4.2BSD/usr/src/sys/net/route.h

/*	route.h	6.1	83/07/29	*/

/*
 * Kernel resident routing tables.
 * 
 * The routing tables are initialized at boot time by
 * making entries for all directly connected interfaces.
 */

/*
 * A route consists of a destination address and a reference
 * to a routing entry.  These are often held by protocols
 * in their control blocks, e.g. inpcb.
 */
struct route {
	struct	rtentry *ro_rt;
	struct	sockaddr ro_dst;
#ifdef notdef
	caddr_t	ro_pcb;			/* not used yet */
#endif
};

/*
 * We distinguish between routes to hosts and routes to networks,
 * preferring the former if available.  For each route we infer
 * the interface to use from the gateway address supplied when
 * the route was entered.  Routes that forward packets through
 * gateways are marked so that the output routines know to address the
 * gateway rather than the ultimate destination.
 */
struct rtentry {
	u_long	rt_hash;		/* to speed lookups */
	struct	sockaddr rt_dst;	/* key */
	struct	sockaddr rt_gateway;	/* value */
	short	rt_flags;		/* up/down?, host/net */
	short	rt_refcnt;		/* # held references */
	u_long	rt_use;			/* raw # packets forwarded */
	struct	ifnet *rt_ifp;		/* the answer: interface to use */
};

#define	RTF_UP		0x1		/* route useable */
#define	RTF_GATEWAY	0x2		/* destination is a gateway */
#define	RTF_HOST	0x4		/* host entry (net otherwise) */

/*
 * Routing statistics.
 */
struct	rtstat {
	short	rts_badredirect;	/* bogus redirect calls */
	short	rts_dynamic;		/* routes created by redirects */
	short	rts_newgateway;		/* routes modified by redirects */
	short	rts_unreach;		/* lookups which failed */
	short	rts_wildcard;		/* lookups satisfied by a wildcard */
};

#ifdef KERNEL
#define	RTFREE(rt) \
	if ((rt)->rt_refcnt == 1) \
		rtfree(rt); \
	else \
		(rt)->rt_refcnt--;

#define	RTHASHSIZ	7
struct	mbuf *rthost[RTHASHSIZ];
struct	mbuf *rtnet[RTHASHSIZ];
struct	rtstat	rtstat;
#endif