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     def log_ignore(why):
 394       print('warning: ignoring config section [%s] (%s)' % (cs, why),
 395             file=sys.stderr)
 396
 397     if cs == 'LIMIT' or cs == 'COMMON':
 398       # plan A "[LIMIT]" or "[COMMON]"
 399       continue
 400
 401     try:
 402       # plan B "[<client>]" part 1
 403       ci = ipaddr(cs)
 404     except AddressValueError:
 405
 406       if server_re.fullmatch(cs):
 407         # plan C "[<servername>]"
 408         putative(servers, cs, cs)
 409         continue
 410
 411       if serverclient_re.fullmatch(cs):
 412         # plan D "[<servername> <client>]" part 1
 413         (pss,pcs) = cs.split(' ')
 414
 415         if pcs == 'LIMIT':
 416           # plan E "[<servername> LIMIT]"
 417           continue
 418
 419         try:
 420           # plan D "[<servername> <client>]" part 2
 421           ci = ipaddr(pc)
 422         except AddressValueError:
 423           # plan F "[<some thing we do not understand>]"
 424           log_ignore('bad-addr')
 425           continue
 426
 427         else: # no AddressValueError
 428           # plan D "[<servername> <client]" part 3
 429           putative(clients, ci, pcs)
 430           putative(servers, pss, pss)
 431           continue
 432
 433     else: # no AddressValueError
 434       # plan B "[<client>" part 2
 435       putative(clients, ci, cs)
 436       continue
 437
 438   return (servers, clients)
 439
 440 def cfg_process_general(c, ss):
 441   c.mtu = cfg1getint(ss, 'mtu')
 442
 443 def cfg_process_saddrs(c, ss):
 444   class ServerAddr():
 445     def __init__(self, port, addrspec):
 446       self.port = port
 447       # also self.addr
 448       try:
 449         self.addr = ipaddress.IPv4Address(addrspec)
 450         self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 451         self._inurl = b'%s'
 452       except AddressValueError:
 453         self.addr = ipaddress.IPv6Address(addrspec)
 454         self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 455         self._inurl = b'[%s]'
 456     def make_endpoint(self):
 457       return self._endpointfactory(reactor, self.port,
 458                                    interface= '%s' % self.addr)
 459     def url(self):
 460       url = b'http://' + (self._inurl % str(self.addr).encode('ascii'))
 461       if self.port != 80: url += b':%d' % self.port
 462       url += b'/'
 463       return url
 464     def __repr__(self):
 465       return 'ServerAddr'+repr((self.port,self.addr))
 466
 467   c.port = cfg1getint(ss,'port')
 468   c.saddrs = [ ]
 469   for addrspec in cfg1get(ss, 'addrs').split():
 470     sa = ServerAddr(c.port, addrspec)
 471     c.saddrs.append(sa)
 472
 473 def cfg_process_vnetwork(c, ss):
 474   c.vnetwork = ipnetwork(cfg1get(ss,'vnetwork'))
 475   if c.vnetwork.num_addresses < 3 + 2:
 476     raise ValueError('vnetwork needs at least 2^3 addresses')
 477
 478 def cfg_process_vaddr(c, ss):
 479   try:
 480     c.vaddr = cfg1get(ss,'vaddr')
 481   except NoOptionError:
 482     cfg_process_vnetwork(c, ss)
 483     c.vaddr = next(c.vnetwork.hosts())
 484
 485 def cfg_search_section(key,sections):
 486   for section in sections:
 487     if cfg.has_option(section, key):
 488       return section
 489   raise NoOptionError(key, repr(sections))
 490
 491 def cfg_get_raw(*args, **kwargs):
 492   # for passing to cfg_search
 493   return cfg.get(*args, raw=True, **kwargs)
 494
 495 def cfg_search(getter,key,sections):
 496   section = cfg_search_section(key,sections)
 497   return getter(section, key)
 498
 499 def cfg1get(section,key, getter=cfg.get,**kwargs):
 500   section = cfg_search_section(key,[section,'COMMON'])
 501   return getter(section,key,**kwargs)
 502
 503 def cfg1getint(section,key, **kwargs):
 504   return cfg1get(section,key, getter=cfg.getint,**kwargs);
 505
 506 def cfg_process_client_limited(cc,ss,sections,key):
 507   val = cfg_search(cfg1getint, key, sections)
 508   lim = cfg_search(cfg1getint, key, ['%s LIMIT' % ss, 'LIMIT'])
 509   cc.__dict__[key] = min(val,lim)
 510
 511 def cfg_process_client_common(cc,ss,cs,ci):
 512   # returns sections to search in, iff password is defined, otherwise None
 513   cc.ci = ci
 514
 515   sections = ['%s %s' % (ss,cs),
 516               cs,
 517               ss,
 518               'COMMON']
 519
 520   try: pwsection = cfg_search_section('password', sections)
 521   except NoOptionError: return None
 522
 523   pw = cfg1get(pwsection, 'password')
 524   cc.password = pw.encode('utf-8')
 525
 526   cfg_process_client_limited(cc,ss,sections,'target_requests_outstanding')
 527   cfg_process_client_limited(cc,ss,sections,'http_timeout')
 528
 529   return sections
 530
 531 def cfg_process_ipif(c, sections, varmap):
 532   for d, s in varmap:
 533     try: v = getattr(c, s)
 534     except AttributeError: continue
 535     setattr(c, d, v)
 536
 537   #print('CFGIPIF',repr((varmap, sections, c.__dict__)),file=sys.stderr)
 538
 539   section = cfg_search_section('ipif', sections)
 540   c.ipif_command = cfg1get(section,'ipif', vars=c.__dict__)
 541
 542 #---------- startup ----------
 543
 544 def log_debug_config(m):
 545   if not DBG.CONFIG in debug_set: return
 546   print('DBG.CONFIG:', m)
 547
 548 def common_startup(process_cfg):
 549   # calls process_cfg(putative_clients, putative_servers)
 550
 551   # ConfigParser hates #-comments after values
 552   trailingcomments_re = regexp.compile(r'#.*')
 553   cfg.read_string(trailingcomments_re.sub('', defcfg))
 554   need_defcfg = True
 555
 556   def readconfig(pathname, mandatory=True):
 557     def log(m, p=pathname):
 558       if not DBG.CONFIG in debug_set: return
 559       log_debug_config('%s: %s' % (m, p))
 560
 561     try:
 562       files = os.listdir(pathname)
 563
 564     except FileNotFoundError:
 565       if mandatory: raise
 566       log('skipped')
 567       return
 568
 569     except NotADirectoryError:
 570       cfg.read(pathname)
 571       log('read file')
 572       return
 573
 574     # is a directory
 575     log('directory')
 576     re = regexp.compile('[^-A-Za-z0-9_]')
 577     for f in os.listdir(pathname):
 578       if re.search(f): continue
 579       subpath = pathname + '/' + f
 580       try:
 581         os.stat(subpath)
 582       except FileNotFoundError:
 583         log('entry skipped', subpath)
 584         continue
 585       cfg.read(subpath)
 586       log('entry read', subpath)
 587
 588   def oc_config(od,os, value, op):
 589     nonlocal need_defcfg
 590     need_defcfg = False
 591     readconfig(value)
 592
 593   def oc_extra_config(od,os, value, op):
 594     readconfig(value)
 595
 596   def read_defconfig():
 597     readconfig('/etc/hippotat/config.d', False)
 598     readconfig('/etc/hippotat/passwords.d', False)
 599     readconfig('/etc/hippotat/master.cfg',   False)
 600
 601   def oc_defconfig(od,os, value, op):
 602     nonlocal need_defcfg
 603     need_defcfg = False
 604     read_defconfig(value)
 605
 606   def dfs_less_detailed(dl):
 607     return [df for df in DBG.iterconstants() if df <= dl]
 608
 609   def ds_default(od,os,dl,op):
 610     global debug_set
 611     debug_set.clear
 612     debug_set |= set(dfs_less_detailed(debug_def_detail))
 613
 614   def ds_select(od,os, spec, op):
 615     for it in spec.split(','):
 616
 617       if it.startswith('-'):
 618         mutator = debug_set.discard
 619         it = it[1:]
 620       else:
 621         mutator = debug_set.add
 622
 623       if it == '+':
 624         dfs = DBG.iterconstants()
 625
 626       else:
 627         if it.endswith('+'):
 628           mapper = dfs_less_detailed
 629           it = it[0:len(it)-1]
 630         else:
 631           mapper = lambda x: [x]
 632
 633           try:
 634             dfspec = DBG.lookupByName(it)
 635           except ValueError:
 636             optparser.error('unknown debug flag %s in --debug-select' % it)
 637
 638         dfs = mapper(dfspec)
 639
 640       for df in dfs:
 641         mutator(df)
 642
 643   optparser.add_option('-D', '--debug',
 644                        nargs=0,
 645                        action='callback',
 646                        help='enable default debug (to stdout)',
 647                        callback= ds_default)
 648
 649   optparser.add_option('--debug-select',
 650                        nargs=1,
 651                        type='string',
 652                        metavar='[-]DFLAG[+]|[-]+,...',
 653                        help=
 654 '''enable (`-': disable) each specified DFLAG;
 655 `+': do same for all "more interesting" DFLAGSs;
 656 just `+': all DFLAGs.
 657   DFLAGS: ''' + ' '.join([df.name for df in DBG.iterconstants()]),
 658                        action='callback',
 659                        callback= ds_select)
 660
 661   optparser.add_option('-c', '--config',
 662                        nargs=1,
 663                        type='string',
 664                        metavar='CONFIGFILE',
 665                        dest='configfile',
 666                        action='callback',
 667                        callback= oc_config)
 668
 669   optparser.add_option('--extra-config',
 670                        nargs=1,
 671                        type='string',
 672                        metavar='CONFIGFILE',
 673                        dest='configfile',
 674                        action='callback',
 675                        callback= oc_extra_config)
 676
 677   optparser.add_option('--default-config',
 678                        action='callback',
 679                        callback= oc_defconfig)
 680
 681   (opts, args) = optparser.parse_args()
 682   if len(args): optparser.error('no non-option arguments please')
 683
 684   if need_defcfg:
 685     read_defconfig()
 686
 687   try:
 688     (pss, pcs) = _cfg_process_putatives()
 689     process_cfg(opts, pss, pcs)
 690   except (configparser.Error, ValueError):
 691     traceback.print_exc(file=sys.stderr)
 692     print('\nInvalid configuration, giving up.', file=sys.stderr)
 693     sys.exit(12)
 694
 695
 696   #print('X', debug_set, file=sys.stderr)
 697
 698   log_formatter = twisted.logger.formatEventAsClassicLogText
 699   stdout_obs = twisted.logger.FileLogObserver(sys.stdout, log_formatter)
 700   stderr_obs = twisted.logger.FileLogObserver(sys.stderr, log_formatter)
 701   pred = twisted.logger.LogLevelFilterPredicate(LogLevel.error)
 702   stdsomething_obs = twisted.logger.FilteringLogObserver(
 703     stderr_obs, [pred], stdout_obs
 704   )
 705   global file_log_observer
 706   file_log_observer = twisted.logger.FilteringLogObserver(
 707     stdsomething_obs, [LogNotBoringTwisted()]
 708   )
 709   #log_observer = stdsomething_obs
 710   twisted.logger.globalLogBeginner.beginLoggingTo(
 711     [ file_log_observer, crash_on_critical ]
 712     )
 713
 714 def common_run():
 715   log_debug(DBG.INIT, 'entering reactor')
 716   if not _crashing: reactor.run()
 717   print('ENDED', file=sys.stderr)
 718   sys.exit(16)