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 /*      $FreeBSD: releng/6.2/sys/netinet6/in6_rmx.c 139826 2005-01-07 02:30:35Z imp $   */
    2 /*      $KAME: in6_rmx.c,v 1.11 2001/07/26 06:53:16 jinmei Exp $        */
    3 
    4 /*-
    5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    6  * All rights reserved.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. Neither the name of the project nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  */
   32 
   33 /*-
   34  * Copyright 1994, 1995 Massachusetts Institute of Technology
   35  *
   36  * Permission to use, copy, modify, and distribute this software and
   37  * its documentation for any purpose and without fee is hereby
   38  * granted, provided that both the above copyright notice and this
   39  * permission notice appear in all copies, that both the above
   40  * copyright notice and this permission notice appear in all
   41  * supporting documentation, and that the name of M.I.T. not be used
   42  * in advertising or publicity pertaining to distribution of the
   43  * software without specific, written prior permission.  M.I.T. makes
   44  * no representations about the suitability of this software for any
   45  * purpose.  It is provided "as is" without express or implied
   46  * warranty.
   47  *
   48  * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
   49  * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
   50  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   51  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
   52  * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   53  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   54  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   55  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   56  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   57  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   58  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   59  * SUCH DAMAGE.
   60  *
   61  */
   62 
   63 /*
   64  * This code does two things necessary for the enhanced TCP metrics to
   65  * function in a useful manner:
   66  *  1) It marks all non-host routes as `cloning', thus ensuring that
   67  *     every actual reference to such a route actually gets turned
   68  *     into a reference to a host route to the specific destination
   69  *     requested.
   70  *  2) When such routes lose all their references, it arranges for them
   71  *     to be deleted in some random collection of circumstances, so that
   72  *     a large quantity of stale routing data is not kept in kernel memory
   73  *     indefinitely.  See in6_rtqtimo() below for the exact mechanism.
   74  */
   75 
   76 #include <sys/param.h>
   77 #include <sys/systm.h>
   78 #include <sys/kernel.h>
   79 #include <sys/sysctl.h>
   80 #include <sys/queue.h>
   81 #include <sys/socket.h>
   82 #include <sys/socketvar.h>
   83 #include <sys/mbuf.h>
   84 #include <sys/syslog.h>
   85 #include <sys/callout.h>
   86 
   87 #include <net/if.h>
   88 #include <net/route.h>
   89 #include <netinet/in.h>
   90 #include <netinet/ip_var.h>
   91 #include <netinet/in_var.h>
   92 
   93 #include <netinet/ip6.h>
   94 #include <netinet6/ip6_var.h>
   95 
   96 #include <netinet/icmp6.h>
   97 #include <netinet6/nd6.h>
   98 
   99 #include <netinet/tcp.h>
  100 #include <netinet/tcp_seq.h>
  101 #include <netinet/tcp_timer.h>
  102 #include <netinet/tcp_var.h>
  103 
  104 extern int      in6_inithead __P((void **head, int off));
  105 
  106 #define RTPRF_OURS              RTF_PROTO3      /* set on routes we manage */
  107 
  108 /*
  109  * Do what we need to do when inserting a route.
  110  */
  111 static struct radix_node *
  112 in6_addroute(void *v_arg, void *n_arg, struct radix_node_head *head,
  113             struct radix_node *treenodes)
  114 {
  115         struct rtentry *rt = (struct rtentry *)treenodes;
  116         struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)rt_key(rt);
  117         struct radix_node *ret;
  118 
  119         if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
  120                 rt->rt_flags |= RTF_MULTICAST;
  121 
  122         /*
  123          * A little bit of help for both IPv6 output and input:
  124          *   For local addresses, we make sure that RTF_LOCAL is set,
  125          *   with the thought that this might one day be used to speed up
  126          *   ip_input().
  127          *
  128          * We also mark routes to multicast addresses as such, because
  129          * it's easy to do and might be useful (but this is much more
  130          * dubious since it's so easy to inspect the address).  (This
  131          * is done above.)
  132          *
  133          * XXX
  134          * should elaborate the code.
  135          */
  136         if (rt->rt_flags & RTF_HOST) {
  137                 if (IN6_ARE_ADDR_EQUAL(&satosin6(rt->rt_ifa->ifa_addr)
  138                                         ->sin6_addr,
  139                                        &sin6->sin6_addr)) {
  140                         rt->rt_flags |= RTF_LOCAL;
  141                 }
  142         }
  143 
  144         if (!rt->rt_rmx.rmx_mtu && rt->rt_ifp)
  145                 rt->rt_rmx.rmx_mtu = IN6_LINKMTU(rt->rt_ifp);
  146 
  147         ret = rn_addroute(v_arg, n_arg, head, treenodes);
  148         if (ret == NULL && rt->rt_flags & RTF_HOST) {
  149                 struct rtentry *rt2;
  150                 /*
  151                  * We are trying to add a host route, but can't.
  152                  * Find out if it is because of an
  153                  * ARP entry and delete it if so.
  154                  */
  155                 rt2 = rtalloc1((struct sockaddr *)sin6, 0, RTF_CLONING);
  156                 if (rt2) {
  157                         if (rt2->rt_flags & RTF_LLINFO &&
  158                                 rt2->rt_flags & RTF_HOST &&
  159                                 rt2->rt_gateway &&
  160                                 rt2->rt_gateway->sa_family == AF_LINK) {
  161                                 rtexpunge(rt2);
  162                                 RTFREE_LOCKED(rt2);
  163                                 ret = rn_addroute(v_arg, n_arg, head,
  164                                         treenodes);
  165                         } else
  166                                 RTFREE_LOCKED(rt2);
  167                 }
  168         } else if (ret == NULL && rt->rt_flags & RTF_CLONING) {
  169                 struct rtentry *rt2;
  170                 /*
  171                  * We are trying to add a net route, but can't.
  172                  * The following case should be allowed, so we'll make a
  173                  * special check for this:
  174                  *      Two IPv6 addresses with the same prefix is assigned
  175                  *      to a single interrface.
  176                  *      # ifconfig if0 inet6 3ffe:0501::1 prefix 64 alias (*1)
  177                  *      # ifconfig if0 inet6 3ffe:0501::2 prefix 64 alias (*2)
  178                  *      In this case, (*1) and (*2) want to add the same
  179                  *      net route entry, 3ffe:0501:: -> if0.
  180                  *      This case should not raise an error.
  181                  */
  182                 rt2 = rtalloc1((struct sockaddr *)sin6, 0, RTF_CLONING);
  183                 if (rt2) {
  184                         if ((rt2->rt_flags & (RTF_CLONING|RTF_HOST|RTF_GATEWAY))
  185                                         == RTF_CLONING
  186                          && rt2->rt_gateway
  187                          && rt2->rt_gateway->sa_family == AF_LINK
  188                          && rt2->rt_ifp == rt->rt_ifp) {
  189                                 ret = rt2->rt_nodes;
  190                         }
  191                         RTFREE_LOCKED(rt2);
  192                 }
  193         }
  194         return ret;
  195 }
  196 
  197 /*
  198  * This code is the inverse of in6_clsroute: on first reference, if we
  199  * were managing the route, stop doing so and set the expiration timer
  200  * back off again.
  201  */
  202 static struct radix_node *
  203 in6_matroute(void *v_arg, struct radix_node_head *head)
  204 {
  205         struct radix_node *rn = rn_match(v_arg, head);
  206         struct rtentry *rt = (struct rtentry *)rn;
  207 
  208         if (rt && rt->rt_refcnt == 0) { /* this is first reference */
  209                 if (rt->rt_flags & RTPRF_OURS) {
  210                         rt->rt_flags &= ~RTPRF_OURS;
  211                         rt->rt_rmx.rmx_expire = 0;
  212                 }
  213         }
  214         return rn;
  215 }
  216 
  217 SYSCTL_DECL(_net_inet6_ip6);
  218 
  219 static int rtq_reallyold = 60*60;
  220         /* one hour is ``really old'' */
  221 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTEXPIRE, rtexpire,
  222         CTLFLAG_RW, &rtq_reallyold , 0, "");
  223 
  224 static int rtq_minreallyold = 10;
  225         /* never automatically crank down to less */
  226 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMINEXPIRE, rtminexpire,
  227         CTLFLAG_RW, &rtq_minreallyold , 0, "");
  228 
  229 static int rtq_toomany = 128;
  230         /* 128 cached routes is ``too many'' */
  231 SYSCTL_INT(_net_inet6_ip6, IPV6CTL_RTMAXCACHE, rtmaxcache,
  232         CTLFLAG_RW, &rtq_toomany , 0, "");
  233 
  234 
  235 /*
  236  * On last reference drop, mark the route as belong to us so that it can be
  237  * timed out.
  238  */
  239 static void
  240 in6_clsroute(struct radix_node *rn, struct radix_node_head *head)
  241 {
  242         struct rtentry *rt = (struct rtentry *)rn;
  243 
  244         RT_LOCK_ASSERT(rt);
  245 
  246         if (!(rt->rt_flags & RTF_UP))
  247                 return;         /* prophylactic measures */
  248 
  249         if ((rt->rt_flags & (RTF_LLINFO | RTF_HOST)) != RTF_HOST)
  250                 return;
  251 
  252         if ((rt->rt_flags & (RTF_WASCLONED | RTPRF_OURS)) != RTF_WASCLONED)
  253                 return;
  254 
  255         /*
  256          * As requested by David Greenman:
  257          * If rtq_reallyold is 0, just delete the route without
  258          * waiting for a timeout cycle to kill it.
  259          */
  260         if (rtq_reallyold != 0) {
  261                 rt->rt_flags |= RTPRF_OURS;
  262                 rt->rt_rmx.rmx_expire = time_second + rtq_reallyold;
  263         } else {
  264                 rtexpunge(rt);
  265         }
  266 }
  267 
  268 struct rtqk_arg {
  269         struct radix_node_head *rnh;
  270         int mode;
  271         int updating;
  272         int draining;
  273         int killed;
  274         int found;
  275         time_t nextstop;
  276 };
  277 
  278 /*
  279  * Get rid of old routes.  When draining, this deletes everything, even when
  280  * the timeout is not expired yet.  When updating, this makes sure that
  281  * nothing has a timeout longer than the current value of rtq_reallyold.
  282  */
  283 static int
  284 in6_rtqkill(struct radix_node *rn, void *rock)
  285 {
  286         struct rtqk_arg *ap = rock;
  287         struct rtentry *rt = (struct rtentry *)rn;
  288         int err;
  289 
  290         if (rt->rt_flags & RTPRF_OURS) {
  291                 ap->found++;
  292 
  293                 if (ap->draining || rt->rt_rmx.rmx_expire <= time_second) {
  294                         if (rt->rt_refcnt > 0)
  295                                 panic("rtqkill route really not free");
  296 
  297                         err = rtrequest(RTM_DELETE,
  298                                         (struct sockaddr *)rt_key(rt),
  299                                         rt->rt_gateway, rt_mask(rt),
  300                                         rt->rt_flags, 0);
  301                         if (err) {
  302                                 log(LOG_WARNING, "in6_rtqkill: error %d", err);
  303                         } else {
  304                                 ap->killed++;
  305                         }
  306                 } else {
  307                         if (ap->updating
  308                            && (rt->rt_rmx.rmx_expire - time_second
  309                                > rtq_reallyold)) {
  310                                 rt->rt_rmx.rmx_expire = time_second
  311                                         + rtq_reallyold;
  312                         }
  313                         ap->nextstop = lmin(ap->nextstop,
  314                                             rt->rt_rmx.rmx_expire);
  315                 }
  316         }
  317 
  318         return 0;
  319 }
  320 
  321 #define RTQ_TIMEOUT     60*10   /* run no less than once every ten minutes */
  322 static int rtq_timeout = RTQ_TIMEOUT;
  323 static struct callout rtq_timer;
  324 
  325 static void
  326 in6_rtqtimo(void *rock)
  327 {
  328         struct radix_node_head *rnh = rock;
  329         struct rtqk_arg arg;
  330         struct timeval atv;
  331         static time_t last_adjusted_timeout = 0;
  332 
  333         arg.found = arg.killed = 0;
  334         arg.rnh = rnh;
  335         arg.nextstop = time_second + rtq_timeout;
  336         arg.draining = arg.updating = 0;
  337         RADIX_NODE_HEAD_LOCK(rnh);
  338         rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  339         RADIX_NODE_HEAD_UNLOCK(rnh);
  340 
  341         /*
  342          * Attempt to be somewhat dynamic about this:
  343          * If there are ``too many'' routes sitting around taking up space,
  344          * then crank down the timeout, and see if we can't make some more
  345          * go away.  However, we make sure that we will never adjust more
  346          * than once in rtq_timeout seconds, to keep from cranking down too
  347          * hard.
  348          */
  349         if ((arg.found - arg.killed > rtq_toomany)
  350            && (time_second - last_adjusted_timeout >= rtq_timeout)
  351            && rtq_reallyold > rtq_minreallyold) {
  352                 rtq_reallyold = 2*rtq_reallyold / 3;
  353                 if (rtq_reallyold < rtq_minreallyold) {
  354                         rtq_reallyold = rtq_minreallyold;
  355                 }
  356 
  357                 last_adjusted_timeout = time_second;
  358 #ifdef DIAGNOSTIC
  359                 log(LOG_DEBUG, "in6_rtqtimo: adjusted rtq_reallyold to %d",
  360                     rtq_reallyold);
  361 #endif
  362                 arg.found = arg.killed = 0;
  363                 arg.updating = 1;
  364                 RADIX_NODE_HEAD_LOCK(rnh);
  365                 rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  366                 RADIX_NODE_HEAD_UNLOCK(rnh);
  367         }
  368 
  369         atv.tv_usec = 0;
  370         atv.tv_sec = arg.nextstop - time_second;
  371         callout_reset(&rtq_timer, tvtohz(&atv), in6_rtqtimo, rock);
  372 }
  373 
  374 /*
  375  * Age old PMTUs.
  376  */
  377 struct mtuex_arg {
  378         struct radix_node_head *rnh;
  379         time_t nextstop;
  380 };
  381 static struct callout rtq_mtutimer;
  382 
  383 static int
  384 in6_mtuexpire(struct radix_node *rn, void *rock)
  385 {
  386         struct rtentry *rt = (struct rtentry *)rn;
  387         struct mtuex_arg *ap = rock;
  388 
  389         /* sanity */
  390         if (!rt)
  391                 panic("rt == NULL in in6_mtuexpire");
  392 
  393         if (rt->rt_rmx.rmx_expire && !(rt->rt_flags & RTF_PROBEMTU)) {
  394                 if (rt->rt_rmx.rmx_expire <= time_second) {
  395                         rt->rt_flags |= RTF_PROBEMTU;
  396                 } else {
  397                         ap->nextstop = lmin(ap->nextstop,
  398                                         rt->rt_rmx.rmx_expire);
  399                 }
  400         }
  401 
  402         return 0;
  403 }
  404 
  405 #define MTUTIMO_DEFAULT (60*1)
  406 
  407 static void
  408 in6_mtutimo(void *rock)
  409 {
  410         struct radix_node_head *rnh = rock;
  411         struct mtuex_arg arg;
  412         struct timeval atv;
  413 
  414         arg.rnh = rnh;
  415         arg.nextstop = time_second + MTUTIMO_DEFAULT;
  416         RADIX_NODE_HEAD_LOCK(rnh);
  417         rnh->rnh_walktree(rnh, in6_mtuexpire, &arg);
  418         RADIX_NODE_HEAD_UNLOCK(rnh);
  419 
  420         atv.tv_usec = 0;
  421         atv.tv_sec = arg.nextstop - time_second;
  422         if (atv.tv_sec < 0) {
  423                 printf("invalid mtu expiration time on routing table\n");
  424                 arg.nextstop = 30;      /* last resort */
  425         }
  426         callout_reset(&rtq_mtutimer, tvtohz(&atv), in6_mtutimo, rock);
  427 }
  428 
  429 #if 0
  430 void
  431 in6_rtqdrain()
  432 {
  433         struct radix_node_head *rnh = rt_tables[AF_INET6];
  434         struct rtqk_arg arg;
  435 
  436         arg.found = arg.killed = 0;
  437         arg.rnh = rnh;
  438         arg.nextstop = 0;
  439         arg.draining = 1;
  440         arg.updating = 0;
  441         RADIX_NODE_HEAD_LOCK(rnh);
  442         rnh->rnh_walktree(rnh, in6_rtqkill, &arg);
  443         RADIX_NODE_HEAD_UNLOCK(rnh);
  444 }
  445 #endif
  446 
  447 /*
  448  * Initialize our routing tree.
  449  */
  450 int
  451 in6_inithead(void **head, int off)
  452 {
  453         struct radix_node_head *rnh;
  454 
  455         if (!rn_inithead(head, off))
  456                 return 0;
  457 
  458         if (head != (void **)&rt_tables[AF_INET6]) /* BOGUS! */
  459                 return 1;       /* only do this for the real routing table */
  460 
  461         rnh = *head;
  462         rnh->rnh_addaddr = in6_addroute;
  463         rnh->rnh_matchaddr = in6_matroute;
  464         rnh->rnh_close = in6_clsroute;
  465         callout_init(&rtq_timer, CALLOUT_MPSAFE);
  466         in6_rtqtimo(rnh);       /* kick off timeout first time */
  467         callout_init(&rtq_mtutimer, CALLOUT_MPSAFE);
  468         in6_mtutimo(rnh);       /* kick off timeout first time */
  469         return 1;
  470 }

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