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 DownloadStopped, 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["decode"] = 0.0
28 self.timings["decrypt"] = 0.0
29 self.timings["cumulative_verify"] = 0.0
32 self.storage_index = None
34 self.encoding = ("?","?")
36 self.status = "Not started"
38 self.counter = self.statusid_counter.next()
39 self.started = time.time()
41 def get_started(self):
43 def get_storage_index(self):
44 return self.storage_index
45 def get_encoding(self):
47 def using_helper(self):
53 def get_progress(self):
57 def get_counter(self):
60 def add_fetch_timing(self, peerid, elapsed):
61 if peerid not in self.timings["fetch_per_server"]:
62 self.timings["fetch_per_server"][peerid] = []
63 self.timings["fetch_per_server"][peerid].append(elapsed)
64 def accumulate_decode_time(self, elapsed):
65 self.timings["decode"] += elapsed
66 def accumulate_decrypt_time(self, elapsed):
67 self.timings["decrypt"] += elapsed
68 def set_storage_index(self, si):
69 self.storage_index = si
70 def set_helper(self, helper):
72 def set_encoding(self, k, n):
73 self.encoding = (k, n)
74 def set_size(self, size):
76 def set_status(self, status):
78 def set_progress(self, value):
80 def set_active(self, value):
87 # this class is currently single-use. Eventually (in MDMF) we will make
88 # it multi-use, in which case you can call download(range) multiple
89 # times, and each will have a separate response chain. However the
90 # Retrieve object will remain tied to a specific version of the file, and
91 # will use a single ServerMap instance.
92 implements(IPushProducer)
94 def __init__(self, filenode, servermap, verinfo, fetch_privkey=False,
97 assert self._node.get_pubkey()
98 self._storage_index = filenode.get_storage_index()
99 assert self._node.get_readkey()
100 self._last_failure = None
101 prefix = si_b2a(self._storage_index)[:5]
102 self._log_number = log.msg("Retrieve(%s): starting" % prefix)
103 self._outstanding_queries = {} # maps (peerid,shnum) to start_time
105 self._decoding = False
106 self._bad_shares = set()
108 self.servermap = servermap
109 assert self._node.get_pubkey()
110 self.verinfo = verinfo
111 # during repair, we may be called upon to grab the private key, since
112 # it wasn't picked up during a verify=False checker run, and we'll
113 # need it for repair to generate a new version.
114 self._need_privkey = verify or (fetch_privkey
115 and not self._node.get_privkey())
117 if self._need_privkey:
118 # TODO: Evaluate the need for this. We'll use it if we want
119 # to limit how many queries are on the wire for the privkey
121 self._privkey_query_markers = [] # one Marker for each time we've
122 # tried to get the privkey.
124 # verify means that we are using the downloader logic to verify all
125 # of our shares. This tells the downloader a few things.
127 # 1. We need to download all of the shares.
128 # 2. We don't need to decode or decrypt the shares, since our
129 # caller doesn't care about the plaintext, only the
130 # information about which shares are or are not valid.
131 # 3. When we are validating readers, we need to validate the
132 # signature on the prefix. Do we? We already do this in the
134 self._verify = verify
136 self._status = RetrieveStatus()
137 self._status.set_storage_index(self._storage_index)
138 self._status.set_helper(False)
139 self._status.set_progress(0.0)
140 self._status.set_active(True)
141 (seqnum, root_hash, IV, segsize, datalength, k, N, prefix,
142 offsets_tuple) = self.verinfo
143 self._status.set_size(datalength)
144 self._status.set_encoding(k, N)
146 self._stopped = False
147 self._pause_deferred = None
149 self._read_length = None
150 self.log("got seqnum %d" % self.verinfo[0])
153 def get_status(self):
156 def log(self, *args, **kwargs):
157 if "parent" not in kwargs:
158 kwargs["parent"] = self._log_number
159 if "facility" not in kwargs:
160 kwargs["facility"] = "tahoe.mutable.retrieve"
161 return log.msg(*args, **kwargs)
163 def _set_current_status(self, state):
164 seg = "%d/%d" % (self._current_segment, self._last_segment)
165 self._status.set_status("segment %s (%s)" % (seg, state))
170 def pauseProducing(self):
172 I am called by my download target if we have produced too much
173 data for it to handle. I make the downloader stop producing new
174 data until my resumeProducing method is called.
176 if self._pause_deferred is not None:
179 # fired when the download is unpaused.
180 self._old_status = self._status.get_status()
181 self._set_current_status("paused")
183 self._pause_deferred = defer.Deferred()
186 def resumeProducing(self):
188 I am called by my download target once it is ready to begin
189 receiving data again.
191 if self._pause_deferred is None:
194 p = self._pause_deferred
195 self._pause_deferred = None
196 self._status.set_status(self._old_status)
198 eventually(p.callback, None)
200 def stopProducing(self):
202 self.resumeProducing()
205 def _check_for_paused(self, res):
207 I am called just before a write to the consumer. I return a
208 Deferred that eventually fires with the data that is to be
209 written to the consumer. If the download has not been paused,
210 the Deferred fires immediately. Otherwise, the Deferred fires
211 when the downloader is unpaused.
214 raise DownloadStopped("our Consumer called stopProducing()")
215 if self._pause_deferred is not None:
217 self._pause_deferred.addCallback(lambda ignored: d.callback(res))
219 return defer.succeed(res)
222 def download(self, consumer=None, offset=0, size=None):
223 assert IConsumer.providedBy(consumer) or self._verify
226 self._consumer = consumer
227 # we provide IPushProducer, so streaming=True, per
229 self._consumer.registerProducer(self, streaming=True)
231 self._done_deferred = defer.Deferred()
232 self._offset = offset
233 self._read_length = size
234 self._setup_download()
235 self._setup_encoding_parameters()
236 self.log("starting download")
237 self._started_fetching = time.time()
238 # The download process beyond this is a state machine.
239 # _add_active_peers will select the peers that we want to use
240 # for the download, and then attempt to start downloading. After
241 # each segment, it will check for doneness, reacting to broken
242 # peers and corrupt shares as necessary. If it runs out of good
243 # peers before downloading all of the segments, _done_deferred
244 # will errback. Otherwise, it will eventually callback with the
245 # contents of the mutable file.
247 return self._done_deferred
250 d = fireEventually(None) # avoid #237 recursion limit problem
251 d.addCallback(lambda ign: self._activate_enough_peers())
252 d.addCallback(lambda ign: self._download_current_segment())
253 # when we're done, _download_current_segment will call _done. If we
254 # aren't, it will call loop() again.
255 d.addErrback(self._error)
257 def _setup_download(self):
258 self._started = time.time()
259 self._status.set_status("Retrieving Shares")
261 # how many shares do we need?
270 offsets_tuple) = self.verinfo
272 # first, which servers can we use?
273 versionmap = self.servermap.make_versionmap()
274 shares = versionmap[self.verinfo]
275 # this sharemap is consumed as we decide to send requests
276 self.remaining_sharemap = DictOfSets()
277 for (shnum, peerid, timestamp) in shares:
278 self.remaining_sharemap.add(shnum, peerid)
279 # If the servermap update fetched anything, it fetched at least 1
280 # KiB, so we ask for that much.
281 # TODO: Change the cache methods to allow us to fetch all of the
282 # data that they have, then change this method to do that.
283 any_cache = self._node._read_from_cache(self.verinfo, shnum,
285 ss = self.servermap.connections[peerid]
286 reader = MDMFSlotReadProxy(ss,
290 reader.peerid = peerid
291 self.readers[shnum] = reader
292 assert len(self.remaining_sharemap) >= k
294 self.shares = {} # maps shnum to validated blocks
295 self._active_readers = [] # list of active readers for this dl.
296 self._block_hash_trees = {} # shnum => hashtree
298 # We need one share hash tree for the entire file; its leaves
299 # are the roots of the block hash trees for the shares that
300 # comprise it, and its root is in the verinfo.
301 self.share_hash_tree = hashtree.IncompleteHashTree(N)
302 self.share_hash_tree.set_hashes({0: root_hash})
304 def decode(self, blocks_and_salts, segnum):
306 I am a helper method that the mutable file update process uses
307 as a shortcut to decode and decrypt the segments that it needs
308 to fetch in order to perform a file update. I take in a
309 collection of blocks and salts, and pick some of those to make a
310 segment with. I return the plaintext associated with that
313 # shnum => block hash tree. Unused, but setup_encoding_parameters will
315 self._block_hash_trees = None
316 self._setup_encoding_parameters()
318 # This is the form expected by decode.
319 blocks_and_salts = blocks_and_salts.items()
320 blocks_and_salts = [(True, [d]) for d in blocks_and_salts]
322 d = self._decode_blocks(blocks_and_salts, segnum)
323 d.addCallback(self._decrypt_segment)
327 def _setup_encoding_parameters(self):
329 I set up the encoding parameters, including k, n, the number
330 of segments associated with this file, and the segment decoders.
340 offsets_tuple) = self.verinfo
341 self._required_shares = k
342 self._total_shares = n
343 self._segment_size = segsize
344 self._data_length = datalength
347 self._version = MDMF_VERSION
349 self._version = SDMF_VERSION
351 if datalength and segsize:
352 self._num_segments = mathutil.div_ceil(datalength, segsize)
353 self._tail_data_size = datalength % segsize
355 self._num_segments = 0
356 self._tail_data_size = 0
358 self._segment_decoder = codec.CRSDecoder()
359 self._segment_decoder.set_params(segsize, k, n)
361 if not self._tail_data_size:
362 self._tail_data_size = segsize
364 self._tail_segment_size = mathutil.next_multiple(self._tail_data_size,
365 self._required_shares)
366 if self._tail_segment_size == self._segment_size:
367 self._tail_decoder = self._segment_decoder
369 self._tail_decoder = codec.CRSDecoder()
370 self._tail_decoder.set_params(self._tail_segment_size,
371 self._required_shares,
374 self.log("got encoding parameters: "
377 "%d segments of %d bytes each (%d byte tail segment)" % \
378 (k, n, self._num_segments, self._segment_size,
379 self._tail_segment_size))
381 if self._block_hash_trees is not None:
382 for i in xrange(self._total_shares):
383 # So we don't have to do this later.
384 self._block_hash_trees[i] = hashtree.IncompleteHashTree(self._num_segments)
386 # Our last task is to tell the downloader where to start and
387 # where to stop. We use three parameters for that:
388 # - self._start_segment: the segment that we need to start
390 # - self._current_segment: the next segment that we need to
392 # - self._last_segment: The last segment that we were asked to
395 # We say that the download is complete when
396 # self._current_segment > self._last_segment. We use
397 # self._start_segment and self._last_segment to know when to
398 # strip things off of segments, and how much to strip.
400 self.log("got offset: %d" % self._offset)
401 # our start segment is the first segment containing the
402 # offset we were given.
403 start = self._offset // self._segment_size
405 assert start < self._num_segments
406 self._start_segment = start
407 self.log("got start segment: %d" % self._start_segment)
409 self._start_segment = 0
412 # If self._read_length is None, then we want to read the whole
413 # file. Otherwise, we want to read only part of the file, and
414 # need to figure out where to stop reading.
415 if self._read_length is not None:
416 # our end segment is the last segment containing part of the
417 # segment that we were asked to read.
418 self.log("got read length %d" % self._read_length)
419 if self._read_length != 0:
420 end_data = self._offset + self._read_length
422 # We don't actually need to read the byte at end_data,
423 # but the one before it.
424 end = (end_data - 1) // self._segment_size
426 assert end < self._num_segments
427 self._last_segment = end
429 self._last_segment = self._start_segment
430 self.log("got end segment: %d" % self._last_segment)
432 self._last_segment = self._num_segments - 1
434 self._current_segment = self._start_segment
436 def _activate_enough_peers(self):
438 I populate self._active_readers with enough active readers to
439 retrieve the contents of this mutable file. I am called before
440 downloading starts, and (eventually) after each validation
441 error, connection error, or other problem in the download.
443 # TODO: It would be cool to investigate other heuristics for
444 # reader selection. For instance, the cost (in time the user
445 # spends waiting for their file) of selecting a really slow peer
446 # that happens to have a primary share is probably more than
447 # selecting a really fast peer that doesn't have a primary
448 # share. Maybe the servermap could be extended to provide this
449 # information; it could keep track of latency information while
450 # it gathers more important data, and then this routine could
451 # use that to select active readers.
453 # (these and other questions would be easier to answer with a
454 # robust, configurable tahoe-lafs simulator, which modeled node
455 # failures, differences in node speed, and other characteristics
456 # that we expect storage servers to have. You could have
457 # presets for really stable grids (like allmydata.com),
458 # friendnets, make it easy to configure your own settings, and
459 # then simulate the effect of big changes on these use cases
460 # instead of just reasoning about what the effect might be. Out
461 # of scope for MDMF, though.)
463 # We need at least self._required_shares readers to download a
464 # segment. If we're verifying, we need all shares.
466 needed = self._total_shares
468 needed = self._required_shares
469 # XXX: Why don't format= log messages work here?
470 self.log("adding %d peers to the active peers list" % needed)
472 if len(self._active_readers) >= needed:
473 # enough shares are active
476 more = needed - len(self._active_readers)
477 known_shnums = set(self.remaining_sharemap.keys())
478 used_shnums = set([r.shnum for r in self._active_readers])
479 unused_shnums = known_shnums - used_shnums
480 # We favor lower numbered shares, since FEC is faster with
481 # primary shares than with other shares, and lower-numbered
482 # shares are more likely to be primary than higher numbered
484 new_shnums = sorted(unused_shnums)[:more]
485 if len(new_shnums) < more and not self._verify:
486 # We don't have enough readers to retrieve the file; fail.
487 self._raise_notenoughshareserror()
489 for shnum in new_shnums:
490 reader = self.readers[shnum]
491 self._active_readers.append(reader)
492 self.log("added reader for share %d" % shnum)
493 # Each time we add a reader, we check to see if we need the
494 # private key. If we do, we politely ask for it and then continue
495 # computing. If we find that we haven't gotten it at the end of
496 # segment decoding, then we'll take more drastic measures.
497 if self._need_privkey and not self._node.is_readonly():
498 d = reader.get_encprivkey()
499 d.addCallback(self._try_to_validate_privkey, reader)
500 # XXX: don't just drop the Deferred. We need error-reporting
501 # but not flow-control here.
502 assert len(self._active_readers) >= self._required_shares
504 def _try_to_validate_prefix(self, prefix, reader):
506 I check that the prefix returned by a candidate server for
507 retrieval matches the prefix that the servermap knows about
508 (and, hence, the prefix that was validated earlier). If it does,
509 I return True, which means that I approve of the use of the
510 candidate server for segment retrieval. If it doesn't, I return
511 False, which means that another server must be chosen.
521 offsets_tuple) = self.verinfo
522 if known_prefix != prefix:
523 self.log("prefix from share %d doesn't match" % reader.shnum)
524 raise UncoordinatedWriteError("Mismatched prefix -- this could "
525 "indicate an uncoordinated write")
526 # Otherwise, we're okay -- no issues.
529 def _remove_reader(self, reader):
531 At various points, we will wish to remove a peer from
532 consideration and/or use. These include, but are not necessarily
535 - A connection error.
536 - A mismatched prefix (that is, a prefix that does not match
537 our conception of the version information string).
538 - A failing block hash, salt hash, or share hash, which can
539 indicate disk failure/bit flips, or network trouble.
541 This method will do that. I will make sure that the
542 (shnum,reader) combination represented by my reader argument is
543 not used for anything else during this download. I will not
544 advise the reader of any corruption, something that my callers
545 may wish to do on their own.
547 # TODO: When you're done writing this, see if this is ever
548 # actually used for something that _mark_bad_share isn't. I have
549 # a feeling that they will be used for very similar things, and
550 # that having them both here is just going to be an epic amount
551 # of code duplication.
553 # (well, okay, not epic, but meaningful)
554 self.log("removing reader %s" % reader)
555 # Remove the reader from _active_readers
556 self._active_readers.remove(reader)
557 # TODO: self.readers.remove(reader)?
558 for shnum in list(self.remaining_sharemap.keys()):
559 self.remaining_sharemap.discard(shnum, reader.peerid)
562 def _mark_bad_share(self, reader, f):
564 I mark the (peerid, shnum) encapsulated by my reader argument as
565 a bad share, which means that it will not be used anywhere else.
567 There are several reasons to want to mark something as a bad
568 share. These include:
570 - A connection error to the peer.
571 - A mismatched prefix (that is, a prefix that does not match
572 our local conception of the version information string).
573 - A failing block hash, salt hash, share hash, or other
576 This method will ensure that readers that we wish to mark bad
577 (for these reasons or other reasons) are not used for the rest
578 of the download. Additionally, it will attempt to tell the
579 remote peer (with no guarantee of success) that its share is
582 self.log("marking share %d on server %s as bad" % \
583 (reader.shnum, reader))
584 prefix = self.verinfo[-2]
585 self.servermap.mark_bad_share(reader.peerid,
588 self._remove_reader(reader)
589 self._bad_shares.add((reader.peerid, reader.shnum, f))
590 self._status.problems[reader.peerid] = f
591 self._last_failure = f
592 self.notify_server_corruption(reader.peerid, reader.shnum,
596 def _download_current_segment(self):
598 I download, validate, decode, decrypt, and assemble the segment
599 that this Retrieve is currently responsible for downloading.
601 assert len(self._active_readers) >= self._required_shares
602 if self._current_segment > self._last_segment:
603 # No more segments to download, we're done.
604 self.log("got plaintext, done")
606 self.log("on segment %d of %d" %
607 (self._current_segment + 1, self._num_segments))
608 d = self._process_segment(self._current_segment)
609 d.addCallback(lambda ign: self.loop())
612 def _process_segment(self, segnum):
614 I download, validate, decode, and decrypt one segment of the
615 file that this Retrieve is retrieving. This means coordinating
616 the process of getting k blocks of that file, validating them,
617 assembling them into one segment with the decoder, and then
620 self.log("processing segment %d" % segnum)
622 # TODO: The old code uses a marker. Should this code do that
623 # too? What did the Marker do?
624 assert len(self._active_readers) >= self._required_shares
626 # We need to ask each of our active readers for its block and
627 # salt. We will then validate those. If validation is
628 # successful, we will assemble the results into plaintext.
630 for reader in self._active_readers:
631 started = time.time()
632 d = reader.get_block_and_salt(segnum)
633 d2 = self._get_needed_hashes(reader, segnum)
634 dl = defer.DeferredList([d, d2], consumeErrors=True)
635 dl.addCallback(self._validate_block, segnum, reader, started)
636 dl.addErrback(self._validation_or_decoding_failed, [reader])
638 dl = defer.DeferredList(ds)
640 dl.addCallback(lambda ignored: "")
641 dl.addCallback(self._set_segment)
643 dl.addCallback(self._maybe_decode_and_decrypt_segment, segnum)
647 def _maybe_decode_and_decrypt_segment(self, blocks_and_salts, segnum):
649 I take the results of fetching and validating the blocks from a
650 callback chain in another method. If the results are such that
651 they tell me that validation and fetching succeeded without
652 incident, I will proceed with decoding and decryption.
653 Otherwise, I will do nothing.
655 self.log("trying to decode and decrypt segment %d" % segnum)
657 for block_and_salt in blocks_and_salts:
658 if not block_and_salt[0] or block_and_salt[1] == None:
659 self.log("some validation operations failed; not proceeding")
663 self.log("everything looks ok, building segment %d" % segnum)
664 d = self._decode_blocks(blocks_and_salts, segnum)
665 d.addCallback(self._decrypt_segment)
666 d.addErrback(self._validation_or_decoding_failed,
667 self._active_readers)
668 # check to see whether we've been paused before writing
670 d.addCallback(self._check_for_paused)
671 d.addCallback(self._set_segment)
674 return defer.succeed(None)
677 def _set_segment(self, segment):
679 Given a plaintext segment, I register that segment with the
680 target that is handling the file download.
682 self.log("got plaintext for segment %d" % self._current_segment)
683 if self._current_segment == self._start_segment:
684 # We're on the first segment. It's possible that we want
685 # only some part of the end of this segment, and that we
686 # just downloaded the whole thing to get that part. If so,
687 # we need to account for that and give the reader just the
688 # data that they want.
689 n = self._offset % self._segment_size
690 self.log("stripping %d bytes off of the first segment" % n)
691 self.log("original segment length: %d" % len(segment))
692 segment = segment[n:]
693 self.log("new segment length: %d" % len(segment))
695 if self._current_segment == self._last_segment and self._read_length is not None:
696 # We're on the last segment. It's possible that we only want
697 # part of the beginning of this segment, and that we
698 # downloaded the whole thing anyway. Make sure to give the
699 # caller only the portion of the segment that they want to
701 extra = self._read_length
702 if self._start_segment != self._last_segment:
703 extra -= self._segment_size - \
704 (self._offset % self._segment_size)
705 extra %= self._segment_size
706 self.log("original segment length: %d" % len(segment))
707 segment = segment[:extra]
708 self.log("new segment length: %d" % len(segment))
709 self.log("only taking %d bytes of the last segment" % extra)
712 self._consumer.write(segment)
714 # we don't care about the plaintext if we are doing a verify.
716 self._current_segment += 1
719 def _validation_or_decoding_failed(self, f, readers):
721 I am called when a block or a salt fails to correctly validate, or when
722 the decryption or decoding operation fails for some reason. I react to
723 this failure by notifying the remote server of corruption, and then
724 removing the remote peer from further activity.
726 assert isinstance(readers, list)
727 bad_shnums = [reader.shnum for reader in readers]
729 self.log("validation or decoding failed on share(s) %s, peer(s) %s "
730 ", segment %d: %s" % \
731 (bad_shnums, readers, self._current_segment, str(f)))
732 for reader in readers:
733 self._mark_bad_share(reader, f)
737 def _validate_block(self, results, segnum, reader, started):
739 I validate a block from one share on a remote server.
741 # Grab the part of the block hash tree that is necessary to
742 # validate this block, then generate the block hash root.
743 self.log("validating share %d for segment %d" % (reader.shnum,
745 elapsed = time.time() - started
746 self._status.add_fetch_timing(reader.peerid, elapsed)
747 self._set_current_status("validating blocks")
748 # Did we fail to fetch either of the things that we were
749 # supposed to? Fail if so.
750 if not results[0][0] and results[1][0]:
751 # handled by the errback handler.
753 # These all get batched into one query, so the resulting
754 # failure should be the same for all of them, so we can just
756 assert isinstance(results[0][1], failure.Failure)
759 raise CorruptShareError(reader.peerid,
761 "Connection error: %s" % str(f))
763 block_and_salt, block_and_sharehashes = results
764 block, salt = block_and_salt[1]
765 blockhashes, sharehashes = block_and_sharehashes[1]
767 blockhashes = dict(enumerate(blockhashes[1]))
768 self.log("the reader gave me the following blockhashes: %s" % \
770 self.log("the reader gave me the following sharehashes: %s" % \
771 sharehashes[1].keys())
772 bht = self._block_hash_trees[reader.shnum]
774 if bht.needed_hashes(segnum, include_leaf=True):
776 bht.set_hashes(blockhashes)
777 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
779 raise CorruptShareError(reader.peerid,
781 "block hash tree failure: %s" % e)
783 if self._version == MDMF_VERSION:
784 blockhash = hashutil.block_hash(salt + block)
786 blockhash = hashutil.block_hash(block)
787 # If this works without an error, then validation is
790 bht.set_hashes(leaves={segnum: blockhash})
791 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
793 raise CorruptShareError(reader.peerid,
795 "block hash tree failure: %s" % e)
797 # Reaching this point means that we know that this segment
798 # is correct. Now we need to check to see whether the share
799 # hash chain is also correct.
800 # SDMF wrote share hash chains that didn't contain the
801 # leaves, which would be produced from the block hash tree.
802 # So we need to validate the block hash tree first. If
803 # successful, then bht[0] will contain the root for the
804 # shnum, which will be a leaf in the share hash tree, which
805 # will allow us to validate the rest of the tree.
806 if self.share_hash_tree.needed_hashes(reader.shnum,
807 include_leaf=True) or \
810 self.share_hash_tree.set_hashes(hashes=sharehashes[1],
811 leaves={reader.shnum: bht[0]})
812 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
814 raise CorruptShareError(reader.peerid,
816 "corrupt hashes: %s" % e)
818 self.log('share %d is valid for segment %d' % (reader.shnum,
820 return {reader.shnum: (block, salt)}
823 def _get_needed_hashes(self, reader, segnum):
825 I get the hashes needed to validate segnum from the reader, then return
826 to my caller when this is done.
828 bht = self._block_hash_trees[reader.shnum]
829 needed = bht.needed_hashes(segnum, include_leaf=True)
830 # The root of the block hash tree is also a leaf in the share
831 # hash tree. So we don't need to fetch it from the remote
832 # server. In the case of files with one segment, this means that
833 # we won't fetch any block hash tree from the remote server,
834 # since the hash of each share of the file is the entire block
835 # hash tree, and is a leaf in the share hash tree. This is fine,
836 # since any share corruption will be detected in the share hash
839 self.log("getting blockhashes for segment %d, share %d: %s" % \
840 (segnum, reader.shnum, str(needed)))
841 d1 = reader.get_blockhashes(needed, force_remote=True)
842 if self.share_hash_tree.needed_hashes(reader.shnum):
843 need = self.share_hash_tree.needed_hashes(reader.shnum)
844 self.log("also need sharehashes for share %d: %s" % (reader.shnum,
846 d2 = reader.get_sharehashes(need, force_remote=True)
848 d2 = defer.succeed({}) # the logic in the next method
850 dl = defer.DeferredList([d1, d2], consumeErrors=True)
854 def _decode_blocks(self, blocks_and_salts, segnum):
856 I take a list of k blocks and salts, and decode that into a
857 single encrypted segment.
860 # We want to merge our dictionaries to the form
861 # {shnum: blocks_and_salts}
863 # The dictionaries come from validate block that way, so we just
864 # need to merge them.
865 for block_and_salt in blocks_and_salts:
866 d.update(block_and_salt[1])
868 # All of these blocks should have the same salt; in SDMF, it is
869 # the file-wide IV, while in MDMF it is the per-segment salt. In
870 # either case, we just need to get one of them and use it.
872 # d.items()[0] is like (shnum, (block, salt))
873 # d.items()[0][1] is like (block, salt)
874 # d.items()[0][1][1] is the salt.
875 salt = d.items()[0][1][1]
876 # Next, extract just the blocks from the dict. We'll use the
877 # salt in the next step.
878 share_and_shareids = [(k, v[0]) for k, v in d.items()]
879 d2 = dict(share_and_shareids)
882 for shareid, share in d2.items():
883 shareids.append(shareid)
886 self._set_current_status("decoding")
887 started = time.time()
888 assert len(shareids) >= self._required_shares, len(shareids)
889 # zfec really doesn't want extra shares
890 shareids = shareids[:self._required_shares]
891 shares = shares[:self._required_shares]
892 self.log("decoding segment %d" % segnum)
893 if segnum == self._num_segments - 1:
894 d = defer.maybeDeferred(self._tail_decoder.decode, shares, shareids)
896 d = defer.maybeDeferred(self._segment_decoder.decode, shares, shareids)
897 def _process(buffers):
898 segment = "".join(buffers)
899 self.log(format="now decoding segment %(segnum)s of %(numsegs)s",
901 numsegs=self._num_segments,
903 self.log(" joined length %d, datalength %d" %
904 (len(segment), self._data_length))
905 if segnum == self._num_segments - 1:
906 size_to_use = self._tail_data_size
908 size_to_use = self._segment_size
909 segment = segment[:size_to_use]
910 self.log(" segment len=%d" % len(segment))
911 self._status.accumulate_decode_time(time.time() - started)
913 d.addCallback(_process)
917 def _decrypt_segment(self, segment_and_salt):
919 I take a single segment and its salt, and decrypt it. I return
920 the plaintext of the segment that is in my argument.
922 segment, salt = segment_and_salt
923 self._set_current_status("decrypting")
924 self.log("decrypting segment %d" % self._current_segment)
925 started = time.time()
926 key = hashutil.ssk_readkey_data_hash(salt, self._node.get_readkey())
928 plaintext = decryptor.process(segment)
929 self._status.accumulate_decrypt_time(time.time() - started)
933 def notify_server_corruption(self, peerid, shnum, reason):
934 ss = self.servermap.connections[peerid]
935 ss.callRemoteOnly("advise_corrupt_share",
936 "mutable", self._storage_index, shnum, reason)
939 def _try_to_validate_privkey(self, enc_privkey, reader):
940 alleged_privkey_s = self._node._decrypt_privkey(enc_privkey)
941 alleged_writekey = hashutil.ssk_writekey_hash(alleged_privkey_s)
942 if alleged_writekey != self._node.get_writekey():
943 self.log("invalid privkey from %s shnum %d" %
944 (reader, reader.shnum),
945 level=log.WEIRD, umid="YIw4tA")
947 self.servermap.mark_bad_share(reader.peerid, reader.shnum,
949 e = CorruptShareError(reader.peerid,
952 f = failure.Failure(e)
953 self._bad_shares.add((reader.peerid, reader.shnum, f))
957 self.log("got valid privkey from shnum %d on reader %s" %
958 (reader.shnum, reader))
959 privkey = rsa.create_signing_key_from_string(alleged_privkey_s)
960 self._node._populate_encprivkey(enc_privkey)
961 self._node._populate_privkey(privkey)
962 self._need_privkey = False
968 I am called by _download_current_segment when the download process
969 has finished successfully. After making some useful logging
970 statements, I return the decrypted contents to the owner of this
971 Retrieve object through self._done_deferred.
973 self._running = False
974 self._status.set_active(False)
976 self._status.timings['total'] = now - self._started
977 self._status.timings['fetch'] = now - self._started_fetching
978 self._status.set_status("Finished")
979 self._status.set_progress(1.0)
981 # remember the encoding parameters, use them again next time
982 (seqnum, root_hash, IV, segsize, datalength, k, N, prefix,
983 offsets_tuple) = self.verinfo
984 self._node._populate_required_shares(k)
985 self._node._populate_total_shares(N)
988 ret = list(self._bad_shares)
989 self.log("done verifying, found %d bad shares" % len(ret))
991 # TODO: upload status here?
993 self._consumer.unregisterProducer()
994 eventually(self._done_deferred.callback, ret)
997 def _raise_notenoughshareserror(self):
999 I am called by _activate_enough_peers when there are not enough
1000 active peers left to complete the download. After making some
1001 useful logging statements, I throw an exception to that effect
1002 to the caller of this Retrieve object through
1003 self._done_deferred.
1006 format = ("ran out of peers: "
1007 "have %(have)d of %(total)d segments "
1008 "found %(bad)d bad shares "
1009 "encoding %(k)d-of-%(n)d")
1010 args = {"have": self._current_segment,
1011 "total": self._num_segments,
1012 "need": self._last_segment,
1013 "k": self._required_shares,
1014 "n": self._total_shares,
1015 "bad": len(self._bad_shares)}
1016 raise NotEnoughSharesError("%s, last failure: %s" %
1017 (format % args, str(self._last_failure)))
1019 def _error(self, f):
1020 # all errors, including NotEnoughSharesError, land here
1021 self._running = False
1022 self._status.set_active(False)
1024 self._status.timings['total'] = now - self._started
1025 self._status.timings['fetch'] = now - self._started_fetching
1026 self._status.set_status("Failed")
1027 eventually(self._done_deferred.errback, f)