The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/in_rmx.c

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    1 /*-
    2  * Copyright 1994, 1995 Massachusetts Institute of Technology
    3  *
    4  * Permission to use, copy, modify, and distribute this software and
    5  * its documentation for any purpose and without fee is hereby
    6  * granted, provided that both the above copyright notice and this
    7  * permission notice appear in all copies, that both the above
    8  * copyright notice and this permission notice appear in all
    9  * supporting documentation, and that the name of M.I.T. not be used
   10  * in advertising or publicity pertaining to distribution of the
   11  * software without specific, written prior permission.  M.I.T. makes
   12  * no representations about the suitability of this software for any
   13  * purpose.  It is provided "as is" without express or implied
   14  * warranty.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
   17  * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
   18  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
   20  * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   23  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   25  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   26  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 /*
   31  * This code does two things necessary for the enhanced TCP metrics to
   32  * function in a useful manner:
   33  *  1) It marks all non-host routes as `cloning', thus ensuring that
   34  *     every actual reference to such a route actually gets turned
   35  *     into a reference to a host route to the specific destination
   36  *     requested.
   37  *  2) When such routes lose all their references, it arranges for them
   38  *     to be deleted in some random collection of circumstances, so that
   39  *     a large quantity of stale routing data is not kept in kernel memory
   40  *     indefinitely.  See in_rtqtimo() below for the exact mechanism.
   41  */
   42 
   43 #include <sys/cdefs.h>
   44 __FBSDID("$FreeBSD: releng/7.3/sys/netinet/in_rmx.c 189895 2009-03-16 18:02:00Z rwatson $");
   45 
   46 #include <sys/param.h>
   47 #include <sys/systm.h>
   48 #include <sys/kernel.h>
   49 #include <sys/sysctl.h>
   50 #include <sys/socket.h>
   51 #include <sys/mbuf.h>
   52 #include <sys/syslog.h>
   53 #include <sys/callout.h>
   54 
   55 #include <net/if.h>
   56 #include <net/route.h>
   57 #include <netinet/in.h>
   58 #include <netinet/in_var.h>
   59 #include <netinet/ip_var.h>
   60 
   61 extern int      in_inithead(void **head, int off);
   62 
   63 #define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */
   64 
   65 /*
   66  * Do what we need to do when inserting a route.
   67  */
   68 static struct radix_node *
   69 in_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
   70     struct radix_node *treenodes)
   71 {
   72         struct rtentry *rt = (struct rtentry *)treenodes;
   73         struct sockaddr_in *sin = (struct sockaddr_in *)rt_key(rt);
   74         struct radix_node *ret;
   75 
   76         /*
   77          * A little bit of help for both IP output and input:
   78          *   For host routes, we make sure that RTF_BROADCAST
   79          *   is set for anything that looks like a broadcast address.
   80          *   This way, we can avoid an expensive call to in_broadcast()
   81          *   in ip_output() most of the time (because the route passed
   82          *   to ip_output() is almost always a host route).
   83          *
   84          *   We also do the same for local addresses, with the thought
   85          *   that this might one day be used to speed up ip_input().
   86          *
   87          * We also mark routes to multicast addresses as such, because
   88          * it's easy to do and might be useful (but this is much more
   89          * dubious since it's so easy to inspect the address).
   90          */
   91         if (rt->rt_flags & RTF_HOST) {
   92                 if (in_broadcast(sin->sin_addr, rt->rt_ifp)) {
   93                         rt->rt_flags |= RTF_BROADCAST;
   94                 } else if (satosin(rt->rt_ifa->ifa_addr)->sin_addr.s_addr ==
   95                     sin->sin_addr.s_addr) {
   96                         rt->rt_flags |= RTF_LOCAL;
   97                 }
   98         }
   99         if (IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
  100                 rt->rt_flags |= RTF_MULTICAST;
  101 
  102         if (!rt->rt_rmx.rmx_mtu && rt->rt_ifp)
  103                 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
  104 
  105         ret = rn_addroute(v_arg, n_arg, head, treenodes);
  106         if (ret == NULL && rt->rt_flags & RTF_HOST) {
  107                 struct rtentry *rt2;
  108                 /*
  109                  * We are trying to add a host route, but can't.
  110                  * Find out if it is because of an
  111                  * ARP entry and delete it if so.
  112                  */
  113                 rt2 = in_rtalloc1((struct sockaddr *)sin, 0,
  114                     RTF_CLONING|RTF_RNH_LOCKED, rt->rt_fibnum);
  115                 if (rt2) {
  116                         if (rt2->rt_flags & RTF_LLINFO &&
  117                             rt2->rt_flags & RTF_HOST &&
  118                             rt2->rt_gateway &&
  119                             rt2->rt_gateway->sa_family == AF_LINK) {
  120                                 rtexpunge(rt2);
  121                                 RTFREE_LOCKED(rt2);
  122                                 ret = rn_addroute(v_arg, n_arg, head,
  123                                                   treenodes);
  124                         } else
  125                                 RTFREE_LOCKED(rt2);
  126                 }
  127         }
  128 
  129         return ret;
  130 }
  131 
  132 /*
  133  * This code is the inverse of in_clsroute: on first reference, if we
  134  * were managing the route, stop doing so and set the expiration timer
  135  * back off again.
  136  */
  137 static struct radix_node *
  138 in_matroute(void *v_arg, struct radix_node_head *head)
  139 {
  140         struct radix_node *rn = rn_match(v_arg, head);
  141         struct rtentry *rt = (struct rtentry *)rn;
  142 
  143         /*XXX locking? */
  144         if (rt && rt->rt_refcnt == 0) {         /* this is first reference */
  145                 if (rt->rt_flags & RTPRF_OURS) {
  146                         rt->rt_flags &= ~RTPRF_OURS;
  147                         rt->rt_rmx.rmx_expire = 0;
  148                 }
  149         }
  150         return rn;
  151 }
  152 
  153 static int rtq_reallyold = 60*60;               /* one hour is "really old" */
  154 SYSCTL_INT(_net_inet_ip, IPCTL_RTEXPIRE, rtexpire, CTLFLAG_RW,
  155     &rtq_reallyold, 0, "Default expiration time on dynamically learned routes");
  156 
  157 static int rtq_minreallyold = 10;  /* never automatically crank down to less */
  158 SYSCTL_INT(_net_inet_ip, IPCTL_RTMINEXPIRE, rtminexpire, CTLFLAG_RW,
  159     &rtq_minreallyold, 0,
  160     "Minimum time to attempt to hold onto dynamically learned routes");
  161 
  162 static int rtq_toomany = 128;           /* 128 cached routes is "too many" */
  163 SYSCTL_INT(_net_inet_ip, IPCTL_RTMAXCACHE, rtmaxcache, CTLFLAG_RW,
  164     &rtq_toomany, 0, "Upper limit on dynamically learned routes");
  165 
  166 /*
  167  * On last reference drop, mark the route as belong to us so that it can be
  168  * timed out.
  169  */
  170 static void
  171 in_clsroute(struct radix_node *rn, struct radix_node_head *head)
  172 {
  173         struct rtentry *rt = (struct rtentry *)rn;
  174 
  175         RT_LOCK_ASSERT(rt);
  176 
  177         if (!(rt->rt_flags & RTF_UP))
  178                 return;                 /* prophylactic measures */
  179 
  180         if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
  181                 return;
  182 
  183         if (rt->rt_flags & RTPRF_OURS)
  184                 return;
  185 
  186         if (!(rt->rt_flags & (RTF_WASCLONED | RTF_DYNAMIC)))
  187                 return;
  188 
  189         /*
  190          * If rtq_reallyold is 0, just delete the route without
  191          * waiting for a timeout cycle to kill it.
  192          */
  193         if (rtq_reallyold != 0) {
  194                 rt->rt_flags |= RTPRF_OURS;
  195                 rt->rt_rmx.rmx_expire = time_uptime + rtq_reallyold;
  196         } else {
  197                 rtexpunge(rt);
  198         }
  199 }
  200 
  201 struct rtqk_arg {
  202         struct radix_node_head *rnh;
  203         int draining;
  204         int killed;
  205         int found;
  206         int updating;
  207         time_t nextstop;
  208 };
  209 
  210 /*
  211  * Get rid of old routes.  When draining, this deletes everything, even when
  212  * the timeout is not expired yet.  When updating, this makes sure that
  213  * nothing has a timeout longer than the current value of rtq_reallyold.
  214  */
  215 static int
  216 in_rtqkill(struct radix_node *rn, void *rock)
  217 {
  218         struct rtqk_arg *ap = rock;
  219         struct rtentry *rt = (struct rtentry *)rn;
  220         int err;
  221 
  222         RADIX_NODE_HEAD_LOCK_ASSERT(ap->rnh);
  223 
  224         if (rt->rt_flags & RTPRF_OURS) {
  225                 ap->found++;
  226 
  227                 if (ap->draining || rt->rt_rmx.rmx_expire <= time_uptime) {
  228                         if (rt->rt_refcnt > 0)
  229                                 panic("rtqkill route really not free");
  230 
  231                         err = in_rtrequest(RTM_DELETE,
  232                                         (struct sockaddr *)rt_key(rt),
  233                                         rt->rt_gateway, rt_mask(rt),
  234                                         rt->rt_flags | RTF_RNH_LOCKED, 0,
  235                                         rt->rt_fibnum);
  236                         if (err) {
  237                                 log(LOG_WARNING, "in_rtqkill: error %d\n", err);
  238                         } else {
  239                                 ap->killed++;
  240                         }
  241                 } else {
  242                         if (ap->updating &&
  243                             (rt->rt_rmx.rmx_expire - time_uptime >
  244                              rtq_reallyold)) {
  245                                 rt->rt_rmx.rmx_expire =
  246                                     time_uptime + rtq_reallyold;
  247                         }
  248                         ap->nextstop = lmin(ap->nextstop,
  249                                             rt->rt_rmx.rmx_expire);
  250                 }
  251         }
  252 
  253         return 0;
  254 }
  255 
  256 #define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
  257 static int rtq_timeout = RTQ_TIMEOUT;
  258 static struct callout rtq_timer;
  259 
  260 static void in_rtqtimo_one(void *rock);
  261 
  262 static void
  263 in_rtqtimo(void *rock)
  264 {
  265         int fibnum;
  266         void *newrock;
  267         struct timeval atv;
  268 
  269         KASSERT((rock == (void *)rt_tables[0][AF_INET]),
  270                         ("in_rtqtimo: unexpected arg"));
  271         for (fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  272                 if ((newrock = rt_tables[fibnum][AF_INET]) != NULL)
  273                         in_rtqtimo_one(newrock);
  274         }
  275         atv.tv_usec = 0;
  276         atv.tv_sec = rtq_timeout;
  277         callout_reset(&rtq_timer, tvtohz(&atv), in_rtqtimo, rock);
  278 }
  279 
  280 static void
  281 in_rtqtimo_one(void *rock)
  282 {
  283         struct radix_node_head *rnh = rock;
  284         struct rtqk_arg arg;
  285         static time_t last_adjusted_timeout = 0;
  286 
  287         arg.found = arg.killed = 0;
  288         arg.rnh = rnh;
  289         arg.nextstop = time_uptime + rtq_timeout;
  290         arg.draining = arg.updating = 0;
  291         RADIX_NODE_HEAD_LOCK(rnh);
  292         rnh->rnh_walktree(rnh, in_rtqkill, &arg);
  293         RADIX_NODE_HEAD_UNLOCK(rnh);
  294 
  295         /*
  296          * Attempt to be somewhat dynamic about this:
  297          * If there are ``too many'' routes sitting around taking up space,
  298          * then crank down the timeout, and see if we can't make some more
  299          * go away.  However, we make sure that we will never adjust more
  300          * than once in rtq_timeout seconds, to keep from cranking down too
  301          * hard.
  302          */
  303         if ((arg.found - arg.killed > rtq_toomany) &&
  304             (time_uptime - last_adjusted_timeout >= rtq_timeout) &&
  305             rtq_reallyold > rtq_minreallyold) {
  306                 rtq_reallyold = 2 * rtq_reallyold / 3;
  307                 if (rtq_reallyold < rtq_minreallyold) {
  308                         rtq_reallyold = rtq_minreallyold;
  309                 }
  310 
  311                 last_adjusted_timeout = time_uptime;
  312 #ifdef DIAGNOSTIC
  313                 log(LOG_DEBUG, "in_rtqtimo: adjusted rtq_reallyold to %d\n",
  314                     rtq_reallyold);
  315 #endif
  316                 arg.found = arg.killed = 0;
  317                 arg.updating = 1;
  318                 RADIX_NODE_HEAD_LOCK(rnh);
  319                 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
  320                 RADIX_NODE_HEAD_UNLOCK(rnh);
  321         }
  322 
  323 }
  324 
  325 void
  326 in_rtqdrain(void)
  327 {
  328         struct radix_node_head *rnh;
  329         struct rtqk_arg arg;
  330         int     fibnum;
  331 
  332         for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  333                 rnh = rt_tables[fibnum][AF_INET];
  334                 arg.found = arg.killed = 0;
  335                 arg.rnh = rnh;
  336                 arg.nextstop = 0;
  337                 arg.draining = 1;
  338                 arg.updating = 0;
  339                 RADIX_NODE_HEAD_LOCK(rnh);
  340                 rnh->rnh_walktree(rnh, in_rtqkill, &arg);
  341                 RADIX_NODE_HEAD_UNLOCK(rnh);
  342         }
  343 }
  344 
  345 static int _in_rt_was_here;
  346 /*
  347  * Initialize our routing tree.
  348  */
  349 int
  350 in_inithead(void **head, int off)
  351 {
  352         struct radix_node_head *rnh;
  353 
  354         /* XXX MRT
  355          * This can be called from vfs_export.c too in which case 'off'
  356          * will be 0. We know the correct value so just use that and
  357          * return directly if it was 0.
  358          * This is a hack that replaces an even worse hack on a bad hack
  359          * on a bad design. After RELENG_7 this should be fixed but that
  360          * will change the ABI, so for now do it this way.
  361          */
  362         if (!rn_inithead(head, 32))
  363                 return 0;
  364 
  365         if (off == 0)           /* XXX MRT  see above */
  366                 return 1;       /* only do the rest for a real routing table */
  367 
  368         rnh = *head;
  369         rnh->rnh_addaddr = in_addroute;
  370         rnh->rnh_matchaddr = in_matroute;
  371         rnh->rnh_close = in_clsroute;
  372         if (_in_rt_was_here == 0 ) {
  373                 callout_init(&rtq_timer, CALLOUT_MPSAFE);
  374                 in_rtqtimo(rnh);        /* kick off timeout first time */
  375                 _in_rt_was_here = 1;
  376         }
  377         return 1;
  378 }
  379 
  380 /*
  381  * This zaps old routes when the interface goes down or interface
  382  * address is deleted.  In the latter case, it deletes static routes
  383  * that point to this address.  If we don't do this, we may end up
  384  * using the old address in the future.  The ones we always want to
  385  * get rid of are things like ARP entries, since the user might down
  386  * the interface, walk over to a completely different network, and
  387  * plug back in.
  388  */
  389 struct in_ifadown_arg {
  390         struct radix_node_head *rnh;
  391         struct ifaddr *ifa;
  392         int del;
  393 };
  394 
  395 static int
  396 in_ifadownkill(struct radix_node *rn, void *xap)
  397 {
  398         struct in_ifadown_arg *ap = xap;
  399         struct rtentry *rt = (struct rtentry *)rn;
  400 
  401         RT_LOCK(rt);
  402         if (rt->rt_ifa == ap->ifa &&
  403             (ap->del || !(rt->rt_flags & RTF_STATIC))) {
  404                 /*
  405                  * We need to disable the automatic prune that happens
  406                  * in this case in rtrequest() because it will blow
  407                  * away the pointers that rn_walktree() needs in order
  408                  * continue our descent.  We will end up deleting all
  409                  * the routes that rtrequest() would have in any case,
  410                  * so that behavior is not needed there.
  411                  */
  412                 rt->rt_flags &= ~RTF_CLONING;
  413                 rtexpunge(rt);
  414         }
  415         RT_UNLOCK(rt);
  416         return 0;
  417 }
  418 
  419 int
  420 in_ifadown(struct ifaddr *ifa, int delete)
  421 {
  422         struct in_ifadown_arg arg;
  423         struct radix_node_head *rnh;
  424         int     fibnum;
  425 
  426         if (ifa->ifa_addr->sa_family != AF_INET)
  427                 return 1;
  428 
  429         for ( fibnum = 0; fibnum < rt_numfibs; fibnum++) {
  430                 arg.rnh = rnh = rt_tables[fibnum][AF_INET];
  431                 arg.ifa = ifa;
  432                 arg.del = delete;
  433                 RADIX_NODE_HEAD_LOCK(rnh);
  434                 rnh->rnh_walktree(rnh, in_ifadownkill, &arg);
  435                 RADIX_NODE_HEAD_UNLOCK(rnh);
  436                 ifa->ifa_flags &= ~IFA_ROUTE;           /* XXXlocking? */
  437         }
  438         return 0;
  439 }
  440 
  441 /*
  442  * inet versions of rt functions. These have fib extensions and 
  443  * for now will just reference the _fib variants.
  444  * eventually this order will be reversed,
  445  */
  446 void
  447 in_rtalloc_ign(struct route *ro, u_long ignflags, u_int fibnum)
  448 {
  449         rtalloc_ign_fib(ro, ignflags, fibnum);
  450 }
  451 
  452 int
  453 in_rtrequest( int req,
  454         struct sockaddr *dst,
  455         struct sockaddr *gateway,
  456         struct sockaddr *netmask,
  457         int flags,
  458         struct rtentry **ret_nrt,
  459         u_int fibnum)
  460 {
  461         return (rtrequest_fib(req, dst, gateway, netmask, 
  462             flags, ret_nrt, fibnum));
  463 }
  464 
  465 struct rtentry *
  466 in_rtalloc1(struct sockaddr *dst, int report, u_long ignflags, u_int fibnum)
  467 {
  468         return (rtalloc1_fib(dst, report, ignflags, fibnum));
  469 }
  470 
  471 void
  472 in_rtredirect(struct sockaddr *dst,
  473         struct sockaddr *gateway,
  474         struct sockaddr *netmask,
  475         int flags,
  476         struct sockaddr *src,
  477         u_int fibnum)
  478 {
  479         rtredirect_fib(dst, gateway, netmask, flags, src, fibnum);
  480 }
  481  
  482 void
  483 in_rtalloc(struct route *ro, u_int fibnum)
  484 {
  485         rtalloc_ign_fib(ro, 0UL, fibnum);
  486 }
  487 
  488 #if 0 /* not used */
  489 int      in_rt_getifa(struct rt_addrinfo *, u_int fibnum);
  490 int      in_rtioctl(u_long, caddr_t, u_int);
  491 int      in_rtrequest1(int, struct rt_addrinfo *, struct rtentry **, u_int);
  492 #endif
  493 
  494 

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