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_reg_handoff_2dparityfec(void);
  73
  74 static gboolean dissect_fec = FALSE;
  75
  76 static int proto_2dparityfec = -1;
  77 static int fec_rtp_payload_type = 96;
  78 static gint ett_2dparityfec = -1;
  79
  80 static int hf_2dparityfec_snbase_low      = -1;
  81 static int hf_2dparityfec_length_recovery = -1;
  82 static int hf_2dparityfec_rfc2733_ext     = -1;
  83 static int hf_2dparityfec_pt_recovery     = -1;
  84 static int hf_2dparityfec_mask            = -1;
  85 static int hf_2dparityfec_ts_recovery     = -1;
  86 static int hf_2dparityfec_ts_pro_mpeg_ext = -1;
  87 static int hf_2dparityfec_row_flag        = -1;
  88 static int hf_2dparityfec_type            = -1;
  89 static int hf_2dparityfec_index           = -1;
  90 static int hf_2dparityfec_offset          = -1;
  91 static int hf_2dparityfec_na              = -1;
  92 static int hf_2dparityfec_snbase_ext      = -1;
  93 static int hf_2dparityfec_payload         = -1;
  94
  95 static const value_string fec_type_names[] = {
  96    {0, "XOR"},
  97    {1, "Hamming"},
  98    {2, "Reed-Solomon"},
  99    {0, NULL}
 100 };
 101
 102 static void dissect_2dparityfec(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 103 {
 104    guint8   OffsetField;
 105    guint8   NAField;
 106    guint32  SNBase;
 107    guint8   D;
 108
 109    /* Extract SNBase */
 110    SNBase  = (guint32)tvb_get_guint8(tvb, 0)<<8;
 111    SNBase |= (guint32)tvb_get_guint8(tvb, 1);
 112    SNBase |= (guint32)tvb_get_guint8(tvb, 15)<<16;
 113
 114    /* Extract D */
 115    D = (tvb_get_guint8(tvb, 12)>>6) & 0x1;
 116
 117    /* Extract Offset and NA */
 118    OffsetField    = tvb_get_guint8(tvb, 13);
 119    NAField        = tvb_get_guint8(tvb, 14);
 120
 121    col_set_str(pinfo->cinfo, COL_PROTOCOL, "2dFEC");
 122
 123    /* Configure the info column */
 124    if(check_col(pinfo->cinfo, COL_INFO))
 125    {
 126       col_clear(pinfo->cinfo, COL_INFO);
 127
 128       if(D)
 129       {
 130          col_add_fstr(pinfo->cinfo, COL_INFO, "Row FEC - SNBase=%u, Offset=%u, NA=%u",
 131                                                 SNBase, OffsetField, NAField);
 132       }
 133       else
 134       {
 135          col_add_fstr(pinfo->cinfo, COL_INFO, "Column FEC - SNBase=%u, Offset=%u, NA=%u",
 136                                                 SNBase, OffsetField, NAField);
 137       }
 138    }
 139
 140    if(tree)
 141    {
 142       /* we are being asked for details */
 143       proto_item *ti = NULL;
 144       proto_tree *tree_2dparityfec = NULL;
 145       gint offset = 0;
 146
 147       ti = proto_tree_add_item(tree, proto_2dparityfec, tvb, 0, -1, FALSE);
 148       tree_2dparityfec = proto_item_add_subtree(ti, ett_2dparityfec);
 149
 150       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_snbase_low,      tvb, offset, 2, FALSE); offset += 2;
 151       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_length_recovery, tvb, offset, 2, FALSE); offset += 2;
 152       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_rfc2733_ext,     tvb, offset, 1, FALSE);
 153       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_pt_recovery,     tvb, offset, 1, FALSE); offset += 1;
 154       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_mask,            tvb, offset, 3, FALSE); offset += 3;
 155       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_ts_recovery,     tvb, offset, 4, FALSE); offset += 4;
 156       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_ts_pro_mpeg_ext, tvb, offset, 1, FALSE);
 157       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_row_flag,        tvb, offset, 1, FALSE);
 158       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_type,            tvb, offset, 1, FALSE);
 159       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_index,           tvb, offset, 1, FALSE); offset += 1;
 160       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_offset,          tvb, offset, 1, FALSE); offset += 1;
 161       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_na,              tvb, offset, 1, FALSE); offset += 1;
 162       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_snbase_ext,      tvb, offset, 1, FALSE); offset += 1;
 163       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_payload,         tvb, offset, -1, FALSE);
 164    }
 165 }
 166
 167 void proto_register_2dparityfec(void)
 168 {
 169    module_t *module_2dparityfec;
 170
 171 /* Payload type definitions */
 172 static hf_register_info hf[] = {
 173    {&hf_2dparityfec_snbase_low,
 174       {   "SNBase low",
 175          "2dparityfec.snbase_low",
 176          FT_UINT16,
 177          BASE_DEC,
 178          NULL,
 179          0x0,
 180          NULL,
 181          HFILL}   },
 182
 183    {&hf_2dparityfec_length_recovery,
 184       {  "Length recovery",
 185          "2dparityfec.lr",
 186          FT_UINT16,
 187          BASE_HEX,
 188          NULL,
 189          0x0,
 190          NULL,
 191          HFILL}   },
 192
 193    {&hf_2dparityfec_rfc2733_ext,
 194       {  "RFC2733 Extension (E)",
 195          "2dparityfec.e",
 196          FT_BOOLEAN,
 197          8,
 198          NULL,
 199          0x80,
 200          NULL,
 201          HFILL}   },
 202
 203    {&hf_2dparityfec_pt_recovery,
 204       {  "Payload Type recovery",
 205          "2dparityfec.ptr",
 206          FT_UINT8,
 207          BASE_HEX,
 208          NULL,
 209          0x7f,
 210          NULL,
 211          HFILL}   },
 212
 213    {&hf_2dparityfec_mask,
 214       {  "Mask",
 215          "2dparityfec.mask",
 216          /*FT_UINT32*/FT_UINT24,
 217          BASE_HEX,
 218          NULL,
 219          /*0x00ffffff*/0x0,
 220          NULL,
 221          HFILL}   },
 222
 223    {&hf_2dparityfec_ts_recovery,
 224       {  "Timestamp recovery",
 225          "2dparityfec.tsr",
 226          FT_UINT32,
 227          BASE_HEX,
 228          NULL,
 229          0x0,
 230          NULL,
 231          HFILL}   },
 232
 233    {&hf_2dparityfec_ts_pro_mpeg_ext,
 234       {  "Pro-MPEG Extension (X)",
 235          "2dparityfec.x",
 236          FT_BOOLEAN,
 237          8,
 238          NULL,
 239          0x80,
 240          NULL,
 241          HFILL}   },
 242
 243    {&hf_2dparityfec_row_flag,
 244       {  "Row FEC (D)",
 245          "2dparityfec.d",
 246          FT_BOOLEAN,
 247          8,
 248          NULL,
 249          0x40,
 250          NULL,
 251          HFILL}   },
 252
 253    {&hf_2dparityfec_type,
 254       {  "Type",
 255          "2dparityfec.type",
 256          FT_UINT8,
 257          BASE_DEC,
 258          VALS(fec_type_names),
 259          0x38,
 260          NULL,
 261          HFILL}   },
 262
 263    {&hf_2dparityfec_index,
 264       {  "Index",
 265          "2dparityfec.index",
 266          FT_UINT8,
 267          BASE_DEC,
 268          NULL,
 269          0x07,
 270          NULL,
 271          HFILL}   },
 272
 273    {&hf_2dparityfec_offset,
 274       {  "Offset",
 275          "2dparityfec.offset",
 276          FT_UINT8,
 277          BASE_DEC,
 278          NULL,
 279          0x0,
 280          NULL,
 281          HFILL}   },
 282
 283    {&hf_2dparityfec_na,
 284       {  "NA",
 285          "2dparityfec.na",
 286          FT_UINT8,
 287          BASE_DEC,
 288          NULL,
 289          0x0,
 290          NULL,
 291          HFILL}   },
 292
 293    {&hf_2dparityfec_snbase_ext,
 294       {  "SNBase ext",
 295          "2dparityfec.snbase_ext",
 296          FT_UINT8,
 297          BASE_DEC,
 298          NULL,
 299          0x0,
 300          NULL,
 301          HFILL}   },
 302
 303    {&hf_2dparityfec_payload,
 304       {  "FEC Payload",
 305          "2dparityfec.payload",
 306          FT_BYTES,
 307          BASE_NONE,
 308          NULL,
 309          0x0,
 310          NULL,
 311          HFILL}   }
 312
 313
 314 };
 315
 316 /* Setup protocol subtree array */
 317 static gint *ett[] = {
 318    &ett_2dparityfec,
 319 };
 320
 321    proto_2dparityfec = proto_register_protocol(
 322       "Pro-MPEG Code of Practice #3 release 2 FEC Protocol",   /* name */
 323       "2dparityfec",            /* short name */
 324       "2dparityfec");           /* abbrev */
 325
 326    proto_register_field_array(proto_2dparityfec, hf, array_length(hf));
 327    proto_register_subtree_array(ett, array_length(ett));
 328
 329    module_2dparityfec = prefs_register_protocol(proto_2dparityfec,
 330                                                 proto_reg_handoff_2dparityfec);
 331
 332    prefs_register_bool_preference(module_2dparityfec, "enable",
 333         "Decode Pro-MPEG FEC on RTP dynamic payload type 96",
 334         "Enable this option to recognise all traffic on RTP dynamic payload type 96 (0x60) "
 335         "as FEC data corresponding to Pro-MPEG Code of Practice #3 release 2",
 336         &dissect_fec);
 337
 338 }
 339
 340 void proto_reg_handoff_2dparityfec(void)
 341 {
 342    static dissector_handle_t handle_2dparityfec = NULL;
 343
 344    if (!handle_2dparityfec) {
 345       handle_2dparityfec = create_dissector_handle(dissect_2dparityfec,
 346                                                    proto_2dparityfec);
 347    }
 348
 349    if (dissect_fec) {
 350       dissector_add("rtp.pt", fec_rtp_payload_type, handle_2dparityfec);
 351    } else {
 352       dissector_delete("rtp.pt", fec_rtp_payload_type, handle_2dparityfec);
 353    }
 354 }
 355
 356 /*
 357  * Editor modelines
 358  *
 359  * Local Variables:
 360  * c-basic-offset: 3
 361  * tab-width: 3
 362  * indent-tabs-mode: nil
 363  * End:
 364  *
 365  * ex: set shiftwidth=3 tabstop=3 expandtab
 366  * :indentSize=3:tabSize=3:noTabs=true:
 367  */