mdw@git.distorted.org.uk Git - hippotat/blob - server

   1 #!/usr/bin/python3
   2
   3 import sys
   4 import os
   5
   6 import twisted
   7 import twisted.internet
   8 import twisted.internet.endpoints
   9 from twisted.internet import reactor
  10 from twisted.web.server import NOT_DONE_YET
  11 from twisted.logger import LogLevel
  12
  13 import ipaddress
  14 from ipaddress import AddressValueError
  15
  16 #import twisted.web.server import Site
  17 #from twisted.web.resource import Resource
  18
  19 from optparse import OptionParser
  20 from configparser import ConfigParser
  21 from configparser import NoOptionError
  22
  23 import collections
  24
  25 import syslog
  26
  27 clients = { }
  28
  29 def ipaddr(input):
  30   try:
  31     r = ipaddress.IPv4Address(input)
  32   except AddressValueError:
  33     r = ipaddress.IPv6Address(input)
  34   return r
  35
  36 def ipnetwork(input):
  37   try:
  38     r = ipaddress.IPv4Network(input)
  39   except NetworkValueError:
  40     r = ipaddress.IPv6Network(input)
  41   return r
  42
  43 defcfg = '''
  44 [DEFAULT]
  45 max_batch_down = 65536
  46 max_queue_time = 10
  47 max_request_time = 54
  48
  49 [virtual]
  50 mtu = 1500
  51 # network
  52 # [host]
  53 # [relay]
  54
  55 [server]
  56 ipif = userv root ipif %(host)s,%(relay)s,%(mtu)s,slip %(network)s
  57 addrs = 127.0.0.1 ::1
  58 port = 80
  59
  60 [limits]
  61 max_batch_down = 262144
  62 max_queue_time = 121
  63 max_request_time = 121
  64 '''
  65
  66 #---------- "router" ----------
  67
  68 def route(packet, saddr, daddr):
  69   print('TRACE ', saddr, daddr, packet)
  70   try: client = clients[daddr]
  71   except KeyError: dclient = None
  72   if dclient is not None:
  73     dclient.queue_outbound(packet)
  74   elif saddr.is_link_local or daddr.is_link_local:
  75     log_discard(packet, saddr, daddr, 'link-local')
  76   elif daddr == host or daddr not in network:
  77     print('TRACE INBOUND ', saddr, daddr, packet)
  78     queue_inbound(packet)
  79   elif daddr == relay:
  80     log_discard(packet, saddr, daddr, 'relay')
  81   else:
  82     log_discard(packet, saddr, daddr, 'no client')
  83
  84 def log_discard(packet, saddr, daddr, why):
  85   print('DROP ', saddr, daddr, why)
  86 #  syslog.syslog(syslog.LOG_DEBUG,
  87 #                'discarded packet %s -> %s (%s)' % (saddr, daddr, why))
  88
  89 #---------- ipif (slip subprocess) ----------
  90
  91 class IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
  92   def __init__(self):
  93     self._buffer = b''
  94   def connectionMade(self): pass
  95   def outReceived(self, data):
  96     #print('RECV ', repr(data))
  97     self._buffer += data
  98     packets = slip_decode(self._buffer)
  99     self._buffer = packets.pop()
 100     for packet in packets:
 101       if not len(packet): continue
 102       (saddr, daddr) = packet_addrs(packet)
 103       route(packet, saddr, daddr)
 104   def processEnded(self, status):
 105     status.raiseException()
 106
 107 def start_ipif():
 108   global ipif
 109   ipif = IpifProcessProtocol()
 110   reactor.spawnProcess(ipif,
 111                        '/bin/sh',['sh','-xc', ipif_command],
 112                        childFDs={0:'w', 1:'r', 2:2})
 113
 114 def queue_inbound(packet):
 115   ipif.transport.write(slip_delimiter)
 116   ipif.transport.write(slip_encode(packet))
 117   ipif.transport.write(slip_delimiter)
 118
 119 #---------- SLIP handling ----------
 120
 121 slip_end = b'\300'
 122 slip_esc = b'\333'
 123 slip_esc_end = b'\334'
 124 slip_esc_esc = b'\335'
 125 slip_delimiter = slip_end
 126
 127 def slip_encode(packet):
 128   return (packet
 129           .replace(slip_esc, slip_esc + slip_esc_esc)
 130           .replace(slip_end, slip_esc + slip_esc_end))
 131
 132 def slip_decode(data):
 133   print('DECODE ', repr(data))
 134   out = []
 135   for packet in data.split(slip_end):
 136     pdata = b''
 137     while True:
 138       eix = packet.find(slip_esc)
 139       if eix == -1:
 140         pdata += packet
 141         break
 142       #print('ESC ', repr((pdata, packet, eix)))
 143       pdata += packet[0 : eix]
 144       ck = packet[eix+1]
 145       if   ck == slip_esc_esc: pdata += slip_esc
 146       elif ck == slip_esc_end: pdata += slip_end
 147       else: raise ValueError('invalid SLIP escape')
 148       packet = packet[eix+2 : ]
 149     out.append(pdata)
 150   print('DECODED ', repr(out))
 151   return out
 152
 153 #---------- packet parsing ----------
 154
 155 def packet_addrs(packet):
 156   version = packet[0] >> 4
 157   if version == 4:
 158     addrlen = 4
 159     saddroff = 3*4
 160     factory = ipaddress.IPv4Address
 161   elif version == 6:
 162     addrlen = 16
 163     saddroff = 2*4
 164     factory = ipaddress.IPv6Address
 165   else:
 166     raise ValueError('unsupported IP version %d' % version)
 167   saddr = factory(packet[ saddroff           : saddroff + addrlen   ])
 168   daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ])
 169   return (saddr, daddr)
 170
 171 #---------- client ----------
 172
 173 class Client():
 174   def __init__(self, ip, cs):
 175     # instance data members
 176     self._ip = ip
 177     self._cs = cs
 178     self.pw = cfg.get(cs, 'password')
 179     self._rq = collections.deque() # requests
 180     self._pq = collections.deque() # packets
 181     # plus from config:
 182     #  .max_batch_down
 183     #  .max_queue_time
 184     #  .max_request_time
 185     for k in ('max_batch_down','max_queue_time','max_request_time'):
 186       req = cfg.getint(cs, k)
 187       limit = cfg.getint('limits',k)
 188       self.__dict__[k] = min(req, limit)
 189
 190     def process_arriving_data(self, d):
 191       for packet in slip_decode(d):
 192         (saddr, daddr) = packet_addrs(packet)
 193         if saddr != self._ip:
 194           raise ValueError('wrong source address %s' % saddr)
 195         route(packet, saddr, daddr)
 196
 197     def _req_cancel(self, request):
 198       request.finish()
 199
 200     def _req_error(self, err, request):
 201       self._req_cancel(request)
 202
 203     def queue_outbound(self, packet):
 204       self._pq.append((time.monotonic(), packet))
 205
 206     def http_request(self, request):
 207       request.setHeader('Content-Type','application/octet-stream')
 208       reactor.callLater(self.max_request_time, self._req_cancel, request)
 209       request.notifyFinish().addErrback(self._req_error, request)
 210       self._rq.append(request)
 211       self._check_outbound()
 212
 213     def _check_outbound(self):
 214       while True:
 215         try: request = self._rq[0]
 216         except IndexError: request = None
 217         if request and request.finished:
 218           self._rq.popleft()
 219           continue
 220
 221         # now request is an unfinished request, or None
 222         try: (queuetime, packet) = self._pq[0]
 223         except IndexError:
 224           # no packets, oh well
 225           break
 226
 227         age = time.monotonic() - queuetime
 228         if age > self.max_queue_time:
 229           self._pq.popleft()
 230           continue
 231
 232         if request is None:
 233           # no request
 234           break
 235
 236         # request, and also some non-expired packets
 237         while True:
 238           try: (dummy, packet) = self._pq[0]
 239           except IndexError: break
 240
 241           encoded = slip_encode(packet)
 242
 243           if request.sentLength > 0:
 244             if (request.sentLength + len(slip_delimiter)
 245                 + len(encoded) > self.max_batch_down):
 246               break
 247             request.write(slip_delimiter)
 248
 249           request.write(encoded)
 250           self._pq.popLeft()
 251
 252         assert(request.sentLength)
 253         self._rq.popLeft()
 254         request.finish()
 255         # round again, looking for more to do
 256
 257 class IphttpResource(twisted.web.resource.Resource):
 258   def render_POST(self, request):
 259     # find client, update config, etc.
 260     ci = ipaddr(request.args['i'])
 261     c = clients[ci]
 262     pw = request.args['pw']
 263     if pw != c.pw: raise ValueError('bad password')
 264
 265     # update config
 266     for r, w in (('mbd', 'max_batch_down'),
 267                  ('mqt', 'max_queue_time'),
 268                  ('mrt', 'max_request_time')):
 269       try: v = request.args[r]
 270       except KeyError: continue
 271       v = int(v)
 272       c.__dict__[w] = v
 273
 274     try: d = request.args['d']
 275     except KeyError: d = ''
 276
 277     c.process_arriving_data(d)
 278     c.new_request(request)
 279
 280 def start_http():
 281   resource = IphttpResource()
 282   sitefactory = twisted.web.server.Site(resource)
 283   for addrspec in cfg.get('server','addrs').split():
 284     try:
 285       addr = ipaddress.IPv4Address(addrspec)
 286       endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 287     except AddressValueError:
 288       addr = ipaddress.IPv6Address(addrspec)
 289       endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 290     ep = endpointfactory(reactor, cfg.getint('server','port'), addr)
 291     defer = ep.listen(sitefactory)
 292     defer.addErrback(lambda err: err.raiseException())
 293
 294 #---------- config and setup ----------
 295
 296 def process_cfg():
 297   global network
 298   global host
 299   global relay
 300   global ipif_command
 301
 302   network = ipnetwork(cfg.get('virtual','network'))
 303   if network.num_addresses < 3 + 2:
 304     raise ValueError('network needs at least 2^3 addresses')
 305
 306   try:
 307     host = cfg.get('virtual','host')
 308   except NoOptionError:
 309     host = next(network.hosts())
 310
 311   try:
 312     relay = cfg.get('virtual','relay')
 313   except NoOptionError:
 314     for search in network.hosts():
 315       if search == host: continue
 316       relay = search
 317       break
 318
 319   for cs in cfg.sections():
 320     if not (':' in cs or '.' in cs): continue
 321     ci = ipaddr(cs)
 322     if ci not in network:
 323       raise ValueError('client %s not in network' % ci)
 324     if ci in clients:
 325       raise ValueError('multiple client cfg sections for %s' % ci)
 326     clients[ci] = Client(ci, cs)
 327
 328   global mtu
 329   mtu = cfg.get('virtual','mtu')
 330
 331   iic_vars = { }
 332   for k in ('host','relay','mtu','network'):
 333     iic_vars[k] = globals()[k]
 334
 335   ipif_command = cfg.get('server','ipif', vars=iic_vars)
 336
 337 def crash_on_critical(event):
 338   if event.get('log_level') >= LogLevel.critical:
 339     print('crashing: ', twisted.logger.formatEvent(event), file=sys.stderr)
 340     #print('crashing!', file=sys.stderr)
 341     #os._exit(1)
 342     try: reactor.stop()
 343     except twisted.internet.error.ReactorNotRunning: pass
 344
 345 def startup():
 346   global cfg
 347
 348   op = OptionParser()
 349   op.add_option('-c', '--config', dest='configfile',
 350                 default='/etc/hippottd/server.conf')
 351   global opts
 352   (opts, args) = op.parse_args()
 353   if len(args): op.error('no non-option arguments please')
 354
 355   twisted.logger.globalLogPublisher.addObserver(crash_on_critical)
 356
 357   cfg = ConfigParser()
 358   cfg.read_string(defcfg)
 359   cfg.read(opts.configfile)
 360   process_cfg()
 361
 362   start_ipif()
 363   start_http()
 364
 365 startup()
 366 reactor.run()