+ AC_REQUIRE([AC_GNU_SOURCE])
+ AC_CHECK_HEADERS_ONCE(netinet/in.h netdb.h)
+ AC_CHECK_DECLS([getaddrinfo, freeaddrinfo, gai_strerror, getnameinfo],,,[
+ /* sys/types.h is not needed according to POSIX, but the
+ sys/socket.h in i386-unknown-freebsd4.10 and
+ powerpc-apple-darwin5.5 required it. */
+#include <sys/types.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+])
+ AC_CHECK_TYPES([struct addrinfo],,,[
+#include <sys/types.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+])