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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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 existence 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 #define NEW_PROTO_TREE_API
  65
  66 #include "config.h"
  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 dissector_handle_t handle_2dparityfec = NULL;
  76
  77 static gboolean dissect_fec = FALSE;
  78
  79 static int fec_rtp_payload_type = 96;
  80 static gint ett_2dparityfec = -1;
  81
  82 static header_field_info *hfi_2dparityfec = NULL;
  83
  84 #define _2DPARITYFEC_HFI_INIT HFI_INIT(proto_2dparityfec)
  85
  86 static header_field_info hfi_2dparityfec_snbase_low _2DPARITYFEC_HFI_INIT =
  87 {  "SNBase low",
  88    "2dparityfec.snbase_low",
  89    FT_UINT16,
  90    BASE_DEC,
  91    NULL,
  92    0x0,
  93    NULL,
  94    HFILL};
  95
  96 static header_field_info hfi_2dparityfec_length_recovery _2DPARITYFEC_HFI_INIT =
  97 { "Length recovery",
  98   "2dparityfec.lr",
  99   FT_UINT16,
 100   BASE_HEX,
 101   NULL,
 102   0x0,
 103   NULL,
 104   HFILL};
 105
 106 static header_field_info hfi_2dparityfec_rfc2733_ext _2DPARITYFEC_HFI_INIT =
 107 { "RFC2733 Extension (E)",
 108   "2dparityfec.e",
 109   FT_BOOLEAN,
 110   8,
 111   NULL,
 112   0x80,
 113   NULL,
 114   HFILL};
 115
 116 static header_field_info hfi_2dparityfec_pt_recovery _2DPARITYFEC_HFI_INIT =
 117 { "Payload Type recovery",
 118   "2dparityfec.ptr",
 119   FT_UINT8,
 120   BASE_HEX,
 121   NULL,
 122   0x7f,
 123   NULL,
 124   HFILL};
 125
 126 static header_field_info hfi_2dparityfec_mask _2DPARITYFEC_HFI_INIT =
 127 { "Mask",
 128   "2dparityfec.mask",
 129   /*FT_UINT32*/FT_UINT24,
 130   BASE_HEX,
 131   NULL,
 132   /*0x00ffffff*/0x0,
 133   NULL,
 134   HFILL};
 135
 136 static header_field_info hfi_2dparityfec_ts_recovery _2DPARITYFEC_HFI_INIT =
 137 { "Timestamp recovery",
 138   "2dparityfec.tsr",
 139   FT_UINT32,
 140   BASE_HEX,
 141   NULL,
 142   0x0,
 143   NULL,
 144   HFILL};
 145
 146 static header_field_info hfi_2dparityfec_ts_pro_mpeg_ext _2DPARITYFEC_HFI_INIT =
 147 { "Pro-MPEG Extension (X)",
 148   "2dparityfec.x",
 149   FT_BOOLEAN,
 150   8,
 151   NULL,
 152   0x80,
 153   NULL,
 154   HFILL};
 155
 156 static header_field_info hfi_2dparityfec_row_flag _2DPARITYFEC_HFI_INIT =
 157 { "Row FEC (D)",
 158   "2dparityfec.d",
 159   FT_BOOLEAN,
 160   8,
 161   NULL,
 162   0x40,
 163   NULL,
 164   HFILL};
 165
 166 static const value_string fec_type_names[] = {
 167    {0, "XOR"},
 168    {1, "Hamming"},
 169    {2, "Reed-Solomon"},
 170    {0, NULL}
 171 };
 172
 173 static header_field_info hfi_2dparityfec_type _2DPARITYFEC_HFI_INIT =
 174 { "Type",
 175   "2dparityfec.type",
 176   FT_UINT8,
 177   BASE_DEC,
 178   VALS(fec_type_names),
 179   0x38,
 180   NULL,
 181   HFILL};
 182
 183 static header_field_info hfi_2dparityfec_index _2DPARITYFEC_HFI_INIT =
 184 { "Index",
 185   "2dparityfec.index",
 186   FT_UINT8,
 187   BASE_DEC,
 188   NULL,
 189   0x07,
 190   NULL,
 191   HFILL};
 192
 193 static header_field_info hfi_2dparityfec_offset _2DPARITYFEC_HFI_INIT =
 194 { "Offset",
 195   "2dparityfec.offset",
 196   FT_UINT8,
 197   BASE_DEC,
 198   NULL,
 199   0x0,
 200   NULL,
 201   HFILL};
 202
 203 static header_field_info hfi_2dparityfec_na _2DPARITYFEC_HFI_INIT =
 204 { "NA",
 205   "2dparityfec.na",
 206   FT_UINT8,
 207   BASE_DEC,
 208   NULL,
 209   0x0,
 210   NULL,
 211   HFILL};
 212
 213 static header_field_info hfi_2dparityfec_snbase_ext _2DPARITYFEC_HFI_INIT =
 214 { "SNBase ext",
 215   "2dparityfec.snbase_ext",
 216   FT_UINT8,
 217   BASE_DEC,
 218   NULL,
 219   0x0,
 220   NULL,
 221   HFILL};
 222
 223 static header_field_info hfi_2dparityfec_payload _2DPARITYFEC_HFI_INIT =
 224 { "FEC Payload",
 225   "2dparityfec.payload",
 226   FT_BYTES,
 227   BASE_NONE,
 228   NULL,
 229   0x0,
 230   NULL,
 231   HFILL};
 232
 233
 234 static void dissect_2dparityfec(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 235 {
 236    guint8   OffsetField;
 237    guint8   NAField;
 238    guint32  SNBase;
 239    guint8   D;
 240
 241    /* Extract SNBase */
 242    SNBase  = (guint32)tvb_get_guint8(tvb, 0)<<8;
 243    SNBase |= (guint32)tvb_get_guint8(tvb, 1);
 244    SNBase |= (guint32)tvb_get_guint8(tvb, 15)<<16;
 245
 246    /* Extract D */
 247    D = (tvb_get_guint8(tvb, 12)>>6) & 0x1;
 248
 249    /* Extract Offset and NA */
 250    OffsetField    = tvb_get_guint8(tvb, 13);
 251    NAField        = tvb_get_guint8(tvb, 14);
 252
 253    col_set_str(pinfo->cinfo, COL_PROTOCOL, "2dFEC");
 254
 255    /* Configure the info column */
 256    if(D)
 257    {
 258       col_add_fstr(pinfo->cinfo, COL_INFO, "Row FEC - SNBase=%u, Offset=%u, NA=%u",
 259                    SNBase, OffsetField, NAField);
 260    }
 261    else
 262    {
 263       col_add_fstr(pinfo->cinfo, COL_INFO, "Column FEC - SNBase=%u, Offset=%u, NA=%u",
 264                    SNBase, OffsetField, NAField);
 265    }
 266
 267    if(tree)
 268    {
 269       /* we are being asked for details */
 270       proto_item *ti = NULL;
 271       proto_tree *tree_2dparityfec = NULL;
 272       gint offset = 0;
 273
 274       ti = proto_tree_add_item(tree, hfi_2dparityfec, tvb, 0, -1, ENC_NA);
 275       tree_2dparityfec = proto_item_add_subtree(ti, ett_2dparityfec);
 276
 277       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_snbase_low,      tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2;
 278       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_length_recovery, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2;
 279       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_rfc2733_ext,     tvb, offset, 1, ENC_BIG_ENDIAN);
 280       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_pt_recovery,     tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 281       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_mask,            tvb, offset, 3, ENC_BIG_ENDIAN); offset += 3;
 282       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_ts_recovery,     tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4;
 283       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_ts_pro_mpeg_ext, tvb, offset, 1, ENC_BIG_ENDIAN);
 284       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_row_flag,        tvb, offset, 1, ENC_BIG_ENDIAN);
 285       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_type,            tvb, offset, 1, ENC_BIG_ENDIAN);
 286       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_index,           tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 287       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_offset,          tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 288       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_na,              tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 289       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_snbase_ext,      tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 290       proto_tree_add_item(tree_2dparityfec, &hfi_2dparityfec_payload,         tvb, offset, -1, ENC_NA);
 291    }
 292 }
 293
 294 void proto_register_2dparityfec(void)
 295 {
 296    module_t *module_2dparityfec;
 297
 298 #ifndef HAVE_HFI_SECTION_INIT
 299 /* Payload type definitions */
 300    static header_field_info *hfi[] = {
 301       &hfi_2dparityfec_snbase_low,
 302       &hfi_2dparityfec_length_recovery,
 303       &hfi_2dparityfec_rfc2733_ext,
 304       &hfi_2dparityfec_pt_recovery,
 305       &hfi_2dparityfec_mask,
 306       &hfi_2dparityfec_ts_recovery,
 307       &hfi_2dparityfec_ts_pro_mpeg_ext,
 308       &hfi_2dparityfec_row_flag,
 309       &hfi_2dparityfec_type,
 310       &hfi_2dparityfec_index,
 311       &hfi_2dparityfec_offset,
 312       &hfi_2dparityfec_na,
 313       &hfi_2dparityfec_snbase_ext,
 314       &hfi_2dparityfec_payload,
 315    };
 316 #endif
 317
 318 /* Setup protocol subtree array */
 319    static gint *ett[] = {
 320       &ett_2dparityfec,
 321    };
 322
 323    int proto_2dparityfec;
 324
 325    proto_2dparityfec = proto_register_protocol(
 326       "Pro-MPEG Code of Practice #3 release 2 FEC Protocol",   /* name */
 327       "2dparityfec",            /* short name */
 328       "2dparityfec");           /* abbrev */
 329    hfi_2dparityfec = proto_registrar_get_nth(proto_2dparityfec);
 330
 331    proto_register_fields(proto_2dparityfec, hfi, array_length(hfi));
 332    proto_register_subtree_array(ett, array_length(ett));
 333
 334    module_2dparityfec = prefs_register_protocol(proto_2dparityfec,
 335                                                 proto_reg_handoff_2dparityfec);
 336
 337    prefs_register_bool_preference(module_2dparityfec, "enable",
 338                                   "Decode Pro-MPEG FEC on RTP dynamic payload type 96",
 339                                   "Enable this option to recognise all traffic on RTP dynamic payload type 96 (0x60) "
 340                                   "as FEC data corresponding to Pro-MPEG Code of Practice #3 release 2",
 341                                   &dissect_fec);
 342
 343       handle_2dparityfec = create_dissector_handle(dissect_2dparityfec,
 344                                                    proto_2dparityfec);
 345 }
 346
 347 void proto_reg_handoff_2dparityfec(void)
 348 {
 349    if (dissect_fec) {
 350       dissector_add_uint("rtp.pt", fec_rtp_payload_type, handle_2dparityfec);
 351    } else {
 352       dissector_delete_uint("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: 8
 362  * indent-tabs-mode: nil
 363  * End:
 364  *
 365  * ex: set shiftwidth=3 tabstop=8 expandtab:
 366  * :indentSize=3:tabSize=8:noTabs=true:
 367  */