_make_web_ftp_clickable_cb() WordPress Function

function _make_web_ftp_clickable_cb( $matches ) {
	$ret  = '';
	$dest = $matches[2];
	$dest = 'http://' . $dest;

	// Removed trailing [.,;:)] from URL.
	$last_char = substr( $dest, -1 );
	if ( in_array( $last_char, array( '.', ',', ';', ':', ')' ), true ) === true ) {
		$ret  = $last_char;
		$dest = substr( $dest, 0, strlen( $dest ) - 1 );
	}

	$dest = esc_url( $dest );
	if ( empty( $dest ) ) {
		return $matches[0];
	}

	if ( 'comment_text' === current_filter() ) {
		$rel = 'nofollow ugc';
	} else {
		$rel = 'nofollow';
	}

	/** This filter is documented in wp-includes/formatting.php */
	$rel = apply_filters( 'make_clickable_rel', $rel, $dest );
	$rel = esc_attr( $rel );

	return $matches[1] . "<a href=\"$dest\" rel=\"$rel\">$dest</a>$ret";
}