175 lines
3.1 KiB
Python
175 lines
3.1 KiB
Python
import socket
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import os
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#
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# Message classes
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#
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class Int32(int):
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pass
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class Message:
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def __init__(self, *pvalues):
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for parameter, value in zip(self.parameters, pvalues):
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assert(isinstance(value, parameter[0]))
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setattr(self, parameter[1], value)
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def __str__(self):
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p = []
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for parameter in self.parameters:
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p.append(parameter[1] + "=" + str(getattr(self, parameter[1])))
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if p:
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pf = " " + " ".join(p)
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else:
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pf = ""
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return "<" + self.__class__.__name__ + pf + ">"
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class MessageTick(Message):
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code = 0
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parameters = []
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class MessageGo(Message):
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code = 1
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parameters = []
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class MessageWrite(Message):
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code = 2
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parameters = [(str, "name"), (Int32, "index"), (int, "value")]
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class MessageRead(Message):
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code = 3
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parameters = [(str, "name"), (Int32, "index")]
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class MessageReadReply(Message):
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code = 4
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parameters = [(int, "value")]
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message_classes = [MessageTick, MessageGo, MessageWrite, MessageRead, MessageReadReply]
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#
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# Packing
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#
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def _pack_int(v):
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if v == 0:
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p = [1, 0]
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else:
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p = []
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while v != 0:
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p.append(v & 0xff)
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v >>= 8
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p.insert(0, len(p))
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return p
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def _pack_str(v):
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p = [ord(c) for c in v]
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p.append(0)
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return p
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def _pack_int32(v):
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return [
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v & 0xff,
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(v & 0xff00) >> 8,
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(v & 0xff0000) >> 16,
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(v & 0xff000000) >> 24
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]
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def _pack(message):
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r = [message.code]
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for t, p in message.parameters:
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value = getattr(message, p)
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assert(isinstance(value, t))
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if t == int:
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r += _pack_int(value)
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elif t == str:
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r += _pack_str(value)
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elif t == Int32:
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r += _pack_int32(value)
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else:
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raise TypeError
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return bytes(r)
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#
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# Unpacking
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#
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def _unpack_int(i, nchunks=None):
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v = 0
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power = 1
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if nchunks is None:
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nchunks = next(i)
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for j in range(nchunks):
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v += power*next(i)
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power *= 256
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return v
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def _unpack_str(i):
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v = ""
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c = next(i)
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while c:
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v += chr(c)
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c = next(i)
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return v
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def _unpack(message):
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i = iter(message)
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code = next(i)
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msgclass = next(filter(lambda x: x.code == code, message_classes))
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pvalues = []
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for t, p in msgclass.parameters:
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if t == int:
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v = _unpack_int(i)
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elif t == str:
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v = _unpack_str(i)
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elif t == Int32:
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v = _unpack_int(i, 4)
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else:
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raise TypeError
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pvalues.append(v)
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return msgclass(*pvalues)
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#
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# I/O
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#
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class PacketTooLarge(Exception):
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pass
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class Initiator:
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def __init__(self, sockaddr):
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self.sockaddr = sockaddr
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self.socket = socket.socket(socket.AF_UNIX, socket.SOCK_SEQPACKET)
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self._cleanup_file()
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self.socket.bind(self.sockaddr)
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self.socket.listen(1)
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def _cleanup_file(self):
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try:
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os.remove(self.sockaddr)
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except OSError:
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pass
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def accept(self):
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self.conn, addr = self.socket.accept()
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def send(self, message):
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self.conn.send(_pack(message))
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def recv(self):
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maxlen = 2048
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packet = self.conn.recv(maxlen)
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if len(packet) < 1:
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return None
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if len(packet) >= maxlen:
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raise PacketTooLarge
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return _unpack(packet)
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def __del__(self):
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if hasattr(self, "conn"):
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self.conn.shutdown(socket.SHUT_RDWR)
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self.conn.close()
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if hasattr(self, "socket"):
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self.socket.shutdown(socket.SHUT_RDWR)
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self.socket.close()
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self._cleanup_file()
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