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