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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.

 *

 * in_rmx.c,v 1.1 1998/08/19 21:32:19 joel 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/queue.h>

#include <sys/socket.h>

#include <sys/socketvar.h>

#include <sys/mbuf.h>

#include <sys/syslog.h>

#include <net/if.h>

#include <net/route.h>

#include <netinet/in.h>

#include <netinet/in_systm.h>

#include <netinet/in_var.h>

#include <netinet/ip.h>

#include <netinet/ip_var.h>

#include <netinet/tcp.h>

#include <netinet/tcp_seq.h>

#include <netinet/tcp_timer.h>

#include <netinet/tcp_var.h>

extern int      in_inithead __P((void **head, int off));

#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;

        /*

         * 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

                }

        }

        /*

         * We also specify a send and receive pipe size for every

         * route added, to help TCP a bit.  TCP doesn't actually

         * want a true pipe size, which would be prohibitive in memory

         * costs and is hard to compute anyway; it simply uses these

         * values to size its buffers.  So, we fill them in with the

         * same values that TCP would have used anyway, and allow the

         * installing program or the link layer to override these values

         * as it sees fit.  This will hopefully allow TCP more

         * opportunities to save its ssthresh value.

         */

        if (!rt->rt_rmx.rmx_sendpipe && !(rt->rt_rmx.rmx_locks & RTV_SPIPE))

                rt->rt_rmx.rmx_sendpipe = tcp_sendspace;

        if (!rt->rt_rmx.rmx_recvpipe && !(rt->rt_rmx.rmx_locks & RTV_RPIPE))

                rt->rt_rmx.rmx_recvpipe = tcp_recvspace;

        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((struct sockaddr *)sin, 0,

                                RTF_CLONING | RTF_PRCLONING);

                if (rt2) {

                        if (rt2->rt_flags & RTF_LLINFO &&

                                rt2->rt_flags & RTF_HOST &&

                                rt2->rt_gateway &&

                                rt2->rt_gateway->sa_family == AF_LINK) {

                                rtrequest(RTM_DELETE,

                                          (struct sockaddr *)rt_key(rt2),

                                          rt2->rt_gateway,

                                          rt_mask(rt2), rt2->rt_flags, 0);

                                ret = rn_addroute(v_arg, n_arg, head,

                                        treenodes);

                        }

                        RTFREE(rt2);

                }

        }

        return ret;

}

/*

 * 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(void *v_arg, struct radix_node_head *head)

{

        struct radix_node *rn = rn_match(v_arg, head);

        struct rtentry *rt = (struct rtentry *)rn;

        if(rt && rt->rt_refcnt == 0) { /* this is first reference */

                if(rt->rt_flags & RTPRF_OURS) {

                        rt->rt_flags &= ~RTPRF_OURS;

                        rt->rt_rmx.rmx_expire = 0;

                }

        }

        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, "");

static int rtq_minreallyold = 10;

        /* never automatically crank down to less */

SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire,

        CTLFLAG_RW, &rtq_minreallyold , 0, "");

static int rtq_toomany = 128;

        /* 128 cached routes is ``too many'' */

SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache,

        CTLFLAG_RW, &rtq_toomany , 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, struct radix_node_head *head)

{

        struct rtentry *rt = (struct rtentry *)rn;

        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;

        /*

         * As requested by David Greenman:

         * If rtq_reallyold is 0, just delete the route without

         * waiting for a timeout cycle to kill it.

         */

        if(rtq_reallyold != 0) {

                rt->rt_flags |= RTPRF_OURS;

                rt->rt_rmx.rmx_expire = rtems_bsdnet_seconds_since_boot() + rtq_reallyold;

        } else {

                rtrequest(RTM_DELETE,

                          (struct sockaddr *)rt_key(rt),

                          rt->rt_gateway, rt_mask(rt),

                          rt->rt_flags, 0);

        }

}

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;

        if(rt->rt_flags & RTPRF_OURS) {

                ap->found++;

                if(ap->draining || rt->rt_rmx.rmx_expire <= rtems_bsdnet_seconds_since_boot()) {

                        if(rt->rt_refcnt > 0)

                                panic("rtqkill route really not free");

                        err = rtrequest(RTM_DELETE,

                                        (struct sockaddr *)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 - rtems_bsdnet_seconds_since_boot()

                               > rtq_reallyold)) {

                                rt->rt_rmx.rmx_expire = rtems_bsdnet_seconds_since_boot()

                                        + rtq_reallyold;

                        }

                        ap->nextstop = lmin(ap->nextstop,

                                            rt->rt_rmx.rmx_expire);

                }

        }

        return 0;

}

#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;

        int s;

        arg.found = arg.killed = 0;

        arg.rnh = rnh;

        arg.nextstop = rtems_bsdnet_seconds_since_boot() + rtq_timeout;

        arg.draining = arg.updating = 0;

        s = splnet();

        rnh->rnh_walktree(rnh, in_rtqkill, &arg);

        splx(s);

        /*

         * 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)

           && (rtems_bsdnet_seconds_since_boot() - 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 = rtems_bsdnet_seconds_since_boot();

#ifdef DIAGNOSTIC

                log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",

                    rtq_reallyold);

#endif

                arg.found = arg.killed = 0;

                arg.updating = 1;

                s = splnet();

                rnh->rnh_walktree(rnh, in_rtqkill, &arg);

                splx(s);

        }

        atv.tv_usec = 0;

        atv.tv_sec = arg.nextstop;

        timeout(in_rtqtimo, rock, hzto(&atv));

}

void

in_rtqdrain(void)

{

        struct radix_node_head *rnh = rt_tables[AF_INET];

        struct rtqk_arg arg;

        int s;

        arg.found = arg.killed = 0;

        arg.rnh = rnh;

        arg.nextstop = 0;

        arg.draining = 1;

        arg.updating = 0;

        s = splnet();

        rnh->rnh_walktree(rnh, in_rtqkill, &arg);

        splx(s);

}

/*

 * Initialize our routing tree.

 */

int

in_inithead(void **head, int off)

{

        struct radix_node_head *rnh;

        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_close = in_clsroute;

        in_rtqtimo(rnh);        /* kick off timeout first time */

        return 1;

}