2 * Linux INET6 implementation
5 * Pedro Roque <roque@di.fc.ul.pt>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
16 #include <linux/ipv6.h>
17 #include <linux/hardirq.h>
18 #include <net/if_inet6.h>
19 #include <net/ndisc.h>
23 #define SIN6_LEN_RFC2133 24
25 #define IPV6_MAXPLEN 65535
28 * NextHeader field of IPv6 header
31 #define NEXTHDR_HOP 0 /* Hop-by-hop option header. */
32 #define NEXTHDR_TCP 6 /* TCP segment. */
33 #define NEXTHDR_UDP 17 /* UDP message. */
34 #define NEXTHDR_IPV6 41 /* IPv6 in IPv6 */
35 #define NEXTHDR_ROUTING 43 /* Routing header. */
36 #define NEXTHDR_FRAGMENT 44 /* Fragmentation/reassembly header. */
37 #define NEXTHDR_GRE 47 /* GRE 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. */
45 #define NEXTHDR_MAX 255
49 #define IPV6_DEFAULT_HOPLIMIT 64
50 #define IPV6_DEFAULT_MCASTHOPS 1
55 * type - unicast | multicast
56 * scope - local | site | global
63 #define IPV6_ADDR_ANY 0x0000U
65 #define IPV6_ADDR_UNICAST 0x0001U
66 #define IPV6_ADDR_MULTICAST 0x0002U
68 #define IPV6_ADDR_LOOPBACK 0x0010U
69 #define IPV6_ADDR_LINKLOCAL 0x0020U
70 #define IPV6_ADDR_SITELOCAL 0x0040U
72 #define IPV6_ADDR_COMPATv4 0x0080U
74 #define IPV6_ADDR_SCOPE_MASK 0x00f0U
76 #define IPV6_ADDR_MAPPED 0x1000U
81 #define IPV6_ADDR_MC_SCOPE(a) \
82 ((a)->s6_addr[1] & 0x0f) /* nonstandard */
83 #define __IPV6_ADDR_SCOPE_INVALID -1
84 #define IPV6_ADDR_SCOPE_NODELOCAL 0x01
85 #define IPV6_ADDR_SCOPE_LINKLOCAL 0x02
86 #define IPV6_ADDR_SCOPE_SITELOCAL 0x05
87 #define IPV6_ADDR_SCOPE_ORGLOCAL 0x08
88 #define IPV6_ADDR_SCOPE_GLOBAL 0x0e
93 #define IPV6_ADDR_MC_FLAG_TRANSIENT(a) \
94 ((a)->s6_addr[1] & 0x10)
95 #define IPV6_ADDR_MC_FLAG_PREFIX(a) \
96 ((a)->s6_addr[1] & 0x20)
97 #define IPV6_ADDR_MC_FLAG_RENDEZVOUS(a) \
98 ((a)->s6_addr[1] & 0x40)
101 * fragmentation header
108 __be32 identification;
111 #define IP6_MF 0x0001
113 #include <net/sock.h>
116 extern int sysctl_mld_max_msf;
118 #define _DEVINC(net, statname, modifier, idev, field) \
120 struct inet6_dev *_idev = (idev); \
121 if (likely(_idev != NULL)) \
122 SNMP_INC_STATS##modifier((_idev)->stats.statname, (field)); \
123 SNMP_INC_STATS##modifier((net)->mib.statname##_statistics, (field));\
126 /* per device counters are atomic_long_t */
127 #define _DEVINCATOMIC(net, statname, modifier, idev, field) \
129 struct inet6_dev *_idev = (idev); \
130 if (likely(_idev != NULL)) \
131 SNMP_INC_STATS_ATOMIC_LONG((_idev)->stats.statname##dev, (field)); \
132 SNMP_INC_STATS##modifier((net)->mib.statname##_statistics, (field));\
135 /* per device and per net counters are atomic_long_t */
136 #define _DEVINC_ATOMIC_ATOMIC(net, statname, idev, field) \
138 struct inet6_dev *_idev = (idev); \
139 if (likely(_idev != NULL)) \
140 SNMP_INC_STATS_ATOMIC_LONG((_idev)->stats.statname##dev, (field)); \
141 SNMP_INC_STATS_ATOMIC_LONG((net)->mib.statname##_statistics, (field));\
144 #define _DEVADD(net, statname, modifier, idev, field, val) \
146 struct inet6_dev *_idev = (idev); \
147 if (likely(_idev != NULL)) \
148 SNMP_ADD_STATS##modifier((_idev)->stats.statname, (field), (val)); \
149 SNMP_ADD_STATS##modifier((net)->mib.statname##_statistics, (field), (val));\
152 #define _DEVUPD(net, statname, modifier, idev, field, val) \
154 struct inet6_dev *_idev = (idev); \
155 if (likely(_idev != NULL)) \
156 SNMP_UPD_PO_STATS##modifier((_idev)->stats.statname, field, (val)); \
157 SNMP_UPD_PO_STATS##modifier((net)->mib.statname##_statistics, field, (val));\
162 #define IP6_INC_STATS(net, idev,field) \
163 _DEVINC(net, ipv6, 64, idev, field)
164 #define IP6_INC_STATS_BH(net, idev,field) \
165 _DEVINC(net, ipv6, 64_BH, idev, field)
166 #define IP6_ADD_STATS(net, idev,field,val) \
167 _DEVADD(net, ipv6, 64, idev, field, val)
168 #define IP6_ADD_STATS_BH(net, idev,field,val) \
169 _DEVADD(net, ipv6, 64_BH, idev, field, val)
170 #define IP6_UPD_PO_STATS(net, idev,field,val) \
171 _DEVUPD(net, ipv6, 64, idev, field, val)
172 #define IP6_UPD_PO_STATS_BH(net, idev,field,val) \
173 _DEVUPD(net, ipv6, 64_BH, idev, field, val)
174 #define ICMP6_INC_STATS(net, idev, field) \
175 _DEVINCATOMIC(net, icmpv6, , idev, field)
176 #define ICMP6_INC_STATS_BH(net, idev, field) \
177 _DEVINCATOMIC(net, icmpv6, _BH, idev, field)
179 #define ICMP6MSGOUT_INC_STATS(net, idev, field) \
180 _DEVINC_ATOMIC_ATOMIC(net, icmpv6msg, idev, field +256)
181 #define ICMP6MSGOUT_INC_STATS_BH(net, idev, field) \
182 _DEVINC_ATOMIC_ATOMIC(net, icmpv6msg, idev, field +256)
183 #define ICMP6MSGIN_INC_STATS_BH(net, idev, field) \
184 _DEVINC_ATOMIC_ATOMIC(net, icmpv6msg, idev, field)
186 struct ip6_ra_chain {
187 struct ip6_ra_chain *next;
190 void (*destructor)(struct sock *);
193 extern struct ip6_ra_chain *ip6_ra_chain;
194 extern rwlock_t ip6_ra_lock;
197 This structure is prepared by protocol, when parsing
198 ancillary data and passed to IPv6.
201 struct ipv6_txoptions {
202 /* Length of this structure */
205 /* length of extension headers */
207 __u16 opt_flen; /* after fragment hdr */
208 __u16 opt_nflen; /* before fragment hdr */
210 struct ipv6_opt_hdr *hopopt;
211 struct ipv6_opt_hdr *dst0opt;
212 struct ipv6_rt_hdr *srcrt; /* Routing Header */
213 struct ipv6_opt_hdr *dst1opt;
215 /* Option buffer, as read by IPV6_PKTOPTIONS, starts here. */
218 struct ip6_flowlabel {
219 struct ip6_flowlabel *next;
223 struct ipv6_txoptions *opt;
224 unsigned long linger;
230 unsigned long lastuse;
231 unsigned long expires;
235 #define IPV6_FLOWINFO_MASK cpu_to_be32(0x0FFFFFFF)
236 #define IPV6_FLOWLABEL_MASK cpu_to_be32(0x000FFFFF)
238 struct ipv6_fl_socklist {
239 struct ipv6_fl_socklist *next;
240 struct ip6_flowlabel *fl;
243 extern struct ip6_flowlabel *fl6_sock_lookup(struct sock *sk, __be32 label);
244 extern struct ipv6_txoptions *fl6_merge_options(struct ipv6_txoptions * opt_space,
245 struct ip6_flowlabel * fl,
246 struct ipv6_txoptions * fopt);
247 extern void fl6_free_socklist(struct sock *sk);
248 extern int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen);
249 extern int ip6_flowlabel_init(void);
250 extern void ip6_flowlabel_cleanup(void);
252 static inline void fl6_sock_release(struct ip6_flowlabel *fl)
255 atomic_dec(&fl->users);
258 extern void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info);
260 extern int ip6_ra_control(struct sock *sk, int sel);
262 extern int ipv6_parse_hopopts(struct sk_buff *skb);
264 extern struct ipv6_txoptions * ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt);
265 extern struct ipv6_txoptions * ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
267 struct ipv6_opt_hdr __user *newopt,
269 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
270 struct ipv6_txoptions *opt);
272 extern bool ipv6_opt_accepted(const struct sock *sk, const struct sk_buff *skb);
274 int ip6_frag_nqueues(struct net *net);
275 int ip6_frag_mem(struct net *net);
277 #define IPV6_FRAG_HIGH_THRESH (256 * 1024) /* 262144 */
278 #define IPV6_FRAG_LOW_THRESH (192 * 1024) /* 196608 */
279 #define IPV6_FRAG_TIMEOUT (60 * HZ) /* 60 seconds */
281 extern int __ipv6_addr_type(const struct in6_addr *addr);
282 static inline int ipv6_addr_type(const struct in6_addr *addr)
284 return __ipv6_addr_type(addr) & 0xffff;
287 static inline int ipv6_addr_scope(const struct in6_addr *addr)
289 return __ipv6_addr_type(addr) & IPV6_ADDR_SCOPE_MASK;
292 static inline int __ipv6_addr_src_scope(int type)
294 return (type == IPV6_ADDR_ANY) ? __IPV6_ADDR_SCOPE_INVALID : (type >> 16);
297 static inline int ipv6_addr_src_scope(const struct in6_addr *addr)
299 return __ipv6_addr_src_scope(__ipv6_addr_type(addr));
302 static inline int ipv6_addr_cmp(const struct in6_addr *a1, const struct in6_addr *a2)
304 return memcmp(a1, a2, sizeof(struct in6_addr));
308 ipv6_masked_addr_cmp(const struct in6_addr *a1, const struct in6_addr *m,
309 const struct in6_addr *a2)
311 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
312 const unsigned long *ul1 = (const unsigned long *)a1;
313 const unsigned long *ulm = (const unsigned long *)m;
314 const unsigned long *ul2 = (const unsigned long *)a2;
316 return !!(((ul1[0] ^ ul2[0]) & ulm[0]) |
317 ((ul1[1] ^ ul2[1]) & ulm[1]));
319 return !!(((a1->s6_addr32[0] ^ a2->s6_addr32[0]) & m->s6_addr32[0]) |
320 ((a1->s6_addr32[1] ^ a2->s6_addr32[1]) & m->s6_addr32[1]) |
321 ((a1->s6_addr32[2] ^ a2->s6_addr32[2]) & m->s6_addr32[2]) |
322 ((a1->s6_addr32[3] ^ a2->s6_addr32[3]) & m->s6_addr32[3]));
326 static inline void ipv6_addr_prefix(struct in6_addr *pfx,
327 const struct in6_addr *addr,
330 /* caller must guarantee 0 <= plen <= 128 */
334 memset(pfx->s6_addr, 0, sizeof(pfx->s6_addr));
335 memcpy(pfx->s6_addr, addr, o);
337 pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b);
340 static inline void ipv6_addr_set(struct in6_addr *addr,
341 __be32 w1, __be32 w2,
342 __be32 w3, __be32 w4)
344 addr->s6_addr32[0] = w1;
345 addr->s6_addr32[1] = w2;
346 addr->s6_addr32[2] = w3;
347 addr->s6_addr32[3] = w4;
350 static inline bool ipv6_addr_equal(const struct in6_addr *a1,
351 const struct in6_addr *a2)
353 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
354 const unsigned long *ul1 = (const unsigned long *)a1;
355 const unsigned long *ul2 = (const unsigned long *)a2;
357 return ((ul1[0] ^ ul2[0]) | (ul1[1] ^ ul2[1])) == 0UL;
359 return ((a1->s6_addr32[0] ^ a2->s6_addr32[0]) |
360 (a1->s6_addr32[1] ^ a2->s6_addr32[1]) |
361 (a1->s6_addr32[2] ^ a2->s6_addr32[2]) |
362 (a1->s6_addr32[3] ^ a2->s6_addr32[3])) == 0;
366 static inline bool __ipv6_prefix_equal(const __be32 *a1, const __be32 *a2,
367 unsigned int prefixlen)
369 unsigned int pdw, pbi;
371 /* check complete u32 in prefix */
372 pdw = prefixlen >> 5;
373 if (pdw && memcmp(a1, a2, pdw << 2))
376 /* check incomplete u32 in prefix */
377 pbi = prefixlen & 0x1f;
378 if (pbi && ((a1[pdw] ^ a2[pdw]) & htonl((0xffffffff) << (32 - pbi))))
384 static inline bool ipv6_prefix_equal(const struct in6_addr *a1,
385 const struct in6_addr *a2,
386 unsigned int prefixlen)
388 return __ipv6_prefix_equal(a1->s6_addr32, a2->s6_addr32,
392 struct inet_frag_queue;
394 enum ip6_defrag_users {
395 IP6_DEFRAG_LOCAL_DELIVER,
396 IP6_DEFRAG_CONNTRACK_IN,
397 __IP6_DEFRAG_CONNTRACK_IN = IP6_DEFRAG_CONNTRACK_IN + USHRT_MAX,
398 IP6_DEFRAG_CONNTRACK_OUT,
399 __IP6_DEFRAG_CONNTRACK_OUT = IP6_DEFRAG_CONNTRACK_OUT + USHRT_MAX,
400 IP6_DEFRAG_CONNTRACK_BRIDGE_IN,
401 __IP6_DEFRAG_CONNTRACK_BRIDGE_IN = IP6_DEFRAG_CONNTRACK_BRIDGE_IN + USHRT_MAX,
404 struct ip6_create_arg {
407 const struct in6_addr *src;
408 const struct in6_addr *dst;
411 void ip6_frag_init(struct inet_frag_queue *q, void *a);
412 bool ip6_frag_match(struct inet_frag_queue *q, void *a);
414 static inline bool ipv6_addr_any(const struct in6_addr *a)
416 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
417 const unsigned long *ul = (const unsigned long *)a;
419 return (ul[0] | ul[1]) == 0UL;
421 return (a->s6_addr32[0] | a->s6_addr32[1] |
422 a->s6_addr32[2] | a->s6_addr32[3]) == 0;
426 static inline u32 ipv6_addr_hash(const struct in6_addr *a)
428 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
429 const unsigned long *ul = (const unsigned long *)a;
430 unsigned long x = ul[0] ^ ul[1];
432 return (u32)(x ^ (x >> 32));
434 return (__force u32)(a->s6_addr32[0] ^ a->s6_addr32[1] ^
435 a->s6_addr32[2] ^ a->s6_addr32[3]);
439 static inline bool ipv6_addr_loopback(const struct in6_addr *a)
441 return (a->s6_addr32[0] | a->s6_addr32[1] |
442 a->s6_addr32[2] | (a->s6_addr32[3] ^ htonl(1))) == 0;
445 static inline bool ipv6_addr_v4mapped(const struct in6_addr *a)
447 return (a->s6_addr32[0] | a->s6_addr32[1] |
448 (a->s6_addr32[2] ^ htonl(0x0000ffff))) == 0;
452 * Check for a RFC 4843 ORCHID address
453 * (Overlay Routable Cryptographic Hash Identifiers)
455 static inline bool ipv6_addr_orchid(const struct in6_addr *a)
457 return (a->s6_addr32[0] & htonl(0xfffffff0)) == htonl(0x20010010);
460 static inline void ipv6_addr_set_v4mapped(const __be32 addr,
461 struct in6_addr *v4mapped)
463 ipv6_addr_set(v4mapped,
470 * find the first different bit between two addresses
471 * length of address must be a multiple of 32bits
473 static inline int __ipv6_addr_diff(const void *token1, const void *token2, int addrlen)
475 const __be32 *a1 = token1, *a2 = token2;
480 for (i = 0; i < addrlen; i++) {
481 __be32 xb = a1[i] ^ a2[i];
483 return i * 32 + 31 - __fls(ntohl(xb));
487 * we should *never* get to this point since that
488 * would mean the addrs are equal
490 * However, we do get to it 8) And exacly, when
491 * addresses are equal 8)
493 * ip route add 1111::/128 via ...
494 * ip route add 1111::/64 via ...
497 * Ideally, this function should stop comparison
498 * at prefix length. It does not, but it is still OK,
499 * if returned value is greater than prefix length.
505 static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_addr *a2)
507 return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));
510 extern void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt);
513 * Prototypes exported by ipv6
517 * rcv function (called from netdevice level)
520 extern int ipv6_rcv(struct sk_buff *skb,
521 struct net_device *dev,
522 struct packet_type *pt,
523 struct net_device *orig_dev);
525 extern int ip6_rcv_finish(struct sk_buff *skb);
528 * upper-layer output functions
530 extern int ip6_xmit(struct sock *sk,
533 struct ipv6_txoptions *opt,
536 extern int ip6_nd_hdr(struct sock *sk,
538 struct net_device *dev,
539 const struct in6_addr *saddr,
540 const struct in6_addr *daddr,
543 extern int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr);
545 extern int ip6_append_data(struct sock *sk,
546 int getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb),
552 struct ipv6_txoptions *opt,
558 extern int ip6_push_pending_frames(struct sock *sk);
560 extern void ip6_flush_pending_frames(struct sock *sk);
562 extern int ip6_dst_lookup(struct sock *sk,
563 struct dst_entry **dst,
565 extern struct dst_entry * ip6_dst_lookup_flow(struct sock *sk,
567 const struct in6_addr *final_dst,
569 extern struct dst_entry * ip6_sk_dst_lookup_flow(struct sock *sk,
571 const struct in6_addr *final_dst,
573 extern struct dst_entry * ip6_blackhole_route(struct net *net,
574 struct dst_entry *orig_dst);
577 * skb processing functions
580 extern int ip6_output(struct sk_buff *skb);
581 extern int ip6_forward(struct sk_buff *skb);
582 extern int ip6_input(struct sk_buff *skb);
583 extern int ip6_mc_input(struct sk_buff *skb);
585 extern int __ip6_local_out(struct sk_buff *skb);
586 extern int ip6_local_out(struct sk_buff *skb);
589 * Extension header (options) processing
592 extern void ipv6_push_nfrag_opts(struct sk_buff *skb,
593 struct ipv6_txoptions *opt,
595 struct in6_addr **daddr_p);
596 extern void ipv6_push_frag_opts(struct sk_buff *skb,
597 struct ipv6_txoptions *opt,
600 extern int ipv6_skip_exthdr(const struct sk_buff *, int start,
601 u8 *nexthdrp, __be16 *frag_offp);
603 extern bool ipv6_ext_hdr(u8 nexthdr);
605 extern int ipv6_find_tlv(struct sk_buff *skb, int offset, int type);
607 extern struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
608 const struct ipv6_txoptions *opt,
609 struct in6_addr *orig);
612 * socket options (ipv6_sockglue.c)
615 extern int ipv6_setsockopt(struct sock *sk, int level,
618 unsigned int optlen);
619 extern int ipv6_getsockopt(struct sock *sk, int level,
623 extern int compat_ipv6_setsockopt(struct sock *sk,
627 unsigned int optlen);
628 extern int compat_ipv6_getsockopt(struct sock *sk,
634 extern int ip6_datagram_connect(struct sock *sk,
635 struct sockaddr *addr, int addr_len);
637 extern int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len);
638 extern int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len);
639 extern void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err, __be16 port,
640 u32 info, u8 *payload);
641 extern void ipv6_local_error(struct sock *sk, int err, struct flowi6 *fl6, u32 info);
642 extern void ipv6_local_rxpmtu(struct sock *sk, struct flowi6 *fl6, u32 mtu);
644 extern int inet6_release(struct socket *sock);
645 extern int inet6_bind(struct socket *sock, struct sockaddr *uaddr,
647 extern int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
648 int *uaddr_len, int peer);
649 extern int inet6_ioctl(struct socket *sock, unsigned int cmd,
652 extern int inet6_hash_connect(struct inet_timewait_death_row *death_row,
658 extern const struct proto_ops inet6_stream_ops;
659 extern const struct proto_ops inet6_dgram_ops;
661 struct group_source_req;
664 extern int ip6_mc_source(int add, int omode, struct sock *sk,
665 struct group_source_req *pgsr);
666 extern int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf);
667 extern int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
668 struct group_filter __user *optval,
670 extern unsigned int inet6_hash_frag(__be32 id, const struct in6_addr *saddr,
671 const struct in6_addr *daddr, u32 rnd);
673 #ifdef CONFIG_PROC_FS
674 extern int ac6_proc_init(struct net *net);
675 extern void ac6_proc_exit(struct net *net);
676 extern int raw6_proc_init(void);
677 extern void raw6_proc_exit(void);
678 extern int tcp6_proc_init(struct net *net);
679 extern void tcp6_proc_exit(struct net *net);
680 extern int udp6_proc_init(struct net *net);
681 extern void udp6_proc_exit(struct net *net);
682 extern int udplite6_proc_init(void);
683 extern void udplite6_proc_exit(void);
684 extern int ipv6_misc_proc_init(void);
685 extern void ipv6_misc_proc_exit(void);
686 extern int snmp6_register_dev(struct inet6_dev *idev);
687 extern int snmp6_unregister_dev(struct inet6_dev *idev);
690 static inline int ac6_proc_init(struct net *net) { return 0; }
691 static inline void ac6_proc_exit(struct net *net) { }
692 static inline int snmp6_register_dev(struct inet6_dev *idev) { return 0; }
693 static inline int snmp6_unregister_dev(struct inet6_dev *idev) { return 0; }
697 extern ctl_table ipv6_route_table_template[];
698 extern ctl_table ipv6_icmp_table_template[];
700 extern struct ctl_table *ipv6_icmp_sysctl_init(struct net *net);
701 extern struct ctl_table *ipv6_route_sysctl_init(struct net *net);
702 extern int ipv6_sysctl_register(void);
703 extern void ipv6_sysctl_unregister(void);
706 #endif /* _NET_IPV6_H */