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wireshark/epan/dissectors/asn1/atn-cpdlc/packet-atn-cpdlc-template.c

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/* packet-atn-cpdlc-template.c
* By Mathias Guettler <guettler@web.de>
* Copyright 2013
*
* Routines for ATN Cpdlcc protocol packet disassembly
* 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
*/
/*
developper comments:
Which CPDLC messages are supported ?
Protected Mode CPDLC (AeQualifier 22) and Plain Old CPDLC (AeQualifier 2)
The dissector has been tested with ICAO doc9705 Edition2 compliant traffic.
*/
#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_CPDLC_PROTO "ICAO Doc9705 CPDLC"
void proto_register_atn_cpdlc(void);
void proto_reg_handoff_atn_cpdlc(void);
static const char *object_identifier_id;
/* IA5 charset (7-bit) for PER IA5 decoding */
static const gchar ia5alpha[] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, \
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, \
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, \
0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, \
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, \
0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, \
0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, \
0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, \
0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, '\0'
};
/* forward declarations */
static int dissect_GroundPDUs_PDU(
tvbuff_t *tvb _U_,
packet_info *pinfo _U_,
proto_tree *tree _U_,
void *data _U_);
static int dissect_AircraftPDUs_PDU(
tvbuff_t *tvb _U_,
packet_info *pinfo _U_,
proto_tree *tree _U_,
void *data _U_);
static int dissect_ProtectedGroundPDUs_PDU(
tvbuff_t *tvb _U_,
packet_info *pinfo _U_,
proto_tree *tree _U_,
void *data _U_);
static int dissect_ProtectedAircraftPDUs_PDU(
tvbuff_t *tvb _U_,
packet_info *pinfo _U_,
proto_tree *tree _U_,
void *data _U_);
#include "packet-atn-cpdlc-hf.c"
#include "packet-atn-cpdlc-ett.c"
static gint ett_atn_cpdlc = -1;
#include "packet-atn-cpdlc-fn.c"
/* Wireshark ID of CPDLC protocol */
static int proto_atn_cpdlc = -1;
static int
dissect_atn_cpdlc(
tvbuff_t *tvb,
packet_info *pinfo,
proto_tree *tree,
void *data _U_)
{
/* note: */
/* there are two co-existing applications of CPDLC: */
/* "plain old" (ae-qualifier 2) and */
/* "protected mode" (ae-qualifier 22) CPDLC. */
/* "protected mode" was introduced to cope with a */
/* safety issue in which a message would sent to the wrong aircraft. */
/* note:*/
/* The protection is an additional checksum and covers the message content, */
/* the 24-bit address of the aircraft, the current flight id and */
/* the current ground facility so that an aircraft would be able to reject */
/* messages which are unexpected (i.e. messages to another flight or */
/* messages from the wrong center). */
/*note:*/
/* although "plain old" CPDLC is more or less deprecated */
/* many aircraft cannot perform */
/* "protected mode" for this largely depends on */
/* upgraded avionics packages */
/*note:*/
/* The use of CPDLC is *optional* as the pilot */
/* may always use a voice radio channel to talk to the controller.*/
proto_tree *atn_cpdlc_tree = NULL;
atn_conversation_t *atn_cv = NULL;
/* note: */
/* we need the ae qualifier stored within the conversation */
/* to decode "plain old cpdlc" or */
/* "protected mode cpdlc correctly " */
/* 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, always use src/srcref & dst */
if((pinfo->clnp_dstref) && (pinfo->clnp_srcref)){
atn_cv = find_atn_conversation(
&pinfo->src,
pinfo->clnp_srcref,
&pinfo->dst );
}
if(!atn_cv){ /* atn conversation not found */
return 0; }
atn_cpdlc_tree = proto_tree_add_subtree(
tree, tvb, 0, -1, ett_atn_cpdlc, NULL,
ATN_CPDLC_PROTO );
switch(atn_cv->ae_qualifier){
case pmcpdlc:
if( check_heur_msg_type(pinfo) == um ) {
/* uplink PDU's = Ground PDU's */
dissect_ProtectedGroundPDUs_PDU(
tvb,
pinfo,
atn_cpdlc_tree, NULL);
}else { /* downlink PDU's = Aircraft PDU's */
dissect_ProtectedAircraftPDUs_PDU(
tvb,
pinfo,
atn_cpdlc_tree, NULL);
}
break;
case cpdlc:
if( check_heur_msg_type(pinfo) == um ) {
/* uplink PDU's = Ground PDU's */
dissect_GroundPDUs_PDU(
tvb,
pinfo,
atn_cpdlc_tree, NULL);
}else { /* downlink PDU's = Aircraft PDU's */
dissect_AircraftPDUs_PDU(
tvb,
pinfo,
atn_cpdlc_tree, NULL);
}
break;
default:
break;
}
return tvb_reported_length_remaining(tvb, 0);
}
static gboolean
dissect_atn_cpdlc_heur(
tvbuff_t *tvb,
packet_info *pinfo,
proto_tree *tree,
void *data _U_)
{
atn_conversation_t *volatile atn_cv = NULL;
volatile gboolean is_atn_cpdlc = FALSE;
volatile gboolean is_pm = FALSE;
int type;
type = check_heur_msg_type(pinfo);
switch(type){
case um:
TRY {
dissect_ProtectedGroundPDUs_PDU(tvb, pinfo, NULL, NULL);
is_atn_cpdlc = TRUE;
is_pm = TRUE;}
CATCH_ALL{
is_atn_cpdlc = FALSE;
is_pm = FALSE;}
ENDTRY;
if (is_atn_cpdlc) {
break;
}
TRY {
dissect_GroundPDUs_PDU(tvb, pinfo, NULL, NULL);
is_pm = FALSE;
is_atn_cpdlc = TRUE;}
CATCH_ALL{
is_atn_cpdlc = FALSE;
is_pm = FALSE;}
ENDTRY;
break;
case dm:
TRY {
dissect_ProtectedAircraftPDUs_PDU(tvb, pinfo, NULL, NULL);
is_atn_cpdlc = TRUE;
is_pm = TRUE;}
CATCH_ALL {
is_atn_cpdlc = FALSE;
is_pm = FALSE; }
ENDTRY;
if (is_atn_cpdlc) {
break;
}
TRY{
dissect_AircraftPDUs_PDU(tvb, pinfo, NULL, NULL);
is_atn_cpdlc = TRUE;
is_pm = FALSE;}
CATCH_ALL{
is_atn_cpdlc = FALSE;
is_pm = FALSE;}
ENDTRY;
break;
default:
break;
}
if(is_atn_cpdlc){
/* note: */
/* all subsequent PDU's belonging to this conversation */
/* are considered CPDLC */
/* if the first CPDLC 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, always use src/srcref & dst */
if((pinfo->clnp_dstref) && (pinfo->clnp_srcref)){
atn_cv = find_atn_conversation(&pinfo->src,
pinfo->clnp_srcref,
&pinfo->dst );
}
if(atn_cv){ /* atn conversation found */
if(is_pm == TRUE) {
atn_cv->ae_qualifier = pmcpdlc; }
else {
atn_cv->ae_qualifier = cpdlc; }
dissect_atn_cpdlc(tvb, pinfo, tree, NULL);
}
}else { /* there should *always* be an atn conversation */
is_atn_cpdlc = FALSE;
}
return is_atn_cpdlc;
}
void proto_register_atn_cpdlc (void)
{
static hf_register_info hf_atn_cpdlc[] = {
#include "packet-atn-cpdlc-hfarr.c"
};
static gint *ett[] = {
#include "packet-atn-cpdlc-ettarr.c"
&ett_atn_cpdlc
};
/* register CPDLC */
proto_atn_cpdlc = proto_register_protocol(
ATN_CPDLC_PROTO ,
"ATN-CPDLC",
"atn-cpdlc");
proto_register_field_array(
proto_atn_cpdlc,
hf_atn_cpdlc,
array_length(hf_atn_cpdlc));
proto_register_subtree_array(
ett,
array_length(ett));
register_dissector(
"atn-cpdlc",
dissect_atn_cpdlc,
proto_atn_cpdlc);
}
void proto_reg_handoff_atn_cpdlc(void)
{
/* add session dissector to atn dissector list dissector list*/
heur_dissector_add(
"atn-ulcs",
dissect_atn_cpdlc_heur,
"ATN-CPDLC over ATN-ULCS",
"atn-cpdlc-ulcs",
proto_atn_cpdlc, 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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