wip, config reorg

[hippotat] / hippotat / __init__.py

# -*- python -*-

import signal
signal.signal(signal.SIGINT, signal.SIG_DFL)

import twisted
from twisted.internet import reactor
from twisted.logger import LogLevel

import ipaddress
from ipaddress import AddressValueError

import hippotat.slip as slip

from optparse import OptionParser
from configparser import ConfigParser
from configparser import NoOptionError

import collections

# these need to be defined here so that they can be imported by import *
cfg = ConfigParser()
optparser = OptionParser()

class ConfigResults:
  def __init__(self, d = { }):
    self.__dict__ = d
  def __repr__(self):
    return 'ConfigResults('+repr(self.__dict__)+')'

c = ConfigResults()

#---------- packet parsing ----------

def packet_addrs(packet):
  version = packet[0] >> 4
  if version == 4:
    addrlen = 4
    saddroff = 3*4
    factory = ipaddress.IPv4Address
  elif version == 6:
    addrlen = 16
    saddroff = 2*4
    factory = ipaddress.IPv6Address
  else:
    raise ValueError('unsupported IP version %d' % version)
  saddr = factory(packet[ saddroff           : saddroff + addrlen   ])
  daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ])
  return (saddr, daddr)

#---------- address handling ----------

def ipaddr(input):
  try:
    r = ipaddress.IPv4Address(input)
  except AddressValueError:
    r = ipaddress.IPv6Address(input)
  return r

def ipnetwork(input):
  try:
    r = ipaddress.IPv4Network(input)
  except NetworkValueError:
    r = ipaddress.IPv6Network(input)
  return r

#---------- ipif (SLIP) subprocess ----------

class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol):
  def __init__(self, router):
    self._buffer = b''
    self._router = router
  def connectionMade(self): pass
  def outReceived(self, data):
    #print('RECV ', repr(data))
    self._buffer += data
    packets = slip.decode(self._buffer)
    self._buffer = packets.pop()
    for packet in packets:
      if not len(packet): continue
      (saddr, daddr) = packet_addrs(packet)
      self._router(packet, saddr, daddr)
  def processEnded(self, status):
    status.raiseException()

def start_ipif(command, router):
  global ipif
  ipif = _IpifProcessProtocol(router)
  reactor.spawnProcess(ipif,
                       '/bin/sh',['sh','-xc', command],
                       childFDs={0:'w', 1:'r', 2:2})

def queue_inbound(packet):
  ipif.transport.write(slip.delimiter)
  ipif.transport.write(slip.encode(packet))
  ipif.transport.write(slip.delimiter)

#---------- packet queue ----------

class PacketQueue():
  def __init__(self, max_queue_time):
    self._max_queue_time = max_queue_time
    self._pq = collections.deque() # packets

  def append(self, packet):
    self._pq.append((time.monotonic(), packet))

  def nonempty(self):
    while True:
      try: (queuetime, packet) = self._pq[0]
      except IndexError: return False

      age = time.monotonic() - queuetime
      if age > self.max_queue_time:
        # strip old packets off the front
        self._pq.popleft()
        continue

      return True

  def popleft(self):
    # caller must have checked nonempty
    try: (dummy, packet) = self._pq[0]
    except IndexError: return None
    return packet

#---------- error handling ----------

def crash(err):
  print('CRASH ', err, file=sys.stderr)
  try: reactor.stop()
  except twisted.internet.error.ReactorNotRunning: pass

def crash_on_defer(defer):
  defer.addErrback(lambda err: crash(err))

def crash_on_critical(event):
  if event.get('log_level') >= LogLevel.critical:
    crash(twisted.logger.formatEvent(event))

#---------- config processing ----------

def process_cfg_common_always():
  global mtu
  c.mtu = cfg.get('virtual','mtu')

def process_cfg_ipif(section, varmap):
  for d, s in varmap:
    try: v = getattr(c, s)
    except KeyError: pass
    setattr(c, d, v)

  print(repr(c))

  c.ipif_command = cfg.get(section,'ipif', vars=c.__dict__)

def process_cfg_network():
  c.network = ipnetwork(cfg.get('virtual','network'))
  if c.network.num_addresses < 3 + 2:
    raise ValueError('network needs at least 2^3 addresses')

def process_cfg_server():
  try:
    c.server = cfg.get('virtual','server')
  except NoOptionError:
    process_cfg_network()
    c.server = next(c.network.hosts())

class ServerAddr():
  def __init__(self, port, addrspec):
    self.port = port
    # also self.addr
    try:
      self.addr = ipaddress.IPv4Address(addrspec)
      self._endpointfactory = twisted.internet.endpoints.TCP4ServerEndpoint
      self._inurl = '%s'
    except AddressValueError:
      self.addr = ipaddress.IPv6Address(addrspec)
      self._endpointfactory = twisted.internet.endpoints.TCP6ServerEndpoint
      self._inurl = '[%s]'
  def make_endpoint(self):
    return self._endpointfactory(reactor, self.port, self.addr)
  def url(self):
    url = 'http://' + (self._inurl % self.addr)
    if self.port != 80: url += ':%d' % self.port
    url += '/'
    return url
    
def process_cfg_saddrs():
  port = cfg.getint('server','port')

  c.saddrs = [ ]
  for addrspec in cfg.get('server','addrs').split():
    sa = ServerAddr(port, addrspec)
    c.saddrs.append(sa)

def process_cfg_clients(constructor):
  c.clients = [ ]
  for cs in cfg.sections():
    if not (':' in cs or '.' in cs): continue
    ci = ipaddr(cs)
    pw = cfg.get(cs, 'password')
    constructor(ci,cs,pw)

#---------- startup ----------

def common_startup(defcfg):
  twisted.logger.globalLogPublisher.addObserver(crash_on_critical)

  optparser.add_option('-c', '--config', dest='configfile',
                       default='/etc/hippotat/config')
  (opts, args) = optparser.parse_args()
  if len(args): optparser.error('no non-option arguments please')

  cfg.read_string(defcfg)
  cfg.read(opts.configfile)

def common_run():
  reactor.run()
  print('CRASHED (end)', file=sys.stderr)