Detect arbitrary negative HTTP error codes

telethon/network/mtprotoplainsender.py

@@ -5,7 +5,7 @@ in plain text, when no authorization key has been created yet.
 import struct
 
 from .mtprotostate import MTProtoState
-from ..errors import BrokenAuthKeyError
+from ..errors import InvalidBufferError
 from ..extensions import BinaryReader
 
 
@@ -34,9 +34,8 @@ class MTProtoPlainSender:
         )
 
         body = await self._connection.recv()
-        if body == b'l\xfe\xff\xff':  # -404 little endian signed
-            # Broken authorization, must reset the auth key
-            raise BrokenAuthKeyError()
+        if len(body) < 8:
+            raise InvalidBufferError(body)
 
         with BinaryReader(body) as reader:
             auth_key_id = reader.read_long()

telethon/network/mtprotosender.py

@@ -9,7 +9,7 @@ from .requeststate import RequestState
 from ..tl.tlobject import TLRequest
 from .. import utils
 from ..errors import (
-    BadMessageError, BrokenAuthKeyError, SecurityError, TypeNotFoundError,
+    BadMessageError, InvalidBufferError, SecurityError, TypeNotFoundError,
     InvalidChecksumError, rpc_message_to_error
 )
 from ..extensions import BinaryReader
@@ -382,8 +382,12 @@ class MTProtoSender:
                 )
             except asyncio.CancelledError:
                 return
-            except (BrokenAuthKeyError, BufferError):
-                __log__.info('Broken authorization key; resetting')
+            except BufferError as e:
+                if isinstance(e, InvalidBufferError) and e.code == 404:
+                    __log__.info('Broken authorization key; resetting')
+                else:
+                    __log__.warning('Invalid buffer %s', e)
+
                 self._connection._state.auth_key = None
                 self._start_reconnect()
                 return

telethon/network/mtprotostate.py

@@ -5,7 +5,7 @@ import time
 from hashlib import sha256
 
 from ..crypto import AES
-from ..errors import SecurityError, BrokenAuthKeyError
+from ..errors import SecurityError, InvalidBufferError
 from ..extensions import BinaryReader
 from ..tl.core import TLMessage
 from ..tl.functions import InvokeAfterMsgRequest
@@ -114,11 +114,7 @@ class MTProtoState:
         Inverse of `encrypt_message_data` for incoming server messages.
         """
         if len(body) < 8:
-            # TODO If len == 4, raise HTTPErrorCode(-little endian int)
-            if body == b'l\xfe\xff\xff':
-                raise BrokenAuthKeyError()
-            else:
-                raise BufferError("Can't decode packet ({})".format(body))
+            raise InvalidBufferError(body)
 
         # TODO Check salt, session_id and sequence_number
         key_id = struct.unpack('<Q', body[:8])[0]