关于http断点续传相关的RANGE这个header

<?php
//1.txt内容“1234567890”
socketData('127.0.0.1','/1.txt',80,"RANGE:bytes=0-0\r\n");
socketData('127.0.0.1','/1.txt',80,"RANGE:bytes=9-9\r\n");
function socketData($host,$url,$port = 80,$headers='',$data='')
{
$fp = fsockopen($host, $port, $errno, $errstr, 15);

if (!$fp) {
return false;
} else {
$out = ($data?'POST':'GET').' '.$url." HTTP/1.1\r\n";
$out .= 'Host: '.$host."\r\n";
$out .= $headers;

if(strlen($data)>=3){
$out .= 'Content-Length: '.strlen($data)."\r\n";
$out .= 'Content-Type: application/x-www-form-urlencoded'."\r\n";
}

$out .= "Connection: Close\r\n\r\n".$data;
fwrite($fp, $out);
$rtn = "";

while (!feof($fp)) {
$get = fread($fp, 1024);
$rtn.= $get;
}

fclose($fp);
}
$strs = explode("\r\n\r\n", $rtn);
echo $strs[1].chr(10);
}