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 import twisted.internet.endpoints
  11 import twisted.logger
  12 from twisted.logger import LogLevel
  13 import twisted.python.constants
  14 from twisted.python.constants import NamedConstant
  15
  16 import ipaddress
  17 from ipaddress import AddressValueError
  18
  19 from optparse import OptionParser
  20 from configparser import ConfigParser
  21 from configparser import NoOptionError
  22
  23 import collections
  24 import time
  25 import codecs
  26 import traceback
  27
  28 import re as regexp
  29
  30 import hippotat.slip as slip
  31
  32 class DBG(twisted.python.constants.Names):
  33   ROUTE = NamedConstant()
  34   DROP = NamedConstant()
  35   FLOW = NamedConstant()
  36   HTTP = NamedConstant()
  37   HTTP_CTRL = NamedConstant()
  38   INIT = NamedConstant()
  39   QUEUE = NamedConstant()
  40   QUEUE_CTRL = NamedConstant()
  41   HTTP_FULL = NamedConstant()
  42
  43 _hex_codec = codecs.getencoder('hex_codec')
  44
  45 log = twisted.logger.Logger()
  46
  47 def log_debug(dflag, msg, idof=None, d=None):
  48   #print('---------------->',repr((dflag, msg, idof, d)), file=sys.stderr)
  49   if idof is not None:
  50     msg = '[%d] %s' % (id(idof), msg)
  51   if d is not None:
  52     #d = d[0:64]
  53     d = _hex_codec(d)[0].decode('ascii')
  54     msg += ' ' + d
  55   log.info('{dflag} {msgcore}', dflag=dflag, msgcore=msg)
  56
  57 defcfg = '''
  58 [DEFAULT]
  59 #[<client>] overrides
  60 max_batch_down = 65536           # used by server, subject to [limits]
  61 max_queue_time = 10              # used by server, subject to [limits]
  62 max_request_time = 54            # used by server, subject to [limits]
  63 target_requests_outstanding = 3  # must match; subject to [limits] on server
  64 max_requests_outstanding = 4     # used by client
  65 max_batch_up = 4000              # used by client
  66 http_timeout = 30                # used by client
  67 http_retry = 5                   # used by client
  68
  69 #[server] or [<client>] overrides
  70 ipif = userv root ipif %(local)s,%(peer)s,%(mtu)s,slip %(rnets)s
  71 # extra interpolations:  %(local)s        %(peer)s          %(rnet)s
  72 #  obtained   on server  [virtual]server  [virtual]relay    [virtual]network
  73 #      from   on client  <client>         [virtual]server   [virtual]routes
  74
  75 [virtual]
  76 mtu = 1500
  77 routes = ''
  78 # network = <prefix>/<len>  # mandatory for server
  79 # server  = <ipaddr>   # used by both, default is computed from `network'
  80 # relay   = <ipaddr>   # used by server, default from `network' and `server'
  81 #  default server is first host in network
  82 #  default relay is first host which is not server
  83
  84 [server]
  85 # addrs = 127.0.0.1 ::1    # mandatory for server
  86 port = 80                  # used by server
  87 # url              # used by client; default from first `addrs' and `port'
  88
  89 # [<client-ip4-or-ipv6-address>]
  90 # password = <password>    # used by both, must match
  91
  92 [limits]
  93 max_batch_down = 262144           # used by server
  94 max_queue_time = 121              # used by server
  95 max_request_time = 121            # used by server
  96 target_requests_outstanding = 10  # used by server
  97 '''
  98
  99 # these need to be defined here so that they can be imported by import *
 100 cfg = ConfigParser()
 101 optparser = OptionParser()
 102
 103 _mimetrans = bytes.maketrans(b'-'+slip.esc, slip.esc+b'-')
 104 def mime_translate(s):
 105   # SLIP-encoded packets cannot contain ESC ESC.
 106   # Swap `-' and ESC.  The result cannot contain `--'
 107   return s.translate(_mimetrans)
 108
 109 class ConfigResults:
 110   def __init__(self, d = { }):
 111     self.__dict__ = d
 112   def __repr__(self):
 113     return 'ConfigResults('+repr(self.__dict__)+')'
 114
 115 c = ConfigResults()
 116
 117 def log_discard(packet, iface, saddr, daddr, why):
 118   log_debug(DBG.DROP,
 119             'discarded packet [%s] %s -> %s: %s' % (iface, saddr, daddr, why),
 120             d=packet)
 121
 122 #---------- packet parsing ----------
 123
 124 def packet_addrs(packet):
 125   version = packet[0] >> 4
 126   if version == 4:
 127     addrlen = 4
 128     saddroff = 3*4
 129     factory = ipaddress.IPv4Address
 130   elif version == 6:
 131     addrlen = 16
 132     saddroff = 2*4
 133     factory = ipaddress.IPv6Address
 134   else:
 135     raise ValueError('unsupported IP version %d' % version)
 136   saddr = factory(packet[ saddroff           : saddroff + addrlen   ])
 137   daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ])
 138   return (saddr, daddr)
 139
 140 #---------- address handling ----------
 141
 142 def ipaddr(input):
 143   try:
 144     r = ipaddress.IPv4Address(input)
 145   except AddressValueError:
 146     r = ipaddress.IPv6Address(input)
 147   return r
 148
 149 def ipnetwork(input):
 150   try:
 151     r = ipaddress.IPv4Network(input)
 152   except NetworkValueError:
 153     r = ipaddress.IPv6Network(input)
 154   return r
 155
 156 #---------- ipif (SLIP) subprocess ----------
 157
 158 class SlipStreamDecoder():
 159   def __init__(self, on_packet):
 160     # we will call packet(<packet>)
 161     self._buffer = b''
 162     self._on_packet = on_packet
 163
 164   def inputdata(self, data):
 165     #print('SLIP-GOT ', repr(data))
 166     self._buffer += data
 167     packets = slip.decode(self._buffer)
 168     self._buffer = packets.pop()
 169     for packet in packets:
 170       self._maybe_packet(packet)
 171
 172   def _maybe_packet(self, packet):
 173       if len(packet):
 174         self._on_packet(packet)
 175
 176   def flush(self):
 177     self._maybe_packet(self._buffer)
 178     self._buffer = b''
 179
 180 class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
 181   def __init__(self, router):
 182     self._router = router
 183     self._decoder = SlipStreamDecoder(self.slip_on_packet)
 184   def connectionMade(self): pass
 185   def outReceived(self, data):
 186     self._decoder.inputdata(data)
 187   def slip_on_packet(self, packet):
 188     (saddr, daddr) = packet_addrs(packet)
 189     if saddr.is_link_local or daddr.is_link_local:
 190       log_discard(packet, 'ipif', saddr, daddr, 'link-local')
 191       return
 192     self._router(packet, saddr, daddr)
 193   def processEnded(self, status):
 194     status.raiseException()
 195
 196 def start_ipif(command, router):
 197   global ipif
 198   ipif = _IpifProcessProtocol(router)
 199   reactor.spawnProcess(ipif,
 200                        '/bin/sh',['sh','-xc', command],
 201                        childFDs={0:'w', 1:'r', 2:2},
 202                        env=None)
 203
 204 def queue_inbound(packet):
 205   log_debug(DBG.FLOW, "queue_inbound", d=packet)
 206   ipif.transport.write(slip.delimiter)
 207   ipif.transport.write(slip.encode(packet))
 208   ipif.transport.write(slip.delimiter)
 209
 210 #---------- packet queue ----------
 211
 212 class PacketQueue():
 213   def __init__(self, desc, max_queue_time):
 214     self._desc = desc
 215     assert(desc + '')
 216     self._max_queue_time = max_queue_time
 217     self._pq = collections.deque() # packets
 218
 219   def _log(self, dflag, msg, **kwargs):
 220     log_debug(dflag, self._desc+' pq: '+msg, **kwargs)
 221
 222   def append(self, packet):
 223     self._log(DBG.QUEUE, 'append', d=packet)
 224     self._pq.append((time.monotonic(), packet))
 225
 226   def nonempty(self):
 227     self._log(DBG.QUEUE, 'nonempty ?')
 228     while True:
 229       try: (queuetime, packet) = self._pq[0]
 230       except IndexError:
 231         self._log(DBG.QUEUE, 'nonempty ? empty.')
 232         return False
 233
 234       age = time.monotonic() - queuetime
 235       if age > self._max_queue_time:
 236         # strip old packets off the front
 237         self._log(DBG.QUEUE, 'dropping (old)', d=packet)
 238         self._pq.popleft()
 239         continue
 240
 241       self._log(DBG.QUEUE, 'nonempty ? nonempty.')
 242       return True
 243
 244   def process(self, sizequery, moredata, max_batch):
 245     # sizequery() should return size of batch so far
 246     # moredata(s) should add s to batch
 247     self._log(DBG.QUEUE, 'process...')
 248     while True:
 249       try: (dummy, packet) = self._pq[0]
 250       except IndexError:
 251         self._log(DBG.QUEUE, 'process... empty')
 252         break
 253
 254       self._log(DBG.QUEUE_CTRL, 'process... packet', d=packet)
 255
 256       encoded = slip.encode(packet)
 257       sofar = sizequery()
 258
 259       self._log(DBG.QUEUE_CTRL,
 260                 'process... (sofar=%d, max=%d) encoded' % (sofar, max_batch),
 261                 d=encoded)
 262
 263       if sofar > 0:
 264         if sofar + len(slip.delimiter) + len(encoded) > max_batch:
 265           self._log(DBG.QUEUE_CTRL, 'process... overflow')
 266           break
 267         moredata(slip.delimiter)
 268
 269       moredata(encoded)
 270       self._pq.popleft()
 271
 272 #---------- error handling ----------
 273
 274 _crashing = False
 275
 276 def crash(err):
 277   global _crashing
 278   _crashing = True
 279   print('CRASH ', err, file=sys.stderr)
 280   try: reactor.stop()
 281   except twisted.internet.error.ReactorNotRunning: pass
 282
 283 def crash_on_defer(defer):
 284   defer.addErrback(lambda err: crash(err))
 285
 286 def crash_on_critical(event):
 287   if event.get('log_level') >= LogLevel.critical:
 288     crash(twisted.logger.formatEvent(event))
 289
 290 #---------- config processing ----------
 291
 292 def process_cfg_common_always():
 293   global mtu
 294   c.mtu = cfg.get('virtual','mtu')
 295
 296 def process_cfg_ipif(section, varmap):
 297   for d, s in varmap:
 298     try: v = getattr(c, s)
 299     except AttributeError: continue
 300     setattr(c, d, v)
 301
 302   #print(repr(c))
 303
 304   c.ipif_command = cfg.get(section,'ipif', vars=c.__dict__)
 305
 306 def process_cfg_network():
 307   c.network = ipnetwork(cfg.get('virtual','network'))
 308   if c.network.num_addresses < 3 + 2:
 309     raise ValueError('network needs at least 2^3 addresses')
 310
 311 def process_cfg_server():
 312   try:
 313     c.server = cfg.get('virtual','server')
 314   except NoOptionError:
 315     process_cfg_network()
 316     c.server = next(c.network.hosts())
 317
 318 class ServerAddr():
 319   def __init__(self, port, addrspec):
 320     self.port = port
 321     # also self.addr
 322     try:
 323       self.addr = ipaddress.IPv4Address(addrspec)
 324       self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
 325       self._inurl = b'%s'
 326     except AddressValueError:
 327       self.addr = ipaddress.IPv6Address(addrspec)
 328       self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
 329       self._inurl = b'[%s]'
 330   def make_endpoint(self):
 331     return self._endpointfactory(reactor, self.port, self.addr)
 332   def url(self):
 333     url = b'http://' + (self._inurl % str(self.addr).encode('ascii'))
 334     if self.port != 80: url += b':%d' % self.port
 335     url += b'/'
 336     return url
 337
 338 def process_cfg_saddrs():
 339   try: port = cfg.getint('server','port')
 340   except NoOptionError: port = 80
 341
 342   c.saddrs = [ ]
 343   for addrspec in cfg.get('server','addrs').split():
 344     sa = ServerAddr(port, addrspec)
 345     c.saddrs.append(sa)
 346
 347 def process_cfg_clients(constructor):
 348   c.clients = [ ]
 349   for cs in cfg.sections():
 350     if not (':' in cs or '.' in cs): continue
 351     ci = ipaddr(cs)
 352     pw = cfg.get(cs, 'password')
 353     pw = pw.encode('utf-8')
 354     constructor(ci,cs,pw)
 355
 356 #---------- startup ----------
 357
 358 def common_startup():
 359   log_formatter = twisted.logger.formatEventAsClassicLogText
 360   log_observer = twisted.logger.FileLogObserver(sys.stderr, log_formatter)
 361   twisted.logger.globalLogBeginner.beginLoggingTo(
 362     [ log_observer, crash_on_critical ]
 363     )
 364
 365   optparser.add_option('-c', '--config', dest='configfile',
 366                        default='/etc/hippotat/config')
 367   (opts, args) = optparser.parse_args()
 368   if len(args): optparser.error('no non-option arguments please')
 369
 370   re = regexp.compile('#.*')
 371   cfg.read_string(re.sub('', defcfg))
 372   cfg.read(opts.configfile)
 373
 374 def common_run():
 375   log_debug(DBG.INIT, 'entering reactor')
 376   if not _crashing: reactor.run()
 377   print('CRASHED (end)', file=sys.stderr)