[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>

1 files changed, 87 insertions, 4 deletions

diff --git a/include/net/udp.h b/include/net/udp.h
index db0c05f67546..4f0626735ed3 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -26,9 +26,28 @@
 #include <net/inet_sock.h>
 #include <net/sock.h>
 #include <net/snmp.h>
+#include <net/ip.h>
+#include <linux/ipv6.h>
 #include <linux/seq_file.h>
 
-#define UDP_HTABLE_SIZE         128
+/**
+ *      struct udp_skb_cb  -  UDP(-Lite) private variables
+ *
+ *      @header:      private variables used by IPv4/IPv6
+ *      @cscov:       checksum coverage length (UDP-Lite only)
+ *      @partial_cov: if set indicates partial csum coverage
+ */
+struct udp_skb_cb {
+        union {
+                struct inet_skb_parm    h4;
+#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
+                struct inet6_skb_parm   h6;
+#endif
+        } header;
+        __u16           cscov;
+        __u8            partial_cov;
+};
+#define UDP_SKB_CB(__skb)       ((struct udp_skb_cb *)((__skb)->cb))
 
 extern struct hlist_head udp_hash[UDP_HTABLE_SIZE];
 extern rwlock_t udp_hash_lock;
@@ -47,6 +66,62 @@ extern struct proto udp_prot;
 
 struct sk_buff;
 
+/*
+ *      Generic checksumming routines for UDP(-Lite) v4 and v6
+ */
+static inline u16  __udp_lib_checksum_complete(struct sk_buff *skb)
+{
+        if (! UDP_SKB_CB(skb)->partial_cov)
+                return __skb_checksum_complete(skb);
+        return  csum_fold(skb_checksum(skb, 0, UDP_SKB_CB(skb)->cscov,
+                          skb->csum));
+}
+
+static __inline__ int udp_lib_checksum_complete(struct sk_buff *skb)
+{
+        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
+                __udp_lib_checksum_complete(skb);
+}
+
+/**
+ *      udp_csum_outgoing  -  compute UDPv4/v6 checksum over fragments
+ *      @sk:    socket we are writing to
+ *      @skb:   sk_buff containing the filled-in UDP header
+ *              (checksum field must be zeroed out)
+ */
+static inline u32 udp_csum_outgoing(struct sock *sk, struct sk_buff *skb)
+{
+        u32 csum = csum_partial(skb->h.raw, sizeof(struct udphdr), 0);
+
+        skb_queue_walk(&sk->sk_write_queue, skb) {
+                csum = csum_add(csum, skb->csum);
+        }
+        return csum;
+}
+
+/* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
+static inline void udp_lib_hash(struct sock *sk)
+{
+        BUG();
+}
+
+static inline void udp_lib_unhash(struct sock *sk)
+{
+        write_lock_bh(&udp_hash_lock);
+        if (sk_del_node_init(sk)) {
+                inet_sk(sk)->num = 0;
+                sock_prot_dec_use(sk->sk_prot);
+        }
+        write_unlock_bh(&udp_hash_lock);
+}
+
+static inline void udp_lib_close(struct sock *sk, long timeout)
+{
+        sk_common_release(sk);
+}
+
+
+/* net/ipv4/udp.c */
 extern int      udp_get_port(struct sock *sk, unsigned short snum,
                              int (*saddr_cmp)(const struct sock *, const struct sock *));
 extern void     udp_err(struct sk_buff *, u32);
@@ -61,21 +136,29 @@ extern unsigned int udp_poll(struct file *file, struct socket *sock,
                              poll_table *wait);
 
 DECLARE_SNMP_STAT(struct udp_mib, udp_statistics);
-#define UDP_INC_STATS(field)            SNMP_INC_STATS(udp_statistics, field)
-#define UDP_INC_STATS_BH(field)         SNMP_INC_STATS_BH(udp_statistics, field)
-#define UDP_INC_STATS_USER(field)       SNMP_INC_STATS_USER(udp_statistics, field)
+/*
+ *      SNMP statistics for UDP and UDP-Lite
+ */
+#define UDP_INC_STATS_USER(field, is_udplite)                          do {   \
+        if (is_udplite) SNMP_INC_STATS_USER(udplite_statistics, field);       \
+        else            SNMP_INC_STATS_USER(udp_statistics, field);  }  while(0)
+#define UDP_INC_STATS_BH(field, is_udplite)                            do  {  \
+        if (is_udplite) SNMP_INC_STATS_BH(udplite_statistics, field);         \
+        else            SNMP_INC_STATS_BH(udp_statistics, field);    }  while(0)
 
 /* /proc */
 struct udp_seq_afinfo {
         struct module           *owner;
         char                    *name;
         sa_family_t             family;
+        struct hlist_head       *hashtable;
         int                     (*seq_show) (struct seq_file *m, void *v);
         struct file_operations  *seq_fops;
 };
 
 struct udp_iter_state {
         sa_family_t             family;
+        struct hlist_head       *hashtable;
         int                     bucket;
         struct seq_operations   seq_ops;
 };