RPCHelper.java

/*
 * Copyright 2014-2015 CyberVision, Inc.
 *
 * Licensed 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.spring4gwt.server;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.gwt.user.client.rpc.SerializationException;
import com.google.gwt.user.client.rpc.impl.AbstractSerializationStream;
import com.google.gwt.user.server.rpc.RPC;
import com.google.gwt.user.server.rpc.SerializationPolicy;

public class RPCHelper {
    
    private static final Logger LOG = LoggerFactory.getLogger(RPCHelper.class);

	  public static String invokeAndEncodeResponse(Object target, Method serviceMethod, Object[] args,
		      SerializationPolicy serializationPolicy) throws SerializationException {
		    return invokeAndEncodeResponse(target, serviceMethod, args, serializationPolicy,
		        AbstractSerializationStream.DEFAULT_FLAGS);
		  }
	  
	  public static String invokeAndEncodeResponse(Object target, Method serviceMethod, Object[] args,
		      SerializationPolicy serializationPolicy, int flags) throws SerializationException {
		    if (serviceMethod == null) {
		      throw new NullPointerException("serviceMethod");
		    }

		    if (serializationPolicy == null) {
		      throw new NullPointerException("serializationPolicy");
		    }

		    String responsePayload;
		    try {
		      Object result = serviceMethod.invoke(target, args);

		      responsePayload = RPC.encodeResponseForSuccess(serviceMethod, result, serializationPolicy, flags);
		    } catch (IllegalAccessException e) {
		      SecurityException securityException =
		          new SecurityException(formatIllegalAccessErrorMessage(target, serviceMethod));
		      securityException.initCause(e);
		      throw securityException;
		    } catch (IllegalArgumentException e) {
		      SecurityException securityException =
		          new SecurityException(formatIllegalArgumentErrorMessage(target, serviceMethod, args));
		      securityException.initCause(e);
		      throw securityException;
		    } catch (InvocationTargetException e) {
		      // Try to encode the caught exception
		      //
		      Throwable cause = e.getCause();
		      
		      LOG.error("Unexpected exception occured while invoking service method - " 
		      + (serviceMethod != null ? serviceMethod.getName() : "null"), cause);

		      responsePayload = RPC.encodeResponseForFailure(serviceMethod, cause, serializationPolicy, flags);
		    }

		    return responsePayload;
		  }
	  
	  private static String formatIllegalArgumentErrorMessage(Object target, Method serviceMethod,
		      Object[] args) {
		    StringBuffer sb = new StringBuffer();
		    sb.append("Blocked attempt to invoke method '");
		    sb.append(getSourceRepresentation(serviceMethod));
		    sb.append("'");

		    if (target != null) {
		      sb.append(" on target '");
		      sb.append(printTypeName(target.getClass()));
		      sb.append("'");
		    }

		    sb.append(" with invalid arguments");

		    if (args != null && args.length > 0) {
		      sb.append(Arrays.asList(args));
		    }

		    return sb.toString();
		  }
	  
	  private static String formatIllegalAccessErrorMessage(Object target, Method serviceMethod) {
		    StringBuffer sb = new StringBuffer();
		    sb.append("Blocked attempt to access inaccessible method '");
		    sb.append(getSourceRepresentation(serviceMethod));
		    sb.append("'");

		    if (target != null) {
		      sb.append(" on target '");
		      sb.append(printTypeName(target.getClass()));
		      sb.append("'");
		    }

		    sb.append("; this is either misconfiguration or a hack attempt");

		    return sb.toString();
		  }
	  
	  private static String printTypeName(Class<?> type) {
		    // Primitives
		    //
		    if (type.equals(Integer.TYPE)) {
		      return "int";
		    } else if (type.equals(Long.TYPE)) {
		      return "long";
		    } else if (type.equals(Short.TYPE)) {
		      return "short";
		    } else if (type.equals(Byte.TYPE)) {
		      return "byte";
		    } else if (type.equals(Character.TYPE)) {
		      return "char";
		    } else if (type.equals(Boolean.TYPE)) {
		      return "boolean";
		    } else if (type.equals(Float.TYPE)) {
		      return "float";
		    } else if (type.equals(Double.TYPE)) {
		      return "double";
		    }

		    // Arrays
		    //
		    if (type.isArray()) {
		      Class<?> componentType = type.getComponentType();
		      return printTypeName(componentType) + "[]";
		    }

		    // Everything else
		    //
		    return type.getName().replace('$', '.');
		  }
	  
	  private static String getSourceRepresentation(Method method) {
		    return method.toString().replace('$', '.');
		  }

	  
}