usr.sbin/mrouted/config.c

   1 /*
   2  * The mrouted program is covered by the license in the accompanying file
   3  * named "LICENSE".  Use of the mrouted program represents acceptance of
   4  * the terms and conditions listed in that file.
   5  *
   6  * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
   7  * Leland Stanford Junior University.
   8  *
   9  *
  10  * config.c,v 3.8.4.10 1998/01/06 01:57:41 fenner Exp
  11  *
  12  * $FreeBSD: src/usr.sbin/mrouted/config.c,v 1.14 1999/08/28 01:17:03 peter Exp $
  13  * $DragonFly: src/usr.sbin/mrouted/config.c,v 1.3 2004/03/15 18:10:28 dillon Exp $
  14  */
  15
  16 #include "defs.h"
  17
  18
  19 struct ifconf ifc;
  20
  21 /*
  22  * Query the kernel to find network interfaces that are multicast-capable
  23  * and install them in the uvifs array.
  24  */
  25 void
  26 config_vifs_from_kernel(void)
  27 {
  28     struct ifreq *ifrp, *ifend;
  29     struct uvif *v;
  30     vifi_t vifi;
  31     int n;
  32     u_int32 addr, mask, subnet;
  33     short flags;
  34     int num_ifreq = 32;
  35
  36     ifc.ifc_len = num_ifreq * sizeof(struct ifreq);
  37     ifc.ifc_buf = malloc(ifc.ifc_len);
  38     while (ifc.ifc_buf) {
  39         if (ioctl(udp_socket, SIOCGIFCONF, (char *)&ifc) < 0)
  40             log(LOG_ERR, errno, "ioctl SIOCGIFCONF");
  41
  42         /*
  43          * If the buffer was large enough to hold all the addresses
  44          * then break out, otherwise increase the buffer size and
  45          * try again.
  46          *
  47          * The only way to know that we definitely had enough space
  48          * is to know that there was enough space for at least one
  49          * more struct ifreq. ???
  50          */
  51         if ((num_ifreq * sizeof(struct ifreq)) >=
  52              ifc.ifc_len + sizeof(struct ifreq))
  53              break;
  54
  55         num_ifreq *= 2;
  56         ifc.ifc_len = num_ifreq * sizeof(struct ifreq);
  57         ifc.ifc_buf = realloc(ifc.ifc_buf, ifc.ifc_len);
  58     }
  59     if (ifc.ifc_buf == NULL)
  60         log(LOG_ERR, 0, "config_vifs_from_kernel: ran out of memory");
  61
  62     ifrp = (struct ifreq *)ifc.ifc_buf;
  63     ifend = (struct ifreq *)(ifc.ifc_buf + ifc.ifc_len);
  64     /*
  65      * Loop through all of the interfaces.
  66      */
  67     for (; ifrp < ifend; ifrp = (struct ifreq *)((char *)ifrp + n)) {
  68         struct ifreq ifr;
  69 #ifdef HAVE_SA_LEN
  70         n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
  71         if (n < sizeof(*ifrp))
  72             n = sizeof(*ifrp);
  73 #else
  74         n = sizeof(*ifrp);
  75 #endif
  76         /*
  77          * Ignore any interface for an address family other than IP.
  78          */
  79         if (ifrp->ifr_addr.sa_family != AF_INET)
  80             continue;
  81
  82         addr = ((struct sockaddr_in *)&ifrp->ifr_addr)->sin_addr.s_addr;
  83
  84         /*
  85          * Need a template to preserve address info that is
  86          * used below to locate the next entry.  (Otherwise,
  87          * SIOCGIFFLAGS stomps over it because the requests
  88          * are returned in a union.)
  89          */
  90         bcopy(ifrp->ifr_name, ifr.ifr_name, sizeof(ifr.ifr_name));
  91
  92         /*
  93          * Ignore loopback interfaces and interfaces that do not support
  94          * multicast.
  95          */
  96         if (ioctl(udp_socket, SIOCGIFFLAGS, (char *)&ifr) < 0)
  97             log(LOG_ERR, errno, "ioctl SIOCGIFFLAGS for %s", ifr.ifr_name);
  98         flags = ifr.ifr_flags;
  99         if ((flags & (IFF_LOOPBACK|IFF_MULTICAST)) != IFF_MULTICAST) continue;
 100
 101         /*
 102          * Ignore any interface whose address and mask do not define a
 103          * valid subnet number, or whose address is of the form {subnet,0}
 104          * or {subnet,-1}.
 105          */
 106         if (ioctl(udp_socket, SIOCGIFNETMASK, (char *)&ifr) < 0)
 107             log(LOG_ERR, errno, "ioctl SIOCGIFNETMASK for %s", ifr.ifr_name);
 108         mask = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr;
 109         subnet = addr & mask;
 110         if (!inet_valid_subnet(subnet, mask) ||
 111             addr == subnet ||
 112             addr == (subnet | ~mask)) {
 113             log(LOG_WARNING, 0,
 114                 "ignoring %s, has invalid address (%s) and/or mask (%s)",
 115                 ifr.ifr_name, inet_fmt(addr, s1), inet_fmt(mask, s2));
 116             continue;
 117         }
 118
 119         /*
 120          * Ignore any interface that is connected to the same subnet as
 121          * one already installed in the uvifs array.
 122          */
 123         for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
 124             if (strcmp(v->uv_name, ifr.ifr_name) == 0) {
 125                 log(LOG_DEBUG, 0, "skipping %s (%s on subnet %s) (alias for vif#%u?)",
 126                         v->uv_name, inet_fmt(addr, s1),
 127                         inet_fmts(subnet, mask, s2), vifi);
 128                 break;
 129             }
 130             if ((addr & v->uv_subnetmask) == v->uv_subnet ||
 131                 (v->uv_subnet & mask) == subnet) {
 132                 log(LOG_WARNING, 0, "ignoring %s, same subnet as %s",
 133                                         ifr.ifr_name, v->uv_name);
 134                 break;
 135             }
 136         }
 137         if (vifi != numvifs) continue;
 138
 139         /*
 140          * If there is room in the uvifs array, install this interface.
 141          */
 142         if (numvifs == MAXVIFS) {
 143             log(LOG_WARNING, 0, "too many vifs, ignoring %s", ifr.ifr_name);
 144             continue;
 145         }
 146         v  = &uvifs[numvifs];
 147         zero_vif(v, 0);
 148         v->uv_lcl_addr    = addr;
 149         v->uv_subnet      = subnet;
 150         v->uv_subnetmask  = mask;
 151         v->uv_subnetbcast = subnet | ~mask;
 152         strncpy(v->uv_name, ifr.ifr_name, IFNAMSIZ);
 153         v->uv_name[IFNAMSIZ-1] = '\0';
 154
 155         if (flags & IFF_POINTOPOINT)
 156             v->uv_flags |= VIFF_REXMIT_PRUNES;
 157
 158         log(LOG_INFO,0,"installing %s (%s on subnet %s) as vif #%u - rate=%d",
 159             v->uv_name, inet_fmt(addr, s1), inet_fmts(subnet, mask, s2),
 160             numvifs, v->uv_rate_limit);
 161
 162         ++numvifs;
 163
 164         /*
 165          * If the interface is not yet up, set the vifs_down flag to
 166          * remind us to check again later.
 167          */
 168         if (!(flags & IFF_UP)) {
 169             v->uv_flags |= VIFF_DOWN;
 170             vifs_down = TRUE;
 171         }
 172     }
 173 }