+ if (xrds.selected_service_priority < INT_MAX) {
+ if (oiddata->op_url == NULL) {
+ oiddata->op_url = NewStrBuf();
+ }
+ FlushStrBuf(oiddata->op_url);
+ StrBufAppendBuf(oiddata->op_url, xrds.selected_service_uri, 0);
+ return_value = openid_disco_xrds;
+ }
+
+ FreeStrBuf(&xrds.CharData);
+ FreeStrBuf(&xrds.current_service_uri);
+ FreeStrBuf(&xrds.selected_service_uri);
+
+ return(return_value);
+}
+
+
+/*
+ * Callback function for perform_openid2_discovery()
+ * We're interested in the X-XRDS-Location: header.
+ */
+size_t yadis_headerfunction(void *ptr, size_t size, size_t nmemb, void *userdata) {
+ char hdr[1024];
+ StrBuf **x_xrds_location = (StrBuf **) userdata;
+
+ memcpy(hdr, ptr, (size*nmemb));
+ hdr[size*nmemb] = 0;
+
+ if (!strncasecmp(hdr, "X-XRDS-Location:", 16)) {
+ *x_xrds_location = NewStrBufPlain(&hdr[16], ((size*nmemb)-16));
+ StrBufTrim(*x_xrds_location);
+ }
+
+ return(size * nmemb);
+}
+
+
+/* Attempt to perform Yadis discovery as specified in Yadis 1.0 section 6.2.5.
+ *
+ * If Yadis fails, we then attempt HTML discovery using the same document.
+ *
+ * If successful, returns nonzero and calls parse_xrds_document() to act upon the received data.
+ * If fails, returns 0 and does nothing else.
+ */
+int perform_openid2_discovery(StrBuf *SuppliedURL) {
+ ctdl_openid *oiddata = (ctdl_openid *) CC->openid_data;
+ int docbytes = (-1);
+ StrBuf *ReplyBuf = NULL;
+ int return_value = 0;
+ CURL *curl;
+ CURLcode result;
+ char errmsg[1024] = "";
+ struct curl_slist *my_headers = NULL;
+ StrBuf *x_xrds_location = NULL;
+
+ if (!SuppliedURL) return(0);
+ syslog(LOG_DEBUG, "openid: perform_openid2_discovery(%s)", ChrPtr(SuppliedURL));
+ if (StrLength(SuppliedURL) == 0) return(0);
+
+ ReplyBuf = NewStrBuf();
+ if (!ReplyBuf) return(0);
+
+ curl = ctdl_openid_curl_easy_init(errmsg);
+ if (!curl) return(0);
+
+ curl_easy_setopt(curl, CURLOPT_URL, ChrPtr(SuppliedURL));
+ curl_easy_setopt(curl, CURLOPT_WRITEDATA, ReplyBuf);
+ curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, CurlFillStrBuf_callback);
+
+ my_headers = curl_slist_append(my_headers, "Accept:"); /* disable the default Accept: header */
+ my_headers = curl_slist_append(my_headers, "Accept: application/xrds+xml");
+ curl_easy_setopt(curl, CURLOPT_HTTPHEADER, my_headers);
+
+ curl_easy_setopt(curl, CURLOPT_WRITEHEADER, &x_xrds_location);
+ curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, yadis_headerfunction);
+
+ result = curl_easy_perform(curl);
+ if (result) {
+ syslog(LOG_DEBUG, "openid: libcurl error %d: %s", result, errmsg);
+ }
+ curl_slist_free_all(my_headers);
+ curl_easy_cleanup(curl);
+ docbytes = StrLength(ReplyBuf);
+
+ /*
+ * The response from the server will be one of:
+ *
+ * Option 1: An HTML document with a <head> element that includes a <meta> element with http-equiv
+ * attribute, X-XRDS-Location,
+ *
+ * Does any provider actually do this? If so then we will implement it in the future.
+ */
+
+ /*
+ * Option 2: HTTP response-headers that include an X-XRDS-Location response-header,
+ * together with a document.
+ * Option 3: HTTP response-headers only, which MAY include an X-XRDS-Location response-header,
+ * a contenttype response-header specifying MIME media type,
+ * application/xrds+xml, or both.
+ *
+ * If the X-XRDS-Location header was delivered, we know about it at this point...
+ */
+ if ( (x_xrds_location)
+ && (strcmp(ChrPtr(x_xrds_location), ChrPtr(SuppliedURL)))
+ ) {
+ syslog(LOG_DEBUG, "openid: X-XRDS-Location: %s ... recursing!", ChrPtr(x_xrds_location));
+ return_value = perform_openid2_discovery(x_xrds_location);
+ FreeStrBuf(&x_xrds_location);
+ }
+
+ /*
+ * Option 4: the returned web page may *be* an XRDS document. Try to parse it.
+ */
+ if ( (return_value == 0) && (docbytes >= 0)) {
+ return_value = parse_xrds_document(ReplyBuf);
+ }
+
+ /*
+ * Option 5: if all else fails, attempt HTML based discovery.
+ */
+ if ( (return_value == 0) && (docbytes >= 0)) {
+ if (oiddata->op_url == NULL) {
+ oiddata->op_url = NewStrBuf();
+ }
+ extract_link(oiddata->op_url, HKEY("openid2.provider"), ReplyBuf);
+ if (StrLength(oiddata->op_url) > 0) {
+ return_value = openid_disco_html;
+ }
+ }
+
+ if (ReplyBuf != NULL) {
+ FreeStrBuf(&ReplyBuf);
+ }
+ return(return_value);