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/* wimax_pdu_decoder.c
* WiMax PDU Burst decoder
*
* Copyright (c) 2007 by Intel Corporation.
*
* Author: Lu Pan <lu.pan@intel.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1999 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/* Include files */
#include "config.h"
#include <epan/packet.h>
#include "crc.h"
#include "wimax-int.h"
#include "wimax_utils.h"
extern gint proto_wimax;
void proto_reg_handoff_wimax_pdu(void);
static dissector_handle_t mac_generic_decoder_handle = NULL;
static dissector_handle_t mac_header_type1_handle = NULL;
static dissector_handle_t mac_header_type2_handle = NULL;
static dissector_handle_t wimax_harq_map_handle = NULL;
#define WIMAX_PDU_PADDING_MASK 0xFF
#define WIMAX_INVALID_PDU_MASK 0xF0
#define WIMAX_MAP_TYPE_MASK 0xE0 /* 0b111 */
#define WIMAX_HARQ_MAP_MSG_IND 0xE0 /* 0b111 */
#define WIMAX_COMPRESSED_DL_MAP_IND 0xC0 /* 0b110 */
#define REDUCED_PRIVATE_MAP_MASK 0x0C /* 0b11 */
#define WIMAX_MAC_HEADER_SIZE 6
#define WIMAX_MAC_HEADER_INFO_FIELDS 5
#define WIMAX_MAC_HEADER_HT_FIELD 0x80
#define WIMAX_MAC_HEADER_EC_FIELD 0x40
#define WIMAX_MAC_HEADER_LENGTH_MSB_MASK 0x07
#define WIMAX_HARQ_MAP_MSG_LENGTH_MASK1 0x07FC
/* Global Variables. */
gboolean first_gmh;
static gint proto_wimax_pdu_decoder = -1;
static gint ett_wimax_pdu_decoder = -1;
static int hf_wimax_value_bytes = -1;
static int dissect_wimax_pdu_decoder(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
guint offset;
guint mac_ht, mac_ec;
guint first_byte, length;
guint mac_hcs, mac_hcs_calculated;
proto_item *pdu_item = NULL;
proto_tree *pdu_tree = NULL;
#ifndef STATIC_DATA
/* generate the table of CRC32 remainders for all possible bytes */
wimax_mac_gen_crc32_table();
/* generate the table of CRC8 remainders for all possible bytes */
wimax_mac_gen_crc8_table();
#endif
/* parsing the PDU burst */
for(offset = 0; offset < tvb_reported_length(tvb); )
{
if (offset == 0)
{
first_gmh = TRUE;
}
else
{
first_gmh = FALSE;
}
/* get the length of the remainder */
length = tvb_reported_length_remaining(tvb, offset);
/* get the first byte at offset */
first_byte = tvb_get_guint8(tvb, offset);
/* check for padding */
if(first_byte == WIMAX_PDU_PADDING_MASK)
{ /* Padding */
/* display message */
pdu_item = proto_tree_add_protocol_format(tree, proto_wimax_pdu_decoder, tvb, offset, length, "Padding (%u bytes)", length);
/* add subtree */
pdu_tree = proto_item_add_subtree(pdu_item, ett_wimax_pdu_decoder);
/* display the padding in Hex */
proto_tree_add_item(pdu_tree, hf_wimax_value_bytes, tvb, offset, length, ENC_NA);
break;
}
else if((first_byte & WIMAX_MAP_TYPE_MASK) == WIMAX_HARQ_MAP_MSG_IND)
{ /* HARQ MAP message (no mac header) */
/* get the HARQ MAp Message Length */
length = ((tvb_get_ntohs(tvb, offset) & WIMAX_HARQ_MAP_MSG_LENGTH_MASK1) >> 2);
if (length == 0)
{
length = 3; /* At least 3 bytes. This prevents endless loop */
}
call_dissector(wimax_harq_map_handle, tvb_new_subset_length(tvb,offset,length), pinfo, tree);
offset += length;
continue;
}
else if((first_byte & WIMAX_MAP_TYPE_MASK) == WIMAX_COMPRESSED_DL_MAP_IND)
{
if(is_down_link(pinfo))
{ /* decode compressed dl-map without mac header */
if ((first_byte & REDUCED_PRIVATE_MAP_MASK) == REDUCED_PRIVATE_MAP_MASK)
{
length = wimax_decode_dlmap_reduced_aas(tvb, pinfo, tree);
}
else
{
length = wimax_decode_dlmapc(tvb, pinfo, tree);
}
offset += length;
continue;
}
}
else if((first_byte & WIMAX_INVALID_PDU_MASK) == WIMAX_INVALID_PDU_MASK)
{ /* Invalid PDU */
/* update the info column */
col_append_sep_str(pinfo->cinfo, COL_INFO, NULL, "Invalid PDU");
/* display message */
pdu_item = proto_tree_add_protocol_format(tree, proto_wimax_pdu_decoder, tvb, offset, length, "Invalid PDU (%u bytes)", length);
/* add subtree */
pdu_tree = proto_item_add_subtree(pdu_item, ett_wimax_pdu_decoder);
/* display the invalid MAC Header in Hex */
proto_tree_add_item(pdu_tree, hf_wimax_value_bytes, tvb, offset, length, ENC_NA);
break;
}
/* calculate the MAC header HCS */
mac_hcs_calculated = wimax_mac_calc_crc8(tvb_get_ptr(tvb, offset, WIMAX_MAC_HEADER_INFO_FIELDS), WIMAX_MAC_HEADER_INFO_FIELDS);
/* get the Header Check Sequence (HCS) in the header */
mac_hcs = tvb_get_guint8(tvb, offset + WIMAX_MAC_HEADER_SIZE - 1);
/* verify the HCS */
if(mac_hcs != mac_hcs_calculated)
{
/* update the info column */
col_append_sep_str(pinfo->cinfo, COL_INFO, NULL, "MAC Header CRC error");
/* display message */
pdu_item = proto_tree_add_protocol_format(tree, proto_wimax_pdu_decoder, tvb, offset, WIMAX_MAC_HEADER_SIZE, "MAC Header CRC error %X (in header) and %X (calculated)", mac_hcs, mac_hcs_calculated);
/* add subtree */
pdu_tree = proto_item_add_subtree(pdu_item, ett_wimax_pdu_decoder);
/* display the bad MAC Header in Hex */
proto_tree_add_item(pdu_tree, hf_wimax_value_bytes, tvb, offset, length, ENC_NA);
break;
}
/* get the Header Type (HT) */
mac_ht = ((first_byte & WIMAX_MAC_HEADER_HT_FIELD)?1:0);
/* get the Encryption Control (EC) */
mac_ec = ((first_byte & WIMAX_MAC_HEADER_EC_FIELD)?1:0);
/* update the MAC length for Generic MAC frame */
if(!mac_ht)
{ /* Generic MAC Header with payload */
/* get the MAC length */
length = (tvb_get_guint8(tvb, offset+1) & WIMAX_MAC_HEADER_LENGTH_MSB_MASK);
length = ((length<<8) | tvb_get_guint8(tvb, offset+2));
}
else /* MAC signaling Headers or Bandwidth Request Headers */
{ /* set the mac length */
length = WIMAX_MAC_HEADER_SIZE;
}
/* display PDU frame info */
/*
pdu_item = proto_tree_add_protocol_format(tree, proto_wimax_pdu_decoder, tvb, offset, length, "PDU Frame (%u bytes)", length);
*/
pdu_item = proto_tree_add_protocol_format(tree, proto_wimax_pdu_decoder, tvb, offset, length, "PDU (%u bytes)", length);
/* add PDU subtree */
pdu_tree = proto_item_add_subtree(pdu_item, ett_wimax_pdu_decoder);
if (length == 0) {
offset += 6; /* Add header size. */
/* Must skip the code below or tvb_new_subset_length()
* keeps allocating memory until it runs out. */
continue;
}
/* process the valid MAC header */
if(mac_ht)
{ /* MAC signaling Headers or Bandwidth Request Headers */
/* check the header type */
if(mac_ec)
{ /* MAC Signaling Header Type II Header */
proto_item_append_text(pdu_item, " - Mac Type II Header: ");
call_dissector(mac_header_type2_handle, tvb_new_subset_length(tvb,offset,length), pinfo, pdu_tree);
}
else
{ /* MAC Signaling Header Type I Header */
proto_item_append_text(pdu_item, " - Mac Type I Header: ");
call_dissector(mac_header_type1_handle, tvb_new_subset_length(tvb,offset,length), pinfo, pdu_tree);
}
}
else /* Generic MAC Header with payload */
{
call_dissector(mac_generic_decoder_handle, tvb_new_subset_length(tvb,offset,length), pinfo, pdu_tree);
}
offset += length;
}
return tvb_captured_length(tvb);
}
/* Register Wimax PDU Burst Protocol */
void wimax_proto_register_wimax_pdu(void)
{
/* PDU display */
static hf_register_info hf[] =
{
{
&hf_wimax_value_bytes,
{
"Values", "wmx.pdu.value",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL
}
},
};
/* Setup protocol subtree array */
static gint *ett[] =
{
&ett_wimax_pdu_decoder,
};
proto_wimax_pdu_decoder = proto_wimax;
register_dissector("wimax_pdu_burst_handler", dissect_wimax_pdu_decoder, proto_wimax_pdu_decoder);
proto_register_field_array(proto_wimax_pdu_decoder, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
void
wimax_proto_reg_handoff_wimax_pdu(void)
{
mac_generic_decoder_handle = find_dissector("mac_header_generic_handler");
mac_header_type1_handle = find_dissector("mac_header_type_1_handler");
mac_header_type2_handle = find_dissector("mac_header_type_2_handler");
wimax_harq_map_handle = find_dissector("wimax_harq_map_handler");
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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