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wireshark/epan/dissectors/packet-h263p.c
Michael Mann f4b0abc729 Dissectors don't need a journey of self discovery. 
They already know who they are when they register themselves.  Saving the
handle then to avoid finding it later.
Not sure if this will increase unnecessary register_dissector functions
(instead of using create_dissector_handle in proto_reg_handoff function)
when other dissectors copy/paste, but it should make startup time
a few microseconds better.

Change-Id: I3839be791b32b84887ac51a6a65fb5733e9f1f43
Reviewed-on: https://code.wireshark.org/review/19481
Petri-Dish: Michael Mann <mmann78@netscape.net>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>
2016-12-31 07:31:42 +00:00

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/* packet-h263p.c
*
* Routines for RFC-4629-encapsulated H.263 dissection
*
* Copyright 2003 Niklas Ogren <niklas.ogren@7l.se>
* Seven Levels Consultants AB
*
* Copyright 2008 Richard van der Hoff, MX Telecom
* <richardv@mxtelecom.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 <epan/packet.h>
#include <epan/prefs.h>
#include "packet-h263.h"
void proto_reg_handoff_h263P(void);
void proto_register_h263P(void);
static int proto_h263P = -1;
/* H.263 RFC 4629 fields */
static int hf_h263P_payload = -1;
static int hf_h263P_rr = -1;
static int hf_h263P_pbit = -1;
static int hf_h263P_vbit = -1;
static int hf_h263P_plen = -1;
static int hf_h263P_pebit = -1;
static int hf_h263P_tid = -1;
static int hf_h263P_trun = -1;
static int hf_h263P_s = -1;
static int hf_h263P_extra_hdr = -1;
/* static int hf_h263P_PSC = -1; */
/* static int hf_h263P_TR = -1; */
/* H.263-1998 fields defining a sub tree */
static gint ett_h263P = -1;
static gint ett_h263P_extra_hdr = -1;
static gint ett_h263P_payload = -1;
static gint ett_h263P_data = -1;
/* The dynamic payload type which will be dissected as H.263-1998/H263-2000 */
static guint temp_dynamic_payload_type = 0;
static dissector_handle_t h263P_handle;
/* RFC 4629 */
static int
dissect_h263P( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_ )
{
proto_item *ti = NULL;
proto_item *data_item = NULL;
proto_item *extra_hdr_item = NULL;
proto_tree *h263P_tree = NULL;
proto_tree *h263P_extr_hdr_tree = NULL;
proto_tree *h263P_data_tree = NULL;
unsigned int offset = 0;
guint16 data16, plen;
guint8 startcode;
/*
tvbuff_t *next_tvb;
*/
col_set_str(pinfo->cinfo, COL_PROTOCOL, "H.263 RFC4629 ");
if ( tree ) {
ti = proto_tree_add_item( tree, proto_h263P, tvb, offset, -1, ENC_NA );
h263P_tree = proto_item_add_subtree( ti, ett_h263P );
data16 = tvb_get_ntohs(tvb,offset);
proto_tree_add_item( h263P_tree, hf_h263P_rr, tvb, offset, 2, ENC_BIG_ENDIAN );
proto_tree_add_item( h263P_tree, hf_h263P_pbit, tvb, offset, 2, ENC_BIG_ENDIAN );
proto_tree_add_item( h263P_tree, hf_h263P_vbit, tvb, offset, 2, ENC_BIG_ENDIAN );
proto_tree_add_item( h263P_tree, hf_h263P_plen, tvb, offset, 2, ENC_BIG_ENDIAN );
proto_tree_add_item( h263P_tree, hf_h263P_pebit, tvb, offset, 2, ENC_BIG_ENDIAN );
offset = offset +2;
/*
* V: 1 bit
*
* Indicates the presence of an 8-bit field containing information
* for Video Redundancy Coding (VRC), which follows immediately after
* the initial 16 bits of the payload header, if present. For syntax
* and semantics of that 8-bit VRC field, see Section 5.2.
*/
if ((data16&0x0200)==0x0200){
/* V bit = 1
* The format of the VRC header extension is as follows:
*
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+
* | TID | Trun |S|
* +-+-+-+-+-+-+-+-+
*
* TID: 3 bits
*
* Thread ID. Up to 7 threads are allowed. Each frame of H.263+ VRC
* data will use as reference information only sync frames or frames
* within the same thread. By convention, thread 0 is expected to be
* the "canonical" thread, which is the thread from which the sync frame
* should ideally be used. In the case of corruption or loss of the
* thread 0 representation, a representation of the sync frame with a
* higher thread number can be used by the decoder. Lower thread
* numbers are expected to contain representations of the sync frames
* equal to or better than higher thread numbers in the absence of data
* corruption or loss. See [Vredun] for a detailed discussion of VRC.
*
* Trun: 4 bits
*
* Monotonically increasing (modulo 16) 4-bit number counting the packet
* number within each thread.
*
* S: 1 bit
*
* A bit that indicates that the packet content is for a sync frame.
* :
*/
proto_tree_add_item( h263P_tree, hf_h263P_tid, tvb, offset, 1, ENC_BIG_ENDIAN );
proto_tree_add_item( h263P_tree, hf_h263P_trun, tvb, offset, 1, ENC_BIG_ENDIAN );
proto_tree_add_item( h263P_tree, hf_h263P_s, tvb, offset, 1, ENC_BIG_ENDIAN );
offset++;
}
/* Length, in bytes, of the extra picture header. */
plen = (data16 & 0x01f8) >> 3;
if (plen != 0){
extra_hdr_item = proto_tree_add_item( h263P_tree, hf_h263P_extra_hdr, tvb, offset, plen, ENC_NA );
h263P_extr_hdr_tree = proto_item_add_subtree( extra_hdr_item, ett_h263P_extra_hdr );
dissect_h263_picture_layer( tvb, pinfo, h263P_extr_hdr_tree, offset, plen, TRUE);
offset += plen;
}
if ((data16&0x0400)!=0){
/* P bit = 1 */
data_item = proto_tree_add_item( h263P_tree, hf_h263P_payload, tvb, offset, -1, ENC_NA );
h263P_data_tree = proto_item_add_subtree( data_item, ett_h263P_data );
/* Startc code holds bit 17 -23 of the codeword */
startcode = tvb_get_guint8(tvb,offset)&0xfe;
if (startcode & 0x80){
/* All picture, slice, and EOSBS start codes
* shall be byte aligned, and GOB and EOS start codes may be byte aligned.
*/
switch(startcode){
case 0xf8:
/* End Of Sub-Bitstream code (EOSBS)
* EOSBS codes shall be byte aligned
* ( 1111 100. )
*/
break;
case 0x80:
case 0x82:
/* Picture Start Code (PSC)
* ( 1000 00x.)
*/
col_append_str( pinfo->cinfo, COL_INFO, "(PSC) ");
dissect_h263_picture_layer( tvb, pinfo, h263P_data_tree, offset, -1, TRUE);
break;
case 0xfc:
case 0xfe:
/* End Of Sequence (EOS)
* ( 1111 11x. )
*/
default:
/* Group of Block Start Code (GBSC) or
* Slice Start Code (SSC)
*/
col_append_str( pinfo->cinfo, COL_INFO, "(GBSC) ");
dissect_h263_group_of_blocks_layer( tvb, h263P_data_tree, offset,TRUE);
break;
}
}else{
/* Error */
}
return tvb_captured_length(tvb);
}
proto_tree_add_item( h263P_tree, hf_h263P_payload, tvb, offset, -1, ENC_NA );
}
return tvb_captured_length(tvb);
}
void
proto_reg_handoff_h263P(void)
{
static guint dynamic_payload_type;
static gboolean h263P_prefs_initialized = FALSE;
if (!h263P_prefs_initialized) {
dissector_add_string("rtp_dyn_payload_type","H263-1998", h263P_handle);
dissector_add_string("rtp_dyn_payload_type","H263-2000", h263P_handle);
h263P_prefs_initialized = TRUE;
}
else {
if ( dynamic_payload_type > 95 )
dissector_delete_uint("rtp.pt", dynamic_payload_type, h263P_handle);
}
dynamic_payload_type = temp_dynamic_payload_type;
if ( dynamic_payload_type > 95 ){
dissector_add_uint("rtp.pt", dynamic_payload_type, h263P_handle);
}
}
void
proto_register_h263P(void)
{
module_t *h263P_module;
static hf_register_info hf[] =
{
{
&hf_h263P_payload,
{
"H.263 RFC4629 payload",
"h263p.payload",
FT_NONE,
BASE_NONE,
NULL,
0x0,
"The actual H.263 RFC4629 data", HFILL
}
},
{
&hf_h263P_rr,
{
"Reserved",
"h263p.rr",
FT_UINT16,
BASE_DEC,
NULL,
0xf800,
"Reserved SHALL be zero", HFILL
}
},
{
&hf_h263P_pbit,
{
"P",
"h263p.p",
FT_BOOLEAN,
16,
NULL,
0x0400,
"Indicates (GOB/Slice) start or (EOS or EOSBS)", HFILL
}
},
{
&hf_h263P_vbit,
{
"V",
"h263p.v",
FT_BOOLEAN,
16,
NULL,
0x0200,
"presence of Video Redundancy Coding (VRC) field", HFILL
}
},
{
&hf_h263P_plen,
{
"PLEN",
"h263p.plen",
FT_UINT16,
BASE_DEC,
NULL,
0x01f8,
"Length, in bytes, of the extra picture header", HFILL
}
},
{
&hf_h263P_pebit,
{
"PEBIT",
"h263p.pebit",
FT_UINT16,
BASE_DEC,
NULL,
0x0003,
"number of bits that shall be ignored in the last byte of the picture header", HFILL
}
},
{
&hf_h263P_tid,
{
"Thread ID",
"h263p.tid",
FT_UINT8,
BASE_DEC,
NULL,
0xe0,
NULL, HFILL
}
},
{
&hf_h263P_trun,
{
"Trun",
"h263p.trun",
FT_UINT8,
BASE_DEC,
NULL,
0x1e,
"Monotonically increasing (modulo 16) 4-bit number counting the packet number within each thread", HFILL
}
},
{
&hf_h263P_s,
{
"S",
"h263p.s",
FT_UINT8,
BASE_DEC,
NULL,
0x01,
"Indicates that the packet content is for a sync frame", HFILL
}
},
{
&hf_h263P_extra_hdr,
{
"Extra picture header",
"h263p.extra_hdr",
FT_BYTES,
BASE_NONE,
NULL,
0x0,
NULL, HFILL
}
},
#if 0
{
&hf_h263P_PSC,
{
"H.263 PSC",
"h263p.PSC",
FT_UINT16,
BASE_HEX,
NULL,
0xfc00,
"Picture Start Code(PSC)", HFILL
}
},
#endif
#if 0
{
&hf_h263P_TR,
{
"H.263 Temporal Reference",
"h263p.tr",
FT_UINT16,
BASE_HEX,
NULL,
0x03fc,
"Temporal Reference, TR", HFILL
}
},
#endif
};
static gint *ett[] =
{
&ett_h263P,
&ett_h263P_extra_hdr,
&ett_h263P_payload,
&ett_h263P_data,
};
proto_h263P = proto_register_protocol("ITU-T Recommendation H.263 RTP Payload header (RFC4629)",
"H263P", "h263p");
proto_register_field_array(proto_h263P, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
h263P_module = prefs_register_protocol(proto_h263P, proto_reg_handoff_h263P);
prefs_register_uint_preference(h263P_module,
"dynamic.payload.type",
"H263-1998 and H263-2000 dynamic payload type",
"The dynamic payload type which will be interpreted as H264"
"; The value must be greater than 95",
10,
&temp_dynamic_payload_type);
h263P_handle = register_dissector("h263P", dissect_h263P, proto_h263P);
}
/*
* 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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