How to keep php://stdout open forever - php

Question

I find a bug with php integrated to Ejabberd in authentication mode. This script, open php://stdin and php://stdout to read/write data, but after a while it will be hang so the authentication feature could not work.
My code:
<?php
/**
* A class extending EjabberdExternalAuth may optionally implement this interface
* to support additional, non-critical methods for adding and removing users.
*/
interface EjabberdExternalAuth_UserManagement {
/**
* Corresponds to `setpass` operation.
*/
public function setPassword($user, $server, $password);
/**
* Corresponds to `tryregister` operation.
*/
public function register($user, $server, $password);
/**
* Corresponds to `removeuser` operation.
*/
public function remove($user, $server);
/**
* Corresponds to `removeuser3` operation.
*/
public function removeSafely($user, $server, $password);
}
abstract class EjabberdExternalAuth {
private $db = null;
private $log = null;
private $stdin = null;
private $stdout = null;
public static $logLevel = array(LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR, LOG_WARNING, LOG_INFO, LOG_KERN);
/**
* Corresponds to `auth` operation.
*/
abstract protected function authenticate($user, $server, $password);
/**
* Corresponds to `isuser` operation.
*/
abstract protected function exists($user, $server);
final public function __construct(PDO $db = null, $log = null) {
set_error_handler(array($this, 'errorHandler'));
$this->db = $db;
$this->stdin = fopen('php://stdin', 'rb');
$this->stdout = fopen('php://stdout', 'wb');
if ($log) {
$this->log = fopen($log, 'a');
}
$this->log('Starting auth service...', LOG_INFO);
try {
$this->work();
} catch (Exception $e) {
$this->log($e->getMessage());
}
$this->log('Exiting...', LOG_INFO);
}
final protected function db() {
return $this->db;
}
final private function work() {
$this->log('Entering event loop...', LOG_INFO);
while (true) {
try {
$message = $this->read();
$message = $this->parseMessage($message);
} catch (UnexpectedValueException $e) {
$this->log($e->getMessage());
continue;
}
$this->log('Received message: ' . json_encode($message), LOG_DEBUG);
$response = false;
switch ($message['command']) {
case 'auth' :
$response = $this->authenticate($message['user'], $message['server'], $message['password']);
break;
case 'isuser' :
$response = $this->exists($message['user'], $message['server']);
break;
}
if ($this instanceof EjabberdExternalAuth_UserManagement) {
switch ($message['command']) {
case 'setpass' :
$response = $this->setPassword($message['user'], $message['server'], $message['password']);
break;
case 'tryregister' :
$response = $this->register($message['user'], $message['server'], $message['password']);
break;
case 'removeuser' :
$response = $this->remove($message['user'], $message['server']);
break;
case 'removeuser3' :
$response = $this->removeSafely($message['user'], $message['server'], $message['password']);
break;
}
}
$this->respond($response);
}
}
final private function read() {
$length = fgets($this->stdin, 3);
if (feof($this->stdin)) {
throw new RuntimeException('Pipe broken');
}
$length = current(unpack('n', $length));
if (!$length) {
throw new UnexpectedValueException("Invalid length value, won't continue reading");
}
$message = fgets($this->stdin, $length + 1);
return $message;
}
final private function parseMessage($message) {
$message = explode(':', $message, 4);
if (count($message) < 3) {
throw new UnexpectedValueException('Message is too short: ' . join(':', $message));
}
list($command, $user, $server) = $message;
$password = isset($message[3]) ? $message[3] : null;
return compact('command', 'user', 'server', 'password');
}
final private function respond($status) {
$message = pack('nn', 2, (int)$status);
$this->log('Sending response: ' . bin2hex($message), LOG_DEBUG);
fwrite($this->stdout, $message);
}
final protected function log($message, $severity = LOG_ERR) {
if ($this->log && in_array($severity, self::$logLevel, true)) {
static $types = array(
LOG_EMERG => 'EMERGENCY',
LOG_ALERT => 'ALERT',
LOG_CRIT => 'CRITICAL',
LOG_ERR => 'ERROR',
LOG_WARNING => 'WARNING',
LOG_NOTICE => 'NOTICE',
LOG_INFO => 'INFO',
LOG_DEBUG => 'DEBUG',
LOG_KERN => 'KERNEL'
);
$message = sprintf('%s <%s> %9s: %s', date('Y-m-d H:i:s'), getmypid(), isset($types[$severity]) ? $types[$severity] : $types[LOG_ERR], $message);
fwrite($this->log, $message . PHP_EOL);
}
}
final protected function errorHandler($errno, $errstr, $errfile, $errline, array $errcontext) {
$this->log("($errno) $errstr in $errfile on line $errline");
return false;
}
}
I think that, something is wrong, example: the STDOUT may be broken, so I need to write data to php://stdout forever, so how could I make sure the stream will never be broken.