5e1a672fc2
This module is not intended to be used directly in most cases, per: https://docs.python.org/3/library/builtins.html None of our usages warrant the explicit import. We also avoid some confusion as folks dig to see what we are doing to require importing builtins directly.
89 lines
2.5 KiB
Python
89 lines
2.5 KiB
Python
"""
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MCCP - Mud Client Compression Protocol
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This implements the MCCP v2 telnet protocol as per
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http://tintin.sourceforge.net/mccp/. MCCP allows for the server to
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compress data when sending to supporting clients, reducing bandwidth
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by 70-90%.. The compression is done using Python's builtin zlib
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library. If the client doesn't support MCCP, server sends uncompressed
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as normal. Note: On modern hardware you are not likely to notice the
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effect of MCCP unless you have extremely heavy traffic or sits on a
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terribly slow connection.
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This protocol is implemented by the telnet protocol importing
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mccp_compress and calling it from its write methods.
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"""
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import zlib
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# negotiations for v1 and v2 of the protocol
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MCCP = b'\x56'
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FLUSH = zlib.Z_SYNC_FLUSH
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def mccp_compress(protocol, data):
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"""
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Handles zlib compression, if applicable.
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Args:
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data (str): Incoming data to compress.
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Returns:
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stream (binary): Zlib-compressed data.
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"""
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if hasattr(protocol, 'zlib'):
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return protocol.zlib.compress(data) + protocol.zlib.flush(FLUSH)
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return data
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class Mccp(object):
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"""
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Implements the MCCP protocol. Add this to a
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variable on the telnet protocol to set it up.
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"""
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def __init__(self, protocol):
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"""
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initialize MCCP by storing protocol on
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ourselves and calling the client to see if
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it supports MCCP. Sets callbacks to
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start zlib compression in that case.
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Args:
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protocol (Protocol): The active protocol instance.
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"""
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self.protocol = protocol
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self.protocol.protocol_flags['MCCP'] = False
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# ask if client will mccp, connect callbacks to handle answer
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self.protocol.will(MCCP).addCallbacks(self.do_mccp, self.no_mccp)
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def no_mccp(self, option):
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"""
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Called if client doesn't support mccp or chooses to turn it off.
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Args:
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option (Option): Option dict (not used).
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"""
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if hasattr(self.protocol, 'zlib'):
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del self.protocol.zlib
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self.protocol.protocol_flags['MCCP'] = False
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self.protocol.handshake_done()
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def do_mccp(self, option):
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"""
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The client supports MCCP. Set things up by
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creating a zlib compression stream.
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Args:
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option (Option): Option dict (not used).
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"""
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self.protocol.protocol_flags['MCCP'] = True
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self.protocol.requestNegotiation(MCCP, b'')
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self.protocol.zlib = zlib.compressobj(9)
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self.protocol.handshake_done()
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