[apple/xnu.git] / bsd / netinet / in_rmx.c

/*
 * Copyright (c) 2000-2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * 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.
 *
 * $FreeBSD: src/sys/netinet/in_rmx.c,v 1.37.2.1 2001/05/14 08:23:49 ru Exp $
 */

/*
 * This code does two things necessary for the enhanced TCP metrics to
 * function in a useful manner:
 *  1) It marks all non-host routes as `cloning', thus ensuring that
 *     every actual reference to such a route actually gets turned
 *     into a reference to a host route to the specific destination
 *     requested.
 *  2) When such routes lose all their references, it arranges for them
 *     to be deleted in some random collection of circumstances, so that
 *     a large quantity of stale routing data is not kept in kernel memory
 *     indefinitely.  See in_rtqtimo() below for the exact mechanism.
 */

#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 <sys/syslog.h>
#include <kern/lock.h>

#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_var.h>

extern int tvtohz(struct timeval *);
extern int      in_inithead(void **head, int off);

#ifdef __APPLE__
static void in_rtqtimo(void *rock);
#endif

static struct radix_node *in_matroute_args(void *, struct radix_node_head *,
    rn_matchf_t *f, void *);

#define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */

/*
 * Do what we need to do when inserting a route.
 */
static struct radix_node *
in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
            struct radix_node *treenodes)
{
        struct rtentry *rt = (struct rtentry *)treenodes;
        struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
        struct radix_node *ret;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);
        RT_LOCK_ASSERT_HELD(rt);

        /*
         * For IP, all unicast non-host routes are automatically cloning.
         */
        if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
                rt->rt_flags |= RTF_MULTICAST;

        if (!(rt->rt_flags & (RTF_HOST | RTF_CLONING | RTF_MULTICAST))) {
                rt->rt_flags |= RTF_PRCLONING;
        }

        /*
         * A little bit of help for both IP output and input:
         *   For host routes, we make sure that RTF_BROADCAST
         *   is set for anything that looks like a broadcast address.
         *   This way, we can avoid an expensive call to in_broadcast()
         *   in ip_output() most of the time (because the route passed
         *   to ip_output() is almost always a host route).
         *
         *   We also do the same for local addresses, with the thought
         *   that this might one day be used to speed up ip_input().
         *
         * We also mark routes to multicast addresses as such, because
         * it's easy to do and might be useful (but this is much more
         * dubious since it's so easy to inspect the address).  (This
         * is done above.)
         */
        if (rt->rt_flags & RTF_HOST) {
                if (in_broadcast(sin->sin_addr, rt->rt_ifp)) {
                        rt->rt_flags |= RTF_BROADCAST;
                } else {
#define satosin(sa) ((struct sockaddr_in *)sa)
                        if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr
                            == sin->sin_addr.s_addr)
                                rt->rt_flags |= RTF_LOCAL;
#undef satosin
                }
        }

        if (!rt->rt_rmx.rmx_mtu && !(rt->rt_rmx.rmx_locks & RTV_MTU) 
            && rt->rt_ifp)
                rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;

        ret = rn_addroute(v_arg, n_arg, head, treenodes);
        if (ret == NULL && rt->rt_flags & RTF_HOST) {
                struct rtentry *rt2;
                /*
                 * We are trying to add a host route, but can't.
                 * Find out if it is because of an
                 * ARP entry and delete it if so.
                 */
                rt2 = rtalloc1_scoped_locked(rt_key(rt), 0,
                    RTF_CLONING | RTF_PRCLONING, sa_get_ifscope(rt_key(rt)));
                if (rt2) {
                        RT_LOCK(rt2);
                        if ((rt2->rt_flags & RTF_LLINFO) &&
                            (rt2->rt_flags & RTF_HOST) &&
                            rt2->rt_gateway != NULL &&
                            rt2->rt_gateway->sa_family == AF_LINK) {
                                /*
                                 * Safe to drop rt_lock and use rt_key,
                                 * rt_gateway, since holding rnh_lock here
                                 * prevents another thread from calling
                                 * rt_setgate() on this route.
                                 */
                                RT_UNLOCK(rt2);
                                rtrequest_locked(RTM_DELETE, rt_key(rt2),
                                    rt2->rt_gateway, rt_mask(rt2),
                                    rt2->rt_flags, 0);
                                ret = rn_addroute(v_arg, n_arg, head,
                                        treenodes);
                        } else {
                                RT_UNLOCK(rt2);
                        }
                        rtfree_locked(rt2);
                }
        }
        return ret;
}

/*
 * Validate (unexpire) an expiring AF_INET route.
 */
struct radix_node *
in_validate(struct radix_node *rn)
{
        struct rtentry *rt = (struct rtentry *)rn;

        RT_LOCK_ASSERT_HELD(rt);

        /* This is first reference? */
        if (rt->rt_refcnt == 0 && (rt->rt_flags & RTPRF_OURS)) {
                rt->rt_flags &= ~RTPRF_OURS;
                rt->rt_rmx.rmx_expire = 0;
        }
        return (rn);
}

/*
 * Similar to in_matroute_args except without the leaf-matching parameters.
 */
static struct radix_node *
in_matroute(void *v_arg, struct radix_node_head *head)
{
        return (in_matroute_args(v_arg, head, NULL, NULL));
}

/*
 * This code is the inverse of in_clsroute: on first reference, if we
 * were managing the route, stop doing so and set the expiration timer
 * back off again.
 */
static struct radix_node *
in_matroute_args(void *v_arg, struct radix_node_head *head,
    rn_matchf_t *f, void *w)
{
        struct radix_node *rn = rn_match_args(v_arg, head, f, w);

        if (rn != NULL) {
                RT_LOCK_SPIN((struct rtentry *)rn);
                in_validate(rn);
                RT_UNLOCK((struct rtentry *)rn);
        }
        return (rn);
}

static int rtq_reallyold = 60*60;
        /* one hour is ``really old'' */
SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW, 
    &rtq_reallyold , 0, 
    "Default expiration time on dynamically learned routes");
                                   
static int rtq_minreallyold = 10;
        /* never automatically crank down to less */
SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW, 
    &rtq_minreallyold , 0, 
    "Minimum time to attempt to hold onto dynamically learned routes");
                                   
static int rtq_toomany = 128;
        /* 128 cached routes is ``too many'' */
SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW, 
    &rtq_toomany , 0, "Upper limit on dynamically learned routes");

#ifdef __APPLE__
/* XXX LD11JUL02 Special case for AOL 5.1.2 connectivity issue to AirPort BS (Radar 2969954)
 * AOL is adding a circular route ("10.0.1.1/32 10.0.1.1") when establishing its ppp tunnel
 * to the AP BaseStation by removing the default gateway and replacing it with their tunnel entry point.
 * There is no apparent reason to add this route as there is a valid 10.0.1.1/24 route to the BS.
 * That circular route was ignored on previous version of MacOS X because of a routing bug
 * corrected with the merge to FreeBSD4.4 (a route generated from an RTF_CLONING route had the RTF_WASCLONED
 * flag set but did not have a reference to the parent route) and that entry was left in the RT. This workaround is
 * made in order to provide binary compatibility with AOL. 
 * If we catch a process adding a circular route with a /32 from the routing socket, we error it out instead of
 * confusing the routing table with a wrong route to the previous default gateway
 * If for some reason a circular route is needed, turn this sysctl (net.inet.ip.check_route_selfref) to zero.
 */
int check_routeselfref = 1;
SYSCTL_INT(_net_inet_ip, OID_AUTO, check_route_selfref, CTLFLAG_RW, 
    &check_routeselfref , 0, "");
#endif

int use_routegenid = 1;
SYSCTL_INT(_net_inet_ip, OID_AUTO, use_route_genid, CTLFLAG_RW, 
    &use_routegenid , 0, "");

/*
 * On last reference drop, mark the route as belong to us so that it can be
 * timed out.
 */
static void
in_clsroute(struct radix_node *rn, __unused struct radix_node_head *head)
{
        struct rtentry *rt = (struct rtentry *)rn;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);
        RT_LOCK_ASSERT_HELD(rt);

        if (!(rt->rt_flags & RTF_UP))
                return;         /* prophylactic measures */

        if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
                return;

        if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED)
                return;

        /*
         * Delete the route immediately if RTF_DELCLONE is set or
         * if route caching is disabled (rtq_reallyold set to 0).
         * Otherwise, let it expire and be deleted by in_rtqkill().
         */
        if ((rt->rt_flags & RTF_DELCLONE) || rtq_reallyold == 0) {
                /*
                 * Delete the route from the radix tree but since we are
                 * called when the route's reference count is 0, don't
                 * deallocate it until we return from this routine by
                 * telling rtrequest that we're interested in it.
                 * Safe to drop rt_lock and use rt_key, rt_gateway since
                 * holding rnh_lock here prevents another thread from
                 * calling rt_setgate() on this route.
                 */
                RT_UNLOCK(rt);
                if (rtrequest_locked(RTM_DELETE, (struct sockaddr *)rt_key(rt),
                    rt->rt_gateway, rt_mask(rt), rt->rt_flags, &rt) == 0) {
                        /* Now let the caller free it */
                        RT_LOCK(rt);
                        RT_REMREF_LOCKED(rt);
                } else {
                        RT_LOCK(rt);
                }
        } else {
                struct timeval timenow;

                getmicrotime(&timenow);
                rt->rt_flags |= RTPRF_OURS;
                rt->rt_rmx.rmx_expire = timenow.tv_sec + rtq_reallyold;
        }
}

struct rtqk_arg {
        struct radix_node_head *rnh;
        int draining;
        int killed;
        int found;
        int updating;
        time_t nextstop;
};

/*
 * Get rid of old routes.  When draining, this deletes everything, even when
 * the timeout is not expired yet.  When updating, this makes sure that
 * nothing has a timeout longer than the current value of rtq_reallyold.
 */
static int
in_rtqkill(struct radix_node *rn, void *rock)
{
        struct rtqk_arg *ap = rock;
        struct rtentry *rt = (struct rtentry *)rn;
        int err;
        struct timeval timenow;

        getmicrotime(&timenow);
        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        RT_LOCK(rt);
        if (rt->rt_flags & RTPRF_OURS) {
                ap->found++;

                if (ap->draining || rt->rt_rmx.rmx_expire <= timenow.tv_sec) {
                        if (rt->rt_refcnt > 0)
                                panic("rtqkill route really not free");

                        /*
                         * Delete this route since we're done with it;
                         * the route may be freed afterwards, so we
                         * can no longer refer to 'rt' upon returning
                         * from rtrequest().  Safe to drop rt_lock and
                         * use rt_key, rt_gateway since holding rnh_lock
                         * here prevents another thread from calling
                         * rt_setgate() on this route.
                         */
                        RT_UNLOCK(rt);
                        err = rtrequest_locked(RTM_DELETE, rt_key(rt),
                            rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
                        if (err) {
                                log(LOG_WARNING, "in_rtqkill: error %d\n", err);
                        } else {
                                ap->killed++;
                        }
                } else {
                        if (ap->updating
                           && (rt->rt_rmx.rmx_expire - timenow.tv_sec
                               > rtq_reallyold)) {
                                rt->rt_rmx.rmx_expire = timenow.tv_sec
                                        + rtq_reallyold;
                        }
                        ap->nextstop = lmin(ap->nextstop,
                                            rt->rt_rmx.rmx_expire);
                        RT_UNLOCK(rt);
                }
        } else {
                RT_UNLOCK(rt);
        }

        return 0;
}

static void
in_rtqtimo_funnel(void *rock)
{
        in_rtqtimo(rock);

}
#define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
static int rtq_timeout = RTQ_TIMEOUT;

static void
in_rtqtimo(void *rock)
{
        struct radix_node_head *rnh = rock;
        struct rtqk_arg arg;
        struct timeval atv;
        static time_t last_adjusted_timeout = 0;
        struct timeval timenow;

        lck_mtx_lock(rnh_lock);
        /* Get the timestamp after we acquire the lock for better accuracy */
        getmicrotime(&timenow);

        arg.found = arg.killed = 0;
        arg.rnh = rnh;
        arg.nextstop = timenow.tv_sec + rtq_timeout;
        arg.draining = arg.updating = 0;
        rnh->rnh_walktree(rnh, in_rtqkill, &arg);

        /*
         * Attempt to be somewhat dynamic about this:
         * If there are ``too many'' routes sitting around taking up space,
         * then crank down the timeout, and see if we can't make some more
         * go away.  However, we make sure that we will never adjust more
         * than once in rtq_timeout seconds, to keep from cranking down too
         * hard.
         */
        if((arg.found - arg.killed > rtq_toomany)
           && (timenow.tv_sec - last_adjusted_timeout >= rtq_timeout)
           && rtq_reallyold > rtq_minreallyold) {
                rtq_reallyold = 2*rtq_reallyold / 3;
                if(rtq_reallyold < rtq_minreallyold) {
                        rtq_reallyold = rtq_minreallyold;
                }

                last_adjusted_timeout = timenow.tv_sec;
#if DIAGNOSTIC
                log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",
                    rtq_reallyold);
#endif
                arg.found = arg.killed = 0;
                arg.updating = 1;
                rnh->rnh_walktree(rnh, in_rtqkill, &arg);
        }

        atv.tv_usec = 0;
        atv.tv_sec = arg.nextstop - timenow.tv_sec;
        lck_mtx_unlock(rnh_lock);
        timeout(in_rtqtimo_funnel, rock, tvtohz(&atv));
}

void
in_rtqdrain(void)
{
        struct radix_node_head *rnh = rt_tables[AF_INET];
        struct rtqk_arg arg;
        arg.found = arg.killed = 0;
        arg.rnh = rnh;
        arg.nextstop = 0;
        arg.draining = 1;
        arg.updating = 0;
        lck_mtx_lock(rnh_lock);
        rnh->rnh_walktree(rnh, in_rtqkill, &arg);
        lck_mtx_unlock(rnh_lock);
}

/*
 * Initialize our routing tree.
 */
int
in_inithead(void **head, int off)
{
        struct radix_node_head *rnh;

#ifdef __APPLE__
        if (*head)
                return 1;
#endif

        if(!rn_inithead(head, off))
                return 0;

        if(head != (void **)&rt_tables[AF_INET]) /* BOGUS! */
                return 1;       /* only do this for the real routing table */

        rnh = *head;
        rnh->rnh_addaddr = in_addroute;
        rnh->rnh_matchaddr = in_matroute;
        rnh->rnh_matchaddr_args = in_matroute_args;
        rnh->rnh_close = in_clsroute;
        in_rtqtimo(rnh);        /* kick off timeout first time */
        return 1;
}

\f
/*
 * 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 radix_node_head *rnh;
        struct ifaddr *ifa;
        int del;
};

static int
in_ifadownkill(struct radix_node *rn, void *xap)
{
        struct in_ifadown_arg *ap = xap;
        struct rtentry *rt = (struct rtentry *)rn;
        int err;

        RT_LOCK(rt);
        if (rt->rt_ifa == ap->ifa &&
            (ap->del || !(rt->rt_flags & RTF_STATIC))) {
                /*
                 * We need to disable the automatic prune that happens
                 * in this case in rtrequest() because it will blow
                 * away the pointers that rn_walktree() needs in order
                 * continue our descent.  We will end up deleting all
                 * the routes that rtrequest() would have in any case,
                 * so that behavior is not needed there.  Safe to drop
                 * rt_lock and use rt_key, rt_gateway, since holding
                 * rnh_lock here prevents another thread from calling
                 * rt_setgate() on this route.
                 */
                rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING);
                RT_UNLOCK(rt);
                err = rtrequest_locked(RTM_DELETE, rt_key(rt),
                    rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
                if (err) {
                        log(LOG_WARNING, "in_ifadownkill: error %d\n", err);
                }
        } else {
                RT_UNLOCK(rt);
        }
        return 0;
}

int
in_ifadown(struct ifaddr *ifa, int delete)
{
        struct in_ifadown_arg arg;
        struct radix_node_head *rnh;

        lck_mtx_assert(rnh_lock, LCK_MTX_ASSERT_OWNED);

        if (ifa->ifa_addr->sa_family != AF_INET)
                return 1;

        /* trigger route cache reevaluation */
        if (use_routegenid)
                routegenid_update();

        arg.rnh = rnh = rt_tables[AF_INET];
        arg.ifa = ifa;
        arg.del = delete;
        rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
        ifa->ifa_flags &= ~IFA_ROUTE;
        return 0;
}