/*
 * IPVS         An implementation of the IP virtual server support for the
 *              LINUX operating system.  IPVS is now implemented as a module
 *              over the Netfilter framework. IPVS can be used to build a
 *              high-performance and highly available server based on a
 *              cluster of servers.
 *
 * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
 *              Peter Kese <peter.kese@ijs.si>
 *              Julian Anastasov <ja@ssi.bg>
 *
 *              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.
 *
 * The IPVS code for kernel 2.2 was done by Wensong Zhang and Peter Kese,
 * with changes/fixes from Julian Anastasov, Lars Marowsky-Bree, Horms
 * and others. Many code here is taken from IP MASQ code of kernel 2.2.
 *
 * Changes:
 *
 */

#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/net.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/proc_fs.h>		/* for proc_net_* */
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/jhash.h>
#include <linux/random.h>

#include <net/net_namespace.h>
#include <net/ip_vs.h>


#ifndef CONFIG_IP_VS_TAB_BITS
#define CONFIG_IP_VS_TAB_BITS	12
#endif

/*
 * Connection hash size. Default is what was selected at compile time.
*/
static int ip_vs_conn_tab_bits = CONFIG_IP_VS_TAB_BITS;
module_param_named(conn_tab_bits, ip_vs_conn_tab_bits, int, 0444);
MODULE_PARM_DESC(conn_tab_bits, "Set connections' hash size");

/* size and mask values */
int ip_vs_conn_tab_size __read_mostly;
static int ip_vs_conn_tab_mask __read_mostly;

/*
 *  Connection hash table: for input and output packets lookups of IPVS
 */
static struct hlist_head *ip_vs_conn_tab __read_mostly;

/*  SLAB cache for IPVS connections */
static struct kmem_cache *ip_vs_conn_cachep __read_mostly;

/*  counter for no client port connections */
static atomic_t ip_vs_conn_no_cport_cnt = ATOMIC_INIT(0);

/* random value for IPVS connection hash */
static unsigned int ip_vs_conn_rnd __read_mostly;

/*
 *  Fine locking granularity for big connection hash table
 */
#define CT_LOCKARRAY_BITS  5
#define CT_LOCKARRAY_SIZE  (1<<CT_LOCKARRAY_BITS)
#define CT_LOCKARRAY_MASK  (CT_LOCKARRAY_SIZE-1)

/* We need an addrstrlen that works with or without v6 */
#ifdef CONFIG_IP_VS_IPV6
#define IP_VS_ADDRSTRLEN INET6_ADDRSTRLEN
#else
#define IP_VS_ADDRSTRLEN (8+1)
#endif

struct ip_vs_aligned_lock
{
	spinlock_t	l;
} __attribute__((__aligned__(SMP_CACHE_BYTES)));

/* lock array for conn table */
static struct ip_vs_aligned_lock
__ip_vs_conntbl_lock_array[CT_LOCKARRAY_SIZE] __cacheline_aligned;

static inline void ct_write_lock_bh(unsigned int key)
{
	spin_lock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}

static inline void ct_write_unlock_bh(unsigned int key)
{
	spin_unlock_bh(&__ip_vs_conntbl_lock_array[key&CT_LOCKARRAY_MASK].l);
}


/*
 *	Returns hash value for IPVS connection entry
 */
static unsigned int ip_vs_conn_hashkey(struct net *net, int af, unsigned int proto,
				       const union nf_inet_addr *addr,
				       __be16 port)
{
#ifdef CONFIG_IP_VS_IPV6
	if (af == AF_INET6)
		return (jhash_3words(jhash(addr, 16, ip_vs_conn_rnd),
				    (__force u32)port, proto, ip_vs_conn_rnd) ^
			((size_t)net>>8)) & ip_vs_conn_tab_mask;
#endif
	return (jhash_3words((__force u32)addr->ip, (__force u32)port, proto,
			    ip_vs_conn_rnd) ^
		((size_t)net>>8)) & ip_vs_conn_tab_mask;
}

static unsigned int ip_vs_conn_hashkey_param(const struct ip_vs_conn_param *p,
					     bool inverse)
{
	const union nf_inet_addr *addr;
	__be16 port;

	if (p->pe_data && p->pe->hashkey_raw)
		return p->pe->hashkey_raw(p, ip_vs_conn_rnd, inverse) &
			ip_vs_conn_tab_mask;

	if (likely(!inverse)) {
		addr = p->caddr;
		port = p->cport;
	} else {
		addr = p->vaddr;
		port = p->vport;
	}

	return ip_vs_conn_hashkey(p->net, p->af, p->protocol, addr, port);
}

static unsigned int ip_vs_conn_hashkey_conn(const struct ip_vs_conn *cp)
{
	struct ip_vs_conn_param p;

	ip_vs_conn_fill_param(ip_vs_conn_net(cp), cp->af, cp->protocol,
			      &cp->caddr, cp->cport, NULL, 0, &p);

	if (cp->pe) {
		p.pe = cp->pe;
		p.pe_data = cp->pe_data;
		p.pe_data_len = cp->pe_data_len;
	}

	return ip_vs_conn_hashkey_param(&p, false);
}

/*
 *	Hashes ip_vs_conn in ip_vs_conn_tab by netns,proto,addr,port.
 *	returns bool success.
 */
static inline int ip_vs_conn_hash(struct ip_vs_conn *cp)
{
	unsigned int hash;
	int ret;

	if (cp->flags & IP_VS_CONN_F_ONE_PACKET)
		return 0;

	/* Hash by protocol, client address and port */
	hash = ip_vs_conn_hashkey_conn(cp);

	ct_write_lock_bh(hash);
	spin_lock(&cp->lock);

	if (!(cp->flags & IP_VS_CONN_F_HASHED)) {
		cp->flags |= IP_VS_CONN_F_HASHED;
		atomic_inc(&cp->refcnt);
		hlist_add_head_rcu(&cp->c_list, &ip_vs_conn_tab[hash]);
		ret = 1;
	} else {
		pr_err("%s(): request for already hashed, called from %pF\n",
		       __func__, __builtin_return_address(0));
		ret = 0;
	}

	spin_unlock(&cp->lock);
	ct_write_unlock_bh(hash);

	return ret;
}


/*
 *	UNhashes ip_vs_conn from ip_vs_conn_tab.
 *	returns bool success. Caller should hold conn reference.
 */
static inline int ip_vs_conn_unhash(struct ip_vs_conn *cp)
{
	unsigned int hash;
	int ret;

	/* unhash it and decrease its reference counter */
	hash = ip_vs_conn_hashkey_conn(cp);

	ct_write_lock_bh(hash);
	spin_lock(&cp->lock);

	if (cp->flags & IP_VS_CONN_F_HASHED) {
		hlist_del_rcu(&cp->c_list);
		cp->flags &= ~IP_VS_CONN_F_HASHED;
		atomic_dec(&cp->refcnt);
		ret = 1;
	} else
		ret = 0;

	spin_unlock(&cp->lock);
	ct_write_unlock_bh(hash);

	return ret;
}

/* Try to unlink ip_vs_conn from ip_vs_conn_tab.
 * returns bool success.
 */
static inline bool ip_vs_conn_unlink(struct ip_vs_conn *cp)
{
	unsigned int hash;
	bool ret;

	hash = ip_vs_conn_hashkey_conn(cp);

	ct_write_lock_bh(hash);
	spin_lock(&cp->lock);

	if (cp->flags & IP_VS_CONN_F_HASHED) {
		ret = false;
		/* Decrease refcnt and unlink conn only if we are last user */
		if (atomic_cmpxchg(&cp->refcnt, 1, 0) == 1) {
			hlist_del_rcu(&cp->c_list);
			cp->flags &= ~IP_VS_CONN_F_HASHED;
			ret = true;
		}
	} else
		ret = atomic_read(&cp->refcnt) ? false : true;

	spin_unlock(&cp->lock);
	ct_write_unlock_bh(hash);

	return ret;
}


/*
 *  Gets ip_vs_conn associated with supplied parameters in the ip_vs_conn_tab.
 *  Called for pkts coming from OUTside-to-INside.
 *	p->caddr, p->cport: pkt source address (foreign host)
 *	p->vaddr, p->vport: pkt dest address (load balancer)
 */
static inline struct ip_vs_conn *
__ip_vs_conn_in_get(const struct ip_vs_conn_param *p)
{
	unsigned int hash;
	struct ip_vs_conn *cp;

	hash = ip_vs_conn_hashkey_param(p, false);

	rcu_read_lock();

	hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {
		if (p->cport == cp->cport && p->vport == cp->vport &&
		    cp->af == p->af &&
		    ip_vs_addr_equal(p->af, p->caddr, &cp->caddr) &&
		    ip_vs_addr_equal(p->af, p->vaddr, &cp->vaddr) &&
		    ((!p->cport) ^ (!(cp->flags & IP_VS_CONN_F_NO_CPORT))) &&
		    p->protocol == cp->protocol &&
		    ip_vs_conn_net_eq(cp, p->net)) {
			if (!__ip_vs_conn_get(cp))
				continue;
			/* HIT */
			rcu_read_unlock();
			return cp;
		}
	}

	rcu_read_unlock();

	return NULL;
}

struct ip_vs_conn *ip_vs_conn_in_get(const struct ip_vs_conn_param *p)
{
	struct ip_vs_conn *cp;

	cp = __ip_vs_conn_in_get(p);
	if (!cp && atomic_read(&ip_vs_conn_no_cport_cnt)) {
		struct ip_vs_conn_param cport_zero_p = *p;
		cport_zero_p.cport = 0;
		cp = __ip_vs_conn_in_get(&cport_zero_p);
	}

	IP_VS_DBG_BUF(9, "lookup/in %s %s:%d->%s:%d %s\n",
		      ip_vs_proto_name(p->protocol),
		      IP_VS_DBG_ADDR(p->af, p->caddr), ntohs(p->cport),
		      IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
		      cp ? "hit" : "not hit");

	return cp;
}

static int
ip_vs_conn_fill_param_proto(int af, const struct sk_buff *skb,
			    const struct ip_vs_iphdr *iph,
			    int inverse, struct ip_vs_conn_param *p)
{
	__be16 _ports[2], *pptr;
	struct net *net = skb_net(skb);

	pptr = frag_safe_skb_hp(skb, iph->len, sizeof(_ports), _ports, iph);
	if (pptr == NULL)
		return 1;

	if (likely(!inverse))
		ip_vs_conn_fill_param(net, af, iph->protocol, &iph->saddr,
				      pptr[0], &iph->daddr, pptr[1], p);
	else
		ip_vs_conn_fill_param(net, af, iph->protocol, &iph->daddr,
				      pptr[1], &iph->saddr, pptr[0], p);
	return 0;
}

struct ip_vs_conn *
ip_vs_conn_in_get_proto(int af, const struct sk_buff *skb,
			const struct ip_vs_iphdr *iph, int inverse)
{
	struct ip_vs_conn_param p;

	if (ip_vs_conn_fill_param_proto(af, skb, iph, inverse, &p))
		return NULL;

	return ip_vs_conn_in_get(&p);
}
EXPORT_SYMBOL_GPL(ip_vs_conn_in_get_proto);

/* Get reference to connection template */
struct ip_vs_conn *ip_vs_ct_in_get(const struct ip_vs_conn_param *p)
{
	unsigned int hash;
	struct ip_vs_conn *cp;

	hash = ip_vs_conn_hashkey_param(p, false);

	rcu_read_lock();

	hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {
		if (unlikely(p->pe_data && p->pe->ct_match)) {
			if (!ip_vs_conn_net_eq(cp, p->net))
				continue;
			if (p->pe == cp->pe && p->pe->ct_match(p, cp)) {
				if (__ip_vs_conn_get(cp))
					goto out;
			}
			continue;
		}

		if (cp->af == p->af &&
		    ip_vs_addr_equal(p->af, p->caddr, &cp->caddr) &&
		    /* protocol should only be IPPROTO_IP if
		     * p->vaddr is a fwmark */
		    ip_vs_addr_equal(p->protocol == IPPROTO_IP ? AF_UNSPEC :
				     p->af, p->vaddr, &cp->vaddr) &&
		    p->vport == cp->vport && p->cport == cp->cport &&
		    cp->flags & IP_VS_CONN_F_TEMPLATE &&
		    p->protocol == cp->protocol &&
		    ip_vs_conn_net_eq(cp, p->net)) {
			if (__ip_vs_conn_get(cp))
				goto out;
		}
	}
	cp = NULL;

  out:
	rcu_read_unlock();

	IP_VS_DBG_BUF(9, "template lookup/in %s %s:%d->%s:%d %s\n",
		      ip_vs_proto_name(p->protocol),
		      IP_VS_DBG_ADDR(p->af, p->caddr), ntohs(p->cport),
		      IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
		      cp ? "hit" : "not hit");

	return cp;
}

/* Gets ip_vs_conn associated with supplied parameters in the ip_vs_conn_tab.
 * Called for pkts coming from inside-to-OUTside.
 *	p->caddr, p->cport: pkt source address (inside host)
 *	p->vaddr, p->vport: pkt dest address (foreign host) */
struct ip_vs_conn *ip_vs_conn_out_get(const struct ip_vs_conn_param *p)
{
	unsigned int hash;
	struct ip_vs_conn *cp, *ret=NULL;

	/*
	 *	Check for "full" addressed entries
	 */
	hash = ip_vs_conn_hashkey_param(p, true);

	rcu_read_lock();

	hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {
		if (p->vport == cp->cport && p->cport == cp->dport &&
		    cp->af == p->af &&
		    ip_vs_addr_equal(p->af, p->vaddr, &cp->caddr) &&
		    ip_vs_addr_equal(p->af, p->caddr, &cp->daddr) &&
		    p->protocol == cp->protocol &&
		    ip_vs_conn_net_eq(cp, p->net)) {
			if (!__ip_vs_conn_get(cp))
				continue;
			/* HIT */
			ret = cp;
			break;
		}
	}

	rcu_read_unlock();

	IP_VS_DBG_BUF(9, "lookup/out %s %s:%d->%s:%d %s\n",
		      ip_vs_proto_name(p->protocol),
		      IP_VS_DBG_ADDR(p->af, p->caddr), ntohs(p->cport),
		      IP_VS_DBG_ADDR(p->af, p->vaddr), ntohs(p->vport),
		      ret ? "hit" : "not hit");

	return ret;
}

struct ip_vs_conn *
ip_vs_conn_out_get_proto(int af, const struct sk_buff *skb,
			 const struct ip_vs_iphdr *iph, int inverse)
{
	struct ip_vs_conn_param p;

	if (ip_vs_conn_fill_param_proto(af, skb, iph, inverse, &p))
		return NULL;

	return ip_vs_conn_out_get(&p);
}
EXPORT_SYMBOL_GPL(ip_vs_conn_out_get_proto);

/*
 *      Put back the conn and restart its timer with its timeout
 */
void ip_vs_conn_put(struct ip_vs_conn *cp)
{
	unsigned long t = (cp->flags & IP_VS_CONN_F_ONE_PACKET) ?
		0 : cp->timeout;
	mod_timer(&cp->timer, jiffies+t);

	__ip_vs_conn_put(cp);
}


/*
 *	Fill a no_client_port connection with a client port number
 */
void ip_vs_conn_fill_cport(struct ip_vs_conn *cp, __be16 cport)
{
	if (ip_vs_conn_unhash(cp)) {
		spin_lock_bh(&cp->lock);
		if (cp->flags & IP_VS_CONN_F_NO_CPORT) {
			atomic_dec(&ip_vs_conn_no_cport_cnt);
			cp->flags &= ~IP_VS_CONN_F_NO_CPORT;
			cp->cport = cport;
		}
		spin_unlock_bh(&cp->lock);

		/* hash on new dport */
		ip_vs_conn_hash(cp);
	}
}


/*
 *	Bind a connection entry with the corresponding packet_xmit.
 *	Called by ip_vs_conn_new.
 */
static inline void ip_vs_bind_xmit(struct ip_vs_conn *cp)
{
	switch (IP_VS_FWD_METHOD(cp)) {
	case IP_VS_CONN_F_MASQ:
		cp->packet_xmit = ip_vs_nat_xmit;
		break;

	case IP_VS_CONN_F_TUNNEL:
#ifdef CONFIG_IP_VS_IPV6
		if (cp->daf == AF_INET6)
			cp->packet_xmit = ip_vs_tunnel_xmit_v6;
		else
#endif
			cp->packet_xmit = ip_vs_tunnel_xmit;
		break;

	case IP_VS_CONN_F_DROUTE:
		cp->packet_xmit = ip_vs_dr_xmit;
		break;

	case IP_VS_CONN_F_LOCALNODE:
		cp->packet_xmit = ip_vs_null_xmit;
		break;

	case IP_VS_CONN_F_BYPASS:
		cp->packet_xmit = ip_vs_bypass_xmit;
		break;
	}
}

#ifdef CONFIG_IP_VS_IPV6
static inline void ip_vs_bind_xmit_v6(struct ip_vs_conn *cp)
{
	switch (IP_VS_FWD_METHOD(cp)) {
	case IP_VS_CONN_F_MASQ:
		cp->packet_xmit = ip_vs_nat_xmit_v6;
		break;

	case IP_VS_CONN_F_TUNNEL:
		if (cp->daf == AF_INET6)
			cp->packet_xmit = ip_vs_tunnel_xmit_v6;
		else
			cp->packet_xmit = ip_vs_tunnel_xmit;
		break;

	case IP_VS_CONN_F_DROUTE:
		cp->packet_xmit = ip_vs_dr_xmit_v6;
		break;

	case IP_VS_CONN_F_LOCALNODE:
		cp->packet_xmit = ip_vs_null_xmit;
		break;

	case IP_VS_CONN_F_BYPASS:
		cp->packet_xmit = ip_vs_bypass_xmit_v6;
		break;
	}
}
#endif


static inline int ip_vs_dest_totalconns(struct ip_vs_dest *dest)
{
	return atomic_read(&dest->activeconns)
		+ atomic_read(&dest->inactconns);
}

/*
 *	Bind a connection entry with a virtual service destination
 *	Called just after a new connection entry is created.
 */
static inline void
ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest *dest)
{
	unsigned int conn_flags;
	__u32 flags;

	/* if dest is NULL, then return directly */
	if (!dest)
		return;

	/* Increase the refcnt counter of the dest */
	ip_vs_dest_hold(dest);

	conn_flags = atomic_read(&dest->conn_flags);
	if (cp->protocol != IPPROTO_UDP)
		conn_flags &= ~IP_VS_CONN_F_ONE_PACKET;
	flags = cp->flags;
	/* Bind with the destination and its corresponding transmitter */
	if (flags & IP_VS_CONN_F_SYNC) {
		/* if the connection is not template and is created
		 * by sync, preserve the activity flag.
		 */
		if (!(flags & IP_VS_CONN_F_TEMPLATE))
			conn_flags &= ~IP_VS_CONN_F_INACTIVE;
		/* connections inherit forwarding method from dest */
		flags &= ~(IP_VS_CONN_F_FWD_MASK | IP_VS_CONN_F_NOOUTPUT);
	}
	flags |= conn_flags;
	cp->flags = flags;
	cp->dest = dest;

	IP_VS_DBG_BUF(7, "Bind-dest %s c:%s:%d v:%s:%d "
		      "d:%s:%d fwd:%c s:%u conn->flags:%X conn->refcnt:%d "
		      "dest->refcnt:%d\n",
		      ip_vs_proto_name(cp->protocol),
		      IP_VS_DBG_ADDR(cp->af, &cp->caddr), ntohs(cp->cport),
		      IP_VS_DBG_ADDR(cp->af, &cp->vaddr), ntohs(cp->vport),
		      IP_VS_DBG_ADDR(cp->daf, &cp->daddr), ntohs(cp->dport),
		      ip_vs_fwd_tag(cp), cp->state,
		      cp->flags, atomic_read(&cp->refcnt),
		      atomic_read(&dest->refcnt));

	/* Update the connection counters */
	if (!(flags & IP_VS_CONN_F_TEMPLATE)) {
		/* It is a normal connection, so modify the counters
		 * according to the flags, later the protocol can
		 * update them on state change
		 */
		if (!(flags & IP_VS_CONN_F_INACTIVE))
			atomic_inc(&dest->activeconns);
		else
			atomic_inc(&dest->inactconns);
	} else {
		/* It is a persistent connection/template, so increase
		   the persistent connection counter */
		atomic_inc(&dest->persistconns);
	}

	if (dest->u_threshold != 0 &&
	    ip_vs_dest_totalconns(dest) >= dest->u_threshold)
		dest->flags |= IP_VS_DEST_F_OVERLOAD;
}


/*
 * Check if there is a destination for the connection, if so
 * bind the connection to the destination.
 */
void ip_vs_try_bind_dest(struct ip_vs_conn *cp)
{
	struct ip_vs_dest *dest;

	rcu_read_lock();

	/* This function is only invoked by the synchronization code. We do
	 * not currently support heterogeneous pools with synchronization,
	 * so we can make the assumption that the svc_af is the same as the
	 * dest_af
	 */
	dest = ip_vs_find_dest(ip_vs_conn_net(cp), cp->af, cp->af, &cp->daddr,
			       cp->dport, &cp->vaddr, cp->vport,
			       cp->protocol, cp->fwmark, cp->flags);
	if (dest) {
		struct ip_vs_proto_data *pd;

		spin_lock_bh(&cp->lock);
		if (cp->dest) {
			spin_unlock_bh(&cp->lock);
			rcu_read_unlock();
			return;
		}

		/* Applications work depending on the forwarding method
		 * but better to reassign them always when binding dest */
		if (cp->app)
			ip_vs_unbind_app(cp);

		ip_vs_bind_dest(cp, dest);
		spin_unlock_bh(&cp->lock);

		/* Update its packet transmitter */
		cp->packet_xmit = NULL;
#ifdef CONFIG_IP_VS_IPV6
		if (cp->af == AF_INET6)
			ip_vs_bind_xmit_v6(cp);
		else
#endif
			ip_vs_bind_xmit(cp);

		pd = ip_vs_proto_data_get(ip_vs_conn_net(cp), cp->protocol);
		if (pd && atomic_read(&pd->appcnt))
			ip_vs_bind_app(cp, pd->pp);
	}
	rcu_read_unlock();
}


/*
 *	Unbind a connection entry with its VS destination
 *	Called by the ip_vs_conn_expire function.
 */
static inline void ip_vs_unbind_dest(struct ip_vs_conn *cp)
{
	struct ip_vs_dest *dest = cp->dest;

	if (!dest)
		return;

	IP_VS_DBG_BUF(7, "Unbind-dest %s c:%s:%d v:%s:%d "
		      "d:%s:%d fwd:%c s:%u conn->flags:%X conn->refcnt:%d "
		      "dest->refcnt:%d\n",
		      ip_vs_proto_name(cp->protocol),
		      IP_VS_DBG_ADDR(cp->af, &cp->caddr), ntohs(cp->cport),
		      IP_VS_DBG_ADDR(cp->af, &cp->vaddr), ntohs(cp->vport),
		      IP_VS_DBG_ADDR(cp->daf, &cp->daddr), ntohs(cp->dport),
		      ip_vs_fwd_tag(cp), cp->state,
		      cp->flags, atomic_read(&cp->refcnt),
		      atomic_read(&dest->refcnt));

	/* Update the connection counters */
	if (!(cp->flags & IP_VS_CONN_F_TEMPLATE)) {
		/* It is a normal connection, so decrease the inactconns
		   or activeconns counter */
		if (cp->flags & IP_VS_CONN_F_INACTIVE) {
			atomic_dec(&dest->inactconns);
		} else {
			atomic_dec(&dest->activeconns);
		}
	} else {
		/* It is a persistent connection/template, so decrease
		   the persistent connection counter */
		atomic_dec(&dest->persistconns);
	}

	if (dest->l_threshold != 0) {
		if (ip_vs_dest_totalconns(dest) < dest->l_threshold)
			dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
	} else if (dest->u_threshold != 0) {
		if (ip_vs_dest_totalconns(dest) * 4 < dest->u_threshold * 3)
			dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
	} else {
		if (dest->flags & IP_VS_DEST_F_OVERLOAD)
			dest->flags &= ~IP_VS_DEST_F_OVERLOAD;
	}

	ip_vs_dest_put(dest);
}

static int expire_quiescent_template(struct netns_ipvs *ipvs,
				     struct ip_vs_dest *dest)
{
#ifdef CONFIG_SYSCTL
	return ipvs->sysctl_expire_quiescent_template &&
		(atomic_read(&dest->weight) == 0);
#else
	return 0;
#endif
}

/*
 *	Checking if the destination of a connection template is available.
 *	If available, return 1, otherwise invalidate this connection
 *	template and return 0.
 */
int ip_vs_check_template(struct ip_vs_conn *ct)
{
	struct ip_vs_dest *dest = ct->dest;
	struct netns_ipvs *ipvs = net_ipvs(ip_vs_conn_net(ct));

	/*
	 * Checking the dest server status.
	 */
	if ((dest == NULL) ||
	    !(dest->flags & IP_VS_DEST_F_AVAILABLE) ||
	    expire_quiescent_template(ipvs, dest)) {
		IP_VS_DBG_BUF(9, "check_template: dest not available for "
			      "protocol %s s:%s:%d v:%s:%d "
			      "-> d:%s:%d\n",
			      ip_vs_proto_name(ct->protocol),
			      IP_VS_DBG_ADDR(ct->af, &ct->caddr),
			      ntohs(ct->cport),
			      IP_VS_DBG_ADDR(ct->af, &ct->vaddr),
			      ntohs(ct->vport),
			      IP_VS_DBG_ADDR(ct->daf, &ct->daddr),
			      ntohs(ct->dport));

		/*
		 * Invalidate the connection template
		 */
		if (ct->vport != htons(0xffff)) {
			if (ip_vs_conn_unhash(ct)) {
				ct->dport = htons(0xffff);
				ct->vport = htons(0xffff);
				ct->cport = 0;
				ip_vs_conn_hash(ct);
			}
		}

		/*
		 * Simply decrease the refcnt of the template,
		 * don't restart its timer.
		 */
		__ip_vs_conn_put(ct);
		return 0;
	}
	return 1;
}

static void ip_vs_conn_rcu_free(struct rcu_head *head)
{
	struct ip_vs_conn *cp = container_of(head, struct ip_vs_conn,
					     rcu_head);

	ip_vs_pe_put(cp->pe);
	kfree(cp->pe_data);
	kmem_cache_free(ip_vs_conn_cachep, cp);
}

static void ip_vs_conn_expire(unsigned long data)
{
	struct ip_vs_conn *cp = (struct ip_vs_conn *)data;
	struct net *net = ip_vs_conn_net(cp);
	struct netns_ipvs *ipvs = net_ipvs(net);

	/*
	 *	do I control anybody?
	 */
	if (atomic_read(&cp->n_control))
		goto expire_later;

	/* Unlink conn if not referenced anymore */
	if (likely(ip_vs_conn_unlink(cp))) {
		/* delete the timer if it is activated by other users */
		del_timer(&cp->timer);

		/* does anybody control me? */
		if (cp->control)
			ip_vs_control_del(cp);

		if (cp->flags & IP_VS_CONN_F_NFCT) {
			/* Do not access conntracks during subsys cleanup
			 * because nf_conntrack_find_get can not be used after
			 * conntrack cleanup for the net.
			 */
			smp_rmb();
			if (ipvs->enable)
				ip_vs_conn_drop_conntrack(cp);
		}

		if (unlikely(cp->app != NULL))
			ip_vs_unbind_app(cp);
		ip_vs_unbind_dest(cp);
		if (cp->flags & IP_VS_CONN_F_NO_CPORT)
			atomic_dec(&ip_vs_conn_no_cport_cnt);
		call_rcu(&cp->rcu_head, ip_vs_conn_rcu_free);
		atomic_dec(&ipvs->conn_count);
		return;
	}

  expire_later:
	IP_VS_DBG(7, "delayed: conn->refcnt=%d conn->n_control=%d\n",
		  atomic_read(&cp->refcnt),
		  atomic_read(&cp->n_control));

	atomic_inc(&cp->refcnt);
	cp->timeout = 60*HZ;

	if (ipvs->sync_state & IP_VS_STATE_MASTER)
		ip_vs_sync_conn(net, cp, sysctl_sync_threshold(ipvs));

	ip_vs_conn_put(cp);
}

/* Modify timer, so that it expires as soon as possible.
 * Can be called without reference only if under RCU lock.
 */
void ip_vs_conn_expire_now(struct ip_vs_conn *cp)
{
	/* Using mod_timer_pending will ensure the timer is not
	 * modified after the final del_timer in ip_vs_conn_expire.
	 */
	if (timer_pending(&cp->timer) &&
	    time_after(cp->timer.expires, jiffies))
		mod_timer_pending(&cp->timer, jiffies);
}


/*
 *	Create a new connection entry and hash it into the ip_vs_conn_tab
 */
struct ip_vs_conn *
ip_vs_conn_new(const struct ip_vs_conn_param *p, int dest_af,
	       const union nf_inet_addr *daddr, __be16 dport, unsigned int flags,
	       struct ip_vs_dest *dest, __u32 fwmark)
{
	struct ip_vs_conn *cp;
	struct netns_ipvs *ipvs = net_ipvs(p->net);
	struct ip_vs_proto_data *pd = ip_vs_proto_data_get(p->net,
							   p->protocol);

	cp = kmem_cache_alloc(ip_vs_conn_cachep, GFP_ATOMIC);
	if (cp == NULL) {
		IP_VS_ERR_RL("%s(): no memory\n", __func__);
		return NULL;
	}

	INIT_HLIST_NODE(&cp->c_list);
	setup_timer(&cp->timer, ip_vs_conn_expire, (unsigned long)cp);
	ip_vs_conn_net_set(cp, p->net);
	cp->af		   = p->af;
	cp->daf		   = dest_af;
	cp->protocol	   = p->protocol;
	ip_vs_addr_set(p->af, &cp->caddr, p->caddr);
	cp->cport	   = p->cport;
	/* proto should only be IPPROTO_IP if p->vaddr is a fwmark */
	ip_vs_addr_set(p->protocol == IPPROTO_IP ? AF_UNSPEC : p->af,
		       &cp->vaddr, p->vaddr);
	cp->vport	   = p->vport;
	ip_vs_addr_set(cp->daf, &cp->daddr, daddr);
	cp->dport          = dport;
	cp->flags	   = flags;
	cp->fwmark         = fwmark;
	if (flags & IP_VS_CONN_F_TEMPLATE && p->pe) {
		ip_vs_pe_get(p->pe);
		cp->pe = p->pe;
		cp->pe_data = p->pe_data;
		cp->pe_data_len = p->pe_data_len;
	} else {
		cp->pe = NULL;
		cp->pe_data = NULL;
		cp->pe_data_len = 0;
	}
	spin_lock_init(&cp->lock);

	/*
	 * Set the entry is referenced by the current thread before hashing
	 * it in the table, so that other thread run ip_vs_random_dropentry
	 * but cannot drop this entry.
	 */
	atomic_set(&cp->refcnt, 1);

	cp->control = NULL;
	atomic_set(&cp->n_control, 0);
	atomic_set(&cp->in_pkts, 0);

	cp->packet_xmit = NULL;
	cp->app = NULL;
	cp->app_data = NULL;
	/* reset struct ip_vs_seq */
	cp->in_seq.delta = 0;
	cp->out_seq.delta = 0;

	atomic_inc(&ipvs->conn_count);
	if (flags & IP_VS_CONN_F_NO_CPORT)
		atomic_inc(&ip_vs_conn_no_cport_cnt);

	/* Bind the connection with a destination server */
	cp->dest = NULL;
	ip_vs_bind_dest(cp, dest);

	/* Set its state and timeout */
	cp->state = 0;
	cp->old_state = 0;
	cp->timeout = 3*HZ;
	cp->sync_endtime = jiffies & ~3UL;

	/* Bind its packet transmitter */
#ifdef CONFIG_IP_VS_IPV6
	if (p->af == AF_INET6)
		ip_vs_bind_xmit_v6(cp);
	else
#endif
		ip_vs_bind_xmit(cp);

	if (unlikely(pd && atomic_read(&pd->appcnt)))
		ip_vs_bind_app(cp, pd->pp);

	/*
	 * Allow conntrack to be preserved. By default, conntrack
	 * is created and destroyed for every packet.
	 * Sometimes keeping conntrack can be useful for
	 * IP_VS_CONN_F_ONE_PACKET too.
	 */

	if (ip_vs_conntrack_enabled(ipvs))
		cp->flags |= IP_VS_CONN_F_NFCT;

	/* Hash it in the ip_vs_conn_tab finally */
	ip_vs_conn_hash(cp);

	return cp;
}

/*
 *	/proc/net/ip_vs_conn entries
 */
#ifdef CONFIG_PROC_FS
struct ip_vs_iter_state {
	struct seq_net_private	p;
	struct hlist_head	*l;
};

static void *ip_vs_conn_array(struct seq_file *seq, loff_t pos)
{
	int idx;
	struct ip_vs_conn *cp;
	struct ip_vs_iter_state *iter = seq->private;

	for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {
		hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {
			/* __ip_vs_conn_get() is not needed by
			 * ip_vs_conn_seq_show and ip_vs_conn_sync_seq_show
			 */
			if (pos-- == 0) {
				iter->l = &ip_vs_conn_tab[idx];
				return cp;
			}
		}
		cond_resched_rcu();
	}

	return NULL;
}

static void *ip_vs_conn_seq_start(struct seq_file *seq, loff_t *pos)
	__acquires(RCU)
{
	struct ip_vs_iter_state *iter = seq->private;

	iter->l = NULL;
	rcu_read_lock();
	return *pos ? ip_vs_conn_array(seq, *pos - 1) :SEQ_START_TOKEN;
}

static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct ip_vs_conn *cp = v;
	struct ip_vs_iter_state *iter = seq->private;
	struct hlist_node *e;
	struct hlist_head *l = iter->l;
	int idx;

	++*pos;
	if (v == SEQ_START_TOKEN)
		return ip_vs_conn_array(seq, 0);

	/* more on same hash chain? */
	e = rcu_dereference(hlist_next_rcu(&cp->c_list));
	if (e)
		return hlist_entry(e, struct ip_vs_conn, c_list);

	idx = l - ip_vs_conn_tab;
	while (++idx < ip_vs_conn_tab_size) {
		hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {
			iter->l = &ip_vs_conn_tab[idx];
			return cp;
		}
		cond_resched_rcu();
	}
	iter->l = NULL;
	return NULL;
}

static void ip_vs_conn_seq_stop(struct seq_file *seq, void *v)
	__releases(RCU)
{
	rcu_read_unlock();
}

static int ip_vs_conn_seq_show(struct seq_file *seq, void *v)
{

	if (v == SEQ_START_TOKEN)
		seq_puts(seq,
   "Pro FromIP   FPrt ToIP     TPrt DestIP   DPrt State       Expires PEName PEData\n");
	else {
		const struct ip_vs_conn *cp = v;
		struct net *net = seq_file_net(seq);
		char pe_data[IP_VS_PENAME_MAXLEN + IP_VS_PEDATA_MAXLEN + 3];
		size_t len = 0;
		char dbuf[IP_VS_ADDRSTRLEN];

		if (!ip_vs_conn_net_eq(cp, net))
			return 0;
		if (cp->pe_data) {
			pe_data[0] = ' ';
			len = strlen(cp->pe->name);
			memcpy(pe_data + 1, cp->pe->name, len);
			pe_data[len + 1] = ' ';
			len += 2;
			len += cp->pe->show_pe_data(cp, pe_data + len);
		}
		pe_data[len] = '\0';

#ifdef CONFIG_IP_VS_IPV6
		if (cp->daf == AF_INET6)
			snprintf(dbuf, sizeof(dbuf), "%pI6", &cp->daddr.in6);
		else
#endif
			snprintf(dbuf, sizeof(dbuf), "%08X",
				 ntohl(cp->daddr.ip));

#ifdef CONFIG_IP_VS_IPV6
		if (cp->af == AF_INET6)
			seq_printf(seq, "%-3s %pI6 %04X %pI6 %04X "
				"%s %04X %-11s %7lu%s\n",
				ip_vs_proto_name(cp->protocol),
				&cp->caddr.in6, ntohs(cp->cport),
				&cp->vaddr.in6, ntohs(cp->vport),
				dbuf, ntohs(cp->dport),
				ip_vs_state_name(cp->protocol, cp->state),
				(cp->timer.expires-jiffies)/HZ, pe_data);
		else
#endif
			seq_printf(seq,
				"%-3s %08X %04X %08X %04X"
				" %s %04X %-11s %7lu%s\n",
				ip_vs_proto_name(cp->protocol),
				ntohl(cp->caddr.ip), ntohs(cp->cport),
				ntohl(cp->vaddr.ip), ntohs(cp->vport),
				dbuf, ntohs(cp->dport),
				ip_vs_state_name(cp->protocol, cp->state),
				(cp->timer.expires-jiffies)/HZ, pe_data);
	}
	return 0;
}

static const struct seq_operations ip_vs_conn_seq_ops = {
	.start = ip_vs_conn_seq_start,
	.next  = ip_vs_conn_seq_next,
	.stop  = ip_vs_conn_seq_stop,
	.show  = ip_vs_conn_seq_show,
};

static int ip_vs_conn_open(struct inode *inode, struct file *file)
{
	return seq_open_net(inode, file, &ip_vs_conn_seq_ops,
			    sizeof(struct ip_vs_iter_state));
}

static const struct file_operations ip_vs_conn_fops = {
	.owner	 = THIS_MODULE,
	.open    = ip_vs_conn_open,
	.read    = seq_read,
	.llseek  = seq_lseek,
	.release = seq_release_net,
};

static const char *ip_vs_origin_name(unsigned int flags)
{
	if (flags & IP_VS_CONN_F_SYNC)
		return "SYNC";
	else
		return "LOCAL";
}

static int ip_vs_conn_sync_seq_show(struct seq_file *seq, void *v)
{
	char dbuf[IP_VS_ADDRSTRLEN];

	if (v == SEQ_START_TOKEN)
		seq_puts(seq,
   "Pro FromIP   FPrt ToIP     TPrt DestIP   DPrt State       Origin Expires\n");
	else {
		const struct ip_vs_conn *cp = v;
		struct net *net = seq_file_net(seq);

		if (!ip_vs_conn_net_eq(cp, net))
			return 0;

#ifdef CONFIG_IP_VS_IPV6
		if (cp->daf == AF_INET6)
			snprintf(dbuf, sizeof(dbuf), "%pI6", &cp->daddr.in6);
		else
#endif
			snprintf(dbuf, sizeof(dbuf), "%08X",
				 ntohl(cp->daddr.ip));

#ifdef CONFIG_IP_VS_IPV6
		if (cp->af == AF_INET6)
			seq_printf(seq, "%-3s %pI6 %04X %pI6 %04X "
				"%s %04X %-11s %-6s %7lu\n",
				ip_vs_proto_name(cp->protocol),
				&cp->caddr.in6, ntohs(cp->cport),
				&cp->vaddr.in6, ntohs(cp->vport),
				dbuf, ntohs(cp->dport),
				ip_vs_state_name(cp->protocol, cp->state),
				ip_vs_origin_name(cp->flags),
				(cp->timer.expires-jiffies)/HZ);
		else
#endif
			seq_printf(seq,
				"%-3s %08X %04X %08X %04X "
				"%s %04X %-11s %-6s %7lu\n",
				ip_vs_proto_name(cp->protocol),
				ntohl(cp->caddr.ip), ntohs(cp->cport),
				ntohl(cp->vaddr.ip), ntohs(cp->vport),
				dbuf, ntohs(cp->dport),
				ip_vs_state_name(cp->protocol, cp->state),
				ip_vs_origin_name(cp->flags),
				(cp->timer.expires-jiffies)/HZ);
	}
	return 0;
}

static const struct seq_operations ip_vs_conn_sync_seq_ops = {
	.start = ip_vs_conn_seq_start,
	.next  = ip_vs_conn_seq_next,
	.stop  = ip_vs_conn_seq_stop,
	.show  = ip_vs_conn_sync_seq_show,
};

static int ip_vs_conn_sync_open(struct inode *inode, struct file *file)
{
	return seq_open_net(inode, file, &ip_vs_conn_sync_seq_ops,
			    sizeof(struct ip_vs_iter_state));
}

static const struct file_operations ip_vs_conn_sync_fops = {
	.owner	 = THIS_MODULE,
	.open    = ip_vs_conn_sync_open,
	.read    = seq_read,
	.llseek  = seq_lseek,
	.release = seq_release_net,
};

#endif


/*
 *      Randomly drop connection entries before running out of memory
 */
static inline int todrop_entry(struct ip_vs_conn *cp)
{
	/*
	 * The drop rate array needs tuning for real environments.
	 * Called from timer bh only => no locking
	 */
	static const char todrop_rate[9] = {0, 1, 2, 3, 4, 5, 6, 7, 8};
	static char todrop_counter[9] = {0};
	int i;

	/* if the conn entry hasn't lasted for 60 seconds, don't drop it.
	   This will leave enough time for normal connection to get
	   through. */
	if (time_before(cp->timeout + jiffies, cp->timer.expires + 60*HZ))
		return 0;

	/* Don't drop the entry if its number of incoming packets is not
	   located in [0, 8] */
	i = atomic_read(&cp->in_pkts);
	if (i > 8 || i < 0) return 0;

	if (!todrop_rate[i]) return 0;
	if (--todrop_counter[i] > 0) return 0;

	todrop_counter[i] = todrop_rate[i];
	return 1;
}

/* Called from keventd and must protect itself from softirqs */
void ip_vs_random_dropentry(struct net *net)
{
	int idx;
	struct ip_vs_conn *cp, *cp_c;

	rcu_read_lock();
	/*
	 * Randomly scan 1/32 of the whole table every second
	 */
	for (idx = 0; idx < (ip_vs_conn_tab_size>>5); idx++) {
		unsigned int hash = prandom_u32() & ip_vs_conn_tab_mask;

		hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[hash], c_list) {
			if (cp->flags & IP_VS_CONN_F_TEMPLATE)
				/* connection template */
				continue;
			if (!ip_vs_conn_net_eq(cp, net))
				continue;
			if (cp->protocol == IPPROTO_TCP) {
				switch(cp->state) {
				case IP_VS_TCP_S_SYN_RECV:
				case IP_VS_TCP_S_SYNACK:
					break;

				case IP_VS_TCP_S_ESTABLISHED:
					if (todrop_entry(cp))
						break;
					continue;

				default:
					continue;
				}
			} else if (cp->protocol == IPPROTO_SCTP) {
				switch (cp->state) {
				case IP_VS_SCTP_S_INIT1:
				case IP_VS_SCTP_S_INIT:
					break;
				case IP_VS_SCTP_S_ESTABLISHED:
					if (todrop_entry(cp))
						break;
					continue;
				default:
					continue;
				}
			} else {
				if (!todrop_entry(cp))
					continue;
			}

			IP_VS_DBG(4, "del connection\n");
			ip_vs_conn_expire_now(cp);
			cp_c = cp->control;
			/* cp->control is valid only with reference to cp */
			if (cp_c && __ip_vs_conn_get(cp)) {
				IP_VS_DBG(4, "del conn template\n");
				ip_vs_conn_expire_now(cp_c);
				__ip_vs_conn_put(cp);
			}
		}
		cond_resched_rcu();
	}
	rcu_read_unlock();
}


/*
 *      Flush all the connection entries in the ip_vs_conn_tab
 */
static void ip_vs_conn_flush(struct net *net)
{
	int idx;
	struct ip_vs_conn *cp, *cp_c;
	struct netns_ipvs *ipvs = net_ipvs(net);

flush_again:
	rcu_read_lock();
	for (idx = 0; idx < ip_vs_conn_tab_size; idx++) {

		hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) {
			if (!ip_vs_conn_net_eq(cp, net))
				continue;
			IP_VS_DBG(4, "del connection\n");
			ip_vs_conn_expire_now(cp);
			cp_c = cp->control;
			/* cp->control is valid only with reference to cp */
			if (cp_c && __ip_vs_conn_get(cp)) {
				IP_VS_DBG(4, "del conn template\n");
				ip_vs_conn_expire_now(cp_c);
				__ip_vs_conn_put(cp);
			}
		}
		cond_resched_rcu();
	}
	rcu_read_unlock();

	/* the counter may be not NULL, because maybe some conn entries
	   are run by slow timer handler or unhashed but still referred */
	if (atomic_read(&ipvs->conn_count) != 0) {
		schedule();
		goto flush_again;
	}
}
/*
 * per netns init and exit
 */
int __net_init ip_vs_conn_net_init(struct net *net)
{
	struct netns_ipvs *ipvs = net_ipvs(net);

	atomic_set(&ipvs->conn_count, 0);

	proc_create("ip_vs_conn", 0, net->proc_net, &ip_vs_conn_fops);
	proc_create("ip_vs_conn_sync", 0, net->proc_net, &ip_vs_conn_sync_fops);
	return 0;
}

void __net_exit ip_vs_conn_net_cleanup(struct net *net)
{
	/* flush all the connection entries first */
	ip_vs_conn_flush(net);
	remove_proc_entry("ip_vs_conn", net->proc_net);
	remove_proc_entry("ip_vs_conn_sync", net->proc_net);
}

int __init ip_vs_conn_init(void)
{
	int idx;

	/* Compute size and mask */
	ip_vs_conn_tab_size = 1 << ip_vs_conn_tab_bits;
	ip_vs_conn_tab_mask = ip_vs_conn_tab_size - 1;

	/*
	 * Allocate the connection hash table and initialize its list heads
	 */
	ip_vs_conn_tab = vmalloc(ip_vs_conn_tab_size * sizeof(*ip_vs_conn_tab));
	if (!ip_vs_conn_tab)
		return -ENOMEM;

	/* Allocate ip_vs_conn slab cache */
	ip_vs_conn_cachep = kmem_cache_create("ip_vs_conn",
					      sizeof(struct ip_vs_conn), 0,
					      SLAB_HWCACHE_ALIGN, NULL);
	if (!ip_vs_conn_cachep) {
		vfree(ip_vs_conn_tab);
		return -ENOMEM;
	}

	pr_info("Connection hash table configured "
		"(size=%d, memory=%ldKbytes)\n",
		ip_vs_conn_tab_size,
		(long)(ip_vs_conn_tab_size*sizeof(struct list_head))/1024);
	IP_VS_DBG(0, "Each connection entry needs %Zd bytes at least\n",
		  sizeof(struct ip_vs_conn));

	for (idx = 0; idx < ip_vs_conn_tab_size; idx++)
		INIT_HLIST_HEAD(&ip_vs_conn_tab[idx]);

	for (idx = 0; idx < CT_LOCKARRAY_SIZE; idx++)  {
		spin_lock_init(&__ip_vs_conntbl_lock_array[idx].l);
	}

	/* calculate the random value for connection hash */
	get_random_bytes(&ip_vs_conn_rnd, sizeof(ip_vs_conn_rnd));

	return 0;
}

void ip_vs_conn_cleanup(void)
{
	/* Wait all ip_vs_conn_rcu_free() callbacks to complete */
	rcu_barrier();
	/* Release the empty cache */
	kmem_cache_destroy(ip_vs_conn_cachep);
	vfree(ip_vs_conn_tab);
}