/**
* 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 0.0.1
*
* @param string $url URL to ping.
* @param int $deprecated Not Used.
* @return false|string False on failure, string containing URI on success.
*/
function discover_pingback_server_uri($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
$uploads_dir = hq_upload_dir();
if (0 === strpos($url, $uploads_dir['baseurl'])) {
return false;
}
$response = hq_safe_remote_head($url, array('timeout' => 2, 'httpversion' => '1.0'));
if (is_hq_error($response)) {
return false;
}
if (hq_remote_retrieve_header($response, 'x-pingback')) {
return hq_remote_retrieve_header($response, 'x-pingback');
}
// Not an (x)html, sgml, or xml page, no use going further.
if (preg_match('#(image|audio|video|model)/#is', hq_remote_retrieve_header($response, 'content-type'))) {
return false;
}
// Now do a GET since we're going to look in the html headers (and we're sure it's not a binary file)
$response = hq_safe_remote_get($url, array('timeout' => 2, 'httpversion' => '1.0'));
if (is_hq_error($response)) {
return false;
}
$contents = hq_remote_retrieve_body($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;
}
/**
* Retrieve HTTP Headers from URL.
*
* @since 0.0.1
*
* @param string $url URL to retrieve HTTP headers from.
* @param bool $deprecated Not Used.
* @return bool|string False on failure, headers on success.
*/
function hq_get_http_headers($url, $deprecated = false)
{
if (!empty($deprecated)) {
_deprecated_argument(__FUNCTION__, '2.7');
}
$response = hq_safe_remote_head($url);
if (is_hq_error($response)) {
return false;
}
return hq_remote_retrieve_headers($response);
}