sysdeps/unix/sysv/linux/getsourcefilter.c

   1 /* Get source filter.  Linux version.
   2    Copyright (C) 2004, 2006 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <alloca.h>
  22 #include <assert.h>
  23 #include <errno.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <netatalk/at.h>
  27 #include <netax25/ax25.h>
  28 #include <netinet/in.h>
  29 #include <netipx/ipx.h>
  30 #include <netpacket/packet.h>
  31 #include <netrose/rose.h>
  32 #include <sys/param.h>
  33 #include <sys/socket.h>
  34
  35
  36 static const struct
  37 {
  38   int sol;
  39   int af;
  40   socklen_t size;
  41 }  sol_map[] =
  42   {
  43     /* Sort the array according to importance of the protocols.  Add
  44        more protocols when they become available.  */
  45     { SOL_IP, AF_INET, sizeof (struct sockaddr_in) },
  46     { SOL_IPV6, AF_INET6, sizeof (struct sockaddr_in6) },
  47     { SOL_AX25, AF_AX25, sizeof (struct sockaddr_ax25) },
  48     { SOL_IPX, AF_IPX, sizeof (struct sockaddr_ipx) },
  49     { SOL_ATALK, AF_APPLETALK, sizeof (struct sockaddr_at) },
  50     { SOL_ROSE, AF_ROSE, sizeof (struct sockaddr_rose) },
  51     { SOL_PACKET, AF_PACKET, sizeof (struct sockaddr_ll) }
  52   };
  53 #define NSOL_MAP (sizeof (sol_map) / sizeof (sol_map[0]))
  54
  55
  56 /* Try to determine the socket level value.  Ideally both side and
  57    family are set.  But sometimes only the size is correct and the
  58    family value might be bogus.  Loop over the array entries and look
  59    for a perfect match or the first match based on size.  */
  60 int
  61 __get_sol (int af, socklen_t len)
  62 {
  63   int first_size_sol = -1;
  64
  65   for (size_t cnt = 0; cnt < NSOL_MAP; ++cnt)
  66     {
  67       /* Just a test so that we make sure the special value used to
  68          signal the "we have so far no socket level value" is OK.  */
  69       assert (sol_map[cnt].sol != -1);
  70
  71       if (len == sol_map[cnt].size)
  72         {
  73           /* The size matches, which is a requirement.  If the family
  74              matches, too, we have a winner.  Otherwise we remember the
  75              socket level value for this protocol if it is the first
  76              match.  */
  77           if (af == sol_map[cnt].af)
  78             /* Bingo!  */
  79             return sol_map[cnt].sol;
  80
  81           if (first_size_sol == -1)
  82             first_size_sol = sol_map[cnt].sol;
  83       }
  84     }
  85
  86   return first_size_sol;
  87 }
  88
  89
  90 int
  91 getsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
  92                  socklen_t grouplen, uint32_t *fmode, uint32_t *numsrc,
  93                  struct sockaddr_storage *slist)
  94 {
  95   /* We have to create an struct ip_msfilter object which we can pass
  96      to the kernel.  */
  97   socklen_t needed = GROUP_FILTER_SIZE (*numsrc);
  98   int use_alloca = __libc_use_alloca (needed);
  99
 100   struct group_filter *gf;
 101   if (use_alloca)
 102     gf = (struct group_filter *) alloca (needed);
 103   else
 104     {
 105       gf = (struct group_filter *) malloc (needed);
 106       if (gf == NULL)
 107         return -1;
 108     }
 109
 110   gf->gf_interface = interface;
 111   memcpy (&gf->gf_group, group, grouplen);
 112   gf->gf_numsrc = *numsrc;
 113
 114   /* We need to provide the appropriate socket level value.  */
 115   int result;
 116   int sol = __get_sol (group->sa_family, grouplen);
 117   if (sol == -1)
 118     {
 119       __set_errno (EINVAL);
 120       result = -1;
 121     }
 122   else
 123     {
 124       result = __getsockopt (s, sol, MCAST_MSFILTER, gf, &needed);
 125
 126       /* If successful, copy the results to the places the caller wants
 127          them in.  */
 128       if (result == 0)
 129         {
 130           *fmode = gf->gf_fmode;
 131           memcpy (slist, gf->gf_slist,
 132                   MIN (*numsrc, gf->gf_numsrc)
 133                   * sizeof (struct sockaddr_storage));
 134           *numsrc = gf->gf_numsrc;
 135         }
 136     }
 137
 138   if (! use_alloca)
 139     {
 140       int save_errno = errno;
 141       free (gf);
 142       __set_errno (save_errno);
 143     }
 144
 145   return result;
 146 }