391 lines
12 KiB
C
391 lines
12 KiB
C
/* packet-h263p.c
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*
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* Routines for RFC-4629-encapsulated H.263 dissection
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*
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* Copyright 2003 Niklas Ogren <niklas.ogren@7l.se>
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* Seven Levels Consultants AB
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*
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* Copyright 2008 Richard van der Hoff, MX Telecom
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* <richardv@mxtelecom.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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#include <epan/prefs.h>
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#include "packet-h263.h"
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void proto_reg_handoff_h263P(void);
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void proto_register_h263P(void);
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static int proto_h263P = -1;
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/* H.263 RFC 4629 fields */
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static int hf_h263P_payload = -1;
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static int hf_h263P_rr = -1;
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static int hf_h263P_pbit = -1;
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static int hf_h263P_vbit = -1;
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static int hf_h263P_plen = -1;
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static int hf_h263P_pebit = -1;
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static int hf_h263P_tid = -1;
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static int hf_h263P_trun = -1;
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static int hf_h263P_s = -1;
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static int hf_h263P_extra_hdr = -1;
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/* static int hf_h263P_PSC = -1; */
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/* static int hf_h263P_TR = -1; */
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/* H.263-1998 fields defining a sub tree */
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static gint ett_h263P = -1;
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static gint ett_h263P_extra_hdr = -1;
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static gint ett_h263P_payload = -1;
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static gint ett_h263P_data = -1;
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static dissector_handle_t h263P_handle;
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/* RFC 4629 */
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static int
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dissect_h263P( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_ )
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{
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proto_item *ti = NULL;
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proto_item *data_item = NULL;
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proto_item *extra_hdr_item = NULL;
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proto_tree *h263P_tree = NULL;
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proto_tree *h263P_extr_hdr_tree = NULL;
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proto_tree *h263P_data_tree = NULL;
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unsigned int offset = 0;
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guint16 data16, plen;
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guint8 startcode;
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/*
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tvbuff_t *next_tvb;
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*/
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "H.263 RFC4629 ");
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if ( tree ) {
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ti = proto_tree_add_item( tree, proto_h263P, tvb, offset, -1, ENC_NA );
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h263P_tree = proto_item_add_subtree( ti, ett_h263P );
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data16 = tvb_get_ntohs(tvb,offset);
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proto_tree_add_item( h263P_tree, hf_h263P_rr, tvb, offset, 2, ENC_BIG_ENDIAN );
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proto_tree_add_item( h263P_tree, hf_h263P_pbit, tvb, offset, 2, ENC_BIG_ENDIAN );
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proto_tree_add_item( h263P_tree, hf_h263P_vbit, tvb, offset, 2, ENC_BIG_ENDIAN );
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proto_tree_add_item( h263P_tree, hf_h263P_plen, tvb, offset, 2, ENC_BIG_ENDIAN );
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proto_tree_add_item( h263P_tree, hf_h263P_pebit, tvb, offset, 2, ENC_BIG_ENDIAN );
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offset = offset +2;
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/*
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* V: 1 bit
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*
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* Indicates the presence of an 8-bit field containing information
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* for Video Redundancy Coding (VRC), which follows immediately after
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* the initial 16 bits of the payload header, if present. For syntax
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* and semantics of that 8-bit VRC field, see Section 5.2.
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*/
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if ((data16&0x0200)==0x0200){
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/* V bit = 1
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* The format of the VRC header extension is as follows:
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*
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* 0 1 2 3 4 5 6 7
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* +-+-+-+-+-+-+-+-+
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* | TID | Trun |S|
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* +-+-+-+-+-+-+-+-+
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*
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* TID: 3 bits
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*
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* Thread ID. Up to 7 threads are allowed. Each frame of H.263+ VRC
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* data will use as reference information only sync frames or frames
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* within the same thread. By convention, thread 0 is expected to be
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* the "canonical" thread, which is the thread from which the sync frame
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* should ideally be used. In the case of corruption or loss of the
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* thread 0 representation, a representation of the sync frame with a
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* higher thread number can be used by the decoder. Lower thread
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* numbers are expected to contain representations of the sync frames
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* equal to or better than higher thread numbers in the absence of data
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* corruption or loss. See [Vredun] for a detailed discussion of VRC.
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*
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* Trun: 4 bits
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*
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* Monotonically increasing (modulo 16) 4-bit number counting the packet
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* number within each thread.
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*
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* S: 1 bit
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*
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* A bit that indicates that the packet content is for a sync frame.
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* :
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*/
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proto_tree_add_item( h263P_tree, hf_h263P_tid, tvb, offset, 1, ENC_BIG_ENDIAN );
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proto_tree_add_item( h263P_tree, hf_h263P_trun, tvb, offset, 1, ENC_BIG_ENDIAN );
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proto_tree_add_item( h263P_tree, hf_h263P_s, tvb, offset, 1, ENC_BIG_ENDIAN );
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offset++;
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}
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/* Length, in bytes, of the extra picture header. */
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plen = (data16 & 0x01f8) >> 3;
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if (plen != 0){
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extra_hdr_item = proto_tree_add_item( h263P_tree, hf_h263P_extra_hdr, tvb, offset, plen, ENC_NA );
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h263P_extr_hdr_tree = proto_item_add_subtree( extra_hdr_item, ett_h263P_extra_hdr );
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dissect_h263_picture_layer( tvb, pinfo, h263P_extr_hdr_tree, offset, plen, TRUE);
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offset += plen;
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}
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if ((data16&0x0400)!=0){
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/* P bit = 1 */
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data_item = proto_tree_add_item( h263P_tree, hf_h263P_payload, tvb, offset, -1, ENC_NA );
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h263P_data_tree = proto_item_add_subtree( data_item, ett_h263P_data );
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/* Startc code holds bit 17 -23 of the codeword */
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startcode = tvb_get_guint8(tvb,offset)&0xfe;
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if (startcode & 0x80){
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/* All picture, slice, and EOSBS start codes
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* shall be byte aligned, and GOB and EOS start codes may be byte aligned.
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*/
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switch(startcode){
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case 0xf8:
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/* End Of Sub-Bitstream code (EOSBS)
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* EOSBS codes shall be byte aligned
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* ( 1111 100. )
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*/
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break;
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case 0x80:
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case 0x82:
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/* Picture Start Code (PSC)
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* ( 1000 00x.)
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*/
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col_append_str( pinfo->cinfo, COL_INFO, "(PSC) ");
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dissect_h263_picture_layer( tvb, pinfo, h263P_data_tree, offset, -1, TRUE);
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break;
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case 0xfc:
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case 0xfe:
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/* End Of Sequence (EOS)
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* ( 1111 11x. )
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*/
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default:
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/* Group of Block Start Code (GBSC) or
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* Slice Start Code (SSC)
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*/
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col_append_str( pinfo->cinfo, COL_INFO, "(GBSC) ");
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dissect_h263_group_of_blocks_layer( tvb, h263P_data_tree, offset,TRUE);
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break;
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}
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}else{
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/* Error */
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}
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return tvb_captured_length(tvb);
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}
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proto_tree_add_item( h263P_tree, hf_h263P_payload, tvb, offset, -1, ENC_NA );
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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_reg_handoff_h263P(void)
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{
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dissector_add_string("rtp_dyn_payload_type","H263-1998", h263P_handle);
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dissector_add_string("rtp_dyn_payload_type","H263-2000", h263P_handle);
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dissector_add_uint_range_with_preference("rtp.pt", "", h263P_handle);
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}
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void
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proto_register_h263P(void)
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{
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module_t *h263P_module;
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static hf_register_info hf[] =
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{
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{
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&hf_h263P_payload,
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{
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"H.263 RFC4629 payload",
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"h263p.payload",
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FT_NONE,
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BASE_NONE,
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NULL,
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0x0,
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"The actual H.263 RFC4629 data", HFILL
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}
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},
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{
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&hf_h263P_rr,
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{
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"Reserved",
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"h263p.rr",
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FT_UINT16,
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BASE_DEC,
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NULL,
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0xf800,
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"Reserved SHALL be zero", HFILL
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}
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},
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{
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&hf_h263P_pbit,
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{
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"P",
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"h263p.p",
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FT_BOOLEAN,
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16,
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NULL,
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0x0400,
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"Indicates (GOB/Slice) start or (EOS or EOSBS)", HFILL
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}
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},
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{
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&hf_h263P_vbit,
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{
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"V",
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"h263p.v",
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FT_BOOLEAN,
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16,
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NULL,
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0x0200,
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"presence of Video Redundancy Coding (VRC) field", HFILL
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}
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},
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{
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&hf_h263P_plen,
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{
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"PLEN",
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"h263p.plen",
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FT_UINT16,
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BASE_DEC,
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NULL,
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0x01f8,
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"Length, in bytes, of the extra picture header", HFILL
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}
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},
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{
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&hf_h263P_pebit,
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{
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"PEBIT",
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"h263p.pebit",
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FT_UINT16,
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BASE_DEC,
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NULL,
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0x0003,
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"number of bits that shall be ignored in the last byte of the picture header", HFILL
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}
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},
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{
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&hf_h263P_tid,
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{
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"Thread ID",
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"h263p.tid",
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FT_UINT8,
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BASE_DEC,
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NULL,
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0xe0,
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NULL, HFILL
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}
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},
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{
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&hf_h263P_trun,
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{
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"Trun",
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"h263p.trun",
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FT_UINT8,
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BASE_DEC,
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NULL,
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0x1e,
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"Monotonically increasing (modulo 16) 4-bit number counting the packet number within each thread", HFILL
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}
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},
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{
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&hf_h263P_s,
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{
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"S",
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"h263p.s",
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FT_UINT8,
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BASE_DEC,
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NULL,
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0x01,
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"Indicates that the packet content is for a sync frame", HFILL
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}
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},
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{
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&hf_h263P_extra_hdr,
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{
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"Extra picture header",
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"h263p.extra_hdr",
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FT_BYTES,
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BASE_NONE,
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NULL,
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0x0,
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NULL, HFILL
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}
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},
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#if 0
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{
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&hf_h263P_PSC,
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{
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"H.263 PSC",
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"h263p.PSC",
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FT_UINT16,
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BASE_HEX,
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NULL,
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0xfc00,
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"Picture Start Code(PSC)", HFILL
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}
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},
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#endif
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#if 0
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{
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&hf_h263P_TR,
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{
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"H.263 Temporal Reference",
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"h263p.tr",
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FT_UINT16,
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BASE_HEX,
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NULL,
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0x03fc,
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"Temporal Reference, TR", HFILL
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}
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},
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#endif
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};
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static gint *ett[] =
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{
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&ett_h263P,
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&ett_h263P_extra_hdr,
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&ett_h263P_payload,
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&ett_h263P_data,
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};
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proto_h263P = proto_register_protocol("ITU-T Recommendation H.263 RTP Payload header (RFC4629)",
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"H.263P", "h263p");
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proto_register_field_array(proto_h263P, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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h263P_module = prefs_register_protocol(proto_h263P, NULL);
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prefs_register_obsolete_preference(h263P_module, "dynamic.payload.type");
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h263P_handle = register_dissector("h263P", dissect_h263P, proto_h263P);
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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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