def filter(self, data):
"""\
Handle a bunch of incoming bytes. This is a generator. It will yield
all characters not of interest for Telnet/RFC 2217.
The idea is that the reader thread pushes data from the socket through
this filter:
for byte in filter(socket.recv(1024)):
# do things like CR/LF conversion/whatever
# and write data to the serial port
serial.write(byte)
(socket error handling code left as exercise for the reader)
"""
for byte in iterbytes(data):
if self.mode == M_NORMAL:
# interpret as command or as data
if byte == IAC:
self.mode = M_IAC_SEEN
else:
# store data in sub option buffer or pass it to our
# consumer depending on state
if self.suboption is not None:
self.suboption += byte
else:
yield byte
elif self.mode == M_IAC_SEEN:
if byte == IAC:
# interpret as command doubled -> insert character
# itself
if self.suboption is not None:
self.suboption += byte
else:
yield byte
self.mode = M_NORMAL
elif byte == SB:
# sub option start
self.suboption = bytearray()
self.mode = M_NORMAL
elif byte == SE:
# sub option end -> process it now
self._telnetProcessSubnegotiation(bytes(self.suboption))
self.suboption = None
self.mode = M_NORMAL
elif byte in (DO, DONT, WILL, WONT):
# negotiation
self.telnet_command = byte
self.mode = M_NEGOTIATE
else:
# other telnet commands
self._telnetProcessCommand(byte)
self.mode = M_NORMAL
elif self.mode == M_NEGOTIATE: # DO, DONT, WILL, WONT was received, option now following
self._telnetNegotiateOption(self.telnet_command, byte)
self.mode = M_NORMAL
# - incoming telnet commands and options
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