Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=54127

Add support for sending a WebSocket ping
Patch provided by Sean Winterberger

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1407619 13f79535-47bb-0310-9956-ffa450edef68

java/org/apache/catalina/websocket/WsOutbound.java

@@ -301,14 +301,37 @@ public synchronized void close(int status, ByteBuffer data)
      * @throws IOException  If an error occurs writing to the client
      */
     public synchronized void pong(ByteBuffer data) throws IOException {
+        sendControlMessage(data, Constants.OPCODE_PONG);
+    }
+
+    /**
+     * Send a ping message to the client
+     *
+     * @param data      Optional message.
+     *
+     * @throws IOException  If an error occurs writing to the client
+     */
+    public synchronized void ping(ByteBuffer data) throws IOException {
+        sendControlMessage(data, Constants.OPCODE_PING);
+    }
+
+    /**
+     * Generic function to send either a ping or a pong.
+     *
+     * @param data      Optional message.
+     * @param opcode    The byte to include as the opcode.
+     *
+     * @throws IOException  If an error occurs writing to the client
+     */
+    private synchronized void sendControlMessage(ByteBuffer data, byte opcode) throws IOException {
 
         if (closed) {
             throw new IOException(sm.getString("outbound.closed"));
         }
 
         doFlush(true);
 
-        upgradeOutbound.write(0x8A);
+        upgradeOutbound.write(0x80 | opcode);
         if (data == null) {
             upgradeOutbound.write(0);
         } else {