* better

[mascara-docs.git] / i386 / linux-2.3.21 / net / core / sock.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.
 *
 *              Generic socket support routines. Memory allocators, socket lock/release
 *              handler for protocols to use and generic option handler.
 *
 *
 * Version:     $Id: sock.c,v 1.86 1999/09/01 08:11:49 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>
 *
 * Fixes:
 *              Alan Cox        :       Numerous verify_area() problems
 *              Alan Cox        :       Connecting on a connecting socket
 *                                      now returns an error for tcp.
 *              Alan Cox        :       sock->protocol is set correctly.
 *                                      and is not sometimes left as 0.
 *              Alan Cox        :       connect handles icmp errors on a
 *                                      connect properly. Unfortunately there
 *                                      is a restart syscall nasty there. I
 *                                      can't match BSD without hacking the C
 *                                      library. Ideas urgently sought!
 *              Alan Cox        :       Disallow bind() to addresses that are
 *                                      not ours - especially broadcast ones!!
 *              Alan Cox        :       Socket 1024 _IS_ ok for users. (fencepost)
 *              Alan Cox        :       sock_wfree/sock_rfree don't destroy sockets,
 *                                      instead they leave that for the DESTROY timer.
 *              Alan Cox        :       Clean up error flag in accept
 *              Alan Cox        :       TCP ack handling is buggy, the DESTROY timer
 *                                      was buggy. Put a remove_sock() in the handler
 *                                      for memory when we hit 0. Also altered the timer
 *                                      code. The ACK stuff can wait and needs major 
 *                                      TCP layer surgery.
 *              Alan Cox        :       Fixed TCP ack bug, removed remove sock
 *                                      and fixed timer/inet_bh race.
 *              Alan Cox        :       Added zapped flag for TCP
 *              Alan Cox        :       Move kfree_skb into skbuff.c and tidied up surplus code
 *              Alan Cox        :       for new sk_buff allocations wmalloc/rmalloc now call alloc_skb
 *              Alan Cox        :       kfree_s calls now are kfree_skbmem so we can track skb resources
 *              Alan Cox        :       Supports socket option broadcast now as does udp. Packet and raw need fixing.
 *              Alan Cox        :       Added RCVBUF,SNDBUF size setting. It suddenly occurred to me how easy it was so...
 *              Rick Sladkey    :       Relaxed UDP rules for matching packets.
 *              C.E.Hawkins     :       IFF_PROMISC/SIOCGHWADDR support
 *      Pauline Middelink       :       identd support
 *              Alan Cox        :       Fixed connect() taking signals I think.
 *              Alan Cox        :       SO_LINGER supported
 *              Alan Cox        :       Error reporting fixes
 *              Anonymous       :       inet_create tidied up (sk->reuse setting)
 *              Alan Cox        :       inet sockets don't set sk->type!
 *              Alan Cox        :       Split socket option code
 *              Alan Cox        :       Callbacks
 *              Alan Cox        :       Nagle flag for Charles & Johannes stuff
 *              Alex            :       Removed restriction on inet fioctl
 *              Alan Cox        :       Splitting INET from NET core
 *              Alan Cox        :       Fixed bogus SO_TYPE handling in getsockopt()
 *              Adam Caldwell   :       Missing return in SO_DONTROUTE/SO_DEBUG code
 *              Alan Cox        :       Split IP from generic code
 *              Alan Cox        :       New kfree_skbmem()
 *              Alan Cox        :       Make SO_DEBUG superuser only.
 *              Alan Cox        :       Allow anyone to clear SO_DEBUG
 *                                      (compatibility fix)
 *              Alan Cox        :       Added optimistic memory grabbing for AF_UNIX throughput.
 *              Alan Cox        :       Allocator for a socket is settable.
 *              Alan Cox        :       SO_ERROR includes soft errors.
 *              Alan Cox        :       Allow NULL arguments on some SO_ opts
 *              Alan Cox        :       Generic socket allocation to make hooks
 *                                      easier (suggested by Craig Metz).
 *              Michael Pall    :       SO_ERROR returns positive errno again
 *              Steve Whitehouse:       Added default destructor to free
 *                                      protocol private data.
 *              Steve Whitehouse:       Added various other default routines
 *                                      common to several socket families.
 *              Chris Evans     :       Call suser() check last on F_SETOWN
 *              Jay Schulist    :       Added SO_ATTACH_FILTER and SO_DETACH_FILTER.
 *              Andi Kleen      :       Add sock_kmalloc()/sock_kfree_s()
 *              Andi Kleen      :       Fix write_space callback
 *
 * To Fix:
 *
 *
 *              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/slab.h>
#include <linux/interrupt.h>
#include <linux/poll.h>
#include <linux/init.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/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 <linux/ipsec.h>

#ifdef CONFIG_FILTER
#include <linux/filter.h>
#endif

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

/* Run time adjustable parameters. */
__u32 sysctl_wmem_max = SK_WMEM_MAX;
__u32 sysctl_rmem_max = SK_RMEM_MAX;
__u32 sysctl_wmem_default = SK_WMEM_MAX;
__u32 sysctl_rmem_default = SK_RMEM_MAX;

/* Maximal space eaten by iovec or ancilliary data plus some space */
int sysctl_optmem_max = sizeof(unsigned long)*(2*UIO_MAXIOV + 512);

/*
 *      This is meant for all protocols to use and covers goings on
 *      at the socket level. Everything here is generic.
 */

int sock_setsockopt(struct socket *sock, int level, int optname,
                    char *optval, int optlen)
{
        struct sock *sk=sock->sk;
#ifdef CONFIG_FILTER
        struct sk_filter *filter;
#endif
        int val;
        int valbool;
        int err;
        struct linger ling;
        int ret = 0;
        
        /*
         *      Options without arguments
         */

#ifdef SO_DONTLINGER            /* Compatibility item... */
        switch(optname)
        {
                case SO_DONTLINGER:
                        sk->linger=0;
                        return 0;
        }
#endif  
                
        if(optlen<sizeof(int))
                return(-EINVAL);
        
        err = get_user(val, (int *)optval);
        if (err)
                return err;
        
        valbool = val?1:0;

        lock_sock(sk);

        switch(optname) 
        {
                case SO_DEBUG:  
                        if(val && !capable(CAP_NET_ADMIN))
                        {
                                ret = -EACCES;
                        }
                        else
                                sk->debug=valbool;
                        break;
                case SO_REUSEADDR:
                        sk->reuse = valbool;
                        break;
                case SO_TYPE:
                case SO_ERROR:
                        ret = -ENOPROTOOPT;
                        break;
                case SO_DONTROUTE:
                        sk->localroute=valbool;
                        break;
                case SO_BROADCAST:
                        sk->broadcast=valbool;
                        break;
                case SO_SNDBUF:
                        /* Don't error on this BSD doesn't and if you think
                           about it this is right. Otherwise apps have to
                           play 'guess the biggest size' games. RCVBUF/SNDBUF
                           are treated in BSD as hints */
                           
                        if (val > sysctl_wmem_max)
                                val = sysctl_wmem_max;

                        sk->sndbuf = max(val*2,2048);

                        /*
                         *      Wake up sending tasks if we
                         *      upped the value.
                         */
                        sk->write_space(sk);
                        break;

                case SO_RCVBUF:
                        /* Don't error on this BSD doesn't and if you think
                           about it this is right. Otherwise apps have to
                           play 'guess the biggest size' games. RCVBUF/SNDBUF
                           are treated in BSD as hints */
                          
                        if (val > sysctl_rmem_max)
                                val = sysctl_rmem_max;

                        /* FIXME: is this lower bound the right one? */
                        sk->rcvbuf = max(val*2,256);
                        break;

                case SO_KEEPALIVE:
#ifdef CONFIG_INET
                        if (sk->protocol == IPPROTO_TCP)
                        {
                                tcp_set_keepalive(sk, valbool);
                        }
#endif
                        sk->keepopen = valbool;
                        break;

                case SO_OOBINLINE:
                        sk->urginline = valbool;
                        break;

                case SO_NO_CHECK:
                        sk->no_check = valbool;
                        break;

                case SO_PRIORITY:
                        if ((val >= 0 && val <= 6) || capable(CAP_NET_ADMIN)) 
                                sk->priority = val;
                        else
                                ret = -EPERM;
                        break;

                case SO_LINGER:
                        if(optlen<sizeof(ling)) {
                                ret = -EINVAL;  /* 1003.1g */
                                break;
                        }
                        if (copy_from_user(&ling,optval,sizeof(ling)))
                        {
                                ret = -EFAULT;
                                break;
                        }
                        if(ling.l_onoff==0)
                                sk->linger=0;
                        else
                        {
                                sk->lingertime=ling.l_linger;
                                sk->linger=1;
                        }
                        break;

                case SO_BSDCOMPAT:
                        sk->bsdism = valbool;
                        break;

                case SO_PASSCRED:
                        sock->passcred = valbool;
                        break;
                        
                        
#ifdef CONFIG_NETDEVICES
                case SO_BINDTODEVICE:
                {
                        char devname[IFNAMSIZ]; 

                        /* Sorry... */ 
                        if (!capable(CAP_NET_RAW)) {
                                ret = -EPERM;
                                break;
                        }

                        /* Bind this socket to a particular device like "eth0",
                         * as specified in the passed interface name. If the
                         * name is "" or the option length is zero the socket 
                         * is not bound. 
                         */ 

                        if (!valbool) {
                                sk->bound_dev_if = 0;
                        } else {
                                if (optlen > IFNAMSIZ) 
                                        optlen = IFNAMSIZ; 
                                if (copy_from_user(devname, optval, optlen)) {
                                        ret = -EFAULT;
                                        break;
                                }

                                /* Remove any cached route for this socket. */
                                sk_dst_reset(sk);

                                if (devname[0] == '\0') {
                                        sk->bound_dev_if = 0;
                                } else {
                                        struct net_device *dev = dev_get_by_name(devname);
                                        if (!dev) {
                                                ret = -ENODEV;
                                                break;
                                        }
                                        sk->bound_dev_if = dev->ifindex;
                                        dev_put(dev);
                                }
                        }
                        break;
                }
#endif


#ifdef CONFIG_FILTER
                case SO_ATTACH_FILTER:
                        ret = -EINVAL;
                        if (optlen == sizeof(struct sock_fprog)) {
                                struct sock_fprog fprog;

                                ret = -EFAULT;
                                if (copy_from_user(&fprog, optval, sizeof(fprog)))
                                        break;

                                ret = sk_attach_filter(&fprog, sk);
                        }
                        break;

                case SO_DETACH_FILTER:
                        spin_lock_bh(&sk->lock.slock);
                        filter = sk->filter;
                        if (filter) {
                                sk->filter = NULL;
                                spin_unlock_bh(&sk->lock.slock);
                                sk_filter_release(sk, filter);
                                break;
                        }
                        spin_unlock_bh(&sk->lock.slock);
                        ret = -ENONET;
                        break;
#endif
                /* We implement the SO_SNDLOWAT etc to
                   not be settable (1003.1g 5.3) */
                default:
                        ret = -ENOPROTOOPT;
                        break;
        }
        release_sock(sk);
        return ret;
}


int sock_getsockopt(struct socket *sock, int level, int optname,
                    char *optval, int *optlen)
{
        struct sock *sk = sock->sk;
        
        union
        {
                int val;
                struct linger ling;
                struct timeval tm;
        } v;
        
        int lv=sizeof(int),len;
        
        if(get_user(len,optlen))
                return -EFAULT;

        switch(optname) 
        {
                case SO_DEBUG:          
                        v.val = sk->debug;
                        break;
                
                case SO_DONTROUTE:
                        v.val = sk->localroute;
                        break;
                
                case SO_BROADCAST:
                        v.val= sk->broadcast;
                        break;

                case SO_SNDBUF:
                        v.val=sk->sndbuf;
                        break;
                
                case SO_RCVBUF:
                        v.val =sk->rcvbuf;
                        break;

                case SO_REUSEADDR:
                        v.val = sk->reuse;
                        break;

                case SO_KEEPALIVE:
                        v.val = sk->keepopen;
                        break;

                case SO_TYPE:
                        v.val = sk->type;                               
                        break;

                case SO_ERROR:
                        v.val = -sock_error(sk);
                        if(v.val==0)
                                v.val=xchg(&sk->err_soft,0);
                        break;

                case SO_OOBINLINE:
                        v.val = sk->urginline;
                        break;
        
                case SO_NO_CHECK:
                        v.val = sk->no_check;
                        break;

                case SO_PRIORITY:
                        v.val = sk->priority;
                        break;
                
                case SO_LINGER: 
                        lv=sizeof(v.ling);
                        v.ling.l_onoff=sk->linger;
                        v.ling.l_linger=sk->lingertime;
                        break;
                                        
                case SO_BSDCOMPAT:
                        v.val = sk->bsdism;
                        break;
                        
                case SO_RCVTIMEO:
                case SO_SNDTIMEO:
                        lv=sizeof(struct timeval);
                        v.tm.tv_sec=0;
                        v.tm.tv_usec=0;
                        break;

                case SO_RCVLOWAT:
                case SO_SNDLOWAT:
                        v.val=1;
                        break; 

                case SO_PASSCRED:
                        v.val = sock->passcred;
                        break;

                case SO_PEERCRED:
                        lv=sizeof(sk->peercred);
                        len=min(len, lv);
                        if(copy_to_user((void*)optval, &sk->peercred, len))
                                return -EFAULT;
                        goto lenout;
                        
                default:
                        return(-ENOPROTOOPT);
        }
        len=min(len,lv);
        if(copy_to_user(optval,&v,len))
                return -EFAULT;
lenout:
        if(put_user(len, optlen))
                return -EFAULT;
        return 0;
}

static kmem_cache_t *sk_cachep;

/*
 *      All socket objects are allocated here. This is for future
 *      usage.
 */
 
struct sock *sk_alloc(int family, int priority, int zero_it)
{
        struct sock *sk = kmem_cache_alloc(sk_cachep, priority);

        if(sk && zero_it) {
                memset(sk, 0, sizeof(struct sock));
                sk->family = family;
                sock_lock_init(sk);
        }

        return sk;
}

void sk_free(struct sock *sk)
{
#ifdef CONFIG_FILTER
        struct sk_filter *filter;
#endif

        if (sk->destruct)
                sk->destruct(sk);

#ifdef CONFIG_FILTER
        filter = sk->filter;
        if (filter) {
                sk_filter_release(sk, filter);
                sk->filter = NULL;
        }
#endif

        if (atomic_read(&sk->omem_alloc))
                printk(KERN_DEBUG "sk_free: optmem leakage (%d bytes) detected.\n", atomic_read(&sk->omem_alloc));

        kmem_cache_free(sk_cachep, sk);
}

void __init sk_init(void)
{
        sk_cachep = kmem_cache_create("sock", sizeof(struct sock), 0,
                                      SLAB_HWCACHE_ALIGN, 0, 0);

}

/*
 *      Simple resource managers for sockets.
 */


/* 
 * Write buffer destructor automatically called from kfree_skb. 
 */
void sock_wfree(struct sk_buff *skb)
{
        struct sock *sk = skb->sk;

        /* In case it might be waiting for more memory. */
        atomic_sub(skb->truesize, &sk->wmem_alloc);
        sk->write_space(sk);
        sock_put(sk);
}

/* 
 * Read buffer destructor automatically called from kfree_skb. 
 */
void sock_rfree(struct sk_buff *skb)
{
        struct sock *sk = skb->sk;

        atomic_sub(skb->truesize, &sk->rmem_alloc);
}

void sock_cfree(struct sk_buff *skb)
{
        sock_put(skb->sk);
}

/*
 * Allocate a skb from the socket's send buffer.
 */
struct sk_buff *sock_wmalloc(struct sock *sk, unsigned long size, int force, int priority)
{
        if (force || atomic_read(&sk->wmem_alloc) < sk->sndbuf) {
                struct sk_buff * skb = alloc_skb(size, priority);
                if (skb) {
                        skb_set_owner_w(skb, sk);
                        return skb;
                }
        }
        return NULL;
}

/*
 * Allocate a skb from the socket's receive buffer.
 */ 
struct sk_buff *sock_rmalloc(struct sock *sk, unsigned long size, int force, int priority)
{
        if (force || atomic_read(&sk->rmem_alloc) < sk->rcvbuf) {
                struct sk_buff *skb = alloc_skb(size, priority);
                if (skb) {
                        skb_set_owner_r(skb, sk);
                        return skb;
                }
        }
        return NULL;
}

/* 
 * Allocate a memory block from the socket's option memory buffer.
 */ 
void *sock_kmalloc(struct sock *sk, int size, int priority)
{
        if ((unsigned)size <= sysctl_optmem_max &&
            atomic_read(&sk->omem_alloc)+size < sysctl_optmem_max) {
                void *mem;
                /* First do the add, to avoid the race if kmalloc
                 * might sleep.
                 */
                atomic_add(size, &sk->omem_alloc);
                mem = kmalloc(size, priority);
                if (mem)
                        return mem;
                atomic_sub(size, &sk->omem_alloc);
        }
        return NULL;
}

/*
 * Free an option memory block.
 */
void sock_kfree_s(struct sock *sk, void *mem, int size)
{
        kfree_s(mem, size); 
        atomic_sub(size, &sk->omem_alloc);
}

/* FIXME: this is insane. We are trying suppose to be controlling how
 * how much space we have for data bytes, not packet headers.
 * This really points out that we need a better system for doing the
 * receive buffer. -- erics
 * WARNING: This is currently ONLY used in tcp. If you need it else where
 * this will probably not be what you want. Possibly these two routines
 * should move over to the ipv4 directory.
 */
unsigned long sock_rspace(struct sock *sk)
{
        int amt = 0;

        if (sk != NULL) {
                /* This used to have some bizarre complications that
                 * to attempt to reserve some amount of space. This doesn't
                 * make sense, since the number returned here does not
                 * actually reflect allocated space, but rather the amount
                 * of space we committed to. We gamble that we won't
                 * run out of memory, and returning a smaller number does
                 * not change the gamble. If we lose the gamble tcp still
                 * works, it may just slow down for retransmissions.
                 */
                amt = sk->rcvbuf - atomic_read(&sk->rmem_alloc);
                if (amt < 0) 
                        amt = 0;
        }
        return amt;
}


/* It is almost wait_for_tcp_memory minus release_sock/lock_sock.
   I think, these locks should be removed for datagram sockets.
 */
static void sock_wait_for_wmem(struct sock * sk)
{
        DECLARE_WAITQUEUE(wait, current);

        sk->socket->flags &= ~SO_NOSPACE;
        add_wait_queue(sk->sleep, &wait);
        for (;;) {
                if (signal_pending(current))
                        break;
                set_current_state(TASK_INTERRUPTIBLE);
                if (atomic_read(&sk->wmem_alloc) < sk->sndbuf)
                        break;
                if (sk->shutdown & SEND_SHUTDOWN)
                        break;
                if (sk->err)
                        break;
                schedule();
        }
        __set_current_state(TASK_RUNNING);
        remove_wait_queue(sk->sleep, &wait);
}


/*
 *      Generic send/receive buffer handlers
 */

struct sk_buff *sock_alloc_send_skb(struct sock *sk, unsigned long size, 
                        unsigned long fallback, int noblock, int *errcode)
{
        int err;
        struct sk_buff *skb;

        while (1) {
                unsigned long try_size = size;

                err = sock_error(sk);
                if (err != 0)
                        goto failure;

                /*
                 *      We should send SIGPIPE in these cases according to
                 *      1003.1g draft 6.4. If we (the user) did a shutdown()
                 *      call however we should not. 
                 *
                 *      Note: This routine isnt just used for datagrams and
                 *      anyway some datagram protocols have a notion of
                 *      close down.
                 */

                err = -EPIPE;
                if (sk->shutdown&SEND_SHUTDOWN)
                        goto failure;

                if (fallback) {
                        /* The buffer get won't block, or use the atomic queue.
                         * It does produce annoying no free page messages still.
                         */
                        skb = sock_wmalloc(sk, size, 0, GFP_BUFFER);
                        if (skb)
                                break;
                        try_size = fallback;
                }
                skb = sock_wmalloc(sk, try_size, 0, sk->allocation);
                if (skb)
                        break;

                /*
                 *      This means we have too many buffers for this socket already.
                 */

                sk->socket->flags |= SO_NOSPACE;
                err = -EAGAIN;
                if (noblock)
                        goto failure;
                err = -ERESTARTSYS;
                if (signal_pending(current))
                        goto failure;
                sock_wait_for_wmem(sk);
        }

        return skb;

failure:
        *errcode = err;
        return NULL;
}

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

        add_wait_queue_exclusive(&sk->lock.wq, &wait);
        for(;;) {
                current->state = TASK_EXCLUSIVE | TASK_UNINTERRUPTIBLE;
                spin_unlock_bh(&sk->lock.slock);
                schedule();
                spin_lock_bh(&sk->lock.slock);
                if(!sk->lock.users)
                        break;
        }
        current->state = TASK_RUNNING;
        remove_wait_queue(&sk->lock.wq, &wait);
}

void __release_sock(struct sock *sk)
{
        struct sk_buff *skb = sk->backlog.head;
        do {
                struct sk_buff *next = skb->next;
                skb->next = NULL;
                sk->backlog_rcv(sk, skb);
                skb = next;
        } while(skb != NULL);
        sk->backlog.head = sk->backlog.tail = NULL;
}

/*
 *      Generic socket manager library. Most simpler socket families
 *      use this to manage their socket lists. At some point we should
 *      hash these. By making this generic we get the lot hashed for free.
 *
 *      It is broken by design. All the protocols using it must be fixed. --ANK
 */

rwlock_t net_big_sklist_lock = RW_LOCK_UNLOCKED;
 
void sklist_remove_socket(struct sock **list, struct sock *sk)
{
        struct sock *s;

        write_lock_bh(&net_big_sklist_lock);

        s= *list;
        if(s==sk)
        {
                *list = s->next;
                write_unlock_bh(&net_big_sklist_lock);
                sock_put(sk);
                return;
        }
        while(s && s->next)
        {
                if(s->next==sk)
                {
                        s->next=sk->next;
                        break;
                }
                s=s->next;
        }
        write_unlock_bh(&net_big_sklist_lock);
}

void sklist_insert_socket(struct sock **list, struct sock *sk)
{
        write_lock_bh(&net_big_sklist_lock);
        sk->next= *list;
        *list=sk;
        sock_hold(sk);
        write_unlock_bh(&net_big_sklist_lock);
}

/*
 *      This is only called from user mode. Thus it protects itself against
 *      interrupt users but doesn't worry about being called during work.
 *      Once it is removed from the queue no interrupt or bottom half will
 *      touch it and we are (fairly 8-) ) safe.
 */

void sklist_destroy_socket(struct sock **list, struct sock *sk);

/*
 *      Handler for deferred kills.
 */

static void sklist_destroy_timer(unsigned long data)
{
        struct sock *sk=(struct sock *)data;
        sklist_destroy_socket(NULL,sk);
}

/*
 *      Destroy a socket. We pass NULL for a list if we know the
 *      socket is not on a list.
 */
 
void sklist_destroy_socket(struct sock **list,struct sock *sk)
{
        struct sk_buff *skb;
        if(list)
                sklist_remove_socket(list, sk);

        while((skb=skb_dequeue(&sk->receive_queue))!=NULL)
        {
                kfree_skb(skb);
        }

        if(atomic_read(&sk->wmem_alloc) == 0 &&
           atomic_read(&sk->rmem_alloc) == 0 &&
           sk->dead)
        {
                sock_put(sk);
        }
        else
        {
                /*
                 *      Someone is using our buffers still.. defer
                 */
                init_timer(&sk->timer);
                sk->timer.expires=jiffies+SOCK_DESTROY_TIME;
                sk->timer.function=sklist_destroy_timer;
                sk->timer.data = (unsigned long)sk;
                add_timer(&sk->timer);
        }
}

/*
 * Set of default routines for initialising struct proto_ops when
 * the protocol does not support a particular function. In certain
 * cases where it makes no sense for a protocol to have a "do nothing"
 * function, some default processing is provided.
 */

int sock_no_release(struct socket *sock)
{
        return 0;
}

int sock_no_bind(struct socket *sock, struct sockaddr *saddr, int len)
{
        return -EOPNOTSUPP;
}

int sock_no_connect(struct socket *sock, struct sockaddr *saddr, 
                    int len, int flags)
{
        return -EOPNOTSUPP;
}

int sock_no_socketpair(struct socket *sock1, struct socket *sock2)
{
        return -EOPNOTSUPP;
}

int sock_no_accept(struct socket *sock, struct socket *newsock, int flags)
{
        return -EOPNOTSUPP;
}

int sock_no_getname(struct socket *sock, struct sockaddr *saddr, 
                    int *len, int peer)
{
        return -EOPNOTSUPP;
}

unsigned int sock_no_poll(struct file * file, struct socket *sock, poll_table *pt)
{
        return 0;
}

int sock_no_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        return -EOPNOTSUPP;
}

int sock_no_listen(struct socket *sock, int backlog)
{
        return -EOPNOTSUPP;
}

int sock_no_shutdown(struct socket *sock, int how)
{
        return -EOPNOTSUPP;
}

int sock_no_setsockopt(struct socket *sock, int level, int optname,
                    char *optval, int optlen)
{
        return -EOPNOTSUPP;
}

int sock_no_getsockopt(struct socket *sock, int level, int optname,
                    char *optval, int *optlen)
{
        return -EOPNOTSUPP;
}

/* 
 * Note: if you add something that sleeps here then change sock_fcntl()
 *       to do proper fd locking.
 */
int sock_no_fcntl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        struct sock *sk = sock->sk;

        switch(cmd)
        {
                case F_SETOWN:
                        /*
                         * This is a little restrictive, but it's the only
                         * way to make sure that you can't send a sigurg to
                         * another process.
                         */
                        if (current->pgrp != -arg &&
                                current->pid != arg &&
                                !capable(CAP_KILL)) return(-EPERM);
                        sk->proc = arg;
                        return(0);
                case F_GETOWN:
                        return(sk->proc);
                default:
                        return(-EINVAL);
        }
}

int sock_no_sendmsg(struct socket *sock, struct msghdr *m, int flags,
                    struct scm_cookie *scm)
{
        return -EOPNOTSUPP;
}

int sock_no_recvmsg(struct socket *sock, struct msghdr *m, int flags,
                    struct scm_cookie *scm)
{
        return -EOPNOTSUPP;
}

int sock_no_mmap(struct file *file, struct socket *sock, struct vm_area_struct *vma)
{
        /* Mirror missing mmap method error code */
        return -ENODEV;
}

/*
 *      Default Socket Callbacks
 */

void sock_def_wakeup(struct sock *sk)
{
        read_lock(&sk->callback_lock);
        if(!sk->dead)
                wake_up_interruptible(sk->sleep);
        read_unlock(&sk->callback_lock);
}

void sock_def_error_report(struct sock *sk)
{
        read_lock(&sk->callback_lock);
        if (!sk->dead) {
                wake_up_interruptible(sk->sleep);
                sock_wake_async(sk->socket,0,POLL_ERR); 
        }
        read_unlock(&sk->callback_lock);
}

void sock_def_readable(struct sock *sk, int len)
{
        read_lock(&sk->callback_lock);
        if(!sk->dead) {
                wake_up_interruptible(sk->sleep);
                sock_wake_async(sk->socket,1,POLL_IN);
        }
        read_unlock(&sk->callback_lock);
}

void sock_def_write_space(struct sock *sk)
{
        read_lock(&sk->callback_lock);

        /* Do not wake up a writer until he can make "significant"
         * progress.  --DaveM
         */
        if(!sk->dead &&
           ((atomic_read(&sk->wmem_alloc) << 1) <= sk->sndbuf)) {
                wake_up_interruptible(sk->sleep);

                /* Should agree with poll, otherwise some programs break */
                if (sock_writeable(sk))
                        sock_wake_async(sk->socket, 2, POLL_OUT);
        }
        read_unlock(&sk->callback_lock);
}

void sock_def_destruct(struct sock *sk)
{
        if (sk->protinfo.destruct_hook)
                kfree(sk->protinfo.destruct_hook);
}

void sock_init_data(struct socket *sock, struct sock *sk)
{
        skb_queue_head_init(&sk->receive_queue);
        skb_queue_head_init(&sk->write_queue);
        skb_queue_head_init(&sk->error_queue);

        spin_lock_init(&sk->timer_lock);
        init_timer(&sk->timer);
        
        sk->allocation  =       GFP_KERNEL;
        sk->rcvbuf      =       sysctl_rmem_default;
        sk->sndbuf      =       sysctl_wmem_default;
        sk->state       =       TCP_CLOSE;
        sk->zapped      =       1;
        sk->socket      =       sock;

        if(sock)
        {
                sk->type        =       sock->type;
                sk->sleep       =       &sock->wait;
                sock->sk        =       sk;
        } else
                sk->sleep       =       NULL;

        sk->callback_lock       =       RW_LOCK_UNLOCKED;

        sk->state_change        =       sock_def_wakeup;
        sk->data_ready          =       sock_def_readable;
        sk->write_space         =       sock_def_write_space;
        sk->error_report        =       sock_def_error_report;
        sk->destruct            =       sock_def_destruct;

        sk->peercred.pid        =       0;
        sk->peercred.uid        =       -1;
        sk->peercred.gid        =       -1;

        atomic_set(&sk->refcnt, 1);
}