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
        }
    });