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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  -  http://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:
 */