Source

File: wp-includes/functions.php

function wp_get_http_headers( $url, $deprecated = false ) {
	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '2.7.0' );
	}

	$response = wp_safe_remote_head( $url );

	if ( is_wp_error( $response ) ) {
		return false;
	}

	return wp_remote_retrieve_headers( $response );
}