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/* packet-atn-cm.c
* By Mathias Guettler <guettler@web.de>
* Copyright 2013
*
* Routines for ATN context management protocol packet disassembly.
* ATN context management allows an aircraft
* to log on to a ground facility.
* details see:
* http://en.wikipedia.org/wiki/CPDLC
* http://members.optusnet.com.au/~cjr/introduction.htm
* standards:
* http://legacy.icao.int/anb/panels/acp/repository.cfm
* note:
* We are dealing with ATN/CPDLC aka ICAO Doc 9705 Ed2 here
* (CPDLC may also be transmitted via ACARS/AOA aka "FANS-1/A ").
* 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 "packet-ber.h"
#include "packet-per.h"
#include "packet-atn-ulcs.h"
#define ATN_CM_PROTO "ICAO Doc9705 CM"
void proto_register_atn_cm(void);
void proto_reg_handoff_atn_cm(void);
#include "packet-atn-cm-hf.c"
#include "packet-atn-cm-ett.c"
static gint ett_atn_cm = -1;
#include "packet-atn-cm-fn.c"
static int proto_atn_cm = -1;
static int
dissect_atn_cm(
tvbuff_t *tvb,
packet_info *pinfo,
proto_tree *tree,
void *data _U_)
{
int type;
proto_tree *sub_tree;
sub_tree = proto_tree_add_subtree(
tree, tvb, 0, -1, ett_atn_cm, NULL, ATN_CM_PROTO);
/* ti = proto_tree_add_item(tree, proto_atn_cm, tvb, 0, 0 , ENC_NA); */
/* sub_tree = proto_item_add_subtree(ti, ett_atn_cm_pdu); */
/* determine whether it is uplink or downlink */
type = check_heur_msg_type(pinfo);
switch(type){
case um:
dissect_CMGroundMessage_PDU(
tvb,
pinfo,
sub_tree, NULL);
break;
case dm:
dissect_CMAircraftMessage_PDU(
tvb,
pinfo,
sub_tree, NULL);
break;
default:
break;
}
return tvb_reported_length_remaining(tvb, 0);
}
static gboolean
dissect_atn_cm_heur(
tvbuff_t *tvb,
packet_info *pinfo,
proto_tree *tree,
void *data _U_)
{
atn_conversation_t *volatile atn_cv = NULL;
volatile gboolean is_atn_cm = FALSE;
int type;
/* determine whether it is uplink or downlink */
type = check_heur_msg_type(pinfo);
/* heuristically decode message */
switch(type){
case um:
TRY {
dissect_CMGroundMessage_PDU(
tvb,
pinfo,
NULL, NULL);
/* no exception thrown: looks like it is a CM PDU */
is_atn_cm = TRUE; }
CATCH_ALL {
is_atn_cm = FALSE; }
ENDTRY;
break;
case dm:
TRY {
dissect_CMAircraftMessage_PDU(
tvb,
pinfo,
NULL, NULL);
/* no exception thrown: looks like it is a CM PDU */
is_atn_cm = TRUE;}
CATCH_ALL {
is_atn_cm = FALSE; }
ENDTRY;
break;
default:
break;
}
if (is_atn_cm == TRUE) {
/* note: */
/* all subsequent PDU's belonging to this conversation are considered CM */
/* if the first CM PDU has been decoded successfully */
/* (This is done in "atn-ulcs" by using "call_dissector_with_data()") */
/* DT: dstref present, srcref is always zero */
if((pinfo->clnp_dstref) &&
(!pinfo->clnp_srcref)){
atn_cv = find_atn_conversation(
&pinfo->dst,
pinfo->clnp_dstref,
&pinfo->src );
}
/* CR: srcref present, dstref is always zero */
if((!pinfo->clnp_dstref) &&
(pinfo->clnp_srcref)){
atn_cv = find_atn_conversation(
&pinfo->src,
pinfo->clnp_srcref,
&pinfo->dst );
}
/* CC: srcref and dstref present */
if((pinfo->clnp_dstref) &&
(pinfo->clnp_srcref)){
atn_cv = find_atn_conversation(
&pinfo->src,
pinfo->clnp_srcref,
&pinfo->dst );
}
if(atn_cv){
atn_cv->ae_qualifier = cma;
}
dissect_atn_cm(
tvb,
pinfo,
tree,
NULL);
}
return is_atn_cm;
}
void proto_register_atn_cm (void)
{
static hf_register_info hf_atn_cm[] = {
#include "packet-atn-cm-hfarr.c"
};
static gint *ett[] = {
#include "packet-atn-cm-ettarr.c"
&ett_atn_cm
};
/* register CM application */
proto_atn_cm = proto_register_protocol(ATN_CM_PROTO, "ATN-CM", "atn-cm");
proto_register_field_array(
proto_atn_cm,
hf_atn_cm,
array_length(hf_atn_cm));
proto_register_subtree_array(
ett,
array_length(ett));
register_dissector(
"atn-cm",
dissect_atn_cm,
proto_atn_cm);
}
void proto_reg_handoff_atn_cm(void)
{
/* add session dissector to subdissector list*/
heur_dissector_add(
"atn-ulcs",
dissect_atn_cm_heur,
"ATN-CM over ATN-ULCS",
"atn-cm-ulcs",
proto_atn_cm, 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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