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),
409 info = peerinfo(me._peer)
410 if 'connect' in info:
411 S.warn('watch', 'reconnecting', me._peer)
413 T.spawn(connect, me._peer)
414 me._timer = M.SelTimer(time() + me._every, me._time)
418 def event(me, code, stuff):
420 Respond to an event which happened to this peer.
422 Timer events indicate that we should start a new ping. (The server has
423 its own timeout which detects lost packets.)
425 We trap unknown-peer responses and detach from the Pinger.
427 If the ping fails and we run out of retries, we attempt to restart the
434 S.notify('watch', 'ping-failed', me._peer, *stuff)
435 if stuff and stuff[0] == 'unknown-peer':
436 me._pinger.kill(me._peer)
438 if stuff[0] == 'ping-ok':
440 S.warn('watch', 'ping-ok', me._peer)
441 me._timer = M.SelTimer(time() + me._every, me._time)
442 elif stuff[0] == 'ping-timeout':
444 S.warn('watch', 'ping-timeout', me._peer,
445 'attempt', str(me._failures), 'of', str(me._retries))
446 if me._failures < me._retries:
450 elif stuff[0] == 'ping-peer-died':
451 me._pinger.kill(me._peer)
456 Handle timer callbacks by posting a timeout event on the queue.
459 me._q.put(((me._peer, me.seq), 'TIMER', None))
462 return 'PingPeer(%s, %d, f = %d)' % (me._peer, me.seq, me._failures)
466 class Pinger (T.Coroutine):
468 The Pinger keeps track of the peers which we expect to be connected and
469 takes action if they seem to stop responding.
471 There is usually only one Pinger, called pinger.
473 The Pinger maintains a collection of PingPeer objects, and an event queue.
474 The PingPeers direct the results of their pings, and timer events, to the
475 event queue. The Pinger's coroutine picks items off the queue and
476 dispatches them back to the PingPeers as appropriate.
480 """Initialize the Pinger."""
481 T.Coroutine.__init__(me)
487 Coroutine function: reads the pinger queue and sends events to the
488 PingPeer objects they correspond to.
491 (peer, seq), code, stuff = me._q.get()
492 if peer in me._peers and seq == me._peers[peer].seq:
493 me._peers[peer].event(code, stuff)
495 def add(me, peer, info, pingnow):
497 Add PEER to the collection of peers under the Pinger's watchful eye.
498 The arguments are as for PingPeer: see above.
500 me._peers[peer] = PingPeer(me, me._q, peer, info, pingnow)
504 """Remove PEER from the peers being watched by the Pinger."""
508 def rescan(me, startup):
510 General resynchronization method.
512 We scan the list of peers (with connect scripts) known at the server.
513 Any which are known to the Pinger but aren't known to the server are
514 removed from our list; newly arrived peers are added. (Note that a peer
515 can change state here either due to the server sneakily changing its list
516 without issuing notifications or, more likely, the database changing its
517 idea of whether a peer is interesting.) Finally, PingPeers which are
518 still present are prodded to update their timing parameters.
520 This method is called once at startup to pick up the peers already
521 installed, and again by the dbwatcher coroutine when it detects a change
525 for peer in S.list():
527 info = peerinfo(peer)
530 if boolean(info, 'watch', False):
532 for peer, obj in me._peers.items():
534 obj.update(correct[peer])
537 for peer, info in correct.iteritems():
538 if peer not in me._peers:
540 ifname = S.ifname(peer)
542 addpeer(info, peer, ifname, *addr)
544 me.add(peer, info, True)
549 Returns the list of peers being watched by the Pinger.
551 return me._peers.keys()
553 ###--------------------------------------------------------------------------
556 def encode_envvars(env, prefix, vars):
558 Encode the variables in VARS suitably for including in a program
559 environment. Lowercase letters in variable names are forced to uppercase;
560 runs of non-alphanumeric characters are replaced by single underscores; and
561 the PREFIX is prepended. The resulting variables are written to ENV.
563 for k, v in vars.iteritems():
564 env[prefix + r_bad.sub('_', k.upper())] = v
566 r_bad = RX.compile(r'[\W_]+')
569 Translate the database INFO dictionary for a peer into a dictionary of
570 environment variables with plausible upper-case names and a P_ prefix.
571 Also collect the crypto information into A_ variables.
574 encode_envvars(env, 'P_', info)
575 encode_envvars(env, 'A_', S.algs())
578 def ifupdown(what, peer, info, *args):
580 Run the interface up/down script for a peer.
582 WHAT is 'ifup' or 'ifdown'. PEER names the peer in question. INFO is the
583 database record dictionary. ARGS is a list of arguments to pass to the
584 script, in addition to the peer name.
586 The command is run and watched in the background by potwatch.
589 c = Command([what, peer], q, what,
590 M.split(info[what], quotep = True)[0] +
593 potwatch(what, peer, q)
595 def addpeer(info, peer, ifname, *addr):
597 Add a new peer to our collection.
599 INFO is the peer information dictionary, or None if we don't have one yet.
601 PEER names the peer; IFNAME is the interface name for its tunnel; and ADDR
602 is the list of tokens representing its address.
604 We try to bring up the interface and provoke a connection to the peer if
609 info = peerinfo(peer)
613 T.Coroutine(ifupdown).switch('ifup', peer, info, ifname, *addr)
614 if 'connect' in info:
615 T.Coroutine(connect).switch(peer, info['connect'])
616 if boolean(info, 'watch', False):
617 pinger.add(peer, info, False)
620 """Drop the PEER from the Pinger and put its interface to bed."""
622 info = peerinfo(peer)
630 T.Coroutine(ifupdown).switch('ifdown', peer, info)
632 def notify(_, code, *rest):
634 Watch for notifications.
636 We trap ADD and KILL notifications, and send them straight to addpeer and
637 delpeer respectively.
644 ###--------------------------------------------------------------------------
648 raise T.TripeJobError('not-implemented')
652 kick PEER: Force a new connection attempt for PEER
654 if peer not in pinger.adopted():
655 raise T.TripeJobError('peer-not-adopted', peer)
656 T.spawn(connect, peer)
660 adopted: Report a list of adopted peers.
662 for peer in pinger.adopted():
665 ###--------------------------------------------------------------------------
672 Register the notification watcher, and rescan the peers.
674 S.handler['NOTE'] = notify
676 pinger.rescan(opts.startup)
680 Initialization to be done before service startup.
682 global errorwatch, childwatch, pinger
683 errorwatch = ErrorWatch()
684 childwatch = ChildWatch()
686 T.Coroutine(dbwatch).switch()
692 Parse the command-line options.
694 Automatically changes directory to the requested configdir, and turns on
695 debugging. Returns the options object.
697 op = OptionParser(usage = '%prog [-a FILE] [-d DIR]',
698 version = '%%prog %s' % VERSION)
700 op.add_option('-a', '--admin-socket',
701 metavar = 'FILE', dest = 'tripesock', default = T.tripesock,
702 help = 'Select socket to connect to [default %default]')
703 op.add_option('-d', '--directory',
704 metavar = 'DIR', dest = 'dir', default = T.configdir,
705 help = 'Select current diretory [default %default]')
706 op.add_option('-p', '--peerdb',
707 metavar = 'FILE', dest = 'cdb', default = T.peerdb,
708 help = 'Select peers database [default %default]')
709 op.add_option('--daemon', dest = 'daemon',
710 default = False, action = 'store_true',
711 help = 'Become a daemon after successful initialization')
712 op.add_option('--debug', dest = 'debug',
713 default = False, action = 'store_true',
714 help = 'Emit debugging trace information')
715 op.add_option('--startup', dest = 'startup',
716 default = False, action = 'store_true',
717 help = 'Being called as part of the server startup')
719 opts, args = op.parse_args()
720 if args: op.error('no arguments permitted')
722 T._debug = opts.debug
725 ## Service table, for running manually.
726 service_info = [('watch', T.VERSION, {
727 'adopted': (0, 0, '', cmd_adopted),
728 'kick': (1, 1, 'PEER', cmd_kick)
731 if __name__ == '__main__':
732 opts = parse_options()
733 T.runservices(opts.tripesock, service_info,
734 init = init, setup = setup,
735 daemon = opts.daemon)
737 ###----- That's all, folks --------------------------------------------------