/*
 * 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.
 *
 *              PF_INET protocol family socket handler.
 *
 * Version:     $Id: af_inet.c,v 1.137 2002/02/01 22:01:03 davem Exp $
 *
 * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *              Florian La Roche, <flla@stud.uni-sb.de>
 *              Alan Cox, <A.Cox@swansea.ac.uk>
 *
 * Changes (see also sock.c)
 *
 *              piggy,
 *              Karl Knutson    :       Socket protocol table
 *              A.N.Kuznetsov   :       Socket death error in accept().
 *              John Richardson :       Fix non blocking error in connect()
 *                                      so sockets that fail to connect
 *                                      don't return -EINPROGRESS.
 *              Alan Cox        :       Asynchronous I/O support
 *              Alan Cox        :       Keep correct socket pointer on sock
 *                                      structures
 *                                      when accept() ed
 *              Alan Cox        :       Semantics of SO_LINGER aren't state
 *                                      moved to close when you look carefully.
 *                                      With this fixed and the accept bug fixed
 *                                      some RPC stuff seems happier.
 *              Niibe Yutaka    :       4.4BSD style write async I/O
 *              Alan Cox,
 *              Tony Gale       :       Fixed reuse semantics.
 *              Alan Cox        :       bind() shouldn't abort existing but dead
 *                                      sockets. Stops FTP netin:.. I hope.
 *              Alan Cox        :       bind() works correctly for RAW sockets.
 *                                      Note that FreeBSD at least was broken
 *                                      in this respect so be careful with
 *                                      compatibility tests...
 *              Alan Cox        :       routing cache support
 *              Alan Cox        :       memzero the socket structure for
 *                                      compactness.
 *              Matt Day        :       nonblock connect error handler
 *              Alan Cox        :       Allow large numbers of pending sockets
 *                                      (eg for big web sites), but only if
 *                                      specifically application requested.
 *              Alan Cox        :       New buffering throughout IP. Used
 *                                      dumbly.
 *              Alan Cox        :       New buffering now used smartly.
 *              Alan Cox        :       BSD rather than common sense
 *                                      interpretation of listen.
 *              Germano Caronni :       Assorted small races.
 *              Alan Cox        :       sendmsg/recvmsg basic support.
 *              Alan Cox        :       Only sendmsg/recvmsg now supported.
 *              Alan Cox        :       Locked down bind (see security list).
 *              Alan Cox        :       Loosened bind a little.
 *              Mike McLagan    :       ADD/DEL DLCI Ioctls
 *      Willy Konynenberg       :       Transparent proxying support.
 *              David S. Miller :       New socket lookup architecture.
 *                                      Some other random speedups.
 *              Cyrus Durgin    :       Cleaned up file for kmod hacks.
 *              Andi Kleen      :       Fix inet_stream_connect TCP race.
 *
 *              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 <linux/config.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/netfilter_ipv4.h>

#include <asm/uaccess.h>
#include <asm/system.h>

#include <linux/smp_lock.h>
#include <linux/inet.h>
#include <linux/igmp.h>
#include <linux/netdevice.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/arp.h>
#include <net/route.h>
#include <net/ip_fib.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/raw.h>
#include <net/icmp.h>
#include <net/ipip.h>
#include <net/inet_common.h>
#include <net/xfrm.h>
#ifdef CONFIG_IP_MROUTE
#include <linux/mroute.h>
#endif

DEFINE_SNMP_STAT(struct linux_mib, net_statistics);

#ifdef INET_REFCNT_DEBUG
atomic_t inet_sock_nr;
#endif

extern void ip_mc_drop_socket(struct sock *sk);

/* Per protocol sock slabcache */
kmem_cache_t *tcp_sk_cachep;
static kmem_cache_t *udp_sk_cachep;
static kmem_cache_t *raw4_sk_cachep;

/* The inetsw table contains everything that inet_create needs to
 * build a new socket.
 */
static struct list_head inetsw[SOCK_MAX];
static spinlock_t inetsw_lock = SPIN_LOCK_UNLOCKED;

/* New destruction routine */

void inet_sock_destruct(struct sock *sk)
{
        struct inet_opt *inet = inet_sk(sk);

        __skb_queue_purge(&sk->sk_receive_queue);
        __skb_queue_purge(&sk->sk_error_queue);

        if (sk->sk_type == SOCK_STREAM && sk->sk_state != TCP_CLOSE) {
                printk("Attempt to release TCP socket in state %d %p\n",
                       sk->sk_state, sk);
                return;
        }
        if (!sock_flag(sk, SOCK_DEAD)) {
                printk("Attempt to release alive inet socket %p\n", sk);
                return;
        }

        BUG_TRAP(!atomic_read(&sk->sk_rmem_alloc));
        BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc));
        BUG_TRAP(!sk->sk_wmem_queued);
        BUG_TRAP(!sk->sk_forward_alloc);

        if (inet->opt)
                kfree(inet->opt);
        dst_release(sk->sk_dst_cache);
#ifdef INET_REFCNT_DEBUG
        atomic_dec(&inet_sock_nr);
        printk(KERN_DEBUG "INET socket %p released, %d are still alive\n",
               sk, atomic_read(&inet_sock_nr));
#endif
}

void inet_sock_release(struct sock *sk)
{
        if (sk->sk_prot->destroy)
                sk->sk_prot->destroy(sk);

        /* Observation: when inet_sock_release is called, processes have
         * no access to socket. But net still has.
         * Step one, detach it from networking:
         *
         * A. Remove from hash tables.
         */

        sk->sk_prot->unhash(sk);

        /* In this point socket cannot receive new packets,
         * but it is possible that some packets are in flight
         * because some CPU runs receiver and did hash table lookup
         * before we unhashed socket. They will achieve receive queue
         * and will be purged by socket destructor.
         *
         * Also we still have packets pending on receive
         * queue and probably, our own packets waiting in device queues.
         * sock_destroy will drain receive queue, but transmitted
         * packets will delay socket destruction until the last reference
         * will be released.
         */

        sock_orphan(sk);

        xfrm_sk_free_policy(sk);

#ifdef INET_REFCNT_DEBUG
        if (atomic_read(&sk->sk_refcnt) != 1)
                printk(KERN_DEBUG "Destruction inet %p delayed, c=%d\n",
                       sk, atomic_read(&sk->sk_refcnt));
#endif
        sock_put(sk);
}


/*
 *      The routines beyond this point handle the behaviour of an AF_INET
 *      socket object. Mostly it punts to the subprotocols of IP to do
 *      the work.
 */

/*
 *      Set socket options on an inet socket.
 */
int inet_setsockopt(struct socket *sock, int level, int optname,
                    char *optval, int optlen)
{
        struct sock *sk = sock->sk;

        return sk->sk_prot->setsockopt(sk, level, optname, optval, optlen);
}

/*
 *      Get a socket option on an AF_INET socket.
 *
 *      FIX: POSIX 1003.1g is very ambiguous here. It states that
 *      asynchronous errors should be reported by getsockopt. We assume
 *      this means if you specify SO_ERROR (otherwise whats the point of it).
 */

int inet_getsockopt(struct socket *sock, int level, int optname,
                    char *optval, int *optlen)
{
        struct sock *sk = sock->sk;

        return sk->sk_prot->getsockopt(sk, level, optname, optval, optlen);
}

/*
 *      Automatically bind an unbound socket.
 */

static int inet_autobind(struct sock *sk)
{
        struct inet_opt *inet;
        /* We may need to bind the socket. */
        lock_sock(sk);
        inet = inet_sk(sk);
        if (!inet->num) {
                if (sk->sk_prot->get_port(sk, 0)) {
                        release_sock(sk);
                        return -EAGAIN;
                }
                inet->sport = htons(inet->num);
        }
        release_sock(sk);
        return 0;
}

/*
 *      Move a socket into listening state.
 */
int inet_listen(struct socket *sock, int backlog)
{
        struct sock *sk = sock->sk;
        unsigned char old_state;
        int err;

        lock_sock(sk);

        err = -EINVAL;
        if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
                goto out;

        old_state = sk->sk_state;
        if (!((1 << old_state) & (TCPF_CLOSE | TCPF_LISTEN)))
                goto out;

        /* Really, if the socket is already in listen state
         * we can only allow the backlog to be adjusted.
         */
        if (old_state != TCP_LISTEN) {
                err = tcp_listen_start(sk);
                if (err)
                        goto out;
        }
        sk->sk_max_ack_backlog = backlog;
        err = 0;

out:
        release_sock(sk);
        return err;
}

static __inline__ kmem_cache_t *inet_sk_slab(int protocol)
{
        kmem_cache_t* rc = tcp_sk_cachep;

        if (protocol == IPPROTO_UDP)
                rc = udp_sk_cachep;
        else if (protocol == IPPROTO_RAW)
                rc = raw4_sk_cachep;
        return rc;
}

static __inline__ int inet_sk_size(int protocol)
{
        int rc = sizeof(struct tcp_sock);

        if (protocol == IPPROTO_UDP)
                rc = sizeof(struct udp_sock);
        else if (protocol == IPPROTO_RAW)
                rc = sizeof(struct raw_sock);
        return rc;
}

/*
 *      Create an inet socket.
 */

static int inet_create(struct socket *sock, int protocol)
{
        struct sock *sk;
        struct list_head *p;
        struct inet_protosw *answer;
        struct inet_opt *inet;
        int err = -ENOBUFS;

        sock->state = SS_UNCONNECTED;
        sk = sk_alloc(PF_INET, GFP_KERNEL, inet_sk_size(protocol),
                      inet_sk_slab(protocol));
        if (!sk)
                goto out;

        /* Look for the requested type/protocol pair. */
        answer = NULL;
        rcu_read_lock();
        list_for_each_rcu(p, &inetsw[sock->type]) {
                answer = list_entry(p, struct inet_protosw, list);

                /* Check the non-wild match. */
                if (protocol == answer->protocol) {
                        if (protocol != IPPROTO_IP)
                                break;
                } else {
                        /* Check for the two wild cases. */
                        if (IPPROTO_IP == protocol) {
                                protocol = answer->protocol;
                                break;
                        }
                        if (IPPROTO_IP == answer->protocol)
                                break;
                }
                answer = NULL;
        }

        err = -ESOCKTNOSUPPORT;
        if (!answer)
                goto out_sk_free;
        err = -EPERM;
        if (answer->capability > 0 && !capable(answer->capability))
                goto out_sk_free;
        err = -EPROTONOSUPPORT;
        if (!protocol)
                goto out_sk_free;
        err = 0;
        sock->ops = answer->ops;
        sk->sk_prot = answer->prot;
        sk->sk_no_check = answer->no_check;
        if (INET_PROTOSW_REUSE & answer->flags)
                sk->sk_reuse = 1;
        rcu_read_unlock();

        inet = inet_sk(sk);

        if (SOCK_RAW == sock->type) {
                inet->num = protocol;
                if (IPPROTO_RAW == protocol)
                        inet->hdrincl = 1;
        }

        if (ipv4_config.no_pmtu_disc)
                inet->pmtudisc = IP_PMTUDISC_DONT;
        else
                inet->pmtudisc = IP_PMTUDISC_WANT;

        inet->id = 0;

        sock_init_data(sock, sk);
        sk_set_owner(sk, THIS_MODULE);

        sk->sk_destruct    = inet_sock_destruct;
        sk->sk_zapped      = 0;
        sk->sk_family      = PF_INET;
        sk->sk_protocol    = protocol;
        sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;

        inet->uc_ttl    = -1;
        inet->mc_loop   = 1;
        inet->mc_ttl    = 1;
        inet->mc_index  = 0;
        inet->mc_list   = NULL;

#ifdef INET_REFCNT_DEBUG
        atomic_inc(&inet_sock_nr);
#endif

        if (inet->num) {
                /* It assumes that any protocol which allows
                 * the user to assign a number at socket
                 * creation time automatically
                 * shares.
                 */
                inet->sport = htons(inet->num);
                /* Add to protocol hash chains. */
                sk->sk_prot->hash(sk);
        }

        if (sk->sk_prot->init) {
                err = sk->sk_prot->init(sk);
                if (err)
                        inet_sock_release(sk);
        }
out:
        return err;
out_sk_free:
        rcu_read_unlock();
        sk_free(sk);
        goto out;
}


/*
 *      The peer socket should always be NULL (or else). When we call this
 *      function we are destroying the object and from then on nobody
 *      should refer to it.
 */
int inet_release(struct socket *sock)
{
        struct sock *sk = sock->sk;

        if (sk) {
                long timeout;

                /* Applications forget to leave groups before exiting */
                ip_mc_drop_socket(sk);

                /* If linger is set, we don't return until the close
                 * is complete.  Otherwise we return immediately. The
                 * actually closing is done the same either way.
                 *
                 * If the close is due to the process exiting, we never
                 * linger..
                 */
                timeout = 0;
                if (sock_flag(sk, SOCK_LINGER) &&
                    !(current->flags & PF_EXITING))
                        timeout = sk->sk_lingertime;
                sock->sk = NULL;
                sk->sk_prot->close(sk, timeout);
        }
        return 0;
}

/* It is off by default, see below. */
int sysctl_ip_nonlocal_bind;

int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
        struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
        struct sock *sk = sock->sk;
        struct inet_opt *inet = inet_sk(sk);
        unsigned short snum;
        int chk_addr_ret;
        int err;

        /* If the socket has its own bind function then use it. (RAW) */
        if (sk->sk_prot->bind) {
                err = sk->sk_prot->bind(sk, uaddr, addr_len);
                goto out;
        }
        err = -EINVAL;
        if (addr_len < sizeof(struct sockaddr_in))
                goto out;

        chk_addr_ret = inet_addr_type(addr->sin_addr.s_addr);

        /* Not specified by any standard per-se, however it breaks too
         * many applications when removed.  It is unfortunate since
         * allowing applications to make a non-local bind solves
         * several problems with systems using dynamic addressing.
         * (ie. your servers still start up even if your ISDN link
         *  is temporarily down)
         */
        err = -EADDRNOTAVAIL;
        if (!sysctl_ip_nonlocal_bind &&
            !inet->freebind &&
            addr->sin_addr.s_addr != INADDR_ANY &&
            chk_addr_ret != RTN_LOCAL &&
            chk_addr_ret != RTN_MULTICAST &&
            chk_addr_ret != RTN_BROADCAST)
                goto out;

        snum = ntohs(addr->sin_port);
        err = -EACCES;
        if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
                goto out;

        /*      We keep a pair of addresses. rcv_saddr is the one
         *      used by hash lookups, and saddr is used for transmit.
         *
         *      In the BSD API these are the same except where it
         *      would be illegal to use them (multicast/broadcast) in
         *      which case the sending device address is used.
         */
        lock_sock(sk);

        /* Check these errors (active socket, double bind). */
        err = -EINVAL;
        if (sk->sk_state != TCP_CLOSE || inet->num)
                goto out_release_sock;

        inet->rcv_saddr = inet->saddr = addr->sin_addr.s_addr;
        if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)
                inet->saddr = 0;  /* Use device */

        /* Make sure we are allowed to bind here. */
        if (sk->sk_prot->get_port(sk, snum)) {
                inet->saddr = inet->rcv_saddr = 0;
                err = -EADDRINUSE;
                goto out_release_sock;
        }

        if (inet->rcv_saddr)
                sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
        if (snum)
                sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
        inet->sport = htons(inet->num);
        inet->daddr = 0;
        inet->dport = 0;
        sk_dst_reset(sk);
        err = 0;
out_release_sock:
        release_sock(sk);
out:
        return err;
}

int inet_dgram_connect(struct socket *sock, struct sockaddr * uaddr,
                       int addr_len, int flags)
{
        struct sock *sk = sock->sk;

        if (uaddr->sa_family == AF_UNSPEC)
                return sk->sk_prot->disconnect(sk, flags);

        if (!inet_sk(sk)->num && inet_autobind(sk))
                return -EAGAIN;
        return sk->sk_prot->connect(sk, (struct sockaddr *)uaddr, addr_len);
}

static long inet_wait_for_connect(struct sock *sk, long timeo)
{
        DEFINE_WAIT(wait);

        prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);

        /* Basic assumption: if someone sets sk->sk_err, he _must_
         * change state of the socket from TCP_SYN_*.
         * Connect() does not allow to get error notifications
         * without closing the socket.
         */
        while ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
                release_sock(sk);
                timeo = schedule_timeout(timeo);
                lock_sock(sk);
                if (signal_pending(current) || !timeo)
                        break;
                prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
        }
        finish_wait(sk->sk_sleep, &wait);
        return timeo;
}

/*
 *      Connect to a remote host. There is regrettably still a little
 *      TCP 'magic' in here.
 */
int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
                        int addr_len, int flags)
{
        struct sock *sk = sock->sk;
        int err;
        long timeo;

        lock_sock(sk);

        if (uaddr->sa_family == AF_UNSPEC) {
                err = sk->sk_prot->disconnect(sk, flags);
                sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
                goto out;
        }

        switch (sock->state) {
        default:
                err = -EINVAL;
                goto out;
        case SS_CONNECTED:
                err = -EISCONN;
                goto out;
        case SS_CONNECTING:
                err = -EALREADY;
                /* Fall out of switch with err, set for this state */
                break;
        case SS_UNCONNECTED:
                err = -EISCONN;
                if (sk->sk_state != TCP_CLOSE)
                        goto out;

                err = sk->sk_prot->connect(sk, uaddr, addr_len);
                if (err < 0)
                        goto out;

                sock->state = SS_CONNECTING;

                /* Just entered SS_CONNECTING state; the only
                 * difference is that return value in non-blocking
                 * case is EINPROGRESS, rather than EALREADY.
                 */
                err = -EINPROGRESS;
                break;
        }

        timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);

        if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
                /* Error code is set above */
                if (!timeo || !inet_wait_for_connect(sk, timeo))
                        goto out;

                err = sock_intr_errno(timeo);
                if (signal_pending(current))
                        goto out;
        }

        /* Connection was closed by RST, timeout, ICMP error
         * or another process disconnected us.
         */
        if (sk->sk_state == TCP_CLOSE)
                goto sock_error;

        /* sk->sk_err may be not zero now, if RECVERR was ordered by user
         * and error was received after socket entered established state.
         * Hence, it is handled normally after connect() return successfully.
         */

        sock->state = SS_CONNECTED;
        err = 0;
out:
        release_sock(sk);
        return err;

sock_error:
        err = sock_error(sk) ? : -ECONNABORTED;
        sock->state = SS_UNCONNECTED;
        if (sk->sk_prot->disconnect(sk, flags))
                sock->state = SS_DISCONNECTING;
        goto out;
}

/*
 *      Accept a pending connection. The TCP layer now gives BSD semantics.
 */

int inet_accept(struct socket *sock, struct socket *newsock, int flags)
{
        struct sock *sk1 = sock->sk;
        int err = -EINVAL;
        struct sock *sk2 = sk1->sk_prot->accept(sk1, flags, &err);

        if (!sk2)
                goto do_err;

        lock_sock(sk2);

        BUG_TRAP((1 << sk2->sk_state) &
                 (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_CLOSE));

        sock_graft(sk2, newsock);

        newsock->state = SS_CONNECTED;
        err = 0;
        release_sock(sk2);
do_err:
        return err;
}


/*
 *      This does both peername and sockname.
 */
int inet_getname(struct socket *sock, struct sockaddr *uaddr,
                        int *uaddr_len, int peer)
{
        struct sock *sk         = sock->sk;
        struct inet_opt *inet   = inet_sk(sk);
        struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;

        sin->sin_family = AF_INET;
        if (peer) {
                if (!inet->dport ||
                    (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
                     peer == 1))
                        return -ENOTCONN;
                sin->sin_port = inet->dport;
                sin->sin_addr.s_addr = inet->daddr;
        } else {
                __u32 addr = inet->rcv_saddr;
                if (!addr)
                        addr = inet->saddr;
                sin->sin_port = inet->sport;
                sin->sin_addr.s_addr = addr;
        }
        memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
        *uaddr_len = sizeof(*sin);
        return 0;
}


int inet_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
                 int size, int flags)
{
        struct sock *sk = sock->sk;
        int addr_len = 0;
        int err;

        err = sk->sk_prot->recvmsg(iocb, sk, msg, size, flags & MSG_DONTWAIT,
                                   flags & ~MSG_DONTWAIT, &addr_len);
        if (err >= 0)
                msg->msg_namelen = addr_len;
        return err;
}


int inet_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
                 int size)
{
        struct sock *sk = sock->sk;

        /* We may need to bind the socket. */
        if (!inet_sk(sk)->num && inet_autobind(sk))
                return -EAGAIN;

        return sk->sk_prot->sendmsg(iocb, sk, msg, size);
}


ssize_t inet_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags)
{
        struct sock *sk = sock->sk;

        /* We may need to bind the socket. */
        if (!inet_sk(sk)->num && inet_autobind(sk))
                return -EAGAIN;

        if (sk->sk_prot->sendpage)
                return sk->sk_prot->sendpage(sk, page, offset, size, flags);
        return sock_no_sendpage(sock, page, offset, size, flags);
}


int inet_shutdown(struct socket *sock, int how)
{
        struct sock *sk = sock->sk;
        int err = 0;

        /* This should really check to make sure
         * the socket is a TCP socket. (WHY AC...)
         */
        how++; /* maps 0->1 has the advantage of making bit 1 rcvs and
                       1->2 bit 2 snds.
                       2->3 */
        if ((how & ~SHUTDOWN_MASK) || !how)     /* MAXINT->0 */
                return -EINVAL;

        lock_sock(sk);
        if (sock->state == SS_CONNECTING) {
                if ((1 << sk->sk_state) &
                    (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE))
                        sock->state = SS_DISCONNECTING;
                else
                        sock->state = SS_CONNECTED;
        }

        switch (sk->sk_state) {
        case TCP_CLOSE:
                err = -ENOTCONN;
                /* Hack to wake up other listeners, who can poll for
                   POLLHUP, even on eg. unconnected UDP sockets -- RR */
        default:
                sk->sk_shutdown |= how;
                if (sk->sk_prot->shutdown)
                        sk->sk_prot->shutdown(sk, how);
                break;

        /* Remaining two branches are temporary solution for missing
         * close() in multithreaded environment. It is _not_ a good idea,
         * but we have no choice until close() is repaired at VFS level.
         */
        case TCP_LISTEN:
                if (!(how & RCV_SHUTDOWN))
                        break;
                /* Fall through */
        case TCP_SYN_SENT:
                err = sk->sk_prot->disconnect(sk, O_NONBLOCK);
                sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
                break;
        }

        /* Wake up anyone sleeping in poll. */
        sk->sk_state_change(sk);
        release_sock(sk);
        return err;
}

/*
 *      ioctl() calls you can issue on an INET socket. Most of these are
 *      device configuration and stuff and very rarely used. Some ioctls
 *      pass on to the socket itself.
 *
 *      NOTE: I like the idea of a module for the config stuff. ie ifconfig
 *      loads the devconfigure module does its configuring and unloads it.
 *      There's a good 20K of config code hanging around the kernel.
 */

int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        struct sock *sk = sock->sk;
        int err = 0;

        switch (cmd) {
                case SIOCGSTAMP:
                        if (!sk->sk_stamp.tv_sec)
                                err = -ENOENT;
                        else if (copy_to_user((void *)arg, &sk->sk_stamp,
                                              sizeof(struct timeval)))
                                err = -EFAULT;
                        break;
                case SIOCADDRT:
                case SIOCDELRT:
                case SIOCRTMSG:
                        err = ip_rt_ioctl(cmd, (void *)arg);
                        break;
                case SIOCDARP:
                case SIOCGARP:
                case SIOCSARP:
                        err = arp_ioctl(cmd, (void *)arg);
                        break;
                case SIOCGIFADDR:
                case SIOCSIFADDR:
                case SIOCGIFBRDADDR:
                case SIOCSIFBRDADDR:
                case SIOCGIFNETMASK:
                case SIOCSIFNETMASK:
                case SIOCGIFDSTADDR:
                case SIOCSIFDSTADDR:
                case SIOCSIFPFLAGS:
                case SIOCGIFPFLAGS:
                case SIOCSIFFLAGS:
                        err = devinet_ioctl(cmd, (void *)arg);
                        break;
                default:
                        if (!sk->sk_prot->ioctl ||
                            (err = sk->sk_prot->ioctl(sk, cmd, arg)) ==
                                                                -ENOIOCTLCMD)
                                err = dev_ioctl(cmd, (void *)arg);
                        break;
        }
        return err;
}

struct proto_ops inet_stream_ops = {
        .family =       PF_INET,
        .owner =        THIS_MODULE,
        .release =      inet_release,
        .bind =         inet_bind,
        .connect =      inet_stream_connect,
        .socketpair =   sock_no_socketpair,
        .accept =       inet_accept,
        .getname =      inet_getname,
        .poll =         tcp_poll,
        .ioctl =        inet_ioctl,
        .listen =       inet_listen,
        .shutdown =     inet_shutdown,
        .setsockopt =   inet_setsockopt,
        .getsockopt =   inet_getsockopt,
        .sendmsg =      inet_sendmsg,
        .recvmsg =      inet_recvmsg,
        .mmap =         sock_no_mmap,
        .sendpage =     tcp_sendpage
};

struct proto_ops inet_dgram_ops = {
        .family =       PF_INET,
        .owner =        THIS_MODULE,
        .release =      inet_release,
        .bind =         inet_bind,
        .connect =      inet_dgram_connect,
        .socketpair =   sock_no_socketpair,
        .accept =       sock_no_accept,
        .getname =      inet_getname,
        .poll =         datagram_poll,
        .ioctl =        inet_ioctl,
        .listen =       sock_no_listen,
        .shutdown =     inet_shutdown,
        .setsockopt =   inet_setsockopt,
        .getsockopt =   inet_getsockopt,
        .sendmsg =      inet_sendmsg,
        .recvmsg =      inet_recvmsg,
        .mmap =         sock_no_mmap,
        .sendpage =     inet_sendpage,
};

struct net_proto_family inet_family_ops = {
        .family = PF_INET,
        .create = inet_create,
        .owner  = THIS_MODULE,
};


extern void tcp_init(void);
extern void tcp_v4_init(struct net_proto_family *);

/* Upon startup we insert all the elements in inetsw_array[] into
 * the linked list inetsw.
 */
static struct inet_protosw inetsw_array[] =
{
        {
                .type =       SOCK_STREAM,
                .protocol =   IPPROTO_TCP,
                .prot =       &tcp_prot,
                .ops =        &inet_stream_ops,
                .capability = -1,
                .no_check =   0,
                .flags =      INET_PROTOSW_PERMANENT,
        },

        {
                .type =       SOCK_DGRAM,
                .protocol =   IPPROTO_UDP,
                .prot =       &udp_prot,
                .ops =        &inet_dgram_ops,
                .capability = -1,
                .no_check =   UDP_CSUM_DEFAULT,
                .flags =      INET_PROTOSW_PERMANENT,
       },
        

       {
               .type =       SOCK_RAW,
               .protocol =   IPPROTO_IP,        /* wild card */
               .prot =       &raw_prot,
               .ops =        &inet_dgram_ops,
               .capability = CAP_NET_RAW,
               .no_check =   UDP_CSUM_DEFAULT,
               .flags =      INET_PROTOSW_REUSE,
       }
};

#define INETSW_ARRAY_LEN (sizeof(inetsw_array) / sizeof(struct inet_protosw))

void inet_register_protosw(struct inet_protosw *p)
{
        struct list_head *lh;
        struct inet_protosw *answer;
        int protocol = p->protocol;
        struct list_head *last_perm;

        spin_lock_bh(&inetsw_lock);

        if (p->type > SOCK_MAX)
                goto out_illegal;

        /* If we are trying to override a permanent protocol, bail. */
        answer = NULL;
        last_perm = &inetsw[p->type];
        list_for_each(lh, &inetsw[p->type]) {
                answer = list_entry(lh, struct inet_protosw, list);

                /* Check only the non-wild match. */
                if (INET_PROTOSW_PERMANENT & answer->flags) {
                        if (protocol == answer->protocol)
                                break;
                        last_perm = lh;
                }

                answer = NULL;
        }
        if (answer)
                goto out_permanent;

        /* Add the new entry after the last permanent entry if any, so that
         * the new entry does not override a permanent entry when matched with
         * a wild-card protocol. But it is allowed to override any existing
         * non-permanent entry.  This means that when we remove this entry, the 
         * system automatically returns to the old behavior.
         */
        list_add_rcu(&p->list, last_perm);
out:
        spin_unlock_bh(&inetsw_lock);

        synchronize_net();

        return;

out_permanent:
        printk(KERN_ERR "Attempt to override permanent protocol %d.\n",
               protocol);
        goto out;

out_illegal:
        printk(KERN_ERR
               "Ignoring attempt to register invalid socket type %d.\n",
               p->type);
        goto out;
}

void inet_unregister_protosw(struct inet_protosw *p)
{
        if (INET_PROTOSW_PERMANENT & p->flags) {
                printk(KERN_ERR
                       "Attempt to unregister permanent protocol %d.\n",
                       p->protocol);
        } else {
                spin_lock_bh(&inetsw_lock);
                list_del_rcu(&p->list);
                spin_unlock_bh(&inetsw_lock);

                synchronize_net();
        }
}

#ifdef CONFIG_IP_MULTICAST
static struct inet_protocol igmp_protocol = {
        .handler =      igmp_rcv,
};
#endif

static struct inet_protocol tcp_protocol = {
        .handler =      tcp_v4_rcv,
        .err_handler =  tcp_v4_err,
        .no_policy =    1,
};

static struct inet_protocol udp_protocol = {
        .handler =      udp_rcv,
        .err_handler =  udp_err,
        .no_policy =    1,
};

static struct inet_protocol icmp_protocol = {
        .handler =      icmp_rcv,
};

static int __init init_ipv4_mibs(void)
{
        net_statistics[0] = alloc_percpu(struct linux_mib);
        net_statistics[1] = alloc_percpu(struct linux_mib);
        ip_statistics[0] = alloc_percpu(struct ip_mib);
        ip_statistics[1] = alloc_percpu(struct ip_mib);
        icmp_statistics[0] = alloc_percpu(struct icmp_mib);
        icmp_statistics[1] = alloc_percpu(struct icmp_mib);
        tcp_statistics[0] = alloc_percpu(struct tcp_mib);
        tcp_statistics[1] = alloc_percpu(struct tcp_mib);
        udp_statistics[0] = alloc_percpu(struct udp_mib);
        udp_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]))
                return -ENOMEM;

        (void) tcp_mib_init();

        return 0;
}

int ipv4_proc_init(void);
extern void ipfrag_init(void);

static int __init inet_init(void)
{
        struct sk_buff *dummy_skb;
        struct inet_protosw *q;
        struct list_head *r;

        if (sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb)) {
                printk(KERN_CRIT "%s: panic\n", __FUNCTION__);
                return -EINVAL;
        }

        tcp_sk_cachep = kmem_cache_create("tcp_sock",
                                          sizeof(struct tcp_sock), 0,
                                          SLAB_HWCACHE_ALIGN, 0, 0);
        udp_sk_cachep = kmem_cache_create("udp_sock",
                                          sizeof(struct udp_sock), 0,
                                          SLAB_HWCACHE_ALIGN, 0, 0);
        raw4_sk_cachep = kmem_cache_create("raw4_sock",
                                           sizeof(struct raw_sock), 0,
                                           SLAB_HWCACHE_ALIGN, 0, 0);
        if (!tcp_sk_cachep || !udp_sk_cachep || !raw4_sk_cachep)
                printk(KERN_CRIT
                       "inet_init: Can't create protocol sock SLAB caches!\n");
        /*
         *      Tell SOCKET that we are alive... 
         */

        (void)sock_register(&inet_family_ops);

        /*
         *      Add all the base protocols.
         */

        if (inet_add_protocol(&icmp_protocol, IPPROTO_ICMP) < 0)
                printk(KERN_CRIT "inet_init: Cannot add ICMP protocol\n");
        if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0)
                printk(KERN_CRIT "inet_init: Cannot add UDP protocol\n");
        if (inet_add_protocol(&tcp_protocol, IPPROTO_TCP) < 0)
                printk(KERN_CRIT "inet_init: Cannot add TCP protocol\n");
#ifdef CONFIG_IP_MULTICAST
        if (inet_add_protocol(&igmp_protocol, IPPROTO_IGMP) < 0)
                printk(KERN_CRIT "inet_init: Cannot add IGMP protocol\n");
#endif

        /* Register the socket-side information for inet_create. */
        for (r = &inetsw[0]; r < &inetsw[SOCK_MAX]; ++r)
                INIT_LIST_HEAD(r);

        for (q = inetsw_array; q < &inetsw_array[INETSW_ARRAY_LEN]; ++q)
                inet_register_protosw(q);

        /*
         *      Set the ARP module up
         */

        arp_init();

        /*
         *      Set the IP module up
         */

        ip_init();

        tcp_v4_init(&inet_family_ops);

        /* Setup TCP slab cache for open requests. */
        tcp_init();


        /*
         *      Set the ICMP layer up
         */

        icmp_init(&inet_family_ops);

        /* I wish inet_add_protocol had no constructor hook...
           I had to move IPIP from net/ipv4/protocol.c :-( --ANK
         */
#ifdef CONFIG_NET_IPIP
        ipip_init();
#endif
#ifdef CONFIG_NET_IPGRE
        ipgre_init();
#endif

        /*
         *      Initialise the multicast router
         */
#if defined(CONFIG_IP_MROUTE)
        ip_mr_init();
#endif
        /*
         *      Initialise per-cpu ipv4 mibs
         */ 

        if(init_ipv4_mibs())
                printk(KERN_CRIT "inet_init: Cannot init ipv4 mibs\n"); ;
        
        ipv4_proc_init();

        ipfrag_init();

        return 0;
}

module_init(inet_init);

/* ------------------------------------------------------------------------ */

#ifdef CONFIG_PROC_FS
extern int  fib_proc_init(void);
extern void fib_proc_exit(void);
extern int  ip_misc_proc_init(void);
extern int  raw_proc_init(void);
extern void raw_proc_exit(void);
extern int  tcp4_proc_init(void);
extern void tcp4_proc_exit(void);
extern int  udp4_proc_init(void);
extern void udp4_proc_exit(void);

int __init ipv4_proc_init(void)
{
        int rc = 0;

        if (raw_proc_init())
                goto out_raw;
        if (tcp4_proc_init())
                goto out_tcp;
        if (udp4_proc_init())
                goto out_udp;
        if (fib_proc_init())
                goto out_fib;
        if (ip_misc_proc_init())
                goto out_misc;
out:
        return rc;
out_misc:
        fib_proc_exit();
out_fib:
        udp4_proc_exit();
out_udp:
        tcp4_proc_exit();
out_tcp:
        raw_proc_exit();
out_raw:
        rc = -ENOMEM;
        goto out;
}

#else /* CONFIG_PROC_FS */
int __init ipv4_proc_init(void)
{
        return 0;
}
#endif /* CONFIG_PROC_FS */

MODULE_ALIAS_NETPROTO(PF_INET);

EXPORT_SYMBOL(inet_accept);
EXPORT_SYMBOL(inet_bind);
EXPORT_SYMBOL(inet_dgram_connect);
EXPORT_SYMBOL(inet_dgram_ops);
EXPORT_SYMBOL(inet_family_ops);
EXPORT_SYMBOL(inet_getname);
EXPORT_SYMBOL(inet_getsockopt);
EXPORT_SYMBOL(inet_ioctl);
EXPORT_SYMBOL(inet_listen);
EXPORT_SYMBOL(inet_recvmsg);
EXPORT_SYMBOL(inet_register_protosw);
EXPORT_SYMBOL(inet_release);
EXPORT_SYMBOL(inet_sendmsg);
EXPORT_SYMBOL(inet_setsockopt);
EXPORT_SYMBOL(inet_shutdown);
EXPORT_SYMBOL(inet_sock_destruct);
EXPORT_SYMBOL(inet_sock_release);
EXPORT_SYMBOL(inet_stream_connect);
EXPORT_SYMBOL(inet_stream_ops);
EXPORT_SYMBOL(inet_unregister_protosw);
EXPORT_SYMBOL(net_statistics);
EXPORT_SYMBOL(tcp_protocol);
EXPORT_SYMBOL(udp_protocol);

#ifdef INET_REFCNT_DEBUG
EXPORT_SYMBOL(inet_sock_nr);
#endif