Add ping response timeout handling (#210)

* Add ping response timeout handling

* Implement pr feedback

Author: Namoshek

src/MqttClient.php

@@ -45,9 +45,10 @@ class MqttClient implements ClientContract
     public const SOCKET_READ_BUFFER_SIZE = 8192;
     private string $clientId;
     private ConnectionSettings $settings;
-    private string $buffer     = '';
-    private bool $connected    = false;
-    private ?float $lastPingAt = null;
+    private string $buffer                    = '';
+    private bool $connected                   = false;
+    private ?float $lastPingAt                = null;
+    private ?float $pingResponseExpectedUntil = null;
     private MessageProcessor $messageProcessor;
     private Repository $repository;
     private LoggerInterface $logger;
@@ -489,6 +490,7 @@ public function disconnect(): void
             stream_socket_shutdown($this->socket, STREAM_SHUT_WR);
         }
 
+        $this->socket    = null;
         $this->connected = false;
     }
 
@@ -650,6 +652,10 @@ public function loopOnce(float $loopStartedAt, bool $allowSleep = false, int $sl
         // This includes published messages, subscribe and unsubscribe requests.
         $this->resendPendingMessages();
 
+        // If the last ping we sent has not been answered within the configured keep alive interval,
+        // we assume the connection is dead and try to reconnect if configured to do so.
+        $this->handlePingTimeout();
+
         // If the last message of the broker has been received more seconds ago
         // than specified by the keep alive time, we will send a ping to ensure
         // the connection is kept alive.
@@ -869,6 +875,14 @@ protected function handleMessage(Message $message): void
             $this->writeToSocketWithAutoReconnect($this->messageProcessor->buildPingResponseMessage());
             return;
         }
+
+        // PINGRESP
+        if ($message->getType()->equals(MessageType::PING_RESPONSE())) {
+            // Set the ping response expectation to null, so we know the broker responded.
+            $this->logger->debug('Received ping response from the broker.');
+            $this->pingResponseExpectedUntil = null;
+            return;
+        }
     }
 
     /**
@@ -1020,6 +1034,39 @@ protected function ping(): void
         $this->logger->debug('Sending ping to the broker to keep the connection alive.');
 
         $this->writeToSocketWithAutoReconnect($this->messageProcessor->buildPingRequestMessage());
+        
+        // Set the deadline for receiving a PINGRESP message according to MQTT specification requirements.
+        $this->pingResponseExpectedUntil = microtime(true) + $this->settings->getKeepAliveInterval();
+    }
+
+    /**
+     * Handles a ping timeout by closing the socket and trying to reconnect if configured to do so.
+     *
+     * @throws DataTransferException
+     */
+    protected function handlePingTimeout(): void
+    {
+        if ($this->pingResponseExpectedUntil === null || microtime(true) < $this->pingResponseExpectedUntil) {
+            return;
+        }
+
+        $this->logger->warning(
+            'The broker did not respond to our ping request within the configured keep alive interval. Assuming the connection is dead.'
+        );
+
+        $this->closeSocket();
+
+        $this->lastPingAt                = null;
+        $this->pingResponseExpectedUntil = null;
+
+        if (!$this->settings->shouldReconnectAutomatically()) {
+            throw new DataTransferException(
+                DataTransferException::EXCEPTION_RX_DATA,
+                'No ping response received in time. The connection is dead.'
+            );
+        }
+
+        $this->reconnect();
     }
 
     /**
@@ -1231,6 +1278,7 @@ protected function closeSocket(): void
             ]);
         }
 
-        $this->socket = null;
+        $this->socket    = null;
+        $this->connected = false;
     }
 }