ESP8266 restart when using UserAuth and ServiceAuth

[ulver2812]

Hi, I'm trying to implement this function:

boolean sendPushNotification(String title, String body, JsonDocument jsonPush){
  UserAuth user_auth(apiKey, username, password);
  initializeApp(aClient, app, getAuth(user_auth), aResult_no_callback);
  authHandler();
  app.getApp<RealtimeDatabase>(Database);
  Database.url(dbUrl);
  aClient.setAsyncResult(aResult_no_callback);

  String path = "users/" + app.getUid();  
  String fcmToken = Database.get<String>(aClient, path + "/fcmToken");

  if (aClient.lastError().code() == 0){
    ServiceAuth sa_auth(timeStatusCB, clientEmail, projectID, privateKey, 3000 /* expire period in seconds (<= 3600) */);
    initializeApp(aClient, app, getAuth(sa_auth), aResult_no_callback);
    authHandler();
    app.getApp<Messaging>(messaging);
    aClient.setAsyncResult(aResult_no_callback);

    Messages::Message msg;    
    msg.token(fcmToken); // Registration token to send a message to    

    Messages::Notification notification;
    notification.body(body).title(title);

    String serializedData = "";
    serializeJson(jsonPush, serializedData);

    msg.data(object_t(serializedData));

    Messages::AndroidConfig androidConfig;
    androidConfig.priority(Messages::AndroidMessagePriority::_HIGH);
    Messages::AndroidNotification androidNotification;
    androidNotification.notification_priority(Messages::NotificationPriority::PRIORITY_HIGH);
    androidConfig.notification(androidNotification);
    msg.android(androidConfig);
    msg.notification(notification);
    
    String payload = messaging.send(aClient, Messages::Parent(projectID), msg);
    if (aClient.lastError().code() == 0){
        debugPrintln(payload);
        return true;
    }else{
      debugPrintln("Failed to send push notification.");    
      return false;   
    }
    return true;
  }else{
   debugPrintln("Failed to get FCM Token.");    
   return false;
  }  
}

But when execute it I obtain this in the Arduino IDE serial monitor:

Event task: task_90, msg: authenticating, code: 7
Debug task: task_90, msg: Connecting to server...
Event task: task_90, msg: auth request sent, code: 8
Event task: task_90, msg: auth response received, code: 9
Debug task: task_90, msg: Terminating the server connection...
Event task: task_90, msg: ready, code: 10

Event task: task_8796, msg: initializing, code: 1
Debug task: task_8796, msg: Connecting to server...
Event task: task_8796, msg: token signing, code: 6
Debug task: task_8796, msg: Terminating the server connection...
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And then the ESP8266 crash and restart, the code apparently stop and crash after executing the second authHandler(); right after the ServiceAuth authentication.

Probably I'm doing something wrong but I can't understand where. I'm trying to mix the Realtime DB sync example with Cloud messaging sync example.

[mobizt]

You should know about SSL client memory usage and heap options in esp8266
https://github.com/mobizt/FirebaseClient?tab=readme-ov-file#prerequisites

[ulver2812]

Yes, I'm already using the option 3, 16KB cache + 48KB IRAM and 2nd Heap (shared) but the issue persist.

[mobizt]

In esp8266 programming, you have to know the stack restriction. It is only 4k and most of it used by SSL client. You should not do many things inside the one function sendPushNotification because everything you defined locally uses stack.

Please use static defines or global object/var to use heap instead.

In embedded programming you should be aware of available stack especially esp8266, it is so small even it can be editing the source to increase.

[mobizt]

All classes that represent the Firebase API objects in this library e.g. Messages::AndroidNotification etc.

It is designed for data manipulation instead of data container. it contains many Arduino Strings then it consumes more memory than the raw string.

This similar to JSON object that it does not contain the raw JSON serialized string but contains in-memory objects like a link list inside.

Then when define these objects it should live shortly to avoid stack growth.

[ulver2812]

Ok, I'm trying to simplify as much as possible in order to consume less memory. I declared the privete key, etc. as const, removed the code part to get the FCM token (I use it statically for the test) and focus the code only to authenticate with ServiceAuth and send push notication, this is my code now:

const char PRIVATE_KEY[] PROGMEM = "-----BEGIN PRIVATE KEY-----XXXXX-----END PRIVATE KEY-----\n";
#define FIREBASE_PROJECT_ID "my-project-id"
#define FIREBASE_CLIENT_EMAIL "my-client-email"

void getMsg(Messages::Message &msg){    
    msg.token("MY-TOKEN-ID"); // Registration token to send a message to    
    
    Messages::Notification notification;
    notification.body("Notification body").title("Notification title");   

    object_t data, obj1, obj2, obj3, obj4;
    JsonWriter writer;

    writer.create(obj1, "name", string_t("wrench"));
    writer.create(obj2, "mass", string_t("1.3kg"));
    writer.create(obj3, "count", string_t("3"));
    writer.join(data, 3 /* no. of object_t (s) to join */, obj1, obj2, obj3);    

    msg.data(data);
    data.clear();

    Messages::AndroidConfig androidConfig;
    androidConfig.priority(Messages::AndroidMessagePriority::_HIGH);
    Messages::AndroidNotification androidNotification;
    androidNotification.notification_priority(Messages::NotificationPriority::PRIORITY_HIGH);
    androidConfig.notification(androidNotification);
    msg.android(androidConfig);
    msg.notification(notification);
}

boolean sendPushNotification(){  
    ServiceAuth sa_auth(timeStatusCB, FIREBASE_CLIENT_EMAIL, FIREBASE_PROJECT_ID, PRIVATE_KEY, 3000 /* expire period in seconds (<= 3600) */);
    initializeApp(aClient, app, getAuth(sa_auth), aResult_no_callback);
    authHandler();
    app.getApp<Messaging>(messaging);
    aClient.setAsyncResult(aResult_no_callback);    
    
    Messages::Message msg;        
    getMsg(msg);

    String payload = messaging.send(aClient, Messages::Parent(FIREBASE_PROJECT_ID), msg);
    if (aClient.lastError().code() == 0){
        debugPrintln(payload);
        return true;
    }else{
      return false;   
    }
}

void btnLongClickDetected(Button2& btn) {
    sendPushNotification();
}

I run sendPushNotification() on a long button click and on execution the esp8266 still crash and get this output on Serial monitor:

Event task: task_91, msg: initializing, code: 1
Debug task: task_91, msg: Getting current time...
Event task: task_91, msg: token signing, code: 6
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What else I need to do ?
Thanks!

[mobizt]

As you see the debug info before device crashed.

Event task: task_91, msg: token signing, code: 6

Care should be taken when working with ServiceAuth in ESP8266 due to the stack usage is really critical.

The internal processes for authentication with ServiceAuth involved the JWT generation and signing using BearSSL .

It uses 3k by BearSSLcrypto tasks (2996 bytes when repaint the stack and measuring high watermark) in JWT token signing process.

This is the result that you have only 800 bytes of stack for use that is why I mentioned about.

This is the important information about ESP8266 stack memory restriction.

For your application. it is not necessary to call initializeApp many times unless it is needed.

When you are working with different Firebase services (different APIs) and you don't strict to only user access controls using security rules i.e. admin access using access token will by-pass the security rules. You can use only one auth token authentication/authorization for all Firebase services e.g. by using ServiceAuth and AccessToken like in this example.

After the ServiceAuth authentication process has done and the stack is repainted, the stack returns to 3.9k as normal.

Then you have to manage your memory usage (stack/heap) carefully when working with ServiceAuth authentication.

Another option is to edit the ESP8266 Core source to increase the stack size.

[mobizt]

To measure the stack.
ESP.getFreeContStack();

To repaint the stack high watermark
ESP.resetFreeContStack();

[mobizt]

You should know that the credentials taken by ServiceAuth class are quite large, see the size of private key.

The ServiceAuth class object define locally, and it makes a private key copy inside (uses stack), that is why the stack is overflown in your case.

Why don't define ServiceAuth class object globally?

[mobizt]

The reason to make ServiceAuth internal private key copy instead of pointer to the string literal (const char*) in user code is it implements the service account file parser and stores the private key inside to be processed later.

With local defined ServiceAuth , you also can call sa_auth.clear(); immediately after initializeApp to free the string buffer of ServiceAuth class object.

[ulver2812]

I got it, thanks for your precious informations!