[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/proc.c b/net/ipv6/proc.c
index 4158d38..35249d8 100644
--- a/net/ipv6/proc.c
+++ b/net/ipv6/proc.c
@@ -49,6 +49,8 @@
 		       fold_prot_inuse(&tcpv6_prot));
 	seq_printf(seq, "UDP6: inuse %d\n",
 		       fold_prot_inuse(&udpv6_prot));
+	seq_printf(seq, "UDPLITE6: inuse %d\n",
+		        fold_prot_inuse(&udplitev6_prot));
 	seq_printf(seq, "RAW6: inuse %d\n",
 		       fold_prot_inuse(&rawv6_prot));
 	seq_printf(seq, "FRAG6: inuse %d memory %d\n",
@@ -133,6 +135,14 @@
 	SNMP_MIB_SENTINEL
 };
 
+static struct snmp_mib snmp6_udplite6_list[] = {
+	SNMP_MIB_ITEM("UdpLite6InDatagrams", UDP_MIB_INDATAGRAMS),
+	SNMP_MIB_ITEM("UdpLite6NoPorts", UDP_MIB_NOPORTS),
+	SNMP_MIB_ITEM("UdpLite6InErrors", UDP_MIB_INERRORS),
+	SNMP_MIB_ITEM("UdpLite6OutDatagrams", UDP_MIB_OUTDATAGRAMS),
+	SNMP_MIB_SENTINEL
+};
+
 static unsigned long
 fold_field(void *mib[], int offt)
 {
@@ -167,6 +177,7 @@
 		snmp6_seq_show_item(seq, (void **)ipv6_statistics, snmp6_ipstats_list);
 		snmp6_seq_show_item(seq, (void **)icmpv6_statistics, snmp6_icmp6_list);
 		snmp6_seq_show_item(seq, (void **)udp_stats_in6, snmp6_udp6_list);
+		snmp6_seq_show_item(seq, (void **)udplite_stats_in6, snmp6_udplite6_list);
 	}
 	return 0;
 }