/* $OpenBSD: art.h,v 1.25 2023/11/11 12:17:50 bluhm Exp $ */

/*
 * Copyright (c) 2015 Martin Pieuchot
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef _NET_ART_H_
#define _NET_ART_H_

#include <sys/rwlock.h>
#include <sys/srp.h>

#define ART_MAXLVL	32	/* We currently use 32 levels for IPv6. */

/*
 * Root of the ART tables, equivalent to the radix head.
 *
 *  Locks used to protect struct members in this file:
 *	I	immutable after creation
 *	l	root's `ar_lock'
 *	K	kernel lock
 *  For SRP related structures that allow lock-free reads, the write lock
 *  is indicated below.
 */
struct art_root {
	struct srp		 ar_root;	/* [l] First table */
	struct rwlock		 ar_lock;	/* [] Serialise modifications */
	uint8_t			 ar_bits[ART_MAXLVL]; /* [I] Per level stride */
	uint8_t			 ar_nlvl;	/* [I] Number of levels */
	uint8_t			 ar_alen;	/* [I] Address length in bits */
	uint8_t			 ar_off;	/* [I] Offset of key in bytes */
	struct sockaddr		*ar_source;	/* [N] use optional src addr */
};

#define ISLEAF(e)	(((unsigned long)(e) & 1) == 0)
#define SUBTABLE(e)	((struct art_table *)((unsigned long)(e) & ~1))
#define ASNODE(t)	((struct art_node *)((unsigned long)(t) | 1))

/*
 * Allotment Table.
 */
struct art_table {
	struct art_table	*at_parent;	/* Parent table */
	uint32_t		 at_index;	/* Index in the parent table */
	uint32_t		 at_minfringe;	/* Index that fringe begins */
	uint32_t		 at_level;	/* Level of the table */
	uint8_t			 at_bits;	/* Stride length of the table */
	uint8_t			 at_offset;	/* Sum of parents' stride len */

	/*
	 * Items stored in the heap are pointers to nodes, in the leaf
	 * case, or tables otherwise.  One exception is index 0 which
	 * is a route counter.
	 */
	union {
		struct srp		 node;
		unsigned long		 count;
	} *at_heap;				/* Array of 2^(slen+1) items */
};
#define	at_refcnt	at_heap[0].count/* Refcounter (1 per different route) */
#define	at_default	at_heap[1].node	/* Default route (was in parent heap) */

/* Heap size for an ART table of stride length ``slen''. */
#define AT_HEAPSIZE(slen)	((1 << ((slen) + 1)) * sizeof(void *))

/*
 * Forward declaration needed for the list of mpath routes
 * attached to a single ART node.
 */
struct rtentry;

/*
 * A node is the internal representation of a route entry.
 */
struct art_node {
	union {
	    SRPL_HEAD(, rtentry) an__rtlist;	/* Route related to this node */
	    struct art_node	*an__gc;	/* Entry on GC list */
	}			 an_pointer;
	uint8_t			 an_plen;	/* Prefix length */
};
#define an_rtlist	an_pointer.an__rtlist
#define an_gc		an_pointer.an__gc

void		 art_init(void);
struct art_root *art_alloc(unsigned int, unsigned int, unsigned int);
struct art_node *art_insert(struct art_root *, struct art_node *, const void *,
		     int);
struct art_node *art_delete(struct art_root *, struct art_node *, const void *,
		     int);
struct art_node *art_match(struct art_root *, const void *, struct srp_ref *);
struct art_node *art_lookup(struct art_root *, const void *, int,
		     struct srp_ref *);
int		 art_walk(struct art_root *,
		     int (*)(struct art_node *, void *), void *);

struct art_node *art_get(uint8_t);
void		 art_put(struct art_node *);

#endif /* _NET_ART_H_ */