/* packet-gsm_r_uus1.c

 * Routines for GSM-R UUS1 dissection

 *

 * Copyright 2018, Michail Koreshkov <michail.koreshkov [at] bk.ru

 *

 * Reference [1]

 * Railways Telecommunications (RT);

 * Global System for Mobile communications (GSM);

 * Usage of the User-to-User Information Element

 * for GSM Operation on Railways

 * (ETSI TS 102 610 V1.2.0 (2012-08))

 *

 * Reference [2]

 * EIRENE SRS: "UIC Project EIRENE System Requirements Specification".

 *

 * Reference [3]

 * MORANE F 10 T 6003 4: "FFFS for Presentation of Functional Numbers

 * to Called and Calling Parties".

 *

 * Reference [4]

 * eLDA IRS (V5.0): "Interface Requirements Specification

 * enhanced Location Dependent Addressing".

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/expert.h>

#include <epan/tfs.h>

#include <epan/prefs.h>

/* forward reference */

void proto_register_gsm_r_uus1(void);

void proto_reg_handoff_gsm_r_uus1(void);

/* Initialize the protocol and registered fields */

static int proto_gsm_r_uus1;

static int hf_gsm_r_uus1_elem_tag;

static int hf_gsm_r_uus1_elem_len;

static int hf_gsm_r_uus1_pfn;

static int hf_gsm_r_uus1_pfn_digits;

/* 5.2 and 5.3 */

static int hf_gsm_r_uus1_chpc;

static int hf_gsm_r_uus1_chpc_t_dur;

static int hf_gsm_r_uus1_chpc_t_rel;

static int hf_gsm_r_uus1_chpc_pl_call;

static int hf_gsm_r_uus1_chpc_cause;

static int hf_gsm_r_uus1_chpc_cause_power;

static int hf_gsm_r_uus1_chpc_cause_radio;

static int hf_gsm_r_uus1_chpc_cause_reserved3;

static int hf_gsm_r_uus1_chpc_cause_reserved4;

static int hf_gsm_r_uus1_chpc_cause_user_command;

static int hf_gsm_r_uus1_chpc_cause_reserved6;

static int hf_gsm_r_uus1_chpc_cause_reserved7;

static int hf_gsm_r_uus1_chpc_cause_reserved8;

static int hf_gsm_r_uus1_chpc_gref;

static int hf_gsm_r_uus1_chpc_ack_cause;

/* 5.4 */

static int hf_gsm_r_uus1_epfn;

/* 5.5 */

static int hf_gsm_r_uus1_present_text_str;

/* 5.6 */

static int hf_gsm_r_uus1_elda;

static int hf_gsm_r_uus1_elda_lat;

static int hf_gsm_r_uus1_elda_lat_deg;

static int hf_gsm_r_uus1_elda_lat_min;

static int hf_gsm_r_uus1_elda_lat_sec;

static int hf_gsm_r_uus1_elda_lat_hem;

static int hf_gsm_r_uus1_elda_long;

static int hf_gsm_r_uus1_elda_long_deg;

static int hf_gsm_r_uus1_elda_long_min;

static int hf_gsm_r_uus1_elda_long_sec;

static int hf_gsm_r_uus1_elda_long_hem;

static int hf_gsm_r_uus1_elda_height;

static int hf_gsm_r_uus1_elda_speed;

static int hf_gsm_r_uus1_elda_heading;

static int hf_gsm_r_uus1_elda_e_time;

static int hf_gsm_r_uus1_elda_distance;

static int hf_gsm_r_uus1_elda_scale;

static int hf_gsm_r_uus1_elda_spare;

/* 5.7 */

static int hf_gsm_r_uus1_present_dsd_alarm;

static int hf_gsm_r_uus1_present_dsd_alarm_loco_number;

/* 5.8 */

static int hf_gsm_r_uus1_alert_controller;

static int hf_gsm_r_uus1_alert_controller_gref;

/* Initialize the subtree pointers */

static int ett_gsm_r_uus1;

static int ett_gsm_r_uus1_pfn;

static int ett_gsm_r_uus1_chpc;

static int ett_gsm_r_uus1_chpc_cause;

static int ett_gsm_r_uus1_epfn;

static int ett_gsm_r_uus1_present_text_str;

static int ett_gsm_r_uus1_elda;

static int ett_gsm_r_uus1_elda_lat;

static int ett_gsm_r_uus1_elda_long;

static int ett_gsm_r_uus1_present_dsd_alarm;

static int ett_gsm_r_uus1_alert_controller;

/* Preferences */

static bool q931_u2u;

static bool gsm_a_u2u = true;

static expert_field ei_gsm_r_uus1_not_implemented_yet;

static const value_string gsm_r_uus1_tags[] = {

    { 2,  "Acknowledgement by Receiver of a HPC and response from device accepting the acknowledgement" },

    { 3,  "Acknowledgement by Initiator of a HPC" },

    { 5,  "Presentation of Functional Number" },

    { 6,  "enhanced Location Dependent Addressing" },

    { 7,  "enhanced Location Dependent Addressing (Reserved for future use)" },

    { 8,  "enhanced Location Dependent Addressing (Reserved for future use)" },

    { 9,  "ePFN Information" },

    { 10, "User specific plain text according to alphabet indicator" },

    { 11, "DSD Alarm Notification" },

    { 12, "Alerting of a Controller Notification and Response" },

    { 0, NULL }

};

/*

 * 5.1 Presentation of functional number

 *

 */

static uint16_t

de_gsm_r_uus1_pfn(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, uint32_t offset)

{

    uint32_t  curr_offset;

    uint32_t  len;

    const char *fn_str;

    proto_item *item;

    proto_tree *sub_tree;

    curr_offset = offset;

    len = tvb_get_uint8(tvb, offset+1);

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_pfn, tvb, curr_offset, len+2, ENC_NA);

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_pfn);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, curr_offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_len, tvb, curr_offset+1, 1, ENC_NA);

    curr_offset += 2;

    if(len == 0) {

        proto_item_append_text(item, ": No FN Available");

    }else {

        fn_str = tvb_bcd_dig_to_str(pinfo->pool, tvb, offset+2, len, NULL, false);

        proto_tree_add_string(sub_tree, hf_gsm_r_uus1_pfn_digits, tvb, curr_offset, len, fn_str);

        proto_item_append_text(item, ": %s", fn_str);

        curr_offset += len;

    }

    return (curr_offset - offset);

}

/*

 * 5.2 Confirmation of High Priority Calls

 *

 */

static const range_string gsm_r_uus1_chpc_priority_vals[] = {

    { 0x00, 0x00, "no priority specified in call"},

    { 0x01, 0x01, "eMLPP priority of 4 (Railway Information)"},

    { 0x02, 0x02, "eMLPP priority of 3 (Railway Operation)"},

    { 0x03, 0x03, "eMLPP priority of 2 (Public Emergency/Group Calls)"},

    { 0x04, 0x04, "eMLPP priority of 1 (Command and Control)"},

    { 0x05, 0x05, "eMLPP priority of 0 (Railway Emergency)"},

    { 0x06, 0x07, "unknown" },

    { 0, 0, NULL }

};

static uint16_t

de_gsm_r_uus1_chpc_forward(tvbuff_t *tvb, proto_tree *tree, uint32_t offset)

{

    uint32_t  curr_offset;

    uint32_t  len;

    uint32_t t_dur;

    uint32_t t_rel;

    proto_item *item;

    proto_tree *sub_tree;

    curr_offset = offset;

    len = tvb_get_uint8(tvb, offset+1);

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_chpc, tvb, curr_offset, len+2, ENC_NA);

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_chpc);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, curr_offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_len, tvb, curr_offset+1, 1, ENC_NA);

    curr_offset += 2;

    t_dur = tvb_get_uint24(tvb, curr_offset, ENC_LITTLE_ENDIAN);

    proto_tree_add_uint_format_value(sub_tree, hf_gsm_r_uus1_chpc_t_dur, tvb, curr_offset, 3, t_dur, "%d ms", t_dur*100);

    curr_offset += 3;

    t_rel = tvb_get_uint32(tvb, curr_offset, ENC_LITTLE_ENDIAN);

    proto_tree_add_uint_format_value(sub_tree, hf_gsm_r_uus1_chpc_t_rel, tvb, curr_offset, 4, t_rel, "%d ms", t_rel*100);

    curr_offset += 4;

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_chpc_pl_call, tvb, curr_offset, 1, ENC_NA);

    curr_offset += 1;

    static int * const cause_flags[] = {

        &hf_gsm_r_uus1_chpc_cause_power,

        &hf_gsm_r_uus1_chpc_cause_radio,

        &hf_gsm_r_uus1_chpc_cause_reserved3,

        &hf_gsm_r_uus1_chpc_cause_reserved4,

        &hf_gsm_r_uus1_chpc_cause_user_command,

        &hf_gsm_r_uus1_chpc_cause_reserved6,

        &hf_gsm_r_uus1_chpc_cause_reserved7,

        &hf_gsm_r_uus1_chpc_cause_reserved8,

        NULL

    };

    proto_tree_add_bitmask(sub_tree, tvb, curr_offset, hf_gsm_r_uus1_chpc_cause, ett_gsm_r_uus1_chpc_cause, cause_flags, ENC_NA);

    curr_offset += 1;

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_chpc_gref, tvb, curr_offset, 4, ENC_BCD_DIGITS_0_9|ENC_LITTLE_ENDIAN);

    curr_offset += 4;

    return (curr_offset - offset);

}

/*

 * 5.3 CHPC tag definition for collecting network device

 *

 * The tag is included in a RELEASE_COMPLETE message

 * which shall have the release cause value of "Normal Call Clearing".

 *

 * gsm_a.dtap.msg_cc_type == 0x2a

 */

static const range_string gsm_r_uus1_chpc_ack_cause_vals[] = {

    { 0x00, 0x00, "ACK (no error)" },

    { 0x01, 0x01, "NACK-1 (error, repetition should take place)" },

    { 0x02, 0x7f, "Reserved for internal use" },

    { 0x80, 0x80, "NACK-2 (fatal error, NO repetition to take place)" },

    { 0x81, 0xff, "Reserved" },

    { 0, 0, NULL }

};

static uint16_t

de_gsm_r_uus1_chpc_collect(tvbuff_t *tvb, proto_tree *tree, uint32_t offset)

{

    proto_item *item;

    proto_tree *sub_tree;

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_chpc, tvb, offset, 2, ENC_NA);

    proto_item_set_text(item, "CHPC for collecting network device");

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_chpc);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_chpc_ack_cause, tvb, offset+1, 1, ENC_NA);

    return 2;

}

/*

 * Type of field depends on BSSAP message type. SETUP or RELEASE_COMPLETE

 * But I don't know how to verify message type.

 * That is why use length variable to find type of field

 */

static uint16_t

de_gsm_r_uus1_chpc(tvbuff_t *tvb, proto_tree *tree, uint32_t offset)

{

    uint8_t field_length;

    field_length = tvb_get_uint8(tvb, offset+1);

    if(field_length == 13)

        return de_gsm_r_uus1_chpc_forward(tvb, tree, offset);

    else

        return de_gsm_r_uus1_chpc_collect(tvb, tree, offset);

}

/*

 * 5.4 Enhanced presentation of functional number

 * (not implemented now)

 */

static uint16_t

de_gsm_r_uus1_epfn(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset)

{

    uint32_t  curr_offset;

    uint32_t  len;

    proto_item *item;

    proto_tree *sub_tree;

    curr_offset = offset;

    len = tvb_get_uint8(tvb, offset+1);

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_epfn, tvb, curr_offset, len+2, ENC_NA);

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_epfn);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, curr_offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_len, tvb, curr_offset+1, 1, ENC_NA);

    curr_offset += 2;

    proto_tree_add_expert(sub_tree, pinfo, &ei_gsm_r_uus1_not_implemented_yet, tvb, curr_offset, len);

    curr_offset += len;

    return (curr_offset - offset);

}

/*

 * 5.5 Presentation of text strings

 * (not implemented now)

 */

static uint16_t

de_gsm_r_uus1_text_str(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset)

{

    uint32_t  curr_offset;

    uint32_t  len;

    proto_item *item;

    proto_tree *sub_tree;

    curr_offset = offset;

    len = tvb_get_uint8(tvb, offset+1);

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_present_text_str, tvb, curr_offset, len+2, ENC_NA);

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_present_text_str);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, curr_offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_len, tvb, curr_offset+1, 1, ENC_NA);

    curr_offset += 2;

    proto_tree_add_expert(sub_tree, pinfo, &ei_gsm_r_uus1_not_implemented_yet, tvb, curr_offset, len);

    curr_offset += len;

    return (curr_offset - offset);

}

/*

 * 5.6 Transfer of train position (eLDA)

 *

 */

static const true_false_string gsm_r_uus1_elda_lat_hem = {

    "North",

    "South"

};

static const true_false_string gsm_r_uus1_elda_long_hem = {

    "West",

    "East"

};

static const value_string gsm_r_uus1_elda_scale_vals[] = {

    { 0,  "10 cm resolution" },

    { 1,  "1 metre resolution" },

    { 2,  "10 metre resolution" },

    { 3,  "Odometry information not valid" },

    { 0, NULL }

};

static uint16_t

de_gsm_r_uus1_elda(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset)

{

    uint32_t  curr_offset;

    unsigned   bit_offset;

    uint32_t lat_deg_val;

    uint32_t lat_min_val;

    uint32_t lat_sec_val;

    bool     lat_hem_val;

    uint32_t long_deg_val;

    uint32_t long_min_val;

    uint32_t long_sec_val;

    bool     long_hem_val;

    uint32_t t_val;

    proto_item *item;

    proto_tree *sub_tree;

    proto_item *lat_item;

    proto_item *long_item;

    proto_tree *lat_tree;

    proto_tree *long_tree;

    proto_item *lat_sec, *long_sec;

    curr_offset = offset;

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_elda, tvb, curr_offset, 16, ENC_NA);

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_elda);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, curr_offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_len, tvb, curr_offset+1, 1, ENC_NA);

    curr_offset += 2;

    /* Latitude (in subtree) - 27 bits */

    lat_item = proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elda_lat, tvb, curr_offset, 4, ENC_NA);

    lat_tree = proto_item_add_subtree(lat_item, ett_gsm_r_uus1_elda_lat);

    proto_tree_add_item_ret_uint(lat_tree, hf_gsm_r_uus1_elda_lat_deg, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &lat_deg_val);

    proto_tree_add_item_ret_uint(lat_tree, hf_gsm_r_uus1_elda_lat_min, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &lat_min_val);

    lat_sec = proto_tree_add_item_ret_uint(lat_tree, hf_gsm_r_uus1_elda_lat_sec, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &lat_sec_val);

    proto_item_append_text(lat_sec, " (%.2f)", (float)(lat_sec_val)/100);

    proto_tree_add_item_ret_boolean(lat_tree, hf_gsm_r_uus1_elda_lat_hem, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &lat_hem_val);

    /* Add details to subtree */

    proto_item_set_text(lat_item, "Latitude: %d %d\'%.2f\"%s", lat_deg_val, lat_min_val, (float)(lat_sec_val)/100,

        lat_hem_val ? "N" : "S");

    /* Move past 3 bytes */

    curr_offset += 3;

    /* Longitude (in subtree) - 28 bits */

    long_item = proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elda_long, tvb, curr_offset, 4, ENC_NA);

    long_tree = proto_item_add_subtree(long_item, ett_gsm_r_uus1_elda_long);

    proto_tree_add_item_ret_uint(long_tree, hf_gsm_r_uus1_elda_long_deg, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &long_deg_val);

    proto_tree_add_item_ret_uint(long_tree, hf_gsm_r_uus1_elda_long_min, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &long_min_val);

    long_sec = proto_tree_add_item_ret_uint(long_tree, hf_gsm_r_uus1_elda_long_sec, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &long_sec_val);

    proto_item_append_text(long_sec, " (%.2f)", (float)(long_sec_val)/100);

    proto_tree_add_item_ret_boolean(long_tree, hf_gsm_r_uus1_elda_long_hem, tvb, curr_offset, 4, ENC_BIG_ENDIAN, &long_hem_val);

    /* Add details to subtree */

    proto_item_set_text(long_item, "Longitude: %d %d\'%.2f\"%s", long_deg_val, long_min_val, (float)(long_sec_val)/100,

        long_hem_val ? "W" : "E");

    curr_offset += 3;

    /* TODO: would be nice to add masks to the items below and dispense with messy calls to get bit values with explicit offsets */

    bit_offset = 55;

    /* Height, Speed, Heading */

    // height step 1m. Range: -100m...+4500m

    t_val = tvb_get_bits16(tvb, bit_offset, 13, ENC_BIG_ENDIAN) - 100;

    proto_tree_add_int(sub_tree, hf_gsm_r_uus1_elda_height, tvb, curr_offset, 4, t_val);

    bit_offset += 13;

    // speed step 10 km/h

    t_val = tvb_get_bits8(tvb, bit_offset, 6) * 10;

    proto_tree_add_uint(sub_tree, hf_gsm_r_uus1_elda_speed, tvb, curr_offset, 4, t_val);

    bit_offset += 6;

    // heading step 10 deg

    t_val = tvb_get_bits8(tvb, bit_offset, 6) * 10;

    proto_tree_add_uint(sub_tree, hf_gsm_r_uus1_elda_heading, tvb, curr_offset, 4, t_val);

    bit_offset += 6;

    curr_offset += 4;

    /* Elapsed Time, Distance, Scale, Spare */

    // time step 1 second. Range: 0...2047

    t_val = tvb_get_bits16(tvb, bit_offset, 11, ENC_BIG_ENDIAN);

    proto_tree_add_uint(sub_tree, hf_gsm_r_uus1_elda_e_time, tvb, curr_offset, 4, t_val);

    bit_offset += 11;

    // distance step = 10 cm, 1 m or 10 m depending on the parameter Scale

    t_val = tvb_get_bits16(tvb, bit_offset, 14, ENC_BIG_ENDIAN);

    proto_tree_add_uint(sub_tree, hf_gsm_r_uus1_elda_distance, tvb, curr_offset, 4, t_val);

    bit_offset += 14;

    // scale

    t_val = tvb_get_bits8(tvb, bit_offset, 2);

    proto_tree_add_uint(sub_tree, hf_gsm_r_uus1_elda_scale, tvb, curr_offset, 4, t_val);

    bit_offset += 2;

    // spare

    t_val = tvb_get_bits8(tvb, bit_offset, 5);

    proto_tree_add_uint(sub_tree, hf_gsm_r_uus1_elda_spare, tvb, curr_offset, 4, t_val);

    return 16;

}

/*

 * 5.7 Notification DSD alarm condition

 *

 */

static uint16_t

de_gsm_r_uus1_dsd_alarm(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset)

{

    uint32_t  curr_offset;

    uint32_t  len;

    const char *loco_engine_number;

    proto_item *item;

    proto_tree *sub_tree;

    curr_offset = offset;

    len = tvb_get_uint8(tvb, offset+1);

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_present_dsd_alarm, tvb, curr_offset, len+2, ENC_NA);

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_present_dsd_alarm);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, curr_offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_len, tvb, curr_offset+1, 1, ENC_NA);

    curr_offset += 2;

    loco_engine_number = tvb_bcd_dig_to_str(pinfo->pool, tvb, offset+2, len, NULL, false);

    proto_tree_add_string(sub_tree, hf_gsm_r_uus1_present_dsd_alarm_loco_number, tvb, curr_offset, len, loco_engine_number);

    proto_item_append_text(item, ": %s", loco_engine_number);

    curr_offset += len;

    return (curr_offset - offset);

}

/*

 * 5.8 Notification of a request to alert a controller

 *

 */

static uint16_t

de_gsm_r_uus1_alert_controller(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset)

{

    uint32_t  curr_offset;

    uint32_t  len;

    proto_item *item;

    proto_tree *sub_tree;

    char       *gref_str;

    curr_offset = offset;

    len = tvb_get_uint8(tvb, offset+1);

    item = proto_tree_add_item(tree, hf_gsm_r_uus1_alert_controller, tvb, curr_offset+2, len, ENC_NA);

    sub_tree = proto_item_add_subtree(item, ett_gsm_r_uus1_alert_controller);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_tag, tvb, curr_offset, 1, ENC_NA);

    proto_tree_add_item(sub_tree, hf_gsm_r_uus1_elem_len, tvb, curr_offset+1, 1, ENC_NA);

    curr_offset += 2;

    proto_tree_add_item_ret_display_string(sub_tree, hf_gsm_r_uus1_alert_controller_gref, tvb, curr_offset, 4, ENC_BCD_DIGITS_0_9|ENC_LITTLE_ENDIAN, pinfo->pool, &gref_str);

    proto_item_append_text(item, ": %s", gref_str);

    curr_offset += 4;

    return (curr_offset - offset);

}

static int

dissect_gsm_r_uus1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)

{

    uint8_t elem_tag;

    uint32_t  offset;

    uint32_t  len;

    proto_item   *gsm_r_uus1_item   = NULL;

    proto_tree   *gsm_r_uus1_tree   = NULL;

    offset = 0;

    len = tvb_captured_length(tvb);

    gsm_r_uus1_item =

        proto_tree_add_protocol_format(tree, proto_gsm_r_uus1, tvb, 0, len, "GSM-R User-to-User Signaling");

    gsm_r_uus1_tree = proto_item_add_subtree(gsm_r_uus1_item, ett_gsm_r_uus1);

    while (offset < len){

        elem_tag = tvb_get_uint8(tvb, offset);

        switch (elem_tag) {

        case 2:

        case 3:

            offset += de_gsm_r_uus1_chpc(tvb, gsm_r_uus1_tree, offset);

            break;

        case 5:

            offset += de_gsm_r_uus1_pfn(tvb, pinfo, gsm_r_uus1_tree, offset);

            break;

        case 6:

        case 7:

        case 8:

            offset += de_gsm_r_uus1_elda(tvb, gsm_r_uus1_tree, pinfo, offset);

            break;

        case 9:

            offset += de_gsm_r_uus1_epfn(tvb, gsm_r_uus1_tree, pinfo, offset);

            break;

        case 10:

            offset += de_gsm_r_uus1_text_str(tvb, gsm_r_uus1_tree, pinfo, offset);

            break;

        case 11:

             offset += de_gsm_r_uus1_dsd_alarm(tvb, gsm_r_uus1_tree, pinfo, offset);

            break;

        case 12:

            offset += de_gsm_r_uus1_alert_controller(tvb, gsm_r_uus1_tree, pinfo, offset);

            break;

        default:

            return offset;

        }

    }

    return offset;

}

/* heuristic dissector */

static bool

dissect_gsm_r_uus1_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)

{

    if (dissect_gsm_r_uus1(tvb, pinfo, tree, data) > 0)

        return false;

    return true;

}

/* Register the protocol with Wireshark */

void

proto_register_gsm_r_uus1(void)

{

    /* Setup list of header fields */

    static hf_register_info hf[] = {

        { &hf_gsm_r_uus1_elem_tag,

          { "Element tag", "gsm-r-uus1.elem_tag",

            FT_UINT8, BASE_DEC, VALS(gsm_r_uus1_tags), 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elem_len,

          { "Length", "gsm-r-uus1.elem_len",

            FT_UINT8, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_pfn,

          { "Presentation of Functional Number (PFN)", "gsm-r-uus1.pfn",

            FT_NONE, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_pfn_digits,

          { "Digits", "gsm-r-uus1.pfn.digits",

            FT_STRING, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc,

          { "Confirmation of High Priority Calls (CHPC)", "gsm-r-uus1.chpc",

            FT_NONE, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_t_dur,

          { "Duration of the call", "gsm-r-uus1.chpc.t_dur",

            FT_UINT24, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_t_rel,

          { "Interval between the end of the call and the transmission of the confirmation message", "gsm-r-uus1.chpc.t_rel",

            FT_UINT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_pl_call,

          { "Priority level of the call", "gsm-r-uus1.chpc.pl_call",

            FT_UINT8, BASE_DEC|BASE_RANGE_STRING, RVALS(gsm_r_uus1_chpc_priority_vals), 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause,

          { "Reason for termination of the call", "gsm-r-uus1.chpc.cause",

            FT_UINT8, BASE_HEX, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_power,

          { "Mobile was powered off when receiving (power fail)", "gsm-r-uus1.chpc.cause.power",

            FT_BOOLEAN, 8, NULL, 0x01,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_radio,

          { "Call was interrupted due to radio link error", "gsm-r-uus1.chpc.cause.radio",

            FT_BOOLEAN, 8, NULL, 0x02,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_reserved3,

          { "Reserved", "gsm-r-uus1.chpc.cause.reserved3",

            FT_BOOLEAN, 8, NULL, 0x04,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_reserved4,

          { "Reserved", "gsm-r-uus1.chpc.cause.reserved4",

            FT_BOOLEAN, 8, NULL, 0x08,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_user_command,

          { "Call was left on user command", "gsm-r-uus1.chpc.cause.user_command",

            FT_BOOLEAN, 8, NULL, 0x10,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_reserved6,

          { "Reserved", "gsm-r-uus1.chpc.cause.reserved6",

            FT_BOOLEAN, 8, NULL, 0x20,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_reserved7,

          { "Reserved", "gsm-r-uus1.chpc.cause.reserved7",

            FT_BOOLEAN, 8, NULL, 0x40,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_cause_reserved8,

          { "Reserved", "gsm-r-uus1.chpc.cause.reserved8",

            FT_BOOLEAN, 8, NULL, 0x80,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_gref,

          { "Group call reference", "gsm-r-uus1.chpc.gref",

            FT_STRING, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_chpc_ack_cause,

          { "ACK/CAUSE", "gsm-r-uus1.chpc.ack_cause",

            FT_UINT8, BASE_DEC|BASE_RANGE_STRING, RVALS(gsm_r_uus1_chpc_ack_cause_vals), 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_epfn,

          { "Enhanced presentation of functional number (ePFN)", "gsm-r-uus1.epfn",

            FT_BYTES, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_present_text_str,

          { "Presentation of text strings", "gsm-r-uus1.present_text_str",

            FT_BYTES, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda,

          { "Train position (eLDA)", "gsm-r-uus1.elda",

            FT_NONE, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_lat,

          { "Latitude", "gsm-r-uus1.elda.lat",

            FT_NONE, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_lat_deg,

          { "Degrees", "gsm-r-uus1.elda.lat.deg",

            FT_UINT32, BASE_DEC, NULL, 0xFE000000,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_lat_min,

          { "Minutes", "gsm-r-uus1.elda.lat.min",

            FT_UINT32, BASE_DEC, NULL, 0x01F80000,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_lat_sec,

          { "Seconds", "gsm-r-uus1.elda.lat.sec",

            FT_UINT32, BASE_DEC, NULL, 0x0007FFC0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_lat_hem,

          { "Hemisphere", "gsm-r-uus1.elda.lat.hem",

            FT_BOOLEAN, 32, TFS(&gsm_r_uus1_elda_lat_hem), 0x00000020,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_long,

          { "Latitude", "gsm-r-uus1.elda.long",

            FT_NONE, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_long_deg,

          { "Degrees", "gsm-r-uus1.elda.long.deg",

            FT_UINT32, BASE_DEC, NULL, 0x1FE00000,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_long_min,

          { "Minutes", "gsm-r-uus1.elda.long.min",

            FT_UINT32, BASE_DEC, NULL, 0x001F8000,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_long_sec,

          { "Seconds", "gsm-r-uus1.elda_long.sec",

            FT_UINT32, BASE_DEC, NULL, 0x00007FFC,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_long_hem,

          { "Hemisphere", "gsm-r-uus1.elda_long.hem",

            FT_BOOLEAN, 32, TFS(&gsm_r_uus1_elda_long_hem), 0x00000002,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_height,

          { "Height (m)", "gsm-r-uus1.elda.height",

            FT_INT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_speed,

          { "Speed (km/h)", "gsm-r-uus1.elda.speed",

            FT_UINT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_heading,

          { "Heading (deg)", "gsm-r-uus1.elda.heading",

            FT_UINT8, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_e_time,

          { "Elapsed Time (sec)", "gsm-r-uus1.elda.e_time",

            FT_UINT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_distance,

          { "Distance", "gsm-r-uus1.elda.distance",

            FT_UINT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_scale,

          { "Scale", "gsm-r-uus1.elda.scale",

            FT_UINT32, BASE_DEC, VALS(gsm_r_uus1_elda_scale_vals), 0x00,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_elda_spare,

          { "Spare", "gsm-r-uus1.elda.spare",

            FT_UINT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_present_dsd_alarm,

          { "Notification DSD alarm condition", "gsm-r-uus1.present_dsd_alarm",

            FT_NONE, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_present_dsd_alarm_loco_number,

          { "Locomotive engine number", "gsm-r-uus1.present_dsd_alarm.loco_number",

            FT_STRING, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_alert_controller,

          { "Notification of a request to alert a controller", "gsm-r-uus1.alert_controller",

            FT_NONE, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_gsm_r_uus1_alert_controller_gref,

          { "Group call reference", "gsm-r-uus1.alert_controller.gref",

            FT_STRING, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

    };

    static ei_register_info ei[] = {

        { &ei_gsm_r_uus1_not_implemented_yet, { "gsm-r-uus1.not_implemented_yet", PI_UNDECODED, PI_NOTE, "Not implemented yet", EXPFILL }},

    };

    expert_module_t* expert_gsm_r_uus1;

    static int *ett[] = {

        &ett_gsm_r_uus1,

        &ett_gsm_r_uus1_pfn,

        &ett_gsm_r_uus1_chpc,

        &ett_gsm_r_uus1_chpc_cause,

        &ett_gsm_r_uus1_epfn,

        &ett_gsm_r_uus1_present_text_str,

        &ett_gsm_r_uus1_elda,

        &ett_gsm_r_uus1_elda_lat,

        &ett_gsm_r_uus1_elda_long,

        &ett_gsm_r_uus1_present_dsd_alarm,

        &ett_gsm_r_uus1_alert_controller

    };

    module_t *gsm_r_uus1_module;

    /* Register the protocol name and description */

    proto_gsm_r_uus1 =

        proto_register_protocol("GSM-R User-to-User Signaling", "GSM-R", "gsm-r-uus1");

    proto_register_field_array(proto_gsm_r_uus1, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    expert_gsm_r_uus1 = expert_register_protocol(proto_gsm_r_uus1);

    expert_register_field_array(expert_gsm_r_uus1, ei, array_length(ei));

    /* subdissector code */

    register_dissector("gsm-r-uus1", dissect_gsm_r_uus1, proto_gsm_r_uus1);

    gsm_r_uus1_module = prefs_register_protocol(proto_gsm_r_uus1, proto_reg_handoff_gsm_r_uus1);

    prefs_register_bool_preference(gsm_r_uus1_module, "dissect_q931_u2u",

        "Dissect Q.931 User-To-User information",

        "Dissect Q.931 User-To-User information",

        &q931_u2u);

    prefs_register_bool_preference(gsm_r_uus1_module, "dissect_gsm_a_u2u",

        "Dissect GSM-A User-To-User information",

        "Dissect GSM-A User-To-User information",

        &gsm_a_u2u);

}

void

proto_reg_handoff_gsm_r_uus1(void)

{

    dissector_handle_t gsm_r_uus1_handle;

    gsm_r_uus1_handle = find_dissector("gsm-r-uus1");

    if(q931_u2u){

        heur_dissector_add("q931_user", dissect_gsm_r_uus1_heur, "GSM-R over UUS1", "gsm_r_uus1", proto_gsm_r_uus1, HEURISTIC_ENABLE);

    } else {

        heur_dissector_delete("q931_user", dissect_gsm_r_uus1_heur, proto_gsm_r_uus1);

    }

    if(gsm_a_u2u){

        dissector_add_uint("gsm_a.dtap.u2u_prot_discr", 0, gsm_r_uus1_handle);

    } else {

        dissector_delete_uint("gsm_a.dtap.u2u_prot_discr", 0, gsm_r_uus1_handle);

    }

}

/*

 * 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:

 */