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/* packet-t125.c
* Routines for t125 packet dissection
* Copyright 2007, Ronnie Sahlberg
*
* 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/exceptions.h>
#include <wsutil/array.h>
#include <epan/asn1.h>
#include "packet-ber.h"
#include "packet-per.h"
#include "packet-t124.h"
#define PNAME "MULTIPOINT-COMMUNICATION-SERVICE T.125"
#define PSNAME "T.125"
#define PFNAME "t125"
#define HF_T125_ERECT_DOMAIN_REQUEST 1
#define HF_T125_DISCONNECT_PROVIDER_ULTIMATUM 8
#define HF_T125_ATTACH_USER_REQUEST 10
#define HF_T125_ATTACH_USER_CONFIRM 11
#define HF_T125_CHANNEL_JOIN_REQUEST 14
#define HF_T125_CHANNEL_JOIN_CONFIRM 15
#define HF_T125_SEND_DATA_REQUEST 25
#define HF_T125_SEND_DATA_INDICATION 26
void proto_register_t125(void);
void proto_reg_handoff_t125(void);
/* Initialize the protocol and registered fields */
static int proto_t125;
static proto_tree *top_tree;
#include "packet-t125-hf.c"
/* Initialize the subtree pointers */
static int ett_t125;
#include "packet-t125-ett.c"
static heur_dissector_list_t t125_heur_subdissector_list;
#include "packet-t125-fn.c"
static int
dissect_t125(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_)
{
proto_item *item = NULL;
proto_tree *tree = NULL;
int8_t ber_class;
bool pc;
int32_t tag;
top_tree = parent_tree;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "T.125");
col_clear(pinfo->cinfo, COL_INFO);
item = proto_tree_add_item(parent_tree, proto_t125, tvb, 0, tvb_captured_length(tvb), ENC_NA);
tree = proto_item_add_subtree(item, ett_t125);
get_ber_identifier(tvb, 0, &ber_class, &pc, &tag);
if ( (ber_class==BER_CLASS_APP) && (tag>=101) && (tag<=104) ){
dissect_ConnectMCSPDU_PDU(tvb, pinfo, tree, NULL);
} else {
t124_set_top_tree(top_tree);
dissect_DomainMCSPDU_PDU(tvb, pinfo, tree);
}
return tvb_captured_length(tvb);
}
static bool
dissect_t125_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_)
{
int8_t ber_class;
bool pc;
int32_t tag;
volatile bool failed;
/*
* We must catch all the "ran past the end of the packet" exceptions
* here and, if we catch one, just return false. It's too painful
* to have a version of dissect_per_sequence() that checks all
* references to the tvbuff before making them and returning "no"
* if they would fail.
*/
failed = false;
TRY {
/* could be BER */
get_ber_identifier(tvb, 0, &ber_class, &pc, &tag);
} CATCH_BOUNDS_ERRORS {
failed = true;
} ENDTRY;
if (failed) {
return false;
}
if (((ber_class==BER_CLASS_APP) && ((tag>=101) && (tag<=104)))) {
dissect_t125(tvb, pinfo, parent_tree, NULL);
return true;
}
/*
* Check that the first byte of the packet is a valid t125/MCS header.
* This might not be enough, but since t125 only catch COTP packets,
* it should not be a problem.
*/
uint8_t first_byte = tvb_get_uint8(tvb, 0) >> 2;
switch (first_byte) {
case HF_T125_ERECT_DOMAIN_REQUEST:
case HF_T125_ATTACH_USER_REQUEST:
case HF_T125_ATTACH_USER_CONFIRM:
case HF_T125_CHANNEL_JOIN_REQUEST:
case HF_T125_CHANNEL_JOIN_CONFIRM:
case HF_T125_DISCONNECT_PROVIDER_ULTIMATUM:
case HF_T125_SEND_DATA_REQUEST:
case HF_T125_SEND_DATA_INDICATION:
dissect_t125(tvb, pinfo, parent_tree, NULL);
return true;
}
return false;
}
/*--- proto_register_t125 -------------------------------------------*/
void proto_register_t125(void) {
/* List of fields */
static hf_register_info hf[] = {
#include "packet-t125-hfarr.c"
};
/* List of subtrees */
static int *ett[] = {
&ett_t125,
#include "packet-t125-ettarr.c"
};
/* Register protocol */
proto_t125 = proto_register_protocol(PNAME, PSNAME, PFNAME);
/* Register fields and subtrees */
proto_register_field_array(proto_t125, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
t125_heur_subdissector_list= register_heur_dissector_list_with_description("t125", "T.125 User data", proto_t125);
register_dissector("t125", dissect_t125, proto_t125);
}
/*--- proto_reg_handoff_t125 ---------------------------------------*/
void proto_reg_handoff_t125(void) {
heur_dissector_add("cotp", dissect_t125_heur, "T.125 over COTP", "t125_cotp", proto_t125, HEURISTIC_ENABLE);
heur_dissector_add("cotp_is", dissect_t125_heur, "T.125 over COTP (inactive subset)", "t125_cotp_is", proto_t125, HEURISTIC_ENABLE);
}
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