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/* packet-nb_rtpmux.c
* Routines for 3GPP RTP Multiplex dissection, 3GPP TS 29.414
* Copyright 2009, ip.access ltd <amp@ipaccess.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "config.h"
#include <glib.h>
#include <epan/packet.h>
void proto_register_nb_rtpmux(void);
void proto_reg_handoff_nb_rtpmux(void);
/* Initialize the protocol and registered fields */
static int proto_nb_rtpmux = -1;
static int hf_nb_rtpmux_compressed = -1;
static int hf_nb_rtpmux_dstport = -1;
static int hf_nb_rtpmux_length = -1;
static int hf_nb_r_bit = -1;
static int hf_nb_rtpmux_srcport = -1;
static int hf_nb_rtpmux_data = -1;
static int hf_nb_rtpmux_cmp_rtp_sequence_no = -1;
static int hf_nb_rtpmux_cmp_rtp_timestamp = -1;
static int hf_nb_rtpmux_cmp_rtp_data = -1;
/* Initialize the subtree pointers */
static gint ett_nb_rtpmux = -1;
static gint ett_nb_rtpmux_cmp_rtp_hdr = -1;
static dissector_handle_t rtpdissector;
static int
dissect_nb_rtpmux(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
/* Set up structures needed to add the protocol subtree and manage it */
proto_item *ti;
proto_tree *nb_rtpmux_tree, *nb_rtpmux_cmp_rtp_tree;
unsigned int offset = 0;
/* First, if at all possible, do some heuristics to check if the packet cannot
* possibly belong to your protocol. This is especially important for
* protocols directly on top of TCP or UDP where port collisions are
* common place (e.g., even though your protocol uses a well known port,
* someone else may set up, for example, a web server on that port which,
* if someone analyzed that web server's traffic in Wireshark, would result
* in Wireshark handing an HTTP packet to your dissector). For example:
*/
/*
* XXX - this is *FAR* too weak a heuristic; it could cause all sorts
* of stuff to be incorrectly identified as Nb_RTPmux. Either this
* needs a stronger heuristic, or it needs to have a preference to
* set the port on which to dissect it, or it needs to be a non-heuristic
* dissector and *require* that a user use "Decode As..." to decode
* traffic as Nb_RTPmux.
*
* Look for a payload that looks like an RTP packet, using the
* same (weakish) heuristics as RTP uses?
*/
/* Check that there's enough data */
if (tvb_captured_length(tvb) < 6)
return 0;
/* Make entries in Protocol column and Info column on summary display */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "NB_RTPMUX");
/* NOTE: The offset and length values in the call to
"proto_tree_add_item()" define what data bytes to highlight in the hex
display window when the line in the protocol tree display
corresponding to that item is selected.
Supplying a length of -1 is the way to highlight all data from the
offset to the end of the packet. */
/* create display subtree for the protocol */
while (offset < tvb_reported_length(tvb)-5)
{
guint16 dstport, srcport;
unsigned int length;
gint captured_length;
tvbuff_t *next_tvb;
gboolean tbit;
length = tvb_get_guint8(tvb, offset+2);
ti = proto_tree_add_item(tree, proto_nb_rtpmux, tvb, offset, length+5, ENC_NA);
nb_rtpmux_tree = proto_item_add_subtree(ti, ett_nb_rtpmux);
/* XXX - what if the T bit is set? */
proto_tree_add_item(nb_rtpmux_tree, hf_nb_rtpmux_compressed, tvb, offset, 2, ENC_BIG_ENDIAN);
tbit = tvb_get_guint8(tvb,offset)>>7;
if(tbit == 1){
/* 6.4.2.4 Transport Format for multiplexing with RTP header compression */
dstport = (tvb_get_ntohs(tvb, offset) & 0x7fff) << 1;
proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_dstport, tvb, offset, 2, dstport );
proto_tree_add_item(nb_rtpmux_tree, hf_nb_rtpmux_length, tvb, offset+2, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(nb_rtpmux_tree, hf_nb_r_bit, tvb, offset+3, 2, ENC_BIG_ENDIAN);
srcport = (tvb_get_ntohs(tvb, offset+3) & 0x7fff) << 1;
proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_srcport, tvb, offset+3, 2, srcport );
nb_rtpmux_cmp_rtp_tree = proto_tree_add_subtree( nb_rtpmux_tree, tvb, offset+5, 3, ett_nb_rtpmux_cmp_rtp_hdr, NULL, "Compressed RTP header" );
/* Sequence Number (SN) */
proto_tree_add_item(nb_rtpmux_cmp_rtp_tree, hf_nb_rtpmux_cmp_rtp_sequence_no, tvb, offset+5, 1, ENC_BIG_ENDIAN);
/* Timestamp (TS) */
proto_tree_add_item(nb_rtpmux_cmp_rtp_tree, hf_nb_rtpmux_cmp_rtp_timestamp, tvb, offset+6, 2, ENC_BIG_ENDIAN);
if (length != 0)
proto_tree_add_item(nb_rtpmux_cmp_rtp_tree, hf_nb_rtpmux_cmp_rtp_data,tvb, offset+8, length-3, ENC_NA);
}else{
/* 6.4.2.3 Transport Format for multiplexing without RTP Header Compression */
dstport = (tvb_get_ntohs(tvb, offset) & 0x7fff) << 1;
proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_dstport, tvb, offset, 2, dstport );
proto_tree_add_item(nb_rtpmux_tree,
hf_nb_rtpmux_length, tvb, offset+2, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(nb_rtpmux_tree, hf_nb_r_bit, tvb, offset+3, 1, ENC_BIG_ENDIAN);
srcport = (tvb_get_ntohs(tvb, offset+3) & 0x7fff) << 1;
proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_srcport, tvb, offset+3, 2, srcport );
if (length != 0)
{
/* We have an RTP payload. */
if (rtpdissector)
{
captured_length = tvb_reported_length_remaining(tvb, offset + 5);
if (captured_length > (gint)length)
captured_length = length;
next_tvb = tvb_new_subset(tvb, offset+5, captured_length,
length);
call_dissector(rtpdissector, next_tvb, pinfo, nb_rtpmux_tree);
}
else
{
proto_tree_add_item(nb_rtpmux_tree,
hf_nb_rtpmux_data, tvb, offset+5, length, ENC_NA);
}
}
} /* if tbit */
offset += 5+length;
}
/* Return the amount of data this dissector was able to dissect */
return tvb_reported_length(tvb);
}
/* Register the protocol with Wireshark */
void
proto_register_nb_rtpmux(void)
{
static hf_register_info hf[] = {
{ &hf_nb_rtpmux_compressed,
{ "Compressed headers(T bit)", "nb_rtpmux.compressed",
FT_BOOLEAN, 16, NULL, 0x8000,
NULL, HFILL }
},
{ &hf_nb_rtpmux_dstport,
{ "Dst port", "nb_rtpmux.dstport",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_nb_rtpmux_length,
{ "Length", "nb_rtpmux.length",
FT_UINT8, BASE_DEC, NULL, 0x00,
NULL, HFILL }
},
{ &hf_nb_r_bit,
{ "R bit", "nb_rtpmux.r_bit",
FT_BOOLEAN, 16, NULL, 0x8000,
NULL, HFILL }
},
{ &hf_nb_rtpmux_srcport,
{ "Src port", "nb_rtpmux.srcport",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_nb_rtpmux_data,
{ "RTP Packet", "nb_rtpmux.data",
FT_BYTES, BASE_NONE, NULL, 0x00,
NULL, HFILL }
},
{ &hf_nb_rtpmux_cmp_rtp_sequence_no,
{ "Sequence Number", "nb_rtpmux.cmp_rtp.sequence_no",
FT_UINT16, BASE_DEC, NULL, 0x00,
NULL, HFILL }
},
{ &hf_nb_rtpmux_cmp_rtp_timestamp,
{ "Timestamp", "nb_rtpmux.cmp_rtp.timestamp",
FT_UINT16, BASE_DEC, NULL, 0x00,
NULL, HFILL }
},
{ &hf_nb_rtpmux_cmp_rtp_data,
{ "RTP Data", "nb_rtpmux.cmp_rtp.data",
FT_BYTES, BASE_NONE, NULL, 0x00,
NULL,HFILL }
}
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_nb_rtpmux,
&ett_nb_rtpmux_cmp_rtp_hdr
};
/* Register the protocol name and description */
proto_nb_rtpmux = proto_register_protocol("3GPP Nb Interface RTP Multiplex",
"NB_RTPMUX", "nb_rtpmux");
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_nb_rtpmux, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
void
proto_reg_handoff_nb_rtpmux(void)
{
dissector_handle_t nb_rtpmux_handle;
/* Use new_create_dissector_handle() to indicate that dissect_nb_rtpmux()
* returns the number of bytes it dissected (or 0 if it thinks the packet
* does not belong to PROTONAME).
*/
nb_rtpmux_handle = new_create_dissector_handle(dissect_nb_rtpmux,
proto_nb_rtpmux);
dissector_add_for_decode_as("udp.port", nb_rtpmux_handle);
rtpdissector = find_dissector("rtp");
}
/*
* Editor modelines - http://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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