20210911
This commit is contained in:
lampmerchant
parent
02b2ac1a90
commit
e7cbd5e519
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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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from .receiver import TashTalkReceiver
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from .transmitter import TashTalkTransmitter
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from .misc import hexdump_lines, NodeIdSet
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'''Code for calculating CRCs ('frame check sequences') in the bizarre way that SDLC defined and LocalTalk followed.'''
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LT_CRC_LUT = (
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0x0000, 0x1189, 0x2312, 0x329B, 0x4624, 0x57AD, 0x6536, 0x74BF, 0x8C48, 0x9DC1, 0xAF5A, 0xBED3, 0xCA6C, 0xDBE5, 0xE97E, 0xF8F7,
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0x1081, 0x0108, 0x3393, 0x221A, 0x56A5, 0x472C, 0x75B7, 0x643E, 0x9CC9, 0x8D40, 0xBFDB, 0xAE52, 0xDAED, 0xCB64, 0xF9FF, 0xE876,
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0x2102, 0x308B, 0x0210, 0x1399, 0x6726, 0x76AF, 0x4434, 0x55BD, 0xAD4A, 0xBCC3, 0x8E58, 0x9FD1, 0xEB6E, 0xFAE7, 0xC87C, 0xD9F5,
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0x3183, 0x200A, 0x1291, 0x0318, 0x77A7, 0x662E, 0x54B5, 0x453C, 0xBDCB, 0xAC42, 0x9ED9, 0x8F50, 0xFBEF, 0xEA66, 0xD8FD, 0xC974,
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0x4204, 0x538D, 0x6116, 0x709F, 0x0420, 0x15A9, 0x2732, 0x36BB, 0xCE4C, 0xDFC5, 0xED5E, 0xFCD7, 0x8868, 0x99E1, 0xAB7A, 0xBAF3,
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0x5285, 0x430C, 0x7197, 0x601E, 0x14A1, 0x0528, 0x37B3, 0x263A, 0xDECD, 0xCF44, 0xFDDF, 0xEC56, 0x98E9, 0x8960, 0xBBFB, 0xAA72,
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0x6306, 0x728F, 0x4014, 0x519D, 0x2522, 0x34AB, 0x0630, 0x17B9, 0xEF4E, 0xFEC7, 0xCC5C, 0xDDD5, 0xA96A, 0xB8E3, 0x8A78, 0x9BF1,
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0x7387, 0x620E, 0x5095, 0x411C, 0x35A3, 0x242A, 0x16B1, 0x0738, 0xFFCF, 0xEE46, 0xDCDD, 0xCD54, 0xB9EB, 0xA862, 0x9AF9, 0x8B70,
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0x8408, 0x9581, 0xA71A, 0xB693, 0xC22C, 0xD3A5, 0xE13E, 0xF0B7, 0x0840, 0x19C9, 0x2B52, 0x3ADB, 0x4E64, 0x5FED, 0x6D76, 0x7CFF,
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0x9489, 0x8500, 0xB79B, 0xA612, 0xD2AD, 0xC324, 0xF1BF, 0xE036, 0x18C1, 0x0948, 0x3BD3, 0x2A5A, 0x5EE5, 0x4F6C, 0x7DF7, 0x6C7E,
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0xA50A, 0xB483, 0x8618, 0x9791, 0xE32E, 0xF2A7, 0xC03C, 0xD1B5, 0x2942, 0x38CB, 0x0A50, 0x1BD9, 0x6F66, 0x7EEF, 0x4C74, 0x5DFD,
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0xB58B, 0xA402, 0x9699, 0x8710, 0xF3AF, 0xE226, 0xD0BD, 0xC134, 0x39C3, 0x284A, 0x1AD1, 0x0B58, 0x7FE7, 0x6E6E, 0x5CF5, 0x4D7C,
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0xC60C, 0xD785, 0xE51E, 0xF497, 0x8028, 0x91A1, 0xA33A, 0xB2B3, 0x4A44, 0x5BCD, 0x6956, 0x78DF, 0x0C60, 0x1DE9, 0x2F72, 0x3EFB,
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0xD68D, 0xC704, 0xF59F, 0xE416, 0x90A9, 0x8120, 0xB3BB, 0xA232, 0x5AC5, 0x4B4C, 0x79D7, 0x685E, 0x1CE1, 0x0D68, 0x3FF3, 0x2E7A,
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0xE70E, 0xF687, 0xC41C, 0xD595, 0xA12A, 0xB0A3, 0x8238, 0x93B1, 0x6B46, 0x7ACF, 0x4854, 0x59DD, 0x2D62, 0x3CEB, 0x0E70, 0x1FF9,
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0xF78F, 0xE606, 0xD49D, 0xC514, 0xB1AB, 0xA022, 0x92B9, 0x8330, 0x7BC7, 0x6A4E, 0x58D5, 0x495C, 0x3DE3, 0x2C6A, 0x1EF1, 0x0F78,
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)
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class CrcCalculator:
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'''Utility class to calculate the CRC of a frame.'''
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def __init__(self):
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self.reset()
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def reset(self):
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'''Reset the CRC calculator as though no data had been fed into it.'''
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self.reg = 0xFFFF
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def feed_byte(self, byte):
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'''Feed a single byte (an integer between 0 and 255) into the CRC calculator.'''
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index = (self.reg & 0xFF) ^ byte
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self.reg = LT_CRC_LUT[index] ^ (self.reg >> 8)
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def feed(self, data):
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'''Feed a bytes-like object into the CRC calculator.'''
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for byte in data:
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self.feed_byte(byte)
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def byte1(self):
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'''Returns the first byte of the frame CRC.'''
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return (self.reg & 0xFF) ^ 0xFF
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def byte2(self):
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'''Returns the second byte of the frame CRC.'''
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return (self.reg >> 8) ^ 0xFF
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def is_okay(self):
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'''If the CRC has been fed into the calculator and is correct, this will return True.'''
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return True if self.reg == 61624 else False # this is the binary constant on B-22 of Inside Appletalk, but backwards
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'''Miscellaneous functions and classes.'''
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import time
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def hexdump_lines(data):
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'''Utility function to make a hex dump of a bytes-like object.'''
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for index in range(0, len(data), 16):
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line_data = data[index:index+16]
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yield '%06X %-47s %-16s' % (index,
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' '.join(('%02X' % i) for i in line_data),
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''.join((chr(i) if 32 <= i < 127 else '.') for i in line_data))
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class NodeIdSet:
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def __init__(self, sender, timeout=600):
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self.sender = sender
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self.timeout = timeout
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self.node_ids = {}
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def touch(self, node_id):
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if node_id in self.node_ids:
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self.node_ids[node_id] = time.monotonic()
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else:
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self.node_ids[node_id] = time.monotonic()
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self.sender.set_node_ids(self.node_ids.keys())
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def check_expiration(self):
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expired = set()
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now = time.monotonic()
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for node_id, last_time in self.node_ids.items():
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if now - last_time >= self.timeout: expired.add(node_id)
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if expired:
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for node_id in expired: self.node_ids.pop(node_id)
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self.sender.set_node_ids(self.node_ids.keys())
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def __contains__(self, item):
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return True if item in self.node_ids else False
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'''Code to abstract TashTalk receiver side.'''
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from collections import deque
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from itertools import chain
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import logging
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from .lt_crc import CrcCalculator
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from .misc import hexdump_lines
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class TashTalkReceiver:
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'''Abstracted TashTalk receiver that deals in frames rather than raw serial port data.'''
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def __init__(self, serial_obj):
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self.serial_obj = serial_obj
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self.crc = CrcCalculator()
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self.next_frame = deque()
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self.escape_on = False
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self.frames = deque()
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def _reset(self):
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self.crc.reset()
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self.next_frame.clear()
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self.escape_on = False
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def _feed(self, data):
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for byte in data:
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if self.escape_on:
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if byte == 0xFF: # literal 0 byte
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self.next_frame.append(0)
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self.crc.feed_byte(0)
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elif byte == 0xFD: # Frame Delimiter
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if self.crc.is_okay() and len(self.next_frame) >= 5:
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frame = bytes(self.next_frame)
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if logging.getLogger().isEnabledFor(logging.DEBUG):
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logging.debug('\n'.join(chain(('TashTalk received good frame:',), (line for line in hexdump_lines(frame)))))
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self.frames.append(frame)
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else:
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if logging.getLogger().isEnabledFor(logging.INFO):
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frame = bytes(self.next_frame)
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logging.info('\n'.join(chain(('TashTalk received bad frame:',), (line for line in hexdump_lines(frame)))))
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self._reset()
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elif byte == 0xFE: # Framing Error
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if logging.getLogger().isEnabledFor(logging.INFO):
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frame = bytes(self.next_frame)
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logging.info('\n'.join(chain(('TashTalk detected framing error:',), (line for line in hexdump_lines(frame)))))
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self._reset()
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elif byte == 0xFA: # Frame Aborted
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if logging.getLogger().isEnabledFor(logging.INFO):
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frame = bytes(self.next_frame)
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logging.info('\n'.join(chain(('TashTalk detected aborted frame:',), (line for line in hexdump_lines(frame)))))
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self._reset()
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self.escape_on = False
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elif byte == 0x00:
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self.escape_on = True
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else:
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self.next_frame.append(byte)
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self.crc.feed_byte(byte)
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def _service_serial_port(self):
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while True:
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data = self.serial_obj.read(16384)
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if not data: break
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logging.debug('read %d bytes from TashTalk', len(data))
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self._feed(data)
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def get_frames(self):
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'''Get data from TashTalk and yield any frames that were completed since the last time this was called.'''
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self._service_serial_port()
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for frame in self.frames:
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yield frame
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self.frames.clear()
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def fileno(self):
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'''This function makes it possible to pass a receiver into select.select, at least on POSIX platforms.'''
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return self.serial_obj.fileno()
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'''Code to abstract TashTalk transmitter side.'''
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from itertools import chain
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import logging
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from .lt_crc import CrcCalculator
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from .misc import hexdump_lines
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class TashTalkTransmitter:
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'''Abstracted TashTalk transmitter that deals in commands rather than raw serial port data.'''
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def __init__(self, serial_obj):
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self.serial_obj = serial_obj
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def initialize(self):
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'''Initialize TashTalk by bringing it to a known-good state and setting it not to respond to any node IDs.'''
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self.known_state()
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self.set_node_ids(())
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def known_state(self):
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'''Return TashTalk to the known state where it's awaiting a command byte.'''
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self.serial_obj.write(b'\x00' * 1024)
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logging.debug('return to known state sent to TashTalk')
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def send_frame(self, frame):
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'''Accept a frame without CRC bytes, check it for validity, and send it to TashTalk with the correct CRC bytes.'''
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if len(frame) < 3:
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raise ValueError('frame must be 3 bytes minimum')
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elif len(frame) == 3 and not (frame[2] & 0x80):
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raise ValueError('a 3-byte frame must be a control frame')
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elif (frame[2] & 0x80) and not len(frame) == 3:
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raise ValueError('a control frame must be 3 bytes in length')
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elif len(frame) == 4:
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raise ValueError('invalid frame length')
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elif len(frame) > 603:
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raise ValueError('frame may be 603 bytes maximum')
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elif len(frame) >= 5 and (((frame[3] & 0x3) << 8) | frame[4]) != len(frame) - 3:
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raise ValueError('frame length does not match frame length field')
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crc = CrcCalculator()
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crc.feed(frame)
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frame += bytes((crc.byte1(), crc.byte2()))
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self.serial_obj.write(b'\x01' + frame)
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if logging.getLogger().isEnabledFor(logging.DEBUG):
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logging.debug('\n'.join(chain(('frame sent to TashTalk:',), (line for line in hexdump_lines(frame)))))
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def set_node_ids(self, ids):
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'''Set the node IDs for which TashTalk should respond to RTS, CTS, and ENQ control frames.'''
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id_bitmap = bytearray(32)
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for id in ids:
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byte_num, bit_num = divmod(id, 8)
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id_bitmap[byte_num] |= (1 << bit_num)
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self.serial_obj.write(b'\x02' + id_bitmap)
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logging.debug('ID bitmap sent to TashTalk: %s', ', '.join(hex(id) for id in ids) if ids else '(empty)')
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#!/usr/bin/env python3
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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import argparse
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import logging
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import sys
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import serial
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from daemon.protocol.ltoudp import LtoudpDaemon
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def main(argv):
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parser = argparse.ArgumentParser(description='Userspace daemon for TashTalk.')
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parser.add_argument('--device', '-d', metavar='DEVICE', required=True, help='serial device where TashTalk is connected')
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parser.add_argument('--verbose', '-v', action='count', default=0, help='increase verbosity of logging')
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args = parser.parse_args(argv[1:])
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logging.basicConfig(level=logging.DEBUG if args.verbose > 1 else logging.INFO if args.verbose else logging.WARNING,
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format='[%(levelname)s] %(message)s')
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serial_obj = serial.Serial(port=args.device, baudrate=1000000, timeout=0, rtscts=True)
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daemon = LtoudpDaemon(serial_obj)
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daemon.initialize()
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daemon.run()
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if __name__ == '__main__': sys.exit(main(sys.argv))
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