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Name	Size	Permission	Date
9p	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
bluetooth	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
caif	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
iucv	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
mana	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
netfilter	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
netns	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
nfc	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
page_pool	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
phonet	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
sctp	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
tc_act	[ DIR ]	drwxr-xr-x	2026-06-04 06:36
6lowpan.h	10.03 KB	-rw-r--r--	2024-03-10 20:38
Space.h	455 B	-rw-r--r--	2024-03-10 20:38
act_api.h	9.27 KB	-rw-r--r--	2024-03-10 20:38
addrconf.h	14.28 KB	-rw-r--r--	2026-05-26 09:55
af_ieee802154.h	1.19 KB	-rw-r--r--	2024-03-10 20:38
af_rxrpc.h	3.3 KB	-rw-r--r--	2024-03-10 20:38
af_unix.h	3.76 KB	-rw-r--r--	2026-05-26 09:55
af_vsock.h	8.41 KB	-rw-r--r--	2026-05-26 09:55
ah.h	382 B	-rw-r--r--	2024-03-10 20:38
amt.h	8.35 KB	-rw-r--r--	2024-03-10 20:38
arp.h	1.95 KB	-rw-r--r--	2024-03-10 20:38
atmclip.h	1.48 KB	-rw-r--r--	2024-03-10 20:38
ax25.h	14.94 KB	-rw-r--r--	2026-05-26 09:55
ax88796.h	1.43 KB	-rw-r--r--	2024-03-10 20:38
bareudp.h	333 B	-rw-r--r--	2024-03-10 20:38
bond_3ad.h	9.48 KB	-rw-r--r--	2026-05-26 09:55
bond_alb.h	6.1 KB	-rw-r--r--	2024-03-10 20:38
bond_options.h	4.83 KB	-rw-r--r--	2026-05-26 09:55
bonding.h	21.37 KB	-rw-r--r--	2026-05-26 09:55
bpf_sk_storage.h	1.74 KB	-rw-r--r--	2024-03-10 20:38
busy_poll.h	4.28 KB	-rw-r--r--	2026-05-26 09:55
calipso.h	1.55 KB	-rw-r--r--	2024-03-10 20:38
cfg80211-wext.h	1.86 KB	-rw-r--r--	2024-03-10 20:38
cfg80211.h	336.64 KB	-rw-r--r--	2026-05-26 09:55
cfg802154.h	16.68 KB	-rw-r--r--	2026-05-26 09:55
checksum.h	4.98 KB	-rw-r--r--	2026-05-26 09:55
cipso_ipv4.h	7.37 KB	-rw-r--r--	2024-03-10 20:38
cls_cgroup.h	2.04 KB	-rw-r--r--	2026-05-26 09:55
codel.h	5.86 KB	-rw-r--r--	2024-03-10 20:38
codel_impl.h	8.3 KB	-rw-r--r--	2024-03-10 20:38
codel_qdisc.h	2.95 KB	-rw-r--r--	2024-03-10 20:38
compat.h	2.48 KB	-rw-r--r--	2024-03-10 20:38
datalink.h	590 B	-rw-r--r--	2024-03-10 20:38
dcbevent.h	766 B	-rw-r--r--	2024-03-10 20:38
dcbnl.h	4.98 KB	-rw-r--r--	2024-03-10 20:38
devlink.h	70.92 KB	-rw-r--r--	2024-03-10 20:38
dropreason-core.h	14.76 KB	-rw-r--r--	2026-05-26 09:55
dropreason.h	1.36 KB	-rw-r--r--	2024-03-10 20:38
dsa.h	41.05 KB	-rw-r--r--	2026-05-26 09:55
dsa_stubs.h	1.28 KB	-rw-r--r--	2024-03-10 20:38
dsfield.h	1.12 KB	-rw-r--r--	2024-03-10 20:38
dst.h	15.12 KB	-rw-r--r--	2026-05-26 09:55
dst_cache.h	2.96 KB	-rw-r--r--	2024-03-10 20:38
dst_metadata.h	6.34 KB	-rw-r--r--	2024-03-10 20:38
dst_ops.h	2.07 KB	-rw-r--r--	2026-05-26 09:55
erspan.h	9.04 KB	-rw-r--r--	2024-03-10 20:38
esp.h	1.18 KB	-rw-r--r--	2024-03-10 20:38
espintcp.h	966 B	-rw-r--r--	2024-03-10 20:38
ethoc.h	439 B	-rw-r--r--	2024-03-10 20:38
failover.h	1.18 KB	-rw-r--r--	2024-03-10 20:38
fib_notifier.h	1.35 KB	-rw-r--r--	2024-03-10 20:38
fib_rules.h	5.39 KB	-rw-r--r--	2024-03-10 20:38
firewire.h	599 B	-rw-r--r--	2024-03-10 20:38
flow.h	4.96 KB	-rw-r--r--	2024-03-10 20:38
flow_dissector.h	11.95 KB	-rw-r--r--	2024-03-10 20:38
flow_offload.h	17.37 KB	-rw-r--r--	2024-03-10 20:38
fou.h	578 B	-rw-r--r--	2024-03-10 20:38
fq.h	2.41 KB	-rw-r--r--	2024-03-10 20:38
fq_impl.h	7.96 KB	-rw-r--r--	2024-03-10 20:38
garp.h	2.67 KB	-rw-r--r--	2024-03-10 20:38
gen_stats.h	2.99 KB	-rw-r--r--	2024-03-10 20:38
genetlink.h	19.62 KB	-rw-r--r--	2026-05-26 09:55
geneve.h	1.84 KB	-rw-r--r--	2024-03-10 20:38
gre.h	3.29 KB	-rw-r--r--	2024-03-10 20:38
gro.h	13.38 KB	-rw-r--r--	2026-05-26 09:55
gro_cells.h	443 B	-rw-r--r--	2024-03-10 20:38
gso.h	3.2 KB	-rw-r--r--	2024-03-10 20:38
gtp.h	1.46 KB	-rw-r--r--	2024-03-10 20:38
gue.h	3.29 KB	-rw-r--r--	2024-03-10 20:38
handshake.h	1.39 KB	-rw-r--r--	2024-03-10 20:38
hwbm.h	995 B	-rw-r--r--	2024-03-10 20:38
icmp.h	1.87 KB	-rw-r--r--	2024-03-10 20:38
ieee80211_radiotap.h	23.22 KB	-rw-r--r--	2026-05-26 09:55
ieee802154_netdev.h	13.02 KB	-rw-r--r--	2024-03-10 20:38
if_inet6.h	6.6 KB	-rw-r--r--	2024-03-10 20:38
ife.h	1.03 KB	-rw-r--r--	2024-03-10 20:38
inet6_connection_sock.h	794 B	-rw-r--r--	2024-03-10 20:38
inet6_hashtables.h	5.57 KB	-rw-r--r--	2026-05-26 09:55
inet_common.h	2.83 KB	-rw-r--r--	2024-03-10 20:38
inet_connection_sock.h	11.7 KB	-rw-r--r--	2026-05-26 09:55
inet_dscp.h	1.55 KB	-rw-r--r--	2024-03-10 20:38
inet_ecn.h	7.83 KB	-rw-r--r--	2024-03-10 20:38
inet_frag.h	5.25 KB	-rw-r--r--	2026-05-26 09:55
inet_hashtables.h	16.6 KB	-rw-r--r--	2026-05-26 09:55
inet_sock.h	11.36 KB	-rw-r--r--	2026-05-26 09:55
inet_timewait_sock.h	3.71 KB	-rw-r--r--	2026-05-26 09:55
inetpeer.h	3.23 KB	-rw-r--r--	2026-05-26 09:55
ioam6.h	1.19 KB	-rw-r--r--	2024-03-10 20:38
ip.h	23.18 KB	-rw-r--r--	2026-05-26 09:55
ip6_checksum.h	2.3 KB	-rw-r--r--	2024-03-10 20:38
ip6_fib.h	17.13 KB	-rw-r--r--	2026-05-26 09:55
ip6_route.h	10.18 KB	-rw-r--r--	2026-05-26 09:55
ip6_tunnel.h	5.01 KB	-rw-r--r--	2024-03-10 20:38
ip_fib.h	16.13 KB	-rw-r--r--	2026-05-26 09:55
ip_tunnels.h	16.52 KB	-rw-r--r--	2026-05-26 09:55
ip_vs.h	53.83 KB	-rw-r--r--	2024-03-10 20:38
ipcomp.h	737 B	-rw-r--r--	2024-03-10 20:38
ipconfig.h	837 B	-rw-r--r--	2024-03-10 20:38
ipv6.h	37.58 KB	-rw-r--r--	2026-05-26 09:55
ipv6_frag.h	3.38 KB	-rw-r--r--	2024-03-10 20:38
ipv6_stubs.h	3.75 KB	-rw-r--r--	2026-05-26 09:55
iw_handler.h	20.66 KB	-rw-r--r--	2024-03-10 20:38
kcm.h	4.84 KB	-rw-r--r--	2026-05-26 09:55
l3mdev.h	7.03 KB	-rw-r--r--	2026-05-26 09:55
lag.h	409 B	-rw-r--r--	2024-03-10 20:38
lapb.h	4.82 KB	-rw-r--r--	2026-05-26 09:55
lib80211.h	3.92 KB	-rw-r--r--	2024-03-10 20:38
llc.h	4.41 KB	-rw-r--r--	2024-03-10 20:38
llc_c_ac.h	9.32 KB	-rw-r--r--	2024-03-10 20:38
llc_c_ev.h	10.61 KB	-rw-r--r--	2024-03-10 20:38
llc_c_st.h	1.77 KB	-rw-r--r--	2024-03-10 20:38
llc_conn.h	4.11 KB	-rw-r--r--	2024-03-10 20:38
llc_if.h	2.17 KB	-rw-r--r--	2024-03-10 20:38
llc_pdu.h	14.46 KB	-rw-r--r--	2024-03-10 20:38
llc_s_ac.h	1.59 KB	-rw-r--r--	2024-03-10 20:38
llc_s_ev.h	2.22 KB	-rw-r--r--	2024-03-10 20:38
llc_s_st.h	1.03 KB	-rw-r--r--	2024-03-10 20:38
llc_sap.h	1.08 KB	-rw-r--r--	2024-03-10 20:38
lwtunnel.h	6.69 KB	-rw-r--r--	2026-05-26 09:55
mac80211.h	293.16 KB	-rw-r--r--	2026-05-26 09:55
mac802154.h	14.88 KB	-rw-r--r--	2024-03-10 20:38
macsec.h	10.53 KB	-rw-r--r--	2026-05-26 09:55
mctp.h	8.03 KB	-rw-r--r--	2026-05-26 09:55
mctpdevice.h	1.26 KB	-rw-r--r--	2024-03-10 20:38
mip6.h	1016 B	-rw-r--r--	2024-03-10 20:38
mld.h	2.85 KB	-rw-r--r--	2024-03-10 20:38
mpls.h	943 B	-rw-r--r--	2024-03-10 20:38
mpls_iptunnel.h	481 B	-rw-r--r--	2024-03-10 20:38
mptcp.h	7.41 KB	-rw-r--r--	2024-03-10 20:38
mrp.h	3.13 KB	-rw-r--r--	2024-03-10 20:38
ncsi.h	1.94 KB	-rw-r--r--	2024-03-10 20:38
ndisc.h	14.64 KB	-rw-r--r--	2024-03-10 20:38
neighbour.h	16.55 KB	-rw-r--r--	2026-05-26 09:55
net_debug.h	5.08 KB	-rw-r--r--	2026-05-26 09:55
net_failover.h	1023 B	-rw-r--r--	2024-03-10 20:38
net_namespace.h	14.36 KB	-rw-r--r--	2026-05-26 09:55
net_ratelimit.h	220 B	-rw-r--r--	2024-03-10 20:38
net_trackers.h	424 B	-rw-r--r--	2024-03-10 20:38
netdev_queues.h	5.75 KB	-rw-r--r--	2024-03-10 20:38
netdev_rx_queue.h	1.32 KB	-rw-r--r--	2024-03-10 20:38
netevent.h	1.04 KB	-rw-r--r--	2024-03-10 20:38
netkit.h	1.16 KB	-rw-r--r--	2024-03-10 20:38
netlabel.h	20.15 KB	-rw-r--r--	2026-05-26 09:55
netlink.h	64.18 KB	-rw-r--r--	2024-03-10 20:38
netprio_cgroup.h	1.02 KB	-rw-r--r--	2024-03-10 20:38
netrom.h	7.73 KB	-rw-r--r--	2024-03-10 20:38
nexthop.h	11.91 KB	-rw-r--r--	2024-03-10 20:38
nl802154.h	16.04 KB	-rw-r--r--	2024-03-10 20:38
nsh.h	12.3 KB	-rw-r--r--	2024-03-10 20:38
p8022.h	403 B	-rw-r--r--	2024-03-10 20:38
pie.h	3.6 KB	-rw-r--r--	2024-03-10 20:38
ping.h	2.66 KB	-rw-r--r--	2024-03-10 20:38
pkt_cls.h	25.47 KB	-rw-r--r--	2024-03-10 20:38
pkt_sched.h	7.74 KB	-rw-r--r--	2026-05-26 09:55
pptp.h	604 B	-rw-r--r--	2024-03-10 20:38
protocol.h	3.81 KB	-rw-r--r--	2024-03-10 20:38
psample.h	1.06 KB	-rw-r--r--	2024-03-10 20:38
psnap.h	430 B	-rw-r--r--	2024-03-10 20:38
raw.h	2.46 KB	-rw-r--r--	2024-03-10 20:38
rawv6.h	862 B	-rw-r--r--	2024-03-10 20:38
red.h	11.33 KB	-rw-r--r--	2024-03-10 20:38
regulatory.h	9.96 KB	-rw-r--r--	2024-03-10 20:38
request_sock.h	6.5 KB	-rw-r--r--	2024-03-10 20:38
rose.h	8.06 KB	-rw-r--r--	2026-05-26 09:55
route.h	11.32 KB	-rw-r--r--	2026-05-26 09:55
rpl.h	749 B	-rw-r--r--	2024-03-10 20:38
rsi_91x.h	1.67 KB	-rw-r--r--	2024-03-10 20:38
rtnetlink.h	7.58 KB	-rw-r--r--	2026-05-26 09:55
rtnh.h	859 B	-rw-r--r--	2024-03-10 20:38
sch_generic.h	34.15 KB	-rw-r--r--	2026-05-26 09:55
scm.h	5.36 KB	-rw-r--r--	2026-05-26 09:55
secure_seq.h	868 B	-rw-r--r--	2024-03-10 20:38
seg6.h	2.18 KB	-rw-r--r--	2024-03-10 20:38
seg6_hmac.h	1.44 KB	-rw-r--r--	2024-03-10 20:38
seg6_local.h	644 B	-rw-r--r--	2024-03-10 20:38
selftests.h	582 B	-rw-r--r--	2024-03-10 20:38
slhc_vj.h	6.67 KB	-rw-r--r--	2024-03-10 20:38
smc.h	2.5 KB	-rw-r--r--	2026-05-26 09:55
snmp.h	5.14 KB	-rw-r--r--	2024-03-10 20:38
sock.h	85.78 KB	-rw-r--r--	2026-05-26 09:55
sock_reuseport.h	1.83 KB	-rw-r--r--	2024-03-10 20:38
stp.h	412 B	-rw-r--r--	2024-03-10 20:38
strparser.h	4.34 KB	-rw-r--r--	2026-05-26 09:55
switchdev.h	15.1 KB	-rw-r--r--	2024-03-10 20:38
tc_wrapper.h	6.29 KB	-rw-r--r--	2026-05-26 09:55
tcp.h	85.12 KB	-rw-r--r--	2026-05-26 09:55
tcp_ao.h	12.08 KB	-rw-r--r--	2026-05-26 09:55
tcp_states.h	1.3 KB	-rw-r--r--	2024-03-10 20:38
tcx.h	4.3 KB	-rw-r--r--	2026-05-26 09:55
timewait_sock.h	925 B	-rw-r--r--	2024-03-10 20:38
tipc.h	2.35 KB	-rw-r--r--	2024-03-10 20:38
tls.h	13.28 KB	-rw-r--r--	2026-05-26 09:55
tls_prot.h	1.84 KB	-rw-r--r--	2024-03-10 20:38
tls_toe.h	2.94 KB	-rw-r--r--	2024-03-10 20:38
transp_v6.h	1.88 KB	-rw-r--r--	2024-03-10 20:38
tso.h	721 B	-rw-r--r--	2024-03-10 20:38
tun_proto.h	1015 B	-rw-r--r--	2024-03-10 20:38
udp.h	15.88 KB	-rw-r--r--	2026-05-26 09:55
udp_tunnel.h	12.47 KB	-rw-r--r--	2024-03-10 20:38
udplite.h	2.3 KB	-rw-r--r--	2024-03-10 20:38
vsock_addr.h	662 B	-rw-r--r--	2024-03-10 20:38
vxlan.h	15.83 KB	-rw-r--r--	2026-05-26 09:55
wext.h	1.47 KB	-rw-r--r--	2024-03-10 20:38
x25.h	9.46 KB	-rw-r--r--	2024-03-10 20:38
x25device.h	387 B	-rw-r--r--	2024-03-10 20:38
xdp.h	15.85 KB	-rw-r--r--	2026-05-26 09:55
xdp_priv.h	427 B	-rw-r--r--	2024-03-10 20:38
xdp_sock.h	6.3 KB	-rw-r--r--	2026-05-26 09:55
xdp_sock_drv.h	9.33 KB	-rw-r--r--	2024-03-10 20:38
xfrm.h	58.29 KB	-rw-r--r--	2026-05-26 09:55
xsk_buff_pool.h	7.13 KB	-rw-r--r--	2026-05-26 09:55

Rename

#ifndef __NET_NSH_H
#define __NET_NSH_H 1

#include <linux/skbuff.h>

/*
 * Network Service Header:
 *  0                   1                   2                   3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |Ver|O|U|    TTL    |   Length  |U|U|U|U|MD Type| Next Protocol |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |          Service Path Identifier (SPI)        | Service Index |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                                                               |
 * ~               Mandatory/Optional Context Headers              ~
 * |                                                               |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Version: The version field is used to ensure backward compatibility
 * going forward with future NSH specification updates.  It MUST be set
 * to 0x0 by the sender, in this first revision of NSH.  Given the
 * widespread implementation of existing hardware that uses the first
 * nibble after an MPLS label stack for ECMP decision processing, this
 * document reserves version 01b and this value MUST NOT be used in
 * future versions of the protocol.  Please see [RFC7325] for further
 * discussion of MPLS-related forwarding requirements.
 *
 * O bit: Setting this bit indicates an Operations, Administration, and
 * Maintenance (OAM) packet.  The actual format and processing of SFC
 * OAM packets is outside the scope of this specification (see for
 * example [I-D.ietf-sfc-oam-framework] for one approach).
 *
 * The O bit MUST be set for OAM packets and MUST NOT be set for non-OAM
 * packets.  The O bit MUST NOT be modified along the SFP.
 *
 * SF/SFF/SFC Proxy/Classifier implementations that do not support SFC
 * OAM procedures SHOULD discard packets with O bit set, but MAY support
 * a configurable parameter to enable forwarding received SFC OAM
 * packets unmodified to the next element in the chain.  Forwarding OAM
 * packets unmodified by SFC elements that do not support SFC OAM
 * procedures may be acceptable for a subset of OAM functions, but can
 * result in unexpected outcomes for others, thus it is recommended to
 * analyze the impact of forwarding an OAM packet for all OAM functions
 * prior to enabling this behavior.  The configurable parameter MUST be
 * disabled by default.
 *
 * TTL: Indicates the maximum SFF hops for an SFP.  This field is used
 * for service plane loop detection.  The initial TTL value SHOULD be
 * configurable via the control plane; the configured initial value can
 * be specific to one or more SFPs.  If no initial value is explicitly
 * provided, the default initial TTL value of 63 MUST be used.  Each SFF
 * involved in forwarding an NSH packet MUST decrement the TTL value by
 * 1 prior to NSH forwarding lookup.  Decrementing by 1 from an incoming
 * value of 0 shall result in a TTL value of 63.  The packet MUST NOT be
 * forwarded if TTL is, after decrement, 0.
 *
 * All other flag fields, marked U, are unassigned and available for
 * future use, see Section 11.2.1.  Unassigned bits MUST be set to zero
 * upon origination, and MUST be ignored and preserved unmodified by
 * other NSH supporting elements.  Elements which do not understand the
 * meaning of any of these bits MUST NOT modify their actions based on
 * those unknown bits.
 *
 * Length: The total length, in 4-byte words, of NSH including the Base
 * Header, the Service Path Header, the Fixed Length Context Header or
 * Variable Length Context Header(s).  The length MUST be 0x6 for MD
 * Type equal to 0x1, and MUST be 0x2 or greater for MD Type equal to
 * 0x2.  The length of the NSH header MUST be an integer multiple of 4
 * bytes, thus variable length metadata is always padded out to a
 * multiple of 4 bytes.
 *
 * MD Type: Indicates the format of NSH beyond the mandatory Base Header
 * and the Service Path Header.  MD Type defines the format of the
 * metadata being carried.
 *
 * 0x0 - This is a reserved value.  Implementations SHOULD silently
 * discard packets with MD Type 0x0.
 *
 * 0x1 - This indicates that the format of the header includes a fixed
 * length Context Header (see Figure 4 below).
 *
 * 0x2 - This does not mandate any headers beyond the Base Header and
 * Service Path Header, but may contain optional variable length Context
 * Header(s).  The semantics of the variable length Context Header(s)
 * are not defined in this document.  The format of the optional
 * variable length Context Headers is provided in Section 2.5.1.
 *
 * 0xF - This value is reserved for experimentation and testing, as per
 * [RFC3692].  Implementations not explicitly configured to be part of
 * an experiment SHOULD silently discard packets with MD Type 0xF.
 *
 * Next Protocol: indicates the protocol type of the encapsulated data.
 * NSH does not alter the inner payload, and the semantics on the inner
 * protocol remain unchanged due to NSH service function chaining.
 * Please see the IANA Considerations section below, Section 11.2.5.
 *
 * This document defines the following Next Protocol values:
 *
 * 0x1: IPv4
 * 0x2: IPv6
 * 0x3: Ethernet
 * 0x4: NSH
 * 0x5: MPLS
 * 0xFE: Experiment 1
 * 0xFF: Experiment 2
 *
 * Packets with Next Protocol values not supported SHOULD be silently
 * dropped by default, although an implementation MAY provide a
 * configuration parameter to forward them.  Additionally, an
 * implementation not explicitly configured for a specific experiment
 * [RFC3692] SHOULD silently drop packets with Next Protocol values 0xFE
 * and 0xFF.
 *
 * Service Path Identifier (SPI): Identifies a service path.
 * Participating nodes MUST use this identifier for Service Function
 * Path selection.  The initial classifier MUST set the appropriate SPI
 * for a given classification result.
 *
 * Service Index (SI): Provides location within the SFP.  The initial
 * classifier for a given SFP SHOULD set the SI to 255, however the
 * control plane MAY configure the initial value of SI as appropriate
 * (i.e., taking into account the length of the service function path).
 * The Service Index MUST be decremented by a value of 1 by Service
 * Functions or by SFC Proxy nodes after performing required services
 * and the new decremented SI value MUST be used in the egress packet's
 * NSH.  The initial Classifier MUST send the packet to the first SFF in
 * the identified SFP for forwarding along an SFP.  If re-classification
 * occurs, and that re-classification results in a new SPI, the
 * (re)classifier is, in effect, the initial classifier for the
 * resultant SPI.
 *
 * The SI is used in conjunction the with Service Path Identifier for
 * Service Function Path Selection and for determining the next SFF/SF
 * in the path.  The SI is also valuable when troubleshooting or
 * reporting service paths.  Additionally, while the TTL field is the
 * main mechanism for service plane loop detection, the SI can also be
 * used for detecting service plane loops.
 *
 * When the Base Header specifies MD Type = 0x1, a Fixed Length Context
 * Header (16-bytes) MUST be present immediately following the Service
 * Path Header. The value of a Fixed Length Context
 * Header that carries no metadata MUST be set to zero.
 *
 * When the base header specifies MD Type = 0x2, zero or more Variable
 * Length Context Headers MAY be added, immediately following the
 * Service Path Header (see Figure 5).  Therefore, Length = 0x2,
 * indicates that only the Base Header followed by the Service Path
 * Header are present.  The optional Variable Length Context Headers
 * MUST be of an integer number of 4-bytes.  The base header Length
 * field MUST be used to determine the offset to locate the original
 * packet or frame for SFC nodes that require access to that
 * information.
 *
 * The format of the optional variable length Context Headers
 *
 *  0                   1                   2                   3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |          Metadata Class       |      Type     |U|    Length   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      Variable Metadata                        |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 * Metadata Class (MD Class): Defines the scope of the 'Type' field to
 * provide a hierarchical namespace.  The IANA Considerations
 * Section 11.2.4 defines how the MD Class values can be allocated to
 * standards bodies, vendors, and others.
 *
 * Type: Indicates the explicit type of metadata being carried.  The
 * definition of the Type is the responsibility of the MD Class owner.
 *
 * Unassigned bit: One unassigned bit is available for future use. This
 * bit MUST NOT be set, and MUST be ignored on receipt.
 *
 * Length: Indicates the length of the variable metadata, in bytes.  In
 * case the metadata length is not an integer number of 4-byte words,
 * the sender MUST add pad bytes immediately following the last metadata
 * byte to extend the metadata to an integer number of 4-byte words.
 * The receiver MUST round up the length field to the nearest 4-byte
 * word boundary, to locate and process the next field in the packet.
 * The receiver MUST access only those bytes in the metadata indicated
 * by the length field (i.e., actual number of bytes) and MUST ignore
 * the remaining bytes up to the nearest 4-byte word boundary.  The
 * Length may be 0 or greater.
 *
 * A value of 0 denotes a Context Header without a Variable Metadata
 * field.
 *
 * [0] https://datatracker.ietf.org/doc/draft-ietf-sfc-nsh/
 */

/**
 * struct nsh_md1_ctx - Keeps track of NSH context data
 * @context: NSH Contexts.
 */
struct nsh_md1_ctx {
	__be32 context[4];
};

struct nsh_md2_tlv {
	__be16 md_class;
	u8 type;
	u8 length;
	u8 md_value[];
};

struct nshhdr {
	__be16 ver_flags_ttl_len;
	u8 mdtype;
	u8 np;
	__be32 path_hdr;
	union {
	    struct nsh_md1_ctx md1;
	    struct nsh_md2_tlv md2;
	};
};

/* Masking NSH header fields. */
#define NSH_VER_MASK       0xc000
#define NSH_VER_SHIFT      14
#define NSH_FLAGS_MASK     0x3000
#define NSH_FLAGS_SHIFT    12
#define NSH_TTL_MASK       0x0fc0
#define NSH_TTL_SHIFT      6
#define NSH_LEN_MASK       0x003f
#define NSH_LEN_SHIFT      0

#define NSH_MDTYPE_MASK    0x0f
#define NSH_MDTYPE_SHIFT   0

#define NSH_SPI_MASK       0xffffff00
#define NSH_SPI_SHIFT      8
#define NSH_SI_MASK        0x000000ff
#define NSH_SI_SHIFT       0

/* MD Type Registry. */
#define NSH_M_TYPE1     0x01
#define NSH_M_TYPE2     0x02
#define NSH_M_EXP1      0xFE
#define NSH_M_EXP2      0xFF

/* NSH Base Header Length */
#define NSH_BASE_HDR_LEN  8

/* NSH MD Type 1 header Length. */
#define NSH_M_TYPE1_LEN   24

/* NSH header maximum Length. */
#define NSH_HDR_MAX_LEN 256

/* NSH context headers maximum Length. */
#define NSH_CTX_HDRS_MAX_LEN 248

static inline struct nshhdr *nsh_hdr(struct sk_buff *skb)
{
	return (struct nshhdr *)skb_network_header(skb);
}

static inline u16 nsh_hdr_len(const struct nshhdr *nsh)
{
	return ((ntohs(nsh->ver_flags_ttl_len) & NSH_LEN_MASK)
		>> NSH_LEN_SHIFT) << 2;
}

static inline u8 nsh_get_ver(const struct nshhdr *nsh)
{
	return (ntohs(nsh->ver_flags_ttl_len) & NSH_VER_MASK)
		>> NSH_VER_SHIFT;
}

static inline u8 nsh_get_flags(const struct nshhdr *nsh)
{
	return (ntohs(nsh->ver_flags_ttl_len) & NSH_FLAGS_MASK)
		>> NSH_FLAGS_SHIFT;
}

static inline u8 nsh_get_ttl(const struct nshhdr *nsh)
{
	return (ntohs(nsh->ver_flags_ttl_len) & NSH_TTL_MASK)
		>> NSH_TTL_SHIFT;
}

static inline void __nsh_set_xflag(struct nshhdr *nsh, u16 xflag, u16 xmask)
{
	nsh->ver_flags_ttl_len
		= (nsh->ver_flags_ttl_len & ~htons(xmask)) | htons(xflag);
}

static inline void nsh_set_flags_and_ttl(struct nshhdr *nsh, u8 flags, u8 ttl)
{
	__nsh_set_xflag(nsh, ((flags << NSH_FLAGS_SHIFT) & NSH_FLAGS_MASK) |
			     ((ttl << NSH_TTL_SHIFT) & NSH_TTL_MASK),
			NSH_FLAGS_MASK | NSH_TTL_MASK);
}

static inline void nsh_set_flags_ttl_len(struct nshhdr *nsh, u8 flags,
					 u8 ttl, u8 len)
{
	len = len >> 2;
	__nsh_set_xflag(nsh, ((flags << NSH_FLAGS_SHIFT) & NSH_FLAGS_MASK) |
			     ((ttl << NSH_TTL_SHIFT) & NSH_TTL_MASK) |
			     ((len << NSH_LEN_SHIFT) & NSH_LEN_MASK),
			NSH_FLAGS_MASK | NSH_TTL_MASK | NSH_LEN_MASK);
}

int nsh_push(struct sk_buff *skb, const struct nshhdr *pushed_nh);
int nsh_pop(struct sk_buff *skb);

#endif /* __NET_NSH_H */