http://hdknr.ubu/blog/openid/ でXRDをサポートしていないから、らしいです。(@kthrtty)

出力しているテンプレートを見る。

hdknr@LennyOne:~/python-openid-2.2.4/examples/djopenid$ vi templates/server/trust.html

{% ifequal trust_root_valid "DISCOVERY_FAILED" %}
  <p>The site <tt>{{ trust_root|escape }}</tt> has requested verification
  of your OpenID.  However, <tt>{{ trust_root|escape }}</tt> does not
  implement OpenID 2.0’s relying party verification mechanism.  Please use
  extra caution in deciding whether to release information to this party,
  and ask <tt>{{ trust_root|escape }}</tt> to implement relying party
  verification for your future transactions.</p>

  {% include "server/pape_request_info.html" %}
{% endifequal %}

対応するヴューの処理

hdknr@LennyOne:~/python-openid-2.2.4/examples/djopenid$ vi server/views.py

from openid.server.trustroot import verifyReturnTo

def showDecidePage(request, openid_request):
    """
    Render a page to the user so a trust decision can be made.

    @type openid_request: openid.server.server.CheckIDRequest
    """
    trust_root = openid_request.trust_root    #### RELM
    return_to = openid_request.return_to      #### RETURN_TO

    try:
        # Stringify because template’s ifequal can only compare to strings.
        trust_root_valid = verifyReturnTo(trust_root, return_to) \
                           and "Valid" or "Invalid"
    except DiscoveryFailure, err:
        trust_root_valid = "DISCOVERY_FAILED"
    except HTTPFetchingError, err:
        trust_root_valid = "Unreachable"

    pape_request = pape.Request.fromOpenIDRequest(openid_request)

    return direct_to_template(
        request,
        ‘server/trust.html’,
        {’trust_root’: trust_root,
         ‘trust_handler_url’:getViewURL(request, processTrustResult),
         ‘trust_root_valid’: trust_root_valid,
         ‘pape_request’: pape_request,

実際は次のように呼び出し。

verifyReturnTo(http://hdknr.ubu/blog/openid/,
http://hdknr.ubu/blog/openid/?openid=consumer&janrain_nonce=2009-07-01T07%3A40%3A59Z9ns9Iw&openid1_claimed_id=http%3A%2F%

2Fhdknr.deb%2Fserver%2Fuser%2F)

_vrfyでDiscoveryFailureが発生。

def verifyReturnTo(realm_str, return_to, _vrfy=getAllowedReturnURLs):
    """Verify that a return_to URL is valid for the given realm.

    This function builds a discovery URL, performs Yadis discovery on
    it, makes sure that the URL does not redirect, parses out the
    return_to URLs, and finally checks to see if the current return_to
    URL matches the return_to.

    @raises DiscoveryFailure: When Yadis discovery fails
    @returns: True if the return_to URL is valid for the realm

    @since: 2.1.0
    """
    realm = TrustRoot.parse(realm_str)

    if realm is None:
        # The realm does not parse as a URL pattern
        return False

    try:
        allowable_urls = _vrfy(realm.buildDiscoveryURL())
    except RealmVerificationRedirected, err:
        oidutil.log(str(err))
        return False

    if returnToMatches(allowable_urls, return_to):
        return True
    else:
        oidutil.log("Failed to validate return_to %r for realm %r, was not "
                    "in %s" % (return_to, realm_str, allowable_urls))
        return False

デフォルトでは、_vrfyがgetAllowedReturnURLs関数。

from openid.yadis import services

def getAllowedReturnURLs(relying_party_url):
    (rp_url_after_redirects, return_to_urls) = services.getServiceEndpoints(
        relying_party_url, _extractReturnURL)    #ここでだめな模様。

    if rp_url_after_redirects != relying_party_url:
        # Verification caused a redirect
        raise RealmVerificationRedirected(
            relying_party_url, rp_url_after_redirects)

    return return_to_urls

yadis/service.py

def getServiceEndpoints(input_url, flt=None):
    result = discover(input_url)
    try:
        endpoints = applyFilter(result.normalized_uri,
                                result.response_text, flt)
    except XRDSError, err:
        raise DiscoveryFailure(str(err), None)
    return (result.normalized_uri, endpoints)

def applyFilter(normalized_uri, xrd_data, flt=None):
    flt = mkFilter(flt)
    et = parseXRDS(xrd_data)                              #<—– ここで例外。
    endpoints = []
    for service_element in iterServices(et):
        endpoints.extend(
            flt.getServiceEndpoints(normalized_uri, service_element))

    return endpoints

yadis/etxrd.py　どうやらtext(xrd_data)がElementTreeでXMLにパースできないもよう。
なぜならばWordPressのトップページがHTMLだから。

def parseXRDS(text):
    """Parse the given text as an XRDS document.

    @return: ElementTree containing an XRDS document

    @raises XRDSError: When there is a parse error or the document does
        not contain an XRDS.
    """
    try:
        element = ElementTree.XML(text)
    except XMLError, why:
        exc = XRDSError(‘Error parsing document as XML’) #<——— ここ
        exc.reason = why
        raise exc
    else:
        tree = ElementTree.ElementTree(element)
        if not isXRDS(tree):
            raise XRDSError(‘Not an XRDS document’)

        return tree

ということです。

WordPressでリクエストヘッダーを見てみると。 ( index.php にデバックコードを入れる)
root@ubuntu-vbox:/home/sites/hdknr.ubu/wordpress_blog_openid# !ta
tail -f /var/log/messages

Jul  1 17:40:40 ubuntu-vbox OpenID[9446]: APACHE REQUEST HEADER:Accept-Encoding:identity
Jul  1 17:40:40 ubuntu-vbox OpenID[9446]: APACHE REQUEST HEADER:Host:hdknr.ubu
Jul  1 17:40:40 ubuntu-vbox OpenID[9446]: APACHE REQUEST HEADER:Connection:close
Jul  1 17:40:40 ubuntu-vbox OpenID[9446]: APACHE REQUEST HEADER:Accept:text/html; q=0.3, application/xhtml+xml; q=0.5, application/xrds+xml
Jul  1 17:40:40 ubuntu-vbox OpenID[9446]: APACHE REQUEST HEADER:User-Agent:python-openid/2.2.1 (linux2) Python-urllib/2.5

ですので、Acceptにapplication/xrds+xmlがしていされたら、WordPressのトップページでXRDSをダウンロードするようにすれば対応可能でしょう。