Add error handling for when the listener has been logged out

.bumpversion.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.9.5
+current_version = 1.9.6
 commit = True
 tag = True
 

fbchat/__init__.py

@@ -13,7 +13,7 @@ from ._client import Client
 from ._util import log  # TODO: Remove this (from examples too)
 
 __title__ = "fbchat"
-__version__ = "1.9.5"
+__version__ = "1.9.6"
 __description__ = "Facebook Chat (Messenger) for Python"
 
 __copyright__ = "Copyright 2015 - 2019 by Taehoon Kim"

fbchat/_mqtt.py

@@ -79,6 +79,8 @@ class Mqtt(object):
             log.exception("Failed parsing MQTT data on %s as JSON", message.topic)
             return
 
+        log.debug("MQTT payload: %s, %s", message.topic, j)
+
         if message.topic == "/t_ms":
             # Update sync_token when received
             # This is received in the first message after we've created a messenger
@@ -86,18 +88,31 @@ class Mqtt(object):
             if "syncToken" in j and "firstDeltaSeqId" in j:
                 self._sync_token = j["syncToken"]
                 self._sequence_id = j["firstDeltaSeqId"]
+                return
 
             # Update last sequence id when received
             if "lastIssuedSeqId" in j:
                 self._sequence_id = j["lastIssuedSeqId"]
 
             if "errorCode" in j:
-                # Known types: ERROR_QUEUE_OVERFLOW | ERROR_QUEUE_NOT_FOUND
-                # 'F\xfa\x84\x8c\x85\xf8\xbc-\x88 FB_PAGES_INSUFFICIENT_PERMISSION\x00'
-                log.error("MQTT error code %s received", j["errorCode"])
-                # TODO: Consider resetting the sync_token and sequence ID here?
-
-        log.debug("MQTT payload: %s, %s", message.topic, j)
+                error = j["errorCode"]
+                # TODO: 'F\xfa\x84\x8c\x85\xf8\xbc-\x88 FB_PAGES_INSUFFICIENT_PERMISSION\x00'
+                if error in ("ERROR_QUEUE_NOT_FOUND", "ERROR_QUEUE_OVERFLOW"):
+                    # ERROR_QUEUE_NOT_FOUND means that the queue was deleted, since too
+                    # much time passed, or that it was simply missing
+                    # ERROR_QUEUE_OVERFLOW means that the sequence id was too small, so
+                    # the desired events could not be retrieved
+                    log.error(
+                        "The MQTT listener was disconnected for too long,"
+                        " events may have been lost"
+                    )
+                    self._sync_token = None
+                    self._sequence_id = self._fetch_sequence_id(self._state)
+                    self._messenger_queue_publish()
+                    # TODO: Signal to the user that they should reload their data!
+                    return
+                log.error("MQTT error code %s received", error)
+                return
 
         # Call the external callback
         self._on_message(message.topic, j)
@@ -115,11 +130,10 @@ class Mqtt(object):
         log.debug("Fetching MQTT sequence ID")
         # Same request as in `Client.fetchThreadList`
         (j,) = state._graphql_requests(_graphql.from_doc_id("1349387578499440", params))
-        try:
-            return int(j["viewer"]["message_threads"]["sync_sequence_id"])
-        except (KeyError, ValueError):
-            # TODO: Proper exceptions
-            raise
+        sequence_id = j["viewer"]["message_threads"]["sync_sequence_id"]
+        if not sequence_id:
+            raise _exception.FBchatNotLoggedIn("Failed fetching sequence id")
+        return int(sequence_id)
 
     def _on_connect_handler(self, client, userdata, flags, rc):
         if rc == 21:
@@ -129,6 +143,9 @@ class Mqtt(object):
         if rc != 0:
             return  # Don't try to send publish if the connection failed
 
+        self._messenger_queue_publish()
+
+    def _messenger_queue_publish(self):
         # configure receiving messages.
         payload = {
             "sync_api_version": 10,
@@ -171,6 +188,10 @@ class Mqtt(object):
             "/br_sr",
             # Response to /br_sr
             "/sr_res",
+            # Data about user-to-user calls
+            # TODO: Investigate the response from this! (A bunch of binary data)
+            # "/t_rtc",
+            # TODO: Find out what this does!
             # TODO: Investigate the response from this! (A bunch of binary data)
             # "/t_p",
             # TODO: Find out what this does!
@@ -186,7 +207,6 @@ class Mqtt(object):
             "/messaging_events",
             "/orca_message_notifications",
             "/pp",
-            "/t_rtc",
             "/webrtc_response",
         ]
 
@@ -266,6 +286,8 @@ class Mqtt(object):
                 # This error is wrongly classified
                 # See https://github.com/eclipse/paho.mqtt.python/issues/340
                 log.warning("Connection error, retrying")
+            elif rc == paho.mqtt.client.MQTT_ERR_CONN_REFUSED:
+                raise _exception.FBchatNotLoggedIn("MQTT connection refused")
             else:
                 err = paho.mqtt.client.error_string(rc)
                 log.error("MQTT Error: %s", err)