epan/dissectors/packet-rmt-fec.c

   1 /* packet-rmt-fec.c
   2  * Reliable Multicast Transport (RMT)
   3  * FEC Building Block dissector
   4  * Copyright 2005, Stefano Pettini <spettini@users.sourceforge.net>
   5  *
   6  * Forward Error Correction (ALC):
   7  * -------------------------------
   8  *
   9  * The goal of the FEC building block is to describe functionality
  10  * directly related to FEC codes that is common to all reliable content
  11  * delivery IP multicast protocols, and to leave out any additional
  12  * functionality that is specific to particular protocols.
  13  *
  14  * References:
  15  *     RFC 3452, Forward Error Correction Building Block
  16  *     RFC 3695, Compact Forward Error Correction (FEC) Schemes
  17  *     Simple XOR, Reed-Solomon, and Parity Check Matrix-based FEC Schemes draft-peltotalo-rmt-bb-fec-supp-xor-pcm-rs-00
  18  *     IANA RMT FEC parameters (http://www.iana.org/assignments/rmt-fec-parameters)
  19  *
  20  * Wireshark - Network traffic analyzer
  21  * By Gerald Combs <gerald@wireshark.org>
  22  * Copyright 1998 Gerald Combs
  23  *
  24  * SPDX-License-Identifier: GPL-2.0-or-later
  25  */
  26
  27 #include "config.h"
  28
  29 #include <epan/packet.h>
  30 #include <epan/expert.h>
  31 #include <epan/proto_data.h>
  32 #include "packet-rmt-common.h"
  33
  34 void proto_register_rmt_fec(void);
  35
  36 static int proto_rmt_fec;
  37
  38 static int hf_encoding_id;
  39 static int hf_instance_id;
  40 static int hf_sbn;
  41 static int hf_sbn_with_mask;
  42 static int hf_sbl;
  43 static int hf_esi;
  44 static int hf_esi_with_mask;
  45 static int hf_fti_transfer_length;
  46 static int hf_fti_encoding_symbol_length;
  47 static int hf_fti_max_source_block_length;
  48 static int hf_fti_max_number_encoding_symbols;
  49 static int hf_fti_num_blocks;
  50 static int hf_fti_num_subblocks;
  51 static int hf_fti_alignment;
  52
  53 static int ett_main;
  54
  55 static expert_field ei_fec_encoding_id;
  56
  57 typedef struct fec_packet_data
  58 {
  59     uint8_t instance_id;
  60
  61 } fec_packet_data_t;
  62
  63
  64 /* String tables */
  65 const value_string string_fec_encoding_id[] =
  66 {
  67     {   0, "Compact No-Code" },
  68     {   1, "Raptor" },
  69     {   2, "Reed-Solomon Codes over GF(2^^m)" },
  70     {   3, "LDPC Staircase Codes" },
  71     {   4, "LDPC Triangle Codes" },
  72     {   5, "Reed-Solomon Codes over GF(2^^8)" },
  73     {   6, "RaptorQ Code" },
  74     /* 7-127 Unassigned  */
  75     { 128, "Small Block, Large Block and Expandable FEC Codes" },
  76     { 129, "Small Block Systematic FEC Codes" },
  77     { 130, "Compact FEC Codes" },
  78     /* 131-255 Unassigned  */
  79     { 0, NULL }
  80 };
  81
  82 /* Dissection */
  83 /* ---------- */
  84
  85 /* Decode an EXT_FTI extension and fill FEC array */
  86 void fec_decode_ext_fti(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, uint8_t encoding_id)
  87 {
  88     uint64_t           transfer_length;
  89     fec_packet_data_t *fec_data;
  90     uint8_t            instance_id = 0;
  91     proto_item        *ti;
  92
  93     if (encoding_id == 6){
  94         /* Raptor Q uses 40-bit transfer length */
  95         transfer_length = tvb_get_ntoh40(tvb, offset+2);
  96     }
  97     else {
  98         /* Decode 48-bit length field */
  99         transfer_length = tvb_get_ntoh48(tvb, offset+2);
 100     }
 101
 102     if (encoding_id >= 128)
 103     {
 104         instance_id = (uint8_t) tvb_get_ntohs(tvb, offset+8);
 105
 106         /* Decode FEC Instance ID */
 107         fec_data = wmem_new0(wmem_file_scope(), fec_packet_data_t);
 108         fec_data->instance_id = instance_id;
 109
 110         p_add_proto_data(wmem_file_scope(), pinfo, proto_rmt_fec, 0, fec_data);
 111     }
 112
 113     if (encoding_id == 6){
 114         /* Raptor Q uses 40-bit transfer length */
 115         proto_tree_add_uint64(tree, hf_fti_transfer_length, tvb, offset+2, 5, transfer_length);
 116     }
 117     else {
 118         proto_tree_add_uint64(tree, hf_fti_transfer_length, tvb, offset+2, 6, transfer_length);
 119         ti = proto_tree_add_item(tree, hf_instance_id, tvb,  offset+8, 2, ENC_BIG_ENDIAN);
 120         if ((encoding_id < 128) && (encoding_id != 0)) {
 121             expert_add_info(pinfo, ti, &ei_fec_encoding_id);
 122         }
 123     }
 124
 125     switch (encoding_id)
 126     {
 127     case 1:
 128         proto_tree_add_item(tree, hf_fti_encoding_symbol_length,      tvb, offset+10, 2, ENC_BIG_ENDIAN);
 129         proto_tree_add_item(tree, hf_fti_num_blocks,                  tvb, offset+12, 2, ENC_BIG_ENDIAN);
 130         proto_tree_add_item(tree, hf_fti_num_subblocks,               tvb, offset+14, 1, ENC_BIG_ENDIAN);
 131         proto_tree_add_item(tree, hf_fti_alignment,                   tvb, offset+15, 1, ENC_BIG_ENDIAN);
 132         break;
 133
 134     case 6:
 135         proto_tree_add_item(tree, hf_fti_encoding_symbol_length,      tvb, offset+8,  2, ENC_BIG_ENDIAN);
 136         proto_tree_add_item(tree, hf_fti_num_blocks,                  tvb, offset+10, 1, ENC_BIG_ENDIAN);
 137         proto_tree_add_item(tree, hf_fti_num_subblocks,               tvb, offset+11, 2, ENC_BIG_ENDIAN);
 138         proto_tree_add_item(tree, hf_fti_alignment,                   tvb, offset+13, 1, ENC_BIG_ENDIAN);
 139         break;
 140
 141     case 0:
 142     case 2:
 143     case 128:
 144     case 130:
 145         proto_tree_add_item(tree, hf_fti_encoding_symbol_length,      tvb, offset+10, 2, ENC_BIG_ENDIAN);
 146         proto_tree_add_item(tree, hf_fti_max_source_block_length,     tvb, offset+12, 4, ENC_BIG_ENDIAN);
 147         break;
 148
 149     case 129:
 150         proto_tree_add_item(tree, hf_fti_encoding_symbol_length,      tvb, offset+10, 2, ENC_BIG_ENDIAN);
 151         proto_tree_add_item(tree, hf_fti_max_source_block_length,     tvb, offset+12, 2, ENC_BIG_ENDIAN);
 152         proto_tree_add_item(tree, hf_fti_max_number_encoding_symbols, tvb, offset+14, 2, ENC_BIG_ENDIAN);
 153         break;
 154
 155     case 132:
 156         proto_tree_add_item(tree, hf_fti_encoding_symbol_length,      tvb, offset+10, 2, ENC_BIG_ENDIAN);
 157         proto_tree_add_item(tree, hf_fti_max_source_block_length,     tvb, offset+12, 4, ENC_BIG_ENDIAN);
 158         proto_tree_add_item(tree, hf_fti_max_number_encoding_symbols, tvb, offset+16, 4, ENC_BIG_ENDIAN);
 159         break;
 160     }
 161 }
 162
 163 /* Dissect a FEC header:
 164  * fec - ptr to the logical FEC packet representation to fill
 165  * hf - ptr to header fields array
 166  * ett - ptr to ett array
 167  * prefs - ptr to FEC prefs array
 168  * tvb - buffer
 169  * pinfo - packet info
 170  * tree - tree where to add FEC header subtree
 171  * offset - ptr to offset to use and update
 172  */
 173 static int
 174 dissect_fec(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
 175 {
 176     proto_item          *ti;
 177     proto_tree          *fec_tree;
 178     unsigned             offset      = 0;
 179     fec_data_exchange_t *fec         = (fec_data_exchange_t*)data;
 180     uint8_t              encoding_id = 0;
 181     fec_packet_data_t   *packet_data = (fec_packet_data_t*)p_get_proto_data(wmem_file_scope(), pinfo, proto_rmt_fec, 0);
 182
 183     if (fec != NULL)
 184     {
 185         encoding_id = fec->encoding_id;
 186     }
 187
 188     /* Create the FEC subtree */
 189     ti = proto_tree_add_item(tree, proto_rmt_fec, tvb, offset, -1, ENC_NA);
 190     fec_tree = proto_item_add_subtree(ti, ett_main);
 191
 192     proto_tree_add_uint(fec_tree, hf_encoding_id, tvb, offset, 0, encoding_id);
 193
 194     if (encoding_id >= 128 && (packet_data != NULL))
 195         proto_tree_add_uint(fec_tree, hf_instance_id, tvb, offset, 0, packet_data->instance_id);
 196
 197     switch (encoding_id)
 198     {
 199     case 0:
 200     case 1:
 201     case 130:
 202         proto_tree_add_item(fec_tree, hf_sbn, tvb, offset,   2, ENC_BIG_ENDIAN);
 203         proto_tree_add_item(fec_tree, hf_esi, tvb, offset+2, 2, ENC_BIG_ENDIAN);
 204
 205         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohs(tvb, offset));
 206         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohs(tvb, offset+2));
 207
 208         offset += 4;
 209         break;
 210
 211     case 2:
 212     case 128:
 213     case 132:
 214         proto_tree_add_item(fec_tree, hf_sbn, tvb, offset,   4, ENC_BIG_ENDIAN);
 215         proto_tree_add_item(fec_tree, hf_esi, tvb, offset+4, 4, ENC_BIG_ENDIAN);
 216
 217         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohl(tvb, offset));
 218         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohl(tvb, offset+4));
 219
 220         offset += 8;
 221         break;
 222
 223     case 3:
 224     case 4:
 225         proto_tree_add_item(fec_tree, hf_sbn_with_mask, tvb, offset, 4, ENC_BIG_ENDIAN);
 226         proto_tree_add_item(fec_tree, hf_esi_with_mask, tvb, offset, 4, ENC_BIG_ENDIAN);
 227
 228         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohl(tvb, offset) >> 20);
 229         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohl(tvb, offset) & 0xfffff);
 230
 231         offset += 4;
 232         break;
 233
 234     case 6:
 235         proto_tree_add_item(fec_tree, hf_sbn, tvb, offset,   1, ENC_BIG_ENDIAN);
 236         proto_tree_add_item(fec_tree, hf_esi, tvb, offset+1, 3, ENC_BIG_ENDIAN);
 237
 238         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_uint8(tvb, offset));
 239         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntoh24(tvb, offset+1));
 240
 241         offset += 4;
 242         break;
 243
 244     case 129:
 245         proto_tree_add_item(fec_tree, hf_sbn, tvb, offset,   4, ENC_BIG_ENDIAN);
 246         proto_tree_add_item(fec_tree, hf_sbl, tvb, offset+4, 2, ENC_BIG_ENDIAN);
 247         proto_tree_add_item(fec_tree, hf_esi, tvb, offset+6, 2, ENC_BIG_ENDIAN);
 248
 249         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohl(tvb, offset));
 250         col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohs(tvb, offset+6));
 251
 252         offset += 8;
 253         break;
 254     }
 255
 256     return offset;
 257 }
 258
 259 void proto_register_rmt_fec(void)
 260 {
 261     static hf_register_info hf[] = {
 262         { &hf_encoding_id,
 263           { "FEC Encoding ID", "rmt-fec.encoding_id",
 264             FT_UINT8, BASE_DEC, VALS(string_fec_encoding_id), 0x0,
 265             NULL, HFILL }
 266         },
 267         { &hf_instance_id,
 268           { "FEC Instance ID", "rmt-fec.instance_id",
 269             FT_UINT16, BASE_DEC, NULL, 0x0,
 270             NULL, HFILL }
 271         },
 272         { &hf_sbn,
 273           { "Source Block Number", "rmt-fec.sbn",
 274             FT_UINT32, BASE_DEC, NULL, 0x0,
 275             NULL, HFILL }
 276         },
 277         { &hf_sbn_with_mask,
 278           { "Source Block Number", "rmt-fec.sbn",
 279             FT_UINT32, BASE_DEC, NULL, 0xFFF00000,
 280             NULL, HFILL }
 281         },
 282         { &hf_sbl,
 283           { "Source Block Length", "rmt-fec.sbl",
 284             FT_UINT32, BASE_DEC, NULL, 0x0,
 285             NULL, HFILL }
 286         },
 287         { &hf_esi,
 288           { "Encoding Symbol ID", "rmt-fec.esi",
 289             FT_UINT32, BASE_HEX, NULL, 0x0,
 290             NULL, HFILL }
 291         },
 292         { &hf_esi_with_mask,
 293           { "Encoding Symbol ID", "rmt-fec.esi",
 294             FT_UINT32, BASE_HEX, NULL, 0x000FFFFF,
 295             NULL, HFILL }
 296         },
 297         { &hf_fti_transfer_length,
 298           { "Transfer Length", "rmt-fec.fti.transfer_length",
 299             FT_UINT64, BASE_DEC, NULL, 0x0,
 300             NULL, HFILL }
 301         },
 302         { &hf_fti_encoding_symbol_length,
 303           { "Encoding Symbol Length", "rmt-fec.fti.encoding_symbol_length",
 304             FT_UINT32, BASE_DEC, NULL, 0x0,
 305             NULL, HFILL }
 306         },
 307         { &hf_fti_max_source_block_length,
 308           { "Maximum Source Block Length", "rmt-fec.fti.max_source_block_length",
 309             FT_UINT32, BASE_DEC, NULL, 0x0,
 310             NULL, HFILL }
 311         },
 312         { &hf_fti_max_number_encoding_symbols,
 313           { "Maximum Number of Encoding Symbols", "rmt-fec.fti.max_number_encoding_symbols",
 314             FT_UINT32, BASE_DEC, NULL, 0x0,
 315             NULL, HFILL }
 316         },
 317         { &hf_fti_num_blocks,
 318           { "Number of Source Blocks", "rmt-fec.fti.num_blocks",
 319             FT_UINT16, BASE_DEC, NULL, 0x0,
 320             NULL, HFILL }
 321         },
 322         { &hf_fti_num_subblocks,
 323           { "Number of Sub-Blocks", "rmt-fec.fti.num_subblocks",
 324             FT_UINT16, BASE_DEC, NULL, 0x0,
 325             NULL, HFILL }
 326         },
 327         { &hf_fti_alignment,
 328           { "Symbol Alignment", "rmt-fec.fti.alignment",
 329             FT_UINT8, BASE_DEC, NULL, 0x0,
 330             NULL, HFILL }
 331         }
 332     };
 333
 334     /* Setup protocol subtree array */
 335     static int *ett[] = {
 336         &ett_main,
 337     };
 338
 339     static ei_register_info ei[] = {
 340         { &ei_fec_encoding_id, { "rmt-fec.encoding_id.not0", PI_PROTOCOL, PI_WARN, "FEC Encoding ID < 128, should be zero", EXPFILL }},
 341     };
 342
 343     expert_module_t* expert_rmt_fec;
 344
 345     /* Register the protocol name and description */
 346     proto_rmt_fec = proto_register_protocol("Forward Error Correction (FEC)", "RMT-FEC", "rmt-fec");
 347     register_dissector("rmt-fec", dissect_fec, proto_rmt_fec);
 348
 349     /* Required function calls to register the header fields and subtrees used */
 350     proto_register_field_array(proto_rmt_fec, hf, array_length(hf));
 351     proto_register_subtree_array(ett, array_length(ett));
 352     expert_rmt_fec = expert_register_protocol(proto_rmt_fec);
 353     expert_register_field_array(expert_rmt_fec, ei, array_length(ei));
 354 }
 355
 356 /*
 357  * Editor modelines - https://www.wireshark.org/tools/modelines.html
 358  *
 359  * Local variables:
 360  * c-basic-offset: 4
 361  * tab-width: 8
 362  * indent-tabs-mode: nil
 363  * End:
 364  *
 365  * ex: set shiftwidth=4 tabstop=8 expandtab:
 366  * :indentSize=4:tabSize=8:noTabs=true:
 367  */