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