/**
* Gets the Pingback endpoint URI provided by a web page specified by URL
*
* @return string|boolean Returns the Pingback endpoint URI if found or false
*/
function get_endpoint_uri($url)
{
// First check for an X-pingback header
if (!($response = nxt_remote_head($url))) {
return false;
}
if (!($content_type = nxt_remote_retrieve_header($response, 'content-type'))) {
return false;
}
if (preg_match('#(image|audio|video|model)/#is', $content_type)) {
return false;
}
if ($x_pingback = nxt_remote_retrieve_header($response, 'x-pingback')) {
return trim($x_pingback);
}
// Fall back to extracting it from the HTML link
if (!($response = nxt_remote_get($url))) {
return false;
}
if (200 !== nxt_remote_retrieve_response_code($response)) {
return false;
}
if ('' === ($response_body = nxt_remote_retrieve_body($response))) {
return false;
}
if (!preg_match_all('@<link([^>]+)>@im', $response_body, $response_links)) {
return false;
}
foreach ($response_links[1] as $response_link_attributes) {
$_link = array('rel' => false, 'href' => false);
$response_link_attributes = preg_split('@\\s+@im', $response_link_attributes, -1, PREG_SPLIT_NO_EMPTY);
foreach ($response_link_attributes as $response_link_attribute) {
if ($_link['rel'] == 'pingback' && $_link['href']) {
return $_link['href'];
}
if (strpos($response_link_attribute, '=', 1) !== false) {
list($_key, $_value) = explode('=', $response_link_attribute, 2);
$_link[strtolower($_key)] = trim($_value, "'\"");
}
}
}
// Fail
return false;
}
/**
* Finds a pingback server URI based on the given URL.
*
* Checks the HTML for the rel="pingback" link and x-pingback headers. It does
* a check for the x-pingback headers first and returns that, if available. The
* check for the rel="pingback" has more overhead than just the header.
*
* @since 1.5.0
*
* @param string $url URL to ping.
* @param int $deprecated Not Used.
* @return bool|string False on failure, string containing URI on success.
*/
function discover_pingback_server_uri($url, $deprecated = '')
{
if (!empty($deprecated)) {
_deprecated_argument(__FUNCTION__, '2.7');
}
$pingback_str_dquote = 'rel="pingback"';
$pingback_str_squote = 'rel=\'pingback\'';
/** @todo Should use Filter Extension or custom preg_match instead. */
$parsed_url = parse_url($url);
if (!isset($parsed_url['host'])) {
// Not an URL. This should never happen.
return false;
}
//Do not search for a pingback server on our own uploads
$uploads_dir = nxt_upload_dir();
if (0 === strpos($url, $uploads_dir['baseurl'])) {
return false;
}
$response = nxt_remote_head($url, array('timeout' => 2, 'httpversion' => '1.0'));
if (is_nxt_error($response)) {
return false;
}
if (nxt_remote_retrieve_header($response, 'x-pingback')) {
return nxt_remote_retrieve_header($response, 'x-pingback');
}
// Not an (x)html, sgml, or xml page, no use going further.
if (preg_match('#(image|audio|video|model)/#is', nxt_remote_retrieve_header($response, 'content-type'))) {
return false;
}
// Now do a GET since we're going to look in the html headers (and we're sure its not a binary file)
$response = nxt_remote_get($url, array('timeout' => 2, 'httpversion' => '1.0'));
if (is_nxt_error($response)) {
return false;
}
$contents = nxt_remote_retrieve_body($response);
$pingback_link_offset_dquote = strpos($contents, $pingback_str_dquote);
$pingback_link_offset_squote = strpos($contents, $pingback_str_squote);
if ($pingback_link_offset_dquote || $pingback_link_offset_squote) {
$quote = $pingback_link_offset_dquote ? '"' : '\'';
$pingback_link_offset = $quote == '"' ? $pingback_link_offset_dquote : $pingback_link_offset_squote;
$pingback_href_pos = @strpos($contents, 'href=', $pingback_link_offset);
$pingback_href_start = $pingback_href_pos + 6;
$pingback_href_end = @strpos($contents, $quote, $pingback_href_start);
$pingback_server_url_len = $pingback_href_end - $pingback_href_start;
$pingback_server_url = substr($contents, $pingback_href_start, $pingback_server_url_len);
// We may find rel="pingback" but an incomplete pingback URL
if ($pingback_server_url_len > 0) {
// We got it!
return $pingback_server_url;
}
}
return false;
}
