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, java.io.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.

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

COOKIE_NAME_PARAM

public static final java.lang.String COOKIE_NAME_PARAM

Session cookie name initialization parameter.

See Also:

Constant Field Values

COOKIE_NAME_NOT_SET_ERROR_MSG

static final java.lang.String COOKIE_NAME_NOT_SET_ERROR_MSG

See Also:

Constant Field Values

XsrfTokenServiceServlet

public XsrfTokenServiceServlet()

Default constructor.

XsrfTokenServiceServlet

public XsrfTokenServiceServlet(java.lang.String sessionCookieName)

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

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