263 lines
10 KiB
C
263 lines
10 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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* 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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#include "config.h"
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#include <epan/packet.h>
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void proto_register_nb_rtpmux(void);
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void proto_reg_handoff_nb_rtpmux(void);
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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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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;
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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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gboolean first_rtp_payload_seen = FALSE;
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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_captured_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, length+5, ENC_NA);
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nb_rtpmux_tree = proto_item_add_subtree(ti, ett_nb_rtpmux);
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/* T bit */
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proto_tree_add_item(nb_rtpmux_tree, hf_nb_rtpmux_compressed, tvb, offset, 2, 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, 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+3, 2, 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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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" );
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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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/* Not trying to decompress... */
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/* Add summary to protocol root */
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proto_item_append_text(ti, ", Src Port: %u, Dst Port: %u Length: %u", srcport, dstport, length);
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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+3, 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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/* Add summary to protocol root */
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proto_item_append_text(ti, ", Src Port: %u, Dst Port: %u Length: %u", srcport, dstport, length);
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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_reported_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_length_caplen(tvb, offset+5, captured_length,
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length);
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if (first_rtp_payload_seen)
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{
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/* Don't want to clear the column, instead show where multiple
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RTP frames are being carried */
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col_append_str(pinfo->cinfo, COL_INFO, " | ");
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col_set_fence(pinfo->cinfo, COL_INFO);
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}
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call_dissector(rtpdissector, next_tvb, pinfo, nb_rtpmux_tree);
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first_rtp_payload_seen = TRUE;
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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_reported_length(tvb);
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}
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/* Register the protocol with Wireshark */
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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, 16, NULL, 0x8000,
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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, 0x0,
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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, 16, NULL, 0x8000,
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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, 0x0,
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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", "NB_RTPMUX", "nb_rtpmux");
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register_dissector("nb_rtpmux", dissect_nb_rtpmux, proto_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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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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nb_rtpmux_handle = create_dissector_handle(dissect_nb_rtpmux, proto_nb_rtpmux);
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dissector_add_uint_range_with_preference("udp.port", "", nb_rtpmux_handle);
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rtpdissector = find_dissector_add_dependency("rtp", proto_nb_rtpmux);
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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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