mdw@git.distorted.org.uk Git - hippotat/blob - hippotatlib/__init__.py

   1 # -*- python -*-
   2 #
   3 # Hippotat - Asinine IP Over HTTP program
   4 # hippotatlib/__init__.py - common library code
   5 #
   6 # Copyright 2017 Ian Jackson
   7 #
   8 # GPLv3+
   9 #
  10 #    This program is free software: you can redistribute it and/or modify
  11 #    it under the terms of the GNU General Public License as published by
  12 #    the Free Software Foundation, either version 3 of the License, or
  13 #    (at your option) any later version.
  14 #
  15 #    This program is distributed in the hope that it will be useful,
  16 #    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 #    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 #    GNU General Public License for more details.
  19 #
  20 #    You should have received a copy of the GNU General Public License
  21 #    along with this program, in the file GPLv3.  If not,
  22 #    see <http://www.gnu.org/licenses/>.
  23
  24
  25 import signal
  26 signal.signal(signal.SIGINT, signal.SIG_DFL)
  27
  28 import sys
  29 import os
  30
  31 from zope.interface import implementer
  32
  33 import twisted
  34 from twisted.internet import reactor
  35 import twisted.internet.endpoints
  36 import twisted.logger
  37 from twisted.logger import LogLevel
  38 import twisted.python.constants
  39 from twisted.python.constants import NamedConstant
  40
  41 import ipaddress
  42 from ipaddress import AddressValueError
  43
  44 from optparse import OptionParser
  45 import configparser
  46 from configparser import ConfigParser
  47 from configparser import NoOptionError
  48
  49 from functools import partial
  50
  51 import collections
  52 import time
  53 import codecs
  54 import traceback
  55
  56 import re as regexp
  57
  58 import hippotatlib.slip as slip
  59
  60 class DBG(twisted.python.constants.Names):
  61   INIT = NamedConstant()
  62   CONFIG = NamedConstant()
  63   ROUTE = NamedConstant()
  64   DROP = NamedConstant()
  65   OWNSOURCE = NamedConstant()
  66   FLOW = NamedConstant()
  67   HTTP = NamedConstant()
  68   TWISTED = NamedConstant()
  69   QUEUE = NamedConstant()
  70   HTTP_CTRL = NamedConstant()
  71   QUEUE_CTRL = NamedConstant()
  72   HTTP_FULL = NamedConstant()
  73   CTRL_DUMP = NamedConstant()
  74   SLIP_FULL = NamedConstant()
  75   DATA_COMPLETE = NamedConstant()
  76
  77 _hex_codec = codecs.getencoder('hex_codec')
  78
  79 #---------- logging ----------
  80
  81 org_stderr = sys.stderr
  82
  83 log = twisted.logger.Logger()
  84
  85 debug_set = set()
  86 debug_def_detail = DBG.HTTP
  87
  88 def log_debug(dflag, msg, idof=None, d=None):
  89   if dflag not in debug_set: return
  90   #print('---------------->',repr((dflag, msg, idof, d)), file=sys.stderr)
  91   if idof is not None:
  92     msg = '[%#x] %s' % (id(idof), msg)
  93   if d is not None:
  94     trunc = ''
  95     if not DBG.DATA_COMPLETE in debug_set:
  96       if len(d) > 64:
  97         d = d[0:64]
  98         trunc = '...'
  99     d = _hex_codec(d)[0].decode('ascii')
 100     msg += ' ' + d + trunc
 101   log.info('{dflag} {msgcore}', dflag=dflag, msgcore=msg)
 102
 103 def logevent_is_boringtwisted(event):
 104   try:
 105     if event.get('log_level') != LogLevel.info:
 106       return False
 107     dflag = event.get('dflag')
 108     if dflag is False                            : return False
 109     if dflag                         in debug_set: return False
 110     if dflag is None and DBG.TWISTED in debug_set: return False
 111     return True
 112   except Exception:
 113     print('EXCEPTION (IN BORINGTWISTED CHECK)',
 114           traceback.format_exc(), file=org_stderr)
 115     return False
 116
 117 @implementer(twisted.logger.ILogFilterPredicate)
 118 class LogNotBoringTwisted:
 119   def __call__(self, event):
 120     return (
 121       twisted.logger.PredicateResult.no
 122       if logevent_is_boringtwisted(event) else
 123       twisted.logger.PredicateResult.yes
 124     )
 125
 126 #---------- default config ----------
 127
 128 defcfg = '''
 129 [COMMON]
 130 max_batch_down = 65536
 131 max_queue_time = 10
 132 target_requests_outstanding = 3
 133 http_timeout = 30
 134 http_timeout_grace = 5
 135 max_requests_outstanding = 6
 136 max_batch_up = 4000
 137 http_retry = 5
 138 port = 80
 139 vroutes = ''
 140 ifname_client = hippo%%d
 141 ifname_server = shippo%%d
 142
 143 #[server] or [<client>] overrides
 144 ipif = userv root ipif %(local)s,%(peer)s,%(mtu)s,slip,%(ifname)s %(rnets)s
 145
 146 # relating to virtual network
 147 mtu = 1500
 148
 149 # addrs = 127.0.0.1 ::1
 150 # url
 151
 152 # relating to virtual network
 153 vvnetwork = 172.24.230.192
 154 # vnetwork = <prefix>/<len>
 155 # vaddr    = <ipaddr>
 156 # vrelay   = <ipaddr>
 157
 158
 159 # [<client-ip4-or-ipv6-address>]
 160 # password = <password>    # used by both, must match
 161
 162 [LIMIT]
 163 max_batch_down = 262144
 164 max_queue_time = 121
 165 http_timeout = 121
 166 target_requests_outstanding = 10
 167 '''
 168
 169 # these need to be defined here so that they can be imported by import *
 170 cfg = ConfigParser(strict=False)
 171 optparser = OptionParser()
 172
 173 _mimetrans = bytes.maketrans(b'-'+slip.esc, slip.esc+b'-')
 174 def mime_translate(s):
 175   # SLIP-encoded packets cannot contain ESC ESC.
 176   # Swap `-' and ESC.  The result cannot contain `--'
 177   return s.translate(_mimetrans)
 178
 179 class ConfigResults:
 180   def __init__(self):
 181     pass
 182   def __repr__(self):
 183     return 'ConfigResults('+repr(self.__dict__)+')'
 184
 185 def log_discard(packet, iface, saddr, daddr, why):
 186   log_debug(DBG.DROP,
 187             'discarded packet [%s] %s -> %s: %s' % (iface, saddr, daddr, why),
 188             d=packet)
 189
 190 #---------- packet parsing ----------
 191
 192 def packet_addrs(packet):
 193   version = packet[0] >> 4
 194   if version == 4:
 195     addrlen = 4
 196     saddroff = 3*4
 197     factory = ipaddress.IPv4Address
 198   elif version == 6:
 199     addrlen = 16
 200     saddroff = 2*4
 201     factory = ipaddress.IPv6Address
 202   else:
 203     raise ValueError('unsupported IP version %d' % version)
 204   saddr = factory(packet[ saddroff           : saddroff + addrlen   ])
 205   daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ])
 206   return (saddr, daddr)
 207
 208 #---------- address handling ----------
 209
 210 def ipaddr(input):
 211   try:
 212     r = ipaddress.IPv4Address(input)
 213   except AddressValueError:
 214     r = ipaddress.IPv6Address(input)
 215   return r
 216
 217 def ipnetwork(input):
 218   try:
 219     r = ipaddress.IPv4Network(input)
 220   except NetworkValueError:
 221     r = ipaddress.IPv6Network(input)
 222   return r
 223
 224 #---------- ipif (SLIP) subprocess ----------
 225
 226 class SlipStreamDecoder():
 227   def __init__(self, desc, on_packet):
 228     self._buffer = b''
 229     self._on_packet = on_packet
 230     self._desc = desc
 231     self._log('__init__')
 232
 233   def _log(self, msg, **kwargs):
 234     log_debug(DBG.SLIP_FULL, 'slip %s: %s' % (self._desc, msg), **kwargs)
 235
 236   def inputdata(self, data):
 237     self._log('inputdata', d=data)
 238     data = self._buffer + data
 239     self._buffer = b''
 240     packets = slip.decode(data, True)
 241     self._buffer = packets.pop()
 242     for packet in packets:
 243       self._maybe_packet(packet)
 244     self._log('bufremain', d=self._buffer)
 245
 246   def _maybe_packet(self, packet):
 247     self._log('maybepacket', d=packet)
 248     if len(packet):
 249       self._on_packet(packet)
 250
 251   def flush(self):
 252     self._log('flush')
 253     data = self._buffer
 254     self._buffer = b''
 255     packets = slip.decode(data)
 256     assert(len(packets) == 1)
 257     self._maybe_packet(packets[0])
 258
 259 class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
 260   def __init__(self, router):
 261     self._router = router
 262     self._decoder = SlipStreamDecoder('ipif', self.slip_on_packet)
 263   def connectionMade(self): pass
 264   def outReceived(self, data):
 265     self._decoder.inputdata(data)
 266   def slip_on_packet(self, packet):
 267     (saddr, daddr) = packet_addrs(packet)
 268     if saddr.is_link_local or daddr.is_link_local:
 269       log_discard(packet, 'ipif', saddr, daddr, 'link-local')
 270       return
 271     self._router(packet, saddr, daddr)
 272   def processEnded(self, status):
 273     status.raiseException()
 274
 275 def start_ipif(command, router):
 276   ipif = _IpifProcessProtocol(router)
 277   reactor.spawnProcess(ipif,
 278                        '/bin/sh',['sh','-xc', command],
 279                        childFDs={0:'w', 1:'r', 2:2},
 280                        env=None)
 281   return ipif
 282
 283 def queue_inbound(ipif, packet):
 284   log_debug(DBG.FLOW, "queue_inbound", d=packet)
 285   ipif.transport.write(slip.delimiter)
 286   ipif.transport.write(slip.encode(packet))
 287   ipif.transport.write(slip.delimiter)
 288
 289 #---------- packet queue ----------
 290
 291 class PacketQueue():
 292   def __init__(self, desc, max_queue_time):
 293     self._desc = desc
 294     assert(desc + '')
 295     self._max_queue_time = max_queue_time
 296     self._pq = collections.deque() # packets
 297
 298   def _log(self, dflag, msg, **kwargs):
 299     log_debug(dflag, self._desc+' pq: '+msg, **kwargs)
 300
 301   def append(self, packet):
 302     self._log(DBG.QUEUE, 'append', d=packet)
 303     self._pq.append((time.monotonic(), packet))
 304
 305   def nonempty(self):
 306     self._log(DBG.QUEUE, 'nonempty ?')
 307     while True:
 308       try: (queuetime, packet) = self._pq[0]
 309       except IndexError:
 310         self._log(DBG.QUEUE, 'nonempty ? empty.')
 311         return False
 312
 313       age = time.monotonic() - queuetime
 314       if age > self._max_queue_time:
 315         # strip old packets off the front
 316         self._log(DBG.QUEUE, 'dropping (old)', d=packet)
 317         self._pq.popleft()
 318         continue
 319
 320       self._log(DBG.QUEUE, 'nonempty ? nonempty.')
 321       return True
 322
 323   def process(self, sizequery, moredata, max_batch):
 324     # sizequery() should return size of batch so far
 325     # moredata(s) should add s to batch
 326     self._log(DBG.QUEUE, 'process...')
 327     while True:
 328       try: (dummy, packet) = self._pq[0]
 329       except IndexError:
 330         self._log(DBG.QUEUE, 'process... empty')
 331         break
 332
 333       self._log(DBG.QUEUE_CTRL, 'process... packet', d=packet)
 334
 335       encoded = slip.encode(packet)
 336       sofar = sizequery()
 337
 338       self._log(DBG.QUEUE_CTRL,
 339                 'process... (sofar=%d, max=%d) encoded' % (sofar, max_batch),
 340                 d=encoded)
 341
 342       if sofar > 0:
 343         if sofar + len(slip.delimiter) + len(encoded) > max_batch:
 344           self._log(DBG.QUEUE_CTRL, 'process... overflow')
 345           break
 346         moredata(slip.delimiter)
 347
 348       moredata(encoded)
 349       self._pq.popleft()
 350
 351 #---------- error handling ----------
 352
 353 _crashing = False
 354
 355 def crash(err):
 356   global _crashing
 357   _crashing = True
 358   print('========== CRASH ==========', err,
 359         '===========================', file=sys.stderr)
 360   try: reactor.stop()
 361   except twisted.internet.error.ReactorNotRunning: pass
 362
 363 def crash_on_defer(defer):
 364   defer.addErrback(lambda err: crash(err))
 365
 366 def crash_on_critical(event):
 367   if event.get('log_level') >= LogLevel.critical:
 368     crash(twisted.logger.formatEvent(event))
 369
 370 #---------- config processing ----------
 371
 372 def _cfg_process_putatives():
 373   servers = { }
 374   clients = { }
 375   # maps from abstract object to canonical name for cs's
 376
 377   def putative(cmap, abstract, canoncs):
 378     try:
 379       current_canoncs = cmap[abstract]
 380     except KeyError:
 381       pass
 382     else:
 383       assert(current_canoncs == canoncs)
 384     cmap[abstract] = canoncs
 385
 386   server_pat = r'[-.0-9A-Za-z]+'
 387   client_pat = r'[.:0-9a-f]+'
 388   server_re = regexp.compile(server_pat)
 389   serverclient_re = regexp.compile(
 390         server_pat + r' ' + '(?:' + client_pat + '|LIMIT)')
 391
 392   for cs in cfg.sections():
 393     if cs == 'LIMIT' or cs == 'COMMON':
 394       # plan A "[LIMIT]" or "[COMMON]"
 395       continue
 396
 397     try:
 398       # plan B "[<client>]" part 1
 399       ci = ipaddr(cs)
 400     except AddressValueError:
 401
 402       if server_re.fullmatch(cs):
 403         # plan C "[<servername>]"
 404         putative(servers, cs, cs)
 405         continue
 406
 407       if serverclient_re.fullmatch(cs):
 408         # plan D "[<servername> <client>]" part 1
 409         (pss,pcs) = cs.split(' ')
 410
 411         if pcs == 'LIMIT':
 412           # plan E "[<servername> LIMIT]"
 413           continue
 414
 415         try:
 416           # plan D "[<servername> <client>]" part 2
 417           ci = ipaddr(pc)
 418         except AddressValueError:
 419           # plan F "[<some thing we do not understand>]"
 420           # well, we ignore this
 421           print('warning: ignoring config section %s' % cs, file=sys.stderr)
 422           continue
 423
 424         else: # no AddressValueError
 425           # plan D "[<servername> <client]" part 3
 426           putative(clients, ci, pcs)
 427           putative(servers, pss, pss)
 428           continue
 429
 430     else: # no AddressValueError
 431       # plan B "[<client>" part 2
 432       putative(clients, ci, cs)
 433       continue
 434
 435   return (servers, clients)
 436
 437 def cfg_process_general(c, ss):
 438   c.mtu = cfg1getint(ss, 'mtu')
 439
 440 def cfg_process_saddrs(c, ss):
 441   class ServerAddr():
 442     def __init__(self, port, addrspec):
 443       self.port = port
 444       # also self.addr
 445       try:
 446         self.addr = ipaddress.IPv4Address(addrspec)
 447         self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 448         self._inurl = b'%s'
 449       except AddressValueError:
 450         self.addr = ipaddress.IPv6Address(addrspec)
 451         self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 452         self._inurl = b'[%s]'
 453     def make_endpoint(self):
 454       return self._endpointfactory(reactor, self.port,
 455                                    interface= '%s' % self.addr)
 456     def url(self):
 457       url = b'http://' + (self._inurl % str(self.addr).encode('ascii'))
 458       if self.port != 80: url += b':%d' % self.port
 459       url += b'/'
 460       return url
 461     def __repr__(self):
 462       return 'ServerAddr'+repr((self.port,self.addr))
 463
 464   c.port = cfg1getint(ss,'port')
 465   c.saddrs = [ ]
 466   for addrspec in cfg1get(ss, 'addrs').split():
 467     sa = ServerAddr(c.port, addrspec)
 468     c.saddrs.append(sa)
 469
 470 def cfg_process_vnetwork(c, ss):
 471   c.vnetwork = ipnetwork(cfg1get(ss,'vnetwork'))
 472   if c.vnetwork.num_addresses < 3 + 2:
 473     raise ValueError('vnetwork needs at least 2^3 addresses')
 474
 475 def cfg_process_vaddr(c, ss):
 476   try:
 477     c.vaddr = cfg1get(ss,'vaddr')
 478   except NoOptionError:
 479     cfg_process_vnetwork(c, ss)
 480     c.vaddr = next(c.vnetwork.hosts())
 481
 482 def cfg_search_section(key,sections):
 483   for section in sections:
 484     if cfg.has_option(section, key):
 485       return section
 486   raise NoOptionError(key, repr(sections))
 487
 488 def cfg_get_raw(*args, **kwargs):
 489   # for passing to cfg_search
 490   return cfg.get(*args, raw=True, **kwargs)
 491
 492 def cfg_search(getter,key,sections):
 493   section = cfg_search_section(key,sections)
 494   return getter(section, key)
 495
 496 def cfg1get(section,key, getter=cfg.get,**kwargs):
 497   section = cfg_search_section(key,[section,'COMMON'])
 498   return getter(section,key,**kwargs)
 499
 500 def cfg1getint(section,key, **kwargs):
 501   return cfg1get(section,key, getter=cfg.getint,**kwargs);
 502
 503 def cfg_process_client_limited(cc,ss,sections,key):
 504   val = cfg_search(cfg1getint, key, sections)
 505   lim = cfg_search(cfg1getint, key, ['%s LIMIT' % ss, 'LIMIT'])
 506   cc.__dict__[key] = min(val,lim)
 507
 508 def cfg_process_client_common(cc,ss,cs,ci):
 509   # returns sections to search in, iff password is defined, otherwise None
 510   cc.ci = ci
 511
 512   sections = ['%s %s' % (ss,cs),
 513               cs,
 514               ss,
 515               'COMMON']
 516
 517   try: pwsection = cfg_search_section('password', sections)
 518   except NoOptionError: return None
 519
 520   pw = cfg1get(pwsection, 'password')
 521   cc.password = pw.encode('utf-8')
 522
 523   cfg_process_client_limited(cc,ss,sections,'target_requests_outstanding')
 524   cfg_process_client_limited(cc,ss,sections,'http_timeout')
 525
 526   return sections
 527
 528 def cfg_process_ipif(c, sections, varmap):
 529   for d, s in varmap:
 530     try: v = getattr(c, s)
 531     except AttributeError: continue
 532     setattr(c, d, v)
 533
 534   #print('CFGIPIF',repr((varmap, sections, c.__dict__)),file=sys.stderr)
 535
 536   section = cfg_search_section('ipif', sections)
 537   c.ipif_command = cfg1get(section,'ipif', vars=c.__dict__)
 538
 539 #---------- startup ----------
 540
 541 def log_debug_config(m):
 542   if not DBG.CONFIG in debug_set: return
 543   print('DBG.CONFIG:', m)
 544
 545 def common_startup(process_cfg):
 546   # calls process_cfg(putative_clients, putative_servers)
 547
 548   # ConfigParser hates #-comments after values
 549   trailingcomments_re = regexp.compile(r'#.*')
 550   cfg.read_string(trailingcomments_re.sub('', defcfg))
 551   need_defcfg = True
 552
 553   def readconfig(pathname, mandatory=True):
 554     def log(m, p=pathname):
 555       if not DBG.CONFIG in debug_set: return
 556       log_debug_config('%s: %s' % (m, p))
 557
 558     try:
 559       files = os.listdir(pathname)
 560
 561     except FileNotFoundError:
 562       if mandatory: raise
 563       log('skipped')
 564       return
 565
 566     except NotADirectoryError:
 567       cfg.read(pathname)
 568       log('read file')
 569       return
 570
 571     # is a directory
 572     log('directory')
 573     re = regexp.compile('[^-A-Za-z0-9_]')
 574     for f in os.listdir(pathname):
 575       if re.search(f): continue
 576       subpath = pathname + '/' + f
 577       try:
 578         os.stat(subpath)
 579       except FileNotFoundError:
 580         log('entry skipped', subpath)
 581         continue
 582       cfg.read(subpath)
 583       log('entry read', subpath)
 584
 585   def oc_config(od,os, value, op):
 586     nonlocal need_defcfg
 587     need_defcfg = False
 588     readconfig(value)
 589
 590   def oc_extra_config(od,os, value, op):
 591     readconfig(value)
 592
 593   def read_defconfig():
 594     readconfig('/etc/hippotat/config.d', False)
 595     readconfig('/etc/hippotat/passwords.d', False)
 596     readconfig('/etc/hippotat/master.cfg',   False)
 597
 598   def oc_defconfig(od,os, value, op):
 599     nonlocal need_defcfg
 600     need_defcfg = False
 601     read_defconfig(value)
 602
 603   def dfs_less_detailed(dl):
 604     return [df for df in DBG.iterconstants() if df <= dl]
 605
 606   def ds_default(od,os,dl,op):
 607     global debug_set
 608     debug_set.clear
 609     debug_set |= set(dfs_less_detailed(debug_def_detail))
 610
 611   def ds_select(od,os, spec, op):
 612     for it in spec.split(','):
 613
 614       if it.startswith('-'):
 615         mutator = debug_set.discard
 616         it = it[1:]
 617       else:
 618         mutator = debug_set.add
 619
 620       if it == '+':
 621         dfs = DBG.iterconstants()
 622
 623       else:
 624         if it.endswith('+'):
 625           mapper = dfs_less_detailed
 626           it = it[0:len(it)-1]
 627         else:
 628           mapper = lambda x: [x]
 629
 630           try:
 631             dfspec = DBG.lookupByName(it)
 632           except ValueError:
 633             optparser.error('unknown debug flag %s in --debug-select' % it)
 634
 635         dfs = mapper(dfspec)
 636
 637       for df in dfs:
 638         mutator(df)
 639
 640   optparser.add_option('-D', '--debug',
 641                        nargs=0,
 642                        action='callback',
 643                        help='enable default debug (to stdout)',
 644                        callback= ds_default)
 645
 646   optparser.add_option('--debug-select',
 647                        nargs=1,
 648                        type='string',
 649                        metavar='[-]DFLAG[+]|[-]+,...',
 650                        help=
 651 '''enable (`-': disable) each specified DFLAG;
 652 `+': do same for all "more interesting" DFLAGSs;
 653 just `+': all DFLAGs.
 654   DFLAGS: ''' + ' '.join([df.name for df in DBG.iterconstants()]),
 655                        action='callback',
 656                        callback= ds_select)
 657
 658   optparser.add_option('-c', '--config',
 659                        nargs=1,
 660                        type='string',
 661                        metavar='CONFIGFILE',
 662                        dest='configfile',
 663                        action='callback',
 664                        callback= oc_config)
 665
 666   optparser.add_option('--extra-config',
 667                        nargs=1,
 668                        type='string',
 669                        metavar='CONFIGFILE',
 670                        dest='configfile',
 671                        action='callback',
 672                        callback= oc_extra_config)
 673
 674   optparser.add_option('--default-config',
 675                        action='callback',
 676                        callback= oc_defconfig)
 677
 678   (opts, args) = optparser.parse_args()
 679   if len(args): optparser.error('no non-option arguments please')
 680
 681   if need_defcfg:
 682     read_defconfig()
 683
 684   try:
 685     (pss, pcs) = _cfg_process_putatives()
 686     process_cfg(opts, pss, pcs)
 687   except (configparser.Error, ValueError):
 688     traceback.print_exc(file=sys.stderr)
 689     print('\nInvalid configuration, giving up.', file=sys.stderr)
 690     sys.exit(12)
 691
 692
 693   #print('X', debug_set, file=sys.stderr)
 694
 695   log_formatter = twisted.logger.formatEventAsClassicLogText
 696   stdout_obs = twisted.logger.FileLogObserver(sys.stdout, log_formatter)
 697   stderr_obs = twisted.logger.FileLogObserver(sys.stderr, log_formatter)
 698   pred = twisted.logger.LogLevelFilterPredicate(LogLevel.error)
 699   stdsomething_obs = twisted.logger.FilteringLogObserver(
 700     stderr_obs, [pred], stdout_obs
 701   )
 702   global file_log_observer
 703   file_log_observer = twisted.logger.FilteringLogObserver(
 704     stdsomething_obs, [LogNotBoringTwisted()]
 705   )
 706   #log_observer = stdsomething_obs
 707   twisted.logger.globalLogBeginner.beginLoggingTo(
 708     [ file_log_observer, crash_on_critical ]
 709     )
 710
 711 def common_run():
 712   log_debug(DBG.INIT, 'entering reactor')
 713   if not _crashing: reactor.run()
 714   print('ENDED', file=sys.stderr)
 715   sys.exit(16)