[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, 300 insertions, 218 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9e1bd374875e..98ba75096175 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -92,22 +92,16 @@
 #include <linux/timer.h>
 #include <linux/mm.h>
 #include <linux/inet.h>
-#include <linux/ipv6.h>
 #include <linux/netdevice.h>
-#include <net/snmp.h>
-#include <net/ip.h>
 #include <net/tcp_states.h>
-#include <net/protocol.h>
 #include <linux/skbuff.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
-#include <net/sock.h>
-#include <net/udp.h>
 #include <net/icmp.h>
 #include <net/route.h>
-#include <net/inet_common.h>
 #include <net/checksum.h>
 #include <net/xfrm.h>
+#include "udp_impl.h"
 
 /*
  *      Snmp MIB for the UDP layer
@@ -120,26 +114,30 @@ DEFINE_RWLOCK(udp_hash_lock);
 
 static int udp_port_rover;
 
-static inline int udp_lport_inuse(u16 num)
+static inline int __udp_lib_lport_inuse(__be16 num, struct hlist_head udptable[])
 {
         struct sock *sk;
         struct hlist_node *node;
 
-        sk_for_each(sk, node, &udp_hash[num & (UDP_HTABLE_SIZE - 1)])
+        sk_for_each(sk, node, &udptable[num & (UDP_HTABLE_SIZE - 1)])
                 if (inet_sk(sk)->num == num)
                         return 1;
         return 0;
 }
 
 /**
- *  udp_get_port  -  common port lookup for IPv4 and IPv6
+ *  __udp_lib_get_port  -  UDP/-Lite port lookup for IPv4 and IPv6
  *
  *  @sk:          socket struct in question
  *  @snum:        port number to look up
+ *  @udptable:    hash list table, must be of UDP_HTABLE_SIZE
+ *  @port_rover:  pointer to record of last unallocated port
  *  @saddr_comp:  AF-dependent comparison of bound local IP addresses
  */
-int udp_get_port(struct sock *sk, unsigned short snum,
-                 int (*saddr_cmp)(const struct sock *sk1, const struct sock *sk2))
+int __udp_lib_get_port(struct sock *sk, unsigned short snum,
+                       struct hlist_head udptable[], int *port_rover,
+                       int (*saddr_comp)(const struct sock *sk1,
+                                         const struct sock *sk2 )    )
 {
         struct hlist_node *node;
         struct hlist_head *head;
@@ -150,15 +148,15 @@ int udp_get_port(struct sock *sk, unsigned short snum,
         if (snum == 0) {
                 int best_size_so_far, best, result, i;
 
-                if (udp_port_rover > sysctl_local_port_range[1] ||
-                    udp_port_rover < sysctl_local_port_range[0])
-                        udp_port_rover = sysctl_local_port_range[0];
+                if (*port_rover > sysctl_local_port_range[1] ||
+                    *port_rover < sysctl_local_port_range[0])
+                        *port_rover = sysctl_local_port_range[0];
                 best_size_so_far = 32767;
-                best = result = udp_port_rover;
+                best = result = *port_rover;
                 for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
                         int size;
 
-                        head = &udp_hash[result & (UDP_HTABLE_SIZE - 1)];
+                        head = &udptable[result & (UDP_HTABLE_SIZE - 1)];
                         if (hlist_empty(head)) {
                                 if (result > sysctl_local_port_range[1])
                                         result = sysctl_local_port_range[0] +
@@ -179,15 +177,15 @@ int udp_get_port(struct sock *sk, unsigned short snum,
                                 result = sysctl_local_port_range[0]
                                         + ((result - sysctl_local_port_range[0]) &
                                            (UDP_HTABLE_SIZE - 1));
-                        if (!udp_lport_inuse(result))
+                        if (! __udp_lib_lport_inuse(result, udptable))
                                 break;
                 }
                 if (i >= (1 << 16) / UDP_HTABLE_SIZE)
                         goto fail;
 gotit:
-                udp_port_rover = snum = result;
+                *port_rover = snum = result;
         } else {
-                head = &udp_hash[snum & (UDP_HTABLE_SIZE - 1)];
+                head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];
 
                 sk_for_each(sk2, node, head)
                         if (inet_sk(sk2)->num == snum                        &&
@@ -195,12 +193,12 @@ gotit:
                             (!sk2->sk_reuse        || !sk->sk_reuse)         &&
                             (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if
                              || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
-                            (*saddr_cmp)(sk, sk2)                              )
+                            (*saddr_comp)(sk, sk2)                             )
                                 goto fail;
         }
         inet_sk(sk)->num = snum;
         if (sk_unhashed(sk)) {
-                head = &udp_hash[snum & (UDP_HTABLE_SIZE - 1)];
+                head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];
                 sk_add_node(sk, head);
                 sock_prot_inc_use(sk->sk_prot);
         }
@@ -210,7 +208,13 @@ fail:
         return error;
 }
 
-static inline int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
+__inline__ int udp_get_port(struct sock *sk, unsigned short snum,
+                        int (*scmp)(const struct sock *, const struct sock *))
+{
+        return  __udp_lib_get_port(sk, snum, udp_hash, &udp_port_rover, scmp);
+}
+
+inline int ipv4_rcv_saddr_equal(const struct sock *sk1, const struct sock *sk2)
 {
         struct inet_sock *inet1 = inet_sk(sk1), *inet2 = inet_sk(sk2);
 
@@ -224,34 +228,20 @@ static inline int udp_v4_get_port(struct sock *sk, unsigned short snum)
         return udp_get_port(sk, snum, ipv4_rcv_saddr_equal);
 }
 
-
-static void udp_v4_hash(struct sock *sk)
-{
-        BUG();
-}
-
-static void udp_v4_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);
-}
-
 /* UDP is nearly always wildcards out the wazoo, it makes no sense to try
  * harder than this. -DaveM
  */
-static struct sock *udp_v4_lookup_longway(__be32 saddr, __be16 sport,
-                                          __be32 daddr, __be16 dport, int dif)
+static struct sock *__udp4_lib_lookup(__be32 saddr, __be16 sport,
+                                      __be32 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;
 
-        sk_for_each(sk, node, &udp_hash[hnum & (UDP_HTABLE_SIZE - 1)]) {
+        read_lock(&udp_hash_lock);
+        sk_for_each(sk, node, &udptable[hnum & (UDP_HTABLE_SIZE - 1)]) {
                 struct inet_sock *inet = inet_sk(sk);
 
                 if (inet->num == hnum && !ipv6_only_sock(sk)) {
@@ -285,20 +275,10 @@ static struct sock *udp_v4_lookup_longway(__be32 saddr, __be16 sport,
                         }
                 }
         }
-        return result;
-}
-
-static __inline__ struct sock *udp_v4_lookup(__be32 saddr, __be16 sport,
-                                             __be32 daddr, __be16 dport, int dif)
-{
-        struct sock *sk;
-
-        read_lock(&udp_hash_lock);
-        sk = udp_v4_lookup_longway(saddr, sport, daddr, dport, dif);
-        if (sk)
-                sock_hold(sk);
+        if (result)
+                sock_hold(result);
         read_unlock(&udp_hash_lock);
-        return sk;
+        return result;
 }
 
 static inline struct sock *udp_v4_mcast_next(struct sock *sk,
@@ -340,7 +320,7 @@ found:
  * to find the appropriate port.
  */
 
-void udp_err(struct sk_buff *skb, u32 info)
+void __udp4_lib_err(struct sk_buff *skb, u32 info, struct hlist_head udptable[])
 {
         struct inet_sock *inet;
         struct iphdr *iph = (struct iphdr*)skb->data;
@@ -351,7 +331,8 @@ void udp_err(struct sk_buff *skb, u32 info)
         int harderr;
         int err;
 
-        sk = udp_v4_lookup(iph->daddr, uh->dest, iph->saddr, uh->source, skb->dev->ifindex);
+        sk = __udp4_lib_lookup(iph->daddr, uh->dest, iph->saddr, uh->source,
+                               skb->dev->ifindex, udptable                  );
         if (sk == NULL) {
                 ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
                 return; /* No socket for error */
@@ -405,6 +386,11 @@ out:
         sock_put(sk);
 }
 
+__inline__ void udp_err(struct sk_buff *skb, u32 info)
+{
+        return __udp4_lib_err(skb, info, udp_hash);
+}
+
 /*
  * Throw away all pending data and cancel the corking. Socket is locked.
  */
@@ -419,16 +405,56 @@ static void udp_flush_pending_frames(struct sock *sk)
         }
 }
 
+/**
+ *      udp4_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 udp4_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
+                                 __be32 src, __be32 dst, int len      )
+{
+        unsigned int csum = 0, offset;
+        struct udphdr *uh = skb->h.uh;
+
+        if (skb_queue_len(&sk->sk_write_queue) == 1) {
+                /*
+                 * Only one fragment on the socket.
+                 */
+                skb->csum = offsetof(struct udphdr, check);
+                uh->check = ~csum_tcpudp_magic(src, dst, 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->h.raw - skb->data;
+                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_tcpudp_magic(src, dst, len, IPPROTO_UDP, csum);
+                if (uh->check == 0)
+                        uh->check = -1;
+        }
+}
+
 /*
  * Push out all pending data as one UDP datagram. Socket is locked.
  */
-static int udp_push_pending_frames(struct sock *sk, struct udp_sock *up)
+int udp_push_pending_frames(struct sock *sk, struct udp_sock *up)
 {
         struct inet_sock *inet = inet_sk(sk);
         struct flowi *fl = &inet->cork.fl;
         struct sk_buff *skb;
         struct udphdr *uh;
         int err = 0;
+        u32 csum = 0;
 
         /* Grab the skbuff where UDP header space exists. */
         if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
@@ -443,52 +469,28 @@ static int udp_push_pending_frames(struct sock *sk, struct udp_sock *up)
         uh->len = htons(up->len);
         uh->check = 0;
 
-        if (sk->sk_no_check == UDP_CSUM_NOXMIT) {
+        if (up->pcflag)                                  /*     UDP-Lite      */
+                csum  = udplite_csum_outgoing(sk, skb);
+
+        else if (sk->sk_no_check == UDP_CSUM_NOXMIT) {   /* UDP csum disabled */
+
                 skb->ip_summed = CHECKSUM_NONE;
                 goto send;
-        }
 
-        if (skb_queue_len(&sk->sk_write_queue) == 1) {
-                /*
-                 * Only one fragment on the socket.
-                 */
-                if (skb->ip_summed == CHECKSUM_PARTIAL) {
-                        skb->csum = offsetof(struct udphdr, check);
-                        uh->check = ~csum_tcpudp_magic(fl->fl4_src, fl->fl4_dst,
-                                        up->len, IPPROTO_UDP, 0);
-                } else {
-                        skb->csum = csum_partial((char *)uh,
-                                        sizeof(struct udphdr), skb->csum);
-                        uh->check = csum_tcpudp_magic(fl->fl4_src, fl->fl4_dst,
-                                        up->len, IPPROTO_UDP, skb->csum);
-                        if (uh->check == 0)
-                                uh->check = -1;
-                }
-        } else {
-                unsigned int csum = 0;
-                /*
-                 * 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.
-                 */
-                if (skb->ip_summed == CHECKSUM_PARTIAL) {
-                        int offset = (unsigned char *)uh - skb->data;
-                        skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
+        } else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
 
-                        skb->ip_summed = CHECKSUM_NONE;
-                } else {
-                        skb->csum = csum_partial((char *)uh,
-                                        sizeof(struct udphdr), skb->csum);
-                }
+                udp4_hwcsum_outgoing(sk, skb, fl->fl4_src,fl->fl4_dst, up->len);
+                goto send;
+
+        } else                                           /*   `normal' UDP    */
+                csum = udp_csum_outgoing(sk, skb);
+
+        /* add protocol-dependent pseudo-header */
+        uh->check = csum_tcpudp_magic(fl->fl4_src, fl->fl4_dst, up->len,
+                                      sk->sk_protocol, csum             );
+        if (uh->check == 0)
+                uh->check = -1;
 
-                skb_queue_walk(&sk->sk_write_queue, skb) {
-                        csum = csum_add(csum, skb->csum);
-                }
-                uh->check = csum_tcpudp_magic(fl->fl4_src, fl->fl4_dst,
-                                up->len, IPPROTO_UDP, csum);
-                if (uh->check == 0)
-                        uh->check = -1;
-        }
 send:
         err = ip_push_pending_frames(sk);
 out:
@@ -497,12 +499,6 @@ out:
         return err;
 }
 
-
-static unsigned short udp_check(struct udphdr *uh, int len, __be32 saddr, __be32 daddr, unsigned long base)
-{
-        return(csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base));
-}
-
 int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 size_t len)
 {
@@ -516,8 +512,9 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         __be32 daddr, faddr, saddr;
         __be16 dport;
         u8  tos;
-        int err;
+        int err, is_udplite = up->pcflag;
         int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;
+        int (*getfrag)(void *, char *, int, int, int, struct sk_buff *);
 
         if (len > 0xFFFF)
                 return -EMSGSIZE;
@@ -622,7 +619,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                                               { .daddr = faddr,
                                                 .saddr = saddr,
                                                 .tos = tos } },
-                                    .proto = IPPROTO_UDP,
+                                    .proto = sk->sk_protocol,
                                     .uli_u = { .ports =
                                                { .sport = inet->sport,
                                                  .dport = dport } } };
@@ -668,8 +665,9 @@ back_from_confirm:
 
 do_append_data:
         up->len += ulen;
-        err = ip_append_data(sk, ip_generic_getfrag, msg->msg_iov, ulen, 
-                        sizeof(struct udphdr), &ipc, rt, 
+        getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
+        err = ip_append_data(sk, getfrag, msg->msg_iov, ulen,
+                        sizeof(struct udphdr), &ipc, rt,
                         corkreq ? msg->msg_flags|MSG_MORE : msg->msg_flags);
         if (err)
                 udp_flush_pending_frames(sk);
@@ -684,7 +682,7 @@ out:
         if (free)
                 kfree(ipc.opt);
         if (!err) {
-                UDP_INC_STATS_USER(UDP_MIB_OUTDATAGRAMS);
+                UDP_INC_STATS_USER(UDP_MIB_OUTDATAGRAMS, is_udplite);
                 return len;
         }
         /*
@@ -695,7 +693,7 @@ out:
          * seems like overkill.
          */
         if (err == -ENOBUFS || test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
-                UDP_INC_STATS_USER(UDP_MIB_SNDBUFERRORS);
+                UDP_INC_STATS_USER(UDP_MIB_SNDBUFERRORS, is_udplite);
         }
         return err;
 
@@ -707,8 +705,8 @@ do_confirm:
         goto out;
 }
 
-static int udp_sendpage(struct sock *sk, struct page *page, int offset,
-                        size_t size, int flags)
+int udp_sendpage(struct sock *sk, struct page *page, int offset,
+                 size_t size, int flags)
 {
         struct udp_sock *up = udp_sk(sk);
         int ret;
@@ -795,29 +793,18 @@ int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
         return(0);
 }
 
-static __inline__ int __udp_checksum_complete(struct sk_buff *skb)
-{
-        return __skb_checksum_complete(skb);
-}
-
-static __inline__ int udp_checksum_complete(struct sk_buff *skb)
-{
-        return skb->ip_summed != CHECKSUM_UNNECESSARY &&
-                __udp_checksum_complete(skb);
-}
-
 /*
  *      This should be easy, if there is something there we
  *      return it, otherwise we block.
  */
 
-static int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
-                       size_t len, int noblock, int flags, int *addr_len)
+int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+                size_t len, int noblock, int flags, int *addr_len)
 {
         struct inet_sock *inet = inet_sk(sk);
         struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
         struct sk_buff *skb;
-        int copied, err;
+        int copied, err, copy_only, is_udplite = IS_UDPLITE(sk);
 
         /*
          *      Check any passed addresses
@@ -839,15 +826,25 @@ try_again:
                 msg->msg_flags |= MSG_TRUNC;
         }
 
-        if (skb->ip_summed==CHECKSUM_UNNECESSARY) {
-                err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov,
-                                              copied);
-        } else if (msg->msg_flags&MSG_TRUNC) {
-                if (__udp_checksum_complete(skb))
+        /*
+         *      Decide whether to checksum and/or copy data.
+         *
+         *      UDP:      checksum may have been computed in HW,
+         *                (re-)compute it if message is truncated.
+         *      UDP-Lite: always needs to checksum, no HW support.
+         */
+        copy_only = (skb->ip_summed==CHECKSUM_UNNECESSARY);
+
+        if (is_udplite  ||  (!copy_only  &&  msg->msg_flags&MSG_TRUNC)) {
+                if (__udp_lib_checksum_complete(skb))
                         goto csum_copy_err;
-                err = skb_copy_datagram_iovec(skb, sizeof(struct udphdr), msg->msg_iov,
-                                              copied);
-        } else {
+                copy_only = 1;
+        }
+
+        if (copy_only)
+                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)
@@ -880,7 +877,7 @@ out:
         return err;
 
 csum_copy_err:
-        UDP_INC_STATS_BH(UDP_MIB_INERRORS);
+        UDP_INC_STATS_BH(UDP_MIB_INERRORS, is_udplite);
 
         skb_kill_datagram(sk, skb, flags);
 
@@ -912,11 +909,6 @@ int udp_disconnect(struct sock *sk, int flags)
         return 0;
 }
 
-static void udp_close(struct sock *sk, long timeout)
-{
-        sk_common_release(sk);
-}
-
 /* return:
  *      1  if the the UDP system should process it
  *      0  if we should drop this packet
@@ -1022,7 +1014,7 @@ static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)
  * Note that in the success and error cases, the skb is assumed to
  * have either been requeued or freed.
  */
-static int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
+int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
 {
         struct udp_sock *up = udp_sk(sk);
         int rc;
@@ -1030,10 +1022,8 @@ static int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
         /*
          *      Charge it to the socket, dropping if the queue is full.
          */
-        if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) {
-                kfree_skb(skb);
-                return -1;
-        }
+        if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
+                goto drop;
         nf_reset(skb);
 
         if (up->encap_type) {
@@ -1057,31 +1047,68 @@ static int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
                 if (ret < 0) {
                         /* process the ESP packet */
                         ret = xfrm4_rcv_encap(skb, up->encap_type);
-                        UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS);
+                        UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
                         return -ret;
                 }
                 /* FALLTHROUGH -- it's a UDP Packet */
         }
 
-        if (sk->sk_filter && skb->ip_summed != CHECKSUM_UNNECESSARY) {
-                if (__udp_checksum_complete(skb)) {
-                        UDP_INC_STATS_BH(UDP_MIB_INERRORS);
-                        kfree_skb(skb);
-                        return -1;
+        /*
+         *      UDP-Lite specific tests, ignored on UDP sockets
+         */
+        if ((up->pcflag & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
+
+                /*
+                 * MIB statistics other than incrementing the error count are
+                 * disabled for the following two types of errors: these depend
+                 * on the application settings, not on the functioning of the
+                 * protocol stack as such.
+                 *
+                 * RFC 3828 here recommends (sec 3.3): "There should also be a
+                 * way ... to ... at least let the receiving application block
+                 * delivery of packets with coverage values less than a value
+                 * provided by the application."
+                 */
+                if (up->pcrlen == 0) {          /* full coverage was set  */
+                        LIMIT_NETDEBUG(KERN_WARNING "UDPLITE: partial coverage "
+                                "%d while full coverage %d requested\n",
+                                UDP_SKB_CB(skb)->cscov, skb->len);
+                        goto drop;
                 }
+                /* The next case involves violating the min. coverage requested
+                 * by the receiver. This is subtle: if receiver wants x and x is
+                 * greater than the buffersize/MTU then receiver will complain
+                 * that it wants x while sender emits packets of smaller size y.
+                 * Therefore the above ...()->partial_cov statement is essential.
+                 */
+                if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
+                        LIMIT_NETDEBUG(KERN_WARNING
+                                "UDPLITE: coverage %d too small, need min %d\n",
+                                UDP_SKB_CB(skb)->cscov, up->pcrlen);
+                        goto drop;
+                }
+        }
+
+        if (sk->sk_filter && skb->ip_summed != CHECKSUM_UNNECESSARY) {
+                if (__udp_lib_checksum_complete(skb))
+                        goto drop;
                 skb->ip_summed = CHECKSUM_UNNECESSARY;
         }
 
         if ((rc = sock_queue_rcv_skb(sk,skb)) < 0) {
                 /* Note that an ENOMEM error is charged twice */
                 if (rc == -ENOMEM)
-                        UDP_INC_STATS_BH(UDP_MIB_RCVBUFERRORS);
-                UDP_INC_STATS_BH(UDP_MIB_INERRORS);
-                kfree_skb(skb);
-                return -1;
+                        UDP_INC_STATS_BH(UDP_MIB_RCVBUFERRORS, up->pcflag);
+                goto drop;
         }
-        UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS);
+
+        UDP_INC_STATS_BH(UDP_MIB_INDATAGRAMS, up->pcflag);
         return 0;
+
+drop:
+        UDP_INC_STATS_BH(UDP_MIB_INERRORS, up->pcflag);
+        kfree_skb(skb);
+        return -1;
 }
 
 /*
@@ -1090,14 +1117,16 @@ static int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
  *      Note: called only from the BH handler context,
  *      so we don't need to lock the hashes.
  */
-static int udp_v4_mcast_deliver(struct sk_buff *skb, struct udphdr *uh,
-                                 __be32 saddr, __be32 daddr)
+static int __udp4_lib_mcast_deliver(struct sk_buff *skb,
+                                    struct udphdr  *uh,
+                                    __be32 saddr, __be32 daddr,
+                                    struct hlist_head udptable[])
 {
         struct sock *sk;
         int dif;
 
         read_lock(&udp_hash_lock);
-        sk = sk_head(&udp_hash[ntohs(uh->dest) & (UDP_HTABLE_SIZE - 1)]);
+        sk = sk_head(&udptable[ntohs(uh->dest) & (UDP_HTABLE_SIZE - 1)]);
         dif = skb->dev->ifindex;
         sk = udp_v4_mcast_next(sk, uh->dest, daddr, uh->source, saddr, dif);
         if (sk) {
@@ -1131,65 +1160,75 @@ static int udp_v4_mcast_deliver(struct sk_buff *skb, struct udphdr *uh,
  * Otherwise, csum completion requires chacksumming packet body,
  * including udp header and folding it to skb->csum.
  */
-static void udp_checksum_init(struct sk_buff *skb, struct udphdr *uh,
-                             unsigned short ulen, __be32 saddr, __be32 daddr)
+static inline void udp4_csum_init(struct sk_buff *skb, struct udphdr *uh)
 {
         if (uh->check == 0) {
                 skb->ip_summed = CHECKSUM_UNNECESSARY;
         } else if (skb->ip_summed == CHECKSUM_COMPLETE) {
-                if (!udp_check(uh, ulen, saddr, daddr, skb->csum))
+               if (!csum_tcpudp_magic(skb->nh.iph->saddr, skb->nh.iph->daddr,
+                                      skb->len, IPPROTO_UDP, skb->csum       ))
                         skb->ip_summed = CHECKSUM_UNNECESSARY;
         }
         if (skb->ip_summed != CHECKSUM_UNNECESSARY)
-                skb->csum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
+                skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr,
+                                               skb->nh.iph->daddr,
+                                               skb->len, IPPROTO_UDP, 0);
         /* Probably, we should checksum udp header (it should be in cache
          * in any case) and data in tiny packets (< rx copybreak).
          */
+
+        /* UDP = UDP-Lite with a non-partial checksum coverage */
+        UDP_SKB_CB(skb)->partial_cov = 0;
 }
 
 /*
  *      All we need to do is get the socket, and then do a checksum. 
  */
  
-int udp_rcv(struct sk_buff *skb)
+int __udp4_lib_rcv(struct sk_buff *skb, struct hlist_head udptable[],
+                   int is_udplite)
 {
         struct sock *sk;
-        struct udphdr *uh;
+        struct udphdr *uh = skb->h.uh;
         unsigned short ulen;
         struct rtable *rt = (struct rtable*)skb->dst;
         __be32 saddr = skb->nh.iph->saddr;
         __be32 daddr = skb->nh.iph->daddr;
-        int len = skb->len;
 
         /*
-         *      Validate the packet and the UDP length.
+         *  Validate the packet.
          */
         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
-                goto no_header;
-
-        uh = skb->h.uh;
+                goto drop;              /* No space for header. */
 
         ulen = ntohs(uh->len);
-
-        if (ulen > len || ulen < sizeof(*uh))
+        if (ulen > skb->len)
                 goto short_packet;
 
-        if (pskb_trim_rcsum(skb, ulen))
-                goto short_packet;
+        if(! is_udplite ) {             /* UDP validates ulen. */
+
+                if (ulen < sizeof(*uh) || pskb_trim_rcsum(skb, ulen))
+                        goto short_packet;
 
-        udp_checksum_init(skb, uh, ulen, saddr, daddr);
+                udp4_csum_init(skb, uh);
+
+        } else  {                       /* UDP-Lite validates cscov. */
+                if (udplite4_csum_init(skb, uh))
+                        goto csum_error;
+        }
 
         if(rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
-                return udp_v4_mcast_deliver(skb, uh, saddr, daddr);
+                return __udp4_lib_mcast_deliver(skb, uh, saddr, daddr, udptable);
 
-        sk = udp_v4_lookup(saddr, uh->source, daddr, uh->dest, skb->dev->ifindex);
+        sk = __udp4_lib_lookup(saddr, uh->source, daddr, uh->dest,
+                               skb->dev->ifindex, udptable        );
 
         if (sk != NULL) {
                 int ret = udp_queue_rcv_skb(sk, skb);
                 sock_put(sk);
 
                 /* a return value > 0 means to resubmit the input, but
-                 * it it wants the return to be -protocol, or 0
+                 * it wants the return to be -protocol, or 0
                  */
                 if (ret > 0)
                         return -ret;
@@ -1201,10 +1240,10 @@ int udp_rcv(struct sk_buff *skb)
         nf_reset(skb);
 
         /* No socket. Drop packet silently, if checksum is wrong */
-        if (udp_checksum_complete(skb))
+        if (udp_lib_checksum_complete(skb))
                 goto csum_error;
 
-        UDP_INC_STATS_BH(UDP_MIB_NOPORTS);
+        UDP_INC_STATS_BH(UDP_MIB_NOPORTS, is_udplite);
         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 
         /*
@@ -1215,36 +1254,40 @@ int udp_rcv(struct sk_buff *skb)
         return(0);
 
 short_packet:
-        LIMIT_NETDEBUG(KERN_DEBUG "UDP: short packet: From %u.%u.%u.%u:%u %d/%d to %u.%u.%u.%u:%u\n",
+        LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: short packet: From %u.%u.%u.%u:%u %d/%d to %u.%u.%u.%u:%u\n",
+                       is_udplite? "-Lite" : "",
                        NIPQUAD(saddr),
                        ntohs(uh->source),
                        ulen,
-                       len,
+                       skb->len,
                        NIPQUAD(daddr),
                        ntohs(uh->dest));
-no_header:
-        UDP_INC_STATS_BH(UDP_MIB_INERRORS);
-        kfree_skb(skb);
-        return(0);
+        goto drop;
 
 csum_error:
         /* 
          * RFC1122: OK.  Discards the bad packet silently (as far as 
          * the network is concerned, anyway) as per 4.1.3.4 (MUST). 
          */
-        LIMIT_NETDEBUG(KERN_DEBUG "UDP: bad checksum. From %d.%d.%d.%d:%d to %d.%d.%d.%d:%d ulen %d\n",
+        LIMIT_NETDEBUG(KERN_DEBUG "UDP%s: bad checksum. From %d.%d.%d.%d:%d to %d.%d.%d.%d:%d ulen %d\n",
+                       is_udplite? "-Lite" : "",
                        NIPQUAD(saddr),
                        ntohs(uh->source),
                        NIPQUAD(daddr),
                        ntohs(uh->dest),
                        ulen);
 drop:
-        UDP_INC_STATS_BH(UDP_MIB_INERRORS);
+        UDP_INC_STATS_BH(UDP_MIB_INERRORS, is_udplite);
         kfree_skb(skb);
         return(0);
 }
 
-static int udp_destroy_sock(struct sock *sk)
+__inline__ int udp_rcv(struct sk_buff *skb)
+{
+        return __udp4_lib_rcv(skb, udp_hash, 0);
+}
+
+int udp_destroy_sock(struct sock *sk)
 {
         lock_sock(sk);
         udp_flush_pending_frames(sk);
@@ -1293,6 +1336,32 @@ static int do_udp_setsockopt(struct sock *sk, int level, int optname,
                 }
                 break;
 
+        /*
+         *      UDP-Lite's partial checksum coverage (RFC 3828).
+         */
+        /* The sender sets actual checksum coverage length via this option.
+         * The case coverage > packet length is handled by send module. */
+        case UDPLITE_SEND_CSCOV:
+                if (!up->pcflag)         /* Disable the option on UDP sockets */
+                        return -ENOPROTOOPT;
+                if (val != 0 && val < 8) /* Illegal coverage: use default (8) */
+                        val = 8;
+                up->pcslen = val;
+                up->pcflag |= UDPLITE_SEND_CC;
+                break;
+
+        /* The receiver specifies a minimum checksum coverage value. To make
+         * sense, this should be set to at least 8 (as done below). If zero is
+         * used, this again means full checksum coverage.                     */
+        case UDPLITE_RECV_CSCOV:
+                if (!up->pcflag)         /* Disable the option on UDP sockets */
+                        return -ENOPROTOOPT;
+                if (val != 0 && val < 8) /* Avoid silly minimal values.       */
+                        val = 8;
+                up->pcrlen = val;
+                up->pcflag |= UDPLITE_RECV_CC;
+                break;
+
         default:
                 err = -ENOPROTOOPT;
                 break;
@@ -1301,21 +1370,21 @@ static int do_udp_setsockopt(struct sock *sk, int level, int optname,
         return err;
 }
 
-static int udp_setsockopt(struct sock *sk, int level, int optname,
-                          char __user *optval, int optlen)
+int udp_setsockopt(struct sock *sk, int level, int optname,
+                   char __user *optval, int optlen)
 {
-        if (level != SOL_UDP)
-                return ip_setsockopt(sk, level, optname, optval, optlen);
-        return do_udp_setsockopt(sk, level, optname, optval, optlen);
+        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
+                return do_udp_setsockopt(sk, level, optname, optval, optlen);
+        return ip_setsockopt(sk, level, optname, optval, optlen);
 }
 
 #ifdef CONFIG_COMPAT
-static int compat_udp_setsockopt(struct sock *sk, int level, int optname,
-                                 char __user *optval, int optlen)
+int compat_udp_setsockopt(struct sock *sk, int level, int optname,
+                          char __user *optval, int optlen)
 {
-        if (level != SOL_UDP)
-                return compat_ip_setsockopt(sk, level, optname, optval, optlen);
-        return do_udp_setsockopt(sk, level, optname, optval, optlen);
+        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
+                return do_udp_setsockopt(sk, level, optname, optval, optlen);
+        return compat_ip_setsockopt(sk, level, optname, optval, optlen);
 }
 #endif
 
@@ -1342,6 +1411,16 @@ static int do_udp_getsockopt(struct sock *sk, int level, int optname,
                 val = up->encap_type;
                 break;
 
+        /* The following two cannot be changed on UDP sockets, the return is
+         * always 0 (which corresponds to the full checksum coverage of UDP). */
+        case UDPLITE_SEND_CSCOV:
+                val = up->pcslen;
+                break;
+
+        case UDPLITE_RECV_CSCOV:
+                val = up->pcrlen;
+                break;
+
         default:
                 return -ENOPROTOOPT;
         };
@@ -1353,21 +1432,21 @@ static int do_udp_getsockopt(struct sock *sk, int level, int optname,
         return 0;
 }
 
-static int udp_getsockopt(struct sock *sk, int level, int optname,
-                          char __user *optval, int __user *optlen)
+int udp_getsockopt(struct sock *sk, int level, int optname,
+                   char __user *optval, int __user *optlen)
 {
-        if (level != SOL_UDP)
-                return ip_getsockopt(sk, level, optname, optval, optlen);
-        return do_udp_getsockopt(sk, level, optname, optval, optlen);
+        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
+                return do_udp_getsockopt(sk, level, optname, optval, optlen);
+        return ip_getsockopt(sk, level, optname, optval, optlen);
 }
 
 #ifdef CONFIG_COMPAT
-static int compat_udp_getsockopt(struct sock *sk, int level, int optname,
+int compat_udp_getsockopt(struct sock *sk, int level, int optname,
                                  char __user *optval, int __user *optlen)
 {
-        if (level != SOL_UDP)
-                return compat_ip_getsockopt(sk, level, optname, optval, optlen);
-        return do_udp_getsockopt(sk, level, optname, optval, optlen);
+        if (level == SOL_UDP  ||  level == SOL_UDPLITE)
+                return do_udp_getsockopt(sk, level, optname, optval, optlen);
+        return compat_ip_getsockopt(sk, level, optname, optval, optlen);
 }
 #endif
 /**
@@ -1387,7 +1466,8 @@ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait)
 {
         unsigned int mask = datagram_poll(file, sock, wait);
         struct sock *sk = sock->sk;
-        
+        int     is_lite = IS_UDPLITE(sk);
+
         /* Check for false positives due to checksum errors */
         if ( (mask & POLLRDNORM) &&
              !(file->f_flags & O_NONBLOCK) &&
@@ -1397,8 +1477,8 @@ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait)
 
                 spin_lock_bh(&rcvq->lock);
                 while ((skb = skb_peek(rcvq)) != NULL) {
-                        if (udp_checksum_complete(skb)) {
-                                UDP_INC_STATS_BH(UDP_MIB_INERRORS);
+                        if (udp_lib_checksum_complete(skb)) {
+                                UDP_INC_STATS_BH(UDP_MIB_INERRORS, is_lite);
                                 __skb_unlink(skb, rcvq);
                                 kfree_skb(skb);
                         } else {
@@ -1420,7 +1500,7 @@ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait)
 struct proto udp_prot = {
         .name              = "UDP",
         .owner             = THIS_MODULE,
-        .close             = udp_close,
+        .close             = udp_lib_close,
         .connect           = ip4_datagram_connect,
         .disconnect        = udp_disconnect,
         .ioctl             = udp_ioctl,
@@ -1431,8 +1511,8 @@ struct proto udp_prot = {
         .recvmsg           = udp_recvmsg,
         .sendpage          = udp_sendpage,
         .backlog_rcv       = udp_queue_rcv_skb,
-        .hash              = udp_v4_hash,
-        .unhash            = udp_v4_unhash,
+        .hash              = udp_lib_hash,
+        .unhash            = udp_lib_unhash,
         .get_port          = udp_v4_get_port,
         .obj_size          = sizeof(struct udp_sock),
 #ifdef CONFIG_COMPAT
@@ -1451,7 +1531,7 @@ static struct sock *udp_get_first(struct seq_file *seq)
 
         for (state->bucket = 0; state->bucket < UDP_HTABLE_SIZE; ++state->bucket) {
                 struct hlist_node *node;
-                sk_for_each(sk, node, &udp_hash[state->bucket]) {
+                sk_for_each(sk, node, state->hashtable + state->bucket) {
                         if (sk->sk_family == state->family)
                                 goto found;
                 }
@@ -1472,7 +1552,7 @@ try_again:
         } while (sk && sk->sk_family != state->family);
 
         if (!sk && ++state->bucket < UDP_HTABLE_SIZE) {
-                sk = sk_head(&udp_hash[state->bucket]);
+                sk = sk_head(state->hashtable + state->bucket);
                 goto try_again;
         }
         return sk;
@@ -1522,6 +1602,7 @@ static int udp_seq_open(struct inode *inode, struct file *file)
         if (!s)
                 goto out;
         s->family               = afinfo->family;
+        s->hashtable            = afinfo->hashtable;
         s->seq_ops.start        = udp_seq_start;
         s->seq_ops.next         = udp_seq_next;
         s->seq_ops.show         = afinfo->seq_show;
@@ -1588,7 +1669,7 @@ static void udp4_format_sock(struct sock *sp, char *tmpbuf, int bucket)
                 atomic_read(&sp->sk_refcnt), sp);
 }
 
-static int udp4_seq_show(struct seq_file *seq, void *v)
+int udp4_seq_show(struct seq_file *seq, void *v)
 {
         if (v == SEQ_START_TOKEN)
                 seq_printf(seq, "%-127s\n",
@@ -1611,6 +1692,7 @@ static struct udp_seq_afinfo udp4_seq_afinfo = {
         .owner          = THIS_MODULE,
         .name           = "udp",
         .family         = AF_INET,
+        .hashtable      = udp_hash,
         .seq_show       = udp4_seq_show,
         .seq_fops       = &udp4_seq_fops,
 };