path: root/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.
 *
 *		AF_INET protocol family socket handler.
 *
 * Version:	$Id: af_inet.c,v 1.6 1998/03/17 22:18:20 ralf 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.
 *
 *		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))

extern int sysctl_core_destroy_delay;

extern int raw_get_info(char *, char **, off_t, int, int);
extern int snmp_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);

  	/* Now the backlog. */
  	while((skb=skb_dequeue(&sk->back_log)) != NULL)
		kfree_skb(skb);
}

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]
	 */
		  
	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;
	release_sock(sk);
	net_reset_timer(sk, TIME_DESTROY, sysctl_core_destroy_delay);
}

void destroy_sock(struct sock *sk)
{
	lock_sock(sk);			/* just to be safe. */

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

	sock->state = SS_UNCONNECTED;
	sk = sk_alloc(AF_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;
		sk->no_check = TCP_NO_CHECK;
		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 (!suser())
			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 = AF_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) {
		unsigned 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 = ~0UL;

			/* XXX This makes no sense whatsoever... -DaveM */
			if (!sk->lingertime)
				timeout = jiffies + 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;
		
	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 && !suser())
		return(-EACCES);
	
	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 || !suser())
#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 */

	/* 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);
}

/*
 *	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) {
		if(tcp_connected(sk->state)) {
			sock->state = SS_CONNECTED;
			return 0;
		}
		if(sk->protocol == IPPROTO_TCP && (flags & O_NONBLOCK)) {
			if(sk->err)
				return sock_error(sk);
			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);
		if (err < 0)
			return(err);
  		sock->state = SS_CONNECTING;
	}
	
	if (sk->state > TCP_FIN_WAIT2 && sock->state == SS_CONNECTING) {
		sock->state = SS_UNCONNECTED;
		return sock_error(sk);
	}

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

	cli();
	while(sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV) {
		interruptible_sleep_on(sk->sleep);
		if (signal_pending(current)) {
			sti();
			return(-ERESTARTSYS);
		}
		/* This fixes a nasty in the tcp/ip code. There is a hideous hassle with
		   icmp error packets wanting to close a tcp or udp socket. */
		if (sk->err && sk->protocol == IPPROTO_TCP) {
			sock->state = SS_UNCONNECTED;
			sti();
			return sock_error(sk); /* set by tcp_err() */
		}
	}
	sti();

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

/*
 *	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;

	cli();
	while (sk2->state == TCP_SYN_RECV) {
		interruptible_sleep_on(sk2->sleep);
		if (signal_pending(current))
			goto do_interrupted;
	}
	sti();
	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_interrupted:
	sti();
	sk1->pair = sk2;
	sk2->sleep = NULL;
	sk2->socket = NULL;
	newsock->sk = newsk;
	newsk->socket = newsock;
	err = -ERESTARTSYS;
do_err:
	return err;
do_sk1_err:
	err = sock_error(sk1);
	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);
	if (sk->err)
		return sock_error(sk);
	/* 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);
	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 && !suser())
				return -EPERM;
			sk->proc = pid;
			return(0);
		case FIOGETOWN:
		case SIOCGPGRP:
			return put_user(sk->proc, (int *)arg);
			return(0);			
		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 = {
	AF_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 = {
	AF_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 = {
	AF_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_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);

/*
 *	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 "Swansea University Computer Society TCP/IP for NET3.037\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();

	/* 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_ACCT)||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_sockstat);
	proc_net_register(&proc_net_tcp);
	proc_net_register(&proc_net_udp);
#endif		/* CONFIG_PROC_FS */
}