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/11.0/sys/net/radix_mpath.c 298663 2016-04-26 20:27:17Z cem $");
   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/route_var.h>
   52 #include <net/if.h>
   53 #include <net/if_var.h>
   54 
   55 /*
   56  * give some jitter to hash, to avoid synchronization between routers
   57  */
   58 static uint32_t hashjitter;
   59 
   60 int
   61 rt_mpath_capable(struct rib_head *rnh)
   62 {
   63 
   64         return rnh->rnh_multipath;
   65 }
   66 
   67 int
   68 rn_mpath_capable(struct radix_head *rh)
   69 {
   70 
   71         return (rt_mpath_capable((struct rib_head *)rh));
   72 }
   73 
   74 struct radix_node *
   75 rn_mpath_next(struct radix_node *rn)
   76 {
   77         struct radix_node *next;
   78 
   79         if (!rn->rn_dupedkey)
   80                 return NULL;
   81         next = rn->rn_dupedkey;
   82         if (rn->rn_mask == next->rn_mask)
   83                 return next;
   84         else
   85                 return NULL;
   86 }
   87 
   88 uint32_t
   89 rn_mpath_count(struct radix_node *rn)
   90 {
   91         uint32_t i = 0;
   92         struct rtentry *rt;
   93         
   94         while (rn != NULL) {
   95                 rt = (struct rtentry *)rn;
   96                 i += rt->rt_weight;
   97                 rn = rn_mpath_next(rn);
   98         }
   99         return (i);
  100 }
  101 
  102 struct rtentry *
  103 rt_mpath_matchgate(struct rtentry *rt, struct sockaddr *gate)
  104 {
  105         struct radix_node *rn;
  106 
  107         if (!gate || !rt->rt_gateway)
  108                 return NULL;
  109 
  110         /* beyond here, we use rn as the master copy */
  111         rn = (struct radix_node *)rt;
  112         do {
  113                 rt = (struct rtentry *)rn;
  114                 /*
  115                  * we are removing an address alias that has 
  116                  * the same prefix as another address
  117                  * we need to compare the interface address because
  118                  * rt_gateway is a special sockadd_dl structure
  119                  */
  120                 if (rt->rt_gateway->sa_family == AF_LINK) {
  121                         if (!memcmp(rt->rt_ifa->ifa_addr, gate, gate->sa_len))
  122                                 break;
  123                 }
  124 
  125                 /*
  126                  * Check for other options:
  127                  * 1) Routes with 'real' IPv4/IPv6 gateway
  128                  * 2) Loopback host routes (another AF_LINK/sockadd_dl check)
  129                  * */
  130                 if (rt->rt_gateway->sa_len == gate->sa_len &&
  131                     !memcmp(rt->rt_gateway, gate, gate->sa_len))
  132                         break;
  133         } while ((rn = rn_mpath_next(rn)) != NULL);
  134 
  135         return (struct rtentry *)rn;
  136 }
  137 
  138 /* 
  139  * go through the chain and unlink "rt" from the list
  140  * the caller will free "rt"
  141  */
  142 int
  143 rt_mpath_deldup(struct rtentry *headrt, struct rtentry *rt)
  144 {
  145         struct radix_node *t, *tt;
  146 
  147         if (!headrt || !rt)
  148             return (0);
  149         t = (struct radix_node *)headrt;
  150         tt = rn_mpath_next(t);
  151         while (tt) {
  152             if (tt == (struct radix_node *)rt) {
  153                 t->rn_dupedkey = tt->rn_dupedkey;
  154                 tt->rn_dupedkey = NULL;
  155                 tt->rn_flags &= ~RNF_ACTIVE;
  156                 tt[1].rn_flags &= ~RNF_ACTIVE;
  157                 return (1);
  158             }
  159             t = tt;
  160             tt = rn_mpath_next((struct radix_node *)t);
  161         }
  162         return (0);
  163 }
  164 
  165 /*
  166  * check if we have the same key/mask/gateway on the table already.
  167  * Assume @rt rt_key host bits are cleared according to @netmask
  168  */
  169 int
  170 rt_mpath_conflict(struct rib_head *rnh, struct rtentry *rt,
  171     struct sockaddr *netmask)
  172 {
  173         struct radix_node *rn, *rn1;
  174         struct rtentry *rt1;
  175 
  176         rn = (struct radix_node *)rt;
  177         rn1 = rnh->rnh_lookup(rt_key(rt), netmask, &rnh->head);
  178         if (!rn1 || rn1->rn_flags & RNF_ROOT)
  179                 return (0);
  180 
  181         /* key/mask are the same. compare gateway for all multipaths */
  182         do {
  183                 rt1 = (struct rtentry *)rn1;
  184 
  185                 /* sanity: no use in comparing the same thing */
  186                 if (rn1 == rn)
  187                         continue;
  188         
  189                 if (rt1->rt_gateway->sa_family == AF_LINK) {
  190                         if (rt1->rt_ifa->ifa_addr->sa_len != rt->rt_ifa->ifa_addr->sa_len ||
  191                             bcmp(rt1->rt_ifa->ifa_addr, rt->rt_ifa->ifa_addr, 
  192                             rt1->rt_ifa->ifa_addr->sa_len))
  193                                 continue;
  194                 } else {
  195                         if (rt1->rt_gateway->sa_len != rt->rt_gateway->sa_len ||
  196                             bcmp(rt1->rt_gateway, rt->rt_gateway,
  197                             rt1->rt_gateway->sa_len))
  198                                 continue;
  199                 }
  200 
  201                 /* all key/mask/gateway are the same.  conflicting entry. */
  202                 return (EEXIST);
  203         } while ((rn1 = rn_mpath_next(rn1)) != NULL);
  204 
  205         return (0);
  206 }
  207 
  208 static struct rtentry *
  209 rt_mpath_selectrte(struct rtentry *rte, uint32_t hash)
  210 {
  211         struct radix_node *rn0, *rn;
  212         uint32_t total_weight;
  213         struct rtentry *rt;
  214         int64_t weight;
  215 
  216         /* beyond here, we use rn as the master copy */
  217         rn0 = rn = (struct radix_node *)rte;
  218         rt = rte;
  219 
  220         /* gw selection by Modulo-N Hash (RFC2991) XXX need improvement? */
  221         total_weight = rn_mpath_count(rn0);
  222         hash += hashjitter;
  223         hash %= total_weight;
  224         for (weight = abs((int32_t)hash);
  225              rt != NULL && weight >= rt->rt_weight; 
  226              weight -= (rt == NULL) ? 0 : rt->rt_weight) {
  227                 
  228                 /* stay within the multipath routes */
  229                 if (rn->rn_dupedkey && rn->rn_mask != rn->rn_dupedkey->rn_mask)
  230                         break;
  231                 rn = rn->rn_dupedkey;
  232                 rt = (struct rtentry *)rn;
  233         }
  234 
  235         return (rt);
  236 }
  237 
  238 struct rtentry *
  239 rt_mpath_select(struct rtentry *rte, uint32_t hash)
  240 {
  241         if (rn_mpath_next((struct radix_node *)rte) == NULL)
  242                 return (rte);
  243 
  244         return (rt_mpath_selectrte(rte, hash));
  245 }
  246 
  247 void
  248 rtalloc_mpath_fib(struct route *ro, uint32_t hash, u_int fibnum)
  249 {
  250         struct rtentry *rt;
  251 
  252         /*
  253          * XXX we don't attempt to lookup cached route again; what should
  254          * be done for sendto(3) case?
  255          */
  256         if (ro->ro_rt && ro->ro_rt->rt_ifp && (ro->ro_rt->rt_flags & RTF_UP)
  257             && RT_LINK_IS_UP(ro->ro_rt->rt_ifp))
  258                 return;                          
  259         ro->ro_rt = rtalloc1_fib(&ro->ro_dst, 1, 0, fibnum);
  260 
  261         /* if the route does not exist or it is not multipath, don't care */
  262         if (ro->ro_rt == NULL)
  263                 return;
  264         if (rn_mpath_next((struct radix_node *)ro->ro_rt) == NULL) {
  265                 RT_UNLOCK(ro->ro_rt);
  266                 return;
  267         }
  268 
  269         rt = rt_mpath_selectrte(ro->ro_rt, hash);
  270         /* XXX try filling rt_gwroute and avoid unreachable gw  */
  271 
  272         /* gw selection has failed - there must be only zero weight routes */
  273         if (!rt) {
  274                 RT_UNLOCK(ro->ro_rt);
  275                 ro->ro_rt = NULL;
  276                 return;
  277         }
  278         if (ro->ro_rt != rt) {
  279                 RTFREE_LOCKED(ro->ro_rt);
  280                 ro->ro_rt = rt;
  281                 RT_LOCK(ro->ro_rt);
  282                 RT_ADDREF(ro->ro_rt);
  283 
  284         } 
  285         RT_UNLOCK(ro->ro_rt);
  286 }
  287 
  288 extern int      in6_inithead(void **head, int off);
  289 extern int      in_inithead(void **head, int off);
  290 
  291 #ifdef INET
  292 int
  293 rn4_mpath_inithead(void **head, int off)
  294 {
  295         struct rib_head *rnh;
  296 
  297         hashjitter = arc4random();
  298         if (in_inithead(head, off) == 1) {
  299                 rnh = (struct rib_head *)*head;
  300                 rnh->rnh_multipath = 1;
  301                 return 1;
  302         } else
  303                 return 0;
  304 }
  305 #endif
  306 
  307 #ifdef INET6
  308 int
  309 rn6_mpath_inithead(void **head, int off)
  310 {
  311         struct rib_head *rnh;
  312 
  313         hashjitter = arc4random();
  314         if (in6_inithead(head, off) == 1) {
  315                 rnh = (struct rib_head *)*head;
  316                 rnh->rnh_multipath = 1;
  317                 return 1;
  318         } else
  319                 return 0;
  320 }
  321 
  322 #endif

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