100 lines
3.3 KiB
Python
100 lines
3.3 KiB
Python
from itertools import chain
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import logging
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import os
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import select
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import socket
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import struct
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import time
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from ..util import hexdump_lines, TashTalkReceiver, TashTalkTransmitter, NodeIdSet
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LTOUDP_GROUP = '239.192.76.84' # the last two octets spell 'LT'
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LTOUDP_PORT = 1954
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class LtoudpDaemon:
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def __init__(self, serial_obj):
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self.serial_obj = serial_obj
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self.receiver = None
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self.sender = None
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self.socket = None
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self.sender_id = None
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self.node_id_set = None
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def initialize(self):
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'''Set up the serial and socket connections the daemon will use.'''
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self.receiver = TashTalkReceiver(self.serial_obj)
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self.sender = TashTalkTransmitter(self.serial_obj)
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self.sender.initialize()
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self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
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self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
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self.socket.bind((LTOUDP_GROUP, LTOUDP_PORT))
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self.socket.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, 1)
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self.socket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP,
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struct.pack('=4sL', socket.inet_aton(LTOUDP_GROUP), socket.INADDR_ANY))
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#TODO add an option for this instead of forcing INADDR_ANY?
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self.sender_id = struct.pack('>L', os.getpid())
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self.node_id_set = NodeIdSet(self.sender)
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def service_tashtalk(self):
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'''Called when there is data from TashTalk that could finish one or more frames.'''
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for frame in self.receiver.get_frames():
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frame_dest = frame[0]
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frame_type = frame[2]
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if frame_type in (0x84, 0x85):
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logging.debug('not retransmitting RTS/CTS frame')
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continue
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if frame_type == 0x81 and frame_dest in self.node_id_set:
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logging.debug('not retransmitting ENQ frame that TashTalk has already responded to')
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continue
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self.socket.sendto(self.sender_id + frame[:-2], (LTOUDP_GROUP, LTOUDP_PORT))
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def service_udp(self):
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'''Called when there is a UDP datagram to be parsed and potentially forwarded.'''
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data, sender_addr = self.socket.recvfrom(65507)
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if logging.getLogger().isEnabledFor(logging.DEBUG):
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logging.debug('\n'.join(chain(('received UDP datagram from %s:' % str(sender_addr),),
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(line for line in hexdump_lines(data)))))
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if len(data) < 7:
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logging.info('ignoring invalid too-small UDP datagram')
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return
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if data[0:4] == self.sender_id: #TODO check sender_addr too
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logging.info('ignoring echoed UDP datagram')
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return
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frame = data[4:]
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frame_dest = frame[0]
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frame_src = frame[1]
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frame_type = frame[2]
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if not (frame_type == 0x81 and frame_dest == frame_src): self.node_id_set.touch(frame_src)
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self.sender.send_frame(frame)
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def run(self):
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'''Run the daemon.'''
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last_check_expiration = time.monotonic()
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while True:
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rlist, wlist, xlist = select.select((self.receiver, self.socket), (), (), 10)
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if self.receiver in rlist: self.service_tashtalk()
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if self.socket in rlist: self.service_udp()
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now = time.monotonic()
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if now - last_check_expiration >= 10:
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self.node_id_set.check_expiration()
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last_check_expiration = now
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