Initialize udp socket nonblocking

configure

@@ -11176,6 +11176,52 @@ if test "x$ac_cv_type_u_char" = xyes; then :
 fi
 
 
+for ac_func in fcntl
+do :
+  ac_fn_c_check_func "$LINENO" "fcntl" "ac_cv_func_fcntl"
+if test "x$ac_cv_func_fcntl" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_FCNTL 1
+_ACEOF
+
+fi
+done
+
+# check ioctlsocket
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for ioctlsocket" >&5
+$as_echo_n "checking for ioctlsocket... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#endif
+
+int
+main ()
+{
+
+	(void)ioctlsocket(0, 0, NULL);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+$as_echo "#define HAVE_IOCTLSOCKET 1" >>confdefs.h
+
+
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+
 getdns_LIBS=$LIBS
 getdns_LDFLAGS=$LDFLAGS
 

configure.ac

@@ -189,6 +189,20 @@ AC_TYPE_UINT64_T
 AC_TYPE_UINT8_T
 AC_CHECK_TYPE([u_char])
 
+AC_CHECK_FUNCS([fcntl])
+# check ioctlsocket
+AC_MSG_CHECKING(for ioctlsocket)
+AC_LINK_IFELSE([AC_LANG_PROGRAM([
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#endif
+], [
+	(void)ioctlsocket(0, 0, NULL);
+])], [
+AC_MSG_RESULT(yes)
+AC_DEFINE(HAVE_IOCTLSOCKET, 1, [if the function 'ioctlsocket' is available])
+],[AC_MSG_RESULT(no)])
+
 getdns_LIBS=$LIBS
 getdns_LDFLAGS=$LDFLAGS
 

src/config.h.in

@@ -30,9 +30,15 @@
 /* Define to 1 if you have the <ev.h> header file. */
 #undef HAVE_EV_H
 
+/* Define to 1 if you have the `fcntl' function. */
+#undef HAVE_FCNTL
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
 
+/* if the function 'ioctlsocket' is available */
+#undef HAVE_IOCTLSOCKET
+
 /* Define to 1 if you have the <libev/ev.h> header file. */
 #undef HAVE_LIBEV_EV_H
 

src/stub.c

@@ -32,6 +32,7 @@
  */
 
 #include "config.h"
+#include <fcntl.h>
 #include "stub.h"
 #include "gldns/rrdef.h"
 #include "gldns/str2wire.h"
@@ -42,7 +43,6 @@
 #include "util-internal.h"
 #include "general.h"
 
-
 static int
 getdns_make_query_pkt_buf(getdns_context *context, const char *name,
     uint16_t request_type, getdns_dict *extensions, uint8_t* buf, size_t* olen)
@@ -243,6 +243,26 @@ getdns_get_query_pkt_size(getdns_context *context,
 	    ;
 }
 
+/** best effort to set nonblocking */
+static void
+getdns_sock_nonblock(int sockfd)
+{
+#ifdef HAVE_FCNTL
+	int flag;
+	if((flag = fcntl(sockfd, F_GETFL)) != -1) {
+		flag |= O_NONBLOCK;
+		if(fcntl(sockfd, F_SETFL, flag) == -1) {
+			/* ignore error, continue blockingly */
+		}
+	}
+#elif defined(HAVE_IOCTLSOCKET)
+	unsigned long on = 1;
+	if(ioctlsocket(sockfd, FIONBIO, &on) != 0) {
+		/* ignore error, continue blockingly */
+	}
+#endif
+}
+
 static void
 stub_resolve_timeout_cb(void *userarg)
 {
@@ -327,6 +347,8 @@ priv_getdns_submit_stub_request(getdns_network_req *netreq)
 	    upstream->addr.ss_family, SOCK_DGRAM, IPPROTO_UDP)) == -1)
 		goto error;
 
+	getdns_sock_nonblock(netreq->udp_fd);
+
 	if (pkt_len != sendto(netreq->udp_fd, pkt, pkt_len, 0,
 	    (struct sockaddr *)&upstream->addr, upstream->addr_len)) {
 		close(netreq->udp_fd);