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 twisted
   7 from twisted.internet import reactor
   8 from twisted.logger import LogLevel
   9
  10 import ipaddress
  11 from ipaddress import AddressValueError
  12
  13 import hippotat.slip as slip
  14
  15 from optparse import OptionParser
  16 from configparser import ConfigParser
  17 from configparser import NoOptionError
  18
  19 import collections
  20
  21 # these need to be defined here so that they can be imported by import *
  22 cfg = ConfigParser()
  23 optparser = OptionParser()
  24
  25 class ConfigResults:
  26   def __init__(self, d = { }):
  27     self.__dict__ = d
  28   def __repr__(self):
  29     return 'ConfigResults('+repr(self.__dict__)+')'
  30
  31 c = ConfigResults()
  32
  33 #---------- packet parsing ----------
  34
  35 def packet_addrs(packet):
  36   version = packet[0] >> 4
  37   if version == 4:
  38     addrlen = 4
  39     saddroff = 3*4
  40     factory = ipaddress.IPv4Address
  41   elif version == 6:
  42     addrlen = 16
  43     saddroff = 2*4
  44     factory = ipaddress.IPv6Address
  45   else:
  46     raise ValueError('unsupported IP version %d' % version)
  47   saddr = factory(packet[ saddroff           : saddroff + addrlen   ])
  48   daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ])
  49   return (saddr, daddr)
  50
  51 #---------- address handling ----------
  52
  53 def ipaddr(input):
  54   try:
  55     r = ipaddress.IPv4Address(input)
  56   except AddressValueError:
  57     r = ipaddress.IPv6Address(input)
  58   return r
  59
  60 def ipnetwork(input):
  61   try:
  62     r = ipaddress.IPv4Network(input)
  63   except NetworkValueError:
  64     r = ipaddress.IPv6Network(input)
  65   return r
  66
  67 #---------- ipif (SLIP) subprocess ----------
  68
  69 class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
  70   def __init__(self, router):
  71     self._buffer = b''
  72     self._router = router
  73   def connectionMade(self): pass
  74   def outReceived(self, data):
  75     #print('RECV ', repr(data))
  76     self._buffer += data
  77     packets = slip.decode(self._buffer)
  78     self._buffer = packets.pop()
  79     for packet in packets:
  80       if not len(packet): continue
  81       (saddr, daddr) = packet_addrs(packet)
  82       self._router(packet, saddr, daddr)
  83   def processEnded(self, status):
  84     status.raiseException()
  85
  86 def start_ipif(command, router):
  87   global ipif
  88   ipif = _IpifProcessProtocol(router)
  89   reactor.spawnProcess(ipif,
  90                        '/bin/sh',['sh','-xc', command],
  91                        childFDs={0:'w', 1:'r', 2:2})
  92
  93 def queue_inbound(packet):
  94   ipif.transport.write(slip.delimiter)
  95   ipif.transport.write(slip.encode(packet))
  96   ipif.transport.write(slip.delimiter)
  97
  98 #---------- packet queue ----------
  99
 100 class PacketQueue():
 101   def __init__(self, max_queue_time):
 102     self._max_queue_time = max_queue_time
 103     self._pq = collections.deque() # packets
 104
 105   def append(self, packet):
 106     self._pq.append((time.monotonic(), packet))
 107
 108   def nonempty(self):
 109     while True:
 110       try: (queuetime, packet) = self._pq[0]
 111       except IndexError: return False
 112
 113       age = time.monotonic() - queuetime
 114       if age > self.max_queue_time:
 115         # strip old packets off the front
 116         self._pq.popleft()
 117         continue
 118
 119       return True
 120
 121   def popleft(self):
 122     # caller must have checked nonempty
 123     try: (dummy, packet) = self._pq[0]
 124     except IndexError: return None
 125     return packet
 126
 127 #---------- error handling ----------
 128
 129 def crash(err):
 130   print('CRASH ', err, file=sys.stderr)
 131   try: reactor.stop()
 132   except twisted.internet.error.ReactorNotRunning: pass
 133
 134 def crash_on_defer(defer):
 135   defer.addErrback(lambda err: crash(err))
 136
 137 def crash_on_critical(event):
 138   if event.get('log_level') >= LogLevel.critical:
 139     crash(twisted.logger.formatEvent(event))
 140
 141 #---------- config processing ----------
 142
 143 def process_cfg_common_always():
 144   global mtu
 145   c.mtu = cfg.get('virtual','mtu')
 146
 147 def process_cfg_ipif(section, varmap):
 148   for d, s in varmap:
 149     try: v = getattr(c, s)
 150     except KeyError: pass
 151     setattr(c, d, v)
 152
 153   print(repr(c))
 154
 155   c.ipif_command = cfg.get(section,'ipif', vars=c.__dict__)
 156
 157 def process_cfg_network():
 158   c.network = ipnetwork(cfg.get('virtual','network'))
 159   if c.network.num_addresses < 3 + 2:
 160     raise ValueError('network needs at least 2^3 addresses')
 161
 162 def process_cfg_server():
 163   try:
 164     c.server = cfg.get('virtual','server')
 165   except NoOptionError:
 166     process_cfg_network()
 167     c.server = next(c.network.hosts())
 168
 169 class ServerAddr():
 170   def __init__(self, port, addrspec):
 171     self.port = port
 172     # also self.addr
 173     try:
 174       self.addr = ipaddress.IPv4Address(addrspec)
 175       self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 176       self._inurl = '%s'
 177     except AddressValueError:
 178       self.addr = ipaddress.IPv6Address(addrspec)
 179       self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 180       self._inurl = '[%s]'
 181   def make_endpoint(self):
 182     return self._endpointfactory(reactor, self.port, self.addr)
 183   def url(self):
 184     url = 'http://' + (self._inurl % self.addr)
 185     if self.port != 80: url += ':%d' % self.port
 186     url += '/'
 187     return url
 188
 189 def process_cfg_saddrs():
 190   port = cfg.getint('server','port')
 191
 192   c.saddrs = [ ]
 193   for addrspec in cfg.get('server','addrs').split():
 194     sa = ServerAddr(port, addrspec)
 195     c.saddrs.append(sa)
 196
 197 def process_cfg_clients(constructor):
 198   c.clients = [ ]
 199   for cs in cfg.sections():
 200     if not (':' in cs or '.' in cs): continue
 201     ci = ipaddr(cs)
 202     pw = cfg.get(cs, 'password')
 203     constructor(ci,cs,pw)
 204
 205 #---------- startup ----------
 206
 207 def common_startup(defcfg):
 208   twisted.logger.globalLogPublisher.addObserver(crash_on_critical)
 209
 210   optparser.add_option('-c', '--config', dest='configfile',
 211                        default='/etc/hippotat/config')
 212   (opts, args) = optparser.parse_args()
 213   if len(args): optparser.error('no non-option arguments please')
 214
 215   cfg.read_string(defcfg)
 216   cfg.read(opts.configfile)
 217
 218 def common_run():
 219   reactor.run()
 220   print('CRASHED (end)', file=sys.stderr)