liferay portlet: how to use autologin (alternatives also welcome)

Question

I'm using an external token service to validate my users and they then get redirected to the portal (portal url + some get parameters).
Now I would like to log these users in the portal. Since the external authentication service is outside of my control I can't just tie it in with the portal login. And since I can't decrypt the portal user account password I can't just create an ext-plugin and log in through that.

So I searched a bit and stumbled upon the fact that liferay has an autologin.
Now I was wondering:

1. can I just use this in a normal portlet, or does it also need to be in ext (still don't know how to exactly do that)
2. which session variables/cookies do I need to make?
3. does anyone have a code snippet/tutorial since I have yet to find a complete one.
4. how feasible is this when keeping future versions of liferay in mind?

Answer 1

What's this "external token service"? Is it an SSO (Single Sign On) system that Liferay happens to work with out of the box?

Take a look at liferay's web.xml - there's a lot of SSO filters in there - you'll find the implementation in liferay's source code. These filters are used for handling SSO systems and do everything that's necessary to log someone in without username/password validation in the portal itself. You might be able to find the variant that best suites your needs here.

Answer 2

Create your own filter (implements com.liferay.portal.security.auth.AutoLogin):

public class YourAutoLogin implements AutoLogin {...}

and implement login method with code:

public String[] login(HttpServletRequest req, HttpServletResponse resp)
  throws AutoLoginException {
    ...
    req.getSession().setAttribute(WebKeys.USER_ID,
    Long.valueOf(authenticatedUserId));
    ...
}

where authenticatedUserId is equal to ID of the authenticated user in Liferay directory.

Add you filter as hook (file /WEB-INF/classes/portal.properties in your web app):

auto.login.hooks=com.company.filter.YourAutoLogin