/*
   *	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 <linux/slab.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 ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)
  {
  	const struct in6_addr *sk_rcv_saddr6 = &inet6_sk(sk)->rcv_saddr;
  	const struct in6_addr *sk2_rcv_saddr6 = inet6_rcv_saddr(sk2);

  	__be32 sk1_rcv_saddr = inet_sk(sk)->inet_rcv_saddr;

  	__be32 sk2_rcv_saddr = inet_rcv_saddr(sk2);

  	int sk_ipv6only = ipv6_only_sock(sk);
  	int sk2_ipv6only = inet_v6_ipv6only(sk2);
  	int addr_type = ipv6_addr_type(sk_rcv_saddr6);
  	int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
  
  	/* if both are mapped, treat as IPv4 */
  	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED)

  		return (!sk2_ipv6only &&

  			(!sk1_rcv_saddr || !sk2_rcv_saddr ||
  			  sk1_rcv_saddr == sk2_rcv_saddr));

  
  	if (addr_type2 == IPV6_ADDR_ANY &&
  	    !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
  		return 1;
  
  	if (addr_type == IPV6_ADDR_ANY &&
  	    !(sk_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
  		return 1;
  
  	if (sk2_rcv_saddr6 &&
  	    ipv6_addr_equal(sk_rcv_saddr6, sk2_rcv_saddr6))
  		return 1;
  
  	return 0;
  }

  static unsigned int udp6_portaddr_hash(struct net *net,
  				       const struct in6_addr *addr6,
  				       unsigned int port)
  {
  	unsigned int hash, mix = net_hash_mix(net);
  
  	if (ipv6_addr_any(addr6))
  		hash = jhash_1word(0, mix);

  	else if (ipv6_addr_v4mapped(addr6))

  		hash = jhash_1word((__force u32)addr6->s6_addr32[3], mix);

  	else

  		hash = jhash2((__force u32 *)addr6->s6_addr32, 4, mix);

  
  	return hash ^ port;
  }

  int udp_v6_get_port(struct sock *sk, unsigned short snum)

  {

  	unsigned int hash2_nulladdr =
  		udp6_portaddr_hash(sock_net(sk), &in6addr_any, snum);
  	unsigned int hash2_partial = 
  		udp6_portaddr_hash(sock_net(sk), &inet6_sk(sk)->rcv_saddr, 0);

  	/* precompute partial secondary hash */

  	udp_sk(sk)->udp_portaddr_hash = hash2_partial;
  	return udp_lib_get_port(sk, snum, ipv6_rcv_saddr_equal, hash2_nulladdr);

  }

  static void udp_v6_rehash(struct sock *sk)
  {
  	u16 new_hash = udp6_portaddr_hash(sock_net(sk),
  					  &inet6_sk(sk)->rcv_saddr,
  					  inet_sk(sk)->inet_num);
  
  	udp_lib_rehash(sk, new_hash);
  }

  static inline int compute_score(struct sock *sk, struct net *net,
  				unsigned short hnum,
  				struct in6_addr *saddr, __be16 sport,
  				struct in6_addr *daddr, __be16 dport,
  				int dif)
  {
  	int score = -1;

  	if (net_eq(sock_net(sk), net) && udp_sk(sk)->udp_port_hash == hnum &&

  			sk->sk_family == PF_INET6) {
  		struct ipv6_pinfo *np = inet6_sk(sk);
  		struct inet_sock *inet = inet_sk(sk);
  
  		score = 0;

  		if (inet->inet_dport) {
  			if (inet->inet_dport != sport)

  				return -1;
  			score++;
  		}
  		if (!ipv6_addr_any(&np->rcv_saddr)) {
  			if (!ipv6_addr_equal(&np->rcv_saddr, daddr))
  				return -1;
  			score++;
  		}
  		if (!ipv6_addr_any(&np->daddr)) {
  			if (!ipv6_addr_equal(&np->daddr, saddr))
  				return -1;
  			score++;
  		}
  		if (sk->sk_bound_dev_if) {
  			if (sk->sk_bound_dev_if != dif)
  				return -1;
  			score++;
  		}
  	}
  	return score;
  }

  #define SCORE2_MAX (1 + 1 + 1)
  static inline int compute_score2(struct sock *sk, struct net *net,
  				const struct in6_addr *saddr, __be16 sport,
  				const struct in6_addr *daddr, unsigned short hnum,
  				int dif)
  {
  	int score = -1;
  
  	if (net_eq(sock_net(sk), net) && udp_sk(sk)->udp_port_hash == hnum &&
  			sk->sk_family == PF_INET6) {
  		struct ipv6_pinfo *np = inet6_sk(sk);
  		struct inet_sock *inet = inet_sk(sk);
  
  		if (!ipv6_addr_equal(&np->rcv_saddr, daddr))
  			return -1;
  		score = 0;
  		if (inet->inet_dport) {
  			if (inet->inet_dport != sport)
  				return -1;
  			score++;
  		}
  		if (!ipv6_addr_any(&np->daddr)) {
  			if (!ipv6_addr_equal(&np->daddr, saddr))
  				return -1;
  			score++;
  		}
  		if (sk->sk_bound_dev_if) {
  			if (sk->sk_bound_dev_if != dif)
  				return -1;
  			score++;
  		}
  	}
  	return score;
  }

  
  /* called with read_rcu_lock() */
  static struct sock *udp6_lib_lookup2(struct net *net,
  		const struct in6_addr *saddr, __be16 sport,
  		const struct in6_addr *daddr, unsigned int hnum, int dif,
  		struct udp_hslot *hslot2, unsigned int slot2)
  {
  	struct sock *sk, *result;
  	struct hlist_nulls_node *node;
  	int score, badness;
  
  begin:
  	result = NULL;
  	badness = -1;
  	udp_portaddr_for_each_entry_rcu(sk, node, &hslot2->head) {
  		score = compute_score2(sk, net, saddr, sport,
  				      daddr, hnum, dif);
  		if (score > badness) {
  			result = sk;
  			badness = score;
  			if (score == SCORE2_MAX)
  				goto exact_match;
  		}
  	}
  	/*
  	 * if the nulls value we got at the end of this lookup is
  	 * not the expected one, we must restart lookup.
  	 * We probably met an item that was moved to another chain.
  	 */
  	if (get_nulls_value(node) != slot2)
  		goto begin;
  
  	if (result) {
  exact_match:
  		if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
  			result = NULL;
  		else if (unlikely(compute_score2(result, net, saddr, sport,
  				  daddr, hnum, dif) < badness)) {
  			sock_put(result);
  			goto begin;
  		}
  	}
  	return result;
  }

  static struct sock *__udp6_lib_lookup(struct net *net,
  				      struct in6_addr *saddr, __be16 sport,

  				      struct in6_addr *daddr, __be16 dport,

  				      int dif, struct udp_table *udptable)

  {

  	struct sock *sk, *result;

  	struct hlist_nulls_node *node;

  	unsigned short hnum = ntohs(dport);

  	unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
  	struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];

  	int score, badness;

  	rcu_read_lock();

  	if (hslot->count > 10) {
  		hash2 = udp6_portaddr_hash(net, daddr, hnum);
  		slot2 = hash2 & udptable->mask;
  		hslot2 = &udptable->hash2[slot2];
  		if (hslot->count < hslot2->count)
  			goto begin;
  
  		result = udp6_lib_lookup2(net, saddr, sport,
  					  daddr, hnum, dif,
  					  hslot2, slot2);
  		if (!result) {
  			hash2 = udp6_portaddr_hash(net, &in6addr_any, hnum);
  			slot2 = hash2 & udptable->mask;
  			hslot2 = &udptable->hash2[slot2];
  			if (hslot->count < hslot2->count)
  				goto begin;

  			result = udp6_lib_lookup2(net, saddr, sport,
  						  &in6addr_any, hnum, dif,

  						  hslot2, slot2);
  		}
  		rcu_read_unlock();
  		return result;
  	}

  begin:
  	result = NULL;
  	badness = -1;

  	sk_nulls_for_each_rcu(sk, node, &hslot->head) {

  		score = compute_score(sk, net, hnum, saddr, sport, daddr, dport, dif);
  		if (score > badness) {
  			result = sk;
  			badness = score;

  		}
  	}

  	/*
  	 * if the nulls value we got at the end of this lookup is
  	 * not the expected one, we must restart lookup.
  	 * We probably met an item that was moved to another chain.
  	 */

  	if (get_nulls_value(node) != slot)

  		goto begin;

  	if (result) {
  		if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
  			result = NULL;
  		else if (unlikely(compute_score(result, net, hnum, saddr, sport,
  					daddr, dport, dif) < badness)) {
  			sock_put(result);
  			goto begin;
  		}
  	}
  	rcu_read_unlock();

  	return result;
  }

  static struct sock *__udp6_lib_lookup_skb(struct sk_buff *skb,
  					  __be16 sport, __be16 dport,

  					  struct udp_table *udptable)

  {

  	struct sock *sk;

  	struct ipv6hdr *iph = ipv6_hdr(skb);

  	if (unlikely(sk = skb_steal_sock(skb)))
  		return sk;

  	return __udp6_lib_lookup(dev_net(skb_dst(skb)->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;

  	int peeked;

  	int err;
  	int is_udplite = IS_UDPLITE(sk);

  	int is_udp4;

  	bool slow;

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

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

  	if (np->rxpmtu && np->rxopt.bits.rxpmtu)
  		return ipv6_recv_rxpmtu(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);

  	if (len > ulen)
  		len = ulen;
  	else if (len < ulen)

  		msg->msg_flags |= MSG_TRUNC;

  	is_udp4 = (skb->protocol == htons(ETH_P_IP));

  	/*

  	 * 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 (len < 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,len);

  	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) {
  		if (is_udp4)
  			UDP_INC_STATS_USER(sock_net(sk),
  					UDP_MIB_INDATAGRAMS, is_udplite);
  		else
  			UDP6_INC_STATS_USER(sock_net(sk),
  					UDP_MIB_INDATAGRAMS, is_udplite);
  	}

  	sock_recv_ts_and_drops(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 (is_udp4)

  			ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr,
  					       &sin6->sin6_addr);

  		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 (is_udp4) {

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

  	}

  	err = len;

  	if (flags & MSG_TRUNC)

  		err = ulen;

  
  out_free:

  	skb_free_datagram_locked(sk, skb);

  out:
  	return err;
  
  csum_copy_err:

  	slow = lock_sock_fast(sk);

  	if (!skb_kill_datagram(sk, skb, flags)) {
  		if (is_udp4)
  			UDP_INC_STATS_USER(sock_net(sk),
  					UDP_MIB_INERRORS, is_udplite);
  		else
  			UDP6_INC_STATS_USER(sock_net(sk),
  					UDP_MIB_INERRORS, is_udplite);
  	}

  	unlock_sock_fast(sk, slow);

  	if (flags & MSG_DONTWAIT)

  		return -EAGAIN;

  	goto try_again;
  }

  void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

  		    u8 type, u8 code, int offset, __be32 info,

  		    struct udp_table *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, u8 type,
  				 u8 code, int offset, __be32 info     )

  {

  	__udp6_lib_err(skb, opt, type, code, offset, info, &udp_table);

  }
  
  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
  ",
  				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
  ",
  				       UDP_SKB_CB(skb)->cscov, up->pcrlen);
  			goto drop;
  		}

  	}

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

  	if ((rc = ip_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);

  		goto drop_no_sk_drops_inc;

  	}

  	return 0;

  drop:

  	atomic_inc(&sk->sk_drops);
  drop_no_sk_drops_inc:

  	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 net *net, struct sock *sk,

  				      __be16 loc_port, struct in6_addr *loc_addr,
  				      __be16 rmt_port, struct in6_addr *rmt_addr,

  				      int dif)
  {

  	struct hlist_nulls_node *node;

  	struct sock *s = sk;
  	unsigned short num = ntohs(loc_port);

  	sk_nulls_for_each_from(s, node) {

  		struct inet_sock *inet = inet_sk(s);

  		if (!net_eq(sock_net(s), net))

  			continue;

  		if (udp_sk(s)->udp_port_hash == num &&
  		    s->sk_family == PF_INET6) {

  			struct ipv6_pinfo *np = inet6_sk(s);

  			if (inet->inet_dport) {
  				if (inet->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;
  }

  static void flush_stack(struct sock **stack, unsigned int count,
  			struct sk_buff *skb, unsigned int final)
  {
  	unsigned int i;
  	struct sock *sk;
  	struct sk_buff *skb1;
  
  	for (i = 0; i < count; i++) {
  		skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC);

  		sk = stack[i];

  		if (skb1) {

  			if (sk_rcvqueues_full(sk, skb)) {
  				kfree_skb(skb1);
  				goto drop;
  			}

  			bh_lock_sock(sk);
  			if (!sock_owned_by_user(sk))
  				udpv6_queue_rcv_skb(sk, skb1);

  			else if (sk_add_backlog(sk, skb1)) {

  				kfree_skb(skb1);
  				bh_unlock_sock(sk);
  				goto drop;
  			}

  			bh_unlock_sock(sk);

  			continue;

  		}

  drop:
  		atomic_inc(&sk->sk_drops);
  		UDP6_INC_STATS_BH(sock_net(sk),
  				UDP_MIB_RCVBUFERRORS, IS_UDPLITE(sk));
  		UDP6_INC_STATS_BH(sock_net(sk),
  				UDP_MIB_INERRORS, IS_UDPLITE(sk));

  	}
  }

  /*
   * 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 udp_table *udptable)

  {

  	struct sock *sk, *stack[256 / sizeof(struct sock *)];

  	const struct udphdr *uh = udp_hdr(skb);

  	struct udp_hslot *hslot = udp_hashslot(udptable, net, ntohs(uh->dest));

  	int dif;

  	unsigned int i, count = 0;

  	spin_lock(&hslot->lock);

  	sk = sk_nulls_head(&hslot->head);

  	dif = inet6_iif(skb);

  	sk = udp_v6_mcast_next(net, sk, uh->dest, daddr, uh->source, saddr, dif);

  	while (sk) {
  		stack[count++] = sk;
  		sk = udp_v6_mcast_next(net, sk_nulls_next(sk), uh->dest, daddr,
  				       uh->source, saddr, dif);
  		if (unlikely(count == ARRAY_SIZE(stack))) {
  			if (!sk)
  				break;
  			flush_stack(stack, count, skb, ~0);
  			count = 0;

  		}

  	}

  	/*
  	 * before releasing the lock, we must take reference on sockets
  	 */
  	for (i = 0; i < count; i++)
  		sock_hold(stack[i]);

  	spin_unlock(&hslot->lock);

  
  	if (count) {
  		flush_stack(stack, count, skb, count - 1);
  
  		for (i = 0; i < count; i++)
  			sock_put(stack[i]);
  	} else {
  		kfree_skb(skb);
  	}

  	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
  ");
  		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 udp_table *udptable,

  		   int proto)

  {

  	struct net *net = dev_net(skb->dev);

  	struct sock *sk;

  	struct udphdr *uh;

  	struct in6_addr *saddr, *daddr;
  	u32 ulen = 0;
  
  	if (!pskb_may_pull(skb, sizeof(struct udphdr)))

  		goto discard;

  	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);

  
  		kfree_skb(skb);

  		return 0;

  	}

  	/* deliver */

  	if (sk_rcvqueues_full(sk, skb)) {
  		sock_put(sk);
  		goto discard;
  	}

  	bh_lock_sock(sk);

  	if (!sock_owned_by_user(sk))
  		udpv6_queue_rcv_skb(sk, skb);

  	else if (sk_add_backlog(sk, skb)) {

  		atomic_inc(&sk->sk_drops);
  		bh_unlock_sock(sk);
  		sock_put(sk);
  		goto discard;
  	}

  	bh_unlock_sock(sk);

  	sock_put(sk);

  	return 0;

  short_packet:

  	LIMIT_NETDEBUG(KERN_DEBUG "UDP%sv6: short packet: From [%pI6c]:%u %d/%d to [%pI6c]:%u
  ",

  		       proto == IPPROTO_UDPLITE ? "-Lite" : "",

  		       saddr,
  		       ntohs(uh->source),
  		       ulen,
  		       skb->len,
  		       daddr,
  		       ntohs(uh->dest));

  
  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_table, 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);

  	}

  }

  /**
   * 	udp6_hwcsum_outgoing  -  handle outgoing HW checksumming
   * 	@sk: 	socket we are sending on
   * 	@skb: 	sk_buff containing the filled-in UDP header
   * 	        (checksum field must be zeroed out)
   */
  static void udp6_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
  				 const struct in6_addr *saddr,
  				 const struct in6_addr *daddr, int len)
  {
  	unsigned int offset;
  	struct udphdr *uh = udp_hdr(skb);
  	__wsum csum = 0;
  
  	if (skb_queue_len(&sk->sk_write_queue) == 1) {
  		/* Only one fragment on the socket.  */
  		skb->csum_start = skb_transport_header(skb) - skb->head;
  		skb->csum_offset = offsetof(struct udphdr, check);
  		uh->check = ~csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP, 0);
  	} else {
  		/*
  		 * HW-checksum won't work as there are two or more
  		 * fragments on the socket so that all csums of sk_buffs
  		 * should be together
  		 */
  		offset = skb_transport_offset(skb);
  		skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
  
  		skb->ip_summed = CHECKSUM_NONE;
  
  		skb_queue_walk(&sk->sk_write_queue, skb) {
  			csum = csum_add(csum, skb->csum);
  		}
  
  		uh->check = csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP,
  					    csum);
  		if (uh->check == 0)
  			uh->check = CSUM_MANGLED_0;
  	}
  }

  /*
   *	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 if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
  		udp6_hwcsum_outgoing(sk, skb, &fl->fl6_src, &fl->fl6_dst,
  				     up->len);
  		goto send;
  	} 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;

  send:

  	err = ip6_push_pending_frames(sk);

  	if (err) {
  		if (err == -ENOBUFS && !inet6_sk(sk)->recverr) {
  			UDP6_INC_STATS_USER(sock_net(sk),
  					    UDP_MIB_SNDBUFERRORS, is_udplite);
  			err = 0;
  		}
  	} else
  		UDP6_INC_STATS_USER(sock_net(sk),
  				    UDP_MIB_OUTDATAGRAMS, is_udplite);

  out:
  	up->len = 0;
  	up->pending = 0;
  	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, 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 dontfrag = -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->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->inet_dport;

  		daddr = &np->daddr;

  		fl.fl6_flowlabel = np->flow_label;

  		connected = 1;

  	}

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

  	if (!fl.oif)
  		fl.oif = np->sticky_pktinfo.ipi6_ifindex;

  	fl.mark = sk->sk_mark;

  	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, &dontfrag);

  		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->inet_sport;

  	final_p = fl6_update_dst(&fl, opt, &final);
  	if (final_p)

  		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);

  	err = __xfrm_lookup(sock_net(sk), &dst, &fl, sk, XFRM_LOOKUP_WAIT);
  	if (err < 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 (dontfrag < 0)
  		dontfrag = np->dontfrag;

  	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
  ");

  		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, dontfrag);

  	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, unsigned 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, unsigned 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 int udp6_ufo_send_check(struct sk_buff *skb)
  {
  	struct ipv6hdr *ipv6h;
  	struct udphdr *uh;
  
  	if (!pskb_may_pull(skb, sizeof(*uh)))
  		return -EINVAL;
  
  	ipv6h = ipv6_hdr(skb);
  	uh = udp_hdr(skb);
  
  	uh->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr, skb->len,
  				     IPPROTO_UDP, 0);
  	skb->csum_start = skb_transport_header(skb) - skb->head;
  	skb->csum_offset = offsetof(struct udphdr, check);
  	skb->ip_summed = CHECKSUM_PARTIAL;
  	return 0;
  }
  
  static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, int features)
  {
  	struct sk_buff *segs = ERR_PTR(-EINVAL);
  	unsigned int mss;
  	unsigned int unfrag_ip6hlen, unfrag_len;
  	struct frag_hdr *fptr;
  	u8 *mac_start, *prevhdr;
  	u8 nexthdr;
  	u8 frag_hdr_sz = sizeof(struct frag_hdr);
  	int offset;
  	__wsum csum;
  
  	mss = skb_shinfo(skb)->gso_size;
  	if (unlikely(skb->len <= mss))
  		goto out;
  
  	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  		/* Packet is from an untrusted source, reset gso_segs. */
  		int type = skb_shinfo(skb)->gso_type;
  
  		if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY) ||
  			     !(type & (SKB_GSO_UDP))))
  			goto out;
  
  		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  
  		segs = NULL;
  		goto out;
  	}
  
  	/* Do software UFO. Complete and fill in the UDP checksum as HW cannot
  	 * do checksum of UDP packets sent as multiple IP fragments.
  	 */
  	offset = skb->csum_start - skb_headroom(skb);
  	csum = skb_checksum(skb, offset, skb->len- offset, 0);
  	offset += skb->csum_offset;
  	*(__sum16 *)(skb->data + offset) = csum_fold(csum);
  	skb->ip_summed = CHECKSUM_NONE;
  
  	/* Check if there is enough headroom to insert fragment header. */
  	if ((skb_headroom(skb) < frag_hdr_sz) &&
  	    pskb_expand_head(skb, frag_hdr_sz, 0, GFP_ATOMIC))
  		goto out;
  
  	/* Find the unfragmentable header and shift it left by frag_hdr_sz
  	 * bytes to insert fragment header.
  	 */
  	unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
  	nexthdr = *prevhdr;
  	*prevhdr = NEXTHDR_FRAGMENT;
  	unfrag_len = skb_network_header(skb) - skb_mac_header(skb) +
  		     unfrag_ip6hlen;
  	mac_start = skb_mac_header(skb);
  	memmove(mac_start-frag_hdr_sz, mac_start, unfrag_len);
  
  	skb->mac_header -= frag_hdr_sz;
  	skb->network_header -= frag_hdr_sz;
  
  	fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
  	fptr->nexthdr = nexthdr;
  	fptr->reserved = 0;
  	ipv6_select_ident(fptr);
  
  	/* Fragment the skb. ipv6 header and the remaining fields of the
  	 * fragment header are updated in ipv6_gso_segment()
  	 */
  	segs = skb_segment(skb, features);
  
  out:
  	return segs;
  }

  static const struct inet6_protocol udpv6_protocol = {

  	.handler	=	udpv6_rcv,
  	.err_handler	=	udpv6_err,

  	.gso_send_check =	udp6_ufo_send_check,
  	.gso_segment	=	udp6_ufo_fragment,

  	.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->inet_dport);
  	srcp  = ntohs(inet->inet_sport);

  	seq_printf(seq,

  		   "%5d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "

  		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d
  ",

  		   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,

  		   sk_wmem_alloc_get(sp),
  		   sk_rmem_alloc_get(sp),

  		   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
  ");

  	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,

  	.udp_table	= &udp_table,

  	.seq_fops	= {
  		.owner	=	THIS_MODULE,
  	},

  	.seq_ops	= {
  		.show		= udp6_seq_show,
  	},

  };

  int __net_init 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,

  	.rehash		   = udp_v6_rehash,

  	.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),

  	.slab_flags	   = SLAB_DESTROY_BY_RCU,

  	.h.udp_table	   = &udp_table,

  #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,

  	.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);

  }