3 from itertools import count
4 from zope.interface import implements
5 from twisted.internet import defer
6 from twisted.python import failure
7 from twisted.internet.interfaces import IPushProducer, IConsumer
8 from foolscap.api import eventually, fireEventually
9 from allmydata.interfaces import IRetrieveStatus, NotEnoughSharesError, \
10 MDMF_VERSION, SDMF_VERSION
11 from allmydata.util import hashutil, log, mathutil
12 from allmydata.util.dictutil import DictOfSets
13 from allmydata import hashtree, codec
14 from allmydata.storage.server import si_b2a
15 from pycryptopp.cipher.aes import AES
16 from pycryptopp.publickey import rsa
18 from allmydata.mutable.common import CorruptShareError, UncoordinatedWriteError
19 from allmydata.mutable.layout import MDMFSlotReadProxy
22 implements(IRetrieveStatus)
23 statusid_counter = count(0)
26 self.timings["fetch_per_server"] = {}
27 self.timings["cumulative_verify"] = 0.0
30 self.storage_index = None
32 self.encoding = ("?","?")
34 self.status = "Not started"
36 self.counter = self.statusid_counter.next()
37 self.started = time.time()
39 def get_started(self):
41 def get_storage_index(self):
42 return self.storage_index
43 def get_encoding(self):
45 def using_helper(self):
51 def get_progress(self):
55 def get_counter(self):
58 def add_fetch_timing(self, peerid, elapsed):
59 if peerid not in self.timings["fetch_per_server"]:
60 self.timings["fetch_per_server"][peerid] = []
61 self.timings["fetch_per_server"][peerid].append(elapsed)
62 def set_storage_index(self, si):
63 self.storage_index = si
64 def set_helper(self, helper):
66 def set_encoding(self, k, n):
67 self.encoding = (k, n)
68 def set_size(self, size):
70 def set_status(self, status):
72 def set_progress(self, value):
74 def set_active(self, value):
81 # this class is currently single-use. Eventually (in MDMF) we will make
82 # it multi-use, in which case you can call download(range) multiple
83 # times, and each will have a separate response chain. However the
84 # Retrieve object will remain tied to a specific version of the file, and
85 # will use a single ServerMap instance.
86 implements(IPushProducer)
88 def __init__(self, filenode, servermap, verinfo, fetch_privkey=False,
91 assert self._node.get_pubkey()
92 self._storage_index = filenode.get_storage_index()
93 assert self._node.get_readkey()
94 self._last_failure = None
95 prefix = si_b2a(self._storage_index)[:5]
96 self._log_number = log.msg("Retrieve(%s): starting" % prefix)
97 self._outstanding_queries = {} # maps (peerid,shnum) to start_time
99 self._decoding = False
100 self._bad_shares = set()
102 self.servermap = servermap
103 assert self._node.get_pubkey()
104 self.verinfo = verinfo
105 # during repair, we may be called upon to grab the private key, since
106 # it wasn't picked up during a verify=False checker run, and we'll
107 # need it for repair to generate a new version.
108 self._need_privkey = verify or (fetch_privkey
109 and not self._node.get_privkey())
111 if self._need_privkey:
112 # TODO: Evaluate the need for this. We'll use it if we want
113 # to limit how many queries are on the wire for the privkey
115 self._privkey_query_markers = [] # one Marker for each time we've
116 # tried to get the privkey.
118 # verify means that we are using the downloader logic to verify all
119 # of our shares. This tells the downloader a few things.
121 # 1. We need to download all of the shares.
122 # 2. We don't need to decode or decrypt the shares, since our
123 # caller doesn't care about the plaintext, only the
124 # information about which shares are or are not valid.
125 # 3. When we are validating readers, we need to validate the
126 # signature on the prefix. Do we? We already do this in the
128 self._verify = verify
130 self._status = RetrieveStatus()
131 self._status.set_storage_index(self._storage_index)
132 self._status.set_helper(False)
133 self._status.set_progress(0.0)
134 self._status.set_active(True)
135 (seqnum, root_hash, IV, segsize, datalength, k, N, prefix,
136 offsets_tuple) = self.verinfo
137 self._status.set_size(datalength)
138 self._status.set_encoding(k, N)
140 self._pause_deferred = None
142 self._read_length = None
143 self.log("got seqnum %d" % self.verinfo[0])
146 def get_status(self):
149 def log(self, *args, **kwargs):
150 if "parent" not in kwargs:
151 kwargs["parent"] = self._log_number
152 if "facility" not in kwargs:
153 kwargs["facility"] = "tahoe.mutable.retrieve"
154 return log.msg(*args, **kwargs)
160 def pauseProducing(self):
162 I am called by my download target if we have produced too much
163 data for it to handle. I make the downloader stop producing new
164 data until my resumeProducing method is called.
166 if self._pause_deferred is not None:
169 # fired when the download is unpaused.
170 self._old_status = self._status.get_status()
171 self._status.set_status("Paused")
173 self._pause_deferred = defer.Deferred()
176 def resumeProducing(self):
178 I am called by my download target once it is ready to begin
179 receiving data again.
181 if self._pause_deferred is None:
184 p = self._pause_deferred
185 self._pause_deferred = None
186 self._status.set_status(self._old_status)
188 eventually(p.callback, None)
191 def _check_for_paused(self, res):
193 I am called just before a write to the consumer. I return a
194 Deferred that eventually fires with the data that is to be
195 written to the consumer. If the download has not been paused,
196 the Deferred fires immediately. Otherwise, the Deferred fires
197 when the downloader is unpaused.
199 if self._pause_deferred is not None:
201 self._pause_deferred.addCallback(lambda ignored: d.callback(res))
203 return defer.succeed(res)
206 def download(self, consumer=None, offset=0, size=None):
207 assert IConsumer.providedBy(consumer) or self._verify
210 self._consumer = consumer
211 # we provide IPushProducer, so streaming=True, per
213 self._consumer.registerProducer(self, streaming=True)
215 self._done_deferred = defer.Deferred()
216 self._started = time.time()
217 self._status.set_status("Retrieving Shares")
219 self._offset = offset
220 self._read_length = size
222 # first, which servers can we use?
223 versionmap = self.servermap.make_versionmap()
224 shares = versionmap[self.verinfo]
225 # this sharemap is consumed as we decide to send requests
226 self.remaining_sharemap = DictOfSets()
227 for (shnum, peerid, timestamp) in shares:
228 self.remaining_sharemap.add(shnum, peerid)
229 # If the servermap update fetched anything, it fetched at least 1
230 # KiB, so we ask for that much.
231 # TODO: Change the cache methods to allow us to fetch all of the
232 # data that they have, then change this method to do that.
233 any_cache = self._node._read_from_cache(self.verinfo, shnum,
235 ss = self.servermap.connections[peerid]
236 reader = MDMFSlotReadProxy(ss,
240 reader.peerid = peerid
241 self.readers[shnum] = reader
244 self.shares = {} # maps shnum to validated blocks
245 self._active_readers = [] # list of active readers for this dl.
246 self._validated_readers = set() # set of readers that we have
247 # validated the prefix of
248 self._block_hash_trees = {} # shnum => hashtree
250 # how many shares do we need?
259 offsets_tuple) = self.verinfo
262 # We need one share hash tree for the entire file; its leaves
263 # are the roots of the block hash trees for the shares that
264 # comprise it, and its root is in the verinfo.
265 self.share_hash_tree = hashtree.IncompleteHashTree(N)
266 self.share_hash_tree.set_hashes({0: root_hash})
268 # This will set up both the segment decoder and the tail segment
269 # decoder, as well as a variety of other instance variables that
270 # the download process will use.
271 self._setup_encoding_parameters()
272 assert len(self.remaining_sharemap) >= k
274 self.log("starting download")
275 self._started_fetching = time.time()
277 self._add_active_peers()
278 # The download process beyond this is a state machine.
279 # _add_active_peers will select the peers that we want to use
280 # for the download, and then attempt to start downloading. After
281 # each segment, it will check for doneness, reacting to broken
282 # peers and corrupt shares as necessary. If it runs out of good
283 # peers before downloading all of the segments, _done_deferred
284 # will errback. Otherwise, it will eventually callback with the
285 # contents of the mutable file.
286 return self._done_deferred
289 def decode(self, blocks_and_salts, segnum):
291 I am a helper method that the mutable file update process uses
292 as a shortcut to decode and decrypt the segments that it needs
293 to fetch in order to perform a file update. I take in a
294 collection of blocks and salts, and pick some of those to make a
295 segment with. I return the plaintext associated with that
298 # shnum => block hash tree. Unused, but setup_encoding_parameters will
300 # XXX: Make it so that it won't set this if we're just decoding.
301 self._block_hash_trees = None
302 self._setup_encoding_parameters()
303 # This is the form expected by decode.
304 blocks_and_salts = blocks_and_salts.items()
305 blocks_and_salts = [(True, [d]) for d in blocks_and_salts]
307 d = self._decode_blocks(blocks_and_salts, segnum)
308 d.addCallback(self._decrypt_segment)
312 def _setup_encoding_parameters(self):
314 I set up the encoding parameters, including k, n, the number
315 of segments associated with this file, and the segment decoder.
325 offsets_tuple) = self.verinfo
326 self._required_shares = k
327 self._total_shares = n
328 self._segment_size = segsize
329 self._data_length = datalength
332 self._version = MDMF_VERSION
334 self._version = SDMF_VERSION
336 if datalength and segsize:
337 self._num_segments = mathutil.div_ceil(datalength, segsize)
338 self._tail_data_size = datalength % segsize
340 self._num_segments = 0
341 self._tail_data_size = 0
343 self._segment_decoder = codec.CRSDecoder()
344 self._segment_decoder.set_params(segsize, k, n)
346 if not self._tail_data_size:
347 self._tail_data_size = segsize
349 self._tail_segment_size = mathutil.next_multiple(self._tail_data_size,
350 self._required_shares)
351 if self._tail_segment_size == self._segment_size:
352 self._tail_decoder = self._segment_decoder
354 self._tail_decoder = codec.CRSDecoder()
355 self._tail_decoder.set_params(self._tail_segment_size,
356 self._required_shares,
359 self.log("got encoding parameters: "
362 "%d segments of %d bytes each (%d byte tail segment)" % \
363 (k, n, self._num_segments, self._segment_size,
364 self._tail_segment_size))
366 if self._block_hash_trees is not None:
367 for i in xrange(self._total_shares):
368 # So we don't have to do this later.
369 self._block_hash_trees[i] = hashtree.IncompleteHashTree(self._num_segments)
371 # Our last task is to tell the downloader where to start and
372 # where to stop. We use three parameters for that:
373 # - self._start_segment: the segment that we need to start
375 # - self._current_segment: the next segment that we need to
377 # - self._last_segment: The last segment that we were asked to
380 # We say that the download is complete when
381 # self._current_segment > self._last_segment. We use
382 # self._start_segment and self._last_segment to know when to
383 # strip things off of segments, and how much to strip.
385 self.log("got offset: %d" % self._offset)
386 # our start segment is the first segment containing the
387 # offset we were given.
388 start = mathutil.div_ceil(self._offset,
390 # this gets us the first segment after self._offset. Then
391 # our start segment is the one before it.
394 assert start < self._num_segments
395 self._start_segment = start
396 self.log("got start segment: %d" % self._start_segment)
398 self._start_segment = 0
401 if self._read_length:
402 # our end segment is the last segment containing part of the
403 # segment that we were asked to read.
404 self.log("got read length %d" % self._read_length)
405 end_data = self._offset + self._read_length
406 end = mathutil.div_ceil(end_data,
409 assert end < self._num_segments
410 self._last_segment = end
411 self.log("got end segment: %d" % self._last_segment)
413 self._last_segment = self._num_segments - 1
415 self._current_segment = self._start_segment
417 def _add_active_peers(self):
419 I populate self._active_readers with enough active readers to
420 retrieve the contents of this mutable file. I am called before
421 downloading starts, and (eventually) after each validation
422 error, connection error, or other problem in the download.
424 # TODO: It would be cool to investigate other heuristics for
425 # reader selection. For instance, the cost (in time the user
426 # spends waiting for their file) of selecting a really slow peer
427 # that happens to have a primary share is probably more than
428 # selecting a really fast peer that doesn't have a primary
429 # share. Maybe the servermap could be extended to provide this
430 # information; it could keep track of latency information while
431 # it gathers more important data, and then this routine could
432 # use that to select active readers.
434 # (these and other questions would be easier to answer with a
435 # robust, configurable tahoe-lafs simulator, which modeled node
436 # failures, differences in node speed, and other characteristics
437 # that we expect storage servers to have. You could have
438 # presets for really stable grids (like allmydata.com),
439 # friendnets, make it easy to configure your own settings, and
440 # then simulate the effect of big changes on these use cases
441 # instead of just reasoning about what the effect might be. Out
442 # of scope for MDMF, though.)
444 # We need at least self._required_shares readers to download a
447 needed = self._total_shares
449 needed = self._required_shares - len(self._active_readers)
450 # XXX: Why don't format= log messages work here?
451 self.log("adding %d peers to the active peers list" % needed)
453 # We favor lower numbered shares, since FEC is faster with
454 # primary shares than with other shares, and lower-numbered
455 # shares are more likely to be primary than higher numbered
457 active_shnums = set(sorted(self.remaining_sharemap.keys()))
458 # We shouldn't consider adding shares that we already have; this
459 # will cause problems later.
460 active_shnums -= set([reader.shnum for reader in self._active_readers])
461 active_shnums = list(active_shnums)[:needed]
462 if len(active_shnums) < needed and not self._verify:
463 # We don't have enough readers to retrieve the file; fail.
464 return self._failed()
466 for shnum in active_shnums:
467 self._active_readers.append(self.readers[shnum])
468 self.log("added reader for share %d" % shnum)
469 assert len(self._active_readers) >= self._required_shares
470 # Conceptually, this is part of the _add_active_peers step. It
471 # validates the prefixes of newly added readers to make sure
472 # that they match what we are expecting for self.verinfo. If
473 # validation is successful, _validate_active_prefixes will call
474 # _download_current_segment for us. If validation is
475 # unsuccessful, then _validate_prefixes will remove the peer and
476 # call _add_active_peers again, where we will attempt to rectify
477 # the problem by choosing another peer.
478 return self._validate_active_prefixes()
481 def _validate_active_prefixes(self):
483 I check to make sure that the prefixes on the peers that I am
484 currently reading from match the prefix that we want to see, as
485 said in self.verinfo.
487 If I find that all of the active peers have acceptable prefixes,
488 I pass control to _download_current_segment, which will use
489 those peers to do cool things. If I find that some of the active
490 peers have unacceptable prefixes, I will remove them from active
491 peers (and from further consideration) and call
492 _add_active_peers to attempt to rectify the situation. I keep
493 track of which peers I have already validated so that I don't
496 assert self._active_readers, "No more active readers"
499 new_readers = set(self._active_readers) - self._validated_readers
500 self.log('validating %d newly-added active readers' % len(new_readers))
502 for reader in new_readers:
503 # We force a remote read here -- otherwise, we are relying
504 # on cached data that we already verified as valid, and we
505 # won't detect an uncoordinated write that has occurred
506 # since the last servermap update.
507 d = reader.get_prefix(force_remote=True)
508 d.addCallback(self._try_to_validate_prefix, reader)
510 dl = defer.DeferredList(ds, consumeErrors=True)
511 def _check_results(results):
512 # Each result in results will be of the form (success, msg).
513 # We don't care about msg, but success will tell us whether
514 # or not the checkstring validated. If it didn't, we need to
515 # remove the offending (peer,share) from our active readers,
516 # and ensure that active readers is again populated.
518 for i, result in enumerate(results):
520 reader = self._active_readers[i]
522 assert isinstance(f, failure.Failure)
524 self.log("The reader %s failed to "
525 "properly validate: %s" % \
526 (reader, str(f.value)))
527 bad_readers.append((reader, f))
529 reader = self._active_readers[i]
530 self.log("the reader %s checks out, so we'll use it" % \
532 self._validated_readers.add(reader)
533 # Each time we validate a reader, we check to see if
534 # we need the private key. If we do, we politely ask
535 # for it and then continue computing. If we find
536 # that we haven't gotten it at the end of
537 # segment decoding, then we'll take more drastic
539 if self._need_privkey and not self._node.is_readonly():
540 d = reader.get_encprivkey()
541 d.addCallback(self._try_to_validate_privkey, reader)
543 # We do them all at once, or else we screw up list indexing.
544 for (reader, f) in bad_readers:
545 self._mark_bad_share(reader, f)
547 if len(self._active_readers) >= self._required_shares:
548 return self._download_current_segment()
550 return self._failed()
552 return self._add_active_peers()
554 return self._download_current_segment()
555 # The next step will assert that it has enough active
556 # readers to fetch shares; we just need to remove it.
557 dl.addCallback(_check_results)
561 def _try_to_validate_prefix(self, prefix, reader):
563 I check that the prefix returned by a candidate server for
564 retrieval matches the prefix that the servermap knows about
565 (and, hence, the prefix that was validated earlier). If it does,
566 I return True, which means that I approve of the use of the
567 candidate server for segment retrieval. If it doesn't, I return
568 False, which means that another server must be chosen.
578 offsets_tuple) = self.verinfo
579 if known_prefix != prefix:
580 self.log("prefix from share %d doesn't match" % reader.shnum)
581 raise UncoordinatedWriteError("Mismatched prefix -- this could "
582 "indicate an uncoordinated write")
583 # Otherwise, we're okay -- no issues.
586 def _remove_reader(self, reader):
588 At various points, we will wish to remove a peer from
589 consideration and/or use. These include, but are not necessarily
592 - A connection error.
593 - A mismatched prefix (that is, a prefix that does not match
594 our conception of the version information string).
595 - A failing block hash, salt hash, or share hash, which can
596 indicate disk failure/bit flips, or network trouble.
598 This method will do that. I will make sure that the
599 (shnum,reader) combination represented by my reader argument is
600 not used for anything else during this download. I will not
601 advise the reader of any corruption, something that my callers
602 may wish to do on their own.
604 # TODO: When you're done writing this, see if this is ever
605 # actually used for something that _mark_bad_share isn't. I have
606 # a feeling that they will be used for very similar things, and
607 # that having them both here is just going to be an epic amount
608 # of code duplication.
610 # (well, okay, not epic, but meaningful)
611 self.log("removing reader %s" % reader)
612 # Remove the reader from _active_readers
613 self._active_readers.remove(reader)
614 # TODO: self.readers.remove(reader)?
615 for shnum in list(self.remaining_sharemap.keys()):
616 self.remaining_sharemap.discard(shnum, reader.peerid)
619 def _mark_bad_share(self, reader, f):
621 I mark the (peerid, shnum) encapsulated by my reader argument as
622 a bad share, which means that it will not be used anywhere else.
624 There are several reasons to want to mark something as a bad
625 share. These include:
627 - A connection error to the peer.
628 - A mismatched prefix (that is, a prefix that does not match
629 our local conception of the version information string).
630 - A failing block hash, salt hash, share hash, or other
633 This method will ensure that readers that we wish to mark bad
634 (for these reasons or other reasons) are not used for the rest
635 of the download. Additionally, it will attempt to tell the
636 remote peer (with no guarantee of success) that its share is
639 self.log("marking share %d on server %s as bad" % \
640 (reader.shnum, reader))
641 prefix = self.verinfo[-2]
642 self.servermap.mark_bad_share(reader.peerid,
645 self._remove_reader(reader)
646 self._bad_shares.add((reader.peerid, reader.shnum, f))
647 self._status.problems[reader.peerid] = f
648 self._last_failure = f
649 self.notify_server_corruption(reader.peerid, reader.shnum,
653 def _download_current_segment(self):
655 I download, validate, decode, decrypt, and assemble the segment
656 that this Retrieve is currently responsible for downloading.
658 assert len(self._active_readers) >= self._required_shares
659 if self._current_segment <= self._last_segment:
660 d = self._process_segment(self._current_segment)
662 d = defer.succeed(None)
663 d.addBoth(self._turn_barrier)
664 d.addCallback(self._check_for_done)
668 def _turn_barrier(self, result):
670 I help the download process avoid the recursion limit issues
673 return fireEventually(result)
676 def _process_segment(self, segnum):
678 I download, validate, decode, and decrypt one segment of the
679 file that this Retrieve is retrieving. This means coordinating
680 the process of getting k blocks of that file, validating them,
681 assembling them into one segment with the decoder, and then
684 self.log("processing segment %d" % segnum)
686 # TODO: The old code uses a marker. Should this code do that
687 # too? What did the Marker do?
688 assert len(self._active_readers) >= self._required_shares
690 # We need to ask each of our active readers for its block and
691 # salt. We will then validate those. If validation is
692 # successful, we will assemble the results into plaintext.
694 for reader in self._active_readers:
695 started = time.time()
696 d = reader.get_block_and_salt(segnum, queue=True)
697 d2 = self._get_needed_hashes(reader, segnum)
698 dl = defer.DeferredList([d, d2], consumeErrors=True)
699 dl.addCallback(self._validate_block, segnum, reader, started)
700 dl.addErrback(self._validation_or_decoding_failed, [reader])
703 dl = defer.DeferredList(ds)
705 dl.addCallback(lambda ignored: "")
706 dl.addCallback(self._set_segment)
708 dl.addCallback(self._maybe_decode_and_decrypt_segment, segnum)
712 def _maybe_decode_and_decrypt_segment(self, blocks_and_salts, segnum):
714 I take the results of fetching and validating the blocks from a
715 callback chain in another method. If the results are such that
716 they tell me that validation and fetching succeeded without
717 incident, I will proceed with decoding and decryption.
718 Otherwise, I will do nothing.
720 self.log("trying to decode and decrypt segment %d" % segnum)
722 for block_and_salt in blocks_and_salts:
723 if not block_and_salt[0] or block_and_salt[1] == None:
724 self.log("some validation operations failed; not proceeding")
728 self.log("everything looks ok, building segment %d" % segnum)
729 d = self._decode_blocks(blocks_and_salts, segnum)
730 d.addCallback(self._decrypt_segment)
731 d.addErrback(self._validation_or_decoding_failed,
732 self._active_readers)
733 # check to see whether we've been paused before writing
735 d.addCallback(self._check_for_paused)
736 d.addCallback(self._set_segment)
739 return defer.succeed(None)
742 def _set_segment(self, segment):
744 Given a plaintext segment, I register that segment with the
745 target that is handling the file download.
747 self.log("got plaintext for segment %d" % self._current_segment)
748 if self._current_segment == self._start_segment:
749 # We're on the first segment. It's possible that we want
750 # only some part of the end of this segment, and that we
751 # just downloaded the whole thing to get that part. If so,
752 # we need to account for that and give the reader just the
753 # data that they want.
754 n = self._offset % self._segment_size
755 self.log("stripping %d bytes off of the first segment" % n)
756 self.log("original segment length: %d" % len(segment))
757 segment = segment[n:]
758 self.log("new segment length: %d" % len(segment))
760 if self._current_segment == self._last_segment and self._read_length is not None:
761 # We're on the last segment. It's possible that we only want
762 # part of the beginning of this segment, and that we
763 # downloaded the whole thing anyway. Make sure to give the
764 # caller only the portion of the segment that they want to
766 extra = self._read_length
767 if self._start_segment != self._last_segment:
768 extra -= self._segment_size - \
769 (self._offset % self._segment_size)
770 extra %= self._segment_size
771 self.log("original segment length: %d" % len(segment))
772 segment = segment[:extra]
773 self.log("new segment length: %d" % len(segment))
774 self.log("only taking %d bytes of the last segment" % extra)
777 self._consumer.write(segment)
779 # we don't care about the plaintext if we are doing a verify.
781 self._current_segment += 1
784 def _validation_or_decoding_failed(self, f, readers):
786 I am called when a block or a salt fails to correctly validate, or when
787 the decryption or decoding operation fails for some reason. I react to
788 this failure by notifying the remote server of corruption, and then
789 removing the remote peer from further activity.
791 assert isinstance(readers, list)
792 bad_shnums = [reader.shnum for reader in readers]
794 self.log("validation or decoding failed on share(s) %s, peer(s) %s "
795 ", segment %d: %s" % \
796 (bad_shnums, readers, self._current_segment, str(f)))
797 for reader in readers:
798 self._mark_bad_share(reader, f)
802 def _validate_block(self, results, segnum, reader, started):
804 I validate a block from one share on a remote server.
806 # Grab the part of the block hash tree that is necessary to
807 # validate this block, then generate the block hash root.
808 self.log("validating share %d for segment %d" % (reader.shnum,
810 self._status.add_fetch_timing(reader.peerid, started)
811 self._status.set_status("Valdiating blocks for segment %d" % segnum)
812 # Did we fail to fetch either of the things that we were
813 # supposed to? Fail if so.
814 if not results[0][0] and results[1][0]:
815 # handled by the errback handler.
817 # These all get batched into one query, so the resulting
818 # failure should be the same for all of them, so we can just
820 assert isinstance(results[0][1], failure.Failure)
823 raise CorruptShareError(reader.peerid,
825 "Connection error: %s" % str(f))
827 block_and_salt, block_and_sharehashes = results
828 block, salt = block_and_salt[1]
829 blockhashes, sharehashes = block_and_sharehashes[1]
831 blockhashes = dict(enumerate(blockhashes[1]))
832 self.log("the reader gave me the following blockhashes: %s" % \
834 self.log("the reader gave me the following sharehashes: %s" % \
835 sharehashes[1].keys())
836 bht = self._block_hash_trees[reader.shnum]
838 if bht.needed_hashes(segnum, include_leaf=True):
840 bht.set_hashes(blockhashes)
841 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
843 raise CorruptShareError(reader.peerid,
845 "block hash tree failure: %s" % e)
847 if self._version == MDMF_VERSION:
848 blockhash = hashutil.block_hash(salt + block)
850 blockhash = hashutil.block_hash(block)
851 # If this works without an error, then validation is
854 bht.set_hashes(leaves={segnum: blockhash})
855 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
857 raise CorruptShareError(reader.peerid,
859 "block hash tree failure: %s" % e)
861 # Reaching this point means that we know that this segment
862 # is correct. Now we need to check to see whether the share
863 # hash chain is also correct.
864 # SDMF wrote share hash chains that didn't contain the
865 # leaves, which would be produced from the block hash tree.
866 # So we need to validate the block hash tree first. If
867 # successful, then bht[0] will contain the root for the
868 # shnum, which will be a leaf in the share hash tree, which
869 # will allow us to validate the rest of the tree.
870 if self.share_hash_tree.needed_hashes(reader.shnum,
871 include_leaf=True) or \
874 self.share_hash_tree.set_hashes(hashes=sharehashes[1],
875 leaves={reader.shnum: bht[0]})
876 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
878 raise CorruptShareError(reader.peerid,
880 "corrupt hashes: %s" % e)
882 self.log('share %d is valid for segment %d' % (reader.shnum,
884 return {reader.shnum: (block, salt)}
887 def _get_needed_hashes(self, reader, segnum):
889 I get the hashes needed to validate segnum from the reader, then return
890 to my caller when this is done.
892 bht = self._block_hash_trees[reader.shnum]
893 needed = bht.needed_hashes(segnum, include_leaf=True)
894 # The root of the block hash tree is also a leaf in the share
895 # hash tree. So we don't need to fetch it from the remote
896 # server. In the case of files with one segment, this means that
897 # we won't fetch any block hash tree from the remote server,
898 # since the hash of each share of the file is the entire block
899 # hash tree, and is a leaf in the share hash tree. This is fine,
900 # since any share corruption will be detected in the share hash
903 self.log("getting blockhashes for segment %d, share %d: %s" % \
904 (segnum, reader.shnum, str(needed)))
905 d1 = reader.get_blockhashes(needed, queue=True, force_remote=True)
906 if self.share_hash_tree.needed_hashes(reader.shnum):
907 need = self.share_hash_tree.needed_hashes(reader.shnum)
908 self.log("also need sharehashes for share %d: %s" % (reader.shnum,
910 d2 = reader.get_sharehashes(need, queue=True, force_remote=True)
912 d2 = defer.succeed({}) # the logic in the next method
914 dl = defer.DeferredList([d1, d2], consumeErrors=True)
918 def _decode_blocks(self, blocks_and_salts, segnum):
920 I take a list of k blocks and salts, and decode that into a
921 single encrypted segment.
924 # We want to merge our dictionaries to the form
925 # {shnum: blocks_and_salts}
927 # The dictionaries come from validate block that way, so we just
928 # need to merge them.
929 for block_and_salt in blocks_and_salts:
930 d.update(block_and_salt[1])
932 # All of these blocks should have the same salt; in SDMF, it is
933 # the file-wide IV, while in MDMF it is the per-segment salt. In
934 # either case, we just need to get one of them and use it.
936 # d.items()[0] is like (shnum, (block, salt))
937 # d.items()[0][1] is like (block, salt)
938 # d.items()[0][1][1] is the salt.
939 salt = d.items()[0][1][1]
940 # Next, extract just the blocks from the dict. We'll use the
941 # salt in the next step.
942 share_and_shareids = [(k, v[0]) for k, v in d.items()]
943 d2 = dict(share_and_shareids)
946 for shareid, share in d2.items():
947 shareids.append(shareid)
950 self._status.set_status("Decoding")
951 started = time.time()
952 assert len(shareids) >= self._required_shares, len(shareids)
953 # zfec really doesn't want extra shares
954 shareids = shareids[:self._required_shares]
955 shares = shares[:self._required_shares]
956 self.log("decoding segment %d" % segnum)
957 if segnum == self._num_segments - 1:
958 d = defer.maybeDeferred(self._tail_decoder.decode, shares, shareids)
960 d = defer.maybeDeferred(self._segment_decoder.decode, shares, shareids)
961 def _process(buffers):
962 segment = "".join(buffers)
963 self.log(format="now decoding segment %(segnum)s of %(numsegs)s",
965 numsegs=self._num_segments,
967 self.log(" joined length %d, datalength %d" %
968 (len(segment), self._data_length))
969 if segnum == self._num_segments - 1:
970 size_to_use = self._tail_data_size
972 size_to_use = self._segment_size
973 segment = segment[:size_to_use]
974 self.log(" segment len=%d" % len(segment))
975 self._status.timings.setdefault("decode", 0)
976 self._status.timings['decode'] = time.time() - started
978 d.addCallback(_process)
982 def _decrypt_segment(self, segment_and_salt):
984 I take a single segment and its salt, and decrypt it. I return
985 the plaintext of the segment that is in my argument.
987 segment, salt = segment_and_salt
988 self._status.set_status("decrypting")
989 self.log("decrypting segment %d" % self._current_segment)
990 started = time.time()
991 key = hashutil.ssk_readkey_data_hash(salt, self._node.get_readkey())
993 plaintext = decryptor.process(segment)
994 self._status.timings.setdefault("decrypt", 0)
995 self._status.timings['decrypt'] = time.time() - started
999 def notify_server_corruption(self, peerid, shnum, reason):
1000 ss = self.servermap.connections[peerid]
1001 ss.callRemoteOnly("advise_corrupt_share",
1002 "mutable", self._storage_index, shnum, reason)
1005 def _try_to_validate_privkey(self, enc_privkey, reader):
1006 alleged_privkey_s = self._node._decrypt_privkey(enc_privkey)
1007 alleged_writekey = hashutil.ssk_writekey_hash(alleged_privkey_s)
1008 if alleged_writekey != self._node.get_writekey():
1009 self.log("invalid privkey from %s shnum %d" %
1010 (reader, reader.shnum),
1011 level=log.WEIRD, umid="YIw4tA")
1013 self.servermap.mark_bad_share(reader.peerid, reader.shnum,
1015 e = CorruptShareError(reader.peerid,
1018 f = failure.Failure(e)
1019 self._bad_shares.add((reader.peerid, reader.shnum, f))
1023 self.log("got valid privkey from shnum %d on reader %s" %
1024 (reader.shnum, reader))
1025 privkey = rsa.create_signing_key_from_string(alleged_privkey_s)
1026 self._node._populate_encprivkey(enc_privkey)
1027 self._node._populate_privkey(privkey)
1028 self._need_privkey = False
1031 def _check_for_done(self, res):
1033 I check to see if this Retrieve object has successfully finished
1036 I can exit in the following ways:
1037 - If there are no more segments to download, then I exit by
1038 causing self._done_deferred to fire with the plaintext
1039 content requested by the caller.
1040 - If there are still segments to be downloaded, and there
1041 are enough active readers (readers which have not broken
1042 and have not given us corrupt data) to continue
1043 downloading, I send control back to
1044 _download_current_segment.
1045 - If there are still segments to be downloaded but there are
1046 not enough active peers to download them, I ask
1047 _add_active_peers to add more peers. If it is successful,
1048 it will call _download_current_segment. If there are not
1049 enough peers to retrieve the file, then that will cause
1050 _done_deferred to errback.
1052 self.log("checking for doneness")
1053 if self._current_segment > self._last_segment:
1054 # No more segments to download, we're done.
1055 self.log("got plaintext, done")
1058 if len(self._active_readers) >= self._required_shares:
1059 # More segments to download, but we have enough good peers
1060 # in self._active_readers that we can do that without issue,
1061 # so go nab the next segment.
1062 self.log("not done yet: on segment %d of %d" % \
1063 (self._current_segment + 1, self._num_segments))
1064 return self._download_current_segment()
1066 self.log("not done yet: on segment %d of %d, need to add peers" % \
1067 (self._current_segment + 1, self._num_segments))
1068 return self._add_active_peers()
1073 I am called by _check_for_done when the download process has
1074 finished successfully. After making some useful logging
1075 statements, I return the decrypted contents to the owner of this
1076 Retrieve object through self._done_deferred.
1078 self._running = False
1079 self._status.set_active(False)
1081 self._status.timings['total'] = now - self._started
1082 self._status.timings['fetch'] = now - self._started_fetching
1085 ret = list(self._bad_shares)
1086 self.log("done verifying, found %d bad shares" % len(ret))
1088 # TODO: upload status here?
1089 ret = self._consumer
1090 self._consumer.unregisterProducer()
1091 eventually(self._done_deferred.callback, ret)
1096 I am called by _add_active_peers when there are not enough
1097 active peers left to complete the download. After making some
1098 useful logging statements, I return an exception to that effect
1099 to the caller of this Retrieve object through
1100 self._done_deferred.
1102 self._running = False
1103 self._status.set_active(False)
1105 self._status.timings['total'] = now - self._started
1106 self._status.timings['fetch'] = now - self._started_fetching
1109 ret = list(self._bad_shares)
1111 format = ("ran out of peers: "
1112 "have %(have)d of %(total)d segments "
1113 "found %(bad)d bad shares "
1114 "encoding %(k)d-of-%(n)d")
1115 args = {"have": self._current_segment,
1116 "total": self._num_segments,
1117 "need": self._last_segment,
1118 "k": self._required_shares,
1119 "n": self._total_shares,
1120 "bad": len(self._bad_shares)}
1121 e = NotEnoughSharesError("%s, last failure: %s" % \
1122 (format % args, str(self._last_failure)))
1123 f = failure.Failure(e)
1125 eventually(self._done_deferred.callback, ret)