com.google.gwt.user.server.rpc

Class XsrfTokenServiceServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet

com.google.gwt.user.server.rpc.RemoteServiceServlet

com.google.gwt.user.server.rpc.XsrfTokenServiceServlet

All Implemented Interfaces:

RemoteService, XsrfTokenService, SerializationPolicyProvider, Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public class XsrfTokenServiceServlet
extends RemoteServiceServlet
implements XsrfTokenService

EXPERIMENTAL and subject to change. Do not use this in production code.

RPC service to generate XSRF tokens.

Sample use of XsrfTokenService:

1. Add XsrfTokenServiceServlet to web.xml:

    <servlet>
      <servlet-name>xsrf</servlet-name>
      <servlet-class>
        com.google.gwt.user.server.rpc.XsrfTokenServiceServlet
      </servlet-class>
    </servlet>
    <servlet-mapping>
      <servlet-name>xsrf</servlet-name>
      <url-pattern>/gwt/xsrf</url-pattern>
    </servlet-mapping>
    

2. Specify session cookie name that is used for authentication. MD5 hash of the session cookie's value will be used as an XSRF token:

    <context-param>
      <param-name>gwt.xsrf.session_cookie_name</param-name>
      <param-value>JSESSIONID</param-value>
    </context-param>
    

3. To enforce XSRF token validation on each method call either mark RPC interface as XSRF protected using XsrfProtect annotation or extend XsrfProtectedService instead of RemoteService. Use NoXsrfProtect to mark methods as not requiring XSRF protection:

    public interface MyRpcService extends XsrfProtectedService {
      public void doStuff();
    }
    

4. Ensure that RPC's servlet implementation extends XsrfProtectedServiceServlet instead of RemoteServiceServlet:

    public class MyRpcServiceServlet extends XsrfProtectedServiceServlet
        implements MyRpcService {
   
      public void doStuff() {
        // ...
      }
    }
    

5. Obtain XsrfToken and set it on the RPC end point:

    XsrfTokenServiceAsync xsrf = (XsrfTokenServiceAsync)GWT.create(XsrfTokenService.class);
   
    ((ServiceDefTarget)xsrf).setServiceEntryPoint(GWT.getModuleBaseURL() + "xsrf");
   
    xsrf.getNewXsrfToken(new AsyncCallback<XsrfToken>() {
      public void onSuccess(XsrfToken result) {
        MyRpcServiceAsync rpc = (MyRpcServiceAsync)GWT.create(MyRpcService.class);
        ((HasRpcToken) rpc).setRpcToken(result);
        // make XSRF protected RPC call
        rpc.doStuff(new AsyncCallback<Void>() {
          // ...
        });
   
      }
   
      public void onFailure(Throwable caught) {
        try {
          throw caught;
        } catch (RpcTokenException e) {
          // Can be thrown for several reasons:
          //   - duplicate session cookie, which may be a sign of a cookie
          //     overwrite attack
          //   - XSRF token cannot be generated because session cookie isn't
          //     present
        } catch (Throwable e) {
          // unexpected
        }
    });
    

See Also:

XsrfProtectedServiceServlet, XsrfProtect, NoXsrfProtect, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	COOKIE_NAME_PARAM Session cookie name initialization parameter.

Fields inherited from class com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet

perThreadRequest, perThreadResponse

Constructor Summary

Constructors

Constructor and Description
XsrfTokenServiceServlet() Default constructor.
XsrfTokenServiceServlet(String sessionCookieName) Alternative constructor that accepts session cookie name instead of getting it from ServletConfig or ServletContext.

Method Summary

Modifier and Type	Method and Description
XsrfToken	getNewXsrfToken() Generates and returns new XSRF token.
void	init() Servlet initialization.

Methods inherited from class com.google.gwt.user.server.rpc.RemoteServiceServlet

checkPermutationStrongName, doGetSerializationPolicy, getCodeServerPolicyUrl, getRequestModuleBasePath, getSerializationPolicy, init, loadPolicyFromCodeServer, onAfterResponseSerialized, onBeforeRequestDeserialized, processCall, processCall, processPost, shouldCompressResponse

Methods inherited from class com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet

doPost, doUnexpectedFailure, getPermutationStrongName, getThreadLocalRequest, getThreadLocalResponse, onAfterRequestDeserialized, readContent

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, log, log

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString

Field Detail

COOKIE_NAME_PARAM

public static final String COOKIE_NAME_PARAM

Session cookie name initialization parameter.

See Also:

Constant Field Values

Constructor Detail

XsrfTokenServiceServlet

public XsrfTokenServiceServlet()

Default constructor.

XsrfTokenServiceServlet

public XsrfTokenServiceServlet(String sessionCookieName)

Alternative constructor that accepts session cookie name instead of getting it from ServletConfig or ServletContext.

Method Detail

getNewXsrfToken

public XsrfToken getNewXsrfToken()

Generates and returns new XSRF token.

Specified by:

getNewXsrfToken in interface XsrfTokenService

init

public void init()

Servlet initialization.

Overrides:

init in class javax.servlet.GenericServlet