epan/dissectors/packet-bier.c

   1 /* @file
   2  * Routines for Bit Index Explicit Replication (BIER) dissection
   3  *
   4  * Copyright 2024, John Thacker <johnthacker@gmail.com>
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  *
  12  * RFC 8296: https://www.rfc-editor.org/rfc/rfc8296.html
  13  */
  14
  15 #include "config.h"
  16
  17 #include <epan/packet.h>
  18
  19 void proto_register_bier(void);
  20 void proto_reg_handoff_bier(void);
  21
  22 static int proto_bier;
  23
  24 static int hf_bier_nibble;
  25 static int hf_bier_ver;
  26 static int hf_bier_bsl;
  27 static int hf_bier_entropy;
  28 static int hf_bier_oam;
  29 static int hf_bier_rsv;
  30 static int hf_bier_dscp;
  31 static int hf_bier_proto;
  32 static int hf_bier_bfir_id;
  33 static int hf_bier_bitstring;
  34
  35 static int ett_bier;
  36
  37 static dissector_table_t bier_subdissector_table;
  38
  39 static dissector_handle_t bier_handle;
  40
  41 static const value_string bier_bsl_vals[] = {
  42     { 1, "64 bits" },
  43     { 2, "128 bits" },
  44     { 3, "256 bits" },
  45     { 4, "512 bits" },
  46     { 5, "1024 bits" },
  47     { 6, "2048 bits" },
  48     { 7, "4096 bits" },
  49     { 0, NULL }
  50 };
  51
  52 // https://www.iana.org/assignments/bier/bier.xhtml#bier-next-protocol-identifiers
  53 static const value_string bier_proto_vals[] = {
  54     { 0, "Reserved" },
  55     { 1, "MPLS packet with downstream-assigned label at top of stack" },
  56     { 2, "MPLS packet with upstream-assigned label at top of stack" },
  57     { 3, "Ethernet frame" },
  58     { 4, "IPv4 packet" },
  59     { 5, "OAM packet" },
  60     { 6, "IPv6 packet" },
  61     { 7, "Payload is VXLAN encapsulated (no IP/UDP header)" },
  62     { 8, "Payload is NVGRE encapsulated (no IP header)" },
  63     { 9, "Payload is GENEVE encapsulated (no IP/UDP header)" },
  64     { 63, "Reserved" },
  65     { 0, NULL }
  66 };
  67
  68 static int
  69 dissect_bier(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, void* data _U_)
  70 {
  71     proto_item *ti;
  72     proto_tree *bier_tree;
  73
  74     unsigned offset = 0;
  75     uint32_t proto;
  76     tvbuff_t *next_tvb;
  77
  78     if (tvb_reported_length(tvb) < 16) {
  79         return 0;
  80     }
  81
  82     if (tvb_captured_length(tvb) < 2) {
  83         return 0;
  84     }
  85
  86     /* This nibble is ignored in non-MPLS */
  87     if (((tvb_get_uint8(tvb, 0) >> 4) & 0xF) != 0x5) {
  88         return 0;
  89     }
  90
  91     uint8_t bsl = (tvb_get_uint8(tvb, 1) >> 4) & 0xF;
  92     if (bsl == 0 || bsl > 7) {
  93         return 0;
  94     }
  95
  96     int bitstring_length = 1 << (bsl + 2);
  97
  98     if (tvb_reported_length_remaining(tvb, 8) < bitstring_length) {
  99         return 0;
 100     }
 101
 102     col_set_str(pinfo->cinfo, COL_PROTOCOL, "BIER");
 103     col_clear(pinfo->cinfo, COL_INFO);
 104
 105     ti = proto_tree_add_item(tree, proto_bier, tvb, offset, 8 + bitstring_length, ENC_NA);
 106
 107     bier_tree = proto_item_add_subtree(ti, ett_bier);
 108
 109     proto_tree_add_item(bier_tree, hf_bier_nibble, tvb, offset, 1, ENC_NA);
 110     proto_tree_add_item(bier_tree, hf_bier_ver, tvb, offset, 1, ENC_NA);
 111     offset += 1;
 112
 113     proto_tree_add_item(bier_tree, hf_bier_bsl, tvb, offset, 1, ENC_NA);
 114     proto_tree_add_item(bier_tree, hf_bier_entropy, tvb, offset, 3, ENC_BIG_ENDIAN);
 115     offset += 3;
 116
 117     proto_tree_add_item(bier_tree, hf_bier_oam, tvb, offset, 1, ENC_NA);
 118     proto_tree_add_item(bier_tree, hf_bier_rsv, tvb, offset, 1, ENC_NA);
 119     /* DSCP field unused in MPLS; may be as IP DSCP in non-MPLS. */
 120     proto_tree_add_item(bier_tree, hf_bier_dscp, tvb, offset, 2, ENC_BIG_ENDIAN);
 121     offset += 1;
 122
 123     proto_tree_add_item_ret_uint(bier_tree, hf_bier_proto, tvb, offset, 1, ENC_NA, &proto);
 124     col_add_str(pinfo->cinfo, COL_INFO, val_to_str_wmem(pinfo->pool, proto, bier_proto_vals, "Unknown (0x%02x)"));
 125     offset += 1;
 126
 127     proto_tree_add_item(bier_tree, hf_bier_bfir_id, tvb, offset, 2, ENC_BIG_ENDIAN);
 128     offset += 2;
 129
 130     proto_tree_add_item(bier_tree, hf_bier_bitstring, tvb, offset, bitstring_length, ENC_NA);
 131     offset += bitstring_length;
 132
 133     next_tvb = tvb_new_subset_remaining(tvb, offset);
 134     if (!dissector_try_uint(bier_subdissector_table, proto, next_tvb, pinfo, tree)) {
 135         call_data_dissector(next_tvb, pinfo, tree);
 136     }
 137
 138     return tvb_captured_length(tvb);
 139 }
 140
 141 void
 142 proto_register_bier(void)
 143 {
 144     static hf_register_info hf[] = {
 145         {
 146             &hf_bier_nibble,
 147             {
 148                 "Nibble", "bier.nibble", FT_UINT8,
 149                 BASE_HEX, NULL, 0xF0, NULL, HFILL
 150             }
 151         },
 152         {
 153             &hf_bier_ver,
 154             {
 155                 "Version", "bier.ver", FT_UINT8,
 156                 BASE_DEC, NULL, 0x0F, NULL, HFILL
 157             }
 158         },
 159         {
 160             &hf_bier_bsl,
 161             {
 162                 "BitString Length", "bier.bsl", FT_UINT8,
 163                 BASE_DEC, VALS(bier_bsl_vals), 0xF0, NULL, HFILL
 164             }
 165         },
 166         {
 167             &hf_bier_entropy,
 168             {
 169                 "Entropy", "bier.entropy", FT_UINT24,
 170                 BASE_HEX, NULL, 0x0FFFFF, NULL, HFILL
 171             }
 172         },
 173         {
 174             &hf_bier_oam,
 175             {
 176                 "OAM", "bier.oam", FT_UINT8,
 177                 BASE_HEX, NULL, 0xC0, NULL, HFILL
 178             }
 179         },
 180         {
 181             &hf_bier_rsv,
 182             {
 183                 "Rsv", "bier.rsv", FT_UINT8,
 184                 BASE_HEX, NULL, 0x30, NULL, HFILL
 185             }
 186         },
 187         {
 188             &hf_bier_dscp,
 189             {
 190                 "DSCP", "bier.dscp", FT_UINT16,
 191                 BASE_HEX, NULL, 0x0FC0, NULL, HFILL
 192             }
 193         },
 194         {
 195             &hf_bier_proto,
 196             {
 197                 "Next Protocol", "bier.proto", FT_UINT8,
 198                 BASE_HEX, VALS(bier_proto_vals), 0x3F, NULL, HFILL
 199             }
 200         },
 201         {
 202             &hf_bier_bfir_id,
 203             {
 204                 "BFIR-id", "bier.bfir-id", FT_UINT16,
 205                 BASE_DEC, NULL, 0x0, NULL, HFILL
 206             }
 207         },
 208         {
 209             &hf_bier_bitstring,
 210             {
 211                 "BitString", "bier.bitstring", FT_BYTES,
 212                 BASE_NONE, NULL, 0x0, NULL, HFILL
 213             }
 214         },
 215     };
 216
 217     static int *ett[] = {
 218         &ett_bier
 219     };
 220
 221     proto_bier =
 222         proto_register_protocol("Bit Index Explicit Replication", "BIER", "bier");
 223
 224     proto_register_field_array(proto_bier, hf, array_length(hf));
 225     proto_register_subtree_array(ett, array_length(ett));
 226     bier_handle = register_dissector_with_description("bier.mpls", "BIER encapsulated in MPLS", dissect_bier, proto_bier);
 227
 228     bier_subdissector_table = register_dissector_table("bier.proto",
 229         "BIER Next Protocol", proto_bier, FT_UINT8, BASE_DEC);
 230 }
 231
 232 void
 233 proto_reg_handoff_bier(void)
 234 {
 235     dissector_handle_t mpls_handle = find_dissector_add_dependency("mpls", proto_bier);
 236
 237     dissector_add_for_decode_as("mpls.label", bier_handle);
 238
 239     dissector_add_uint("mpls.pfn", 5, bier_handle);
 240
 241     dissector_add_uint("bier.proto", 1, mpls_handle);
 242     dissector_add_uint("bier.proto", 2, mpls_handle);
 243     dissector_add_uint("bier.proto", 3, find_dissector_add_dependency("eth_maybefcs", proto_bier));
 244     dissector_add_uint("bier.proto", 4, find_dissector_add_dependency("ip", proto_bier));
 245     /* 5 is BIER OAM - https://datatracker.ietf.org/doc/draft-ietf-bier-ping/ */
 246     dissector_add_uint("bier.proto", 6, find_dissector_add_dependency("ipv6", proto_bier));
 247     dissector_add_uint("bier.proto", 7, find_dissector_add_dependency("vxlan", proto_bier));
 248     dissector_add_uint("bier.proto", 8, find_dissector_add_dependency("gre", proto_bier));
 249     dissector_add_uint("bier.proto", 9, find_dissector_add_dependency("geneve", proto_bier));
 250 }