/* packet-h261.c * * Routines for ITU-T Recommendation H.261 dissection * * $Id: packet-h261.c,v 1.20 2004/02/14 22:48:52 guy Exp $ * * Copyright 2000, Philips Electronics N.V. * Andreas Sikkema * * Ethereal - Network traffic analyzer * By Gerald Combs * 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* * This dissector tries to dissect the H.261 protocol according to Annex C * of ITU-T Recommendation H.225.0 (02/98) */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #include #include #include #include #include "rtp_pt.h" /* H.261 header fields */ static int proto_h261 = -1; static int hf_h261_sbit = -1; static int hf_h261_ebit = -1; static int hf_h261_ibit = -1; static int hf_h261_vbit = -1; static int hf_h261_gobn = -1; static int hf_h261_mbap = -1; static int hf_h261_quant = -1; static int hf_h261_hmvd = -1; /* Mislabeled in a figure in section C.3.1 as HMDV */ static int hf_h261_vmvd = -1; static int hf_h261_data = -1; /* H.261 fields defining a sub tree */ static gint ett_h261 = -1; static void dissect_h261( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) { proto_item *ti = NULL; proto_tree *h261_tree = NULL; unsigned int offset = 0; if ( check_col( pinfo->cinfo, COL_PROTOCOL ) ) { col_set_str( pinfo->cinfo, COL_PROTOCOL, "H.261" ); } if ( check_col( pinfo->cinfo, COL_INFO) ) { col_set_str( pinfo->cinfo, COL_INFO, "H.261 message"); } if ( tree ) { ti = proto_tree_add_item( tree, proto_h261, tvb, offset, -1, FALSE ); h261_tree = proto_item_add_subtree( ti, ett_h261 ); /* SBIT 1st octet, 3 bits */ proto_tree_add_uint( h261_tree, hf_h261_sbit, tvb, offset, 1, tvb_get_guint8( tvb, offset ) >> 5 ); /* EBIT 1st octet, 3 bits */ proto_tree_add_uint( h261_tree, hf_h261_ebit, tvb, offset, 1, ( tvb_get_guint8( tvb, offset ) << 3 ) >> 5 ); /* I flag, 1 bit */ proto_tree_add_boolean( h261_tree, hf_h261_ibit, tvb, offset, 1, tvb_get_guint8( tvb, offset ) & 2 ); /* V flag, 1 bit */ proto_tree_add_boolean( h261_tree, hf_h261_vbit, tvb, offset, 1, tvb_get_guint8( tvb, offset ) & 1 ); offset++; /* GOBN 2nd octet, 4 bits */ proto_tree_add_uint( h261_tree, hf_h261_gobn, tvb, offset, 1, tvb_get_guint8( tvb, offset ) >> 4 ); /* MBAP 2nd octet, 4 bits, 3rd octet 1 bit */ proto_tree_add_uint( h261_tree, hf_h261_mbap, tvb, offset, 1, ( tvb_get_guint8( tvb, offset ) & 15 ) + ( tvb_get_guint8( tvb, offset + 1 ) >> 7 ) ); offset++; /* QUANT 3rd octet, 5 bits (starting at bit 2!) */ proto_tree_add_uint( h261_tree, hf_h261_quant, tvb, offset, 1, tvb_get_guint8( tvb, offset ) & 124 ); /* HMVD 3rd octet 2 bits, 4th octet 3 bits */ proto_tree_add_uint( h261_tree, hf_h261_hmvd, tvb, offset, 2, ( ( tvb_get_guint8( tvb, offset ) & 0x03 ) << 3 ) + ( tvb_get_guint8( tvb, offset+1 ) >> 5 ) ); offset++; /* VMVD 4th octet, last 5 bits */ proto_tree_add_uint( h261_tree, hf_h261_vmvd, tvb, offset, 1, tvb_get_guint8( tvb, offset ) & 31 ); offset++; /* The rest of the packet is the H.261 stream */ proto_tree_add_item( h261_tree, hf_h261_data, tvb, offset, -1, FALSE ); } } void proto_register_h261(void) { static hf_register_info hf[] = { { &hf_h261_sbit, { "Start bit position", "h261.sbit", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_h261_ebit, { "End bit position", "h261.ebit", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_h261_ibit, { "Intra frame encoded data flag", "h261.i", FT_BOOLEAN, BASE_NONE, NULL, 0x0, "", HFILL } }, { &hf_h261_vbit, { "Motion vector flag", "h261.v", FT_BOOLEAN, BASE_NONE, NULL, 0x0, "", HFILL } }, { &hf_h261_gobn, { "GOB Number", "h261.gobn", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_h261_mbap, { "Macroblock address predictor", "h261.mbap", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_h261_quant, { "Quantizer", "h261.quant", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_h261_hmvd, { "Horizontal motion vector data", "h261.hmvd", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_h261_vmvd, { "Vertical motion vector data", "h261.vmvd", FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL } }, { &hf_h261_data, { "H.261 stream", "h261.stream", FT_BYTES, BASE_NONE, NULL, 0x0, "", HFILL } }, }; static gint *ett[] = { &ett_h261, }; proto_h261 = proto_register_protocol("ITU-T Recommendation H.261", "H.261", "h261"); proto_register_field_array(proto_h261, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); } void proto_reg_handoff_h261(void) { dissector_handle_t h261_handle; h261_handle = create_dissector_handle(dissect_h261, proto_h261); dissector_add("rtp.pt", PT_H261, h261_handle); }