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.venv2/Lib/site-packages/telethon/network/connection/tcpfull.py

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+import struct
+from zlib import crc32
+
+from .connection import Connection, PacketCodec
+from ...errors import InvalidChecksumError, InvalidBufferError
+
+
+class FullPacketCodec(PacketCodec):
+    tag = None
+
+    def __init__(self, connection):
+        super().__init__(connection)
+        self._send_counter = 0  # Important or Telegram won't reply
+
+    def encode_packet(self, data):
+        # https://core.telegram.org/mtproto#tcp-transport
+        # total length, sequence number, packet and checksum (CRC32)
+        length = len(data) + 12
+        data = struct.pack('<ii', length, self._send_counter) + data
+        crc = struct.pack('<I', crc32(data))
+        self._send_counter += 1
+        return data + crc
+
+    async def read_packet(self, reader):
+        packet_len_seq = await reader.readexactly(8)  # 4 and 4
+        packet_len, seq = struct.unpack('<ii', packet_len_seq)
+        if packet_len < 0 and seq < 0:
+            # It has been observed that the length and seq can be -429,
+            # followed by the body of 4 bytes also being -429.
+            # See https://github.com/LonamiWebs/Telethon/issues/4042.
+            body = await reader.readexactly(4)
+            raise InvalidBufferError(body)
+        elif packet_len < 8:
+            # Currently unknown why packet_len may be less than 8 but not negative.
+            # Attempting to `readexactly` with less than 0 fails without saying what
+            # the number was which is less helpful.
+            raise InvalidBufferError(packet_len_seq)
+
+        body = await reader.readexactly(packet_len - 8)
+        checksum = struct.unpack('<I', body[-4:])[0]
+        body = body[:-4]
+
+        valid_checksum = crc32(packet_len_seq + body)
+        if checksum != valid_checksum:
+            raise InvalidChecksumError(checksum, valid_checksum)
+
+        return body
+
+
+class ConnectionTcpFull(Connection):
+    """
+    Default Telegram mode. Sends 12 additional bytes and
+    needs to calculate the CRC value of the packet itself.
+    """
+    packet_codec = FullPacketCodec