include/net/nsh.h

7  * Network Service Header:
10  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
12  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
14  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
18  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
27  * discussion of MPLS-related forwarding requirements.
32  * example [I-D.ietf-sfc-oam-framework] for one approach).
34  * The O bit MUST be set for OAM packets and MUST NOT be set for non-OAM
65  * Length: The total length, in 4-byte words, of NSH including the Base
66  * Header, the Service Path Header, the Fixed Length Context Header or
67  * Variable Length Context Header(s).  The length MUST be 0x6 for MD
69  * 0x2.  The length of the NSH header MUST be an integer multiple of 4
73  * MD Type: Indicates the format of NSH beyond the mandatory Base Header
74  * and the Service Path Header.  MD Type defines the format of the
77  * 0x0 - This is a reserved value.  Implementations SHOULD silently
80  * 0x1 - This indicates that the format of the header includes a fixed
81  * length Context Header (see Figure 4 below).
83  * 0x2 - This does not mandate any headers beyond the Base Header and
84  * Service Path Header, but may contain optional variable length Context
85  * Header(s).  The semantics of the variable length Context Header(s)
89  * 0xF - This value is reserved for experimentation and testing, as per
128  * the identified SFP for forwarding along an SFP.  If re-classification
129  * occurs, and that re-classification results in a new SPI, the
140  * When the Base Header specifies MD Type = 0x1, a Fixed Length Context
141  * Header (16-bytes) MUST be present immediately following the Service
142  * Path Header. The value of a Fixed Length Context
143  * Header that carries no metadata MUST be set to zero.
145  * When the base header specifies MD Type = 0x2, zero or more Variable
147  * Service Path Header (see Figure 5).  Therefore, Length = 0x2,
148  * indicates that only the Base Header followed by the Service Path
149  * Header are present.  The optional Variable Length Context Headers
150  * MUST be of an integer number of 4-bytes.  The base header Length
159  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
161  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
163  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
177  * case the metadata length is not an integer number of 4-byte words,
179  * byte to extend the metadata to an integer number of 4-byte words.
180  * The receiver MUST round up the length field to the nearest 4-byte
184  * the remaining bytes up to the nearest 4-byte word boundary.  The
187  * A value of 0 denotes a Context Header without a Variable Metadata
190  * [0] https://datatracker.ietf.org/doc/draft-ietf-sfc-nsh/
194  * struct nsh_md1_ctx - Keeps track of NSH context data
219 /* Masking NSH header fields. */
243 /* NSH Base Header Length */
246 /* NSH MD Type 1 header Length. */
249 /* NSH header maximum Length. */
262 	return ((ntohs(nsh->ver_flags_ttl_len) & NSH_LEN_MASK)  in nsh_hdr_len()
268 	return (ntohs(nsh->ver_flags_ttl_len) & NSH_VER_MASK)  in nsh_get_ver()
274 	return (ntohs(nsh->ver_flags_ttl_len) & NSH_FLAGS_MASK)  in nsh_get_flags()
280 	return (ntohs(nsh->ver_flags_ttl_len) & NSH_TTL_MASK)  in nsh_get_ttl()
286 	nsh->ver_flags_ttl_len  in __nsh_set_xflag()
287 		= (nsh->ver_flags_ttl_len & ~htons(xmask)) | htons(xflag);  in __nsh_set_xflag()