source: rtems/cpukit/libnetworking/netinet/in_rmx.c @ 9b4422a2

/*
 * 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.
 */

/*
 * 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.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#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(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;
}