3 irkerd - a simple IRC multiplexer daemon
5 Listens for JSON objects of the form {'to':<irc-url>, 'privmsg':<text>}
6 and relays messages to IRC channels. Each request must be followed by
9 The <text> must be a string. The value of the 'to' attribute can be a
10 string containing an IRC URL (e.g. 'irc://chat.freenet.net/botwar') or
11 a list of such strings; in the latter case the message is broadcast to
12 all listed channels. Note that the channel portion of the URL need
13 *not* have a leading '#' unless the channel name itself does.
15 Options: -d sets the debug-message level (probably only of interest to
16 developers). The -V option prints the program version and exits.
18 Design and code by Eric S. Raymond <esr@thyrsus.com>. See the project
19 resource page at <http://www.catb.org/~esr/irker/>.
21 Requires Python 2.6 and the irc client library at version >= 2.0.2: see
23 http://pypi.python.org/pypi/irc/
25 # These things might need tuning
30 NAMESTYLE = "irker%03d" # IRC nick template - must contain '%d'
31 XMIT_TTL = (3 * 60 * 60) # Time to live, seconds from last transmit
32 PING_TTL = (15 * 60) # Time to live, seconds from last PING
33 DISCONNECT_TTL = (24 * 60 * 60) # Time to live, seconds from last connect
34 UNSEEN_TTL = 60 # Time to live, seconds since first request
35 CHANNEL_MAX = 18 # Max channels open per socket (default)
36 ANTI_FLOOD_DELAY = 0.5 # Anti-flood delay after transmissions, seconds
37 ANTI_BUZZ_DELAY = 0.09 # Anti-buzz delay after queue-empty check
39 # No user-serviceable parts below this line
41 # This black magic imports support for green threads (coroutines),
42 # then has kinky sex with the import library internals, replacing
43 # "threading" with a coroutine-using imposter. Threads then become
44 # ultra-light-weight and cooperatively scheduled.
47 eventlet.monkey_patch()
49 # With greenlets we don't worry about thread exhaustion, only the
50 # file descriptor limit (typically 1024 on modern Unixes). Thus we
51 # can handle a lot more concurrent sessions and generate less
52 # join/leave spam under heavy load.
55 # Threads are more expensive if we have to use OS-level ones
56 # rather than greenlets. We need to avoid pushing thread limits
57 # as well as fd limits. See security.txt for discussion.
61 import sys, json, getopt, urlparse, time, random
62 import threading, Queue, SocketServer
63 import irc.client, logging
67 # Sketch of implementation:
69 # One Irker object manages multiple IRC sessions. It holds a map of
70 # Dispatcher objects, one per (server, port) combination, which are
71 # responsible for routing messages to one of any number of Connection
72 # objects that do the actual socket conversations. The reason for the
73 # Dispatcher layer is that IRC daemons limit the number of channels a
74 # client (that is, from the daemon's point of view, a socket) can be
75 # joined to, so each session to a server needs a flock of Connection
76 # instances each with its own socket.
78 # Connections are timed out and removed when either they haven't seen a
79 # PING for a while (indicating that the server may be stalled or down)
80 # or there has been no message traffic to them for a while, or
81 # even if the queue is nonempty but efforts to connect have failed for
84 # There are multiple threads. One accepts incoming traffic from all servers.
85 # Each Connection also has a consumer thread and a thread-safe message queue.
86 # The program main appends messages to queues as JSON requests are received;
87 # the consumer threads try to ship them to servers. When a socket write
88 # stalls, it only blocks an individual consumer thread; if it stalls long
89 # enough, the session will be timed out.
91 # Message delivery is thus not reliable in the face of network stalls,
92 # but this was considered acceptable because IRC (notoriously) has the
93 # same problem - there is little point in reliable delivery to a relay
94 # that is down or unreliable.
96 # This code uses only NICK, JOIN, MODE, and PRIVMSG. It is strictly
97 # compliant to RFC1459, except for the interpretation and use of the
98 # DEAF and CHANLIMIT and (obsolete) MAXCHANNELS features. CHANLIMIT
99 # is as described in the Internet RFC draft
100 # draft-brocklesby-irc-isupport-03 at <http://www.mirc.com/isupport.html>.
103 def __init__(self, irkerd, servername, port):
105 self.servername = servername
107 self.nick_trial = None
108 self.connection = None
109 self.status = "unseen"
110 self.last_xmit = time.time()
111 self.last_ping = time.time()
112 self.channels_joined = []
113 self.channel_limits = {}
114 # The consumer thread
115 self.queue = Queue.Queue()
116 self.thread = threading.Thread(target=self.dequeue)
117 self.thread.daemon = True
119 def nickname(self, n=None):
120 "Return a name for the nth server connection."
123 return (NAMESTYLE % n)
124 def handle_ping(self):
125 "Register the fact that the server has pinged this connection."
126 self.last_ping = time.time()
127 def handle_welcome(self):
128 "The server says we're OK, with a non-conflicting nick."
129 self.status = "ready"
130 self.irker.debug(1, "nick %s accepted" % self.nickname())
131 def handle_badnick(self):
132 "The server says our nick has a conflict."
133 self.irker.debug(1, "nick %s rejected" % self.nickname())
134 # Randomness prevents a malicious user or bot from antcipating the
135 # next trial name in order to block us from completing the handshake.
136 self.nick_trial += random.randint(1, 3)
137 self.connection.nick(self.nickname())
138 def handle_disconnect(self):
139 "Server disconnected us for flooding or some other reason."
140 self.connection = None
141 def handle_kick(self, outof):
143 self.status = "handshaking"
145 self.channels_joined.remove(outof)
147 self.irker.logerr("kicked by %s from %s that's not joined" \
148 % (self.servername, outof))
150 while not self.queue.empty():
151 (channel, message) = self.queue.get()
153 qcopy.append((channel, message))
154 for (channel, message) in qcopy:
155 self.queue.put((channel, message))
156 self.status = "ready"
157 def enqueue(self, channel, message):
158 "Enque a message for transmission."
159 self.queue.put((channel, message))
161 "Try to ship pending messages from the queue."
163 # We want to be kind to the IRC servers and not hold unused
164 # sockets open forever, so they have a time-to-live. The
165 # loop is coded this particular way so that we can drop
166 # the actual server connection when its time-to-live
167 # expires, then reconnect and resume transmission if the
168 # queue fills up again.
169 if not self.connection:
170 self.connection = self.irker.irc.server()
171 self.connection.context = self
172 # Try to avoid colliding with other instances
173 self.nick_trial = random.randint(1, 990)
174 self.channels_joined = []
175 # This will throw irc.client.ServerConnectionError on failure
177 self.connection.connect(self.servername,
179 nickname=self.nickname(),
181 ircname="irker relaying client")
182 self.status = "handshaking"
183 self.irker.debug(1, "XMIT_TTL bump (%s connection) at %s" % (self.servername, time.asctime()))
184 self.last_xmit = time.time()
185 except irc.client.ServerConnectionError:
186 self.status = "disconnected"
187 elif self.status == "handshaking":
188 # Don't buzz on the empty-queue test while we're handshaking
189 time.sleep(ANTI_BUZZ_DELAY)
190 elif self.queue.empty():
191 # Queue is empty, at some point we want to time out
192 # the connection rather than holding a socket open in
193 # the server forever.
195 if now > self.last_xmit + XMIT_TTL \
196 or now > self.last_ping + PING_TTL:
197 self.irker.debug(1, "timing out inactive connection to %s at %s" % (self.servername, time.asctime()))
198 self.connection.context = None
199 self.connection.close()
200 self.connection = None
201 self.status = "disconnected"
203 # Prevent this thread from hogging the CPU by pausing
204 # for just a little bit after the queue-empty check.
205 # As long as this is less that the duration of a human
206 # reflex arc it is highly unlikely any human will ever
208 time.sleep(ANTI_BUZZ_DELAY)
209 elif self.status == "disconnected" \
210 and time.time() > self.last_xmit + DISCONNECT_TTL:
211 # Queue is nonempty, but the IRC server might be down. Letting
212 # failed connections retain queue space forever would be a
214 self.status = "expired"
216 elif self.status == "unseen" \
217 and time.time() > self.last_xmit + UNSEEN_TTL:
218 # Nasty people could attempt a denial-of-service
219 # attack by flooding us with requests with invalid
220 # servernames. We guard against this by rapidly
221 # expiring connections that have a nonempty queue but
222 # have never had a successful open.
223 self.status = "expired"
225 elif self.status == "ready":
226 (channel, message) = self.queue.get()
227 if channel not in self.channels_joined:
228 self.channels_joined.append(channel)
229 self.connection.join(channel)
230 self.irker.debug(1, "joining %s on %s." % (channel, self.servername))
231 for segment in message.split("\n"):
232 self.connection.privmsg(channel, segment)
233 time.sleep(ANTI_FLOOD_DELAY)
234 self.last_xmit = time.time()
235 self.irker.debug(1, "XMIT_TTL bump (%s transmission) at %s" % (self.servername, time.asctime()))
236 self.queue.task_done()
238 "Should this connection not be scavenged?"
239 return self.status != "expired"
240 def joined_to(self, channel):
241 "Is this connection joined to the specified channel?"
242 return channel in self.channels_joined
243 def accepting(self, channel):
244 "Can this connection accept a join of this channel?"
245 if self.channel_limits:
247 for already in self.channels_joined:
248 if already[0] == channel[0]:
250 return match_count < self.channel_limits.get(channel[0], CHANNEL_MAX)
252 return len(self.channels_joined) < CHANNEL_MAX
255 "Represent a transmission target."
256 def __init__(self, url):
257 parsed = urlparse.urlparse(url)
258 irchost, _, ircport = parsed.netloc.partition(':')
261 self.servername = irchost
262 # IRC channel names are case-insensitive. If we don't smash
263 # case here we may run into problems later. There was a bug
264 # observed on irc.rizon.net where an irkerd user specified #Channel,
265 # got kicked, and irkerd crashed because the server returned
266 # "#channel" in the notification that our kick handler saw.
267 self.channel = parsed.path.lstrip('/').lower()
268 if self.channel and self.channel[0] not in "#&+":
269 self.channel = "#" + self.channel
270 self.port = int(ircport)
272 "Both components must be present for a valid target."
273 return self.servername and self.channel
275 "Return a hashable tuple representing the destination server."
276 return (self.servername, self.port)
279 "Manage connections to a particular server-port combination."
280 def __init__(self, irkerd, servername, port):
282 self.servername = servername
284 self.connections = []
285 def dispatch(self, channel, message):
286 "Dispatch messages for our server-port combination."
287 connections = [x for x in self.connections if x.live()]
288 eligibles = [x for x in connections if x.joined_to(channel)] \
289 or [x for x in connections if x.accepting(channel)]
291 newconn = Connection(self.irker,
294 self.connections.append(newconn)
295 eligibles = [newconn]
296 eligibles[0].enqueue(channel, message)
298 "Does this server-port combination have any live connections?"
299 self.connections = [x for x in self.connections if x.live()]
300 return len(self.connections) > 0
302 "Return the time of the most recent transmission."
303 return max([x.last_xmit for x in self.connections])
306 "Persistent IRC multiplexer."
307 def __init__(self, debuglevel=0):
308 self.debuglevel = debuglevel
309 self.irc = irc.client.IRC()
310 self.irc.add_global_handler("ping", self._handle_ping)
311 self.irc.add_global_handler("welcome", self._handle_welcome)
312 self.irc.add_global_handler("erroneusnickname", self._handle_badnick)
313 self.irc.add_global_handler("nicknameinuse", self._handle_badnick)
314 self.irc.add_global_handler("nickcollision", self._handle_badnick)
315 self.irc.add_global_handler("unavailresource", self._handle_badnick)
316 self.irc.add_global_handler("featurelist", self._handle_features)
317 self.irc.add_global_handler("disconnect", self._handle_disconnect)
318 self.irc.add_global_handler("kick", self._handle_kick)
319 thread = threading.Thread(target=self.irc.process_forever)
321 self.irc._thread = thread
324 def logerr(self, errmsg):
325 "Log a processing error."
326 sys.stderr.write("irkerd: " + errmsg + "\n")
327 def debug(self, level, errmsg):
328 "Debugging information."
329 if self.debuglevel >= level:
330 sys.stderr.write("irkerd: %s\n" % errmsg)
331 def _handle_ping(self, connection, _event):
332 "PING arrived, bump the last-received time for the connection."
333 if connection.context:
334 connection.context.handle_ping()
335 def _handle_welcome(self, connection, _event):
336 "Welcome arrived, nick accepted for this connection."
337 if connection.context:
338 connection.context.handle_welcome()
339 def _handle_badnick(self, connection, _event):
340 "Nick not accepted for this connection."
341 if connection.context:
342 connection.context.handle_badnick()
343 def _handle_features(self, connection, event):
344 "Determine if and how we can set deaf mode."
345 if connection.context:
346 cxt = connection.context
347 for lump in event.arguments():
348 if lump.startswith("DEAF="):
349 connection.mode(cxt.nickname(), "+"+lump[5:])
350 elif lump.startswith("MAXCHANNELS="):
353 cxt.channel_limits[pref] = m
354 self.debug(1, "%s maxchannels is %d" \
355 % (connection.server, m))
356 elif lump.startswith("CHANLIMIT=#:"):
357 limits = lump[10:].split(",")
360 (prefixes, limit) = token.split(":")
363 cxt.channel_limits[c] = limit
364 self.debug(1, "%s channel limit map is %s" \
365 % (connection.server, cxt.channel_limits))
367 self.logerr("ill-formed CHANLIMIT property")
368 def _handle_disconnect(self, connection, _event):
369 "Server hung up the connection."
370 self.debug(1, "server %s disconnected" % connection.server)
371 if connection.context:
372 connection.context.handle_disconnect()
373 def _handle_kick(self, connection, event):
374 "Server hung up the connection."
375 self.debug(1, "irker has been kicked from %s on %s" % (event.target(), connection.server))
376 if connection.context:
377 connection.context.handle_kick(event.target())
378 def handle(self, line):
379 "Perform a JSON relay request."
381 request = json.loads(line.strip())
382 if type(request) != type({}):
383 self.logerr("request in tot a JSON dictionary: %s" % repr(request))
384 elif "to" not in request or "privmsg" not in request:
385 self.logerr("malformed reqest - 'to' or 'privmsg' missing: %s" % repr(request))
387 channels = request['to']
388 message = request['privmsg']
389 if type(channels) not in (type([]), type(u"")) \
390 or type(message) != type(u""):
391 self.logerr("malformed request - unexpected types: %s" % repr(request))
393 if type(channels) == type(u""):
394 channels = [channels]
396 if type(url) != type(u""):
397 self.logerr("malformed request - unexpected type: %s" % repr(request))
400 if not target.valid():
402 if target.server() not in self.servers:
403 self.servers[target.server()] = Dispatcher(self, target.servername, target.port)
404 self.servers[target.server()].dispatch(target.channel, message)
405 # GC dispatchers with no active connections
406 servernames = self.servers.keys()
407 for servername in servernames:
408 if not self.servers[servername].live():
409 del self.servers[servername]
410 # If we might be pushing a resource limit
411 # even after garbage collection, remove a
412 # session. The goal here is to head off
413 # DoS attacks that aim at exhausting
414 # thread space or file descriptors. The
415 # cost is that attempts to DoS this
416 # service will cause lots of join/leave
417 # spam as we scavenge old channels after
418 # connecting to new ones. The particular
419 # method used for selecting a session to
420 # be terminated doesn't matter much; we
421 # choose the one longest idle on the
422 # assumption that message activity is likely
425 oldtime = float("inf")
426 if len(self.servers) >= CONNECTION_MAX:
427 for (name, server) in self.servers.items():
428 if server.last_xmit() < oldtime:
430 oldtime = server.last_xmit()
431 del self.servers[oldest]
433 self.logerr("can't recognize JSON on input: %s" % repr(line))
435 self.logerr("wildly malformed JSON blew the parser stack.")
437 class IrkerTCPHandler(SocketServer.StreamRequestHandler):
440 line = self.rfile.readline()
443 irker.handle(line.strip())
445 class IrkerUDPHandler(SocketServer.BaseRequestHandler):
447 data = self.request[0].strip()
448 #socket = self.request[1]
451 if __name__ == '__main__':
453 (options, arguments) = getopt.getopt(sys.argv[1:], "d:V")
454 for (opt, val) in options:
455 if opt == '-d': # Enable debug/progress messages
458 logging.basicConfig(level=logging.DEBUG)
459 elif opt == '-V': # Emit version and exit
460 sys.stdout.write("irkerd version %s\n" % version)
462 irker = Irker(debuglevel=debuglvl)
463 tcpserver = SocketServer.TCPServer((HOST, PORT), IrkerTCPHandler)
464 tcpserver = threading.Thread(target=tcpserver.serve_forever)
465 tcpserver.daemon = True
467 udpserver = SocketServer.UDPServer((HOST, PORT), IrkerUDPHandler)
468 udpserver = threading.Thread(target=udpserver.serve_forever)
469 udpserver.daemon = True
474 except KeyboardInterrupt: