268 lines
9.8 KiB
C
268 lines
9.8 KiB
C
/* packet-nb_rtpmux.c
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* Routines for 3GPP RTP Multiplex dissection, 3GPP TS 29.414
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* Copyright 2009, ip.access ltd <amp@ipaccess.com>
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*
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* $Id$
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include "config.h"
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#include <glib.h>
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#include <epan/packet.h>
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/* Initialize the protocol and registered fields */
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static int proto_nb_rtpmux = -1;
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static int hf_nb_rtpmux_compressed = -1;
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static int hf_nb_rtpmux_dstport = -1;
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static int hf_nb_rtpmux_length = -1;
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static int hf_nb_r_bit = -1;
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static int hf_nb_rtpmux_srcport = -1;
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static int hf_nb_rtpmux_data = -1;
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static int hf_nb_rtpmux_cmp_rtp_sequence_no = -1;
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static int hf_nb_rtpmux_cmp_rtp_timestamp = -1;
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static int hf_nb_rtpmux_cmp_rtp_data = -1;
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/* Initialize the subtree pointers */
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static gint ett_nb_rtpmux = -1;
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static gint ett_nb_rtpmux_cmp_rtp_hdr = -1;
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static dissector_handle_t rtpdissector;
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/* Code to actually dissect the packets */
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static int
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dissect_nb_rtpmux(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
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{
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/* Set up structures needed to add the protocol subtree and manage it */
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proto_item *ti, *cmp_rtp_item;
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proto_tree *nb_rtpmux_tree, *nb_rtpmux_cmp_rtp_tree;
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unsigned int offset = 0;
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/* First, if at all possible, do some heuristics to check if the packet cannot
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* possibly belong to your protocol. This is especially important for
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* protocols directly on top of TCP or UDP where port collisions are
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* common place (e.g., even though your protocol uses a well known port,
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* someone else may set up, for example, a web server on that port which,
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* if someone analyzed that web server's traffic in Wireshark, would result
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* in Wireshark handing an HTTP packet to your dissector). For example:
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*/
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/*
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* XXX - this is *FAR* too weak a heuristic; it could cause all sorts
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* of stuff to be incorrectly identified as Nb_RTPmux. Either this
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* needs a stronger heuristic, or it needs to have a preference to
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* set the port on which to dissect it, or it needs to be a non-heuristic
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* dissector and *require* that a user use "Decode As..." to decode
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* traffic as Nb_RTPmux.
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*
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* Look for a payload that looks like an RTP packet, using the
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* same (weakish) heuristics as RTP uses?
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*/
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/* Check that there's enough data */
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if (tvb_length(tvb) < 6)
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return 0;
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/* Make entries in Protocol column and Info column on summary display */
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "NB_RTPMUX");
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/* NOTE: The offset and length values in the call to
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"proto_tree_add_item()" define what data bytes to highlight in the hex
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display window when the line in the protocol tree display
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corresponding to that item is selected.
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Supplying a length of -1 is the way to highlight all data from the
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offset to the end of the packet. */
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/* create display subtree for the protocol */
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while (offset < tvb_reported_length(tvb)-5)
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{
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guint16 dstport, srcport;
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unsigned int length;
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gint captured_length;
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tvbuff_t* next_tvb;
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gboolean tbit;
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length = tvb_get_guint8(tvb, offset+2);
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ti = proto_tree_add_item(tree, proto_nb_rtpmux, tvb, offset,
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length+5, ENC_NA);
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nb_rtpmux_tree = proto_item_add_subtree(ti, ett_nb_rtpmux);
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/* XXX - what if the T bit is set? */
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proto_tree_add_item(nb_rtpmux_tree,
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hf_nb_rtpmux_compressed, tvb, offset, 1, ENC_BIG_ENDIAN);
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tbit = tvb_get_guint8(tvb,offset)>>7;
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if(tbit == 1){
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/* 6.4.2.4 Transport Format for multiplexing with RTP header compression */
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dstport = (tvb_get_ntohs(tvb, offset) & 0x7fff) << 1;
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proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_dstport, tvb, offset, 2, dstport );
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proto_tree_add_item(nb_rtpmux_tree,
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hf_nb_rtpmux_length, tvb, offset+2, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(nb_rtpmux_tree, hf_nb_r_bit, tvb, offset, 1, ENC_BIG_ENDIAN);
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srcport = (tvb_get_ntohs(tvb, offset+3) & 0x7fff) << 1;
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proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_srcport, tvb, offset+3, 2, srcport );
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cmp_rtp_item = proto_tree_add_text( nb_rtpmux_tree, tvb, offset+5, 3, "Compressed RTP header" );
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nb_rtpmux_cmp_rtp_tree = proto_item_add_subtree(cmp_rtp_item, ett_nb_rtpmux_cmp_rtp_hdr);
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/* Sequence Number (SN) */
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proto_tree_add_item(nb_rtpmux_cmp_rtp_tree, hf_nb_rtpmux_cmp_rtp_sequence_no, tvb, offset+5, 1, ENC_BIG_ENDIAN);
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/* Timestamp (TS) */
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proto_tree_add_item(nb_rtpmux_cmp_rtp_tree, hf_nb_rtpmux_cmp_rtp_timestamp, tvb, offset+6, 2, ENC_BIG_ENDIAN);
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if (length != 0)
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proto_tree_add_item(nb_rtpmux_cmp_rtp_tree, hf_nb_rtpmux_cmp_rtp_data,tvb, offset+8, length-3, ENC_NA);
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}else{
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/* 6.4.2.3 Transport Format for multiplexing without RTP Header Compression */
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dstport = (tvb_get_ntohs(tvb, offset) & 0x7fff) << 1;
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proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_dstport, tvb, offset, 2, dstport );
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proto_tree_add_item(nb_rtpmux_tree,
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hf_nb_rtpmux_length, tvb, offset+2, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(nb_rtpmux_tree, hf_nb_r_bit, tvb, offset, 1, ENC_BIG_ENDIAN);
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srcport = (tvb_get_ntohs(tvb, offset+3) & 0x7fff) << 1;
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proto_tree_add_uint(nb_rtpmux_tree, hf_nb_rtpmux_srcport, tvb, offset+3, 2, srcport );
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if (length != 0)
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{
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/* We have an RTP payload. */
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if (rtpdissector)
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{
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captured_length = tvb_length_remaining(tvb, offset + 5);
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if (captured_length > (gint)length)
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captured_length = length;
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next_tvb = tvb_new_subset(tvb, offset+5, captured_length,
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length);
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call_dissector(rtpdissector, next_tvb, pinfo, nb_rtpmux_tree);
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}
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else
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{
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proto_tree_add_item(nb_rtpmux_tree,
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hf_nb_rtpmux_data, tvb, offset+5, length, ENC_NA);
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}
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}
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} /* if tbit */
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offset += 5+length;
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}
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/* Return the amount of data this dissector was able to dissect */
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return tvb_length(tvb);
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}
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/* Register the protocol with Wireshark */
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/* this format is require because a script is used to build the C function
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that calls all the protocol registration.
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*/
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void
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proto_register_nb_rtpmux(void)
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{
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static hf_register_info hf[] = {
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{ &hf_nb_rtpmux_compressed,
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{ "Compressed headers(T bit)", "nb_rtpmux.compressed",
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FT_BOOLEAN, 8, NULL, 0x80,
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NULL, HFILL }
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},
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{ &hf_nb_rtpmux_dstport,
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{ "Dst port", "nb_rtpmux.dstport",
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FT_UINT16, BASE_DEC, NULL, 0x7FFF,
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NULL, HFILL }
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},
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{ &hf_nb_rtpmux_length,
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{ "Length", "nb_rtpmux.length",
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FT_UINT8, BASE_DEC, NULL, 0x00,
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NULL, HFILL }
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},
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{ &hf_nb_r_bit,
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{ "R bit", "nb_rtpmux.r_bit",
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FT_BOOLEAN, 8, NULL, 0x80,
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NULL, HFILL }
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},
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{ &hf_nb_rtpmux_srcport,
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{ "Src port", "nb_rtpmux.srcport",
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FT_UINT16, BASE_DEC, NULL, 0x7FFF,
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NULL, HFILL }
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},
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{ &hf_nb_rtpmux_data,
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{ "RTP Packet", "nb_rtpmux.data",
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FT_BYTES, BASE_NONE, NULL, 0x00,
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NULL, HFILL }
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},
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{ &hf_nb_rtpmux_cmp_rtp_sequence_no,
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{ "Sequence Number", "nb_rtpmux.cmp_rtp.sequence_no",
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FT_UINT16, BASE_DEC, NULL, 0x00,
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NULL, HFILL }
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},
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{ &hf_nb_rtpmux_cmp_rtp_timestamp,
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{ "Timestamp", "nb_rtpmux.cmp_rtp.timestamp",
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FT_UINT16, BASE_DEC, NULL, 0x00,
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NULL, HFILL }
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},
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{ &hf_nb_rtpmux_cmp_rtp_data,
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{ "RTP Data", "nb_rtpmux.cmp_rtp.data",
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FT_BYTES, BASE_NONE, NULL, 0x00,
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NULL,HFILL }
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}
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};
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/* Setup protocol subtree array */
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static gint *ett[] = {
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&ett_nb_rtpmux,
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&ett_nb_rtpmux_cmp_rtp_hdr
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};
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/* Register the protocol name and description */
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proto_nb_rtpmux = proto_register_protocol("3GPP Nb Interface RTP Multiplex",
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"NB_RTPMUX", "nb_rtpmux");
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/* Required function calls to register the header fields and subtrees used */
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proto_register_field_array(proto_nb_rtpmux, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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}
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/* If this dissector uses sub-dissector registration add a registration routine.
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This exact format is required because a script is used to find these
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routines and create the code that calls these routines.
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This function is also called by preferences whenever "Apply" is pressed
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(see prefs_register_protocol above) so it should accommodate being called
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more than once.
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*/
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void
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proto_reg_handoff_nb_rtpmux(void)
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{
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dissector_handle_t nb_rtpmux_handle;
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/* Use new_create_dissector_handle() to indicate that dissect_nb_rtpmux()
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* returns the number of bytes it dissected (or 0 if it thinks the packet
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* does not belong to PROTONAME).
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*/
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nb_rtpmux_handle = new_create_dissector_handle(dissect_nb_rtpmux,
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proto_nb_rtpmux);
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dissector_add_handle("udp.port", nb_rtpmux_handle);
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rtpdissector = find_dissector("rtp");
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}
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