Simple FTP Server written in PHP to receive images from Hikvision cameras

ftp_server.php

<?php

require __DIR__ . '/vendor/autoload.php';

use Amp\Loop;
use Amp\Socket\Socket;
use function Amp\asyncCall;

$port1 = 1021; // Primary FTP port (you list it in Hikvision), it receives FTP commands
$port2 = 1022; // Secondary FTP port (for receiving binary data - images)

$sockets = 0;

// this script will automatically exit if you update it
$mymtime = filemtime(__FILE__);

Loop::repeat(5000, static function () {
	asyncCall(function () {
		if ($GLOBALS["sockets"] == 0) {
			clearstatcache();
			if (filemtime(__FILE__) != $GLOBALS["mymtime"]) {
				echo "version changed, exiting" . PHP_EOL;
				Loop::stop();
			}
		}

	});
});

// Start main loop
Loop::run(static function () {

	// First port to receive FTP commands
	asyncCall(function () {

		$clientHandler = function (Socket $socket) {

			$GLOBALS["sockets"]++;

			$address = $socket->getRemoteAddress();

			$socket->write("220 Hello" . PHP_EOL); //yield

			echo "starting waiting for data from " . $address->getPort() . PHP_EOL;

			while (null !== $chunk = yield $socket->read()) {

				$response = "";
				if (preg_match('#^USER#', $chunk)) {
					$response = "331 Please specify the password.";
				} elseif (preg_match('#^PASS#', $chunk)) {
					$response = "230 Login successful.";
				} elseif (preg_match('#^PWD#', $chunk)) {
					$response = '257 "root" is cwd.';
				} elseif (preg_match('#^NOOP#', $chunk)) {
					$response = '421 OK.';
				} elseif (preg_match('#^TYPE#', $chunk)) {
					$response = "200 Switching to Binary mode.";
				} elseif (preg_match('#^CWD#', $chunk)) {
					$response = "250 Directory successfully changed.";
				} elseif (preg_match('#^PASV#', $chunk)) {

					$floor = floor($GLOBALS["port2"] / 256);
					$remainder = $GLOBALS["port2"] - 256 * $floor;

					$response = "227 Entering Passive Mode (172,17,0,2,$floor,$remainder).";
				} elseif (preg_match('#^PORT#', $chunk)) {
					$response = "500 Illegal PORT command.";
				} elseif (preg_match('#^STOR#', $chunk)) {
					//$response = "425 Use PORT or PASV first.";
					$response = "150 Accepted, please start" . PHP_EOL . "226 Successfully transferred";
				} elseif (preg_match('#^QUIT#', $chunk)) {
					$response = "221 Goodbye.";
				}

				if (empty($response)) {

					echo $address->getPort() . " < " . strlen($chunk) . " bytes";
					if (strlen($chunk) < 50) {
						echo ": " . substr($chunk, 0, 10);
					}
					echo PHP_EOL;
				} else {
					echo $address->getPort() . " < " . $chunk;
					echo $address->getPort() . " > " . $response . PHP_EOL;
					echo PHP_EOL;
					yield $socket->write($response . PHP_EOL);

				}

			}

			$address = $socket->getRemoteAddress();
			echo "connection closed with " . $address->getPort() . PHP_EOL;

			$GLOBALS["sockets"]--;

		};

		$server = Amp\Socket\Server::listen('0.0.0.0:' . $GLOBALS["port1"]);

		echo 'Listening for new connections on ' . $server->getAddress() . ' ...' . PHP_EOL;
		while ($socket = yield $server->accept()) {

			$address = $socket->getRemoteAddress();

			echo "got connection from " . $address->getPort() . PHP_EOL;

			asyncCall($clientHandler, $socket);
		}
	});
  
	// The second port for receiving images
	asyncCall(function () {

		$uploadHandler = function (Socket $socket) {
			$GLOBALS["sockets"]++;
			$address = $socket->getRemoteAddress();
			$data = "";

			while (null !== $chunk = yield $socket->read()) {

				$data .= $chunk;

			}

			$bytes = strlen($data);

			$address = $socket->getRemoteAddress();
			echo "upload connection closed with " . $address->getPort() . " (" . $bytes . " bytes received)" . PHP_EOL;

			if ($bytes > 1000) {
				// bytes is your image
			}

			$GLOBALS["sockets"]--;

		};

		$server = Amp\Socket\Server::listen('0.0.0.0:' . $GLOBALS["port2"]);

		echo 'Listening for new connections on ' . $server->getAddress() . ' ...' . PHP_EOL;
		while ($socket = yield $server->accept()) {

			$address = $socket->getRemoteAddress();

			echo "got upload connection from " . $address->getPort() . PHP_EOL;

			asyncCall($uploadHandler, $socket);
		}

	});

});