1 ## Airhook Protocol http://airhook.org/protocol.html
2 ## Copyright 2002, Andrew Loewenstern, All Rights Reserved
4 from random import uniform as rand
5 from struct import pack, unpack
7 from StringIO import StringIO
9 from bisect import insort_left
11 from twisted.internet import protocol
12 from twisted.internet import reactor
22 MAX_PACKET_SIZE = 1480
29 def setDelegate(self, delegate):
30 self.delegate = delegate
31 def getDelegate(self):
33 def msgDelegate(self, method, args=(), kwargs={}):
34 if hasattr(self, 'delegate') and hasattr(self.delegate, method) and callable(getattr(self.delegate, method)):
35 apply(getattr(self.delegate, method) , args, kwargs)
37 class Airhook(protocol.DatagramProtocol):
39 def __init__(self, connection_class):
40 self.connection_class = connection_class
41 def startProtocol(self):
44 def datagramReceived(self, datagram, addr):
46 if not flag & FLAG_AIRHOOK: # first bit always must be 0
47 conn = self.connectionForAddr(addr)
48 conn.datagramReceieved(datagram)
50 def connectionForAddr(self, addr):
51 if not self.connections.has_key(addr):
52 conn = connection_class(self.transport, addr, self.delegate)
53 self.connections[addr] = conn
54 return self.connections[addr]
58 def __init__(self, msg):
60 self.oseq = ord(msg[1])
61 self.seq = unpack("!H", msg[2:4])[0]
62 self.flags = ord(msg[0])
69 if self.flags & FLAG_OBSERVED:
70 self.observed = unpack("!L", msg[skip:skip+4])[0]
72 if self.flags & FLAG_SESSION:
73 self.session = unpack("!L", msg[skip:skip+4])[0]
75 if self.flags & FLAG_NEXT:
76 self.next = ord(msg[skip])
78 if self.flags & FLAG_MISSED:
79 num = ord(msg[skip]) + 1
82 self.missed.append( ord(msg[skip+i]))
84 if self.flags & FLAG_NEXT:
85 while len(msg) - skip > 0:
86 n = ord(msg[skip]) + 1
88 self.msgs.append( msg[skip:skip+n])
91 class AirhookConnection(Delegate):
92 def __init__(self, transport, addr, delegate):
93 self.delegate = delegate
95 type, self.host, self.port = addr
96 self.transport = transport
98 self.outSeq = 0 # highest sequence we have sent, can't be 255 more than obSeq
99 self.obSeq = -1 # highest sequence confirmed by remote
100 self.inSeq = 0 # last received sequence
101 self.observed = None # their session id
102 self.sessionID = long(rand(0, 2**32)) # our session id
104 self.lastTransmit = -1 # time we last sent a packet with messages
105 self.lastReceieved = 0 # time we last received a packet with messages
106 self.lastTransmitSeq = -1 # last sequence we sent a packet
109 self.outMsgs = [None] * 256 # outgoing messages (seq sent, message), index = message number
110 self.outMsgNums = [None] * 256 # outgoing message numbers i = outNum % 256
111 self.next = -1 # next outgoing message number
112 self.omsgq = [] # list of messages to go out
113 self.imsgq = [] # list of messages coming in
114 self.sendSession = None # send session/observed fields until obSeq > sendSession
118 def resetMessages(self):
120 self.inMsg = 0 # next incoming message number
122 def datagramReceived(self, datagram):
125 response = 0 # if we know we have a response now (like resending missed packets)
126 p = AirhookPacket(datagram)
128 # check for state change
129 if self.state == pending:
130 if p.observed != None and p.session != None:
131 if p.observed == self.sessionID:
132 self.observed = p.session
133 self.state = confirmed
137 elif p.session != None:
138 self.observed = p.session
141 elif self.state == sent:
142 if p.observed != None and p.session != None:
143 if p.observed == self.sessionID:
144 self.observed = p.session
145 self.sendSession = self.outSeq
146 self.state = confirmed
147 if p.session != None:
148 if not self.observed:
149 self.observed = p.session
150 elif self.observed != p.session:
155 elif self.state == confirmed:
156 if p.session != None or p.observed != None :
157 if p.session != self.observed or p.observed != self.sessionID:
163 if self.state != pending:
167 # check to make sure sequence number isn't out of wack
168 assert (p.seq - self.inSeq) % 2**16 < 256
170 # see if they need us to resend anything
173 if self.outMsgs[i] != None:
174 self.omsgq.insert(0, self.outMsgs[i])
175 self.outMsgs[i] = None
177 # see if we need them to send anything
179 if p.next == 0 and self.inMsg == -1:
181 missed_count = (p.next - self.inMsg) % 256
183 self.lastReceived = time()
184 for i in range(missed_count):
185 missed += [(self.outSeq, (self.inMsg + i) % 256)]
187 self.weMissed += missed
188 self.inMsg = (p.next + len(p.msgs)) % 256
193 if self.state == confirmed:
194 # unpack the observed sequence
195 tseq = unpack('!H', pack('!H', self.outSeq)[0] + chr(p.oseq))[0]
196 if ((self.outSeq - tseq)) % 2**16 > 255:
197 tseq = unpack('!H', chr(ord(pack('!H', self.outSeq)[0]) - 1) + chr(p.oseq))[0]
201 reactor.callLater(0, self.sendNext)
202 self.lastReceived = time()
207 header = chr(self.inSeq & 255) + pack("!H", self.outSeq)
212 if self.state == pending:
213 flags = flags | FLAG_SESSION
214 ids += pack("!L", self.sessionID)
216 elif self.state == sent:
217 if self.observed != None:
218 flags = flags | FLAG_SESSION | FLAG_OBSERVED
219 ids += pack("!LL", self.observed, self.sessionID)
221 flags = flags | FLAG_SESSION
222 ids += pack("!L", self.sessionID)
225 if self.state == sent or self.sendSession:
226 if self.state == confirmed and (self.obSeq - self.sendSession) % 2**16 < 256:
227 self.sendSession = None
229 flags = flags | FLAG_SESSION | FLAG_OBSERVED
230 ids += pack("!LL", self.observed, self.sessionID)
233 self.weMissed = filter(lambda a: a[0] > self.obSeq, self.weMissed)
236 flags = flags | FLAG_MISSED
237 missed += chr(len(self.weMissed) - 1)
238 for i in self.weMissed:
241 if self.state == confirmed and self.omsgq:
242 first = (self.next + 1) % 256
243 while len(self.omsgq) and (len(self.omsgq[-1]) + len(msgs) + len(missed) + len(ids) + len(header) + 1 <= MAX_PACKET_SIZE) :
247 highest = self.outMsgNums[self.obSeq % 256]
248 if self.next != -1 and (self.next + 1) % 256 == (highest - 1) % 256:
251 self.next = (self.next + 1) % 256
252 msg = self.omsgq.pop()
253 msgs += chr(len(msg) - 1) + msg
254 self.outMsgs[self.next] = msg
256 flags = flags | FLAG_NEXT
258 self.lastTransmitSeq = self.outSeq
259 self.outMsgNums[self.outSeq % 256] = first
262 self.outMsgNums[self.outSeq % 256] = 0
264 self.outMsgNums[self.outSeq % 256] = self.next
266 if (self.obSeq - self.lastTransmitSeq) % 2**16 > 256 and self.outMsgNums[self.obSeq % 256] != self.next and not flags & FLAG_NEXT:
267 flags = flags | FLAG_NEXT
268 ids += chr((self.next + 1) % 256)
269 packet = chr(flags) + header + ids + missed + msgs
270 self.outSeq = (self.outSeq + 1) % 2**16
271 self.lastTransmit = time()
272 self.transport.write(packet)
274 if self.omsgq and (self.next + 1) % 256 != self.outMsgNums[self.obSeq % 256] and (self.outSeq - self.obSeq) % 2**16 < 256:
275 reactor.callLater(0, self.sendNext)
277 reactor.callLater(1, self.sendNext)
280 def dataCameIn(self):
281 self.msgDelegate('dataCameIn', (self.host, self.port, self.imsgq))
282 if hasattr(self, 'delegate') and self.delegate != None:
287 if not hasattr(self, 'seq'):
288 self.seq = unpack("!H", self[0:2])[0]
290 def __lt__(self, other):
291 return self.getseq() < other.getseq()
292 def __le__(self, other):
293 return self.getseq() <= other.getseq()
294 def __eq__(self, other):
295 return self.getseq() != other.getseq()
296 def __ne__(self, other):
297 return self.getseq() <= other.getseq()
298 def __gt__(self, other):
299 return self.getseq() > other.getseq()
300 def __ge__(self, other):
301 return self.getseq() >= other.getseq()
303 class OrderedConnection(AirhookConnection):
304 def __init__(self, transport, addr, delegate):
305 AirhookConnection.__init__(self, transport, addr, delegate)
310 def dataCameIn(self):
312 for msg in self.imsgq:
313 insort_left(self.q, ustr(msg))
316 while self.q and self.iseq == self.q[0].getseq():
317 data += self.q[0][2:]
318 self.iseq = (self.iseq + 1) % 2**16
321 self.msgDelegate('dataCameIn', (self.host, self.port, data))
323 def sendSomeData(self, data):
324 # chop it up and queue it up
326 p = "%s%s" % (pack("!H", self.oseq), data[:253])
329 self.oseq = (self.oseq + 1) % 2**16