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 = 0.125 # Anti-flood delay after transmissions, seconds
37 ANTI_BUZZ_DELAY = 0.09 # Anti-buzz delay after queue-empty check
38 CONNECTION_MAX = 200 # Avoid pushing per-process thread or fd limits
40 # No user-serviceable parts below this line
42 # This black magic imports support for green threads (coroutines),
43 # then has kinky sex with the threading library internals.
44 # Threads then become ultra-light-weight and cooperatively
47 import eventlet; eventlet.monkey_patch()
52 import sys, json, getopt, urlparse, time, random
53 import threading, Queue, SocketServer
54 import irc.client, logging
58 # Sketch of implementation:
60 # One Irker object manages multiple IRC sessions. It holds a map of
61 # Dispatcher objects, one per (server, port) combination, which are
62 # responsible for routing messages to one of any number of Connection
63 # objects that do the actual socket conversations. The reason for the
64 # Dispatcher layer is that IRC daemons limit the number of channels a
65 # client (that is, from the daemon's point of view, a socket) can be
66 # joined to, so each session to a server needs a flock of Connection
67 # instances each with its own socket.
69 # Connections are timed out and removed when either they haven't seen a
70 # PING for a while (indicating that the server may be stalled or down)
71 # or there has been no message traffic to them for a while, or
72 # even if the queue is nonempty but efforts to connect have failed for
75 # There are multiple threads. One accepts incoming traffic from all servers.
76 # Each Connection also has a consumer thread and a thread-safe message queue.
77 # The program main appends messages to queues as JSON requests are received;
78 # the consumer threads try to ship them to servers. When a socket write
79 # stalls, it only blocks an individual consumer thread; if it stalls long
80 # enough, the session will be timed out.
82 # Message delivery is thus not reliable in the face of network stalls,
83 # but this was considered acceptable because IRC (notoriously) has the
84 # same problem - there is little point in reliable delivery to a relay
85 # that is down or unreliable.
87 # This code uses only NICK, JOIN, MODE, and PRIVMSG. It is strictly
88 # compliant to RFC1459, except for the interpretation and use of the
89 # DEAF and CHANLIMIT and (obsolete) MAXCHANNELS features. CHANLIMIT
90 # is as described in the Internet RFC draft
91 # draft-brocklesby-irc-isupport-03 at <http://www.mirc.com/isupport.html>.
94 def __init__(self, irkerd, servername, port, nick_base=1):
96 self.servername = servername
98 self.nick_trial = nick_base
99 self.connection = None
100 self.status = "unseen"
101 self.last_xmit = time.time()
102 self.last_ping = time.time()
103 self.channels_joined = []
104 self.channel_limits = {}
105 # The consumer thread
106 self.queue = Queue.Queue()
107 self.thread = threading.Thread(target=self.dequeue)
109 def nickname(self, n=None):
110 "Return a name for the nth server connection."
113 return (NAMESTYLE % n)
114 def handle_ping(self):
115 "Register the fact that the server has pinged this connection."
116 self.last_ping = time.time()
117 def handle_welcome(self):
118 "The server says we're OK, with a non-conflicting nick."
119 self.status = "ready"
120 self.irker.debug(1, "nick %s accepted" % self.nickname())
121 def handle_badnick(self):
122 "The server says our nick has a conflict."
123 self.irker.debug(1, "nick %s rejected" % self.nickname())
124 # Randomness prevents a malicious user or bot from antcipating the
125 # next trial name in order to block us from completing the handshake.
126 self.nick_trial += random.randint(1, 3)
127 self.connection.nick(self.nickname())
128 def enqueue(self, channel, message):
129 "Enque a message for transmission."
130 self.queue.put((channel, message))
132 "Try to ship pending messages from the queue."
134 # We want to be kind to the IRC servers and not hold unused
135 # sockets open forever, so they have a time-to-live. The
136 # loop is coded this particular way so that we can drop
137 # the actual server connection when its time-to-live
138 # expires, then reconnect and resume transmission if the
139 # queue fills up again.
140 if not self.connection:
141 self.connection = self.irker.irc.server()
142 self.connection.context = self
144 self.channels_joined = []
145 # This will throw irc.client.ServerConnectionError on failure
147 self.connection.connect(self.servername,
149 nickname=self.nickname(),
151 ircname="irker relaying client")
152 self.status = "handshaking"
153 self.irker.debug(1, "XMIT_TTL bump (%s connection) at %s" % (self.servername, time.asctime()))
154 self.last_xmit = time.time()
155 except irc.client.ServerConnectionError:
156 self.status = "disconnected"
157 elif self.status == "handshaking":
158 # Don't buzz on the empty-queue test while we're handshaking
159 time.sleep(ANTI_BUZZ_DELAY)
160 elif self.queue.empty():
161 # Queue is empty, at some point we want to time out
162 # the connection rather than holding a socket open in
163 # the server forever.
165 if now > self.last_xmit + XMIT_TTL \
166 or now > self.last_ping + PING_TTL:
167 self.irker.debug(1, "timing out inactive connection to %s at %s" % (self.servername, time.asctime()))
168 self.connection.context = None
169 self.connection.close()
170 self.connection = None
171 self.status = "disconnected"
173 # Prevent this thread from hogging the CPU by pausing
174 # for just a little bit after the queue-empty check.
175 # As long as this is less that the duration of a human
176 # reflex arc it is highly unlikely any human will ever
178 time.sleep(ANTI_BUZZ_DELAY)
179 elif self.status == "disconnected" \
180 and time.time() > self.last_xmit + DISCONNECT_TTL:
181 # Queue is nonempty, but the IRC server might be down. Letting
182 # failed connections retain queue space forever would be a
184 self.status = "expired"
186 elif self.status == "unseen" \
187 and time.time() > self.last_xmit + UNSEEN_TTL:
188 # Nasty people could attempt a denial-of-service
189 # attack by flooding us with requests with invalid
190 # servernames. We guard against this by rapidly
191 # expiring connections that have a nonempty queue but
192 # have never had a successful open.
193 self.status = "expired"
195 elif self.status == "ready":
196 (channel, message) = self.queue.get()
197 if channel not in self.channels_joined:
198 self.channels_joined.append(channel)
199 if channel[0] not in "#&+":
200 channel = "#" + channel
201 self.connection.join(channel)
202 for segment in message.split("\n"):
203 self.connection.privmsg(channel, segment)
204 self.last_xmit = time.time()
205 self.irker.debug(1, "XMIT_TTL bump (%s transmission) at %s" % (self.servername, time.asctime()))
206 self.queue.task_done()
207 time.sleep(ANTI_FLOOD_DELAY)
209 "Should this connection not be scavenged?"
210 return self.status != "expired"
211 def joined_to(self, channel):
212 "Is this connection joined to the specified channel?"
213 return channel in self.channels_joined
214 def accepting(self, channel):
215 "Can this connection accept a join of this channel?"
216 if self.channel_limits:
218 for already in self.channels_joined:
219 if already[0] == channel[0]:
221 return match_count < self.channel_limits.get(channel[0], CHANNEL_MAX)
223 return len(self.channels_joined) < CHANNEL_MAX
226 "Represent a transmission target."
227 def __init__(self, url):
228 parsed = urlparse.urlparse(url)
229 irchost, _, ircport = parsed.netloc.partition(':')
232 self.servername = irchost
233 self.channel = parsed.path.lstrip('/')
234 self.port = int(ircport)
236 "Return a hashable tuple representing the destination server."
237 return (self.servername, self.port)
240 "Manage connections to a particular server-port combination."
241 def __init__(self, irkerd, servername, port):
243 self.servername = servername
245 self.connections = []
246 def dispatch(self, channel, message):
247 "Dispatch messages for our server-port combination."
248 connections = [x for x in self.connections if x.live()]
249 eligibles = [x for x in connections if x.joined_to(channel)] \
250 or [x for x in connections if x.accepting(channel)]
252 newconn = Connection(self.irker,
255 len(self.connections)+1)
256 self.connections.append(newconn)
257 eligibles = [newconn]
258 eligibles[0].enqueue(channel, message)
260 "Does this server-port combination have any live connections?"
261 self.connections = [x for x in self.connections if x.live()]
262 return len(self.connections) > 0
265 "Persistent IRC multiplexer."
266 def __init__(self, debuglevel=0):
267 self.debuglevel = debuglevel
268 self.irc = irc.client.IRC()
269 self.irc.add_global_handler("ping", self._handle_ping)
270 self.irc.add_global_handler("welcome", self._handle_welcome)
271 self.irc.add_global_handler("erroneusnickname", self._handle_badnick)
272 self.irc.add_global_handler("nicknameinuse", self._handle_badnick)
273 self.irc.add_global_handler("nickcollision", self._handle_badnick)
274 self.irc.add_global_handler("unavailresource", self._handle_badnick)
275 self.irc.add_global_handler("featurelist", self._handle_features)
276 thread = threading.Thread(target=self.irc.process_forever)
277 self.irc._thread = thread
280 def logerr(self, errmsg):
281 "Log a processing error."
282 sys.stderr.write("irkerd: " + errmsg + "\n")
283 def debug(self, level, errmsg):
284 "Debugging information."
285 if self.debuglevel >= level:
286 sys.stderr.write("irkerd: %s\n" % errmsg)
287 def _handle_ping(self, connection, _event):
288 "PING arrived, bump the last-received time for the connection."
289 if connection.context:
290 connection.context.handle_ping()
291 def _handle_welcome(self, connection, _event):
292 "Welcome arrived, nick accepted for this connection."
293 if connection.context:
294 connection.context.handle_welcome()
295 def _handle_badnick(self, connection, _event):
296 "Nick not accepted for this connection."
297 if connection.context:
298 connection.context.handle_badnick()
299 def _handle_features(self, connection, event):
300 "Determine if and how we can set deaf mode."
301 if connection.context:
302 cxt = connection.context
303 for lump in event.arguments():
304 if lump.startswith("DEAF="):
305 connection.mode(cxt.nickname(), "+"+lump[5:])
306 elif lump.startswith("MAXCHANNELS="):
309 cxt.channel_limits[pref] = m
310 self.debug(1, "%s maxchannels is %d" \
311 % (connection.server, m))
312 elif lump.startswith("CHANLIMIT=#:"):
313 limits = lump[10:].split(",")
316 (prefixes, limit) = token.split(":")
319 cxt.channel_limits[c] = limit
320 self.debug(1, "%s channel limit map is %s" \
321 % (connection.server, cxt.channel_limits))
323 self.logerr("ill-formed CHANLIMIT property")
324 def handle(self, line):
325 "Perform a JSON relay request."
327 request = json.loads(line.strip())
328 if type(request) != type({}):
329 self.logerr("request in tot a JSON dictionary: %s" % repr(request))
330 elif "to" not in request or "privmsg" not in request:
331 self.logerr("malformed reqest - 'to' or 'privmsg' missing: %s" % repr(request))
333 channels = request['to']
334 message = request['privmsg']
335 if type(channels) not in (type([]), type(u"")) \
336 or type(message) != type(u""):
337 self.logerr("malformed request - unexpected types: %s" % repr(request))
339 if type(channels) == type(u""):
340 channels = [channels]
342 if type(url) != type(u""):
343 self.logerr("malformed request - unexpected type: %s" % repr(request))
346 if target.server() not in self.servers:
347 self.servers[target.server()] = Dispatcher(self, target.servername, target.port)
348 self.servers[target.server()].dispatch(target.channel, message)
349 # GC dispatchers with no active connections
350 servernames = self.servers.keys()
351 for servername in servernames:
352 if not self.servers[servername].live():
353 del self.servers[servername]
354 # If we might be pushing a resource limit
355 # even after garbage collection, remove a
356 # session. The goal here is to head off
357 # DoS attacks that aim at exhausting
358 # thread space or file descriptors. The
359 # cost is that attempts to DoS this
360 # service will cause lots of join/leave
361 # spam as we scavenge old channels after
362 # connecting to new ones. The particular
363 # method used for selecting a session to
364 # be terminated doesn't matter much; we
365 # choose the one longest idle on the
366 # assumption that message activity is likely
369 if len(self.servers) >= CONNECTION_MAX:
370 for (name, server) in self.servers.items():
371 if not oldest or server.last_xmit < self.servers[oldest].last_xmit:
373 del self.servers[oldest]
375 self.logerr("can't recognize JSON on input: %s" % repr(line))
377 class IrkerTCPHandler(SocketServer.StreamRequestHandler):
380 line = self.rfile.readline()
383 irker.handle(line.strip())
385 class IrkerUDPHandler(SocketServer.BaseRequestHandler):
387 data = self.request[0].strip()
388 #socket = self.request[1]
391 if __name__ == '__main__':
393 (options, arguments) = getopt.getopt(sys.argv[1:], "d:V")
394 for (opt, val) in options:
395 if opt == '-d': # Enable debug/progress messages
398 logging.basicConfig(level=logging.DEBUG)
399 elif opt == '-V': # Emit version and exit
400 sys.stdout.write("irkerd version %s\n" % version)
402 irker = Irker(debuglevel=debuglvl)
403 tcpserver = SocketServer.TCPServer((HOST, PORT), IrkerTCPHandler)
404 udpserver = SocketServer.UDPServer((HOST, PORT), IrkerUDPHandler)
405 threading.Thread(target=tcpserver.serve_forever).start()
406 threading.Thread(target=udpserver.serve_forever).start()
407 # Main thread has to stay alive forever for the cooperative
408 # scheduling of the green threads to work.