PHP Decode

<?php 
/* Developed by Kernel Team. 
   http://kernel-team.com 
*/ 
 
error_reporting(E_ERROR | E_PARSE | E_COMPILE_ERROR); 
$api_version = '5.3.0'; 
 
// comma separated list of whitelisted IPs 
$whitelist_ips = ""; 
 
// comma separated list of whitelisted referers 
$whitelist_referers = ""; 
 
// the number of seconds temp links are valid 
$ttl = 3600; 
 
###################################################################################### 
 
$config['cv']="d4c2088d32deb3534d5ffd035dc1d3ad"; 
 
if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) 
{ 
	$_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_X_FORWARDED_FOR']; 
	if (strpos($_SERVER['REMOTE_ADDR'], ',') !== false) 
	{ 
		$_SERVER['REMOTE_ADDR'] = trim(substr($_SERVER['REMOTE_ADDR'], 0, strpos($_SERVER['REMOTE_ADDR'], ','))); 
	} 
} elseif (isset($_SERVER['HTTP_X_REAL_IP'])) 
{ 
	$_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_X_REAL_IP']; 
} 
 
if ($_REQUEST['action'] == '' && $_REQUEST['file'] == '') 
{ 
	echo "connected."; 
	die; 
} elseif ($_REQUEST['action'] == 'version') 
{ 
	echo $api_version; 
	die; 
} elseif ($_REQUEST['action'] == 'ip') 
{ 
	echo $_SERVER['REMOTE_ADDR']; 
	die; 
} elseif ($_REQUEST['action'] == 'path') 
{ 
	if ($_REQUEST['cv'] != $config['cv']) 
	{ 
		sleep(1); 
		http_response_code(403); 
		header("KVS-Errno: 2"); 
		echo "Access denied (errno 2)"; 
		die; 
	} 
	echo dirname($_SERVER['SCRIPT_FILENAME']); 
} elseif ($_REQUEST['action'] == 'status') 
{ 
	if (function_exists('sys_getloadavg')) 
	{ 
		$load = sys_getloadavg(); 
	} else 
	{ 
		$load = [0]; 
	} 
	$load = floatval($load[0]); 
	if ($_REQUEST['content_path'] != '' && (is_dir(dirname($_SERVER['SCRIPT_FILENAME']) . "/$_REQUEST[content_path]") || is_link(dirname($_SERVER['SCRIPT_FILENAME']) . "/$_REQUEST[content_path]"))) 
	{ 
		$total_space = @disk_total_space(dirname($_SERVER['SCRIPT_FILENAME']) . "/$_REQUEST[content_path]"); 
		$free_space = @disk_free_space(dirname($_SERVER['SCRIPT_FILENAME']) . "/$_REQUEST[content_path]"); 
	} else 
	{ 
		$total_space = @disk_total_space(dirname($_SERVER['SCRIPT_FILENAME'])); 
		$free_space = @disk_free_space(dirname($_SERVER['SCRIPT_FILENAME'])); 
	} 
	echo "$load|$total_space|$free_space"; 
	die; 
} elseif ($_REQUEST['action'] == 'time') 
{ 
	echo time(); 
	die; 
} elseif ($_REQUEST['action'] == 'check') 
{ 
	$content_path = $_REQUEST['content_path']; 
	$paths = explode('||', $_REQUEST['files']); 
	foreach ($paths as $path) 
	{ 
		if ($path) 
		{ 
			$path_rec = explode('|', $path); 
			if ($content_path && $path_rec[0]) 
			{ 
				$path_rec[0] = "$content_path/$path_rec[0]"; 
			} 
			if ($path_rec[1] > 0) 
			{ 
				if (sprintf("%.0f", @filesize($path_rec[0])) != $path_rec[1]) 
				{ 
					echo "$path_rec[0] (expected size $path_rec[1])"; 
					die; 
				} 
			} else 
			{ 
				if (sprintf("%.0f", @filesize($path_rec[0])) < 1) 
				{ 
					echo $path_rec[0]; 
					die; 
				} 
			} 
		} 
	} 
	echo '1'; 
	die; 
} elseif ($_REQUEST['file'] <> '') 
{ 
	$time = intval($_REQUEST['time']); 
	$limit = intval($_REQUEST['lr']); 
	$cv = trim($_REQUEST['cv2']); 
	$target_file = rawurldecode($_REQUEST['file']); 
	$is_download = trim($_GET['download']); 
 
	if (strpos($target_file, 'B64') === 0) 
	{ 
		$target_file_info = @unserialize(base64_decode(substr($target_file, 3))); 
 
		if (!isset($target_file_info['time'], $target_file_info['cv'], $target_file_info['file'])) 
		{ 
			http_response_code(403); 
			header("KVS-Errno: 2"); 
			echo "Access denied (errno 2)"; 
			die; 
		} 
 
		if ($target_file_info['time'] < time() - $ttl || $target_file_info['time'] > time() + $ttl) 
		{ 
			http_response_code(403); 
			header("KVS-Errno: 3"); 
			echo "Access denied (errno 3)"; 
			die; 
		} 
 
		$allowed_ips = explode(',', trim($_COOKIE["kt_remote_ips"])); 
		if (md5($target_file_info['time'] . $target_file_info['limit'] . $target_file_info['file'] . $_SERVER['REMOTE_ADDR'] . $config['cv']) !== $target_file_info['cv']) 
		{ 
			$ip_valid = false; 
			foreach ($allowed_ips as $allowed_ip) 
			{ 
				$allowed_ip = explode("||", $allowed_ip); 
				if ($allowed_ip[1] === md5($allowed_ip[0] . $config['cv'])) 
				{ 
					if (md5($target_file_info['time'] . $target_file_info['limit'] . $target_file_info['file'] . $allowed_ip[0] . $config['cv']) === $target_file_info['cv']) 
					{ 
						$ip_valid = true; 
						break; 
					} 
				} 
			} 
			if (!$ip_valid && $whitelist_ips) 
			{ 
				$whitelist_ips = array_map('trim', explode(',', trim($whitelist_ips))); 
				foreach ($whitelist_ips as $whitelist_ip) 
				{ 
					if ($whitelist_ip == $_SERVER['REMOTE_ADDR'] || md5($target_file_info['time'] . $target_file_info['limit'] . $target_file_info['file'] . $whitelist_ip . $config['cv']) === $target_file_info['cv']) 
					{ 
						$ip_valid = true; 
						break; 
					} 
				} 
			} 
			if (!$ip_valid) 
			{ 
				http_response_code(403); 
				header("KVS-Errno: 4"); 
				header("KVS-IP: $_SERVER[REMOTE_ADDR]"); 
				echo "Access denied (errno 4)"; 
				die; 
			} 
		} else 
		{ 
			$has_ip_cookie = false; 
			foreach ($allowed_ips as $allowed_ip) 
			{ 
				$allowed_ip = explode("||", $allowed_ip); 
				if ($allowed_ip[0] == $_SERVER['REMOTE_ADDR']) 
				{ 
					$has_ip_cookie = true; 
				} 
			} 
			if (!$has_ip_cookie) 
			{ 
				$allowed_ips[] = $_SERVER['REMOTE_ADDR'] . '||' . md5($_SERVER['REMOTE_ADDR'] . $config['cv']); 
				if (version_compare(PHP_VERSION, '7.3.0') >= 0) 
				{ 
					setcookie("kt_remote_ips", implode(',', $allowed_ips), ['expires' => time() + $ttl, 'path' => '/', 'samesite' => 'Lax']); 
				} else 
				{ 
					setcookie("kt_remote_ips", implode(',', $allowed_ips), time() + $ttl, "/"); 
				} 
			} 
		} 
 
		$target_file = $target_file_info['file']; 
		$limit = $target_file_info['limit']; 
	} else 
	{ 
		if ($time < time() - $ttl || $time > time() + $ttl) 
		{ 
			http_response_code(403); 
			header("KVS-Errno: 3"); 
			echo "Access denied (errno 3)"; 
			die; 
		} 
 
		if (md5($time . $limit . $config['cv']) !== $cv) 
		{ 
			http_response_code(403); 
			header("KVS-Errno: 4"); 
			echo "Access denied (errno 4)"; 
			die; 
		} 
 
		if ($_SERVER['HTTP_REFERER'] != '' && $_REQUEST['cv3'] != '') 
		{ 
			$ref_host = parse_url(str_replace('www.', '', $_SERVER['HTTP_REFERER']), PHP_URL_HOST); 
			if ($ref_host != '' && $ref_host != $_SERVER['SERVER_NAME'] && md5($ref_host . $config['cv']) !== trim($_REQUEST['cv3'])) 
			{ 
				$referer_valid = false; 
				$whitelist_referers = array_map('trim', explode(',', trim($whitelist_referers))); 
				foreach ($whitelist_referers as $whitelist_referer) 
				{ 
					if ($whitelist_referer == $ref_host) 
					{ 
						$referer_valid = true; 
						break; 
					} 
				} 
 
				if (!$referer_valid) 
				{ 
					http_response_code(403); 
					header("KVS-Errno: 5"); 
					echo "Access denied (errno 5)"; 
					die; 
				} 
			} 
		} 
 
		if (md5($target_file . $config['cv']) !== trim($_REQUEST['cv4'])) 
		{ 
			http_response_code(403); 
			header("KVS-Errno: 6"); 
			echo "Access denied (errno 6)"; 
			die; 
		} 
	} 
 
	if (floatval($_REQUEST['start']) > 0) 
	{ 
		$start_str = "?start=" . floatval($_REQUEST['start']); 
	} 
 
	if (strpos($target_file, ".flv") !== false) 
	{ 
		header("Content-Type: video/x-flv"); 
	} elseif (strpos($target_file, ".mp4") !== false) 
	{ 
		header("Content-Type: video/mp4"); 
	} elseif (strpos($target_file, ".webm") !== false) 
	{ 
		header("Content-Type: video/webm"); 
	} elseif (strpos($target_file, ".jpg") !== false) 
	{ 
		header("Content-Type: image/jpeg"); 
	} elseif (strpos($target_file, ".gif") !== false) 
	{ 
		header("Content-Type: image/gif"); 
	} elseif (strpos($target_file, ".zip") !== false) 
	{ 
		header("Content-Type: application/zip"); 
	} else 
	{ 
		header("Content-Type: application/octet-stream"); 
	} 
 
	if (intval($limit) > 0) 
	{ 
		header("X-Accel-Limit-Rate: $limit"); 
	} 
	$short_file_name = basename($target_file); 
	if ($_REQUEST['download_filename'] <> '') 
	{ 
		$short_file_name = $_REQUEST['download_filename']; 
	} 
	if ($is_download == 'true') 
	{ 
		header("Content-Disposition: attachment; filename=\"$short_file_name\""); 
	} else 
	{ 
		header("Content-Disposition: inline; filename=\"$short_file_name\""); 
	} 
	header("X-Accel-Redirect: $target_file{$start_str}"); 
} ?>