/* packet-vp9.c

 * Routines for VP9 dissection

 * Copyright 2023, Noan Perrot <noan.perrot@gmail.com>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

/*

 * vp9-bitstream-specification-v0.6-20160331-draft - VP9 Bitstream & Decoding Process Specification

 * draft-ietf-payload-vp9-16 - RTP Payload Format for VP9 Video

 */

#include "config.h"

#define WS_LOG_DOMAIN "vp9"

#include <wireshark.h>

#include <epan/packet.h> /* Required dissection API header */

#include <epan/expert.h> /* Include only as needed */

#include <epan/prefs.h>  /* Include only as needed */

#define STRING_SIZE 50

#define VP9_1_BIT_MASK 0x80

#define VP9_2_BIT_MASK 0x40

#define VP9_3_BIT_MASK 0x20

#define VP9_4_BIT_MASK 0x10

#define VP9_5_BIT_MASK 0x08

#define VP9_6_BIT_MASK 0x04

#define VP9_7_BIT_MASK 0x02

#define VP9_8_BIT_MASK 0x01

#define VP9_2_BITS_MASK 0xC0

#define VP9_3_BITS_MASK 0xE0

#define VP9_7_BITS_MASK 0xFE

#define VP9_8_BITS_MASK 0xFF

#define VP9_16_BITS_MASK 0xFFFF

#define VP9_EXTENDED_PID 0x7FFF

static int proto_vp9;

static int hf_vp9_pld_i_bit;

static int hf_vp9_pld_p_bit;

static int hf_vp9_pld_l_bit;

static int hf_vp9_pld_f_bit;

static int hf_vp9_pld_b_bit;

static int hf_vp9_pld_e_bit;

static int hf_vp9_pld_v_bit;

static int hf_vp9_pld_z_bit;

static int hf_vp9_pld_u_bit;

static int hf_vp9_pld_m_bit;

static int hf_vp9_pld_d_bit;

static int hf_vp9_pld_n_bit;

static int hf_vp9_pld_y_bit;

static int hf_vp9_pld_g_bit;

static int hf_vp9_pld_pg_bits;

static int hf_vp9_pld_n_s_bits;

static int hf_vp9_pld_n_g_bits;

static int hf_vp9_pld_sid_bits;

static int hf_vp9_pld_pid_bits;

static int hf_vp9_pld_tid_bits;

static int hf_vp9_pld_width_bits;

static int hf_vp9_pld_height_bits;

static int hf_vp9_pld_n_s_numbers;

static int hf_vp9_pld_p_diff_bits;

static int hf_vp9_pld_tl0picidx_bits;

static int hf_vp9_pld_pg_extended_bits;

static int hf_vp9_pld_pid_extended_bits;

static int ett_vp9;

static int ett_vp9_descriptor;

static int *ett[] = {

    &ett_vp9,

    &ett_vp9_descriptor

};

static int

dissect_vp9(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree _U_, void *data _U_)

{

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "VP9");

    proto_item *vp9_item = proto_tree_add_item(tree, proto_vp9, tvb, 0, -1, ENC_NA);

    proto_tree *vp9_tree = proto_item_add_subtree(vp9_item, ett_vp9);

    proto_item *vp9_descriptor_item;

    proto_tree *vp9_descriptor_tree = proto_tree_add_subtree(vp9_tree, tvb, 0, 1, ett_vp9_descriptor, &vp9_descriptor_item, "Payload Descriptor");

    unsigned offset = 0;

    /*

          0 1 2 3 4 5 6 7

         +-+-+-+-+-+-+-+-+

         |I|P|L|F|B|E|V|Z| (REQUIRED)

         +-+-+-+-+-+-+-+-+

    */

    uint8_t i = tvb_get_uint8(tvb, offset) & VP9_1_BIT_MASK;

    uint8_t p = tvb_get_uint8(tvb, offset) & VP9_2_BIT_MASK;

    uint8_t l = tvb_get_uint8(tvb, offset) & VP9_3_BIT_MASK;

    uint8_t f = tvb_get_uint8(tvb, offset) & VP9_4_BIT_MASK;

    uint8_t v = tvb_get_uint8(tvb, offset) & VP9_7_BIT_MASK;

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_i_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_p_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_l_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_f_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_b_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_e_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_v_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_z_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    offset++;

    /*

         +-+-+-+-+-+-+-+-+

    I:   |M| PICTURE ID  | (REQUIRED)

         +-+-+-+-+-+-+-+-+

    M:   | EXTENDED PID  | (RECOMMENDED)

         +-+-+-+-+-+-+-+-+

    */

    uint8_t m = tvb_get_uint8(tvb, offset) & VP9_1_BIT_MASK;

    proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_m_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

    if (f)

    {

        //  Flexible mode

        if (m == i)

        {

            if (m)

            {

                //  Extended PID

                proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_pid_extended_bits, tvb, offset, 2, ENC_BIG_ENDIAN);

                offset += 2;

            }

            else

            {

                //  PID

                proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_pid_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

                offset++;

            }

        }

        else

        {

            //  Malformed packet

        }

    }

    else

    {

        //  Non-flexible mode

        if (m == i)

        {

            if (m)

            {

                //  Extended PID

                proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_pg_extended_bits, tvb, offset, 2, ENC_BIG_ENDIAN);

                offset += 2;

            }

            else

            {

                //  PID

                proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_pg_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

                offset++;

            }

        }

        else

        {

            //  Malformed packet

        }

    }

    /*

         +-+-+-+-+-+-+-+-+

    L:   | TID |U| SID |D| (Conditionally RECOMMENDED)

         +-+-+-+-+-+-+-+-+

    */

    if (l)

    {

        //  Layer indices present

        proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_tid_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_u_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_sid_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_d_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

        offset++;

        if (f)

        {

            //  1 octet is present for the layer indices

            proto_item_set_len(vp9_descriptor_item, 4);

        }

        else

        {

            //  2 octets are present for the layer indices

            proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_tl0picidx_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

            proto_item_set_len(vp9_descriptor_item, 5);

            offset++;

        }

    }

    /*

          +-+-+-+-+-+-+-+-+                             -\

     P,F: | P_DIFF      |N| (Conditionally REQUIRED)    - up to 3 times

          +-+-+-+-+-+-+-+-+                             -/

    */

    if (p && f)

    {

        uint8_t n = tvb_get_uint8(tvb, offset) & (VP9_1_BIT_MASK >> 7);

        int idx = 0;

        int max_p_diff = 3;

        while (n && idx < max_p_diff)

        {

            proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_p_diff_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

            proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_n_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

            proto_item_set_len(vp9_descriptor_item, 6);

            offset++;

            n = tvb_get_uint8(tvb, offset) & (VP9_1_BIT_MASK >> 7);

            idx++;

            if (n && idx == max_p_diff)

            {

                //  Malformed packet

            }

        }

    }

    /*

           +-+-+-+-+-+-+-+-+

      V:   | SS            |

           | ..            |

           +-+-+-+-+-+-+-+-+

    */

    if (v)

    {

        /*

             +-+-+-+-+-+-+-+-+

        V:   | N_S |Y|G|-|-|-|

             +-+-+-+-+-+-+-+-+

        */

        proto_item* n_s_numbers_field;

        uint8_t n_s = (tvb_get_uint8(tvb, offset) & (VP9_3_BITS_MASK)) >> 5;

        uint8_t y = tvb_get_uint8(tvb, offset) & (VP9_1_BIT_MASK >> 3);

        uint8_t g = tvb_get_uint8(tvb, offset) & (VP9_1_BIT_MASK >> 4);

        uint8_t number_of_spatial_layers = n_s + 1;

        proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_n_s_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

        n_s_numbers_field = proto_tree_add_uint(vp9_descriptor_tree, hf_vp9_pld_n_s_numbers, tvb, offset, 1, number_of_spatial_layers);

        proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_y_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_g_bit, tvb, offset, 1, ENC_BIG_ENDIAN);

        proto_item_set_generated(n_s_numbers_field);

        offset++;

        /*

             +-+-+-+-+-+-+-+-+              -\

        Y:   |     WIDTH     | (OPTIONAL)    .

             +               +               .

             |               | (OPTIONAL)    .

             +-+-+-+-+-+-+-+-+               . - N_S + 1 times

             |     HEIGHT    | (OPTIONAL)    .

             +               +               .

             |               | (OPTIONAL)    .

             +-+-+-+-+-+-+-+-+              -/

        */

        uint8_t spatial_layer = 0;

        while (spatial_layer < number_of_spatial_layers)

        {

            if (y)

            {

                //  TODO: Add subtree for spatial layers

                proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_width_bits, tvb, offset, 2, ENC_BIG_ENDIAN);

                offset += 2;

                proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_height_bits, tvb, offset, 2, ENC_BIG_ENDIAN);

                offset += 2;

            }

            spatial_layer++;

        }

        /*

             +-+-+-+-+-+-+-+-+

        G:   |      N_G      | (OPTIONAL)

             +-+-+-+-+-+-+-+-+

        */

        if (g)

        {

            /*

                     +-+-+-+-+-+-+-+-+                            -\

            N_G:     | TID |U| R |-|-| (OPTIONAL)                 .

                     +-+-+-+-+-+-+-+-+              -\            . - N_G times

                     |    P_DIFF     | (OPTIONAL)    . - R times  .

                     +-+-+-+-+-+-+-+-+              -/            -/

            */

            proto_tree_add_item(vp9_descriptor_tree, hf_vp9_pld_n_g_bits, tvb, offset, 1, ENC_BIG_ENDIAN);

            offset++;

            //  TODO: handle N_G

        }

    }

    return tvb_captured_length(tvb);

}

void proto_register_vp9(void)

{

    static hf_register_info hf[] = {

        {&hf_vp9_pld_i_bit,

         {"Picture ID present (I)", "vp9.pld.i",

          FT_BOOLEAN, 8,

          NULL, VP9_1_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_p_bit,

         {"Inter-picture predicted frame (P)", "vp9.pld.p",

          FT_BOOLEAN, 8,

          NULL, VP9_2_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_l_bit,

         {"Layer indices present (L)", "vp9.pld.l",

          FT_BOOLEAN, 8,

          NULL, VP9_3_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_f_bit,

         {"Flexible mode (F)", "vp9.pld.f",

          FT_BOOLEAN, 8,

          NULL, VP9_4_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_b_bit,

         {"Start of a frame (B)", "vp9.pld.b",

          FT_BOOLEAN, 8,

          NULL, VP9_5_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_e_bit,

         {"End of a frame (E)", "vp9.pld.e",

          FT_BOOLEAN, 8,

          NULL, VP9_6_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_v_bit,

         {"Scalability structure (SS) data present (V)", "vp9.pld.v",

          FT_BOOLEAN, 8,

          NULL, VP9_7_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_z_bit,

         {"Not a reference frame for upper spatial layers (Z)", "vp9.pld.z",

          FT_BOOLEAN, 8,

          NULL, VP9_8_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_m_bit,

         {"Extension flag (M)", "vp9.pld.m",

          FT_BOOLEAN, 8,

          NULL, VP9_1_BIT_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_pid_bits,

         {"Picture ID (PID)", "vp9.pld.pid",

          FT_UINT8, BASE_DEC,

          NULL, VP9_7_BITS_MASK >> 1,

          NULL, HFILL}},

        {&hf_vp9_pld_pid_extended_bits,

         {"Picture ID (PID) Extended", "vp9.pld.pid_ext",

          FT_UINT16, BASE_DEC,

          NULL, VP9_EXTENDED_PID,

          NULL, HFILL}},

        {&hf_vp9_pld_pg_bits,

         {"Picture Group Index (PG)", "vp9.pld.pg",

          FT_UINT8, BASE_DEC,

          NULL, VP9_7_BITS_MASK >> 1,

          NULL, HFILL}},

        {&hf_vp9_pld_pg_extended_bits,

         {"Picture Group Index (PG) Extended", "vp9.pld.pg_ext",

          FT_UINT16, BASE_DEC,

          NULL, VP9_EXTENDED_PID,

          NULL, HFILL}},

        {&hf_vp9_pld_tid_bits,

         {"Temporal layer ID", "vp9.pld.tid",

          FT_UINT8, BASE_DEC,

          NULL, VP9_3_BITS_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_u_bit,

         {"Switching up point (U)", "vp9.pld.u",

          FT_BOOLEAN, 8,

          NULL, VP9_1_BIT_MASK >> 3,

          NULL, HFILL}},

        {&hf_vp9_pld_sid_bits,

         {"Spatial Layer ID", "vp9.pld.sid",

          FT_UINT8, BASE_DEC,

          NULL, VP9_3_BITS_MASK >> 4,

          NULL, HFILL}},

        {&hf_vp9_pld_d_bit,

         {"Inter-layer dependency used (D)", "vp9.pld.d",

          FT_BOOLEAN, 8,

          NULL, VP9_1_BIT_MASK >> 7,

          NULL, HFILL}},

        {&hf_vp9_pld_tl0picidx_bits,

         {"Temporal layer zero index", "vp9.pld.tl0picidx",

          FT_UINT8, BASE_DEC,

          NULL, 0,

          NULL, HFILL}},

        {&hf_vp9_pld_p_diff_bits,

         {"Reference index (P_DIFF)", "vp9.pld.p_diff",

          FT_UINT8, BASE_DEC,

          NULL, VP9_7_BITS_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_n_bit,

         {"Additional reference index (N)", "vp9.pld.n",

          FT_BOOLEAN, 8,

          NULL, VP9_1_BIT_MASK >> 7,

          NULL, HFILL}},

        {&hf_vp9_pld_n_s_bits,

         {"Spatial layers minus 1 (N_S)", "vp9.pld.n_s",

          FT_UINT8, BASE_DEC,

          NULL, VP9_3_BITS_MASK,

          NULL, HFILL}},

        {&hf_vp9_pld_n_s_numbers,

         {"Number of spatial layers", "vp9.pld.spatial_layers_number",

          FT_UINT8, BASE_DEC,

          NULL, 0,

          NULL, HFILL}},

        {&hf_vp9_pld_y_bit,

         {"Spatial layer's frame resolution present (Y)", "vp9.pld.y",

          FT_BOOLEAN, 8,

          NULL, VP9_1_BIT_MASK >> 3,

          NULL, HFILL}},

        {&hf_vp9_pld_g_bit,

         {"PG description flag (G)", "vp9.pld.g",

          FT_BOOLEAN, 8,

          NULL, VP9_1_BIT_MASK >> 4,

          NULL, HFILL}},

        {&hf_vp9_pld_height_bits,

         {"Height", "vp9.pld.height",

          FT_UINT16, BASE_DEC,

          NULL, 0,

          NULL, HFILL}},

        {&hf_vp9_pld_width_bits,

         {"Width", "vp9.pld.width",

          FT_UINT16, BASE_DEC,

          NULL, 0,

          NULL, HFILL}},

        {&hf_vp9_pld_n_g_bits,

         {"Number of pictures (N_G)", "vp9.pld.n_g",

          FT_UINT8, BASE_DEC,

          NULL, 0,

          NULL, HFILL}}};

    proto_vp9 = proto_register_protocol("VP9", "VP9", "vp9");

    proto_register_field_array(proto_vp9, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

}

void proto_reg_handoff_vp9(void)

{

    static dissector_handle_t vp9_handle;

    vp9_handle = register_dissector("vp9", dissect_vp9, proto_vp9);

    dissector_add_string("rtp_dyn_payload_type", "vp9", vp9_handle);

    dissector_add_uint_range_with_preference("rtp.pt", "", vp9_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:

 */