usr/src/sys/net/route.h

/*      route.h 4.7     82/03/31        */

/*
 * Kernel resident routing tables.
 *
 * Each interface makes an entry at boot time so that
 * correspondents directly addressible can be found.
 * User programs can update this data base from information
 * stored in the file system or information gleaned from
 * routing protocol interactions with gateways.
 *
 * TODO:
 *      keep statistics
 *      smooth usage figures
 */
struct rtentry {
        u_long  rt_hash;                /* for net or for host */
        struct  sockaddr rt_dst;        /* match value */
        struct  sockaddr rt_gateway;    /* who to forward to */
        short   rt_flags;               /* see below */
        short   rt_refcnt;              /* # held references */
        u_long  rt_use;                 /* raw # packets forwarded */
        struct  ifnet *rt_ifp;          /* interface to use */
};

struct route {
        struct  rtentry *ro_rt;
        struct  sockaddr ro_dst;
        caddr_t ro_pcb;                 /* back pointer? */
};

/*
 * Flags and host/network status.
 */
#define RTF_UP          0x1             /* route useable */
#define RTF_DIRECT      0x2             /* destination is a neighbor */
#define RTF_HOST        0x4             /* host entry (net otherwise) */

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

#ifdef KERNEL
/*
 * Lookup are hashed by a key.  Each hash bucket
 * consists of a linked list of mbuf's
 * containing routing entries.  Dead entries are
 * reclaimed along with mbufs.
 */
#define RTHASHSIZ       7
struct  mbuf *rthost[RTHASHSIZ];
struct  mbuf *rtnet[RTHASHSIZ];
#endif