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wireshark/epan/dissectors/packet-cl3.c

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/* packet-cl3.c
* Routines for CableLabs Layer-3 Protocol Dissection
* Copyright 2019 Jon Dennis <j.dennis[at]cablelabs.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* Dissector for IEEE-Registered CableLabs EtherType 0xB4E3
*
* IEEE EtherType List
* http://standards-oui.ieee.org/ethertype/eth.txt
*
* CableLabs Specifications Can Be Found At:
* https://www.cablelabs.com/specs
* Note: As of writing this, the spec is in the process of being published.
* Initially, this will be published under the Dual Channel Wi-Fi spec,
* but may split off into its own spec in the future.
* Eventually a direct link to the spec should be put here.
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/etypes.h>
#include <wsutil/str_util.h>
void proto_register_cl3(void);
void proto_reg_handoff_cl3(void);
/* persistent handles for this dissector */
static int proto_cl3 = -1;
static dissector_table_t cl3_command_table;
static gint ett_cl3 = -1;
static int hf_cl3_version = -1;
static int hf_cl3_headerlen = -1;
static int hf_cl3_subproto = -1;
static int hf_cl3_payload = -1;
static expert_field ei_cl3_badheaderlen = EI_INIT;
static expert_field ei_cl3_unsup_ver = EI_INIT;
/* Known CL3 (sub-)protocol type strings: */
static const value_string cl3_protocols[] = {
{0x00DC, "Dual-Channel Wi-Fi Messaging" },
{0, NULL}
};
/* called for each incomming framing matching the CL3 ethertype with a version number of 1: */
static void
dissect_cl3_v1(
tvbuff_t *tvb,
packet_info *pinfo,
proto_tree *tree,
proto_item *ti,
proto_tree *cl3_tree,
guint16 header_length
) {
dissector_handle_t dh;
tvbuff_t *tvb_sub;
guint16 subprotocol_id;
/* ensure the header length is valid for version 1 */
if (header_length != 4) {
expert_add_info(pinfo, ti, &ei_cl3_badheaderlen);
}
/* parse the sub-protocol id */
subprotocol_id = tvb_get_ntohs(tvb, 2);
/* append the subprotocol id to the "packet summary view" fields */
col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "[Subprotocol 0x%04X]", (guint)subprotocol_id);
/* add elements to the CL3 tree...
CL3 version 1 fields: (pretty much just the sub protocol id) */
proto_tree_add_uint(cl3_tree, hf_cl3_subproto, tvb, 2, 2, subprotocol_id);
/* call CL (sub-)protocol dissector */
dh = dissector_get_uint_handle(cl3_command_table, subprotocol_id);
if (dh != NULL) {
tvb_sub = tvb_new_subset_remaining(tvb, header_length);
call_dissector(dh, tvb_sub, pinfo, tree);
}
}
/* called for each incomming framing matching the CL3 ethertype: */
static int
dissect_cl3(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) {
proto_item *ti;
proto_tree *cl3_tree;
guint16 version;
guint16 header_length;
guint32 payload_length;
/* parse the header fields */
version = header_length = tvb_get_ntohs(tvb, 0);
version >>= 12;
header_length >>= 8;
header_length &= 0x0F;
header_length *= 4;
payload_length = tvb_captured_length(tvb) - header_length;
/* setup the "packet summary view" fields */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CL3");
col_clear(pinfo->cinfo, COL_INFO);
col_add_fstr(pinfo->cinfo, COL_INFO, "CableLabs Layer-3 Protocol (Ver %u)", (guint)version);
/* create a tree node for us... */
ti = proto_tree_add_protocol_format(tree, proto_cl3, tvb, 0, header_length, "CableLabs Layer-3 Protocol (CL3) Version %u", (guint)version);
cl3_tree = proto_item_add_subtree(ti, ett_cl3);
/* CL3 version agnostic fields: (pretty much just the first byte; like ipv4, version + length) */
proto_tree_add_item(cl3_tree, hf_cl3_version, tvb, 0, 1, ENC_NA);
proto_tree_add_uint_bits_format_value(cl3_tree, hf_cl3_headerlen, tvb, 0 + 4, 4, header_length,
ENC_BIG_ENDIAN, "%u bytes (%u)", header_length, header_length >> 2);
/* validate the header length... */
if ((header_length < 1) || (header_length > tvb_captured_length(tvb))) {
expert_add_info(pinfo, ti, &ei_cl3_badheaderlen);
}
/* version-specific disscection... */
switch (version) {
case 1:
dissect_cl3_v1(tvb, pinfo, tree, ti, cl3_tree, header_length);
break;
default:
expert_add_info(pinfo, ti, &ei_cl3_unsup_ver);
break;
}
/* add a byte reference to the payload we are carrying */
proto_tree_add_item(cl3_tree, hf_cl3_payload, tvb, header_length, payload_length, ENC_NA);
return tvb_captured_length(tvb);
}
/* initializes this dissector */
void
proto_register_cl3(void) {
static hf_register_info hf[] = {
{ &hf_cl3_version,
{ "Version", "cl3.version",
FT_UINT8, BASE_DEC, NULL, 0xF0,
"The CableLabs layer-3 protocol version number", HFILL }},
{ &hf_cl3_headerlen,
{ "Header Length", "cl3.headerlen",
FT_UINT8, BASE_DEC, NULL, 0x0,
"The length of the CableLabs layer-3 protocol header", HFILL }},
{ &hf_cl3_subproto,
{ "Subprotocol", "cl3.subprotocol",
FT_UINT16, BASE_HEX, VALS(cl3_protocols), 0x0,
"The subprotocol number the CableLabs layer-3 protocol is carrying", HFILL }},
{ &hf_cl3_payload,
{ "CL3 Payload", "cl3.payload",
FT_BYTES, BASE_NONE, NULL, 0x0,
"The payload carried by this CableLabs layer-3 protocol packet", HFILL}},
};
static gint *ett[] = {
&ett_cl3,
};
static ei_register_info ei[] = {
{ &ei_cl3_badheaderlen, { "cl3.badheaderlen", PI_MALFORMED, PI_ERROR, "Bad Header Length", EXPFILL }},
{ &ei_cl3_unsup_ver, { "cl3.unsup_ver", PI_UNDECODED, PI_WARN, "Unknown protocol version", EXPFILL }},
};
expert_module_t* expert_cl3;
proto_cl3 = proto_register_protocol(
"CableLabs Layer 3 Protocol", /* name */
"CL3", /* short name */
"cl3" /* abbrev */
);
proto_register_field_array(proto_cl3, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_cl3 = expert_register_protocol(proto_cl3);
expert_register_field_array(expert_cl3, ei, array_length(ei));
/* subdissector code... */
cl3_command_table = register_dissector_table("cl3.subprotocol", "CableLabs Subprotocol", proto_cl3, FT_UINT16, BASE_DEC);
}
/* hooks in our dissector to be called on matching ethertype */
void
proto_reg_handoff_cl3(void) {
dissector_handle_t cl3_handle;
cl3_handle = create_dissector_handle(&dissect_cl3, proto_cl3);
dissector_add_uint("ethertype", ETHERTYPE_CABLELABS, cl3_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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