/* packet-rfc2190.c
 *
 * Routines for RFC2190-encapsulated H.263 dissection
 *
 * Copyright 2003 Niklas Ogren <niklas.ogren@7l.se>
 * Seven Levels Consultants AB
 *
 * Copyright 2008 Richard van der Hoff, MX Telecom
 * <richardv@mxtelecom.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

/*
 * This dissector tries to dissect the H.263 protocol according to
 * RFC 2190, https://www.ietf.org/rfc/rfc2190
 */

#include "config.h"

#include <epan/packet.h>

#include <epan/rtp_pt.h>
#include <epan/iax2_codec_type.h>

#include "packet-h263.h"

void proto_register_rfc2190(void);
void proto_reg_handoff_rfc2190(void);

/* H.263 header fields             */
static int proto_rfc2190        = -1;

/* Mode A header */
static int hf_rfc2190_ftype = -1;
static int hf_rfc2190_pbframes = -1;
static int hf_rfc2190_sbit = -1;
static int hf_rfc2190_ebit = -1;
static int hf_rfc2190_srcformat = -1;
static int hf_rfc2190_picture_coding_type_modeA = -1;
static int hf_rfc2190_unrestricted_motion_vector_modeA = -1;
static int hf_rfc2190_syntax_based_arithmetic_modeA = -1;
static int hf_rfc2190_advanced_prediction_modeA = -1;
static int hf_rfc2190_r_modeA = -1;
static int hf_rfc2190_rr = -1;
static int hf_rfc2190_dbq = -1;
static int hf_rfc2190_trb = -1;
static int hf_rfc2190_tr = -1;
/* Additional fields for Mode B or C header */
static int hf_rfc2190_picture_coding_type_modeB = -1;
static int hf_rfc2190_unrestricted_motion_vector_modeB = -1;
static int hf_rfc2190_syntax_based_arithmetic_modeB = -1;
static int hf_rfc2190_advanced_prediction_modeB = -1;
static int hf_rfc2190_r_modeB = -1;
static int hf_rfc2190_quant = -1;
static int hf_rfc2190_gobn = -1;
static int hf_rfc2190_mba = -1;
static int hf_rfc2190_hmv1 = -1;
static int hf_rfc2190_vmv1 = -1;
static int hf_rfc2190_hmv2 = -1;
static int hf_rfc2190_vmv2 = -1;

static gint ett_rfc2190         = -1;
static dissector_handle_t h263_handle;
static dissector_handle_t rfc2190_handle;


static int
dissect_rfc2190( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_ )
{
    proto_item   *ti              = NULL;
    proto_tree   *rfc2190_tree    = NULL;
    int           offset          = 0;
    unsigned int  rfc2190_version = 0;
    tvbuff_t     *next_tvb;
    int           hdr_len         = 0;

    rfc2190_version = (tvb_get_guint8( tvb, offset ) & 0xc0 ) >> 6;

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "H.263 ");

    /* Three formats (mode A, mode B and mode C) are defined for H.263
     * payload header. In mode A, an H.263 payload header of four bytes is
     * present before actual compressed H.263 video bitstream in a packet.
     * It allows fragmentation at GOB boundaries. In mode B, an eight byte
     * H.263 payload header is used and each packet starts at MB boundaries
     * without the PB-frames option. Finally, a twelve byte H.263 payload
     * header is defined in mode C to support fragmentation at MB boundaries
     * for frames that are coded with the PB-frames option.
     */
    if( rfc2190_version == 0x00) {
        col_append_str( pinfo->cinfo, COL_INFO, "MODE A ");
        hdr_len = 4;
    }
    else if( rfc2190_version == 0x02) {
        col_append_str( pinfo->cinfo, COL_INFO, "MODE B ");
        hdr_len = 8;
    }
    else if( rfc2190_version == 0x03) {
        col_append_str( pinfo->cinfo, COL_INFO, "MODE C ");
        hdr_len = 12;
    }

    if ( tree ) {
        ti = proto_tree_add_item( tree, proto_rfc2190, tvb, offset, hdr_len, ENC_NA );
        rfc2190_tree = proto_item_add_subtree( ti, ett_rfc2190 );

        /* FBIT 1st octet, 1 bit */
        proto_tree_add_item( rfc2190_tree, hf_rfc2190_ftype, tvb, offset, 1, ENC_BIG_ENDIAN );
        /* PBIT 1st octet, 1 bit */
        proto_tree_add_item( rfc2190_tree, hf_rfc2190_pbframes, tvb, offset, 1, ENC_BIG_ENDIAN );
        /* SBIT 1st octet, 3 bits */
        proto_tree_add_item( rfc2190_tree, hf_rfc2190_sbit, tvb, offset, 1, ENC_BIG_ENDIAN );
        /* EBIT 1st octet, 3 bits */
        proto_tree_add_item( rfc2190_tree, hf_rfc2190_ebit, tvb, offset, 1, ENC_BIG_ENDIAN );
        offset++;

        /* SRC 2nd octet, 3 bits */
        proto_tree_add_item( rfc2190_tree, hf_rfc2190_srcformat, tvb, offset, 1, ENC_BIG_ENDIAN );

        if(rfc2190_version == 0x00) { /* MODE A */
            /* I flag, 1 bit */
            proto_tree_add_item(rfc2190_tree, hf_rfc2190_picture_coding_type_modeA, tvb, offset, 1, ENC_BIG_ENDIAN);
            /* U flag, 1 bit */
            proto_tree_add_item(rfc2190_tree, hf_rfc2190_unrestricted_motion_vector_modeA, tvb, offset, 1, ENC_BIG_ENDIAN);
            /* S flag, 1 bit */
            proto_tree_add_item(rfc2190_tree, hf_rfc2190_syntax_based_arithmetic_modeA, tvb, offset, 1, ENC_BIG_ENDIAN);
            /* A flag, 1 bit */
            proto_tree_add_item(rfc2190_tree, hf_rfc2190_advanced_prediction_modeA, tvb, offset, 1, ENC_BIG_ENDIAN);

            /* Reserved 2nd octet, 1 bit + 3rd octet 3 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_r_modeA, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset++;

            /* DBQ 3 octet, 2 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_dbq, tvb, offset, 1, ENC_BIG_ENDIAN );
            /* TRB 3 octet, 3 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_trb, tvb, offset, 1, ENC_BIG_ENDIAN );
            offset++;

            /* TR 4 octet, 8 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_tr, tvb, offset, 1, ENC_NA );

            offset++;

        } else { /* MODE B or MODE C */
            /* QUANT 2 octet, 5 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_quant, tvb, offset, 1, ENC_NA);

            offset++;

            /* GOBN 3 octet, 5 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_gobn, tvb, offset, 1, ENC_NA);
            /* MBA 3 octet, 3 bits + 4 octet 6 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_mba, tvb, offset, 2, ENC_BIG_ENDIAN );

            offset++;

            /* Reserved 4th octet, 2 bits */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_r_modeB, tvb, offset, 1, ENC_NA);

            offset++;

            /* I flag, 1 bit */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_picture_coding_type_modeB, tvb, offset, 1, ENC_BIG_ENDIAN);
            /* U flag, 1 bit */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_unrestricted_motion_vector_modeB, tvb, offset, 1, ENC_BIG_ENDIAN);
            /* S flag, 1 bit */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_syntax_based_arithmetic_modeB, tvb, offset, 1, ENC_BIG_ENDIAN);
            /* A flag, 1 bit */
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_advanced_prediction_modeB, tvb, offset, 1, ENC_BIG_ENDIAN);

            /* HMV1 5th octet, 4 bits + 6th octet 3 bits*/
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_hmv1, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset++;

            /* VMV1 6th octet, 5 bits + 7th octet 2 bits*/
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_vmv1, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset++;

            /* HMV2 7th octet, 6 bits + 8th octet 1 bit*/
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_hmv2, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset++;

            /* VMV2 8th octet, 7 bits*/
            proto_tree_add_item( rfc2190_tree, hf_rfc2190_vmv2, tvb, offset, 1, ENC_NA);

            offset++;

            if(rfc2190_version == 0x03) { /* MODE C */
                /* Reserved 9th to 11th octet, 8 + 8 + 3 bits */
                proto_tree_add_item( rfc2190_tree, hf_rfc2190_rr, tvb, offset, 3, ENC_BIG_ENDIAN);

                offset+=2;

                /* DBQ 11th octet, 2 bits */
                proto_tree_add_item( rfc2190_tree, hf_rfc2190_dbq, tvb, offset, 1, ENC_BIG_ENDIAN );
                /* TRB 11th octet, 3 bits */
                proto_tree_add_item( rfc2190_tree, hf_rfc2190_trb, tvb, offset, 1, ENC_BIG_ENDIAN );

                offset++;

                /* TR 12th octet, 8 bits */
                proto_tree_add_item( rfc2190_tree, hf_rfc2190_tr, tvb, offset, 1, ENC_NA );

                offset++;
            } /* end mode c */
        } /* end not mode a */
    } else {
        switch(rfc2190_version) {
            case 0x00: /* MODE A */
                offset += 4;
                break;
            case 0x01: /* MODE B */
                offset += 8;
                break;
            case 0x02: /* MODE C */
                offset += 12;
                break;
        }
    }


    /* The rest of the packet is the H.263 stream */
    next_tvb = tvb_new_subset_remaining( tvb, offset);
    call_dissector(h263_handle,next_tvb,pinfo,tree);
    return tvb_captured_length(tvb);
}

void
proto_reg_handoff_rfc2190(void)
{
    dissector_add_uint("rtp.pt", PT_H263, rfc2190_handle);
    dissector_add_uint("iax2.codec", AST_FORMAT_H263, rfc2190_handle);

    h263_handle = find_dissector_add_dependency("h263data", proto_rfc2190);
}


void
proto_register_rfc2190(void)
{
    static hf_register_info hf[] = {
        {
            &hf_rfc2190_ftype,
            {
                "F",
                "rfc2190.ftype",
                FT_BOOLEAN,
                8,
                NULL,
                0x80,
                "Indicates the mode of the payload header (MODE A or B/C)", HFILL
            }
        },
        {
            &hf_rfc2190_pbframes,
            {
                "p/b frame",
                "rfc2190.pbframes",
                FT_BOOLEAN,
                8,
                NULL,
                0x40,
                "Optional PB-frames mode as defined by H.263 (MODE C)", HFILL
            }
        },
        {
            &hf_rfc2190_sbit,
            {
                "Start bit position",
                "rfc2190.sbit",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x38,
                "Start bit position specifies number of most significant bits that shall be ignored in the first data byte.", HFILL
            }
        },
        {
            &hf_rfc2190_ebit,
            {
                "End bit position",
                "rfc2190.ebit",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x7,
                "End bit position specifies number of least significant bits that shall be ignored in the last data byte.", HFILL
            }
        },
        {
            &hf_rfc2190_srcformat,
            {
                "SRC format",
                "rfc2190.srcformat",
                FT_UINT8,
                BASE_DEC,
                VALS(h263_srcformat_vals),
                0xe0,
                "Source format specifies the resolution of the current picture.", HFILL
            }
        },
        {
            &hf_rfc2190_picture_coding_type_modeA,
            {
                "Inter-coded frame",
                "rfc2190.picture_coding_type",
                FT_BOOLEAN,
                8,
                NULL,
                0x10,
                "Picture coding type, intra-coded (false) or inter-coded (true)", HFILL
            }
        },
        {
            &hf_rfc2190_unrestricted_motion_vector_modeA,
            {
                "Motion vector",
                "rfc2190.unrestricted_motion_vector",
                FT_BOOLEAN,
                8,
                NULL,
                0x08,
                "Unrestricted Motion Vector option for current picture", HFILL
            }
        },
        {
            &hf_rfc2190_syntax_based_arithmetic_modeA,
            {
                "Syntax-based arithmetic coding",
                "rfc2190.syntax_based_arithmetic",
                FT_BOOLEAN,
                8,
                NULL,
                0x04,
                "Syntax-based Arithmetic Coding option for current picture", HFILL
            }
        },
        {
            &hf_rfc2190_advanced_prediction_modeA,
            {
                "Advanced prediction option",
                "rfc2190.advanced_prediction",
                FT_BOOLEAN,
                8,
                NULL,
                0x02,
                "Advanced Prediction option for current picture", HFILL
            }
        },
        {
            &hf_rfc2190_picture_coding_type_modeB,
            {
                "Inter-coded frame",
                "rfc2190.picture_coding_type",
                FT_BOOLEAN,
                8,
                NULL,
                0x80,
                "Picture coding type, intra-coded (false) or inter-coded (true)", HFILL
            }
        },
        {
            &hf_rfc2190_unrestricted_motion_vector_modeB,
            {
                "Motion vector",
                "rfc2190.unrestricted_motion_vector",
                FT_BOOLEAN,
                8,
                NULL,
                0x40,
                "Unrestricted Motion Vector option for current picture", HFILL
            }
        },
        {
            &hf_rfc2190_syntax_based_arithmetic_modeB,
            {
                "Syntax-based arithmetic coding",
                "rfc2190.syntax_based_arithmetic",
                FT_BOOLEAN,
                8,
                NULL,
                0x20,
                "Syntax-based Arithmetic Coding option for current picture", HFILL
            }
        },
        {
            &hf_rfc2190_advanced_prediction_modeB,
            {
                "Advanced prediction option",
                "rfc2190.advanced_prediction",
                FT_BOOLEAN,
                8,
                NULL,
                0x10,
                "Advanced Prediction option for current picture", HFILL
            }
        },
        {
            &hf_rfc2190_dbq,
            {
                "Differential quantization parameter",
                "rfc2190.dbq",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x18,
                "Differential quantization parameter used to calculate quantizer for the B frame based on quantizer for the P frame, when PB-frames option is used.", HFILL
            }
        },
        {
            &hf_rfc2190_trb,
            {
                "Temporal Reference for B frames",
                "rfc2190.trb",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x07,
                "Temporal Reference for the B frame as defined by H.263", HFILL
            }
        },
        {
            &hf_rfc2190_tr,
            {
                "Temporal Reference for P frames",
                "rfc2190.tr",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x0,
                "Temporal Reference for the P frame as defined by H.263", HFILL
            }
        },
        {
            &hf_rfc2190_quant,
            {
                "Quantizer",
                "rfc2190.quant",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x1F,
                "Quantization value for the first MB coded at the starting of the packet.", HFILL
            }
        },
        {
            &hf_rfc2190_gobn,
            {
                "GOB Number",
                "rfc2190.gobn",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0xF8,
                "GOB number in effect at the start of the packet.", HFILL
            }
        },
        {
            &hf_rfc2190_mba,
            {
                "Macroblock address",
                "rfc2190.mba",
                FT_UINT16,
                BASE_DEC,
                NULL,
                0x3FE0,
                "The address within the GOB of the first MB in the packet, counting from zero in scan order.", HFILL
            }
        },
        {
            &hf_rfc2190_hmv1,
            {
                "Horizontal motion vector 1",
                "rfc2190.hmv1",
                FT_UINT16,
                BASE_DEC,
                NULL,
                0x07F0,
                "Horizontal motion vector predictor for the first MB in this packet", HFILL
            }
        },
        {
            &hf_rfc2190_vmv1,
            {
                "Vertical motion vector 1",
                "rfc2190.vmv1",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x03F8,
                "Vertical motion vector predictor for the first MB in this packet", HFILL
            }
        },
        {
            &hf_rfc2190_hmv2,
            {
                "Horizontal motion vector 2",
                "rfc2190.hmv2",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x01FC,
                "Horizontal motion vector predictor for block number 3 in the first MB in this packet when four motion vectors are used with the advanced prediction option.", HFILL
            }
        },
        {
            &hf_rfc2190_vmv2,
            {
                "Vertical motion vector 2",
                "rfc2190.vmv2",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x7F,
                "Vertical motion vector predictor for block number 3 in the first MB in this packet when four motion vectors are used with the advanced prediction option.", HFILL
            }
        },
        {
            &hf_rfc2190_r_modeA,
            {
                "Reserved field",
                "rfc2190.r",
                FT_UINT16,
                BASE_DEC,
                NULL,
                0x01E0,
                "Reserved field that should contain zeroes", HFILL
            }
        },
        {
            &hf_rfc2190_r_modeB,
            {
                "Reserved field",
                "rfc2190.r",
                FT_UINT8,
                BASE_DEC,
                NULL,
                0x03,
                "Reserved field that should contain zeroes", HFILL
            }
        },
        {
            &hf_rfc2190_rr,
            {
                "Reserved field 2",
                "rfc2190.rr",
                FT_UINT24,
                BASE_DEC,
                NULL,
                0x07FFFF,
                "Reserved field that should contain zeroes", HFILL
            }
        },
    };

    static gint *ett[] = {
        &ett_rfc2190,
    };

    proto_register_subtree_array(ett, array_length(ett));

    proto_rfc2190 = proto_register_protocol("H.263 RTP Payload header (RFC2190)",
        "H.263 (RFC2190)", "rfc2190");

    proto_register_field_array(proto_rfc2190, hf, array_length(hf));
    rfc2190_handle = register_dissector("rfc2190", dissect_rfc2190, proto_rfc2190);
}

/*
 * 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:
 */
