pre-2.3.4..

[davej-history.git] / net / ipv4 / af_inet.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.
 *
 *              PF_INET protocol family socket handler.
 *
 * Version:     $Id: af_inet.c,v 1.88 1999/05/12 11:24:27 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)
 *
 *              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/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/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/poll.h>

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

#include <linux/inet.h>
#include <linux/netdevice.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/arp.h>
#include <net/rarp.h>
#include <net/route.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 <linux/ip_fw.h>
#ifdef CONFIG_IP_MROUTE
#include <linux/mroute.h>
#endif
#ifdef CONFIG_IP_MASQUERADE
#include <net/ip_masq.h>
#endif
#ifdef CONFIG_BRIDGE
#include <net/br.h>
#endif
#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif
#ifdef CONFIG_NET_RADIO
#include <linux/wireless.h>
#endif  /* CONFIG_NET_RADIO */

#define min(a,b)        ((a)<(b)?(a):(b))

struct linux_mib net_statistics;

extern int raw_get_info(char *, char **, off_t, int, int);
extern int snmp_get_info(char *, char **, off_t, int, int);
extern int netstat_get_info(char *, char **, off_t, int, int);
extern int afinet_get_info(char *, char **, off_t, int, int);
extern int tcp_get_info(char *, char **, off_t, int, int);
extern int udp_get_info(char *, char **, off_t, int, int);
extern void ip_mc_drop_socket(struct sock *sk);

#ifdef CONFIG_DLCI
extern int dlci_ioctl(unsigned int, void*);
#endif

#ifdef CONFIG_DLCI_MODULE
int (*dlci_ioctl_hook)(unsigned int, void *) = NULL;
#endif

int (*rarp_ioctl_hook)(unsigned int,void*) = NULL;

/*
 *      Destroy an AF_INET socket
 */
 
static __inline__ void kill_sk_queues(struct sock *sk)
{
        struct sk_buff *skb;

        /* First the read buffer. */
        while((skb = skb_dequeue(&sk->receive_queue)) != NULL) {
                /* This will take care of closing sockets that were
                 * listening and didn't accept everything.
                 */
                if (skb->sk != NULL && skb->sk != sk)
                        skb->sk->prot->close(skb->sk, 0);
                kfree_skb(skb);
        }

        /* Next, the error queue. */
        while((skb = skb_dequeue(&sk->error_queue)) != NULL)
                kfree_skb(skb);

        /* It is _impossible_ for the backlog to contain anything
         * when we get here.  All user references to this socket
         * have gone away, only the net layer knows can touch it.
         */
}

static __inline__ void kill_sk_now(struct sock *sk)
{
        /* No longer exists. */
        del_from_prot_sklist(sk);

        /* Remove from protocol hash chains. */
        sk->prot->unhash(sk);

        if(sk->opt)
                kfree(sk->opt);
        dst_release(sk->dst_cache);
        sk_free(sk);
}

static __inline__ void kill_sk_later(struct sock *sk)
{
        /* this should never happen. */
        /* actually it can if an ack has just been sent. */
        /* 
         * It's more normal than that...
         * It can happen because a skb is still in the device queues
         * [PR]
         */
                  
        NETDEBUG(printk(KERN_DEBUG "Socket destroy delayed (r=%d w=%d)\n",
                        atomic_read(&sk->rmem_alloc),
                        atomic_read(&sk->wmem_alloc)));

        sk->destroy = 1;
        sk->ack_backlog = 0;
        bh_unlock_sock(sk);
        net_reset_timer(sk, TIME_DESTROY, SOCK_DESTROY_TIME);
}

/* Callers must hold the BH spinlock.
 *
 * At this point, there should be no process reference to this
 * socket, and thus no user references at all.  Therefore we
 * can assume the socket waitqueue is inactive and nobody will
 * try to jump onto it.
 */
void destroy_sock(struct sock *sk)
{
        /* Now we can no longer get new packets or once the
         * timers are killed, send them.
         */
        net_delete_timer(sk);

        if (sk->prot->destroy)
                sk->prot->destroy(sk);

        kill_sk_queues(sk);

        /* Now if it has a half accepted/ closed socket. */
        if (sk->pair) {
                sk->pair->prot->close(sk->pair, 0);
                sk->pair = NULL;
        }

        /* Now if everything is gone we can free the socket
         * structure, otherwise we need to keep it around until
         * everything is gone.
         */
        if (atomic_read(&sk->rmem_alloc) == 0 && atomic_read(&sk->wmem_alloc) == 0)
                kill_sk_now(sk);
        else
                kill_sk_later(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;
        if (sk->prot->setsockopt==NULL)
                return(-EOPNOTSUPP);
        return 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;
        if (sk->prot->getsockopt==NULL)
                return(-EOPNOTSUPP);
        return sk->prot->getsockopt(sk,level,optname,optval,optlen);
}

/*
 *      Automatically bind an unbound socket.
 */

static int inet_autobind(struct sock *sk)
{
        /* We may need to bind the socket. */
        if (sk->num == 0) {
                sk->num = sk->prot->good_socknum();
                if (sk->num == 0) 
                        return(-EAGAIN);
                sk->sport = htons(sk->num);
                sk->prot->hash(sk);
                add_to_prot_sklist(sk);
        }
        return 0;
}

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

        if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
                return(-EINVAL);

        if (inet_autobind(sk) != 0)
                return -EAGAIN;

        /* We might as well re use these. */ 
        if ((unsigned) backlog == 0)    /* BSDism */
                backlog = 1;
        if ((unsigned) backlog > SOMAXCONN)
                backlog = SOMAXCONN;
        sk->max_ack_backlog = backlog;
        if (sk->state != TCP_LISTEN) {
                sk->ack_backlog = 0;
                sk->state = TCP_LISTEN;
                dst_release(xchg(&sk->dst_cache, NULL));
                sk->prot->rehash(sk);
                add_to_prot_sklist(sk);
        }
        sk->socket->flags |= SO_ACCEPTCON;
        return(0);
}

/*
 *      Create an inet socket.
 *
 *      FIXME: Gcc would generate much better code if we set the parameters
 *      up in in-memory structure order. Gcc68K even more so
 */

static int inet_create(struct socket *sock, int protocol)
{
        struct sock *sk;
        struct proto *prot;

        /* Compatibility */
        if (sock->type == SOCK_PACKET) {
                static int warned; 
                if (net_families[PF_PACKET]==NULL)
                {
#if defined(CONFIG_KMOD) && defined(CONFIG_PACKET_MODULE)
                        char module_name[30];
                        sprintf(module_name,"net-pf-%d", PF_PACKET);
                        request_module(module_name);
                        if (net_families[PF_PACKET] == NULL)
#endif
                        return -ESOCKTNOSUPPORT;
                }
                if (!warned++)
                        printk(KERN_INFO "%s uses obsolete (PF_INET,SOCK_PACKET)\n", current->comm);
                return net_families[PF_PACKET]->create(sock, protocol);
        }

        sock->state = SS_UNCONNECTED;
        sk = sk_alloc(PF_INET, GFP_KERNEL, 1);
        if (sk == NULL) 
                goto do_oom;

        switch (sock->type) {
        case SOCK_STREAM:
                if (protocol && protocol != IPPROTO_TCP)
                        goto free_and_noproto;
                protocol = IPPROTO_TCP;
                if (ipv4_config.no_pmtu_disc)
                        sk->ip_pmtudisc = IP_PMTUDISC_DONT;
                else
                        sk->ip_pmtudisc = IP_PMTUDISC_WANT;
                prot = &tcp_prot;
                sock->ops = &inet_stream_ops;
                break;
        case SOCK_SEQPACKET:
                goto free_and_badtype;
        case SOCK_DGRAM:
                if (protocol && protocol != IPPROTO_UDP)
                        goto free_and_noproto;
                protocol = IPPROTO_UDP;
                sk->no_check = UDP_NO_CHECK;
                sk->ip_pmtudisc = IP_PMTUDISC_DONT;
                prot=&udp_prot;
                sock->ops = &inet_dgram_ops;
                break;
        case SOCK_RAW:
                if (!capable(CAP_NET_RAW))
                        goto free_and_badperm;
                if (!protocol)
                        goto free_and_noproto;
                prot = &raw_prot;
                sk->reuse = 1;
                sk->ip_pmtudisc = IP_PMTUDISC_DONT;
                sk->num = protocol;
                sock->ops = &inet_dgram_ops;
                if (protocol == IPPROTO_RAW)
                        sk->ip_hdrincl = 1;
                break;
        default:
                goto free_and_badtype;
        }

        sock_init_data(sock,sk);
        
        sk->destruct = NULL;

        sk->zapped=0;
#ifdef CONFIG_TCP_NAGLE_OFF
        sk->nonagle = 1;
#endif  
        sk->family = PF_INET;
        sk->protocol = protocol;

        sk->prot = prot;
        sk->backlog_rcv = prot->backlog_rcv;

        sk->timer.data = (unsigned long)sk;
        sk->timer.function = &net_timer;

        sk->ip_ttl=ip_statistics.IpDefaultTTL;

        sk->ip_mc_loop=1;
        sk->ip_mc_ttl=1;
        sk->ip_mc_index=0;
        sk->ip_mc_list=NULL;
        
        if (sk->num) {
                /* It assumes that any protocol which allows
                 * the user to assign a number at socket
                 * creation time automatically
                 * shares.
                 */
                sk->sport = htons(sk->num);

                /* Add to protocol hash chains. */
                sk->prot->hash(sk);
                add_to_prot_sklist(sk);
        }

        if (sk->prot->init) {
                int err = sk->prot->init(sk);
                if (err != 0) {
                        destroy_sock(sk);
                        return(err);
                }
        }
        return(0);

free_and_badtype:
        sk_free(sk);
        return -ESOCKTNOSUPPORT;

free_and_badperm:
        sk_free(sk);
        return -EPERM;

free_and_noproto:
        sk_free(sk);
        return -EPROTONOSUPPORT;

do_oom:
        return -ENOBUFS;
}


/*
 *      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 socket *peersock)
{
        struct sock *sk = sock->sk;

        if (sk) {
                long timeout;

                /* Begin closedown and wake up sleepers. */
                if (sock->state != SS_UNCONNECTED)
                        sock->state = SS_DISCONNECTING;
                sk->state_change(sk);

                /* 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 (sk->linger && !(current->flags & PF_EXITING)) {
                        timeout = MAX_SCHEDULE_TIMEOUT;

                        /* XXX This makes no sense whatsoever... -DaveM */
                        if (!sk->lingertime)
                                timeout = HZ*sk->lingertime;
                }
                sock->sk = NULL;
                sk->socket = NULL;
                sk->prot->close(sk, timeout);
        }
        return(0);
}

static 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;
        unsigned short snum;
        int chk_addr_ret;

        /* If the socket has its own bind function then use it. (RAW) */
        if(sk->prot->bind)
                return sk->prot->bind(sk, uaddr, addr_len);
                
        /* Check these errors (active socket, bad address length, double bind). */
        if ((sk->state != TCP_CLOSE)                    ||
            (addr_len < sizeof(struct sockaddr_in))     ||
            (sk->num != 0))
                return -EINVAL;
                
        chk_addr_ret = inet_addr_type(addr->sin_addr.s_addr);
        if (addr->sin_addr.s_addr != 0 && chk_addr_ret != RTN_LOCAL &&
            chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST) {
#ifdef CONFIG_IP_TRANSPARENT_PROXY
                /* Superuser may bind to any address to allow transparent proxying. */
                if(chk_addr_ret != RTN_UNICAST || !capable(CAP_NET_ADMIN))
#endif
                        return -EADDRNOTAVAIL;  /* Source address MUST be ours! */
        }

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

        snum = ntohs(addr->sin_port);
#ifdef CONFIG_IP_MASQUERADE
        /* The kernel masquerader needs some ports. */
        if((snum >= PORT_MASQ_BEGIN) && (snum <= PORT_MASQ_END))
                return -EADDRINUSE;
#endif           
        if (snum == 0) 
                snum = sk->prot->good_socknum();
        if (snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
                return(-EACCES);
        
        /* Make sure we are allowed to bind here. */
        if(sk->prot->verify_bind(sk, snum))
                return -EADDRINUSE;

        sk->num = snum;
        sk->sport = htons(snum);
        sk->daddr = 0;
        sk->dport = 0;
        sk->prot->rehash(sk);
        add_to_prot_sklist(sk);
        dst_release(sk->dst_cache);
        sk->dst_cache=NULL;
        return(0);
}

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

        if (inet_autobind(sk) != 0)
                return(-EAGAIN);
        if (sk->prot->connect == NULL) 
                return(-EOPNOTSUPP);
        err = sk->prot->connect(sk, (struct sockaddr *)uaddr, addr_len);
        if (err < 0) 
                return(err);
        return(0);
}

static void inet_wait_for_connect(struct sock *sk)
{
        DECLARE_WAITQUEUE(wait, current);

        add_wait_queue(sk->sleep, &wait);
        current->state = TASK_INTERRUPTIBLE;
        while (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV) {
                if (signal_pending(current))
                        break;
                if (sk->err)
                        break;
                schedule();
                current->state = TASK_INTERRUPTIBLE;
        }
        current->state = TASK_RUNNING;
        remove_wait_queue(sk->sleep, &wait);
}

/*
 *      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;

        if(sock->state != SS_UNCONNECTED && sock->state != SS_CONNECTING) {
                if(sock->state == SS_CONNECTED)
                        return -EISCONN;
                return -EINVAL;
        }

        if(sock->state == SS_CONNECTING) {
                /* Note: tcp_connected contains SYN_RECV, which may cause
                   bogus results here. -AK */ 
                if(tcp_connected(sk->state)) {
                        sock->state = SS_CONNECTED;
                        return 0;
                }
                if (sk->zapped || sk->err)
                        goto sock_error;
                if (flags & O_NONBLOCK)
                        return -EALREADY;
        } else {
                /* We may need to bind the socket. */
                if (inet_autobind(sk) != 0)
                        return(-EAGAIN);
                if (sk->prot->connect == NULL) 
                        return(-EOPNOTSUPP);
                err = sk->prot->connect(sk, uaddr, addr_len);
                /* Note: there is a theoretical race here when an wake up
                   occurred before inet_wait_for_connect is entered. In 2.3
                   the wait queue setup should be moved before the low level
                   connect call. -AK*/
                if (err < 0)
                        return(err);
                sock->state = SS_CONNECTING;
        }
        
        if (sk->state > TCP_FIN_WAIT2 && sock->state == SS_CONNECTING)
                goto sock_error;

        if (sk->state != TCP_ESTABLISHED && (flags & O_NONBLOCK)) 
                return (-EINPROGRESS);

        if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV) {
                inet_wait_for_connect(sk);
                if (signal_pending(current))
                        return -ERESTARTSYS;
        }

        sock->state = SS_CONNECTED;
        if ((sk->state != TCP_ESTABLISHED) && sk->err)
                goto sock_error; 
        return(0);

sock_error:     
        /* This is ugly but needed to fix a race in the ICMP error handler */
        if (sk->zapped && sk->state != TCP_CLOSE) { 
                lock_sock(sk);  
                tcp_set_state(sk, TCP_CLOSE);
                release_sock(sk); 
                sk->zapped = 0;
        }
        sock->state = SS_UNCONNECTED;
        return sock_error(sk);
}

/*
 *      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, *sk2;
        struct sock *newsk = newsock->sk;
        int err = -EINVAL;

        if (sock->state != SS_UNCONNECTED || !(sock->flags & SO_ACCEPTCON))
                goto do_err;

        err = -EOPNOTSUPP;
        if (sk1->prot->accept == NULL)
                goto do_err;

        /* Restore the state if we have been interrupted, and then returned. */
        if (sk1->pair != NULL) {
                sk2 = sk1->pair;
                sk1->pair = NULL;
        } else {
                if((sk2 = sk1->prot->accept(sk1,flags)) == NULL)
                        goto do_sk1_err;
        }

        /*
         *      We've been passed an extra socket.
         *      We need to free it up because the tcp module creates
         *      its own when it accepts one.
         */
        sk2->sleep = newsk->sleep;

        newsock->sk = sk2;
        sk2->socket = newsock;
        newsk->socket = NULL;

        if (flags & O_NONBLOCK)
                goto do_half_success;

        if(sk2->state == TCP_ESTABLISHED)
                goto do_full_success;
        if(sk2->err > 0)
                goto do_connect_err;
        err = -ECONNABORTED;
        if (sk2->state == TCP_CLOSE)
                goto do_bad_connection;
do_full_success:
        destroy_sock(newsk);
        newsock->state = SS_CONNECTED;
        return 0;

do_half_success:
        destroy_sock(newsk);
        return(0);

do_connect_err:
        err = sock_error(sk2);
do_bad_connection:
        sk2->sleep = NULL;
        sk2->socket = NULL;
        destroy_sock(sk2);
        newsock->sk = newsk;
        newsk->socket = newsock;
        return err;

do_sk1_err:
        err = sock_error(sk1);
do_err:
        return err;
}


/*
 *      This does both peername and sockname.
 */
 
static int inet_getname(struct socket *sock, struct sockaddr *uaddr,
                 int *uaddr_len, int peer)
{
        struct sock *sk         = sock->sk;
        struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
  
        sin->sin_family = AF_INET;
        if (peer) {
                if (!tcp_connected(sk->state)) 
                        return(-ENOTCONN);
                sin->sin_port = sk->dport;
                sin->sin_addr.s_addr = sk->daddr;
        } else {
                __u32 addr = sk->rcv_saddr;
                if (!addr)
                        addr = sk->saddr;
                sin->sin_port = sk->sport;
                sin->sin_addr.s_addr = addr;
        }
        *uaddr_len = sizeof(*sin);
        return(0);
}



int inet_recvmsg(struct socket *sock, struct msghdr *msg, int size,
                 int flags, struct scm_cookie *scm)
{
        struct sock *sk = sock->sk;
        int addr_len = 0;
        int err;
        
        if (sock->flags & SO_ACCEPTCON)
                return(-EINVAL);
        if (sk->prot->recvmsg == NULL) 
                return(-EOPNOTSUPP);
        /* We may need to bind the socket. */
        if (inet_autobind(sk) != 0)
                return(-EAGAIN);
        err = sk->prot->recvmsg(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 socket *sock, struct msghdr *msg, int size,
                 struct scm_cookie *scm)
{
        struct sock *sk = sock->sk;

        if (sk->shutdown & SEND_SHUTDOWN) {
                if (!(msg->msg_flags&MSG_NOSIGNAL))
                        send_sig(SIGPIPE, current, 1);
                return(-EPIPE);
        }
        if (sk->prot->sendmsg == NULL) 
                return(-EOPNOTSUPP);
        if(sk->err)
                return sock_error(sk);

        /* We may need to bind the socket. */
        if(inet_autobind(sk) != 0)
                return -EAGAIN;

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


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

        /* 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==0)   /* MAXINT->0 */
                return(-EINVAL);
        if (sock->state == SS_CONNECTING && sk->state == TCP_ESTABLISHED)
                sock->state = SS_CONNECTED;
        if (!sk || !tcp_connected(sk->state)) 
                return(-ENOTCONN);
        sk->shutdown |= how;
        if (sk->prot->shutdown)
                sk->prot->shutdown(sk, how);
        /* Wake up anyone sleeping in poll. */
        sk->state_change(sk);
        return(0);
}


unsigned int inet_poll(struct file * file, struct socket *sock, poll_table *wait)
{
        struct sock *sk = sock->sk;

        if (sk->prot->poll == NULL)
                return(0);
        return sk->prot->poll(file, sock, wait);
}

/*
 *      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.
 */

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

        switch(cmd) 
        {
                case FIOSETOWN:
                case SIOCSPGRP:
                        err = get_user(pid, (int *) arg);
                        if (err)
                                return err; 
                        if (current->pid != pid && current->pgrp != -pid && 
                            !capable(CAP_NET_ADMIN))
                                return -EPERM;
                        sk->proc = pid;
                        return(0);
                case FIOGETOWN:
                case SIOCGPGRP:
                        return put_user(sk->proc, (int *)arg);
                case SIOCGSTAMP:
                        if(sk->stamp.tv_sec==0)
                                return -ENOENT;
                        err = copy_to_user((void *)arg,&sk->stamp,sizeof(struct timeval));
                        if (err)
                                err = -EFAULT;
                        return err;
                case SIOCADDRT:
                case SIOCDELRT:
                case SIOCRTMSG:
                        return(ip_rt_ioctl(cmd,(void *) arg));
                case SIOCDARP:
                case SIOCGARP:
                case SIOCSARP:
                        return(arp_ioctl(cmd,(void *) arg));
                case SIOCDRARP:
                case SIOCGRARP:
                case SIOCSRARP:
#ifdef CONFIG_KMOD
                        if (rarp_ioctl_hook == NULL)
                                request_module("rarp");
#endif
                        if (rarp_ioctl_hook != NULL)
                                return(rarp_ioctl_hook(cmd,(void *) arg));
                case SIOCGIFADDR:
                case SIOCSIFADDR:
                case SIOCGIFBRDADDR:
                case SIOCSIFBRDADDR:
                case SIOCGIFNETMASK:
                case SIOCSIFNETMASK:
                case SIOCGIFDSTADDR:
                case SIOCSIFDSTADDR:
                case SIOCSIFPFLAGS:     
                case SIOCGIFPFLAGS:     
                case SIOCSIFFLAGS:
                        return(devinet_ioctl(cmd,(void *) arg));
                case SIOCGIFBR:
                case SIOCSIFBR:
#ifdef CONFIG_BRIDGE            
                        return(br_ioctl(cmd,(void *) arg));
#else
                        return -ENOPKG;
#endif                                          
                        
                case SIOCADDDLCI:
                case SIOCDELDLCI:
#ifdef CONFIG_DLCI
                        return(dlci_ioctl(cmd, (void *) arg));
#endif

#ifdef CONFIG_DLCI_MODULE

#ifdef CONFIG_KMOD
                        if (dlci_ioctl_hook == NULL)
                                request_module("dlci");
#endif

                        if (dlci_ioctl_hook)
                                return((*dlci_ioctl_hook)(cmd, (void *) arg));
#endif
                        return -ENOPKG;

                default:
                        if ((cmd >= SIOCDEVPRIVATE) &&
                            (cmd <= (SIOCDEVPRIVATE + 15)))
                                return(dev_ioctl(cmd,(void *) arg));

#ifdef CONFIG_NET_RADIO
                        if((cmd >= SIOCIWFIRST) && (cmd <= SIOCIWLAST))
                                return(dev_ioctl(cmd,(void *) arg));
#endif

                        if (sk->prot->ioctl==NULL || (err=sk->prot->ioctl(sk, cmd, arg))==-ENOIOCTLCMD)
                                return(dev_ioctl(cmd,(void *) arg));            
                        return err;
        }
        /*NOTREACHED*/
        return(0);
}

struct proto_ops inet_stream_ops = {
        PF_INET,

        sock_no_dup,
        inet_release,
        inet_bind,
        inet_stream_connect,
        sock_no_socketpair,
        inet_accept,
        inet_getname, 
        inet_poll,
        inet_ioctl,
        inet_listen,
        inet_shutdown,
        inet_setsockopt,
        inet_getsockopt,
        sock_no_fcntl,
        inet_sendmsg,
        inet_recvmsg
};

struct proto_ops inet_dgram_ops = {
        PF_INET,

        sock_no_dup,
        inet_release,
        inet_bind,
        inet_dgram_connect,
        sock_no_socketpair,
        sock_no_accept,
        inet_getname, 
        datagram_poll,
        inet_ioctl,
        sock_no_listen,
        inet_shutdown,
        inet_setsockopt,
        inet_getsockopt,
        sock_no_fcntl,
        inet_sendmsg,
        inet_recvmsg
};

struct net_proto_family inet_family_ops = {
        PF_INET,
        inet_create
};


#ifdef CONFIG_PROC_FS
#ifdef CONFIG_INET_RARP
static struct proc_dir_entry proc_net_rarp = {
        PROC_NET_RARP, 4, "rarp",
        S_IFREG | S_IRUGO, 1, 0, 0,
        0, &proc_net_inode_operations,
        rarp_get_info
};
#endif          /* RARP */
static struct proc_dir_entry proc_net_raw = {
        PROC_NET_RAW, 3, "raw",
        S_IFREG | S_IRUGO, 1, 0, 0,
        0, &proc_net_inode_operations,
        raw_get_info
};
static struct proc_dir_entry proc_net_netstat = {
        PROC_NET_NETSTAT, 7, "netstat",
        S_IFREG | S_IRUGO, 1, 0, 0,
        0, &proc_net_inode_operations,
        netstat_get_info
};
static struct proc_dir_entry proc_net_snmp = {
        PROC_NET_SNMP, 4, "snmp",
        S_IFREG | S_IRUGO, 1, 0, 0,
        0, &proc_net_inode_operations,
        snmp_get_info
};
static struct proc_dir_entry proc_net_sockstat = {
        PROC_NET_SOCKSTAT, 8, "sockstat",
        S_IFREG | S_IRUGO, 1, 0, 0,
        0, &proc_net_inode_operations,
        afinet_get_info
};
static struct proc_dir_entry proc_net_tcp = {
        PROC_NET_TCP, 3, "tcp",
        S_IFREG | S_IRUGO, 1, 0, 0,
        0, &proc_net_inode_operations,
        tcp_get_info
};
static struct proc_dir_entry proc_net_udp = {
        PROC_NET_UDP, 3, "udp",
        S_IFREG | S_IRUGO, 1, 0, 0,
        0, &proc_net_inode_operations,
        udp_get_info
};
#endif          /* CONFIG_PROC_FS */

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


/*
 *      Called by socket.c on kernel startup.  
 */
 
__initfunc(void inet_proto_init(struct net_proto *pro))
{
        struct sk_buff *dummy_skb;
        struct inet_protocol *p;

        printk(KERN_INFO "NET4: Linux TCP/IP 1.0 for NET4.0\n");

        if (sizeof(struct inet_skb_parm) > sizeof(dummy_skb->cb))
        {
                printk(KERN_CRIT "inet_proto_init: panic\n");
                return;
        }

        /*
         *      Tell SOCKET that we are alive... 
         */
   
        (void) sock_register(&inet_family_ops);

        /*
         *      Add all the protocols. 
         */

        printk(KERN_INFO "IP Protocols: ");
        for(p = inet_protocol_base; p != NULL;) 
        {
                struct inet_protocol *tmp = (struct inet_protocol *) p->next;
                inet_add_protocol(p);
                printk("%s%s",p->name,tmp?", ":"\n");
                p = tmp;
        }

        /*
         *      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

        /*
         *      Set the firewalling up
         */
#if defined(CONFIG_IP_FIREWALL)
        ip_fw_init();
#endif

#ifdef CONFIG_IP_MASQUERADE
        ip_masq_init();
#endif
        
        /*
         *      Initialise the multicast router
         */
#if defined(CONFIG_IP_MROUTE)
        ip_mr_init();
#endif

#ifdef CONFIG_INET_RARP
        rarp_ioctl_hook = rarp_ioctl;
#endif
        /*
         *      Create all the /proc entries.
         */

#ifdef CONFIG_PROC_FS
#ifdef CONFIG_INET_RARP
        proc_net_register(&proc_net_rarp);
#endif          /* RARP */
        proc_net_register(&proc_net_raw);
        proc_net_register(&proc_net_snmp);
        proc_net_register(&proc_net_netstat);
        proc_net_register(&proc_net_sockstat);
        proc_net_register(&proc_net_tcp);
        proc_net_register(&proc_net_udp);
#endif          /* CONFIG_PROC_FS */
}