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()
120 self.thread = threading.Thread(target=self.dequeue)
121 self.thread.daemon = True
123 def nickname(self, n=None):
124 "Return a name for the nth server connection."
127 return (NAMESTYLE % n)
128 def handle_ping(self):
129 "Register the fact that the server has pinged this connection."
130 self.last_ping = time.time()
131 def handle_welcome(self):
132 "The server says we're OK, with a non-conflicting nick."
133 self.status = "ready"
134 self.irker.debug(1, "nick %s accepted" % self.nickname())
135 def handle_badnick(self):
136 "The server says our nick has a conflict."
137 self.irker.debug(1, "nick %s rejected" % self.nickname())
138 # Randomness prevents a malicious user or bot from antcipating the
139 # next trial name in order to block us from completing the handshake.
140 self.nick_trial += random.randint(1, 3)
141 self.connection.nick(self.nickname())
142 def handle_disconnect(self):
143 "Server disconnected us for flooding or some other reason."
144 self.connection = None
145 def handle_kick(self, outof):
147 self.status = "handshaking"
149 self.channels_joined.remove(outof)
151 self.irker.logerr("kicked by %s from %s that's not joined" \
152 % (self.servername, outof))
154 while not self.queue.empty():
155 (channel, message) = self.queue.get()
157 qcopy.append((channel, message))
158 for (channel, message) in qcopy:
159 self.queue.put((channel, message))
160 self.status = "ready"
161 def enqueue(self, channel, message):
162 "Enque a message for transmission."
163 self.queue.put((channel, message))
165 "Try to ship pending messages from the queue."
167 # We want to be kind to the IRC servers and not hold unused
168 # sockets open forever, so they have a time-to-live. The
169 # loop is coded this particular way so that we can drop
170 # the actual server connection when its time-to-live
171 # expires, then reconnect and resume transmission if the
172 # queue fills up again.
173 if not self.connection:
174 self.connection = self.irker.irc.server()
175 self.connection.context = self
176 # Try to avoid colliding with other instances
177 self.nick_trial = random.randint(1, 990)
178 self.channels_joined = []
179 # This will throw irc.client.ServerConnectionError on failure
181 self.connection.connect(self.servername,
183 nickname=self.nickname(),
185 ircname="irker relaying client")
186 self.status = "handshaking"
187 self.irker.debug(1, "XMIT_TTL bump (%s connection) at %s" % (self.servername, time.asctime()))
188 self.last_xmit = time.time()
189 except irc.client.ServerConnectionError:
190 self.status = "disconnected"
191 elif self.status == "handshaking":
192 # Don't buzz on the empty-queue test while we're handshaking
193 time.sleep(ANTI_BUZZ_DELAY)
194 elif self.queue.empty():
195 # Queue is empty, at some point we want to time out
196 # the connection rather than holding a socket open in
197 # the server forever.
199 if now > self.last_xmit + XMIT_TTL \
200 or now > self.last_ping + PING_TTL:
201 self.irker.debug(1, "timing out inactive connection to %s at %s" % (self.servername, time.asctime()))
202 self.connection.context = None
203 self.connection.close()
204 self.connection = None
205 self.status = "disconnected"
207 # Prevent this thread from hogging the CPU by pausing
208 # for just a little bit after the queue-empty check.
209 # As long as this is less that the duration of a human
210 # reflex arc it is highly unlikely any human will ever
212 time.sleep(ANTI_BUZZ_DELAY)
213 elif self.status == "disconnected" \
214 and time.time() > self.last_xmit + DISCONNECT_TTL:
215 # Queue is nonempty, but the IRC server might be down. Letting
216 # failed connections retain queue space forever would be a
218 self.status = "expired"
220 elif self.status == "unseen" \
221 and time.time() > self.last_xmit + UNSEEN_TTL:
222 # Nasty people could attempt a denial-of-service
223 # attack by flooding us with requests with invalid
224 # servernames. We guard against this by rapidly
225 # expiring connections that have a nonempty queue but
226 # have never had a successful open.
227 self.status = "expired"
229 elif self.status == "ready":
230 (channel, message) = self.queue.get()
231 if channel not in self.channels_joined:
232 self.channels_joined.append(channel)
233 self.connection.join(channel)
234 self.irker.debug(1, "joining %s on %s." % (channel, self.servername))
235 for segment in message.split("\n"):
236 self.connection.privmsg(channel, segment)
237 time.sleep(ANTI_FLOOD_DELAY)
238 self.last_xmit = time.time()
239 self.irker.debug(1, "XMIT_TTL bump (%s transmission) at %s" % (self.servername, time.asctime()))
240 self.queue.task_done()
242 "Should this connection not be scavenged?"
243 return self.status != "expired"
244 def joined_to(self, channel):
245 "Is this connection joined to the specified channel?"
246 return channel in self.channels_joined
247 def accepting(self, channel):
248 "Can this connection accept a join of this channel?"
249 if self.channel_limits:
251 for already in self.channels_joined:
252 if already[0] == channel[0]:
254 return match_count < self.channel_limits.get(channel[0], CHANNEL_MAX)
256 return len(self.channels_joined) < CHANNEL_MAX
259 "Represent a transmission target."
260 def __init__(self, url):
261 parsed = urlparse.urlparse(url)
262 irchost, _, ircport = parsed.netloc.partition(':')
265 self.servername = irchost
266 # IRC channel names are case-insensitive. If we don't smash
267 # case here we may run into problems later. There was a bug
268 # observed on irc.rizon.net where an irkerd user specified #Channel,
269 # got kicked, and irkerd crashed because the server returned
270 # "#channel" in the notification that our kick handler saw.
271 self.channel = parsed.path.lstrip('/').lower()
272 if self.channel and self.channel[0] not in "#&+":
273 self.channel = "#" + self.channel
274 self.port = int(ircport)
276 "Both components must be present for a valid target."
277 return self.servername and self.channel
279 "Return a hashable tuple representing the destination server."
280 return (self.servername, self.port)
283 "Manage connections to a particular server-port combination."
284 def __init__(self, irkerd, servername, port):
286 self.servername = servername
288 self.connections = []
289 def dispatch(self, channel, message):
290 "Dispatch messages for our server-port combination."
291 connections = [x for x in self.connections if x.live()]
292 eligibles = [x for x in connections if x.joined_to(channel)] \
293 or [x for x in connections if x.accepting(channel)]
295 newconn = Connection(self.irker,
298 self.connections.append(newconn)
299 eligibles = [newconn]
300 eligibles[0].enqueue(channel, message)
302 "Does this server-port combination have any live connections?"
303 self.connections = [x for x in self.connections if x.live()]
304 return len(self.connections) > 0
306 "Return the time of the most recent transmission."
307 return max([x.last_xmit for x in self.connections])
310 "Persistent IRC multiplexer."
311 def __init__(self, debuglevel=0):
312 self.debuglevel = debuglevel
313 self.irc = irc.client.IRC()
314 self.irc.add_global_handler("ping", self._handle_ping)
315 self.irc.add_global_handler("welcome", self._handle_welcome)
316 self.irc.add_global_handler("erroneusnickname", self._handle_badnick)
317 self.irc.add_global_handler("nicknameinuse", self._handle_badnick)
318 self.irc.add_global_handler("nickcollision", self._handle_badnick)
319 self.irc.add_global_handler("unavailresource", self._handle_badnick)
320 self.irc.add_global_handler("featurelist", self._handle_features)
321 self.irc.add_global_handler("disconnect", self._handle_disconnect)
322 self.irc.add_global_handler("kick", self._handle_kick)
323 thread = threading.Thread(target=self.irc.process_forever)
325 self.irc._thread = thread
328 def logerr(self, errmsg):
329 "Log a processing error."
330 sys.stderr.write("irkerd: " + errmsg + "\n")
331 def debug(self, level, errmsg):
332 "Debugging information."
333 if self.debuglevel >= level:
334 sys.stderr.write("irkerd: %s\n" % errmsg)
335 def _handle_ping(self, connection, _event):
336 "PING arrived, bump the last-received time for the connection."
337 if connection.context:
338 connection.context.handle_ping()
339 def _handle_welcome(self, connection, _event):
340 "Welcome arrived, nick accepted for this connection."
341 if connection.context:
342 connection.context.handle_welcome()
343 def _handle_badnick(self, connection, _event):
344 "Nick not accepted for this connection."
345 if connection.context:
346 connection.context.handle_badnick()
347 def _handle_features(self, connection, event):
348 "Determine if and how we can set deaf mode."
349 if connection.context:
350 cxt = connection.context
351 for lump in event.arguments():
352 if lump.startswith("DEAF="):
353 connection.mode(cxt.nickname(), "+"+lump[5:])
354 elif lump.startswith("MAXCHANNELS="):
357 cxt.channel_limits[pref] = m
358 self.debug(1, "%s maxchannels is %d" \
359 % (connection.server, m))
360 elif lump.startswith("CHANLIMIT=#:"):
361 limits = lump[10:].split(",")
364 (prefixes, limit) = token.split(":")
367 cxt.channel_limits[c] = limit
368 self.debug(1, "%s channel limit map is %s" \
369 % (connection.server, cxt.channel_limits))
371 self.logerr("ill-formed CHANLIMIT property")
372 def _handle_disconnect(self, connection, _event):
373 "Server hung up the connection."
374 self.debug(1, "server %s disconnected" % connection.server)
375 if connection.context:
376 connection.context.handle_disconnect()
377 def _handle_kick(self, connection, event):
378 "Server hung up the connection."
379 self.debug(1, "irker has been kicked from %s on %s" % (event.target(), connection.server))
380 if connection.context:
381 connection.context.handle_kick(event.target())
382 def handle(self, line):
383 "Perform a JSON relay request."
385 request = json.loads(line.strip())
386 if type(request) != type({}):
387 self.logerr("request in tot a JSON dictionary: %s" % repr(request))
388 elif "to" not in request or "privmsg" not in request:
389 self.logerr("malformed reqest - 'to' or 'privmsg' missing: %s" % repr(request))
391 channels = request['to']
392 message = request['privmsg']
393 if type(channels) not in (type([]), type(u"")) \
394 or type(message) != type(u""):
395 self.logerr("malformed request - unexpected types: %s" % repr(request))
397 if type(channels) == type(u""):
398 channels = [channels]
400 if type(url) != type(u""):
401 self.logerr("malformed request - unexpected type: %s" % repr(request))
404 if not target.valid():
406 if target.server() not in self.servers:
407 self.servers[target.server()] = Dispatcher(self, target.servername, target.port)
408 self.servers[target.server()].dispatch(target.channel, message)
409 # GC dispatchers with no active connections
410 servernames = self.servers.keys()
411 for servername in servernames:
412 if not self.servers[servername].live():
413 del self.servers[servername]
414 # If we might be pushing a resource limit
415 # even after garbage collection, remove a
416 # session. The goal here is to head off
417 # DoS attacks that aim at exhausting
418 # thread space or file descriptors. The
419 # cost is that attempts to DoS this
420 # service will cause lots of join/leave
421 # spam as we scavenge old channels after
422 # connecting to new ones. The particular
423 # method used for selecting a session to
424 # be terminated doesn't matter much; we
425 # choose the one longest idle on the
426 # assumption that message activity is likely
429 oldtime = float("inf")
430 if len(self.servers) >= CONNECTION_MAX:
431 for (name, server) in self.servers.items():
432 if server.last_xmit() < oldtime:
434 oldtime = server.last_xmit()
435 del self.servers[oldest]
437 self.logerr("can't recognize JSON on input: %s" % repr(line))
439 self.logerr("wildly malformed JSON blew the parser stack.")
441 class IrkerTCPHandler(SocketServer.StreamRequestHandler):
444 line = self.rfile.readline()
447 irker.handle(line.strip())
449 class IrkerUDPHandler(SocketServer.BaseRequestHandler):
451 data = self.request[0].strip()
452 #socket = self.request[1]
455 if __name__ == '__main__':
457 (options, arguments) = getopt.getopt(sys.argv[1:], "d:V")
458 for (opt, val) in options:
459 if opt == '-d': # Enable debug/progress messages
462 logging.basicConfig(level=logging.DEBUG)
463 elif opt == '-V': # Emit version and exit
464 sys.stdout.write("irkerd version %s\n" % version)
466 irker = Irker(debuglevel=debuglvl)
467 tcpserver = SocketServer.TCPServer((HOST, PORT), IrkerTCPHandler)
468 tcpserver = threading.Thread(target=tcpserver.serve_forever)
469 tcpserver.daemon = True
471 udpserver = SocketServer.UDPServer((HOST, PORT), IrkerUDPHandler)
472 udpserver = threading.Thread(target=udpserver.serve_forever)
473 udpserver.daemon = True
478 except KeyboardInterrupt: