GUACAMOLE-422: Implement GuacamoleProtocolCapability enum.

guacamole-common/src/main/java/org/apache/guacamole/protocol/ConfiguredGuacamoleSocket.java

@@ -200,9 +200,8 @@ public class ConfiguredGuacamoleSocket implements GuacamoleSocket {
                     info.getImageMimetypes().toArray(new String[0])
                 ));
         
-        // Protocol version 1.1.0 and higher options
+        // Check for support for timezone handshake
-        
+        if (protocol.isSupported(GuacamoleProtocolCapability.TIMEZONE_HANDSHAKE)) {
-        if (protocol.atLeast(GuacamoleProtocolVersion.VERSION_1_1_0)) {
             // Send client timezone, if available
             String timezone = info.getTimezone();
             if (timezone != null && !timezone.isEmpty()) {

guacamole-common/src/main/java/org/apache/guacamole/protocol/GuacamoleProtocolCapability.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.guacamole.protocol;
+
+/**
+ * An enum that specifies protocol capabilities that can be used to help
+ * detect whether or not a particular protocol version contains a capability.
+ */
+public enum GuacamoleProtocolCapability {
+    
+    /**
+     * Whether or not the protocol supports arbitrary ordering of the
+     * handshake instructions.  This was introduced in VERSION_1_1_0.
+     */
+    ARBITRARY_HANDSHAKE_ORDER(GuacamoleProtocolVersion.VERSION_1_1_0),
+    
+    /**
+     * Whether or not the protocol supports the ability to dynamically
+     * detect the version client and server are running in order to allow
+     * compatibility between differing client and server versions.  This
+     * was introduced in VERSION_1_1_0.
+     */
+    PROTOCOL_VERSION_DETECTION(GuacamoleProtocolVersion.VERSION_1_1_0),
+    
+    /**
+     * Whether or not the protocol supports the timezone instruction during
+     * the Client-Server handshake phase.  This was introduced in
+     * VERSION_1_1_0.
+     */
+    TIMEZONE_HANDSHAKE(GuacamoleProtocolVersion.VERSION_1_1_0);
+    
+    /**
+     * The minimum protocol version required to support this capability.
+     */
+    private final GuacamoleProtocolVersion version;
+    
+    /**
+     * Create a new enum value with the given protocol version as the minimum
+     * required to support the capability.
+     * 
+     * @param version
+     *     The minimum required protocol version for supporting the
+     *     capability.
+     */
+    GuacamoleProtocolCapability(GuacamoleProtocolVersion version) {
+        this.version = version;
+    }
+    
+    /**
+     * Returns the minimum protocol version required to support this
+     * capability.
+     * 
+     * @return
+     *     The minimum protocol version required to support this capability.
+     */
+    public GuacamoleProtocolVersion getVersion() {
+        return version;
+    }
+    
+}

guacamole-common/src/main/java/org/apache/guacamole/protocol/GuacamoleProtocolVersion.java

@@ -173,4 +173,21 @@ public enum GuacamoleProtocolVersion {
         
     }
     
+    /**
+     * Returns true if the specified capability is supported in the current
+     * protocol version, otherwise false.
+     * 
+     * @param capability
+     *     The protocol capability that is being checked for support.
+     * 
+     * @return
+     *     True if the capability is supported in the current version,
+     *     otherwise false.
+     */
+    public boolean isSupported(GuacamoleProtocolCapability capability) {
+        
+        return atLeast(capability.getVersion());
+        
+    }
+    
 }