From 7f84374e98a57569eba66745b10fbd177f1be4b7 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Fri, 26 May 2017 16:39:59 +0200
Subject: [PATCH] Attempt at fixing msg_id too low/high (#95)

---
 telethon/network/mtproto_sender.py | 11 ++++++++++-
 telethon/tl/session.py             |  6 ++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/telethon/network/mtproto_sender.py b/telethon/network/mtproto_sender.py
index ecefe2e5..67fab922 100644
--- a/telethon/network/mtproto_sender.py
+++ b/telethon/network/mtproto_sender.py
@@ -333,7 +333,16 @@ class MtProtoSender:
         reader.read_int()  # request_sequence
 
         error_code = reader.read_int()
-        raise BadMessageError(error_code)
+        error = BadMessageError(error_code)
+        if error_code in (16, 17):
+            # sent msg_id too low or too high (respectively).
+            # Use the current msg_id to determine the right time offset.
+            self.session.update_time_offset(correct_msg_id=msg_id)
+            self.session.save()
+            self.logger.warning('Read Bad Message error: ' + str(error))
+            self.logger.info('Attempting to use the correct time offset.')
+        else:
+            raise error
 
     def handle_rpc_result(self, msg_id, sequence, reader, request):
         self.logger.debug('Handling RPC result, request is%s None', ' not' if request else '')
diff --git a/telethon/tl/session.py b/telethon/tl/session.py
index 54409419..b910b4c2 100644
--- a/telethon/tl/session.py
+++ b/telethon/tl/session.py
@@ -65,3 +65,9 @@ class Session:
 
         self.last_message_id = new_msg_id
         return new_msg_id
+
+    def update_time_offset(self, correct_msg_id):
+        """Updates the time offset based on a known correct message ID"""
+        now = int(time.time())
+        correct = correct_msg_id >> 32
+        self.time_offset = correct - now