+
+static struct if_nameindex ni;
+
+/* We do not yet have replacements for if_* functions on systems that
+ lack a native <net/if.h>. */
+#if HAVE_NET_IF_H
+# include "signature.h"
+SIGNATURE_CHECK (if_freenameindex, void, (struct if_nameindex *));
+SIGNATURE_CHECK (if_indextoname, char *, (unsigned int, char *));
+SIGNATURE_CHECK (if_nameindex, struct if_nameindex *, (void));
+SIGNATURE_CHECK (if_nametoindex, unsigned int, (const char *));
+#endif
+