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