inetpeer.h 3.01 KB
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/*
 *		INETPEER - A storage for permanent information about peers
 *
 *  Authors:	Andrey V. Savochkin <saw@msu.ru>
 */

#ifndef _NET_INETPEER_H
#define _NET_INETPEER_H

#include <linux/types.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/spinlock.h>
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#include <linux/rtnetlink.h>
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#include <net/ipv6.h>
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#include <linux/atomic.h>
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struct inetpeer_addr_base {
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	union {
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		__be32			a4;
		__be32			a6[4];
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	};
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};

struct inetpeer_addr {
	struct inetpeer_addr_base	addr;
	__u16				family;
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};
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struct inet_peer {
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	/* group together avl_left,avl_right,v4daddr to speedup lookups */
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	struct inet_peer __rcu	*avl_left, *avl_right;
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	struct inetpeer_addr	daddr;
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	__u32			avl_height;
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	u32			metrics[RTAX_MAX];
	u32			rate_tokens;	/* rate limiting for ICMP */
	unsigned long		rate_last;
	unsigned long		pmtu_expires;
	u32			pmtu_orig;
	u32			pmtu_learned;
	struct inetpeer_addr_base redirect_learned;
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	/*
	 * Once inet_peer is queued for deletion (refcnt == -1), following fields
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	 * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
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	 * We can share memory with rcu_head to help keep inet_peer small.
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	 */
	union {
		struct {
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			atomic_t			rid;		/* Frag reception counter */
			atomic_t			ip_id_count;	/* IP ID for the next packet */
			__u32				tcp_ts;
			__u32				tcp_ts_stamp;
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		};
		struct rcu_head         rcu;
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		struct inet_peer	*gc_next;
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	};
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	/* following fields might be frequently dirtied */
	__u32			dtime;	/* the time of last use of not referenced entries */
	atomic_t		refcnt;
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};

void			inet_initpeers(void) __init;

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#define INETPEER_METRICS_NEW	(~(u32) 0)

static inline bool inet_metrics_new(const struct inet_peer *p)
{
	return p->metrics[RTAX_LOCK-1] == INETPEER_METRICS_NEW;
}

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/* can be called with or without local BH being disabled */
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struct inet_peer	*inet_getpeer(const struct inetpeer_addr *daddr, int create);
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static inline struct inet_peer *inet_getpeer_v4(__be32 v4daddr, int create)
{
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	struct inetpeer_addr daddr;
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	daddr.addr.a4 = v4daddr;
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	daddr.family = AF_INET;
	return inet_getpeer(&daddr, create);
}
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static inline struct inet_peer *inet_getpeer_v6(const struct in6_addr *v6daddr, int create)
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{
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	struct inetpeer_addr daddr;
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	ipv6_addr_copy((struct in6_addr *)daddr.addr.a6, v6daddr);
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	daddr.family = AF_INET6;
	return inet_getpeer(&daddr, create);
}

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/* can be called from BH context or outside */
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extern void inet_putpeer(struct inet_peer *p);
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extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);
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/*
 * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
 * tcp_ts_stamp if no refcount is taken on inet_peer
 */
static inline void inet_peer_refcheck(const struct inet_peer *p)
{
	WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
}


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/* can be called with or without local BH being disabled */
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static inline int inet_getid(struct inet_peer *p, int more)
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{
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	int old, new;
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	more++;
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	inet_peer_refcheck(p);
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	do {
		old = atomic_read(&p->ip_id_count);
		new = old + more;
		if (!new)
			new = 1;
	} while (atomic_cmpxchg(&p->ip_id_count, old, new) != old);
	return new;
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}

#endif /* _NET_INETPEER_H */