epan/dissectors/packet-2dparityfec.c

   1 /* packet-2dparityfec.c
   2  * Mark Lewis <mlewis@altera.com>
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  23  */
  24
  25 /*
  26 ** RTP Payload dissector for packets as specified in:
  27 ** Pro-MPEG Code of Practice #3 release 2
  28 **
  29 ** This protocol defines a format for FEC data embedded within RTP packets with
  30 ** a payload type of 96 (0x60). The format of the FEC packets, which reside within
  31 ** the RTP payload, is as follows...
  32 **
  33 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  34 **   |         SNBase low bits       |        Length Recovery        |
  35 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  36 **   |E| PT recovery |                    Mask                       |
  37 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  38 **   |                           TS recovery                         |
  39 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  40 **   |X|D|type |index|    Offset     |       NA      |SNBase ext bits|
  41 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  42 **   |                                                               |
  43 **   :                          FEC Payload                          :
  44 **   |                                                               |
  45 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  46 **
  47 ** For more information on this protocol see...
  48 ** http://www.pro-mpeg.org/publications/pdf/Vid-on-IP-CoP3-r2.pdf
  49 **
  50 **
  51 ** Notes:
  52 **
  53 ** This protocol always resides in RTP packets with payload type 96. However,
  54 ** type 96 is dynamic and may refer to other protocols. As Pro-MPEG FEC must
  55 ** function in the absence of a control channel, and because this data is
  56 ** likely to be transmitted within closed networks, no automatic mechanism
  57 ** exists for specifying the existance of Pro-MPEG FEC on payload type 96.
  58 ** This dissector is thus disabled by default. Dissection of this protocol
  59 ** may be enabled from the 2dparityfec panel under Preferences->Protocols.
  60 **
  61 ** Mark Lewis - 20th June 2006
  62 */
  63
  64 #ifdef HAVE_CONFIG_H
  65 # include "config.h"
  66 #endif
  67
  68 #include <epan/packet.h>
  69 #include <epan/prefs.h>
  70
  71 /* forward reference */
  72 void proto_register_2dparityfec(void);
  73 void proto_reg_handoff_2dparityfec(void);
  74
  75 static gboolean dissect_fec = FALSE;
  76
  77 static int proto_2dparityfec = -1;
  78 static int fec_rtp_payload_type = 96;
  79 static gint ett_2dparityfec = -1;
  80
  81 static int hf_2dparityfec_snbase_low      = -1;
  82 static int hf_2dparityfec_length_recovery = -1;
  83 static int hf_2dparityfec_rfc2733_ext     = -1;
  84 static int hf_2dparityfec_pt_recovery     = -1;
  85 static int hf_2dparityfec_mask            = -1;
  86 static int hf_2dparityfec_ts_recovery     = -1;
  87 static int hf_2dparityfec_ts_pro_mpeg_ext = -1;
  88 static int hf_2dparityfec_row_flag        = -1;
  89 static int hf_2dparityfec_type            = -1;
  90 static int hf_2dparityfec_index           = -1;
  91 static int hf_2dparityfec_offset          = -1;
  92 static int hf_2dparityfec_na              = -1;
  93 static int hf_2dparityfec_snbase_ext      = -1;
  94 static int hf_2dparityfec_payload         = -1;
  95
  96 static const value_string fec_type_names[] = {
  97       {0, "XOR"},
  98       {1, "Hamming"},
  99       {2, "Reed-Solomon"}};
 100
 101 static void dissect_2dparityfec(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 102 {
 103    guint8   OffsetField;
 104    guint8   NAField;
 105    guint32  SNBase;
 106    guint8   D;
 107
 108    /* Extract SNBase */
 109    SNBase  = (guint32)tvb_get_guint8(tvb, 0)<<8;
 110    SNBase |= (guint32)tvb_get_guint8(tvb, 1);
 111    SNBase |= (guint32)tvb_get_guint8(tvb, 15)<<16;
 112
 113    /* Extract D */
 114    D = (tvb_get_guint8(tvb, 12)>>6) & 0x1;
 115
 116    /* Extract Offset and NA */
 117    OffsetField    = tvb_get_guint8(tvb, 13);
 118    NAField        = tvb_get_guint8(tvb, 14);
 119
 120    if(check_col(pinfo->cinfo, COL_PROTOCOL))
 121    {
 122       col_set_str(pinfo->cinfo, COL_PROTOCOL, "2dFEC");
 123    }
 124
 125    /* Configure the info column */
 126    if(check_col(pinfo->cinfo, COL_INFO))
 127    {
 128       col_clear(pinfo->cinfo, COL_INFO);
 129
 130       if(D)
 131       {
 132          col_add_fstr(pinfo->cinfo, COL_INFO, "Row FEC - SNBase=%u, Offset=%u, NA=%u",
 133                                                 SNBase, OffsetField, NAField);
 134       }
 135       else
 136       {
 137          col_add_fstr(pinfo->cinfo, COL_INFO, "Column FEC - SNBase=%u, Offset=%u, NA=%u",
 138                                                 SNBase, OffsetField, NAField);
 139       }
 140    }
 141
 142    if(tree)
 143    {
 144       /* we are being asked for details */
 145       proto_item *ti = NULL;
 146       proto_tree *tree_2dparityfec = NULL;
 147       gint offset = 0;
 148
 149       ti = proto_tree_add_item(tree, proto_2dparityfec, tvb, 0, -1, FALSE);
 150       tree_2dparityfec = proto_item_add_subtree(ti, ett_2dparityfec);
 151
 152       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_snbase_low,      tvb, offset, 2, FALSE); offset += 2;
 153       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_length_recovery, tvb, offset, 2, FALSE); offset += 2;
 154       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_rfc2733_ext,     tvb, offset, 1, FALSE);
 155       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_pt_recovery,     tvb, offset, 1, FALSE); offset += 1;
 156       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_mask,            tvb, offset, 3, FALSE); offset += 3;
 157       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_ts_recovery,     tvb, offset, 4, FALSE); offset += 4;
 158       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_ts_pro_mpeg_ext, tvb, offset, 1, FALSE);
 159       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_row_flag,        tvb, offset, 1, FALSE);
 160       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_type,            tvb, offset, 1, FALSE);
 161       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_index,           tvb, offset, 1, FALSE); offset += 1;
 162       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_offset,          tvb, offset, 1, FALSE); offset += 1;
 163       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_na,              tvb, offset, 1, FALSE); offset += 1;
 164       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_snbase_ext,      tvb, offset, 1, FALSE); offset += 1;
 165       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_payload,         tvb, offset, -1, FALSE);
 166    }
 167 }
 168
 169 /* Payload type definitions */
 170 static hf_register_info hf[] = {
 171         {&hf_2dparityfec_snbase_low,
 172                 {  "SNBase low",
 173                         "2dparityfec.snbase_low",
 174                         FT_UINT16,
 175                         BASE_DEC,
 176                         NULL,
 177                         0x0,
 178                         "",
 179                         HFILL}   },
 180
 181         {&hf_2dparityfec_length_recovery,
 182                 {  "Length recovery",
 183                         "2dparityfec.lr",
 184                         FT_UINT16,
 185                         BASE_HEX,
 186                         NULL,
 187                         0x0,
 188                         "",
 189                         HFILL}   },
 190
 191         {&hf_2dparityfec_rfc2733_ext,
 192                 {  "RFC2733 Extension (E)",
 193                         "2dparityfec.e",
 194                         FT_BOOLEAN,
 195                         8,
 196                         NULL,
 197                         0x80,
 198                         "",
 199                         HFILL}   },
 200
 201         {&hf_2dparityfec_pt_recovery,
 202                 {  "Payload Type recovery",
 203                         "2dparityfec.ptr",
 204                         FT_UINT8,
 205                         BASE_HEX,
 206                         NULL,
 207                         0x7f,
 208                         "",
 209                         HFILL}   },
 210
 211         {&hf_2dparityfec_mask,
 212                 {  "Mask",
 213                         "2dparityfec.mask",
 214                         /*FT_UINT32*/FT_UINT24,
 215                         BASE_HEX,
 216                         NULL,
 217                         /*0x00ffffff*/0x0,
 218                         "",
 219                         HFILL}   },
 220
 221         {&hf_2dparityfec_ts_recovery,
 222                 {  "Timestamp recovery",
 223                         "2dparityfec.tsr",
 224                         FT_UINT32,
 225                         BASE_HEX,
 226                         NULL,
 227                         0x0,
 228                         "",
 229                         HFILL}   },
 230
 231         {&hf_2dparityfec_ts_pro_mpeg_ext,
 232                 {  "Pro-MPEG Extension (X)",
 233                         "2dparityfec.x",
 234                         FT_BOOLEAN,
 235                         8,
 236                         NULL,
 237                         0x80,
 238                         "",
 239                         HFILL}   },
 240
 241         {&hf_2dparityfec_row_flag,
 242                 {  "Row FEC (D)",
 243                         "2dparityfec.d",
 244                         FT_BOOLEAN,
 245                         8,
 246                         NULL,
 247                         0x40,
 248                         "",
 249                         HFILL}   },
 250
 251         {&hf_2dparityfec_type,
 252                 {  "Type",
 253                         "2dparityfec.type",
 254                         FT_UINT8,
 255                         BASE_DEC,
 256                         VALS(fec_type_names),
 257                         0x38,
 258                         "",
 259                         HFILL}   },
 260
 261         {&hf_2dparityfec_index,
 262                 {  "Index",
 263                         "2dparityfec.index",
 264                         FT_UINT8,
 265                         BASE_DEC,
 266                         NULL,
 267                         0x07,
 268                         "",
 269                         HFILL}   },
 270
 271         {&hf_2dparityfec_offset,
 272                 {  "Offset",
 273                         "2dparityfec.offset",
 274                         FT_UINT8,
 275                         BASE_DEC,
 276                         NULL,
 277                         0x0,
 278                         "",
 279                         HFILL}   },
 280
 281         {&hf_2dparityfec_na,
 282                 {  "NA",
 283                         "2dparityfec.na",
 284                         FT_UINT8,
 285                         BASE_DEC,
 286                         NULL,
 287                         0x0,
 288                         "",
 289                         HFILL}   },
 290
 291         {&hf_2dparityfec_snbase_ext,
 292                 {  "SNBase ext",
 293                         "2dparityfec.snbase_ext",
 294                         FT_UINT8,
 295                         BASE_DEC,
 296                         NULL,
 297                         0x0,
 298                         "",
 299                         HFILL}   },
 300
 301         {&hf_2dparityfec_payload,
 302                 {  "FEC Payload",
 303                         "2dparityfec.payload",
 304                         FT_BYTES,
 305                         BASE_HEX,
 306                         NULL,
 307                         0x0,
 308                         "",
 309                         HFILL}   }
 310
 311
 312 };
 313
 314 /* Setup protocol subtree array */
 315 static gint *ett[] = {
 316         &ett_2dparityfec,
 317 };
 318
 319 void proto_register_2dparityfec(void)
 320 {
 321    module_t *module_2dparityfec;
 322
 323    proto_2dparityfec = proto_register_protocol(
 324         "Pro-MPEG Code of Practice #3 release 2 FEC Protocol",   /* name */
 325         "2dparityfec",            /* short name */
 326         "2dparityfec");           /* abbrev */
 327
 328    proto_register_field_array(proto_2dparityfec, hf, array_length(hf));
 329    proto_register_subtree_array(ett, array_length(ett));
 330
 331    module_2dparityfec = prefs_register_protocol(proto_2dparityfec,
 332                                                 proto_reg_handoff_2dparityfec);
 333
 334    prefs_register_bool_preference(module_2dparityfec, "enable",
 335       "Decode Pro-MPEG FEC on RTP dynamic payload type 96",
 336       "Enable this option to recognise all traffic on RTP dynamic payload type 96 (0x60) "
 337       "as FEC data corresponding to Pro-MPEG Code of Practice #3 release 2",
 338       &dissect_fec);
 339
 340 }
 341
 342 void proto_reg_handoff_2dparityfec(void)
 343 {
 344       static dissector_handle_t handle_2dparityfec = NULL;
 345
 346       if (!handle_2dparityfec) {
 347         handle_2dparityfec = create_dissector_handle(dissect_2dparityfec,
 348                                                         proto_2dparityfec);
 349       }
 350
 351       if (dissect_fec) {
 352         dissector_add("rtp.pt", fec_rtp_payload_type, handle_2dparityfec);
 353       } else {
 354         dissector_delete("rtp.pt", fec_rtp_payload_type, handle_2dparityfec);
 355       }
 356 }