src/allmydata/key_generator.py

   1
   2 import os
   3 import time
   4
   5 import foolscap
   6 from zope.interface import implements
   7 from twisted.internet import reactor
   8 from twisted.application import service
   9 from twisted.python import log
  10
  11 from pycryptopp.publickey import rsa
  12 from allmydata.interfaces import RIKeyGenerator
  13
  14 class KeyGenerator(service.MultiService, foolscap.Referenceable):
  15     implements(RIKeyGenerator)
  16
  17     DEFAULT_KEY_SIZE = 2048
  18     pool_size = 16 # no. keys to keep on hand in the pool
  19     pool_refresh_delay = 6 # no. sec to wait after a fetch before generating new keys
  20     verbose = False
  21
  22     def __init__(self):
  23         service.MultiService.__init__(self)
  24         self.keypool = []
  25         self.last_fetch = 0
  26
  27     def startService(self):
  28         self.timer = reactor.callLater(0, self.maybe_refill_pool)
  29         return service.MultiService.startService(self)
  30
  31     def stopService(self):
  32         if self.timer.active():
  33             self.timer.cancel()
  34         return service.MultiService.stopService(self)
  35
  36     def __repr__(self):
  37         return '<KeyGenerator[%s]>' % (len(self.keypool),)
  38
  39     def vlog(self, msg):
  40         if self.verbose:
  41             log.msg(msg)
  42
  43     def reset_timer(self):
  44         self.last_fetch = time.time()
  45         if self.timer.active():
  46             self.timer.reset(self.pool_refresh_delay)
  47         else:
  48             self.timer = reactor.callLater(self.pool_refresh_delay, self.maybe_refill_pool)
  49
  50     def maybe_refill_pool(self):
  51         now = time.time()
  52         if self.last_fetch + self.pool_refresh_delay < now:
  53             self.vlog('%s refilling pool' % (self,))
  54             while len(self.keypool) < self.pool_size:
  55                 self.keypool.append(self.gen_key(self.DEFAULT_KEY_SIZE))
  56         else:
  57             self.vlog('%s not refilling pool' % (self,))
  58
  59     def gen_key(self, key_size):
  60         self.vlog('%s generating key size %s' % (self, key_size, ))
  61         signer = rsa.generate(key_size)
  62         verifier = signer.get_verifying_key()
  63         return verifier.serialize(), signer.serialize()
  64
  65     def remote_get_rsa_key_pair(self, key_size):
  66         self.vlog('%s remote_get_key' % (self,))
  67         if key_size != self.DEFAULT_KEY_SIZE or not self.keypool:
  68             self.reset_timer()
  69             return self.gen_key(key_size)
  70         else:
  71             self.reset_timer()
  72             return self.keypool.pop()
  73
  74 class KeyGeneratorService(service.MultiService):
  75     furl_file = 'key_generator.furl'
  76
  77     def __init__(self, basedir='.', display_furl=True):
  78         service.MultiService.__init__(self)
  79         self.basedir = basedir
  80         self.tub = foolscap.Tub(certFile=os.path.join(self.basedir, 'key_generator.pem'))
  81         self.tub.setServiceParent(self)
  82         self.key_generator = KeyGenerator()
  83         self.key_generator.setServiceParent(self)
  84
  85         portnum = self.get_portnum()
  86         self.listener = self.tub.listenOn(portnum or 'tcp:0')
  87         d = self.tub.setLocationAutomatically()
  88         if portnum is None:
  89             d.addCallback(self.save_portnum)
  90         d.addCallback(self.tub_ready, display_furl)
  91         d.addErrback(log.err)
  92
  93     def get_portnum(self):
  94         portnumfile = os.path.join(self.basedir, 'portnum')
  95         if os.path.exists(portnumfile):
  96             return file(portnumfile, 'rb').read().strip()
  97
  98     def save_portnum(self, junk):
  99         portnum = self.listener.getPortnum()
 100         portnumfile = os.path.join(self.basedir, 'portnum')
 101         file(portnumfile, 'wb').write('%d\n' % (portnum,))
 102
 103     def tub_ready(self, junk, display_furl):
 104         kgf = os.path.join(self.basedir, self.furl_file)
 105         self.keygen_furl = self.tub.registerReference(self.key_generator, furlFile=kgf)
 106         if display_furl:
 107             print 'key generator at:', self.keygen_furl