Avoid using BinaryWriter where possible

telethon/network/connection.py

@@ -1,4 +1,5 @@
 import os
+import struct
 from datetime import timedelta
 from zlib import crc32
 from enum import Enum
@@ -6,7 +7,7 @@ from enum import Enum
 import errno
 
 from ..crypto import AESModeCTR
-from ..extensions import BinaryWriter, TcpClient
+from ..extensions import TcpClient
 from ..errors import InvalidChecksumError
 
 
@@ -175,30 +176,22 @@ class Connection:
         # https://core.telegram.org/mtproto#tcp-transport
         # total length, sequence number, packet and checksum (CRC32)
         length = len(message) + 12
-        with BinaryWriter(known_length=length) as writer:
-            writer.write_int(length)
-            writer.write_int(self._send_counter)
-            writer.write(message)
-            writer.write_int(crc32(writer.get_bytes()), signed=False)
-            self._send_counter += 1
-            self.write(writer.get_bytes())
+        data = struct.pack('<ii', length, self._send_counter) + message
+        crc = struct.pack('<I', crc32(data))
+        self._send_counter += 1
+        self.write(data + crc)
 
     def _send_intermediate(self, message):
-        with BinaryWriter(known_length=len(message) + 4) as writer:
-            writer.write_int(len(message))
-            writer.write(message)
-            self.write(writer.get_bytes())
+        self.write(struct.pack('<i', len(message)) + message)
 
     def _send_abridged(self, message):
-        with BinaryWriter(known_length=len(message) + 4) as writer:
-            length = len(message) >> 2
-            if length < 127:
-                writer.write_byte(length)
-            else:
-                writer.write_byte(127)
-                writer.write(int.to_bytes(length, 3, 'little'))
-            writer.write(message)
-            self.write(writer.get_bytes())
+        length = len(message) >> 2
+        if length < 127:
+            length = struct.pack('B', length)
+        else:
+            length = b'\x7f' + int.to_bytes(length, 3, 'little')
+
+        self.write(length + message)
 
     # endregion