81 lines
2.2 KiB
Python
81 lines
2.2 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 builtins import object
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from django.conf import settings
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NAWS = chr(31)
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IS = chr(0)
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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(width.encode('hex'), 16)
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height = options[2] + options[3]
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self.protocol.protocol_flags['SCREENHEIGHT'][0] = int(height.encode('hex'), 16)
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