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/10.1/sys/net/radix_mpath.c 265711 2014-05-08 20:41:39Z melifaro $");
   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_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                 }
  116 
  117                 /*
  118                  * Check for other options:
  119                  * 1) Routes with 'real' IPv4/IPv6 gateway
  120                  * 2) Loopback host routes (another AF_LINK/sockadd_dl check)
  121                  * */
  122                 if (rt->rt_gateway->sa_len == gate->sa_len &&
  123                     !memcmp(rt->rt_gateway, gate, gate->sa_len))
  124                         break;
  125         } while ((rn = rn_mpath_next(rn)) != NULL);
  126 
  127         return (struct rtentry *)rn;
  128 }
  129 
  130 /* 
  131  * go through the chain and unlink "rt" from the list
  132  * the caller will free "rt"
  133  */
  134 int
  135 rt_mpath_deldup(struct rtentry *headrt, struct rtentry *rt)
  136 {
  137         struct radix_node *t, *tt;
  138 
  139         if (!headrt || !rt)
  140             return (0);
  141         t = (struct radix_node *)headrt;
  142         tt = rn_mpath_next(t);
  143         while (tt) {
  144             if (tt == (struct radix_node *)rt) {
  145                 t->rn_dupedkey = tt->rn_dupedkey;
  146                 tt->rn_dupedkey = NULL;
  147                 tt->rn_flags &= ~RNF_ACTIVE;
  148                 tt[1].rn_flags &= ~RNF_ACTIVE;
  149                 return (1);
  150             }
  151             t = tt;
  152             tt = rn_mpath_next((struct radix_node *)t);
  153         }
  154         return (0);
  155 }
  156 
  157 /*
  158  * check if we have the same key/mask/gateway on the table already.
  159  * Assume @rt rt_key host bits are cleared according to @netmask
  160  */
  161 int
  162 rt_mpath_conflict(struct radix_node_head *rnh, struct rtentry *rt,
  163     struct sockaddr *netmask)
  164 {
  165         struct radix_node *rn, *rn1;
  166         struct rtentry *rt1;
  167 
  168         rn = (struct radix_node *)rt;
  169         rn1 = rnh->rnh_lookup(rt_key(rt), netmask, rnh);
  170         if (!rn1 || rn1->rn_flags & RNF_ROOT)
  171                 return (0);
  172 
  173         /* key/mask are the same. compare gateway for all multipaths */
  174         do {
  175                 rt1 = (struct rtentry *)rn1;
  176 
  177                 /* sanity: no use in comparing the same thing */
  178                 if (rn1 == rn)
  179                         continue;
  180         
  181                 if (rt1->rt_gateway->sa_family == AF_LINK) {
  182                         if (rt1->rt_ifa->ifa_addr->sa_len != rt->rt_ifa->ifa_addr->sa_len ||
  183                             bcmp(rt1->rt_ifa->ifa_addr, rt->rt_ifa->ifa_addr, 
  184                             rt1->rt_ifa->ifa_addr->sa_len))
  185                                 continue;
  186                 } else {
  187                         if (rt1->rt_gateway->sa_len != rt->rt_gateway->sa_len ||
  188                             bcmp(rt1->rt_gateway, rt->rt_gateway,
  189                             rt1->rt_gateway->sa_len))
  190                                 continue;
  191                 }
  192 
  193                 /* all key/mask/gateway are the same.  conflicting entry. */
  194                 return (EEXIST);
  195         } while ((rn1 = rn_mpath_next(rn1)) != NULL);
  196 
  197         return (0);
  198 }
  199 
  200 void
  201 rtalloc_mpath_fib(struct route *ro, uint32_t hash, u_int fibnum)
  202 {
  203         struct radix_node *rn0, *rn;
  204         u_int32_t n;
  205         struct rtentry *rt;
  206         int64_t weight;
  207 
  208         /*
  209          * XXX we don't attempt to lookup cached route again; what should
  210          * be done for sendto(3) case?
  211          */
  212         if (ro->ro_rt && ro->ro_rt->rt_ifp && (ro->ro_rt->rt_flags & RTF_UP)
  213             && RT_LINK_IS_UP(ro->ro_rt->rt_ifp))
  214                 return;                          
  215         ro->ro_rt = rtalloc1_fib(&ro->ro_dst, 1, 0, fibnum);
  216 
  217         /* if the route does not exist or it is not multipath, don't care */
  218         if (ro->ro_rt == NULL)
  219                 return;
  220         if (rn_mpath_next((struct radix_node *)ro->ro_rt) == NULL) {
  221                 RT_UNLOCK(ro->ro_rt);
  222                 return;
  223         }
  224 
  225         /* beyond here, we use rn as the master copy */
  226         rn0 = rn = (struct radix_node *)ro->ro_rt;
  227         n = rn_mpath_count(rn0);
  228 
  229         /* gw selection by Modulo-N Hash (RFC2991) XXX need improvement? */
  230         hash += hashjitter;
  231         hash %= n;
  232         for (weight = abs((int32_t)hash), rt = ro->ro_rt;
  233              weight >= rt->rt_weight && rn; 
  234              weight -= rt->rt_weight) {
  235                 
  236                 /* stay within the multipath routes */
  237                 if (rn->rn_dupedkey && rn->rn_mask != rn->rn_dupedkey->rn_mask)
  238                         break;
  239                 rn = rn->rn_dupedkey;
  240                 rt = (struct rtentry *)rn;
  241         }
  242         /* XXX try filling rt_gwroute and avoid unreachable gw  */
  243 
  244         /* gw selection has failed - there must be only zero weight routes */
  245         if (!rn) {
  246                 RT_UNLOCK(ro->ro_rt);
  247                 ro->ro_rt = NULL;
  248                 return;
  249         }
  250         if (ro->ro_rt != rt) {
  251                 RTFREE_LOCKED(ro->ro_rt);
  252                 ro->ro_rt = (struct rtentry *)rn;
  253                 RT_LOCK(ro->ro_rt);
  254                 RT_ADDREF(ro->ro_rt);
  255 
  256         } 
  257         RT_UNLOCK(ro->ro_rt);
  258 }
  259 
  260 extern int      in6_inithead(void **head, int off);
  261 extern int      in_inithead(void **head, int off);
  262 
  263 #ifdef INET
  264 int
  265 rn4_mpath_inithead(void **head, int off)
  266 {
  267         struct radix_node_head *rnh;
  268 
  269         hashjitter = arc4random();
  270         if (in_inithead(head, off) == 1) {
  271                 rnh = (struct radix_node_head *)*head;
  272                 rnh->rnh_multipath = 1;
  273                 return 1;
  274         } else
  275                 return 0;
  276 }
  277 #endif
  278 
  279 #ifdef INET6
  280 int
  281 rn6_mpath_inithead(void **head, int off)
  282 {
  283         struct radix_node_head *rnh;
  284 
  285         hashjitter = arc4random();
  286         if (in6_inithead(head, off) == 1) {
  287                 rnh = (struct radix_node_head *)*head;
  288                 rnh->rnh_multipath = 1;
  289                 return 1;
  290         } else
  291                 return 0;
  292 }
  293 
  294 #endif

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