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

This 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
        * consolidation of shared code

Signed-off-by: Gerrit Renker  <[EMAIL PROTECTED]>
------------------------------------------------------------------------------

 include/linux/in.h     |    1 
 include/linux/socket.h |    1 
 include/linux/udp.h    |   12 +
 include/net/udp.h      |   91 ++++++++-
 include/net/udplite.h  |  149 +++++++++++++++
 net/ipv4/af_inet.c     |    8 
 net/ipv4/proc.c        |   13 +
 net/ipv4/udp.c         |  481 +++++++++++++++++++++++++++++--------------------
 net/ipv4/udplite.c     |  118 ++++++++++++
 9 files changed, 673 insertions(+), 201 deletions(-)

------------------------------------------------------------------------------

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 014b41d..564f3b0 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -38,6 +38,7 @@ #ifdef __KERNEL__
 #include <linux/types.h>
 
 #include <net/inet_sock.h>
+#define UDP_HTABLE_SIZE                128
 
 struct udp_sock {
        /* inet_sock has to be the first member */
@@ -50,12 +51,23 @@ struct udp_sock {
         * when the socket is uncorked.
         */
        __u16            len;           /* total length of pending frames */
+       /*
+        * Fields specific to UDP-Lite.
+        */
+       __u16            pcslen;
+       __u16            pcrlen;
+/* indicator bits used by pcflag: */
+#define UDPLITE_BIT      0x1           /* set by udplite proto init function */
+#define UDPLITE_SEND_CC  0x2           /* set via udplite setsockopt         */
+#define UDPLITE_RECV_CC  0x4           /* set via udplite setsocktopt        */
+       __u8             pcflag;        /* marks socket as UDP-Lite if > 0    */
 };
 
 static inline struct udp_sock *udp_sk(const struct sock *sk)
 {
        return (struct udp_sock *)sk;
 }
+#define IS_UDPLITE(__sk) (udp_sk(__sk)->pcflag)
 
 #endif
 
diff --git a/include/net/udp.h b/include/net/udp.h
index db0c05f..4f06267 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -26,9 +26,28 @@ #include <linux/list.h>
 #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
                             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;
 };
diff --git a/include/net/udplite.h b/include/net/udplite.h
new file mode 100644
index 0000000..1473b3e
--- /dev/null
+++ b/include/net/udplite.h
@@ -0,0 +1,149 @@
+/*
+ *     Definitions for the UDP-Lite (RFC 3828) code.
+ */
+#ifndef _UDPLITE_H
+#define _UDPLITE_H
+
+/* UDP-Lite socket options */
+#define UDPLITE_SEND_CSCOV   10 /* sender partial coverage (as sent)      */
+#define UDPLITE_RECV_CSCOV   11 /* receiver partial coverage (threshold ) */
+
+extern struct proto            udplite_prot;
+extern struct hlist_head       udplite_hash[UDP_HTABLE_SIZE];
+
+/* UDP-Lite does not have a standardized MIB yet, so we inherit from UDP */
+DECLARE_SNMP_STAT(struct udp_mib, udplite_statistics);
+
+/*
+ *     Checksum computation is all in software, hence simpler getfrag.
+ */
+static __inline__ int udplite_getfrag(void *from, char *to, int  offset,
+                                     int len, int odd, struct sk_buff *skb)
+{
+       return memcpy_fromiovecend(to, (struct iovec *) from, offset, len);
+}
+
+/* Designate sk as UDP-Lite socket */
+static inline int udplite_sk_init(struct sock *sk)
+{
+       udp_sk(sk)->pcflag = UDPLITE_BIT;
+       return 0;
+}
+
+/*
+ *     Checksumming routines
+ */
+static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
+{
+       u16 cscov;
+
+        /* In UDPv4 a zero checksum means that the transmitter generated no
+         * checksum. UDP-Lite (like IPv6) mandates checksums, hence packets
+         * with a zero checksum field are illegal.                            
*/
+       if (uh->check == 0) {
+               LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: zeroed checksum field\n");
+               return 1;
+       }
+
+        UDP_SKB_CB(skb)->partial_cov = 0;
+       cscov = ntohs(uh->len);
+
+       if (cscov == 0)          /* Indicates that full coverage is required. */
+               cscov = skb->len;
+       else if (cscov < 8  || cscov > skb->len) {
+               /*
+                * Coverage length violates RFC 3828: log and discard silently.
+                */
+               LIMIT_NETDEBUG(KERN_DEBUG "UDPLITE: bad csum coverage %d/%d\n",
+                              cscov, skb->len);
+               return 1;
+
+       } else if (cscov < skb->len)
+               UDP_SKB_CB(skb)->partial_cov = 1;
+
+        UDP_SKB_CB(skb)->cscov = cscov;
+
+       /*
+        * There is no known NIC manufacturer supporting UDP-Lite yet,
+        * hence ip_summed is always (re-)set to CHECKSUM_NONE.
+        */
+       skb->ip_summed = CHECKSUM_NONE;
+
+       return 0;
+}
+
+static __inline__ int udplite4_csum_init(struct sk_buff *skb, struct udphdr 
*uh)
+{
+       int rc = udplite_checksum_init(skb, uh);
+
+       if (!rc)
+               skb->csum = csum_tcpudp_nofold(skb->nh.iph->saddr,
+                                              skb->nh.iph->daddr,
+                                              skb->len, IPPROTO_UDPLITE, 0);
+       return rc;
+}
+
+static __inline__ int udplite6_csum_init(struct sk_buff *skb, struct udphdr 
*uh)
+{
+       int rc = udplite_checksum_init(skb, uh);
+
+       if (!rc)
+               skb->csum = ~csum_ipv6_magic(&skb->nh.ipv6h->saddr,
+                                            &skb->nh.ipv6h->daddr,
+                                            skb->len, IPPROTO_UDPLITE, 0);
+       return rc;
+}
+
+static inline int udplite_sender_cscov(struct udp_sock *up, struct udphdr *uh)
+{
+       int cscov = up->len;
+
+       /*
+        * Sender has set `partial coverage' option on UDP-Lite socket
+        */
+       if (up->pcflag & UDPLITE_SEND_CC)    {
+               if (up->pcslen < up->len) {
+               /* up->pcslen == 0 means that full coverage is required,
+                * partial coverage only if  0 < up->pcslen < up->len */
+                       if (0 < up->pcslen) {
+                              cscov = up->pcslen;
+                       }
+                       uh->len = htons(up->pcslen);
+               }
+       /*
+        * NOTE: Causes for the error case  `up->pcslen > up->len':
+        *        (i)  Application error (will not be penalized).
+        *       (ii)  Payload too big for send buffer: data is split
+        *             into several packets, each with its own header.
+        *             In this case (e.g. last segment), coverage may
+        *             exceed packet length.
+        *       Since packets with coverage length > packet length are
+        *       illegal, we fall back to the defaults here.
+        */
+       }
+       return cscov;
+}
+
+static inline u32 udplite_csum_outgoing(struct sock *sk, struct sk_buff *skb)
+{
+       u32 csum = 0;
+       int off, len, cscov = udplite_sender_cscov(udp_sk(sk), skb->h.uh);
+
+       skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
+
+       skb_queue_walk(&sk->sk_write_queue, skb) {
+               off = skb->h.raw - skb->data;
+               len = skb->len - off;
+
+               csum = skb_checksum(skb, off, (cscov > len)? len : cscov, csum);
+
+               if ((cscov -= len) <= 0)
+                       break;
+       }
+       return csum;
+}
+
+extern void    udplite4_register(void);
+extern int     udplite_get_port(struct sock *sk, unsigned short snum,
+                       int (*scmp)(const struct sock *, const struct sock *));
+#endif /* _UDPLITE_H */
diff --git a/include/linux/in.h b/include/linux/in.h
index 2619859..1912e7c 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -45,6 +45,7 @@ enum {
 
   IPPROTO_COMP   = 108,                /* Compression Header protocol */
   IPPROTO_SCTP   = 132,                /* Stream Control Transport Protocol    
*/
+  IPPROTO_UDPLITE = 136,       /* UDP-Lite (RFC 3828)                  */
 
   IPPROTO_RAW   = 255,         /* Raw IP packets                       */
   IPPROTO_MAX
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 3614090..592b666 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -264,6 +264,7 @@ #define SOL_UDP             17
 #define SOL_IPV6       41
 #define SOL_ICMPV6     58
 #define SOL_SCTP       132
+#define SOL_UDPLITE    136     /* UDP-Lite (RFC 3828) */
 #define SOL_RAW                255
 #define SOL_IPX                256
 #define SOL_AX25       257
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 865d752..aa91a1c 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -92,10 +92,8 @@ #include <linux/errno.h>
 #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>
@@ -103,6 +101,7 @@ #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <net/sock.h>
 #include <net/udp.h>
+#include <net/udplite.h>
 #include <net/icmp.h>
 #include <net/route.h>
 #include <net/inet_common.h>
@@ -120,26 +119,29 @@ 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))
+static int __udp_lib_get_port(struct sock *sk, unsigned short snum,
+               struct hlist_head udptable[], int *port_rover,
+               int (*saddr_cmp)(const struct sock *, const struct sock *))
 {
        struct hlist_node *node;
        struct hlist_head *head;
@@ -150,15 +152,15 @@ int udp_get_port(struct sock *sk, unsign
        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 +181,15 @@ int udp_get_port(struct sock *sk, unsign
                                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                        &&
@@ -200,7 +202,7 @@ gotit:
        }
        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);
        }
@@ -210,6 +212,12 @@ fail:
        return error;
 }
 
+__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);
+}
+
 static 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 +232,20 @@ static inline int udp_v4_get_port(struct
        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 +279,10 @@ static struct sock *udp_v4_lookup_longwa
                        }
                }
        }
-       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 +324,8 @@ found:
  * to find the appropriate port.
  */
 
-void udp_err(struct sk_buff *skb, u32 info)
+static 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 +336,8 @@ void udp_err(struct sk_buff *skb, u32 in
        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 +391,11 @@ 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.
  */
@@ -419,6 +410,45 @@ static void udp_flush_pending_frames(str
        }
 }
 
+/**
+ *     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.
  */
@@ -429,6 +459,7 @@ static int udp_push_pending_frames(struc
        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 +474,28 @@ static int udp_push_pending_frames(struc
        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 +504,6 @@ 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 +517,9 @@ int udp_sendmsg(struct kiocb *iocb, stru
        __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 +624,7 @@ int udp_sendmsg(struct kiocb *iocb, stru
                                              { .daddr = faddr,
                                                .saddr = saddr,
                                                .tos = tos } },
-                                   .proto = IPPROTO_UDP,
+                                   .proto = sk->sk_protocol,
                                    .uli_u = { .ports =
                                               { .sport = inet->sport,
                                                 .dport = dport } } };
@@ -668,8 +670,9 @@ 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 +687,7 @@ 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 +698,7 @@ 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;
 
@@ -795,17 +798,6 @@ int udp_ioctl(struct sock *sk, int cmd, 
        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.
@@ -817,7 +809,7 @@ static int udp_recvmsg(struct kiocb *ioc
        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 +831,25 @@ 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 +882,7 @@ 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 +914,6 @@ int udp_disconnect(struct sock *sk, int 
        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
@@ -1021,10 +1018,8 @@ static int udp_queue_rcv_skb(struct sock
        /*
         *      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) {
@@ -1048,31 +1043,68 @@ static int udp_queue_rcv_skb(struct sock
                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;
 }
 
 /*
@@ -1081,14 +1113,16 @@ static int udp_queue_rcv_skb(struct sock
  *     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) {
@@ -1122,65 +1156,75 @@ static int udp_v4_mcast_deliver(struct s
  * 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)
+static 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;
+
+               udp4_csum_init(skb, uh);
 
-       udp_checksum_init(skb, uh, ulen, saddr, daddr);
+       } 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;
@@ -1192,10 +1236,10 @@ 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);
 
        /*
@@ -1206,35 +1250,39 @@ 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);
 }
 
+__inline__ int udp_rcv(struct sk_buff *skb)
+{
+       return __udp4_lib_rcv(skb, udp_hash, 0);
+}
+
 static int udp_destroy_sock(struct sock *sk)
 {
        lock_sock(sk);
@@ -1284,6 +1332,32 @@ static int do_udp_setsockopt(struct sock
                }
                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;
@@ -1295,18 +1369,18 @@ static int do_udp_setsockopt(struct sock
 static 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)
 {
-       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
 
@@ -1333,6 +1407,16 @@ static int do_udp_getsockopt(struct sock
                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;
        };
@@ -1347,18 +1431,18 @@ static int do_udp_getsockopt(struct sock
 static 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,
                                 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
 /**
@@ -1378,7 +1462,8 @@ unsigned int udp_poll(struct file *file,
 {
        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) &&
@@ -1388,8 +1473,8 @@ unsigned int udp_poll(struct file *file,
 
                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 {
@@ -1411,7 +1496,7 @@ unsigned int udp_poll(struct file *file,
 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,
@@ -1422,8 +1507,8 @@ 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
@@ -1442,7 +1527,7 @@ static struct sock *udp_get_first(struct
 
        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;
                }
@@ -1463,7 +1548,7 @@ 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;
@@ -1513,6 +1598,7 @@ static int udp_seq_open(struct inode *in
        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;
@@ -1602,6 +1688,7 @@ static struct udp_seq_afinfo udp4_seq_af
        .owner          = THIS_MODULE,
        .name           = "udp",
        .family         = AF_INET,
+       .hashtable      = udp_hash,
        .seq_show       = udp4_seq_show,
        .seq_fops       = &udp4_seq_fops,
 };
@@ -1630,3 +1717,5 @@ #ifdef CONFIG_PROC_FS
 EXPORT_SYMBOL(udp_proc_register);
 EXPORT_SYMBOL(udp_proc_unregister);
 #endif
+/* the extensions for UDP-Lite (RFC 3828) */
+#include "udplite.c"
diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
new file mode 100644
index 0000000..d220232
--- /dev/null
+++ b/net/ipv4/udplite.c
@@ -0,0 +1,118 @@
+/*
+ *  UDPLITE     An implementation of the UDP-Lite protocol (RFC 3828).
+ *
+ *  Version:    $Id: udplite.c,v 1.25 2006/10/19 07:22:36 gerrit Exp $
+ *
+ *  Authors:    Gerrit Renker       <[EMAIL PROTECTED]>
+ *
+ *  Changes:
+ *  Fixes:
+ *             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.
+ */
+struct hlist_head      udplite_hash[UDP_HTABLE_SIZE];
+static int             udplite_port_rover;
+
+DEFINE_SNMP_STAT(struct udp_mib, udplite_statistics)   __read_mostly;
+
+__inline__ int udplite_get_port(struct sock *sk, unsigned short p,
+                       int (*c)(const struct sock *, const struct sock *))
+{
+       return  __udp_lib_get_port(sk, p, udplite_hash, &udplite_port_rover, c);
+}
+
+static __inline__ int udplite_v4_get_port(struct sock *sk, unsigned short snum)
+{
+       return udplite_get_port(sk, snum, ipv4_rcv_saddr_equal);
+}
+
+__inline__ int udplite_rcv(struct sk_buff *skb)
+{
+       return __udp4_lib_rcv(skb, udplite_hash, 1);
+}
+
+__inline__ void udplite_err(struct sk_buff *skb, u32 info)
+{
+       return __udp4_lib_err(skb, info, udplite_hash);
+}
+
+static struct net_protocol udplite_protocol = {
+       .handler        = udplite_rcv,
+       .err_handler    = udplite_err,
+       .no_policy      = 1,
+};
+
+struct proto   udplite_prot = {
+       .name              = "UDP-Lite",
+       .owner             = THIS_MODULE,
+       .close             = udp_lib_close,
+       .connect           = ip4_datagram_connect,
+       .disconnect        = udp_disconnect,
+       .ioctl             = udp_ioctl,
+       .init              = udplite_sk_init,
+       .destroy           = udp_destroy_sock,
+       .setsockopt        = udp_setsockopt,
+       .getsockopt        = udp_getsockopt,
+       .sendmsg           = udp_sendmsg,
+       .recvmsg           = udp_recvmsg,
+       .sendpage          = udp_sendpage,
+       .backlog_rcv       = udp_queue_rcv_skb,
+       .hash              = udp_lib_hash,
+       .unhash            = udp_lib_unhash,
+       .get_port          = udplite_v4_get_port,
+       .obj_size          = sizeof(struct udp_sock),
+#ifdef CONFIG_COMPAT
+       .compat_setsockopt = compat_udp_setsockopt,
+       .compat_getsockopt = compat_udp_getsockopt,
+#endif
+};
+
+static struct inet_protosw udplite4_protosw = {
+       .type           =  SOCK_DGRAM,
+       .protocol       =  IPPROTO_UDPLITE,
+       .prot           =  &udplite_prot,
+       .ops            =  &inet_dgram_ops,
+       .capability     = -1,
+       .no_check       =  0,           /* must checksum (RFC 3828) */
+       .flags          =  INET_PROTOSW_PERMANENT,
+};
+
+#ifdef CONFIG_PROC_FS
+static struct file_operations udplite4_seq_fops;
+static struct udp_seq_afinfo udplite4_seq_afinfo = {
+       .owner          = THIS_MODULE,
+       .name           = "udplite",
+       .family         = AF_INET,
+       .hashtable      = udplite_hash,
+       .seq_show       = udp4_seq_show,
+       .seq_fops       = &udplite4_seq_fops,
+};
+#endif
+
+void __init udplite4_register(void)
+{
+       if (proto_register(&udplite_prot, 1))
+               goto out_register_err;
+
+       if (inet_add_protocol(&udplite_protocol, IPPROTO_UDPLITE) < 0)
+               goto out_unregister_proto;
+
+       inet_register_protosw(&udplite4_protosw);
+
+#ifdef CONFIG_PROC_FS
+       if (udp_proc_register(&udplite4_seq_afinfo)) /* udplite4_proc_init() */
+               printk(KERN_ERR "%s: Cannot register /proc!\n", __FUNCTION__);
+#endif
+       return;
+
+out_unregister_proto:
+       proto_unregister(&udplite_prot);
+out_register_err:
+       printk(KERN_CRIT "%s: Cannot add UDP-Lite protocol.\n", __FUNCTION__);
+}
+
+EXPORT_SYMBOL(udplite_hash);
+EXPORT_SYMBOL(udplite_prot);
+EXPORT_SYMBOL(udplite_get_port);
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index edcf093..73319a2 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -104,6 +104,7 @@ #include <net/ip_fib.h>
 #include <net/inet_connection_sock.h>
 #include <net/tcp.h>
 #include <net/udp.h>
+#include <net/udplite.h>
 #include <linux/skbuff.h>
 #include <net/sock.h>
 #include <net/raw.h>
@@ -1223,10 +1224,13 @@ static int __init init_ipv4_mibs(void)
        tcp_statistics[1] = alloc_percpu(struct tcp_mib);
        udp_statistics[0] = alloc_percpu(struct udp_mib);
        udp_statistics[1] = alloc_percpu(struct udp_mib);
+       udplite_statistics[0] = alloc_percpu(struct udp_mib);
+       udplite_statistics[1] = alloc_percpu(struct udp_mib);
        if (!
            (net_statistics[0] && net_statistics[1] && ip_statistics[0]
             && ip_statistics[1] && tcp_statistics[0] && tcp_statistics[1]
-            && udp_statistics[0] && udp_statistics[1]))
+            && udp_statistics[0] && udp_statistics[1]
+            && udplite_statistics[0] && udplite_statistics[1]             ) )
                return -ENOMEM;
 
        (void) tcp_mib_init();
@@ -1313,6 +1317,8 @@ #endif
        /* Setup TCP slab cache for open requests. */
        tcp_init();
 
+       /* Add UDP-Lite (RFC 3828) */
+       udplite4_register();
 
        /*
         *      Set the ICMP layer up
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 9c6cbe3..cd873da 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -38,6 +38,7 @@ #include <net/icmp.h>
 #include <net/protocol.h>
 #include <net/tcp.h>
 #include <net/udp.h>
+#include <net/udplite.h>
 #include <linux/inetdevice.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -66,6 +67,7 @@ static int sockstat_seq_show(struct seq_
                   tcp_death_row.tw_count, atomic_read(&tcp_sockets_allocated),
                   atomic_read(&tcp_memory_allocated));
        seq_printf(seq, "UDP: inuse %d\n", fold_prot_inuse(&udp_prot));
+       seq_printf(seq, "UDPLITE: inuse %d\n", fold_prot_inuse(&udplite_prot));
        seq_printf(seq, "RAW: inuse %d\n", fold_prot_inuse(&raw_prot));
        seq_printf(seq,  "FRAG: inuse %d memory %d\n", ip_frag_nqueues,
                   atomic_read(&ip_frag_mem));
@@ -304,6 +306,17 @@ static int snmp_seq_show(struct seq_file
                           fold_field((void **) udp_statistics, 
                                      snmp4_udp_list[i].entry));
 
+       /* the UDP and UDP-Lite MIBs are the same */
+       seq_puts(seq, "\nUdpLite:");
+       for (i = 0; snmp4_udp_list[i].name != NULL; i++)
+               seq_printf(seq, " %s", snmp4_udp_list[i].name);
+
+       seq_puts(seq, "\nUdpLite:");
+       for (i = 0; snmp4_udp_list[i].name != NULL; i++)
+               seq_printf(seq, " %lu",
+                          fold_field((void **) udplite_statistics,
+                                     snmp4_udp_list[i].entry)     );
+
        seq_putc(seq, '\n');
        return 0;
 }
-
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