The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netinet6/in6_rmx.c

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    1 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the project nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      $KAME: in6_rmx.c,v 1.11 2001/07/26 06:53:16 jinmei Exp $
   30  */
   31 
   32 /*-
   33  * Copyright 1994, 1995 Massachusetts Institute of Technology
   34  *
   35  * Permission to use, copy, modify, and distribute this software and
   36  * its documentation for any purpose and without fee is hereby
   37  * granted, provided that both the above copyright notice and this
   38  * permission notice appear in all copies, that both the above
   39  * copyright notice and this permission notice appear in all
   40  * supporting documentation, and that the name of M.I.T. not be used
   41  * in advertising or publicity pertaining to distribution of the
   42  * software without specific, written prior permission.  M.I.T. makes
   43  * no representations about the suitability of this software for any
   44  * purpose.  It is provided "as is" without express or implied
   45  * warranty.
   46  *
   47  * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
   48  * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
   49  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   50  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
   51  * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   52  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   53  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   54  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   55  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   56  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   57  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  */
   61 
   62 /*
   63  * This code does two things necessary for the enhanced TCP metrics to
   64  * function in a useful manner:
   65  *  1) It marks all non-host routes as `cloning', thus ensuring that
   66  *     every actual reference to such a route actually gets turned
   67  *     into a reference to a host route to the specific destination
   68  *     requested.
   69  *  2) When such routes lose all their references, it arranges for them
   70  *     to be deleted in some random collection of circumstances, so that
   71  *     a large quantity of stale routing data is not kept in kernel memory
   72  *     indefinitely.  See in6_rtqtimo() below for the exact mechanism.
   73  */
   74 
   75 #include <sys/cdefs.h>
   76 __FBSDID("$FreeBSD: releng/6.4/sys/netinet6/in6_rmx.c 182649 2008-09-01 22:57:56Z obrien $");
   77 
   78 #include <sys/param.h>
   79 #include <sys/systm.h>
   80 #include <sys/kernel.h>
   81 #include <sys/sysctl.h>
   82 #include <sys/queue.h>
   83 #include <sys/socket.h>
   84 #include <sys/socketvar.h>
   85 #include <sys/mbuf.h>
   86 #include <sys/syslog.h>
   87 #include <sys/callout.h>
   88 
   89 #include <net/if.h>
   90 #include <net/route.h>
   91 #include <netinet/in.h>
   92 #include <netinet/ip_var.h>
   93 #include <netinet/in_var.h>
   94 
   95 #include <netinet/ip6.h>
   96 #include <netinet6/ip6_var.h>
   97 
   98 #include <netinet/icmp6.h>
   99 #include <netinet6/nd6.h>
  100 
  101 #include <netinet/tcp.h>
  102 #include <netinet/tcp_seq.h>
  103 #include <netinet/tcp_timer.h>
  104 #include <netinet/tcp_var.h>
  105 
  106 extern int      in6_inithead(void **head, int off);
  107 
  108 #define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */
  109 
  110 /*
  111  * Do what we need to do when inserting a route.
  112  */
  113 static struct radix_node *
  114 in6_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
  115             struct radix_node *treenodes)
  116 {
  117         struct rtentry *rt = (struct rtentry *)treenodes;
  118         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)rt_key(rt);
  119         struct radix_node *ret;
  120 
  121         if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
  122                 rt->rt_flags |= RTF_MULTICAST;
  123 
  124         /*
  125          * A little bit of help for both IPv6 output and input:
  126          *   For local addresses, we make sure that RTF_LOCAL is set,
  127          *   with the thought that this might one day be used to speed up
  128          *   ip_input().
  129          *
  130          * We also mark routes to multicast addresses as such, because
  131          * it's easy to do and might be useful (but this is much more
  132          * dubious since it's so easy to inspect the address).  (This
  133          * is done above.)
  134          *
  135          * XXX
  136          * should elaborate the code.
  137          */
  138         if (rt->rt_flags & RTF_HOST) {
  139                 if (IN6_ARE_ADDR_EQUAL(&satosin6(rt->rt_ifa->ifa_addr)
  140                                         ->sin6_addr,
  141                                        &sin6->sin6_addr)) {
  142                         rt->rt_flags |= RTF_LOCAL;
  143                 }
  144         }
  145 
  146         if (!rt->rt_rmx.rmx_mtu && rt->rt_ifp)
  147                 rt->rt_rmx.rmx_mtu = IN6_LINKMTU(rt->rt_ifp);
  148 
  149         ret = rn_addroute(v_arg, n_arg, head, treenodes);
  150         if (ret == NULL && rt->rt_flags & RTF_HOST) {
  151                 struct rtentry *rt2;
  152                 /*
  153                  * We are trying to add a host route, but can't.
  154                  * Find out if it is because of an
  155                  * ARP entry and delete it if so.
  156                  */
  157                 rt2 = rtalloc1((struct sockaddr *)sin6, 0, RTF_CLONING);
  158                 if (rt2) {
  159                         if (rt2->rt_flags & RTF_LLINFO &&
  160                                 rt2->rt_flags & RTF_HOST &&
  161                                 rt2->rt_gateway &&
  162                                 rt2->rt_gateway->sa_family == AF_LINK) {
  163                                 rtexpunge(rt2);
  164                                 RTFREE_LOCKED(rt2);
  165                                 ret = rn_addroute(v_arg, n_arg, head,
  166                                         treenodes);
  167                         } else
  168                                 RTFREE_LOCKED(rt2);
  169                 }
  170         } else if (ret == NULL && rt->rt_flags & RTF_CLONING) {
  171                 struct rtentry *rt2;
  172                 /*
  173                  * We are trying to add a net route, but can't.
  174                  * The following case should be allowed, so we'll make a
  175                  * special check for this:
  176                  *      Two IPv6 addresses with the same prefix is assigned
  177                  *      to a single interrface.
  178                  *      # ifconfig if0 inet6 3ffe:0501::1 prefix 64 alias (*1)
  179                  *      # ifconfig if0 inet6 3ffe:0501::2 prefix 64 alias (*2)
  180                  *      In this case, (*1) and (*2) want to add the same
  181                  *      net route entry, 3ffe:0501:: -> if0.
  182                  *      This case should not raise an error.
  183                  */
  184                 rt2 = rtalloc1((struct sockaddr *)sin6, 0, RTF_CLONING);
  185                 if (rt2) {
  186                         if ((rt2->rt_flags & (RTF_CLONING|RTF_HOST|RTF_GATEWAY))
  187                                         == RTF_CLONING
  188                          && rt2->rt_gateway
  189                          && rt2->rt_gateway->sa_family == AF_LINK
  190                          && rt2->rt_ifp == rt->rt_ifp) {
  191                                 ret = rt2->rt_nodes;
  192                         }
  193                         RTFREE_LOCKED(rt2);
  194                 }
  195         }
  196         return ret;
  197 }
  198 
  199 /*
  200  * This code is the inverse of in6_clsroute: on first reference, if we
  201  * were managing the route, stop doing so and set the expiration timer
  202  * back off again.
  203  */
  204 static struct radix_node *
  205 in6_matroute(void *v_arg, struct radix_node_head *head)
  206 {
  207         struct radix_node *rn = rn_match(v_arg, head);
  208         struct rtentry *rt = (struct rtentry *)rn;
  209 
  210         if (rt && rt->rt_refcnt == 0) { /* this is first reference */
  211                 if (rt->rt_flags & RTPRF_OURS) {
  212                         rt->rt_flags &= ~RTPRF_OURS;
  213                         rt->rt_rmx.rmx_expire = 0;
  214                 }
  215         }
  216         return rn;
  217 }
  218 
  219 SYSCTL_DECL(_net_inet6_ip6);
  220 
  221 static int rtq_reallyold = 60*60;
  222         /* one hour is ``really old'' */
  223 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTEXPIRE, rtexpire,
  224         CTLFLAG_RW, &rtq_reallyold , 0, "");
  225 
  226 static int rtq_minreallyold = 10;
  227         /* never automatically crank down to less */
  228 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMINEXPIRE, rtminexpire,
  229         CTLFLAG_RW, &rtq_minreallyold , 0, "");
  230 
  231 static int rtq_toomany = 128;
  232         /* 128 cached routes is ``too many'' */
  233 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMAXCACHE, rtmaxcache,
  234         CTLFLAG_RW, &rtq_toomany , 0, "");
  235 
  236 
  237 /*
  238  * On last reference drop, mark the route as belong to us so that it can be
  239  * timed out.
  240  */
  241 static void
  242 in6_clsroute(struct radix_node *rn, struct radix_node_head *head)
  243 {
  244         struct rtentry *rt = (struct rtentry *)rn;
  245 
  246         RT_LOCK_ASSERT(rt);
  247 
  248         if (!(rt->rt_flags & RTF_UP))
  249                 return;         /* prophylactic measures */
  250 
  251         if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
  252                 return;
  253 
  254         if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED)
  255                 return;
  256 
  257         /*
  258          * As requested by David Greenman:
  259          * If rtq_reallyold is 0, just delete the route without
  260          * waiting for a timeout cycle to kill it.
  261          */
  262         if (rtq_reallyold != 0) {
  263                 rt->rt_flags |= RTPRF_OURS;
  264                 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold;
  265         } else {
  266                 rtexpunge(rt);
  267         }
  268 }
  269 
  270 struct rtqk_arg {
  271         struct radix_node_head *rnh;
  272         int mode;
  273         int updating;
  274         int draining;
  275         int killed;
  276         int found;
  277         time_t nextstop;
  278 };
  279 
  280 /*
  281  * Get rid of old routes.  When draining, this deletes everything, even when
  282  * the timeout is not expired yet.  When updating, this makes sure that
  283  * nothing has a timeout longer than the current value of rtq_reallyold.
  284  */
  285 static int
  286 in6_rtqkill(struct radix_node *rn, void *rock)
  287 {
  288         struct rtqk_arg *ap = rock;
  289         struct rtentry *rt = (struct rtentry *)rn;
  290         int err;
  291 
  292         if (rt->rt_flags & RTPRF_OURS) {
  293                 ap->found++;
  294 
  295                 if (ap->draining || rt->rt_rmx.rmx_expire <= time_second) {
  296                         if (rt->rt_refcnt > 0)
  297                                 panic("rtqkill route really not free");
  298 
  299                         err = rtrequest(RTM_DELETE,
  300                                         (struct sockaddr *)rt_key(rt),
  301                                         rt->rt_gateway, rt_mask(rt),
  302                                         rt->rt_flags, 0);
  303                         if (err) {
  304                                 log(LOG_WARNING, "in6_rtqkill: error %d", err);
  305                         } else {
  306                                 ap->killed++;
  307                         }
  308                 } else {
  309                         if (ap->updating
  310                            && (rt->rt_rmx.rmx_expire - time_second
  311                                > rtq_reallyold)) {
  312                                 rt->rt_rmx.rmx_expire = time_second
  313                                         + rtq_reallyold;
  314                         }
  315                         ap->nextstop = lmin(ap->nextstop,
  316                                             rt->rt_rmx.rmx_expire);
  317                 }
  318         }
  319 
  320         return 0;
  321 }
  322 
  323 #define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
  324 static int rtq_timeout = RTQ_TIMEOUT;
  325 static struct callout rtq_timer;
  326 
  327 static void
  328 in6_rtqtimo(void *rock)
  329 {
  330         struct radix_node_head *rnh = rock;
  331         struct rtqk_arg arg;
  332         struct timeval atv;
  333         static time_t last_adjusted_timeout = 0;
  334 
  335         arg.found = arg.killed = 0;
  336         arg.rnh = rnh;
  337         arg.nextstop = time_second + rtq_timeout;
  338         arg.draining = arg.updating = 0;
  339         RADIX_NODE_HEAD_LOCK(rnh);
  340         rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  341         RADIX_NODE_HEAD_UNLOCK(rnh);
  342 
  343         /*
  344          * Attempt to be somewhat dynamic about this:
  345          * If there are ``too many'' routes sitting around taking up space,
  346          * then crank down the timeout, and see if we can't make some more
  347          * go away.  However, we make sure that we will never adjust more
  348          * than once in rtq_timeout seconds, to keep from cranking down too
  349          * hard.
  350          */
  351         if ((arg.found - arg.killed > rtq_toomany)
  352            && (time_second - last_adjusted_timeout >= rtq_timeout)
  353            && rtq_reallyold > rtq_minreallyold) {
  354                 rtq_reallyold = 2*rtq_reallyold / 3;
  355                 if (rtq_reallyold < rtq_minreallyold) {
  356                         rtq_reallyold = rtq_minreallyold;
  357                 }
  358 
  359                 last_adjusted_timeout = time_second;
  360 #ifdef DIAGNOSTIC
  361                 log(LOG_DEBUG, "in6_rtqtimo: adjusted rtq_reallyold to %d",
  362                     rtq_reallyold);
  363 #endif
  364                 arg.found = arg.killed = 0;
  365                 arg.updating = 1;
  366                 RADIX_NODE_HEAD_LOCK(rnh);
  367                 rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  368                 RADIX_NODE_HEAD_UNLOCK(rnh);
  369         }
  370 
  371         atv.tv_usec = 0;
  372         atv.tv_sec = arg.nextstop - time_second;
  373         callout_reset(&rtq_timer, tvtohz(&atv), in6_rtqtimo, rock);
  374 }
  375 
  376 /*
  377  * Age old PMTUs.
  378  */
  379 struct mtuex_arg {
  380         struct radix_node_head *rnh;
  381         time_t nextstop;
  382 };
  383 static struct callout rtq_mtutimer;
  384 
  385 static int
  386 in6_mtuexpire(struct radix_node *rn, void *rock)
  387 {
  388         struct rtentry *rt = (struct rtentry *)rn;
  389         struct mtuex_arg *ap = rock;
  390 
  391         /* sanity */
  392         if (!rt)
  393                 panic("rt == NULL in in6_mtuexpire");
  394 
  395         if (rt->rt_rmx.rmx_expire && !(rt->rt_flags & RTF_PROBEMTU)) {
  396                 if (rt->rt_rmx.rmx_expire <= time_second) {
  397                         rt->rt_flags |= RTF_PROBEMTU;
  398                 } else {
  399                         ap->nextstop = lmin(ap->nextstop,
  400                                         rt->rt_rmx.rmx_expire);
  401                 }
  402         }
  403 
  404         return 0;
  405 }
  406 
  407 #define MTUTIMO_DEFAULT (60*1)
  408 
  409 static void
  410 in6_mtutimo(void *rock)
  411 {
  412         struct radix_node_head *rnh = rock;
  413         struct mtuex_arg arg;
  414         struct timeval atv;
  415 
  416         arg.rnh = rnh;
  417         arg.nextstop = time_second + MTUTIMO_DEFAULT;
  418         RADIX_NODE_HEAD_LOCK(rnh);
  419         rnh->rnh_walktree(rnh, in6_mtuexpire, &arg);
  420         RADIX_NODE_HEAD_UNLOCK(rnh);
  421 
  422         atv.tv_usec = 0;
  423         atv.tv_sec = arg.nextstop - time_second;
  424         if (atv.tv_sec < 0) {
  425                 printf("invalid mtu expiration time on routing table\n");
  426                 arg.nextstop = 30;      /* last resort */
  427         }
  428         callout_reset(&rtq_mtutimer, tvtohz(&atv), in6_mtutimo, rock);
  429 }
  430 
  431 #if 0
  432 void
  433 in6_rtqdrain()
  434 {
  435         struct radix_node_head *rnh = rt_tables[AF_INET6];
  436         struct rtqk_arg arg;
  437 
  438         arg.found = arg.killed = 0;
  439         arg.rnh = rnh;
  440         arg.nextstop = 0;
  441         arg.draining = 1;
  442         arg.updating = 0;
  443         RADIX_NODE_HEAD_LOCK(rnh);
  444         rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  445         RADIX_NODE_HEAD_UNLOCK(rnh);
  446 }
  447 #endif
  448 
  449 /*
  450  * Initialize our routing tree.
  451  */
  452 int
  453 in6_inithead(void **head, int off)
  454 {
  455         struct radix_node_head *rnh;
  456 
  457         if (!rn_inithead(head, off))
  458                 return 0;
  459 
  460         if (head != (void **)&rt_tables[AF_INET6]) /* BOGUS! */
  461                 return 1;       /* only do this for the real routing table */
  462 
  463         rnh = *head;
  464         rnh->rnh_addaddr = in6_addroute;
  465         rnh->rnh_matchaddr = in6_matroute;
  466         rnh->rnh_close = in6_clsroute;
  467         callout_init(&rtq_timer, CALLOUT_MPSAFE);
  468         in6_rtqtimo(rnh);       /* kick off timeout first time */
  469         callout_init(&rtq_mtutimer, CALLOUT_MPSAFE);
  470         in6_mtutimo(rnh);       /* kick off timeout first time */
  471         return 1;
  472 }

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