+ $isRedirected = false;
+ /**
+ * cURL callback function for CURLOPT_WRITEFUNCTION (called during the download).
+ *
+ * While downloading the remote page, we check that the HTTP code is 200 and content type is 'html/text'
+ * Then we extract the title and the charset and stop the download when it's done.
+ *
+ * @param resource $ch cURL resource
+ * @param string $data chunk of data being downloaded
+ *
+ * @return int|bool length of $data or false if we need to stop the download
+ */
+ return function(&$ch, $data) use ($curlGetInfo, &$charset, &$title, &$isRedirected) {
+ $responseCode = $curlGetInfo($ch, CURLINFO_RESPONSE_CODE);
+ if (!empty($responseCode) && in_array($responseCode, [301, 302])) {
+ $isRedirected = true;
+ return strlen($data);
+ }
+ if (!empty($responseCode) && $responseCode !== 200) {
+ return false;
+ }
+ // After a redirection, the content type will keep the previous request value
+ // until it finds the next content-type header.
+ if (! $isRedirected || strpos(strtolower($data), 'content-type') !== false) {
+ $contentType = $curlGetInfo($ch, CURLINFO_CONTENT_TYPE);
+ }
+ if (!empty($contentType) && strpos($contentType, 'text/html') === false) {
+ return false;
+ }
+ if (!empty($contentType) && empty($charset)) {
+ $charset = header_extract_charset($contentType);
+ }
+ if (empty($charset)) {
+ $charset = html_extract_charset($data);
+ }
+ if (empty($title)) {
+ $title = html_extract_title($data);
+ }
+ // We got everything we want, stop the download.
+ if (!empty($responseCode) && !empty($contentType) && !empty($charset) && !empty($title)) {
+ return false;
+ }
+
+ return strlen($data);
+ };