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/* @file
* Routines for Bit Index Explicit Replication (BIER) dissection
*
* Copyright 2024, John Thacker <johnthacker@gmail.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* RFC 8296: https://www.rfc-editor.org/rfc/rfc8296.html
*/
#include "config.h"
#include <epan/packet.h>
void proto_register_bier(void);
void proto_reg_handoff_bier(void);
static int proto_bier;
static int hf_bier_nibble;
static int hf_bier_ver;
static int hf_bier_bsl;
static int hf_bier_entropy;
static int hf_bier_oam;
static int hf_bier_rsv;
static int hf_bier_dscp;
static int hf_bier_proto;
static int hf_bier_bfir_id;
static int hf_bier_bitstring;
static int ett_bier;
static dissector_table_t bier_subdissector_table;
static dissector_handle_t bier_handle;
static const value_string bier_bsl_vals[] = {
{ 1, "64 bits" },
{ 2, "128 bits" },
{ 3, "256 bits" },
{ 4, "512 bits" },
{ 5, "1024 bits" },
{ 6, "2048 bits" },
{ 7, "4096 bits" },
{ 0, NULL }
};
// https://www.iana.org/assignments/bier/bier.xhtml#bier-next-protocol-identifiers
static const value_string bier_proto_vals[] = {
{ 0, "Reserved" },
{ 1, "MPLS packet with downstream-assigned label at top of stack" },
{ 2, "MPLS packet with upstream-assigned label at top of stack" },
{ 3, "Ethernet frame" },
{ 4, "IPv4 packet" },
{ 5, "OAM packet" },
{ 6, "IPv6 packet" },
{ 7, "Payload is VXLAN encapsulated (no IP/UDP header)" },
{ 8, "Payload is NVGRE encapsulated (no IP header)" },
{ 9, "Payload is GENEVE encapsulated (no IP/UDP header)" },
{ 63, "Reserved" },
{ 0, NULL }
};
static int
dissect_bier(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, void* data _U_)
{
proto_item *ti;
proto_tree *bier_tree;
unsigned offset = 0;
uint32_t proto;
tvbuff_t *next_tvb;
if (tvb_reported_length(tvb) < 16) {
return 0;
}
if (tvb_captured_length(tvb) < 2) {
return 0;
}
/* This nibble is ignored in non-MPLS */
if (((tvb_get_uint8(tvb, 0) >> 4) & 0xF) != 0x5) {
return 0;
}
uint8_t bsl = (tvb_get_uint8(tvb, 1) >> 4) & 0xF;
if (bsl == 0 || bsl > 7) {
return 0;
}
int bitstring_length = 1 << (bsl + 2);
if (tvb_reported_length_remaining(tvb, 8) < bitstring_length) {
return 0;
}
col_set_str(pinfo->cinfo, COL_PROTOCOL, "BIER");
col_clear(pinfo->cinfo, COL_INFO);
ti = proto_tree_add_item(tree, proto_bier, tvb, offset, 8 + bitstring_length, ENC_NA);
bier_tree = proto_item_add_subtree(ti, ett_bier);
proto_tree_add_item(bier_tree, hf_bier_nibble, tvb, offset, 1, ENC_NA);
proto_tree_add_item(bier_tree, hf_bier_ver, tvb, offset, 1, ENC_NA);
offset += 1;
proto_tree_add_item(bier_tree, hf_bier_bsl, tvb, offset, 1, ENC_NA);
proto_tree_add_item(bier_tree, hf_bier_entropy, tvb, offset, 3, ENC_BIG_ENDIAN);
offset += 3;
proto_tree_add_item(bier_tree, hf_bier_oam, tvb, offset, 1, ENC_NA);
proto_tree_add_item(bier_tree, hf_bier_rsv, tvb, offset, 1, ENC_NA);
/* DSCP field unused in MPLS; may be as IP DSCP in non-MPLS. */
proto_tree_add_item(bier_tree, hf_bier_dscp, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 1;
proto_tree_add_item_ret_uint(bier_tree, hf_bier_proto, tvb, offset, 1, ENC_NA, &proto);
col_add_str(pinfo->cinfo, COL_INFO, val_to_str_wmem(pinfo->pool, proto, bier_proto_vals, "Unknown (0x%02x)"));
offset += 1;
proto_tree_add_item(bier_tree, hf_bier_bfir_id, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(bier_tree, hf_bier_bitstring, tvb, offset, bitstring_length, ENC_NA);
offset += bitstring_length;
next_tvb = tvb_new_subset_remaining(tvb, offset);
if (!dissector_try_uint(bier_subdissector_table, proto, next_tvb, pinfo, tree)) {
call_data_dissector(next_tvb, pinfo, tree);
}
return tvb_captured_length(tvb);
}
void
proto_register_bier(void)
{
static hf_register_info hf[] = {
{
&hf_bier_nibble,
{
"Nibble", "bier.nibble", FT_UINT8,
BASE_HEX, NULL, 0xF0, NULL, HFILL
}
},
{
&hf_bier_ver,
{
"Version", "bier.ver", FT_UINT8,
BASE_DEC, NULL, 0x0F, NULL, HFILL
}
},
{
&hf_bier_bsl,
{
"BitString Length", "bier.bsl", FT_UINT8,
BASE_DEC, VALS(bier_bsl_vals), 0xF0, NULL, HFILL
}
},
{
&hf_bier_entropy,
{
"Entropy", "bier.entropy", FT_UINT24,
BASE_HEX, NULL, 0x0FFFFF, NULL, HFILL
}
},
{
&hf_bier_oam,
{
"OAM", "bier.oam", FT_UINT8,
BASE_HEX, NULL, 0xC0, NULL, HFILL
}
},
{
&hf_bier_rsv,
{
"Rsv", "bier.rsv", FT_UINT8,
BASE_HEX, NULL, 0x30, NULL, HFILL
}
},
{
&hf_bier_dscp,
{
"DSCP", "bier.dscp", FT_UINT16,
BASE_HEX, NULL, 0x0FC0, NULL, HFILL
}
},
{
&hf_bier_proto,
{
"Next Protocol", "bier.proto", FT_UINT8,
BASE_HEX, VALS(bier_proto_vals), 0x3F, NULL, HFILL
}
},
{
&hf_bier_bfir_id,
{
"BFIR-id", "bier.bfir-id", FT_UINT16,
BASE_DEC, NULL, 0x0, NULL, HFILL
}
},
{
&hf_bier_bitstring,
{
"BitString", "bier.bitstring", FT_BYTES,
BASE_NONE, NULL, 0x0, NULL, HFILL
}
},
};
static int *ett[] = {
&ett_bier
};
proto_bier =
proto_register_protocol("Bit Index Explicit Replication", "BIER", "bier");
proto_register_field_array(proto_bier, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
bier_handle = register_dissector_with_description("bier.mpls", "BIER encapsulated in MPLS", dissect_bier, proto_bier);
bier_subdissector_table = register_dissector_table("bier.proto",
"BIER Next Protocol", proto_bier, FT_UINT8, BASE_DEC);
}
void
proto_reg_handoff_bier(void)
{
dissector_handle_t mpls_handle = find_dissector_add_dependency("mpls", proto_bier);
dissector_add_for_decode_as("mpls.label", bier_handle);
dissector_add_uint("mpls.pfn", 5, bier_handle);
dissector_add_uint("bier.proto", 1, mpls_handle);
dissector_add_uint("bier.proto", 2, mpls_handle);
dissector_add_uint("bier.proto", 3, find_dissector_add_dependency("eth_maybefcs", proto_bier));
dissector_add_uint("bier.proto", 4, find_dissector_add_dependency("ip", proto_bier));
/* 5 is BIER OAM - https://datatracker.ietf.org/doc/draft-ietf-bier-ping/ */
dissector_add_uint("bier.proto", 6, find_dissector_add_dependency("ipv6", proto_bier));
dissector_add_uint("bier.proto", 7, find_dissector_add_dependency("vxlan", proto_bier));
dissector_add_uint("bier.proto", 8, find_dissector_add_dependency("gre", proto_bier));
dissector_add_uint("bier.proto", 9, find_dissector_add_dependency("geneve", proto_bier));
}
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