dnl AC_C_DNS
 dnl Checks resolv.h presence and usability
 dnl Checks for specific lresolv exports
 dnl Checks for lresolve reentrance
 dnl
 dnl Note using AC_LINK_IFELSE instead of AC_CHECK_LIB
 dnl as symbols are often redefined in resolv.h
 
 AC_DEFUN([AC_C_DNS], [
 
 AC_ARG_ENABLE([dns],

     [AC_HELP_STRING([--disable-dns], [do not include support for database verification through DNS])],

     [want_dns=$enableval], [want_dns=yes]
 )
 if test $want_dns = yes; then

     ac_cv_have_lresolv=no

     AC_CHECK_HEADER([resolv.h],
 	[

 	    AC_CACHE_CHECK([for dn_expand in std libs], [ac_cv_have_lresolv_std], [
 	    	ac_cv_have_lresolv_std='no'

 	        AC_LINK_IFELSE([AC_LANG_SOURCE([

 #include <sys/types.h>
 #include <netinet/in.h>
 #include <arpa/nameser.h>
 #include <resolv.h>

 int main() { return (long)dn_expand; }

 		])],

 		[
 		    ac_cv_have_lresolv_std='yes'
 		    ac_cv_have_lresolv=''
 		])
 	    ])
 	    if test "x$ac_cv_have_lresolv" = "xno"; then
 	    bklibs=$LIBS
 	    LIBS=-lresolv
 	    AC_CACHE_CHECK([for dn_expand in -lresolv], [ac_cv_have_lresolv_lresolv], [
 		ac_cv_have_lresolv_lresolv='yes'

 		AC_LINK_IFELSE([AC_LANG_SOURCE([

 #include <sys/types.h>
 #include <netinet/in.h>
 #include <arpa/nameser.h>
 #include <resolv.h>

 int main() { return (long)dn_expand; }

     	     	])],

 		[

 		    ac_cv_have_lresolv_lresolv='yes'
 		    ac_cv_have_lresolv=' -lresolv'

 		])
 	    ])
 	    LIBS=$bklibs;

 	    fi

 	],

 	[ ac_cv_have_lresolv=no ],

 	[
 #include <sys/types.h>
 #include <netinet/in.h>
 #include <arpa/nameser.h>
     ])

     if test "x$ac_cv_have_lresolv" != "xno"; then
     	FRESHCLAM_LIBS="$FRESHCLAM_LIBS$ac_cv_have_lresolv"

 	AC_DEFINE([HAVE_RESOLV_H],1,[have resolv.h])
     else
 	AC_MSG_WARN([****** DNS support disabled])
     fi
 fi
 
 ])