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