Fix for occasional hang

ChangeLog

@@ -1,3 +1,12 @@
+2022-11-07 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Headers/GNUstepBase/GSTLS.h:
+	* Source/GSTLS.m:
+	Add -pending method to return the number of bytes in the read bufffer.
+	* Source/NSSocketPort.m:
+	Use the new method to avoid a potential hang on an encrypted DO
+	connection.
+
 2022-10-21 Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/GSHTTPURLHandle.m: Refactor a litle to avoid code duplication

Headers/GNUstepBase/GSTLS.h

@@ -265,6 +265,13 @@ GS_EXPORT_CLASS
  */
 - (NSString*) owner;
 
+/** Returns the number of bytes of data available to be read from the TLS
+ * buffers (using the -read:length: method).  If this returns zero the TLS
+ * software needs to perform a network read before any more data can be
+ * returned.
+ */
+- (size_t) pending;
+
 /* After a failed handshake, this should contain a description of the
  * failure reason.
  */

Source/GSTLS.m

@@ -2063,6 +2063,11 @@ retrieve_callback(gnutls_session_t session,
   return owner;
 }
 
+- (size_t) pending
+{
+  return gnutls_record_check_pending(session);
+}
+
 - (NSString*) problem
 {
   return problem;

Source/NSSocketPort.m

@@ -862,6 +862,9 @@ static Class	runLoopClass;
 
 - (void) receivedEventRead
 {
+#if     defined(HAVE_GNUTLS)
+  do {
+#endif
   unsigned	want;
   void	*bytes;
   int	res;
@@ -1219,6 +1222,14 @@ static Class	runLoopClass;
           bytes = [rData mutableBytes];
         }
     }
+#if     defined(HAVE_GNUTLS)
+  /* As long as there are bytes available in the TLS buffers we must act as
+   * if the network connection is readable, otherwise we could have a hang
+   * waiting for the run loop to signal more data when the TLS layer has
+   * already read it.
+   */
+  } while ([session pending]);
+#endif
 }
 
 - (void) receivedEventWrite