x_tables.h

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#ifndef _UAPI_X_TABLES_H
#define _UAPI_X_TABLES_H
#include <linux/kernel.h>
#include <linux/types.h>

#define XT_FUNCTION_MAXNAMELEN 30
#define XT_EXTENSION_MAXNAMELEN 29
#define XT_TABLE_MAXNAMELEN 32

struct xt_entry_match {
    union {
        struct {
            __u16 match_size;

            /* Used by userspace */
            char name[XT_EXTENSION_MAXNAMELEN];
            __u8 revision;
        } user;
        struct {
            __u16 match_size;

            /* Used inside the kernel */
            struct xt_match *match;
        } kernel;

        /* Total length */
        __u16 match_size;
    } u;

    unsigned char data[0];
};

struct xt_entry_target {
    union {
        struct {
            __u16 target_size;

            /* Used by userspace */
            char name[XT_EXTENSION_MAXNAMELEN];
            __u8 revision;
        } user;
        struct {
            __u16 target_size;

            /* Used inside the kernel */
            struct xt_target *target;
        } kernel;

        /* Total length */
        __u16 target_size;
    } u;

    unsigned char data[0];
};

#define XT_TARGET_INIT(__name, __size)                         \
{                                          \
    .target.u.user = {                             \
        .target_size    = XT_ALIGN(__size),                \
        .name       = __name,                      \
    },                                     \
}

struct xt_standard_target {
    struct xt_entry_target target;
    int verdict;
};

struct xt_error_target {
    struct xt_entry_target target;
    char errorname[XT_FUNCTION_MAXNAMELEN];
};

/* The argument to IPT_SO_GET_REVISION_*.  Returns highest revision
 * kernel supports, if >= revision. */
struct xt_get_revision {
    char name[XT_EXTENSION_MAXNAMELEN];
    __u8 revision;
};

/* CONTINUE verdict for targets */
#define XT_CONTINUE 0xFFFFFFFF

/* For standard target */
#define XT_RETURN (-NF_REPEAT - 1)

/* this is a dummy structure to find out the alignment requirement for a struct
 * containing all the fundamental data types that are used in ipt_entry,
 * ip6t_entry and arpt_entry.  This sucks, and it is a hack.  It will be my
 * personal pleasure to remove it -HW
 */
struct _xt_align {
    __u8 u8;
    __u16 u16;
    __u32 u32;
    __u64 u64;
};

#define XT_ALIGN(s) __ALIGN_KERNEL((s), __alignof__(struct _xt_align))

/* Standard return verdict, or do jump. */
#define XT_STANDARD_TARGET ""
/* Error verdict. */
#define XT_ERROR_TARGET "ERROR"

#define SET_COUNTER(c,b,p) do { (c).bcnt = (b); (c).pcnt = (p); } while(0)
#define ADD_COUNTER(c,b,p) do { (c).bcnt += (b); (c).pcnt += (p); } while(0)

struct xt_counters {
    __u64 pcnt, bcnt;           /* Packet and byte counters */
};

/* The argument to IPT_SO_ADD_COUNTERS. */
struct xt_counters_info {
    /* Which table. */
    char name[XT_TABLE_MAXNAMELEN];

    unsigned int num_counters;

    /* The counters (actually `number' of these). */
    struct xt_counters counters[0];
};

#define XT_INV_PROTO        0x40    /* Invert the sense of PROTO. */

#ifndef __KERNEL__
/* fn returns 0 to continue iteration */
#define XT_MATCH_ITERATE(type, e, fn, args...)          \
({                              \
    unsigned int __i;                   \
    int __ret = 0;                      \
    struct xt_entry_match *__m;             \
                                \
    for (__i = sizeof(type);                \
         __i < (e)->target_offset;              \
         __i += __m->u.match_size) {            \
        __m = (void *)e + __i;              \
                                \
        __ret = fn(__m , ## args);          \
        if (__ret != 0)                 \
            break;                  \
    }                           \
    __ret;                          \
})

/* fn returns 0 to continue iteration */
#define XT_ENTRY_ITERATE_CONTINUE(type, entries, size, n, fn, args...) \
({                              \
    unsigned int __i, __n;                  \
    int __ret = 0;                      \
    type *__entry;                      \
                                \
    for (__i = 0, __n = 0; __i < (size);            \
         __i += __entry->next_offset, __n++) {      \
        __entry = (void *)(entries) + __i;      \
        if (__n < n)                    \
            continue;               \
                                \
        __ret = fn(__entry , ## args);          \
        if (__ret != 0)                 \
            break;                  \
    }                           \
    __ret;                          \
})

/* fn returns 0 to continue iteration */
#define XT_ENTRY_ITERATE(type, entries, size, fn, args...) \
    XT_ENTRY_ITERATE_CONTINUE(type, entries, size, 0, fn, args)

#endif /* !__KERNEL__ */

/* pos is normally a struct ipt_entry/ip6t_entry/etc. */
#define xt_entry_foreach(pos, ehead, esize) \
    for ((pos) = (typeof(pos))(ehead); \
         (pos) < (typeof(pos))((char *)(ehead) + (esize)); \
         (pos) = (typeof(pos))((char *)(pos) + (pos)->next_offset))

/* can only be xt_entry_match, so no use of typeof here */
#define xt_ematch_foreach(pos, entry) \
    for ((pos) = (struct xt_entry_match *)entry->elems; \
         (pos) < (struct xt_entry_match *)((char *)(entry) + \
                 (entry)->target_offset); \
         (pos) = (struct xt_entry_match *)((char *)(pos) + \
                 (pos)->u.match_size))


#endif /* _UAPI_X_TABLES_H */