--- /dev/null
+#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
+ * @nshc<1-4>: 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);
+}
+
+#endif /* __NET_NSH_H */
projects / openwrt / staging / blogic.git / commitdiff