external/bsd/dhcpcd/dist/if-pref.c

   1 /*
   2  * dhcpcd - DHCP client daemon
   3  * Copyright (c) 2006-2009 Roy Marples <roy@marples.name>
   4  * All rights reserved
   5
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 #include <sys/types.h>
  29
  30 #include "config.h"
  31 #include "dhcpcd.h"
  32 #include "if-pref.h"
  33 #include "net.h"
  34
  35 /* Interface comparer for working out ordering. */
  36 static int
  37 ifcmp(struct interface *si, struct interface *ti)
  38 {
  39         int sill, till;
  40
  41         if (si->state && !ti->state)
  42                 return -1;
  43         if (!si->state && ti->state)
  44                 return 1;
  45         if (!si->state && !ti->state)
  46                 return 0;
  47         /* If one has a lease and the other not, it takes precedence. */
  48         if (si->state->new && !ti->state->new)
  49                 return -1;
  50         if (!si->state->new && ti->state->new)
  51                 return 1;
  52         /* If we are either, they neither have a lease, or they both have.
  53          * We need to check for IPv4LL and make it non-preferred. */
  54         if (si->state->new) {
  55                 sill = IN_LINKLOCAL(htonl(si->state->new->yiaddr));
  56                 till = IN_LINKLOCAL(htonl(ti->state->new->yiaddr));
  57                 if (!sill && till)
  58                         return -1;
  59                 if (sill && !till)
  60                         return 1;
  61         }
  62         /* Then carrier status. */
  63         if (si->carrier > ti->carrier)
  64                 return -1;
  65         if (si->carrier < ti->carrier)
  66                 return 1;
  67         /* Finally, metric */
  68         if (si->metric < ti->metric)
  69                 return -1;
  70         if (si->metric > ti->metric)
  71                 return 1;
  72         return 0;
  73 }
  74
  75 /* Sort the interfaces into a preferred order - best first, worst last. */
  76 void
  77 sort_interfaces(void)
  78 {
  79         struct interface *sorted, *ifp, *ifn, *ift;
  80
  81         if (!ifaces || !ifaces->next)
  82                 return;
  83         sorted = ifaces;
  84         ifaces = ifaces->next;
  85         sorted->next = NULL;
  86         for (ifp = ifaces; ifp && (ifn = ifp->next, 1); ifp = ifn) {
  87                 /* Are we the new head? */
  88                 if (ifcmp(ifp, sorted) == -1) {
  89                         ifp->next = sorted;
  90                         sorted = ifp;
  91                         continue;
  92                 }
  93                 /* Do we fit in the middle? */
  94                 for (ift = sorted; ift->next; ift = ift->next) {
  95                         if (ifcmp(ifp, ift->next) == -1) {
  96                                 ifp->next = ift->next;
  97                                 ift->next = ifp;
  98                                 break;
  99                         }
 100                 }
 101                 /* We must be at the end */
 102                 if (!ift->next) {
 103                         ift->next = ifp;
 104                         ifp->next = NULL;
 105                 }
 106         }
 107         ifaces = sorted;
 108 }