为什么出现 400 Bad Request 用的是ngix? 400 报错

换了个php环境 

<?php
	//error_reporting(0);
	$fp=fsockopen("127.0.0.1",80);     //打开数据流
	if(!$fp){
		echo "unable to open";
	}
	else{
		fwrite($fp,"get/http/1.0rnrn");
		stream_set_timeout($fp,2);
		$res = fread($fp,2000);
		$info = stream_get_meta_data($fp);
		fclose($fp);
		if($info['timed_out']){
			echo 'connection time out!';
		}
		else{
			echo $res;
		}
	}
?>

为什么出现400 Bad Request nginx/0.8.52 错误