arp_tables.h

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/*
 *  Format of an ARP firewall descriptor
 *
 *  src, tgt, src_mask, tgt_mask, arpop, arpop_mask are always stored in
 *  network byte order.
 *  flags are stored in host byte order (of course).
 */
#ifndef _ARPTABLES_H
#define _ARPTABLES_H

#include <linux/if.h>
#include <linux/in.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <uapi/linux/netfilter_arp/arp_tables.h>

/* Standard entry. */
struct arpt_standard {
    struct arpt_entry entry;
    struct xt_standard_target target;
};

struct arpt_error {
    struct arpt_entry entry;
    struct xt_error_target target;
};

#define ARPT_ENTRY_INIT(__size)                            \
{                                          \
    .target_offset  = sizeof(struct arpt_entry),                   \
    .next_offset    = (__size),                        \
}

#define ARPT_STANDARD_INIT(__verdict)                          \
{                                          \
    .entry      = ARPT_ENTRY_INIT(sizeof(struct arpt_standard)),       \
    .target     = XT_TARGET_INIT(XT_STANDARD_TARGET,               \
                     sizeof(struct xt_standard_target)), \
    .target.verdict = -(__verdict) - 1,                    \
}

#define ARPT_ERROR_INIT                                \
{                                          \
    .entry      = ARPT_ENTRY_INIT(sizeof(struct arpt_error)),          \
    .target     = XT_TARGET_INIT(XT_ERROR_TARGET,              \
                     sizeof(struct xt_error_target)),      \
    .target.errorname = "ERROR",                           \
}

extern void *arpt_alloc_initial_table(const struct xt_table *);
extern struct xt_table *arpt_register_table(struct net *net,
                        const struct xt_table *table,
                        const struct arpt_replace *repl);
extern void arpt_unregister_table(struct xt_table *table);
extern unsigned int arpt_do_table(struct sk_buff *skb,
                  unsigned int hook,
                  const struct net_device *in,
                  const struct net_device *out,
                  struct xt_table *table);

#ifdef CONFIG_COMPAT
#include <net/compat.h>

struct compat_arpt_entry {
    struct arpt_arp arp;
    __u16 target_offset;
    __u16 next_offset;
    compat_uint_t comefrom;
    struct compat_xt_counters counters;
    unsigned char elems[0];
};

static inline struct xt_entry_target *
compat_arpt_get_target(struct compat_arpt_entry *e)
{
    return (void *)e + e->target_offset;
}

#endif /* CONFIG_COMPAT */
#endif /* _ARPTABLES_H */