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/* packet-t124.c
* Routines for t124 packet dissection
* Copyright 2010, Graeme Lunt
*
* 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 <epan/conversation.h>
#include <wsutil/array.h>
#include <epan/asn1.h>
#include "packet-per.h"
#include "packet-ber.h"
#include "packet-t124.h"
#ifdef _MSC_VER
/* disable: "warning C4146: unary minus operator applied to unsigned type, result still unsigned" */
#pragma warning(disable:4146)
#endif
#define PNAME "GENERIC-CONFERENCE-CONTROL T.124"
#define PSNAME "T.124"
#define PFNAME "t124"
void proto_register_t124(void);
void proto_reg_handoff_t124(void);
/* Initialize the protocol and registered fields */
static int proto_t124;
static proto_tree *top_tree;
#include "packet-t124-hf.c"
/* Initialize the subtree pointers */
static int ett_t124;
static int ett_t124_connectGCCPDU;
static int hf_t124_ConnectData;
static int hf_t124_connectGCCPDU;
static int hf_t124_DomainMCSPDU_PDU;
static uint32_t channelId = -1;
static dissector_table_t t124_ns_dissector_table;
static dissector_table_t t124_sd_dissector_table;
#include "packet-t124-ett.c"
#include "packet-t124-fn.c"
static const per_sequence_t t124Heur_sequence[] = {
{ &hf_t124_t124Identifier , ASN1_NO_EXTENSIONS , ASN1_NOT_OPTIONAL, dissect_t124_Key },
{ NULL, 0, 0, NULL }
};
void
register_t124_ns_dissector(const char *nsKey, dissector_t dissector, int proto)
{
dissector_handle_t dissector_handle;
dissector_handle=create_dissector_handle(dissector, proto);
dissector_add_string("t124.ns", nsKey, dissector_handle);
}
void register_t124_sd_dissector(packet_info *pinfo _U_, uint32_t channelId_param, dissector_t dissector, int proto)
{
/* XXX: we should keep the sub-dissectors list per conversation
as the same channels may be used.
While we are just using RDP over T.124, then we can get away with it.
*/
dissector_handle_t dissector_handle;
dissector_handle=create_dissector_handle(dissector, proto);
dissector_add_uint("t124.sd", channelId_param, dissector_handle);
}
uint32_t t124_get_last_channelId(void)
{
return channelId;
}
void t124_set_top_tree(proto_tree *tree)
{
top_tree = tree;
}
int dissect_DomainMCSPDU_PDU(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
int offset = 0;
asn1_ctx_t asn1_ctx;
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, true, pinfo);
offset = dissect_t124_DomainMCSPDU(tvb, offset, &asn1_ctx, tree, hf_t124_DomainMCSPDU_PDU);
offset += 7; offset >>= 3;
return offset;
}
static int
dissect_t124(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_)
{
proto_item *item = NULL;
proto_tree *tree = NULL;
asn1_ctx_t asn1_ctx;
top_tree = parent_tree;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "T.124");
col_clear(pinfo->cinfo, COL_INFO);
item = proto_tree_add_item(parent_tree, proto_t124, tvb, 0, tvb_captured_length(tvb), ENC_NA);
tree = proto_item_add_subtree(item, ett_t124);
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, true, pinfo);
dissect_t124_ConnectData(tvb, 0, &asn1_ctx, tree, hf_t124_ConnectData);
return tvb_captured_length(tvb);
}
static bool
dissect_t124_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data)
{
asn1_ctx_t asn1_ctx;
volatile bool failed = false;
asn1_ctx_init(&asn1_ctx, ASN1_ENC_PER, true, pinfo);
/*
* 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.
*
* We (ab)use hf_t124_connectGCCPDU here just to give a valid entry...
*/
TRY {
(void) dissect_per_sequence(tvb, 0, &asn1_ctx, NULL, hf_t124_connectGCCPDU, -1, t124Heur_sequence);
} CATCH_BOUNDS_ERRORS {
failed = true;
} ENDTRY;
if (!failed && ((asn1_ctx.external.direct_reference != NULL) &&
(strcmp(asn1_ctx.external.direct_reference, "0.0.20.124.0.1") == 0))) {
dissect_t124(tvb, pinfo, parent_tree, data);
return true;
}
return false;
}
/*--- proto_register_t124 -------------------------------------------*/
void proto_register_t124(void) {
/* List of fields */
static hf_register_info hf[] = {
{ &hf_t124_ConnectData,
{ "ConnectData", "t124.ConnectData",
FT_NONE, BASE_NONE, NULL, 0,
NULL, HFILL }},
{ &hf_t124_connectGCCPDU,
{ "connectGCCPDU", "t124.connectGCCPDU",
FT_UINT32, BASE_DEC, VALS(t124_ConnectGCCPDU_vals), 0,
NULL, HFILL }},
{ &hf_t124_DomainMCSPDU_PDU,
{ "DomainMCSPDU", "t124.DomainMCSPDU",
FT_UINT32, BASE_DEC, VALS(t124_DomainMCSPDU_vals), 0,
NULL, HFILL }},
#include "packet-t124-hfarr.c"
};
/* List of subtrees */
static int *ett[] = {
&ett_t124,
&ett_t124_connectGCCPDU,
#include "packet-t124-ettarr.c"
};
/* Register protocol */
proto_t124 = proto_register_protocol(PNAME, PSNAME, PFNAME);
/* Register fields and subtrees */
proto_register_field_array(proto_t124, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
t124_ns_dissector_table = register_dissector_table("t124.ns", "T.124 H.221 Non Standard Dissectors", proto_t124, FT_STRING, STRING_CASE_SENSITIVE);
t124_sd_dissector_table = register_dissector_table("t124.sd", "T.124 H.221 Send Data Dissectors", proto_t124, FT_UINT32, BASE_HEX);
register_dissector("t124", dissect_t124, proto_t124);
}
void
proto_reg_handoff_t124(void) {
register_ber_oid_dissector("0.0.20.124.0.1", dissect_t124, proto_t124, "Generic Conference Control");
heur_dissector_add("t125", dissect_t124_heur, "T.124 over T.125", "t124_t125", proto_t124, HEURISTIC_ENABLE);
}
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