sysroot/usr/include/linux/netfilter/x_tables.h

#ifndef _X_TABLES_H
#define _X_TABLES_H

#define XT_FUNCTION_MAXNAMELEN 30
#define XT_TABLE_MAXNAMELEN 32

struct xt_entry_match
{
	union {
		struct {
			u_int16_t match_size;

			/* Used by userspace */
			char name[XT_FUNCTION_MAXNAMELEN-1];

			u_int8_t revision;
		} user;
		struct {
			u_int16_t match_size;

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

		/* Total length */
		u_int16_t match_size;
	} u;

	unsigned char data[0];
};

struct xt_entry_target
{
	union {
		struct {
			u_int16_t target_size;

			/* Used by userspace */
			char name[XT_FUNCTION_MAXNAMELEN-1];

			u_int8_t revision;
		} user;
		struct {
			u_int16_t target_size;

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

		/* Total length */
		u_int16_t 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;
};

/* The argument to IPT_SO_GET_REVISION_*.  Returns highest revision
 * kernel supports, if >= revision. */
struct xt_get_revision
{
	char name[XT_FUNCTION_MAXNAMELEN-1];

	u_int8_t 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
{
	u_int8_t u8;
	u_int16_t u16;
	u_int32_t u32;
	u_int64_t u64;
};

#define XT_ALIGN(s) (((s) + (__alignof__(struct _xt_align)-1)) 	\
			& ~(__alignof__(struct _xt_align)-1))

/* 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
{
	u_int64_t 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. */


#endif /* _X_TABLES_H */