Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 2663 insertions, 0 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
new file mode 100644
index 0000000..3ac6659
--- /dev/null
+++ b/net/ipv4/tcp_ipv4.c
@@ -0,0 +1,2663 @@
+/*
+ * 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:	$Id: tcp_ipv4.c,v 1.240 2002/02/01 22:01:04 davem Exp $
+ *
+ *		IPv4 specific functions
+ *
+ *
+ *		code split from:
+ *		linux/ipv4/tcp.c
+ *		linux/ipv4/tcp_input.c
+ *		linux/ipv4/tcp_output.c
+ *
+ *		See tcp.c for author information
+ *
+ *	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.
+ */
+
+/*
+ * Changes:
+ *		David S. Miller	:	New socket lookup architecture.
+ *					This code is dedicated to John Dyson.
+ *		David S. Miller :	Change semantics of established hash,
+ *					half is devoted to TIME_WAIT sockets
+ *					and the rest go in the other half.
+ *		Andi Kleen :		Add support for syncookies and fixed
+ *					some bugs: ip options weren't passed to
+ *					the TCP layer, missed a check for an
+ *					ACK bit.
+ *		Andi Kleen :		Implemented fast path mtu discovery.
+ *	     				Fixed many serious bugs in the
+ *					open_request handling and moved
+ *					most of it into the af independent code.
+ *					Added tail drop and some other bugfixes.
+ *					Added new listen sematics.
+ *		Mike McLagan	:	Routing by source
+ *	Juan Jose Ciarlante:		ip_dynaddr bits
+ *		Andi Kleen:		various fixes.
+ *	Vitaly E. Lavrov	:	Transparent proxy revived after year
+ *					coma.
+ *	Andi Kleen		:	Fix new listen.
+ *	Andi Kleen		:	Fix accept error reporting.
+ *	YOSHIFUJI Hideaki @USAGI and:	Support IPV6_V6ONLY socket option, which
+ *	Alexey Kuznetsov		allow both IPv4 and IPv6 sockets to bind
+ *					a single port at the same time.
+ */
+
+#include <linux/config.h>
+
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/cache.h>
+#include <linux/jhash.h>
+#include <linux/init.h>
+#include <linux/times.h>
+
+#include <net/icmp.h>
+#include <net/tcp.h>
+#include <net/ipv6.h>
+#include <net/inet_common.h>
+#include <net/xfrm.h>
+
+#include <linux/inet.h>
+#include <linux/ipv6.h>
+#include <linux/stddef.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+extern int sysctl_ip_dynaddr;
+int sysctl_tcp_tw_reuse;
+int sysctl_tcp_low_latency;
+
+/* Check TCP sequence numbers in ICMP packets. */
+#define ICMP_MIN_LENGTH 8
+
+/* Socket used for sending RSTs */
+static struct socket *tcp_socket;
+
+void tcp_v4_send_check(struct sock *sk, struct tcphdr *th, int len,
+		       struct sk_buff *skb);
+
+struct tcp_hashinfo __cacheline_aligned tcp_hashinfo = {
+	.__tcp_lhash_lock	=	RW_LOCK_UNLOCKED,
+	.__tcp_lhash_users	=	ATOMIC_INIT(0),
+	.__tcp_lhash_wait
+	  = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.__tcp_lhash_wait),
+	.__tcp_portalloc_lock	=	SPIN_LOCK_UNLOCKED
+};
+
+/*
+ * This array holds the first and last local port number.
+ * For high-usage systems, use sysctl to change this to
+ * 32768-61000
+ */
+int sysctl_local_port_range[2] = { 1024, 4999 };
+int tcp_port_rover = 1024 - 1;
+
+static __inline__ int tcp_hashfn(__u32 laddr, __u16 lport,
+				 __u32 faddr, __u16 fport)
+{
+	int h = (laddr ^ lport) ^ (faddr ^ fport);
+	h ^= h >> 16;
+	h ^= h >> 8;
+	return h & (tcp_ehash_size - 1);
+}
+
+static __inline__ int tcp_sk_hashfn(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	__u32 laddr = inet->rcv_saddr;
+	__u16 lport = inet->num;
+	__u32 faddr = inet->daddr;
+	__u16 fport = inet->dport;
+
+	return tcp_hashfn(laddr, lport, faddr, fport);
+}
+
+/* Allocate and initialize a new TCP local port bind bucket.
+ * The bindhash mutex for snum's hash chain must be held here.
+ */
+struct tcp_bind_bucket *tcp_bucket_create(struct tcp_bind_hashbucket *head,
+					  unsigned short snum)
+{
+	struct tcp_bind_bucket *tb = kmem_cache_alloc(tcp_bucket_cachep,
+						      SLAB_ATOMIC);
+	if (tb) {
+		tb->port = snum;
+		tb->fastreuse = 0;
+		INIT_HLIST_HEAD(&tb->owners);
+		hlist_add_head(&tb->node, &head->chain);
+	}
+	return tb;
+}
+
+/* Caller must hold hashbucket lock for this tb with local BH disabled */
+void tcp_bucket_destroy(struct tcp_bind_bucket *tb)
+{
+	if (hlist_empty(&tb->owners)) {
+		__hlist_del(&tb->node);
+		kmem_cache_free(tcp_bucket_cachep, tb);
+	}
+}
+
+/* Caller must disable local BH processing. */
+static __inline__ void __tcp_inherit_port(struct sock *sk, struct sock *child)
+{
+	struct tcp_bind_hashbucket *head =
+				&tcp_bhash[tcp_bhashfn(inet_sk(child)->num)];
+	struct tcp_bind_bucket *tb;
+
+	spin_lock(&head->lock);
+	tb = tcp_sk(sk)->bind_hash;
+	sk_add_bind_node(child, &tb->owners);
+	tcp_sk(child)->bind_hash = tb;
+	spin_unlock(&head->lock);
+}
+
+inline void tcp_inherit_port(struct sock *sk, struct sock *child)
+{
+	local_bh_disable();
+	__tcp_inherit_port(sk, child);
+	local_bh_enable();
+}
+
+void tcp_bind_hash(struct sock *sk, struct tcp_bind_bucket *tb,
+		   unsigned short snum)
+{
+	inet_sk(sk)->num = snum;
+	sk_add_bind_node(sk, &tb->owners);
+	tcp_sk(sk)->bind_hash = tb;
+}
+
+static inline int tcp_bind_conflict(struct sock *sk, struct tcp_bind_bucket *tb)
+{
+	const u32 sk_rcv_saddr = tcp_v4_rcv_saddr(sk);
+	struct sock *sk2;
+	struct hlist_node *node;
+	int reuse = sk->sk_reuse;
+
+	sk_for_each_bound(sk2, node, &tb->owners) {
+		if (sk != sk2 &&
+		    !tcp_v6_ipv6only(sk2) &&
+		    (!sk->sk_bound_dev_if ||
+		     !sk2->sk_bound_dev_if ||
+		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
+			if (!reuse || !sk2->sk_reuse ||
+			    sk2->sk_state == TCP_LISTEN) {
+				const u32 sk2_rcv_saddr = tcp_v4_rcv_saddr(sk2);
+				if (!sk2_rcv_saddr || !sk_rcv_saddr ||
+				    sk2_rcv_saddr == sk_rcv_saddr)
+					break;
+			}
+		}
+	}
+	return node != NULL;
+}
+
+/* Obtain a reference to a local port for the given sock,
+ * if snum is zero it means select any available local port.
+ */
+static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
+{
+	struct tcp_bind_hashbucket *head;
+	struct hlist_node *node;
+	struct tcp_bind_bucket *tb;
+	int ret;
+
+	local_bh_disable();
+	if (!snum) {
+		int low = sysctl_local_port_range[0];
+		int high = sysctl_local_port_range[1];
+		int remaining = (high - low) + 1;
+		int rover;
+
+		spin_lock(&tcp_portalloc_lock);
+		rover = tcp_port_rover;
+		do {
+			rover++;
+			if (rover < low || rover > high)
+				rover = low;
+			head = &tcp_bhash[tcp_bhashfn(rover)];
+			spin_lock(&head->lock);
+			tb_for_each(tb, node, &head->chain)
+				if (tb->port == rover)
+					goto next;
+			break;
+		next:
+			spin_unlock(&head->lock);
+		} while (--remaining > 0);
+		tcp_port_rover = rover;
+		spin_unlock(&tcp_portalloc_lock);
+
+		/* Exhausted local port range during search? */
+		ret = 1;
+		if (remaining <= 0)
+			goto fail;
+
+		/* OK, here is the one we will use.  HEAD is
+		 * non-NULL and we hold it's mutex.
+		 */
+		snum = rover;
+	} else {
+		head = &tcp_bhash[tcp_bhashfn(snum)];
+		spin_lock(&head->lock);
+		tb_for_each(tb, node, &head->chain)
+			if (tb->port == snum)
+				goto tb_found;
+	}
+	tb = NULL;
+	goto tb_not_found;
+tb_found:
+	if (!hlist_empty(&tb->owners)) {
+		if (sk->sk_reuse > 1)
+			goto success;
+		if (tb->fastreuse > 0 &&
+		    sk->sk_reuse && sk->sk_state != TCP_LISTEN) {
+			goto success;
+		} else {
+			ret = 1;
+			if (tcp_bind_conflict(sk, tb))
+				goto fail_unlock;
+		}
+	}
+tb_not_found:
+	ret = 1;
+	if (!tb && (tb = tcp_bucket_create(head, snum)) == NULL)
+		goto fail_unlock;
+	if (hlist_empty(&tb->owners)) {
+		if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
+			tb->fastreuse = 1;
+		else
+			tb->fastreuse = 0;
+	} else if (tb->fastreuse &&
+		   (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
+		tb->fastreuse = 0;
+success:
+	if (!tcp_sk(sk)->bind_hash)
+		tcp_bind_hash(sk, tb, snum);
+	BUG_TRAP(tcp_sk(sk)->bind_hash == tb);
+ 	ret = 0;
+
+fail_unlock:
+	spin_unlock(&head->lock);
+fail:
+	local_bh_enable();
+	return ret;
+}
+
+/* Get rid of any references to a local port held by the
+ * given sock.
+ */
+static void __tcp_put_port(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct tcp_bind_hashbucket *head = &tcp_bhash[tcp_bhashfn(inet->num)];
+	struct tcp_bind_bucket *tb;
+
+	spin_lock(&head->lock);
+	tb = tcp_sk(sk)->bind_hash;
+	__sk_del_bind_node(sk);
+	tcp_sk(sk)->bind_hash = NULL;
+	inet->num = 0;
+	tcp_bucket_destroy(tb);
+	spin_unlock(&head->lock);
+}
+
+void tcp_put_port(struct sock *sk)
+{
+	local_bh_disable();
+	__tcp_put_port(sk);
+	local_bh_enable();
+}
+
+/* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
+ * Look, when several writers sleep and reader wakes them up, all but one
+ * immediately hit write lock and grab all the cpus. Exclusive sleep solves
+ * this, _but_ remember, it adds useless work on UP machines (wake up each
+ * exclusive lock release). It should be ifdefed really.
+ */
+
+void tcp_listen_wlock(void)
+{
+	write_lock(&tcp_lhash_lock);
+
+	if (atomic_read(&tcp_lhash_users)) {
+		DEFINE_WAIT(wait);
+
+		for (;;) {
+			prepare_to_wait_exclusive(&tcp_lhash_wait,
+						&wait, TASK_UNINTERRUPTIBLE);
+			if (!atomic_read(&tcp_lhash_users))
+				break;
+			write_unlock_bh(&tcp_lhash_lock);
+			schedule();
+			write_lock_bh(&tcp_lhash_lock);
+		}
+
+		finish_wait(&tcp_lhash_wait, &wait);
+	}
+}
+
+static __inline__ void __tcp_v4_hash(struct sock *sk, const int listen_possible)
+{
+	struct hlist_head *list;
+	rwlock_t *lock;
+
+	BUG_TRAP(sk_unhashed(sk));
+	if (listen_possible && sk->sk_state == TCP_LISTEN) {
+		list = &tcp_listening_hash[tcp_sk_listen_hashfn(sk)];
+		lock = &tcp_lhash_lock;
+		tcp_listen_wlock();
+	} else {
+		list = &tcp_ehash[(sk->sk_hashent = tcp_sk_hashfn(sk))].chain;
+		lock = &tcp_ehash[sk->sk_hashent].lock;
+		write_lock(lock);
+	}
+	__sk_add_node(sk, list);
+	sock_prot_inc_use(sk->sk_prot);
+	write_unlock(lock);
+	if (listen_possible && sk->sk_state == TCP_LISTEN)
+		wake_up(&tcp_lhash_wait);
+}
+
+static void tcp_v4_hash(struct sock *sk)
+{
+	if (sk->sk_state != TCP_CLOSE) {
+		local_bh_disable();
+		__tcp_v4_hash(sk, 1);
+		local_bh_enable();
+	}
+}
+
+void tcp_unhash(struct sock *sk)
+{
+	rwlock_t *lock;
+
+	if (sk_unhashed(sk))
+		goto ende;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		local_bh_disable();
+		tcp_listen_wlock();
+		lock = &tcp_lhash_lock;
+	} else {
+		struct tcp_ehash_bucket *head = &tcp_ehash[sk->sk_hashent];
+		lock = &head->lock;
+		write_lock_bh(&head->lock);
+	}
+
+	if (__sk_del_node_init(sk))
+		sock_prot_dec_use(sk->sk_prot);
+	write_unlock_bh(lock);
+
+ ende:
+	if (sk->sk_state == TCP_LISTEN)
+		wake_up(&tcp_lhash_wait);
+}
+
+/* Don't inline this cruft.  Here are some nice properties to
+ * exploit here.  The BSD API does not allow a listening TCP
+ * to specify the remote port nor the remote address for the
+ * connection.  So always assume those are both wildcarded
+ * during the search since they can never be otherwise.
+ */
+static struct sock *__tcp_v4_lookup_listener(struct hlist_head *head, u32 daddr,
+					     unsigned short hnum, int dif)
+{
+	struct sock *result = NULL, *sk;
+	struct hlist_node *node;
+	int score, hiscore;
+
+	hiscore=-1;
+	sk_for_each(sk, node, head) {
+		struct inet_sock *inet = inet_sk(sk);
+
+		if (inet->num == hnum && !ipv6_only_sock(sk)) {
+			__u32 rcv_saddr = inet->rcv_saddr;
+
+			score = (sk->sk_family == PF_INET ? 1 : 0);
+			if (rcv_saddr) {
+				if (rcv_saddr != daddr)
+					continue;
+				score+=2;
+			}
+			if (sk->sk_bound_dev_if) {
+				if (sk->sk_bound_dev_if != dif)
+					continue;
+				score+=2;
+			}
+			if (score == 5)
+				return sk;
+			if (score > hiscore) {
+				hiscore = score;
+				result = sk;
+			}
+		}
+	}
+	return result;
+}
+
+/* Optimize the common listener case. */
+static inline struct sock *tcp_v4_lookup_listener(u32 daddr,
+		unsigned short hnum, int dif)
+{
+	struct sock *sk = NULL;
+	struct hlist_head *head;
+
+	read_lock(&tcp_lhash_lock);
+	head = &tcp_listening_hash[tcp_lhashfn(hnum)];
+	if (!hlist_empty(head)) {
+		struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
+
+		if (inet->num == hnum && !sk->sk_node.next &&
+		    (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
+		    (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
+		    !sk->sk_bound_dev_if)
+			goto sherry_cache;
+		sk = __tcp_v4_lookup_listener(head, daddr, hnum, dif);
+	}
+	if (sk) {
+sherry_cache:
+		sock_hold(sk);
+	}
+	read_unlock(&tcp_lhash_lock);
+	return sk;
+}
+
+/* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
+ * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
+ *
+ * Local BH must be disabled here.
+ */
+
+static inline struct sock *__tcp_v4_lookup_established(u32 saddr, u16 sport,
+						       u32 daddr, u16 hnum,
+						       int dif)
+{
+	struct tcp_ehash_bucket *head;
+	TCP_V4_ADDR_COOKIE(acookie, saddr, daddr)
+	__u32 ports = TCP_COMBINED_PORTS(sport, hnum);
+	struct sock *sk;
+	struct hlist_node *node;
+	/* Optimize here for direct hit, only listening connections can
+	 * have wildcards anyways.
+	 */
+	int hash = tcp_hashfn(daddr, hnum, saddr, sport);
+	head = &tcp_ehash[hash];
+	read_lock(&head->lock);
+	sk_for_each(sk, node, &head->chain) {
+		if (TCP_IPV4_MATCH(sk, acookie, saddr, daddr, ports, dif))
+			goto hit; /* You sunk my battleship! */
+	}
+
+	/* Must check for a TIME_WAIT'er before going to listener hash. */
+	sk_for_each(sk, node, &(head + tcp_ehash_size)->chain) {
+		if (TCP_IPV4_TW_MATCH(sk, acookie, saddr, daddr, ports, dif))
+			goto hit;
+	}
+	sk = NULL;
+out:
+	read_unlock(&head->lock);
+	return sk;
+hit:
+	sock_hold(sk);
+	goto out;
+}
+
+static inline struct sock *__tcp_v4_lookup(u32 saddr, u16 sport,
+					   u32 daddr, u16 hnum, int dif)
+{
+	struct sock *sk = __tcp_v4_lookup_established(saddr, sport,
+						      daddr, hnum, dif);
+
+	return sk ? : tcp_v4_lookup_listener(daddr, hnum, dif);
+}
+
+inline struct sock *tcp_v4_lookup(u32 saddr, u16 sport, u32 daddr,
+				  u16 dport, int dif)
+{
+	struct sock *sk;
+
+	local_bh_disable();
+	sk = __tcp_v4_lookup(saddr, sport, daddr, ntohs(dport), dif);
+	local_bh_enable();
+
+	return sk;
+}
+
+EXPORT_SYMBOL_GPL(tcp_v4_lookup);
+
+static inline __u32 tcp_v4_init_sequence(struct sock *sk, struct sk_buff *skb)
+{
+	return secure_tcp_sequence_number(skb->nh.iph->daddr,
+					  skb->nh.iph->saddr,
+					  skb->h.th->dest,
+					  skb->h.th->source);
+}
+
+/* called with local bh disabled */
+static int __tcp_v4_check_established(struct sock *sk, __u16 lport,
+				      struct tcp_tw_bucket **twp)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	u32 daddr = inet->rcv_saddr;
+	u32 saddr = inet->daddr;
+	int dif = sk->sk_bound_dev_if;
+	TCP_V4_ADDR_COOKIE(acookie, saddr, daddr)
+	__u32 ports = TCP_COMBINED_PORTS(inet->dport, lport);
+	int hash = tcp_hashfn(daddr, lport, saddr, inet->dport);
+	struct tcp_ehash_bucket *head = &tcp_ehash[hash];
+	struct sock *sk2;
+	struct hlist_node *node;
+	struct tcp_tw_bucket *tw;
+
+	write_lock(&head->lock);
+
+	/* Check TIME-WAIT sockets first. */
+	sk_for_each(sk2, node, &(head + tcp_ehash_size)->chain) {
+		tw = (struct tcp_tw_bucket *)sk2;
+
+		if (TCP_IPV4_TW_MATCH(sk2, acookie, saddr, daddr, ports, dif)) {
+			struct tcp_sock *tp = tcp_sk(sk);
+
+			/* With PAWS, it is safe from the viewpoint
+			   of data integrity. Even without PAWS it
+			   is safe provided sequence spaces do not
+			   overlap i.e. at data rates <= 80Mbit/sec.
+
+			   Actually, the idea is close to VJ's one,
+			   only timestamp cache is held not per host,
+			   but per port pair and TW bucket is used
+			   as state holder.
+
+			   If TW bucket has been already destroyed we
+			   fall back to VJ's scheme and use initial
+			   timestamp retrieved from peer table.
+			 */
+			if (tw->tw_ts_recent_stamp &&
+			    (!twp || (sysctl_tcp_tw_reuse &&
+				      xtime.tv_sec -
+				      tw->tw_ts_recent_stamp > 1))) {
+				if ((tp->write_seq =
+						tw->tw_snd_nxt + 65535 + 2) == 0)
+					tp->write_seq = 1;
+				tp->rx_opt.ts_recent	   = tw->tw_ts_recent;
+				tp->rx_opt.ts_recent_stamp = tw->tw_ts_recent_stamp;
+				sock_hold(sk2);
+				goto unique;
+			} else
+				goto not_unique;
+		}
+	}
+	tw = NULL;
+
+	/* And established part... */
+	sk_for_each(sk2, node, &head->chain) {
+		if (TCP_IPV4_MATCH(sk2, acookie, saddr, daddr, ports, dif))
+			goto not_unique;
+	}
+
+unique:
+	/* Must record num and sport now. Otherwise we will see
+	 * in hash table socket with a funny identity. */
+	inet->num = lport;
+	inet->sport = htons(lport);
+	sk->sk_hashent = hash;
+	BUG_TRAP(sk_unhashed(sk));
+	__sk_add_node(sk, &head->chain);
+	sock_prot_inc_use(sk->sk_prot);
+	write_unlock(&head->lock);
+
+	if (twp) {
+		*twp = tw;
+		NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
+	} else if (tw) {
+		/* Silly. Should hash-dance instead... */
+		tcp_tw_deschedule(tw);
+		NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
+
+		tcp_tw_put(tw);
+	}
+
+	return 0;
+
+not_unique:
+	write_unlock(&head->lock);
+	return -EADDRNOTAVAIL;
+}
+
+static inline u32 connect_port_offset(const struct sock *sk)
+{
+	const struct inet_sock *inet = inet_sk(sk);
+
+	return secure_tcp_port_ephemeral(inet->rcv_saddr, inet->daddr, 
+					 inet->dport);
+}
+
+/*
+ * Bind a port for a connect operation and hash it.
+ */
+static inline int tcp_v4_hash_connect(struct sock *sk)
+{
+	unsigned short snum = inet_sk(sk)->num;
+ 	struct tcp_bind_hashbucket *head;
+ 	struct tcp_bind_bucket *tb;
+	int ret;
+
+ 	if (!snum) {
+ 		int low = sysctl_local_port_range[0];
+ 		int high = sysctl_local_port_range[1];
+		int range = high - low;
+ 		int i;
+		int port;
+		static u32 hint;
+		u32 offset = hint + connect_port_offset(sk);
+		struct hlist_node *node;
+ 		struct tcp_tw_bucket *tw = NULL;
+
+ 		local_bh_disable();
+		for (i = 1; i <= range; i++) {
+			port = low + (i + offset) % range;
+ 			head = &tcp_bhash[tcp_bhashfn(port)];
+ 			spin_lock(&head->lock);
+
+ 			/* Does not bother with rcv_saddr checks,
+ 			 * because the established check is already
+ 			 * unique enough.
+ 			 */
+			tb_for_each(tb, node, &head->chain) {
+ 				if (tb->port == port) {
+ 					BUG_TRAP(!hlist_empty(&tb->owners));
+ 					if (tb->fastreuse >= 0)
+ 						goto next_port;
+ 					if (!__tcp_v4_check_established(sk,
+									port,
+									&tw))
+ 						goto ok;
+ 					goto next_port;
+ 				}
+ 			}
+
+ 			tb = tcp_bucket_create(head, port);
+ 			if (!tb) {
+ 				spin_unlock(&head->lock);
+ 				break;
+ 			}
+ 			tb->fastreuse = -1;
+ 			goto ok;
+
+ 		next_port:
+ 			spin_unlock(&head->lock);
+ 		}
+ 		local_bh_enable();
+
+ 		return -EADDRNOTAVAIL;
+
+ok:
+		hint += i;
+
+ 		/* Head lock still held and bh's disabled */
+ 		tcp_bind_hash(sk, tb, port);
+		if (sk_unhashed(sk)) {
+ 			inet_sk(sk)->sport = htons(port);
+ 			__tcp_v4_hash(sk, 0);
+ 		}
+ 		spin_unlock(&head->lock);
+
+ 		if (tw) {
+ 			tcp_tw_deschedule(tw);
+ 			tcp_tw_put(tw);
+ 		}
+
+		ret = 0;
+		goto out;
+ 	}
+
+ 	head  = &tcp_bhash[tcp_bhashfn(snum)];
+ 	tb  = tcp_sk(sk)->bind_hash;
+	spin_lock_bh(&head->lock);
+	if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
+		__tcp_v4_hash(sk, 0);
+		spin_unlock_bh(&head->lock);
+		return 0;
+	} else {
+		spin_unlock(&head->lock);
+		/* No definite answer... Walk to established hash table */
+		ret = __tcp_v4_check_established(sk, snum, NULL);
+out:
+		local_bh_enable();
+		return ret;
+	}
+}
+
+/* This will initiate an outgoing connection. */
+int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sockaddr_in *usin = (struct sockaddr_in *)uaddr;
+	struct rtable *rt;
+	u32 daddr, nexthop;
+	int tmp;
+	int err;
+
+	if (addr_len < sizeof(struct sockaddr_in))
+		return -EINVAL;
+
+	if (usin->sin_family != AF_INET)
+		return -EAFNOSUPPORT;
+
+	nexthop = daddr = usin->sin_addr.s_addr;
+	if (inet->opt && inet->opt->srr) {
+		if (!daddr)
+			return -EINVAL;
+		nexthop = inet->opt->faddr;
+	}
+
+	tmp = ip_route_connect(&rt, nexthop, inet->saddr,
+			       RT_CONN_FLAGS(sk), sk->sk_bound_dev_if,
+			       IPPROTO_TCP,
+			       inet->sport, usin->sin_port, sk);
+	if (tmp < 0)
+		return tmp;
+
+	if (rt->rt_flags & (RTCF_MULTICAST | RTCF_BROADCAST)) {
+		ip_rt_put(rt);
+		return -ENETUNREACH;
+	}
+
+	if (!inet->opt || !inet->opt->srr)
+		daddr = rt->rt_dst;
+
+	if (!inet->saddr)
+		inet->saddr = rt->rt_src;
+	inet->rcv_saddr = inet->saddr;
+
+	if (tp->rx_opt.ts_recent_stamp && inet->daddr != daddr) {
+		/* Reset inherited state */
+		tp->rx_opt.ts_recent	   = 0;
+		tp->rx_opt.ts_recent_stamp = 0;
+		tp->write_seq		   = 0;
+	}
+
+	if (sysctl_tcp_tw_recycle &&
+	    !tp->rx_opt.ts_recent_stamp && rt->rt_dst == daddr) {
+		struct inet_peer *peer = rt_get_peer(rt);
+
+		/* VJ's idea. We save last timestamp seen from
+		 * the destination in peer table, when entering state TIME-WAIT
+		 * and initialize rx_opt.ts_recent from it, when trying new connection.
+		 */
+
+		if (peer && peer->tcp_ts_stamp + TCP_PAWS_MSL >= xtime.tv_sec) {
+			tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
+			tp->rx_opt.ts_recent = peer->tcp_ts;
+		}
+	}
+
+	inet->dport = usin->sin_port;
+	inet->daddr = daddr;
+
+	tp->ext_header_len = 0;
+	if (inet->opt)
+		tp->ext_header_len = inet->opt->optlen;
+
+	tp->rx_opt.mss_clamp = 536;
+
+	/* Socket identity is still unknown (sport may be zero).
+	 * However we set state to SYN-SENT and not releasing socket
+	 * lock select source port, enter ourselves into the hash tables and
+	 * complete initialization after this.
+	 */
+	tcp_set_state(sk, TCP_SYN_SENT);
+	err = tcp_v4_hash_connect(sk);
+	if (err)
+		goto failure;
+
+	err = ip_route_newports(&rt, inet->sport, inet->dport, sk);
+	if (err)
+		goto failure;
+
+	/* OK, now commit destination to socket.  */
+	__sk_dst_set(sk, &rt->u.dst);
+	tcp_v4_setup_caps(sk, &rt->u.dst);
+
+	if (!tp->write_seq)
+		tp->write_seq = secure_tcp_sequence_number(inet->saddr,
+							   inet->daddr,
+							   inet->sport,
+							   usin->sin_port);
+
+	inet->id = tp->write_seq ^ jiffies;
+
+	err = tcp_connect(sk);
+	rt = NULL;
+	if (err)
+		goto failure;
+
+	return 0;
+
+failure:
+	/* This unhashes the socket and releases the local port, if necessary. */
+	tcp_set_state(sk, TCP_CLOSE);
+	ip_rt_put(rt);
+	sk->sk_route_caps = 0;
+	inet->dport = 0;
+	return err;
+}
+
+static __inline__ int tcp_v4_iif(struct sk_buff *skb)
+{
+	return ((struct rtable *)skb->dst)->rt_iif;
+}
+
+static __inline__ u32 tcp_v4_synq_hash(u32 raddr, u16 rport, u32 rnd)
+{
+	return (jhash_2words(raddr, (u32) rport, rnd) & (TCP_SYNQ_HSIZE - 1));
+}
+
+static struct open_request *tcp_v4_search_req(struct tcp_sock *tp,
+					      struct open_request ***prevp,
+					      __u16 rport,
+					      __u32 raddr, __u32 laddr)
+{
+	struct tcp_listen_opt *lopt = tp->listen_opt;
+	struct open_request *req, **prev;
+
+	for (prev = &lopt->syn_table[tcp_v4_synq_hash(raddr, rport, lopt->hash_rnd)];
+	     (req = *prev) != NULL;
+	     prev = &req->dl_next) {
+		if (req->rmt_port == rport &&
+		    req->af.v4_req.rmt_addr == raddr &&
+		    req->af.v4_req.loc_addr == laddr &&
+		    TCP_INET_FAMILY(req->class->family)) {
+			BUG_TRAP(!req->sk);
+			*prevp = prev;
+			break;
+		}
+	}
+
+	return req;
+}
+
+static void tcp_v4_synq_add(struct sock *sk, struct open_request *req)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_listen_opt *lopt = tp->listen_opt;
+	u32 h = tcp_v4_synq_hash(req->af.v4_req.rmt_addr, req->rmt_port, lopt->hash_rnd);
+
+	req->expires = jiffies + TCP_TIMEOUT_INIT;
+	req->retrans = 0;
+	req->sk = NULL;
+	req->dl_next = lopt->syn_table[h];
+
+	write_lock(&tp->syn_wait_lock);
+	lopt->syn_table[h] = req;
+	write_unlock(&tp->syn_wait_lock);
+
+	tcp_synq_added(sk);
+}
+
+
+/*
+ * This routine does path mtu discovery as defined in RFC1191.
+ */
+static inline void do_pmtu_discovery(struct sock *sk, struct iphdr *iph,
+				     u32 mtu)
+{
+	struct dst_entry *dst;
+	struct inet_sock *inet = inet_sk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	/* We are not interested in TCP_LISTEN and open_requests (SYN-ACKs
+	 * send out by Linux are always <576bytes so they should go through
+	 * unfragmented).
+	 */
+	if (sk->sk_state == TCP_LISTEN)
+		return;
+
+	/* We don't check in the destentry if pmtu discovery is forbidden
+	 * on this route. We just assume that no packet_to_big packets
+	 * are send back when pmtu discovery is not active.
+     	 * There is a small race when the user changes this flag in the
+	 * route, but I think that's acceptable.
+	 */
+	if ((dst = __sk_dst_check(sk, 0)) == NULL)
+		return;
+
+	dst->ops->update_pmtu(dst, mtu);
+
+	/* Something is about to be wrong... Remember soft error
+	 * for the case, if this connection will not able to recover.
+	 */
+	if (mtu < dst_mtu(dst) && ip_dont_fragment(sk, dst))
+		sk->sk_err_soft = EMSGSIZE;
+
+	mtu = dst_mtu(dst);
+
+	if (inet->pmtudisc != IP_PMTUDISC_DONT &&
+	    tp->pmtu_cookie > mtu) {
+		tcp_sync_mss(sk, mtu);
+
+		/* Resend the TCP packet because it's
+		 * clear that the old packet has been
+		 * dropped. This is the new "fast" path mtu
+		 * discovery.
+		 */
+		tcp_simple_retransmit(sk);
+	} /* else let the usual retransmit timer handle it */
+}
+
+/*
+ * 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.
+ *
+ * The locking strategy used here is very "optimistic". When
+ * someone else accesses the socket the ICMP is just dropped
+ * and for some paths there is no check at all.
+ * A more general error queue to queue errors for later handling
+ * is probably better.
+ *
+ */
+
+void tcp_v4_err(struct sk_buff *skb, u32 info)
+{
+	struct iphdr *iph = (struct iphdr *)skb->data;
+	struct tcphdr *th = (struct tcphdr *)(skb->data + (iph->ihl << 2));
+	struct tcp_sock *tp;
+	struct inet_sock *inet;
+	int type = skb->h.icmph->type;
+	int code = skb->h.icmph->code;
+	struct sock *sk;
+	__u32 seq;
+	int err;
+
+	if (skb->len < (iph->ihl << 2) + 8) {
+		ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+		return;
+	}
+
+	sk = tcp_v4_lookup(iph->daddr, th->dest, iph->saddr,
+			   th->source, tcp_v4_iif(skb));
+	if (!sk) {
+		ICMP_INC_STATS_BH(ICMP_MIB_INERRORS);
+		return;
+	}
+	if (sk->sk_state == TCP_TIME_WAIT) {
+		tcp_tw_put((struct tcp_tw_bucket *)sk);
+		return;
+	}
+
+	bh_lock_sock(sk);
+	/* If too many ICMPs get dropped on busy
+	 * servers this needs to be solved differently.
+	 */
+	if (sock_owned_by_user(sk))
+		NET_INC_STATS_BH(LINUX_MIB_LOCKDROPPEDICMPS);
+
+	if (sk->sk_state == TCP_CLOSE)
+		goto out;
+
+	tp = tcp_sk(sk);
+	seq = ntohl(th->seq);
+	if (sk->sk_state != TCP_LISTEN &&
+	    !between(seq, tp->snd_una, tp->snd_nxt)) {
+		NET_INC_STATS(LINUX_MIB_OUTOFWINDOWICMPS);
+		goto out;
+	}
+
+	switch (type) {
+	case ICMP_SOURCE_QUENCH:
+		/* Just silently ignore these. */
+		goto out;
+	case ICMP_PARAMETERPROB:
+		err = EPROTO;
+		break;
+	case ICMP_DEST_UNREACH:
+		if (code > NR_ICMP_UNREACH)
+			goto out;
+
+		if (code == ICMP_FRAG_NEEDED) { /* PMTU discovery (RFC1191) */
+			if (!sock_owned_by_user(sk))
+				do_pmtu_discovery(sk, iph, info);
+			goto out;
+		}
+
+		err = icmp_err_convert[code].errno;
+		break;
+	case ICMP_TIME_EXCEEDED:
+		err = EHOSTUNREACH;
+		break;
+	default:
+		goto out;
+	}
+
+	switch (sk->sk_state) {
+		struct open_request *req, **prev;
+	case TCP_LISTEN:
+		if (sock_owned_by_user(sk))
+			goto out;
+
+		req = tcp_v4_search_req(tp, &prev, th->dest,
+					iph->daddr, iph->saddr);
+		if (!req)
+			goto out;
+
+		/* ICMPs are not backlogged, hence we cannot get
+		   an established socket here.
+		 */
+		BUG_TRAP(!req->sk);
+
+		if (seq != req->snt_isn) {
+			NET_INC_STATS_BH(LINUX_MIB_OUTOFWINDOWICMPS);
+			goto out;
+		}
+
+		/*
+		 * Still in SYN_RECV, just remove it silently.
+		 * There is no good way to pass the error to the newly
+		 * created socket, and POSIX does not want network
+		 * errors returned from accept().
+		 */
+		tcp_synq_drop(sk, req, prev);
+		goto out;
+
+	case TCP_SYN_SENT:
+	case TCP_SYN_RECV:  /* Cannot happen.
+			       It can f.e. if SYNs crossed.
+			     */
+		if (!sock_owned_by_user(sk)) {
+			TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
+			sk->sk_err = err;
+
+			sk->sk_error_report(sk);
+
+			tcp_done(sk);
+		} else {
+			sk->sk_err_soft = err;
+		}
+		goto out;
+	}
+
+	/* If we've already connected we will keep trying
+	 * until we time out, or the user gives up.
+	 *
+	 * rfc1122 4.2.3.9 allows to consider as hard errors
+	 * only PROTO_UNREACH and PORT_UNREACH (well, FRAG_FAILED too,
+	 * but it is obsoleted by pmtu discovery).
+	 *
+	 * Note, that in modern internet, where routing is unreliable
+	 * and in each dark corner broken firewalls sit, sending random
+	 * errors ordered by their masters even this two messages finally lose
+	 * their original sense (even Linux sends invalid PORT_UNREACHs)
+	 *
+	 * Now we are in compliance with RFCs.
+	 *							--ANK (980905)
+	 */
+
+	inet = inet_sk(sk);
+	if (!sock_owned_by_user(sk) && inet->recverr) {
+		sk->sk_err = err;
+		sk->sk_error_report(sk);
+	} else	{ /* Only an error on timeout */
+		sk->sk_err_soft = err;
+	}
+
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+/* This routine computes an IPv4 TCP checksum. */
+void tcp_v4_send_check(struct sock *sk, struct tcphdr *th, int len,
+		       struct sk_buff *skb)
+{
+	struct inet_sock *inet = inet_sk(sk);
+
+	if (skb->ip_summed == CHECKSUM_HW) {
+		th->check = ~tcp_v4_check(th, len, inet->saddr, inet->daddr, 0);
+		skb->csum = offsetof(struct tcphdr, check);
+	} else {
+		th->check = tcp_v4_check(th, len, inet->saddr, inet->daddr,
+					 csum_partial((char *)th,
+						      th->doff << 2,
+						      skb->csum));
+	}
+}
+
+/*
+ *	This routine will send an RST to the other tcp.
+ *
+ *	Someone asks: why I NEVER use socket parameters (TOS, TTL etc.)
+ *		      for reset.
+ *	Answer: if a packet caused RST, it is not for a socket
+ *		existing in our system, if it is matched to a socket,
+ *		it is just duplicate segment or bug in other side's TCP.
+ *		So that we build reply only basing on parameters
+ *		arrived with segment.
+ *	Exception: precedence violation. We do not implement it in any case.
+ */
+
+static void tcp_v4_send_reset(struct sk_buff *skb)
+{
+	struct tcphdr *th = skb->h.th;
+	struct tcphdr rth;
+	struct ip_reply_arg arg;
+
+	/* Never send a reset in response to a reset. */
+	if (th->rst)
+		return;
+
+	if (((struct rtable *)skb->dst)->rt_type != RTN_LOCAL)
+		return;
+
+	/* Swap the send and the receive. */
+	memset(&rth, 0, sizeof(struct tcphdr));
+	rth.dest   = th->source;
+	rth.source = th->dest;
+	rth.doff   = sizeof(struct tcphdr) / 4;
+	rth.rst    = 1;
+
+	if (th->ack) {
+		rth.seq = th->ack_seq;
+	} else {
+		rth.ack = 1;
+		rth.ack_seq = htonl(ntohl(th->seq) + th->syn + th->fin +
+				    skb->len - (th->doff << 2));
+	}
+
+	memset(&arg, 0, sizeof arg);
+	arg.iov[0].iov_base = (unsigned char *)&rth;
+	arg.iov[0].iov_len  = sizeof rth;
+	arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
+				      skb->nh.iph->saddr, /*XXX*/
+				      sizeof(struct tcphdr), IPPROTO_TCP, 0);
+	arg.csumoffset = offsetof(struct tcphdr, check) / 2;
+
+	ip_send_reply(tcp_socket->sk, skb, &arg, sizeof rth);
+
+	TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
+	TCP_INC_STATS_BH(TCP_MIB_OUTRSTS);
+}
+
+/* The code following below sending ACKs in SYN-RECV and TIME-WAIT states
+   outside socket context is ugly, certainly. What can I do?
+ */
+
+static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+			    u32 win, u32 ts)
+{
+	struct tcphdr *th = skb->h.th;
+	struct {
+		struct tcphdr th;
+		u32 tsopt[3];
+	} rep;
+	struct ip_reply_arg arg;
+
+	memset(&rep.th, 0, sizeof(struct tcphdr));
+	memset(&arg, 0, sizeof arg);
+
+	arg.iov[0].iov_base = (unsigned char *)&rep;
+	arg.iov[0].iov_len  = sizeof(rep.th);
+	if (ts) {
+		rep.tsopt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
+				     (TCPOPT_TIMESTAMP << 8) |
+				     TCPOLEN_TIMESTAMP);
+		rep.tsopt[1] = htonl(tcp_time_stamp);
+		rep.tsopt[2] = htonl(ts);
+		arg.iov[0].iov_len = sizeof(rep);
+	}
+
+	/* Swap the send and the receive. */
+	rep.th.dest    = th->source;
+	rep.th.source  = th->dest;
+	rep.th.doff    = arg.iov[0].iov_len / 4;
+	rep.th.seq     = htonl(seq);
+	rep.th.ack_seq = htonl(ack);
+	rep.th.ack     = 1;
+	rep.th.window  = htons(win);
+
+	arg.csum = csum_tcpudp_nofold(skb->nh.iph->daddr,
+				      skb->nh.iph->saddr, /*XXX*/
+				      arg.iov[0].iov_len, IPPROTO_TCP, 0);
+	arg.csumoffset = offsetof(struct tcphdr, check) / 2;
+
+	ip_send_reply(tcp_socket->sk, skb, &arg, arg.iov[0].iov_len);
+
+	TCP_INC_STATS_BH(TCP_MIB_OUTSEGS);
+}
+
+static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_tw_bucket *tw = (struct tcp_tw_bucket *)sk;
+
+	tcp_v4_send_ack(skb, tw->tw_snd_nxt, tw->tw_rcv_nxt,
+			tw->tw_rcv_wnd >> tw->tw_rcv_wscale, tw->tw_ts_recent);
+
+	tcp_tw_put(tw);
+}
+
+static void tcp_v4_or_send_ack(struct sk_buff *skb, struct open_request *req)
+{
+	tcp_v4_send_ack(skb, req->snt_isn + 1, req->rcv_isn + 1, req->rcv_wnd,
+			req->ts_recent);
+}
+
+static struct dst_entry* tcp_v4_route_req(struct sock *sk,
+					  struct open_request *req)
+{
+	struct rtable *rt;
+	struct ip_options *opt = req->af.v4_req.opt;
+	struct flowi fl = { .oif = sk->sk_bound_dev_if,
+			    .nl_u = { .ip4_u =
+				      { .daddr = ((opt && opt->srr) ?
+						  opt->faddr :
+						  req->af.v4_req.rmt_addr),
+					.saddr = req->af.v4_req.loc_addr,
+					.tos = RT_CONN_FLAGS(sk) } },
+			    .proto = IPPROTO_TCP,
+			    .uli_u = { .ports =
+				       { .sport = inet_sk(sk)->sport,
+					 .dport = req->rmt_port } } };
+
+	if (ip_route_output_flow(&rt, &fl, sk, 0)) {
+		IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
+		return NULL;
+	}
+	if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) {
+		ip_rt_put(rt);
+		IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
+		return NULL;
+	}
+	return &rt->u.dst;
+}
+
+/*
+ *	Send a SYN-ACK after having received an ACK.
+ *	This still operates on a open_request only, not on a big
+ *	socket.
+ */
+static int tcp_v4_send_synack(struct sock *sk, struct open_request *req,
+			      struct dst_entry *dst)
+{
+	int err = -1;
+	struct sk_buff * skb;
+
+	/* First, grab a route. */
+	if (!dst && (dst = tcp_v4_route_req(sk, req)) == NULL)
+		goto out;
+
+	skb = tcp_make_synack(sk, dst, req);
+
+	if (skb) {
+		struct tcphdr *th = skb->h.th;
+
+		th->check = tcp_v4_check(th, skb->len,
+					 req->af.v4_req.loc_addr,
+					 req->af.v4_req.rmt_addr,
+					 csum_partial((char *)th, skb->len,
+						      skb->csum));
+
+		err = ip_build_and_send_pkt(skb, sk, req->af.v4_req.loc_addr,
+					    req->af.v4_req.rmt_addr,
+					    req->af.v4_req.opt);
+		if (err == NET_XMIT_CN)
+			err = 0;
+	}
+
+out:
+	dst_release(dst);
+	return err;
+}
+
+/*
+ *	IPv4 open_request destructor.
+ */
+static void tcp_v4_or_free(struct open_request *req)
+{
+	if (req->af.v4_req.opt)
+		kfree(req->af.v4_req.opt);
+}
+
+static inline void syn_flood_warning(struct sk_buff *skb)
+{
+	static unsigned long warntime;
+
+	if (time_after(jiffies, (warntime + HZ * 60))) {
+		warntime = jiffies;
+		printk(KERN_INFO
+		       "possible SYN flooding on port %d. Sending cookies.\n",
+		       ntohs(skb->h.th->dest));
+	}
+}
+
+/*
+ * Save and compile IPv4 options into the open_request if needed.
+ */
+static inline struct ip_options *tcp_v4_save_options(struct sock *sk,
+						     struct sk_buff *skb)
+{
+	struct ip_options *opt = &(IPCB(skb)->opt);
+	struct ip_options *dopt = NULL;
+
+	if (opt && opt->optlen) {
+		int opt_size = optlength(opt);
+		dopt = kmalloc(opt_size, GFP_ATOMIC);
+		if (dopt) {
+			if (ip_options_echo(dopt, skb)) {
+				kfree(dopt);
+				dopt = NULL;
+			}
+		}
+	}
+	return dopt;
+}
+
+/*
+ * Maximum number of SYN_RECV sockets in queue per LISTEN socket.
+ * One SYN_RECV socket costs about 80bytes on a 32bit machine.
+ * It would be better to replace it with a global counter for all sockets
+ * but then some measure against one socket starving all other sockets
+ * would be needed.
+ *
+ * It was 128 by default. Experiments with real servers show, that
+ * it is absolutely not enough even at 100conn/sec. 256 cures most
+ * of problems. This value is adjusted to 128 for very small machines
+ * (<=32Mb of memory) and to 1024 on normal or better ones (>=256Mb).
+ * Further increasing requires to change hash table size.
+ */
+int sysctl_max_syn_backlog = 256;
+
+struct or_calltable or_ipv4 = {
+	.family		=	PF_INET,
+	.rtx_syn_ack	=	tcp_v4_send_synack,
+	.send_ack	=	tcp_v4_or_send_ack,
+	.destructor	=	tcp_v4_or_free,
+	.send_reset	=	tcp_v4_send_reset,
+};
+
+int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_options_received tmp_opt;
+	struct open_request *req;
+	__u32 saddr = skb->nh.iph->saddr;
+	__u32 daddr = skb->nh.iph->daddr;
+	__u32 isn = TCP_SKB_CB(skb)->when;
+	struct dst_entry *dst = NULL;
+#ifdef CONFIG_SYN_COOKIES
+	int want_cookie = 0;
+#else
+#define want_cookie 0 /* Argh, why doesn't gcc optimize this :( */
+#endif
+
+	/* Never answer to SYNs send to broadcast or multicast */
+	if (((struct rtable *)skb->dst)->rt_flags &
+	    (RTCF_BROADCAST | RTCF_MULTICAST))
+		goto drop;
+
+	/* TW buckets are converted to open requests without
+	 * limitations, they conserve resources and peer is
+	 * evidently real one.
+	 */
+	if (tcp_synq_is_full(sk) && !isn) {
+#ifdef CONFIG_SYN_COOKIES
+		if (sysctl_tcp_syncookies) {
+			want_cookie = 1;
+		} else
+#endif
+		goto drop;
+	}
+
+	/* Accept backlog is full. If we have already queued enough
+	 * of warm entries in syn queue, drop request. It is better than
+	 * clogging syn queue with openreqs with exponentially increasing
+	 * timeout.
+	 */
+	if (sk_acceptq_is_full(sk) && tcp_synq_young(sk) > 1)
+		goto drop;
+
+	req = tcp_openreq_alloc();
+	if (!req)
+		goto drop;
+
+	tcp_clear_options(&tmp_opt);
+	tmp_opt.mss_clamp = 536;
+	tmp_opt.user_mss  = tcp_sk(sk)->rx_opt.user_mss;
+
+	tcp_parse_options(skb, &tmp_opt, 0);
+
+	if (want_cookie) {
+		tcp_clear_options(&tmp_opt);
+		tmp_opt.saw_tstamp = 0;
+	}
+
+	if (tmp_opt.saw_tstamp && !tmp_opt.rcv_tsval) {
+		/* Some OSes (unknown ones, but I see them on web server, which
+		 * contains information interesting only for windows'
+		 * users) do not send their stamp in SYN. It is easy case.
+		 * We simply do not advertise TS support.
+		 */
+		tmp_opt.saw_tstamp = 0;
+		tmp_opt.tstamp_ok  = 0;
+	}
+	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
+
+	tcp_openreq_init(req, &tmp_opt, skb);
+
+	req->af.v4_req.loc_addr = daddr;
+	req->af.v4_req.rmt_addr = saddr;
+	req->af.v4_req.opt = tcp_v4_save_options(sk, skb);
+	req->class = &or_ipv4;
+	if (!want_cookie)
+		TCP_ECN_create_request(req, skb->h.th);
+
+	if (want_cookie) {
+#ifdef CONFIG_SYN_COOKIES
+		syn_flood_warning(skb);
+#endif
+		isn = cookie_v4_init_sequence(sk, skb, &req->mss);
+	} else if (!isn) {
+		struct inet_peer *peer = NULL;
+
+		/* VJ's idea. We save last timestamp seen
+		 * from the destination in peer table, when entering
+		 * state TIME-WAIT, and check against it before
+		 * accepting new connection request.
+		 *
+		 * If "isn" is not zero, this request hit alive
+		 * timewait bucket, so that all the necessary checks
+		 * are made in the function processing timewait state.
+		 */
+		if (tmp_opt.saw_tstamp &&
+		    sysctl_tcp_tw_recycle &&
+		    (dst = tcp_v4_route_req(sk, req)) != NULL &&
+		    (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
+		    peer->v4daddr == saddr) {
+			if (xtime.tv_sec < peer->tcp_ts_stamp + TCP_PAWS_MSL &&
+			    (s32)(peer->tcp_ts - req->ts_recent) >
+							TCP_PAWS_WINDOW) {
+				NET_INC_STATS_BH(LINUX_MIB_PAWSPASSIVEREJECTED);
+				dst_release(dst);
+				goto drop_and_free;
+			}
+		}
+		/* Kill the following clause, if you dislike this way. */
+		else if (!sysctl_tcp_syncookies &&
+			 (sysctl_max_syn_backlog - tcp_synq_len(sk) <
+			  (sysctl_max_syn_backlog >> 2)) &&
+			 (!peer || !peer->tcp_ts_stamp) &&
+			 (!dst || !dst_metric(dst, RTAX_RTT))) {
+			/* Without syncookies last quarter of
+			 * backlog is filled with destinations,
+			 * proven to be alive.
+			 * It means that we continue to communicate
+			 * to destinations, already remembered
+			 * to the moment of synflood.
+			 */
+			NETDEBUG(if (net_ratelimit()) \
+					printk(KERN_DEBUG "TCP: drop open "
+							  "request from %u.%u."
+							  "%u.%u/%u\n", \
+					       NIPQUAD(saddr),
+					       ntohs(skb->h.th->source)));
+			dst_release(dst);
+			goto drop_and_free;
+		}
+
+		isn = tcp_v4_init_sequence(sk, skb);
+	}
+	req->snt_isn = isn;
+
+	if (tcp_v4_send_synack(sk, req, dst))
+		goto drop_and_free;
+
+	if (want_cookie) {
+	   	tcp_openreq_free(req);
+	} else {
+		tcp_v4_synq_add(sk, req);
+	}
+	return 0;
+
+drop_and_free:
+	tcp_openreq_free(req);
+drop:
+	TCP_INC_STATS_BH(TCP_MIB_ATTEMPTFAILS);
+	return 0;
+}
+
+
+/*
+ * The three way handshake has completed - we got a valid synack -
+ * now create the new socket.
+ */
+struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+				  struct open_request *req,
+				  struct dst_entry *dst)
+{
+	struct inet_sock *newinet;
+	struct tcp_sock *newtp;
+	struct sock *newsk;
+
+	if (sk_acceptq_is_full(sk))
+		goto exit_overflow;
+
+	if (!dst && (dst = tcp_v4_route_req(sk, req)) == NULL)
+		goto exit;
+
+	newsk = tcp_create_openreq_child(sk, req, skb);
+	if (!newsk)
+		goto exit;
+
+	newsk->sk_dst_cache = dst;
+	tcp_v4_setup_caps(newsk, dst);
+
+	newtp		      = tcp_sk(newsk);
+	newinet		      = inet_sk(newsk);
+	newinet->daddr	      = req->af.v4_req.rmt_addr;
+	newinet->rcv_saddr    = req->af.v4_req.loc_addr;
+	newinet->saddr	      = req->af.v4_req.loc_addr;
+	newinet->opt	      = req->af.v4_req.opt;
+	req->af.v4_req.opt    = NULL;
+	newinet->mc_index     = tcp_v4_iif(skb);
+	newinet->mc_ttl	      = skb->nh.iph->ttl;
+	newtp->ext_header_len = 0;
+	if (newinet->opt)
+		newtp->ext_header_len = newinet->opt->optlen;
+	newinet->id = newtp->write_seq ^ jiffies;
+
+	tcp_sync_mss(newsk, dst_mtu(dst));
+	newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
+	tcp_initialize_rcv_mss(newsk);
+
+	__tcp_v4_hash(newsk, 0);
+	__tcp_inherit_port(sk, newsk);
+
+	return newsk;
+
+exit_overflow:
+	NET_INC_STATS_BH(LINUX_MIB_LISTENOVERFLOWS);
+exit:
+	NET_INC_STATS_BH(LINUX_MIB_LISTENDROPS);
+	dst_release(dst);
+	return NULL;
+}
+
+static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcphdr *th = skb->h.th;
+	struct iphdr *iph = skb->nh.iph;
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sock *nsk;
+	struct open_request **prev;
+	/* Find possible connection requests. */
+	struct open_request *req = tcp_v4_search_req(tp, &prev, th->source,
+						     iph->saddr, iph->daddr);
+	if (req)
+		return tcp_check_req(sk, skb, req, prev);
+
+	nsk = __tcp_v4_lookup_established(skb->nh.iph->saddr,
+					  th->source,
+					  skb->nh.iph->daddr,
+					  ntohs(th->dest),
+					  tcp_v4_iif(skb));
+
+	if (nsk) {
+		if (nsk->sk_state != TCP_TIME_WAIT) {
+			bh_lock_sock(nsk);
+			return nsk;
+		}
+		tcp_tw_put((struct tcp_tw_bucket *)nsk);
+		return NULL;
+	}
+
+#ifdef CONFIG_SYN_COOKIES
+	if (!th->rst && !th->syn && th->ack)
+		sk = cookie_v4_check(sk, skb, &(IPCB(skb)->opt));
+#endif
+	return sk;
+}
+
+static int tcp_v4_checksum_init(struct sk_buff *skb)
+{
+	if (skb->ip_summed == CHECKSUM_HW) {
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+		if (!tcp_v4_check(skb->h.th, skb->len, skb->nh.iph->saddr,
+				  skb->nh.iph->daddr, skb->csum))
+			return 0;
+
+		NETDEBUG(if (net_ratelimit())
+				printk(KERN_DEBUG "hw tcp v4 csum failed\n"));
+		skb->ip_summed = CHECKSUM_NONE;
+	}
+	if (skb->len <= 76) {
+		if (tcp_v4_check(skb->h.th, skb->len, skb->nh.iph->saddr,
+				 skb->nh.iph->daddr,
+				 skb_checksum(skb, 0, skb->len, 0)))
+			return -1;
+		skb->ip_summed = CHECKSUM_UNNECESSARY;
+	} else {
+		skb->csum = ~tcp_v4_check(skb->h.th, skb->len,
+					  skb->nh.iph->saddr,
+					  skb->nh.iph->daddr, 0);
+	}
+	return 0;
+}
+
+
+/* The socket must have it's spinlock held when we get
+ * here.
+ *
+ * We have a potential double-lock case here, so even when
+ * doing backlog processing we use the BH locking scheme.
+ * This is because we cannot sleep with the original spinlock
+ * held.
+ */
+int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
+		TCP_CHECK_TIMER(sk);
+		if (tcp_rcv_established(sk, skb, skb->h.th, skb->len))
+			goto reset;
+		TCP_CHECK_TIMER(sk);
+		return 0;
+	}
+
+	if (skb->len < (skb->h.th->doff << 2) || tcp_checksum_complete(skb))
+		goto csum_err;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		struct sock *nsk = tcp_v4_hnd_req(sk, skb);
+		if (!nsk)
+			goto discard;
+
+		if (nsk != sk) {
+			if (tcp_child_process(sk, nsk, skb))
+				goto reset;
+			return 0;
+		}
+	}
+
+	TCP_CHECK_TIMER(sk);
+	if (tcp_rcv_state_process(sk, skb, skb->h.th, skb->len))
+		goto reset;
+	TCP_CHECK_TIMER(sk);
+	return 0;
+
+reset:
+	tcp_v4_send_reset(skb);
+discard:
+	kfree_skb(skb);
+	/* Be careful here. If this function gets more complicated and
+	 * gcc suffers from register pressure on the x86, sk (in %ebx)
+	 * might be destroyed here. This current version compiles correctly,
+	 * but you have been warned.
+	 */
+	return 0;
+
+csum_err:
+	TCP_INC_STATS_BH(TCP_MIB_INERRS);
+	goto discard;
+}
+
+/*
+ *	From tcp_input.c
+ */
+
+int tcp_v4_rcv(struct sk_buff *skb)
+{
+	struct tcphdr *th;
+	struct sock *sk;
+	int ret;
+
+	if (skb->pkt_type != PACKET_HOST)
+		goto discard_it;
+
+	/* Count it even if it's bad */
+	TCP_INC_STATS_BH(TCP_MIB_INSEGS);
+
+	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
+		goto discard_it;
+
+	th = skb->h.th;
+
+	if (th->doff < sizeof(struct tcphdr) / 4)
+		goto bad_packet;
+	if (!pskb_may_pull(skb, th->doff * 4))
+		goto discard_it;
+
+	/* An explanation is required here, I think.
+	 * Packet length and doff are validated by header prediction,
+	 * provided case of th->doff==0 is elimineted.
+	 * So, we defer the checks. */
+	if ((skb->ip_summed != CHECKSUM_UNNECESSARY &&
+	     tcp_v4_checksum_init(skb) < 0))
+		goto bad_packet;
+
+	th = skb->h.th;
+	TCP_SKB_CB(skb)->seq = ntohl(th->seq);
+	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
+				    skb->len - th->doff * 4);
+	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
+	TCP_SKB_CB(skb)->when	 = 0;
+	TCP_SKB_CB(skb)->flags	 = skb->nh.iph->tos;
+	TCP_SKB_CB(skb)->sacked	 = 0;
+
+	sk = __tcp_v4_lookup(skb->nh.iph->saddr, th->source,
+			     skb->nh.iph->daddr, ntohs(th->dest),
+			     tcp_v4_iif(skb));
+
+	if (!sk)
+		goto no_tcp_socket;
+
+process:
+	if (sk->sk_state == TCP_TIME_WAIT)
+		goto do_time_wait;
+
+	if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb))
+		goto discard_and_relse;
+
+	if (sk_filter(sk, skb, 0))
+		goto discard_and_relse;
+
+	skb->dev = NULL;
+
+	bh_lock_sock(sk);
+	ret = 0;
+	if (!sock_owned_by_user(sk)) {
+		if (!tcp_prequeue(sk, skb))
+			ret = tcp_v4_do_rcv(sk, skb);
+	} else
+		sk_add_backlog(sk, skb);
+	bh_unlock_sock(sk);
+
+	sock_put(sk);
+
+	return ret;
+
+no_tcp_socket:
+	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
+		goto discard_it;
+
+	if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
+bad_packet:
+		TCP_INC_STATS_BH(TCP_MIB_INERRS);
+	} else {
+		tcp_v4_send_reset(skb);
+	}
+
+discard_it:
+	/* Discard frame. */
+	kfree_skb(skb);
+  	return 0;
+
+discard_and_relse:
+	sock_put(sk);
+	goto discard_it;
+
+do_time_wait:
+	if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+		tcp_tw_put((struct tcp_tw_bucket *) sk);
+		goto discard_it;
+	}
+
+	if (skb->len < (th->doff << 2) || tcp_checksum_complete(skb)) {
+		TCP_INC_STATS_BH(TCP_MIB_INERRS);
+		tcp_tw_put((struct tcp_tw_bucket *) sk);
+		goto discard_it;
+	}
+	switch (tcp_timewait_state_process((struct tcp_tw_bucket *)sk,
+					   skb, th, skb->len)) {
+	case TCP_TW_SYN: {
+		struct sock *sk2 = tcp_v4_lookup_listener(skb->nh.iph->daddr,
+							  ntohs(th->dest),
+							  tcp_v4_iif(skb));
+		if (sk2) {
+			tcp_tw_deschedule((struct tcp_tw_bucket *)sk);
+			tcp_tw_put((struct tcp_tw_bucket *)sk);
+			sk = sk2;
+			goto process;
+		}
+		/* Fall through to ACK */
+	}
+	case TCP_TW_ACK:
+		tcp_v4_timewait_ack(sk, skb);
+		break;
+	case TCP_TW_RST:
+		goto no_tcp_socket;
+	case TCP_TW_SUCCESS:;
+	}
+	goto discard_it;
+}
+
+/* With per-bucket locks this operation is not-atomic, so that
+ * this version is not worse.
+ */
+static void __tcp_v4_rehash(struct sock *sk)
+{
+	sk->sk_prot->unhash(sk);
+	sk->sk_prot->hash(sk);
+}
+
+static int tcp_v4_reselect_saddr(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	int err;
+	struct rtable *rt;
+	__u32 old_saddr = inet->saddr;
+	__u32 new_saddr;
+	__u32 daddr = inet->daddr;
+
+	if (inet->opt && inet->opt->srr)
+		daddr = inet->opt->faddr;
+
+	/* Query new route. */
+	err = ip_route_connect(&rt, daddr, 0,
+			       RT_CONN_FLAGS(sk),
+			       sk->sk_bound_dev_if,
+			       IPPROTO_TCP,
+			       inet->sport, inet->dport, sk);
+	if (err)
+		return err;
+
+	__sk_dst_set(sk, &rt->u.dst);
+	tcp_v4_setup_caps(sk, &rt->u.dst);
+
+	new_saddr = rt->rt_src;
+
+	if (new_saddr == old_saddr)
+		return 0;
+
+	if (sysctl_ip_dynaddr > 1) {
+		printk(KERN_INFO "tcp_v4_rebuild_header(): shifting inet->"
+				 "saddr from %d.%d.%d.%d to %d.%d.%d.%d\n",
+		       NIPQUAD(old_saddr),
+		       NIPQUAD(new_saddr));
+	}
+
+	inet->saddr = new_saddr;
+	inet->rcv_saddr = new_saddr;
+
+	/* XXX The only one ugly spot where we need to
+	 * XXX really change the sockets identity after
+	 * XXX it has entered the hashes. -DaveM
+	 *
+	 * Besides that, it does not check for connection
+	 * uniqueness. Wait for troubles.
+	 */
+	__tcp_v4_rehash(sk);
+	return 0;
+}
+
+int tcp_v4_rebuild_header(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct rtable *rt = (struct rtable *)__sk_dst_check(sk, 0);
+	u32 daddr;
+	int err;
+
+	/* Route is OK, nothing to do. */
+	if (rt)
+		return 0;
+
+	/* Reroute. */
+	daddr = inet->daddr;
+	if (inet->opt && inet->opt->srr)
+		daddr = inet->opt->faddr;
+
+	{
+		struct flowi fl = { .oif = sk->sk_bound_dev_if,
+				    .nl_u = { .ip4_u =
+					      { .daddr = daddr,
+						.saddr = inet->saddr,
+						.tos = RT_CONN_FLAGS(sk) } },
+				    .proto = IPPROTO_TCP,
+				    .uli_u = { .ports =
+					       { .sport = inet->sport,
+						 .dport = inet->dport } } };
+						
+		err = ip_route_output_flow(&rt, &fl, sk, 0);
+	}
+	if (!err) {
+		__sk_dst_set(sk, &rt->u.dst);
+		tcp_v4_setup_caps(sk, &rt->u.dst);
+		return 0;
+	}
+
+	/* Routing failed... */
+	sk->sk_route_caps = 0;
+
+	if (!sysctl_ip_dynaddr ||
+	    sk->sk_state != TCP_SYN_SENT ||
+	    (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
+	    (err = tcp_v4_reselect_saddr(sk)) != 0)
+		sk->sk_err_soft = -err;
+
+	return err;
+}
+
+static void v4_addr2sockaddr(struct sock *sk, struct sockaddr * uaddr)
+{
+	struct sockaddr_in *sin = (struct sockaddr_in *) uaddr;
+	struct inet_sock *inet = inet_sk(sk);
+
+	sin->sin_family		= AF_INET;
+	sin->sin_addr.s_addr	= inet->daddr;
+	sin->sin_port		= inet->dport;
+}
+
+/* VJ's idea. Save last timestamp seen from this destination
+ * and hold it at least for normal timewait interval to use for duplicate
+ * segment detection in subsequent connections, before they enter synchronized
+ * state.
+ */
+
+int tcp_v4_remember_stamp(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct rtable *rt = (struct rtable *)__sk_dst_get(sk);
+	struct inet_peer *peer = NULL;
+	int release_it = 0;
+
+	if (!rt || rt->rt_dst != inet->daddr) {
+		peer = inet_getpeer(inet->daddr, 1);
+		release_it = 1;
+	} else {
+		if (!rt->peer)
+			rt_bind_peer(rt, 1);
+		peer = rt->peer;
+	}
+
+	if (peer) {
+		if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 ||
+		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
+		     peer->tcp_ts_stamp <= tp->rx_opt.ts_recent_stamp)) {
+			peer->tcp_ts_stamp = tp->rx_opt.ts_recent_stamp;
+			peer->tcp_ts = tp->rx_opt.ts_recent;
+		}
+		if (release_it)
+			inet_putpeer(peer);
+		return 1;
+	}
+
+	return 0;
+}
+
+int tcp_v4_tw_remember_stamp(struct tcp_tw_bucket *tw)
+{
+	struct inet_peer *peer = NULL;
+
+	peer = inet_getpeer(tw->tw_daddr, 1);
+
+	if (peer) {
+		if ((s32)(peer->tcp_ts - tw->tw_ts_recent) <= 0 ||
+		    (peer->tcp_ts_stamp + TCP_PAWS_MSL < xtime.tv_sec &&
+		     peer->tcp_ts_stamp <= tw->tw_ts_recent_stamp)) {
+			peer->tcp_ts_stamp = tw->tw_ts_recent_stamp;
+			peer->tcp_ts = tw->tw_ts_recent;
+		}
+		inet_putpeer(peer);
+		return 1;
+	}
+
+	return 0;
+}
+
+struct tcp_func ipv4_specific = {
+	.queue_xmit	=	ip_queue_xmit,
+	.send_check	=	tcp_v4_send_check,
+	.rebuild_header	=	tcp_v4_rebuild_header,
+	.conn_request	=	tcp_v4_conn_request,
+	.syn_recv_sock	=	tcp_v4_syn_recv_sock,
+	.remember_stamp	=	tcp_v4_remember_stamp,
+	.net_header_len	=	sizeof(struct iphdr),
+	.setsockopt	=	ip_setsockopt,
+	.getsockopt	=	ip_getsockopt,
+	.addr2sockaddr	=	v4_addr2sockaddr,
+	.sockaddr_len	=	sizeof(struct sockaddr_in),
+};
+
+/* NOTE: A lot of things set to zero explicitly by call to
+ *       sk_alloc() so need not be done here.
+ */
+static int tcp_v4_init_sock(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	skb_queue_head_init(&tp->out_of_order_queue);
+	tcp_init_xmit_timers(sk);
+	tcp_prequeue_init(tp);
+
+	tp->rto  = TCP_TIMEOUT_INIT;
+	tp->mdev = TCP_TIMEOUT_INIT;
+
+	/* So many TCP implementations out there (incorrectly) count the
+	 * initial SYN frame in their delayed-ACK and congestion control
+	 * algorithms that we must have the following bandaid to talk
+	 * efficiently to them.  -DaveM
+	 */
+	tp->snd_cwnd = 2;
+
+	/* See draft-stevens-tcpca-spec-01 for discussion of the
+	 * initialization of these values.
+	 */
+	tp->snd_ssthresh = 0x7fffffff;	/* Infinity */
+	tp->snd_cwnd_clamp = ~0;
+	tp->mss_cache_std = tp->mss_cache = 536;
+
+	tp->reordering = sysctl_tcp_reordering;
+
+	sk->sk_state = TCP_CLOSE;
+
+	sk->sk_write_space = sk_stream_write_space;
+	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
+
+	tp->af_specific = &ipv4_specific;
+
+	sk->sk_sndbuf = sysctl_tcp_wmem[1];
+	sk->sk_rcvbuf = sysctl_tcp_rmem[1];
+
+	atomic_inc(&tcp_sockets_allocated);
+
+	return 0;
+}
+
+int tcp_v4_destroy_sock(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tcp_clear_xmit_timers(sk);
+
+	/* Cleanup up the write buffer. */
+  	sk_stream_writequeue_purge(sk);
+
+	/* Cleans up our, hopefully empty, out_of_order_queue. */
+  	__skb_queue_purge(&tp->out_of_order_queue);
+
+	/* Clean prequeue, it must be empty really */
+	__skb_queue_purge(&tp->ucopy.prequeue);
+
+	/* Clean up a referenced TCP bind bucket. */
+	if (tp->bind_hash)
+		tcp_put_port(sk);
+
+	/*
+	 * If sendmsg cached page exists, toss it.
+	 */
+	if (sk->sk_sndmsg_page) {
+		__free_page(sk->sk_sndmsg_page);
+		sk->sk_sndmsg_page = NULL;
+	}
+
+	atomic_dec(&tcp_sockets_allocated);
+
+	return 0;
+}
+
+EXPORT_SYMBOL(tcp_v4_destroy_sock);
+
+#ifdef CONFIG_PROC_FS
+/* Proc filesystem TCP sock list dumping. */
+
+static inline struct tcp_tw_bucket *tw_head(struct hlist_head *head)
+{
+	return hlist_empty(head) ? NULL :
+		list_entry(head->first, struct tcp_tw_bucket, tw_node);
+}
+
+static inline struct tcp_tw_bucket *tw_next(struct tcp_tw_bucket *tw)
+{
+	return tw->tw_node.next ?
+		hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL;
+}
+
+static void *listening_get_next(struct seq_file *seq, void *cur)
+{
+	struct tcp_sock *tp;
+	struct hlist_node *node;
+	struct sock *sk = cur;
+	struct tcp_iter_state* st = seq->private;
+
+	if (!sk) {
+		st->bucket = 0;
+		sk = sk_head(&tcp_listening_hash[0]);
+		goto get_sk;
+	}
+
+	++st->num;
+
+	if (st->state == TCP_SEQ_STATE_OPENREQ) {
+		struct open_request *req = cur;
+
+	       	tp = tcp_sk(st->syn_wait_sk);
+		req = req->dl_next;
+		while (1) {
+			while (req) {
+				if (req->class->family == st->family) {
+					cur = req;
+					goto out;
+				}
+				req = req->dl_next;
+			}
+			if (++st->sbucket >= TCP_SYNQ_HSIZE)
+				break;
+get_req:
+			req = tp->listen_opt->syn_table[st->sbucket];
+		}
+		sk	  = sk_next(st->syn_wait_sk);
+		st->state = TCP_SEQ_STATE_LISTENING;
+		read_unlock_bh(&tp->syn_wait_lock);
+	} else {
+	       	tp = tcp_sk(sk);
+		read_lock_bh(&tp->syn_wait_lock);
+		if (tp->listen_opt && tp->listen_opt->qlen)
+			goto start_req;
+		read_unlock_bh(&tp->syn_wait_lock);
+		sk = sk_next(sk);
+	}
+get_sk:
+	sk_for_each_from(sk, node) {
+		if (sk->sk_family == st->family) {
+			cur = sk;
+			goto out;
+		}
+	       	tp = tcp_sk(sk);
+		read_lock_bh(&tp->syn_wait_lock);
+		if (tp->listen_opt && tp->listen_opt->qlen) {
+start_req:
+			st->uid		= sock_i_uid(sk);
+			st->syn_wait_sk = sk;
+			st->state	= TCP_SEQ_STATE_OPENREQ;
+			st->sbucket	= 0;
+			goto get_req;
+		}
+		read_unlock_bh(&tp->syn_wait_lock);
+	}
+	if (++st->bucket < TCP_LHTABLE_SIZE) {
+		sk = sk_head(&tcp_listening_hash[st->bucket]);
+		goto get_sk;
+	}
+	cur = NULL;
+out:
+	return cur;
+}
+
+static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
+{
+	void *rc = listening_get_next(seq, NULL);
+
+	while (rc && *pos) {
+		rc = listening_get_next(seq, rc);
+		--*pos;
+	}
+	return rc;
+}
+
+static void *established_get_first(struct seq_file *seq)
+{
+	struct tcp_iter_state* st = seq->private;
+	void *rc = NULL;
+
+	for (st->bucket = 0; st->bucket < tcp_ehash_size; ++st->bucket) {
+		struct sock *sk;
+		struct hlist_node *node;
+		struct tcp_tw_bucket *tw;
+
+		/* We can reschedule _before_ having picked the target: */
+		cond_resched_softirq();
+
+		read_lock(&tcp_ehash[st->bucket].lock);
+		sk_for_each(sk, node, &tcp_ehash[st->bucket].chain) {
+			if (sk->sk_family != st->family) {
+				continue;
+			}
+			rc = sk;
+			goto out;
+		}
+		st->state = TCP_SEQ_STATE_TIME_WAIT;
+		tw_for_each(tw, node,
+			    &tcp_ehash[st->bucket + tcp_ehash_size].chain) {
+			if (tw->tw_family != st->family) {
+				continue;
+			}
+			rc = tw;
+			goto out;
+		}
+		read_unlock(&tcp_ehash[st->bucket].lock);
+		st->state = TCP_SEQ_STATE_ESTABLISHED;
+	}
+out:
+	return rc;
+}
+
+static void *established_get_next(struct seq_file *seq, void *cur)
+{
+	struct sock *sk = cur;
+	struct tcp_tw_bucket *tw;
+	struct hlist_node *node;
+	struct tcp_iter_state* st = seq->private;
+
+	++st->num;
+
+	if (st->state == TCP_SEQ_STATE_TIME_WAIT) {
+		tw = cur;
+		tw = tw_next(tw);
+get_tw:
+		while (tw && tw->tw_family != st->family) {
+			tw = tw_next(tw);
+		}
+		if (tw) {
+			cur = tw;
+			goto out;
+		}
+		read_unlock(&tcp_ehash[st->bucket].lock);
+		st->state = TCP_SEQ_STATE_ESTABLISHED;
+
+		/* We can reschedule between buckets: */
+		cond_resched_softirq();
+
+		if (++st->bucket < tcp_ehash_size) {
+			read_lock(&tcp_ehash[st->bucket].lock);
+			sk = sk_head(&tcp_ehash[st->bucket].chain);
+		} else {
+			cur = NULL;
+			goto out;
+		}
+	} else
+		sk = sk_next(sk);
+
+	sk_for_each_from(sk, node) {
+		if (sk->sk_family == st->family)
+			goto found;
+	}
+
+	st->state = TCP_SEQ_STATE_TIME_WAIT;
+	tw = tw_head(&tcp_ehash[st->bucket + tcp_ehash_size].chain);
+	goto get_tw;
+found:
+	cur = sk;
+out:
+	return cur;
+}
+
+static void *established_get_idx(struct seq_file *seq, loff_t pos)
+{
+	void *rc = established_get_first(seq);
+
+	while (rc && pos) {
+		rc = established_get_next(seq, rc);
+		--pos;
+	}		
+	return rc;
+}
+
+static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
+{
+	void *rc;
+	struct tcp_iter_state* st = seq->private;
+
+	tcp_listen_lock();
+	st->state = TCP_SEQ_STATE_LISTENING;
+	rc	  = listening_get_idx(seq, &pos);
+
+	if (!rc) {
+		tcp_listen_unlock();
+		local_bh_disable();
+		st->state = TCP_SEQ_STATE_ESTABLISHED;
+		rc	  = established_get_idx(seq, pos);
+	}
+
+	return rc;
+}
+
+static void *tcp_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct tcp_iter_state* st = seq->private;
+	st->state = TCP_SEQ_STATE_LISTENING;
+	st->num = 0;
+	return *pos ? tcp_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
+}
+
+static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	void *rc = NULL;
+	struct tcp_iter_state* st;
+
+	if (v == SEQ_START_TOKEN) {
+		rc = tcp_get_idx(seq, 0);
+		goto out;
+	}
+	st = seq->private;
+
+	switch (st->state) {
+	case TCP_SEQ_STATE_OPENREQ:
+	case TCP_SEQ_STATE_LISTENING:
+		rc = listening_get_next(seq, v);
+		if (!rc) {
+			tcp_listen_unlock();
+			local_bh_disable();
+			st->state = TCP_SEQ_STATE_ESTABLISHED;
+			rc	  = established_get_first(seq);
+		}
+		break;
+	case TCP_SEQ_STATE_ESTABLISHED:
+	case TCP_SEQ_STATE_TIME_WAIT:
+		rc = established_get_next(seq, v);
+		break;
+	}
+out:
+	++*pos;
+	return rc;
+}
+
+static void tcp_seq_stop(struct seq_file *seq, void *v)
+{
+	struct tcp_iter_state* st = seq->private;
+
+	switch (st->state) {
+	case TCP_SEQ_STATE_OPENREQ:
+		if (v) {
+			struct tcp_sock *tp = tcp_sk(st->syn_wait_sk);
+			read_unlock_bh(&tp->syn_wait_lock);
+		}
+	case TCP_SEQ_STATE_LISTENING:
+		if (v != SEQ_START_TOKEN)
+			tcp_listen_unlock();
+		break;
+	case TCP_SEQ_STATE_TIME_WAIT:
+	case TCP_SEQ_STATE_ESTABLISHED:
+		if (v)
+			read_unlock(&tcp_ehash[st->bucket].lock);
+		local_bh_enable();
+		break;
+	}
+}
+
+static int tcp_seq_open(struct inode *inode, struct file *file)
+{
+	struct tcp_seq_afinfo *afinfo = PDE(inode)->data;
+	struct seq_file *seq;
+	struct tcp_iter_state *s;
+	int rc;
+
+	if (unlikely(afinfo == NULL))
+		return -EINVAL;
+
+	s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+	memset(s, 0, sizeof(*s));
+	s->family		= afinfo->family;
+	s->seq_ops.start	= tcp_seq_start;
+	s->seq_ops.next		= tcp_seq_next;
+	s->seq_ops.show		= afinfo->seq_show;
+	s->seq_ops.stop		= tcp_seq_stop;
+
+	rc = seq_open(file, &s->seq_ops);
+	if (rc)
+		goto out_kfree;
+	seq	     = file->private_data;
+	seq->private = s;
+out:
+	return rc;
+out_kfree:
+	kfree(s);
+	goto out;
+}
+
+int tcp_proc_register(struct tcp_seq_afinfo *afinfo)
+{
+	int rc = 0;
+	struct proc_dir_entry *p;
+
+	if (!afinfo)
+		return -EINVAL;
+	afinfo->seq_fops->owner		= afinfo->owner;
+	afinfo->seq_fops->open		= tcp_seq_open;
+	afinfo->seq_fops->read		= seq_read;
+	afinfo->seq_fops->llseek	= seq_lseek;
+	afinfo->seq_fops->release	= seq_release_private;
+	
+	p = proc_net_fops_create(afinfo->name, S_IRUGO, afinfo->seq_fops);
+	if (p)
+		p->data = afinfo;
+	else
+		rc = -ENOMEM;
+	return rc;
+}
+
+void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo)
+{
+	if (!afinfo)
+		return;
+	proc_net_remove(afinfo->name);
+	memset(afinfo->seq_fops, 0, sizeof(*afinfo->seq_fops)); 
+}
+
+static void get_openreq4(struct sock *sk, struct open_request *req,
+			 char *tmpbuf, int i, int uid)
+{
+	int ttd = req->expires - jiffies;
+
+	sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p",
+		i,
+		req->af.v4_req.loc_addr,
+		ntohs(inet_sk(sk)->sport),
+		req->af.v4_req.rmt_addr,
+		ntohs(req->rmt_port),
+		TCP_SYN_RECV,
+		0, 0, /* could print option size, but that is af dependent. */
+		1,    /* timers active (only the expire timer) */
+		jiffies_to_clock_t(ttd),
+		req->retrans,
+		uid,
+		0,  /* non standard timer */
+		0, /* open_requests have no inode */
+		atomic_read(&sk->sk_refcnt),
+		req);
+}
+
+static void get_tcp4_sock(struct sock *sp, char *tmpbuf, int i)
+{
+	int timer_active;
+	unsigned long timer_expires;
+	struct tcp_sock *tp = tcp_sk(sp);
+	struct inet_sock *inet = inet_sk(sp);
+	unsigned int dest = inet->daddr;
+	unsigned int src = inet->rcv_saddr;
+	__u16 destp = ntohs(inet->dport);
+	__u16 srcp = ntohs(inet->sport);
+
+	if (tp->pending == TCP_TIME_RETRANS) {
+		timer_active	= 1;
+		timer_expires	= tp->timeout;
+	} else if (tp->pending == TCP_TIME_PROBE0) {
+		timer_active	= 4;
+		timer_expires	= tp->timeout;
+	} else if (timer_pending(&sp->sk_timer)) {
+		timer_active	= 2;
+		timer_expires	= sp->sk_timer.expires;
+	} else {
+		timer_active	= 0;
+		timer_expires = jiffies;
+	}
+
+	sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
+			"%08X %5d %8d %lu %d %p %u %u %u %u %d",
+		i, src, srcp, dest, destp, sp->sk_state,
+		tp->write_seq - tp->snd_una, tp->rcv_nxt - tp->copied_seq,
+		timer_active,
+		jiffies_to_clock_t(timer_expires - jiffies),
+		tp->retransmits,
+		sock_i_uid(sp),
+		tp->probes_out,
+		sock_i_ino(sp),
+		atomic_read(&sp->sk_refcnt), sp,
+		tp->rto, tp->ack.ato, (tp->ack.quick << 1) | tp->ack.pingpong,
+		tp->snd_cwnd,
+		tp->snd_ssthresh >= 0xFFFF ? -1 : tp->snd_ssthresh);
+}
+
+static void get_timewait4_sock(struct tcp_tw_bucket *tw, char *tmpbuf, int i)
+{
+	unsigned int dest, src;
+	__u16 destp, srcp;
+	int ttd = tw->tw_ttd - jiffies;
+
+	if (ttd < 0)
+		ttd = 0;
+
+	dest  = tw->tw_daddr;
+	src   = tw->tw_rcv_saddr;
+	destp = ntohs(tw->tw_dport);
+	srcp  = ntohs(tw->tw_sport);
+
+	sprintf(tmpbuf, "%4d: %08X:%04X %08X:%04X"
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p",
+		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
+		3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
+		atomic_read(&tw->tw_refcnt), tw);
+}
+
+#define TMPSZ 150
+
+static int tcp4_seq_show(struct seq_file *seq, void *v)
+{
+	struct tcp_iter_state* st;
+	char tmpbuf[TMPSZ + 1];
+
+	if (v == SEQ_START_TOKEN) {
+		seq_printf(seq, "%-*s\n", TMPSZ - 1,
+			   "  sl  local_address rem_address   st tx_queue "
+			   "rx_queue tr tm->when retrnsmt   uid  timeout "
+			   "inode");
+		goto out;
+	}
+	st = seq->private;
+
+	switch (st->state) {
+	case TCP_SEQ_STATE_LISTENING:
+	case TCP_SEQ_STATE_ESTABLISHED:
+		get_tcp4_sock(v, tmpbuf, st->num);
+		break;
+	case TCP_SEQ_STATE_OPENREQ:
+		get_openreq4(st->syn_wait_sk, v, tmpbuf, st->num, st->uid);
+		break;
+	case TCP_SEQ_STATE_TIME_WAIT:
+		get_timewait4_sock(v, tmpbuf, st->num);
+		break;
+	}
+	seq_printf(seq, "%-*s\n", TMPSZ - 1, tmpbuf);
+out:
+	return 0;
+}
+
+static struct file_operations tcp4_seq_fops;
+static struct tcp_seq_afinfo tcp4_seq_afinfo = {
+	.owner		= THIS_MODULE,
+	.name		= "tcp",
+	.family		= AF_INET,
+	.seq_show	= tcp4_seq_show,
+	.seq_fops	= &tcp4_seq_fops,
+};
+
+int __init tcp4_proc_init(void)
+{
+	return tcp_proc_register(&tcp4_seq_afinfo);
+}
+
+void tcp4_proc_exit(void)
+{
+	tcp_proc_unregister(&tcp4_seq_afinfo);
+}
+#endif /* CONFIG_PROC_FS */
+
+struct proto tcp_prot = {
+	.name			= "TCP",
+	.owner			= THIS_MODULE,
+	.close			= tcp_close,
+	.connect		= tcp_v4_connect,
+	.disconnect		= tcp_disconnect,
+	.accept			= tcp_accept,
+	.ioctl			= tcp_ioctl,
+	.init			= tcp_v4_init_sock,
+	.destroy		= tcp_v4_destroy_sock,
+	.shutdown		= tcp_shutdown,
+	.setsockopt		= tcp_setsockopt,
+	.getsockopt		= tcp_getsockopt,
+	.sendmsg		= tcp_sendmsg,
+	.recvmsg		= tcp_recvmsg,
+	.backlog_rcv		= tcp_v4_do_rcv,
+	.hash			= tcp_v4_hash,
+	.unhash			= tcp_unhash,
+	.get_port		= tcp_v4_get_port,
+	.enter_memory_pressure	= tcp_enter_memory_pressure,
+	.sockets_allocated	= &tcp_sockets_allocated,
+	.memory_allocated	= &tcp_memory_allocated,
+	.memory_pressure	= &tcp_memory_pressure,
+	.sysctl_mem		= sysctl_tcp_mem,
+	.sysctl_wmem		= sysctl_tcp_wmem,
+	.sysctl_rmem		= sysctl_tcp_rmem,
+	.max_header		= MAX_TCP_HEADER,
+	.obj_size		= sizeof(struct tcp_sock),
+};
+
+
+
+void __init tcp_v4_init(struct net_proto_family *ops)
+{
+	int err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_TCP, &tcp_socket);
+	if (err < 0)
+		panic("Failed to create the TCP control socket.\n");
+	tcp_socket->sk->sk_allocation   = GFP_ATOMIC;
+	inet_sk(tcp_socket->sk)->uc_ttl = -1;
+
+	/* Unhash it so that IP input processing does not even
+	 * see it, we do not wish this socket to see incoming
+	 * packets.
+	 */
+	tcp_socket->sk->sk_prot->unhash(tcp_socket->sk);
+}
+
+EXPORT_SYMBOL(ipv4_specific);
+EXPORT_SYMBOL(tcp_bind_hash);
+EXPORT_SYMBOL(tcp_bucket_create);
+EXPORT_SYMBOL(tcp_hashinfo);
+EXPORT_SYMBOL(tcp_inherit_port);
+EXPORT_SYMBOL(tcp_listen_wlock);
+EXPORT_SYMBOL(tcp_port_rover);
+EXPORT_SYMBOL(tcp_prot);
+EXPORT_SYMBOL(tcp_put_port);
+EXPORT_SYMBOL(tcp_unhash);
+EXPORT_SYMBOL(tcp_v4_conn_request);
+EXPORT_SYMBOL(tcp_v4_connect);
+EXPORT_SYMBOL(tcp_v4_do_rcv);
+EXPORT_SYMBOL(tcp_v4_rebuild_header);
+EXPORT_SYMBOL(tcp_v4_remember_stamp);
+EXPORT_SYMBOL(tcp_v4_send_check);
+EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
+
+#ifdef CONFIG_PROC_FS
+EXPORT_SYMBOL(tcp_proc_register);
+EXPORT_SYMBOL(tcp_proc_unregister);
+#endif
+EXPORT_SYMBOL(sysctl_local_port_range);
+EXPORT_SYMBOL(sysctl_max_syn_backlog);
+EXPORT_SYMBOL(sysctl_tcp_low_latency);
+EXPORT_SYMBOL(sysctl_tcp_tw_reuse);
+