Major TelegramClient rewrite, split it into TelegramBareClient*

Making a distinction between a bare client and a full-featured
client will make it easier to create instances of the bare
client itself that can be simultaneously and hence have two
separate connections which do not interfer with eachother.

While writing the bare client, full reconnection to a
different data center is once again done only on .connect().

telethon/__init__.py

@@ -1,4 +1,5 @@
 from .errors import *
+from .telegram_bare_client import TelegramBareClient
 from .telegram_client import TelegramClient
 from .interactive_telegram_client import InteractiveTelegramClient
 from . import tl

telethon/interactive_telegram_client.py

@@ -62,18 +62,19 @@ class InteractiveTelegramClient(TelegramClient):
             print('First run. Sending code request...')
             self.send_code_request(user_phone)
 
-            code_ok = False
+            self_user = None
-            while not code_ok:
+            while self_user is None:
                 code = input('Enter the code you just received: ')
                 try:
-                    code_ok = self.sign_in(user_phone, code)
+                    self_user = self.sign_in(user_phone, code)
 
                 # Two-step verification may be enabled
                 except RPCError as e:
                     if e.password_required:
-                        pw = getpass(
+                        pw = getpass('Two step verification is enabled. '
-                            'Two step verification is enabled. Please enter your password: ')
+                                     'Please enter your password: ')
-                        code_ok = self.sign_in(password=pw)
+
+                        self_user = self.sign_in(password=pw)
                     else:
                         raise
 

telethon/telegram_bare_client.py

@@ -0,0 +1,329 @@
+import logging
+import platform
+from datetime import timedelta
+from hashlib import md5
+from os import path
+
+# Import some externalized utilities to work with the Telegram types and more
+from . import helpers as utils
+from .errors import RPCError, InvalidDCError, FloodWaitError
+from .network import authenticator, MtProtoSender, TcpTransport
+from .utils import get_appropriated_part_size
+
+# For sending and receiving requests
+from .tl import MTProtoRequest, Session, JsonSession
+from .tl.all_tlobjects import layer
+from .tl.functions import (InitConnectionRequest, InvokeWithLayerRequest)
+
+# Initial request
+from .tl.functions.help import GetConfigRequest
+
+# Easier access for working with media
+from .tl.functions.upload import (
+    GetFileRequest, SaveBigFilePartRequest, SaveFilePartRequest)
+
+# All the types we need to work with
+from .tl.types import InputFile, InputFileBig
+
+
+class TelegramBareClient:
+    """Bare Telegram Client with just the minimum -
+
+       The reason to distinguish between a MtProtoSender and a
+       TelegramClient itself is because the sender is just that,
+       a sender, which should know nothing about Telegram but
+       rather how to handle this specific connection.
+
+       The TelegramClient itself should know how to initialize
+       a proper connection to the servers, as well as other basic
+       methods such as disconnection and reconnection.
+
+       This distinction between a bare client and a full client
+       makes it possible to create clones of the bare version
+       (by using the same session, IP address and port) to be
+       able to execute queries on either, without the additional
+       cost that would involve having the methods for signing in,
+       logging out, and such.
+    """
+
+    # Current TelegramClient version
+    __version__ = '0.10.1'
+
+    # region Initialization
+
+    def __init__(self, session, api_id, api_hash, proxy=None):
+        """Initializes the Telegram client with the specified API ID and Hash.
+           Session must always be a Session instance, and an optional proxy
+           can also be specified to be used on the connection.
+        """
+
+        self.session = session
+        self.api_id = api_id
+        self.api_hash = api_hash
+        self.proxy = proxy
+        self._logger = logging.getLogger(__name__)
+
+        # These will be set later
+        self.dc_options = None
+        self.sender = None
+
+    # endregion
+
+    # region Connecting
+
+    def connect(self, device_model=None, system_version=None,
+                app_version=None, lang_code=None):
+        """Connects to the Telegram servers, executing authentication if
+           required. Note that authenticating to the Telegram servers is
+           not the same as authenticating the desired user itself, which
+           may require a call (or several) to 'sign_in' for the first time.
+
+           Default values for the optional parameters if left as None are:
+             device_model   = platform.node()
+             system_version = platform.system()
+             app_version    = TelegramClient.__version__
+             lang_code      = 'en'
+        """
+        transport = TcpTransport(self.session.server_address,
+                                 self.session.port, proxy=self.proxy)
+
+        try:
+            if not self.session.auth_key:
+                self.session.auth_key, self.session.time_offset = \
+                    authenticator.do_authentication(transport)
+
+                self.session.save()
+
+            self.sender = MtProtoSender(transport, self.session)
+            self.sender.connect()
+
+            # Set the default parameters if left unspecified
+            if not device_model:
+                device_model = platform.node()
+            if not system_version:
+                system_version = platform.system()
+            if not app_version:
+                app_version = self.__version__
+            if not lang_code:
+                lang_code = 'en'
+
+            # Now it's time to send an InitConnectionRequest
+            # This must always be invoked with the layer we'll be using
+            query = InitConnectionRequest(
+                api_id=self.api_id,
+                device_model=device_model,
+                system_version=system_version,
+                app_version=app_version,
+                lang_code=lang_code,
+                query=GetConfigRequest())
+
+            result = self.invoke(
+                InvokeWithLayerRequest(
+                    layer=layer, query=query))
+
+            # We're only interested in the DC options,
+            # although many other options are available!
+            self.dc_options = result.dc_options
+            return True
+
+        except InvalidDCError as e:
+            # If an InvalidDCError occurs on CONNECTION then it for sure
+            # means that the user is associated with a different DC,
+            # which is the only case in which we need to reconnect.
+            self._logger.info('DC error on initial connection, '
+                              'attempting to reconnect at DC {}'
+                              .format(e.new_dc))
+
+            self.disconnect()
+            self.session.auth_key = None  # Force creating new auth_key
+            dc = self._get_dc(e.new_dc)
+            self.session.server_address = dc.ip_address
+            self.session.port = dc.port
+            self.session.save()
+            self.connect()
+
+        except (RPCError, ConnectionError) as error:
+            # Probably errors from the previous session, ignore them
+            self.disconnect()
+            self._logger.warning('Could not stabilise initial connection: {}'
+                                 .format(error))
+            return False
+
+    def disconnect(self):
+        """Disconnects from the Telegram server"""
+        if self.sender:
+            self.sender.disconnect()
+            self.sender = None
+
+    def reconnect(self):
+        """Disconnects and connects again (effectively reconnecting)"""
+        self.disconnect()
+        self.connect()
+
+    # endregion
+
+    # region Working with different Data Centers
+
+    def _get_dc(self, dc_id):
+        """Gets the Data Center (DC) associated to 'dc_id'"""
+        if not self.dc_options:
+            raise ConnectionError(
+                'Cannot determine the required data center IP address. '
+                'Stabilise a successful initial connection first.')
+
+        return next(dc for dc in self.dc_options if dc.id == dc_id)
+
+    # endregion
+
+    # region Invoking Telegram requests
+
+    def invoke(self, request, timeout=timedelta(seconds=5), updates=None):
+        """Invokes (sends) a MTProtoRequest and returns (receives) its result.
+
+           An optional timeout can be specified to cancel the operation if no
+           result is received within such time, or None to disable any timeout.
+
+           If 'updates' is not None, all read update object will be put
+           in such list. Otherwise, update objects will be ignored.
+        """
+        if not isinstance(request, MTProtoRequest):
+            raise ValueError('You can only invoke MtProtoRequests')
+
+        if not self.sender:
+            raise ValueError('You must be connected to invoke requests!')
+
+        try:
+            self.sender.send(request)
+            self.sender.receive(request, timeout, updates=updates)
+            return request.result
+
+        except ConnectionResetError:
+            self._logger.info('Server disconnected us. Reconnecting and '
+                              'resending request...')
+            self.reconnect()
+            return self.invoke(request, timeout=timeout)
+
+        except FloodWaitError:
+            self.disconnect()
+            raise
+
+    # endregion
+
+    # region Uploading media
+
+    def upload_file(self,
+                    file_path,
+                    part_size_kb=None,
+                    file_name=None,
+                    progress_callback=None):
+        """Uploads the specified file_path and returns a handle (an instance
+           of InputFile or InputFileBig, as required) which can be later used.
+
+           If 'progress_callback' is not None, it should be a function that
+           takes two parameters, (bytes_uploaded, total_bytes).
+
+           Default values for the optional parameters if left as None are:
+             part_size_kb = get_appropriated_part_size(file_size)
+             file_name    = path.basename(file_path)
+        """
+        file_size = path.getsize(file_path)
+        if not part_size_kb:
+            part_size_kb = get_appropriated_part_size(file_size)
+
+        if part_size_kb > 512:
+            raise ValueError('The part size must be less or equal to 512KB')
+
+        part_size = int(part_size_kb * 1024)
+        if part_size % 1024 != 0:
+            raise ValueError('The part size must be evenly divisible by 1024')
+
+        # Determine whether the file is too big (over 10MB) or not
+        # Telegram does make a distinction between smaller or larger files
+        is_large = file_size > 10 * 1024 * 1024
+        part_count = (file_size + part_size - 1) // part_size
+
+        file_id = utils.generate_random_long()
+        hash_md5 = md5()
+
+        with open(file_path, 'rb') as file:
+            for part_index in range(part_count):
+                # Read the file by in chunks of size part_size
+                part = file.read(part_size)
+
+                # The SavePartRequest is different depending on whether
+                # the file is too large or not (over or less than 10MB)
+                if is_large:
+                    request = SaveBigFilePartRequest(file_id, part_index,
+                                                     part_count, part)
+                else:
+                    request = SaveFilePartRequest(file_id, part_index, part)
+
+                result = self.invoke(request)
+                if result:
+                    if not is_large:
+                        # No need to update the hash if it's a large file
+                        hash_md5.update(part)
+
+                    if progress_callback:
+                        progress_callback(file.tell(), file_size)
+                else:
+                    raise ValueError('Failed to upload file part {}.'
+                                     .format(part_index))
+
+        # Set a default file name if None was specified
+        if not file_name:
+            file_name = path.basename(file_path)
+
+        if is_large:
+            return InputFileBig(file_id, part_count, file_name)
+        else:
+            return InputFile(file_id, part_count, file_name,
+                             md5_checksum=hash_md5.hexdigest())
+
+    # endregion
+
+    # region Downloading media
+
+    def download_file(self,
+                          input_location,
+                          file_path,
+                          part_size_kb=None,
+                          file_size=None,
+                          progress_callback=None):
+        """Downloads the given InputFileLocation to file_path.
+
+           If 'progress_callback' is not None, it should be a function that
+           takes two parameters, (bytes_downloaded, total_bytes). Note that
+           'total_bytes' simply equals 'file_size', and may be None."""
+
+        if not part_size_kb:
+            if not file_size:
+                part_size_kb = 64  # Reasonable default
+            else:
+                part_size_kb = get_appropriated_part_size(file_size)
+
+        part_size = int(part_size_kb * 1024)
+        if part_size % 1024 != 0:
+            raise ValueError('The part size must be evenly divisible by 1024.')
+
+        # Ensure that we'll be able to download the media
+        utils.ensure_parent_dir_exists(file_path)
+
+        offset_index = 0
+        with open(file_path, 'wb') as file:
+            while True:
+                offset = offset_index * part_size
+                result = self.invoke(
+                    GetFileRequest(input_location, offset, part_size))
+                offset_index += 1
+
+                # If we have received no data (0 bytes), the file is over
+                # So there is nothing left to download and write
+                if not result.bytes:
+                    return result.type  # Return some extra information
+
+                file.write(result.bytes)
+                if progress_callback:
+                    progress_callback(file.tell(), file_size)
+
+    # endregion

telethon/telegram_client.py

@@ -1,29 +1,23 @@
 import platform
 from datetime import timedelta
-from hashlib import md5
 from mimetypes import guess_type
 from os import listdir, path
 from threading import Event, RLock, Thread
-from time import time, sleep
+from time import sleep
-import logging
+
+from . import TelegramBareClient
 
 # Import some externalized utilities to work with the Telegram types and more
 from . import helpers as utils
-from .errors import (RPCError, InvalidDCError, FloodWaitError,
+from .errors import (RPCError, InvalidDCError, InvalidParameterError,
-                     InvalidParameterError, ReadCancelledError)
+                     ReadCancelledError)
-
 from .network import authenticator, MtProtoSender, TcpTransport
 from .parser.markdown_parser import parse_message_entities
 
 # For sending and receiving requests
 from .tl import MTProtoRequest, Session, JsonSession
 from .tl.all_tlobjects import layer
-from .tl.functions import (InitConnectionRequest, InvokeWithLayerRequest,
+from .tl.functions import (InitConnectionRequest, InvokeWithLayerRequest)
-                           PingRequest)
-
-# Required to work with different data centers
-from .tl.functions.auth import (ExportAuthorizationRequest,
-                                ImportAuthorizationRequest)
 
 # Required to get the password salt
 from .tl.functions.account import GetPasswordRequest
@@ -33,8 +27,9 @@ from .tl.functions.auth import (CheckPasswordRequest, LogOutRequest,
                                 SendCodeRequest, SignInRequest,
                                 SignUpRequest, ImportBotAuthorizationRequest)
 
-# Initial request
+# Required to work with different data centers
-from .tl.functions.help import GetConfigRequest
+from .tl.functions.auth import (ExportAuthorizationRequest,
+                                ImportAuthorizationRequest)
 
 # Easier access to common methods
 from .tl.functions.messages import (
@@ -44,26 +39,27 @@ from .tl.functions.messages import (
 # For .get_me() and ensuring we're authorized
 from .tl.functions.users import GetUsersRequest
 
-# Easier access for working with media, too
-from .tl.functions.upload import (
-    GetFileRequest, SaveBigFilePartRequest, SaveFilePartRequest)
-
 # All the types we need to work with
 from .tl.types import (
     ChatPhotoEmpty, DocumentAttributeAudio, DocumentAttributeFilename,
-    InputDocumentFileLocation, InputFile, InputFileBig, InputFileLocation,
+    InputDocumentFileLocation, InputFileLocation,
     InputMediaUploadedDocument, InputMediaUploadedPhoto, InputPeerEmpty,
     MessageMediaContact, MessageMediaDocument, MessageMediaPhoto,
     UserProfilePhotoEmpty, InputUserSelf)
 
-from .utils import (find_user_or_chat, get_input_peer,
+from .utils import find_user_or_chat, get_input_peer, get_extension
-                    get_appropriated_part_size, get_extension)
 
 
-class TelegramClient:
+class TelegramClient(TelegramBareClient):
+    """Full featured TelegramClient meant to extend the basic functionality -
 
-    # Current TelegramClient version
+       As opposed to the TelegramBareClient, this one  features downloading
-    __version__ = '0.10.1'
+       media from different data centers, starting a second thread to
+       handle updates, and some very common functionality.
+
+       This should be used when the (slight) overhead of having locks,
+       threads, and possibly multiple connections is not an issue.
+    """
 
     # region Initialization
 
@@ -77,31 +73,23 @@ class TelegramClient:
            In the later case, you are free to override the `Session` class to provide different
            .save() and .load() implementations to suit your needs."""
 
-        if api_id is None or api_hash is None:
+        if not api_id or not api_hash:
             raise PermissionError(
-                'Your API ID or Hash are invalid. Please read "Requirements" on README.rst')
+                "Your API ID or Hash cannot be empty or None. "
-
+                "Refer to Telethon's README.rst for more information.")
-        self.api_id = api_id
-        self.api_hash = api_hash
 
         # Determine what session object we have
         # TODO JsonSession until migration is complete (by v1.0)
         if isinstance(session, str) or session is None:
-            self.session = JsonSession.try_load_or_create_new(session)
+            session = JsonSession.try_load_or_create_new(session)
-        elif isinstance(session, Session):
+        elif not isinstance(session, Session):
-            self.session = session
-        else:
             raise ValueError(
-                'The given session must either be a string or a Session instance.')
+                'The given session must be a str or a Session instance.')
 
-        self.transport = None
+        super().__init__(session, api_id, api_hash, proxy)
-        self.proxy = proxy  # Will be used when a TcpTransport is created
-
-        self.login_success = False
 
         # Safety across multiple threads (for the updates thread)
         self._lock = RLock()
-        self._logger = logging.getLogger(__name__)
 
         # Methods to be called when an update is received
         self._update_handlers = []
@@ -113,90 +101,18 @@ class TelegramClient:
         # the time since it's a (somewhat expensive) process.
         self._cached_senders = {}
         self._cached_sessions = {}
-
-        # These will be set later
         self._updates_thread = None
-        self.dc_options = None
+        self._phone_code_hashes = {}
-        self.sender = None
-        self.phone_code_hashes = {}
 
     # endregion
 
     # region Connecting
 
-    def connect(self, reconnect=False,
-                device_model=None, system_version=None,
-                app_version=None, lang_code=None):
-        """Connects to the Telegram servers, executing authentication if
-           required. Note that authenticating to the Telegram servers is
-           not the same as authenticating the desired user itself, which
-           may require a call (or several) to 'sign_in' for the first time.
-
-           Default values for the optional parameters if left as None are:
-             device_model   = platform.node()
-             system_version = platform.system()
-             app_version    = TelegramClient.__version__
-             lang_code      = 'en'
-        """
-        if self.transport is None:
-            self.transport = TcpTransport(self.session.server_address,
-                                          self.session.port, proxy=self.proxy)
-
-        try:
-            if not self.session.auth_key or (reconnect and self.sender is not None):
-                self.session.auth_key, self.session.time_offset = \
-                    authenticator.do_authentication(self.transport)
-
-                self.session.save()
-
-            self.sender = MtProtoSender(self.transport, self.session)
-            self.sender.connect()
-
-            # Set the default parameters if left unspecified
-            if not device_model:
-                device_model = platform.node()
-            if not system_version:
-                system_version = platform.system()
-            if not app_version:
-                app_version = self.__version__
-            if not lang_code:
-                lang_code = 'en'
-
-            # Now it's time to send an InitConnectionRequest
-            # This must always be invoked with the layer we'll be using
-            query = InitConnectionRequest(
-                api_id=self.api_id,
-                device_model=device_model,
-                system_version=system_version,
-                app_version=app_version,
-                lang_code=lang_code,
-                query=GetConfigRequest())
-
-            result = self.invoke(
-                InvokeWithLayerRequest(
-                    layer=layer, query=query))
-
-            # We're only interested in the DC options,
-            # although many other options are available!
-            self.dc_options = result.dc_options
-
-            self.login_success = True
-            return True
-        except (RPCError, ConnectionError) as error:
-            # Probably errors from the previous session, ignore them
-            self._logger.warning('Could not stabilise initial connection: {}'
-                                 .format(error))
-            return False
-
     def disconnect(self):
-        """Disconnects from the Telegram server and stops all the spawned threads"""
+        """Disconnects from the Telegram server
+           and stops all the spawned threads"""
         self._set_updates_thread(running=False)
-        if self.sender:
+        super(TelegramClient, self).disconnect()
-            self.sender.disconnect()
-            self.sender = None
-        if self.transport:
-            self.transport.close()
-            self.transport = None
 
         # Also disconnect all the cached senders
         for sender in self._cached_senders.values():
@@ -205,37 +121,10 @@ class TelegramClient:
         self._cached_senders.clear()
         self._cached_sessions.clear()
 
-    def reconnect(self):
-        """Disconnects and connects again (effectively reconnecting)"""
-        self.disconnect()
-        self.connect()
-
     # endregion
 
     # region Working with different Data Centers
 
-    def _reconnect_to_dc(self, dc_id):
-        """Reconnects to the specified DC ID. This is automatically
-           called after an InvalidDCError is raised"""
-        dc = self._get_dc(dc_id)
-
-        self.transport.close()
-        self.transport = None
-        self.session.server_address = dc.ip_address
-        self.session.port = dc.port
-        self.session.save()
-
-        self.connect(reconnect=True)
-
-    def _get_dc(self, dc_id):
-        """Gets the Data Center (DC) associated to 'dc_id'"""
-        if not self.dc_options:
-            raise ConnectionError(
-                'Cannot determine the required data center IP address. '
-                'Stabilise a successful initial connection first.')
-
-        return next(dc for dc in self.dc_options if dc.id == dc_id)
-
     def _get_exported_sender(self, dc_id, init_connection=False):
         """Gets a cached exported MtProtoSender for the desired DC.
 
@@ -304,13 +193,15 @@ class TelegramClient:
 
     # region Telegram requests functions
 
-    def invoke(self, request, timeout=timedelta(seconds=5), throw_invalid_dc=False):
+    def invoke(self, request, timeout=timedelta(seconds=5), updates=None):
-        """Invokes a MTProtoRequest (sends and receives it) and returns its result.
+        """Invokes (sends) a MTProtoRequest and returns (receives) its result.
-           An optional timeout can be given to cancel the operation after the time delta.
-           Timeout can be set to None for no timeout.
 
-           If throw_invalid_dc is True, these errors won't be caught (useful to
+           An optional timeout can be specified to cancel the operation if no
-           avoid infinite recursion). This should not be set to True manually."""
+           result is received within such time, or None to disable any timeout.
+
+           The 'updates' parameter will be ignored, although it's kept for
+           both function signatures (base class and this) to be the same.
+        """
         if not issubclass(type(request), MTProtoRequest):
             raise ValueError('You can only invoke MtProtoRequests')
 
@@ -322,37 +213,25 @@ class TelegramClient:
 
         try:
             self._lock.acquire()
-            updates = []
-            self.sender.send(request)
-            self.sender.receive(request, timeout, updates=updates)
-            for update in updates:
-                for handler in self._update_handlers:
-                    handler(update)
 
-            return request.result
+            updates = [] if self._update_handlers else None
+            result = super(TelegramClient, self).invoke(
+                request, timeout=timeout, updates=updates)
 
-        except InvalidDCError as error:
+            if updates:
-            if throw_invalid_dc:
+                for update in updates:
-                raise
+                    for handler in self._update_handlers:
+                        handler(update)
 
-            if error.message.startswith('FILE_MIGRATE_'):
+            # TODO Retry if 'result' is None?
-                return self.invoke_on_dc(request, error.new_dc,
+            return result
-                                         timeout=timeout)
-            else:
-                self._reconnect_to_dc(error.new_dc)
-                return self.invoke(request,
-                                   timeout=timeout, throw_invalid_dc=True)
 
-        except ConnectionResetError:
+        except InvalidDCError as e:
-            self._logger.info('Server disconnected us. Reconnecting and '
+            self._logger.info('DC error when invoking request, '
-                              'resending request...')
+                              'attempting to send it on DC {}'
-            self.reconnect()
+                              .format(e.new_dc))
-            self.invoke(request, timeout=timeout,
-                        throw_invalid_dc=throw_invalid_dc)
 
-        except FloodWaitError:
+            return self.invoke_on_dc(request, e.new_dc, timeout=timeout)
-            self.disconnect()
-            raise
 
         finally:
             self._lock.release()
@@ -389,58 +268,64 @@ class TelegramClient:
 
     def send_code_request(self, phone_number):
         """Sends a code request to the specified phone number"""
-        result = self.invoke(SendCodeRequest(phone_number, self.api_id, self.api_hash))
+        result = self.invoke(
-        self.phone_code_hashes[phone_number] = result.phone_code_hash
+            SendCodeRequest(phone_number, self.api_id, self.api_hash))
 
-    def sign_in(self, phone_number=None, code=None, password=None, bot_token=None):
+        self._phone_code_hashes[phone_number] = result.phone_code_hash
-        """Completes the authorization of a phone number by providing the received code.
 
-           If no phone or code is provided, then the sole password will be used. The password
+    def sign_in(self, phone_number=None, code=None,
-           should be used after a normal authorization attempt has happened and an RPCError
+                password=None, bot_token=None):
-           with `.password_required = True` was raised.
+        """Completes the sign in process with the phone number + code pair.
 
-           To login as a bot, only `bot_token` should be provided. This should equal to the
+           If no phone or code is provided, then the sole password will be used.
-           bot access hash provided by https://t.me/BotFather during your bot creation."""
+           The password should be used after a normal authorization attempt
+           has happened and an RPCError with `.password_required = True` was
+           raised.
+
+           To login as a bot, only `bot_token` should be provided.
+           This should equal to the bot access hash provided by
+           https://t.me/BotFather during your bot creation.
+
+           If the login succeeds, the logged in user is returned.
+        """
         if phone_number and code:
-            if phone_number not in self.phone_code_hashes:
+            if phone_number not in self._phone_code_hashes:
                 raise ValueError(
-                    'Please make sure you have called send_code_request first.')
+                    'Please make sure to call send_code_request first.')
 
             try:
-                result = self.invoke(
+                result = self.invoke(SignInRequest(
-                    SignInRequest(phone_number, self.phone_code_hashes[
+                    phone_number, self._phone_code_hashes[phone_number], code))
-                        phone_number], code))
 
             except RPCError as error:
                 if error.message.startswith('PHONE_CODE_'):
-                    return False
+                    return None
                 else:
                     raise
+
         elif password:
             salt = self.invoke(GetPasswordRequest()).current_salt
             result = self.invoke(
                 CheckPasswordRequest(utils.get_password_hash(password, salt)))
+
         elif bot_token:
-            result = self.invoke(
+            result = self.invoke(ImportBotAuthorizationRequest(
-                ImportBotAuthorizationRequest(flags=0,
+                flags=0, bot_auth_token=bot_token,
-                                              api_id=self.api_id,
+                api_id=self.api_id, api_hash=self.api_hash))
-                                              api_hash=self.api_hash,
+
-                                              bot_auth_token=bot_token))
         else:
             raise ValueError(
-                'You must provide a phone_number and a code for the first time, '
+                'You must provide a phone_number and a code the first time, '
                 'and a password only if an RPCError was raised before.')
 
-        # Ignore 'result.user', we don't need it
+        return result.user
-        self.login_success = True
-        return True
 
     def sign_up(self, phone_number, code, first_name, last_name=''):
         """Signs up to Telegram. Make sure you sent a code request first!"""
         result = self.invoke(
             SignUpRequest(
                 phone_number=phone_number,
-                phone_code_hash=self.phone_code_hashes[phone_number],
+                phone_code_hash=self._phone_code_hashes[phone_number],
                 phone_code=code,
                 first_name=first_name,
                 last_name=last_name))
@@ -449,7 +334,9 @@ class TelegramClient:
         self.session.save()
 
     def log_out(self):
-        """Logs out and deletes the current session. Returns True if everything went OK"""
+        """Logs out and deletes the current session.
+           Returns True if everything went okay."""
+
         # Special flag when logging out (so the ack request confirms it)
         self.sender.logging_out = True
         try:
@@ -492,9 +379,13 @@ class TelegramClient:
                     offset_date=None,
                     offset_id=0,
                     offset_peer=InputPeerEmpty()):
-        """Returns a tuple of lists ([dialogs], [entities]) with at least 'limit' items each.
+        """Returns a tuple of lists ([dialogs], [entities])
-           If `limit` is 0, all dialogs will be retrieved.
+           with at least 'limit' items each.
-           The `entity` represents the user, chat or channel corresponding to that dialog"""
+
+           If `limit` is 0, all dialogs will (should) retrieved.
+           The `entities` represent the user, chat or channel
+           corresponding to that dialog.
+        """
 
         r = self.invoke(
             GetDialogsRequest(
@@ -515,7 +406,8 @@ class TelegramClient:
                      message,
                      markdown=False,
                      no_web_page=False):
-        """Sends a message to the given entity (or input peer) and returns the sent message ID"""
+        """Sends a message to the given entity (or input peer)
+           and returns the sent message ID"""
         if markdown:
             msg, entities = parse_message_entities(message)
         else:
@@ -600,89 +492,6 @@ class TelegramClient:
 
     # endregion
 
-    # TODO Handle media downloading/uploading in a different session?
-    #  "It is recommended that large queries (upload.getFile, upload.saveFilePart)
-    #   be handled through a separate session and a separate connection"
-    # region Uploading media requests
-
-    def upload_file(self,
-                    file_path,
-                    part_size_kb=None,
-                    file_name=None,
-                    progress_callback=None):
-        """Uploads the specified file_path and returns a handle which can be later used
-
-        :param file_path: The file path of the file that will be uploaded
-        :param part_size_kb: The part size when uploading the file. None = Automatic
-        :param file_name: The name of the uploaded file. None = Automatic
-        :param progress_callback: A callback function which takes two parameters,
-                                  uploaded size (in bytes) and total file size (in bytes)
-                                  This is called every time a part is uploaded
-        """
-        file_size = path.getsize(file_path)
-        if not part_size_kb:
-            part_size_kb = get_appropriated_part_size(file_size)
-
-        if part_size_kb > 512:
-            raise ValueError('The part size must be less or equal to 512KB')
-
-        part_size = int(part_size_kb * 1024)
-        if part_size % 1024 != 0:
-            raise ValueError('The part size must be evenly divisible by 1024')
-
-        # Determine whether the file is too big (over 10MB) or not
-        # Telegram does make a distinction between smaller or larger files
-        is_large = file_size > 10 * 1024 * 1024
-        part_count = (file_size + part_size - 1) // part_size
-
-        # Multiply the datetime timestamp by 10^6 to get the ticks
-        # This is high likely going to be unique
-        file_id = utils.generate_random_long()
-        hash_md5 = md5()
-
-        with open(file_path, 'rb') as file:
-            for part_index in range(part_count):
-                # Read the file by in chunks of size part_size
-                part = file.read(part_size)
-
-                # The SavePartRequest is different depending on whether
-                # the file is too large or not (over or less than 10MB)
-                if is_large:
-                    request = SaveBigFilePartRequest(file_id, part_index,
-                                                     part_count, part)
-                else:
-                    request = SaveFilePartRequest(file_id, part_index, part)
-
-                # Invoke the file upload and increment both the part index and MD5 checksum
-                result = self.invoke(request)
-                if result:
-                    if not is_large:
-                        # No need to update the hash if it's a large file
-                        hash_md5.update(part)
-
-                    if progress_callback:
-                        progress_callback(file.tell(), file_size)
-                else:
-                    raise ValueError('Could not upload file part #{}'.format(
-                        part_index))
-
-        # Set a default file name if None was specified
-        if not file_name:
-            file_name = path.basename(file_path)
-
-        # After the file has been uploaded, we can return a handle pointing to it
-        if is_large:
-            return InputFileBig(
-                id=file_id,
-                parts=part_count,
-                name=file_name)
-        else:
-            return InputFile(
-                id=file_id,
-                parts=part_count,
-                name=file_name,
-                md5_checksum=hash_md5.hexdigest())
-
     def send_photo_file(self, input_file, entity, caption=''):
         """Sends a previously uploaded input_file
            (which should be a photo) to the given entity (or input peer)"""
@@ -747,12 +556,14 @@ class TelegramClient:
             photo_location = profile_photo.photo_small
 
         # Download the media with the largest size input file location
-        self.download_file_loc(
+        self.download_file(
             InputFileLocation(
                 volume_id=photo_location.volume_id,
                 local_id=photo_location.local_id,
-                secret=photo_location.secret),
+                secret=photo_location.secret
-            file_path)
+            ),
+            file_path
+        )
         return True
 
     def download_msg_media(self,
@@ -798,14 +609,16 @@ class TelegramClient:
             file_path += get_extension(message_media_photo)
 
         # Download the media with the largest size input file location
-        self.download_file_loc(
+        self.download_file(
             InputFileLocation(
                 volume_id=largest_size.volume_id,
                 local_id=largest_size.local_id,
-                secret=largest_size.secret),
+                secret=largest_size.secret
+            ),
             file_path,
             file_size=file_size,
-            progress_callback=progress_callback)
+            progress_callback=progress_callback
+        )
         return file_path
 
     def download_document(self,
@@ -839,14 +652,16 @@ class TelegramClient:
         if add_extension:
             file_path += get_extension(message_media_document)
 
-        self.download_file_loc(
+        self.download_file(
             InputDocumentFileLocation(
                 id=document.id,
                 access_hash=document.access_hash,
-                version=document.version),
+                version=document.version
+            ),
             file_path,
             file_size=file_size,
-            progress_callback=progress_callback)
+            progress_callback=progress_callback
+        )
         return file_path
 
     @staticmethod
@@ -877,48 +692,6 @@ class TelegramClient:
 
         return file_path
 
-    def download_file_loc(self,
-                          input_location,
-                          file_path,
-                          part_size_kb=64,
-                          file_size=None,
-                          progress_callback=None):
-        """Downloads media from the given input_file_location to the specified file_path.
-           If a progress_callback function is given, it will be called taking two
-           arguments (downloaded bytes count and total file size)"""
-
-        if not part_size_kb:
-            if not file_size:
-                raise ValueError('A part size value must be provided')
-            else:
-                part_size_kb = get_appropriated_part_size(file_size)
-
-        part_size = int(part_size_kb * 1024)
-        if part_size % 1024 != 0:
-            raise ValueError('The part size must be evenly divisible by 1024')
-
-        # Ensure that we'll be able to download the media
-        utils.ensure_parent_dir_exists(file_path)
-
-        # Start with an offset index of 0
-        offset_index = 0
-        with open(file_path, 'wb') as file:
-            while True:
-                # The current offset equals the offset_index multiplied by the part size
-                offset = offset_index * part_size
-                result = self.invoke(
-                    GetFileRequest(input_location, offset, part_size))
-                offset_index += 1
-
-                # If we have received no data (0 bytes), the file is over
-                # So there is nothing left to download and write
-                if not result.bytes:
-                    return result.type  # Return some extra information
-
-                file.write(result.bytes)
-                if progress_callback:
-                    progress_callback(file.tell(), file_size)
-
     # endregion
 
     # endregion
@@ -928,9 +701,9 @@ class TelegramClient:
     def add_update_handler(self, handler):
         """Adds an update handler (a function which takes a TLObject,
           an update, as its parameter) and listens for updates"""
-        if not self.sender or not self.login_success:
+        if not self.sender:
             raise RuntimeError("You can't add update handlers until you've "
-                               "successfully logged in.")
+                               "successfully connected to the server.")
 
         first_handler = not self._update_handlers
         self._update_handlers.append(handler)