include/linux/netfilter/nfnetlink.h

#ifndef _NFNETLINK_H
#define _NFNETLINK_H
#include <linux/types.h>

#ifndef __KERNEL__
/* nfnetlink groups: Up to 32 maximum - backwards compatibility for userspace */
#define NF_NETLINK_CONNTRACK_NEW 		0x00000001
#define NF_NETLINK_CONNTRACK_UPDATE		0x00000002
#define NF_NETLINK_CONNTRACK_DESTROY		0x00000004
#define NF_NETLINK_CONNTRACK_EXP_NEW		0x00000008
#define NF_NETLINK_CONNTRACK_EXP_UPDATE		0x00000010
#define NF_NETLINK_CONNTRACK_EXP_DESTROY	0x00000020
#endif

enum nfnetlink_groups {
	NFNLGRP_NONE,
#define NFNLGRP_NONE			NFNLGRP_NONE
	NFNLGRP_CONNTRACK_NEW,
#define NFNLGRP_CONNTRACK_NEW		NFNLGRP_CONNTRACK_NEW
	NFNLGRP_CONNTRACK_UPDATE,
#define NFNLGRP_CONNTRACK_UPDATE	NFNLGRP_CONNTRACK_UPDATE
	NFNLGRP_CONNTRACK_DESTROY,
#define NFNLGRP_CONNTRACK_DESTROY	NFNLGRP_CONNTRACK_DESTROY
	NFNLGRP_CONNTRACK_EXP_NEW,
#define	NFNLGRP_CONNTRACK_EXP_NEW	NFNLGRP_CONNTRACK_EXP_NEW
	NFNLGRP_CONNTRACK_EXP_UPDATE,
#define NFNLGRP_CONNTRACK_EXP_UPDATE	NFNLGRP_CONNTRACK_EXP_UPDATE
	NFNLGRP_CONNTRACK_EXP_DESTROY,
#define NFNLGRP_CONNTRACK_EXP_DESTROY	NFNLGRP_CONNTRACK_EXP_DESTROY
	__NFNLGRP_MAX,
};
#define NFNLGRP_MAX	(__NFNLGRP_MAX - 1)

/* Generic structure for encapsulation optional netfilter information.
 * It is reminiscent of sockaddr, but with sa_family replaced
 * with attribute type. 
 * ! This should someday be put somewhere generic as now rtnetlink and
 * ! nfnetlink use the same attributes methods. - J. Schulist.
 */

struct nfattr
{
	u_int16_t nfa_len;
	u_int16_t nfa_type;	/* we use 15 bits for the type, and the highest
				 * bit to indicate whether the payload is nested */
} __attribute__ ((packed));

/* FIXME: Apart from NFNL_NFA_NESTED shamelessly copy and pasted from
 * rtnetlink.h, it's time to put this in a generic file */

#define NFNL_NFA_NEST	0x8000
#define NFA_TYPE(attr) 	((attr)->nfa_type & 0x7fff)

#define NFA_ALIGNTO     4
#define NFA_ALIGN(len)	(((len) + NFA_ALIGNTO - 1) & ~(NFA_ALIGNTO - 1))
#define NFA_OK(nfa,len)	((len) > 0 && (nfa)->nfa_len >= sizeof(struct nfattr) \
	&& (nfa)->nfa_len <= (len))
#define NFA_NEXT(nfa,attrlen)	((attrlen) -= NFA_ALIGN((nfa)->nfa_len), \
	(struct nfattr *)(((char *)(nfa)) + NFA_ALIGN((nfa)->nfa_len)))
#define NFA_LENGTH(len)	(NFA_ALIGN(sizeof(struct nfattr)) + (len))
#define NFA_SPACE(len)	NFA_ALIGN(NFA_LENGTH(len))
#define NFA_DATA(nfa)   ((void *)(((char *)(nfa)) + NFA_LENGTH(0)))
#define NFA_PAYLOAD(nfa) ((int)((nfa)->nfa_len) - NFA_LENGTH(0))
#define NFA_NEST(skb, type) \
({	struct nfattr *__start = (struct nfattr *) (skb)->tail; \
	NFA_PUT(skb, (NFNL_NFA_NEST | type), 0, NULL); \
	__start;  })
#define NFA_NEST_END(skb, start) \
({      (start)->nfa_len = ((skb)->tail - (unsigned char *) (start)); \
        (skb)->len; })
#define NFA_NEST_CANCEL(skb, start) \
({      if (start) \
                skb_trim(skb, (unsigned char *) (start) - (skb)->data); \
        -1; })

/* General form of address family dependent message.
 */
struct nfgenmsg {
	u_int8_t  nfgen_family;		/* AF_xxx */
	u_int8_t  version;		/* nfnetlink version */
	u_int16_t res_id;		/* resource id */
} __attribute__ ((packed));

#define NFNETLINK_V0	0

#define NFM_NFA(n)      ((struct nfattr *)(((char *)(n)) \
        + NLMSG_ALIGN(sizeof(struct nfgenmsg))))
#define NFM_PAYLOAD(n)  NLMSG_PAYLOAD(n, sizeof(struct nfgenmsg))

/* netfilter netlink message types are split in two pieces:
 * 8 bit subsystem, 8bit operation.
 */

#define NFNL_SUBSYS_ID(x)	((x & 0xff00) >> 8)
#define NFNL_MSG_TYPE(x)	(x & 0x00ff)

/* No enum here, otherwise __stringify() trick of MODULE_ALIAS_NFNL_SUBSYS()
 * won't work anymore */
#define NFNL_SUBSYS_NONE 		0
#define NFNL_SUBSYS_CTNETLINK		1
#define NFNL_SUBSYS_CTNETLINK_EXP	2
#define NFNL_SUBSYS_QUEUE		3
#define NFNL_SUBSYS_ULOG		4
#define NFNL_SUBSYS_COUNT		5

#ifdef __KERNEL__

#include <linux/netlink.h>
#include <linux/capability.h>

struct nfnl_callback
{
	int (*call)(struct sock *nl, struct sk_buff *skb, 
		struct nlmsghdr *nlh, struct nfattr *cda[], int *errp);
	u_int16_t attr_count;	/* number of nfattr's */
};

struct nfnetlink_subsystem
{
	const char *name;
	__u8 subsys_id;		/* nfnetlink subsystem ID */
	__u8 cb_count;		/* number of callbacks */
	struct nfnl_callback *cb; /* callback for individual types */
};

extern void __nfa_fill(struct sk_buff *skb, int attrtype,
        int attrlen, const void *data);
#define NFA_PUT(skb, attrtype, attrlen, data) \
({ if (skb_tailroom(skb) < (int)NFA_SPACE(attrlen)) goto nfattr_failure; \
   __nfa_fill(skb, attrtype, attrlen, data); })

extern struct semaphore nfnl_sem;

#define nfnl_shlock()		down(&nfnl_sem)
#define nfnl_shlock_nowait()	down_trylock(&nfnl_sem)

#define nfnl_shunlock()		do { up(&nfnl_sem); \
				     if(nfnl && nfnl->sk_receive_queue.qlen) \
					    nfnl->sk_data_ready(nfnl, 0); \
                        	} while(0)

extern void nfnl_lock(void);
extern void nfnl_unlock(void);

extern int nfnetlink_subsys_register(struct nfnetlink_subsystem *n);
extern int nfnetlink_subsys_unregister(struct nfnetlink_subsystem *n);

extern void nfattr_parse(struct nfattr *tb[], int maxattr, 
			struct nfattr *nfa, int len);

#define nfattr_parse_nested(tb, max, nfa) \
	nfattr_parse((tb), (max), NFA_DATA((nfa)), NFA_PAYLOAD((nfa)))

#define nfattr_bad_size(tb, max, cta_min)				\
({	int __i, __res = 0;						\
 	for (__i=0; __i<max; __i++) {					\
 		if (!cta_min[__i])					\
 			continue;					\
 		if (tb[__i] && NFA_PAYLOAD(tb[__i]) < cta_min[__i]){	\
 			__res = 1;					\
 			break;						\
 		}							\
 	}								\
 	__res;								\
})

extern int nfnetlink_has_listeners(unsigned int group);
extern int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, 
			  int echo);
extern int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags);

#define MODULE_ALIAS_NFNL_SUBSYS(subsys) \
	MODULE_ALIAS("nfnetlink-subsys-" __stringify(subsys))

#endif	/* __KERNEL__ */
#endif	/* _NFNETLINK_H */