xref: /linux/include/net/ipv6.h (revision c537b994505099b7197e7d3125b942ecbcc51eb6)
1 /*
2  *	Linux INET6 implementation
3  *
4  *	Authors:
5  *	Pedro Roque		<roque@di.fc.ul.pt>
6  *
7  *	$Id: ipv6.h,v 1.1 2002/05/20 15:13:07 jgrimm Exp $
8  *
9  *	This program is free software; you can redistribute it and/or
10  *      modify it under the terms of the GNU General Public License
11  *      as published by the Free Software Foundation; either version
12  *      2 of the License, or (at your option) any later version.
13  */
14 
15 #ifndef _NET_IPV6_H
16 #define _NET_IPV6_H
17 
18 #include <linux/ipv6.h>
19 #include <linux/hardirq.h>
20 #include <net/ndisc.h>
21 #include <net/flow.h>
22 #include <net/snmp.h>
23 
24 #define SIN6_LEN_RFC2133	24
25 
26 #define IPV6_MAXPLEN		65535
27 
28 /*
29  *	NextHeader field of IPv6 header
30  */
31 
32 #define NEXTHDR_HOP		0	/* Hop-by-hop option header. */
33 #define NEXTHDR_TCP		6	/* TCP segment. */
34 #define NEXTHDR_UDP		17	/* UDP message. */
35 #define NEXTHDR_IPV6		41	/* IPv6 in IPv6 */
36 #define NEXTHDR_ROUTING		43	/* Routing header. */
37 #define NEXTHDR_FRAGMENT	44	/* Fragmentation/reassembly header. */
38 #define NEXTHDR_ESP		50	/* Encapsulating security payload. */
39 #define NEXTHDR_AUTH		51	/* Authentication header. */
40 #define NEXTHDR_ICMP		58	/* ICMP for IPv6. */
41 #define NEXTHDR_NONE		59	/* No next header */
42 #define NEXTHDR_DEST		60	/* Destination options header. */
43 #define NEXTHDR_MOBILITY	135	/* Mobility header. */
44 
45 #define NEXTHDR_MAX		255
46 
47 
48 
49 #define IPV6_DEFAULT_HOPLIMIT   64
50 #define IPV6_DEFAULT_MCASTHOPS	1
51 
52 /*
53  *	Addr type
54  *
55  *	type	-	unicast | multicast
56  *	scope	-	local	| site	    | global
57  *	v4	-	compat
58  *	v4mapped
59  *	any
60  *	loopback
61  */
62 
63 #define IPV6_ADDR_ANY		0x0000U
64 
65 #define IPV6_ADDR_UNICAST      	0x0001U
66 #define IPV6_ADDR_MULTICAST    	0x0002U
67 
68 #define IPV6_ADDR_LOOPBACK	0x0010U
69 #define IPV6_ADDR_LINKLOCAL	0x0020U
70 #define IPV6_ADDR_SITELOCAL	0x0040U
71 
72 #define IPV6_ADDR_COMPATv4	0x0080U
73 
74 #define IPV6_ADDR_SCOPE_MASK	0x00f0U
75 
76 #define IPV6_ADDR_MAPPED	0x1000U
77 #define IPV6_ADDR_RESERVED	0x2000U	/* reserved address space */
78 
79 /*
80  *	Addr scopes
81  */
82 #ifdef __KERNEL__
83 #define IPV6_ADDR_MC_SCOPE(a)	\
84 	((a)->s6_addr[1] & 0x0f)	/* nonstandard */
85 #define __IPV6_ADDR_SCOPE_INVALID	-1
86 #endif
87 #define IPV6_ADDR_SCOPE_NODELOCAL	0x01
88 #define IPV6_ADDR_SCOPE_LINKLOCAL	0x02
89 #define IPV6_ADDR_SCOPE_SITELOCAL	0x05
90 #define IPV6_ADDR_SCOPE_ORGLOCAL	0x08
91 #define IPV6_ADDR_SCOPE_GLOBAL		0x0e
92 
93 /*
94  *	fragmentation header
95  */
96 
97 struct frag_hdr {
98 	__u8	nexthdr;
99 	__u8	reserved;
100 	__be16	frag_off;
101 	__be32	identification;
102 };
103 
104 #define	IP6_MF	0x0001
105 
106 #ifdef __KERNEL__
107 
108 #include <net/sock.h>
109 
110 /* sysctls */
111 extern int sysctl_ipv6_bindv6only;
112 extern int sysctl_mld_max_msf;
113 
114 /* MIBs */
115 DECLARE_SNMP_STAT(struct ipstats_mib, ipv6_statistics);
116 #define IP6_INC_STATS(idev,field)		({			\
117 	struct inet6_dev *_idev = (idev);				\
118 	if (likely(_idev != NULL))					\
119 		SNMP_INC_STATS(_idev->stats.ipv6, field);		\
120 	SNMP_INC_STATS(ipv6_statistics, field);				\
121 })
122 #define IP6_INC_STATS_BH(idev,field)		({			\
123 	struct inet6_dev *_idev = (idev);				\
124 	if (likely(_idev != NULL))					\
125 		SNMP_INC_STATS_BH(_idev->stats.ipv6, field);		\
126 	SNMP_INC_STATS_BH(ipv6_statistics, field);			\
127 })
128 #define IP6_INC_STATS_USER(idev,field)		({			\
129 	struct inet6_dev *_idev = (idev);				\
130 	if (likely(_idev != NULL))					\
131 		SNMP_INC_STATS_USER(_idev->stats.ipv6, field);		\
132 	SNMP_INC_STATS_USER(ipv6_statistics, field);			\
133 })
134 DECLARE_SNMP_STAT(struct icmpv6_mib, icmpv6_statistics);
135 #define ICMP6_INC_STATS(idev, field)		({			\
136 	struct inet6_dev *_idev = (idev);				\
137 	if (likely(_idev != NULL))					\
138 		SNMP_INC_STATS(idev->stats.icmpv6, field); 		\
139 	SNMP_INC_STATS(icmpv6_statistics, field);			\
140 })
141 #define ICMP6_INC_STATS_BH(idev, field)		({			\
142 	struct inet6_dev *_idev = (idev);				\
143 	if (likely(_idev != NULL))					\
144 		SNMP_INC_STATS_BH((_idev)->stats.icmpv6, field);	\
145 	SNMP_INC_STATS_BH(icmpv6_statistics, field);			\
146 })
147 #define ICMP6_INC_STATS_USER(idev, field) 	({			\
148 	struct inet6_dev *_idev = (idev);				\
149 	if (likely(_idev != NULL))					\
150 		SNMP_INC_STATS_USER(_idev->stats.icmpv6, field);	\
151 	SNMP_INC_STATS_USER(icmpv6_statistics, field);			\
152 })
153 #define ICMP6_INC_STATS_OFFSET_BH(idev, field, offset)	({			\
154 	struct inet6_dev *_idev = idev;						\
155 	__typeof__(offset) _offset = (offset);					\
156 	if (likely(_idev != NULL))						\
157 		SNMP_INC_STATS_OFFSET_BH(_idev->stats.icmpv6, field, _offset);	\
158 	SNMP_INC_STATS_OFFSET_BH(icmpv6_statistics, field, _offset);    	\
159 })
160 DECLARE_SNMP_STAT(struct udp_mib, udp_stats_in6);
161 DECLARE_SNMP_STAT(struct udp_mib, udplite_stats_in6);
162 #define UDP6_INC_STATS_BH(field, is_udplite) 			      do  {  \
163 	if (is_udplite) SNMP_INC_STATS_BH(udplite_stats_in6, field);         \
164 	else		SNMP_INC_STATS_BH(udp_stats_in6, field);    } while(0)
165 #define UDP6_INC_STATS_USER(field, is_udplite)			       do {    \
166 	if (is_udplite) SNMP_INC_STATS_USER(udplite_stats_in6, field);         \
167 	else		SNMP_INC_STATS_USER(udp_stats_in6, field);    } while(0)
168 
169 int snmp6_register_dev(struct inet6_dev *idev);
170 int snmp6_unregister_dev(struct inet6_dev *idev);
171 int snmp6_alloc_dev(struct inet6_dev *idev);
172 int snmp6_free_dev(struct inet6_dev *idev);
173 int snmp6_mib_init(void *ptr[2], size_t mibsize, size_t mibalign);
174 void snmp6_mib_free(void *ptr[2]);
175 
176 struct ip6_ra_chain
177 {
178 	struct ip6_ra_chain	*next;
179 	struct sock		*sk;
180 	int			sel;
181 	void			(*destructor)(struct sock *);
182 };
183 
184 extern struct ip6_ra_chain	*ip6_ra_chain;
185 extern rwlock_t ip6_ra_lock;
186 
187 /*
188    This structure is prepared by protocol, when parsing
189    ancillary data and passed to IPv6.
190  */
191 
192 struct ipv6_txoptions
193 {
194 	/* Length of this structure */
195 	int			tot_len;
196 
197 	/* length of extension headers   */
198 
199 	__u16			opt_flen;	/* after fragment hdr */
200 	__u16			opt_nflen;	/* before fragment hdr */
201 
202 	struct ipv6_opt_hdr	*hopopt;
203 	struct ipv6_opt_hdr	*dst0opt;
204 	struct ipv6_rt_hdr	*srcrt;	/* Routing Header */
205 	struct ipv6_opt_hdr	*dst1opt;
206 
207 	/* Option buffer, as read by IPV6_PKTOPTIONS, starts here. */
208 };
209 
210 struct ip6_flowlabel
211 {
212 	struct ip6_flowlabel	*next;
213 	__be32			label;
214 	struct in6_addr		dst;
215 	struct ipv6_txoptions	*opt;
216 	atomic_t		users;
217 	unsigned long		linger;
218 	u8			share;
219 	u32			owner;
220 	unsigned long		lastuse;
221 	unsigned long		expires;
222 };
223 
224 #define IPV6_FLOWINFO_MASK	__constant_htonl(0x0FFFFFFF)
225 #define IPV6_FLOWLABEL_MASK	__constant_htonl(0x000FFFFF)
226 
227 struct ipv6_fl_socklist
228 {
229 	struct ipv6_fl_socklist	*next;
230 	struct ip6_flowlabel	*fl;
231 };
232 
233 extern struct ip6_flowlabel	*fl6_sock_lookup(struct sock *sk, __be32 label);
234 extern struct ipv6_txoptions	*fl6_merge_options(struct ipv6_txoptions * opt_space,
235 						   struct ip6_flowlabel * fl,
236 						   struct ipv6_txoptions * fopt);
237 extern void			fl6_free_socklist(struct sock *sk);
238 extern int			ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen);
239 extern void			ip6_flowlabel_init(void);
240 extern void			ip6_flowlabel_cleanup(void);
241 
242 static inline void fl6_sock_release(struct ip6_flowlabel *fl)
243 {
244 	if (fl)
245 		atomic_dec(&fl->users);
246 }
247 
248 extern int 			ip6_ra_control(struct sock *sk, int sel,
249 					       void (*destructor)(struct sock *));
250 
251 
252 extern int			ipv6_parse_hopopts(struct sk_buff **skbp);
253 
254 extern struct ipv6_txoptions *  ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt);
255 extern struct ipv6_txoptions *	ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
256 						   int newtype,
257 						   struct ipv6_opt_hdr __user *newopt,
258 						   int newoptlen);
259 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
260 					  struct ipv6_txoptions *opt);
261 
262 extern int ipv6_opt_accepted(struct sock *sk, struct sk_buff *skb);
263 
264 extern int ip6_frag_nqueues;
265 extern atomic_t ip6_frag_mem;
266 
267 #define IPV6_FRAG_TIMEOUT	(60*HZ)		/* 60 seconds */
268 
269 /*
270  *	Function prototype for build_xmit
271  */
272 
273 typedef int		(*inet_getfrag_t) (const void *data,
274 					   struct in6_addr *addr,
275 					   char *,
276 					   unsigned int, unsigned int);
277 
278 extern int __ipv6_addr_type(const struct in6_addr *addr);
279 static inline int ipv6_addr_type(const struct in6_addr *addr)
280 {
281 	return __ipv6_addr_type(addr) & 0xffff;
282 }
283 
284 static inline int ipv6_addr_scope(const struct in6_addr *addr)
285 {
286 	return __ipv6_addr_type(addr) & IPV6_ADDR_SCOPE_MASK;
287 }
288 
289 static inline int __ipv6_addr_src_scope(int type)
290 {
291 	return (type == IPV6_ADDR_ANY ? __IPV6_ADDR_SCOPE_INVALID : (type >> 16));
292 }
293 
294 static inline int ipv6_addr_src_scope(const struct in6_addr *addr)
295 {
296 	return __ipv6_addr_src_scope(__ipv6_addr_type(addr));
297 }
298 
299 static inline int ipv6_addr_cmp(const struct in6_addr *a1, const struct in6_addr *a2)
300 {
301 	return memcmp((const void *) a1, (const void *) a2, sizeof(struct in6_addr));
302 }
303 
304 static inline int
305 ipv6_masked_addr_cmp(const struct in6_addr *a1, const struct in6_addr *m,
306 		     const struct in6_addr *a2)
307 {
308 	unsigned int i;
309 
310 	for (i = 0; i < 4; i++)
311 		if ((a1->s6_addr32[i] ^ a2->s6_addr32[i]) & m->s6_addr32[i])
312 			return 1;
313 	return 0;
314 }
315 
316 static inline void ipv6_addr_copy(struct in6_addr *a1, const struct in6_addr *a2)
317 {
318 	memcpy((void *) a1, (const void *) a2, sizeof(struct in6_addr));
319 }
320 
321 static inline void ipv6_addr_prefix(struct in6_addr *pfx,
322 				    const struct in6_addr *addr,
323 				    int plen)
324 {
325 	/* caller must guarantee 0 <= plen <= 128 */
326 	int o = plen >> 3,
327 	    b = plen & 0x7;
328 
329 	memcpy(pfx->s6_addr, addr, o);
330 	if (b != 0) {
331 		pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b);
332 		o++;
333 	}
334 	if (o < 16)
335 		memset(pfx->s6_addr + o, 0, 16 - o);
336 }
337 
338 #ifndef __HAVE_ARCH_ADDR_SET
339 static inline void ipv6_addr_set(struct in6_addr *addr,
340 				     __be32 w1, __be32 w2,
341 				     __be32 w3, __be32 w4)
342 {
343 	addr->s6_addr32[0] = w1;
344 	addr->s6_addr32[1] = w2;
345 	addr->s6_addr32[2] = w3;
346 	addr->s6_addr32[3] = w4;
347 }
348 #endif
349 
350 static inline int ipv6_addr_equal(const struct in6_addr *a1,
351 				  const struct in6_addr *a2)
352 {
353 	return (a1->s6_addr32[0] == a2->s6_addr32[0] &&
354 		a1->s6_addr32[1] == a2->s6_addr32[1] &&
355 		a1->s6_addr32[2] == a2->s6_addr32[2] &&
356 		a1->s6_addr32[3] == a2->s6_addr32[3]);
357 }
358 
359 static inline int __ipv6_prefix_equal(const __be32 *a1, const __be32 *a2,
360 				      unsigned int prefixlen)
361 {
362 	unsigned pdw, pbi;
363 
364 	/* check complete u32 in prefix */
365 	pdw = prefixlen >> 5;
366 	if (pdw && memcmp(a1, a2, pdw << 2))
367 		return 0;
368 
369 	/* check incomplete u32 in prefix */
370 	pbi = prefixlen & 0x1f;
371 	if (pbi && ((a1[pdw] ^ a2[pdw]) & htonl((0xffffffff) << (32 - pbi))))
372 		return 0;
373 
374 	return 1;
375 }
376 
377 static inline int ipv6_prefix_equal(const struct in6_addr *a1,
378 				    const struct in6_addr *a2,
379 				    unsigned int prefixlen)
380 {
381 	return __ipv6_prefix_equal(a1->s6_addr32, a2->s6_addr32,
382 				   prefixlen);
383 }
384 
385 static inline int ipv6_addr_any(const struct in6_addr *a)
386 {
387 	return ((a->s6_addr32[0] | a->s6_addr32[1] |
388 		 a->s6_addr32[2] | a->s6_addr32[3] ) == 0);
389 }
390 
391 /*
392  * find the first different bit between two addresses
393  * length of address must be a multiple of 32bits
394  */
395 static inline int __ipv6_addr_diff(const void *token1, const void *token2, int addrlen)
396 {
397 	const __be32 *a1 = token1, *a2 = token2;
398 	int i;
399 
400 	addrlen >>= 2;
401 
402 	for (i = 0; i < addrlen; i++) {
403 		__be32 xb = a1[i] ^ a2[i];
404 		if (xb)
405 			return i * 32 + 32 - fls(ntohl(xb));
406 	}
407 
408 	/*
409 	 *	we should *never* get to this point since that
410 	 *	would mean the addrs are equal
411 	 *
412 	 *	However, we do get to it 8) And exacly, when
413 	 *	addresses are equal 8)
414 	 *
415 	 *	ip route add 1111::/128 via ...
416 	 *	ip route add 1111::/64 via ...
417 	 *	and we are here.
418 	 *
419 	 *	Ideally, this function should stop comparison
420 	 *	at prefix length. It does not, but it is still OK,
421 	 *	if returned value is greater than prefix length.
422 	 *					--ANK (980803)
423 	 */
424 	return (addrlen << 5);
425 }
426 
427 static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_addr *a2)
428 {
429 	return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));
430 }
431 
432 /*
433  *	Prototypes exported by ipv6
434  */
435 
436 /*
437  *	rcv function (called from netdevice level)
438  */
439 
440 extern int			ipv6_rcv(struct sk_buff *skb,
441 					 struct net_device *dev,
442 					 struct packet_type *pt,
443 					 struct net_device *orig_dev);
444 
445 extern int			ip6_rcv_finish(struct sk_buff *skb);
446 
447 /*
448  *	upper-layer output functions
449  */
450 extern int			ip6_xmit(struct sock *sk,
451 					 struct sk_buff *skb,
452 					 struct flowi *fl,
453 					 struct ipv6_txoptions *opt,
454 					 int ipfragok);
455 
456 extern int			ip6_nd_hdr(struct sock *sk,
457 					   struct sk_buff *skb,
458 					   struct net_device *dev,
459 					   struct in6_addr *saddr,
460 					   struct in6_addr *daddr,
461 					   int proto, int len);
462 
463 extern int			ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr);
464 
465 extern int			ip6_append_data(struct sock *sk,
466 						int getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb),
467 		    				void *from,
468 						int length,
469 						int transhdrlen,
470 		      				int hlimit,
471 		      				int tclass,
472 						struct ipv6_txoptions *opt,
473 						struct flowi *fl,
474 						struct rt6_info *rt,
475 						unsigned int flags);
476 
477 extern int			ip6_push_pending_frames(struct sock *sk);
478 
479 extern void			ip6_flush_pending_frames(struct sock *sk);
480 
481 extern int			ip6_dst_lookup(struct sock *sk,
482 					       struct dst_entry **dst,
483 					       struct flowi *fl);
484 extern int			ip6_sk_dst_lookup(struct sock *sk,
485 						  struct dst_entry **dst,
486 						  struct flowi *fl);
487 
488 /*
489  *	skb processing functions
490  */
491 
492 extern int			ip6_output(struct sk_buff *skb);
493 extern int			ip6_forward(struct sk_buff *skb);
494 extern int			ip6_input(struct sk_buff *skb);
495 extern int			ip6_mc_input(struct sk_buff *skb);
496 
497 /*
498  *	Extension header (options) processing
499  */
500 
501 extern u8 *			ipv6_build_nfrag_opts(struct sk_buff *skb,
502 						      u8 *prev_hdr,
503 						      struct ipv6_txoptions *opt,
504 						      struct in6_addr *daddr,
505 						      u32 jumbolen);
506 extern u8 *			ipv6_build_frag_opts(struct sk_buff *skb,
507 						     u8 *prev_hdr,
508 						     struct ipv6_txoptions *opt);
509 extern void 			ipv6_push_nfrag_opts(struct sk_buff *skb,
510 						     struct ipv6_txoptions *opt,
511 						     u8 *proto,
512 						     struct in6_addr **daddr_p);
513 extern void			ipv6_push_frag_opts(struct sk_buff *skb,
514 						    struct ipv6_txoptions *opt,
515 						    u8 *proto);
516 
517 extern int			ipv6_skip_exthdr(const struct sk_buff *, int start,
518 					         u8 *nexthdrp);
519 
520 extern int 			ipv6_ext_hdr(u8 nexthdr);
521 
522 extern int ipv6_find_tlv(struct sk_buff *skb, int offset, int type);
523 
524 extern struct ipv6_txoptions *	ipv6_invert_rthdr(struct sock *sk,
525 						  struct ipv6_rt_hdr *hdr);
526 
527 
528 /*
529  *	socket options (ipv6_sockglue.c)
530  */
531 
532 extern int			ipv6_setsockopt(struct sock *sk, int level,
533 						int optname,
534 						char __user *optval,
535 						int optlen);
536 extern int			ipv6_getsockopt(struct sock *sk, int level,
537 						int optname,
538 						char __user *optval,
539 						int __user *optlen);
540 extern int			compat_ipv6_setsockopt(struct sock *sk,
541 						int level,
542 						int optname,
543 						char __user *optval,
544 						int optlen);
545 extern int			compat_ipv6_getsockopt(struct sock *sk,
546 						int level,
547 						int optname,
548 						char __user *optval,
549 						int __user *optlen);
550 
551 extern void			ipv6_packet_init(void);
552 
553 extern void			ipv6_packet_cleanup(void);
554 
555 extern int			ip6_datagram_connect(struct sock *sk,
556 						     struct sockaddr *addr, int addr_len);
557 
558 extern int 			ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len);
559 extern void			ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err, __be16 port,
560 						u32 info, u8 *payload);
561 extern void			ipv6_local_error(struct sock *sk, int err, struct flowi *fl, u32 info);
562 
563 extern int inet6_release(struct socket *sock);
564 extern int inet6_bind(struct socket *sock, struct sockaddr *uaddr,
565 		      int addr_len);
566 extern int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
567 			 int *uaddr_len, int peer);
568 extern int inet6_ioctl(struct socket *sock, unsigned int cmd,
569 		       unsigned long arg);
570 
571 extern int inet6_hash_connect(struct inet_timewait_death_row *death_row,
572 			      struct sock *sk);
573 
574 /*
575  * reassembly.c
576  */
577 extern int sysctl_ip6frag_high_thresh;
578 extern int sysctl_ip6frag_low_thresh;
579 extern int sysctl_ip6frag_time;
580 extern int sysctl_ip6frag_secret_interval;
581 
582 extern const struct proto_ops inet6_stream_ops;
583 extern const struct proto_ops inet6_dgram_ops;
584 
585 struct group_source_req;
586 struct group_filter;
587 
588 extern int ip6_mc_source(int add, int omode, struct sock *sk,
589 			 struct group_source_req *pgsr);
590 extern int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf);
591 extern int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
592 			 struct group_filter __user *optval,
593 			 int __user *optlen);
594 
595 #ifdef CONFIG_PROC_FS
596 extern int  ac6_proc_init(void);
597 extern void ac6_proc_exit(void);
598 extern int  raw6_proc_init(void);
599 extern void raw6_proc_exit(void);
600 extern int  tcp6_proc_init(void);
601 extern void tcp6_proc_exit(void);
602 extern int  udp6_proc_init(void);
603 extern void udp6_proc_exit(void);
604 extern int  udplite6_proc_init(void);
605 extern void udplite6_proc_exit(void);
606 extern int  ipv6_misc_proc_init(void);
607 extern void ipv6_misc_proc_exit(void);
608 
609 extern struct rt6_statistics rt6_stats;
610 #endif
611 
612 #ifdef CONFIG_SYSCTL
613 extern ctl_table ipv6_route_table[];
614 extern ctl_table ipv6_icmp_table[];
615 
616 extern void ipv6_sysctl_register(void);
617 extern void ipv6_sysctl_unregister(void);
618 #endif
619 
620 #endif /* __KERNEL__ */
621 #endif /* _NET_IPV6_H */
622