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