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 import time
  22
  23 import re as regexp
  24
  25 import hippotat.slip as slip
  26
  27 defcfg = '''
  28 [DEFAULT]
  29 #[<client>] overrides
  30 max_batch_down = 65536           # used by server, subject to [limits]
  31 max_queue_time = 10              # used by server, subject to [limits]
  32 max_request_time = 54            # used by server, subject to [limits]
  33 target_requests_outstanding = 3  # must match; subject to [limits] on server
  34 max_requests_outstanding = 4     # used by client
  35 max_batch_up = 4000              # used by client
  36 http_timeout = 30                # used by client
  37
  38 #[server] or [<client>] overrides
  39 ipif = userv root ipif %(local)s,%(peer)s,%(mtu)s,slip %(rnets)s
  40 # extra interpolations:  %(local)s        %(peer)s          %(rnet)s
  41 #  obtained   on server  [virtual]server  [virtual]relay    [virtual]network
  42 #      from   on client  <client>         [virtual]server   [virtual]routes
  43
  44 [virtual]
  45 mtu = 1500
  46 routes = ''
  47 # network = <prefix>/<len>  # mandatory for server
  48 # server  = <ipaddr>   # used by both, default is computed from `network'
  49 # relay   = <ipaddr>   # used by server, default from `network' and `server'
  50 #  default server is first host in network
  51 #  default relay is first host which is not server
  52
  53 [server]
  54 # addrs = 127.0.0.1 ::1    # mandatory for server
  55 port = 80                  # used by server
  56 # url              # used by client; default from first `addrs' and `port'
  57
  58 # [<client-ip4-or-ipv6-address>]
  59 # password = <password>    # used by both, must match
  60
  61 [limits]
  62 max_batch_down = 262144           # used by server
  63 max_queue_time = 121              # used by server
  64 max_request_time = 121            # used by server
  65 target_requests_outstanding = 10  # used by server
  66 '''
  67
  68 # these need to be defined here so that they can be imported by import *
  69 cfg = ConfigParser()
  70 optparser = OptionParser()
  71
  72 _mimetrans = bytes.maketrans(b'-'+slip.esc, slip.esc+b'-')
  73 def mime_translate(s):
  74   # SLIP-encoded packets cannot contain ESC ESC.
  75   # Swap `-' and ESC.  The result cannot contain `--'
  76   return s.translate(_mimetrans)
  77
  78 class ConfigResults:
  79   def __init__(self, d = { }):
  80     self.__dict__ = d
  81   def __repr__(self):
  82     return 'ConfigResults('+repr(self.__dict__)+')'
  83
  84 c = ConfigResults()
  85
  86 def log_discard(packet, saddr, daddr, why):
  87   print('DROP ', saddr, daddr, why)
  88 #  syslog.syslog(syslog.LOG_DEBUG,
  89 #                'discarded packet %s -> %s (%s)' % (saddr, daddr, why))
  90
  91 #---------- packet parsing ----------
  92
  93 def packet_addrs(packet):
  94   version = packet[0] >> 4
  95   if version == 4:
  96     addrlen = 4
  97     saddroff = 3*4
  98     factory = ipaddress.IPv4Address
  99   elif version == 6:
 100     addrlen = 16
 101     saddroff = 2*4
 102     factory = ipaddress.IPv6Address
 103   else:
 104     raise ValueError('unsupported IP version %d' % version)
 105   saddr = factory(packet[ saddroff           : saddroff + addrlen   ])
 106   daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ])
 107   return (saddr, daddr)
 108
 109 #---------- address handling ----------
 110
 111 def ipaddr(input):
 112   try:
 113     r = ipaddress.IPv4Address(input)
 114   except AddressValueError:
 115     r = ipaddress.IPv6Address(input)
 116   return r
 117
 118 def ipnetwork(input):
 119   try:
 120     r = ipaddress.IPv4Network(input)
 121   except NetworkValueError:
 122     r = ipaddress.IPv6Network(input)
 123   return r
 124
 125 #---------- ipif (SLIP) subprocess ----------
 126
 127 class SlipStreamDecoder():
 128   def __init__(self, on_packet):
 129     # we will call packet(<packet>)
 130     self._buffer = b''
 131     self._on_packet = on_packet
 132
 133   def inputdata(self, data):
 134     #print('SLIP-GOT ', repr(data))
 135     self._buffer += data
 136     packets = slip.decode(self._buffer)
 137     self._buffer = packets.pop()
 138     for packet in packets:
 139       self._maybe_packet(packet)
 140
 141   def _maybe_packet(self, packet):
 142       if len(packet):
 143         self._on_packet(packet)
 144
 145   def flush(self):
 146     self._maybe_packet(self._buffer)
 147     self._buffer = b''
 148
 149 class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
 150   def __init__(self, router):
 151     self._router = router
 152     self._decoder = SlipStreamDecoder(self.slip_on_packet)
 153   def connectionMade(self): pass
 154   def outReceived(self, data):
 155     self._decoder.inputdata(data)
 156   def slip_on_packet(self, packet):
 157     (saddr, daddr) = packet_addrs(packet)
 158     if saddr.is_link_local or daddr.is_link_local:
 159       log_discard(packet, saddr, daddr, 'link-local')
 160       return
 161     self._router(packet, saddr, daddr)
 162   def processEnded(self, status):
 163     status.raiseException()
 164
 165 def start_ipif(command, router):
 166   global ipif
 167   ipif = _IpifProcessProtocol(router)
 168   reactor.spawnProcess(ipif,
 169                        '/bin/sh',['sh','-xc', command],
 170                        childFDs={0:'w', 1:'r', 2:2},
 171                        env=None)
 172
 173 def queue_inbound(packet):
 174   ipif.transport.write(slip.delimiter)
 175   ipif.transport.write(slip.encode(packet))
 176   ipif.transport.write(slip.delimiter)
 177
 178 #---------- packet queue ----------
 179
 180 class PacketQueue():
 181   def __init__(self, max_queue_time):
 182     self._max_queue_time = max_queue_time
 183     self._pq = collections.deque() # packets
 184
 185   def append(self, packet):
 186     self._pq.append((time.monotonic(), packet))
 187
 188   def nonempty(self):
 189     while True:
 190       try: (queuetime, packet) = self._pq[0]
 191       except IndexError: return False
 192
 193       age = time.monotonic() - queuetime
 194       if age > self._max_queue_time:
 195         # strip old packets off the front
 196         self._pq.popleft()
 197         continue
 198
 199       return True
 200
 201   def process(self, sizequery, moredata, max_batch):
 202     # sizequery() should return size of batch so far
 203     # moredata(s) should add s to batch
 204     while True:
 205       try: (dummy, packet) = self._pq[0]
 206       except IndexError: break
 207
 208       encoded = slip.encode(packet)
 209       sofar = sizequery()
 210
 211       if sofar > 0:
 212         if sofar + len(slip.delimiter) + len(encoded) > max_batch:
 213           break
 214         moredata(slip.delimiter)
 215
 216       moredata(encoded)
 217       self._pq.popleft()
 218
 219 #---------- error handling ----------
 220
 221 def crash(err):
 222   print('CRASH ', err, file=sys.stderr)
 223   try: reactor.stop()
 224   except twisted.internet.error.ReactorNotRunning: pass
 225
 226 def crash_on_defer(defer):
 227   defer.addErrback(lambda err: crash(err))
 228
 229 def crash_on_critical(event):
 230   if event.get('log_level') >= LogLevel.critical:
 231     crash(twisted.logger.formatEvent(event))
 232
 233 #---------- config processing ----------
 234
 235 def process_cfg_common_always():
 236   global mtu
 237   c.mtu = cfg.get('virtual','mtu')
 238
 239 def process_cfg_ipif(section, varmap):
 240   for d, s in varmap:
 241     try: v = getattr(c, s)
 242     except AttributeError: continue
 243     setattr(c, d, v)
 244
 245   print(repr(c))
 246
 247   c.ipif_command = cfg.get(section,'ipif', vars=c.__dict__)
 248
 249 def process_cfg_network():
 250   c.network = ipnetwork(cfg.get('virtual','network'))
 251   if c.network.num_addresses < 3 + 2:
 252     raise ValueError('network needs at least 2^3 addresses')
 253
 254 def process_cfg_server():
 255   try:
 256     c.server = cfg.get('virtual','server')
 257   except NoOptionError:
 258     process_cfg_network()
 259     c.server = next(c.network.hosts())
 260
 261 class ServerAddr():
 262   def __init__(self, port, addrspec):
 263     self.port = port
 264     # also self.addr
 265     try:
 266       self.addr = ipaddress.IPv4Address(addrspec)
 267       self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 268       self._inurl = b'%s'
 269     except AddressValueError:
 270       self.addr = ipaddress.IPv6Address(addrspec)
 271       self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 272       self._inurl = b'[%s]'
 273   def make_endpoint(self):
 274     return self._endpointfactory(reactor, self.port, self.addr)
 275   def url(self):
 276     url = b'http://' + (self._inurl % str(self.addr).encode('ascii'))
 277     if self.port != 80: url += b':%d' % self.port
 278     url += b'/'
 279     return url
 280
 281 def process_cfg_saddrs():
 282   try: port = cfg.getint('server','port')
 283   except NoOptionError: port = 80
 284
 285   c.saddrs = [ ]
 286   for addrspec in cfg.get('server','addrs').split():
 287     sa = ServerAddr(port, addrspec)
 288     c.saddrs.append(sa)
 289
 290 def process_cfg_clients(constructor):
 291   c.clients = [ ]
 292   for cs in cfg.sections():
 293     if not (':' in cs or '.' in cs): continue
 294     ci = ipaddr(cs)
 295     pw = cfg.get(cs, 'password')
 296     pw = pw.encode('utf-8')
 297     constructor(ci,cs,pw)
 298
 299 #---------- startup ----------
 300
 301 def common_startup():
 302   twisted.logger.globalLogPublisher.addObserver(crash_on_critical)
 303
 304   optparser.add_option('-c', '--config', dest='configfile',
 305                        default='/etc/hippotat/config')
 306   (opts, args) = optparser.parse_args()
 307   if len(args): optparser.error('no non-option arguments please')
 308
 309   re = regexp.compile('#.*')
 310   cfg.read_string(re.sub('', defcfg))
 311   cfg.read(opts.configfile)
 312
 313 def common_run():
 314   reactor.run()
 315   print('CRASHED (end)', file=sys.stderr)