Get rid of arch/mips64/kernel. 9116 lines of code gone.

[linux-2.6/linux-mips.git] / net / ipv4 / udp.c

/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              The User Datagram Protocol (UDP).
 *
 * Version:     $Id: udp.c,v 1.102 2002/02/01 22:01:04 davem Exp $
 *
 * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 *              Alan Cox, <Alan.Cox@linux.org>
 *              Hirokazu Takahashi, <taka@valinux.co.jp>
 *
 * Fixes:
 *              Alan Cox        :       verify_area() calls
 *              Alan Cox        :       stopped close while in use off icmp
 *                                      messages. Not a fix but a botch that
 *                                      for udp at least is 'valid'.
 *              Alan Cox        :       Fixed icmp handling properly
 *              Alan Cox        :       Correct error for oversized datagrams
 *              Alan Cox        :       Tidied select() semantics. 
 *              Alan Cox        :       udp_err() fixed properly, also now 
 *                                      select and read wake correctly on errors
 *              Alan Cox        :       udp_send verify_area moved to avoid mem leak
 *              Alan Cox        :       UDP can count its memory
 *              Alan Cox        :       send to an unknown connection causes
 *                                      an ECONNREFUSED off the icmp, but
 *                                      does NOT close.
 *              Alan Cox        :       Switched to new sk_buff handlers. No more backlog!
 *              Alan Cox        :       Using generic datagram code. Even smaller and the PEEK
 *                                      bug no longer crashes it.
 *              Fred Van Kempen :       Net2e support for sk->broadcast.
 *              Alan Cox        :       Uses skb_free_datagram
 *              Alan Cox        :       Added get/set sockopt support.
 *              Alan Cox        :       Broadcasting without option set returns EACCES.
 *              Alan Cox        :       No wakeup calls. Instead we now use the callbacks.
 *              Alan Cox        :       Use ip_tos and ip_ttl
 *              Alan Cox        :       SNMP Mibs
 *              Alan Cox        :       MSG_DONTROUTE, and 0.0.0.0 support.
 *              Matt Dillon     :       UDP length checks.
 *              Alan Cox        :       Smarter af_inet used properly.
 *              Alan Cox        :       Use new kernel side addressing.
 *              Alan Cox        :       Incorrect return on truncated datagram receive.
 *      Arnt Gulbrandsen        :       New udp_send and stuff
 *              Alan Cox        :       Cache last socket
 *              Alan Cox        :       Route cache
 *              Jon Peatfield   :       Minor efficiency fix to sendto().
 *              Mike Shaver     :       RFC1122 checks.
 *              Alan Cox        :       Nonblocking error fix.
 *      Willy Konynenberg       :       Transparent proxying support.
 *              Mike McLagan    :       Routing by source
 *              David S. Miller :       New socket lookup architecture.
 *                                      Last socket cache retained as it
 *                                      does have a high hit rate.
 *              Olaf Kirch      :       Don't linearise iovec on sendmsg.
 *              Andi Kleen      :       Some cleanups, cache destination entry
 *                                      for connect. 
 *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
 *              Melvin Smith    :       Check msg_name not msg_namelen in sendto(),
 *                                      return ENOTCONN for unconnected sockets (POSIX)
 *              Janos Farkas    :       don't deliver multi/broadcasts to a different
 *                                      bound-to-device socket
 *      Hirokazu Takahashi      :       HW checksumming for outgoing UDP
 *                                      datagrams.
 *      Hirokazu Takahashi      :       sendfile() on UDP works now.
 *              Arnaldo C. Melo :       convert /proc/net/udp to seq_file
 *      YOSHIFUJI Hideaki @USAGI and:   Support IPV6_V6ONLY socket option, which
 *      Alexey Kuznetsov:               allow both IPv4 and IPv6 sockets to bind
 *                                      a single port at the same time.
 *      Derek Atkins <derek@ihtfp.com>: Add Encapulation Support
 *
 *
 *              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.
 */
 
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/config.h>
#include <linux/inet.h>
#include <linux/ipv6.h>
#include <linux/netdevice.h>
#include <net/snmp.h>
#include <net/tcp.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>

/*
 *      Snmp MIB for the UDP layer
 */

DEFINE_SNMP_STAT(struct udp_mib, udp_statistics);

struct hlist_head udp_hash[UDP_HTABLE_SIZE];
rwlock_t udp_hash_lock = RW_LOCK_UNLOCKED;

/* Shared by v4/v6 udp. */
int udp_port_rover;

static int udp_v4_get_port(struct sock *sk, unsigned short snum)
{
        struct hlist_node *node;
        struct sock *sk2;
        struct inet_opt *inet = inet_sk(sk);

        write_lock_bh(&udp_hash_lock);
        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];
                best_size_so_far = 32767;
                best = result = udp_port_rover;
                for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
                        struct hlist_head *list;
                        int size;

                        list = &udp_hash[result & (UDP_HTABLE_SIZE - 1)];
                        if (hlist_empty(list)) {
                                if (result > sysctl_local_port_range[1])
                                        result = sysctl_local_port_range[0] +
                                                ((result - sysctl_local_port_range[0]) &
                                                 (UDP_HTABLE_SIZE - 1));
                                goto gotit;
                        }
                        size = 0;
                        sk_for_each(sk2, node, list)
                                if (++size >= best_size_so_far)
                                        goto next;
                        best_size_so_far = size;
                        best = result;
                next:;
                }
                result = best;
                for(i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++, result += UDP_HTABLE_SIZE) {
                        if (result > sysctl_local_port_range[1])
                                result = sysctl_local_port_range[0]
                                        + ((result - sysctl_local_port_range[0]) &
                                           (UDP_HTABLE_SIZE - 1));
                        if (!udp_lport_inuse(result))
                                break;
                }
                if (i >= (1 << 16) / UDP_HTABLE_SIZE)
                        goto fail;
gotit:
                udp_port_rover = snum = result;
        } else {
                sk_for_each(sk2, node,
                            &udp_hash[snum & (UDP_HTABLE_SIZE - 1)]) {
                        struct inet_opt *inet2 = inet_sk(sk2);

                        if (inet2->num == snum &&
                            sk2 != sk &&
                            !ipv6_only_sock(sk2) &&
                            sk2->sk_bound_dev_if == sk->sk_bound_dev_if &&
                            (!inet2->rcv_saddr ||
                             !inet->rcv_saddr ||
                             inet2->rcv_saddr == inet->rcv_saddr) &&
                            (!sk2->sk_reuse || !sk->sk_reuse))
                                goto fail;
                }
        }
        inet->num = snum;
        if (sk_unhashed(sk)) {
                struct hlist_head *h = &udp_hash[snum & (UDP_HTABLE_SIZE - 1)];

                sk_add_node(sk, h);
                sock_prot_inc_use(sk->sk_prot);
        }
        write_unlock_bh(&udp_hash_lock);
        return 0;

fail:
        write_unlock_bh(&udp_hash_lock);
        return 1;
}

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
 */
struct sock *udp_v4_lookup_longway(u32 saddr, u16 sport, u32 daddr, u16 dport, int dif)
{
        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)]) {
                struct inet_opt *inet = inet_sk(sk);

                if (inet->num == hnum && !ipv6_only_sock(sk)) {
                        int score = (sk->sk_family == PF_INET ? 1 : 0);
                        if (inet->rcv_saddr) {
                                if (inet->rcv_saddr != daddr)
                                        continue;
                                score+=2;
                        }
                        if (inet->daddr) {
                                if (inet->daddr != saddr)
                                        continue;
                                score+=2;
                        }
                        if (inet->dport) {
                                if (inet->dport != sport)
                                        continue;
                                score+=2;
                        }
                        if (sk->sk_bound_dev_if) {
                                if (sk->sk_bound_dev_if != dif)
                                        continue;
                                score+=2;
                        }
                        if(score == 9) {
                                result = sk;
                                break;
                        } else if(score > badness) {
                                result = sk;
                                badness = score;
                        }
                }
        }
        return result;
}

__inline__ struct sock *udp_v4_lookup(u32 saddr, u16 sport, u32 daddr, u16 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);
        read_unlock(&udp_hash_lock);
        return sk;
}

static inline struct sock *udp_v4_mcast_next(struct sock *sk,
                                             u16 loc_port, u32 loc_addr,
                                             u16 rmt_port, u32 rmt_addr,
                                             int dif)
{
        struct hlist_node *node;
        struct sock *s = sk;
        unsigned short hnum = ntohs(loc_port);

        sk_for_each_from(s, node) {
                struct inet_opt *inet = inet_sk(s);

                if (inet->num != hnum                                   ||
                    (inet->daddr && inet->daddr != rmt_addr)            ||
                    (inet->dport != rmt_port && inet->dport)            ||
                    (inet->rcv_saddr && inet->rcv_saddr != loc_addr)    ||
                    ipv6_only_sock(s)                                   ||
                    (s->sk_bound_dev_if && s->sk_bound_dev_if != dif))
                        continue;
                if (!ip_mc_sf_allow(sk, loc_addr, rmt_addr, dif))
                        continue;
                goto found;
        }
        s = NULL;
found:
        return s;
}

/*
 * This routine is called by the ICMP module when it gets some
 * sort of error condition.  If err < 0 then the socket should
 * be closed and the error returned to the user.  If err > 0
 * it's just the icmp type << 8 | icmp code.  
 * Header points to the ip header of the error packet. We move
 * on past this. Then (as it used to claim before adjustment)
 * header points to the first 8 bytes of the udp header.  We need
 * to find the appropriate port.
 */

void udp_err(struct sk_buff *skb, u32 info)
{
        struct inet_opt *inet;
        struct iphdr *iph = (struct iphdr*)skb->data;
        struct udphdr *uh = (struct udphdr*)(skb->data+(iph->ihl<<2));
        int type = skb->h.icmph->type;
        int code = skb->h.icmph->code;
        struct sock *sk;
        int harderr;
        int err;

        sk = udp_v4_lookup(iph->daddr, uh->dest, iph->saddr, uh->source, skb->dev->ifindex);
        if (sk == NULL) {
                ICMP_INC_STATS_BH(IcmpInErrors);
                return; /* No socket for error */
        }

        err = 0;
        harderr = 0;
        inet = inet_sk(sk);

        switch (type) {
        default:
        case ICMP_TIME_EXCEEDED:
                err = EHOSTUNREACH;
                break;
        case ICMP_SOURCE_QUENCH:
                goto out;
        case ICMP_PARAMETERPROB:
                err = EPROTO;
                harderr = 1;
                break;
        case ICMP_DEST_UNREACH:
                if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
                        if (inet->pmtudisc != IP_PMTUDISC_DONT) {
                                err = EMSGSIZE;
                                harderr = 1;
                                break;
                        }
                        goto out;
                }
                err = EHOSTUNREACH;
                if (code <= NR_ICMP_UNREACH) {
                        harderr = icmp_err_convert[code].fatal;
                        err = icmp_err_convert[code].errno;
                }
                break;
        }

        /*
         *      RFC1122: OK.  Passes ICMP errors back to application, as per 
         *      4.1.3.3.
         */
        if (!inet->recverr) {
                if (!harderr || sk->sk_state != TCP_ESTABLISHED)
                        goto out;
        } else {
                ip_icmp_error(sk, skb, err, uh->dest, info, (u8*)(uh+1));
        }
        sk->sk_err = err;
        sk->sk_error_report(sk);
out:
        sock_put(sk);
}

/*
 * Throw away all pending data and cancel the corking. Socket is locked.
 */
static void udp_flush_pending_frames(struct sock *sk)
{
        struct udp_opt *up = udp_sk(sk);

        if (up->pending) {
                up->pending = 0;
                ip_flush_pending_frames(sk);
        }
}

/*
 * Push out all pending data as one UDP datagram. Socket is locked.
 */
static int udp_push_pending_frames(struct sock *sk, struct udp_opt *up)
{
        struct sk_buff *skb;
        struct udphdr *uh;
        int err = 0;

        /* Grab the skbuff where UDP header space exists. */
        if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
                goto out;

        /*
         * Create a UDP header
         */
        uh = skb->h.uh;
        uh->source = up->sport;
        uh->dest = up->dport;
        uh->len = htons(up->len);
        uh->check = 0;

        if (sk->sk_no_check == UDP_CSUM_NOXMIT) {
                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_HW) {
                        skb->csum = offsetof(struct udphdr, check);
                        uh->check = ~csum_tcpudp_magic(up->saddr, up->daddr,
                                        up->len, IPPROTO_UDP, 0);
                } else {
                        skb->csum = csum_partial((char *)uh,
                                        sizeof(struct udphdr), skb->csum);
                        uh->check = csum_tcpudp_magic(up->saddr, up->daddr,
                                        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_HW) {
                        int offset = (unsigned char *)uh - skb->data;
                        skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);

                        skb->ip_summed = CHECKSUM_NONE;
                } else {
                        skb->csum = csum_partial((char *)uh,
                                        sizeof(struct udphdr), skb->csum);
                }

                skb_queue_walk(&sk->sk_write_queue, skb) {
                        csum = csum_add(csum, skb->csum);
                }
                uh->check = csum_tcpudp_magic(up->saddr, up->daddr,
                                up->len, IPPROTO_UDP, csum);
                if (uh->check == 0)
                        uh->check = -1;
        }
send:
        err = ip_push_pending_frames(sk);
out:
        up->len = 0;
        up->pending = 0;
        return err;
}


static unsigned short udp_check(struct udphdr *uh, int len, unsigned long saddr, unsigned long 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,
                int len)
{
        struct inet_opt *inet = inet_sk(sk);
        struct udp_opt *up = udp_sk(sk);
        int ulen = len;
        struct ipcm_cookie ipc;
        struct rtable *rt = NULL;
        int free = 0;
        int connected = 0;
        u32 daddr, faddr, saddr;
        u16 dport;
        u8  tos;
        int err;
        int corkreq = up->corkflag || msg->msg_flags&MSG_MORE;

        /* This check is ONLY to check for arithmetic overflow
           on integer(!) len. Not more! Real check will be made
           in ip_append_* --ANK

           BTW socket.c -> af_*.c -> ... make multiple
           invalid conversions size_t -> int. We MUST repair it f.e.
           by replacing all of them with size_t and revise all
           the places sort of len += sizeof(struct iphdr)
           If len was ULONG_MAX-10 it would be cathastrophe  --ANK
         */

        if (len < 0 || len > 0xFFFF)
                return -EMSGSIZE;

        /* 
         *      Check the flags.
         */

        if (msg->msg_flags&MSG_OOB)     /* Mirror BSD error message compatibility */
                return -EOPNOTSUPP;

        ipc.opt = NULL;

        if (up->pending) {
                /*
                 * There are pending frames.
                 * The socket lock must be held while it's corked.
                 */
                lock_sock(sk);
                if (likely(up->pending))
                        goto do_append_data;
                release_sock(sk);
        }
        ulen += sizeof(struct udphdr);

        /*
         *      Get and verify the address. 
         */
        if (msg->msg_name) {
                struct sockaddr_in * usin = (struct sockaddr_in*)msg->msg_name;
                if (msg->msg_namelen < sizeof(*usin))
                        return -EINVAL;
                if (usin->sin_family != AF_INET) {
                        if (usin->sin_family != AF_UNSPEC)
                                return -EINVAL;
                }

                daddr = usin->sin_addr.s_addr;
                dport = usin->sin_port;
                if (dport == 0)
                        return -EINVAL;
        } else {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;
                daddr = inet->daddr;
                dport = inet->dport;
                /* Open fast path for connected socket.
                   Route will not be used, if at least one option is set.
                 */
                connected = 1;
        }
        ipc.addr = inet->saddr;

        ipc.oif = sk->sk_bound_dev_if;
        if (msg->msg_controllen) {
                err = ip_cmsg_send(msg, &ipc);
                if (err)
                        return err;
                if (ipc.opt)
                        free = 1;
                connected = 0;
        }
        if (!ipc.opt)
                ipc.opt = inet->opt;

        saddr = ipc.addr;
        ipc.addr = faddr = daddr;

        if (ipc.opt && ipc.opt->srr) {
                if (!daddr)
                        return -EINVAL;
                faddr = ipc.opt->faddr;
                connected = 0;
        }
        tos = RT_TOS(inet->tos);
        if (sk->sk_localroute || (msg->msg_flags & MSG_DONTROUTE) || 
            (ipc.opt && ipc.opt->is_strictroute)) {
                tos |= RTO_ONLINK;
                connected = 0;
        }

        if (MULTICAST(daddr)) {
                if (!ipc.oif)
                        ipc.oif = inet->mc_index;
                if (!saddr)
                        saddr = inet->mc_addr;
                connected = 0;
        }

        if (connected)
                rt = (struct rtable*)sk_dst_check(sk, 0);

        if (rt == NULL) {
                struct flowi fl = { .oif = ipc.oif,
                                    .nl_u = { .ip4_u =
                                              { .daddr = faddr,
                                                .saddr = saddr,
                                                .tos = tos } },
                                    .proto = IPPROTO_UDP,
                                    .uli_u = { .ports =
                                               { .sport = inet->sport,
                                                 .dport = dport } } };
                err = ip_route_output_flow(&rt, &fl, sk, !(msg->msg_flags&MSG_DONTWAIT));
                if (err)
                        goto out;

                err = -EACCES;
                if ((rt->rt_flags & RTCF_BROADCAST) &&
                    !sock_flag(sk, SOCK_BROADCAST))
                        goto out;
                if (connected)
                        sk_dst_set(sk, dst_clone(&rt->u.dst));
        }

        if (msg->msg_flags&MSG_CONFIRM)
                goto do_confirm;
back_from_confirm:

        saddr = rt->rt_src;
        if (!ipc.addr)
                daddr = ipc.addr = rt->rt_dst;

        lock_sock(sk);
        if (unlikely(up->pending)) {
                /* The socket is already corked while preparing it. */
                /* ... which is an evident application bug. --ANK */
                release_sock(sk);

                NETDEBUG(if (net_ratelimit()) printk(KERN_DEBUG "udp cork app bug 2\n"));
                err = -EINVAL;
                goto out;
        }
        /*
         *      Now cork the socket to pend data.
         */
        up->daddr = daddr;
        up->dport = dport;
        up->saddr = saddr;
        up->sport = inet->sport;
        up->pending = 1;

do_append_data:
        up->len += ulen;
        err = ip_append_data(sk, ip_generic_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);
        else if (!corkreq)
                err = udp_push_pending_frames(sk, up);
        release_sock(sk);

out:
        ip_rt_put(rt);
        if (free)
                kfree(ipc.opt);
        if (!err) {
                UDP_INC_STATS_USER(UdpOutDatagrams);
                return len;
        }
        return err;

do_confirm:
        dst_confirm(&rt->u.dst);
        if (!(msg->msg_flags&MSG_PROBE) || len)
                goto back_from_confirm;
        err = 0;
        goto out;
}

int udp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, int flags)
{
        struct udp_opt *up = udp_sk(sk);
        int ret;

        if (!up->pending) {
                struct msghdr msg = {   .msg_flags = flags|MSG_MORE };

                /* Call udp_sendmsg to specify destination address which
                 * sendpage interface can't pass.
                 * This will succeed only when the socket is connected.
                 */
                ret = udp_sendmsg(NULL, sk, &msg, 0);
                if (ret < 0)
                        return ret;
        }

        lock_sock(sk);

        if (unlikely(!up->pending)) {
                release_sock(sk);

                NETDEBUG(if (net_ratelimit()) printk(KERN_DEBUG "udp cork app bug 3\n"));
                return -EINVAL;
        }

        ret = ip_append_page(sk, page, offset, size, flags);
        if (ret == -EOPNOTSUPP) {
                release_sock(sk);
                return sock_no_sendpage(sk->sk_socket, page, offset,
                                        size, flags);
        }
        if (ret < 0) {
                udp_flush_pending_frames(sk);
                goto out;
        }

        up->len += size;
        if (!(up->corkflag || (flags&MSG_MORE)))
                ret = udp_push_pending_frames(sk, up);
        if (!ret)
                ret = size;
out:
        release_sock(sk);
        return ret;
}

/*
 *      IOCTL requests applicable to the UDP protocol
 */
 
int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
        switch(cmd) 
        {
                case SIOCOUTQ:
                {
                        int amount = atomic_read(&sk->sk_wmem_alloc);
                        return put_user(amount, (int *)arg);
                }

                case SIOCINQ:
                {
                        struct sk_buff *skb;
                        unsigned long amount;

                        amount = 0;
                        spin_lock_irq(&sk->sk_receive_queue.lock);
                        skb = skb_peek(&sk->sk_receive_queue);
                        if (skb != NULL) {
                                /*
                                 * We will only return the amount
                                 * of this packet since that is all
                                 * that will be read.
                                 */
                                amount = skb->len - sizeof(struct udphdr);
                        }
                        spin_unlock_irq(&sk->sk_receive_queue.lock);
                        return put_user(amount, (int *)arg);
                }

                default:
                        return -ENOIOCTLCMD;
        }
        return(0);
}

static __inline__ int __udp_checksum_complete(struct sk_buff *skb)
{
        return (unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum));
}

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.
 */

int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                int len, int noblock, int flags, int *addr_len)
{
        struct inet_opt *inet = inet_sk(sk);
        struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
        struct sk_buff *skb;
        int copied, err;

        /*
         *      Check any passed addresses
         */
        if (addr_len)
                *addr_len=sizeof(*sin);

        if (flags & MSG_ERRQUEUE)
                return ip_recv_error(sk, msg, len);

        skb = skb_recv_datagram(sk, flags, noblock, &err);
        if (!skb)
                goto out;
  
        copied = skb->len - sizeof(struct udphdr);
        if (copied > len) {
                copied = len;
                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))
                        goto csum_copy_err;
                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)
                        goto csum_copy_err;
        }

        if (err)
                goto out_free;

        sock_recv_timestamp(msg, sk, skb);

        /* Copy the address. */
        if (sin)
        {
                sin->sin_family = AF_INET;
                sin->sin_port = skb->h.uh->source;
                sin->sin_addr.s_addr = skb->nh.iph->saddr;
                memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
        }
        if (inet->cmsg_flags)
                ip_cmsg_recv(msg, skb);
        err = copied;
  
out_free:
        skb_free_datagram(sk, skb);
out:
        return err;

csum_copy_err:
        UDP_INC_STATS_BH(UdpInErrors);

        /* Clear queue. */
        if (flags&MSG_PEEK) {
                int clear = 0;
                spin_lock_irq(&sk->sk_receive_queue.lock);
                if (skb == skb_peek(&sk->sk_receive_queue)) {
                        __skb_unlink(skb, &sk->sk_receive_queue);
                        clear = 1;
                }
                spin_unlock_irq(&sk->sk_receive_queue.lock);
                if (clear)
                        kfree_skb(skb);
        }

        skb_free_datagram(sk, skb);

        return -EAGAIN; 
}

int udp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
        struct inet_opt *inet = inet_sk(sk);
        struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
        struct rtable *rt;
        u32 saddr;
        int oif;
        int err;

        
        if (addr_len < sizeof(*usin)) 
                return -EINVAL;

        if (usin->sin_family != AF_INET) 
                return -EAFNOSUPPORT;

        sk_dst_reset(sk);

        oif = sk->sk_bound_dev_if;
        saddr = inet->saddr;
        if (MULTICAST(usin->sin_addr.s_addr)) {
                if (!oif)
                        oif = inet->mc_index;
                if (!saddr)
                        saddr = inet->mc_addr;
        }
        err = ip_route_connect(&rt, usin->sin_addr.s_addr, saddr,
                               RT_CONN_FLAGS(sk), oif,
                               IPPROTO_UDP,
                               inet->sport, usin->sin_port, sk);
        if (err)
                return err;
        if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
                ip_rt_put(rt);
                return -EACCES;
        }
        if (!inet->saddr)
                inet->saddr = rt->rt_src;       /* Update source address */
        if (!inet->rcv_saddr)
                inet->rcv_saddr = rt->rt_src;
        inet->daddr = rt->rt_dst;
        inet->dport = usin->sin_port;
        sk->sk_state = TCP_ESTABLISHED;
        inet->id = jiffies;

        sk_dst_set(sk, &rt->u.dst);
        return(0);
}

int udp_disconnect(struct sock *sk, int flags)
{
        struct inet_opt *inet = inet_sk(sk);
        /*
         *      1003.1g - break association.
         */
         
        sk->sk_state = TCP_CLOSE;
        inet->daddr = 0;
        inet->dport = 0;
        sk->sk_bound_dev_if = 0;
        if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
                inet_reset_saddr(sk);

        if (!(sk->sk_userlocks & SOCK_BINDPORT_LOCK)) {
                sk->sk_prot->unhash(sk);
                inet->sport = 0;
        }
        sk_dst_reset(sk);
        return 0;
}

static void udp_close(struct sock *sk, long timeout)
{
        inet_sock_release(sk);
}

/* return:
 *      1  if the the UDP system should process it
 *      0  if we should drop this packet
 *      -1 if it should get processed by xfrm4_rcv_encap
 */
static int udp_encap_rcv(struct sock * sk, struct sk_buff *skb)
{
        struct udp_opt *up = udp_sk(sk);
        struct udphdr *uh = skb->h.uh;
        struct iphdr *iph;
        int iphlen, len;
  
        __u8 *udpdata = (__u8 *)uh + sizeof(struct udphdr);
        __u32 *udpdata32 = (__u32 *)udpdata;
        __u16 encap_type = up->encap_type;

        /* if we're overly short, let UDP handle it */
        if (udpdata > skb->tail)
                return 1;

        /* if this is not encapsulated socket, then just return now */
        if (!encap_type)
                return 1;

        len = skb->tail - udpdata;

        switch (encap_type) {
        case UDP_ENCAP_ESPINUDP:
                /* Check if this is a keepalive packet.  If so, eat it. */
                if (len == 1 && udpdata[0] == 0xff) {
                        return 0;
                } else if (len > sizeof(struct ip_esp_hdr) && udpdata32[0] != 0 ) {
                        /* ESP Packet without Non-ESP header */
                        len = sizeof(struct udphdr);
                } else
                        /* Must be an IKE packet.. pass it through */
                        return 1;

                /* At this point we are sure that this is an ESPinUDP packet,
                 * so we need to remove 'len' bytes from the packet (the UDP
                 * header and optional ESP marker bytes) and then modify the
                 * protocol to ESP, and then call into the transform receiver.
                 */

                /* Now we can update and verify the packet length... */
                iph = skb->nh.iph;
                iphlen = iph->ihl << 2;
                iph->tot_len = htons(ntohs(iph->tot_len) - len);
                if (skb->len < iphlen + len) {
                        /* packet is too small!?! */
                        return 0;
                }

                /* pull the data buffer up to the ESP header and set the
                 * transport header to point to ESP.  Keep UDP on the stack
                 * for later.
                 */
                skb->h.raw = skb_pull(skb, len);

                /* modify the protocol (it's ESP!) */
                iph->protocol = IPPROTO_ESP;

                /* and let the caller know to send this into the ESP processor... */
                return -1;

        default:
                printk(KERN_INFO "udp_encap_rcv(): Unhandled UDP encap type: %u\n",
                       encap_type);
                return 1;
        }
}

/* returns:
 *  -1: error
 *   0: success
 *  >0: "udp encap" protocol resubmission
 *
 * 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)
{
        struct udp_opt *up = udp_sk(sk);

        /*
         *      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 (up->encap_type) {
                /*
                 * This is an encapsulation socket, so let's see if this is
                 * an encapsulated packet.
                 * If it's a keepalive packet, then just eat it.
                 * If it's an encapsulateed packet, then pass it to the
                 * IPsec xfrm input and return the response
                 * appropriately.  Otherwise, just fall through and
                 * pass this up the UDP socket.
                 */
                int ret;

                ret = udp_encap_rcv(sk, skb);
                if (ret == 0) {
                        /* Eat the packet .. */
                        kfree_skb(skb);
                        return 0;
                }
                if (ret < 0) {
                        /* process the ESP packet */
                        ret = xfrm4_rcv_encap(skb, up->encap_type);
                        UDP_INC_STATS_BH(UdpInDatagrams);
                        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(UdpInErrors);
                        kfree_skb(skb);
                        return -1;
                }
                skb->ip_summed = CHECKSUM_UNNECESSARY;
        }

        if (sock_queue_rcv_skb(sk,skb)<0) {
                UDP_INC_STATS_BH(UdpInErrors);
                kfree_skb(skb);
                return -1;
        }
        UDP_INC_STATS_BH(UdpInDatagrams);
        return 0;
}

/*
 *      Multicasts and broadcasts go to each listener.
 *
 *      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,
                                 u32 saddr, u32 daddr)
{
        struct sock *sk;
        int dif;

        read_lock(&udp_hash_lock);
        sk = sk_head(&udp_hash[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) {
                struct sock *sknext = NULL;

                do {
                        struct sk_buff *skb1 = skb;

                        sknext = udp_v4_mcast_next(sk_next(sk), uh->dest, daddr,
                                                   uh->source, saddr, dif);
                        if(sknext)
                                skb1 = skb_clone(skb, GFP_ATOMIC);

                        if(skb1) {
                                int ret = udp_queue_rcv_skb(sk, skb1);
                                if (ret > 0)
                                        /* we should probably re-process instead
                                         * of dropping packets here. */
                                        kfree_skb(skb1);
                        }
                        sk = sknext;
                } while(sknext);
        } else
                kfree_skb(skb);
        read_unlock(&udp_hash_lock);
        return 0;
}

/* Initialize UDP checksum. If exited with zero value (success),
 * CHECKSUM_UNNECESSARY means, that no more checks are required.
 * Otherwise, csum completion requires chacksumming packet body,
 * including udp header and folding it to skb->csum.
 */
static int udp_checksum_init(struct sk_buff *skb, struct udphdr *uh,
                             unsigned short ulen, u32 saddr, u32 daddr)
{
        if (uh->check == 0) {
                skb->ip_summed = CHECKSUM_UNNECESSARY;
        } else if (skb->ip_summed == CHECKSUM_HW) {
                skb->ip_summed = CHECKSUM_UNNECESSARY;
                if (!udp_check(uh, ulen, saddr, daddr, skb->csum))
                        return 0;
                NETDEBUG(if (net_ratelimit()) printk(KERN_DEBUG "udp v4 hw csum failure.\n"));
                skb->ip_summed = CHECKSUM_NONE;
        }
        if (skb->ip_summed != CHECKSUM_UNNECESSARY)
                skb->csum = csum_tcpudp_nofold(saddr, daddr, ulen, IPPROTO_UDP, 0);
        /* Probably, we should checksum udp header (it should be in cache
         * in any case) and data in tiny packets (< rx copybreak).
         */
        return 0;
}

/*
 *      All we need to do is get the socket, and then do a checksum. 
 */
 
int udp_rcv(struct sk_buff *skb)
{
        struct sock *sk;
        struct udphdr *uh;
        unsigned short ulen;
        struct rtable *rt = (struct rtable*)skb->dst;
        u32 saddr = skb->nh.iph->saddr;
        u32 daddr = skb->nh.iph->daddr;
        int len = skb->len;

        /*
         *      Validate the packet and the UDP length.
         */
        if (!pskb_may_pull(skb, sizeof(struct udphdr)))
                goto no_header;

        uh = skb->h.uh;

        ulen = ntohs(uh->len);

        if (ulen > len || ulen < sizeof(*uh))
                goto short_packet;

        if (pskb_trim(skb, ulen))
                goto short_packet;

        if (udp_checksum_init(skb, uh, ulen, saddr, daddr) < 0)
                goto csum_error;

        if(rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
                return udp_v4_mcast_deliver(skb, uh, saddr, daddr);

        sk = udp_v4_lookup(saddr, uh->source, daddr, uh->dest, skb->dev->ifindex);

        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
                 */
                if (ret > 0)
                        return -ret;
                return 0;
        }

        if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
                goto drop;

        /* No socket. Drop packet silently, if checksum is wrong */
        if (udp_checksum_complete(skb))
                goto csum_error;

        UDP_INC_STATS_BH(UdpNoPorts);
        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);

        /*
         * Hmm.  We got an UDP packet to a port to which we
         * don't wanna listen.  Ignore it.
         */
        kfree_skb(skb);
        return(0);

short_packet:
        NETDEBUG(if (net_ratelimit())
                printk(KERN_DEBUG "UDP: short packet: From %u.%u.%u.%u:%u %d/%d to %u.%u.%u.%u:%u\n",
                        NIPQUAD(saddr),
                        ntohs(uh->source),
                        ulen,
                        len,
                        NIPQUAD(daddr),
                        ntohs(uh->dest)));
no_header:
        UDP_INC_STATS_BH(UdpInErrors);
        kfree_skb(skb);
        return(0);

csum_error:
        /* 
         * RFC1122: OK.  Discards the bad packet silently (as far as 
         * the network is concerned, anyway) as per 4.1.3.4 (MUST). 
         */
        NETDEBUG(if (net_ratelimit())
                 printk(KERN_DEBUG "UDP: bad checksum. From %d.%d.%d.%d:%d to %d.%d.%d.%d:%d ulen %d\n",
                        NIPQUAD(saddr),
                        ntohs(uh->source),
                        NIPQUAD(daddr),
                        ntohs(uh->dest),
                        ulen));
drop:
        UDP_INC_STATS_BH(UdpInErrors);
        kfree_skb(skb);
        return(0);
}

static int udp_destroy_sock(struct sock *sk)
{
        lock_sock(sk);
        udp_flush_pending_frames(sk);
        release_sock(sk);
        return 0;
}

/*
 *      Socket option code for UDP
 */
static int udp_setsockopt(struct sock *sk, int level, int optname, 
                          char *optval, int optlen)
{
        struct udp_opt *up = udp_sk(sk);
        int val;
        int err = 0;

        if (level != SOL_UDP)
                return ip_setsockopt(sk, level, optname, optval, optlen);

        if(optlen<sizeof(int))
                return -EINVAL;

        if (get_user(val, (int *)optval))
                return -EFAULT;

        switch(optname) {
        case UDP_CORK:
                if (val != 0) {
                        up->corkflag = 1;
                } else {
                        up->corkflag = 0;
                        lock_sock(sk);
                        udp_push_pending_frames(sk, up);
                        release_sock(sk);
                }
                break;
                
        case UDP_ENCAP:
                up->encap_type = val;
                break;

        default:
                err = -ENOPROTOOPT;
                break;
        };

        return err;
}

static int udp_getsockopt(struct sock *sk, int level, int optname, 
                          char *optval, int *optlen)
{
        struct udp_opt *up = udp_sk(sk);
        int val, len;

        if (level != SOL_UDP)
                return ip_getsockopt(sk, level, optname, optval, optlen);

        if(get_user(len,optlen))
                return -EFAULT;

        len = min_t(unsigned int, len, sizeof(int));
        
        if(len < 0)
                return -EINVAL;

        switch(optname) {
        case UDP_CORK:
                val = up->corkflag;
                break;

        case UDP_ENCAP:
                val = up->encap_type;
                break;

        default:
                return -ENOPROTOOPT;
        };

        if(put_user(len, optlen))
                return -EFAULT;
        if(copy_to_user(optval, &val,len))
                return -EFAULT;
        return 0;
}


struct proto udp_prot = {
        .name =         "UDP",
        .close =        udp_close,
        .connect =      udp_connect,
        .disconnect =   udp_disconnect,
        .ioctl =        udp_ioctl,
        .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_v4_hash,
        .unhash =       udp_v4_unhash,
        .get_port =     udp_v4_get_port,
};

/* ------------------------------------------------------------------------ */
#ifdef CONFIG_PROC_FS

static __inline__ struct sock *udp_get_bucket(struct seq_file *seq, loff_t *pos)
{
        int i;
        struct sock *sk;
        struct hlist_node *node;
        loff_t l = *pos;
        struct udp_iter_state *state = seq->private;

        for (; state->bucket < UDP_HTABLE_SIZE; ++state->bucket) {
                i = 0;
                sk_for_each(sk, node, &udp_hash[state->bucket]) {
                        if (sk->sk_family != state->family) {
                                ++i;
                                continue;
                        }
                        if (l--) {
                                ++i;
                                continue;
                        }
                        *pos = i;
                        goto out;
                }
        }
        sk = NULL;
out:
        return sk;
}

static void *udp_seq_start(struct seq_file *seq, loff_t *pos)
{
        read_lock(&udp_hash_lock);
        return *pos ? udp_get_bucket(seq, pos) : (void *)1;
}

static void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct sock *sk;
        struct hlist_node *node;
        struct udp_iter_state *state;

        if (v == (void *)1) {
                sk = udp_get_bucket(seq, pos);
                goto out;
        }

        state = seq->private;

        sk = v;
        sk_for_each_continue(sk, node)
                if (sk->sk_family == state->family)
                        goto out;

        if (++state->bucket >= UDP_HTABLE_SIZE) 
                goto out;

        *pos = 0;
        sk = udp_get_bucket(seq, pos);
out:
        ++*pos;
        return sk;
}

static void udp_seq_stop(struct seq_file *seq, void *v)
{
        read_unlock(&udp_hash_lock);
}

static int udp_seq_open(struct inode *inode, struct file *file)
{
        struct udp_seq_afinfo *afinfo = PDE(inode)->data;
        struct seq_file *seq;
        int rc = -ENOMEM;
        struct udp_iter_state *s = kmalloc(sizeof(*s), GFP_KERNEL);

        if (!s)
                goto out;
        memset(s, 0, sizeof(*s));
        s->family               = afinfo->family;
        s->seq_ops.start        = udp_seq_start;
        s->seq_ops.next         = udp_seq_next;
        s->seq_ops.show         = afinfo->seq_show;
        s->seq_ops.stop         = udp_seq_stop;

        rc = seq_open(file, &s->seq_ops);
        if (rc)
                goto out_kfree;

        seq          = file->private_data;
        seq->private = s;
out:
        return rc;
out_kfree:
        kfree(s);
        goto out;
}

/* ------------------------------------------------------------------------ */
int udp_proc_register(struct udp_seq_afinfo *afinfo)
{
        struct proc_dir_entry *p;
        int rc = 0;

        if (!afinfo)
                return -EINVAL;
        afinfo->seq_fops->owner         = afinfo->owner;
        afinfo->seq_fops->open          = udp_seq_open;
        afinfo->seq_fops->read          = seq_read;
        afinfo->seq_fops->llseek        = seq_lseek;
        afinfo->seq_fops->release       = seq_release_private;

        p = create_proc_entry(afinfo->name, S_IRUGO, proc_net);
        if (p) {
                p->data = afinfo;
                p->proc_fops = afinfo->seq_fops;
        } else
                rc = -ENOMEM;
        return rc;
}

void udp_proc_unregister(struct udp_seq_afinfo *afinfo)
{
        if (!afinfo)
                return;
        remove_proc_entry(afinfo->name, proc_net);
        memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops));
}

/* ------------------------------------------------------------------------ */
static void udp4_format_sock(struct sock *sp, char *tmpbuf, int bucket)
{
        struct inet_opt *inet = inet_sk(sp);
        unsigned int dest = inet->daddr;
        unsigned int src  = inet->rcv_saddr;
        __u16 destp       = ntohs(inet->dport);
        __u16 srcp        = ntohs(inet->sport);

        sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
                " %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p",
                bucket, src, srcp, dest, destp, sp->sk_state, 
                atomic_read(&sp->sk_wmem_alloc),
                atomic_read(&sp->sk_rmem_alloc),
                0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
                atomic_read(&sp->sk_refcnt), sp);
}

static int udp4_seq_show(struct seq_file *seq, void *v)
{
        if (v == (void *)1)
                seq_printf(seq, "%-127s\n",
                           "  sl  local_address rem_address   st tx_queue "
                           "rx_queue tr tm->when retrnsmt   uid  timeout "
                           "inode");
        else {
                char tmpbuf[129];
                struct udp_iter_state *state = seq->private;

                udp4_format_sock(v, tmpbuf, state->bucket);
                seq_printf(seq, "%-127s\n", tmpbuf);
        }
        return 0;
}

/* ------------------------------------------------------------------------ */
static struct file_operations udp4_seq_fops;
static struct udp_seq_afinfo udp4_seq_afinfo = {
        .owner          = THIS_MODULE,
        .name           = "udp",
        .family         = AF_INET,
        .seq_show       = udp4_seq_show,
        .seq_fops       = &udp4_seq_fops,
};

int __init udp4_proc_init(void)
{
        return udp_proc_register(&udp4_seq_afinfo);
}

void udp4_proc_exit(void)
{
        udp_proc_unregister(&udp4_seq_afinfo);
}
#endif /* CONFIG_PROC_FS */