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root/net/ipv6/udp.c

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DEFINITIONS

This source file includes following definitions.
  1. udp_v6_get_port
  2. __udp6_lib_lookup
  3. __udp6_lib_lookup_skb
  4. udpv6_recvmsg
  5. __udp6_lib_err
  6. udpv6_err
  7. udpv6_queue_rcv_skb
  8. udp_v6_mcast_next
  9. __udp6_lib_mcast_deliver
  10. udp6_csum_init
  11. __udp6_lib_rcv
  12. udpv6_rcv
  13. udp_v6_flush_pending_frames
  14. udp_v6_push_pending_frames
  15. udpv6_sendmsg
  16. udpv6_destroy_sock
  17. udpv6_setsockopt
  18. compat_udpv6_setsockopt
  19. udpv6_getsockopt
  20. compat_udpv6_getsockopt
  21. udp6_sock_seq_show
  22. udp6_seq_show
  23. udp6_proc_init
  24. udp6_proc_exit
  25. udpv6_init
  26. udpv6_exit

/*
 *      UDP over IPv6
 *      Linux INET6 implementation
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>
 *
 *      Based on linux/ipv4/udp.c
 *
 *      Fixes:
 *      Hideaki YOSHIFUJI       :       sin6_scope_id support
 *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
 *      Alexey Kuznetsov                allow both IPv4 and IPv6 sockets to bind
 *                                      a single port at the same time.
 *      Kazunori MIYAZAWA @USAGI:       change process style to use ip6_append_data
 *      YOSHIFUJI Hideaki @USAGI:       convert /proc/net/udp6 to seq_file.
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/ipv6.h>
#include <linux/icmpv6.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <asm/uaccess.h>

#include <net/ndisc.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/ip6_route.h>
#include <net/raw.h>
#include <net/tcp_states.h>
#include <net/ip6_checksum.h>
#include <net/xfrm.h>

#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include "udp_impl.h"

int udp_v6_get_port(struct sock *sk, unsigned short snum)
{
        return udp_lib_get_port(sk, snum, ipv6_rcv_saddr_equal);
}

static struct sock *__udp6_lib_lookup(struct net *net,
                                      struct in6_addr *saddr, __be16 sport,
                                      struct in6_addr *daddr, __be16 dport,
                                      int dif, struct hlist_head udptable[])
{
        struct sock *sk, *result = NULL;
        struct hlist_node *node;
        unsigned short hnum = ntohs(dport);
        int badness = -1;

        read_lock(&udp_hash_lock);
        sk_for_each(sk, node, &udptable[udp_hashfn(net, hnum)]) {
                struct inet_sock *inet = inet_sk(sk);

                if (net_eq(sock_net(sk), net) && sk->sk_hash == hnum &&
                                sk->sk_family == PF_INET6) {
                        struct ipv6_pinfo *np = inet6_sk(sk);
                        int score = 0;
                        if (inet->dport) {
                                if (inet->dport != sport)
                                        continue;
                                score++;
                        }
                        if (!ipv6_addr_any(&np->rcv_saddr)) {
                                if (!ipv6_addr_equal(&np->rcv_saddr, daddr))
                                        continue;
                                score++;
                        }
                        if (!ipv6_addr_any(&np->daddr)) {
                                if (!ipv6_addr_equal(&np->daddr, saddr))
                                        continue;
                                score++;
                        }
                        if (sk->sk_bound_dev_if) {
                                if (sk->sk_bound_dev_if != dif)
                                        continue;
                                score++;
                        }
                        if (score == 4) {
                                result = sk;
                                break;
                        } else if (score > badness) {
                                result = sk;
                                badness = score;
                        }
                }
        }
        if (result)
                sock_hold(result);
        read_unlock(&udp_hash_lock);
        return result;
}

static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
                                          __be16 sport, __be16 dport,
                                          struct hlist_head udptable[])
{
        struct sock *sk;
        struct ipv6hdr *iph = ipv6_hdr(skb);

        if (unlikely(sk = skb_steal_sock(skb)))
                return sk;
        else
                return __udp6_lib_lookup(dev_net(skb->dst->dev), &iph->saddr, sport,
                                         &iph->daddr, dport, inet6_iif(skb),
                                         udptable);
}

/*
 *      This should be easy, if there is something there we
 *      return it, otherwise we block.
 */

int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
                  struct msghdr *msg, size_t len,
                  int noblock, int flags, int *addr_len)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct inet_sock *inet = inet_sk(sk);
        struct sk_buff *skb;
        unsigned int ulen, copied;
        int peeked;
        int err;
        int is_udplite = IS_UDPLITE(sk);

        if (addr_len)
                *addr_len=sizeof(struct sockaddr_in6);

        if (flags & MSG_ERRQUEUE)
                return ipv6_recv_error(sk, msg, len);

try_again:
        skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
                                  &peeked, &err);
        if (!skb)
                goto out;

        ulen = skb->len - sizeof(struct udphdr);
        copied = len;
        if (copied > ulen)
                copied = ulen;
        else if (copied < ulen)
                msg->msg_flags |= MSG_TRUNC;

        /*
         * If checksum is needed at all, try to do it while copying the
         * data.  If the data is truncated, or if we only want a partial
         * coverage checksum (UDP-Lite), do it before the copy.
         */

        if (copied < ulen || UDP_SKB_CB(skb)->partial_cov) {
                if (udp_lib_checksum_complete(skb))
                        goto csum_copy_err;
        }

        if (skb_csum_unnecessary(skb))
                err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr),
                                              msg->msg_iov, copied       );
        else {
                err = skb_copy_and_csum_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov);
                if (err == -EINVAL)
                        goto csum_copy_err;
        }
        if (err)
                goto out_free;

        if (!peeked)
                UDP6_INC_STATS_USER(sock_net(sk),
                                UDP_MIB_INDATAGRAMS, is_udplite);

        sock_recv_timestamp(msg, sk, skb);

        /* Copy the address. */
        if (msg->msg_name) {
                struct sockaddr_in6 *sin6;

                sin6 = (struct sockaddr_in6 *) msg->msg_name;
                sin6->sin6_family = AF_INET6;
                sin6->sin6_port = udp_hdr(skb)->source;
                sin6->sin6_flowinfo = 0;
                sin6->sin6_scope_id = 0;

                if (skb->protocol == htons(ETH_P_IP))
                        ipv6_addr_set(&sin6->sin6_addr, 0, 0,
                                      htonl(0xffff), ip_hdr(skb)->saddr);
                else {
                        ipv6_addr_copy(&sin6->sin6_addr,
                                       &ipv6_hdr(skb)->saddr);
                        if (ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL)
                                sin6->sin6_scope_id = IP6CB(skb)->iif;
                }

        }
        if (skb->protocol == htons(ETH_P_IP)) {
                if (inet->cmsg_flags)
                        ip_cmsg_recv(msg, skb);
        } else {
                if (np->rxopt.all)
                        datagram_recv_ctl(sk, msg, skb);
        }

        err = copied;
        if (flags & MSG_TRUNC)
                err = ulen;

out_free:
        lock_sock(sk);
        skb_free_datagram(sk, skb);
        release_sock(sk);
out:
        return err;

csum_copy_err:
        lock_sock(sk);
        if (!skb_kill_datagram(sk, skb, flags))
                UDP6_INC_STATS_USER(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
        release_sock(sk);

        if (flags & MSG_DONTWAIT)
                return -EAGAIN;
        goto try_again;
}

void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                    int type, int code, int offset, __be32 info,
                    struct hlist_head udptable[]                    )
{
        struct ipv6_pinfo *np;
        struct ipv6hdr *hdr = (struct ipv6hdr*)skb->data;
        struct in6_addr *saddr = &hdr->saddr;
        struct in6_addr *daddr = &hdr->daddr;
        struct udphdr *uh = (struct udphdr*)(skb->data+offset);
        struct sock *sk;
        int err;

        sk = __udp6_lib_lookup(dev_net(skb->dev), daddr, uh->dest,
                               saddr, uh->source, inet6_iif(skb), udptable);
        if (sk == NULL)
                return;

        np = inet6_sk(sk);

        if (!icmpv6_err_convert(type, code, &err) && !np->recverr)
                goto out;

        if (sk->sk_state != TCP_ESTABLISHED && !np->recverr)
                goto out;

        if (np->recverr)
                ipv6_icmp_error(sk, skb, err, uh->dest, ntohl(info), (u8 *)(uh+1));

        sk->sk_err = err;
        sk->sk_error_report(sk);
out:
        sock_put(sk);
}

static __inline__ void udpv6_err(struct sk_buff *skb,
                                 struct inet6_skb_parm *opt, int type,
                                 int code, int offset, __be32 info     )
{
        __udp6_lib_err(skb, opt, type, code, offset, info, udp_hash);
}

int udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
{
        struct udp_sock *up = udp_sk(sk);
        int rc;
        int is_udplite = IS_UDPLITE(sk);

        if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
                goto drop;

        /*
         * UDP-Lite specific tests, ignored on UDP sockets (see net/ipv4/udp.c).
         */
        if ((is_udplite & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {

                if (up->pcrlen == 0) {          /* full coverage was set  */
                        LIMIT_NETDEBUG(KERN_WARNING "UDPLITE6: partial coverage"
                                " %d while full coverage %d requested\n",
                                UDP_SKB_CB(skb)->cscov, skb->len);
                        goto drop;
                }
                if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
                        LIMIT_NETDEBUG(KERN_WARNING "UDPLITE6: coverage %d "
                                                    "too small, need min %d\n",
                                       UDP_SKB_CB(skb)->cscov, up->pcrlen);
                        goto drop;
                }
        }

        if (sk->sk_filter) {
                if (udp_lib_checksum_complete(skb))
                        goto drop;
        }

        if ((rc = sock_queue_rcv_skb(sk,skb)) < 0) {
                /* Note that an ENOMEM error is charged twice */
                if (rc == -ENOMEM) {
                        UDP6_INC_STATS_BH(sock_net(sk),
                                        UDP_MIB_RCVBUFERRORS, is_udplite);
                        atomic_inc(&sk->sk_drops);
                }
                goto drop;
        }

        return 0;
drop:
        UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS, is_udplite);
        kfree_skb(skb);
        return -1;
}

static struct sock *udp_v6_mcast_next(struct sock *sk,
                                      __be16 loc_port, struct in6_addr *loc_addr,
                                      __be16 rmt_port, struct in6_addr *rmt_addr,
                                      int dif)
{
        struct hlist_node *node;
        struct sock *s = sk;
        unsigned short num = ntohs(loc_port);

        sk_for_each_from(s, node) {
                struct inet_sock *inet = inet_sk(s);

                if (sock_net(s) != sock_net(sk))
                        continue;

                if (s->sk_hash == num && s->sk_family == PF_INET6) {
                        struct ipv6_pinfo *np = inet6_sk(s);
                        if (inet->dport) {
                                if (inet->dport != rmt_port)
                                        continue;
                        }
                        if (!ipv6_addr_any(&np->daddr) &&
                            !ipv6_addr_equal(&np->daddr, rmt_addr))
                                continue;

                        if (s->sk_bound_dev_if && s->sk_bound_dev_if != dif)
                                continue;

                        if (!ipv6_addr_any(&np->rcv_saddr)) {
                                if (!ipv6_addr_equal(&np->rcv_saddr, loc_addr))
                                        continue;
                        }
                        if (!inet6_mc_check(s, loc_addr, rmt_addr))
                                continue;
                        return s;
                }
        }
        return NULL;
}

/*
 * Note: called only from the BH handler context,
 * so we don't need to lock the hashes.
 */
static int __udp6_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
                struct in6_addr *saddr, struct in6_addr *daddr,
                struct hlist_head udptable[])
{
        struct sock *sk, *sk2;
        const struct udphdr *uh = udp_hdr(skb);
        int dif;

        read_lock(&udp_hash_lock);
        sk = sk_head(&udptable[udp_hashfn(net, ntohs(uh->dest))]);
        dif = inet6_iif(skb);
        sk = udp_v6_mcast_next(sk, uh->dest, daddr, uh->source, saddr, dif);
        if (!sk) {
                kfree_skb(skb);
                goto out;
        }

        sk2 = sk;
        while ((sk2 = udp_v6_mcast_next(sk_next(sk2), uh->dest, daddr,
                                        uh->source, saddr, dif))) {
                struct sk_buff *buff = skb_clone(skb, GFP_ATOMIC);
                if (buff) {
                        bh_lock_sock(sk2);
                        if (!sock_owned_by_user(sk2))
                                udpv6_queue_rcv_skb(sk2, buff);
                        else
                                sk_add_backlog(sk2, buff);
                        bh_unlock_sock(sk2);
                }
        }
        bh_lock_sock(sk);
        if (!sock_owned_by_user(sk))
                udpv6_queue_rcv_skb(sk, skb);
        else
                sk_add_backlog(sk, skb);
        bh_unlock_sock(sk);
out:
        read_unlock(&udp_hash_lock);
        return 0;
}

static inline int udp6_csum_init(struct sk_buff *skb, struct udphdr *uh,
                                 int proto)
{
        int err;

        UDP_SKB_CB(skb)->partial_cov = 0;
        UDP_SKB_CB(skb)->cscov = skb->len;

        if (proto == IPPROTO_UDPLITE) {
                err = udplite_checksum_init(skb, uh);
                if (err)
                        return err;
        }

        if (uh->check == 0) {
                /* RFC 2460 section 8.1 says that we SHOULD log
                   this error. Well, it is reasonable.
                 */
                LIMIT_NETDEBUG(KERN_INFO "IPv6: udp checksum is 0\n");
                return 1;
        }
        if (skb->ip_summed == CHECKSUM_COMPLETE &&
            !csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr,
                             skb->len, proto, skb->csum))
                skb->ip_summed = CHECKSUM_UNNECESSARY;

        if (!skb_csum_unnecessary(skb))
                skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
                                                         &ipv6_hdr(skb)->daddr,
                                                         skb->len, proto, 0));

        return 0;
}

int __udp6_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[],
                   int proto)
{
        struct sock *sk;
        struct udphdr *uh;
        struct net_device *dev = skb->dev;
        struct in6_addr *saddr, *daddr;
        u32 ulen = 0;
        struct net *net = dev_net(skb->dev);

        if (!pskb_may_pull(skb, sizeof(struct udphdr)))
                goto short_packet;

        saddr = &ipv6_hdr(skb)->saddr;
        daddr = &ipv6_hdr(skb)->daddr;
        uh = udp_hdr(skb);

        ulen = ntohs(uh->len);
        if (ulen > skb->len)
                goto short_packet;

        if (proto == IPPROTO_UDP) {
                /* UDP validates ulen. */

                /* Check for jumbo payload */
                if (ulen == 0)
                        ulen = skb->len;

                if (ulen < sizeof(*uh))
                        goto short_packet;

                if (ulen < skb->len) {
                        if (pskb_trim_rcsum(skb, ulen))
                                goto short_packet;
                        saddr = &ipv6_hdr(skb)->saddr;
                        daddr = &ipv6_hdr(skb)->daddr;
                        uh = udp_hdr(skb);
                }
        }

        if (udp6_csum_init(skb, uh, proto))
                goto discard;

        /*
         *      Multicast receive code
         */
        if (ipv6_addr_is_multicast(daddr))
                return __udp6_lib_mcast_deliver(net, skb,
                                saddr, daddr, udptable);

        /* Unicast */

        /*
         * check socket cache ... must talk to Alan about his plans
         * for sock caches... i'll skip this for now.
         */
        sk = __udp6_lib_lookup_skb(skb, uh->source, uh->dest, udptable);

        if (sk == NULL) {
                if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
                        goto discard;

                if (udp_lib_checksum_complete(skb))
                        goto discard;
                UDP6_INC_STATS_BH(net, UDP_MIB_NOPORTS,
                                proto == IPPROTO_UDPLITE);

                icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0, dev);

                kfree_skb(skb);
                return 0;
        }

        /* deliver */

        bh_lock_sock(sk);
        if (!sock_owned_by_user(sk))
                udpv6_queue_rcv_skb(sk, skb);
        else
                sk_add_backlog(sk, skb);
        bh_unlock_sock(sk);
        sock_put(sk);
        return 0;

short_packet:
        LIMIT_NETDEBUG(KERN_DEBUG "UDP%sv6: short packet: %d/%u\n",
                       proto == IPPROTO_UDPLITE ? "-Lite" : "",
                       ulen, skb->len);

discard:
        UDP6_INC_STATS_BH(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
        kfree_skb(skb);
        return 0;
}

static __inline__ int udpv6_rcv(struct sk_buff *skb)
{
        return __udp6_lib_rcv(skb, udp_hash, IPPROTO_UDP);
}

/*
 * Throw away all pending data and cancel the corking. Socket is locked.
 */
static void udp_v6_flush_pending_frames(struct sock *sk)
{
        struct udp_sock *up = udp_sk(sk);

        if (up->pending == AF_INET)
                udp_flush_pending_frames(sk);
        else if (up->pending) {
                up->len = 0;
                up->pending = 0;
                ip6_flush_pending_frames(sk);
        }
}

/*
 *      Sending
 */

static int udp_v6_push_pending_frames(struct sock *sk)
{
        struct sk_buff *skb;
        struct udphdr *uh;
        struct udp_sock  *up = udp_sk(sk);
        struct inet_sock *inet = inet_sk(sk);
        struct flowi *fl = &inet->cork.fl;
        int err = 0;
        int is_udplite = IS_UDPLITE(sk);
        __wsum csum = 0;

        /* Grab the skbuff where UDP header space exists. */
        if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
                goto out;

        /*
         * Create a UDP header
         */
        uh = udp_hdr(skb);
        uh->source = fl->fl_ip_sport;
        uh->dest = fl->fl_ip_dport;
        uh->len = htons(up->len);
        uh->check = 0;

        if (is_udplite)
                csum = udplite_csum_outgoing(sk, skb);
         else
                csum = udp_csum_outgoing(sk, skb);

        /* add protocol-dependent pseudo-header */
        uh->check = csum_ipv6_magic(&fl->fl6_src, &fl->fl6_dst,
                                    up->len, fl->proto, csum   );
        if (uh->check == 0)
                uh->check = CSUM_MANGLED_0;

        err = ip6_push_pending_frames(sk);
out:
        up->len = 0;
        up->pending = 0;
        if (!err)
                UDP6_INC_STATS_USER(sock_net(sk),
                                UDP_MIB_OUTDATAGRAMS, is_udplite);
        return err;
}

int udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
                  struct msghdr *msg, size_t len)
{
        struct ipv6_txoptions opt_space;
        struct udp_sock *up = udp_sk(sk);
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) msg->msg_name;
        struct in6_addr *daddr, *final_p = NULL, final;
        struct ipv6_txoptions *opt = NULL;
        struct ip6_flowlabel *flowlabel = NULL;
        struct flowi fl;
        struct dst_entry *dst;
        int addr_len = msg->msg_namelen;
        int ulen = len;
        int hlimit = -1;
        int tclass = -1;
        int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
        int err;
        int connected = 0;
        int is_udplite = IS_UDPLITE(sk);
        int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);

        /* destination address check */
        if (sin6) {
                if (addr_len < offsetof(struct sockaddr, sa_data))
                        return -EINVAL;

                switch (sin6->sin6_family) {
                case AF_INET6:
                        if (addr_len < SIN6_LEN_RFC2133)
                                return -EINVAL;
                        daddr = &sin6->sin6_addr;
                        break;
                case AF_INET:
                        goto do_udp_sendmsg;
                case AF_UNSPEC:
                        msg->msg_name = sin6 = NULL;
                        msg->msg_namelen = addr_len = 0;
                        daddr = NULL;
                        break;
                default:
                        return -EINVAL;
                }
        } else if (!up->pending) {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;
                daddr = &np->daddr;
        } else
                daddr = NULL;

        if (daddr) {
                if (ipv6_addr_v4mapped(daddr)) {
                        struct sockaddr_in sin;
                        sin.sin_family = AF_INET;
                        sin.sin_port = sin6 ? sin6->sin6_port : inet->dport;
                        sin.sin_addr.s_addr = daddr->s6_addr32[3];
                        msg->msg_name = &sin;
                        msg->msg_namelen = sizeof(sin);
do_udp_sendmsg:
                        if (__ipv6_only_sock(sk))
                                return -ENETUNREACH;
                        return udp_sendmsg(iocb, sk, msg, len);
                }
        }

        if (up->pending == AF_INET)
                return udp_sendmsg(iocb, sk, msg, len);

        /* Rough check on arithmetic overflow,
           better check is made in ip6_append_data().
           */
        if (len > INT_MAX - sizeof(struct udphdr))
                return -EMSGSIZE;

        if (up->pending) {
                /*
                 * There are pending frames.
                 * The socket lock must be held while it's corked.
                 */
                lock_sock(sk);
                if (likely(up->pending)) {
                        if (unlikely(up->pending != AF_INET6)) {
                                release_sock(sk);
                                return -EAFNOSUPPORT;
                        }
                        dst = NULL;
                        goto do_append_data;
                }
                release_sock(sk);
        }
        ulen += sizeof(struct udphdr);

        memset(&fl, 0, sizeof(fl));

        if (sin6) {
                if (sin6->sin6_port == 0)
                        return -EINVAL;

                fl.fl_ip_dport = sin6->sin6_port;
                daddr = &sin6->sin6_addr;

                if (np->sndflow) {
                        fl.fl6_flowlabel = sin6->sin6_flowinfo&IPV6_FLOWINFO_MASK;
                        if (fl.fl6_flowlabel&IPV6_FLOWLABEL_MASK) {
                                flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
                                if (flowlabel == NULL)
                                        return -EINVAL;
                                daddr = &flowlabel->dst;
                        }
                }

                /*
                 * Otherwise it will be difficult to maintain
                 * sk->sk_dst_cache.
                 */
                if (sk->sk_state == TCP_ESTABLISHED &&
                    ipv6_addr_equal(daddr, &np->daddr))
                        daddr = &np->daddr;

                if (addr_len >= sizeof(struct sockaddr_in6) &&
                    sin6->sin6_scope_id &&
                    ipv6_addr_type(daddr)&IPV6_ADDR_LINKLOCAL)
                        fl.oif = sin6->sin6_scope_id;
        } else {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;

                fl.fl_ip_dport = inet->dport;
                daddr = &np->daddr;
                fl.fl6_flowlabel = np->flow_label;
                connected = 1;
        }

        if (!fl.oif)
                fl.oif = sk->sk_bound_dev_if;

        if (msg->msg_controllen) {
                opt = &opt_space;
                memset(opt, 0, sizeof(struct ipv6_txoptions));
                opt->tot_len = sizeof(*opt);

                err = datagram_send_ctl(sock_net(sk), msg, &fl, opt, &hlimit, &tclass);
                if (err < 0) {
                        fl6_sock_release(flowlabel);
                        return err;
                }
                if ((fl.fl6_flowlabel&IPV6_FLOWLABEL_MASK) && !flowlabel) {
                        flowlabel = fl6_sock_lookup(sk, fl.fl6_flowlabel);
                        if (flowlabel == NULL)
                                return -EINVAL;
                }
                if (!(opt->opt_nflen|opt->opt_flen))
                        opt = NULL;
                connected = 0;
        }
        if (opt == NULL)
                opt = np->opt;
        if (flowlabel)
                opt = fl6_merge_options(&opt_space, flowlabel, opt);
        opt = ipv6_fixup_options(&opt_space, opt);

        fl.proto = sk->sk_protocol;
        if (!ipv6_addr_any(daddr))
                ipv6_addr_copy(&fl.fl6_dst, daddr);
        else
                fl.fl6_dst.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
        if (ipv6_addr_any(&fl.fl6_src) && !ipv6_addr_any(&np->saddr))
                ipv6_addr_copy(&fl.fl6_src, &np->saddr);
        fl.fl_ip_sport = inet->sport;

        /* merge ip6_build_xmit from ip6_output */
        if (opt && opt->srcrt) {
                struct rt0_hdr *rt0 = (struct rt0_hdr *) opt->srcrt;
                ipv6_addr_copy(&final, &fl.fl6_dst);
                ipv6_addr_copy(&fl.fl6_dst, rt0->addr);
                final_p = &final;
                connected = 0;
        }

        if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst)) {
                fl.oif = np->mcast_oif;
                connected = 0;
        }

        security_sk_classify_flow(sk, &fl);

        err = ip6_sk_dst_lookup(sk, &dst, &fl);
        if (err)
                goto out;
        if (final_p)
                ipv6_addr_copy(&fl.fl6_dst, final_p);

        if ((err = __xfrm_lookup(&dst, &fl, sk, XFRM_LOOKUP_WAIT)) < 0) {
                if (err == -EREMOTE)
                        err = ip6_dst_blackhole(sk, &dst, &fl);
                if (err < 0)
                        goto out;
        }

        if (hlimit < 0) {
                if (ipv6_addr_is_multicast(&fl.fl6_dst))
                        hlimit = np->mcast_hops;
                else
                        hlimit = np->hop_limit;
                if (hlimit < 0)
                        hlimit = ip6_dst_hoplimit(dst);
        }

        if (tclass < 0) {
                tclass = np->tclass;
                if (tclass < 0)
                        tclass = 0;
        }

        if (msg->msg_flags&MSG_CONFIRM)
                goto do_confirm;
back_from_confirm:

        lock_sock(sk);
        if (unlikely(up->pending)) {
                /* The socket is already corked while preparing it. */
                /* ... which is an evident application bug. --ANK */
                release_sock(sk);

                LIMIT_NETDEBUG(KERN_DEBUG "udp cork app bug 2\n");
                err = -EINVAL;
                goto out;
        }

        up->pending = AF_INET6;

do_append_data:
        up->len += ulen;
        getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
        err = ip6_append_data(sk, getfrag, msg->msg_iov, ulen,
                sizeof(struct udphdr), hlimit, tclass, opt, &fl,
                (struct rt6_info*)dst,
                corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
        if (err)
                udp_v6_flush_pending_frames(sk);
        else if (!corkreq)
                err = udp_v6_push_pending_frames(sk);
        else if (unlikely(skb_queue_empty(&sk->sk_write_queue)))
                up->pending = 0;

        if (dst) {
                if (connected) {
                        ip6_dst_store(sk, dst,
                                      ipv6_addr_equal(&fl.fl6_dst, &np->daddr) ?
                                      &np->daddr : NULL,
#ifdef CONFIG_IPV6_SUBTREES
                                      ipv6_addr_equal(&fl.fl6_src, &np->saddr) ?
                                      &np->saddr :
#endif
                                      NULL);
                } else {
                        dst_release(dst);
                }
                dst = NULL;
        }

        if (err > 0)
                err = np->recverr ? net_xmit_errno(err) : 0;
        release_sock(sk);
out:
        dst_release(dst);
        fl6_sock_release(flowlabel);
        if (!err)
                return len;
        /*
         * ENOBUFS = no kernel mem, SOCK_NOSPACE = no sndbuf space.  Reporting
         * ENOBUFS might not be good (it's not tunable per se), but otherwise
         * we don't have a good statistic (IpOutDiscards but it can be too many
         * things).  We could add another new stat but at least for now that
         * seems like overkill.
         */
        if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
                UDP6_INC_STATS_USER(sock_net(sk),
                                UDP_MIB_SNDBUFERRORS, is_udplite);
        }
        return err;

do_confirm:
        dst_confirm(dst);
        if (!(msg->msg_flags&MSG_PROBE) || len)
                goto back_from_confirm;
        err = 0;
        goto out;
}

void udpv6_destroy_sock(struct sock *sk)
{
        lock_sock(sk);
        udp_v6_flush_pending_frames(sk);
        release_sock(sk);

        inet6_destroy_sock(sk);
}

/*
 *      Socket option code for UDP
 */
int udpv6_setsockopt(struct sock *sk, int level, int optname,
                     char __user *optval, int optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_setsockopt(sk, level, optname, optval, optlen,
                                          udp_v6_push_pending_frames);
        return ipv6_setsockopt(sk, level, optname, optval, optlen);
}

#ifdef CONFIG_COMPAT
int compat_udpv6_setsockopt(struct sock *sk, int level, int optname,
                            char __user *optval, int optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_setsockopt(sk, level, optname, optval, optlen,
                                          udp_v6_push_pending_frames);
        return compat_ipv6_setsockopt(sk, level, optname, optval, optlen);
}
#endif

int udpv6_getsockopt(struct sock *sk, int level, int optname,
                     char __user *optval, int __user *optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_getsockopt(sk, level, optname, optval, optlen);
        return ipv6_getsockopt(sk, level, optname, optval, optlen);
}

#ifdef CONFIG_COMPAT
int compat_udpv6_getsockopt(struct sock *sk, int level, int optname,
                            char __user *optval, int __user *optlen)
{
        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
                return udp_lib_getsockopt(sk, level, optname, optval, optlen);
        return compat_ipv6_getsockopt(sk, level, optname, optval, optlen);
}
#endif

static struct inet6_protocol udpv6_protocol = {
        .handler        =       udpv6_rcv,
        .err_handler    =       udpv6_err,
        .flags          =       INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
};

/* ------------------------------------------------------------------------ */
#ifdef CONFIG_PROC_FS

static void udp6_sock_seq_show(struct seq_file *seq, struct sock *sp, int bucket)
{
        struct inet_sock *inet = inet_sk(sp);
        struct ipv6_pinfo *np = inet6_sk(sp);
        struct in6_addr *dest, *src;
        __u16 destp, srcp;

        dest  = &np->daddr;
        src   = &np->rcv_saddr;
        destp = ntohs(inet->dport);
        srcp  = ntohs(inet->sport);
        seq_printf(seq,
                   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
                   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d\n",
                   bucket,
                   src->s6_addr32[0], src->s6_addr32[1],
                   src->s6_addr32[2], src->s6_addr32[3], srcp,
                   dest->s6_addr32[0], dest->s6_addr32[1],
                   dest->s6_addr32[2], dest->s6_addr32[3], destp,
                   sp->sk_state,
                   atomic_read(&sp->sk_wmem_alloc),
                   atomic_read(&sp->sk_rmem_alloc),
                   0, 0L, 0,
                   sock_i_uid(sp), 0,
                   sock_i_ino(sp),
                   atomic_read(&sp->sk_refcnt), sp,
                   atomic_read(&sp->sk_drops));
}

int udp6_seq_show(struct seq_file *seq, void *v)
{
        if (v == SEQ_START_TOKEN)
                seq_printf(seq,
                           "  sl  "
                           "local_address                         "
                           "remote_address                        "
                           "st tx_queue rx_queue tr tm->when retrnsmt"
                           "   uid  timeout inode ref pointer drops\n");
        else
                udp6_sock_seq_show(seq, v, ((struct udp_iter_state *)seq->private)->bucket);
        return 0;
}

static struct udp_seq_afinfo udp6_seq_afinfo = {
        .name           = "udp6",
        .family         = AF_INET6,
        .hashtable      = udp_hash,
        .seq_fops       = {
                .owner  =       THIS_MODULE,
        },
        .seq_ops        = {
                .show           = udp6_seq_show,
        },
};

int udp6_proc_init(struct net *net)
{
        return udp_proc_register(net, &udp6_seq_afinfo);
}

void udp6_proc_exit(struct net *net) {
        udp_proc_unregister(net, &udp6_seq_afinfo);
}
#endif /* CONFIG_PROC_FS */

/* ------------------------------------------------------------------------ */

struct proto udpv6_prot = {
        .name              = "UDPv6",
        .owner             = THIS_MODULE,
        .close             = udp_lib_close,
        .connect           = ip6_datagram_connect,
        .disconnect        = udp_disconnect,
        .ioctl             = udp_ioctl,
        .destroy           = udpv6_destroy_sock,
        .setsockopt        = udpv6_setsockopt,
        .getsockopt        = udpv6_getsockopt,
        .sendmsg           = udpv6_sendmsg,
        .recvmsg           = udpv6_recvmsg,
        .backlog_rcv       = udpv6_queue_rcv_skb,
        .hash              = udp_lib_hash,
        .unhash            = udp_lib_unhash,
        .get_port          = udp_v6_get_port,
        .memory_allocated  = &udp_memory_allocated,
        .sysctl_mem        = sysctl_udp_mem,
        .sysctl_wmem       = &sysctl_udp_wmem_min,
        .sysctl_rmem       = &sysctl_udp_rmem_min,
        .obj_size          = sizeof(struct udp6_sock),
        .h.udp_hash        = udp_hash,
#ifdef CONFIG_COMPAT
        .compat_setsockopt = compat_udpv6_setsockopt,
        .compat_getsockopt = compat_udpv6_getsockopt,
#endif
};

static struct inet_protosw udpv6_protosw = {
        .type =      SOCK_DGRAM,
        .protocol =  IPPROTO_UDP,
        .prot =      &udpv6_prot,
        .ops =       &inet6_dgram_ops,
        .capability =-1,
        .no_check =  UDP_CSUM_DEFAULT,
        .flags =     INET_PROTOSW_PERMANENT,
};


int __init udpv6_init(void)
{
        int ret;

        ret = inet6_add_protocol(&udpv6_protocol, IPPROTO_UDP);
        if (ret)
                goto out;

        ret = inet6_register_protosw(&udpv6_protosw);
        if (ret)
                goto out_udpv6_protocol;
out:
        return ret;

out_udpv6_protocol:
        inet6_del_protocol(&udpv6_protocol, IPPROTO_UDP);
        goto out;
}

void udpv6_exit(void)
{
        inet6_unregister_protosw(&udpv6_protosw);
        inet6_del_protocol(&udpv6_protocol, IPPROTO_UDP);
}

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