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  * SPDX-License-Identifier: BSD-3-Clause
    5  *
    6  * Copyright (C) 2001 WIDE Project.
    7  * All rights reserved.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. Neither the name of the project nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  * THE AUTHORS DO NOT GUARANTEE THAT THIS SOFTWARE DOES NOT INFRINGE
   33  * ANY OTHERS' INTELLECTUAL PROPERTIES. IN NO EVENT SHALL THE AUTHORS
   34  * BE LIABLE FOR ANY INFRINGEMENT OF ANY OTHERS' INTELLECTUAL
   35  * PROPERTIES.
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/12.0/sys/net/radix_mpath.c 335250 2018-06-16 08:26:23Z ae $");
   40 
   41 #include "opt_inet.h"
   42 #include "opt_inet6.h"
   43 
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/lock.h>
   47 #include <sys/malloc.h>
   48 #include <sys/mutex.h>
   49 #include <sys/socket.h>
   50 #include <sys/domain.h>
   51 #include <sys/syslog.h>
   52 #include <net/radix.h>
   53 #include <net/radix_mpath.h>
   54 #include <sys/rmlock.h>
   55 #include <net/route.h>
   56 #include <net/route_var.h>
   57 #include <net/if.h>
   58 #include <net/if_var.h>
   59 
   60 /*
   61  * give some jitter to hash, to avoid synchronization between routers
   62  */
   63 static uint32_t hashjitter;
   64 
   65 int
   66 rt_mpath_capable(struct rib_head *rnh)
   67 {
   68 
   69         return rnh->rnh_multipath;
   70 }
   71 
   72 int
   73 rn_mpath_capable(struct radix_head *rh)
   74 {
   75 
   76         return (rt_mpath_capable((struct rib_head *)rh));
   77 }
   78 
   79 struct radix_node *
   80 rn_mpath_next(struct radix_node *rn)
   81 {
   82         struct radix_node *next;
   83 
   84         if (!rn->rn_dupedkey)
   85                 return NULL;
   86         next = rn->rn_dupedkey;
   87         if (rn->rn_mask == next->rn_mask)
   88                 return next;
   89         else
   90                 return NULL;
   91 }
   92 
   93 uint32_t
   94 rn_mpath_count(struct radix_node *rn)
   95 {
   96         uint32_t i = 0;
   97         struct rtentry *rt;
   98         
   99         while (rn != NULL) {
  100                 rt = (struct rtentry *)rn;
  101                 i += rt->rt_weight;
  102                 rn = rn_mpath_next(rn);
  103         }
  104         return (i);
  105 }
  106 
  107 struct rtentry *
  108 rt_mpath_matchgate(struct rtentry *rt, struct sockaddr *gate)
  109 {
  110         struct radix_node *rn;
  111 
  112         if (!gate || !rt->rt_gateway)
  113                 return NULL;
  114 
  115         /* beyond here, we use rn as the master copy */
  116         rn = (struct radix_node *)rt;
  117         do {
  118                 rt = (struct rtentry *)rn;
  119                 /*
  120                  * we are removing an address alias that has 
  121                  * the same prefix as another address
  122                  * we need to compare the interface address because
  123                  * rt_gateway is a special sockadd_dl structure
  124                  */
  125                 if (rt->rt_gateway->sa_family == AF_LINK) {
  126                         if (!memcmp(rt->rt_ifa->ifa_addr, gate, gate->sa_len))
  127                                 break;
  128                 }
  129 
  130                 /*
  131                  * Check for other options:
  132                  * 1) Routes with 'real' IPv4/IPv6 gateway
  133                  * 2) Loopback host routes (another AF_LINK/sockadd_dl check)
  134                  * */
  135                 if (rt->rt_gateway->sa_len == gate->sa_len &&
  136                     !memcmp(rt->rt_gateway, gate, gate->sa_len))
  137                         break;
  138         } while ((rn = rn_mpath_next(rn)) != NULL);
  139 
  140         return (struct rtentry *)rn;
  141 }
  142 
  143 /* 
  144  * go through the chain and unlink "rt" from the list
  145  * the caller will free "rt"
  146  */
  147 int
  148 rt_mpath_deldup(struct rtentry *headrt, struct rtentry *rt)
  149 {
  150         struct radix_node *t, *tt;
  151 
  152         if (!headrt || !rt)
  153             return (0);
  154         t = (struct radix_node *)headrt;
  155         tt = rn_mpath_next(t);
  156         while (tt) {
  157             if (tt == (struct radix_node *)rt) {
  158                 t->rn_dupedkey = tt->rn_dupedkey;
  159                 tt->rn_dupedkey = NULL;
  160                 tt->rn_flags &= ~RNF_ACTIVE;
  161                 tt[1].rn_flags &= ~RNF_ACTIVE;
  162                 return (1);
  163             }
  164             t = tt;
  165             tt = rn_mpath_next((struct radix_node *)t);
  166         }
  167         return (0);
  168 }
  169 
  170 /*
  171  * check if we have the same key/mask/gateway on the table already.
  172  * Assume @rt rt_key host bits are cleared according to @netmask
  173  */
  174 int
  175 rt_mpath_conflict(struct rib_head *rnh, struct rtentry *rt,
  176     struct sockaddr *netmask)
  177 {
  178         struct radix_node *rn, *rn1;
  179         struct rtentry *rt1;
  180 
  181         rn = (struct radix_node *)rt;
  182         rn1 = rnh->rnh_lookup(rt_key(rt), netmask, &rnh->head);
  183         if (!rn1 || rn1->rn_flags & RNF_ROOT)
  184                 return (0);
  185 
  186         /* key/mask are the same. compare gateway for all multipaths */
  187         do {
  188                 rt1 = (struct rtentry *)rn1;
  189 
  190                 /* sanity: no use in comparing the same thing */
  191                 if (rn1 == rn)
  192                         continue;
  193         
  194                 if (rt1->rt_gateway->sa_family == AF_LINK) {
  195                         if (rt1->rt_ifa->ifa_addr->sa_len != rt->rt_ifa->ifa_addr->sa_len ||
  196                             bcmp(rt1->rt_ifa->ifa_addr, rt->rt_ifa->ifa_addr, 
  197                             rt1->rt_ifa->ifa_addr->sa_len))
  198                                 continue;
  199                 } else {
  200                         if (rt1->rt_gateway->sa_len != rt->rt_gateway->sa_len ||
  201                             bcmp(rt1->rt_gateway, rt->rt_gateway,
  202                             rt1->rt_gateway->sa_len))
  203                                 continue;
  204                 }
  205 
  206                 /* all key/mask/gateway are the same.  conflicting entry. */
  207                 return (EEXIST);
  208         } while ((rn1 = rn_mpath_next(rn1)) != NULL);
  209 
  210         return (0);
  211 }
  212 
  213 static struct rtentry *
  214 rt_mpath_selectrte(struct rtentry *rte, uint32_t hash)
  215 {
  216         struct radix_node *rn0, *rn;
  217         uint32_t total_weight;
  218         struct rtentry *rt;
  219         int64_t weight;
  220 
  221         /* beyond here, we use rn as the master copy */
  222         rn0 = rn = (struct radix_node *)rte;
  223         rt = rte;
  224 
  225         /* gw selection by Modulo-N Hash (RFC2991) XXX need improvement? */
  226         total_weight = rn_mpath_count(rn0);
  227         hash += hashjitter;
  228         hash %= total_weight;
  229         for (weight = abs((int32_t)hash);
  230              rt != NULL && weight >= rt->rt_weight; 
  231              weight -= (rt == NULL) ? 0 : rt->rt_weight) {
  232                 
  233                 /* stay within the multipath routes */
  234                 if (rn->rn_dupedkey && rn->rn_mask != rn->rn_dupedkey->rn_mask)
  235                         break;
  236                 rn = rn->rn_dupedkey;
  237                 rt = (struct rtentry *)rn;
  238         }
  239 
  240         return (rt);
  241 }
  242 
  243 struct rtentry *
  244 rt_mpath_select(struct rtentry *rte, uint32_t hash)
  245 {
  246         if (rn_mpath_next((struct radix_node *)rte) == NULL)
  247                 return (rte);
  248 
  249         return (rt_mpath_selectrte(rte, hash));
  250 }
  251 
  252 void
  253 rtalloc_mpath_fib(struct route *ro, uint32_t hash, u_int fibnum)
  254 {
  255         struct rtentry *rt;
  256 
  257         /*
  258          * XXX we don't attempt to lookup cached route again; what should
  259          * be done for sendto(3) case?
  260          */
  261         if (ro->ro_rt && ro->ro_rt->rt_ifp && (ro->ro_rt->rt_flags & RTF_UP)
  262             && RT_LINK_IS_UP(ro->ro_rt->rt_ifp))
  263                 return;                          
  264         ro->ro_rt = rtalloc1_fib(&ro->ro_dst, 1, 0, fibnum);
  265 
  266         /* if the route does not exist or it is not multipath, don't care */
  267         if (ro->ro_rt == NULL)
  268                 return;
  269         if (rn_mpath_next((struct radix_node *)ro->ro_rt) == NULL) {
  270                 RT_UNLOCK(ro->ro_rt);
  271                 return;
  272         }
  273 
  274         rt = rt_mpath_selectrte(ro->ro_rt, hash);
  275         /* XXX try filling rt_gwroute and avoid unreachable gw  */
  276 
  277         /* gw selection has failed - there must be only zero weight routes */
  278         if (!rt) {
  279                 RT_UNLOCK(ro->ro_rt);
  280                 ro->ro_rt = NULL;
  281                 return;
  282         }
  283         if (ro->ro_rt != rt) {
  284                 RTFREE_LOCKED(ro->ro_rt);
  285                 ro->ro_rt = rt;
  286                 RT_LOCK(ro->ro_rt);
  287                 RT_ADDREF(ro->ro_rt);
  288 
  289         } 
  290         RT_UNLOCK(ro->ro_rt);
  291 }
  292 
  293 extern int      in6_inithead(void **head, int off);
  294 extern int      in_inithead(void **head, int off);
  295 
  296 #ifdef INET
  297 int
  298 rn4_mpath_inithead(void **head, int off)
  299 {
  300         struct rib_head *rnh;
  301 
  302         hashjitter = arc4random();
  303         if (in_inithead(head, off) == 1) {
  304                 rnh = (struct rib_head *)*head;
  305                 rnh->rnh_multipath = 1;
  306                 return 1;
  307         } else
  308                 return 0;
  309 }
  310 #endif
  311 
  312 #ifdef INET6
  313 int
  314 rn6_mpath_inithead(void **head, int off)
  315 {
  316         struct rib_head *rnh;
  317 
  318         hashjitter = arc4random();
  319         if (in6_inithead(head, off) == 1) {
  320                 rnh = (struct rib_head *)*head;
  321                 rnh->rnh_multipath = 1;
  322                 return 1;
  323         } else
  324                 return 0;
  325 }
  326 
  327 #endif

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