/*
 * NET          An implementation of the SOCKET network access protocol.
 *
 * Version:     @(#)socket.c    1.1.93  18/02/95
 *
 * Authors:     Orest Zborowski, <obz@Kodak.COM>
 *              Ross Biro, <bir7@leland.Stanford.Edu>
 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *
 * Fixes:
 *              Anonymous       :       NOTSOCK/BADF cleanup. Error fix in
 *                                      shutdown()
 *              Alan Cox        :       verify_area() fixes
 *              Alan Cox        :       Removed DDI
 *              Jonathan Kamens :       SOCK_DGRAM reconnect bug
 *              Alan Cox        :       Moved a load of checks to the very
 *                                      top level.
 *              Alan Cox        :       Move address structures to/from user
 *                                      mode above the protocol layers.
 *              Rob Janssen     :       Allow 0 length sends.
 *              Alan Cox        :       Asynchronous I/O support (cribbed from the
 *                                      tty drivers).
 *              Niibe Yutaka    :       Asynchronous I/O for writes (4.4BSD style)
 *              Jeff Uphoff     :       Made max number of sockets command-line
 *                                      configurable.
 *              Matti Aarnio    :       Made the number of sockets dynamic,
 *                                      to be allocated when needed, and mr.
 *                                      Uphoff's max is used as max to be
 *                                      allowed to allocate.
 *              Linus           :       Argh. removed all the socket allocation
 *                                      altogether: it's in the inode now.
 *              Alan Cox        :       Made sock_alloc()/sock_release() public
 *                                      for NetROM and future kernel nfsd type
 *                                      stuff.
 *              Alan Cox        :       sendmsg/recvmsg basics.
 *              Tom Dyas        :       Export net symbols.
 *              Marcin Dalecki  :       Fixed problems with CONFIG_NET="n".
 *              Alan Cox        :       Added thread locking to sys_* calls
 *                                      for sockets. May have errors at the
 *                                      moment.
 *              Kevin Buhr      :       Fixed the dumb errors in the above.
 *              Andi Kleen      :       Some small cleanups, optimizations,
 *                                      and fixed a copy_from_user() bug.
 *              Tigran Aivazian :       sys_send(args) calls sys_sendto(args, NULL, 0)
 *
 *
 *              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.
 *
 *
 *      This module is effectively the top level interface to the BSD socket
 *      paradigm. 
 *
 */

#include <linux/config.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/socket.h>
#include <linux/file.h>
#include <linux/net.h>
#include <linux/interrupt.h>
#include <linux/netdevice.h>
#include <linux/proc_fs.h>
#include <linux/firewall.h>
#include <linux/wanrouter.h>
#include <linux/init.h>
#include <linux/poll.h>

#if defined(CONFIG_KMOD) && defined(CONFIG_NET)
#include <linux/kmod.h>
#endif

#include <asm/uaccess.h>

#include <linux/inet.h>
#include <net/ip.h>
#include <net/sock.h>
#include <net/rarp.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/scm.h>

static int sock_no_open(struct inode *irrelevant, struct file *dontcare);
static long long sock_lseek(struct file *file, long long offset, int whence);
static ssize_t sock_read(struct file *file, char *buf,
                         size_t size, loff_t *ppos);
static ssize_t sock_write(struct file *file, const char *buf,
                          size_t size, loff_t *ppos);

static int sock_close(struct inode *inode, struct file *file);
static unsigned int sock_poll(struct file *file,
                              struct poll_table_struct *wait);
static int sock_ioctl(struct inode *inode, struct file *file,
                      unsigned int cmd, unsigned long arg);
static int sock_fasync(int fd, struct file *filp, int on);


/*
 *      Socket files have a set of 'special' operations as well as the generic file ones. These don't appear
 *      in the operation structures but are done directly via the socketcall() multiplexor.
 */

static struct file_operations socket_file_ops = {
        sock_lseek,
        sock_read,
        sock_write,
        NULL,                   /* readdir */
        sock_poll,
        sock_ioctl,
        NULL,                   /* mmap */
        sock_no_open,           /* special open code to disallow open via /proc */
        NULL,                   /* flush */
        sock_close,
        NULL,                   /* no fsync */
        sock_fasync
};

/*
 *      The protocol list. Each protocol is registered in here.
 */

struct net_proto_family *net_families[NPROTO];

/*
 *      Statistics counters of the socket lists
 */

static int sockets_in_use  = 0;

/*
 *      Support routines. Move socket addresses back and forth across the kernel/user
 *      divide and look after the messy bits.
 */

#define MAX_SOCK_ADDR   128             /* 108 for Unix domain - 
                                           16 for IP, 16 for IPX,
                                           24 for IPv6,
                                           about 80 for AX.25 
                                           must be at least one bigger than
                                           the AF_UNIX size (see net/unix/af_unix.c
                                           :unix_mkname()).  
                                         */

int move_addr_to_kernel(void *uaddr, int ulen, void *kaddr)
{
        if(ulen<0||ulen>MAX_SOCK_ADDR)
                return -EINVAL;
        if(ulen==0)
                return 0;
        if(copy_from_user(kaddr,uaddr,ulen))
                return -EFAULT;
        return 0;
}

int move_addr_to_user(void *kaddr, int klen, void *uaddr, int *ulen)
{
        int err;
        int len;

        if((err=get_user(len, ulen)))
                return err;
        if(len>klen)
                len=klen;
        if(len<0 || len> MAX_SOCK_ADDR)
                return -EINVAL;
        if(len)
        {
                if(copy_to_user(uaddr,kaddr,len))
                        return -EFAULT;
        }
        /*
         *      "fromlen shall refer to the value before truncation.."
         *                      1003.1g
         */
        return __put_user(klen, ulen);
}

/*
 *      Obtains the first available file descriptor and sets it up for use. 
 */

static int get_fd(struct inode *inode)
{
        int fd;

        /*
         *      Find a file descriptor suitable for return to the user. 
         */

        fd = get_unused_fd();
        if (fd >= 0) {
                struct file *file = get_empty_filp();

                if (!file) {
                        put_unused_fd(fd);
                        return -ENFILE;
                }

                file->f_dentry = d_alloc_root(inode, NULL);
                if (!file->f_dentry) {
                        put_filp(file);
                        put_unused_fd(fd);
                        return -ENOMEM;
                }

                /*
                 * The socket maintains a reference to the inode, so we
                 * have to increment the count.
                 */
                inode->i_count++;

                fd_install(fd, file);
                file->f_op = &socket_file_ops;
                file->f_mode = 3;
                file->f_flags = O_RDWR;
                file->f_pos = 0;
        }
        return fd;
}

extern __inline__ struct socket *socki_lookup(struct inode *inode)
{
        return &inode->u.socket_i;
}

/*
 *      Go from a file number to its socket slot.
 */

extern struct socket *sockfd_lookup(int fd, int *err)
{
        struct file *file;
        struct inode *inode;
        struct socket *sock;

        if (!(file = fget(fd)))
        {
                *err = -EBADF;
                return NULL;
        }

        inode = file->f_dentry->d_inode;
        if (!inode || !inode->i_sock || !(sock = socki_lookup(inode)))
        {
                *err = -ENOTSOCK;
                fput(file);
                return NULL;
        }

        if (sock->file != file) {
                printk(KERN_ERR "socki_lookup: socket file changed!\n");
                sock->file = file;
        }
        return sock;
}

extern __inline__ void sockfd_put(struct socket *sock)
{
        fput(sock->file);
}

/*
 *      Allocate a socket.
 */

struct socket *sock_alloc(void)
{
        struct inode * inode;
        struct socket * sock;

        inode = get_empty_inode();
        if (!inode)
                return NULL;

        sock = socki_lookup(inode);

        inode->i_mode = S_IFSOCK|S_IRWXUGO;
        inode->i_sock = 1;
        inode->i_uid = current->uid;
        inode->i_gid = current->gid;

        sock->inode = inode;
        init_waitqueue(&sock->wait);
        sock->fasync_list = NULL;
        sock->state = SS_UNCONNECTED;
        sock->flags = 0;
        sock->ops = NULL;
        sock->sk = NULL;
        sock->file = NULL;

        sockets_in_use++;
        return sock;
}

/*
 *      In theory you can't get an open on this inode, but /proc provides
 *      a back door. Remember to keep it shut otherwise you'll let the
 *      creepy crawlies in.
 */
  
static int sock_no_open(struct inode *irrelevant, struct file *dontcare)
{
        return -ENXIO;
}

void sock_release(struct socket *sock)
{
        if (sock->state != SS_UNCONNECTED)
                sock->state = SS_DISCONNECTING;

        if (sock->ops) 
                sock->ops->release(sock, NULL);

        if (sock->fasync_list)
                printk(KERN_ERR "sock_release: fasync list not empty!\n");

        --sockets_in_use;       /* Bookkeeping.. */
        sock->file=NULL;
        iput(sock->inode);
}

int sock_sendmsg(struct socket *sock, struct msghdr *msg, int size)
{
        int err;
        struct scm_cookie scm;

        err = scm_send(sock, msg, &scm);
        if (err >= 0) {
                err = sock->ops->sendmsg(sock, msg, size, &scm);
                scm_destroy(&scm);
        }
        return err;
}

int sock_recvmsg(struct socket *sock, struct msghdr *msg, int size, int flags)
{
        struct scm_cookie scm;

        memset(&scm, 0, sizeof(scm));

        size = sock->ops->recvmsg(sock, msg, size, flags, &scm);
        if (size >= 0)
                scm_recv(sock, msg, &scm, flags);

        return size;
}


/*
 *      Sockets are not seekable.
 */

static long long sock_lseek(struct file *file,long long offset, int whence)
{
        return -ESPIPE;
}

/*
 *      Read data from a socket. ubuf is a user mode pointer. We make sure the user
 *      area ubuf...ubuf+size-1 is writable before asking the protocol.
 */

static ssize_t sock_read(struct file *file, char *ubuf,
                         size_t size, loff_t *ppos)
{
        struct socket *sock;
        struct iovec iov;
        struct msghdr msg;

        if (ppos != &file->f_pos)
                return -ESPIPE;
        if (size==0)            /* Match SYS5 behaviour */
                return 0;

        sock = socki_lookup(file->f_dentry->d_inode); 

        msg.msg_name=NULL;
        msg.msg_namelen=0;
        msg.msg_iov=&iov;
        msg.msg_iovlen=1;
        msg.msg_control=NULL;
        msg.msg_controllen=0;
        iov.iov_base=ubuf;
        iov.iov_len=size;

        return sock_recvmsg(sock, &msg, size,
                            !(file->f_flags & O_NONBLOCK) ? 0 : MSG_DONTWAIT);
}


/*
 *      Write data to a socket. We verify that the user area ubuf..ubuf+size-1
 *      is readable by the user process.
 */

static ssize_t sock_write(struct file *file, const char *ubuf,
                          size_t size, loff_t *ppos)
{
        struct socket *sock;
        struct msghdr msg;
        struct iovec iov;
        
        if (ppos != &file->f_pos)
                return -ESPIPE;
        if(size==0)             /* Match SYS5 behaviour */
                return 0;

        sock = socki_lookup(file->f_dentry->d_inode); 

        msg.msg_name=NULL;
        msg.msg_namelen=0;
        msg.msg_iov=&iov;
        msg.msg_iovlen=1;
        msg.msg_control=NULL;
        msg.msg_controllen=0;
        msg.msg_flags=!(file->f_flags & O_NONBLOCK) ? 0 : MSG_DONTWAIT;
        iov.iov_base=(void *)ubuf;
        iov.iov_len=size;
        
        return sock_sendmsg(sock, &msg, size);
}

int sock_readv_writev(int type, struct inode * inode, struct file * file,
                      const struct iovec * iov, long count, long size)
{
        struct msghdr msg;
        struct socket *sock;

        sock = socki_lookup(inode);

        msg.msg_name = NULL;
        msg.msg_namelen = 0;
        msg.msg_control = NULL;
        msg.msg_controllen = 0;
        msg.msg_iov = (struct iovec *) iov;
        msg.msg_iovlen = count;
        msg.msg_flags = (file->f_flags & O_NONBLOCK) ? MSG_DONTWAIT : 0;

        /* read() does a VERIFY_WRITE */
        if (type == VERIFY_WRITE)
                return sock_recvmsg(sock, &msg, size, msg.msg_flags);
        return sock_sendmsg(sock, &msg, size);
}


/*
 *      With an ioctl arg may well be a user mode pointer, but we don't know what to do
 *      with it - that's up to the protocol still.
 */

int sock_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
           unsigned long arg)
{
        struct socket *sock = socki_lookup(inode);
        return sock->ops->ioctl(sock, cmd, arg);
}


static unsigned int sock_poll(struct file *file, poll_table * wait)
{
        struct socket *sock;

        sock = socki_lookup(file->f_dentry->d_inode);

        /*
         *      We can't return errors to poll, so it's either yes or no. 
         */

        return sock->ops->poll(file, sock, wait);
}


int sock_close(struct inode *inode, struct file *filp)
{
        /*
         *      It was possible the inode is NULL we were 
         *      closing an unfinished socket. 
         */

        if (!inode)
        {
                printk(KERN_DEBUG "sock_close: NULL inode\n");
                return 0;
        }
        sock_fasync(-1, filp, 0);
        sock_release(socki_lookup(inode));
        return 0;
}

/*
 *      Update the socket async list
 */

static int sock_fasync(int fd, struct file *filp, int on)
{
        struct fasync_struct *fa, *fna=NULL, **prev;
        struct socket *sock;
        
        if (on)
        {
                fna=(struct fasync_struct *)kmalloc(sizeof(struct fasync_struct), GFP_KERNEL);
                if(fna==NULL)
                        return -ENOMEM;
        }

        sock = socki_lookup(filp->f_dentry->d_inode);
        
        prev=&(sock->fasync_list);

        lock_sock(sock->sk); 
        
        for (fa=*prev; fa!=NULL; prev=&fa->fa_next,fa=*prev)
                if (fa->fa_file==filp)
                        break;
        
        if(on)
        {
                if(fa!=NULL)
                {
                        fa->fa_fd=fd;
                        kfree_s(fna,sizeof(struct fasync_struct));
                        release_sock(sock->sk); 
                        return 0;
                }
                fna->fa_file=filp;
                fna->fa_fd=fd;
                fna->magic=FASYNC_MAGIC;
                fna->fa_next=sock->fasync_list;
                sock->fasync_list=fna;
        }
        else
        {
                if (fa!=NULL)
                {
                        *prev=fa->fa_next;
                        kfree_s(fa,sizeof(struct fasync_struct));
                }
        }

        release_sock(sock->sk); 
        return 0;
}

int sock_wake_async(struct socket *sock, int how)
{
        if (!sock || !sock->fasync_list)
                return -1;
        switch (how)
        {
        case 1:
                if (sock->flags & SO_WAITDATA)
                        break;
                goto call_kill;
        case 2:
                if (!(sock->flags & SO_NOSPACE))
                        break;
                sock->flags &= ~SO_NOSPACE;
                /* fall through */
        case 0:
        call_kill:
                kill_fasync(sock->fasync_list, SIGIO);
                break;
        }
        return 0;
}


int sock_create(int family, int type, int protocol, struct socket **res)
{
        int i;
        struct socket *sock;

        /*
         *      Check protocol is in range
         */
        if(family<0||family>=NPROTO)
                return -EINVAL;
                
#if defined(CONFIG_KMOD) && defined(CONFIG_NET)
        /* Attempt to load a protocol module if the find failed. 
         * 
         * 12/09/1996 Marcin: But! this makes REALLY only sense, if the user 
         * requested real, full-featured networking support upon configuration.
         * Otherwise module support will break!
         */
        if (net_families[family]==NULL)
        {
                char module_name[30];
                sprintf(module_name,"net-pf-%d",family);
                request_module(module_name);
        }
#endif

        if (net_families[family]==NULL)
                return -EINVAL;

/*
 *      Check that this is a type that we know how to manipulate and
 *      the protocol makes sense here. The family can still reject the
 *      protocol later.
 */
 
        if ((type != SOCK_STREAM && type != SOCK_DGRAM &&
             type != SOCK_SEQPACKET && type != SOCK_RAW && type != SOCK_RDM &&
#ifdef CONFIG_XTP
                type != SOCK_WEB  &&
#endif
             type != SOCK_PACKET) || protocol < 0)
                        return -EINVAL;

/*
 *      Allocate the socket and allow the family to set things up. if
 *      the protocol is 0, the family is instructed to select an appropriate
 *      default.
 */

        if (!(sock = sock_alloc())) 
        {
                printk(KERN_WARNING "socket: no more sockets\n");
                return -ENFILE;         /* Not exactly a match, but its the
                                           closest posix thing */
        }

        sock->type   = type;

        if ((i = net_families[family]->create(sock, protocol)) < 0) 
        {
                sock_release(sock);
                return i;
        }

        *res = sock;
        return 0;
}

asmlinkage int sys_socket(int family, int type, int protocol)
{
        int retval;
        struct socket *sock;

        lock_kernel();

        retval = sock_create(family, type, protocol, &sock);
        if (retval < 0)
                goto out;

        retval = get_fd(sock->inode);
        if (retval < 0)
                goto out_release;
        sock->file = fcheck(retval);

out:
        unlock_kernel();
        return retval;

out_release:
        sock_release(sock);
        goto out;
}

/*
 *      Create a pair of connected sockets.
 */

asmlinkage int sys_socketpair(int family, int type, int protocol, int usockvec[2])
{
        struct socket *sock1, *sock2;
        int fd1, fd2, err;

        lock_kernel();

        /*
         * Obtain the first socket and check if the underlying protocol
         * supports the socketpair call.
         */

        err = sys_socket(family, type, protocol);
        if (err < 0)
                goto out;
        fd1 = err;

        /*
         * Now grab another socket
         */
        err = -EINVAL;
        fd2 = sys_socket(family, type, protocol);
        if (fd2 < 0) 
                goto out_close1;

        /*
         * Get the sockets for the two fd's
         */
        sock1 = sockfd_lookup(fd1, &err);
        if (!sock1)
                goto out_close2;
        sock2 = sockfd_lookup(fd2, &err);
        if (!sock2)
                goto out_put1;

        /* try to connect the two sockets together */ 
        err = sock1->ops->socketpair(sock1, sock2);
        if (err < 0) 
                goto out_put2;

        err = put_user(fd1, &usockvec[0]); 
        if (err) 
                goto out_put2;
        err = put_user(fd2, &usockvec[1]);

out_put2:
        sockfd_put(sock2);
out_put1:
        sockfd_put(sock1);

        if (err) {
        out_close2:
                sys_close(fd2);
        out_close1:
                sys_close(fd1);
        }
out:
        unlock_kernel();
        return err;
}


/*
 *      Bind a name to a socket. Nothing much to do here since it's
 *      the protocol's responsibility to handle the local address.
 *
 *      We move the socket address to kernel space before we call
 *      the protocol layer (having also checked the address is ok).
 */

asmlinkage int sys_bind(int fd, struct sockaddr *umyaddr, int addrlen)
{
        struct socket *sock;
        char address[MAX_SOCK_ADDR];
        int err;

        lock_kernel();
        if((sock = sockfd_lookup(fd,&err))!=NULL)
        {
                if((err=move_addr_to_kernel(umyaddr,addrlen,address))>=0)
                        err = sock->ops->bind(sock, (struct sockaddr *)address, addrlen);
                sockfd_put(sock);
        }                       
        unlock_kernel();
        return err;
}


/*
 *      Perform a listen. Basically, we allow the protocol to do anything
 *      necessary for a listen, and if that works, we mark the socket as
 *      ready for listening.
 */

asmlinkage int sys_listen(int fd, int backlog)
{
        struct socket *sock;
        int err;
        
        lock_kernel();
        if((sock = sockfd_lookup(fd, &err))!=NULL)
        {
                err=sock->ops->listen(sock, backlog);
                sockfd_put(sock);
        }
        unlock_kernel();
        return err;
}


/*
 *      For accept, we attempt to create a new socket, set up the link
 *      with the client, wake up the client, then return the new
 *      connected fd. We collect the address of the connector in kernel
 *      space and move it to user at the very end. This is unclean because
 *      we open the socket then return an error.
 *
 *      1003.1g adds the ability to recvmsg() to query connection pending
 *      status to recvmsg. We need to add that support in a way thats
 *      clean when we restucture accept also.
 */

asmlinkage int sys_accept(int fd, struct sockaddr *upeer_sockaddr, int *upeer_addrlen)
{
        struct inode *inode;
        struct socket *sock, *newsock;
        int err, len;
        char address[MAX_SOCK_ADDR];

        lock_kernel();
        sock = sockfd_lookup(fd, &err);
        if (!sock)
                goto out;

restart:
        err = -EMFILE;
        if (!(newsock = sock_alloc())) 
                goto out_put;

        inode = newsock->inode;
        newsock->type = sock->type;

        err = sock->ops->dup(newsock, sock);
        if (err < 0) 
                goto out_release;

        err = newsock->ops->accept(sock, newsock, sock->file->f_flags);
        if (err < 0)
                goto out_release;
        newsock = socki_lookup(inode);

        if ((err = get_fd(inode)) < 0) 
                goto out_release;
        newsock->file = fcheck(err);

        if (upeer_sockaddr)
        {
                /* Handle the race where the accept works and we
                   then getname after it has closed again */
                if(newsock->ops->getname(newsock, (struct sockaddr *)address, &len, 1)<0)
                {
                        sys_close(err);
                        goto restart;
                }
                /* N.B. Should check for errors here */
                move_addr_to_user(address, len, upeer_sockaddr, upeer_addrlen);
        }

out_put:
        sockfd_put(sock);
out:
        unlock_kernel();
        return err;

out_release:
        sock_release(newsock);
        goto out_put;
}


/*
 *      Attempt to connect to a socket with the server address.  The address
 *      is in user space so we verify it is OK and move it to kernel space.
 *
 *      For 1003.1g we need to add clean support for a bind to AF_UNSPEC to
 *      break bindings
 *
 *      NOTE: 1003.1g draft 6.3 is broken with respect to AX.25/NetROM and
 *      other SEQPACKET protocols that take time to connect() as it doesn't
 *      include the -EINPROGRESS status for such sockets.
 */

asmlinkage int sys_connect(int fd, struct sockaddr *uservaddr, int addrlen)
{
        struct socket *sock;
        char address[MAX_SOCK_ADDR];
        int err;

        lock_kernel();
        sock = sockfd_lookup(fd, &err);
        if (!sock)
                goto out;
        err = move_addr_to_kernel(uservaddr, addrlen, address);
        if (err < 0)
                goto out_put;
        err = sock->ops->connect(sock, (struct sockaddr *) address, addrlen,
                                 sock->file->f_flags);
out_put:
        sockfd_put(sock);
out:
        unlock_kernel();
        return err;
}

/*
 *      Get the local address ('name') of a socket object. Move the obtained
 *      name to user space.
 */

asmlinkage int sys_getsockname(int fd, struct sockaddr *usockaddr, int *usockaddr_len)
{
        struct socket *sock;
        char address[MAX_SOCK_ADDR];
        int len, err;
        
        lock_kernel();
        sock = sockfd_lookup(fd, &err);
        if (!sock)
                goto out;
        err = sock->ops->getname(sock, (struct sockaddr *)address, &len, 0);
        if (err)
                goto out_put;
        err = move_addr_to_user(address, len, usockaddr, usockaddr_len);

out_put:
        sockfd_put(sock);
out:
        unlock_kernel();
        return err;
}

/*
 *      Get the remote address ('name') of a socket object. Move the obtained
 *      name to user space.
 */

asmlinkage int sys_getpeername(int fd, struct sockaddr *usockaddr, int *usockaddr_len)
{
        struct socket *sock;
        char address[MAX_SOCK_ADDR];
        int len, err;

        lock_kernel();
        if ((sock = sockfd_lookup(fd, &err))!=NULL)
        {
                err = sock->ops->getname(sock, (struct sockaddr *)address, &len, 1);
                if (!err)
                        err=move_addr_to_user(address,len, usockaddr, usockaddr_len);
                sockfd_put(sock);
        }
        unlock_kernel();
        return err;
}

/*
 *      Send a datagram to a given address. We move the address into kernel
 *      space and check the user space data area is readable before invoking
 *      the protocol.
 */

asmlinkage int sys_sendto(int fd, void * buff, size_t len, unsigned flags,
           struct sockaddr *addr, int addr_len)
{
        struct socket *sock;
        char address[MAX_SOCK_ADDR];
        int err;
        struct msghdr msg;
        struct iovec iov;
        
        lock_kernel();
        sock = sockfd_lookup(fd, &err);
        if (!sock)
                goto out;
        iov.iov_base=buff;
        iov.iov_len=len;
        msg.msg_name=NULL;
        msg.msg_iov=&iov;
        msg.msg_iovlen=1;
        msg.msg_control=NULL;
        msg.msg_controllen=0;
        msg.msg_namelen=addr_len;
        if(addr)
        {
                err = move_addr_to_kernel(addr, addr_len, address);
                if (err < 0)
                        goto out_put;
                msg.msg_name=address;
        }
        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;
        msg.msg_flags = flags;
        err = sock_sendmsg(sock, &msg, len);

out_put:                
        sockfd_put(sock);
out:
        unlock_kernel();
        return err;
}

/*
 *      Send a datagram down a socket. 
 */

asmlinkage int sys_send(int fd, void * buff, size_t len, unsigned flags)
{
        return sys_sendto(fd, buff, len, flags, NULL, 0);
}

/*
 *      Receive a frame from the socket and optionally record the address of the 
 *      sender. We verify the buffers are writable and if needed move the
 *      sender address from kernel to user space.
 */

asmlinkage int sys_recvfrom(int fd, void * ubuf, size_t size, unsigned flags,
             struct sockaddr *addr, int *addr_len)
{
        struct socket *sock;
        struct iovec iov;
        struct msghdr msg;
        char address[MAX_SOCK_ADDR];
        int err,err2;

        lock_kernel();
        sock = sockfd_lookup(fd, &err);
        if (!sock)
                goto out;

        msg.msg_control=NULL;
        msg.msg_controllen=0;
        msg.msg_iovlen=1;
        msg.msg_iov=&iov;
        iov.iov_len=size;
        iov.iov_base=ubuf;
        msg.msg_name=address;
        msg.msg_namelen=MAX_SOCK_ADDR;
        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;
        err=sock_recvmsg(sock, &msg, size, flags);

        if(err >= 0 && addr != NULL)
        {
                err2=move_addr_to_user(address, msg.msg_namelen, addr, addr_len);
                if(err2<0)
                        err=err2;
        }
        sockfd_put(sock);                       
out:
        unlock_kernel();
        return err;
}

/*
 *      Receive a datagram from a socket. 
 */

asmlinkage int sys_recv(int fd, void * ubuf, size_t size, unsigned flags)
{
        return sys_recvfrom(fd, ubuf, size, flags, NULL, NULL);
}

/*
 *      Set a socket option. Because we don't know the option lengths we have
 *      to pass the user mode parameter for the protocols to sort out.
 */

asmlinkage int sys_setsockopt(int fd, int level, int optname, char *optval, int optlen)
{
        int err;
        struct socket *sock;
        
        lock_kernel();
        if ((sock = sockfd_lookup(fd, &err))!=NULL)
        {
                if (level == SOL_SOCKET)
                        err=sock_setsockopt(sock,level,optname,optval,optlen);
                else
                        err=sock->ops->setsockopt(sock, level, optname, optval, optlen);
                sockfd_put(sock);
        }
        unlock_kernel();
        return err;
}

/*
 *      Get a socket option. Because we don't know the option lengths we have
 *      to pass a user mode parameter for the protocols to sort out.
 */

asmlinkage int sys_getsockopt(int fd, int level, int optname, char *optval, int *optlen)
{
        int err;
        struct socket *sock;

        lock_kernel();
        if ((sock = sockfd_lookup(fd, &err))!=NULL)
        {
                if (level == SOL_SOCKET)
                        err=sock_getsockopt(sock,level,optname,optval,optlen);
                else
                        err=sock->ops->getsockopt(sock, level, optname, optval, optlen);
                sockfd_put(sock);
        }
        unlock_kernel();
        return err;
}


/*
 *      Shutdown a socket.
 */

asmlinkage int sys_shutdown(int fd, int how)
{
        int err;
        struct socket *sock;

        lock_kernel();
        if ((sock = sockfd_lookup(fd, &err))!=NULL)
        {
                err=sock->ops->shutdown(sock, how);
                sockfd_put(sock);
        }
        unlock_kernel();
        return err;
}

/*
 *      BSD sendmsg interface
 */

asmlinkage int sys_sendmsg(int fd, struct msghdr *msg, unsigned flags)
{
        struct socket *sock;
        char address[MAX_SOCK_ADDR];
        struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
        unsigned char ctl[sizeof(struct cmsghdr) + 20]; /* 20 is size of ipv6_pktinfo */
        unsigned char *ctl_buf = ctl;
        struct msghdr msg_sys;
        int err, ctl_len, iov_size, total_len;
        
        lock_kernel();

        err = -EFAULT;
        if (copy_from_user(&msg_sys,msg,sizeof(struct msghdr)))
                goto out; 

        sock = sockfd_lookup(fd, &err);
        if (!sock) 
                goto out;

        /* do not move before msg_sys is valid */
        err = -EINVAL;
        if (msg_sys.msg_iovlen > UIO_MAXIOV)
                goto out_put;

        /* Check whether to allocate the iovec area*/
        err = -ENOMEM;
        iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
        if (msg_sys.msg_iovlen > 1 /* UIO_FASTIOV */) {
                iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
                if (!iov)
                        goto out_put;
        }

        /* This will also move the address data into kernel space */
        err = verify_iovec(&msg_sys, iov, address, VERIFY_READ);
        if (err < 0) 
                goto out_freeiov;
        total_len = err;

        ctl_len = msg_sys.msg_controllen; 
        if (ctl_len) 
        {
                if (ctl_len > sizeof(ctl))
                {
                        /* Suggested by the Advanced Sockets API for IPv6 draft:
                         * Limit the msg_controllen size by the SO_SNDBUF size.
                         */
                        /* Note - when this code becomes multithreaded on
                         * SMP machines you have a race to fix here.
                         */
                        err = -ENOBUFS;
                        ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL);
                        if (ctl_buf == NULL) 
                                goto out_freeiov;
                }
                err = -EFAULT;
                if (copy_from_user(ctl_buf, msg_sys.msg_control, ctl_len))
                        goto out_freectl;
                msg_sys.msg_control = ctl_buf;
        }
        msg_sys.msg_flags = flags;

        if (sock->file->f_flags & O_NONBLOCK)
                msg_sys.msg_flags |= MSG_DONTWAIT;
        err = sock_sendmsg(sock, &msg_sys, total_len);

out_freectl:
        if (ctl_buf != ctl)    
                sock_kfree_s(sock->sk, ctl_buf, ctl_len);
out_freeiov:
        if (iov != iovstack)
                sock_kfree_s(sock->sk, iov, iov_size);
out_put:
        sockfd_put(sock);
out:       
        unlock_kernel();
        return err;
}

/*
 *      BSD recvmsg interface
 */

asmlinkage int sys_recvmsg(int fd, struct msghdr *msg, unsigned int flags)
{
        struct socket *sock;
        struct iovec iovstack[UIO_FASTIOV];
        struct iovec *iov=iovstack;
        struct msghdr msg_sys;
        unsigned long cmsg_ptr;
        int err, iov_size, total_len, len;

        /* kernel mode address */
        char addr[MAX_SOCK_ADDR];

        /* user mode address pointers */
        struct sockaddr *uaddr;
        int *uaddr_len;
        
        lock_kernel();
        err=-EFAULT;
        if (copy_from_user(&msg_sys,msg,sizeof(struct msghdr)))
                goto out;

        sock = sockfd_lookup(fd, &err);
        if (!sock)
                goto out;

        err = -EINVAL;
        if (msg_sys.msg_iovlen > UIO_MAXIOV)
                goto out_put;
        
        /* Check whether to allocate the iovec area*/
        err = -ENOMEM;
        iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
        if (msg_sys.msg_iovlen > UIO_FASTIOV) {
                iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
                if (!iov)
                        goto out_put;
        }

        /*
         *      Save the user-mode address (verify_iovec will change the
         *      kernel msghdr to use the kernel address space)
         */
         
        uaddr = msg_sys.msg_name;
        uaddr_len = &msg->msg_namelen;
        err = verify_iovec(&msg_sys, iov, addr, VERIFY_WRITE);
        if (err < 0)
                goto out_freeiov;
        total_len=err;

        cmsg_ptr = (unsigned long)msg_sys.msg_control;
        msg_sys.msg_flags = 0;
        
        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;
        err = sock_recvmsg(sock, &msg_sys, total_len, flags);
        if (err < 0)
                goto out_freeiov;
        len = err;

        if (uaddr != NULL) {
                err = move_addr_to_user(addr, msg_sys.msg_namelen, uaddr, uaddr_len);
                if (err < 0)
                        goto out_freeiov;
        }
        err = __put_user(msg_sys.msg_flags, &msg->msg_flags);
        if (err)
                goto out_freeiov;
        err = __put_user((unsigned long)msg_sys.msg_control-cmsg_ptr, 
                                                         &msg->msg_controllen);
        if (err)
                goto out_freeiov;
        err = len;

out_freeiov:
        if (iov != iovstack)
                sock_kfree_s(sock->sk, iov, iov_size);
out_put:
        sockfd_put(sock);
out:
        unlock_kernel();
        return err;
}


/*
 *      Perform a file control on a socket file descriptor.
 *
 *      Doesn't aquire a fd lock, because no network fcntl
 *      function sleeps currently.
 */

int sock_fcntl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct socket *sock;

        sock = socki_lookup (filp->f_dentry->d_inode);
        if (sock && sock->ops)
                return sock->ops->fcntl(sock, cmd, arg);
        return(-EINVAL);
}

/* Argument list sizes for sys_socketcall */
#define AL(x) ((x) * sizeof(unsigned long))
static unsigned char nargs[18]={AL(0),AL(3),AL(3),AL(3),AL(2),AL(3),
                                AL(3),AL(3),AL(4),AL(4),AL(4),AL(6),
                                AL(6),AL(2),AL(5),AL(5),AL(3),AL(3)};
#undef AL

/*
 *      System call vectors. 
 *
 *      Argument checking cleaned up. Saved 20% in size.
 *  This function doesn't need to set the kernel lock because
 *  it is set by the callees. 
 */

asmlinkage int sys_socketcall(int call, unsigned long *args)
{
        unsigned long a[6];
        unsigned long a0,a1;
        int err;

        if(call<1||call>SYS_RECVMSG)
                return -EINVAL;

        /* copy_from_user should be SMP safe. */
        if (copy_from_user(a, args, nargs[call]))
                return -EFAULT;
                
        a0=a[0];
        a1=a[1];
        
        switch(call) 
        {
                case SYS_SOCKET:
                        err = sys_socket(a0,a1,a[2]);
                        break;
                case SYS_BIND:
                        err = sys_bind(a0,(struct sockaddr *)a1, a[2]);
                        break;
                case SYS_CONNECT:
                        err = sys_connect(a0, (struct sockaddr *)a1, a[2]);
                        break;
                case SYS_LISTEN:
                        err = sys_listen(a0,a1);
                        break;
                case SYS_ACCEPT:
                        err = sys_accept(a0,(struct sockaddr *)a1, (int *)a[2]);
                        break;
                case SYS_GETSOCKNAME:
                        err = sys_getsockname(a0,(struct sockaddr *)a1, (int *)a[2]);
                        break;
                case SYS_GETPEERNAME:
                        err = sys_getpeername(a0, (struct sockaddr *)a1, (int *)a[2]);
                        break;
                case SYS_SOCKETPAIR:
                        err = sys_socketpair(a0,a1, a[2], (int *)a[3]);
                        break;
                case SYS_SEND:
                        err = sys_send(a0, (void *)a1, a[2], a[3]);
                        break;
                case SYS_SENDTO:
                        err = sys_sendto(a0,(void *)a1, a[2], a[3],
                                         (struct sockaddr *)a[4], a[5]);
                        break;
                case SYS_RECV:
                        err = sys_recv(a0, (void *)a1, a[2], a[3]);
                        break;
                case SYS_RECVFROM:
                        err = sys_recvfrom(a0, (void *)a1, a[2], a[3],
                                           (struct sockaddr *)a[4], (int *)a[5]);
                        break;
                case SYS_SHUTDOWN:
                        err = sys_shutdown(a0,a1);
                        break;
                case SYS_SETSOCKOPT:
                        err = sys_setsockopt(a0, a1, a[2], (char *)a[3], a[4]);
                        break;
                case SYS_GETSOCKOPT:
                        err = sys_getsockopt(a0, a1, a[2], (char *)a[3], (int *)a[4]);
                        break;
                case SYS_SENDMSG:
                        err = sys_sendmsg(a0, (struct msghdr *) a1, a[2]);
                        break;
                case SYS_RECVMSG:
                        err = sys_recvmsg(a0, (struct msghdr *) a1, a[2]);
                        break;
                default:
                        err = -EINVAL;
                        break;
        }
        return err;
}

/*
 *      This function is called by a protocol handler that wants to
 *      advertise its address family, and have it linked into the
 *      SOCKET module.
 */

int sock_register(struct net_proto_family *ops)
{
        if (ops->family >= NPROTO) {
                printk(KERN_CRIT "protocol %d >= NPROTO(%d)\n", ops->family, NPROTO);
                return -ENOBUFS;
        }
        net_families[ops->family]=ops;
        return 0;
}

/*
 *      This function is called by a protocol handler that wants to
 *      remove its address family, and have it unlinked from the
 *      SOCKET module.
 */

int sock_unregister(int family)
{
        if (family < 0 || family >= NPROTO)
                return -1;

        net_families[family]=NULL;
        return 0;
}

void __init proto_init(void)
{
        extern struct net_proto protocols[];    /* Network protocols */
        struct net_proto *pro;

        /* Kick all configured protocols. */
        pro = protocols;
        while (pro->name != NULL) 
        {
                (*pro->init_func)(pro);
                pro++;
        }
        /* We're all done... */
}

extern void sk_init(void);
#ifdef CONFIG_WAN_ROUTER
extern void wanrouter_init(void);
#endif

void __init sock_init(void)
{
        int i;

        printk(KERN_INFO "Linux NET4.0 for Linux 2.2\n");
        printk(KERN_INFO "Based upon Swansea University Computer Society NET3.039\n");

        /*
         *      Initialize all address (protocol) families. 
         */
         
        for (i = 0; i < NPROTO; i++) 
                net_families[i] = NULL;

        /*
         *      Initialize sock SLAB cache.
         */
         
        sk_init();

#ifdef SLAB_SKB
        /*
         *      Initialize skbuff SLAB cache 
         */
        skb_init();
#endif


        /*
         *      Wan router layer. 
         */

#ifdef CONFIG_WAN_ROUTER         
        wanrouter_init();
#endif

        /*
         *      Attach the firewall module if configured
         */
         
#ifdef CONFIG_FIREWALL   
        fwchain_init();
#endif

        /*
         *      Initialize the protocols module. 
         */

        proto_init();

        /*
         *      The netlink device handler may be needed early.
         */

#ifdef  CONFIG_RTNETLINK
        rtnetlink_init();
#endif
#ifdef CONFIG_NETLINK_DEV
        init_netlink();
#endif
}

int socket_get_info(char *buffer, char **start, off_t offset, int length)
{
        int len = sprintf(buffer, "sockets: used %d\n", sockets_in_use);
        if (offset >= len)
        {
                *start = buffer;
                return 0;
        }
        *start = buffer + offset;
        len -= offset;
        if (len > length)
                len = length;
        return len;
}