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/* packet-sync.c
* Routines for MBMS synchronisation protocol dissection
* Copyright 2012, David Wei <davidwei@lavabit.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* Ref 3GPP TS 25.446
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/crc6-tvb.h>
#include <epan/unit_strings.h>
#include <wsutil/array.h>
#define TYPE_0_LEN 17
#define TYPE_1_LEN 11
#define TYPE_2_LEN 12
#define TYPE_3_LEN 19
void proto_register_sync(void);
void proto_reg_handoff_sync(void);
/* Initialize the protocol and registered fields */
static int proto_sync;
static int hf_sync_type;
static int hf_sync_spare4;
static int hf_sync_timestamp;
static int hf_sync_packet_nr;
static int hf_sync_elapsed_octet_ctr;
static int hf_sync_total_nr_of_packet;
static int hf_sync_total_nr_of_octet;
static int hf_sync_header_crc;
static int hf_sync_payload_crc;
static int hf_sync_length_of_packet;
/* Initialize the subtree pointers */
static int ett_sync;
static expert_field ei_sync_pdu_type2;
static expert_field ei_sync_type;
static dissector_handle_t sync_handle;
static dissector_handle_t ip_handle;
static const value_string sync_type_vals[] = {
{ 0, "Synchronisation frame without payload" },
{ 1, "User data with synchronisation frame for uncompressed headers" },
{ 2, "User data with synchronisation frame for compressed headers" },
{ 3, "Synchronisation frame with Length of Packets" },
/* 4-15 reserved for future PDU type extensions */
{ 0, NULL}
};
static int
dissect_sync(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_item *ti, *item, *type_item;
proto_tree *sync_tree;
uint8_t type, spare;
uint16_t packet_nr, packet_len1, packet_len2;
uint32_t timestamp, total_nr_of_packet;
int offset = 0;
tvbuff_t *next_tvb;
type = tvb_get_uint8(tvb, offset) >> 4;
spare = tvb_get_uint8(tvb, offset) & 0x0F;
/* Heuristics to check if packet is really MBMS sync */
#if 0
if ( type > 3 )
return 0;
if ( type == 0 && tvb_captured_length(tvb) < 18) {
return 0;
} else if ( type == 1 && tvb_captured_length(tvb) < 11 ) {
return 0;
} else if ( type == 3 && tvb_captured_length(tvb) < 19 ) {
return 0;
}
if ( (type != 2) && (spare != 0) )
return 0;
#endif
col_set_str(pinfo->cinfo, COL_PROTOCOL, "SYNC");
col_set_str(pinfo->cinfo, COL_INFO, "MBMS synchronisation protocol");
/* Ugly, but necessary to get the correct length for type 3 */
packet_nr = tvb_get_ntohs(tvb, offset+3) + 1;
/* The length varies depending on PDU type */
switch (type) {
case 0:
ti = proto_tree_add_item(tree, proto_sync, tvb, 0, TYPE_0_LEN, ENC_NA);
break;
case 1:
ti = proto_tree_add_item(tree, proto_sync, tvb, 0, TYPE_1_LEN, ENC_NA);
break;
case 2:
ti = proto_tree_add_item(tree, proto_sync, tvb, 0, TYPE_2_LEN + (spare & 0x01 ? 40 : 20), ENC_NA);
break;
case 3:
ti = proto_tree_add_item(tree, proto_sync, tvb, 0,
TYPE_3_LEN + (int16_t)(packet_nr % 2 == 0 ?
1.5*packet_nr : 1.5*(packet_nr-1)+2),
ENC_NA);
break;
default:
ti = proto_tree_add_item(tree, proto_sync, tvb, 0, -1, ENC_NA);
break;
}
sync_tree = proto_item_add_subtree(ti, ett_sync);
/* Octet 1 - PDU Type */
type_item = proto_tree_add_item(sync_tree, hf_sync_type, tvb, offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(sync_tree, hf_sync_spare4, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
/* Octet 2 - Time Stamp */
timestamp = tvb_get_ntohs(tvb, offset) * 10;
proto_tree_add_uint(sync_tree, hf_sync_timestamp, tvb, offset, 2, timestamp);
offset += 2;
/* Octet 4 - Packet Number */
proto_tree_add_uint(sync_tree, hf_sync_packet_nr, tvb, offset, 2, packet_nr);
offset += 2;
/* Octet 6 - Elapsed Octet Counter */
proto_tree_add_item(sync_tree, hf_sync_elapsed_octet_ctr, tvb, offset, 4, ENC_BIG_ENDIAN);
offset += 4;
switch (type) {
case 0:
/* SYNC PDU Type 0 */
proto_tree_add_item(sync_tree, hf_sync_total_nr_of_packet, tvb, offset, 3, ENC_BIG_ENDIAN);
offset += 3;
proto_tree_add_item(sync_tree, hf_sync_total_nr_of_octet, tvb, offset, 5, ENC_BIG_ENDIAN);
offset += 5;
proto_tree_add_item(sync_tree, hf_sync_header_crc, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
break;
case 1:
/* SYNC PDU Type 1 */
/* XXX - Calculate the CRC and check against this value? */
item = proto_tree_add_item(sync_tree, hf_sync_header_crc, tvb, offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(sync_tree, hf_sync_payload_crc, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_item_append_text(item, " [Calculated CRC 0x%x]",
crc6_compute_tvb(tvb, offset));
offset += 2;
/* XXX - The payload may not always be present? */
next_tvb = tvb_new_subset_remaining(tvb, offset);
/* XXX - The payload may not always be IP? */
call_dissector(ip_handle, next_tvb, pinfo, tree);
break;
case 2:
/* SYNC PDU Type 2 */
expert_add_info(pinfo, ti, &ei_sync_pdu_type2);
break;
case 3:
/* SYNC PDU Type 3 */
total_nr_of_packet = tvb_get_ntoh24(tvb, offset);
proto_tree_add_item(sync_tree, hf_sync_total_nr_of_packet, tvb, offset, 3, ENC_BIG_ENDIAN);
offset += 3;
proto_tree_add_item(sync_tree, hf_sync_total_nr_of_octet, tvb, offset, 5, ENC_BIG_ENDIAN);
offset += 5;
proto_tree_add_item(sync_tree, hf_sync_header_crc, tvb, offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(sync_tree, hf_sync_payload_crc, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
if (offset < (int)tvb_reported_length(tvb)) {
int i;
if (total_nr_of_packet != 0 && packet_nr % 2 == 0) {
/* Even number of packets */
for (i = 1; i < packet_nr; i+=2, offset+=3) {
packet_len1 = tvb_get_bits16(tvb, offset*8, 12, ENC_BIG_ENDIAN);
packet_len2 = tvb_get_bits16(tvb, offset*8+12, 12, ENC_BIG_ENDIAN);
proto_tree_add_uint_format(sync_tree, hf_sync_length_of_packet, tvb, offset, 2, packet_len1, "Length of Packet %u : %hu", i, packet_len1);
proto_tree_add_uint_format(sync_tree, hf_sync_length_of_packet, tvb, offset+1, 2, packet_len2, "Length of Packet %u : %hu", i+1, packet_len2);
}
} else {
/* Odd number of packets */
for (i = 1; i < packet_nr; i+=2, offset+=3) {
packet_len1 = tvb_get_bits16(tvb, offset*8, 12, ENC_BIG_ENDIAN);
packet_len2 = tvb_get_bits16(tvb, offset*8+12, 12, ENC_BIG_ENDIAN);
proto_tree_add_uint_format(sync_tree, hf_sync_length_of_packet, tvb, offset, 2, packet_len1, "Length of Packet %u : %hu", i, packet_len1);
proto_tree_add_uint_format(sync_tree, hf_sync_length_of_packet, tvb, offset+1, 2, packet_len2, "Length of Packet %u : %hu", i+1, packet_len2);
}
packet_len1 = tvb_get_bits16(tvb, offset*8, 12, ENC_BIG_ENDIAN);
proto_tree_add_uint_format(sync_tree, hf_sync_length_of_packet, tvb, offset, 2, packet_len1, "Length of Packet %u : %hu", packet_nr, packet_len1);
offset++;
proto_tree_add_item(sync_tree, hf_sync_spare4, tvb, offset, 1, ENC_BIG_ENDIAN);
}
}
break;
default:
expert_add_info(pinfo, type_item, &ei_sync_type);
break;
}
return tvb_captured_length(tvb);
}
void
proto_register_sync(void)
{
static hf_register_info hf_sync[] = {
{ &hf_sync_type,
{ "PDU Type", "sync.type",
FT_UINT8, BASE_DEC, VALS(sync_type_vals), 0xF0,
NULL, HFILL }
},
{ &hf_sync_spare4,
{ "Spare", "sync.spare",
FT_UINT8, BASE_DEC, NULL, 0x0F,
NULL, HFILL }
},
{ &hf_sync_timestamp,
{ "Timestamp", "sync.timestamp",
FT_UINT16, BASE_DEC|BASE_UNIT_STRING, UNS(&units_milliseconds), 0x0,
"Relative time value for the starting time of a synchronisation sequence within the synchronisation period.", HFILL }
},
{ &hf_sync_packet_nr,
{ "Packet Number", "sync.packet_nr",
FT_UINT16, BASE_DEC, NULL, 0x0,
"Number of elapsed SYNC PDUs cumulatively within the synchronisation sequence.", HFILL }
},
{ &hf_sync_elapsed_octet_ctr,
{ "Elapsed Octet Counter", "sync.elapsed_octet_ctr",
FT_UINT32, BASE_DEC, NULL, 0x0,
"Number of elapsed cumulative octets cumulatively within one synchronisation sequence.", HFILL }
},
{ &hf_sync_total_nr_of_packet,
{ "Total Number of Packet", "sync.total_nr_of_packet",
FT_UINT24, BASE_DEC, NULL, 0x0,
"Cumulatively the number of the packets for the MBMS service within one synchronisation period.", HFILL }
},
{ &hf_sync_total_nr_of_octet,
{ "Total Number of Octet", "sync.total_nr_of_octet",
FT_UINT64, BASE_DEC, NULL, 0x0,
"Cumulatively the number of the octets for the MBMS service within one synchronisation period.", HFILL }
},
{ &hf_sync_header_crc,
{ "Header CRC", "sync.header_crc",
FT_UINT8, BASE_HEX, NULL, 0xFC,
NULL, HFILL }
},
{ &hf_sync_payload_crc,
{ "Payload CRC", "sync.payload_crc",
FT_UINT16, BASE_HEX, NULL, 0x03FF,
NULL, HFILL }
},
{ &hf_sync_length_of_packet,
{ "Length of Packet", "sync.length_of_packet",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
};
static int *ett_sync_array[] = {
&ett_sync
};
static ei_register_info ei[] = {
{ &ei_sync_pdu_type2, { "sync.pdu_type2", PI_UNDECODED, PI_WARN, "SYNC PDU type 2 unsupported", EXPFILL }},
{ &ei_sync_type, { "sync.type.unknown", PI_PROTOCOL, PI_WARN, "Unknown SYNC PDU type", EXPFILL }},
};
expert_module_t* expert_sync;
proto_sync = proto_register_protocol("MBMS synchronisation protocol", "SYNC", "sync");
proto_register_field_array(proto_sync, hf_sync, array_length(hf_sync));
proto_register_subtree_array(ett_sync_array, array_length(ett_sync_array));
expert_sync = expert_register_protocol(proto_sync);
expert_register_field_array(expert_sync, ei, array_length(ei));
sync_handle = register_dissector("sync", dissect_sync, proto_sync);
}
void
proto_reg_handoff_sync(void)
{
ip_handle = find_dissector_add_dependency("ip", proto_sync);
dissector_add_for_decode_as_with_preference("udp.port", sync_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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