Source
File: wp-includes/class-wp-oembed.php
public function discover( $url ) {
$providers = array();
$args = array(
'limit_response_size' => 153600, // 150 KB
);
/**
* Filters oEmbed remote get arguments.
*
* @since 4.0.0
*
* @see WP_Http::request()
*
* @param array $args oEmbed remote get arguments.
* @param string $url URL to be inspected.
*/
$args = apply_filters( 'oembed_remote_get_args', $args, $url );
// Fetch URL content.
$request = wp_safe_remote_get( $url, $args );
$html = wp_remote_retrieve_body( $request );
if ( $html ) {
/**
* Filters the link types that contain oEmbed provider URLs.
*
* @since 2.9.0
*
* @param string[] $format Array of oEmbed link types. Accepts 'application/json+oembed',
* 'text/xml+oembed', and 'application/xml+oembed' (incorrect,
* used by at least Vimeo).
*/
$linktypes = apply_filters(
'oembed_linktypes',
array(
'application/json+oembed' => 'json',
'text/xml+oembed' => 'xml',
'application/xml+oembed' => 'xml',
)
);
// Strip <body>.
$html_head_end = stripos( $html, '</head>' );
if ( $html_head_end ) {
$html = substr( $html, 0, $html_head_end );
}
// Do a quick check.
$tagfound = false;
foreach ( $linktypes as $linktype => $format ) {
if ( stripos( $html, $linktype ) ) {
$tagfound = true;
break;
}
}
if ( $tagfound && preg_match_all( '#<link([^<>]+)/?>#iU', $html, $links ) ) {
foreach ( $links[1] as $link ) {
$atts = shortcode_parse_atts( $link );
if ( ! empty( $atts['type'] ) && ! empty( $linktypes[ $atts['type'] ] ) && ! empty( $atts['href'] ) ) {
$providers[ $linktypes[ $atts['type'] ] ] = htmlspecialchars_decode( $atts['href'] );
// Stop here if it's JSON (that's all we need).
if ( 'json' === $linktypes[ $atts['type'] ] ) {
break;
}
}
}
}
}
// JSON is preferred to XML.
if ( ! empty( $providers['json'] ) ) {
return $providers['json'];
} elseif ( ! empty( $providers['xml'] ) ) {
return $providers['xml'];
} else {
return false;
}
}