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/net/radix_mpath.c

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    1 /*      $KAME: radix_mpath.c,v 1.17 2004/11/08 10:29:39 itojun Exp $    */
    2 
    3 /*
    4  * Copyright (C) 2001 WIDE Project.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of the project nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  * THE AUTHORS DO NOT GUARANTEE THAT THIS SOFTWARE DOES NOT INFRINGE
   31  * ANY OTHERS' INTELLECTUAL PROPERTIES. IN NO EVENT SHALL THE AUTHORS
   32  * BE LIABLE FOR ANY INFRINGEMENT OF ANY OTHERS' INTELLECTUAL
   33  * PROPERTIES.
   34  */
   35 
   36 #include <sys/cdefs.h>
   37 __FBSDID("$FreeBSD: releng/9.0/sys/net/radix_mpath.c 225163 2011-08-25 04:31:20Z qingli $");
   38 
   39 #include "opt_inet.h"
   40 #include "opt_inet6.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/malloc.h>
   45 #include <sys/socket.h>
   46 #include <sys/domain.h>
   47 #include <sys/syslog.h>
   48 #include <net/radix.h>
   49 #include <net/radix_mpath.h>
   50 #include <net/route.h>
   51 #include <net/if.h>
   52 #include <net/if_var.h>
   53 
   54 /*
   55  * give some jitter to hash, to avoid synchronization between routers
   56  */
   57 static uint32_t hashjitter;
   58 
   59 int
   60 rn_mpath_capable(struct radix_node_head *rnh)
   61 {
   62 
   63         return rnh->rnh_multipath;
   64 }
   65 
   66 struct radix_node *
   67 rn_mpath_next(struct radix_node *rn)
   68 {
   69         struct radix_node *next;
   70 
   71         if (!rn->rn_dupedkey)
   72                 return NULL;
   73         next = rn->rn_dupedkey;
   74         if (rn->rn_mask == next->rn_mask)
   75                 return next;
   76         else
   77                 return NULL;
   78 }
   79 
   80 uint32_t
   81 rn_mpath_count(struct radix_node *rn)
   82 {
   83         uint32_t i = 0;
   84         struct rtentry *rt;
   85         
   86         while (rn != NULL) {
   87                 rt = (struct rtentry *)rn;
   88                 i += rt->rt_rmx.rmx_weight;
   89                 rn = rn_mpath_next(rn);
   90         }
   91         return (i);
   92 }
   93 
   94 struct rtentry *
   95 rt_mpath_matchgate(struct rtentry *rt, struct sockaddr *gate)
   96 {
   97         struct radix_node *rn;
   98 
   99         if (!gate || !rt->rt_gateway)
  100                 return NULL;
  101 
  102         /* beyond here, we use rn as the master copy */
  103         rn = (struct radix_node *)rt;
  104         do {
  105                 rt = (struct rtentry *)rn;
  106                 /*
  107                  * we are removing an address alias that has 
  108                  * the same prefix as another address
  109                  * we need to compare the interface address because
  110                  * rt_gateway is a special sockadd_dl structure
  111                  */
  112                 if (rt->rt_gateway->sa_family == AF_LINK) {
  113                         if (!memcmp(rt->rt_ifa->ifa_addr, gate, gate->sa_len))
  114                                 break;
  115                 } else {
  116                         if (rt->rt_gateway->sa_len == gate->sa_len &&
  117                             !memcmp(rt->rt_gateway, gate, gate->sa_len))
  118                                 break;
  119                 }
  120         } while ((rn = rn_mpath_next(rn)) != NULL);
  121 
  122         return (struct rtentry *)rn;
  123 }
  124 
  125 /* 
  126  * go through the chain and unlink "rt" from the list
  127  * the caller will free "rt"
  128  */
  129 int
  130 rt_mpath_deldup(struct rtentry *headrt, struct rtentry *rt)
  131 {
  132         struct radix_node *t, *tt;
  133 
  134         if (!headrt || !rt)
  135             return (0);
  136         t = (struct radix_node *)headrt;
  137         tt = rn_mpath_next(t);
  138         while (tt) {
  139             if (tt == (struct radix_node *)rt) {
  140                 t->rn_dupedkey = tt->rn_dupedkey;
  141                 tt->rn_dupedkey = NULL;
  142                 tt->rn_flags &= ~RNF_ACTIVE;
  143                 tt[1].rn_flags &= ~RNF_ACTIVE;
  144                 return (1);
  145             }
  146             t = tt;
  147             tt = rn_mpath_next((struct radix_node *)t);
  148         }
  149         return (0);
  150 }
  151 
  152 /*
  153  * check if we have the same key/mask/gateway on the table already.
  154  */
  155 int
  156 rt_mpath_conflict(struct radix_node_head *rnh, struct rtentry *rt,
  157     struct sockaddr *netmask)
  158 {
  159         struct radix_node *rn, *rn1;
  160         struct rtentry *rt1;
  161         char *p, *q, *eq;
  162         int same, l, skip;
  163 
  164         rn = (struct radix_node *)rt;
  165         rn1 = rnh->rnh_lookup(rt_key(rt), netmask, rnh);
  166         if (!rn1 || rn1->rn_flags & RNF_ROOT)
  167                 return 0;
  168 
  169         /*
  170          * unlike other functions we have in this file, we have to check
  171          * all key/mask/gateway as rnh_lookup can match less specific entry.
  172          */
  173         rt1 = (struct rtentry *)rn1;
  174 
  175         /* compare key. */
  176         if (rt_key(rt1)->sa_len != rt_key(rt)->sa_len ||
  177             bcmp(rt_key(rt1), rt_key(rt), rt_key(rt1)->sa_len))
  178                 goto different;
  179 
  180         /* key was the same.  compare netmask.  hairy... */
  181         if (rt_mask(rt1) && netmask) {
  182                 skip = rnh->rnh_treetop->rn_offset;
  183                 if (rt_mask(rt1)->sa_len > netmask->sa_len) {
  184                         /*
  185                          * as rt_mask(rt1) is made optimal by radix.c,
  186                          * there must be some 1-bits on rt_mask(rt1)
  187                          * after netmask->sa_len.  therefore, in
  188                          * this case, the entries are different.
  189                          */
  190                         if (rt_mask(rt1)->sa_len > skip)
  191                                 goto different;
  192                         else {
  193                                 /* no bits to compare, i.e. same*/
  194                                 goto maskmatched;
  195                         }
  196                 }
  197 
  198                 l = rt_mask(rt1)->sa_len;
  199                 if (skip > l) {
  200                         /* no bits to compare, i.e. same */
  201                         goto maskmatched;
  202                 }
  203                 p = (char *)rt_mask(rt1);
  204                 q = (char *)netmask;
  205                 if (bcmp(p + skip, q + skip, l - skip))
  206                         goto different;
  207                 /*
  208                  * need to go through all the bit, as netmask is not
  209                  * optimal and can contain trailing 0s
  210                  */
  211                 eq = (char *)netmask + netmask->sa_len;
  212                 q += l;
  213                 same = 1;
  214                 while (eq > q)
  215                         if (*q++) {
  216                                 same = 0;
  217                                 break;
  218                         }
  219                 if (!same)
  220                         goto different;
  221         } else if (!rt_mask(rt1) && !netmask)
  222                 ; /* no mask to compare, i.e. same */
  223         else {
  224                 /* one has mask and the other does not, different */
  225                 goto different;
  226         }
  227 
  228 maskmatched:
  229 
  230         /* key/mask were the same.  compare gateway for all multipaths */
  231         do {
  232                 rt1 = (struct rtentry *)rn1;
  233 
  234                 /* sanity: no use in comparing the same thing */
  235                 if (rn1 == rn)
  236                         continue;
  237         
  238                 if (rt1->rt_gateway->sa_family == AF_LINK) {
  239                         if (rt1->rt_ifa->ifa_addr->sa_len != rt->rt_ifa->ifa_addr->sa_len ||
  240                             bcmp(rt1->rt_ifa->ifa_addr, rt->rt_ifa->ifa_addr, 
  241                             rt1->rt_ifa->ifa_addr->sa_len))
  242                                 continue;
  243                 } else {
  244                         if (rt1->rt_gateway->sa_len != rt->rt_gateway->sa_len ||
  245                             bcmp(rt1->rt_gateway, rt->rt_gateway,
  246                             rt1->rt_gateway->sa_len))
  247                                 continue;
  248                 }
  249 
  250                 /* all key/mask/gateway are the same.  conflicting entry. */
  251                 return EEXIST;
  252         } while ((rn1 = rn_mpath_next(rn1)) != NULL);
  253 
  254 different:
  255         return 0;
  256 }
  257 
  258 void
  259 rtalloc_mpath_fib(struct route *ro, uint32_t hash, u_int fibnum)
  260 {
  261         struct radix_node *rn0, *rn;
  262         u_int32_t n;
  263         struct rtentry *rt;
  264         int64_t weight;
  265 
  266         /*
  267          * XXX we don't attempt to lookup cached route again; what should
  268          * be done for sendto(3) case?
  269          */
  270         if (ro->ro_rt && ro->ro_rt->rt_ifp && (ro->ro_rt->rt_flags & RTF_UP)
  271             && RT_LINK_IS_UP(ro->ro_rt->rt_ifp))
  272                 return;                          
  273         ro->ro_rt = rtalloc1_fib(&ro->ro_dst, 1, 0, fibnum);
  274 
  275         /* if the route does not exist or it is not multipath, don't care */
  276         if (ro->ro_rt == NULL)
  277                 return;
  278         if (rn_mpath_next((struct radix_node *)ro->ro_rt) == NULL) {
  279                 RT_UNLOCK(ro->ro_rt);
  280                 return;
  281         }
  282 
  283         /* beyond here, we use rn as the master copy */
  284         rn0 = rn = (struct radix_node *)ro->ro_rt;
  285         n = rn_mpath_count(rn0);
  286 
  287         /* gw selection by Modulo-N Hash (RFC2991) XXX need improvement? */
  288         hash += hashjitter;
  289         hash %= n;
  290         for (weight = abs((int32_t)hash), rt = ro->ro_rt;
  291              weight >= rt->rt_rmx.rmx_weight && rn; 
  292              weight -= rt->rt_rmx.rmx_weight) {
  293                 
  294                 /* stay within the multipath routes */
  295                 if (rn->rn_dupedkey && rn->rn_mask != rn->rn_dupedkey->rn_mask)
  296                         break;
  297                 rn = rn->rn_dupedkey;
  298                 rt = (struct rtentry *)rn;
  299         }
  300         /* XXX try filling rt_gwroute and avoid unreachable gw  */
  301 
  302         /* gw selection has failed - there must be only zero weight routes */
  303         if (!rn) {
  304                 RT_UNLOCK(ro->ro_rt);
  305                 ro->ro_rt = NULL;
  306                 return;
  307         }
  308         if (ro->ro_rt != rt) {
  309                 RTFREE_LOCKED(ro->ro_rt);
  310                 ro->ro_rt = (struct rtentry *)rn;
  311                 RT_LOCK(ro->ro_rt);
  312                 RT_ADDREF(ro->ro_rt);
  313 
  314         } 
  315         RT_UNLOCK(ro->ro_rt);
  316 }
  317 
  318 extern int      in6_inithead(void **head, int off);
  319 extern int      in_inithead(void **head, int off);
  320 
  321 #ifdef INET
  322 int
  323 rn4_mpath_inithead(void **head, int off)
  324 {
  325         struct radix_node_head *rnh;
  326 
  327         hashjitter = arc4random();
  328         if (in_inithead(head, off) == 1) {
  329                 rnh = (struct radix_node_head *)*head;
  330                 rnh->rnh_multipath = 1;
  331                 return 1;
  332         } else
  333                 return 0;
  334 }
  335 #endif
  336 
  337 #ifdef INET6
  338 int
  339 rn6_mpath_inithead(void **head, int off)
  340 {
  341         struct radix_node_head *rnh;
  342 
  343         hashjitter = arc4random();
  344         if (in6_inithead(head, off) == 1) {
  345                 rnh = (struct radix_node_head *)*head;
  346                 rnh->rnh_multipath = 1;
  347                 return 1;
  348         } else
  349                 return 0;
  350 }
  351 
  352 #endif

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