nf_conntrack_l3proto.h

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/*
 * Copyright (C)2003,2004 USAGI/WIDE Project
 *
 * Header for use in defining a given L3 protocol for connection tracking.
 *
 * Author:
 *  Yasuyuki Kozakai @USAGI <[email protected]>
 *
 * Derived from include/netfilter_ipv4/ip_conntrack_protocol.h
 */

#ifndef _NF_CONNTRACK_L3PROTO_H
#define _NF_CONNTRACK_L3PROTO_H
#include <linux/netlink.h>
#include <net/netlink.h>
#include <linux/seq_file.h>
#include <net/netfilter/nf_conntrack.h>

struct nf_conntrack_l3proto {
    /* L3 Protocol Family number. ex) PF_INET */
    u_int16_t l3proto;

    /* Protocol name */
    const char *name;

    /*
     * Try to fill in the third arg: nhoff is offset of l3 proto
         * hdr.  Return true if possible.
     */
    bool (*pkt_to_tuple)(const struct sk_buff *skb, unsigned int nhoff,
                 struct nf_conntrack_tuple *tuple);

    /*
     * Invert the per-proto part of the tuple: ie. turn xmit into reply.
     * Some packets can't be inverted: return 0 in that case.
     */
    bool (*invert_tuple)(struct nf_conntrack_tuple *inverse,
                 const struct nf_conntrack_tuple *orig);

    /* Print out the per-protocol part of the tuple. */
    int (*print_tuple)(struct seq_file *s,
               const struct nf_conntrack_tuple *);

    /*
     * Called before tracking. 
     *  *dataoff: offset of protocol header (TCP, UDP,...) in skb
     *  *protonum: protocol number
     */
    int (*get_l4proto)(const struct sk_buff *skb, unsigned int nhoff,
               unsigned int *dataoff, u_int8_t *protonum);

    int (*tuple_to_nlattr)(struct sk_buff *skb,
                   const struct nf_conntrack_tuple *t);

    /*
     * Calculate size of tuple nlattr
     */
    int (*nlattr_tuple_size)(void);

    int (*nlattr_to_tuple)(struct nlattr *tb[],
                   struct nf_conntrack_tuple *t);
    const struct nla_policy *nla_policy;

    size_t nla_size;

#ifdef CONFIG_SYSCTL
    const char      *ctl_table_path;
#endif /* CONFIG_SYSCTL */

    /* Init l3proto pernet data */
    int (*init_net)(struct net *net);

    /* Module (if any) which this is connected to. */
    struct module *me;
};

extern struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX];

/* Protocol registration. */
extern int nf_conntrack_l3proto_register(struct net *net,
                     struct nf_conntrack_l3proto *proto);
extern void nf_conntrack_l3proto_unregister(struct net *net,
                        struct nf_conntrack_l3proto *proto);
extern struct nf_conntrack_l3proto *nf_ct_l3proto_find_get(u_int16_t l3proto);
extern void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p);

/* Existing built-in protocols */
extern struct nf_conntrack_l3proto nf_conntrack_l3proto_generic;

static inline struct nf_conntrack_l3proto *
__nf_ct_l3proto_find(u_int16_t l3proto)
{
    if (unlikely(l3proto >= AF_MAX))
        return &nf_conntrack_l3proto_generic;
    return rcu_dereference(nf_ct_l3protos[l3proto]);
}

#endif /*_NF_CONNTRACK_L3PROTO_H*/