/*
 *  ebtables
 *
 *	Authors:
 *	Bart De Schuymer		<bart.de.schuymer@pandora.be>
 *
 *  ebtables.c,v 2.0, September, 2002
 *
 *  This code is stongly inspired on the iptables code which is
 *  Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
 */

#ifndef __LINUX_BRIDGE_EFF_H
#define __LINUX_BRIDGE_EFF_H
#include <linux/if.h>
#include <linux/netfilter_bridge.h>
#include <linux/if_ether.h>

#define EBT_TABLE_MAXNAMELEN 32
#define EBT_CHAIN_MAXNAMELEN EBT_TABLE_MAXNAMELEN
#define EBT_FUNCTION_MAXNAMELEN EBT_TABLE_MAXNAMELEN

// verdicts >0 are "branches"
#define EBT_ACCEPT   -1
#define EBT_DROP     -2
#define EBT_CONTINUE -3
#define EBT_RETURN   -4
#define NUM_STANDARD_TARGETS   4

struct ebt_counter
{
	uint64_t pcnt;
	uint64_t bcnt;
};

struct ebt_entries {
	// this field is always set to zero
	// See EBT_ENTRY_OR_ENTRIES.
	// Must be same size as ebt_entry.bitmask
	unsigned int distinguisher;
	// the chain name
	char name[EBT_CHAIN_MAXNAMELEN];
	// counter offset for this chain
	unsigned int counter_offset;
	// one standard (accept, drop, return) per hook
	int policy;
	// nr. of entries
	unsigned int nentries;
	// entry list
	char data[0];
};

// used for the bitmask of struct ebt_entry

// This is a hack to make a difference between an ebt_entry struct and an
// ebt_entries struct when traversing the entries from start to end.
// Using this simplifies the code alot, while still being able to use
// ebt_entries.
// Contrary, iptables doesn't use something like ebt_entries and therefore uses
// different techniques for naming the policy and such. So, iptables doesn't
// need a hack like this.
#define EBT_ENTRY_OR_ENTRIES 0x01
// these are the normal masks
#define EBT_NOPROTO 0x02
#define EBT_802_3 0x04
#define EBT_SOURCEMAC 0x08
#define EBT_DESTMAC 0x10
#define EBT_F_MASK (EBT_NOPROTO | EBT_802_3 | EBT_SOURCEMAC | EBT_DESTMAC \
   | EBT_ENTRY_OR_ENTRIES)

#define EBT_IPROTO 0x01
#define EBT_IIN 0x02
#define EBT_IOUT 0x04
#define EBT_ISOURCE 0x8
#define EBT_IDEST 0x10
#define EBT_ILOGICALIN 0x20
#define EBT_ILOGICALOUT 0x40
#define EBT_INV_MASK (EBT_IPROTO | EBT_IIN | EBT_IOUT | EBT_ILOGICALIN \
   | EBT_ILOGICALOUT | EBT_ISOURCE | EBT_IDEST)

struct ebt_entry_match
{
	union {
		char name[EBT_FUNCTION_MAXNAMELEN];
		struct ebt_match *match;
	} u;
	// size of data
	unsigned int match_size;
	unsigned char data[0];
};

struct ebt_entry_watcher
{
	union {
		char name[EBT_FUNCTION_MAXNAMELEN];
		struct ebt_watcher *watcher;
	} u;
	// size of data
	unsigned int watcher_size;
	unsigned char data[0];
};

struct ebt_entry_target
{
	union {
		char name[EBT_FUNCTION_MAXNAMELEN];
		struct ebt_target *target;
	} u;
	// size of data
	unsigned int target_size;
	unsigned char data[0];
};

#define EBT_STANDARD_TARGET "standard"
struct ebt_standard_target
{
	struct ebt_entry_target target;
	int verdict;
};

// one entry
struct ebt_entry {
	// this needs to be the first field
	unsigned int bitmask;
	unsigned int invflags;
	uint16_t ethproto;
	// the physical in-dev
	char in[IFNAMSIZ];
	// the logical in-dev
	char logical_in[IFNAMSIZ];
	// the physical out-dev
	char out[IFNAMSIZ];
	// the logical out-dev
	char logical_out[IFNAMSIZ];
	unsigned char sourcemac[ETH_ALEN];
	unsigned char sourcemsk[ETH_ALEN];
	unsigned char destmac[ETH_ALEN];
	unsigned char destmsk[ETH_ALEN];
	// sizeof ebt_entry + matches
	unsigned int watchers_offset;
	// sizeof ebt_entry + matches + watchers
	unsigned int target_offset;
	// sizeof ebt_entry + matches + watchers + target
	unsigned int next_offset;
	unsigned char elems[0];
};

struct ebt_replace
{
	char name[EBT_TABLE_MAXNAMELEN];
	unsigned int valid_hooks;
	// nr of rules in the table
	unsigned int nentries;
	// total size of the entries
	unsigned int entries_size;
	// start of the chains
	struct ebt_entries *hook_entry[NF_BR_NUMHOOKS];
	// nr of counters userspace expects back
	unsigned int num_counters;
	// where the kernel will put the old counters
	struct ebt_counter *counters;
	char *entries;
};

// [gs]etsockopt numbers
#define EBT_BASE_CTL            128

#define EBT_SO_SET_ENTRIES      (EBT_BASE_CTL)
#define EBT_SO_SET_COUNTERS     (EBT_SO_SET_ENTRIES+1)
#define EBT_SO_SET_MAX          (EBT_SO_SET_COUNTERS+1)

#define EBT_SO_GET_INFO         (EBT_BASE_CTL)
#define EBT_SO_GET_ENTRIES      (EBT_SO_GET_INFO+1)
#define EBT_SO_GET_INIT_INFO    (EBT_SO_GET_ENTRIES+1)
#define EBT_SO_GET_INIT_ENTRIES (EBT_SO_GET_INIT_INFO+1)
#define EBT_SO_GET_MAX          (EBT_SO_GET_INIT_ENTRIES+1)

#ifdef __KERNEL__

// return values for match() functions
#define EBT_MATCH 0
#define EBT_NOMATCH 1

struct ebt_match
{
	struct list_head list;
	const char name[EBT_FUNCTION_MAXNAMELEN];
	// 0 == it matches
	int (*match)(const struct sk_buff *skb, const struct net_device *in,
	   const struct net_device *out, const void *matchdata,
	   unsigned int datalen);
	// 0 == let it in
	int (*check)(const char *tablename, unsigned int hookmask,
	   const struct ebt_entry *e, void *matchdata, unsigned int datalen);
	void (*destroy)(void *matchdata, unsigned int datalen);
	struct module *me;
};

struct ebt_watcher
{
	struct list_head list;
	const char name[EBT_FUNCTION_MAXNAMELEN];
	void (*watcher)(const struct sk_buff *skb, const struct net_device *in,
	   const struct net_device *out, const void *watcherdata,
	   unsigned int datalen);
	// 0 == let it in
	int (*check)(const char *tablename, unsigned int hookmask,
	   const struct ebt_entry *e, void *watcherdata, unsigned int datalen);
	void (*destroy)(void *watcherdata, unsigned int datalen);
	struct module *me;
};

struct ebt_target
{
	struct list_head list;
	const char name[EBT_FUNCTION_MAXNAMELEN];
	// returns one of the standard verdicts
	int (*target)(struct sk_buff **pskb, unsigned int hooknr,
	   const struct net_device *in, const struct net_device *out,
	   const void *targetdata, unsigned int datalen);
	// 0 == let it in
	int (*check)(const char *tablename, unsigned int hookmask,
	   const struct ebt_entry *e, void *targetdata, unsigned int datalen);
	void (*destroy)(void *targetdata, unsigned int datalen);
	struct module *me;
};

// used for jumping from and into user defined chains (udc)
struct ebt_chainstack
{
	struct ebt_entries *chaininfo; // pointer to chain data
	struct ebt_entry *e; // pointer to entry data
	unsigned int n; // n'th entry
};

struct ebt_table_info
{
	// total size of the entries
	unsigned int entries_size;
	unsigned int nentries;
	// pointers to the start of the chains
	struct ebt_entries *hook_entry[NF_BR_NUMHOOKS];
	// room to maintain the stack used for jumping from and into udc
	struct ebt_chainstack **chainstack;
	char *entries;
	struct ebt_counter counters[0] ____cacheline_aligned;
};

struct ebt_table
{
	struct list_head list;
	char name[EBT_TABLE_MAXNAMELEN];
	struct ebt_replace *table;
	unsigned int valid_hooks;
	rwlock_t lock;
	// e.g. could be the table explicitly only allows certain
	// matches, targets, ... 0 == let it in
	int (*check)(const struct ebt_table_info *info,
	   unsigned int valid_hooks);
	// the data used by the kernel
	struct ebt_table_info *private;
};

#define EBT_ALIGN(s) (((s) + (__alignof__(struct ebt_entry_target)-1)) & \
		     ~(__alignof__(struct ebt_entry_target)-1))
extern int ebt_register_table(struct ebt_table *table);
extern void ebt_unregister_table(struct ebt_table *table);
extern int ebt_register_match(struct ebt_match *match);
extern void ebt_unregister_match(struct ebt_match *match);
extern int ebt_register_watcher(struct ebt_watcher *watcher);
extern void ebt_unregister_watcher(struct ebt_watcher *watcher);
extern int ebt_register_target(struct ebt_target *target);
extern void ebt_unregister_target(struct ebt_target *target);
extern unsigned int ebt_do_table(unsigned int hook, struct sk_buff **pskb,
   const struct net_device *in, const struct net_device *out,
   struct ebt_table *table);

   // Used in the kernel match() functions
#define FWINV(bool,invflg) ((bool) ^ !!(info->invflags & invflg))
// True if the hook mask denotes that the rule is in a base chain,
// used in the check() functions
#define BASE_CHAIN (hookmask & (1 << NF_BR_NUMHOOKS))
// Clear the bit in the hook mask that tells if the rule is on a base chain
#define CLEAR_BASE_CHAIN_BIT (hookmask &= ~(1 << NF_BR_NUMHOOKS))
// True if the target is not a standard target
#define INVALID_TARGET (info->target < -NUM_STANDARD_TARGETS || info->target >= 0)

#endif /* __KERNEL__ */

// blatently stolen from ip_tables.h
// fn returns 0 to continue iteration
#define EBT_MATCH_ITERATE(e, fn, args...)                   \
({                                                          \
	unsigned int __i;                                   \
	int __ret = 0;                                      \
	struct ebt_entry_match *__match;                    \
	                                                    \
	for (__i = sizeof(struct ebt_entry);                \
	     __i < (e)->watchers_offset;                    \
	     __i += __match->match_size +                   \
	     sizeof(struct ebt_entry_match)) {              \
		__match = (void *)(e) + __i;                \
		                                            \
		__ret = fn(__match , ## args);              \
		if (__ret != 0)                             \
			break;                              \
	}                                                   \
	if (__ret == 0) {                                   \
		if (__i != (e)->watchers_offset)            \
			__ret = -EINVAL;                    \
	}                                                   \
	__ret;                                              \
})

#define EBT_WATCHER_ITERATE(e, fn, args...)                 \
({                                                          \
	unsigned int __i;                                   \
	int __ret = 0;                                      \
	struct ebt_entry_watcher *__watcher;                \
	                                                    \
	for (__i = e->watchers_offset;                      \
	     __i < (e)->target_offset;                      \
	     __i += __watcher->watcher_size +               \
	     sizeof(struct ebt_entry_watcher)) {            \
		__watcher = (void *)(e) + __i;              \
		                                            \
		__ret = fn(__watcher , ## args);            \
		if (__ret != 0)                             \
			break;                              \
	}                                                   \
	if (__ret == 0) {                                   \
		if (__i != (e)->target_offset)              \
			__ret = -EINVAL;                    \
	}                                                   \
	__ret;                                              \
})

#define EBT_ENTRY_ITERATE(entries, size, fn, args...)       \
({                                                          \
	unsigned int __i;                                   \
	int __ret = 0;                                      \
	struct ebt_entry *__entry;                          \
	                                                    \
	for (__i = 0; __i < (size);) {                      \
		__entry = (void *)(entries) + __i;          \
		__ret = fn(__entry , ## args);              \
		if (__ret != 0)                             \
			break;                              \
		if (__entry->bitmask != 0)                  \
			__i += __entry->next_offset;        \
		else                                        \
			__i += sizeof(struct ebt_entries);  \
	}                                                   \
	if (__ret == 0) {                                   \
		if (__i != (size))                          \
			__ret = -EINVAL;                    \
	}                                                   \
	__ret;                                              \
})

#endif
