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