+ return(0); /* FIXME return nonzero if something wonderful happened */
+}
+
+
+
+/*
+ * Callback function for perform_yadis_discovery()
+ * We're interested in HTTP headers returned from the server.
+ */
+size_t yadis_headerfunction(void *ptr, size_t size, size_t nmemb, void *userdata) {
+ char hdr[1024];
+
+ memcpy(hdr, ptr, (size*nmemb));
+ hdr[size*nmemb] = 0;
+
+ /* We are looking for a header like this:
+ * X-XRDS-Location: https://api.screenname.aol.com/auth/openid/xrds
+ */
+ if (!strncasecmp(hdr, "X-XRDS-Location:", 16)) {
+ safestrncpy(hdr, &hdr[16], sizeof(hdr));
+ striplt(hdr);
+ syslog(LOG_DEBUG, "\033[32m%s\033[0m", hdr);
+ /* FIXME now do something with it */
+ }
+
+ return(size * nmemb);
+}
+
+
+
+/* Attempt to perform Yadis discovery as specified in Yadis 1.0 section 6.2.5.
+ * If successful, returns nonzero and calls parse_xrds_document() to act upon the received data.
+ * If Yadis fails, returns 0 and does nothing else.
+ */
+int perform_yadis_discovery(StrBuf *YadisURL) {
+ int docbytes = (-1);
+ StrBuf *ReplyBuf = NULL;
+ int r;
+ CURL *curl;
+ CURLcode result;
+ char errmsg[1024] = "";
+ struct curl_slist *my_headers = NULL;
+
+ if (YadisURL == NULL) return(0);
+ if (StrLength(YadisURL) == 0) return(0);
+
+ ReplyBuf = NewStrBuf ();
+ if (ReplyBuf == 0) return(0);
+
+ curl = ctdl_openid_curl_easy_init(errmsg);
+ if (!curl) return(0);
+
+ curl_easy_setopt(curl, CURLOPT_URL, ChrPtr(YadisURL));
+ 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, NULL);
+ curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, yadis_headerfunction);
+
+ result = curl_easy_perform(curl);
+ if (result) {
+ syslog(LOG_DEBUG, "libcurl error %d: %s", result, errmsg);
+ }
+ curl_slist_free_all(my_headers);
+ curl_easy_cleanup(curl);
+
+ docbytes = StrLength(ReplyBuf);
+
+ /* FIXME here we need to handle Yadis 1.0 section 6.2.5.
+ *
+ * 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,
+ *
+ * Option 2: HTTP response-headers that include an X-XRDS-Location response-header, together with a
+ * document (NOTE: we can probably recurse for this)
+ *
+ * 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.
+ *
+ */
+
+ /*
+ * Option 4: the returned web page may *be* an XRDS document. Try to parse it.
+ */
+ r = 0;
+ if (docbytes >= 0) {
+ r = parse_xrds_document(ReplyBuf);
+ FreeStrBuf(&ReplyBuf);
+ }
+
+ return(r);