/* packet-rmt-fec.c * Reliable Multicast Transport (RMT) * FEC Building Block dissector * Copyright 2005, Stefano Pettini * * Forward Error Correction (ALC): * ------------------------------- * * The goal of the FEC building block is to describe functionality * directly related to FEC codes that is common to all reliable content * delivery IP multicast protocols, and to leave out any additional * functionality that is specific to particular protocols. * * References: * RFC 3452, Forward Error Correction Building Block * RFC 3695, Compact Forward Error Correction (FEC) Schemes * Simple XOR, Reed-Solomon, and Parity Check Matrix-based FEC Schemes draft-peltotalo-rmt-bb-fec-supp-xor-pcm-rs-00 * IANA RMT FEC parameters (http://www.iana.org/assignments/rmt-fec-parameters) * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ #include "config.h" #include #include #include #include "packet-rmt-common.h" void proto_register_rmt_fec(void); static int proto_rmt_fec; static int hf_encoding_id; static int hf_instance_id; static int hf_sbn; static int hf_sbn_with_mask; static int hf_sbl; static int hf_esi; static int hf_esi_with_mask; static int hf_fti_transfer_length; static int hf_fti_encoding_symbol_length; static int hf_fti_max_source_block_length; static int hf_fti_max_number_encoding_symbols; static int hf_fti_num_blocks; static int hf_fti_num_subblocks; static int hf_fti_alignment; static int ett_main; static expert_field ei_fec_encoding_id; typedef struct fec_packet_data { uint8_t instance_id; } fec_packet_data_t; /* String tables */ const value_string string_fec_encoding_id[] = { { 0, "Compact No-Code" }, { 1, "Raptor" }, { 2, "Reed-Solomon Codes over GF(2^^m)" }, { 3, "LDPC Staircase Codes" }, { 4, "LDPC Triangle Codes" }, { 5, "Reed-Solomon Codes over GF(2^^8)" }, { 6, "RaptorQ Code" }, /* 7-127 Unassigned */ { 128, "Small Block, Large Block and Expandable FEC Codes" }, { 129, "Small Block Systematic FEC Codes" }, { 130, "Compact FEC Codes" }, /* 131-255 Unassigned */ { 0, NULL } }; /* Dissection */ /* ---------- */ /* Decode an EXT_FTI extension and fill FEC array */ void fec_decode_ext_fti(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, uint8_t encoding_id) { uint64_t transfer_length; fec_packet_data_t *fec_data; uint8_t instance_id = 0; proto_item *ti; if (encoding_id == 6){ /* Raptor Q uses 40-bit transfer length */ transfer_length = tvb_get_ntoh40(tvb, offset+2); } else { /* Decode 48-bit length field */ transfer_length = tvb_get_ntoh48(tvb, offset+2); } if (encoding_id >= 128) { instance_id = (uint8_t) tvb_get_ntohs(tvb, offset+8); /* Decode FEC Instance ID */ fec_data = wmem_new0(wmem_file_scope(), fec_packet_data_t); fec_data->instance_id = instance_id; p_add_proto_data(wmem_file_scope(), pinfo, proto_rmt_fec, 0, fec_data); } if (encoding_id == 6){ /* Raptor Q uses 40-bit transfer length */ proto_tree_add_uint64(tree, hf_fti_transfer_length, tvb, offset+2, 5, transfer_length); } else { proto_tree_add_uint64(tree, hf_fti_transfer_length, tvb, offset+2, 6, transfer_length); ti = proto_tree_add_item(tree, hf_instance_id, tvb, offset+8, 2, ENC_BIG_ENDIAN); if ((encoding_id < 128) && (encoding_id != 0)) { expert_add_info(pinfo, ti, &ei_fec_encoding_id); } } switch (encoding_id) { case 1: proto_tree_add_item(tree, hf_fti_encoding_symbol_length, tvb, offset+10, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_num_blocks, tvb, offset+12, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_num_subblocks, tvb, offset+14, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_alignment, tvb, offset+15, 1, ENC_BIG_ENDIAN); break; case 6: proto_tree_add_item(tree, hf_fti_encoding_symbol_length, tvb, offset+8, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_num_blocks, tvb, offset+10, 1, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_num_subblocks, tvb, offset+11, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_alignment, tvb, offset+13, 1, ENC_BIG_ENDIAN); break; case 0: case 2: case 128: case 130: proto_tree_add_item(tree, hf_fti_encoding_symbol_length, tvb, offset+10, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_max_source_block_length, tvb, offset+12, 4, ENC_BIG_ENDIAN); break; case 129: proto_tree_add_item(tree, hf_fti_encoding_symbol_length, tvb, offset+10, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_max_source_block_length, tvb, offset+12, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_max_number_encoding_symbols, tvb, offset+14, 2, ENC_BIG_ENDIAN); break; case 132: proto_tree_add_item(tree, hf_fti_encoding_symbol_length, tvb, offset+10, 2, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_max_source_block_length, tvb, offset+12, 4, ENC_BIG_ENDIAN); proto_tree_add_item(tree, hf_fti_max_number_encoding_symbols, tvb, offset+16, 4, ENC_BIG_ENDIAN); break; } } /* Dissect a FEC header: * fec - ptr to the logical FEC packet representation to fill * hf - ptr to header fields array * ett - ptr to ett array * prefs - ptr to FEC prefs array * tvb - buffer * pinfo - packet info * tree - tree where to add FEC header subtree * offset - ptr to offset to use and update */ static int dissect_fec(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data) { proto_item *ti; proto_tree *fec_tree; unsigned offset = 0; fec_data_exchange_t *fec = (fec_data_exchange_t*)data; uint8_t encoding_id = 0; fec_packet_data_t *packet_data = (fec_packet_data_t*)p_get_proto_data(wmem_file_scope(), pinfo, proto_rmt_fec, 0); if (fec != NULL) { encoding_id = fec->encoding_id; } /* Create the FEC subtree */ ti = proto_tree_add_item(tree, proto_rmt_fec, tvb, offset, -1, ENC_NA); fec_tree = proto_item_add_subtree(ti, ett_main); proto_tree_add_uint(fec_tree, hf_encoding_id, tvb, offset, 0, encoding_id); if (encoding_id >= 128 && (packet_data != NULL)) proto_tree_add_uint(fec_tree, hf_instance_id, tvb, offset, 0, packet_data->instance_id); switch (encoding_id) { case 0: case 1: case 130: proto_tree_add_item(fec_tree, hf_sbn, tvb, offset, 2, ENC_BIG_ENDIAN); proto_tree_add_item(fec_tree, hf_esi, tvb, offset+2, 2, ENC_BIG_ENDIAN); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohs(tvb, offset)); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohs(tvb, offset+2)); offset += 4; break; case 2: case 128: case 132: proto_tree_add_item(fec_tree, hf_sbn, tvb, offset, 4, ENC_BIG_ENDIAN); proto_tree_add_item(fec_tree, hf_esi, tvb, offset+4, 4, ENC_BIG_ENDIAN); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohl(tvb, offset)); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohl(tvb, offset+4)); offset += 8; break; case 3: case 4: proto_tree_add_item(fec_tree, hf_sbn_with_mask, tvb, offset, 4, ENC_BIG_ENDIAN); proto_tree_add_item(fec_tree, hf_esi_with_mask, tvb, offset, 4, ENC_BIG_ENDIAN); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohl(tvb, offset) >> 20); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohl(tvb, offset) & 0xfffff); offset += 4; break; case 6: proto_tree_add_item(fec_tree, hf_sbn, tvb, offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(fec_tree, hf_esi, tvb, offset+1, 3, ENC_BIG_ENDIAN); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_uint8(tvb, offset)); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntoh24(tvb, offset+1)); offset += 4; break; case 129: proto_tree_add_item(fec_tree, hf_sbn, tvb, offset, 4, ENC_BIG_ENDIAN); proto_tree_add_item(fec_tree, hf_sbl, tvb, offset+4, 2, ENC_BIG_ENDIAN); proto_tree_add_item(fec_tree, hf_esi, tvb, offset+6, 2, ENC_BIG_ENDIAN); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "SBN: %u", tvb_get_ntohl(tvb, offset)); col_append_sep_fstr(pinfo->cinfo, COL_INFO, " ", "ESI: 0x%X", tvb_get_ntohs(tvb, offset+6)); offset += 8; break; } return offset; } void proto_register_rmt_fec(void) { static hf_register_info hf[] = { { &hf_encoding_id, { "FEC Encoding ID", "rmt-fec.encoding_id", FT_UINT8, BASE_DEC, VALS(string_fec_encoding_id), 0x0, NULL, HFILL } }, { &hf_instance_id, { "FEC Instance ID", "rmt-fec.instance_id", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_sbn, { "Source Block Number", "rmt-fec.sbn", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_sbn_with_mask, { "Source Block Number", "rmt-fec.sbn", FT_UINT32, BASE_DEC, NULL, 0xFFF00000, NULL, HFILL } }, { &hf_sbl, { "Source Block Length", "rmt-fec.sbl", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_esi, { "Encoding Symbol ID", "rmt-fec.esi", FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL } }, { &hf_esi_with_mask, { "Encoding Symbol ID", "rmt-fec.esi", FT_UINT32, BASE_HEX, NULL, 0x000FFFFF, NULL, HFILL } }, { &hf_fti_transfer_length, { "Transfer Length", "rmt-fec.fti.transfer_length", FT_UINT64, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_fti_encoding_symbol_length, { "Encoding Symbol Length", "rmt-fec.fti.encoding_symbol_length", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_fti_max_source_block_length, { "Maximum Source Block Length", "rmt-fec.fti.max_source_block_length", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_fti_max_number_encoding_symbols, { "Maximum Number of Encoding Symbols", "rmt-fec.fti.max_number_encoding_symbols", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_fti_num_blocks, { "Number of Source Blocks", "rmt-fec.fti.num_blocks", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_fti_num_subblocks, { "Number of Sub-Blocks", "rmt-fec.fti.num_subblocks", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } }, { &hf_fti_alignment, { "Symbol Alignment", "rmt-fec.fti.alignment", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } } }; /* Setup protocol subtree array */ static int *ett[] = { &ett_main, }; static ei_register_info ei[] = { { &ei_fec_encoding_id, { "rmt-fec.encoding_id.not0", PI_PROTOCOL, PI_WARN, "FEC Encoding ID < 128, should be zero", EXPFILL }}, }; expert_module_t* expert_rmt_fec; /* Register the protocol name and description */ proto_rmt_fec = proto_register_protocol("Forward Error Correction (FEC)", "RMT-FEC", "rmt-fec"); register_dissector("rmt-fec", dissect_fec, proto_rmt_fec); /* Required function calls to register the header fields and subtrees used */ proto_register_field_array(proto_rmt_fec, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); expert_rmt_fec = expert_register_protocol(proto_rmt_fec); expert_register_field_array(expert_rmt_fec, ei, array_length(ei)); } /* * Editor modelines - https://www.wireshark.org/tools/modelines.html * * Local variables: * c-basic-offset: 4 * tab-width: 8 * indent-tabs-mode: nil * End: * * ex: set shiftwidth=4 tabstop=8 expandtab: * :indentSize=4:tabSize=8:noTabs=true: */