4 ### Watch arrival and departure of peers
6 ### (c) 2007 Straylight/Edgeware
9 ###----- Licensing notice ---------------------------------------------------
11 ### This file is part of Trivial IP Encryption (TrIPE).
13 ### TrIPE is free software; you can redistribute it and/or modify
14 ### it under the terms of the GNU General Public License as published by
15 ### the Free Software Foundation; either version 2 of the License, or
16 ### (at your option) any later version.
18 ### TrIPE is distributed in the hope that it will be useful,
19 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
20 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 ### GNU General Public License for more details.
23 ### You should have received a copy of the GNU General Public License
24 ### along with TrIPE; if not, write to the Free Software Foundation,
25 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 ###--------------------------------------------------------------------------
30 ### External dependencies.
32 from optparse import OptionParser
41 import subprocess as PROC
45 ###--------------------------------------------------------------------------
46 ### Running auxiliary commands.
48 class SelLineQueue (M.SelLineBuffer):
49 """Glues the select-line-buffer into the coroutine queue system."""
51 def __new__(cls, file, queue, tag, kind):
52 """See __init__ for documentation."""
53 return M.SelLineBuffer.__new__(cls, file.fileno())
55 def __init__(me, file, queue, tag, kind):
57 Initialize a new line-reading adaptor.
59 The adaptor reads lines from FILE. Each line is inserted as a message of
60 the stated KIND, bearing the TAG, into the QUEUE. End-of-file is
71 me._q.put((me._tag, me._kind, line))
76 me._q.put((me._tag, me._kind, None))
78 class ErrorWatch (T.Coroutine):
80 An object which watches stderr streams for errors and converts them into
83 WARN watch INFO stderr LINE
85 The INFO is a list of tokens associated with the file when it was
88 Usually there is a single ErrorWatch object, called errorwatch.
92 """Initialization: there are no arguments."""
93 T.Coroutine.__init__(me)
98 def watch(me, file, info):
100 Adds FILE to the collection of files to watch.
102 INFO will be written in the warning messages from this FILE. Returns a
103 sequence number which can be used to unregister the file again.
107 me._map[seq] = info, SelLineQueue(file, me._q, seq, 'stderr')
110 def unwatch(me, seq):
111 """Stop watching the file with sequence number SEQ."""
117 Coroutine function: read items from the queue and report them.
119 Unregisters files automatically when they reach EOF.
122 seq, _, line = me._q.get()
126 S.warn(*['watch'] + me._map[seq][0] + ['stderr', line])
130 Coroutine function: wake up every second and notice changes to the
131 database. When a change happens, tell the Pinger (q.v.) to rescan its
134 cr = T.Coroutine.getcurrent()
136 fw = M.FWatch(opts.cdb)
138 timer = M.SelTimer(time() + 1, lambda: cr.switch())
142 S.notify('watch', 'peerdb-update')
144 class ChildWatch (M.SelSignal):
146 An object which watches for specified processes exiting and reports
147 terminations by writing items of the form (TAG, 'exit', RESULT) to a queue.
149 There is usually only one ChildWatch object, called childwatch.
153 """Initialize the child-watcher."""
154 return M.SelSignal.__new__(cls, SIG.SIGCHLD)
157 """Initialize the child-watcher."""
161 def watch(me, pid, queue, tag):
163 Register PID as a child to watch. If it exits, write (TAG, 'exit', CODE)
164 to the QUEUE, where CODE is one of
166 * None (successful termination)
167 * ['exit-nonzero', CODE] (CODE is a string!)
168 * ['exit-signal', 'S' + CODE] (CODE is the signal number as a string)
169 * ['exit-unknown', STATUS] (STATUS is the entire exit status, in hex)
171 me._pid[pid] = queue, tag
174 def unwatch(me, pid):
175 """Unregister PID as a child to watch."""
182 Called when child processes exit: collect exit statuses and report
187 pid, status = OS.waitpid(-1, OS.WNOHANG)
189 if exc.errno == E.ECHILD:
193 if pid not in me._pid:
195 queue, tag = me._pid[pid]
196 if OS.WIFEXITED(status):
197 exit = OS.WEXITSTATUS(status)
201 code = ['exit-nonzero', str(exit)]
202 elif OS.WIFSIGNALED(status):
203 code = ['exit-signal', 'S' + str(OS.WTERMSIG(status))]
205 code = ['exit-unknown', hex(status)]
206 queue.put((tag, 'exit', code))
208 class Command (object):
210 Represents a running command.
212 This class is the main interface to the machery provided by the ChildWatch
213 and ErrorWatch objects. See also potwatch.
216 def __init__(me, info, queue, tag, args, env):
218 Start a new child process.
220 The ARGS are a list of arguments to be given to the child process. The
221 ENV is either None or a dictionary of environment variable assignments to
222 override the extant environment. INFO is a list of tokens to be included
223 in warnings about the child's stderr output. If the child writes a line
224 to standard output, put (TAG, 'stdout', LINE) to the QUEUE. When the
225 child exits, write (TAG, 'exit', CODE) to the QUEUE.
230 myenv = OS.environ.copy()
231 if env: myenv.update(env)
232 me._proc = PROC.Popen(args = args, env = myenv, bufsize = 1,
233 stdout = PROC.PIPE, stderr = PROC.PIPE)
234 me._lq = SelLineQueue(me._proc.stdout, queue, tag, 'stdout')
235 errorwatch.watch(me._proc.stderr, info)
236 childwatch.watch(me._proc.pid, queue, tag)
240 If I've been forgotten then stop watching for termination.
242 childwatch.unwatch(me._proc.pid)
244 def potwatch(what, name, q):
246 Watch the queue Q for activity as reported by a Command object.
248 Information from the process's stdout is reported as
250 NOTE WHAT NAME stdout LINE
252 abnormal termination is reported as
256 where CODE is what the ChildWatch wrote.
259 while not deadp or not eofp:
260 _, kind, more = q.get()
265 S.notify('watch', what, name, 'stdout', more)
267 if more: S.warn('watch', what, name, *more)
270 ###--------------------------------------------------------------------------
271 ### Peer database utilities.
273 def timespec(info, key, default):
274 """Parse INFO[KEY] as a timespec, or return DEFAULT."""
276 return T.timespec(info[key])
277 except (KeyError, T.TripeJobError):
280 def integer(info, key, default):
281 """Parse INFO[KEY] as an integer, or return DEFAULT."""
283 return int(info[key])
284 except (KeyError, ValueError):
287 def boolean(info, key, default):
288 """Parse INFO[KEY] as a boolean, or return DEFAULT."""
290 return info[key] in ['t', 'true', 'y', 'yes', 'on']
291 except (KeyError, ValueError):
296 Return a dictionary containing information about PEER from the database.
298 return dict(M.URLDecode(CDB.init(opts.cdb)['P' + peer], semip = True))
300 ###--------------------------------------------------------------------------
301 ### Waking up and watching peers.
303 def connect(peer, conn = None):
305 Start the job of connecting to the passive PEER.
307 The CONN string is a shell command which will connect to the peer (via some
308 back-channel, say ssh and userv), issue a command
310 SVCSUBMIT connect passive [OPTIONS] USER
312 and write the resulting challenge to standard error.
316 conn = peerinfo(peer)['connect']
320 cmd = Command(['connect', peer], q, 'connect',
321 ['/bin/sh', '-c', conn], None)
322 _, kind, more = q.peek()
325 S.warn('watch', 'connect', peer, 'unexpected-eof')
330 potwatch('connect', peer, q)
333 class PingPeer (object):
335 Object representing a peer which we are pinging to ensure that it is still
338 PingPeer objects are held by the Pinger (q.v.). The Pinger maintains an
339 event queue -- which saves us from having an enormous swarm of coroutines
340 -- but most of the actual work is done here.
342 In order to avoid confusion between different PingPeer instances for the
343 same actual peer, each PingPeer has a sequence number (its `seq'
344 attribute). Events for the PingPeer are identified by a (PEER, SEQ) pair.
345 (Using the PingPeer instance itself will prevent garbage collection of
346 otherwise defunct instances.)
349 def __init__(me, pinger, queue, peer, info, pingnow):
351 Create a new PingPeer.
353 The PINGER is the Pinger object we should send the results to. This is
354 used when we remove ourselves, if the peer has been explicitly removed.
356 The QUEUE is the event queue on which timer and ping-command events
359 The PEER is just the peer's name, as a string.
361 The INFO is the database record for the peer, as a dictionary, or None if
362 it's not readily available. (This is just a tweak to save multiple
363 probes if we don't really need them.)
365 If PINGNOW is true, then immediately start pinging the peer. Otherwise
366 wait until the usual retry interval.
380 me._timer = M.SelTimer(time() + me._every, me._time)
382 def update(me, info):
384 Refreshes the timer parameters for this peer. We don't, however,
385 immediately reschedule anything: that will happen next time anything
389 info = peerinfo(me._peer)
390 me._every = timespec(info, 'every', 120)
391 me._timeout = timespec(info, 'timeout', 10)
392 me._retries = integer(info, 'retries', 5)
393 me._connectp = 'connect' in info
398 Send a ping to the peer; the result is sent to the Pinger's event queue.
400 S.rawcommand(T.TripeAsynchronousCommand(
401 me._q, (me._peer, me.seq),
403 '-background', S.bgtag(),
404 '-timeout', str(me._timeout),
408 def event(me, code, stuff):
410 Respond to an event which happened to this peer.
412 Timer events indicate that we should start a new ping. (The server has
413 its own timeout which detects lost packets.)
415 We trap unknown-peer responses and detach from the Pinger.
417 If the ping fails and we run out of retries, we attempt to restart the
424 S.notify('watch', 'ping-failed', me._peer, *stuff)
425 if stuff and stuff[0] == 'unknown-peer':
426 me._pinger.kill(me._peer)
428 if stuff[0] == 'ping-ok':
430 S.warn('watch', 'ping-ok', me._peer)
431 me._timer = M.SelTimer(time() + me._every, me._time)
432 elif stuff[0] == 'ping-timeout':
434 S.warn('watch', 'ping-timeout', me._peer,
435 'attempt', str(me._failures), 'of', str(me._retries))
436 if me._failures < me._retries:
439 info = peerinfo(me._peer)
440 if 'connect' in info:
441 S.warn('watch', 'reconnecting', me._peer)
443 T.spawn(T.Coroutine(connect), me._peer)
444 me._timer = M.SelTimer(time() + me._every, me._time)
447 elif stuff[0] == 'ping-peer-died':
448 me._pinger.kill(me._peer)
453 Handle timer callbacks by posting a timeout event on the queue.
456 me._q.put(((me._peer, me.seq), 'TIMER', None))
459 return 'PingPeer(%s, %d, f = %d)' % (me._peer, me.seq, me._failures)
463 class Pinger (T.Coroutine):
465 The Pinger keeps track of the peers which we expect to be connected and
466 takes action if they seem to stop responding.
468 There is usually only one Pinger, called pinger.
470 The Pinger maintains a collection of PingPeer objects, and an event queue.
471 The PingPeers direct the results of their pings, and timer events, to the
472 event queue. The Pinger's coroutine picks items off the queue and
473 dispatches them back to the PingPeers as appropriate.
477 """Initialize the Pinger."""
478 T.Coroutine.__init__(me)
484 Coroutine function: reads the pinger queue and sends events to the
485 PingPeer objects they correspond to.
488 (peer, seq), code, stuff = me._q.get()
489 if peer in me._peers and seq == me._peers[peer].seq:
490 me._peers[peer].event(code, stuff)
492 def add(me, peer, info, pingnow):
494 Add PEER to the collection of peers under the Pinger's watchful eye.
495 The arguments are as for PingPeer: see above.
497 me._peers[peer] = PingPeer(me, me._q, peer, info, pingnow)
501 """Remove PEER from the peers being watched by the Pinger."""
505 def rescan(me, startup):
507 General resynchronization method.
509 We scan the list of peers (with connect scripts) known at the server.
510 Any which are known to the Pinger but aren't known to the server are
511 removed from our list; newly arrived peers are added. (Note that a peer
512 can change state here either due to the server sneakily changing its list
513 without issuing notifications or, more likely, the database changing its
514 idea of whether a peer is interesting.) Finally, PingPeers which are
515 still present are prodded to update their timing parameters.
517 This method is called once at startup to pick up the peers already
518 installed, and again by the dbwatcher coroutine when it detects a change
522 for peer in S.list():
524 info = peerinfo(peer)
527 if boolean(info, 'watch', False):
529 for peer, obj in me._peers.items():
531 obj.update(correct[peer])
534 for peer, info in correct.iteritems():
535 if peer not in me._peers:
537 ifname = S.ifname(peer)
539 addpeer(info, peer, ifname, *addr)
541 me.add(peer, info, True)
546 Returns the list of peers being watched by the Pinger.
548 return me._peers.keys()
550 ###--------------------------------------------------------------------------
553 def encode_envvars(env, prefix, vars):
555 Encode the variables in VARS suitably for including in a program
556 environment. Lowercase letters in variable names are forced to uppercase;
557 runs of non-alphanumeric characters are replaced by single underscores; and
558 the PREFIX is prepended. The resulting variables are written to ENV.
560 for k, v in vars.iteritems():
561 env[prefix + r_bad.sub('_', k.upper())] = v
563 r_bad = RX.compile(r'[\W_]+')
566 Translate the database INFO dictionary for a peer into a dictionary of
567 environment variables with plausible upper-case names and a P_ prefix.
568 Also collect the crypto information into A_ variables.
571 encode_envvars(env, 'P_', info)
572 encode_envvars(env, 'A_', S.algs())
575 def ifupdown(what, peer, info, *args):
577 Run the interface up/down script for a peer.
579 WHAT is 'ifup' or 'ifdown'. PEER names the peer in question. INFO is the
580 database record dictionary. ARGS is a list of arguments to pass to the
581 script, in addition to the peer name.
583 The command is run and watched in the background by potwatch.
586 c = Command([what, peer], q, what,
587 M.split(info[what], quotep = True)[0] +
590 potwatch(what, peer, q)
592 def addpeer(info, peer, ifname, *addr):
594 Add a new peer to our collection.
596 INFO is the peer information dictionary, or None if we don't have one yet.
598 PEER names the peer; IFNAME is the interface name for its tunnel; and ADDR
599 is the list of tokens representing its address.
601 We try to bring up the interface and provoke a connection to the peer if
606 info = peerinfo(peer)
610 T.Coroutine(ifupdown).switch('ifup', peer, info, ifname, *addr)
611 if 'connect' in info:
612 T.Coroutine(connect).switch(peer, info['connect'])
613 if boolean(info, 'watch', False):
614 pinger.add(peer, info, False)
617 """Drop the PEER from the Pinger and put its interface to bed."""
619 info = peerinfo(peer)
627 T.Coroutine(ifupdown).switch('ifdown', peer, info)
629 def notify(_, code, *rest):
631 Watch for notifications.
633 We trap ADD and KILL notifications, and send them straight to addpeer and
634 delpeer respectively.
641 ###--------------------------------------------------------------------------
645 raise T.TripeJobError('not-implemented')
649 kick PEER: Force a new connection attempt for PEER
651 if peer not in pinger.adopted():
652 raise T.TripeJobError('peer-not-adopted', peer)
653 T.spawn(T.Coroutine(connect), peer)
657 adopted: Report a list of adopted peers.
659 for peer in pinger.adopted():
662 ###--------------------------------------------------------------------------
669 Register the notification watcher, and rescan the peers.
671 S.handler['NOTE'] = notify
673 pinger.rescan(opts.startup)
677 Initialization to be done before service startup.
679 global errorwatch, childwatch, pinger
680 errorwatch = ErrorWatch()
681 childwatch = ChildWatch()
683 T.Coroutine(dbwatch).switch()
689 Parse the command-line options.
691 Automatically changes directory to the requested configdir, and turns on
692 debugging. Returns the options object.
694 op = OptionParser(usage = '%prog [-a FILE] [-d DIR]',
695 version = '%%prog %s' % VERSION)
697 op.add_option('-a', '--admin-socket',
698 metavar = 'FILE', dest = 'tripesock', default = T.tripesock,
699 help = 'Select socket to connect to [default %default]')
700 op.add_option('-d', '--directory',
701 metavar = 'DIR', dest = 'dir', default = T.configdir,
702 help = 'Select current diretory [default %default]')
703 op.add_option('-p', '--peerdb',
704 metavar = 'FILE', dest = 'cdb', default = T.peerdb,
705 help = 'Select peers database [default %default]')
706 op.add_option('--daemon', dest = 'daemon',
707 default = False, action = 'store_true',
708 help = 'Become a daemon after successful initialization')
709 op.add_option('--debug', dest = 'debug',
710 default = False, action = 'store_true',
711 help = 'Emit debugging trace information')
712 op.add_option('--startup', dest = 'startup',
713 default = False, action = 'store_true',
714 help = 'Being called as part of the server startup')
716 opts, args = op.parse_args()
717 if args: op.error('no arguments permitted')
719 T._debug = opts.debug
722 ## Service table, for running manually.
723 service_info = [('watch', T.VERSION, {
724 'adopted': (0, 0, '', cmd_adopted),
725 'kick': (1, 1, 'PEER', cmd_kick)
728 if __name__ == '__main__':
729 opts = parse_options()
730 T.runservices(opts.tripesock, service_info,
731 init = init, setup = setup,
732 daemon = opts.daemon)
734 ###----- That's all, folks --------------------------------------------------