sysdeps/unix/sysv/linux/getipv4sourcefilter.c

   1 /* Get IPv4 source filter.  Linux version.
   2    Copyright (C) 2004-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <stdlib.h>
  21 #include <scratch_buffer.h>
  22 #include <string.h>
  23 #include <stdint.h>
  24 #include <netinet/in.h>
  25 #include <sys/param.h>
  26 #include <sys/socket.h>
  27
  28
  29 int
  30 getipv4sourcefilter (int s, struct in_addr interface, struct in_addr group,
  31                      uint32_t *fmode, uint32_t *numsrc, struct in_addr *slist)
  32 {
  33   /* We have to create an struct ip_msfilter object which we can pass
  34      to the kernel.  */
  35   socklen_t needed = IP_MSFILTER_SIZE (*numsrc);
  36
  37   struct scratch_buffer buf;
  38   scratch_buffer_init (&buf);
  39   if (!scratch_buffer_set_array_size (&buf, 1, needed))
  40     return -1;
  41   struct ip_msfilter *imsf = buf.data;
  42
  43   imsf->imsf_multiaddr = group;
  44   imsf->imsf_interface = interface;
  45   imsf->imsf_numsrc = *numsrc;
  46
  47   int result = __getsockopt (s, SOL_IP, IP_MSFILTER, imsf, &needed);
  48
  49   /* If successful, copy the results to the places the caller wants
  50      them in.  */
  51   if (result == 0)
  52     {
  53       *fmode = imsf->imsf_fmode;
  54       memcpy (slist, imsf->imsf_slist,
  55               MIN (*numsrc, imsf->imsf_numsrc) * sizeof (struct in_addr));
  56       *numsrc = imsf->imsf_numsrc;
  57     }
  58
  59   scratch_buffer_free (&buf);
  60
  61   return result;
  62 }