path: root/epan/dissectors/packet-mpeg-sect.c

/* packet-mpeg-sect.c
 * Routines for MPEG2 (ISO/ISO 13818-1) Section dissection
 * Copyright 2012, Guy Martin <gmsoft@tuxicoman.be>
 *
 * 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/prefs.h>
#include <epan/crc32-tvb.h>
#include <epan/expert.h>
#include <epan/decode_as.h>
#include <epan/proto_data.h>
#include "packet-mpeg-sect.h"

void proto_register_mpeg_sect(void);

static int proto_mpeg_sect;
static int hf_mpeg_sect_table_id;
static int hf_mpeg_sect_syntax_indicator;
static int hf_mpeg_sect_reserved;
static int hf_mpeg_sect_length;
static int hf_mpeg_sect_crc;
static int hf_mpeg_sect_crc_status;

static int ett_mpeg_sect;

static expert_field ei_mpeg_sect_crc;

static dissector_table_t mpeg_sect_tid_dissector_table;

static bool mpeg_sect_check_crc;

/* minimum length of the entire section ==
   bytes from table_id to section_length == 3 bytes */
#define MPEG_SECT_MIN_LEN    3
/* the section_length field is 12 bits, it can add up to 4096 bytes
   after the initial bytes */
#define MPEG_SECT_MAX_LEN    MPEG_SECT_MIN_LEN+4096


#define MPEG_SECT_SYNTAX_INDICATOR_MASK 0x8000
#define MPEG_SECT_RESERVED_MASK         0x7000
#define MPEG_SECT_LENGTH_MASK           0x0FFF

/* From ISO/IEC 13818-1 */
enum {
    TID_PAT,
    TID_CA,
    TID_PMT,
    TID_TS_DESC,
    TID_SCENE_DESC,
    TID_OBJECT_DESC,
    TID_FORBIDEN    = 0xFF
};

/* From ETSI EN 300 468 */
enum {
    TID_NIT       = 0x40,
    TID_NIT_OTHER,
    TID_SDT,
    TID_SDT_OTHER = 0x46,
    TID_BAT       = 0x4A,
    TID_EIT_PF    = 0x4E,
    TID_EIT_PF_OTHER,
    TID_EIT_SC0   = 0x50,
    TID_EIT_SC1,
    TID_EIT_SC2,
    TID_EIT_SC3,
    TID_EIT_SC4,
    TID_EIT_SC5,
    TID_EIT_SC6,
    TID_EIT_SC7,
    TID_EIT_SC8,
    TID_EIT_SC9,
    TID_EIT_SCA,
    TID_EIT_SCB,
    TID_EIT_SCC,
    TID_EIT_SCD,
    TID_EIT_SCE,
    TID_EIT_SCF,
    TID_EIT_SC0_OTH = 0x60,
    TID_EIT_SC1_OTH,
    TID_EIT_SC2_OTH,
    TID_EIT_SC3_OTH,
    TID_EIT_SC4_OTH,
    TID_EIT_SC5_OTH,
    TID_EIT_SC6_OTH,
    TID_EIT_SC7_OTH,
    TID_EIT_SC8_OTH,
    TID_EIT_SC9_OTH,
    TID_EIT_SCA_OTH,
    TID_EIT_SCB_OTH,
    TID_EIT_SCC_OTH,
    TID_EIT_SCD_OTH,
    TID_EIT_SCE_OTH,
    TID_EIT_SCF_OTH,
    TID_TDT       = 0x70,
    TID_RST,
    TID_ST,
    TID_TOT,
    TID_SIT       = 0x7F
};

/* From ETSI EN 301 790 */
enum {
    TID_RMT = 0x41, /* Conflict with TID_NIT_OTHER */
    TID_SCT = 0xA0,
    TID_FCT,
    TID_TCT,
    TID_SPT,
    TID_CMT,
    TID_TBTP,
    TID_PCR,
    TID_TIM = 0xB0
};

/* From ETSI EN 301 192 */
enum {
    TID_DVB_MPE = 0x3E
};

/* From OC-SP-ETV-AM 1.0-IO5 */
enum {
    TID_ETV_EISS = 0xE0,
    TID_ETV_DII  = 0xE3,
    TID_ETV_DDB  = 0xE4
};

/* From ETSI TS 102 899 */
enum {
    TID_AIT = 0x74
};


static const value_string mpeg_sect_table_id_vals[] = {

    { TID_PAT,         "Program Association Table (PAT)" },
    { TID_CA,          "Conditional Access (CA)" },
    { TID_PMT,         "Program Map Table (PMT)" },
    { TID_TS_DESC,     "Transport Stream Description" },
    { TID_SCENE_DESC,  "ISO/IEC 14496 Scene Description" },
    { TID_OBJECT_DESC, "ISO/IEC 14496 Object Description" },
    { TID_NIT,         "Network Information Table (NIT), current network" },
    { TID_NIT_OTHER,   "Network Information Table (NIT), other network" },
    { TID_SDT,         "Service Description Table (SDT), current network" },
    { TID_SDT_OTHER,   "Service Description (SDT), other network" },
    { TID_BAT,         "Bouquet Association Table (BAT)" },
    { TID_EIT_PF,      "Event Information Table (EIT), present/following, actual TS" },
    { TID_EIT_PF_OTHER,"Event Information Table (EIT), present/following, other TS" },
    { TID_EIT_SC0,     "Event Information Table (EIT), schedule 0, actual TS" },
    { TID_EIT_SC1,     "Event Information Table (EIT), schedule 1, actual TS" },
    { TID_EIT_SC2,     "Event Information Table (EIT), schedule 2, actual TS" },
    { TID_EIT_SC3,     "Event Information Table (EIT), schedule 3, actual TS" },
    { TID_EIT_SC4,     "Event Information Table (EIT), schedule 4, actual TS" },
    { TID_EIT_SC5,     "Event Information Table (EIT), schedule 5, actual TS" },
    { TID_EIT_SC6,     "Event Information Table (EIT), schedule 6, actual TS" },
    { TID_EIT_SC7,     "Event Information Table (EIT), schedule 7, actual TS" },
    { TID_EIT_SC8,     "Event Information Table (EIT), schedule 8, actual TS" },
    { TID_EIT_SC9,     "Event Information Table (EIT), schedule 9, actual TS" },
    { TID_EIT_SCA,     "Event Information Table (EIT), schedule A, actual TS" },
    { TID_EIT_SCB,     "Event Information Table (EIT), schedule B, actual TS" },
    { TID_EIT_SCC,     "Event Information Table (EIT), schedule C, actual TS" },
    { TID_EIT_SCD,     "Event Information Table (EIT), schedule D, actual TS" },
    { TID_EIT_SCE,     "Event Information Table (EIT), schedule E, actual TS" },
    { TID_EIT_SCF,     "Event Information Table (EIT), schedule F, actual TS" },
    { TID_EIT_SC0_OTH, "Event Information Table (EIT), schedule 0, other TS" },
    { TID_EIT_SC1_OTH, "Event Information Table (EIT), schedule 1, other TS" },
    { TID_EIT_SC2_OTH, "Event Information Table (EIT), schedule 2, other TS" },
    { TID_EIT_SC3_OTH, "Event Information Table (EIT), schedule 3, other TS" },
    { TID_EIT_SC4_OTH, "Event Information Table (EIT), schedule 4, other TS" },
    { TID_EIT_SC5_OTH, "Event Information Table (EIT), schedule 5, other TS" },
    { TID_EIT_SC6_OTH, "Event Information Table (EIT), schedule 6, other TS" },
    { TID_EIT_SC7_OTH, "Event Information Table (EIT), schedule 7, other TS" },
    { TID_EIT_SC8_OTH, "Event Information Table (EIT), schedule 8, other TS" },
    { TID_EIT_SC9_OTH, "Event Information Table (EIT), schedule 9, other TS" },
    { TID_EIT_SCA_OTH, "Event Information Table (EIT), schedule A, other TS" },
    { TID_EIT_SCB_OTH, "Event Information Table (EIT), schedule B, other TS" },
    { TID_EIT_SCC_OTH, "Event Information Table (EIT), schedule C, other TS" },
    { TID_EIT_SCD_OTH, "Event Information Table (EIT), schedule D, other TS" },
    { TID_EIT_SCE_OTH, "Event Information Table (EIT), schedule E, other TS" },
    { TID_EIT_SCF_OTH, "Event Information Table (EIT), schedule F, other TS" },
    { TID_TDT,         "Time and Date Table (TDT)" },
    { TID_RST,         "Running Status Table (RST)" },
    { TID_ST,          "Stuffing Table (ST)" },
    { TID_TOT,         "Time Offset Table (TOT)" },
    { TID_AIT,         "Application Information Table (AIT)" },
    { TID_SIT,         "Selection Information Table (SIT)" },
    { TID_SCT,         "Superframe Composition Table (SCT)" },
    { TID_FCT,         "Frame Composition Table (FCT)" },
    { TID_TCT,         "Time-Slot Composition Table (TCT)" },
    { TID_SPT,         "Satellite Position Table (SPT)" },
    { TID_CMT,         "Correction Message Table (CMT)" },
    { TID_TBTP,        "Terminal Burst Time Plan (TBTP)" },
    { TID_TIM,         "Terminal Information Message (TIM)" },
    { TID_DVB_MPE,     "DVB MultiProtocol Encapsulation (MPE)" },
    { TID_ETV_EISS,    "ETV Integrated Signaling Stream (EISS)" },
    { TID_ETV_DII,     "ETV Download Info Indication" },
    { TID_ETV_DDB,     "ETV Download Data Block" },
    { TID_FORBIDEN,    "Forbidden" },
    { 0, NULL }
};

static void mpeg_sect_prompt(packet_info *pinfo, char* result)
{
    snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Table ID %u as",
        GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_mpeg_sect, MPEG_SECT_TID_KEY)));
}

static void *mpeg_sect_value(packet_info *pinfo)
{
    return p_get_proto_data(pinfo->pool, pinfo, proto_mpeg_sect, MPEG_SECT_TID_KEY);
}

/* read a utc_time field in a tvb and write it to the utc_time struct
   the encoding of the field is according to DVB-SI specification, section 5.2.5
   16bit modified julian day (MJD), 24bit 6*4bit BCD digits hhmmss
   return the length in bytes or -1 for error */
int
packet_mpeg_sect_mjd_to_utc_time(tvbuff_t *tvb, int offset, nstime_t *utc_time)
{
    int    bcd_time_offset;     /* start offset of the bcd time in the tvbuff */
    uint8_t hour, min, sec;

    if (!utc_time)
        return -1;

    nstime_set_zero(utc_time);
    utc_time->secs  = (tvb_get_ntohs(tvb, offset) - 40587) * 86400;
    bcd_time_offset = offset+2;
    hour            = MPEG_SECT_BCD44_TO_DEC(tvb_get_uint8(tvb, bcd_time_offset));
    min             = MPEG_SECT_BCD44_TO_DEC(tvb_get_uint8(tvb, bcd_time_offset+1));
    sec             = MPEG_SECT_BCD44_TO_DEC(tvb_get_uint8(tvb, bcd_time_offset+2));
    if (hour>23 || min>59 || sec>59)
        return -1;

    utc_time->secs += hour*3600 + min*60 + sec;
    return 5;
}

unsigned
packet_mpeg_sect_header(tvbuff_t *tvb, unsigned offset,
            proto_tree *tree, unsigned *sect_len, bool *ssi)
{
    return packet_mpeg_sect_header_extra(tvb, offset, tree, sect_len,
                         NULL, ssi, NULL);
}

unsigned
packet_mpeg_sect_header_extra(tvbuff_t *tvb, unsigned offset, proto_tree *tree,
                unsigned *sect_len, unsigned *reserved, bool *ssi,
                proto_item **items)
{
    unsigned    tmp;
    unsigned    len = 0;
    proto_item *pi[PACKET_MPEG_SECT_PI__SIZE];
    int         i;

    for (i = 0; i < PACKET_MPEG_SECT_PI__SIZE; i++) {
        pi[i] = NULL;
    }

    if (tree) {
        pi[PACKET_MPEG_SECT_PI__TABLE_ID] =
            proto_tree_add_item(tree, hf_mpeg_sect_table_id,
                    tvb, offset + len, 1, ENC_BIG_ENDIAN);
    }

    len++;

    if (tree) {
        pi[PACKET_MPEG_SECT_PI__SSI] =
            proto_tree_add_item(tree, hf_mpeg_sect_syntax_indicator,
                    tvb, offset + len, 2, ENC_BIG_ENDIAN);

        pi[PACKET_MPEG_SECT_PI__RESERVED] =
            proto_tree_add_item(tree, hf_mpeg_sect_reserved, tvb,
                    offset + len, 2, ENC_BIG_ENDIAN);

        pi[PACKET_MPEG_SECT_PI__LENGTH] =
            proto_tree_add_item(tree, hf_mpeg_sect_length, tvb,
                    offset + len, 2, ENC_BIG_ENDIAN);
    }

    tmp = tvb_get_ntohs(tvb, offset + len);

    if (sect_len)
        *sect_len = MPEG_SECT_LENGTH_MASK & tmp;

    if (reserved)
        *reserved = (MPEG_SECT_RESERVED_MASK & tmp) >> 12;

    if (ssi)
        *ssi = (MPEG_SECT_SYNTAX_INDICATOR_MASK & tmp);

    if (items) {
        for (i = 0; i < PACKET_MPEG_SECT_PI__SIZE; i++) {
            items[i] = pi[i];
        }
    }

    len += 2;

    return len;
}


unsigned
packet_mpeg_sect_crc(tvbuff_t *tvb, packet_info *pinfo,
             proto_tree *tree, unsigned start, unsigned end)
{
    if (mpeg_sect_check_crc) {
        proto_tree_add_checksum(tree, tvb, end, hf_mpeg_sect_crc, hf_mpeg_sect_crc_status, &ei_mpeg_sect_crc, pinfo, crc32_mpeg2_tvb_offset(tvb, start, end),
                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);
    } else {
        proto_tree_add_checksum(tree, tvb, end, hf_mpeg_sect_crc, hf_mpeg_sect_crc_status, &ei_mpeg_sect_crc, pinfo, crc32_mpeg2_tvb_offset(tvb, start, end),
                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
    }

    return 4;
}


static int
dissect_mpeg_sect(tvbuff_t *tvb, packet_info *pinfo,
        proto_tree *tree, void *data _U_)
{
    int      tvb_len;
    int      offset           = 0;
    unsigned section_length   = 0;
    bool     syntax_indicator = false;
    uint8_t  table_id;

    proto_item *ti;
    proto_tree *mpeg_sect_tree;

    /* the incoming tvb contains only one section, no additional data */

    tvb_len = (int)tvb_reported_length(tvb);
    if (tvb_len<MPEG_SECT_MIN_LEN || tvb_len>MPEG_SECT_MAX_LEN)
        return 0;

    table_id = tvb_get_uint8(tvb, offset);
    p_add_proto_data(pinfo->pool, pinfo, proto_mpeg_sect, MPEG_SECT_TID_KEY, GUINT_TO_POINTER(table_id));

    /* Check if a dissector can parse the current table */
    if (dissector_try_uint(mpeg_sect_tid_dissector_table, table_id, tvb, pinfo, tree))
        return tvb_len;

    /* If no dissector is registered, use the common one */
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "MPEG SECT");
    col_add_fstr(pinfo->cinfo, COL_INFO, "Table ID 0x%02x", table_id);

    ti = proto_tree_add_item(tree, proto_mpeg_sect, tvb, offset, -1, ENC_NA);
    mpeg_sect_tree = proto_item_add_subtree(ti, ett_mpeg_sect);

    proto_item_append_text(ti, " Table_ID=0x%02x", table_id);

    packet_mpeg_sect_header(tvb, offset, mpeg_sect_tree,
                &section_length, &syntax_indicator);

    if (syntax_indicator)
        packet_mpeg_sect_crc(tvb, pinfo, mpeg_sect_tree, 0, (section_length-1));

    return tvb_len;
}


void
proto_register_mpeg_sect(void)
{
    static hf_register_info hf[] = {
        { &hf_mpeg_sect_table_id, {
            "Table ID", "mpeg_sect.tid",
            FT_UINT8, BASE_HEX, VALS(mpeg_sect_table_id_vals), 0, NULL, HFILL
        } },

        { &hf_mpeg_sect_syntax_indicator, {
            "Syntax indicator", "mpeg_sect.syntax_indicator",
            FT_UINT16, BASE_DEC, NULL, MPEG_SECT_SYNTAX_INDICATOR_MASK, NULL, HFILL
        } },

        { &hf_mpeg_sect_reserved, {
            "Reserved", "mpeg_sect.reserved",
            FT_UINT16, BASE_HEX, NULL, MPEG_SECT_RESERVED_MASK, NULL, HFILL
        } },

        { &hf_mpeg_sect_length, {
            "Length", "mpeg_sect.len",
            FT_UINT16, BASE_DEC, NULL, MPEG_SECT_LENGTH_MASK, NULL, HFILL
        } },

        { &hf_mpeg_sect_crc, {
            "CRC 32", "mpeg_sect.crc",
            FT_UINT32, BASE_HEX, NULL, 0, NULL, HFILL
        } },

        { &hf_mpeg_sect_crc_status, {
            "CRC 32 Status", "mpeg_sect.crc.status",
            FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0, NULL, HFILL
        } },

    };

    static int *ett[] = {
        &ett_mpeg_sect
    };

    static ei_register_info ei[] = {
        { &ei_mpeg_sect_crc, { "mpeg_sect.crc.invalid", PI_CHECKSUM, PI_WARN, "Invalid CRC", EXPFILL }},
    };

    /* Decode As handling */
    static build_valid_func mpeg_sect_da_build_value[1] = {mpeg_sect_value};
    static decode_as_value_t mpeg_sect_da_values = {mpeg_sect_prompt, 1, mpeg_sect_da_build_value};
    static decode_as_t mpeg_sect_da = {"mpeg_sect", "mpeg_sect.tid", 1, 0, &mpeg_sect_da_values, NULL, NULL, decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};

    module_t *mpeg_sect_module;
    expert_module_t* expert_mpeg_sect;

    proto_mpeg_sect = proto_register_protocol("MPEG2 Section", "MPEG SECT", "mpeg_sect");
    register_dissector("mpeg_sect", dissect_mpeg_sect, proto_mpeg_sect);

    proto_register_field_array(proto_mpeg_sect, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_mpeg_sect = expert_register_protocol(proto_mpeg_sect);
    expert_register_field_array(expert_mpeg_sect, ei, array_length(ei));

    mpeg_sect_module = prefs_register_protocol(proto_mpeg_sect, NULL);

    prefs_register_bool_preference(mpeg_sect_module,
        "verify_crc",
        "Verify the section CRC",
        "Whether the section dissector should verify the CRC",
        &mpeg_sect_check_crc);

    mpeg_sect_tid_dissector_table = register_dissector_table("mpeg_sect.tid",
                                 "MPEG SECT Table ID",
                                 proto_mpeg_sect, FT_UINT8, BASE_HEX);

    register_decode_as(&mpeg_sect_da);
}

/*
 * 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:
 */