/* packet-ccsds-sp.c

 * Routines for CCSDS Space Packet dissection

 * Copyright 2000, Scott Hovis scott.hovis@ums.msfc.nasa.gov

 * Enhanced 2008, Matt Dunkle Matthew.L.Dunkle@nasa.gov

 *

 * 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/expert.h>

#include <epan/prefs.h>

#include <epan/to_str.h>

void proto_register_ccsds(void);

void proto_reg_handoff_ccsds(void);

/*

 * See

 *

 *  https://ccsds.org/Pubs/133x0b1s.pdf Space Packet Protocol section 4.1  -- CCSDS 133.0-B-1 replaces CCSDS 701.0-B-2

 *  https://ccsds.org/Pubs/133x0b2e2.pdf Space Packet Protocol section 4.1 -- CCSDS 133.0-B-2, replaces CCSDS 133.0-B-1

 *  http://everyspec.com/NASA/NASA-JSC/NASA-SSP-PUBS/download.php?spec=SSP_52050E.003096.pdf section 3.1.3

 *

 * for some information.

 *

 * See

 *

 *  https://arc.aiaa.org/doi/pdf/10.2514/6.2002-T5-11

 *

 * for a discussion of a restructuring of the CCSDS protocol definitions

 * that combined:

 *

 *   * the Source Packet from CCSDS 102.0 - https://ccsds.org/Pubs/102x0b5s.pdf;

 *   * the CCSDS Packet from CCSDS 701.0 - https://ccsds.org/Pubs/701x0b3s.pdf;

 *   * the TC Packet from CCSDS 203.0 - https://ccsds.org/Pubs/203x0b2s.pdf;

 *

 * all of which had the same format, into the Space Packet.

 */

/* Initialize the protocol and registered fields */

static int proto_ccsds;

/* primary header */

static int hf_ccsds_header_flags;

static int hf_ccsds_apid;

static int hf_ccsds_version;

static int hf_ccsds_secheader;

static int hf_ccsds_type;

static int hf_ccsds_seqnum;

static int hf_ccsds_seqflag;

static int hf_ccsds_length;

/* common secondary header */

static int hf_ccsds_coarse_time;

static int hf_ccsds_fine_time;

static int hf_ccsds_timeid;

static int hf_ccsds_checkword_flag;

/* payload specific secondary header */

static int hf_ccsds_zoe;

static int hf_ccsds_packet_type_unused;

static int hf_ccsds_vid;

static int hf_ccsds_dcc;

/* core specific secondary header */

/* static int hf_ccsds_spare1; */

static int hf_ccsds_packet_type;

/* static int hf_ccsds_spare2; */

static int hf_ccsds_element_id;

static int hf_ccsds_cmd_data_packet;

static int hf_ccsds_format_version_id;

static int hf_ccsds_extended_format_id;

/* static int hf_ccsds_spare3; */

static int hf_ccsds_frame_id;

static int hf_ccsds_embedded_time;

static int hf_ccsds_user_data;

/* Checkword (checksum) */

static int hf_ccsds_checkword;

static int hf_ccsds_checkword_good;

static int hf_ccsds_checkword_bad;

/* Initialize the subtree pointers */

static int ett_ccsds_primary_header_flags;

static int ett_ccsds;

static int ett_ccsds_primary_header;

static int ett_ccsds_secondary_header;

static int ett_ccsds_checkword;

static expert_field ei_ccsds_length_error;

static expert_field ei_ccsds_checkword;

static dissector_handle_t ccsds_handle;

/* Dissector table */

static dissector_table_t ccsds_dissector_table;

static const enum_val_t dissect_checkword[] = {

    { "hdr", "Use header flag", 2 },

    { "no",  "Override header flag to be false", 0 },

    { "yes", "Override header flag to be true", 1 },

    { NULL, NULL, 0 }

};

/* Global preferences */

/* As defined above, default is to use header flag */

static int global_dissect_checkword = 2;

/*

 * Bits in the first 16-bit header word

 */

#define HDR_VERSION 0xe000

#define HDR_TYPE    0x1000

#define HDR_SECHDR  0x0800

#define HDR_APID    0x07ff

/* some basic sizing parameters */

enum

{

    CCSDS_PRIMARY_HEADER_LENGTH = 6,

    CCSDS_SECONDARY_HEADER_LENGTH = 10

};

/* leap year macro */

#ifndef Leap

#  define Leap(yr) ( ( 0 == (yr)%4  &&  0 != (yr)%100 )  ||  ( 0 == (yr)%400 ) )

#endif

static const value_string ccsds_primary_header_sequence_flags[] = {

    {  0, "Continuation segment" },

    {  1, "First segment" },

    {  2, "Last segment" },

    {  3, "Unsegmented data" },

    {  0, NULL }

};

static const value_string ccsds_secondary_header_type[] = {

    {  0, "Core" },

    {  1, "Payload" },

    {  0, NULL }

};

static const value_string ccsds_secondary_header_packet_type[] = {

    {  0, "UNDEFINED" },

    {  1, "Data Dump" },

    {  2, "UNDEFINED" },

    {  3, "UNDEFINED" },

    {  4, "TLM/Status" },

    {  5, "UNDEFINED" },

    {  6, "Payload Private/Science" },

    {  7, "Ancillary Data" },

    {  8, "Essential Cmd" },

    {  9, "System Cmd" },

    { 10, "Payload Cmd" },

    { 11, "Data Load/File Transfer" },

    { 12, "UNDEFINED" },

    { 13, "UNDEFINED" },

    { 14, "UNDEFINED" },

    { 15, "UNDEFINED" },

    {  0, NULL }

};

static const value_string ccsds_secondary_header_element_id[] = {

    {  0, "NASA (Ground Test Only)" },

    {  1, "NASA" },

    {  2, "ESA/APM" },

    {  3, "NASDA" },

    {  4, "RSA" },

    {  5, "CSA" },

    {  6, "ESA/ATV" },

    {  7, "ASI" },

    {  8, "ESA/ERA" },

    {  9, "Reserved" },

    { 10, "RSA SPP" },

    { 11, "NASDA HTV" },

    { 12, "Reserved" },

    { 13, "Reserved" },

    { 14, "Reserved" },

    { 15, "Reserved" },

    {  0, NULL }

};

static const value_string ccsds_secondary_header_cmd_data_packet[] = {

    {  0, "Command Packet" },

    {  1, "Data Packet" },

    {  0, NULL }

};

static const value_string ccsds_secondary_header_format_id[] = {

    {  0, "Reserved" },

    {  1, "Essential Telemetry" },

    {  2, "Housekeeping Tlm - 1" },

    {  3, "Housekeeping Tlm - 2" },

    {  4, "PCS DDT" },

    {  5, "CCS S-Band Command Response" },

    {  6, "Contingency Telemetry via the SMCC" },

    {  7, "Normal Data Dump" },

    {  8, "Extended Data Dump" },

    {  9, "Reserved" },

    { 10, "Reserved" },

    { 11, "Broadcast Ancillary Data" },

    { 12, "Reserved" },

    { 13, "NCS to OIU Telemetry and ECOMM Telemetry" },

    { 14, "CCS to OIU Telemetry - Direct" },

    { 15, "Reserved" },

    { 16, "Normal File Dump" },

    { 17, "Extended File Dump" },

    { 18, "NCS to FGB Telemetry" },

    { 19, "Reserved" },

    { 20, "ZOE Normal Dump (S-Band)" },

    { 21, "ZOE Extended Dump (S-Band)" },

    { 22, "EMU S-Band TLM Packet" },

    { 23, "Reserved" },

    { 24, "Reserved" },

    { 25, "Reserved" },

    { 26, "CCS to OIU Telemetry via UHF" },

    { 27, "OSTP Telemetry (After Flight 1E, CCS R5)" },

    { 28, "Reserved" },

    { 29, "Reserved" },

    { 30, "Reserved" },

    { 31, "Reserved" },

    { 32, "Reserved" },

    { 33, "Reserved" },

    { 34, "Reserved" },

    { 35, "Reserved" },

    { 36, "Reserved" },

    { 37, "Reserved" },

    { 38, "Reserved" },

    { 39, "Reserved" },

    { 40, "Reserved" },

    { 41, "Reserved" },

    { 42, "Reserved" },

    { 43, "Reserved" },

    { 44, "Reserved" },

    { 45, "Reserved" },

    { 46, "Reserved" },

    { 47, "Reserved" },

    { 48, "Reserved" },

    { 49, "Reserved" },

    { 50, "Reserved" },

    { 51, "Reserved" },

    { 52, "Reserved" },

    { 53, "Reserved" },

    { 54, "Reserved" },

    { 55, "Reserved" },

    { 56, "Reserved" },

    { 57, "Reserved" },

    { 58, "Reserved" },

    { 59, "Reserved" },

    { 60, "Reserved" },

    { 61, "Reserved" },

    { 62, "Reserved" },

    { 63, "Reserved" },

    { 0, NULL }

};

static value_string_ext ccsds_secondary_header_format_id_ext = VALUE_STRING_EXT_INIT(ccsds_secondary_header_format_id);

/* convert CCSDS embedded time to a human readable string - NOT THREAD SAFE */

static const char* embedded_time_to_string ( wmem_allocator_t *pool, int coarse_time, int fine_time )

{

    static int utcdiff    = 0;

    nstime_t   t;

    int        yr;

    int        fraction;

    int        multiplier = 1000;

    /* compute the static constant difference in seconds

     * between midnight 5-6 January 1980 (GPS time) and

     * seconds since 1/1/1970 (UTC time) just this once

     */

    if ( 0 == utcdiff )

    {

        for ( yr = 1970; yr < 1980; ++yr )

        {

            utcdiff += ( Leap(yr)  ?  366 : 365 ) * 24 * 60 * 60;

        }

        utcdiff += 5 * 24 * 60 * 60;  /* five days of January 1980 */

    }

    t.secs = coarse_time + utcdiff;

    fraction = ( multiplier * ( (int)fine_time & 0xff ) ) / 256;

    t.nsecs = fraction*1000000; /* msecs to nsecs */

    return abs_time_to_str(pool, &t, ABSOLUTE_TIME_DOY_UTC, true);

}

/*

 * Dissect CCSDS Space Packet.

 */

static int

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

{

    int          offset          = 0;

    proto_item  *ccsds_packet;

    proto_tree  *ccsds_tree;

    proto_item  *primary_header;

    proto_tree  *primary_header_tree;

    uint16_t     first_word;

    uint32_t     coarse_time;

    uint8_t      fine_time;

    proto_item  *secondary_header;

    proto_tree  *secondary_header_tree;

    const char  *time_string;

    int          ccsds_length;

    int          length          = 0;

    int          reported_length;

    uint8_t      checkword_flag  = 0;

    int          counter         = 0;

    proto_item  *item, *checkword_item = NULL;

    proto_tree  *checkword_tree;

    uint16_t     checkword_field = 0;

    uint16_t     checkword_sum   = 0;

    tvbuff_t    *next_tvb;

    static int * const header_flags[] = {

        &hf_ccsds_version,

        &hf_ccsds_type,

        &hf_ccsds_secheader,

        &hf_ccsds_apid,

        NULL

    };

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "CCSDS SP");

    col_set_str(pinfo->cinfo, COL_INFO, "CCSDS Space Packet");

    first_word = tvb_get_ntohs(tvb, 0);

    col_add_fstr(pinfo->cinfo, COL_INFO, "APID %4d (0x%03X)", first_word&HDR_APID, first_word&HDR_APID);

    reported_length = tvb_reported_length_remaining(tvb, 0);

    ccsds_length    = tvb_get_ntohs(tvb, 4) + CCSDS_PRIMARY_HEADER_LENGTH + 1;

    /* Min length is size of headers, whereas max length is reported length.

     * If the length field in the CCSDS header is outside of these bounds,

     * use the value it violates.  Otherwise, use the length field value.

     */

    if (ccsds_length > reported_length)

        length = reported_length;

    else if (ccsds_length < CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH)

        length = CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH;

    else

        length = ccsds_length;

    ccsds_packet = proto_tree_add_item(tree, proto_ccsds, tvb, 0, length, ENC_NA);

    ccsds_tree   = proto_item_add_subtree(ccsds_packet, ett_ccsds);

    /* build the primary header tree */

    primary_header_tree = proto_tree_add_subtree(ccsds_tree, tvb, offset, CCSDS_PRIMARY_HEADER_LENGTH,

                            ett_ccsds_primary_header, &primary_header, "Primary Header");

    proto_tree_add_bitmask(primary_header_tree, tvb, offset, hf_ccsds_header_flags,

                    ett_ccsds_primary_header_flags, header_flags, ENC_BIG_ENDIAN);

    offset += 2;

    proto_tree_add_item(primary_header_tree, hf_ccsds_seqflag, tvb, offset, 2, ENC_BIG_ENDIAN);

    proto_tree_add_item(primary_header_tree, hf_ccsds_seqnum, tvb, offset, 2, ENC_BIG_ENDIAN);

    offset += 2;

    item = proto_tree_add_item(primary_header_tree, hf_ccsds_length, tvb, offset, 2, ENC_BIG_ENDIAN);

    if (ccsds_length > reported_length) {

        expert_add_info(pinfo, item, &ei_ccsds_length_error);

    }

    offset += 2;

    proto_item_set_end(primary_header, tvb, offset);

    /*

     * Build the secondary header tree.

     *

     * 133.0 says this consists of:

     *

     *   a time code field that "shall consist of one of the CCSDS

     *   segmented binary or unsegmented binary time codes specified

     *   in reference [3].", reference [3] being "Time Code Formats

     * . Issue 4. Recommendation for Space Data System Standards (Blue

     *   Book), CCSDS 301.0-B-4. Washington, D.C.: CCSDS, November 2010";

     *

     * followed by an ancillary data field not specified by 133.0.

     *

     * 102.0 says this consists of:

     *

     *   "a PACKET SECONDARY HEADER DATA FIELD;

     *    or a PACKET SECONDARY HEADER TIME CODE FIELD;

     *    or a PACKET SECONDARY HEADER TIME CODE FIELD followed by a

     *    PACKET SECONDARY HEADER DATA FIELD."

     *

     * where "a PACKET SECONDARY HEADER DATA FIELD" isn't defined by 102.0

     * and "a PACKET SECONDARY HEADER TIME CODE FIELD" "shall consist of

     * one of the CCSDS segmented binary or unsegmented binary time codes

     * specified in Reference [3]", reference [3] being "Time Code Formats

     * Recommendation for Space Data Systems Standards, CCSDS

     * 301.0-B-2. Blue Book. Issue 2. Washington, D.C.: CCSDS, April 1990.

     *

     * 701.0 says this is "specified by the source end user" and gives,

     * in Annex A, a secondary header for time stamping, which "shall

     * consist of:

     *

     *    a Time Code Field only; or

     *    an Ancillary Data Field only; or

     *    a Time Code Field followed by an Ancillary Data Field"

     *

     * wbere "it is preferred that the Packet Secondary Header Time Code Field

     * should contain one of the CCSDS segmented binary or unsegmented binary

     * time codes specified in Reference [20]", where reference [20] is

     * "'Time Code Formats', Recommendation for Space Data Systems Standards,

     * CCSDS 301.0-B-2, Blue Book, Issue 2 (Washington, D.C.: CCSDS, April

     * 1990 or later issue)."

     *

     * 203.0 says:

     *

     * "The purpose of the Secondary Header is to provide a means for

     * encoding, within a TC Packet, any ancillary data (time, sending

     * address, data field format, etc.) which may be necessary for the

     * interpretation of the application data contained within the packet.

     *

     * If a Secondary Header is present, this shall be indicated by

     * setting the Secondary Header Flag to value "1".  At present, the

     * CCSDS has not developed recommendations for the internal format

     * of the Secondary Header: therefore, local conventions may be used as

     * required.  However, in order to permit future standardization of

     * this data structure the most-significant bit (Bit 0) of the

     * leading octet within the Secondary Header shall be reserved and

     * assigned as follows whenever the Secondary Header Flag is set to

     * value "1":

     *

     *              Bit 0 = "0" : non-CCSDS-defined Secondary Header follows

     *              Bit 0 = "1" : CCSDS-defined Secondary Header follows"

     *

     */

    if ( first_word & HDR_SECHDR )

    {

        secondary_header_tree = proto_tree_add_subtree(ccsds_tree, tvb, offset, CCSDS_SECONDARY_HEADER_LENGTH,

                        ett_ccsds_secondary_header, &secondary_header, "CCSDS Space Packet Secondary Header");

        /* command secondary header flags */

        proto_tree_add_item_ret_uint(secondary_header_tree, hf_ccsds_coarse_time, tvb, offset, 4, ENC_BIG_ENDIAN, &coarse_time);

        offset += 4;

        proto_tree_add_item_ret_uint8(secondary_header_tree, hf_ccsds_fine_time, tvb, offset, 1, ENC_BIG_ENDIAN, &fine_time);

        ++offset;

        time_string = embedded_time_to_string ( pinfo->pool, coarse_time, fine_time );

        proto_tree_add_string(secondary_header_tree, hf_ccsds_embedded_time, tvb, offset-5, 5, time_string);

        proto_tree_add_item(secondary_header_tree, hf_ccsds_timeid, tvb, offset, 1, ENC_BIG_ENDIAN);

        checkword_item = proto_tree_add_item(secondary_header_tree, hf_ccsds_checkword_flag, tvb, offset, 1, ENC_BIG_ENDIAN);

        /* Global Preference: how to handle checkword flag */

        switch (global_dissect_checkword) {

           case 0:

              /* force checkword presence flag to be false */

              checkword_flag = 0;

              break;

           case 1:

              /* force checkword presence flag to be true */

              checkword_flag = 1;

              break;

           default:

              /* use value of checkword presence flag from header */

              checkword_flag = (tvb_get_uint8(tvb, offset)&0x20) >> 5;

              break;

        }

        /* payload specific secondary header flags */

        if ( first_word & HDR_TYPE )

        {

            proto_tree_add_item(secondary_header_tree, hf_ccsds_zoe, tvb, offset, 1, ENC_BIG_ENDIAN);

            proto_tree_add_item(secondary_header_tree, hf_ccsds_packet_type_unused, tvb, offset, 1, ENC_BIG_ENDIAN);

            ++offset;

            proto_tree_add_item(secondary_header_tree, hf_ccsds_vid, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset += 2;

            proto_tree_add_item(secondary_header_tree, hf_ccsds_dcc, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset += 2;

        }

        /* core specific secondary header flags */

        else

        {

            /* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare1, tvb, offset, 1, ENC_BIG_ENDIAN); */

            proto_tree_add_item(secondary_header_tree, hf_ccsds_packet_type, tvb, offset, 1, ENC_BIG_ENDIAN);

            ++offset;

            /* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare2, tvb, offset, 2, ENC_BIG_ENDIAN); */

            proto_tree_add_item(secondary_header_tree, hf_ccsds_element_id, tvb, offset, 2, ENC_BIG_ENDIAN);

            proto_tree_add_item(secondary_header_tree, hf_ccsds_cmd_data_packet, tvb, offset, 2, ENC_BIG_ENDIAN);

            proto_tree_add_item(secondary_header_tree, hf_ccsds_format_version_id, tvb, offset, 2, ENC_BIG_ENDIAN);

            proto_tree_add_item(secondary_header_tree, hf_ccsds_extended_format_id, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset += 2;

            /* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare3, tvb, offset, 1, ENC_BIG_ENDIAN); */

            ++offset;

            proto_tree_add_item(secondary_header_tree, hf_ccsds_frame_id, tvb, offset, 1, ENC_BIG_ENDIAN);

            ++offset;

        }

        /* finish the secondary header */

        proto_item_set_end(secondary_header, tvb, offset);

    }

    /* If there wasn't a full packet, then don't allow a tree item for checkword. */

    if (reported_length < ccsds_length || ccsds_length < CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH) {

        /* Label payload 'User Data' */

        if (length > offset)

            proto_tree_add_item(ccsds_tree, hf_ccsds_user_data, tvb, offset, length-offset, ENC_NA);

        offset += length-offset;

        if (checkword_flag == 1)

            expert_add_info(pinfo, checkword_item, &ei_ccsds_checkword);

    }

    /*  Handle checkword according to preference setting. */

    else {

        next_tvb = tvb_new_subset_remaining(tvb, offset);

        /* Look for a subdissector for the payload */

        if (!dissector_try_uint(ccsds_dissector_table, first_word&HDR_APID, next_tvb, pinfo, tree)) {

          /* If no subdissector is found, label the payload as 'User Data' */

          proto_tree_add_item(ccsds_tree, hf_ccsds_user_data, tvb, offset, length-offset-2*checkword_flag, ENC_NA);

        }

        offset += length-offset-2*checkword_flag;

        /* If checkword is present, calculate packet checksum (16-bit running sum) for comparison */

        if (checkword_flag == 1) {

            /* don't count the checkword as part of the checksum */

            while (counter < ccsds_length-2) {

                checkword_sum += tvb_get_ntohs(tvb, counter);

                counter += 2;

            }

            checkword_field = tvb_get_ntohs(tvb, offset);

            /* Report checkword status */

            if (checkword_sum == checkword_field) {

                item = proto_tree_add_uint_format_value(ccsds_tree, hf_ccsds_checkword, tvb, offset, 2, checkword_field,

                        "0x%04x [correct]", checkword_field);

                checkword_tree = proto_item_add_subtree(item, ett_ccsds_checkword);

                item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_good, tvb, offset, 2, true);

                proto_item_set_generated(item);

                item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_bad, tvb, offset, 2, false);

                proto_item_set_generated(item);

            } else {

                item = proto_tree_add_uint_format_value(ccsds_tree, hf_ccsds_checkword, tvb, offset, 2, checkword_field,

                        "0x%04x [incorrect, should be 0x%04x]", checkword_field, checkword_sum);

                checkword_tree = proto_item_add_subtree(item, ett_ccsds_checkword);

                item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_good, tvb, offset, 2, false);

                proto_item_set_generated(item);

                item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_bad, tvb, offset, 2, true);

                proto_item_set_generated(item);

            }

            offset += 2;

        }

    }

    /* Give the data dissector any bytes past the packet length */

    call_data_dissector(tvb_new_subset_remaining(tvb, offset), pinfo, tree);

    return tvb_captured_length(tvb);

}

void

proto_register_ccsds(void)

{

    static hf_register_info hf[] = {

        /* primary header flags */

        { &hf_ccsds_header_flags,

            { "Header Flags",           "ccsds.header_flags",

            FT_UINT16, BASE_HEX, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_ccsds_version,

            { "Version",           "ccsds.version",

            FT_UINT16, BASE_DEC, NULL, HDR_VERSION,

            NULL, HFILL }

        },

        { &hf_ccsds_type,

            { "Type",           "ccsds.type",

            FT_UINT16, BASE_DEC, VALS(ccsds_secondary_header_type), HDR_TYPE,

            NULL, HFILL }

        },

        { &hf_ccsds_secheader,

            { "Secondary Header",           "ccsds.secheader",

            FT_BOOLEAN, 16, NULL, HDR_SECHDR,

            "Secondary Header Present", HFILL }

        },

        { &hf_ccsds_apid,

            { "APID",           "ccsds.apid",

            FT_UINT16, BASE_DEC, NULL, HDR_APID,

            NULL, HFILL }

        },

        { &hf_ccsds_seqflag,

            { "Sequence Flags",           "ccsds.seqflag",

            FT_UINT16, BASE_DEC, VALS(ccsds_primary_header_sequence_flags), 0xc000,

            NULL, HFILL }

        },

        { &hf_ccsds_seqnum,

            { "Sequence Number",           "ccsds.seqnum",

            FT_UINT16, BASE_DEC, NULL, 0x3fff,

            NULL, HFILL }

        },

        { &hf_ccsds_length,

            { "Packet Length",           "ccsds.length",

            FT_UINT16, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        /* common secondary header flags */

        { &hf_ccsds_coarse_time,

            { "Coarse Time",           "ccsds.coarse_time",

            FT_UINT32, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_ccsds_fine_time,

            { "Fine Time",           "ccsds.fine_time",

            FT_UINT8, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_ccsds_timeid,

            { "Time Identifier",           "ccsds.timeid",

            FT_UINT8, BASE_DEC, NULL, 0xc0,

            NULL, HFILL }

        },

        { &hf_ccsds_checkword_flag,

            { "Checkword Indicator",           "ccsds.checkword_flag",

            FT_BOOLEAN, 8, NULL, 0x20,

            "Checkword present", HFILL }

        },

        /* payload specific secondary header flags */

        { &hf_ccsds_zoe,

            { "ZOE TLM",           "ccsds.zoe",

            FT_UINT8, BASE_DEC, NULL, 0x10,

            "Contains S-band ZOE Packets", HFILL }

        },

        { &hf_ccsds_packet_type_unused,

            { "Packet Type (unused for Ku-band)",  "ccsds.packet_type",

            FT_UINT8, BASE_DEC, NULL, 0x0f,

            NULL, HFILL }

        },

        { &hf_ccsds_vid,

            { "Version Identifier",           "ccsds.vid",

            FT_UINT16, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_ccsds_dcc,

            { "Data Cycle Counter",           "ccsds.dcc",

            FT_UINT16, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        /* core specific secondary header flags */

#if 0

        { &hf_ccsds_spare1,

            { "Spare Bit 1",           "ccsds.spare1",

            FT_UINT8, BASE_DEC, NULL, 0x10,

            "unused spare bit 1", HFILL }

        },

#endif

        { &hf_ccsds_packet_type,

            { "Packet Type",       "ccsds.packet_type",

            FT_UINT8, BASE_DEC, VALS(ccsds_secondary_header_packet_type), 0x0f,

            NULL, HFILL }

        },

#if 0

        { &hf_ccsds_spare2,

            { "Spare Bit 2",           "ccsds.spare2",

            FT_UINT16, BASE_DEC, NULL, 0x8000,

            NULL, HFILL }

        },

#endif

        { &hf_ccsds_element_id,

            { "Element ID",           "ccsds.element_id",

            FT_UINT16, BASE_DEC, VALS(ccsds_secondary_header_element_id), 0x7800,

            NULL, HFILL }

        },

        { &hf_ccsds_cmd_data_packet,

            { "Cmd/Data Packet Indicator",  "ccsds.cmd_data_packet",

            FT_UINT16, BASE_DEC, VALS(ccsds_secondary_header_cmd_data_packet), 0x0400,

            NULL, HFILL }

        },

        { &hf_ccsds_format_version_id,

            { "Format Version ID",    "ccsds.format_version_id",

            FT_UINT16, BASE_DEC, NULL, 0x03c0,

            NULL, HFILL }

        },

        { &hf_ccsds_extended_format_id,

            { "Extended Format ID",   "ccsds.extended_format_id",

            FT_UINT16, BASE_DEC | BASE_EXT_STRING, &ccsds_secondary_header_format_id_ext, 0x003f,

            NULL, HFILL }

        },

#if 0

        { &hf_ccsds_spare3,

            { "Spare Bits 3",         "ccsds.spare3",

            FT_UINT8, BASE_DEC, NULL, 0xff,

            NULL, HFILL }

        },

#endif

        { &hf_ccsds_frame_id,

            { "Frame ID",             "ccsds.frame_id",

            FT_UINT8, BASE_DEC, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_ccsds_embedded_time,

            { "Embedded Time",        "ccsds.embedded_time",

            FT_STRING, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_ccsds_user_data,

            { "User Data",        "ccsds.user_data",

            FT_BYTES, BASE_NONE, NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_ccsds_checkword,

            { "Checkword",   "ccsds.checkword",

            FT_UINT16, BASE_HEX, NULL, 0x0,

            "Checkword: 16-bit running sum of all bytes excluding the checkword", HFILL }

        },

        { &hf_ccsds_checkword_good,

            { "Good",              "ccsds.checkword_good",

            FT_BOOLEAN, BASE_NONE, NULL, 0x0,

            "True: checkword matches packet content; False: doesn't match content", HFILL }

        },

        { &hf_ccsds_checkword_bad,

            { "Bad",               "ccsds.checkword_bad",

            FT_BOOLEAN, BASE_NONE, NULL, 0x0,

            "True: checkword doesn't match packet content; False: matches content", HFILL }

        }

    };

    /* Setup protocol subtree array */

    static int *ett[] = {

        &ett_ccsds_primary_header_flags,

        &ett_ccsds,

        &ett_ccsds_primary_header,

        &ett_ccsds_secondary_header,

        &ett_ccsds_checkword

    };

    static ei_register_info ei[] = {

        { &ei_ccsds_length_error, { "ccsds.length.error", PI_MALFORMED, PI_ERROR, "Length field value is greater than the packet seen on the wire", EXPFILL }},

        { &ei_ccsds_checkword, { "ccsds.no_checkword", PI_PROTOCOL, PI_WARN, "Packet does not contain a Checkword", EXPFILL }},

    };

    /* Define the preferences module */

    module_t *ccsds_module;

    expert_module_t* expert_ccsds;

    /* Register the protocol name and description */

    proto_ccsds = proto_register_protocol("CCSDS Space Packet", "CCSDS SP", "ccsds");

    /* Required function calls to register the header fields and subtrees used */

    proto_register_field_array(proto_ccsds, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    expert_ccsds = expert_register_protocol(proto_ccsds);

    expert_register_field_array(expert_ccsds, ei, array_length(ei));

    ccsds_handle = register_dissector("ccsds", dissect_ccsds, proto_ccsds);

    /* Register preferences module */

    ccsds_module = prefs_register_protocol(proto_ccsds, NULL);

    prefs_register_enum_preference(ccsds_module, "global_pref_checkword",

        "How to handle the CCSDS Checkword",

        "Specify how the dissector should handle the Ccheckword",

        &global_dissect_checkword, dissect_checkword, false);

    /* Dissector table for sub-dissectors */

    ccsds_dissector_table = register_dissector_table("ccsds.apid", "CCSDS SP apid", proto_ccsds, FT_UINT16, BASE_DEC);

}

void

proto_reg_handoff_ccsds(void)

{

    dissector_add_for_decode_as_with_preference( "udp.port", ccsds_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:

 */