Use `struct ip_mreqn' instead of `struct ip_mreq' for multicast

operations on 2.1/2.2 kernels. This allows passing of real interface
indexes instead of referencing interfaces by their IP addresses which
fails badly in presence of unnumbered interfaces.

Unfortunately, this structure is not visible with glibc 2.0 as it provides
its own networking headers :-(  Both libc5 and glibc 2.1 should be OK.

1 files changed, 12 insertions, 0 deletions

diff --git a/aclocal.m4 b/aclocal.m4
index 651b0db4..98a5ca8e 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -116,3 +116,15 @@ case "$bird_cv_type_time_t" in
 	*)		AC_DEFINE(TIME_T_IS_SIGNED) ;;
 	esac
 ])
+
+AC_DEFUN(BIRD_CHECK_STRUCT_IP_MREQN,
+[AC_CACHE_CHECK([struct ip_mreqn], bird_cv_struct_ip_mreqn,[
+AC_TRY_COMPILE([#include <netinet/in.h>
+],[struct ip_mreqn x;
+],[bird_cv_struct_ip_mreqn=yes
+],[bird_cv_struct_ip_mreqn=no
+])])
+if test "$bird_cv_struct_ip_mreqn" = yes ; then
+	AC_DEFINE(HAVE_STRUCT_IP_MREQN)
+fi
+])