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in6_proto.c revision 1.68.4.1
      1  1.68.4.1  wrstuden /*	$NetBSD: in6_proto.c,v 1.68.4.1 2007/06/04 01:54:24 wrstuden Exp $	*/
      2      1.21    itojun /*	$KAME: in6_proto.c,v 1.66 2000/10/10 15:35:47 itojun Exp $	*/
      3       1.3   thorpej 
      4       1.2    itojun /*
      5       1.2    itojun  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      6       1.2    itojun  * All rights reserved.
      7      1.18    itojun  *
      8       1.2    itojun  * Redistribution and use in source and binary forms, with or without
      9       1.2    itojun  * modification, are permitted provided that the following conditions
     10       1.2    itojun  * are met:
     11       1.2    itojun  * 1. Redistributions of source code must retain the above copyright
     12       1.2    itojun  *    notice, this list of conditions and the following disclaimer.
     13       1.2    itojun  * 2. Redistributions in binary form must reproduce the above copyright
     14       1.2    itojun  *    notice, this list of conditions and the following disclaimer in the
     15       1.2    itojun  *    documentation and/or other materials provided with the distribution.
     16       1.2    itojun  * 3. Neither the name of the project nor the names of its contributors
     17       1.2    itojun  *    may be used to endorse or promote products derived from this software
     18       1.2    itojun  *    without specific prior written permission.
     19      1.18    itojun  *
     20       1.2    itojun  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     21       1.2    itojun  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     22       1.2    itojun  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     23       1.2    itojun  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     24       1.2    itojun  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     25       1.2    itojun  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     26       1.2    itojun  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     27       1.2    itojun  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     28       1.2    itojun  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     29       1.2    itojun  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     30       1.2    itojun  * SUCH DAMAGE.
     31       1.2    itojun  */
     32       1.2    itojun 
     33       1.2    itojun /*
     34       1.2    itojun  * Copyright (c) 1982, 1986, 1993
     35       1.2    itojun  *	The Regents of the University of California.  All rights reserved.
     36       1.2    itojun  *
     37       1.2    itojun  * Redistribution and use in source and binary forms, with or without
     38       1.2    itojun  * modification, are permitted provided that the following conditions
     39       1.2    itojun  * are met:
     40       1.2    itojun  * 1. Redistributions of source code must retain the above copyright
     41       1.2    itojun  *    notice, this list of conditions and the following disclaimer.
     42       1.2    itojun  * 2. Redistributions in binary form must reproduce the above copyright
     43       1.2    itojun  *    notice, this list of conditions and the following disclaimer in the
     44       1.2    itojun  *    documentation and/or other materials provided with the distribution.
     45      1.49       agc  * 3. Neither the name of the University nor the names of its contributors
     46       1.2    itojun  *    may be used to endorse or promote products derived from this software
     47       1.2    itojun  *    without specific prior written permission.
     48       1.2    itojun  *
     49       1.2    itojun  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     50       1.2    itojun  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     51       1.2    itojun  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     52       1.2    itojun  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     53       1.2    itojun  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     54       1.2    itojun  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     55       1.2    itojun  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     56       1.2    itojun  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     57       1.2    itojun  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     58       1.2    itojun  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     59       1.2    itojun  * SUCH DAMAGE.
     60       1.2    itojun  *
     61       1.2    itojun  *	@(#)in_proto.c	8.1 (Berkeley) 6/10/93
     62       1.2    itojun  */
     63      1.34     lukem 
     64      1.34     lukem #include <sys/cdefs.h>
     65  1.68.4.1  wrstuden __KERNEL_RCSID(0, "$NetBSD: in6_proto.c,v 1.68.4.1 2007/06/04 01:54:24 wrstuden Exp $");
     66       1.2    itojun 
     67       1.2    itojun #include "opt_inet.h"
     68       1.4   thorpej #include "opt_ipsec.h"
     69      1.26    itojun #include "opt_iso.h"
     70       1.2    itojun 
     71       1.2    itojun #include <sys/param.h>
     72       1.2    itojun #include <sys/socket.h>
     73       1.2    itojun #include <sys/protosw.h>
     74       1.2    itojun #include <sys/kernel.h>
     75       1.2    itojun #include <sys/domain.h>
     76       1.2    itojun #include <sys/mbuf.h>
     77       1.2    itojun 
     78       1.2    itojun #include <net/if.h>
     79       1.2    itojun #include <net/radix.h>
     80       1.2    itojun #include <net/route.h>
     81       1.2    itojun 
     82       1.2    itojun #include <netinet/in.h>
     83       1.2    itojun #include <netinet/in_systm.h>
     84       1.2    itojun #include <netinet/in_var.h>
     85      1.17    itojun #include <netinet/ip_encap.h>
     86       1.2    itojun #include <netinet/ip.h>
     87       1.2    itojun #include <netinet/ip_var.h>
     88       1.2    itojun #include <netinet/in_pcb.h>
     89      1.13    itojun #include <netinet/ip6.h>
     90       1.2    itojun #include <netinet6/ip6_var.h>
     91      1.13    itojun #include <netinet/icmp6.h>
     92       1.2    itojun #include <netinet6/in6_pcb.h>
     93       1.2    itojun 
     94       1.2    itojun #include <netinet/tcp.h>
     95       1.2    itojun #include <netinet/tcp_fsm.h>
     96       1.2    itojun #include <netinet/tcp_seq.h>
     97       1.2    itojun #include <netinet/tcp_timer.h>
     98       1.2    itojun #include <netinet/tcp_var.h>
     99       1.2    itojun #include <netinet/tcpip.h>
    100       1.2    itojun #include <netinet/tcp_debug.h>
    101       1.2    itojun 
    102       1.2    itojun #include <netinet6/udp6.h>
    103       1.2    itojun #include <netinet6/udp6_var.h>
    104       1.2    itojun 
    105       1.2    itojun #include <netinet6/pim6_var.h>
    106       1.2    itojun 
    107       1.2    itojun #include <netinet6/nd6.h>
    108       1.2    itojun 
    109       1.2    itojun #ifdef IPSEC
    110       1.9    itojun #include <netinet6/ipsec.h>
    111       1.2    itojun #include <netinet6/ah.h>
    112       1.2    itojun #ifdef IPSEC_ESP
    113       1.2    itojun #include <netinet6/esp.h>
    114       1.2    itojun #endif
    115       1.2    itojun #include <netinet6/ipcomp.h>
    116      1.32    itojun #endif /* IPSEC */
    117       1.2    itojun 
    118  1.68.4.1  wrstuden #ifdef FAST_IPSEC
    119  1.68.4.1  wrstuden #include <netipsec/ipsec.h>
    120  1.68.4.1  wrstuden #include <netipsec/ipsec6.h>
    121  1.68.4.1  wrstuden #include <netipsec/key.h>
    122  1.68.4.1  wrstuden #endif /* FAST_IPSEC */
    123  1.68.4.1  wrstuden 
    124  1.68.4.1  wrstuden 
    125      1.63  liamjfoy #include "carp.h"
    126      1.63  liamjfoy #if NCARP > 0
    127      1.63  liamjfoy #include <netinet/ip_carp.h>
    128      1.63  liamjfoy #endif
    129      1.63  liamjfoy 
    130      1.68    rpaulo #include "etherip.h"
    131      1.68    rpaulo #if NETHERIP > 1
    132      1.68    rpaulo #include <netinet6/ip6_etherip.h>
    133      1.68    rpaulo #endif
    134      1.68    rpaulo 
    135       1.2    itojun #include <netinet6/ip6protosw.h>
    136       1.2    itojun 
    137      1.35    itojun #include <net/net_osdep.h>
    138      1.35    itojun 
    139      1.47   thorpej #ifndef offsetof		/* XXX */
    140       1.2    itojun #define	offsetof(type, member)	((size_t)(&((type *)0)->member))
    141      1.47   thorpej #endif
    142       1.2    itojun 
    143       1.2    itojun /*
    144       1.2    itojun  * TCP/IP protocol family: IP6, ICMP6, UDP, TCP.
    145       1.2    itojun  */
    146       1.2    itojun 
    147      1.58      matt DOMAIN_DEFINE(inet6domain);	/* forward declare and add to link set */
    148       1.2    itojun 
    149      1.57      matt const struct ip6protosw inet6sw[] = {
    150       1.2    itojun { 0,		&inet6domain,	IPPROTO_IPV6,	0,
    151       1.2    itojun   0,		0,		0,		0,
    152       1.2    itojun   0,
    153       1.9    itojun   ip6_init,	0,		frag6_slowtimo,	frag6_drain,
    154       1.2    itojun },
    155      1.60       gdt { SOCK_DGRAM,	&inet6domain,	IPPROTO_UDP,	PR_ATOMIC|PR_ADDR|PR_PURGEIF,
    156       1.2    itojun   udp6_input,	0,		udp6_ctlinput,	ip6_ctloutput,
    157      1.12    itojun   udp6_usrreq,	udp6_init,
    158       1.9    itojun   0,		0,		0,
    159       1.2    itojun },
    160      1.60       gdt { SOCK_STREAM,	&inet6domain,	IPPROTO_TCP,	PR_CONNREQUIRED|PR_WANTRCVD|PR_LISTEN|PR_ABRTACPTDIS|PR_PURGEIF,
    161       1.2    itojun   tcp6_input,	0,		tcp6_ctlinput,	tcp_ctloutput,
    162       1.2    itojun   tcp_usrreq,
    163      1.20     enami #ifdef INET	/* don't call initialization and timeout routines twice */
    164      1.51    itojun   0,		0,		0,		0,
    165       1.9    itojun #else
    166      1.52    itojun   tcp_init,	0,		tcp_slowtimo,	tcp_drain,
    167       1.9    itojun #endif
    168       1.2    itojun },
    169      1.60       gdt { SOCK_RAW,	&inet6domain,	IPPROTO_RAW,	PR_ATOMIC|PR_ADDR|PR_PURGEIF,
    170      1.16    itojun   rip6_input,	rip6_output,	rip6_ctlinput,	rip6_ctloutput,
    171       1.2    itojun   rip6_usrreq,
    172       1.9    itojun   0,		0,		0,		0,
    173       1.2    itojun },
    174      1.28    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_ICMPV6,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
    175      1.25    itojun   icmp6_input,	rip6_output,	rip6_ctlinput,	rip6_ctloutput,
    176       1.2    itojun   rip6_usrreq,
    177      1.62    rpaulo   icmp6_init,	0,		0,		0,
    178       1.2    itojun },
    179       1.2    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_DSTOPTS,PR_ATOMIC|PR_ADDR,
    180       1.2    itojun   dest6_input,	0,	 	0,		0,
    181      1.43    itojun   0,
    182       1.2    itojun   0,		0,		0,		0,
    183       1.2    itojun },
    184       1.2    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_ROUTING,PR_ATOMIC|PR_ADDR,
    185       1.2    itojun   route6_input,	0,	 	0,		0,
    186      1.43    itojun   0,
    187       1.2    itojun   0,		0,		0,		0,
    188       1.2    itojun },
    189       1.2    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_FRAGMENT,PR_ATOMIC|PR_ADDR,
    190       1.2    itojun   frag6_input,	0,	 	0,		0,
    191      1.43    itojun   0,
    192       1.2    itojun   0,		0,		0,		0,
    193       1.2    itojun },
    194       1.2    itojun #ifdef IPSEC
    195       1.2    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_AH,	PR_ATOMIC|PR_ADDR,
    196      1.22    itojun   ah6_input,	0,	 	ah6_ctlinput,	0,
    197      1.43    itojun   0,
    198       1.9    itojun   0,		0,		0,		0,
    199       1.2    itojun },
    200       1.2    itojun #ifdef IPSEC_ESP
    201       1.2    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_ESP,	PR_ATOMIC|PR_ADDR,
    202      1.22    itojun   esp6_input,	0,	 	esp6_ctlinput,	0,
    203      1.43    itojun   0,
    204       1.9    itojun   0,		0,		0,		0,
    205       1.2    itojun },
    206       1.2    itojun #endif
    207       1.2    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_IPCOMP,	PR_ATOMIC|PR_ADDR,
    208       1.2    itojun   ipcomp6_input, 0,	 	0,		0,
    209      1.43    itojun   0,
    210       1.9    itojun   0,		0,		0,		0,
    211       1.2    itojun },
    212       1.2    itojun #endif /* IPSEC */
    213  1.68.4.1  wrstuden #ifdef FAST_IPSEC
    214  1.68.4.1  wrstuden { SOCK_RAW,    &inet6domain,   IPPROTO_AH,     PR_ATOMIC|PR_ADDR,
    215  1.68.4.1  wrstuden   ipsec6_common_input, 0,              ah6_ctlinput,   0,
    216  1.68.4.1  wrstuden   0,
    217  1.68.4.1  wrstuden   0,           0,              0,              0,
    218  1.68.4.1  wrstuden },
    219  1.68.4.1  wrstuden { SOCK_RAW,    &inet6domain,   IPPROTO_ESP,    PR_ATOMIC|PR_ADDR,
    220  1.68.4.1  wrstuden   ipsec6_common_input,    0,           esp6_ctlinput,  0,
    221  1.68.4.1  wrstuden   0,
    222  1.68.4.1  wrstuden   0,           0,              0,              0,
    223  1.68.4.1  wrstuden },
    224  1.68.4.1  wrstuden { SOCK_RAW,    &inet6domain,   IPPROTO_IPCOMP, PR_ATOMIC|PR_ADDR,
    225  1.68.4.1  wrstuden   ipsec6_common_input,    0,           0,              0,
    226  1.68.4.1  wrstuden   0,
    227  1.68.4.1  wrstuden   0,           0,              0,              0,
    228  1.68.4.1  wrstuden },
    229  1.68.4.1  wrstuden #endif /* FAST_IPSEC */
    230      1.17    itojun #ifdef INET
    231      1.28    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_IPV4,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
    232      1.38    itojun   encap6_input,	rip6_output, 	encap6_ctlinput, rip6_ctloutput,
    233      1.17    itojun   rip6_usrreq,
    234      1.37    itojun   encap_init,	0,		0,		0,
    235       1.2    itojun },
    236      1.17    itojun #endif
    237      1.28    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_IPV6,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
    238      1.38    itojun   encap6_input, rip6_output,	encap6_ctlinput, rip6_ctloutput,
    239      1.17    itojun   rip6_usrreq,
    240      1.17    itojun   encap_init,	0,		0,		0,
    241       1.2    itojun },
    242      1.68    rpaulo #if NETHERIP > 1
    243      1.68    rpaulo { SOCK_RAW,	&inet6domain,	IPPROTO_ETHERIP,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
    244      1.68    rpaulo   ip6_etherip_input,	rip6_output,	rip6_ctlinput,	rip6_ctloutput,
    245      1.68    rpaulo   rip6_usrreq,
    246      1.68    rpaulo   0,		0,		0,		0,
    247      1.68    rpaulo },
    248      1.68    rpaulo #endif
    249      1.63  liamjfoy #if NCARP > 0
    250      1.63  liamjfoy { SOCK_RAW,	&inet6domain,	IPPROTO_CARP,	PR_ATOMIC|PR_ADDR,
    251      1.63  liamjfoy   carp6_proto_input,	rip6_output,	0,		rip6_ctloutput,
    252      1.63  liamjfoy   rip6_usrreq,
    253      1.65  christos   0,		0,		0,		0,
    254      1.63  liamjfoy },
    255      1.63  liamjfoy #endif /* NCARP */
    256      1.26    itojun #ifdef ISO
    257      1.28    itojun { SOCK_RAW,	&inet6domain,	IPPROTO_EON,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
    258      1.38    itojun   encap6_input,	rip6_output,	encap6_ctlinput, rip6_ctloutput,
    259      1.27    itojun   rip6_usrreq,	/*XXX*/
    260      1.37    itojun   encap_init,	0,		0,		0,
    261      1.26    itojun },
    262      1.26    itojun #endif
    263      1.28    itojun { SOCK_RAW,     &inet6domain,	IPPROTO_PIM,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
    264      1.42    itojun   pim6_input,	rip6_output,	0,              rip6_ctloutput,
    265       1.2    itojun   rip6_usrreq,
    266       1.2    itojun   0,            0,              0,              0,
    267       1.2    itojun },
    268       1.2    itojun /* raw wildcard */
    269      1.50    itojun { SOCK_RAW,	&inet6domain,	0,		PR_ATOMIC|PR_ADDR|PR_LASTHDR,
    270       1.2    itojun   rip6_input,	rip6_output,	0,		rip6_ctloutput,
    271      1.15    itojun   rip6_usrreq,
    272      1.15    itojun   rip6_init,	0,		0,		0,
    273       1.2    itojun },
    274       1.2    itojun };
    275      1.17    itojun 
    276      1.66  christos struct domain inet6domain = {
    277      1.66  christos 	AF_INET6, "internet6", NULL, NULL, NULL,
    278      1.66  christos 	(const struct protosw *)inet6sw,
    279      1.66  christos 	(const struct protosw *)&inet6sw[sizeof(inet6sw)/sizeof(inet6sw[0])],
    280      1.66  christos 	rn_inithead,
    281      1.66  christos 	offsetof(struct sockaddr_in6, sin6_addr) << 3,
    282      1.66  christos 	sizeof(struct sockaddr_in6),
    283      1.66  christos 	in6_domifattach, in6_domifdetach,
    284      1.66  christos 	{ &ip6intrq, NULL },
    285      1.66  christos 	{ NULL },
    286      1.67    dogcow 	MOWNER_INIT("","")
    287      1.66  christos };
    288       1.2    itojun 
    289       1.2    itojun /*
    290       1.2    itojun  * Internet configuration info
    291       1.2    itojun  */
    292       1.2    itojun #ifndef	IPV6FORWARDING
    293       1.2    itojun #ifdef GATEWAY6
    294       1.2    itojun #define	IPV6FORWARDING	1	/* forward IP6 packets not for us */
    295       1.2    itojun #else
    296       1.2    itojun #define	IPV6FORWARDING	0	/* don't forward IP6 packets not for us */
    297       1.2    itojun #endif /* GATEWAY6 */
    298       1.2    itojun #endif /* !IPV6FORWARDING */
    299       1.2    itojun 
    300       1.2    itojun int	ip6_forwarding = IPV6FORWARDING;	/* act as router? */
    301      1.48    itojun int	ip6_sendredirects = 1;
    302       1.2    itojun int	ip6_defhlim = IPV6_DEFHLIM;
    303       1.2    itojun int	ip6_defmcasthlim = IPV6_DEFAULT_MULTICAST_HOPS;
    304       1.2    itojun int	ip6_accept_rtadv = 0;	/* "IPV6FORWARDING ? 0 : 1" is dangerous */
    305       1.2    itojun int	ip6_maxfragpackets = 200;
    306      1.40    itojun int	ip6_maxfrags = 200;
    307       1.2    itojun int	ip6_log_interval = 5;
    308       1.2    itojun int	ip6_hdrnestlimit = 50;	/* appropriate? */
    309       1.2    itojun int	ip6_dad_count = 1;	/* DupAddrDetectionTransmits */
    310       1.2    itojun int	ip6_auto_flowlabel = 1;
    311      1.45    itojun int	ip6_use_deprecated = 1;	/* allow deprecated addr (RFC2462 5.5.4) */
    312       1.9    itojun int	ip6_rr_prune = 5;	/* router renumbering prefix
    313      1.38    itojun 				 * walk list every 5 sec. */
    314      1.62    rpaulo int	ip6_mcast_pmtu = 0;	/* enable pMTU discovery for multicast? */
    315      1.55    briggs int	ip6_v6only = 1;
    316      1.11    itojun 
    317       1.2    itojun int	ip6_keepfaith = 0;
    318       1.2    itojun time_t	ip6_log_time = (time_t)0L;
    319       1.2    itojun 
    320       1.2    itojun /* icmp6 */
    321       1.9    itojun /*
    322       1.9    itojun  * BSDI4 defines these variables in in_proto.c...
    323       1.9    itojun  * XXX: what if we don't define INET? Should we define pmtu6_expire
    324       1.9    itojun  * or so? (jinmei (at) kame.net 19990310)
    325       1.9    itojun  */
    326       1.2    itojun int pmtu_expire = 60*10;
    327       1.2    itojun 
    328       1.2    itojun /* raw IP6 parameters */
    329       1.2    itojun /*
    330       1.2    itojun  * Nominal space allocated to a raw ip socket.
    331       1.2    itojun  */
    332       1.2    itojun #define	RIPV6SNDQ	8192
    333       1.2    itojun #define	RIPV6RCVQ	8192
    334       1.2    itojun 
    335       1.2    itojun u_long	rip6_sendspace = RIPV6SNDQ;
    336       1.2    itojun u_long	rip6_recvspace = RIPV6RCVQ;
    337       1.2    itojun 
    338       1.2    itojun /* ICMPV6 parameters */
    339       1.2    itojun int	icmp6_rediraccept = 1;		/* accept and process redirects */
    340       1.2    itojun int	icmp6_redirtimeout = 10 * 60;	/* 10 minutes */
    341      1.18    itojun int	icmp6errppslim = 100;		/* 100pps */
    342      1.10    itojun int	icmp6_nodeinfo = 1;		/* enable/disable NI response */
    343       1.2    itojun 
    344       1.2    itojun /* UDP on IP6 parameters */
    345       1.2    itojun int	udp6_sendspace = 9216;		/* really max datagram size */
    346       1.2    itojun int	udp6_recvspace = 40 * (1024 + sizeof(struct sockaddr_in6));
    347       1.2    itojun 					/* 40 1K datagrams */
    348