epan/dissectors/packet-2dparityfec.c

   1 /* packet-2dparityfec.c
   2  * Mark Lewis <mlewis@altera.com>
   3  *
   4  * Wireshark - Network traffic analyzer
   5  * By Gerald Combs <gerald@wireshark.org>
   6  * Copyright 1998 Gerald Combs
   7  *
   8  * SPDX-License-Identifier: GPL-2.0-or-later
   9  */
  10
  11 /*
  12 ** RTP Payload dissector for packets as specified in:
  13 ** Pro-MPEG Code of Practice #3 release 2
  14 **
  15 ** This protocol defines a format for FEC data embedded within RTP packets with
  16 ** a payload type of 96 (0x60). The format of the FEC packets, which reside within
  17 ** the RTP payload, is as follows...
  18 **
  19 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  20 **   |         SNBase low bits       |        Length Recovery        |
  21 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  22 **   |E| PT recovery |                    Mask                       |
  23 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  24 **   |                           TS recovery                         |
  25 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  26 **   |X|D|type |index|    Offset     |       NA      |SNBase ext bits|
  27 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  28 **   |                                                               |
  29 **   :                          FEC Payload                          :
  30 **   |                                                               |
  31 **   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  32 **
  33 ** For more information on this protocol see...
  34 ** http://www.pro-mpeg.org/publications/pdf/Vid-on-IP-CoP3-r2.pdf
  35 **
  36 **
  37 ** Notes:
  38 **
  39 ** This protocol always resides in RTP packets with payload type 96. However,
  40 ** type 96 is dynamic and may refer to other protocols. As Pro-MPEG FEC must
  41 ** function in the absence of a control channel, and because this data is
  42 ** likely to be transmitted within closed networks, no automatic mechanism
  43 ** exists for specifying the existence of Pro-MPEG FEC on payload type 96.
  44 ** This dissector is thus disabled by default. Dissection of this protocol
  45 ** may be enabled from the 2dparityfec panel under Preferences->Protocols.
  46 **
  47 ** Mark Lewis - 20th June 2006
  48 */
  49 #include "config.h"
  50
  51 #include <epan/packet.h>
  52 #include <epan/prefs.h>
  53 #include <wsutil/array.h>
  54
  55 /* forward reference */
  56 void proto_register_2dparityfec(void);
  57 void proto_reg_handoff_2dparityfec(void);
  58
  59 static dissector_handle_t handle_2dparityfec;
  60
  61 static bool dissect_fec;
  62
  63 static int fec_rtp_payload_type = 96;
  64
  65 static int proto_2dparityfec;
  66
  67 static int hf_2dparityfec_index;
  68 static int hf_2dparityfec_length_recovery;
  69 static int hf_2dparityfec_mask;
  70 static int hf_2dparityfec_na;
  71 static int hf_2dparityfec_offset;
  72 static int hf_2dparityfec_payload;
  73 static int hf_2dparityfec_pt_recovery;
  74 static int hf_2dparityfec_rfc2733_ext;
  75 static int hf_2dparityfec_row_flag;
  76 static int hf_2dparityfec_snbase_ext;
  77 static int hf_2dparityfec_snbase_low;
  78 static int hf_2dparityfec_ts_pro_mpeg_ext;
  79 static int hf_2dparityfec_ts_recovery;
  80 static int hf_2dparityfec_type;
  81
  82 static int ett_2dparityfec;
  83
  84 static const value_string fec_type_names[] = {
  85    {0, "XOR"},
  86    {1, "Hamming"},
  87    {2, "Reed-Solomon"},
  88    {0, NULL}
  89 };
  90
  91 static int dissect_2dparityfec(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  92 {
  93    uint8_t  OffsetField;
  94    uint8_t  NAField;
  95    uint32_t SNBase;
  96    uint8_t  D;
  97
  98    /* Extract SNBase */
  99    SNBase  = (uint32_t)tvb_get_uint8(tvb, 0)<<8;
 100    SNBase |= (uint32_t)tvb_get_uint8(tvb, 1);
 101    SNBase |= (uint32_t)tvb_get_uint8(tvb, 15)<<16;
 102
 103    /* Extract D */
 104    D = (tvb_get_uint8(tvb, 12)>>6) & 0x1;
 105
 106    /* Extract Offset and NA */
 107    OffsetField    = tvb_get_uint8(tvb, 13);
 108    NAField        = tvb_get_uint8(tvb, 14);
 109
 110    col_set_str(pinfo->cinfo, COL_PROTOCOL, "2dFEC");
 111
 112    /* Configure the info column */
 113    if(D)
 114    {
 115       col_add_fstr(pinfo->cinfo, COL_INFO, "Row FEC - SNBase=%u, Offset=%u, NA=%u",
 116                    SNBase, OffsetField, NAField);
 117    }
 118    else
 119    {
 120       col_add_fstr(pinfo->cinfo, COL_INFO, "Column FEC - SNBase=%u, Offset=%u, NA=%u",
 121                    SNBase, OffsetField, NAField);
 122    }
 123
 124    if(tree)
 125    {
 126       /* we are being asked for details */
 127       proto_item *ti;
 128       proto_tree *tree_2dparityfec;
 129       int offset = 0;
 130
 131       ti = proto_tree_add_item(tree, proto_2dparityfec, tvb, 0, -1, ENC_NA);
 132       tree_2dparityfec = proto_item_add_subtree(ti, ett_2dparityfec);
 133
 134       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_snbase_low,      tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2;
 135       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_length_recovery, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2;
 136       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_rfc2733_ext,     tvb, offset, 1, ENC_BIG_ENDIAN);
 137       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_pt_recovery,     tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 138       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_mask,            tvb, offset, 3, ENC_BIG_ENDIAN); offset += 3;
 139       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_ts_recovery,     tvb, offset, 4, ENC_BIG_ENDIAN); offset += 4;
 140       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_ts_pro_mpeg_ext, tvb, offset, 1, ENC_BIG_ENDIAN);
 141       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_row_flag,        tvb, offset, 1, ENC_BIG_ENDIAN);
 142       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_type,            tvb, offset, 1, ENC_BIG_ENDIAN);
 143       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_index,           tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 144       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_offset,          tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 145       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_na,              tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 146       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_snbase_ext,      tvb, offset, 1, ENC_BIG_ENDIAN); offset += 1;
 147       proto_tree_add_item(tree_2dparityfec, hf_2dparityfec_payload,         tvb, offset, -1, ENC_NA);
 148    }
 149
 150    return tvb_captured_length(tvb);
 151 }
 152
 153 void proto_register_2dparityfec(void)
 154 {
 155    static hf_register_info hf[] = {
 156       { &hf_2dparityfec_snbase_low,
 157          { "SNBase low", "2dparityfec.snbase_low",
 158            FT_UINT16, BASE_DEC, NULL, 0x0,
 159            NULL, HFILL }
 160       },
 161       { &hf_2dparityfec_length_recovery,
 162          { "Length recovery", "2dparityfec.lr",
 163            FT_UINT16, BASE_HEX, NULL, 0x0,
 164            NULL, HFILL }
 165       },
 166       { &hf_2dparityfec_rfc2733_ext,
 167          { "RFC2733 Extension (E)", "2dparityfec.e",
 168            FT_BOOLEAN, 8, NULL, 0x80,
 169            NULL, HFILL }
 170       },
 171       { &hf_2dparityfec_pt_recovery,
 172          { "Payload Type recovery", "2dparityfec.ptr",
 173            FT_UINT8, BASE_HEX, NULL, 0x7f,
 174            NULL, HFILL }
 175       },
 176       { &hf_2dparityfec_mask,
 177          { "Mask", "2dparityfec.mask",
 178            /*FT_UINT32*/FT_UINT24, BASE_HEX, NULL, /*0x00ffffff*/0x0,
 179            NULL, HFILL }
 180       },
 181       { &hf_2dparityfec_ts_recovery,
 182          { "Timestamp recovery", "2dparityfec.tsr",
 183            FT_UINT32, BASE_HEX, NULL, 0x0,
 184            NULL, HFILL }
 185       },
 186       { &hf_2dparityfec_ts_pro_mpeg_ext,
 187          { "Pro-MPEG Extension (X)", "2dparityfec.x",
 188            FT_BOOLEAN, 8, NULL, 0x80,
 189            NULL, HFILL }
 190       },
 191       { &hf_2dparityfec_row_flag,
 192          { "Row FEC (D)", "2dparityfec.d",
 193            FT_BOOLEAN, 8, NULL, 0x40,
 194            NULL, HFILL }
 195       },
 196       { &hf_2dparityfec_type,
 197          { "Type", "2dparityfec.type",
 198            FT_UINT8, BASE_DEC, VALS(fec_type_names), 0x38,
 199            NULL, HFILL }
 200       },
 201       { &hf_2dparityfec_index,
 202          { "Index", "2dparityfec.index",
 203            FT_UINT8, BASE_DEC, NULL, 0x07,
 204            NULL, HFILL }
 205       },
 206       { &hf_2dparityfec_offset,
 207          { "Offset", "2dparityfec.offset",
 208            FT_UINT8, BASE_DEC, NULL, 0x0,
 209            NULL, HFILL }
 210       },
 211       { &hf_2dparityfec_na,
 212          { "NA", "2dparityfec.na",
 213            FT_UINT8, BASE_DEC, NULL, 0x0,
 214            NULL, HFILL }
 215       },
 216       { &hf_2dparityfec_snbase_ext,
 217          { "SNBase ext", "2dparityfec.snbase_ext",
 218            FT_UINT8, BASE_DEC, NULL, 0x0,
 219            NULL, HFILL }
 220       },
 221       { &hf_2dparityfec_payload,
 222          { "FEC Payload", "2dparityfec.payload",
 223            FT_BYTES, BASE_NONE, NULL, 0x0,
 224            NULL, HFILL }
 225       },
 226    };
 227
 228 /* Setup protocol subtree array */
 229    static int *ett[] = {
 230       &ett_2dparityfec,
 231    };
 232
 233    module_t *module_2dparityfec;
 234
 235    proto_2dparityfec = proto_register_protocol("Pro-MPEG Code of Practice #3 release 2 FEC Protocol", "2dparityfec", "2dparityfec");
 236
 237    proto_register_field_array(proto_2dparityfec, hf, array_length(hf));
 238    proto_register_subtree_array(ett, array_length(ett));
 239
 240    module_2dparityfec = prefs_register_protocol(proto_2dparityfec,
 241                                                 proto_reg_handoff_2dparityfec);
 242
 243    prefs_register_bool_preference(module_2dparityfec, "enable",
 244                                   "Decode Pro-MPEG FEC on RTP dynamic payload type 96",
 245                                   "Enable this option to recognise all traffic on RTP dynamic payload type 96 (0x60) "
 246                                   "as FEC data corresponding to Pro-MPEG Code of Practice #3 release 2",
 247                                   &dissect_fec);
 248
 249       handle_2dparityfec = register_dissector("2dparityfec", dissect_2dparityfec,
 250                                                    proto_2dparityfec);
 251 }
 252
 253 void proto_reg_handoff_2dparityfec(void)
 254 {
 255    if (dissect_fec) {
 256       dissector_add_uint("rtp.pt", fec_rtp_payload_type, handle_2dparityfec);
 257    } else {
 258       dissector_delete_uint("rtp.pt", fec_rtp_payload_type, handle_2dparityfec);
 259    }
 260 }
 261
 262 /*
 263  * Editor modelines
 264  *
 265  * Local Variables:
 266  * c-basic-offset: 3
 267  * tab-width: 8
 268  * indent-tabs-mode: nil
 269  * End:
 270  *
 271  * ex: set shiftwidth=3 tabstop=8 expandtab:
 272  * :indentSize=3:tabSize=8:noTabs=true:
 273  */