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/* packet-cl3dcw.c
* Routines for CableLabs Dual-Channel Wi-Fi Messaging 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
*
* CableLabs Specifications Can Be Found At:
* https://www.cablelabs.com/specs
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
void proto_register_cl3dcw(void);
void proto_reg_handoff_cl3dcw(void);
static dissector_handle_t cl3dcw_handle;
#define SSID_MAX_LENGTH 32
/* persistent handles for this dissector */
static int proto_cl3dcw;
static int ett_cl3dcw;
static int hf_cl3dcw_type;
static int hf_cl3dcw_dccount;
static int hf_cl3dcw_datamacaddrcount;
static int hf_cl3dcw_datassidcount;
static int hf_cl3dcw_dcmacaddr;
static int hf_cl3dcw_dcssid;
static int hf_cl3dcw_dcbond;
static int ett_cl3dcw_dcbond;
static expert_field ei_cl3dcw_unknown_type;
static expert_field ei_cl3dcw_nodc;
static expert_field ei_cl3dcw_ssid_too_big;
/* message id types */
#define DCWMSG_STA_JOIN 0x01
#define DCWMSG_STA_UNJOIN 0x02
#define DCWMSG_STA_ACK 0x11
#define DCWMSG_STA_NACK 0x12
#define DCWMSG_AP_ACCEPT_STA 0x21
#define DCWMSG_AP_REJECT_STA 0x22
#define DCWMSG_AP_ACK_DISCONNECT 0x41
#define DCWMSG_AP_QUIT 0x99
/* message type strings */
static const value_string cl3dcw_msg_types[] = {
{DCWMSG_STA_JOIN, "Station Join" },
{DCWMSG_STA_UNJOIN, "Station Unjoin" },
{DCWMSG_STA_ACK, "Station Ack" },
{DCWMSG_STA_NACK, "Station Nack" },
{DCWMSG_AP_ACCEPT_STA, "AP Accept Station" },
{DCWMSG_AP_REJECT_STA, "AP Reject Station" },
{DCWMSG_AP_ACK_DISCONNECT, "AP Ack Disconnect" },
{DCWMSG_AP_QUIT, "AQ Quit" },
{0, NULL}
};
static int
dissect_sta_join(tvbuff_t * const tvb, packet_info * const pinfo, proto_tree * const tree _U_, proto_item * const ti) {
uint32_t data_macaddr_count;
int offset;
proto_tree_add_item_ret_uint(tree, hf_cl3dcw_datamacaddrcount, tvb, 0, 1, ENC_NA, &data_macaddr_count);
if (data_macaddr_count < 1) {
expert_add_info(pinfo, ti, &ei_cl3dcw_nodc);
}
offset = 1;
while(data_macaddr_count--) {
proto_tree_add_item(tree, hf_cl3dcw_dcmacaddr, tvb, offset, 6, ENC_NA);
offset += 6;
}
return offset;
}
static int
dissect_sta_unjoin(tvbuff_t * const tvb, packet_info * const pinfo, proto_tree * const tree _U_, proto_item * const ti) {
uint32_t data_macaddr_count;
int offset;
proto_tree_add_item_ret_uint(tree, hf_cl3dcw_datamacaddrcount, tvb, 0, 1, ENC_NA, &data_macaddr_count);
if (data_macaddr_count < 1) {
expert_add_info(pinfo, ti, &ei_cl3dcw_nodc);
}
offset = 1;
while (data_macaddr_count--) {
proto_tree_add_item(tree, hf_cl3dcw_dcmacaddr, tvb, offset, 6, ENC_NA);
offset += 6;
}
return offset;
}
static int
dissect_sta_ack(tvbuff_t * const tvb, packet_info * const pinfo, proto_tree * const tree _U_, proto_item * const ti) {
proto_item *bond_item;
proto_tree *bond_tree;
uint32_t data_channel_count;
uint8_t ssid_len;
uint8_t *ssidbuf;
int offset;
proto_tree_add_item_ret_uint(tree, hf_cl3dcw_dccount, tvb, 0, 1, ENC_NA, &data_channel_count);
if (data_channel_count < 1) {
expert_add_info(pinfo, ti, &ei_cl3dcw_nodc);
}
offset = 1;
while (data_channel_count--) {
/* parse each data channel bond...
* format is 6-byte mac addr + 1 byte ssid string length + ssid string
*/
ssid_len = tvb_get_uint8(tvb, offset + 6); /* +6 = skip over mac address */
if (ssid_len > SSID_MAX_LENGTH) {
expert_add_info(pinfo, ti, &ei_cl3dcw_ssid_too_big);
}
ssidbuf = tvb_get_string_enc(pinfo->pool, tvb, offset + 6 + 1, ssid_len, ENC_ASCII); /* +6+1 = skip over mac address and length field */
/* add the data channel bond sub-tree item */
bond_item = proto_tree_add_item(tree, hf_cl3dcw_dcbond, tvb, offset, 6, ENC_NA);
proto_item_append_text(bond_item, " -> \"%s\"", ssidbuf);
proto_item_set_len(bond_item, 6 + 1 + ssid_len);
bond_tree = proto_item_add_subtree(bond_item, ett_cl3dcw_dcbond);
/* add the MAC address... */
proto_tree_add_item(bond_tree, hf_cl3dcw_dcmacaddr, tvb, offset, 6, ENC_NA);
offset += 6;
/* add the SSID string
* XXX the intent here is to highlight the leading length byte in the hex dump
* without printing it in the string... i suspect there is a better way of doing this
*/
proto_tree_add_string_format(bond_tree, hf_cl3dcw_dcssid, tvb, offset, 1 + ssid_len,
"", "Data Channel SSID: %s", ssidbuf);
offset += 1 + ssid_len;
}
return offset;
}
static int
dissect_sta_nack(tvbuff_t * const tvb, packet_info * const pinfo, proto_tree * const tree _U_, proto_item * const ti) {
uint32_t data_macaddr_count;
int offset;
proto_tree_add_item_ret_uint(tree, hf_cl3dcw_datamacaddrcount, tvb, 0, 1, ENC_NA, &data_macaddr_count);
if (data_macaddr_count < 1) {
expert_add_info(pinfo, ti, &ei_cl3dcw_nodc);
}
offset = 1;
while (data_macaddr_count--) {
proto_tree_add_item(tree, hf_cl3dcw_dcmacaddr, tvb, offset, 6, ENC_NA);
offset += 6;
}
return offset;
}
static int
dissect_ap_accept_sta(tvbuff_t * const tvb, packet_info * const pinfo, proto_tree * const tree _U_, proto_item * const ti) {
uint32_t data_ssid_count;
uint8_t ssid_len;
uint8_t *ssidbuf;
int offset;
proto_tree_add_item_ret_uint(tree, hf_cl3dcw_datassidcount, tvb, 0, 1, ENC_NA, &data_ssid_count);
if (data_ssid_count < 1) {
expert_add_info(pinfo, ti, &ei_cl3dcw_nodc);
}
offset = 1;
while (data_ssid_count--) {
ssid_len = tvb_get_uint8(tvb, offset);
if (ssid_len > SSID_MAX_LENGTH) {
expert_add_info(pinfo, ti, &ei_cl3dcw_ssid_too_big);
}
ssidbuf = tvb_get_string_enc(pinfo->pool, tvb, offset + 1, ssid_len, ENC_ASCII); /* +1 = skip over length field */
/* add the SSID string
* XXX the intent here is to highlight the leading length byte in the hex dump
* without printing it in the string... i suspect there is a better way of doing this
*/
proto_tree_add_string_format(tree, hf_cl3dcw_dcssid, tvb, offset, 1 + ssid_len,
"", "Data Channel SSID: %s", ssidbuf);
offset += 1 + ssid_len;
}
return offset;
}
static int
dissect_ap_reject_sta(tvbuff_t * const tvb, packet_info * const pinfo, proto_tree * const tree _U_, proto_item * const ti) {
uint32_t data_macaddr_count;
int offset;
proto_tree_add_item_ret_uint(tree, hf_cl3dcw_datamacaddrcount, tvb, 0, 1, ENC_NA, &data_macaddr_count);
if (data_macaddr_count < 1) {
expert_add_info(pinfo, ti, &ei_cl3dcw_nodc);
}
offset = 1;
while (data_macaddr_count--) {
proto_tree_add_item(tree, hf_cl3dcw_dcmacaddr, tvb, offset, 6, ENC_NA);
offset += 6;
}
return offset;
}
/* called for each incomming framing matching our CL3 (sub-)protocol id: */
static int
dissect_cl3dcw(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree _U_, void *data _U_) {
proto_item *ti;
proto_tree *cl3dcw_tree;
tvbuff_t *tvb_msg;
int total_dcw_message_len;
uint8_t type;
/* parse the header fields */
total_dcw_message_len = 1;
type = tvb_get_uint8(tvb, 0);
/* setup the "packet summary view" fields */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CL3-DCW");
col_clear(pinfo->cinfo, COL_INFO);
col_add_fstr(pinfo->cinfo, COL_INFO, "Dual-Channel Wi-Fi %s [Type 0x%02X]", val_to_str_const(type, cl3dcw_msg_types, "Unknown"), (unsigned)type);
/* create a tree node for us... */
ti = proto_tree_add_protocol_format(tree, proto_cl3dcw, tvb, 0, tvb_captured_length(tvb), "Dual-Channel Wi-Fi Control Message");
cl3dcw_tree = proto_item_add_subtree(ti, ett_cl3dcw);
tvb_msg = tvb_new_subset_remaining(tvb, 1);
/* display dcw fields: */
proto_tree_add_uint(cl3dcw_tree, hf_cl3dcw_type, tvb, 0, 1, type);
/* parse the message by type... */
switch (type) {
case DCWMSG_STA_JOIN: total_dcw_message_len += dissect_sta_join(tvb_msg, pinfo, cl3dcw_tree, ti); break;
case DCWMSG_STA_UNJOIN: total_dcw_message_len += dissect_sta_unjoin(tvb_msg, pinfo, cl3dcw_tree, ti); break;
case DCWMSG_STA_ACK: total_dcw_message_len += dissect_sta_ack(tvb_msg, pinfo, cl3dcw_tree, ti); break;
case DCWMSG_STA_NACK: total_dcw_message_len += dissect_sta_nack(tvb_msg, pinfo, cl3dcw_tree, ti); break;
case DCWMSG_AP_ACCEPT_STA: total_dcw_message_len += dissect_ap_accept_sta(tvb_msg, pinfo, cl3dcw_tree, ti); break;
case DCWMSG_AP_REJECT_STA: total_dcw_message_len += dissect_ap_reject_sta(tvb_msg, pinfo, cl3dcw_tree, ti); break;
case DCWMSG_AP_ACK_DISCONNECT: /* nothing to really dissect */ break;
case DCWMSG_AP_QUIT: /* nothing to really dissect */ break;
default:
expert_add_info(pinfo, ti, &ei_cl3dcw_unknown_type);
return tvb_captured_length(tvb);
}
/* now that the individual message dissection functions have ran,
update the tree item length so that the hex dissection dieplay
highlighting does not include any ethernet frame padding */
proto_item_set_len(ti, total_dcw_message_len);
return total_dcw_message_len; /* is this correct ? */
}
/* initializes this dissector */
void
proto_register_cl3dcw(void) {
static hf_register_info hf[] = {
{ &hf_cl3dcw_type,
{ "Type", "cl3dcw.type",
FT_UINT8, BASE_HEX, VALS(cl3dcw_msg_types), 0x0,
NULL, HFILL }},
{ &hf_cl3dcw_dccount,
{ "Data Channel Count", "cl3dcw.dccount",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_cl3dcw_datamacaddrcount,
{ "Data MAC Address Count", "cl3dcw.datamacaddrcount",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_cl3dcw_datassidcount,
{ "Data SSID Count", "cl3dcw.datassidcount",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_cl3dcw_dcmacaddr,
{ "Data Channel MAC Address", "cl3dcw.dcmacaddr",
FT_ETHER, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
{ &hf_cl3dcw_dcssid,
{ "Data Channel SSID", "cl3dcw.dcssid",
FT_STRING, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
{ &hf_cl3dcw_dcbond,
{ "Data Channel Bond", "cl3dcw.dcbond",
FT_BYTES, SEP_COLON, NULL, 0x0,
NULL, HFILL }},
};
static int *ett[] = {
&ett_cl3dcw,
&ett_cl3dcw_dcbond,
};
static ei_register_info ei[] = {
{ &ei_cl3dcw_unknown_type, { "cl3dcw.unknown_type", PI_MALFORMED, PI_ERROR, "Unknown DCW message type", EXPFILL }},
{ &ei_cl3dcw_nodc, { "cl3dcw.no_data_channels", PI_MALFORMED, PI_WARN, "No data-channels provided", EXPFILL }},
{ &ei_cl3dcw_ssid_too_big, { "cl3dcw.ssid_too_big", PI_MALFORMED, PI_WARN, "Data channel SSID too big (expecting 32-byte maximum SSID)", EXPFILL }},
};
expert_module_t* expert_cl3dcw;
proto_cl3dcw = proto_register_protocol("CableLabs Dual-Channel Wi-Fi", "cl3dcw", "cl3dcw");
proto_register_field_array(proto_cl3dcw, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
expert_cl3dcw = expert_register_protocol(proto_cl3dcw);
expert_register_field_array(expert_cl3dcw, ei, array_length(ei));
cl3dcw_handle = register_dissector("cl3dcw", &dissect_cl3dcw, proto_cl3dcw);
}
/* hooks in our dissector to be called on matching CL3 (sub-)protocol id */
void
proto_reg_handoff_cl3dcw(void) {
dissector_add_uint("cl3.subprotocol", 0x00DC, cl3dcw_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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