I have been trying to set up an OpenID provider on my server which integrates with LDAP. I found Community-ID (http://source.keyboard-monkeys.org/projects/show/communityid) which seems to do exactly what I want with the exception that it does not work with the stackoverflow website. Whenever I try and log in to stackoverflow, I enter the identity URL, get taken to my servers login page, then redirected back to stackoverflow at which point I am presented with:
Unable to log in with your OpenID provider: Unexpected HTTP status code 500 InternalServerError received in direct response.
The problem is easy to reproduce with the public community-id provider: http://www.community-id.org/. The only other site I have tested it with is slashdot which works fine. I have filed a bug with the community-id team but based on some testing I did at (http://test-id.net) I think the problem is that the community-id provider is not "sending properly formatted error responses to invalid direct request messages" (from test (http://test-id.net/OP/DirectMessageErrors.aspx)) as the error message is the same. Logs have not been very helpful (apache error/access, community id logs, etc) and I obviously cannot see the stackoverflow server logs.
I am not sure who's bug this is, community-id's or stackoverflow's. Has anybody seen anything similar before? Any suggestions for an alternate OpenID provider which supports an LDAP backend?