usr/src/sys/net/route.c

/*
 * Copyright (c) 1980, 1986 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *      @(#)route.c     7.5 (Berkeley) %G%
 */

#include "param.h"
#include "systm.h"
#include "mbuf.h"
#include "protosw.h"
#include "socket.h"
#include "dir.h"
#include "user.h"
#include "ioctl.h"
#include "errno.h"

#include "if.h"
#include "af.h"
#include "route.h"

int     rttrash;                /* routes not in table but not freed */
struct  sockaddr wildcard;      /* zero valued cookie for wildcard searches */
int     rthashsize = RTHASHSIZ; /* for netstat, etc. */

/*
 * Packet routing routines.
 */
rtalloc(ro)
        register struct route *ro;
{
        register struct rtentry *rt;
        register struct mbuf *m;
        register u_long hash;
        struct sockaddr *dst = &ro->ro_dst;
        int (*match)(), doinghost, s;
        struct afhash h;
        u_int af = dst->sa_family;
        struct mbuf **table;

        if (ro->ro_rt && ro->ro_rt->rt_ifp && (ro->ro_rt->rt_flags & RTF_UP))
                return;                          /* XXX */
        if (af >= AF_MAX)
                return;
        (*afswitch[af].af_hash)(dst, &h);
        match = afswitch[af].af_netmatch;
        hash = h.afh_hosthash, table = rthost, doinghost = 1;
        s = splnet();
again:
        for (m = table[RTHASHMOD(hash)]; m; m = m->m_next) {
                rt = mtod(m, struct rtentry *);
                if (rt->rt_hash != hash)
                        continue;
                if ((rt->rt_flags & RTF_UP) == 0 ||
                    (rt->rt_ifp->if_flags & IFF_UP) == 0)
                        continue;
                if (doinghost) {
                        if (bcmp((caddr_t)&rt->rt_dst, (caddr_t)dst,
                            sizeof (*dst)))
                                continue;
                } else {
                        if (rt->rt_dst.sa_family != af ||
                            !(*match)(&rt->rt_dst, dst))
                                continue;
                }
                rt->rt_refcnt++;
                splx(s);
                if (dst == &wildcard)
                        rtstat.rts_wildcard++;
                ro->ro_rt = rt;
                return;
        }
        if (doinghost) {
                doinghost = 0;
                hash = h.afh_nethash, table = rtnet;
                goto again;
        }
        /*
         * Check for wildcard gateway, by convention network 0.
         */
        if (dst != &wildcard) {
                dst = &wildcard, hash = 0;
                goto again;
        }
        splx(s);
        rtstat.rts_unreach++;
}

rtfree(rt)
        register struct rtentry *rt;
{

        if (rt == 0)
                panic("rtfree");
        rt->rt_refcnt--;
        if (rt->rt_refcnt == 0 && (rt->rt_flags&RTF_UP) == 0) {
                rttrash--;
                (void) m_free(dtom(rt));
        }
}

/*
 * Force a routing table entry to the specified
 * destination to go through the given gateway.
 * Normally called as a result of a routing redirect
 * message from the network layer.
 *
 * N.B.: must be called at splnet or higher
 *
 */
rtredirect(dst, gateway, flags, src)
        struct sockaddr *dst, *gateway, *src;
        int flags;
{
        struct route ro;
        register struct rtentry *rt;

        /* verify the gateway is directly reachable */
        if (ifa_ifwithnet(gateway) == 0) {
                rtstat.rts_badredirect++;
                return;
        }
        ro.ro_dst = *dst;
        ro.ro_rt = 0;
        rtalloc(&ro);
        rt = ro.ro_rt;
#define equal(a1, a2) \
        (bcmp((caddr_t)(a1), (caddr_t)(a2), sizeof(struct sockaddr)) == 0)
        /*
         * If the redirect isn't from our current router for this dst,
         * it's either old or wrong.  If it redirects us to ourselves,
         * we have a routing loop, perhaps as a result of an interface
         * going down recently.
         */
        if ((rt && !equal(src, &rt->rt_gateway)) || ifa_ifwithaddr(gateway)) {
                rtstat.rts_badredirect++;
                if (rt)
                        rtfree(rt);
                return;
        }
        /*
         * Create a new entry if we just got back a wildcard entry
         * or the the lookup failed.  This is necessary for hosts
         * which use routing redirects generated by smart gateways
         * to dynamically build the routing tables.
         */
        if (rt &&
            (*afswitch[dst->sa_family].af_netmatch)(&wildcard, &rt->rt_dst)) {
                rtfree(rt);
                rt = 0;
        }
        if (rt == 0) {
                rtinit(dst, gateway, (int)SIOCADDRT,
                    (flags & RTF_HOST) | RTF_GATEWAY | RTF_DYNAMIC);
                rtstat.rts_dynamic++;
                return;
        }
        /*
         * Don't listen to the redirect if it's
         * for a route to an interface.
         */
        if (rt->rt_flags & RTF_GATEWAY) {
                if (((rt->rt_flags & RTF_HOST) == 0) && (flags & RTF_HOST)) {
                        /*
                         * Changing from route to net => route to host.
                         * Create new route, rather than smashing route to net.
                         */
                        rtinit(dst, gateway, (int)SIOCADDRT,
                            flags | RTF_DYNAMIC);
                        rtstat.rts_dynamic++;
                } else {
                        /*
                         * Smash the current notion of the gateway to
                         * this destination.
                         */
                        rt->rt_gateway = *gateway;
                        rt->rt_flags |= RTF_MODIFIED;
                        rtstat.rts_newgateway++;
                }
        } else
                rtstat.rts_badredirect++;
        rtfree(rt);
}

/*
 * Routing table ioctl interface.
 */
rtioctl(cmd, data)
        int cmd;
        caddr_t data;
{

        if (cmd != SIOCADDRT && cmd != SIOCDELRT)
                return (EINVAL);
        if (!suser())
                return (u.u_error);
        return (rtrequest(cmd, (struct rtentry *)data));
}

/*
 * Carry out a request to change the routing table.  Called by
 * interfaces at boot time to make their ``local routes'' known,
 * for ioctl's, and as the result of routing redirects.
 */
rtrequest(req, entry)
        int req;
        register struct rtentry *entry;
{
        register struct mbuf *m, **mprev;
        struct mbuf **mfirst;
        register struct rtentry *rt;
        struct afhash h;
        int s, error = 0, (*match)();
        u_int af;
        u_long hash;
        struct ifaddr *ifa;
        struct ifaddr *ifa_ifwithdstaddr();

        af = entry->rt_dst.sa_family;
        if (af >= AF_MAX)
                return (EAFNOSUPPORT);
        (*afswitch[af].af_hash)(&entry->rt_dst, &h);
        if (entry->rt_flags & RTF_HOST) {
                hash = h.afh_hosthash;
                mprev = &rthost[RTHASHMOD(hash)];
        } else {
                hash = h.afh_nethash;
                mprev = &rtnet[RTHASHMOD(hash)];
        }
        match = afswitch[af].af_netmatch;
        s = splimp();
        for (mfirst = mprev; m = *mprev; mprev = &m->m_next) {
                rt = mtod(m, struct rtentry *);
                if (rt->rt_hash != hash)
                        continue;
                if (entry->rt_flags & RTF_HOST) {
                        if (!equal(&rt->rt_dst, &entry->rt_dst))
                                continue;
                } else {
                        if (rt->rt_dst.sa_family != entry->rt_dst.sa_family ||
                            (*match)(&rt->rt_dst, &entry->rt_dst) == 0)
                                continue;
                }
                if (equal(&rt->rt_gateway, &entry->rt_gateway))
                        break;
        }
        switch (req) {

        case SIOCDELRT:
                if (m == 0) {
                        error = ESRCH;
                        goto bad;
                }
                *mprev = m->m_next;
                if (rt->rt_refcnt > 0) {
                        rt->rt_flags &= ~RTF_UP;
                        rttrash++;
                        m->m_next = 0;
                } else
                        (void) m_free(m);
                break;

        case SIOCADDRT:
                if (m) {
                        error = EEXIST;
                        goto bad;
                }
                if ((entry->rt_flags & RTF_GATEWAY) == 0) {
                        /*
                         * If we are adding a route to an interface,
                         * and the interface is a pt to pt link
                         * we should search for the destination
                         * as our clue to the interface.  Otherwise
                         * we can use the local address.
                         */
                        ifa = 0;
                        if (entry->rt_flags & RTF_HOST)
                                ifa = ifa_ifwithdstaddr(&entry->rt_dst);
                        if (ifa == 0)
                                ifa = ifa_ifwithaddr(&entry->rt_gateway);
                } else {
                        /*
                         * If we are adding a route to a remote net
                         * or host, the gateway may still be on the
                         * other end of a pt to pt link.
                         */
                        ifa = ifa_ifwithdstaddr(&entry->rt_gateway);
                }
                if (ifa == 0) {
                        ifa = ifa_ifwithnet(&entry->rt_gateway);
                        if (ifa == 0) {
                                error = ENETUNREACH;
                                goto bad;
                        }
                }
                m = m_get(M_DONTWAIT, MT_RTABLE);
                if (m == 0) {
                        error = ENOBUFS;
                        goto bad;
                }
                m->m_next = *mfirst;
                *mfirst = m;
                m->m_len = sizeof (struct rtentry);
                rt = mtod(m, struct rtentry *);
                rt->rt_hash = hash;
                rt->rt_dst = entry->rt_dst;
                rt->rt_gateway = entry->rt_gateway;
                rt->rt_flags = RTF_UP |
                    (entry->rt_flags & (RTF_HOST|RTF_GATEWAY|RTF_DYNAMIC));
                rt->rt_refcnt = 0;
                rt->rt_use = 0;
                rt->rt_ifp = ifa->ifa_ifp;
                break;
        }
bad:
        splx(s);
        return (error);
}

/*
 * Set up a routing table entry, normally
 * for an interface.
 */
rtinit(dst, gateway, cmd, flags)
        struct sockaddr *dst, *gateway;
        int cmd, flags;
{
        struct rtentry route;

        bzero((caddr_t)&route, sizeof (route));
        route.rt_dst = *dst;
        route.rt_gateway = *gateway;
        route.rt_flags = flags;
        (void) rtrequest(cmd, &route);
}