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.
81 lines
2.3 KiB
Python
81 lines
2.3 KiB
Python
"""
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NAWS - Negotiate About Window Size
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This implements the NAWS telnet option as per
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https://www.ietf.org/rfc/rfc1073.txt
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NAWS allows telnet clients to report their current window size to the
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client and update it when the size changes
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"""
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from codecs import encode as codecs_encode
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from django.conf import settings
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NAWS = b'\x1f'
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IS = b'\x00'
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# default taken from telnet specification
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DEFAULT_WIDTH = settings.CLIENT_DEFAULT_WIDTH
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DEFAULT_HEIGHT = settings.CLIENT_DEFAULT_HEIGHT
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# try to get the customized mssp info, if it exists.
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class Naws(object):
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"""
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Implements the NAWS protocol. Add this to a variable on the telnet
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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 NAWS by storing protocol on ourselves and calling
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the client to see if it supports NAWS.
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Args:
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protocol (Protocol): The active protocol instance.
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"""
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self.naws_step = 0
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self.protocol = protocol
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self.protocol.protocol_flags['SCREENWIDTH'] = {0: DEFAULT_WIDTH} # windowID (0 is root):width
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self.protocol.protocol_flags['SCREENHEIGHT'] = {0: DEFAULT_HEIGHT} # windowID:width
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self.protocol.negotiationMap[NAWS] = self.negotiate_sizes
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self.protocol.do(NAWS).addCallbacks(self.do_naws, self.no_naws)
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def no_naws(self, option):
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"""
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Called when client is not reporting NAWS. This is the normal
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operation.
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Args:
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option (Option): Not used.
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"""
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self.protocol.handshake_done()
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def do_naws(self, option):
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"""
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Client wants to negotiate all the NAWS information.
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Args:
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option (Option): Not used.
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"""
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self.protocol.handshake_done()
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def negotiate_sizes(self, options):
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"""
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Step through the NAWS handshake.
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Args:
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option (list): The incoming NAWS options.
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"""
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if len(options) == 4:
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# NAWS is negotiated with 16bit words
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width = options[0] + options[1]
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self.protocol.protocol_flags['SCREENWIDTH'][0] = int(codecs_encode(width, 'hex'), 16)
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height = options[2] + options[3]
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self.protocol.protocol_flags['SCREENHEIGHT'][0] = int(codecs_encode(height, 'hex'), 16)
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