Initial revision

1 files changed, 5100 insertions, 0 deletions

diff --git a/pfinet/linux-inet/tcp.c b/pfinet/linux-inet/tcp.c
new file mode 100644
index 00000000..c73ad07f
--- /dev/null
+++ b/pfinet/linux-inet/tcp.c
@@ -0,0 +1,5100 @@
+/*
+ * 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.
+ *
+ *		Implementation of the Transmission Control Protocol(TCP).
+ *
+ * Version:	@(#)tcp.c	1.0.16	05/25/93
+ *
+ * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *		Mark Evans, <evansmp@uhura.aston.ac.uk>
+ *		Corey Minyard <wf-rch!minyard@relay.EU.net>
+ *		Florian La Roche, <flla@stud.uni-sb.de>
+ *		Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
+ *		Linus Torvalds, <torvalds@cs.helsinki.fi>
+ *		Alan Cox, <gw4pts@gw4pts.ampr.org>
+ *		Matthew Dillon, <dillon@apollo.west.oic.com>
+ *		Arnt Gulbrandsen, <agulbra@no.unit.nvg>
+ *
+ * Fixes:	
+ *		Alan Cox	:	Numerous verify_area() calls
+ *		Alan Cox	:	Set the ACK bit on a reset
+ *		Alan Cox	:	Stopped it crashing if it closed while sk->inuse=1
+ *					and was trying to connect (tcp_err()).
+ *		Alan Cox	:	All icmp error handling was broken
+ *					pointers passed where wrong and the
+ *					socket was looked up backwards. Nobody
+ *					tested any icmp error code obviously.
+ *		Alan Cox	:	tcp_err() now handled properly. It wakes people
+ *					on errors. select behaves and the icmp error race
+ *					has gone by moving it into sock.c
+ *		Alan Cox	:	tcp_reset() fixed to work for everything not just
+ *					packets for unknown sockets.
+ *		Alan Cox	:	tcp option processing.
+ *		Alan Cox	:	Reset tweaked (still not 100%) [Had syn rule wrong]
+ *		Herp Rosmanith  :	More reset fixes
+ *		Alan Cox	:	No longer acks invalid rst frames. Acking
+ *					any kind of RST is right out.
+ *		Alan Cox	:	Sets an ignore me flag on an rst receive
+ *					otherwise odd bits of prattle escape still
+ *		Alan Cox	:	Fixed another acking RST frame bug. Should stop
+ *					LAN workplace lockups.
+ *		Alan Cox	: 	Some tidyups using the new skb list facilities
+ *		Alan Cox	:	sk->keepopen now seems to work
+ *		Alan Cox	:	Pulls options out correctly on accepts
+ *		Alan Cox	:	Fixed assorted sk->rqueue->next errors
+ *		Alan Cox	:	PSH doesn't end a TCP read. Switched a bit to skb ops.
+ *		Alan Cox	:	Tidied tcp_data to avoid a potential nasty.
+ *		Alan Cox	:	Added some better commenting, as the tcp is hard to follow
+ *		Alan Cox	:	Removed incorrect check for 20 * psh
+ *	Michael O'Reilly	:	ack < copied bug fix.
+ *	Johannes Stille		:	Misc tcp fixes (not all in yet).
+ *		Alan Cox	:	FIN with no memory -> CRASH
+ *		Alan Cox	:	Added socket option proto entries. Also added awareness of them to accept.
+ *		Alan Cox	:	Added TCP options (SOL_TCP)
+ *		Alan Cox	:	Switched wakeup calls to callbacks, so the kernel can layer network sockets.
+ *		Alan Cox	:	Use ip_tos/ip_ttl settings.
+ *		Alan Cox	:	Handle FIN (more) properly (we hope).
+ *		Alan Cox	:	RST frames sent on unsynchronised state ack error/
+ *		Alan Cox	:	Put in missing check for SYN bit.
+ *		Alan Cox	:	Added tcp_select_window() aka NET2E 
+ *					window non shrink trick.
+ *		Alan Cox	:	Added a couple of small NET2E timer fixes
+ *		Charles Hedrick :	TCP fixes
+ *		Toomas Tamm	:	TCP window fixes
+ *		Alan Cox	:	Small URG fix to rlogin ^C ack fight
+ *		Charles Hedrick	:	Rewrote most of it to actually work
+ *		Linus		:	Rewrote tcp_read() and URG handling
+ *					completely
+ *		Gerhard Koerting:	Fixed some missing timer handling
+ *		Matthew Dillon  :	Reworked TCP machine states as per RFC
+ *		Gerhard Koerting:	PC/TCP workarounds
+ *		Adam Caldwell	:	Assorted timer/timing errors
+ *		Matthew Dillon	:	Fixed another RST bug
+ *		Alan Cox	:	Move to kernel side addressing changes.
+ *		Alan Cox	:	Beginning work on TCP fastpathing (not yet usable)
+ *		Arnt Gulbrandsen:	Turbocharged tcp_check() routine.
+ *		Alan Cox	:	TCP fast path debugging
+ *		Alan Cox	:	Window clamping
+ *		Michael Riepe	:	Bug in tcp_check()
+ *		Matt Dillon	:	More TCP improvements and RST bug fixes
+ *		Matt Dillon	:	Yet more small nasties remove from the TCP code
+ *					(Be very nice to this man if tcp finally works 100%) 8)
+ *		Alan Cox	:	BSD accept semantics. 
+ *		Alan Cox	:	Reset on closedown bug.
+ *	Peter De Schrijver	:	ENOTCONN check missing in tcp_sendto().
+ *		Michael Pall	:	Handle select() after URG properly in all cases.
+ *		Michael Pall	:	Undo the last fix in tcp_read_urg() (multi URG PUSH broke rlogin).
+ *		Michael Pall	:	Fix the multi URG PUSH problem in tcp_readable(), select() after URG works now.
+ *		Michael Pall	:	recv(...,MSG_OOB) never blocks in the BSD api.
+ *		Alan Cox	:	Changed the semantics of sk->socket to 
+ *					fix a race and a signal problem with
+ *					accept() and async I/O.
+ *		Alan Cox	:	Relaxed the rules on tcp_sendto().
+ *		Yury Shevchuk	:	Really fixed accept() blocking problem.
+ *		Craig I. Hagan  :	Allow for BSD compatible TIME_WAIT for
+ *					clients/servers which listen in on
+ *					fixed ports.
+ *		Alan Cox	:	Cleaned the above up and shrank it to
+ *					a sensible code size.
+ *		Alan Cox	:	Self connect lockup fix.
+ *		Alan Cox	:	No connect to multicast.
+ *		Ross Biro	:	Close unaccepted children on master
+ *					socket close.
+ *		Alan Cox	:	Reset tracing code.
+ *		Alan Cox	:	Spurious resets on shutdown.
+ *		Alan Cox	:	Giant 15 minute/60 second timer error
+ *		Alan Cox	:	Small whoops in selecting before an accept.
+ *		Alan Cox	:	Kept the state trace facility since it's
+ *					handy for debugging.
+ *		Alan Cox	:	More reset handler fixes.
+ *		Alan Cox	:	Started rewriting the code based on the RFC's
+ *					for other useful protocol references see:  
+ *					Comer, KA9Q NOS, and for a reference on the
+ *					difference between specifications and how BSD
+ *					works see the 4.4lite source.
+ *		A.N.Kuznetsov	:	Don't time wait on completion of tidy 
+ *					close.
+ *		Linus Torvalds	:	Fin/Shutdown & copied_seq changes.
+ *		Linus Torvalds	:	Fixed BSD port reuse to work first syn
+ *		Alan Cox	:	Reimplemented timers as per the RFC and using multiple
+ *					timers for sanity. 
+ *		Alan Cox	:	Small bug fixes, and a lot of new
+ *					comments.
+ *		Alan Cox	:	Fixed dual reader crash by locking
+ *					the buffers (much like datagram.c)
+ *		Alan Cox	:	Fixed stuck sockets in probe. A probe
+ *					now gets fed up of retrying without
+ *					(even a no space) answer.
+ *		Alan Cox	:	Extracted closing code better
+ *		Alan Cox	:	Fixed the closing state machine to
+ *					resemble the RFC.
+ *		Alan Cox	:	More 'per spec' fixes.
+ *		Alan Cox	:	tcp_data() doesn't ack illegal PSH
+ *					only frames. At least one pc tcp stack
+ *					generates them.
+ *
+ *
+ * To Fix:
+ *		Fast path the code. Two things here - fix the window calculation
+ *		so it doesn't iterate over the queue, also spot packets with no funny
+ *		options arriving in order and process directly.
+ *
+ *		Implement RFC 1191 [Path MTU discovery]
+ *		Look at the effect of implementing RFC 1337 suggestions and their impact.
+ *		Rewrite output state machine to use a single queue and do low window
+ *		situations as per the spec (RFC 1122)
+ *		Speed up input assembly algorithm.
+ *		RFC1323 - PAWS and window scaling. PAWS is required for IPv6 so we
+ *		could do with it working on IPv4
+ *		User settable/learned rtt/max window/mtu
+ *		Cope with MTU/device switches when retransmitting in tcp.
+ *		Fix the window handling to use PR's new code.
+ *
+ *		Change the fundamental structure to a single send queue maintained
+ *		by TCP (removing the bogus ip stuff [thus fixing mtu drops on
+ *		active routes too]). Cut the queue off in tcp_retransmit/
+ *		tcp_transmit.
+ *		Change the receive queue to assemble as it goes. This lets us
+ *		dispose of most of tcp_sequence, half of tcp_ack and chunks of
+ *		tcp_data/tcp_read as well as the window shrink crud.
+ *		Separate out duplicated code - tcp_alloc_skb, tcp_build_ack
+ *		tcp_queue_skb seem obvious routines to extract.
+ *	
+ *		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.
+ *
+ * Description of States:
+ *
+ *	TCP_SYN_SENT		sent a connection request, waiting for ack
+ *
+ *	TCP_SYN_RECV		received a connection request, sent ack,
+ *				waiting for final ack in three-way handshake.
+ *
+ *	TCP_ESTABLISHED		connection established
+ *
+ *	TCP_FIN_WAIT1		our side has shutdown, waiting to complete
+ *				transmission of remaining buffered data
+ *
+ *	TCP_FIN_WAIT2		all buffered data sent, waiting for remote
+ *				to shutdown
+ *
+ *	TCP_CLOSING		both sides have shutdown but we still have
+ *				data we have to finish sending
+ *
+ *	TCP_TIME_WAIT		timeout to catch resent junk before entering
+ *				closed, can only be entered from FIN_WAIT2
+ *				or CLOSING.  Required because the other end
+ *				may not have gotten our last ACK causing it
+ *				to retransmit the data packet (which we ignore)
+ *
+ *	TCP_CLOSE_WAIT		remote side has shutdown and is waiting for
+ *				us to finish writing our data and to shutdown
+ *				(we have to close() to move on to LAST_ACK)
+ *
+ *	TCP_LAST_ACK		out side has shutdown after remote has
+ *				shutdown.  There may still be data in our
+ *				buffer that we have to finish sending
+ *		
+ *	TCP_CLOSE		socket is finished
+ */
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/time.h>
+#include <linux/string.h>
+#include <linux/config.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/termios.h>
+#include <linux/in.h>
+#include <linux/fcntl.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include "snmp.h"
+#include "ip.h"
+#include "protocol.h"
+#include "icmp.h"
+#include "tcp.h"
+#include "arp.h"
+#include <linux/skbuff.h>
+#include "sock.h"
+#include "route.h"
+#include <linux/errno.h>
+#include <linux/timer.h>
+#include <asm/system.h>
+#include <asm/segment.h>
+#include <linux/mm.h>
+
+/*
+ *	The MSL timer is the 'normal' timer.
+ */
+ 
+#define reset_msl_timer(x,y,z)	reset_timer(x,y,z)
+
+#define SEQ_TICK 3
+unsigned long seq_offset;
+struct tcp_mib	tcp_statistics;
+
+static void tcp_close(struct sock *sk, int timeout);
+
+
+/*
+ *	The less said about this the better, but it works and will do for 1.2 
+ */
+
+static struct wait_queue *master_select_wakeup;
+
+static __inline__ int min(unsigned int a, unsigned int b)
+{
+	if (a < b) 
+		return(a);
+	return(b);
+}
+
+#undef STATE_TRACE
+
+#ifdef STATE_TRACE
+static char *statename[]={
+	"Unused","Established","Syn Sent","Syn Recv",
+	"Fin Wait 1","Fin Wait 2","Time Wait", "Close",
+	"Close Wait","Last ACK","Listen","Closing"
+};
+#endif
+
+static __inline__ void tcp_set_state(struct sock *sk, int state)
+{
+	if(sk->state==TCP_ESTABLISHED)
+		tcp_statistics.TcpCurrEstab--;
+#ifdef STATE_TRACE
+	if(sk->debug)
+		printk("TCP sk=%p, State %s -> %s\n",sk, statename[sk->state],statename[state]);
+#endif	
+	/* This is a hack but it doesn't occur often and it's going to
+	   be a real        to fix nicely */
+	   
+	if(state==TCP_ESTABLISHED && sk->state==TCP_SYN_RECV)
+	{
+		wake_up_interruptible(&master_select_wakeup);
+	}
+	sk->state=state;
+	if(state==TCP_ESTABLISHED)
+		tcp_statistics.TcpCurrEstab++;
+}
+
+/*
+ *	This routine picks a TCP windows for a socket based on
+ *	the following constraints
+ *  
+ *	1. The window can never be shrunk once it is offered (RFC 793)
+ *	2. We limit memory per socket
+ *   
+ *	For now we use NET2E3's heuristic of offering half the memory
+ *	we have handy. All is not as bad as this seems however because
+ *	of two things. Firstly we will bin packets even within the window
+ *	in order to get the data we are waiting for into the memory limit.
+ *	Secondly we bin common duplicate forms at receive time
+ *      Better heuristics welcome
+ */
+   
+int tcp_select_window(struct sock *sk)
+{
+	int new_window = sk->prot->rspace(sk);
+	
+	if(sk->window_clamp)
+		new_window=min(sk->window_clamp,new_window);
+	/*
+	 * 	Two things are going on here.  First, we don't ever offer a
+	 * 	window less than min(sk->mss, MAX_WINDOW/2).  This is the
+	 * 	receiver side of SWS as specified in RFC1122.
+	 * 	Second, we always give them at least the window they
+	 * 	had before, in order to avoid retracting window.  This
+	 * 	is technically allowed, but RFC1122 advises against it and
+	 * 	in practice it causes trouble.
+	 *
+	 * 	Fixme: This doesn't correctly handle the case where
+	 *	new_window > sk->window but not by enough to allow for the
+	 *	shift in sequence space. 
+	 */
+	if (new_window < min(sk->mss, MAX_WINDOW/2) || new_window < sk->window)
+		return(sk->window);
+	return(new_window);
+}
+
+/*
+ *	Find someone to 'accept'. Must be called with
+ *	sk->inuse=1 or cli()
+ */ 
+
+static struct sk_buff *tcp_find_established(struct sock *s)
+{
+	struct sk_buff *p=skb_peek(&s->receive_queue);
+	if(p==NULL)
+		return NULL;
+	do
+	{
+		if(p->sk->state == TCP_ESTABLISHED || p->sk->state >= TCP_FIN_WAIT1)
+			return p;
+		p=p->next;
+	}
+	while(p!=(struct sk_buff *)&s->receive_queue);
+	return NULL;
+}
+
+/*
+ *	Remove a completed connection and return it. This is used by
+ *	tcp_accept() to get connections from the queue.
+ */
+
+static struct sk_buff *tcp_dequeue_established(struct sock *s)
+{
+	struct sk_buff *skb;
+	unsigned long flags;
+	save_flags(flags);
+	cli(); 
+	skb=tcp_find_established(s);
+	if(skb!=NULL)
+		skb_unlink(skb);	/* Take it off the queue */
+	restore_flags(flags);
+	return skb;
+}
+
+/* 
+ *	This routine closes sockets which have been at least partially
+ *	opened, but not yet accepted. Currently it is only called by
+ *	tcp_close, and timeout mirrors the value there. 
+ */
+
+static void tcp_close_pending (struct sock *sk) 
+{
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&sk->receive_queue)) != NULL) 
+	{
+		skb->sk->dead=1;
+		tcp_close(skb->sk, 0);
+		kfree_skb(skb, FREE_READ);
+	}
+	return;
+}
+
+/*
+ *	Enter the time wait state. 
+ */
+
+static void tcp_time_wait(struct sock *sk)
+{
+	tcp_set_state(sk,TCP_TIME_WAIT);
+	sk->shutdown = SHUTDOWN_MASK;
+	if (!sk->dead)
+		sk->state_change(sk);
+	reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
+}
+
+/*
+ *	A socket has timed out on its send queue and wants to do a
+ *	little retransmitting. Currently this means TCP.
+ */
+
+void tcp_do_retransmit(struct sock *sk, int all)
+{
+	struct sk_buff * skb;
+	struct proto *prot;
+	struct device *dev;
+	int ct=0;
+
+	prot = sk->prot;
+	skb = sk->send_head;
+
+	while (skb != NULL)
+	{
+		struct tcphdr *th;
+		struct iphdr *iph;
+		int size;
+
+		dev = skb->dev;
+		IS_SKB(skb);
+		skb->when = jiffies;
+
+		/*
+		 * In general it's OK just to use the old packet.  However we
+		 * need to use the current ack and window fields.  Urg and
+		 * urg_ptr could possibly stand to be updated as well, but we
+		 * don't keep the necessary data.  That shouldn't be a problem,
+		 * if the other end is doing the right thing.  Since we're
+		 * changing the packet, we have to issue a new IP identifier.
+		 */
+
+		iph = (struct iphdr *)(skb->data + dev->hard_header_len);
+		th = (struct tcphdr *)(((char *)iph) + (iph->ihl << 2));
+		size = skb->len - (((unsigned char *) th) - skb->data);
+		
+		/*
+		 *	Note: We ought to check for window limits here but
+		 *	currently this is done (less efficiently) elsewhere.
+		 *	We do need to check for a route change but can't handle
+		 *	that until we have the new 1.3.x buffers in.
+		 *
+		 */
+
+		iph->id = htons(ip_id_count++);
+		ip_send_check(iph);
+
+		/*
+		 *	This is not the right way to handle this. We have to
+		 *	issue an up to date window and ack report with this 
+		 *	retransmit to keep the odd buggy tcp that relies on 
+		 *	the fact BSD does this happy. 
+		 *	We don't however need to recalculate the entire 
+		 *	checksum, so someone wanting a small problem to play
+		 *	with might like to implement RFC1141/RFC1624 and speed
+		 *	this up by avoiding a full checksum.
+		 */
+		 
+		th->ack_seq = ntohl(sk->acked_seq);
+		th->window = ntohs(tcp_select_window(sk));
+		tcp_send_check(th, sk->saddr, sk->daddr, size, sk);
+		
+		/*
+		 *	If the interface is (still) up and running, kick it.
+		 */
+
+		if (dev->flags & IFF_UP)
+		{
+			/*
+			 *	If the packet is still being sent by the device/protocol
+			 *	below then don't retransmit. This is both needed, and good -
+			 *	especially with connected mode AX.25 where it stops resends
+			 *	occurring of an as yet unsent anyway frame!
+			 *	We still add up the counts as the round trip time wants
+			 *	adjusting.
+			 */
+			if (sk && !skb_device_locked(skb))
+			{
+				/* Remove it from any existing driver queue first! */
+				skb_unlink(skb);
+				/* Now queue it */
+				ip_statistics.IpOutRequests++;
+				dev_queue_xmit(skb, dev, sk->priority);
+			}
+		}
+
+		/*
+		 *	Count retransmissions
+		 */
+		 
+		ct++;
+		sk->prot->retransmits ++;
+
+		/*
+		 *	Only one retransmit requested.
+		 */
+	
+		if (!all)
+			break;
+
+		/*
+		 *	This should cut it off before we send too many packets.
+		 */
+
+		if (ct >= sk->cong_window)
+			break;
+		skb = skb->link3;
+	}
+}
+
+/*
+ *	Reset the retransmission timer
+ */
+ 
+static void reset_xmit_timer(struct sock *sk, int why, unsigned long when)
+{
+	del_timer(&sk->retransmit_timer);
+	sk->ip_xmit_timeout = why;
+	if((int)when < 0)
+	{
+		when=3;
+		printk("Error: Negative timer in xmit_timer\n");
+	}
+	sk->retransmit_timer.expires=when;
+	add_timer(&sk->retransmit_timer);
+}
+
+/*
+ * 	This is the normal code called for timeouts.  It does the retransmission
+ * 	and then does backoff.  tcp_do_retransmit is separated out because
+ * 	tcp_ack needs to send stuff from the retransmit queue without
+ * 	initiating a backoff.
+ */
+
+
+void tcp_retransmit_time(struct sock *sk, int all)
+{
+	tcp_do_retransmit(sk, all);
+
+	/*
+	 * Increase the timeout each time we retransmit.  Note that
+	 * we do not increase the rtt estimate.  rto is initialized
+	 * from rtt, but increases here.  Jacobson (SIGCOMM 88) suggests
+	 * that doubling rto each time is the least we can get away with.
+	 * In KA9Q, Karn uses this for the first few times, and then
+	 * goes to quadratic.  netBSD doubles, but only goes up to *64,
+	 * and clamps at 1 to 64 sec afterwards.  Note that 120 sec is
+	 * defined in the protocol as the maximum possible RTT.  I guess
+	 * we'll have to use something other than TCP to talk to the
+	 * University of Mars.
+	 *
+	 * PAWS allows us longer timeouts and large windows, so once
+	 * implemented ftp to mars will work nicely. We will have to fix
+	 * the 120 second clamps though!
+	 */
+
+	sk->retransmits++;
+	sk->backoff++;
+	sk->rto = min(sk->rto << 1, 120*HZ);
+	reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+}
+
+
+/*
+ *	A timer event has trigger a tcp retransmit timeout. The
+ *	socket xmit queue is ready and set up to send. Because
+ *	the ack receive code keeps the queue straight we do
+ *	nothing clever here.
+ */
+
+static void tcp_retransmit(struct sock *sk, int all)
+{
+	if (all) 
+	{
+		tcp_retransmit_time(sk, all);
+		return;
+	}
+
+	sk->ssthresh = sk->cong_window >> 1; /* remember window where we lost */
+	/* sk->ssthresh in theory can be zero.  I guess that's OK */
+	sk->cong_count = 0;
+
+	sk->cong_window = 1;
+
+	/* Do the actual retransmit. */
+	tcp_retransmit_time(sk, all);
+}
+
+/*
+ *	A write timeout has occurred. Process the after effects.
+ */
+
+static int tcp_write_timeout(struct sock *sk)
+{
+	/*
+	 *	Look for a 'soft' timeout.
+	 */
+	if ((sk->state == TCP_ESTABLISHED && sk->retransmits && !(sk->retransmits & 7))
+		|| (sk->state != TCP_ESTABLISHED && sk->retransmits > TCP_RETR1)) 
+	{
+		/*
+		 *	Attempt to recover if arp has changed (unlikely!) or
+		 *	a route has shifted (not supported prior to 1.3).
+		 */
+		arp_destroy (sk->daddr, 0);
+		ip_route_check (sk->daddr);
+	}
+	/*
+	 *	Has it gone just too far ?
+	 */
+	if (sk->retransmits > TCP_RETR2) 
+	{
+		sk->err = ETIMEDOUT;
+		sk->error_report(sk);
+		del_timer(&sk->retransmit_timer);
+		/*
+		 *	Time wait the socket 
+		 */
+		if (sk->state == TCP_FIN_WAIT1 || sk->state == TCP_FIN_WAIT2 || sk->state == TCP_CLOSING ) 
+		{
+			tcp_set_state(sk,TCP_TIME_WAIT);
+			reset_msl_timer (sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
+		}
+		else
+		{
+			/*
+			 *	Clean up time.
+			 */
+			tcp_set_state(sk, TCP_CLOSE);
+			return 0;
+		}
+	}
+	return 1;
+}
+
+/*
+ *	The TCP retransmit timer. This lacks a few small details.
+ *
+ *	1. 	An initial rtt timeout on the probe0 should cause what we can
+ *		of the first write queue buffer to be split and sent.
+ *	2.	On a 'major timeout' as defined by RFC1122 we shouldn't report
+ *		ETIMEDOUT if we know an additional 'soft' error caused this.
+ *		tcp_err should save a 'soft error' for us.
+ */
+
+static void retransmit_timer(unsigned long data)
+{
+	struct sock *sk = (struct sock*)data;
+	int why = sk->ip_xmit_timeout;
+
+	/* 
+	 * only process if socket is not in use
+	 */
+
+	cli();
+	if (sk->inuse || in_bh) 
+	{
+		/* Try again in 1 second */
+		sk->retransmit_timer.expires = HZ;
+		add_timer(&sk->retransmit_timer);
+		sti();
+		return;
+	}
+
+	sk->inuse = 1;
+	sti();
+
+	/* Always see if we need to send an ack. */
+
+	if (sk->ack_backlog && !sk->zapped) 
+	{
+		sk->prot->read_wakeup (sk);
+		if (! sk->dead)
+			sk->data_ready(sk,0);
+	}
+
+	/* Now we need to figure out why the socket was on the timer. */
+
+	switch (why) 
+	{
+		/* Window probing */
+		case TIME_PROBE0:
+			tcp_send_probe0(sk);
+			tcp_write_timeout(sk);
+			break;
+		/* Retransmitting */
+		case TIME_WRITE:
+			/* It could be we got here because we needed to send an ack.
+			 * So we need to check for that.
+			 */
+		{
+			struct sk_buff *skb;
+			unsigned long flags;
+
+			save_flags(flags);
+			cli();
+			skb = sk->send_head;
+			if (!skb) 
+			{
+				restore_flags(flags);
+			} 
+			else 
+			{
+				/*
+				 *	Kicked by a delayed ack. Reset timer
+				 *	correctly now
+				 */
+				if (jiffies < skb->when + sk->rto) 
+				{
+					reset_xmit_timer (sk, TIME_WRITE, skb->when + sk->rto - jiffies);
+					restore_flags(flags);
+					break;
+				}
+				restore_flags(flags);
+				/*
+				 *	Retransmission
+				 */
+				sk->prot->retransmit (sk, 0);
+				tcp_write_timeout(sk);
+			}
+			break;
+		}
+		/* Sending Keepalives */
+		case TIME_KEEPOPEN:
+			/* 
+			 * this reset_timer() call is a hack, this is not
+			 * how KEEPOPEN is supposed to work.
+			 */
+			reset_xmit_timer (sk, TIME_KEEPOPEN, TCP_TIMEOUT_LEN);
+
+			/* Send something to keep the connection open. */
+			if (sk->prot->write_wakeup)
+				  sk->prot->write_wakeup (sk);
+			sk->retransmits++;
+			tcp_write_timeout(sk);
+			break;
+		default:
+			printk ("rexmit_timer: timer expired - reason unknown\n");
+			break;
+	}
+	release_sock(sk);
+}
+
+/*
+ * This routine is called by the ICMP module when it gets some
+ * sort of error condition.  If err < 0 then the socket should
+ * be closed and the error returned to the user.  If err > 0
+ * it's just the icmp type << 8 | icmp code.  After adjustment
+ * header points to the first 8 bytes of the tcp header.  We need
+ * to find the appropriate port.
+ */
+
+void tcp_err(int err, unsigned char *header, unsigned long daddr,
+	unsigned long saddr, struct inet_protocol *protocol)
+{
+	struct tcphdr *th;
+	struct sock *sk;
+	struct iphdr *iph=(struct iphdr *)header;
+  
+	header+=4*iph->ihl;
+   
+
+	th =(struct tcphdr *)header;
+	sk = get_sock(&tcp_prot, th->source, daddr, th->dest, saddr);
+
+	if (sk == NULL) 
+		return;
+  
+	if(err<0)
+	{
+	  	sk->err = -err;
+	  	sk->error_report(sk);
+	  	return;
+	}
+
+	if ((err & 0xff00) == (ICMP_SOURCE_QUENCH << 8)) 
+	{
+		/*
+		 * FIXME:
+		 * For now we will just trigger a linear backoff.
+		 * The slow start code should cause a real backoff here.
+		 */
+		if (sk->cong_window > 4)
+			sk->cong_window--;
+		return;
+	}
+
+/*	sk->err = icmp_err_convert[err & 0xff].errno;  -- moved as TCP should hide non fatals internally (and does) */
+
+	/*
+	 * If we've already connected we will keep trying
+	 * until we time out, or the user gives up.
+	 */
+
+	if (icmp_err_convert[err & 0xff].fatal || sk->state == TCP_SYN_SENT) 
+	{
+		if (sk->state == TCP_SYN_SENT) 
+		{
+			tcp_statistics.TcpAttemptFails++;
+			tcp_set_state(sk,TCP_CLOSE);
+			sk->error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */
+		}
+		sk->err = icmp_err_convert[err & 0xff].errno;		
+	}
+	return;
+}
+
+
+/*
+ *	Walk down the receive queue counting readable data until we hit the end or we find a gap
+ *	in the received data queue (ie a frame missing that needs sending to us). Not
+ *	sorting using two queues as data arrives makes life so much harder.
+ */
+
+static int tcp_readable(struct sock *sk)
+{
+	unsigned long counted;
+	unsigned long amount;
+	struct sk_buff *skb;
+	int sum;
+	unsigned long flags;
+
+	if(sk && sk->debug)
+	  	printk("tcp_readable: %p - ",sk);
+
+	save_flags(flags);
+	cli();
+	if (sk == NULL || (skb = skb_peek(&sk->receive_queue)) == NULL)
+	{
+		restore_flags(flags);
+	  	if(sk && sk->debug) 
+	  		printk("empty\n");
+	  	return(0);
+	}
+  
+	counted = sk->copied_seq;	/* Where we are at the moment */
+	amount = 0;
+  
+	/* 
+	 *	Do until a push or until we are out of data. 
+	 */
+	 
+	do 
+	{
+		if (before(counted, skb->h.th->seq)) 	/* Found a hole so stops here */
+			break;
+		sum = skb->len -(counted - skb->h.th->seq);	/* Length - header but start from where we are up to (avoid overlaps) */
+		if (skb->h.th->syn)
+			sum++;
+		if (sum > 0) 
+		{					/* Add it up, move on */
+			amount += sum;
+			if (skb->h.th->syn) 
+				amount--;
+			counted += sum;
+		}
+		/*
+		 * Don't count urg data ... but do it in the right place!
+		 * Consider: "old_data (ptr is here) URG PUSH data"
+		 * The old code would stop at the first push because
+		 * it counted the urg (amount==1) and then does amount--
+		 * *after* the loop.  This means tcp_readable() always
+		 * returned zero if any URG PUSH was in the queue, even
+		 * though there was normal data available. If we subtract
+		 * the urg data right here, we even get it to work for more
+		 * than one URG PUSH skb without normal data.
+		 * This means that select() finally works now with urg data
+		 * in the queue.  Note that rlogin was never affected
+		 * because it doesn't use select(); it uses two processes
+		 * and a blocking read().  And the queue scan in tcp_read()
+		 * was correct.  Mike <pall@rz.uni-karlsruhe.de>
+		 */
+		if (skb->h.th->urg)
+			amount--;	/* don't count urg data */
+		if (amount && skb->h.th->psh) break;
+		skb = skb->next;
+	}
+	while(skb != (struct sk_buff *)&sk->receive_queue);
+
+	restore_flags(flags);
+	if(sk->debug)
+	  	printk("got %lu bytes.\n",amount);
+	return(amount);
+}
+
+/*
+ * LISTEN is a special case for select..
+ */
+static int tcp_listen_select(struct sock *sk, int sel_type, select_table *wait)
+{
+	if (sel_type == SEL_IN) {
+		int retval;
+
+		sk->inuse = 1;
+		retval = (tcp_find_established(sk) != NULL);
+		release_sock(sk);
+		if (!retval)
+			select_wait(&master_select_wakeup,wait);
+		return retval;
+	}
+	return 0;
+}
+
+
+/*
+ *	Wait for a TCP event.
+ *
+ *	Note that we don't need to set "sk->inuse", as the upper select layers
+ *	take care of normal races (between the test and the event) and we don't
+ *	go look at any of the socket buffers directly.
+ */
+static int tcp_select(struct sock *sk, int sel_type, select_table *wait)
+{
+	if (sk->state == TCP_LISTEN)
+		return tcp_listen_select(sk, sel_type, wait);
+
+	switch(sel_type) {
+	case SEL_IN:
+		if (sk->err)
+			return 1;
+		if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
+			break;
+
+		if (sk->shutdown & RCV_SHUTDOWN)
+			return 1;
+			
+		if (sk->acked_seq == sk->copied_seq)
+			break;
+
+		if (sk->urg_seq != sk->copied_seq ||
+		    sk->acked_seq != sk->copied_seq+1 ||
+		    sk->urginline || !sk->urg_data)
+			return 1;
+		break;
+
+	case SEL_OUT:
+		if (sk->shutdown & SEND_SHUTDOWN) 
+			return 0;
+		if (sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
+			break;
+		/*
+		 * This is now right thanks to a small fix
+		 * by Matt Dillon.
+		 */
+
+		if (sk->prot->wspace(sk) < sk->mtu+128+sk->prot->max_header)
+			break;
+		return 1;
+
+	case SEL_EX:
+		if (sk->err || sk->urg_data)
+			return 1;
+		break;
+	}
+	select_wait(sk->sleep, wait);
+	return 0;
+}
+
+int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
+{
+	int err;
+	switch(cmd) 
+	{
+
+		case TIOCINQ:
+#ifdef FIXME	/* FIXME: */
+		case FIONREAD:
+#endif
+		{
+			unsigned long amount;
+
+			if (sk->state == TCP_LISTEN) 
+				return(-EINVAL);
+
+			sk->inuse = 1;
+			amount = tcp_readable(sk);
+			release_sock(sk);
+			err=verify_area(VERIFY_WRITE,(void *)arg,
+						   sizeof(unsigned long));
+			if(err)
+				return err;
+			put_fs_long(amount,(unsigned long *)arg);
+			return(0);
+		}
+		case SIOCATMARK:
+		{
+			int answ = sk->urg_data && sk->urg_seq == sk->copied_seq;
+
+			err = verify_area(VERIFY_WRITE,(void *) arg,
+						  sizeof(unsigned long));
+			if (err)
+				return err;
+			put_fs_long(answ,(int *) arg);
+			return(0);
+		}
+		case TIOCOUTQ:
+		{
+			unsigned long amount;
+
+			if (sk->state == TCP_LISTEN) return(-EINVAL);
+			amount = sk->prot->wspace(sk);
+			err=verify_area(VERIFY_WRITE,(void *)arg,
+						   sizeof(unsigned long));
+			if(err)
+				return err;
+			put_fs_long(amount,(unsigned long *)arg);
+			return(0);
+		}
+		default:
+			return(-EINVAL);
+	}
+}
+
+
+/*
+ *	This routine computes a TCP checksum. 
+ */
+ 
+unsigned short tcp_check(struct tcphdr *th, int len,
+	  unsigned long saddr, unsigned long daddr)
+{     
+	unsigned long sum;
+   
+	if (saddr == 0) saddr = ip_my_addr();
+
+/*
+ * stupid, gcc complains when I use just one __asm__ block,
+ * something about too many reloads, but this is just two
+ * instructions longer than what I want
+ */
+	__asm__("
+	    addl %%ecx, %%ebx
+	    adcl %%edx, %%ebx
+	    adcl $0, %%ebx
+	    "
+	: "=b"(sum)
+	: "0"(daddr), "c"(saddr), "d"((ntohs(len) << 16) + IPPROTO_TCP*256)
+	: "bx", "cx", "dx" );
+	__asm__("
+	    movl %%ecx, %%edx
+	    cld
+	    cmpl $32, %%ecx
+	    jb 2f
+	    shrl $5, %%ecx
+	    clc
+1:	    lodsl
+	    adcl %%eax, %%ebx
+	    lodsl
+	    adcl %%eax, %%ebx
+	    lodsl
+	    adcl %%eax, %%ebx
+	    lodsl
+	    adcl %%eax, %%ebx
+	    lodsl
+	    adcl %%eax, %%ebx
+	    lodsl
+	    adcl %%eax, %%ebx
+	    lodsl
+	    adcl %%eax, %%ebx
+	    lodsl
+	    adcl %%eax, %%ebx
+	    loop 1b
+	    adcl $0, %%ebx
+	    movl %%edx, %%ecx
+2:	    andl $28, %%ecx
+	    je 4f
+	    shrl $2, %%ecx
+	    clc
+3:	    lodsl
+	    adcl %%eax, %%ebx
+	    loop 3b
+	    adcl $0, %%ebx
+4:	    movl $0, %%eax
+	    testw $2, %%dx
+	    je 5f
+	    lodsw
+	    addl %%eax, %%ebx
+	    adcl $0, %%ebx
+	    movw $0, %%ax
+5:	    test $1, %%edx
+	    je 6f
+	    lodsb
+	    addl %%eax, %%ebx
+	    adcl $0, %%ebx
+6:	    movl %%ebx, %%eax
+	    shrl $16, %%eax
+	    addw %%ax, %%bx
+	    adcw $0, %%bx
+	    "
+	: "=b"(sum)
+	: "0"(sum), "c"(len), "S"(th)
+	: "ax", "bx", "cx", "dx", "si" );
+
+  	/* We only want the bottom 16 bits, but we never cleared the top 16. */
+  
+  	return((~sum) & 0xffff);
+}
+
+
+
+void tcp_send_check(struct tcphdr *th, unsigned long saddr, 
+		unsigned long daddr, int len, struct sock *sk)
+{
+	th->check = 0;
+	th->check = tcp_check(th, len, saddr, daddr);
+	return;
+}
+
+/*
+ *	This is the main buffer sending routine. We queue the buffer
+ *	having checked it is sane seeming.
+ */
+ 
+static void tcp_send_skb(struct sock *sk, struct sk_buff *skb)
+{
+	int size;
+	struct tcphdr * th = skb->h.th;
+
+	/*
+	 *	length of packet (not counting length of pre-tcp headers) 
+	 */
+	 
+	size = skb->len - ((unsigned char *) th - skb->data);
+
+	/*
+	 *	Sanity check it.. 
+	 */
+	 
+	if (size < sizeof(struct tcphdr) || size > skb->len) 
+	{
+		printk("tcp_send_skb: bad skb (skb = %p, data = %p, th = %p, len = %lu)\n",
+			skb, skb->data, th, skb->len);
+		kfree_skb(skb, FREE_WRITE);
+		return;
+	}
+
+	/*
+	 *	If we have queued a header size packet.. (these crash a few
+	 *	tcp stacks if ack is not set)
+	 */
+	 
+	if (size == sizeof(struct tcphdr)) 
+	{
+		/* If it's got a syn or fin it's notionally included in the size..*/
+		if(!th->syn && !th->fin) 
+		{
+			printk("tcp_send_skb: attempt to queue a bogon.\n");
+			kfree_skb(skb,FREE_WRITE);
+			return;
+		}
+	}
+
+	/*
+	 *	Actual processing.
+	 */
+	 
+	tcp_statistics.TcpOutSegs++;  
+	skb->h.seq = ntohl(th->seq) + size - 4*th->doff;
+	
+	/*
+	 *	We must queue if
+	 *
+	 *	a) The right edge of this frame exceeds the window
+	 *	b) We are retransmitting (Nagle's rule)
+	 *	c) We have too many packets 'in flight'
+	 */
+	 
+	if (after(skb->h.seq, sk->window_seq) ||
+	    (sk->retransmits && sk->ip_xmit_timeout == TIME_WRITE) ||
+	     sk->packets_out >= sk->cong_window) 
+	{
+		/* checksum will be supplied by tcp_write_xmit.  So
+		 * we shouldn't need to set it at all.  I'm being paranoid */
+		th->check = 0;
+		if (skb->next != NULL) 
+		{
+			printk("tcp_send_partial: next != NULL\n");
+			skb_unlink(skb);
+		}
+		skb_queue_tail(&sk->write_queue, skb);
+		
+		/*
+		 *	If we don't fit we have to start the zero window
+		 *	probes. This is broken - we really need to do a partial
+		 *	send _first_ (This is what causes the Cisco and PC/TCP
+		 *	grief).
+		 */
+		 
+		if (before(sk->window_seq, sk->write_queue.next->h.seq) &&
+		    sk->send_head == NULL && sk->ack_backlog == 0)
+			reset_xmit_timer(sk, TIME_PROBE0, sk->rto);
+	} 
+	else 
+	{
+		/*
+		 *	This is going straight out
+		 */
+		 
+		th->ack_seq = ntohl(sk->acked_seq);
+		th->window = ntohs(tcp_select_window(sk));
+
+		tcp_send_check(th, sk->saddr, sk->daddr, size, sk);
+
+		sk->sent_seq = sk->write_seq;
+		
+		/*
+		 *	This is mad. The tcp retransmit queue is put together
+		 *	by the ip layer. This causes half the problems with
+		 *	unroutable FIN's and other things.
+		 */
+		 
+		sk->prot->queue_xmit(sk, skb->dev, skb, 0);
+		
+		/*
+		 *	Set for next retransmit based on expected ACK time.
+		 *	FIXME: We set this every time which means our 
+		 *	retransmits are really about a window behind.
+		 */
+
+		reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+	}
+}
+
+/*
+ *	Locking problems lead us to a messy situation where we can have
+ *	multiple partially complete buffers queued up. This is really bad
+ *	as we don't want to be sending partial buffers. Fix this with
+ *	a semaphore or similar to lock tcp_write per socket.
+ *
+ *	These routines are pretty self descriptive.
+ */
+ 
+struct sk_buff * tcp_dequeue_partial(struct sock * sk)
+{
+	struct sk_buff * skb;
+	unsigned long flags;
+
+	save_flags(flags);
+	cli();
+	skb = sk->partial;
+	if (skb) {
+		sk->partial = NULL;
+		del_timer(&sk->partial_timer);
+	}
+	restore_flags(flags);
+	return skb;
+}
+
+/*
+ *	Empty the partial queue
+ */
+ 
+static void tcp_send_partial(struct sock *sk)
+{
+	struct sk_buff *skb;
+
+	if (sk == NULL)
+		return;
+	while ((skb = tcp_dequeue_partial(sk)) != NULL)
+		tcp_send_skb(sk, skb);
+}
+
+/*
+ *	Queue a partial frame
+ */
+ 
+void tcp_enqueue_partial(struct sk_buff * skb, struct sock * sk)
+{
+	struct sk_buff * tmp;
+	unsigned long flags;
+
+	save_flags(flags);
+	cli();
+	tmp = sk->partial;
+	if (tmp)
+		del_timer(&sk->partial_timer);
+	sk->partial = skb;
+	init_timer(&sk->partial_timer);
+	/*
+	 *	Wait up to 1 second for the buffer to fill.
+	 */
+	sk->partial_timer.expires = HZ;
+	sk->partial_timer.function = (void (*)(unsigned long)) tcp_send_partial;
+	sk->partial_timer.data = (unsigned long) sk;
+	add_timer(&sk->partial_timer);
+	restore_flags(flags);
+	if (tmp)
+		tcp_send_skb(sk, tmp);
+}
+
+
+/*
+ *	This routine sends an ack and also updates the window. 
+ */
+ 
+static void tcp_send_ack(unsigned long sequence, unsigned long ack,
+	     struct sock *sk,
+	     struct tcphdr *th, unsigned long daddr)
+{
+	struct sk_buff *buff;
+	struct tcphdr *t1;
+	struct device *dev = NULL;
+	int tmp;
+
+	if(sk->zapped)
+		return;		/* We have been reset, we may not send again */
+		
+	/*
+	 * We need to grab some memory, and put together an ack,
+	 * and then put it into the queue to be sent.
+	 */
+
+	buff = sk->prot->wmalloc(sk, MAX_ACK_SIZE, 1, GFP_ATOMIC);
+	if (buff == NULL) 
+	{
+		/* 
+		 *	Force it to send an ack. We don't have to do this
+		 *	(ACK is unreliable) but it's much better use of 
+		 *	bandwidth on slow links to send a spare ack than
+		 *	resend packets. 
+		 */
+		 
+		sk->ack_backlog++;
+		if (sk->ip_xmit_timeout != TIME_WRITE && tcp_connected(sk->state)) 
+		{
+			reset_xmit_timer(sk, TIME_WRITE, HZ);
+		}
+		return;
+	}
+
+	/*
+	 *	Assemble a suitable TCP frame
+	 */
+	 
+	buff->len = sizeof(struct tcphdr);
+	buff->sk = sk;
+	buff->localroute = sk->localroute;
+	t1 =(struct tcphdr *) buff->data;
+
+	/* 
+	 *	Put in the IP header and routing stuff. 
+	 */
+	 
+	tmp = sk->prot->build_header(buff, sk->saddr, daddr, &dev,
+				IPPROTO_TCP, sk->opt, MAX_ACK_SIZE,sk->ip_tos,sk->ip_ttl);
+	if (tmp < 0) 
+	{
+  		buff->free = 1;
+		sk->prot->wfree(sk, buff->mem_addr, buff->mem_len);
+		return;
+	}
+	buff->len += tmp;
+	t1 =(struct tcphdr *)((char *)t1 +tmp);
+
+	memcpy(t1, th, sizeof(*t1));
+
+	/*
+	 *	Swap the send and the receive. 
+	 */
+	 
+	t1->dest = th->source;
+	t1->source = th->dest;
+	t1->seq = ntohl(sequence);
+	t1->ack = 1;
+	sk->window = tcp_select_window(sk);
+	t1->window = ntohs(sk->window);
+	t1->res1 = 0;
+	t1->res2 = 0;
+	t1->rst = 0;
+	t1->urg = 0;
+	t1->syn = 0;
+	t1->psh = 0;
+	t1->fin = 0;
+	
+	/*
+	 *	If we have nothing queued for transmit and the transmit timer
+	 *	is on we are just doing an ACK timeout and need to switch
+	 *	to a keepalive.
+	 */
+	 
+	if (ack == sk->acked_seq) 
+	{
+		sk->ack_backlog = 0;
+		sk->bytes_rcv = 0;
+		sk->ack_timed = 0;
+		if (sk->send_head == NULL && skb_peek(&sk->write_queue) == NULL
+				  && sk->ip_xmit_timeout == TIME_WRITE) 
+		{
+			if(sk->keepopen) {
+				reset_xmit_timer(sk,TIME_KEEPOPEN,TCP_TIMEOUT_LEN);
+			} else {
+				delete_timer(sk);
+			}
+		}
+  	}
+  	
+  	/*
+  	 *	Fill in the packet and send it
+  	 */
+  	 
+  	t1->ack_seq = ntohl(ack);
+  	t1->doff = sizeof(*t1)/4;
+  	tcp_send_check(t1, sk->saddr, daddr, sizeof(*t1), sk);
+  	if (sk->debug)
+  		 printk("\rtcp_ack: seq %lx ack %lx\n", sequence, ack);
+  	tcp_statistics.TcpOutSegs++;
+  	sk->prot->queue_xmit(sk, dev, buff, 1);
+}
+
+
+/* 
+ *	This routine builds a generic TCP header. 
+ */
+ 
+extern __inline int tcp_build_header(struct tcphdr *th, struct sock *sk, int push)
+{
+
+	memcpy(th,(void *) &(sk->dummy_th), sizeof(*th));
+	th->seq = htonl(sk->write_seq);
+	th->psh =(push == 0) ? 1 : 0;
+	th->doff = sizeof(*th)/4;
+	th->ack = 1;
+	th->fin = 0;
+	sk->ack_backlog = 0;
+	sk->bytes_rcv = 0;
+	sk->ack_timed = 0;
+	th->ack_seq = htonl(sk->acked_seq);
+	sk->window = tcp_select_window(sk);
+	th->window = htons(sk->window);
+
+	return(sizeof(*th));
+}
+
+/*
+ *	This routine copies from a user buffer into a socket,
+ *	and starts the transmit system.
+ */
+
+static int tcp_write(struct sock *sk, unsigned char *from,
+	  int len, int nonblock, unsigned flags)
+{
+	int copied = 0;
+	int copy;
+	int tmp;
+	struct sk_buff *skb;
+	struct sk_buff *send_tmp;
+	unsigned char *buff;
+	struct proto *prot;
+	struct device *dev = NULL;
+
+	sk->inuse=1;
+	prot = sk->prot;
+	while(len > 0) 
+	{
+		if (sk->err) 
+		{			/* Stop on an error */
+			release_sock(sk);
+			if (copied) 
+				return(copied);
+			tmp = -sk->err;
+			sk->err = 0;
+			return(tmp);
+		}
+
+		/*
+		 *	First thing we do is make sure that we are established. 
+		 */
+	
+		if (sk->shutdown & SEND_SHUTDOWN) 
+		{
+			release_sock(sk);
+			sk->err = EPIPE;
+			if (copied) 
+				return(copied);
+			sk->err = 0;
+			return(-EPIPE);
+		}
+
+		/* 
+		 *	Wait for a connection to finish.
+		 */
+	
+		while(sk->state != TCP_ESTABLISHED && sk->state != TCP_CLOSE_WAIT) 
+		{
+			if (sk->err) 
+			{
+				release_sock(sk);
+				if (copied) 
+					return(copied);
+				tmp = -sk->err;
+				sk->err = 0;
+				return(tmp);
+			}
+
+			if (sk->state != TCP_SYN_SENT && sk->state != TCP_SYN_RECV) 
+			{
+				release_sock(sk);
+				if (copied) 
+					return(copied);
+
+				if (sk->err) 
+				{
+					tmp = -sk->err;
+					sk->err = 0;
+					return(tmp);
+				}
+
+				if (sk->keepopen) 
+				{
+					send_sig(SIGPIPE, current, 0);
+				}
+				return(-EPIPE);
+			}
+
+			if (nonblock || copied) 
+			{
+				release_sock(sk);
+				if (copied) 
+					return(copied);
+				return(-EAGAIN);
+			}
+
+			release_sock(sk);
+			cli();
+		
+			if (sk->state != TCP_ESTABLISHED &&
+		    		sk->state != TCP_CLOSE_WAIT && sk->err == 0) 
+		    	{
+				interruptible_sleep_on(sk->sleep);
+				if (current->signal & ~current->blocked) 
+				{
+					sti();
+					if (copied) 
+						return(copied);
+					return(-ERESTARTSYS);
+				}
+			}
+			sk->inuse = 1;
+			sti();
+		}
+
+	/*
+	 * The following code can result in copy <= if sk->mss is ever
+	 * decreased.  It shouldn't be.  sk->mss is min(sk->mtu, sk->max_window).
+	 * sk->mtu is constant once SYN processing is finished.  I.e. we
+	 * had better not get here until we've seen his SYN and at least one
+	 * valid ack.  (The SYN sets sk->mtu and the ack sets sk->max_window.)
+	 * But ESTABLISHED should guarantee that.  sk->max_window is by definition
+	 * non-decreasing.  Note that any ioctl to set user_mss must be done
+	 * before the exchange of SYN's.  If the initial ack from the other
+	 * end has a window of 0, max_window and thus mss will both be 0.
+	 */
+
+	/* 
+	 *	Now we need to check if we have a half built packet. 
+	 */
+
+		if ((skb = tcp_dequeue_partial(sk)) != NULL) 
+		{
+		        int hdrlen;
+
+		         /* IP header + TCP header */
+			hdrlen = ((unsigned long)skb->h.th - (unsigned long)skb->data)
+			         + sizeof(struct tcphdr);
+	
+			/* Add more stuff to the end of skb->len */
+			if (!(flags & MSG_OOB)) 
+			{
+				copy = min(sk->mss - (skb->len - hdrlen), len);
+				/* FIXME: this is really a bug. */
+				if (copy <= 0) 
+				{
+			  		printk("TCP: **bug**: \"copy\" <= 0!!\n");
+			  		copy = 0;
+				}
+	  
+				memcpy_fromfs(skb->data + skb->len, from, copy);
+				skb->len += copy;
+				from += copy;
+				copied += copy;
+				len -= copy;
+				sk->write_seq += copy;
+			}
+			if ((skb->len - hdrlen) >= sk->mss ||
+				(flags & MSG_OOB) || !sk->packets_out)
+				tcp_send_skb(sk, skb);
+			else
+				tcp_enqueue_partial(skb, sk);
+			continue;
+		}
+
+	/*
+	 * We also need to worry about the window.
+ 	 * If window < 1/2 the maximum window we've seen from this
+ 	 *   host, don't use it.  This is sender side
+ 	 *   silly window prevention, as specified in RFC1122.
+ 	 *   (Note that this is different than earlier versions of
+ 	 *   SWS prevention, e.g. RFC813.).  What we actually do is 
+	 *   use the whole MSS.  Since the results in the right
+	 *   edge of the packet being outside the window, it will
+	 *   be queued for later rather than sent.
+	 */
+
+		copy = sk->window_seq - sk->write_seq;
+		if (copy <= 0 || copy < (sk->max_window >> 1) || copy > sk->mss)
+			copy = sk->mss;
+		if (copy > len)
+			copy = len;
+
+	/*
+	 *	We should really check the window here also. 
+	 */
+	 
+		send_tmp = NULL;
+		if (copy < sk->mss && !(flags & MSG_OOB)) 
+		{
+			/*
+			 *	We will release the socket in case we sleep here. 
+			 */
+			release_sock(sk);
+			/*
+			 *	NB: following must be mtu, because mss can be increased.
+			 *	mss is always <= mtu 
+			 */
+			skb = prot->wmalloc(sk, sk->mtu + 128 + prot->max_header, 0, GFP_KERNEL);
+			sk->inuse = 1;
+			send_tmp = skb;
+		} 
+		else 
+		{
+			/*
+			 *	We will release the socket in case we sleep here. 
+			 */
+			release_sock(sk);
+			skb = prot->wmalloc(sk, copy + prot->max_header , 0, GFP_KERNEL);
+  			sk->inuse = 1;
+		}
+
+		/*
+		 *	If we didn't get any memory, we need to sleep. 
+		 */
+
+		if (skb == NULL) 
+		{
+			sk->socket->flags |= SO_NOSPACE;
+			if (nonblock) 
+			{
+				release_sock(sk);
+				if (copied) 
+					return(copied);
+				return(-EAGAIN);
+			}
+
+			/*
+			 *	FIXME: here is another race condition. 
+			 */
+
+			tmp = sk->wmem_alloc;
+			release_sock(sk);
+			cli();
+			/*
+			 *	Again we will try to avoid it. 
+			 */
+			if (tmp <= sk->wmem_alloc &&
+				  (sk->state == TCP_ESTABLISHED||sk->state == TCP_CLOSE_WAIT)
+				&& sk->err == 0) 
+			{
+				sk->socket->flags &= ~SO_NOSPACE;
+				interruptible_sleep_on(sk->sleep);
+				if (current->signal & ~current->blocked) 
+				{
+					sti();
+					if (copied) 
+						return(copied);
+					return(-ERESTARTSYS);
+				}
+			}
+			sk->inuse = 1;
+			sti();
+			continue;
+		}
+
+		skb->len = 0;
+		skb->sk = sk;
+		skb->free = 0;
+		skb->localroute = sk->localroute|(flags&MSG_DONTROUTE);
+	
+		buff = skb->data;
+	
+		/*
+		 * FIXME: we need to optimize this.
+		 * Perhaps some hints here would be good.
+		 */
+		
+		tmp = prot->build_header(skb, sk->saddr, sk->daddr, &dev,
+				 IPPROTO_TCP, sk->opt, skb->mem_len,sk->ip_tos,sk->ip_ttl);
+		if (tmp < 0 ) 
+		{
+			prot->wfree(sk, skb->mem_addr, skb->mem_len);
+			release_sock(sk);
+			if (copied) 
+				return(copied);
+			return(tmp);
+		}
+		skb->len += tmp;
+		skb->dev = dev;
+		buff += tmp;
+		skb->h.th =(struct tcphdr *) buff;
+		tmp = tcp_build_header((struct tcphdr *)buff, sk, len-copy);
+		if (tmp < 0) 
+		{
+			prot->wfree(sk, skb->mem_addr, skb->mem_len);
+			release_sock(sk);
+			if (copied) 
+				return(copied);
+			return(tmp);
+		}
+
+		if (flags & MSG_OOB) 
+		{
+			((struct tcphdr *)buff)->urg = 1;
+			((struct tcphdr *)buff)->urg_ptr = ntohs(copy);
+		}
+		skb->len += tmp;
+		memcpy_fromfs(buff+tmp, from, copy);
+
+		from += copy;
+		copied += copy;
+		len -= copy;
+		skb->len += copy;
+		skb->free = 0;
+		sk->write_seq += copy;
+	
+		if (send_tmp != NULL && sk->packets_out) 
+		{
+			tcp_enqueue_partial(send_tmp, sk);
+			continue;
+		}
+		tcp_send_skb(sk, skb);
+	}
+	sk->err = 0;
+
+/*
+ *	Nagle's rule. Turn Nagle off with TCP_NODELAY for highly
+ *	interactive fast network servers. It's meant to be on and
+ *	it really improves the throughput though not the echo time
+ *	on my slow slip link - Alan
+ */
+
+/*
+ *	Avoid possible race on send_tmp - c/o Johannes Stille 
+ */
+ 
+	if(sk->partial && ((!sk->packets_out) 
+     /* If not nagling we can send on the before case too.. */
+	      || (sk->nonagle && before(sk->write_seq , sk->window_seq))
+      	))
+  		tcp_send_partial(sk);
+
+	release_sock(sk);
+	return(copied);
+}
+
+/*
+ *	This is just a wrapper. 
+ */
+
+static int tcp_sendto(struct sock *sk, unsigned char *from,
+	   int len, int nonblock, unsigned flags,
+	   struct sockaddr_in *addr, int addr_len)
+{
+	if (flags & ~(MSG_OOB|MSG_DONTROUTE))
+		return -EINVAL;
+	if (sk->state == TCP_CLOSE)
+		return -ENOTCONN;
+	if (addr_len < sizeof(*addr))
+		return -EINVAL;
+	if (addr->sin_family && addr->sin_family != AF_INET) 
+		return -EINVAL;
+	if (addr->sin_port != sk->dummy_th.dest) 
+		return -EISCONN;
+	if (addr->sin_addr.s_addr != sk->daddr) 
+		return -EISCONN;
+	return tcp_write(sk, from, len, nonblock, flags);
+}
+
+
+/*
+ *	Send an ack if one is backlogged at this point. Ought to merge
+ *	this with tcp_send_ack().
+ */
+ 
+static void tcp_read_wakeup(struct sock *sk)
+{
+	int tmp;
+	struct device *dev = NULL;
+	struct tcphdr *t1;
+	struct sk_buff *buff;
+
+	if (!sk->ack_backlog) 
+		return;
+
+	/*
+	 * FIXME: we need to put code here to prevent this routine from
+	 * being called.  Being called once in a while is ok, so only check
+	 * if this is the second time in a row.
+ 	 */
+
+	/*
+	 * We need to grab some memory, and put together an ack,
+	 * and then put it into the queue to be sent.
+	 */
+
+	buff = sk->prot->wmalloc(sk,MAX_ACK_SIZE,1, GFP_ATOMIC);
+	if (buff == NULL) 
+	{
+		/* Try again real soon. */
+		reset_xmit_timer(sk, TIME_WRITE, HZ);
+		return;
+ 	}
+
+	buff->len = sizeof(struct tcphdr);
+	buff->sk = sk;
+	buff->localroute = sk->localroute;
+	
+	/*
+	 *	Put in the IP header and routing stuff. 
+	 */
+
+	tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
+			       IPPROTO_TCP, sk->opt, MAX_ACK_SIZE,sk->ip_tos,sk->ip_ttl);
+	if (tmp < 0) 
+	{
+  		buff->free = 1;
+		sk->prot->wfree(sk, buff->mem_addr, buff->mem_len);
+		return;
+	}
+
+	buff->len += tmp;
+	t1 =(struct tcphdr *)(buff->data +tmp);
+
+	memcpy(t1,(void *) &sk->dummy_th, sizeof(*t1));
+	t1->seq = htonl(sk->sent_seq);
+	t1->ack = 1;
+	t1->res1 = 0;
+	t1->res2 = 0;
+	t1->rst = 0;
+	t1->urg = 0;
+	t1->syn = 0;
+	t1->psh = 0;
+	sk->ack_backlog = 0;
+	sk->bytes_rcv = 0;
+	sk->window = tcp_select_window(sk);
+	t1->window = ntohs(sk->window);
+	t1->ack_seq = ntohl(sk->acked_seq);
+	t1->doff = sizeof(*t1)/4;
+	tcp_send_check(t1, sk->saddr, sk->daddr, sizeof(*t1), sk);
+	sk->prot->queue_xmit(sk, dev, buff, 1);
+	tcp_statistics.TcpOutSegs++;
+}
+
+
+/*
+ * 	FIXME:
+ * 	This routine frees used buffers.
+ * 	It should consider sending an ACK to let the
+ * 	other end know we now have a bigger window.
+ */
+
+static void cleanup_rbuf(struct sock *sk)
+{
+	unsigned long flags;
+	unsigned long left;
+	struct sk_buff *skb;
+	unsigned long rspace;
+
+	if(sk->debug)
+	  	printk("cleaning rbuf for sk=%p\n", sk);
+  
+	save_flags(flags);
+	cli();
+  
+	left = sk->prot->rspace(sk);
+ 
+	/*
+	 *	We have to loop through all the buffer headers,
+	 *	and try to free up all the space we can.
+	 */
+
+	while((skb=skb_peek(&sk->receive_queue)) != NULL) 
+	{
+		if (!skb->used || skb->users) 
+			break;
+		skb_unlink(skb);
+		skb->sk = sk;
+		kfree_skb(skb, FREE_READ);
+	}
+
+	restore_flags(flags);
+
+	/*
+	 *	FIXME:
+	 *	At this point we should send an ack if the difference
+	 *	in the window, and the amount of space is bigger than
+	 *	TCP_WINDOW_DIFF.
+	 */
+
+	if(sk->debug)
+		printk("sk->rspace = %lu, was %lu\n", sk->prot->rspace(sk),
+  					    left);
+	if ((rspace=sk->prot->rspace(sk)) != left) 
+	{
+		/*
+		 * This area has caused the most trouble.  The current strategy
+		 * is to simply do nothing if the other end has room to send at
+		 * least 3 full packets, because the ack from those will auto-
+		 * matically update the window.  If the other end doesn't think
+		 * we have much space left, but we have room for at least 1 more
+		 * complete packet than it thinks we do, we will send an ack
+		 * immediately.  Otherwise we will wait up to .5 seconds in case
+		 * the user reads some more.
+		 */
+		sk->ack_backlog++;
+	/*
+	 * It's unclear whether to use sk->mtu or sk->mss here.  They differ only
+	 * if the other end is offering a window smaller than the agreed on MSS
+	 * (called sk->mtu here).  In theory there's no connection between send
+	 * and receive, and so no reason to think that they're going to send
+	 * small packets.  For the moment I'm using the hack of reducing the mss
+	 * only on the send side, so I'm putting mtu here.
+	 */
+
+		if (rspace > (sk->window - sk->bytes_rcv + sk->mtu)) 
+		{
+			/* Send an ack right now. */
+			tcp_read_wakeup(sk);
+		} 
+		else 
+		{
+			/* Force it to send an ack soon. */
+			int was_active = del_timer(&sk->retransmit_timer);
+			if (!was_active || TCP_ACK_TIME < sk->timer.expires) 
+			{
+				reset_xmit_timer(sk, TIME_WRITE, TCP_ACK_TIME);
+			} 
+			else
+				add_timer(&sk->retransmit_timer);
+		}
+	}
+} 
+
+
+/*
+ *	Handle reading urgent data. BSD has very simple semantics for
+ *	this, no blocking and very strange errors 8)
+ */
+ 
+static int tcp_read_urg(struct sock * sk, int nonblock,
+	     unsigned char *to, int len, unsigned flags)
+{
+	/*
+	 *	No URG data to read
+	 */
+	if (sk->urginline || !sk->urg_data || sk->urg_data == URG_READ)
+		return -EINVAL;	/* Yes this is right ! */
+		
+	if (sk->err) 
+	{
+		int tmp = -sk->err;
+		sk->err = 0;
+		return tmp;
+	}
+
+	if (sk->state == TCP_CLOSE || sk->done) 
+	{
+		if (!sk->done) {
+			sk->done = 1;
+			return 0;
+		}
+		return -ENOTCONN;
+	}
+
+	if (sk->shutdown & RCV_SHUTDOWN) 
+	{
+		sk->done = 1;
+		return 0;
+	}
+	sk->inuse = 1;
+	if (sk->urg_data & URG_VALID) 
+	{
+		char c = sk->urg_data;
+		if (!(flags & MSG_PEEK))
+			sk->urg_data = URG_READ;
+		put_fs_byte(c, to);
+		release_sock(sk);
+		return 1;
+	}
+	release_sock(sk);
+	
+	/*
+	 * Fixed the recv(..., MSG_OOB) behaviour.  BSD docs and
+	 * the available implementations agree in this case:
+	 * this call should never block, independent of the
+	 * blocking state of the socket.
+	 * Mike <pall@rz.uni-karlsruhe.de>
+	 */
+	return -EAGAIN;
+}
+
+
+/*
+ *	This routine copies from a sock struct into the user buffer. 
+ */
+ 
+static int tcp_read(struct sock *sk, unsigned char *to,
+	int len, int nonblock, unsigned flags)
+{
+	struct wait_queue wait = { current, NULL };
+	int copied = 0;
+	unsigned long peek_seq;
+	volatile unsigned long *seq;	/* So gcc doesn't overoptimise */
+	unsigned long used;
+
+	/* 
+	 *	This error should be checked. 
+	 */
+	 
+	if (sk->state == TCP_LISTEN)
+		return -ENOTCONN;
+
+	/*
+	 *	Urgent data needs to be handled specially. 
+	 */
+	 
+	if (flags & MSG_OOB)
+		return tcp_read_urg(sk, nonblock, to, len, flags);
+
+	/*
+	 *	Copying sequence to update. This is volatile to handle
+	 *	the multi-reader case neatly (memcpy_to/fromfs might be 
+	 *	inline and thus not flush cached variables otherwise).
+	 */
+	 
+	peek_seq = sk->copied_seq;
+	seq = &sk->copied_seq;
+	if (flags & MSG_PEEK)
+		seq = &peek_seq;
+
+	add_wait_queue(sk->sleep, &wait);
+	sk->inuse = 1;
+	while (len > 0) 
+	{
+		struct sk_buff * skb;
+		unsigned long offset;
+	
+		/*
+		 * Are we at urgent data? Stop if we have read anything.
+		 */
+		 
+		if (copied && sk->urg_data && sk->urg_seq == *seq)
+			break;
+
+		/*
+		 *	Next get a buffer.
+		 */
+		 
+		current->state = TASK_INTERRUPTIBLE;
+
+		skb = skb_peek(&sk->receive_queue);
+		do 
+		{
+			if (!skb)
+				break;
+			if (before(*seq, skb->h.th->seq))
+				break;
+			offset = *seq - skb->h.th->seq;
+			if (skb->h.th->syn)
+				offset--;
+			if (offset < skb->len)
+				goto found_ok_skb;
+			if (skb->h.th->fin)
+				goto found_fin_ok;
+			if (!(flags & MSG_PEEK))
+				skb->used = 1;
+			skb = skb->next;
+		}
+		while (skb != (struct sk_buff *)&sk->receive_queue);
+
+		if (copied)
+			break;
+
+		if (sk->err) 
+		{
+			copied = -sk->err;
+			sk->err = 0;
+			break;
+		}
+
+		if (sk->state == TCP_CLOSE) 
+		{
+			if (!sk->done) 
+			{
+				sk->done = 1;
+				break;
+			}
+			copied = -ENOTCONN;
+			break;
+		}
+
+		if (sk->shutdown & RCV_SHUTDOWN) 
+		{
+			sk->done = 1;
+			break;
+		}
+			
+		if (nonblock) 
+		{
+			copied = -EAGAIN;
+			break;
+		}
+
+		cleanup_rbuf(sk);
+		release_sock(sk);
+		sk->socket->flags |= SO_WAITDATA;
+		schedule();
+		sk->socket->flags &= ~SO_WAITDATA;
+		sk->inuse = 1;
+
+		if (current->signal & ~current->blocked) 
+		{
+			copied = -ERESTARTSYS;
+			break;
+		}
+		continue;
+
+	found_ok_skb:
+		/*
+		 *	Lock the buffer. We can be fairly relaxed as
+		 *	an interrupt will never steal a buffer we are 
+		 *	using unless I've missed something serious in
+		 *	tcp_data.
+		 */
+		
+		skb->users++;
+		
+		/*
+		 *	Ok so how much can we use ? 
+		 */
+		 
+		used = skb->len - offset;
+		if (len < used)
+			used = len;
+		/*
+		 *	Do we have urgent data here? 
+		 */
+		
+		if (sk->urg_data) 
+		{
+			unsigned long urg_offset = sk->urg_seq - *seq;
+			if (urg_offset < used) 
+			{
+				if (!urg_offset) 
+				{
+					if (!sk->urginline) 
+					{
+						++*seq;
+						offset++;
+						used--;
+					}
+				}
+				else
+					used = urg_offset;
+			}
+		}
+		
+		/*
+		 *	Copy it - We _MUST_ update *seq first so that we
+		 *	don't ever double read when we have dual readers
+		 */
+		 
+		*seq += used;
+
+		/*
+		 *	This memcpy_tofs can sleep. If it sleeps and we
+		 *	do a second read it relies on the skb->users to avoid
+		 *	a crash when cleanup_rbuf() gets called.
+		 */
+		 
+		memcpy_tofs(to,((unsigned char *)skb->h.th) +
+			skb->h.th->doff*4 + offset, used);
+		copied += used;
+		len -= used;
+		to += used;
+		
+		/*
+		 *	We now will not sleep again until we are finished
+		 *	with skb. Sorry if you are doing the SMP port
+		 *	but you'll just have to fix it neatly ;)
+		 */
+		 
+		skb->users --;
+		
+		if (after(sk->copied_seq,sk->urg_seq))
+			sk->urg_data = 0;
+		if (used + offset < skb->len)
+			continue;
+		
+		/*
+		 *	Process the FIN.
+		 */
+
+		if (skb->h.th->fin)
+			goto found_fin_ok;
+		if (flags & MSG_PEEK)
+			continue;
+		skb->used = 1;
+		continue;
+
+	found_fin_ok:
+		++*seq;
+		if (flags & MSG_PEEK)
+			break;
+			
+		/*
+		 *	All is done
+		 */
+		 
+		skb->used = 1;
+		sk->shutdown |= RCV_SHUTDOWN;
+		break;
+
+	}
+	remove_wait_queue(sk->sleep, &wait);
+	current->state = TASK_RUNNING;
+
+	/* Clean up data we have read: This will do ACK frames */
+	cleanup_rbuf(sk);
+	release_sock(sk);
+	return copied;
+}
+
+/*
+ *	State processing on a close. This implements the state shift for
+ *	sending our FIN frame. Note that we only send a FIN for some 
+ *	states. A shutdown() may have already sent the FIN, or we may be
+ *	closed.
+ */
+ 
+static int tcp_close_state(struct sock *sk, int dead)
+{
+	int ns=TCP_CLOSE;
+	int send_fin=0;
+	switch(sk->state)
+	{
+		case TCP_SYN_SENT:	/* No SYN back, no FIN needed */
+			break;
+		case TCP_SYN_RECV:
+		case TCP_ESTABLISHED:	/* Closedown begin */
+			ns=TCP_FIN_WAIT1;
+			send_fin=1;
+			break;
+		case TCP_FIN_WAIT1:	/* Already closing, or FIN sent: no change */
+		case TCP_FIN_WAIT2:
+		case TCP_CLOSING:
+			ns=sk->state;
+			break;
+		case TCP_CLOSE:
+		case TCP_LISTEN:
+			break;
+		case TCP_CLOSE_WAIT:	/* They have FIN'd us. We send our FIN and
+					   wait only for the ACK */
+			ns=TCP_LAST_ACK;
+			send_fin=1;
+	}
+	
+	tcp_set_state(sk,ns);
+		
+	/*
+	 *	This is a (useful) BSD violating of the RFC. There is a
+	 *	problem with TCP as specified in that the other end could
+	 *	keep a socket open forever with no application left this end.
+	 *	We use a 3 minute timeout (about the same as BSD) then kill
+	 *	our end. If they send after that then tough - BUT: long enough
+	 *	that we won't make the old 4*rto = almost no time - whoops
+	 *	reset mistake.
+	 */
+	if(dead && ns==TCP_FIN_WAIT2)
+	{
+		int timer_active=del_timer(&sk->timer);
+		if(timer_active)
+			add_timer(&sk->timer);
+		else
+			reset_msl_timer(sk, TIME_CLOSE, TCP_FIN_TIMEOUT);
+	}
+	
+	return send_fin;
+}
+
+/*
+ *	Send a fin.
+ */
+
+static void tcp_send_fin(struct sock *sk)
+{
+	struct proto *prot =(struct proto *)sk->prot;
+	struct tcphdr *th =(struct tcphdr *)&sk->dummy_th;
+	struct tcphdr *t1;
+	struct sk_buff *buff;
+	struct device *dev=NULL;
+	int tmp;
+		
+	release_sock(sk); /* in case the malloc sleeps. */
+	
+	buff = prot->wmalloc(sk, MAX_RESET_SIZE,1 , GFP_KERNEL);
+	sk->inuse = 1;
+
+	if (buff == NULL)
+	{
+		/* This is a disaster if it occurs */
+		printk("tcp_send_fin: Impossible malloc failure");
+		return;
+	}
+
+	/*
+	 *	Administrivia
+	 */
+	 
+	buff->sk = sk;
+	buff->len = sizeof(*t1);
+	buff->localroute = sk->localroute;
+	t1 =(struct tcphdr *) buff->data;
+
+	/*
+	 *	Put in the IP header and routing stuff. 
+	 */
+
+	tmp = prot->build_header(buff,sk->saddr, sk->daddr, &dev,
+			   IPPROTO_TCP, sk->opt,
+			   sizeof(struct tcphdr),sk->ip_tos,sk->ip_ttl);
+	if (tmp < 0) 
+	{
+		int t;
+  		/*
+  		 *	Finish anyway, treat this as a send that got lost. 
+  		 *	(Not good).
+  		 */
+  		 
+	  	buff->free = 1;
+		prot->wfree(sk,buff->mem_addr, buff->mem_len);
+		sk->write_seq++;
+		t=del_timer(&sk->timer);
+		if(t)
+			add_timer(&sk->timer);
+		else
+			reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
+		return;
+	}
+	
+	/*
+	 *	We ought to check if the end of the queue is a buffer and
+	 *	if so simply add the fin to that buffer, not send it ahead.
+	 */
+
+	t1 =(struct tcphdr *)((char *)t1 +tmp);
+	buff->len += tmp;
+	buff->dev = dev;
+	memcpy(t1, th, sizeof(*t1));
+	t1->seq = ntohl(sk->write_seq);
+	sk->write_seq++;
+	buff->h.seq = sk->write_seq;
+	t1->ack = 1;
+	t1->ack_seq = ntohl(sk->acked_seq);
+	t1->window = ntohs(sk->window=tcp_select_window(sk));
+	t1->fin = 1;
+	t1->rst = 0;
+	t1->doff = sizeof(*t1)/4;
+	tcp_send_check(t1, sk->saddr, sk->daddr, sizeof(*t1), sk);
+
+	/*
+	 * If there is data in the write queue, the fin must be appended to
+	 * the write queue.
+ 	 */
+ 	
+ 	if (skb_peek(&sk->write_queue) != NULL) 
+ 	{
+  		buff->free = 0;
+		if (buff->next != NULL) 
+		{
+			printk("tcp_send_fin: next != NULL\n");
+			skb_unlink(buff);
+		}
+		skb_queue_tail(&sk->write_queue, buff);
+  	} 
+  	else 
+  	{
+        	sk->sent_seq = sk->write_seq;
+		sk->prot->queue_xmit(sk, dev, buff, 0);
+		reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+	}
+}
+
+/*
+ *	Shutdown the sending side of a connection. Much like close except
+ *	that we don't receive shut down or set sk->dead=1.
+ */
+
+void tcp_shutdown(struct sock *sk, int how)
+{
+	/*
+	 *	We need to grab some memory, and put together a FIN,
+	 *	and then put it into the queue to be sent.
+	 *		Tim MacKenzie(tym@dibbler.cs.monash.edu.au) 4 Dec '92.
+	 */
+
+	if (!(how & SEND_SHUTDOWN)) 
+		return;
+	 
+	/*
+	 *	If we've already sent a FIN, or it's a closed state
+	 */
+	 
+	if (sk->state == TCP_FIN_WAIT1 ||
+	    sk->state == TCP_FIN_WAIT2 ||
+	    sk->state == TCP_CLOSING ||
+	    sk->state == TCP_LAST_ACK ||
+	    sk->state == TCP_TIME_WAIT || 
+	    sk->state == TCP_CLOSE ||
+	    sk->state == TCP_LISTEN
+	  )
+	{
+		return;
+	}
+	sk->inuse = 1;
+
+	/*
+	 * flag that the sender has shutdown
+	 */
+
+	sk->shutdown |= SEND_SHUTDOWN;
+
+	/*
+	 *  Clear out any half completed packets. 
+	 */
+
+	if (sk->partial)
+		tcp_send_partial(sk);
+		
+	/*
+	 *	FIN if needed
+	 */
+	 
+	if(tcp_close_state(sk,0))
+		tcp_send_fin(sk);
+		
+	release_sock(sk);
+}
+
+
+static int
+tcp_recvfrom(struct sock *sk, unsigned char *to,
+	     int to_len, int nonblock, unsigned flags,
+	     struct sockaddr_in *addr, int *addr_len)
+{
+	int result;
+  
+	/* 
+	 *	Have to check these first unlike the old code. If 
+	 *	we check them after we lose data on an error
+	 *	which is wrong 
+	 */
+
+	if(addr_len)
+		*addr_len = sizeof(*addr);
+	result=tcp_read(sk, to, to_len, nonblock, flags);
+
+	if (result < 0) 
+		return(result);
+  
+  	if(addr)
+  	{
+		addr->sin_family = AF_INET;
+ 		addr->sin_port = sk->dummy_th.dest;
+		addr->sin_addr.s_addr = sk->daddr;
+	}
+	return(result);
+}
+
+
+/*
+ *	This routine will send an RST to the other tcp. 
+ */
+ 
+static void tcp_reset(unsigned long saddr, unsigned long daddr, struct tcphdr *th,
+	  struct proto *prot, struct options *opt, struct device *dev, int tos, int ttl)
+{
+	struct sk_buff *buff;
+	struct tcphdr *t1;
+	int tmp;
+	struct device *ndev=NULL;
+
+	/*
+	 *	Cannot reset a reset (Think about it).
+	 */
+	 
+	if(th->rst)
+		return;
+  
+	/*
+	 * We need to grab some memory, and put together an RST,
+	 * and then put it into the queue to be sent.
+	 */
+
+	buff = prot->wmalloc(NULL, MAX_RESET_SIZE, 1, GFP_ATOMIC);
+	if (buff == NULL) 
+	  	return;
+
+	buff->len = sizeof(*t1);
+	buff->sk = NULL;
+	buff->dev = dev;
+	buff->localroute = 0;
+
+	t1 =(struct tcphdr *) buff->data;
+
+	/*
+	 *	Put in the IP header and routing stuff. 
+	 */
+
+	tmp = prot->build_header(buff, saddr, daddr, &ndev, IPPROTO_TCP, opt,
+			   sizeof(struct tcphdr),tos,ttl);
+	if (tmp < 0) 
+	{
+  		buff->free = 1;
+		prot->wfree(NULL, buff->mem_addr, buff->mem_len);
+		return;
+	}
+
+	t1 =(struct tcphdr *)((char *)t1 +tmp);
+	buff->len += tmp;
+	memcpy(t1, th, sizeof(*t1));
+
+	/*
+	 *	Swap the send and the receive. 
+	 */
+
+	t1->dest = th->source;
+	t1->source = th->dest;
+	t1->rst = 1;  
+	t1->window = 0;
+  
+	if(th->ack)
+	{
+		t1->ack = 0;
+	  	t1->seq = th->ack_seq;
+	  	t1->ack_seq = 0;
+	}
+	else
+	{
+	  	t1->ack = 1;
+	  	if(!th->syn)
+  			t1->ack_seq=htonl(th->seq);
+  		else
+  			t1->ack_seq=htonl(th->seq+1);
+  		t1->seq=0;
+	}
+
+	t1->syn = 0;
+	t1->urg = 0;
+	t1->fin = 0;
+	t1->psh = 0;
+	t1->doff = sizeof(*t1)/4;
+	tcp_send_check(t1, saddr, daddr, sizeof(*t1), NULL);
+	prot->queue_xmit(NULL, ndev, buff, 1);
+	tcp_statistics.TcpOutSegs++;
+}
+
+
+/*
+ *	Look for tcp options. Parses everything but only knows about MSS.
+ *      This routine is always called with the packet containing the SYN.
+ *      However it may also be called with the ack to the SYN.  So you
+ *      can't assume this is always the SYN.  It's always called after
+ *      we have set up sk->mtu to our own MTU.
+ *
+ *	We need at minimum to add PAWS support here. Possibly large windows
+ *	as Linux gets deployed on 100Mb/sec networks.
+ */
+ 
+static void tcp_options(struct sock *sk, struct tcphdr *th)
+{
+	unsigned char *ptr;
+	int length=(th->doff*4)-sizeof(struct tcphdr);
+	int mss_seen = 0;
+    
+	ptr = (unsigned char *)(th + 1);
+  
+	while(length>0)
+	{
+	  	int opcode=*ptr++;
+	  	int opsize=*ptr++;
+	  	switch(opcode)
+	  	{
+	  		case TCPOPT_EOL:
+	  			return;
+	  		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
+	  			length--;
+	  			ptr--;		/* the opsize=*ptr++ above was a mistake */
+	  			continue;
+	  		
+	  		default:
+	  			if(opsize<=2)	/* Avoid silly options looping forever */
+	  				return;
+	  			switch(opcode)
+	  			{
+	  				case TCPOPT_MSS:
+	  					if(opsize==4 && th->syn)
+	  					{
+	  						sk->mtu=min(sk->mtu,ntohs(*(unsigned short *)ptr));
+							mss_seen = 1;
+	  					}
+	  					break;
+		  				/* Add other options here as people feel the urge to implement stuff like large windows */
+	  			}
+	  			ptr+=opsize-2;
+	  			length-=opsize;
+	  	}
+	}
+	if (th->syn) 
+	{
+		if (! mss_seen)
+		      sk->mtu=min(sk->mtu, 536);  /* default MSS if none sent */
+	}
+#ifdef CONFIG_INET_PCTCP
+	sk->mss = min(sk->max_window >> 1, sk->mtu);
+#else    
+	sk->mss = min(sk->max_window, sk->mtu);
+#endif  
+}
+
+static inline unsigned long default_mask(unsigned long dst)
+{
+	dst = ntohl(dst);
+	if (IN_CLASSA(dst))
+		return htonl(IN_CLASSA_NET);
+	if (IN_CLASSB(dst))
+		return htonl(IN_CLASSB_NET);
+	return htonl(IN_CLASSC_NET);
+}
+
+/*
+ *	Default sequence number picking algorithm.
+ *	As close as possible to RFC 793, which
+ *	suggests using a 250kHz clock.
+ *	Further reading shows this assumes 2MB/s networks.
+ *	For 10MB/s ethernet, a 1MHz clock is appropriate.
+ *	That's funny, Linux has one built in!  Use it!
+ */
+
+extern inline unsigned long tcp_init_seq(void)
+{
+	struct timeval tv;
+	do_gettimeofday(&tv);
+	return tv.tv_usec+tv.tv_sec*1000000;
+}
+
+/*
+ *	This routine handles a connection request.
+ *	It should make sure we haven't already responded.
+ *	Because of the way BSD works, we have to send a syn/ack now.
+ *	This also means it will be harder to close a socket which is
+ *	listening.
+ */
+ 
+static void tcp_conn_request(struct sock *sk, struct sk_buff *skb,
+		 unsigned long daddr, unsigned long saddr,
+		 struct options *opt, struct device *dev, unsigned long seq)
+{
+	struct sk_buff *buff;
+	struct tcphdr *t1;
+	unsigned char *ptr;
+	struct sock *newsk;
+	struct tcphdr *th;
+	struct device *ndev=NULL;
+	int tmp;
+	struct rtable *rt;
+  
+	th = skb->h.th;
+
+	/* If the socket is dead, don't accept the connection. */
+	if (!sk->dead) 
+	{
+  		sk->data_ready(sk,0);
+	}
+	else 
+	{
+		if(sk->debug)
+			printk("Reset on %p: Connect on dead socket.\n",sk);
+		tcp_reset(daddr, saddr, th, sk->prot, opt, dev, sk->ip_tos,sk->ip_ttl);
+		tcp_statistics.TcpAttemptFails++;
+		kfree_skb(skb, FREE_READ);
+		return;
+	}
+
+	/*
+	 * Make sure we can accept more.  This will prevent a
+	 * flurry of syns from eating up all our memory.
+	 */
+
+	if (sk->ack_backlog >= sk->max_ack_backlog) 
+	{
+		tcp_statistics.TcpAttemptFails++;
+		kfree_skb(skb, FREE_READ);
+		return;
+	}
+
+	/*
+	 * We need to build a new sock struct.
+	 * It is sort of bad to have a socket without an inode attached
+	 * to it, but the wake_up's will just wake up the listening socket,
+	 * and if the listening socket is destroyed before this is taken
+	 * off of the queue, this will take care of it.
+	 */
+
+	newsk = (struct sock *) kmalloc(sizeof(struct sock), GFP_ATOMIC);
+	if (newsk == NULL) 
+	{
+		/* just ignore the syn.  It will get retransmitted. */
+		tcp_statistics.TcpAttemptFails++;
+		kfree_skb(skb, FREE_READ);
+		return;
+	}
+
+	memcpy(newsk, sk, sizeof(*newsk));
+	skb_queue_head_init(&newsk->write_queue);
+	skb_queue_head_init(&newsk->receive_queue);
+	newsk->send_head = NULL;
+	newsk->send_tail = NULL;
+	skb_queue_head_init(&newsk->back_log);
+	newsk->rtt = 0;		/*TCP_CONNECT_TIME<<3*/
+	newsk->rto = TCP_TIMEOUT_INIT;
+	newsk->mdev = 0;
+	newsk->max_window = 0;
+	newsk->cong_window = 1;
+	newsk->cong_count = 0;
+	newsk->ssthresh = 0;
+	newsk->backoff = 0;
+	newsk->blog = 0;
+	newsk->intr = 0;
+	newsk->proc = 0;
+	newsk->done = 0;
+	newsk->partial = NULL;
+	newsk->pair = NULL;
+	newsk->wmem_alloc = 0;
+	newsk->rmem_alloc = 0;
+	newsk->localroute = sk->localroute;
+
+	newsk->max_unacked = MAX_WINDOW - TCP_WINDOW_DIFF;
+
+	newsk->err = 0;
+	newsk->shutdown = 0;
+	newsk->ack_backlog = 0;
+	newsk->acked_seq = skb->h.th->seq+1;
+	newsk->copied_seq = skb->h.th->seq+1;
+	newsk->fin_seq = skb->h.th->seq;
+	newsk->state = TCP_SYN_RECV;
+	newsk->timeout = 0;
+	newsk->ip_xmit_timeout = 0;
+	newsk->write_seq = seq; 
+	newsk->window_seq = newsk->write_seq;
+	newsk->rcv_ack_seq = newsk->write_seq;
+	newsk->urg_data = 0;
+	newsk->retransmits = 0;
+	newsk->linger=0;
+	newsk->destroy = 0;
+	init_timer(&newsk->timer);
+	newsk->timer.data = (unsigned long)newsk;
+	newsk->timer.function = &net_timer;
+	init_timer(&newsk->retransmit_timer);
+	newsk->retransmit_timer.data = (unsigned long)newsk;
+	newsk->retransmit_timer.function=&retransmit_timer;
+	newsk->dummy_th.source = skb->h.th->dest;
+	newsk->dummy_th.dest = skb->h.th->source;
+	
+	/*
+	 *	Swap these two, they are from our point of view. 
+	 */
+	 
+	newsk->daddr = saddr;
+	newsk->saddr = daddr;
+
+	put_sock(newsk->num,newsk);
+	newsk->dummy_th.res1 = 0;
+	newsk->dummy_th.doff = 6;
+	newsk->dummy_th.fin = 0;
+	newsk->dummy_th.syn = 0;
+	newsk->dummy_th.rst = 0;	
+	newsk->dummy_th.psh = 0;
+	newsk->dummy_th.ack = 0;
+	newsk->dummy_th.urg = 0;
+	newsk->dummy_th.res2 = 0;
+	newsk->acked_seq = skb->h.th->seq + 1;
+	newsk->copied_seq = skb->h.th->seq + 1;
+	newsk->socket = NULL;
+
+	/*
+	 *	Grab the ttl and tos values and use them 
+	 */
+
+	newsk->ip_ttl=sk->ip_ttl;
+	newsk->ip_tos=skb->ip_hdr->tos;
+
+	/*
+	 *	Use 512 or whatever user asked for 
+	 */
+
+	/*
+	 * 	Note use of sk->user_mss, since user has no direct access to newsk 
+	 */
+
+	rt=ip_rt_route(saddr, NULL,NULL);
+	
+	if(rt!=NULL && (rt->rt_flags&RTF_WINDOW))
+		newsk->window_clamp = rt->rt_window;
+	else
+		newsk->window_clamp = 0;
+		
+	if (sk->user_mss)
+		newsk->mtu = sk->user_mss;
+	else if(rt!=NULL && (rt->rt_flags&RTF_MSS))
+		newsk->mtu = rt->rt_mss - HEADER_SIZE;
+	else 
+	{
+#ifdef CONFIG_INET_SNARL	/* Sub Nets Are Local */
+		if ((saddr ^ daddr) & default_mask(saddr))
+#else
+		if ((saddr ^ daddr) & dev->pa_mask)
+#endif
+			newsk->mtu = 576 - HEADER_SIZE;
+		else
+			newsk->mtu = MAX_WINDOW;
+	}
+
+	/*
+	 *	But not bigger than device MTU 
+	 */
+
+	newsk->mtu = min(newsk->mtu, dev->mtu - HEADER_SIZE);
+
+	/*
+	 *	This will min with what arrived in the packet 
+	 */
+
+	tcp_options(newsk,skb->h.th);
+
+	buff = newsk->prot->wmalloc(newsk, MAX_SYN_SIZE, 1, GFP_ATOMIC);
+	if (buff == NULL) 
+	{
+		sk->err = -ENOMEM;
+		newsk->dead = 1;
+		newsk->state = TCP_CLOSE;
+		/* And this will destroy it */
+		release_sock(newsk);
+		kfree_skb(skb, FREE_READ);
+		tcp_statistics.TcpAttemptFails++;
+		return;
+	}
+  
+	buff->len = sizeof(struct tcphdr)+4;
+	buff->sk = newsk;
+	buff->localroute = newsk->localroute;
+
+	t1 =(struct tcphdr *) buff->data;
+
+	/*
+	 *	Put in the IP header and routing stuff. 
+	 */
+
+	tmp = sk->prot->build_header(buff, newsk->saddr, newsk->daddr, &ndev,
+			       IPPROTO_TCP, NULL, MAX_SYN_SIZE,sk->ip_tos,sk->ip_ttl);
+
+	/*
+	 *	Something went wrong. 
+	 */
+
+	if (tmp < 0) 
+	{
+		sk->err = tmp;
+		buff->free = 1;
+		kfree_skb(buff,FREE_WRITE);
+		newsk->dead = 1;
+		newsk->state = TCP_CLOSE;
+		release_sock(newsk);
+		skb->sk = sk;
+		kfree_skb(skb, FREE_READ);
+		tcp_statistics.TcpAttemptFails++;
+		return;
+	}
+
+	buff->len += tmp;
+	t1 =(struct tcphdr *)((char *)t1 +tmp);
+  
+	memcpy(t1, skb->h.th, sizeof(*t1));
+	buff->h.seq = newsk->write_seq;
+	/*
+	 *	Swap the send and the receive. 
+	 */
+	t1->dest = skb->h.th->source;
+	t1->source = newsk->dummy_th.source;
+	t1->seq = ntohl(newsk->write_seq++);
+	t1->ack = 1;
+	newsk->window = tcp_select_window(newsk);
+	newsk->sent_seq = newsk->write_seq;
+	t1->window = ntohs(newsk->window);
+	t1->res1 = 0;
+	t1->res2 = 0;
+	t1->rst = 0;
+	t1->urg = 0;
+	t1->psh = 0;
+	t1->syn = 1;
+	t1->ack_seq = ntohl(skb->h.th->seq+1);
+	t1->doff = sizeof(*t1)/4+1;
+	ptr =(unsigned char *)(t1+1);
+	ptr[0] = 2;
+	ptr[1] = 4;
+	ptr[2] = ((newsk->mtu) >> 8) & 0xff;
+	ptr[3] =(newsk->mtu) & 0xff;
+
+	tcp_send_check(t1, daddr, saddr, sizeof(*t1)+4, newsk);
+	newsk->prot->queue_xmit(newsk, ndev, buff, 0);
+	reset_xmit_timer(newsk, TIME_WRITE , TCP_TIMEOUT_INIT);
+	skb->sk = newsk;
+
+	/*
+	 *	Charge the sock_buff to newsk. 
+	 */
+	 
+	sk->rmem_alloc -= skb->mem_len;
+	newsk->rmem_alloc += skb->mem_len;
+	
+	skb_queue_tail(&sk->receive_queue,skb);
+	sk->ack_backlog++;
+	release_sock(newsk);
+	tcp_statistics.TcpOutSegs++;
+}
+
+
+static void tcp_close(struct sock *sk, int timeout)
+{
+	/*
+	 * We need to grab some memory, and put together a FIN,	
+	 * and then put it into the queue to be sent.
+	 */
+	
+	sk->inuse = 1;
+	
+	if(sk->state == TCP_LISTEN)
+	{
+		/* Special case */
+		tcp_set_state(sk, TCP_CLOSE);
+		tcp_close_pending(sk);
+		release_sock(sk);
+		return;
+	}
+	
+	sk->keepopen = 1;
+	sk->shutdown = SHUTDOWN_MASK;
+
+	if (!sk->dead) 
+	  	sk->state_change(sk);
+
+	if (timeout == 0) 
+	{
+		struct sk_buff *skb;
+		
+		/*
+		 *  We need to flush the recv. buffs.  We do this only on the
+		 *  descriptor close, not protocol-sourced closes, because the
+		 *  reader process may not have drained the data yet!
+		 */
+		 
+		while((skb=skb_dequeue(&sk->receive_queue))!=NULL)
+			kfree_skb(skb, FREE_READ);
+		/*
+		 *	Get rid off any half-completed packets. 
+		 */
+
+		if (sk->partial) 
+			tcp_send_partial(sk);
+	}
+
+		
+	/*
+	 *	Timeout is not the same thing - however the code likes
+	 *	to send both the same way (sigh).
+	 */
+	 
+	if(timeout)
+	{
+		tcp_set_state(sk, TCP_CLOSE);	/* Dead */
+	}
+	else
+	{
+		if(tcp_close_state(sk,1)==1)
+		{
+			tcp_send_fin(sk);
+		}
+	}
+	release_sock(sk);
+}
+
+
+/*
+ * 	This routine takes stuff off of the write queue,
+ *	and puts it in the xmit queue. This happens as incoming acks
+ *	open up the remote window for us.
+ */
+ 
+static void tcp_write_xmit(struct sock *sk)
+{
+	struct sk_buff *skb;
+
+	/*
+	 *	The bytes will have to remain here. In time closedown will
+	 *	empty the write queue and all will be happy 
+	 */
+
+	if(sk->zapped)
+		return;
+
+	/*
+	 *	Anything on the transmit queue that fits the window can
+	 *	be added providing we are not
+	 *
+	 *	a) retransmitting (Nagle's rule)
+	 *	b) exceeding our congestion window.
+	 */
+	 
+	while((skb = skb_peek(&sk->write_queue)) != NULL &&
+		before(skb->h.seq, sk->window_seq + 1) &&
+		(sk->retransmits == 0 ||
+		 sk->ip_xmit_timeout != TIME_WRITE ||
+		 before(skb->h.seq, sk->rcv_ack_seq + 1))
+		&& sk->packets_out < sk->cong_window) 
+	{
+		IS_SKB(skb);
+		skb_unlink(skb);
+		
+		/*
+		 *	See if we really need to send the packet. 
+		 */
+		 
+		if (before(skb->h.seq, sk->rcv_ack_seq +1)) 
+		{
+			/*
+			 *	This is acked data. We can discard it. This 
+			 *	cannot currently occur.
+			 */
+			 
+			sk->retransmits = 0;
+			kfree_skb(skb, FREE_WRITE);
+			if (!sk->dead) 
+				sk->write_space(sk);
+		} 
+		else
+		{
+			struct tcphdr *th;
+			struct iphdr *iph;
+			int size;
+/*
+ * put in the ack seq and window at this point rather than earlier,
+ * in order to keep them monotonic.  We really want to avoid taking
+ * back window allocations.  That's legal, but RFC1122 says it's frowned on.
+ * Ack and window will in general have changed since this packet was put
+ * on the write queue.
+ */
+			iph = (struct iphdr *)(skb->data +
+					       skb->dev->hard_header_len);
+			th = (struct tcphdr *)(((char *)iph) +(iph->ihl << 2));
+			size = skb->len - (((unsigned char *) th) - skb->data);
+			
+			th->ack_seq = ntohl(sk->acked_seq);
+			th->window = ntohs(tcp_select_window(sk));
+
+			tcp_send_check(th, sk->saddr, sk->daddr, size, sk);
+
+			sk->sent_seq = skb->h.seq;
+			
+			/*
+			 *	IP manages our queue for some crazy reason
+			 */
+			 
+			sk->prot->queue_xmit(sk, skb->dev, skb, skb->free);
+			
+			/*
+			 *	Again we slide the timer wrongly
+			 */
+			 
+			reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+		}
+	}
+}
+
+
+/*
+ *	This routine deals with incoming acks, but not outgoing ones.
+ */
+
+extern __inline__ int tcp_ack(struct sock *sk, struct tcphdr *th, unsigned long saddr, int len)
+{
+	unsigned long ack;
+	int flag = 0;
+
+	/* 
+	 * 1 - there was data in packet as well as ack or new data is sent or 
+	 *     in shutdown state
+	 * 2 - data from retransmit queue was acked and removed
+	 * 4 - window shrunk or data from retransmit queue was acked and removed
+	 */
+
+	if(sk->zapped)
+		return(1);	/* Dead, cant ack any more so why bother */
+
+	/*
+	 *	Have we discovered a larger window
+	 */
+	 
+	ack = ntohl(th->ack_seq);
+
+	if (ntohs(th->window) > sk->max_window) 
+	{
+  		sk->max_window = ntohs(th->window);
+#ifdef CONFIG_INET_PCTCP
+		/* Hack because we don't send partial packets to non SWS
+		   handling hosts */
+		sk->mss = min(sk->max_window>>1, sk->mtu);
+#else
+		sk->mss = min(sk->max_window, sk->mtu);
+#endif	
+	}
+
+	/*
+	 *	We have dropped back to keepalive timeouts. Thus we have
+	 *	no retransmits pending.
+	 */
+	 
+	if (sk->retransmits && sk->ip_xmit_timeout == TIME_KEEPOPEN)
+	  	sk->retransmits = 0;
+
+	/*
+	 *	If the ack is newer than sent or older than previous acks
+	 *	then we can probably ignore it.
+	 */
+	 
+	if (after(ack, sk->sent_seq) || before(ack, sk->rcv_ack_seq)) 
+	{
+		if(sk->debug)
+			printk("Ack ignored %lu %lu\n",ack,sk->sent_seq);
+			
+		/*
+		 *	Keepalive processing.
+		 */
+		 
+		if (after(ack, sk->sent_seq)) 
+		{
+			return(0);
+		}
+		
+		/*
+		 *	Restart the keepalive timer.
+		 */
+		 
+		if (sk->keepopen) 
+		{
+			if(sk->ip_xmit_timeout==TIME_KEEPOPEN)
+				reset_xmit_timer(sk, TIME_KEEPOPEN, TCP_TIMEOUT_LEN);
+		}
+		return(1);
+	}
+
+	/*
+	 *	If there is data set flag 1
+	 */
+	 
+	if (len != th->doff*4) 
+		flag |= 1;
+
+	/*
+	 *	See if our window has been shrunk. 
+	 */
+
+	if (after(sk->window_seq, ack+ntohs(th->window))) 
+	{
+		/*
+		 * We may need to move packets from the send queue
+		 * to the write queue, if the window has been shrunk on us.
+		 * The RFC says you are not allowed to shrink your window
+		 * like this, but if the other end does, you must be able
+		 * to deal with it.
+		 */
+		struct sk_buff *skb;
+		struct sk_buff *skb2;
+		struct sk_buff *wskb = NULL;
+  	
+		skb2 = sk->send_head;
+		sk->send_head = NULL;
+		sk->send_tail = NULL;
+	
+		/*
+		 *	This is an artifact of a flawed concept. We want one
+		 *	queue and a smarter send routine when we send all.
+		 */
+	
+		flag |= 4;	/* Window changed */
+	
+		sk->window_seq = ack + ntohs(th->window);
+		cli();
+		while (skb2 != NULL) 
+		{
+			skb = skb2;
+			skb2 = skb->link3;
+			skb->link3 = NULL;
+			if (after(skb->h.seq, sk->window_seq)) 
+			{
+				if (sk->packets_out > 0) 
+					sk->packets_out--;
+				/* We may need to remove this from the dev send list. */
+				if (skb->next != NULL) 
+				{
+					skb_unlink(skb);				
+				}
+				/* Now add it to the write_queue. */
+				if (wskb == NULL)
+					skb_queue_head(&sk->write_queue,skb);
+				else
+					skb_append(wskb,skb);
+				wskb = skb;
+			} 
+			else 
+			{
+				if (sk->send_head == NULL) 
+				{
+					sk->send_head = skb;
+					sk->send_tail = skb;
+				}
+				else
+				{
+					sk->send_tail->link3 = skb;
+					sk->send_tail = skb;
+				}
+				skb->link3 = NULL;
+			}
+		}
+		sti();
+	}
+
+	/*
+	 *	Pipe has emptied
+	 */
+	 
+	if (sk->send_tail == NULL || sk->send_head == NULL) 
+	{
+		sk->send_head = NULL;
+		sk->send_tail = NULL;
+		sk->packets_out= 0;
+	}
+
+	/*
+	 *	Update the right hand window edge of the host
+	 */
+	 
+	sk->window_seq = ack + ntohs(th->window);
+
+	/*
+	 *	We don't want too many packets out there. 
+	 */
+	 
+	if (sk->ip_xmit_timeout == TIME_WRITE && 
+		sk->cong_window < 2048 && after(ack, sk->rcv_ack_seq)) 
+	{
+		/* 
+		 * This is Jacobson's slow start and congestion avoidance. 
+		 * SIGCOMM '88, p. 328.  Because we keep cong_window in integral
+		 * mss's, we can't do cwnd += 1 / cwnd.  Instead, maintain a 
+		 * counter and increment it once every cwnd times.  It's possible
+		 * that this should be done only if sk->retransmits == 0.  I'm
+		 * interpreting "new data is acked" as including data that has
+		 * been retransmitted but is just now being acked.
+		 */
+		if (sk->cong_window < sk->ssthresh)  
+			/* 
+			 *	In "safe" area, increase
+			 */
+			sk->cong_window++;
+		else 
+		{
+			/*
+			 *	In dangerous area, increase slowly.  In theory this is
+			 *  	sk->cong_window += 1 / sk->cong_window
+			 */
+			if (sk->cong_count >= sk->cong_window) 
+			{
+				sk->cong_window++;
+				sk->cong_count = 0;
+			}
+			else 
+				sk->cong_count++;
+		}
+	}
+
+	/*
+	 *	Remember the highest ack received.
+	 */
+	 
+	sk->rcv_ack_seq = ack;
+
+	/*
+	 *	If this ack opens up a zero window, clear backoff.  It was
+	 *	being used to time the probes, and is probably far higher than
+	 *	it needs to be for normal retransmission.
+	 */
+
+	if (sk->ip_xmit_timeout == TIME_PROBE0) 
+	{
+		sk->retransmits = 0;	/* Our probe was answered */
+		
+		/*
+		 *	Was it a usable window open ?
+		 */
+		 
+  		if (skb_peek(&sk->write_queue) != NULL &&   /* should always be non-null */
+		    ! before (sk->window_seq, sk->write_queue.next->h.seq)) 
+		{
+			sk->backoff = 0;
+			
+			/*
+			 *	Recompute rto from rtt.  this eliminates any backoff.
+			 */
+
+			sk->rto = ((sk->rtt >> 2) + sk->mdev) >> 1;
+			if (sk->rto > 120*HZ)
+				sk->rto = 120*HZ;
+			if (sk->rto < 20)	/* Was 1*HZ, then 1 - turns out we must allow about
+						   .2 of a second because of BSD delayed acks - on a 100Mb/sec link
+						   .2 of a second is going to need huge windows (SIGH) */
+			sk->rto = 20;
+		}
+	}
+
+	/* 
+	 *	See if we can take anything off of the retransmit queue.
+	 */
+   
+	while(sk->send_head != NULL) 
+	{
+		/* Check for a bug. */
+		if (sk->send_head->link3 &&
+		    after(sk->send_head->h.seq, sk->send_head->link3->h.seq)) 
+			printk("INET: tcp.c: *** bug send_list out of order.\n");
+			
+		/*
+		 *	If our packet is before the ack sequence we can
+		 *	discard it as it's confirmed to have arrived the other end.
+		 */
+		 
+		if (before(sk->send_head->h.seq, ack+1)) 
+		{
+			struct sk_buff *oskb;	
+			if (sk->retransmits) 
+			{	
+				/*
+				 *	We were retransmitting.  don't count this in RTT est 
+				 */
+				flag |= 2;
+
+				/*
+				 * even though we've gotten an ack, we're still
+				 * retransmitting as long as we're sending from
+				 * the retransmit queue.  Keeping retransmits non-zero
+				 * prevents us from getting new data interspersed with
+				 * retransmissions.
+				 */
+
+				if (sk->send_head->link3)	/* Any more queued retransmits? */
+					sk->retransmits = 1;
+				else
+					sk->retransmits = 0;
+			}
+  			/*
+			 * Note that we only reset backoff and rto in the
+			 * rtt recomputation code.  And that doesn't happen
+			 * if there were retransmissions in effect.  So the
+			 * first new packet after the retransmissions is
+			 * sent with the backoff still in effect.  Not until
+			 * we get an ack from a non-retransmitted packet do
+			 * we reset the backoff and rto.  This allows us to deal
+			 * with a situation where the network delay has increased
+			 * suddenly.  I.e. Karn's algorithm. (SIGCOMM '87, p5.)
+			 */
+
+			/*
+			 *	We have one less packet out there. 
+			 */
+			 
+			if (sk->packets_out > 0) 
+				sk->packets_out --;
+			/* 
+			 *	Wake up the process, it can probably write more. 
+			 */
+			if (!sk->dead) 
+				sk->write_space(sk);
+			oskb = sk->send_head;
+
+			if (!(flag&2)) 	/* Not retransmitting */
+			{
+				long m;
+	
+				/*
+				 *	The following amusing code comes from Jacobson's
+				 *	article in SIGCOMM '88.  Note that rtt and mdev
+				 *	are scaled versions of rtt and mean deviation.
+				 *	This is designed to be as fast as possible 
+				 *	m stands for "measurement".
+				 */
+	
+				m = jiffies - oskb->when;  /* RTT */
+				if(m<=0)
+					m=1;		/* IS THIS RIGHT FOR <0 ??? */
+				m -= (sk->rtt >> 3);    /* m is now error in rtt est */
+				sk->rtt += m;           /* rtt = 7/8 rtt + 1/8 new */
+				if (m < 0)
+					m = -m;		/* m is now abs(error) */
+				m -= (sk->mdev >> 2);   /* similar update on mdev */
+				sk->mdev += m;	    	/* mdev = 3/4 mdev + 1/4 new */
+	
+				/*
+				 *	Now update timeout.  Note that this removes any backoff.
+				 */
+			 
+				sk->rto = ((sk->rtt >> 2) + sk->mdev) >> 1;
+				if (sk->rto > 120*HZ)
+					sk->rto = 120*HZ;
+				if (sk->rto < 20)	/* Was 1*HZ - keep .2 as minimum cos of the BSD delayed acks */
+					sk->rto = 20;
+				sk->backoff = 0;
+			}
+			flag |= (2|4);	/* 2 is really more like 'don't adjust the rtt 
+			                   In this case as we just set it up */
+			cli();
+			oskb = sk->send_head;
+			IS_SKB(oskb);
+			sk->send_head = oskb->link3;
+			if (sk->send_head == NULL) 
+			{
+				sk->send_tail = NULL;
+			}
+
+		/*
+		 *	We may need to remove this from the dev send list. 
+		 */
+
+			if (oskb->next)
+				skb_unlink(oskb);
+			sti();
+			kfree_skb(oskb, FREE_WRITE); /* write. */
+			if (!sk->dead) 
+				sk->write_space(sk);
+		}
+		else
+		{
+			break;
+		}
+	}
+
+	/*
+	 * XXX someone ought to look at this too.. at the moment, if skb_peek()
+	 * returns non-NULL, we complete ignore the timer stuff in the else
+	 * clause.  We ought to organize the code so that else clause can
+	 * (should) be executed regardless, possibly moving the PROBE timer
+	 * reset over.  The skb_peek() thing should only move stuff to the
+	 * write queue, NOT also manage the timer functions.
+	 */
+
+	/*
+	 * Maybe we can take some stuff off of the write queue,
+	 * and put it onto the xmit queue.
+	 */
+	if (skb_peek(&sk->write_queue) != NULL) 
+	{
+		if (after (sk->window_seq+1, sk->write_queue.next->h.seq) &&
+		        (sk->retransmits == 0 || 
+			 sk->ip_xmit_timeout != TIME_WRITE ||
+			 before(sk->write_queue.next->h.seq, sk->rcv_ack_seq + 1))
+			&& sk->packets_out < sk->cong_window) 
+		{
+			/*
+			 *	Add more data to the send queue.
+			 */
+			flag |= 1;
+			tcp_write_xmit(sk);
+		}
+		else if (before(sk->window_seq, sk->write_queue.next->h.seq) &&
+ 			sk->send_head == NULL &&
+ 			sk->ack_backlog == 0 &&
+ 			sk->state != TCP_TIME_WAIT) 
+ 		{
+ 			/*
+ 			 *	Data to queue but no room.
+ 			 */
+ 	        	reset_xmit_timer(sk, TIME_PROBE0, sk->rto);
+ 		}		
+	}
+	else
+	{
+		/*
+		 * from TIME_WAIT we stay in TIME_WAIT as long as we rx packets
+		 * from TCP_CLOSE we don't do anything
+		 *
+		 * from anything else, if there is write data (or fin) pending,
+		 * we use a TIME_WRITE timeout, else if keepalive we reset to
+		 * a KEEPALIVE timeout, else we delete the timer.
+		 *
+		 * We do not set flag for nominal write data, otherwise we may
+		 * force a state where we start to write itsy bitsy tidbits
+		 * of data.
+		 */
+
+		switch(sk->state) {
+		case TCP_TIME_WAIT:
+			/*
+			 * keep us in TIME_WAIT until we stop getting packets,
+			 * reset the timeout.
+			 */
+			reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
+			break;
+		case TCP_CLOSE:
+			/*
+			 * don't touch the timer.
+			 */
+			break;
+		default:
+			/*
+			 * 	Must check send_head, write_queue, and ack_backlog
+			 * 	to determine which timeout to use.
+			 */
+			if (sk->send_head || skb_peek(&sk->write_queue) != NULL || sk->ack_backlog) {
+				reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+			} else if (sk->keepopen) {
+				reset_xmit_timer(sk, TIME_KEEPOPEN, TCP_TIMEOUT_LEN);
+			} else {
+				del_timer(&sk->retransmit_timer);
+				sk->ip_xmit_timeout = 0;
+			}
+			break;
+		}
+	}
+
+	/*
+	 *	We have nothing queued but space to send. Send any partial
+	 *	packets immediately (end of Nagle rule application).
+	 */
+	 
+	if (sk->packets_out == 0 && sk->partial != NULL &&
+		skb_peek(&sk->write_queue) == NULL && sk->send_head == NULL) 
+	{
+		flag |= 1;
+		tcp_send_partial(sk);
+	}
+
+	/*
+	 * In the LAST_ACK case, the other end FIN'd us.  We then FIN'd them, and
+	 * we are now waiting for an acknowledge to our FIN.  The other end is
+	 * already in TIME_WAIT.
+	 *
+	 * Move to TCP_CLOSE on success.
+	 */
+
+	if (sk->state == TCP_LAST_ACK) 
+	{
+		if (!sk->dead)
+			sk->state_change(sk);
+		if(sk->debug)
+			printk("rcv_ack_seq: %lX==%lX, acked_seq: %lX==%lX\n",
+				sk->rcv_ack_seq,sk->write_seq,sk->acked_seq,sk->fin_seq);
+		if (sk->rcv_ack_seq == sk->write_seq /*&& sk->acked_seq == sk->fin_seq*/) 
+		{
+			flag |= 1;
+			tcp_set_state(sk,TCP_CLOSE);
+			sk->shutdown = SHUTDOWN_MASK;
+		}
+	}
+
+	/*
+	 *	Incoming ACK to a FIN we sent in the case of our initiating the close.
+	 *
+	 *	Move to FIN_WAIT2 to await a FIN from the other end. Set
+	 *	SEND_SHUTDOWN but not RCV_SHUTDOWN as data can still be coming in.
+	 */
+
+	if (sk->state == TCP_FIN_WAIT1) 
+	{
+
+		if (!sk->dead) 
+			sk->state_change(sk);
+		if (sk->rcv_ack_seq == sk->write_seq) 
+		{
+			flag |= 1;
+			sk->shutdown |= SEND_SHUTDOWN;
+			tcp_set_state(sk, TCP_FIN_WAIT2);
+		}
+	}
+
+	/*
+	 *	Incoming ACK to a FIN we sent in the case of a simultaneous close.
+	 *
+	 *	Move to TIME_WAIT
+	 */
+
+	if (sk->state == TCP_CLOSING) 
+	{
+
+		if (!sk->dead) 
+			sk->state_change(sk);
+		if (sk->rcv_ack_seq == sk->write_seq) 
+		{
+			flag |= 1;
+			tcp_time_wait(sk);
+		}
+	}
+	
+	/*
+	 *	Final ack of a three way shake 
+	 */
+	 
+	if(sk->state==TCP_SYN_RECV)
+	{
+		tcp_set_state(sk, TCP_ESTABLISHED);
+		tcp_options(sk,th);
+		sk->dummy_th.dest=th->source;
+		sk->copied_seq = sk->acked_seq;
+		if(!sk->dead)
+			sk->state_change(sk);
+		if(sk->max_window==0)
+		{
+			sk->max_window=32;	/* Sanity check */
+			sk->mss=min(sk->max_window,sk->mtu);
+		}
+	}
+	
+	/*
+	 * I make no guarantees about the first clause in the following
+	 * test, i.e. "(!flag) || (flag&4)".  I'm not entirely sure under
+	 * what conditions "!flag" would be true.  However I think the rest
+	 * of the conditions would prevent that from causing any
+	 * unnecessary retransmission. 
+	 *   Clearly if the first packet has expired it should be 
+	 * retransmitted.  The other alternative, "flag&2 && retransmits", is
+	 * harder to explain:  You have to look carefully at how and when the
+	 * timer is set and with what timeout.  The most recent transmission always
+	 * sets the timer.  So in general if the most recent thing has timed
+	 * out, everything before it has as well.  So we want to go ahead and
+	 * retransmit some more.  If we didn't explicitly test for this
+	 * condition with "flag&2 && retransmits", chances are "when + rto < jiffies"
+	 * would not be true.  If you look at the pattern of timing, you can
+	 * show that rto is increased fast enough that the next packet would
+	 * almost never be retransmitted immediately.  Then you'd end up
+	 * waiting for a timeout to send each packet on the retransmission
+	 * queue.  With my implementation of the Karn sampling algorithm,
+	 * the timeout would double each time.  The net result is that it would
+	 * take a hideous amount of time to recover from a single dropped packet.
+	 * It's possible that there should also be a test for TIME_WRITE, but
+	 * I think as long as "send_head != NULL" and "retransmit" is on, we've
+	 * got to be in real retransmission mode.
+	 *   Note that tcp_do_retransmit is called with all==1.  Setting cong_window
+	 * back to 1 at the timeout will cause us to send 1, then 2, etc. packets.
+	 * As long as no further losses occur, this seems reasonable.
+	 */
+	
+	if (((!flag) || (flag&4)) && sk->send_head != NULL &&
+	       (((flag&2) && sk->retransmits) ||
+	       (sk->send_head->when + sk->rto < jiffies))) 
+	{
+		if(sk->send_head->when + sk->rto < jiffies)
+			tcp_retransmit(sk,0);	
+		else
+		{
+			tcp_do_retransmit(sk, 1);
+			reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+		}
+	}
+
+	return(1);
+}
+
+
+/*
+ * 	Process the FIN bit. This now behaves as it is supposed to work
+ *	and the FIN takes effect when it is validly part of sequence
+ *	space. Not before when we get holes.
+ *
+ *	If we are ESTABLISHED, a received fin moves us to CLOSE-WAIT
+ *	(and thence onto LAST-ACK and finally, CLOSE, we never enter
+ *	TIME-WAIT)
+ *
+ *	If we are in FINWAIT-1, a received FIN indicates simultaneous
+ *	close and we go into CLOSING (and later onto TIME-WAIT)
+ *
+ *	If we are in FINWAIT-2, a received FIN moves us to TIME-WAIT.
+ *
+ */
+ 
+static int tcp_fin(struct sk_buff *skb, struct sock *sk, struct tcphdr *th)
+{
+	sk->fin_seq = th->seq + skb->len + th->syn + th->fin;
+
+	if (!sk->dead) 
+	{
+		sk->state_change(sk);
+		sock_wake_async(sk->socket, 1);
+	}
+
+	switch(sk->state) 
+	{
+		case TCP_SYN_RECV:
+		case TCP_SYN_SENT:
+		case TCP_ESTABLISHED:
+			/*
+			 * move to CLOSE_WAIT, tcp_data() already handled
+			 * sending the ack.
+			 */
+			tcp_set_state(sk,TCP_CLOSE_WAIT);
+			if (th->rst)
+				sk->shutdown = SHUTDOWN_MASK;
+			break;
+
+		case TCP_CLOSE_WAIT:
+		case TCP_CLOSING:
+			/*
+			 * received a retransmission of the FIN, do
+			 * nothing.
+			 */
+			break;
+		case TCP_TIME_WAIT:
+			/*
+			 * received a retransmission of the FIN,
+			 * restart the TIME_WAIT timer.
+			 */
+			reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
+			return(0);
+		case TCP_FIN_WAIT1:
+			/*
+			 * This case occurs when a simultaneous close
+			 * happens, we must ack the received FIN and
+			 * enter the CLOSING state.
+			 *
+			 * This causes a WRITE timeout, which will either
+			 * move on to TIME_WAIT when we timeout, or resend
+			 * the FIN properly (maybe we get rid of that annoying
+			 * FIN lost hang). The TIME_WRITE code is already correct
+			 * for handling this timeout.
+			 */
+
+			if(sk->ip_xmit_timeout != TIME_WRITE)
+				reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+			tcp_set_state(sk,TCP_CLOSING);
+			break;
+		case TCP_FIN_WAIT2:
+			/*
+			 * received a FIN -- send ACK and enter TIME_WAIT
+			 */
+			reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
+			sk->shutdown|=SHUTDOWN_MASK;
+			tcp_set_state(sk,TCP_TIME_WAIT);
+			break;
+		case TCP_CLOSE:
+			/*
+			 * already in CLOSE
+			 */
+			break;
+		default:
+			tcp_set_state(sk,TCP_LAST_ACK);
+	
+			/* Start the timers. */
+			reset_msl_timer(sk, TIME_CLOSE, TCP_TIMEWAIT_LEN);
+			return(0);
+	}
+
+	return(0);
+}
+
+
+
+/*
+ *	This routine handles the data.  If there is room in the buffer,
+ *	it will be have already been moved into it.  If there is no
+ *	room, then we will just have to discard the packet.
+ */
+
+extern __inline__ int tcp_data(struct sk_buff *skb, struct sock *sk, 
+	 unsigned long saddr, unsigned short len)
+{
+	struct sk_buff *skb1, *skb2;
+	struct tcphdr *th;
+	int dup_dumped=0;
+	unsigned long new_seq;
+	unsigned long shut_seq;
+
+	th = skb->h.th;
+	skb->len = len -(th->doff*4);
+
+	/*
+	 *	The bytes in the receive read/assembly queue has increased. Needed for the
+	 *	low memory discard algorithm 
+	 */
+	   
+	sk->bytes_rcv += skb->len;
+	
+	if (skb->len == 0 && !th->fin) 
+	{
+		/* 
+		 *	Don't want to keep passing ack's back and forth. 
+		 *	(someone sent us dataless, boring frame)
+		 */
+		if (!th->ack)
+			tcp_send_ack(sk->sent_seq, sk->acked_seq,sk, th, saddr);
+		kfree_skb(skb, FREE_READ);
+		return(0);
+	}
+	
+	/*
+	 *	We no longer have anyone receiving data on this connection.
+	 */
+
+#ifndef TCP_DONT_RST_SHUTDOWN		 
+
+	if(sk->shutdown & RCV_SHUTDOWN)
+	{
+		/*
+		 *	FIXME: BSD has some magic to avoid sending resets to
+		 *	broken 4.2 BSD keepalives. Much to my surprise a few non
+		 *	BSD stacks still have broken keepalives so we want to
+		 *	cope with it.
+		 */
+
+		if(skb->len)	/* We don't care if it's just an ack or
+				   a keepalive/window probe */
+		{
+			new_seq= th->seq + skb->len + th->syn;	/* Right edge of _data_ part of frame */
+			
+			/* Do this the way 4.4BSD treats it. Not what I'd
+			   regard as the meaning of the spec but it's what BSD
+			   does and clearly they know everything 8) */
+
+			/*
+			 *	This is valid because of two things
+			 *
+			 *	a) The way tcp_data behaves at the bottom.
+			 *	b) A fin takes effect when read not when received.
+			 */
+			 
+			shut_seq=sk->acked_seq+1;	/* Last byte */
+			
+			if(after(new_seq,shut_seq))
+			{
+				if(sk->debug)
+					printk("Data arrived on %p after close [Data right edge %lX, Socket shut on %lX] %d\n",
+						sk, new_seq, shut_seq, sk->blog);
+				if(sk->dead)
+				{
+					sk->acked_seq = new_seq + th->fin;
+					tcp_reset(sk->saddr, sk->daddr, skb->h.th,
+						sk->prot, NULL, skb->dev, sk->ip_tos, sk->ip_ttl);
+					tcp_statistics.TcpEstabResets++;
+					tcp_set_state(sk,TCP_CLOSE);
+					sk->err = EPIPE;
+					sk->shutdown = SHUTDOWN_MASK;
+					kfree_skb(skb, FREE_READ);
+					return 0;
+				}
+			}
+		}
+	}
+
+#endif
+
+	/*
+	 * 	Now we have to walk the chain, and figure out where this one
+	 * 	goes into it.  This is set up so that the last packet we received
+	 * 	will be the first one we look at, that way if everything comes
+	 * 	in order, there will be no performance loss, and if they come
+	 * 	out of order we will be able to fit things in nicely.
+	 *
+	 *	[AC: This is wrong. We should assume in order first and then walk
+	 *	 forwards from the first hole based upon real traffic patterns.]
+	 *	
+	 */
+
+	if (skb_peek(&sk->receive_queue) == NULL) 	/* Empty queue is easy case */
+	{
+		skb_queue_head(&sk->receive_queue,skb);
+		skb1= NULL;
+	} 
+	else
+	{
+		for(skb1=sk->receive_queue.prev; ; skb1 = skb1->prev) 
+		{
+			if(sk->debug)
+			{
+				printk("skb1=%p :", skb1);
+				printk("skb1->h.th->seq = %ld: ", skb1->h.th->seq);
+				printk("skb->h.th->seq = %ld\n",skb->h.th->seq);
+				printk("copied_seq = %ld acked_seq = %ld\n", sk->copied_seq,
+						sk->acked_seq);
+			}
+			
+			/*
+			 *	Optimisation: Duplicate frame or extension of previous frame from
+			 *	same sequence point (lost ack case).
+			 *	The frame contains duplicate data or replaces a previous frame
+			 *	discard the previous frame (safe as sk->inuse is set) and put
+			 *	the new one in its place.
+			 */
+			 
+			if (th->seq==skb1->h.th->seq && skb->len>= skb1->len)
+			{
+				skb_append(skb1,skb);
+				skb_unlink(skb1);
+				kfree_skb(skb1,FREE_READ);
+				dup_dumped=1;
+				skb1=NULL;
+				break;
+			}
+			
+			/*
+			 *	Found where it fits
+			 */
+			 
+			if (after(th->seq+1, skb1->h.th->seq))
+			{
+				skb_append(skb1,skb);
+				break;
+			}
+			
+			/*
+			 *	See if we've hit the start. If so insert.
+			 */
+			if (skb1 == skb_peek(&sk->receive_queue))
+			{
+				skb_queue_head(&sk->receive_queue, skb);
+				break;
+			}
+		}
+  	}
+
+	/*
+	 *	Figure out what the ack value for this frame is
+	 */
+	 
+ 	th->ack_seq = th->seq + skb->len;
+ 	if (th->syn) 
+ 		th->ack_seq++;
+ 	if (th->fin)
+ 		th->ack_seq++;
+
+	if (before(sk->acked_seq, sk->copied_seq)) 
+	{
+		printk("*** tcp.c:tcp_data bug acked < copied\n");
+		sk->acked_seq = sk->copied_seq;
+	}
+
+	/*
+	 *	Now figure out if we can ack anything. This is very messy because we really want two
+	 *	receive queues, a completed and an assembly queue. We also want only one transmit
+	 *	queue.
+	 */
+
+	if ((!dup_dumped && (skb1 == NULL || skb1->acked)) || before(th->seq, sk->acked_seq+1)) 
+	{
+		if (before(th->seq, sk->acked_seq+1)) 
+		{
+			int newwindow;
+
+			if (after(th->ack_seq, sk->acked_seq)) 
+			{
+				newwindow = sk->window-(th->ack_seq - sk->acked_seq);
+				if (newwindow < 0)
+					newwindow = 0;	
+				sk->window = newwindow;
+				sk->acked_seq = th->ack_seq;
+			}
+			skb->acked = 1;
+
+			/*
+			 *	When we ack the fin, we do the FIN 
+			 *	processing.
+			 */
+
+			if (skb->h.th->fin) 
+			{
+				tcp_fin(skb,sk,skb->h.th);
+			}
+	  
+			for(skb2 = skb->next;
+			    skb2 != (struct sk_buff *)&sk->receive_queue;
+			    skb2 = skb2->next) 
+			{
+				if (before(skb2->h.th->seq, sk->acked_seq+1)) 
+				{
+					if (after(skb2->h.th->ack_seq, sk->acked_seq))
+					{
+						newwindow = sk->window -
+						 (skb2->h.th->ack_seq - sk->acked_seq);
+						if (newwindow < 0)
+							newwindow = 0;	
+						sk->window = newwindow;
+						sk->acked_seq = skb2->h.th->ack_seq;
+					}
+					skb2->acked = 1;
+					/*
+					 * 	When we ack the fin, we do
+					 * 	the fin handling.
+					 */
+					if (skb2->h.th->fin) 
+					{
+						tcp_fin(skb,sk,skb->h.th);
+					}
+
+					/*
+					 *	Force an immediate ack.
+					 */
+					 
+					sk->ack_backlog = sk->max_ack_backlog;
+				}
+				else
+				{
+					break;
+				}
+			}
+
+			/*
+			 *	This also takes care of updating the window.
+			 *	This if statement needs to be simplified.
+			 */
+			if (!sk->delay_acks ||
+			    sk->ack_backlog >= sk->max_ack_backlog || 
+			    sk->bytes_rcv > sk->max_unacked || th->fin) {
+	/*			tcp_send_ack(sk->sent_seq, sk->acked_seq,sk,th, saddr); */
+			}
+			else 
+			{
+				sk->ack_backlog++;
+				if(sk->debug)
+					printk("Ack queued.\n");
+				reset_xmit_timer(sk, TIME_WRITE, TCP_ACK_TIME);
+			}
+		}
+	}
+
+	/*
+	 *	If we've missed a packet, send an ack.
+	 *	Also start a timer to send another.
+	 */
+	 
+	if (!skb->acked) 
+	{
+	
+	/*
+	 *	This is important.  If we don't have much room left,
+	 *	we need to throw out a few packets so we have a good
+	 *	window.  Note that mtu is used, not mss, because mss is really
+	 *	for the send side.  He could be sending us stuff as large as mtu.
+	 */
+		 
+		while (sk->prot->rspace(sk) < sk->mtu) 
+		{
+			skb1 = skb_peek(&sk->receive_queue);
+			if (skb1 == NULL) 
+			{
+				printk("INET: tcp.c:tcp_data memory leak detected.\n");
+				break;
+			}
+
+			/*
+			 *	Don't throw out something that has been acked. 
+			 */
+		 
+			if (skb1->acked) 
+			{
+				break;
+			}
+		
+			skb_unlink(skb1);
+			kfree_skb(skb1, FREE_READ);
+		}
+		tcp_send_ack(sk->sent_seq, sk->acked_seq, sk, th, saddr);
+		sk->ack_backlog++;
+		reset_xmit_timer(sk, TIME_WRITE, TCP_ACK_TIME);
+	}
+	else
+	{
+		tcp_send_ack(sk->sent_seq, sk->acked_seq, sk, th, saddr);
+	}
+
+	/*
+	 *	Now tell the user we may have some data. 
+	 */
+	 
+	if (!sk->dead) 
+	{
+        	if(sk->debug)
+        		printk("Data wakeup.\n");
+		sk->data_ready(sk,0);
+	} 
+	return(0);
+}
+
+
+/*
+ *	This routine is only called when we have urgent data
+ *	signalled. Its the 'slow' part of tcp_urg. It could be
+ *	moved inline now as tcp_urg is only called from one
+ *	place. We handle URGent data wrong. We have to - as
+ *	BSD still doesn't use the correction from RFC961.
+ */
+ 
+static void tcp_check_urg(struct sock * sk, struct tcphdr * th)
+{
+	unsigned long ptr = ntohs(th->urg_ptr);
+
+	if (ptr)
+		ptr--;
+	ptr += th->seq;
+
+	/* ignore urgent data that we've already seen and read */
+	if (after(sk->copied_seq, ptr))
+		return;
+
+	/* do we already have a newer (or duplicate) urgent pointer? */
+	if (sk->urg_data && !after(ptr, sk->urg_seq))
+		return;
+
+	/* tell the world about our new urgent pointer */
+	if (sk->proc != 0) {
+		if (sk->proc > 0) {
+			kill_proc(sk->proc, SIGURG, 1);
+		} else {
+			kill_pg(-sk->proc, SIGURG, 1);
+		}
+	}
+	sk->urg_data = URG_NOTYET;
+	sk->urg_seq = ptr;
+}
+
+/*
+ *	This is the 'fast' part of urgent handling.
+ */
+ 
+extern __inline__ int tcp_urg(struct sock *sk, struct tcphdr *th,
+	unsigned long saddr, unsigned long len)
+{
+	unsigned long ptr;
+
+	/*
+	 *	Check if we get a new urgent pointer - normally not 
+	 */
+	 
+	if (th->urg)
+		tcp_check_urg(sk,th);
+
+	/*
+	 *	Do we wait for any urgent data? - normally not
+	 */
+	 
+	if (sk->urg_data != URG_NOTYET)
+		return 0;
+
+	/*
+	 *	Is the urgent pointer pointing into this packet? 
+	 */
+	 
+	ptr = sk->urg_seq - th->seq + th->doff*4;
+	if (ptr >= len)
+		return 0;
+
+	/*
+	 *	Ok, got the correct packet, update info 
+	 */
+	 
+	sk->urg_data = URG_VALID | *(ptr + (unsigned char *) th);
+	if (!sk->dead)
+		sk->data_ready(sk,0);
+	return 0;
+}
+
+/*
+ *	This will accept the next outstanding connection. 
+ */
+ 
+static struct sock *tcp_accept(struct sock *sk, int flags)
+{
+	struct sock *newsk;
+	struct sk_buff *skb;
+  
+  /*
+   * We need to make sure that this socket is listening,
+   * and that it has something pending.
+   */
+
+	if (sk->state != TCP_LISTEN) 
+	{
+		sk->err = EINVAL;
+		return(NULL); 
+	}
+
+	/* Avoid the race. */
+	cli();
+	sk->inuse = 1;
+
+	while((skb = tcp_dequeue_established(sk)) == NULL) 
+	{
+		if (flags & O_NONBLOCK) 
+		{
+			sti();
+			release_sock(sk);
+			sk->err = EAGAIN;
+			return(NULL);
+		}
+
+		release_sock(sk);
+		interruptible_sleep_on(sk->sleep);
+		if (current->signal & ~current->blocked) 
+		{
+			sti();
+			sk->err = ERESTARTSYS;
+			return(NULL);
+		}
+		sk->inuse = 1;
+  	}
+	sti();
+
+	/*
+	 *	Now all we need to do is return skb->sk. 
+	 */
+
+	newsk = skb->sk;
+
+	kfree_skb(skb, FREE_READ);
+	sk->ack_backlog--;
+	release_sock(sk);
+	return(newsk);
+}
+
+
+/*
+ *	This will initiate an outgoing connection. 
+ */
+ 
+static int tcp_connect(struct sock *sk, struct sockaddr_in *usin, int addr_len)
+{
+	struct sk_buff *buff;
+	struct device *dev=NULL;
+	unsigned char *ptr;
+	int tmp;
+	int atype;
+	struct tcphdr *t1;
+	struct rtable *rt;
+
+	if (sk->state != TCP_CLOSE) 
+	{
+		return(-EISCONN);
+	}
+	
+	if (addr_len < 8) 
+		return(-EINVAL);
+
+	if (usin->sin_family && usin->sin_family != AF_INET) 
+		return(-EAFNOSUPPORT);
+
+  	/*
+  	 *	connect() to INADDR_ANY means loopback (BSD'ism).
+  	 */
+  	
+  	if(usin->sin_addr.s_addr==INADDR_ANY)
+		usin->sin_addr.s_addr=ip_my_addr();
+		  
+	/*
+	 *	Don't want a TCP connection going to a broadcast address 
+	 */
+
+	if ((atype=ip_chk_addr(usin->sin_addr.s_addr)) == IS_BROADCAST || atype==IS_MULTICAST) 
+		return -ENETUNREACH;
+  
+	sk->inuse = 1;
+	sk->daddr = usin->sin_addr.s_addr;
+	sk->write_seq = tcp_init_seq();
+	sk->window_seq = sk->write_seq;
+	sk->rcv_ack_seq = sk->write_seq -1;
+	sk->err = 0;
+	sk->dummy_th.dest = usin->sin_port;
+	release_sock(sk);
+
+	buff = sk->prot->wmalloc(sk,MAX_SYN_SIZE,0, GFP_KERNEL);
+	if (buff == NULL) 
+	{
+		return(-ENOMEM);
+	}
+	sk->inuse = 1;
+	buff->len = 24;
+	buff->sk = sk;
+	buff->free = 0;
+	buff->localroute = sk->localroute;
+	
+	t1 = (struct tcphdr *) buff->data;
+
+	/*
+	 *	Put in the IP header and routing stuff. 
+	 */
+	 
+	rt=ip_rt_route(sk->daddr, NULL, NULL);
+	
+
+	/*
+	 *	We need to build the routing stuff from the things saved in skb. 
+	 */
+
+	tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
+					IPPROTO_TCP, NULL, MAX_SYN_SIZE,sk->ip_tos,sk->ip_ttl);
+	if (tmp < 0) 
+	{
+		sk->prot->wfree(sk, buff->mem_addr, buff->mem_len);
+		release_sock(sk);
+		return(-ENETUNREACH);
+	}
+
+	buff->len += tmp;
+	t1 = (struct tcphdr *)((char *)t1 +tmp);
+
+	memcpy(t1,(void *)&(sk->dummy_th), sizeof(*t1));
+	t1->seq = ntohl(sk->write_seq++);
+	sk->sent_seq = sk->write_seq;
+	buff->h.seq = sk->write_seq;
+	t1->ack = 0;
+	t1->window = 2;
+	t1->res1=0;
+	t1->res2=0;
+	t1->rst = 0;
+	t1->urg = 0;
+	t1->psh = 0;
+	t1->syn = 1;
+	t1->urg_ptr = 0;
+	t1->doff = 6;
+	/* use 512 or whatever user asked for */
+	
+	if(rt!=NULL && (rt->rt_flags&RTF_WINDOW))
+		sk->window_clamp=rt->rt_window;
+	else
+		sk->window_clamp=0;
+
+	if (sk->user_mss)
+		sk->mtu = sk->user_mss;
+	else if(rt!=NULL && (rt->rt_flags&RTF_MTU))
+		sk->mtu = rt->rt_mss;
+	else 
+	{
+#ifdef CONFIG_INET_SNARL
+		if ((sk->saddr ^ sk->daddr) & default_mask(sk->saddr))
+#else
+		if ((sk->saddr ^ sk->daddr) & dev->pa_mask)
+#endif
+			sk->mtu = 576 - HEADER_SIZE;
+		else
+			sk->mtu = MAX_WINDOW;
+	}
+	/*
+	 *	but not bigger than device MTU 
+	 */
+
+	if(sk->mtu <32)
+		sk->mtu = 32;	/* Sanity limit */
+		
+	sk->mtu = min(sk->mtu, dev->mtu - HEADER_SIZE);
+	
+	/*
+	 *	Put in the TCP options to say MTU. 
+	 */
+
+	ptr = (unsigned char *)(t1+1);
+	ptr[0] = 2;
+	ptr[1] = 4;
+	ptr[2] = (sk->mtu) >> 8;
+	ptr[3] = (sk->mtu) & 0xff;
+	tcp_send_check(t1, sk->saddr, sk->daddr,
+		  sizeof(struct tcphdr) + 4, sk);
+
+	/*
+	 *	This must go first otherwise a really quick response will get reset. 
+	 */
+
+	tcp_set_state(sk,TCP_SYN_SENT);
+	sk->rto = TCP_TIMEOUT_INIT;
+#if 0 /* we already did this */
+	init_timer(&sk->retransmit_timer); 
+#endif
+	sk->retransmit_timer.function=&retransmit_timer;
+	sk->retransmit_timer.data = (unsigned long)sk;
+	reset_xmit_timer(sk, TIME_WRITE, sk->rto);	/* Timer for repeating the SYN until an answer */
+	sk->retransmits = TCP_SYN_RETRIES;
+
+	sk->prot->queue_xmit(sk, dev, buff, 0);  
+	reset_xmit_timer(sk, TIME_WRITE, sk->rto);
+	tcp_statistics.TcpActiveOpens++;
+	tcp_statistics.TcpOutSegs++;
+  
+	release_sock(sk);
+	return(0);
+}
+
+
+/* This functions checks to see if the tcp header is actually acceptable. */
+extern __inline__ int tcp_sequence(struct sock *sk, struct tcphdr *th, short len,
+	     struct options *opt, unsigned long saddr, struct device *dev)
+{
+	unsigned long next_seq;
+
+	next_seq = len - 4*th->doff;
+	if (th->fin)
+		next_seq++;
+	/* if we have a zero window, we can't have any data in the packet.. */
+	if (next_seq && !sk->window)
+		goto ignore_it;
+	next_seq += th->seq;
+
+	/*
+	 * This isn't quite right.  sk->acked_seq could be more recent
+	 * than sk->window.  This is however close enough.  We will accept
+	 * slightly more packets than we should, but it should not cause
+	 * problems unless someone is trying to forge packets.
+	 */
+
+	/* have we already seen all of this packet? */
+	if (!after(next_seq+1, sk->acked_seq))
+		goto ignore_it;
+	/* or does it start beyond the window? */
+	if (!before(th->seq, sk->acked_seq + sk->window + 1))
+		goto ignore_it;
+
+	/* ok, at least part of this packet would seem interesting.. */
+	return 1;
+
+ignore_it:
+	if (th->rst)
+		return 0;
+
+	/*
+	 *	Send a reset if we get something not ours and we are
+	 *	unsynchronized. Note: We don't do anything to our end. We
+	 *	are just killing the bogus remote connection then we will
+	 *	connect again and it will work (with luck).
+	 */
+  	 
+	if (sk->state==TCP_SYN_SENT || sk->state==TCP_SYN_RECV) 
+	{
+		tcp_reset(sk->saddr,sk->daddr,th,sk->prot,NULL,dev, sk->ip_tos,sk->ip_ttl);
+		return 1;
+	}
+
+	/* Try to resync things. */
+	tcp_send_ack(sk->sent_seq, sk->acked_seq, sk, th, saddr);
+	return 0;
+}
+
+/*
+ *	When we get a reset we do this.
+ */
+
+static int tcp_std_reset(struct sock *sk, struct sk_buff *skb)
+{
+	sk->zapped = 1;
+	sk->err = ECONNRESET;
+	if (sk->state == TCP_SYN_SENT)
+		sk->err = ECONNREFUSED;
+	if (sk->state == TCP_CLOSE_WAIT)
+		sk->err = EPIPE;
+#ifdef TCP_DO_RFC1337		
+	/*
+	 *	Time wait assassination protection [RFC1337]
+	 */
+	if(sk->state!=TCP_TIME_WAIT)
+	{	
+		tcp_set_state(sk,TCP_CLOSE);
+		sk->shutdown = SHUTDOWN_MASK;
+	}
+#else	
+	tcp_set_state(sk,TCP_CLOSE);
+	sk->shutdown = SHUTDOWN_MASK;
+#endif	
+	if (!sk->dead) 
+		sk->state_change(sk);
+	kfree_skb(skb, FREE_READ);
+	release_sock(sk);
+	return(0);
+}
+
+/*
+ *	A TCP packet has arrived.
+ */
+ 
+int tcp_rcv(struct sk_buff *skb, struct device *dev, struct options *opt,
+	unsigned long daddr, unsigned short len,
+	unsigned long saddr, int redo, struct inet_protocol * protocol)
+{
+	struct tcphdr *th;
+	struct sock *sk;
+	int syn_ok=0;
+	
+	if (!skb) 
+	{
+		printk("IMPOSSIBLE 1\n");
+		return(0);
+	}
+
+	if (!dev) 
+	{
+		printk("IMPOSSIBLE 2\n");
+		return(0);
+	}
+  
+	tcp_statistics.TcpInSegs++;
+  
+	if(skb->pkt_type!=PACKET_HOST)
+	{
+	  	kfree_skb(skb,FREE_READ);
+	  	return(0);
+	}
+  
+	th = skb->h.th;
+
+	/*
+	 *	Find the socket.
+	 */
+
+	sk = get_sock(&tcp_prot, th->dest, saddr, th->source, daddr);
+
+	/*
+	 *	If this socket has got a reset it's to all intents and purposes 
+  	 *	really dead. Count closed sockets as dead.
+  	 *
+  	 *	Note: BSD appears to have a bug here. A 'closed' TCP in BSD
+  	 *	simply drops data. This seems incorrect as a 'closed' TCP doesn't
+  	 *	exist so should cause resets as if the port was unreachable.
+  	 */
+  	 
+	if (sk!=NULL && (sk->zapped || sk->state==TCP_CLOSE))
+		sk=NULL;
+
+	if (!redo) 
+	{
+		if (tcp_check(th, len, saddr, daddr )) 
+		{
+			skb->sk = NULL;
+			kfree_skb(skb,FREE_READ);
+			/*
+			 *	We don't release the socket because it was
+			 *	never marked in use.
+			 */
+			return(0);
+		}
+		th->seq = ntohl(th->seq);
+
+		/* See if we know about the socket. */
+		if (sk == NULL) 
+		{
+			/*
+			 *	No such TCB. If th->rst is 0 send a reset (checked in tcp_reset)
+			 */
+			tcp_reset(daddr, saddr, th, &tcp_prot, opt,dev,skb->ip_hdr->tos,255);
+			skb->sk = NULL;
+			/*
+			 *	Discard frame
+			 */
+			kfree_skb(skb, FREE_READ);
+			return(0);
+		}
+
+		skb->len = len;
+		skb->acked = 0;
+		skb->used = 0;
+		skb->free = 0;
+		skb->saddr = daddr;
+		skb->daddr = saddr;
+	
+		/* We may need to add it to the backlog here. */
+		cli();
+		if (sk->inuse) 
+		{
+			skb_queue_tail(&sk->back_log, skb);
+			sti();
+			return(0);
+		}
+		sk->inuse = 1;
+		sti();
+	}
+	else
+	{
+		if (sk==NULL) 
+		{
+			tcp_reset(daddr, saddr, th, &tcp_prot, opt,dev,skb->ip_hdr->tos,255);
+			skb->sk = NULL;
+			kfree_skb(skb, FREE_READ);
+			return(0);
+		}
+	}
+
+
+	if (!sk->prot) 
+	{
+		printk("IMPOSSIBLE 3\n");
+		return(0);
+	}
+
+
+	/*
+	 *	Charge the memory to the socket. 
+	 */
+	 
+	if (sk->rmem_alloc + skb->mem_len >= sk->rcvbuf) 
+	{
+		kfree_skb(skb, FREE_READ);
+		release_sock(sk);
+		return(0);
+	}
+
+	skb->sk=sk;
+	sk->rmem_alloc += skb->mem_len;
+
+	/*
+	 *	This basically follows the flow suggested by RFC793, with the corrections in RFC1122. We
+	 *	don't implement precedence and we process URG incorrectly (deliberately so) for BSD bug
+	 *	compatibility. We also set up variables more thoroughly [Karn notes in the
+	 *	KA9Q code the RFC793 incoming segment rules don't initialise the variables for all paths].
+	 */
+
+	if(sk->state!=TCP_ESTABLISHED)		/* Skip this lot for normal flow */
+	{
+	
+		/*
+		 *	Now deal with unusual cases.
+		 */
+	 
+		if(sk->state==TCP_LISTEN)
+		{
+			if(th->ack)	/* These use the socket TOS.. might want to be the received TOS */
+				tcp_reset(daddr,saddr,th,sk->prot,opt,dev,sk->ip_tos, sk->ip_ttl);
+
+			/*
+			 *	We don't care for RST, and non SYN are absorbed (old segments)
+			 *	Broadcast/multicast SYN isn't allowed. Note - bug if you change the
+			 *	netmask on a running connection it can go broadcast. Even Sun's have
+			 *	this problem so I'm ignoring it 
+			 */
+			   
+			if(th->rst || !th->syn || th->ack || ip_chk_addr(daddr)!=IS_MYADDR)
+			{
+				kfree_skb(skb, FREE_READ);
+				release_sock(sk);
+				return 0;
+			}
+		
+			/*	
+			 *	Guess we need to make a new socket up 
+			 */
+		
+			tcp_conn_request(sk, skb, daddr, saddr, opt, dev, tcp_init_seq());
+		
+			/*
+			 *	Now we have several options: In theory there is nothing else
+			 *	in the frame. KA9Q has an option to send data with the syn,
+			 *	BSD accepts data with the syn up to the [to be] advertised window
+			 *	and Solaris 2.1 gives you a protocol error. For now we just ignore
+			 *	it, that fits the spec precisely and avoids incompatibilities. It
+			 *	would be nice in future to drop through and process the data.
+			 */
+			 
+			release_sock(sk);
+			return 0;
+		}
+	
+		/* retransmitted SYN? */
+		if (sk->state == TCP_SYN_RECV && th->syn && th->seq+1 == sk->acked_seq)
+		{
+			kfree_skb(skb, FREE_READ);
+			release_sock(sk);
+			return 0;
+		}
+		
+		/*
+		 *	SYN sent means we have to look for a suitable ack and either reset
+		 *	for bad matches or go to connected 
+		 */
+	   
+		if(sk->state==TCP_SYN_SENT)
+		{
+			/* Crossed SYN or previous junk segment */
+			if(th->ack)
+			{
+				/* We got an ack, but it's not a good ack */
+				if(!tcp_ack(sk,th,saddr,len))
+				{
+					/* Reset the ack - its an ack from a 
+					   different connection  [ th->rst is checked in tcp_reset()] */
+					tcp_statistics.TcpAttemptFails++;
+					tcp_reset(daddr, saddr, th,
+						sk->prot, opt,dev,sk->ip_tos,sk->ip_ttl);
+					kfree_skb(skb, FREE_READ);
+					release_sock(sk);
+					return(0);
+				}
+				if(th->rst)
+					return tcp_std_reset(sk,skb);
+				if(!th->syn)
+				{
+					/* A valid ack from a different connection
+					   start. Shouldn't happen but cover it */
+					kfree_skb(skb, FREE_READ);
+					release_sock(sk);
+					return 0;
+				}
+				/*
+				 *	Ok.. it's good. Set up sequence numbers and
+				 *	move to established.
+				 */
+				syn_ok=1;	/* Don't reset this connection for the syn */
+				sk->acked_seq=th->seq+1;
+				sk->fin_seq=th->seq;
+				tcp_send_ack(sk->sent_seq,sk->acked_seq,sk,th,sk->daddr);
+				tcp_set_state(sk, TCP_ESTABLISHED);
+				tcp_options(sk,th);
+				sk->dummy_th.dest=th->source;
+				sk->copied_seq = sk->acked_seq;
+				if(!sk->dead)
+				{
+					sk->state_change(sk);
+					sock_wake_async(sk->socket, 0);
+				}
+				if(sk->max_window==0)
+				{
+					sk->max_window = 32;
+					sk->mss = min(sk->max_window, sk->mtu);
+				}
+			}
+			else
+			{
+				/* See if SYN's cross. Drop if boring */
+				if(th->syn && !th->rst)
+				{
+					/* Crossed SYN's are fine - but talking to
+					   yourself is right out... */
+					if(sk->saddr==saddr && sk->daddr==daddr &&
+						sk->dummy_th.source==th->source &&
+						sk->dummy_th.dest==th->dest)
+					{
+						tcp_statistics.TcpAttemptFails++;
+						return tcp_std_reset(sk,skb);
+					}
+					tcp_set_state(sk,TCP_SYN_RECV);
+					
+					/*
+					 *	FIXME:
+					 *	Must send SYN|ACK here
+					 */
+				}		
+				/* Discard junk segment */
+				kfree_skb(skb, FREE_READ);
+				release_sock(sk);
+				return 0;
+			}
+			/*
+			 *	SYN_RECV with data maybe.. drop through
+			 */
+			goto rfc_step6;
+		}
+
+	/*
+	 *	BSD has a funny hack with TIME_WAIT and fast reuse of a port. There is
+	 *	a more complex suggestion for fixing these reuse issues in RFC1644
+	 *	but not yet ready for general use. Also see RFC1379.
+	 */
+	
+#define BSD_TIME_WAIT
+#ifdef BSD_TIME_WAIT
+		if (sk->state == TCP_TIME_WAIT && th->syn && sk->dead && 
+			after(th->seq, sk->acked_seq) && !th->rst)
+		{
+			long seq=sk->write_seq;
+			if(sk->debug)
+				printk("Doing a BSD time wait\n");
+			tcp_statistics.TcpEstabResets++;	   
+			sk->rmem_alloc -= skb->mem_len;
+			skb->sk = NULL;
+			sk->err=ECONNRESET;
+			tcp_set_state(sk, TCP_CLOSE);
+			sk->shutdown = SHUTDOWN_MASK;
+			release_sock(sk);
+			sk=get_sock(&tcp_prot, th->dest, saddr, th->source, daddr);
+			if (sk && sk->state==TCP_LISTEN)
+			{
+				sk->inuse=1;
+				skb->sk = sk;
+				sk->rmem_alloc += skb->mem_len;
+				tcp_conn_request(sk, skb, daddr, saddr,opt, dev,seq+128000);
+				release_sock(sk);
+				return 0;
+			}
+			kfree_skb(skb, FREE_READ);
+			return 0;
+		}
+#endif	
+	}
+
+	/*
+	 *	We are now in normal data flow (see the step list in the RFC)
+	 *	Note most of these are inline now. I'll inline the lot when
+	 *	I have time to test it hard and look at what gcc outputs 
+	 */
+	
+	if(!tcp_sequence(sk,th,len,opt,saddr,dev))
+	{
+		kfree_skb(skb, FREE_READ);
+		release_sock(sk);
+		return 0;
+	}
+
+	if(th->rst)
+		return tcp_std_reset(sk,skb);
+	
+	/*
+	 *	!syn_ok is effectively the state test in RFC793.
+	 */
+	 
+	if(th->syn && !syn_ok)
+	{
+		tcp_reset(daddr,saddr,th, &tcp_prot, opt, dev, skb->ip_hdr->tos, 255);
+		return tcp_std_reset(sk,skb);	
+	}
+
+	/*
+	 *	Process the ACK
+	 */
+	 
+
+	if(th->ack && !tcp_ack(sk,th,saddr,len))
+	{
+		/*
+		 *	Our three way handshake failed.
+		 */
+		 
+		if(sk->state==TCP_SYN_RECV)
+		{
+			tcp_reset(daddr, saddr, th,sk->prot, opt, dev,sk->ip_tos,sk->ip_ttl);
+		}
+		kfree_skb(skb, FREE_READ);
+		release_sock(sk);
+		return 0;
+	}
+	
+rfc_step6:		/* I'll clean this up later */
+
+	/*
+	 *	Process urgent data
+	 */
+	 	
+	if(tcp_urg(sk, th, saddr, len))
+	{
+		kfree_skb(skb, FREE_READ);
+		release_sock(sk);
+		return 0;
+	}
+	
+	
+	/*
+	 *	Process the encapsulated data
+	 */
+	
+	if(tcp_data(skb,sk, saddr, len))
+	{
+		kfree_skb(skb, FREE_READ);
+		release_sock(sk);
+		return 0;
+	}
+
+	/*
+	 *	And done
+	 */	
+	
+	release_sock(sk);
+	return 0;
+}
+
+/*
+ *	This routine sends a packet with an out of date sequence
+ *	number. It assumes the other end will try to ack it.
+ */
+
+static void tcp_write_wakeup(struct sock *sk)
+{
+	struct sk_buff *buff;
+	struct tcphdr *t1;
+	struct device *dev=NULL;
+	int tmp;
+
+	if (sk->zapped)
+		return;	/* After a valid reset we can send no more */
+
+	/*
+	 *	Write data can still be transmitted/retransmitted in the
+	 *	following states.  If any other state is encountered, return.
+	 *	[listen/close will never occur here anyway]
+	 */
+
+	if (sk->state != TCP_ESTABLISHED && 
+	    sk->state != TCP_CLOSE_WAIT &&
+	    sk->state != TCP_FIN_WAIT1 && 
+	    sk->state != TCP_LAST_ACK &&
+	    sk->state != TCP_CLOSING
+	) 
+	{
+		return;
+	}
+
+	buff = sk->prot->wmalloc(sk,MAX_ACK_SIZE,1, GFP_ATOMIC);
+	if (buff == NULL) 
+		return;
+
+	buff->len = sizeof(struct tcphdr);
+	buff->free = 1;
+	buff->sk = sk;
+	buff->localroute = sk->localroute;
+
+	t1 = (struct tcphdr *) buff->data;
+
+	/* Put in the IP header and routing stuff. */
+	tmp = sk->prot->build_header(buff, sk->saddr, sk->daddr, &dev,
+				IPPROTO_TCP, sk->opt, MAX_ACK_SIZE,sk->ip_tos,sk->ip_ttl);
+	if (tmp < 0) 
+	{
+		sk->prot->wfree(sk, buff->mem_addr, buff->mem_len);
+		return;
+	}
+
+	buff->len += tmp;
+	t1 = (struct tcphdr *)((char *)t1 +tmp);
+
+	memcpy(t1,(void *) &sk->dummy_th, sizeof(*t1));
+
+	/*
+	 *	Use a previous sequence.
+	 *	This should cause the other end to send an ack.
+	 */
+	 
+	t1->seq = htonl(sk->sent_seq-1);
+	t1->ack = 1; 
+	t1->res1= 0;
+	t1->res2= 0;
+	t1->rst = 0;
+	t1->urg = 0;
+	t1->psh = 0;
+	t1->fin = 0;	/* We are sending a 'previous' sequence, and 0 bytes of data - thus no FIN bit */
+	t1->syn = 0;
+	t1->ack_seq = ntohl(sk->acked_seq);
+	t1->window = ntohs(tcp_select_window(sk));
+	t1->doff = sizeof(*t1)/4;
+	tcp_send_check(t1, sk->saddr, sk->daddr, sizeof(*t1), sk);
+	 /*
+	  *	Send it and free it.
+   	  *	This will prevent the timer from automatically being restarted.
+	  */
+	sk->prot->queue_xmit(sk, dev, buff, 1);
+	tcp_statistics.TcpOutSegs++;
+}
+
+/*
+ *	A window probe timeout has occurred.
+ */
+
+void tcp_send_probe0(struct sock *sk)
+{
+	if (sk->zapped)
+		return;		/* After a valid reset we can send no more */
+
+	tcp_write_wakeup(sk);
+
+	sk->backoff++;
+	sk->rto = min(sk->rto << 1, 120*HZ);
+	reset_xmit_timer (sk, TIME_PROBE0, sk->rto);
+	sk->retransmits++;
+	sk->prot->retransmits ++;
+}
+
+/*
+ *	Socket option code for TCP. 
+ */
+  
+int tcp_setsockopt(struct sock *sk, int level, int optname, char *optval, int optlen)
+{
+	int val,err;
+
+	if(level!=SOL_TCP)
+		return ip_setsockopt(sk,level,optname,optval,optlen);
+
+  	if (optval == NULL) 
+  		return(-EINVAL);
+
+  	err=verify_area(VERIFY_READ, optval, sizeof(int));
+  	if(err)
+  		return err;
+  	
+  	val = get_fs_long((unsigned long *)optval);
+
+	switch(optname)
+	{
+		case TCP_MAXSEG:
+/*
+ * values greater than interface MTU won't take effect.  however at
+ * the point when this call is done we typically don't yet know
+ * which interface is going to be used
+ */
+	  		if(val<1||val>MAX_WINDOW)
+				return -EINVAL;
+			sk->user_mss=val;
+			return 0;
+		case TCP_NODELAY:
+			sk->nonagle=(val==0)?0:1;
+			return 0;
+		default:
+			return(-ENOPROTOOPT);
+	}
+}
+
+int tcp_getsockopt(struct sock *sk, int level, int optname, char *optval, int *optlen)
+{
+	int val,err;
+
+	if(level!=SOL_TCP)
+		return ip_getsockopt(sk,level,optname,optval,optlen);
+			
+	switch(optname)
+	{
+		case TCP_MAXSEG:
+			val=sk->user_mss;
+			break;
+		case TCP_NODELAY:
+			val=sk->nonagle;
+			break;
+		default:
+			return(-ENOPROTOOPT);
+	}
+	err=verify_area(VERIFY_WRITE, optlen, sizeof(int));
+	if(err)
+  		return err;
+  	put_fs_long(sizeof(int),(unsigned long *) optlen);
+
+  	err=verify_area(VERIFY_WRITE, optval, sizeof(int));
+  	if(err)
+  		return err;
+  	put_fs_long(val,(unsigned long *)optval);
+
+  	return(0);
+}	
+
+
+struct proto tcp_prot = {
+	sock_wmalloc,
+	sock_rmalloc,
+	sock_wfree,
+	sock_rfree,
+	sock_rspace,
+	sock_wspace,
+	tcp_close,
+	tcp_read,
+	tcp_write,
+	tcp_sendto,
+	tcp_recvfrom,
+	ip_build_header,
+	tcp_connect,
+	tcp_accept,
+	ip_queue_xmit,
+	tcp_retransmit,
+	tcp_write_wakeup,
+	tcp_read_wakeup,
+	tcp_rcv,
+	tcp_select,
+	tcp_ioctl,
+	NULL,
+	tcp_shutdown,
+	tcp_setsockopt,
+	tcp_getsockopt,
+	128,
+	0,
+	{NULL,},
+	"TCP",
+	0, 0
+};