/* packet-hdmi.c

 * Routines for HDMI dissection

 * Copyright 2014 Martin Kaiser <martin@kaiser.cx>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

/* this dissector handles I2C messages on the HDMI Display Data Channel (DDC)

 *

 * EDID (Extended Display Identification Data) messages are dissected here,

 * HDCP messages are passed on to the HDCP dissector

 */

#include "config.h"

#include <epan/packet.h>

void proto_register_hdmi(void);

void proto_reg_handoff_hdmi(void);

static int proto_hdmi;

static dissector_handle_t hdmi_handle;

static dissector_handle_t hdcp_handle;

static int ett_hdmi;

static int ett_hdmi_edid;

static int hf_hdmi_addr;

static int hf_hdmi_edid_offset;

static int hf_hdmi_edid_hdr;

static int hf_hdmi_edid_manf_id;

static int hf_hdmi_edid_manf_prod_code;

static int hf_hdmi_edid_manf_serial;

static int hf_hdmi_edid_manf_week;

static int hf_hdmi_edid_mod_year;

static int hf_hdmi_edid_manf_year;

static int hf_hdmi_edid_version;

/* also called Source and Sink in the HDMI spec */

#define ADDR_TRX "Transmitter"

#define ADDR_RCV "Receiver"

/* we use 8bit I2C addresses, including the direction bit */

#define ADDR8_HDCP_WRITE 0x74  /* transmitter->receiver */

#define ADDR8_HDCP_READ  0x75  /* r->t */

#define ADDR8_EDID_WRITE 0xA0  /* t->r */

#define ADDR8_EDID_READ  0xA1  /* r->t */

#define HDCP_ADDR8(x)   (x == ADDR8_HDCP_WRITE || x == ADDR8_HDCP_READ)

static const value_string hdmi_addr[] = {

    { ADDR8_HDCP_WRITE, "transmitter writes HDCP data for receiver" },

    { ADDR8_HDCP_READ,  "transmitter reads HDCP data from receiver" },

    { ADDR8_EDID_WRITE, "EDID request" },

    { ADDR8_EDID_READ,  "EDID read" },

    { 0, NULL }

};

#define EDID_HDR_VALUE UINT64_C(0x00ffffffffffff00)

/* grab 5 bits, from bit n to n+4, from a big-endian number x

   map those bits to a capital letter such that A == 1, B == 2, ... */

#define CAPITAL_LETTER(x, n) ('A'-1 + (((x) & (0x1F<<n)) >> n))

/* dissect EDID data from the receiver

   return the offset after the dissected data */

static int

dissect_hdmi_edid(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree)

{

    proto_item *yi;

    proto_tree *edid_tree;

    uint64_t    edid_hdr;

    uint16_t    manf_id;

    char        manf_id_str[4]; /* 3 letters + 0-termination */

    uint8_t     week, year;

    int         year_hf;

    edid_tree = proto_tree_add_subtree(tree, tvb,

            offset, -1, ett_hdmi_edid, NULL,

            "Extended Display Identification Data (EDID)");

    edid_hdr = tvb_get_ntoh64(tvb, offset);

    if (edid_hdr != EDID_HDR_VALUE)

        return offset; /* XXX handle fragmented EDID messages */

    col_append_sep_str(pinfo->cinfo, COL_INFO, NULL, "EDID");

    proto_tree_add_item(edid_tree, hf_hdmi_edid_hdr,

            tvb, offset, 8, ENC_LITTLE_ENDIAN);

    offset += 8;

    /* read as big endian for easier splitting */

    manf_id = tvb_get_ntohs(tvb, offset);

    /* XXX check that MSB is 0 */

    manf_id_str[0] = CAPITAL_LETTER(manf_id, 10);

    manf_id_str[1] = CAPITAL_LETTER(manf_id,  5);

    manf_id_str[2] = CAPITAL_LETTER(manf_id,  0);

    manf_id_str[3] = 0;

    proto_tree_add_string(edid_tree, hf_hdmi_edid_manf_id,

            tvb, offset, 2, manf_id_str);

    offset += 2;

    proto_tree_add_item(edid_tree, hf_hdmi_edid_manf_prod_code,

            tvb, offset, 2, ENC_LITTLE_ENDIAN);

    offset += 2;

    proto_tree_add_item(edid_tree, hf_hdmi_edid_manf_serial,

            tvb, offset, 4, ENC_LITTLE_ENDIAN);

    offset += 4;

    proto_tree_add_item_ret_uint8(edid_tree, hf_hdmi_edid_manf_week,

            tvb, offset, 1, ENC_LITTLE_ENDIAN, &week);

    offset += 1;

    year_hf = week == 255 ? hf_hdmi_edid_mod_year : hf_hdmi_edid_manf_year;

    yi = proto_tree_add_item_ret_uint8(edid_tree, year_hf,

            tvb, offset, 1, ENC_LITTLE_ENDIAN, &year);

    proto_item_append_text(yi, " (year %d)", 1990+year);

    offset += 1;

    proto_tree_add_item(edid_tree, hf_hdmi_edid_version, tvb, offset, 2, ENC_BIG_ENDIAN);

    /* XXX dissect the parts following the EDID header */

    return tvb_reported_length(tvb);

}

static int

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

{

    uint8_t     addr;

    int         offset=0;

    proto_item *pi;

    proto_tree *hdmi_tree;

    /* the I2C address in the first byte is always handled by the HDMI

       dissector, even if the packet contains HDCP data */

    addr = tvb_get_uint8(tvb, 0);

    if (!try_val_to_str(addr, hdmi_addr))

        return 0; /* no HDMI packet */

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

    col_clear(pinfo->cinfo, COL_INFO);

    pi = proto_tree_add_item(tree, proto_hdmi, tvb, 0, -1, ENC_NA);

    hdmi_tree = proto_item_add_subtree(pi, ett_hdmi);

    if (addr&0x01) {

        set_address(&pinfo->src, AT_STRINGZ, (int)strlen(ADDR_RCV)+1, ADDR_RCV);

        set_address(&pinfo->dst, AT_STRINGZ, (int)strlen(ADDR_TRX)+1, ADDR_TRX);

        pinfo->p2p_dir = P2P_DIR_RECV;

    }

    else {

        set_address(&pinfo->src, AT_STRINGZ, (int)strlen(ADDR_TRX)+1, ADDR_TRX);

        set_address(&pinfo->dst, AT_STRINGZ, (int)strlen(ADDR_RCV)+1, ADDR_RCV);

        pinfo->p2p_dir = P2P_DIR_SENT;

    }

    /* there's no explicit statement in the spec saying that the protocol is

        big or little endian

       there's three cases: one byte values, symmetrical values or values

        that are explicitly marked as little endian

       for the sake of simplicity, we use little endian everywhere */

    proto_tree_add_item(hdmi_tree, hf_hdmi_addr, tvb, offset, 1, ENC_LITTLE_ENDIAN);

    offset += 1;

    if (HDCP_ADDR8(addr)) {

        tvbuff_t *hdcp_tvb;

        hdcp_tvb = tvb_new_subset_remaining(tvb, offset);

        return call_dissector(hdcp_handle, hdcp_tvb, pinfo, hdmi_tree);

    }

    if (addr == ADDR8_EDID_WRITE) {

        col_append_sep_str(pinfo->cinfo, COL_INFO, NULL, "EDID request");

        proto_tree_add_item(hdmi_tree, hf_hdmi_edid_offset,

            tvb, offset, 1, ENC_LITTLE_ENDIAN);

        offset += 1;

        return offset;

    }

    return dissect_hdmi_edid(tvb, offset, pinfo, hdmi_tree);

}

static void

hdmi_fmt_edid_version( char *result, uint32_t revision )

{

   snprintf( result, ITEM_LABEL_LENGTH, "%d.%02d", (uint8_t)(( revision & 0xFF00 ) >> 8), (uint8_t)(revision & 0xFF) );

}

void

proto_register_hdmi(void)

{

    static hf_register_info hf[] = {

        { &hf_hdmi_addr,

            { "8bit I2C address", "hdmi.addr", FT_UINT8, BASE_HEX,

                VALS(hdmi_addr), 0, NULL, HFILL } },

        { &hf_hdmi_edid_offset,

            { "Offset", "hdmi.edid.offset",

                FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_hdr,

            { "EDID header", "hdmi.edid.hdr",

                FT_UINT64, BASE_HEX, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_manf_id,

            { "Manufacturer ID", "hdmi.edid.manf_id",

                FT_STRING, BASE_NONE, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_manf_prod_code,

            { "Manufacturer product code", "hdmi.edid.manf_prod_code",

                FT_UINT16, BASE_HEX, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_manf_serial,

            { "Serial number", "hdmi.edid.serial_num",

                FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_manf_week,

            { "Week of manufacture", "hdmi.edid.manf_week",

                FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_mod_year,

            { "Model year", "hdmi.edid.model_year",

                FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_manf_year,

            { "Year of manufacture", "hdmi.edid.manf_year",

                FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },

        { &hf_hdmi_edid_version,

            { "EDID Version", "hdmi.edid.version",

                FT_UINT16, BASE_CUSTOM, CF_FUNC(hdmi_fmt_edid_version), 0, NULL, HFILL } }

    };

    static int *ett[] = {

        &ett_hdmi,

        &ett_hdmi_edid

    };

    proto_hdmi = proto_register_protocol("High-Definition Multimedia Interface", "HDMI", "hdmi");

    hdmi_handle = register_dissector("hdmi",  dissect_hdmi, proto_hdmi );

    proto_register_field_array(proto_hdmi, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

}

void

proto_reg_handoff_hdmi(void)

{

    hdcp_handle = find_dissector_add_dependency("hdcp", proto_hdmi);

    dissector_add_for_decode_as("i2c.message", hdmi_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:

 */