[NET]: Supporting UDP-Lite (RFC 3828) in Linux

This is a revision of the previously submitted patch, which alters
the way files are organized and compiled in the following manner:

	* UDP and UDP-Lite now use separate object files
	* source file dependencies resolved via header files
	  net/ipv{4,6}/udp_impl.h
	* order of inclusion files in udp.c/udplite.c adapted
	  accordingly

[NET/IPv4]: Support for the UDP-Lite protocol (RFC 3828)

This patch adds support for UDP-Lite to the IPv4 stack, provided as an
extension to the existing UDPv4 code:
        * generic routines are all located in net/ipv4/udp.c
        * UDP-Lite specific routines are in net/ipv4/udplite.c
        * MIB/statistics support in /proc/net/snmp and /proc/net/udplite
        * shared API with extensions for partial checksum coverage

[NET/IPv6]: Extension for UDP-Lite over IPv6

It extends the existing UDPv6 code base with support for UDP-Lite
in the same manner as per UDPv4. In particular,
        * UDPv6 generic and shared code is in net/ipv6/udp.c
        * UDP-Litev6 specific extensions are in net/ipv6/udplite.c
        * MIB/statistics support in /proc/net/snmp6 and /proc/net/udplite6
        * support for IPV6_ADDRFORM
        * aligned the coding style of protocol initialisation with af_inet6.c
        * made the error handling in udpv6_queue_rcv_skb consistent;
          to return `-1' on error on all error cases
        * consolidation of shared code

[NET]: UDP-Lite Documentation and basic XFRM/Netfilter support

The UDP-Lite patch further provides
        * API documentation for UDP-Lite
        * basic xfrm support
        * basic netfilter support for IPv4 and IPv6 (LOG target)

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/udp_impl.h b/net/ipv6/udp_impl.h
new file mode 100644
index 0000000..ec98788
--- /dev/null
+++ b/net/ipv6/udp_impl.h
@@ -0,0 +1,34 @@
+#ifndef _UDP6_IMPL_H
+#define _UDP6_IMPL_H
+#include <net/udp.h>
+#include <net/udplite.h>
+#include <net/protocol.h>
+#include <net/addrconf.h>
+#include <net/inet_common.h>
+
+extern int  	__udp6_lib_rcv(struct sk_buff **, struct hlist_head [], int );
+extern void 	__udp6_lib_err(struct sk_buff *, struct inet6_skb_parm *,
+			       int , int , int , __be32 , struct hlist_head []);
+
+extern int	udpv6_getsockopt(struct sock *sk, int level, int optname,
+		     		 char __user *optval, int __user *optlen);
+extern int	udpv6_setsockopt(struct sock *sk, int level, int optname,
+			  	 char __user *optval, int optlen);
+#ifdef CONFIG_COMPAT
+extern int	compat_udpv6_setsockopt(struct sock *sk, int level, int optname,
+					char __user *optval, int optlen);
+extern int	compat_udpv6_getsockopt(struct sock *sk, int level, int optname,
+				       char __user *optval, int __user *optlen);
+#endif
+extern int	udpv6_sendmsg(struct kiocb *iocb, struct sock *sk,
+			      struct msghdr *msg, size_t len);
+extern int	udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
+			      struct msghdr *msg, size_t len,
+		  	      int noblock, int flags, int *addr_len);
+extern int	udpv6_queue_rcv_skb(struct sock * sk, struct sk_buff *skb);
+extern int	udpv6_destroy_sock(struct sock *sk);
+
+#ifdef CONFIG_PROC_FS
+extern int	udp6_seq_show(struct seq_file *seq, void *v);
+#endif
+#endif	/* _UDP6_IMPL_H */