/* 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
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#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 *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  -  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:
 */