xref: /dpdk/lib/net/rte_ip.h (revision b225783dda7a254fc49bc4d43b8b58f67e03be1d)
1 /* SPDX-License-Identifier: BSD-3-Clause
2  * Copyright(c) 1982, 1986, 1990, 1993
3  *      The Regents of the University of California.
4  * Copyright(c) 2010-2014 Intel Corporation.
5  * Copyright(c) 2014 6WIND S.A.
6  * All rights reserved.
7  */
8 
9 #ifndef _RTE_IP_H_
10 #define _RTE_IP_H_
11 
12 /**
13  * @file
14  *
15  * IP-related defines
16  */
17 
18 #include <stdint.h>
19 
20 #ifdef RTE_EXEC_ENV_WINDOWS
21 #include <ws2tcpip.h>
22 #else
23 #include <sys/socket.h>
24 #include <sys/types.h>
25 #include <netinet/in.h>
26 #include <arpa/inet.h>
27 #include <netinet/ip.h>
28 #include <netinet/ip6.h>
29 #endif
30 
31 #include <rte_byteorder.h>
32 #include <rte_mbuf.h>
33 
34 #ifdef __cplusplus
35 extern "C" {
36 #endif
37 
38 /**
39  * IPv4 Header
40  */
41 struct rte_ipv4_hdr {
42 	uint8_t  version_ihl;		/**< version and header length */
43 	uint8_t  type_of_service;	/**< type of service */
44 	rte_be16_t total_length;	/**< length of packet */
45 	rte_be16_t packet_id;		/**< packet ID */
46 	rte_be16_t fragment_offset;	/**< fragmentation offset */
47 	uint8_t  time_to_live;		/**< time to live */
48 	uint8_t  next_proto_id;		/**< protocol ID */
49 	rte_be16_t hdr_checksum;	/**< header checksum */
50 	rte_be32_t src_addr;		/**< source address */
51 	rte_be32_t dst_addr;		/**< destination address */
52 } __rte_packed;
53 
54 /** Create IPv4 address */
55 #define RTE_IPV4(a, b, c, d) ((uint32_t)(((a) & 0xff) << 24) | \
56 					   (((b) & 0xff) << 16) | \
57 					   (((c) & 0xff) << 8)  | \
58 					   ((d) & 0xff))
59 
60 /** Maximal IPv4 packet length (including a header) */
61 #define RTE_IPV4_MAX_PKT_LEN        65535
62 
63 /** Internet header length mask for version_ihl field */
64 #define RTE_IPV4_HDR_IHL_MASK	(0x0f)
65 /**
66  * Internet header length field multiplier (IHL field specifies overall header
67  * length in number of 4-byte words)
68  */
69 #define RTE_IPV4_IHL_MULTIPLIER	(4)
70 
71 /* Type of Service fields */
72 #define RTE_IPV4_HDR_DSCP_MASK	(0xfc)
73 #define RTE_IPV4_HDR_ECN_MASK	(0x03)
74 #define RTE_IPV4_HDR_ECN_CE	RTE_IPV4_HDR_ECN_MASK
75 
76 /* Fragment Offset * Flags. */
77 #define	RTE_IPV4_HDR_DF_SHIFT	14
78 #define	RTE_IPV4_HDR_MF_SHIFT	13
79 #define	RTE_IPV4_HDR_FO_SHIFT	3
80 
81 #define	RTE_IPV4_HDR_DF_FLAG	(1 << RTE_IPV4_HDR_DF_SHIFT)
82 #define	RTE_IPV4_HDR_MF_FLAG	(1 << RTE_IPV4_HDR_MF_SHIFT)
83 
84 #define	RTE_IPV4_HDR_OFFSET_MASK	((1 << RTE_IPV4_HDR_MF_SHIFT) - 1)
85 
86 #define	RTE_IPV4_HDR_OFFSET_UNITS	8
87 
88 /*
89  * IPv4 address types
90  */
91 #define RTE_IPV4_ANY              ((uint32_t)0x00000000) /**< 0.0.0.0 */
92 #define RTE_IPV4_LOOPBACK         ((uint32_t)0x7f000001) /**< 127.0.0.1 */
93 #define RTE_IPV4_BROADCAST        ((uint32_t)0xe0000000) /**< 224.0.0.0 */
94 #define RTE_IPV4_ALLHOSTS_GROUP   ((uint32_t)0xe0000001) /**< 224.0.0.1 */
95 #define RTE_IPV4_ALLRTRS_GROUP    ((uint32_t)0xe0000002) /**< 224.0.0.2 */
96 #define RTE_IPV4_MAX_LOCAL_GROUP  ((uint32_t)0xe00000ff) /**< 224.0.0.255 */
97 
98 /*
99  * IPv4 Multicast-related macros
100  */
101 #define RTE_IPV4_MIN_MCAST \
102 	RTE_IPV4(224, 0, 0, 0)          /**< Minimal IPv4-multicast address */
103 #define RTE_IPV4_MAX_MCAST \
104 	RTE_IPV4(239, 255, 255, 255)    /**< Maximum IPv4 multicast address */
105 
106 #define RTE_IS_IPV4_MCAST(x) \
107 	((x) >= RTE_IPV4_MIN_MCAST && (x) <= RTE_IPV4_MAX_MCAST)
108 	/**< check if IPv4 address is multicast */
109 
110 /* IPv4 default fields values */
111 #define RTE_IPV4_MIN_IHL    (0x5)
112 #define RTE_IPV4_VHL_DEF    ((IPVERSION << 4) | RTE_IPV4_MIN_IHL)
113 
114 /**
115  * Get the length of an IPv4 header.
116  *
117  * @param ipv4_hdr
118  *   Pointer to the IPv4 header.
119  * @return
120  *   The length of the IPv4 header (with options if present) in bytes.
121  */
122 static inline uint8_t
123 rte_ipv4_hdr_len(const struct rte_ipv4_hdr *ipv4_hdr)
124 {
125 	return (uint8_t)((ipv4_hdr->version_ihl & RTE_IPV4_HDR_IHL_MASK) *
126 		RTE_IPV4_IHL_MULTIPLIER);
127 }
128 
129 /**
130  * @internal Calculate a sum of all words in the buffer.
131  * Helper routine for the rte_raw_cksum().
132  *
133  * @param buf
134  *   Pointer to the buffer.
135  * @param len
136  *   Length of the buffer.
137  * @param sum
138  *   Initial value of the sum.
139  * @return
140  *   sum += Sum of all words in the buffer.
141  */
142 static inline uint32_t
143 __rte_raw_cksum(const void *buf, size_t len, uint32_t sum)
144 {
145 	/* workaround gcc strict-aliasing warning */
146 	uintptr_t ptr = (uintptr_t)buf;
147 	typedef uint16_t __attribute__((__may_alias__)) u16_p;
148 	const u16_p *u16_buf = (const u16_p *)ptr;
149 
150 	while (len >= (sizeof(*u16_buf) * 4)) {
151 		sum += u16_buf[0];
152 		sum += u16_buf[1];
153 		sum += u16_buf[2];
154 		sum += u16_buf[3];
155 		len -= sizeof(*u16_buf) * 4;
156 		u16_buf += 4;
157 	}
158 	while (len >= sizeof(*u16_buf)) {
159 		sum += *u16_buf;
160 		len -= sizeof(*u16_buf);
161 		u16_buf += 1;
162 	}
163 
164 	/* if length is in odd bytes */
165 	if (len == 1) {
166 		uint16_t left = 0;
167 		*(uint8_t *)&left = *(const uint8_t *)u16_buf;
168 		sum += left;
169 	}
170 
171 	return sum;
172 }
173 
174 /**
175  * @internal Reduce a sum to the non-complemented checksum.
176  * Helper routine for the rte_raw_cksum().
177  *
178  * @param sum
179  *   Value of the sum.
180  * @return
181  *   The non-complemented checksum.
182  */
183 static inline uint16_t
184 __rte_raw_cksum_reduce(uint32_t sum)
185 {
186 	sum = ((sum & 0xffff0000) >> 16) + (sum & 0xffff);
187 	sum = ((sum & 0xffff0000) >> 16) + (sum & 0xffff);
188 	return (uint16_t)sum;
189 }
190 
191 /**
192  * Process the non-complemented checksum of a buffer.
193  *
194  * @param buf
195  *   Pointer to the buffer.
196  * @param len
197  *   Length of the buffer.
198  * @return
199  *   The non-complemented checksum.
200  */
201 static inline uint16_t
202 rte_raw_cksum(const void *buf, size_t len)
203 {
204 	uint32_t sum;
205 
206 	sum = __rte_raw_cksum(buf, len, 0);
207 	return __rte_raw_cksum_reduce(sum);
208 }
209 
210 /**
211  * Compute the raw (non complemented) checksum of a packet.
212  *
213  * @param m
214  *   The pointer to the mbuf.
215  * @param off
216  *   The offset in bytes to start the checksum.
217  * @param len
218  *   The length in bytes of the data to checksum.
219  * @param cksum
220  *   A pointer to the checksum, filled on success.
221  * @return
222  *   0 on success, -1 on error (bad length or offset).
223  */
224 static inline int
225 rte_raw_cksum_mbuf(const struct rte_mbuf *m, uint32_t off, uint32_t len,
226 	uint16_t *cksum)
227 {
228 	const struct rte_mbuf *seg;
229 	const char *buf;
230 	uint32_t sum, tmp;
231 	uint32_t seglen, done;
232 
233 	/* easy case: all data in the first segment */
234 	if (off + len <= rte_pktmbuf_data_len(m)) {
235 		*cksum = rte_raw_cksum(rte_pktmbuf_mtod_offset(m,
236 				const char *, off), len);
237 		return 0;
238 	}
239 
240 	if (unlikely(off + len > rte_pktmbuf_pkt_len(m)))
241 		return -1; /* invalid params, return a dummy value */
242 
243 	/* else browse the segment to find offset */
244 	seglen = 0;
245 	for (seg = m; seg != NULL; seg = seg->next) {
246 		seglen = rte_pktmbuf_data_len(seg);
247 		if (off < seglen)
248 			break;
249 		off -= seglen;
250 	}
251 	RTE_ASSERT(seg != NULL);
252 	if (seg == NULL)
253 		return -1;
254 	seglen -= off;
255 	buf = rte_pktmbuf_mtod_offset(seg, const char *, off);
256 	if (seglen >= len) {
257 		/* all in one segment */
258 		*cksum = rte_raw_cksum(buf, len);
259 		return 0;
260 	}
261 
262 	/* hard case: process checksum of several segments */
263 	sum = 0;
264 	done = 0;
265 	for (;;) {
266 		tmp = __rte_raw_cksum(buf, seglen, 0);
267 		if (done & 1)
268 			tmp = rte_bswap16((uint16_t)tmp);
269 		sum += tmp;
270 		done += seglen;
271 		if (done == len)
272 			break;
273 		seg = seg->next;
274 		buf = rte_pktmbuf_mtod(seg, const char *);
275 		seglen = rte_pktmbuf_data_len(seg);
276 		if (seglen > len - done)
277 			seglen = len - done;
278 	}
279 
280 	*cksum = __rte_raw_cksum_reduce(sum);
281 	return 0;
282 }
283 
284 /**
285  * Process the IPv4 checksum of an IPv4 header.
286  *
287  * The checksum field must be set to 0 by the caller.
288  *
289  * @param ipv4_hdr
290  *   The pointer to the contiguous IPv4 header.
291  * @return
292  *   The complemented checksum to set in the IP packet.
293  */
294 static inline uint16_t
295 rte_ipv4_cksum(const struct rte_ipv4_hdr *ipv4_hdr)
296 {
297 	uint16_t cksum;
298 	cksum = rte_raw_cksum(ipv4_hdr, rte_ipv4_hdr_len(ipv4_hdr));
299 	return (uint16_t)~cksum;
300 }
301 
302 /**
303  * Process the pseudo-header checksum of an IPv4 header.
304  *
305  * The checksum field must be set to 0 by the caller.
306  *
307  * Depending on the ol_flags, the pseudo-header checksum expected by the
308  * drivers is not the same. For instance, when TSO is enabled, the IP
309  * payload length must not be included in the packet.
310  *
311  * When ol_flags is 0, it computes the standard pseudo-header checksum.
312  *
313  * @param ipv4_hdr
314  *   The pointer to the contiguous IPv4 header.
315  * @param ol_flags
316  *   The ol_flags of the associated mbuf.
317  * @return
318  *   The non-complemented checksum to set in the L4 header.
319  */
320 static inline uint16_t
321 rte_ipv4_phdr_cksum(const struct rte_ipv4_hdr *ipv4_hdr, uint64_t ol_flags)
322 {
323 	struct ipv4_psd_header {
324 		uint32_t src_addr; /* IP address of source host. */
325 		uint32_t dst_addr; /* IP address of destination host. */
326 		uint8_t  zero;     /* zero. */
327 		uint8_t  proto;    /* L4 protocol type. */
328 		uint16_t len;      /* L4 length. */
329 	} psd_hdr;
330 
331 	uint32_t l3_len;
332 
333 	psd_hdr.src_addr = ipv4_hdr->src_addr;
334 	psd_hdr.dst_addr = ipv4_hdr->dst_addr;
335 	psd_hdr.zero = 0;
336 	psd_hdr.proto = ipv4_hdr->next_proto_id;
337 	if (ol_flags & PKT_TX_TCP_SEG) {
338 		psd_hdr.len = 0;
339 	} else {
340 		l3_len = rte_be_to_cpu_16(ipv4_hdr->total_length);
341 		psd_hdr.len = rte_cpu_to_be_16((uint16_t)(l3_len -
342 			rte_ipv4_hdr_len(ipv4_hdr)));
343 	}
344 	return rte_raw_cksum(&psd_hdr, sizeof(psd_hdr));
345 }
346 
347 /**
348  * @internal Calculate the non-complemented IPv4 L4 checksum
349  */
350 static inline uint16_t
351 __rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr)
352 {
353 	uint32_t cksum;
354 	uint32_t l3_len, l4_len;
355 	uint8_t ip_hdr_len;
356 
357 	ip_hdr_len = rte_ipv4_hdr_len(ipv4_hdr);
358 	l3_len = rte_be_to_cpu_16(ipv4_hdr->total_length);
359 	if (l3_len < ip_hdr_len)
360 		return 0;
361 
362 	l4_len = l3_len - ip_hdr_len;
363 
364 	cksum = rte_raw_cksum(l4_hdr, l4_len);
365 	cksum += rte_ipv4_phdr_cksum(ipv4_hdr, 0);
366 
367 	cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff);
368 
369 	return (uint16_t)cksum;
370 }
371 
372 /**
373  * Process the IPv4 UDP or TCP checksum.
374  *
375  * The IP and layer 4 checksum must be set to 0 in the packet by
376  * the caller.
377  *
378  * @param ipv4_hdr
379  *   The pointer to the contiguous IPv4 header.
380  * @param l4_hdr
381  *   The pointer to the beginning of the L4 header.
382  * @return
383  *   The complemented checksum to set in the IP packet.
384  */
385 static inline uint16_t
386 rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr)
387 {
388 	uint16_t cksum = __rte_ipv4_udptcp_cksum(ipv4_hdr, l4_hdr);
389 
390 	cksum = ~cksum;
391 
392 	/*
393 	 * Per RFC 768: If the computed checksum is zero for UDP,
394 	 * it is transmitted as all ones
395 	 * (the equivalent in one's complement arithmetic).
396 	 */
397 	if (cksum == 0 && ipv4_hdr->next_proto_id == IPPROTO_UDP)
398 		cksum = 0xffff;
399 
400 	return cksum;
401 }
402 
403 /**
404  * Validate the IPv4 UDP or TCP checksum.
405  *
406  * In case of UDP, the caller must first check if udp_hdr->dgram_cksum is 0
407  * (i.e. no checksum).
408  *
409  * @param ipv4_hdr
410  *   The pointer to the contiguous IPv4 header.
411  * @param l4_hdr
412  *   The pointer to the beginning of the L4 header.
413  * @return
414  *   Return 0 if the checksum is correct, else -1.
415  */
416 __rte_experimental
417 static inline int
418 rte_ipv4_udptcp_cksum_verify(const struct rte_ipv4_hdr *ipv4_hdr,
419 			     const void *l4_hdr)
420 {
421 	uint16_t cksum = __rte_ipv4_udptcp_cksum(ipv4_hdr, l4_hdr);
422 
423 	if (cksum != 0xffff)
424 		return -1;
425 
426 	return 0;
427 }
428 
429 /**
430  * IPv6 Header
431  */
432 struct rte_ipv6_hdr {
433 	rte_be32_t vtc_flow;	/**< IP version, traffic class & flow label. */
434 	rte_be16_t payload_len;	/**< IP payload size, including ext. headers */
435 	uint8_t  proto;		/**< Protocol, next header. */
436 	uint8_t  hop_limits;	/**< Hop limits. */
437 	uint8_t  src_addr[16];	/**< IP address of source host. */
438 	uint8_t  dst_addr[16];	/**< IP address of destination host(s). */
439 } __rte_packed;
440 
441 /* IPv6 vtc_flow: IPv / TC / flow_label */
442 #define RTE_IPV6_HDR_FL_SHIFT 0
443 #define RTE_IPV6_HDR_TC_SHIFT 20
444 #define RTE_IPV6_HDR_FL_MASK	((1u << RTE_IPV6_HDR_TC_SHIFT) - 1)
445 #define RTE_IPV6_HDR_TC_MASK	(0xff << RTE_IPV6_HDR_TC_SHIFT)
446 #define RTE_IPV6_HDR_DSCP_MASK	(0xfc << RTE_IPV6_HDR_TC_SHIFT)
447 #define RTE_IPV6_HDR_ECN_MASK	(0x03 << RTE_IPV6_HDR_TC_SHIFT)
448 #define RTE_IPV6_HDR_ECN_CE	RTE_IPV6_HDR_ECN_MASK
449 
450 #define RTE_IPV6_MIN_MTU 1280 /**< Minimum MTU for IPv6, see RFC 8200. */
451 
452 /**
453  * Process the pseudo-header checksum of an IPv6 header.
454  *
455  * Depending on the ol_flags, the pseudo-header checksum expected by the
456  * drivers is not the same. For instance, when TSO is enabled, the IPv6
457  * payload length must not be included in the packet.
458  *
459  * When ol_flags is 0, it computes the standard pseudo-header checksum.
460  *
461  * @param ipv6_hdr
462  *   The pointer to the contiguous IPv6 header.
463  * @param ol_flags
464  *   The ol_flags of the associated mbuf.
465  * @return
466  *   The non-complemented checksum to set in the L4 header.
467  */
468 static inline uint16_t
469 rte_ipv6_phdr_cksum(const struct rte_ipv6_hdr *ipv6_hdr, uint64_t ol_flags)
470 {
471 	uint32_t sum;
472 	struct {
473 		rte_be32_t len;   /* L4 length. */
474 		rte_be32_t proto; /* L4 protocol - top 3 bytes must be zero */
475 	} psd_hdr;
476 
477 	psd_hdr.proto = (uint32_t)(ipv6_hdr->proto << 24);
478 	if (ol_flags & PKT_TX_TCP_SEG) {
479 		psd_hdr.len = 0;
480 	} else {
481 		psd_hdr.len = ipv6_hdr->payload_len;
482 	}
483 
484 	sum = __rte_raw_cksum(ipv6_hdr->src_addr,
485 		sizeof(ipv6_hdr->src_addr) + sizeof(ipv6_hdr->dst_addr),
486 		0);
487 	sum = __rte_raw_cksum(&psd_hdr, sizeof(psd_hdr), sum);
488 	return __rte_raw_cksum_reduce(sum);
489 }
490 
491 /**
492  * @internal Calculate the non-complemented IPv4 L4 checksum
493  */
494 static inline uint16_t
495 __rte_ipv6_udptcp_cksum(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr)
496 {
497 	uint32_t cksum;
498 	uint32_t l4_len;
499 
500 	l4_len = rte_be_to_cpu_16(ipv6_hdr->payload_len);
501 
502 	cksum = rte_raw_cksum(l4_hdr, l4_len);
503 	cksum += rte_ipv6_phdr_cksum(ipv6_hdr, 0);
504 
505 	cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff);
506 
507 	return (uint16_t)cksum;
508 }
509 
510 /**
511  * Process the IPv6 UDP or TCP checksum.
512  *
513  * The IPv4 header should not contains options. The layer 4 checksum
514  * must be set to 0 in the packet by the caller.
515  *
516  * @param ipv6_hdr
517  *   The pointer to the contiguous IPv6 header.
518  * @param l4_hdr
519  *   The pointer to the beginning of the L4 header.
520  * @return
521  *   The complemented checksum to set in the IP packet.
522  */
523 static inline uint16_t
524 rte_ipv6_udptcp_cksum(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr)
525 {
526 	uint16_t cksum = __rte_ipv6_udptcp_cksum(ipv6_hdr, l4_hdr);
527 
528 	cksum = ~cksum;
529 
530 	/*
531 	 * Per RFC 768: If the computed checksum is zero for UDP,
532 	 * it is transmitted as all ones
533 	 * (the equivalent in one's complement arithmetic).
534 	 */
535 	if (cksum == 0 && ipv6_hdr->proto == IPPROTO_UDP)
536 		cksum = 0xffff;
537 
538 	return cksum;
539 }
540 
541 /**
542  * Validate the IPv6 UDP or TCP checksum.
543  *
544  * In case of UDP, the caller must first check if udp_hdr->dgram_cksum is 0:
545  * this is either invalid or means no checksum in some situations. See 8.1
546  * (Upper-Layer Checksums) in RFC 8200.
547  *
548  * @param ipv6_hdr
549  *   The pointer to the contiguous IPv6 header.
550  * @param l4_hdr
551  *   The pointer to the beginning of the L4 header.
552  * @return
553  *   Return 0 if the checksum is correct, else -1.
554  */
555 __rte_experimental
556 static inline int
557 rte_ipv6_udptcp_cksum_verify(const struct rte_ipv6_hdr *ipv6_hdr,
558 			     const void *l4_hdr)
559 {
560 	uint16_t cksum = __rte_ipv6_udptcp_cksum(ipv6_hdr, l4_hdr);
561 
562 	if (cksum != 0xffff)
563 		return -1;
564 
565 	return 0;
566 }
567 
568 /** IPv6 fragment extension header. */
569 #define	RTE_IPV6_EHDR_MF_SHIFT	0
570 #define	RTE_IPV6_EHDR_MF_MASK	1
571 #define	RTE_IPV6_EHDR_FO_SHIFT	3
572 #define	RTE_IPV6_EHDR_FO_MASK	(~((1 << RTE_IPV6_EHDR_FO_SHIFT) - 1))
573 #define	RTE_IPV6_EHDR_FO_ALIGN	(1 << RTE_IPV6_EHDR_FO_SHIFT)
574 
575 #define RTE_IPV6_FRAG_USED_MASK	(RTE_IPV6_EHDR_MF_MASK | RTE_IPV6_EHDR_FO_MASK)
576 
577 #define RTE_IPV6_GET_MF(x)	((x) & RTE_IPV6_EHDR_MF_MASK)
578 #define RTE_IPV6_GET_FO(x)	((x) >> RTE_IPV6_EHDR_FO_SHIFT)
579 
580 #define RTE_IPV6_SET_FRAG_DATA(fo, mf)	\
581 	(((fo) & RTE_IPV6_EHDR_FO_MASK) | ((mf) & RTE_IPV6_EHDR_MF_MASK))
582 
583 struct rte_ipv6_fragment_ext {
584 	uint8_t next_header;	/**< Next header type */
585 	uint8_t reserved;	/**< Reserved */
586 	rte_be16_t frag_data;	/**< All fragmentation data */
587 	rte_be32_t id;		/**< Packet ID */
588 } __rte_packed;
589 
590 /* IPv6 fragment extension header size */
591 #define RTE_IPV6_FRAG_HDR_SIZE	sizeof(struct rte_ipv6_fragment_ext)
592 
593 /**
594  * Parse next IPv6 header extension
595  *
596  * This function checks if proto number is an IPv6 extensions and parses its
597  * data if so, providing information on next header and extension length.
598  *
599  * @param p
600  *   Pointer to an extension raw data.
601  * @param proto
602  *   Protocol number extracted from the "next header" field from
603  *   the IPv6 header or the previous extension.
604  * @param ext_len
605  *   Extension data length.
606  * @return
607  *   next protocol number if proto is an IPv6 extension, -EINVAL otherwise
608  */
609 __rte_experimental
610 static inline int
611 rte_ipv6_get_next_ext(const uint8_t *p, int proto, size_t *ext_len)
612 {
613 	int next_proto;
614 
615 	switch (proto) {
616 	case IPPROTO_AH:
617 		next_proto = *p++;
618 		*ext_len = (*p + 2) * sizeof(uint32_t);
619 		break;
620 
621 	case IPPROTO_HOPOPTS:
622 	case IPPROTO_ROUTING:
623 	case IPPROTO_DSTOPTS:
624 		next_proto = *p++;
625 		*ext_len = (*p + 1) * sizeof(uint64_t);
626 		break;
627 
628 	case IPPROTO_FRAGMENT:
629 		next_proto = *p;
630 		*ext_len = RTE_IPV6_FRAG_HDR_SIZE;
631 		break;
632 
633 	default:
634 		return -EINVAL;
635 	}
636 
637 	return next_proto;
638 }
639 
640 #ifdef __cplusplus
641 }
642 #endif
643 
644 #endif /* _RTE_IP_H_ */
645