Auth_OpenID_GenericConsumer::_verifyDiscoverySingle PHP Method

    function _verifyDiscoverySingle($endpoint, $to_match)
    {
        // Every type URI that's in the to_match endpoint has to be
        // present in the discovered endpoint.
        foreach ($to_match->type_uris as $type_uri) {
            if (!$endpoint->usesExtension($type_uri)) {
                return new Auth_OpenID_TypeURIMismatch($endpoint, "Required type " . $type_uri . " not present");
            }
        }
        // Fragments do not influence discovery, so we can't compare a
        // claimed identifier with a fragment to discovered
        // information.
        list($defragged_claimed_id, $_) = Auth_OpenID::urldefrag($to_match->claimed_id);
        if ($defragged_claimed_id != $endpoint->claimed_id) {
            return new Auth_OpenID_FailureResponse($endpoint, sprintf('Claimed ID does not match (different subjects!), ' . 'Expected %s, got %s', $defragged_claimed_id, $endpoint->claimed_id));
        }
        if ($to_match->getLocalID() != $endpoint->getLocalID()) {
            return new Auth_OpenID_FailureResponse($endpoint, sprintf('local_id mismatch. Expected %s, got %s', $to_match->getLocalID(), $endpoint->getLocalID()));
        }
        // If the server URL is None, this must be an OpenID 1
        // response, because op_endpoint is a required parameter in
        // OpenID 2. In that case, we don't actually care what the
        // discovered server_url is, because signature checking or
        // check_auth should take care of that check for us.
        if ($to_match->server_url === null) {
            if ($to_match->preferredNamespace() != Auth_OpenID_OPENID1_NS) {
                return new Auth_OpenID_FailureResponse($endpoint, "Preferred namespace mismatch (bug)");
            }
        } else {
            if ($to_match->server_url != $endpoint->server_url) {
                return new Auth_OpenID_FailureResponse($endpoint, sprintf('OP Endpoint mismatch. Expected %s, got %s', $to_match->server_url, $endpoint->server_url));
            }
        }
        return null;
    }