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, getopt, urlparse, time, random
62 import threading, Queue, SocketServer
63 import irc.client, logging
65 import simplejson as json # Faster, also makes us Python-2.4-compatible
71 # Sketch of implementation:
73 # One Irker object manages multiple IRC sessions. It holds a map of
74 # Dispatcher objects, one per (server, port) combination, which are
75 # responsible for routing messages to one of any number of Connection
76 # objects that do the actual socket conversations. The reason for the
77 # Dispatcher layer is that IRC daemons limit the number of channels a
78 # client (that is, from the daemon's point of view, a socket) can be
79 # joined to, so each session to a server needs a flock of Connection
80 # instances each with its own socket.
82 # Connections are timed out and removed when either they haven't seen a
83 # PING for a while (indicating that the server may be stalled or down)
84 # or there has been no message traffic to them for a while, or
85 # even if the queue is nonempty but efforts to connect have failed for
88 # There are multiple threads. One accepts incoming traffic from all servers.
89 # Each Connection also has a consumer thread and a thread-safe message queue.
90 # The program main appends messages to queues as JSON requests are received;
91 # the consumer threads try to ship them to servers. When a socket write
92 # stalls, it only blocks an individual consumer thread; if it stalls long
93 # enough, the session will be timed out.
95 # Message delivery is thus not reliable in the face of network stalls,
96 # but this was considered acceptable because IRC (notoriously) has the
97 # same problem - there is little point in reliable delivery to a relay
98 # that is down or unreliable.
100 # This code uses only NICK, JOIN, MODE, and PRIVMSG. It is strictly
101 # compliant to RFC1459, except for the interpretation and use of the
102 # DEAF and CHANLIMIT and (obsolete) MAXCHANNELS features. CHANLIMIT
103 # is as described in the Internet RFC draft
104 # draft-brocklesby-irc-isupport-03 at <http://www.mirc.com/isupport.html>.
107 def __init__(self, irkerd, servername, port):
109 self.servername = servername
111 self.nick_trial = None
112 self.connection = None
113 self.status = "unseen"
114 self.last_xmit = time.time()
115 self.last_ping = time.time()
116 self.channels_joined = []
117 self.channel_limits = {}
118 # The consumer thread
119 self.queue = Queue.Queue()
121 def nickname(self, n=None):
122 "Return a name for the nth server connection."
125 return (NAMESTYLE % n)
126 def handle_ping(self):
127 "Register the fact that the server has pinged this connection."
128 self.last_ping = time.time()
129 def handle_welcome(self):
130 "The server says we're OK, with a non-conflicting nick."
131 self.status = "ready"
132 self.irker.debug(1, "nick %s accepted" % self.nickname())
133 def handle_badnick(self):
134 "The server says our nick has a conflict."
135 self.irker.debug(1, "nick %s rejected" % self.nickname())
136 # Randomness prevents a malicious user or bot from antcipating the
137 # next trial name in order to block us from completing the handshake.
138 self.nick_trial += random.randint(1, 3)
139 self.connection.nick(self.nickname())
140 def handle_disconnect(self):
141 "Server disconnected us for flooding or some other reason."
142 self.connection = None
143 def handle_kick(self, outof):
145 self.status = "handshaking"
147 self.channels_joined.remove(outof)
149 self.irker.logerr("kicked by %s from %s that's not joined"
150 % (self.servername, outof))
152 while not self.queue.empty():
153 (channel, message) = self.queue.get()
155 qcopy.append((channel, message))
156 for (channel, message) in qcopy:
157 self.queue.put((channel, message))
158 self.status = "ready"
159 def enqueue(self, channel, message):
160 "Enque a message for transmission."
161 if self.thread is None or not self.thread_is.alive():
162 self.thread = threading.Thread(target=self.dequeue)
163 self.thread.setDaemon(True)
165 self.queue.put((channel, message))
167 "Try to ship pending messages from the queue."
169 # We want to be kind to the IRC servers and not hold unused
170 # sockets open forever, so they have a time-to-live. The
171 # loop is coded this particular way so that we can drop
172 # the actual server connection when its time-to-live
173 # expires, then reconnect and resume transmission if the
174 # queue fills up again.
175 if not self.connection:
176 self.connection = self.irker.irc.server()
177 self.connection.context = self
178 # Try to avoid colliding with other instances
179 self.nick_trial = random.randint(1, 990)
180 self.channels_joined = []
181 # This will throw irc.client.ServerConnectionError on failure
183 self.connection.connect(self.servername,
185 nickname=self.nickname(),
187 ircname="irker relaying client")
188 self.status = "handshaking"
189 self.irker.debug(1, "XMIT_TTL bump (%s connection) at %s" % (self.servername, time.asctime()))
190 self.last_xmit = time.time()
191 except irc.client.ServerConnectionError:
192 self.status = "disconnected"
193 elif self.status == "handshaking":
194 # Don't buzz on the empty-queue test while we're handshaking
195 time.sleep(ANTI_BUZZ_DELAY)
196 elif self.queue.empty():
197 # Queue is empty, at some point we want to time out
198 # the connection rather than holding a socket open in
199 # the server forever.
201 if now > self.last_xmit + XMIT_TTL \
202 or now > self.last_ping + PING_TTL:
203 self.irker.debug(1, "timing out inactive connection to %s at %s" % (self.servername, time.asctime()))
204 self.connection.context = None
205 self.connection.quit("transmission timeout")
206 self.connection.close()
207 self.connection = None
208 self.status = "disconnected"
210 # Prevent this thread from hogging the CPU by pausing
211 # for just a little bit after the queue-empty check.
212 # As long as this is less that the duration of a human
213 # reflex arc it is highly unlikely any human will ever
215 time.sleep(ANTI_BUZZ_DELAY)
216 elif self.status == "disconnected" \
217 and time.time() > self.last_xmit + DISCONNECT_TTL:
218 # Queue is nonempty, but the IRC server might be down. Letting
219 # failed connections retain queue space forever would be a
221 self.status = "expired"
223 elif self.status == "unseen" \
224 and time.time() > self.last_xmit + UNSEEN_TTL:
225 # Nasty people could attempt a denial-of-service
226 # attack by flooding us with requests with invalid
227 # servernames. We guard against this by rapidly
228 # expiring connections that have a nonempty queue but
229 # have never had a successful open.
230 self.status = "expired"
232 elif self.status == "ready":
233 (channel, message) = self.queue.get()
234 if channel not in self.channels_joined:
235 self.channels_joined.append(channel)
236 self.connection.join(channel)
237 self.irker.debug(1, "joining %s on %s." % (channel, self.servername))
238 for segment in message.split("\n"):
239 self.connection.privmsg(channel, segment)
240 time.sleep(ANTI_FLOOD_DELAY)
241 self.last_xmit = time.time()
242 self.irker.debug(1, "XMIT_TTL bump (%s transmission) at %s" % (self.servername, time.asctime()))
243 self.queue.task_done()
245 "Should this connection not be scavenged?"
246 return self.status != "expired"
247 def joined_to(self, channel):
248 "Is this connection joined to the specified channel?"
249 return channel in self.channels_joined
250 def accepting(self, channel):
251 "Can this connection accept a join of this channel?"
252 if self.channel_limits:
254 for already in self.channels_joined:
255 if already[0] == channel[0]:
257 return match_count < self.channel_limits.get(channel[0], CHANNEL_MAX)
259 return len(self.channels_joined) < CHANNEL_MAX
262 "Represent a transmission target."
263 def __init__(self, url):
264 parsed = urlparse.urlparse(url)
265 irchost, _, ircport = parsed.netloc.partition(':')
268 self.servername = irchost
269 # IRC channel names are case-insensitive. If we don't smash
270 # case here we may run into problems later. There was a bug
271 # observed on irc.rizon.net where an irkerd user specified #Channel,
272 # got kicked, and irkerd crashed because the server returned
273 # "#channel" in the notification that our kick handler saw.
274 self.channel = parsed.path.lstrip('/').lower()
275 if self.channel and self.channel[0] not in "#&+":
276 self.channel = "#" + self.channel
277 self.port = int(ircport)
279 "Both components must be present for a valid target."
280 return self.servername and self.channel
282 "Return a hashable tuple representing the destination server."
283 return (self.servername, self.port)
286 "Manage connections to a particular server-port combination."
287 def __init__(self, irkerd, servername, port):
289 self.servername = servername
291 self.connections = []
292 def dispatch(self, channel, message):
293 "Dispatch messages for our server-port combination."
294 connections = [x for x in self.connections if x.live()]
295 eligibles = [x for x in connections if x.joined_to(channel)] \
296 or [x for x in connections if x.accepting(channel)]
298 newconn = Connection(self.irker,
301 self.connections.append(newconn)
302 eligibles = [newconn]
303 eligibles[0].enqueue(channel, message)
305 "Does this server-port combination have any live connections?"
306 self.connections = [x for x in self.connections if x.live()]
307 return len(self.connections) > 0
309 "Return the time of the most recent transmission."
310 return max([x.last_xmit for x in self.connections])
313 "Persistent IRC multiplexer."
314 def __init__(self, debuglevel=0):
315 self.debuglevel = debuglevel
316 self.irc = irc.client.IRC()
317 self.irc.add_global_handler("ping", self._handle_ping)
318 self.irc.add_global_handler("welcome", self._handle_welcome)
319 self.irc.add_global_handler("erroneusnickname", self._handle_badnick)
320 self.irc.add_global_handler("nicknameinuse", self._handle_badnick)
321 self.irc.add_global_handler("nickcollision", self._handle_badnick)
322 self.irc.add_global_handler("unavailresource", self._handle_badnick)
323 self.irc.add_global_handler("featurelist", self._handle_features)
324 self.irc.add_global_handler("disconnect", self._handle_disconnect)
325 self.irc.add_global_handler("kick", self._handle_kick)
326 thread = threading.Thread(target=self.irc.process_forever)
327 thread.setDaemon(True)
328 self.irc._thread = thread
331 def logerr(self, errmsg):
332 "Log a processing error."
333 sys.stderr.write("irkerd: " + errmsg + "\n")
334 def debug(self, level, errmsg):
335 "Debugging information."
336 if self.debuglevel >= level:
337 sys.stderr.write("irkerd: %s\n" % errmsg)
338 def _handle_ping(self, connection, _event):
339 "PING arrived, bump the last-received time for the connection."
340 if connection.context:
341 connection.context.handle_ping()
342 def _handle_welcome(self, connection, _event):
343 "Welcome arrived, nick accepted for this connection."
344 if connection.context:
345 connection.context.handle_welcome()
346 def _handle_badnick(self, connection, _event):
347 "Nick not accepted for this connection."
348 if connection.context:
349 connection.context.handle_badnick()
350 def _handle_features(self, connection, event):
351 "Determine if and how we can set deaf mode."
352 if connection.context:
353 cxt = connection.context
354 for lump in event.arguments():
355 if lump.startswith("DEAF="):
356 connection.mode(cxt.nickname(), "+"+lump[5:])
357 elif lump.startswith("MAXCHANNELS="):
360 cxt.channel_limits[pref] = m
361 self.debug(1, "%s maxchannels is %d"
362 % (connection.server, m))
363 elif lump.startswith("CHANLIMIT=#:"):
364 limits = lump[10:].split(",")
367 (prefixes, limit) = token.split(":")
370 cxt.channel_limits[c] = limit
371 self.debug(1, "%s channel limit map is %s"
372 % (connection.server, cxt.channel_limits))
374 self.logerr("ill-formed CHANLIMIT property")
375 def _handle_disconnect(self, connection, _event):
376 "Server hung up the connection."
377 self.debug(1, "server %s disconnected" % connection.server)
378 if connection.context:
379 connection.context.handle_disconnect()
380 def _handle_kick(self, connection, event):
381 "Server hung up the connection."
382 self.debug(1, "irker has been kicked from %s on %s" % (event.target(), connection.server))
383 if connection.context:
384 connection.context.handle_kick(event.target())
385 def handle(self, line):
386 "Perform a JSON relay request."
388 request = json.loads(line.strip())
389 if not isinstance(request, dict):
390 self.logerr("request is not a JSON dictionary: %r" % request)
391 elif "to" not in request or "privmsg" not in request:
392 self.logerr("malformed request - 'to' or 'privmsg' missing: %r" % request)
394 channels = request['to']
395 message = request['privmsg']
396 if not isinstance(channels, (list, unicode)) \
397 and not isinstance(message, unicode):
398 self.logerr("malformed request - unexpected types: %r" % request)
400 if isinstance(channels, unicode):
401 channels = [channels]
403 if not type(url) in (type(""), type(u"")):
404 self.logerr("malformed request - URL has unexpected type: %r" % url)
407 if not target.valid():
409 if target.server() not in self.servers:
410 self.servers[target.server()] = Dispatcher(self, target.servername, target.port)
411 self.servers[target.server()].dispatch(target.channel, message)
412 # GC dispatchers with no active connections
413 servernames = self.servers.keys()
414 for servername in servernames:
415 if not self.servers[servername].live():
416 del self.servers[servername]
417 # If we might be pushing a resource limit
418 # even after garbage collection, remove a
419 # session. The goal here is to head off
420 # DoS attacks that aim at exhausting
421 # thread space or file descriptors. The
422 # cost is that attempts to DoS this
423 # service will cause lots of join/leave
424 # spam as we scavenge old channels after
425 # connecting to new ones. The particular
426 # method used for selecting a session to
427 # be terminated doesn't matter much; we
428 # choose the one longest idle on the
429 # assumption that message activity is likely
432 oldtime = float("inf")
433 if len(self.servers) >= CONNECTION_MAX:
434 for (name, server) in self.servers.items():
435 if server.last_xmit() < oldtime:
437 oldtime = server.last_xmit()
438 del self.servers[oldest]
440 self.logerr("can't recognize JSON on input: %r" % line)
442 self.logerr("wildly malformed JSON blew the parser stack.")
444 class IrkerTCPHandler(SocketServer.StreamRequestHandler):
447 line = self.rfile.readline()
450 irker.handle(line.strip())
452 class IrkerUDPHandler(SocketServer.BaseRequestHandler):
454 data = self.request[0].strip()
455 #socket = self.request[1]
458 if __name__ == '__main__':
460 (options, arguments) = getopt.getopt(sys.argv[1:], "d:V")
461 for (opt, val) in options:
462 if opt == '-d': # Enable debug/progress messages
465 logging.basicConfig(level=logging.DEBUG)
466 elif opt == '-V': # Emit version and exit
467 sys.stdout.write("irkerd version %s\n" % version)
469 irker = Irker(debuglevel=debuglvl)
470 irker.debug(1, "irkerd version %s" % version)
471 tcpserver = SocketServer.TCPServer((HOST, PORT), IrkerTCPHandler)
472 udpserver = SocketServer.UDPServer((HOST, PORT), IrkerUDPHandler)
473 for server in [tcpserver, udpserver]:
474 server = threading.Thread(target=server.serve_forever)
475 server.setDaemon(True)
480 except KeyboardInterrupt: