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wireshark/epan/dissectors/packet-hdmi.c

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/* 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 = -1;
static dissector_handle_t hdcp_handle;
static gint ett_hdmi = -1;
static gint ett_hdmi_edid = -1;
static int hf_hdmi_addr = -1;
static int hf_hdmi_edid_offset = -1;
static int hf_hdmi_edid_hdr = -1;
static int hf_hdmi_edid_manf_id = -1;
static int hf_hdmi_edid_manf_prod_code = -1;
static int hf_hdmi_edid_manf_serial = -1;
static int hf_hdmi_edid_manf_week = -1;
static int hf_hdmi_edid_mod_year = -1;
static int hf_hdmi_edid_manf_year = -1;
static int hf_hdmi_edid_version = -1;
/* 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 G_GUINT64_CONSTANT(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 gint
dissect_hdmi_edid(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree)
{
proto_item *yi;
proto_tree *edid_tree;
guint64 edid_hdr;
guint16 manf_id;
gchar manf_id_str[4]; /* 3 letters + 0-termination */
guint8 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;
week = tvb_get_guint8(tvb, offset);
proto_tree_add_item(edid_tree, hf_hdmi_edid_manf_week,
tvb, offset, 1, ENC_LITTLE_ENDIAN);
offset += 1;
year_hf = week == 255 ? hf_hdmi_edid_mod_year : hf_hdmi_edid_manf_year;
year = tvb_get_guint8(tvb, offset);
yi = proto_tree_add_item(edid_tree, year_hf,
tvb, offset, 1, ENC_LITTLE_ENDIAN);
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_)
{
guint8 addr;
gint 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_guint8(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( gchar *result, guint32 revision )
{
g_snprintf( result, ITEM_LABEL_LENGTH, "%d.%02d", (guint8)(( revision & 0xFF00 ) >> 8), (guint8)(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, STR_ASCII, 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 gint *ett[] = {
&ett_hdmi,
&ett_hdmi_edid
};
proto_hdmi = proto_register_protocol(
"High-Definition Multimedia Interface", "HDMI", "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)
{
dissector_handle_t hdmi_handle;
hdcp_handle = find_dissector_add_dependency("hdcp", proto_hdmi);
hdmi_handle = create_dissector_handle( dissect_hdmi, 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:
*/
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