forked from osmocom/wireshark
310 lines
12 KiB
C
310 lines
12 KiB
C
/* packet-sync.c
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* Routines for MBMS synchronisation protocol dissection
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* Copyright 2012, David Wei <davidwei@lavabit.com>
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*
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* Ref 3GPP TS 25.446
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*/
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#include "config.h"
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#include <epan/packet.h>
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#include <epan/expert.h>
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#include <epan/crc6-tvb.h>
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#define TYPE_0_LEN 17
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#define TYPE_1_LEN 11
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#define TYPE_2_LEN 12
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#define TYPE_3_LEN 19
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void proto_register_sync(void);
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void proto_reg_handoff_sync(void);
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/* Initialize the protocol and registered fields */
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static int proto_sync = -1;
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static int hf_sync_type = -1;
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static int hf_sync_spare4 = -1;
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static int hf_sync_timestamp = -1;
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static int hf_sync_packet_nr = -1;
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static int hf_sync_elapsed_octet_ctr = -1;
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static int hf_sync_total_nr_of_packet = -1;
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static int hf_sync_total_nr_of_octet = -1;
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static int hf_sync_header_crc = -1;
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static int hf_sync_payload_crc = -1;
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static int hf_sync_length_of_packet = -1;
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/* Initialize the subtree pointers */
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static gint ett_sync = -1;
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static expert_field ei_sync_pdu_type2 = EI_INIT;
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static expert_field ei_sync_type = EI_INIT;
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static dissector_handle_t sync_handle;
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static dissector_handle_t ip_handle;
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static const value_string sync_type_vals[] = {
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{ 0, "Synchronisation frame without payload" },
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{ 1, "User data with synchronisation frame for uncompressed headers" },
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{ 2, "User data with synchronisation frame for compressed headers" },
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{ 3, "Synchronisation frame with Length of Packets" },
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/* 4-15 reserved for future PDU type extensions */
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{ 0, NULL}
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};
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static int
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dissect_sync(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
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{
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proto_item *ti, *item, *type_item;
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proto_tree *sync_tree;
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guint8 type, spare;
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guint16 packet_nr, packet_len1, packet_len2;
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guint32 timestamp, total_nr_of_packet;
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int offset = 0;
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tvbuff_t *next_tvb;
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type = tvb_get_guint8(tvb, offset) >> 4;
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spare = tvb_get_guint8(tvb, offset) & 0x0F;
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/* Heuristics to check if packet is really MBMS sync */
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#if 0
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if ( type > 3 )
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return 0;
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if ( type == 0 && tvb_captured_length(tvb) < 18) {
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return 0;
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} else if ( type == 1 && tvb_captured_length(tvb) < 11 ) {
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return 0;
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} else if ( type == 3 && tvb_captured_length(tvb) < 19 ) {
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return 0;
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}
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if ( (type != 2) && (spare != 0) )
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return 0;
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#endif
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "SYNC");
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col_set_str(pinfo->cinfo, COL_INFO, "MBMS synchronisation protocol");
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/* Ugly, but necessary to get the correct length for type 3 */
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packet_nr = tvb_get_ntohs(tvb, offset+3) + 1;
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/* The length varies depending on PDU type */
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switch (type) {
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case 0:
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ti = proto_tree_add_item(tree, proto_sync, tvb, 0, TYPE_0_LEN, ENC_NA);
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break;
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case 1:
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ti = proto_tree_add_item(tree, proto_sync, tvb, 0, TYPE_1_LEN, ENC_NA);
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break;
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case 2:
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ti = proto_tree_add_item(tree, proto_sync, tvb, 0, TYPE_2_LEN + (spare & 0x01 ? 40 : 20), ENC_NA);
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break;
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case 3:
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ti = proto_tree_add_item(tree, proto_sync, tvb, 0,
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TYPE_3_LEN + (gint16)(packet_nr % 2 == 0 ?
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1.5*packet_nr : 1.5*(packet_nr-1)+2),
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ENC_NA);
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break;
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default:
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ti = proto_tree_add_item(tree, proto_sync, tvb, 0, -1, ENC_NA);
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break;
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}
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sync_tree = proto_item_add_subtree(ti, ett_sync);
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/* Octet 1 - PDU Type */
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type_item = proto_tree_add_item(sync_tree, hf_sync_type, tvb, offset, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(sync_tree, hf_sync_spare4, tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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/* Octet 2 - Time Stamp */
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timestamp = tvb_get_ntohs(tvb, offset) * 10;
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proto_tree_add_uint(sync_tree, hf_sync_timestamp, tvb, offset, 2, timestamp);
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offset += 2;
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/* Octet 4 - Packet Number */
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proto_tree_add_uint(sync_tree, hf_sync_packet_nr, tvb, offset, 2, packet_nr);
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offset += 2;
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/* Octet 6 - Elapsed Octet Counter */
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proto_tree_add_item(sync_tree, hf_sync_elapsed_octet_ctr, tvb, offset, 4, ENC_BIG_ENDIAN);
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offset += 4;
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switch (type) {
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case 0:
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/* SYNC PDU Type 0 */
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proto_tree_add_item(sync_tree, hf_sync_total_nr_of_packet, tvb, offset, 3, ENC_BIG_ENDIAN);
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offset += 3;
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proto_tree_add_item(sync_tree, hf_sync_total_nr_of_octet, tvb, offset, 5, ENC_BIG_ENDIAN);
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offset += 5;
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proto_tree_add_item(sync_tree, hf_sync_header_crc, tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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break;
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case 1:
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/* SYNC PDU Type 1 */
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/* XXX - Calculate the CRC and check against this value? */
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item = proto_tree_add_item(sync_tree, hf_sync_header_crc, tvb, offset, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(sync_tree, hf_sync_payload_crc, tvb, offset, 2, ENC_BIG_ENDIAN);
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proto_item_append_text(item, " [Calculated CRC 0x%x]",
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crc6_compute_tvb(tvb, offset));
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offset += 2;
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/* XXX - The payload may not always be present? */
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next_tvb = tvb_new_subset_remaining(tvb, offset);
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/* XXX - The payload may not always be IP? */
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call_dissector(ip_handle, next_tvb, pinfo, tree);
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break;
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case 2:
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/* SYNC PDU Type 2 */
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expert_add_info(pinfo, ti, &ei_sync_pdu_type2);
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break;
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case 3:
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/* SYNC PDU Type 3 */
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total_nr_of_packet = tvb_get_ntoh24(tvb, offset);
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proto_tree_add_item(sync_tree, hf_sync_total_nr_of_packet, tvb, offset, 3, ENC_BIG_ENDIAN);
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offset += 3;
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proto_tree_add_item(sync_tree, hf_sync_total_nr_of_octet, tvb, offset, 5, ENC_BIG_ENDIAN);
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offset += 5;
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proto_tree_add_item(sync_tree, hf_sync_header_crc, tvb, offset, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(sync_tree, hf_sync_payload_crc, tvb, offset, 2, ENC_BIG_ENDIAN);
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offset += 2;
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if (offset < (gint)tvb_reported_length(tvb)) {
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int i;
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if (total_nr_of_packet != 0 && packet_nr % 2 == 0) {
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/* Even number of packets */
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for (i = 1; i < packet_nr; i+=2, offset+=3) {
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packet_len1 = tvb_get_bits16(tvb, offset*8, 12, ENC_BIG_ENDIAN);
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packet_len2 = tvb_get_bits16(tvb, offset*8+12, 12, ENC_BIG_ENDIAN);
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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);
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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);
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}
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} else {
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/* Odd number of packets */
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for (i = 1; i < packet_nr; i+=2, offset+=3) {
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packet_len1 = tvb_get_bits16(tvb, offset*8, 12, ENC_BIG_ENDIAN);
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packet_len2 = tvb_get_bits16(tvb, offset*8+12, 12, ENC_BIG_ENDIAN);
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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);
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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);
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}
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packet_len1 = tvb_get_bits16(tvb, offset*8, 12, ENC_BIG_ENDIAN);
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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);
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offset++;
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proto_tree_add_item(sync_tree, hf_sync_spare4, tvb, offset, 1, ENC_BIG_ENDIAN);
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}
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}
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break;
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default:
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expert_add_info(pinfo, type_item, &ei_sync_type);
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break;
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}
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return tvb_captured_length(tvb);
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}
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void
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proto_register_sync(void)
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{
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static hf_register_info hf_sync[] = {
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{ &hf_sync_type,
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{ "PDU Type", "sync.type",
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FT_UINT8, BASE_DEC, VALS(sync_type_vals), 0xF0,
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NULL, HFILL }
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},
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{ &hf_sync_spare4,
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{ "Spare", "sync.spare",
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FT_UINT8, BASE_DEC, NULL, 0x0F,
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NULL, HFILL }
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},
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{ &hf_sync_timestamp,
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{ "Timestamp", "sync.timestamp",
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FT_UINT16, BASE_DEC|BASE_UNIT_STRING, &units_milliseconds, 0x0,
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"Relative time value for the starting time of a synchronisation sequence within the synchronisation period.", HFILL }
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},
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{ &hf_sync_packet_nr,
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{ "Packet Number", "sync.packet_nr",
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FT_UINT16, BASE_DEC, NULL, 0x0,
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"Number of elapsed SYNC PDUs cumulatively within the synchronisation sequence.", HFILL }
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},
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{ &hf_sync_elapsed_octet_ctr,
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{ "Elapsed Octet Counter", "sync.elapsed_octet_ctr",
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FT_UINT32, BASE_DEC, NULL, 0x0,
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"Number of elapsed cumulative octets cumulatively within one synchronisation sequence.", HFILL }
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},
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{ &hf_sync_total_nr_of_packet,
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{ "Total Number of Packet", "sync.total_nr_of_packet",
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FT_UINT24, BASE_DEC, NULL, 0x0,
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"Cumulatively the number of the packets for the MBMS service within one synchronisation period.", HFILL }
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},
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{ &hf_sync_total_nr_of_octet,
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{ "Total Number of Octet", "sync.total_nr_of_octet",
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FT_UINT64, BASE_DEC, NULL, 0x0,
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"Cumulatively the number of the octets for the MBMS service within one synchronisation period.", HFILL }
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},
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{ &hf_sync_header_crc,
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{ "Header CRC", "sync.header_crc",
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FT_UINT8, BASE_HEX, NULL, 0xFC,
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NULL, HFILL }
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},
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{ &hf_sync_payload_crc,
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{ "Payload CRC", "sync.payload_crc",
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FT_UINT16, BASE_HEX, NULL, 0x03FF,
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NULL, HFILL }
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},
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{ &hf_sync_length_of_packet,
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{ "Length of Packet", "sync.length_of_packet",
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FT_UINT16, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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},
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};
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static gint *ett_sync_array[] = {
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&ett_sync
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};
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static ei_register_info ei[] = {
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{ &ei_sync_pdu_type2, { "sync.pdu_type2", PI_UNDECODED, PI_WARN, "SYNC PDU type 2 unsupported", EXPFILL }},
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{ &ei_sync_type, { "sync.type.unknown", PI_PROTOCOL, PI_WARN, "Unknown SYNC PDU type", EXPFILL }},
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};
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expert_module_t* expert_sync;
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proto_sync = proto_register_protocol("MBMS synchronisation protocol", "SYNC", "sync");
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proto_register_field_array(proto_sync, hf_sync, array_length(hf_sync));
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proto_register_subtree_array(ett_sync_array, array_length(ett_sync_array));
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expert_sync = expert_register_protocol(proto_sync);
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expert_register_field_array(expert_sync, ei, array_length(ei));
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sync_handle = register_dissector("sync", dissect_sync, proto_sync);
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}
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void
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proto_reg_handoff_sync(void)
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{
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ip_handle = find_dissector_add_dependency("ip", proto_sync);
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dissector_add_for_decode_as_with_preference("udp.port", sync_handle);
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}
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/*
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* Editor modelines - https://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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