in_rmx.c

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/*-
 * Copyright 1994, 1995 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that both the above copyright notice and this
 * permission notice appear in all copies, that both the above
 * copyright notice and this permission notice appear in all
 * supporting documentation, and that the name of M.I.T. not be used
 * in advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.  M.I.T. makes
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/socket.h>
#include <sys/mbuf.h>
 
#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>
#include <net/route/route_ctl.h>
#include <net/route/route_var.h>
#include <net/route/nhop.h>
#include <net/vnet.h>
 
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_var.h>
 
static int
rib4_preadd(u_int fibnum, const struct sockaddr *addr, const struct sockaddr *mask,
    struct nhop_object *nh)
{
        const struct sockaddr_in *addr4 = (const struct sockaddr_in *)addr;
        uint16_t nh_type;
        int rt_flags;
 
        /* XXX: RTF_LOCAL && RTF_MULTICAST */
 
        rt_flags = nhop_get_rtflags(nh);
 
        if (rt_flags & RTF_HOST) {
                /*
                 * Backward compatibility:
                 * if the destination is broadcast,
                 * mark route as broadcast.
                 * This behavior was useful when route cloning
                 * was in place, so there was an explicit cloned
                 * route for every broadcasted address.
                 * Currently (2020-04) there is no kernel machinery
                 * to do route cloning, though someone might explicitly
                 * add these routes to support some cases with active-active
                 * load balancing. Given that, retain this support.
                 */
                if (in_broadcast(addr4->sin_addr, nh->nh_ifp)) {
                        rt_flags |= RTF_BROADCAST;
                        nhop_set_rtflags(nh, rt_flags);
                        nh->nh_flags |= NHF_BROADCAST;
                }
        }
 
        /*
         * Check route MTU:
         * inherit interface MTU if not set or
         * check if MTU is too large.
         */
        if (nh->nh_mtu == 0) {
                nh->nh_mtu = nh->nh_ifp->if_mtu;
        } else if (nh->nh_mtu > nh->nh_ifp->if_mtu)
                nh->nh_mtu = nh->nh_ifp->if_mtu;
 
        /* Ensure that default route nhop has special flag */
        const struct sockaddr_in *mask4 = (const struct sockaddr_in *)mask;
        if ((rt_flags & RTF_HOST) == 0 && mask4 != NULL &&
            mask4->sin_addr.s_addr == 0)
                nh->nh_flags |= NHF_DEFAULT;
 
        /* Set nhop type to basic per-AF nhop */
        if (nhop_get_type(nh) == 0) {
                if (nh->nh_flags & NHF_GATEWAY)
                        nh_type = NH_TYPE_IPV4_ETHER_NHOP;
                else
                        nh_type = NH_TYPE_IPV4_ETHER_RSLV;
 
                nhop_set_type(nh, nh_type);
        }
 
        return (0);
}
 
/*
 * Initialize our routing tree.
 */
struct rib_head *
in_inithead(uint32_t fibnum)
{
        struct rib_head *rh;
 
        rh = rt_table_init(32, AF_INET, fibnum);
        if (rh == NULL)
                return (NULL);
 
        rh->rnh_preadd = rib4_preadd;
 
        return (rh);
}
 
#ifdef VIMAGE
void
in_detachhead(struct rib_head *rh)
{
 
        rt_table_destroy(rh);
}
#endif
 
/*
 * This zaps old routes when the interface goes down or interface
 * address is deleted.  In the latter case, it deletes static routes
 * that point to this address.  If we don't do this, we may end up
 * using the old address in the future.  The ones we always want to
 * get rid of are things like ARP entries, since the user might down
 * the interface, walk over to a completely different network, and
 * plug back in.
 */
struct in_ifadown_arg {
        struct ifaddr *ifa;
        int del;
};
 
static int
in_ifadownkill(const struct rtentry *rt, const struct nhop_object *nh,
    void *xap)
{
        struct in_ifadown_arg *ap = xap;
 
        if (nh->nh_ifa != ap->ifa)
                return (0);
 
        if ((nhop_get_rtflags(nh) & RTF_STATIC) != 0 && ap->del == 0)
                return (0);
 
        return (1);
}
 
void
in_ifadown(struct ifaddr *ifa, int delete)
{
        struct in_ifadown_arg arg;
 
        KASSERT(ifa->ifa_addr->sa_family == AF_INET,
            ("%s: wrong family", __func__));
 
        arg.ifa = ifa;
        arg.del = delete;
 
        rib_foreach_table_walk_del(AF_INET, in_ifadownkill, &arg);
        ifa->ifa_flags &= ~IFA_ROUTE;           /* XXXlocking? */
}