discover_pingback_server_uri( string $url, string $deprecated = '' ): string|false

Source

function discover_pingback_server_uri( $url, $deprecated = '' ) {	if ( ! empty( $deprecated ) ) {	_deprecated_argument( __FUNCTION__, '2.7.0' );	}	$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 a URL. This should never happen.	return false;	}	// Do not search for a pingback server on our own uploads.	$uploads_dir = wp_get_upload_dir();	if ( str_starts_with( $url, $uploads_dir['baseurl'] ) ) {	return false;	}	$response = wp_safe_remote_head(	$url,	array(	'timeout' => 2,	'httpversion' => '1.0',	)	);	if ( is_wp_error( $response ) ) {	return false;	}	if ( wp_remote_retrieve_header( $response, 'X-Pingback' ) ) {	return wp_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', wp_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 = wp_safe_remote_get(	$url,	array(	'timeout' => 2,	'httpversion' => '1.0',	)	);	if ( is_wp_error( $response ) ) {	return false;	}	$contents = wp_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; } 

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