Poll local socket to make sure SSH tunnel is ready before connecting

java/com/tigervnc/vncviewer/Tunnel.java

@@ -29,6 +29,8 @@
 import java.io.File;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.io.IOException;
+import java.net.*;
 import java.util.*;
 
 import com.tigervnc.rdr.*;
@@ -209,13 +211,38 @@ private static void createTunnelExt(String gatewayHost, String remoteHost,
  try {
  Thread t = new Thread(new ExtProcess(cmd, vlog, true));
  t.start();
- // wait for the ssh process to start
- Thread.sleep(1000);
+ // try for up to 5s
+ for (int i=0;i<50;i++) {
+ if (isTunnelReady(localPort))
+ return;
+ else
+ Thread.sleep(100);
+ }
+ throw new Exception("SSH Tunnel not ready");
  } catch (java.lang.Exception e) {
  throw new Exception(e.getMessage());
  }
  }
 
+ private static boolean isTunnelReady(int localPort) throws Exception {
+ // test the local forwarding socket to make
+ // sure the tunnel is up before connecting
+ SocketAddress sockAddr =
+ new InetSocketAddress("localhost", localPort);
+ java.net.Socket socket = new java.net.Socket();
+ boolean ready = false;
+ try {
+ socket.connect(sockAddr);
+ ready = socket.isConnected();
+ socket.close();
+ } catch (IOException e) {
+ // expected until tunnel is up
+ } catch (java.lang.Exception e) {
+ throw new Exception(e.getMessage());
+ }
+ return ready;
+ }
+
  private static String fillCmdPattern(String pattern, String gatewayHost,
  String remoteHost, int remotePort,
  int localPort) {