src/allmydata/immutable/filenode.py

   1
   2 import binascii
   3 import copy
   4 import time
   5 now = time.time
   6 from zope.interface import implements
   7 from twisted.internet import defer
   8
   9 from allmydata import uri
  10 from twisted.internet.interfaces import IConsumer
  11 from allmydata.interfaces import IImmutableFileNode, IUploadResults
  12 from allmydata.util import consumer
  13 from allmydata.check_results import CheckResults, CheckAndRepairResults
  14 from allmydata.util.dictutil import DictOfSets
  15 from pycryptopp.cipher.aes import AES
  16
  17 # local imports
  18 from allmydata.immutable.checker import Checker
  19 from allmydata.immutable.repairer import Repairer
  20 from allmydata.immutable.downloader.node import DownloadNode, \
  21      IDownloadStatusHandlingConsumer
  22 from allmydata.immutable.downloader.status import DownloadStatus
  23
  24 class CiphertextFileNode:
  25     def __init__(self, verifycap, storage_broker, secret_holder,
  26                  terminator, history):
  27         assert isinstance(verifycap, uri.CHKFileVerifierURI)
  28         self._verifycap = verifycap
  29         self._storage_broker = storage_broker
  30         self._secret_holder = secret_holder
  31         self._terminator = terminator
  32         self._history = history
  33         self._download_status = None
  34         self._node = None # created lazily, on read()
  35
  36     def _maybe_create_download_node(self):
  37         if not self._download_status:
  38             ds = DownloadStatus(self._verifycap.storage_index,
  39                                 self._verifycap.size)
  40             if self._history:
  41                 self._history.add_download(ds)
  42             self._download_status = ds
  43         if self._node is None:
  44             self._node = DownloadNode(self._verifycap, self._storage_broker,
  45                                       self._secret_holder,
  46                                       self._terminator,
  47                                       self._history, self._download_status)
  48
  49     def read(self, consumer, offset=0, size=None):
  50         """I am the main entry point, from which FileNode.read() can get
  51         data. I feed the consumer with the desired range of ciphertext. I
  52         return a Deferred that fires (with the consumer) when the read is
  53         finished."""
  54         self._maybe_create_download_node()
  55         return self._node.read(consumer, offset, size)
  56
  57     def get_segment(self, segnum):
  58         """Begin downloading a segment. I return a tuple (d, c): 'd' is a
  59         Deferred that fires with (offset,data) when the desired segment is
  60         available, and c is an object on which c.cancel() can be called to
  61         disavow interest in the segment (after which 'd' will never fire).
  62
  63         You probably need to know the segment size before calling this,
  64         unless you want the first few bytes of the file. If you ask for a
  65         segment number which turns out to be too large, the Deferred will
  66         errback with BadSegmentNumberError.
  67
  68         The Deferred fires with the offset of the first byte of the data
  69         segment, so that you can call get_segment() before knowing the
  70         segment size, and still know which data you received.
  71         """
  72         self._maybe_create_download_node()
  73         return self._node.get_segment(segnum)
  74
  75     def get_segment_size(self):
  76         # return a Deferred that fires with the file's real segment size
  77         self._maybe_create_download_node()
  78         return self._node.get_segsize()
  79
  80     def get_storage_index(self):
  81         return self._verifycap.storage_index
  82     def get_verify_cap(self):
  83         return self._verifycap
  84     def get_size(self):
  85         return self._verifycap.size
  86
  87     def raise_error(self):
  88         pass
  89
  90
  91     def check_and_repair(self, monitor, verify=False, add_lease=False):
  92         verifycap = self._verifycap
  93         storage_index = verifycap.storage_index
  94         sb = self._storage_broker
  95         servers = sb.get_connected_servers()
  96         sh = self._secret_holder
  97
  98         c = Checker(verifycap=verifycap, servers=servers,
  99                     verify=verify, add_lease=add_lease, secret_holder=sh,
 100                     monitor=monitor)
 101         d = c.start()
 102         def _maybe_repair(cr):
 103             crr = CheckAndRepairResults(storage_index)
 104             crr.pre_repair_results = cr
 105             if cr.is_healthy():
 106                 crr.post_repair_results = cr
 107                 return defer.succeed(crr)
 108             else:
 109                 crr.repair_attempted = True
 110                 crr.repair_successful = False # until proven successful
 111                 def _gather_repair_results(ur):
 112                     assert IUploadResults.providedBy(ur), ur
 113                     # clone the cr (check results) to form the basis of the
 114                     # prr (post-repair results)
 115                     prr = CheckResults(cr.uri, cr.storage_index)
 116                     prr.data = copy.deepcopy(cr.data)
 117
 118                     sm = prr.data['sharemap']
 119                     assert isinstance(sm, DictOfSets), sm
 120                     sm.update(ur.sharemap)
 121                     servers_responding = set(prr.data['servers-responding'])
 122                     servers_responding.union(ur.sharemap.iterkeys())
 123                     prr.data['servers-responding'] = list(servers_responding)
 124                     prr.data['count-shares-good'] = len(sm)
 125                     prr.data['count-good-share-hosts'] = len(sm)
 126                     is_healthy = bool(len(sm) >= verifycap.total_shares)
 127                     is_recoverable = bool(len(sm) >= verifycap.needed_shares)
 128                     prr.set_healthy(is_healthy)
 129                     prr.set_recoverable(is_recoverable)
 130                     crr.repair_successful = is_healthy
 131                     prr.set_needs_rebalancing(len(sm) >= verifycap.total_shares)
 132
 133                     crr.post_repair_results = prr
 134                     return crr
 135                 def _repair_error(f):
 136                     # as with mutable repair, I'm not sure if I want to pass
 137                     # through a failure or not. TODO
 138                     crr.repair_successful = False
 139                     crr.repair_failure = f
 140                     return f
 141                 r = Repairer(self, storage_broker=sb, secret_holder=sh,
 142                              monitor=monitor)
 143                 d = r.start()
 144                 d.addCallbacks(_gather_repair_results, _repair_error)
 145                 return d
 146
 147         d.addCallback(_maybe_repair)
 148         return d
 149
 150     def check(self, monitor, verify=False, add_lease=False):
 151         verifycap = self._verifycap
 152         sb = self._storage_broker
 153         servers = sb.get_connected_servers()
 154         sh = self._secret_holder
 155
 156         v = Checker(verifycap=verifycap, servers=servers,
 157                     verify=verify, add_lease=add_lease, secret_holder=sh,
 158                     monitor=monitor)
 159         return v.start()
 160
 161 class DecryptingConsumer:
 162     """I sit between a CiphertextDownloader (which acts as a Producer) and
 163     the real Consumer, decrypting everything that passes by. The real
 164     Consumer sees the real Producer, but the Producer sees us instead of the
 165     real consumer."""
 166     implements(IConsumer, IDownloadStatusHandlingConsumer)
 167
 168     def __init__(self, consumer, readkey, offset):
 169         self._consumer = consumer
 170         self._read_ev = None
 171         # TODO: pycryptopp CTR-mode needs random-access operations: I want
 172         # either a=AES(readkey, offset) or better yet both of:
 173         #  a=AES(readkey, offset=0)
 174         #  a.process(ciphertext, offset=xyz)
 175         # For now, we fake it with the existing iv= argument.
 176         offset_big = offset // 16
 177         offset_small = offset % 16
 178         iv = binascii.unhexlify("%032x" % offset_big)
 179         self._decryptor = AES(readkey, iv=iv)
 180         self._decryptor.process("\x00"*offset_small)
 181
 182     def set_download_status_read_event(self, read_ev):
 183         self._read_ev = read_ev
 184
 185     def registerProducer(self, producer, streaming):
 186         # this passes through, so the real consumer can flow-control the real
 187         # producer. Therefore we don't need to provide any IPushProducer
 188         # methods. We implement all the IConsumer methods as pass-throughs,
 189         # and only intercept write() to perform decryption.
 190         self._consumer.registerProducer(producer, streaming)
 191     def unregisterProducer(self):
 192         self._consumer.unregisterProducer()
 193     def write(self, ciphertext):
 194         started = now()
 195         plaintext = self._decryptor.process(ciphertext)
 196         if self._read_ev:
 197             elapsed = now() - started
 198             self._read_ev.update(0, elapsed, 0)
 199         self._consumer.write(plaintext)
 200
 201 class ImmutableFileNode:
 202     implements(IImmutableFileNode)
 203
 204     # I wrap a CiphertextFileNode with a decryption key
 205     def __init__(self, filecap, storage_broker, secret_holder, terminator,
 206                  history):
 207         assert isinstance(filecap, uri.CHKFileURI)
 208         verifycap = filecap.get_verify_cap()
 209         self._cnode = CiphertextFileNode(verifycap, storage_broker,
 210                                          secret_holder, terminator, history)
 211         assert isinstance(filecap, uri.CHKFileURI)
 212         self.u = filecap
 213         self._readkey = filecap.key
 214
 215     # TODO: I'm not sure about this.. what's the use case for node==node? If
 216     # we keep it here, we should also put this on CiphertextFileNode
 217     def __hash__(self):
 218         return self.u.__hash__()
 219     def __eq__(self, other):
 220         if isinstance(other, ImmutableFileNode):
 221             return self.u.__eq__(other.u)
 222         else:
 223             return False
 224     def __ne__(self, other):
 225         if isinstance(other, ImmutableFileNode):
 226             return self.u.__eq__(other.u)
 227         else:
 228             return True
 229
 230     def read(self, consumer, offset=0, size=None):
 231         decryptor = DecryptingConsumer(consumer, self._readkey, offset)
 232         d = self._cnode.read(decryptor, offset, size)
 233         d.addCallback(lambda dc: consumer)
 234         return d
 235
 236     def raise_error(self):
 237         pass
 238
 239     def get_write_uri(self):
 240         return None
 241
 242     def get_readonly_uri(self):
 243         return self.get_uri()
 244
 245     def get_uri(self):
 246         return self.u.to_string()
 247     def get_cap(self):
 248         return self.u
 249     def get_readcap(self):
 250         return self.u.get_readonly()
 251     def get_verify_cap(self):
 252         return self.u.get_verify_cap()
 253     def get_repair_cap(self):
 254         # CHK files can be repaired with just the verifycap
 255         return self.u.get_verify_cap()
 256
 257     def get_storage_index(self):
 258         return self.u.get_storage_index()
 259
 260     def get_size(self):
 261         return self.u.get_size()
 262     def get_current_size(self):
 263         return defer.succeed(self.get_size())
 264
 265     def is_mutable(self):
 266         return False
 267
 268     def is_readonly(self):
 269         return True
 270
 271     def is_unknown(self):
 272         return False
 273
 274     def is_allowed_in_immutable_directory(self):
 275         return True
 276
 277     def check_and_repair(self, monitor, verify=False, add_lease=False):
 278         return self._cnode.check_and_repair(monitor, verify, add_lease)
 279     def check(self, monitor, verify=False, add_lease=False):
 280         return self._cnode.check(monitor, verify, add_lease)
 281
 282     def get_best_readable_version(self):
 283         """
 284         Return an IReadable of the best version of this file. Since
 285         immutable files can have only one version, we just return the
 286         current filenode.
 287         """
 288         return defer.succeed(self)
 289
 290
 291     def download_best_version(self):
 292         """
 293         Download the best version of this file, returning its contents
 294         as a bytestring. Since there is only one version of an immutable
 295         file, we download and return the contents of this file.
 296         """
 297         d = consumer.download_to_data(self)
 298         return d
 299
 300     # for an immutable file, download_to_data (specified in IReadable)
 301     # is the same as download_best_version (specified in IFileNode). For
 302     # mutable files, the difference is more meaningful, since they can
 303     # have multiple versions.
 304     download_to_data = download_best_version
 305
 306
 307     # get_size() (IReadable), get_current_size() (IFilesystemNode), and
 308     # get_size_of_best_version(IFileNode) are all the same for immutable
 309     # files.
 310     get_size_of_best_version = get_current_size