nf_conntrack_helper.h

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/*
 * connection tracking helpers.
 *
 * 16 Dec 2003: Yasuyuki Kozakai @USAGI <[email protected]>
 *  - generalize L3 protocol dependent part.
 *
 * Derived from include/linux/netfiter_ipv4/ip_conntrack_helper.h
 */

#ifndef _NF_CONNTRACK_HELPER_H
#define _NF_CONNTRACK_HELPER_H
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_conntrack_expect.h>

struct module;

enum nf_ct_helper_flags {
    NF_CT_HELPER_F_USERSPACE    = (1 << 0),
    NF_CT_HELPER_F_CONFIGURED   = (1 << 1),
};

#define NF_CT_HELPER_NAME_LEN   16

struct nf_conntrack_helper {
    struct hlist_node hnode;    /* Internal use. */

    char name[NF_CT_HELPER_NAME_LEN]; /* name of the module */
    struct module *me;      /* pointer to self */
    const struct nf_conntrack_expect_policy *expect_policy;

    /* length of internal data, ie. sizeof(struct nf_ct_*_master) */
    size_t data_len;

    /* Tuple of things we will help (compared against server response) */
    struct nf_conntrack_tuple tuple;

    /* Function to call when data passes; return verdict, or -1 to
           invalidate. */
    int (*help)(struct sk_buff *skb,
            unsigned int protoff,
            struct nf_conn *ct,
            enum ip_conntrack_info conntrackinfo);

    void (*destroy)(struct nf_conn *ct);

    int (*from_nlattr)(struct nlattr *attr, struct nf_conn *ct);
    int (*to_nlattr)(struct sk_buff *skb, const struct nf_conn *ct);
    unsigned int expect_class_max;

    unsigned int flags;
    unsigned int queue_num;     /* For user-space helpers. */
};

extern struct nf_conntrack_helper *
__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum);

extern struct nf_conntrack_helper *
nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum);

extern int nf_conntrack_helper_register(struct nf_conntrack_helper *);
extern void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);

extern struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, struct nf_conntrack_helper *helper, gfp_t gfp);

extern int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
                     gfp_t flags);

extern void nf_ct_helper_destroy(struct nf_conn *ct);

static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
{
    return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
}

static inline void *nfct_help_data(const struct nf_conn *ct)
{
    struct nf_conn_help *help;

    help = nf_ct_ext_find(ct, NF_CT_EXT_HELPER);

    return (void *)help->data;
}

extern int nf_conntrack_helper_init(struct net *net);
extern void nf_conntrack_helper_fini(struct net *net);

extern int nf_conntrack_broadcast_help(struct sk_buff *skb,
                       unsigned int protoff,
                       struct nf_conn *ct,
                       enum ip_conntrack_info ctinfo,
                       unsigned int timeout);

struct nf_ct_helper_expectfn {
    struct list_head head;
    const char *name;
    void (*expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
};

void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n);
void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n);
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_name(const char *name);
struct nf_ct_helper_expectfn *
nf_ct_helper_expectfn_find_by_symbol(const void *symbol);

extern struct hlist_head *nf_ct_helper_hash;
extern unsigned int nf_ct_helper_hsize;

#endif /*_NF_CONNTRACK_HELPER_H*/