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
 171 def queue_inbound(packet):
 172   ipif.transport.write(slip.delimiter)
 173   ipif.transport.write(slip.encode(packet))
 174   ipif.transport.write(slip.delimiter)
 175
 176 #---------- packet queue ----------
 177
 178 class PacketQueue():
 179   def __init__(self, max_queue_time):
 180     self._max_queue_time = max_queue_time
 181     self._pq = collections.deque() # packets
 182
 183   def append(self, packet):
 184     self._pq.append((time.monotonic(), packet))
 185
 186   def nonempty(self):
 187     while True:
 188       try: (queuetime, packet) = self._pq[0]
 189       except IndexError: return False
 190
 191       age = time.monotonic() - queuetime
 192       if age > self.max_queue_time:
 193         # strip old packets off the front
 194         self._pq.popleft()
 195         continue
 196
 197       return True
 198
 199   def process(self, sizequery, moredata, max_batch):
 200     # sizequery() should return size of batch so far
 201     # moredata(s) should add s to batch
 202     while True:
 203       try: (dummy, packet) = self._pq[0]
 204       except IndexError: break
 205
 206       encoded = slip.encode(packet)
 207       sofar = sizequery()
 208
 209       if sofar > 0:
 210         if sofar + len(slip.delimiter) + len(encoded) > max_batch:
 211           break
 212         moredata(slip.delimiter)
 213
 214       moredata(encoded)
 215       self._pq.popLeft()
 216
 217 #---------- error handling ----------
 218
 219 def crash(err):
 220   print('CRASH ', err, file=sys.stderr)
 221   try: reactor.stop()
 222   except twisted.internet.error.ReactorNotRunning: pass
 223
 224 def crash_on_defer(defer):
 225   defer.addErrback(lambda err: crash(err))
 226
 227 def crash_on_critical(event):
 228   if event.get('log_level') >= LogLevel.critical:
 229     crash(twisted.logger.formatEvent(event))
 230
 231 #---------- config processing ----------
 232
 233 def process_cfg_common_always():
 234   global mtu
 235   c.mtu = cfg.get('virtual','mtu')
 236
 237 def process_cfg_ipif(section, varmap):
 238   for d, s in varmap:
 239     try: v = getattr(c, s)
 240     except AttributeError: continue
 241     setattr(c, d, v)
 242
 243   print(repr(c))
 244
 245   c.ipif_command = cfg.get(section,'ipif', vars=c.__dict__)
 246
 247 def process_cfg_network():
 248   c.network = ipnetwork(cfg.get('virtual','network'))
 249   if c.network.num_addresses < 3 + 2:
 250     raise ValueError('network needs at least 2^3 addresses')
 251
 252 def process_cfg_server():
 253   try:
 254     c.server = cfg.get('virtual','server')
 255   except NoOptionError:
 256     process_cfg_network()
 257     c.server = next(c.network.hosts())
 258
 259 class ServerAddr():
 260   def __init__(self, port, addrspec):
 261     self.port = port
 262     # also self.addr
 263     try:
 264       self.addr = ipaddress.IPv4Address(addrspec)
 265       self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 266       self._inurl = '%s'
 267     except AddressValueError:
 268       self.addr = ipaddress.IPv6Address(addrspec)
 269       self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 270       self._inurl = '[%s]'
 271   def make_endpoint(self):
 272     return self._endpointfactory(reactor, self.port, self.addr)
 273   def url(self):
 274     url = 'http://' + (self._inurl % self.addr)
 275     if self.port != 80: url += ':%d' % self.port
 276     url += '/'
 277     return url
 278
 279 def process_cfg_saddrs():
 280   try: port = cfg.getint('server','port')
 281   except NoOptionError: port = 80
 282
 283   c.saddrs = [ ]
 284   for addrspec in cfg.get('server','addrs').split():
 285     sa = ServerAddr(port, addrspec)
 286     c.saddrs.append(sa)
 287
 288 def process_cfg_clients(constructor):
 289   c.clients = [ ]
 290   for cs in cfg.sections():
 291     if not (':' in cs or '.' in cs): continue
 292     ci = ipaddr(cs)
 293     pw = cfg.get(cs, 'password')
 294     constructor(ci,cs,pw)
 295
 296 #---------- startup ----------
 297
 298 def common_startup():
 299   twisted.logger.globalLogPublisher.addObserver(crash_on_critical)
 300
 301   optparser.add_option('-c', '--config', dest='configfile',
 302                        default='/etc/hippotat/config')
 303   (opts, args) = optparser.parse_args()
 304   if len(args): optparser.error('no non-option arguments please')
 305
 306   re = regexp.compile('#.*')
 307   cfg.read_string(re.sub('', defcfg))
 308   cfg.read(opts.configfile)
 309
 310 def common_run():
 311   reactor.run()
 312   print('CRASHED (end)', file=sys.stderr)