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

   1 # -*- python -*-
   2
   3 import signal
   4 signal.signal(signal.SIGINT, signal.SIG_DFL)
   5
   6 import sys
   7
   8 import twisted
   9 from twisted.internet import reactor
  10 import twisted.internet.endpoints
  11 import twisted.logger
  12 from twisted.logger import LogLevel
  13 import twisted.python.constants
  14 from twisted.python.constants import NamedConstant
  15
  16 import ipaddress
  17 from ipaddress import AddressValueError
  18
  19 from optparse import OptionParser
  20 from configparser import ConfigParser
  21 from configparser import NoOptionError
  22
  23 import collections
  24 import time
  25 import codecs
  26 import traceback
  27
  28 import re as regexp
  29
  30 import hippotat.slip as slip
  31
  32 class DBG(twisted.python.constants.Names):
  33   ROUTE = NamedConstant()
  34   DROP = NamedConstant()
  35   FLOW = NamedConstant()
  36   HTTP = NamedConstant()
  37   HTTP_CTRL = NamedConstant()
  38   INIT = NamedConstant()
  39   QUEUE = NamedConstant()
  40   QUEUE_CTRL = NamedConstant()
  41   HTTP_FULL = NamedConstant()
  42   SLIP_FULL = NamedConstant()
  43
  44 _hex_codec = codecs.getencoder('hex_codec')
  45
  46 log = twisted.logger.Logger()
  47
  48 def log_debug(dflag, msg, idof=None, d=None):
  49   #print('---------------->',repr((dflag, msg, idof, d)), file=sys.stderr)
  50   if idof is not None:
  51     msg = '[%d] %s' % (id(idof), msg)
  52   if d is not None:
  53     d = d[0:64]
  54     d = _hex_codec(d)[0].decode('ascii')
  55     msg += ' ' + d
  56   log.info('{dflag} {msgcore}', dflag=dflag, msgcore=msg)
  57
  58 defcfg = '''
  59 [DEFAULT]
  60 #[<client>] overrides
  61 max_batch_down = 65536           # used by server, subject to [limits]
  62 max_queue_time = 10              # used by server, subject to [limits]
  63 max_request_time = 54            # used by server, subject to [limits]
  64 target_requests_outstanding = 3  # must match; subject to [limits] on server
  65 max_requests_outstanding = 4     # used by client
  66 max_batch_up = 4000              # used by client
  67 http_timeout = 30                # used by client
  68 http_retry = 5                   # used by client
  69
  70 #[server] or [<client>] overrides
  71 ipif = userv root ipif %(local)s,%(peer)s,%(mtu)s,slip %(rnets)s
  72 # extra interpolations:  %(local)s        %(peer)s          %(rnet)s
  73 #  obtained   on server  [virtual]server  [virtual]relay    [virtual]network
  74 #      from   on client  <client>         [virtual]server   [virtual]routes
  75
  76 [virtual]
  77 mtu = 1500
  78 routes = ''
  79 # network = <prefix>/<len>  # mandatory for server
  80 # server  = <ipaddr>   # used by both, default is computed from `network'
  81 # relay   = <ipaddr>   # used by server, default from `network' and `server'
  82 #  default server is first host in network
  83 #  default relay is first host which is not server
  84
  85 [server]
  86 # addrs = 127.0.0.1 ::1    # mandatory for server
  87 port = 80                  # used by server
  88 # url              # used by client; default from first `addrs' and `port'
  89
  90 # [<client-ip4-or-ipv6-address>]
  91 # password = <password>    # used by both, must match
  92
  93 [limits]
  94 max_batch_down = 262144           # used by server
  95 max_queue_time = 121              # used by server
  96 max_request_time = 121            # used by server
  97 target_requests_outstanding = 10  # used by server
  98 '''
  99
 100 # these need to be defined here so that they can be imported by import *
 101 cfg = ConfigParser()
 102 optparser = OptionParser()
 103
 104 _mimetrans = bytes.maketrans(b'-'+slip.esc, slip.esc+b'-')
 105 def mime_translate(s):
 106   # SLIP-encoded packets cannot contain ESC ESC.
 107   # Swap `-' and ESC.  The result cannot contain `--'
 108   return s.translate(_mimetrans)
 109
 110 class ConfigResults:
 111   def __init__(self, d = { }):
 112     self.__dict__ = d
 113   def __repr__(self):
 114     return 'ConfigResults('+repr(self.__dict__)+')'
 115
 116 c = ConfigResults()
 117
 118 def log_discard(packet, iface, saddr, daddr, why):
 119   log_debug(DBG.DROP,
 120             'discarded packet [%s] %s -> %s: %s' % (iface, saddr, daddr, why),
 121             d=packet)
 122
 123 #---------- packet parsing ----------
 124
 125 def packet_addrs(packet):
 126   version = packet[0] >> 4
 127   if version == 4:
 128     addrlen = 4
 129     saddroff = 3*4
 130     factory = ipaddress.IPv4Address
 131   elif version == 6:
 132     addrlen = 16
 133     saddroff = 2*4
 134     factory = ipaddress.IPv6Address
 135   else:
 136     raise ValueError('unsupported IP version %d' % version)
 137   saddr = factory(packet[ saddroff           : saddroff + addrlen   ])
 138   daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ])
 139   return (saddr, daddr)
 140
 141 #---------- address handling ----------
 142
 143 def ipaddr(input):
 144   try:
 145     r = ipaddress.IPv4Address(input)
 146   except AddressValueError:
 147     r = ipaddress.IPv6Address(input)
 148   return r
 149
 150 def ipnetwork(input):
 151   try:
 152     r = ipaddress.IPv4Network(input)
 153   except NetworkValueError:
 154     r = ipaddress.IPv6Network(input)
 155   return r
 156
 157 #---------- ipif (SLIP) subprocess ----------
 158
 159 class SlipStreamDecoder():
 160   def __init__(self, desc, on_packet):
 161     self._buffer = b''
 162     self._on_packet = on_packet
 163     self._desc = desc
 164     self._log('__init__')
 165
 166   def _log(self, msg, **kwargs):
 167     log_debug(DBG.SLIP_FULL, 'slip %s: %s' % (self._desc, msg), **kwargs)
 168
 169   def inputdata(self, data):
 170     self._log('inputdata', d=data)
 171     data = self._buffer + data
 172     self._buffer = b''
 173     packets = slip.decode(data)
 174     self._buffer = packets.pop()
 175     for packet in packets:
 176       self._maybe_packet(packet)
 177     self._log('bufremain', d=self._buffer)
 178
 179   def _maybe_packet(self, packet):
 180     self._log('maybepacket', d=packet)
 181     if len(packet):
 182       self._on_packet(packet)
 183
 184   def flush(self):
 185     self._log('flush')
 186     self._maybe_packet(self._buffer)
 187     self._buffer = b''
 188
 189 class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
 190   def __init__(self, router):
 191     self._router = router
 192     self._decoder = SlipStreamDecoder('ipif', self.slip_on_packet)
 193   def connectionMade(self): pass
 194   def outReceived(self, data):
 195     self._decoder.inputdata(data)
 196   def slip_on_packet(self, packet):
 197     (saddr, daddr) = packet_addrs(packet)
 198     if saddr.is_link_local or daddr.is_link_local:
 199       log_discard(packet, 'ipif', saddr, daddr, 'link-local')
 200       return
 201     self._router(packet, saddr, daddr)
 202   def processEnded(self, status):
 203     status.raiseException()
 204
 205 def start_ipif(command, router):
 206   global ipif
 207   ipif = _IpifProcessProtocol(router)
 208   reactor.spawnProcess(ipif,
 209                        '/bin/sh',['sh','-xc', command],
 210                        childFDs={0:'w', 1:'r', 2:2},
 211                        env=None)
 212
 213 def queue_inbound(packet):
 214   log_debug(DBG.FLOW, "queue_inbound", d=packet)
 215   ipif.transport.write(slip.delimiter)
 216   ipif.transport.write(slip.encode(packet))
 217   ipif.transport.write(slip.delimiter)
 218
 219 #---------- packet queue ----------
 220
 221 class PacketQueue():
 222   def __init__(self, desc, max_queue_time):
 223     self._desc = desc
 224     assert(desc + '')
 225     self._max_queue_time = max_queue_time
 226     self._pq = collections.deque() # packets
 227
 228   def _log(self, dflag, msg, **kwargs):
 229     log_debug(dflag, self._desc+' pq: '+msg, **kwargs)
 230
 231   def append(self, packet):
 232     self._log(DBG.QUEUE, 'append', d=packet)
 233     self._pq.append((time.monotonic(), packet))
 234
 235   def nonempty(self):
 236     self._log(DBG.QUEUE, 'nonempty ?')
 237     while True:
 238       try: (queuetime, packet) = self._pq[0]
 239       except IndexError:
 240         self._log(DBG.QUEUE, 'nonempty ? empty.')
 241         return False
 242
 243       age = time.monotonic() - queuetime
 244       if age > self._max_queue_time:
 245         # strip old packets off the front
 246         self._log(DBG.QUEUE, 'dropping (old)', d=packet)
 247         self._pq.popleft()
 248         continue
 249
 250       self._log(DBG.QUEUE, 'nonempty ? nonempty.')
 251       return True
 252
 253   def process(self, sizequery, moredata, max_batch):
 254     # sizequery() should return size of batch so far
 255     # moredata(s) should add s to batch
 256     self._log(DBG.QUEUE, 'process...')
 257     while True:
 258       try: (dummy, packet) = self._pq[0]
 259       except IndexError:
 260         self._log(DBG.QUEUE, 'process... empty')
 261         break
 262
 263       self._log(DBG.QUEUE_CTRL, 'process... packet', d=packet)
 264
 265       encoded = slip.encode(packet)
 266       sofar = sizequery()
 267
 268       self._log(DBG.QUEUE_CTRL,
 269                 'process... (sofar=%d, max=%d) encoded' % (sofar, max_batch),
 270                 d=encoded)
 271
 272       if sofar > 0:
 273         if sofar + len(slip.delimiter) + len(encoded) > max_batch:
 274           self._log(DBG.QUEUE_CTRL, 'process... overflow')
 275           break
 276         moredata(slip.delimiter)
 277
 278       moredata(encoded)
 279       self._pq.popleft()
 280
 281 #---------- error handling ----------
 282
 283 _crashing = False
 284
 285 def crash(err):
 286   global _crashing
 287   _crashing = True
 288   print('CRASH ', err, file=sys.stderr)
 289   try: reactor.stop()
 290   except twisted.internet.error.ReactorNotRunning: pass
 291
 292 def crash_on_defer(defer):
 293   defer.addErrback(lambda err: crash(err))
 294
 295 def crash_on_critical(event):
 296   if event.get('log_level') >= LogLevel.critical:
 297     crash(twisted.logger.formatEvent(event))
 298
 299 #---------- config processing ----------
 300
 301 def process_cfg_common_always():
 302   global mtu
 303   c.mtu = cfg.get('virtual','mtu')
 304
 305 def process_cfg_ipif(section, varmap):
 306   for d, s in varmap:
 307     try: v = getattr(c, s)
 308     except AttributeError: continue
 309     setattr(c, d, v)
 310
 311   #print(repr(c))
 312
 313   c.ipif_command = cfg.get(section,'ipif', vars=c.__dict__)
 314
 315 def process_cfg_network():
 316   c.network = ipnetwork(cfg.get('virtual','network'))
 317   if c.network.num_addresses < 3 + 2:
 318     raise ValueError('network needs at least 2^3 addresses')
 319
 320 def process_cfg_server():
 321   try:
 322     c.server = cfg.get('virtual','server')
 323   except NoOptionError:
 324     process_cfg_network()
 325     c.server = next(c.network.hosts())
 326
 327 class ServerAddr():
 328   def __init__(self, port, addrspec):
 329     self.port = port
 330     # also self.addr
 331     try:
 332       self.addr = ipaddress.IPv4Address(addrspec)
 333       self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 334       self._inurl = b'%s'
 335     except AddressValueError:
 336       self.addr = ipaddress.IPv6Address(addrspec)
 337       self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 338       self._inurl = b'[%s]'
 339   def make_endpoint(self):
 340     return self._endpointfactory(reactor, self.port, self.addr)
 341   def url(self):
 342     url = b'http://' + (self._inurl % str(self.addr).encode('ascii'))
 343     if self.port != 80: url += b':%d' % self.port
 344     url += b'/'
 345     return url
 346
 347 def process_cfg_saddrs():
 348   try: port = cfg.getint('server','port')
 349   except NoOptionError: port = 80
 350
 351   c.saddrs = [ ]
 352   for addrspec in cfg.get('server','addrs').split():
 353     sa = ServerAddr(port, addrspec)
 354     c.saddrs.append(sa)
 355
 356 def process_cfg_clients(constructor):
 357   c.clients = [ ]
 358   for cs in cfg.sections():
 359     if not (':' in cs or '.' in cs): continue
 360     ci = ipaddr(cs)
 361     pw = cfg.get(cs, 'password')
 362     pw = pw.encode('utf-8')
 363     constructor(ci,cs,pw)
 364
 365 #---------- startup ----------
 366
 367 def common_startup():
 368   log_formatter = twisted.logger.formatEventAsClassicLogText
 369   log_observer = twisted.logger.FileLogObserver(sys.stderr, log_formatter)
 370   twisted.logger.globalLogBeginner.beginLoggingTo(
 371     [ log_observer, crash_on_critical ]
 372     )
 373
 374   optparser.add_option('-c', '--config', dest='configfile',
 375                        default='/etc/hippotat/config')
 376   (opts, args) = optparser.parse_args()
 377   if len(args): optparser.error('no non-option arguments please')
 378
 379   re = regexp.compile('#.*')
 380   cfg.read_string(re.sub('', defcfg))
 381   cfg.read(opts.configfile)
 382
 383 def common_run():
 384   log_debug(DBG.INIT, 'entering reactor')
 385   if not _crashing: reactor.run()
 386   print('CRASHED (end)', file=sys.stderr)