FreeBSD/Linux Kernel Cross Reference
sys/netinet/in_rmx.c

     /*
      * 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 1.37.2.3 2002/08/09 14:49:23 ru Exp $
     * $DragonFly: src/sys/netinet/in_rmx.c,v 1.14 2006/04/11 06:59:34 dillon 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 "opt_carp.h"
    
    #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 <sys/globaldata.h>
    #include <sys/thread2.h>
    
    #include <net/if.h>
    #include <net/route.h>
    #include <net/if_var.h>
    #ifdef CARP
    #include <net/if_types.h>
    #endif
    #include <net/netmsg2.h>
    #include <net/netisr2.h>
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    #include <netinet/ip_var.h>
    #include <netinet/ip_flow.h>
    
    #define RTPRF_EXPIRING  RTF_PROTO3      /* set on routes we manage */
    
    struct in_rtqtimo_ctx {
            struct callout          timo_ch;
            struct netmsg_base      timo_nmsg;
            struct radix_node_head  *timo_rnh;
    } __cachealign;
    
    static void     in_rtqtimo(void *);
    
    static struct in_rtqtimo_ctx in_rtqtimo_context[MAXCPU];
    
    /*
     * Do what we need to do when inserting a route.
     */
    static struct radix_node *
    in_addroute(char *key, char *mask, 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;
            struct in_ifaddr_container *iac;
            struct in_ifaddr *ia;
    
            /*
             * For IP, 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).
            *
            * 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;
   
           /*
            *   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).
            *
            *   For local routes we set RTF_LOCAL allowing various shortcuts.
            *
            *   A cloned network route will point to one of several possible
            *   addresses if an interface has aliases and must be repointed
            *   back to the correct address or arp_rtrequest() will not properly
            *   detect the local ip.
            */
           if (rt->rt_flags & RTF_HOST) {
                   if (in_broadcast(sin->sin_addr, rt->rt_ifp)) {
                           rt->rt_flags |= RTF_BROADCAST;
                   } else if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr ==
                              sin->sin_addr.s_addr) {
                           rt->rt_flags |= RTF_LOCAL;
                   } else {
                           LIST_FOREACH(iac, INADDR_HASH(sin->sin_addr.s_addr),
                                        ia_hash) {
                                   ia = iac->ia;
                                   if (sin->sin_addr.s_addr ==
                                       ia->ia_addr.sin_addr.s_addr) {
                                           rt->rt_flags |= RTF_LOCAL;
                                           IFAREF(&ia->ia_ifa);
                                           IFAFREE(rt->rt_ifa);
                                           rt->rt_ifa = &ia->ia_ifa;
                                           rt->rt_ifp = rt->rt_ifa->ifa_ifp;
                                           break;
                                   }
                           }
                   }
           }
   
           if (rt->rt_rmx.rmx_mtu != 0 && !(rt->rt_rmx.rmx_locks & RTV_MTU) &&
               rt->rt_ifp != NULL)
                   rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
   
           ret = rn_addroute(key, mask, head, treenodes);
           if (ret == NULL && (rt->rt_flags & RTF_HOST)) {
                   struct rtentry *oldrt;
   
                   /*
                    * 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.
                    */
                   oldrt = rtpurelookup((struct sockaddr *)sin);
                   if (oldrt != NULL) {
                           --oldrt->rt_refcnt;
                           if ((oldrt->rt_flags & RTF_LLINFO) &&
                               (oldrt->rt_flags & RTF_HOST) &&
                               oldrt->rt_gateway &&
                               oldrt->rt_gateway->sa_family == AF_LINK) {
                                   rtrequest(RTM_DELETE, rt_key(oldrt),
                                             oldrt->rt_gateway, rt_mask(oldrt),
                                             oldrt->rt_flags, NULL);
                                   ret = rn_addroute(key, mask, head, treenodes);
                           }
                   }
           }
   
           /*
            * If the new route has been created successfully, and it is
            * not a multicast/broadcast or cloned route, then we will
            * have to flush the ipflow.  Otherwise, we may end up using
            * the wrong route.
            */
           if (ret != NULL &&
               (rt->rt_flags &
                (RTF_MULTICAST | RTF_BROADCAST | RTF_WASCLONED)) == 0) {
                   ipflow_flush_oncpu();
           }
           return ret;
   }
   
   /*
    * This code is the inverse of in_closeroute: 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_matchroute(char *key, struct radix_node_head *head)
   {
           struct radix_node *rn = rn_match(key, head);
           struct rtentry *rt = (struct rtentry *)rn;
   
           if (rt != NULL && rt->rt_refcnt == 0) { /* this is first reference */
                   if (rt->rt_flags & RTPRF_EXPIRING) {
                           rt->rt_flags &= ~RTPRF_EXPIRING;
                           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,
       "Default expiration time on cloned 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 cloned 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 cloned routes");
   
   /*
    * On last reference drop, mark the route as belong to us so that it can be
    * timed out.
    */
   static void
   in_closeroute(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_EXPIRING)) != 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_EXPIRING;
                   rt->rt_rmx.rmx_expire = time_uptime + rtq_reallyold;
           } else {
                   /*
                    * Remove route from the radix tree, but defer deallocation
                    * until we return to rtfree().
                    */
                   rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway, rt_mask(rt),
                             rt->rt_flags, &rt);
           }
   }
   
   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_EXPIRING) {
                   ap->found++;
                   if (ap->draining || rt->rt_rmx.rmx_expire <= time_uptime) {
                           if (rt->rt_refcnt > 0)
                                   panic("rtqkill route really not free");
   
                           err = rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
                                           rt_mask(rt), rt->rt_flags, NULL);
                           if (err)
                                   log(LOG_WARNING, "in_rtqkill: error %d\n", err);
                           else
                                   ap->killed++;
                   } else {
                           if (ap->updating &&
                               (int)(rt->rt_rmx.rmx_expire - time_uptime) >
                                rtq_reallyold) {
                                   rt->rt_rmx.rmx_expire = time_uptime +
                                       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;
   
   /*
    * NOTE:
    * 'last_adjusted_timeout' and 'rtq_reallyold' are _not_ read-only, and
    * could be changed by all CPUs.  However, they are changed at so low
    * frequency that we could ignore the cache trashing issue and take them
    * as read-mostly.
    */
   static void
   in_rtqtimo_dispatch(netmsg_t nmsg)
   {
           struct rtqk_arg arg;
           struct timeval atv;
           static time_t last_adjusted_timeout = 0;
           struct in_rtqtimo_ctx *ctx = &in_rtqtimo_context[mycpuid];
           struct radix_node_head *rnh = ctx->timo_rnh;
   
           /* Reply ASAP */
           crit_enter();
           lwkt_replymsg(&nmsg->lmsg, 0);
           crit_exit();
   
           arg.found = arg.killed = 0;
           arg.rnh = rnh;
           arg.nextstop = time_uptime + 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) &&
               (int)(time_uptime - 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 = time_uptime;
   #ifdef 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 - time_uptime;
           if ((int)atv.tv_sec < 1) {              /* time shift safety */
                   atv.tv_sec = 1;
                   arg.nextstop = time_uptime + atv.tv_sec;
           }
           if ((int)atv.tv_sec > rtq_timeout) {    /* time shift safety */
                   atv.tv_sec = rtq_timeout;
                   arg.nextstop = time_uptime + atv.tv_sec;
           }
           callout_reset(&ctx->timo_ch, tvtohz_high(&atv), in_rtqtimo, NULL);
   }
   
   static void
   in_rtqtimo(void *arg __unused)
   {
           int cpuid = mycpuid;
           struct lwkt_msg *lmsg = &in_rtqtimo_context[cpuid].timo_nmsg.lmsg;
   
           crit_enter();
           if (lmsg->ms_flags & MSGF_DONE)
                   lwkt_sendmsg_oncpu(netisr_cpuport(cpuid), lmsg);
           crit_exit();
   }
   
   void
   in_rtqdrain(void)
   {
           struct radix_node_head *rnh = rt_tables[mycpuid][AF_INET];
           struct rtqk_arg arg;
   
           arg.found = arg.killed = 0;
           arg.rnh = rnh;
           arg.nextstop = 0;
           arg.draining = 1;
           arg.updating = 0;
           crit_enter();
           rnh->rnh_walktree(rnh, in_rtqkill, &arg);
           crit_exit();
   }
   
   /*
    * Initialize our routing tree.
    */
   int
   in_inithead(void **head, int off)
   {
           struct radix_node_head *rnh;
           struct in_rtqtimo_ctx *ctx;
           int cpuid = mycpuid;
   
           if (!rn_inithead(head, rn_cpumaskhead(cpuid), off))
                   return 0;
   
           if (head != (void **)&rt_tables[cpuid][AF_INET]) /* BOGUS! */
                   return 1;       /* only do this for the real routing table */
   
           rnh = *head;
           rnh->rnh_addaddr = in_addroute;
           rnh->rnh_matchaddr = in_matchroute;
           rnh->rnh_close = in_closeroute;
   
           ctx = &in_rtqtimo_context[cpuid];
           ctx->timo_rnh = rnh;
           callout_init_mp(&ctx->timo_ch);
           netmsg_init(&ctx->timo_nmsg, NULL, &netisr_adone_rport, 0,
                       in_rtqtimo_dispatch);
   
           in_rtqtimo(NULL);       /* kick off timeout first time */
           return 1;
   }
   
   /*
    * 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.
    *
    * in_ifadown() is typically called when an interface is being brought
    * down.  We must iterate through all per-cpu route tables and clean
    * them up.
    */
   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;
   
           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.
                    */
                   rt->rt_flags &= ~(RTF_CLONING | RTF_PRCLONING);
                   err = rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
                                   rt_mask(rt), rt->rt_flags, NULL);
                   if (err)
                           log(LOG_WARNING, "in_ifadownkill: error %d\n", err);
           }
           return 0;
   }
   
   struct netmsg_ifadown {
           struct netmsg_base      base;
           struct ifaddr           *ifa;
           int                     del;
   };
   
   static void
   in_ifadown_dispatch(netmsg_t msg)
   {
           struct netmsg_ifadown *rmsg = (void *)msg;
           struct radix_node_head *rnh;
           struct ifaddr *ifa = rmsg->ifa;
           struct in_ifadown_arg arg;
           int nextcpu, cpu;
   
           cpu = mycpuid;
   
           arg.rnh = rnh = rt_tables[cpu][AF_INET];
           arg.ifa = ifa;
           arg.del = rmsg->del;
           rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
           ifa->ifa_flags &= ~IFA_ROUTE;
   
           nextcpu = cpu + 1;
           if (nextcpu < ncpus)
                   lwkt_forwardmsg(netisr_cpuport(nextcpu), &rmsg->base.lmsg);
           else
                   lwkt_replymsg(&rmsg->base.lmsg, 0);
   }
   
   int
   in_ifadown_force(struct ifaddr *ifa, int delete)
   {
           struct netmsg_ifadown msg;
   
           if (ifa->ifa_addr->sa_family != AF_INET)
                   return 1;
   
           /*
            * XXX individual requests are not independantly chained,
            * which means that the per-cpu route tables will not be
            * consistent in the middle of the operation.  If routes
            * related to the interface are manipulated while we are
            * doing this the inconsistancy could trigger a panic.
            */
           netmsg_init(&msg.base, NULL, &curthread->td_msgport, MSGF_PRIORITY,
               in_ifadown_dispatch);
           msg.ifa = ifa;
           msg.del = delete;
           rt_domsg_global(&msg.base);
   
           return 0;
   }
   
   int
   in_ifadown(struct ifaddr *ifa, int delete)
   {
   #ifdef CARP
           if (ifa->ifa_ifp->if_type == IFT_CARP)
                   return 0;
   #endif
           return in_ifadown_force(ifa, delete);
   }

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