointers */
static int ett_rlm;
/* RLM definitions - missing some! */
#define RLM_START_REQUEST 1
#define RLM_START_ACK 2
/* #define ??? 3 */
/* #define ??? 4 */
#define RLM_ECHO_REQUEST 5
#define RLM_ECHO_REPLY 6
/* #define ??? ?? */
/* Code to actually dissect the packets */
static bool
dissect_rlm(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_item *ti;
proto_tree *rlm_tree;
uint8_t rlm_type, version;
const char *type_str = NULL;
if (pinfo->srcport < 3000 || pinfo->srcport > 3015
|| pinfo->destport < 3000 || pinfo->destport > 3015
|| pinfo->destport != pinfo->srcport)
return false;
if (tvb_captured_length(tvb) < 2)
return false;
version = tvb_get_uint8(tvb, 0);
rlm_type = tvb_get_uint8(tvb, 1);
/* we only know about version 2, and I've only seen 8 byte packets */
if (tvb_captured_length(tvb) != 8 || version != 2) {
return false;
}
col_set_str(pinfo->cinfo, COL_PROTOCOL, "RLM");
switch (rlm_type) {
case RLM_START_REQUEST:
type_str = "Start request";
break;
case RLM_START_ACK:
type_str = "Start acknowledgement";
break;
case RLM_ECHO_REQUEST:
type_str = "Echo request";
break;
case RLM_ECHO_REPLY:
type_str = "Echo reply";
break;
default:
type_str = "Unknown type";
break;
}
col_set_str(pinfo->cinfo, COL_INFO, type_str);
if (tree) {
/* proto_tree_add_protocol_format(tree, proto_rlm, tvb, 0,
16, "Cisco Session Management"); */
ti = proto_tree_add_item(tree, proto_rlm, tvb, 0, 8, ENC_NA);
rlm_tree = proto_item_add_subtree(ti, ett_rlm);
proto_tree_add_item(rlm_tree, hf_rlm_version, tvb, 0, 1, ENC_BIG_ENDIAN);
proto_tree_add_uint_format_value(rlm_tree, hf_rlm_type, tvb, 1, 1, rlm_type, "%u (%s)", rlm_type, type_str);
proto_tree_add_item(rlm_tree, hf_rlm_unknown, tvb, 2, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(rlm_tree, hf_rlm_tid, tvb, 4, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(rlm_tree, hf_rlm_unknown2, tvb, 6, 2, ENC_BIG_ENDIAN);
}
return true;
}
/* Register the protocol with Wireshark */
/* this format is require because a script is used to build the C function
that calls all the protocol registration.
*/
void
proto_reg_handoff_rlm(void)
{
heur_dissector_add("udp", dissect_rlm, "Redundant Link Management over UDP", "rlm_udp", proto_rlm, HEURISTIC_ENABLE);
}
void
proto_register_rlm(void)
{
/* Setup list of header fields See Section 1.6.1 for details*/
static hf_register_info hf[] = {
{ &hf_rlm_version,
{ "Version", "rlm.version",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_rlm_type,
{ "Type", "rlm.type",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_rlm_unknown,
{ "Unknown", "rlm.unknown",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_rlm_tid,
{ "Transaction ID", "rlm.tid",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_rlm_unknown2,
{ "Unknown", "rlm.unknown2",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
};
/* Setup protocol subtree array */
static int *ett[] = {
&ett_rlm,
};
/* Register the protocol name and description */
proto_rlm = proto_register_protocol("Redundant Link Management Protocol",
"RLM", "rlm");
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_rlm, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
/*
* 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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