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["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._pause_deferred = None
148 self._read_length = None
149 self.log("got seqnum %d" % self.verinfo[0])
152 def get_status(self):
155 def log(self, *args, **kwargs):
156 if "parent" not in kwargs:
157 kwargs["parent"] = self._log_number
158 if "facility" not in kwargs:
159 kwargs["facility"] = "tahoe.mutable.retrieve"
160 return log.msg(*args, **kwargs)
162 def _set_current_status(self, state):
163 seg = "%d/%d" % (self._current_segment, self._last_segment)
164 self._status.set_status("segment %s (%s)" % (seg, state))
169 def pauseProducing(self):
171 I am called by my download target if we have produced too much
172 data for it to handle. I make the downloader stop producing new
173 data until my resumeProducing method is called.
175 if self._pause_deferred is not None:
178 # fired when the download is unpaused.
179 self._old_status = self._status.get_status()
180 self._set_current_status("paused")
182 self._pause_deferred = defer.Deferred()
185 def resumeProducing(self):
187 I am called by my download target once it is ready to begin
188 receiving data again.
190 if self._pause_deferred is None:
193 p = self._pause_deferred
194 self._pause_deferred = None
195 self._status.set_status(self._old_status)
197 eventually(p.callback, None)
200 def _check_for_paused(self, res):
202 I am called just before a write to the consumer. I return a
203 Deferred that eventually fires with the data that is to be
204 written to the consumer. If the download has not been paused,
205 the Deferred fires immediately. Otherwise, the Deferred fires
206 when the downloader is unpaused.
208 if self._pause_deferred is not None:
210 self._pause_deferred.addCallback(lambda ignored: d.callback(res))
212 return defer.succeed(res)
215 def download(self, consumer=None, offset=0, size=None):
216 assert IConsumer.providedBy(consumer) or self._verify
219 self._consumer = consumer
220 # we provide IPushProducer, so streaming=True, per
222 self._consumer.registerProducer(self, streaming=True)
224 self._done_deferred = defer.Deferred()
225 self._started = time.time()
226 self._status.set_status("Retrieving Shares")
228 self._offset = offset
229 self._read_length = size
231 # first, which servers can we use?
232 versionmap = self.servermap.make_versionmap()
233 shares = versionmap[self.verinfo]
234 # this sharemap is consumed as we decide to send requests
235 self.remaining_sharemap = DictOfSets()
236 for (shnum, peerid, timestamp) in shares:
237 self.remaining_sharemap.add(shnum, peerid)
238 # If the servermap update fetched anything, it fetched at least 1
239 # KiB, so we ask for that much.
240 # TODO: Change the cache methods to allow us to fetch all of the
241 # data that they have, then change this method to do that.
242 any_cache = self._node._read_from_cache(self.verinfo, shnum,
244 ss = self.servermap.connections[peerid]
245 reader = MDMFSlotReadProxy(ss,
249 reader.peerid = peerid
250 self.readers[shnum] = reader
253 self.shares = {} # maps shnum to validated blocks
254 self._active_readers = [] # list of active readers for this dl.
255 self._validated_readers = set() # set of readers that we have
256 # validated the prefix of
257 self._block_hash_trees = {} # shnum => hashtree
259 # how many shares do we need?
268 offsets_tuple) = self.verinfo
271 # We need one share hash tree for the entire file; its leaves
272 # are the roots of the block hash trees for the shares that
273 # comprise it, and its root is in the verinfo.
274 self.share_hash_tree = hashtree.IncompleteHashTree(N)
275 self.share_hash_tree.set_hashes({0: root_hash})
277 # This will set up both the segment decoder and the tail segment
278 # decoder, as well as a variety of other instance variables that
279 # the download process will use.
280 self._setup_encoding_parameters()
281 assert len(self.remaining_sharemap) >= k
283 self.log("starting download")
284 self._started_fetching = time.time()
286 self._add_active_peers()
288 # The download process beyond this is a state machine.
289 # _add_active_peers will select the peers that we want to use
290 # for the download, and then attempt to start downloading. After
291 # each segment, it will check for doneness, reacting to broken
292 # peers and corrupt shares as necessary. If it runs out of good
293 # peers before downloading all of the segments, _done_deferred
294 # will errback. Otherwise, it will eventually callback with the
295 # contents of the mutable file.
296 return self._done_deferred
299 def decode(self, blocks_and_salts, segnum):
301 I am a helper method that the mutable file update process uses
302 as a shortcut to decode and decrypt the segments that it needs
303 to fetch in order to perform a file update. I take in a
304 collection of blocks and salts, and pick some of those to make a
305 segment with. I return the plaintext associated with that
308 # shnum => block hash tree. Unused, but setup_encoding_parameters will
310 self._block_hash_trees = None
311 self._setup_encoding_parameters()
313 # This is the form expected by decode.
314 blocks_and_salts = blocks_and_salts.items()
315 blocks_and_salts = [(True, [d]) for d in blocks_and_salts]
317 d = self._decode_blocks(blocks_and_salts, segnum)
318 d.addCallback(self._decrypt_segment)
322 def _setup_encoding_parameters(self):
324 I set up the encoding parameters, including k, n, the number
325 of segments associated with this file, and the segment decoder.
335 offsets_tuple) = self.verinfo
336 self._required_shares = k
337 self._total_shares = n
338 self._segment_size = segsize
339 self._data_length = datalength
342 self._version = MDMF_VERSION
344 self._version = SDMF_VERSION
346 if datalength and segsize:
347 self._num_segments = mathutil.div_ceil(datalength, segsize)
348 self._tail_data_size = datalength % segsize
350 self._num_segments = 0
351 self._tail_data_size = 0
353 self._segment_decoder = codec.CRSDecoder()
354 self._segment_decoder.set_params(segsize, k, n)
356 if not self._tail_data_size:
357 self._tail_data_size = segsize
359 self._tail_segment_size = mathutil.next_multiple(self._tail_data_size,
360 self._required_shares)
361 if self._tail_segment_size == self._segment_size:
362 self._tail_decoder = self._segment_decoder
364 self._tail_decoder = codec.CRSDecoder()
365 self._tail_decoder.set_params(self._tail_segment_size,
366 self._required_shares,
369 self.log("got encoding parameters: "
372 "%d segments of %d bytes each (%d byte tail segment)" % \
373 (k, n, self._num_segments, self._segment_size,
374 self._tail_segment_size))
376 if self._block_hash_trees is not None:
377 for i in xrange(self._total_shares):
378 # So we don't have to do this later.
379 self._block_hash_trees[i] = hashtree.IncompleteHashTree(self._num_segments)
381 # Our last task is to tell the downloader where to start and
382 # where to stop. We use three parameters for that:
383 # - self._start_segment: the segment that we need to start
385 # - self._current_segment: the next segment that we need to
387 # - self._last_segment: The last segment that we were asked to
390 # We say that the download is complete when
391 # self._current_segment > self._last_segment. We use
392 # self._start_segment and self._last_segment to know when to
393 # strip things off of segments, and how much to strip.
395 self.log("got offset: %d" % self._offset)
396 # our start segment is the first segment containing the
397 # offset we were given.
398 start = self._offset // self._segment_size
400 assert start < self._num_segments
401 self._start_segment = start
402 self.log("got start segment: %d" % self._start_segment)
404 self._start_segment = 0
407 # If self._read_length is None, then we want to read the whole
408 # file. Otherwise, we want to read only part of the file, and
409 # need to figure out where to stop reading.
410 if self._read_length is not None:
411 # our end segment is the last segment containing part of the
412 # segment that we were asked to read.
413 self.log("got read length %d" % self._read_length)
414 if self._read_length != 0:
415 end_data = self._offset + self._read_length
417 # We don't actually need to read the byte at end_data,
418 # but the one before it.
419 end = (end_data - 1) // self._segment_size
421 assert end < self._num_segments
422 self._last_segment = end
424 self._last_segment = self._start_segment
425 self.log("got end segment: %d" % self._last_segment)
427 self._last_segment = self._num_segments - 1
429 self._current_segment = self._start_segment
431 def _add_active_peers(self):
433 I populate self._active_readers with enough active readers to
434 retrieve the contents of this mutable file. I am called before
435 downloading starts, and (eventually) after each validation
436 error, connection error, or other problem in the download.
438 # TODO: It would be cool to investigate other heuristics for
439 # reader selection. For instance, the cost (in time the user
440 # spends waiting for their file) of selecting a really slow peer
441 # that happens to have a primary share is probably more than
442 # selecting a really fast peer that doesn't have a primary
443 # share. Maybe the servermap could be extended to provide this
444 # information; it could keep track of latency information while
445 # it gathers more important data, and then this routine could
446 # use that to select active readers.
448 # (these and other questions would be easier to answer with a
449 # robust, configurable tahoe-lafs simulator, which modeled node
450 # failures, differences in node speed, and other characteristics
451 # that we expect storage servers to have. You could have
452 # presets for really stable grids (like allmydata.com),
453 # friendnets, make it easy to configure your own settings, and
454 # then simulate the effect of big changes on these use cases
455 # instead of just reasoning about what the effect might be. Out
456 # of scope for MDMF, though.)
458 # We need at least self._required_shares readers to download a
461 needed = self._total_shares
463 needed = self._required_shares - len(self._active_readers)
464 # XXX: Why don't format= log messages work here?
465 self.log("adding %d peers to the active peers list" % needed)
467 # We favor lower numbered shares, since FEC is faster with
468 # primary shares than with other shares, and lower-numbered
469 # shares are more likely to be primary than higher numbered
471 active_shnums = set(sorted(self.remaining_sharemap.keys()))
472 # We shouldn't consider adding shares that we already have; this
473 # will cause problems later.
474 active_shnums -= set([reader.shnum for reader in self._active_readers])
475 active_shnums = list(active_shnums)[:needed]
476 if len(active_shnums) < needed and not self._verify:
477 # We don't have enough readers to retrieve the file; fail.
478 return self._failed()
480 for shnum in active_shnums:
481 self._active_readers.append(self.readers[shnum])
482 self.log("added reader for share %d" % shnum)
483 assert len(self._active_readers) >= self._required_shares
484 # Conceptually, this is part of the _add_active_peers step. It
485 # validates the prefixes of newly added readers to make sure
486 # that they match what we are expecting for self.verinfo. If
487 # validation is successful, _validate_active_prefixes will call
488 # _download_current_segment for us. If validation is
489 # unsuccessful, then _validate_prefixes will remove the peer and
490 # call _add_active_peers again, where we will attempt to rectify
491 # the problem by choosing another peer.
492 return self._validate_active_prefixes()
495 def _validate_active_prefixes(self):
497 I check to make sure that the prefixes on the peers that I am
498 currently reading from match the prefix that we want to see, as
499 said in self.verinfo.
501 If I find that all of the active peers have acceptable prefixes,
502 I pass control to _download_current_segment, which will use
503 those peers to do cool things. If I find that some of the active
504 peers have unacceptable prefixes, I will remove them from active
505 peers (and from further consideration) and call
506 _add_active_peers to attempt to rectify the situation. I keep
507 track of which peers I have already validated so that I don't
510 assert self._active_readers, "No more active readers"
513 new_readers = set(self._active_readers) - self._validated_readers
514 self.log('validating %d newly-added active readers' % len(new_readers))
516 for reader in new_readers:
517 # We force a remote read here -- otherwise, we are relying
518 # on cached data that we already verified as valid, and we
519 # won't detect an uncoordinated write that has occurred
520 # since the last servermap update.
521 d = reader.get_prefix(force_remote=True)
522 d.addCallback(self._try_to_validate_prefix, reader)
524 dl = defer.DeferredList(ds, consumeErrors=True)
525 def _check_results(results):
526 # Each result in results will be of the form (success, msg).
527 # We don't care about msg, but success will tell us whether
528 # or not the checkstring validated. If it didn't, we need to
529 # remove the offending (peer,share) from our active readers,
530 # and ensure that active readers is again populated.
532 for i, result in enumerate(results):
534 reader = self._active_readers[i]
536 assert isinstance(f, failure.Failure)
538 self.log("The reader %s failed to "
539 "properly validate: %s" % \
540 (reader, str(f.value)))
541 bad_readers.append((reader, f))
543 reader = self._active_readers[i]
544 self.log("the reader %s checks out, so we'll use it" % \
546 self._validated_readers.add(reader)
547 # Each time we validate a reader, we check to see if
548 # we need the private key. If we do, we politely ask
549 # for it and then continue computing. If we find
550 # that we haven't gotten it at the end of
551 # segment decoding, then we'll take more drastic
553 if self._need_privkey and not self._node.is_readonly():
554 d = reader.get_encprivkey()
555 d.addCallback(self._try_to_validate_privkey, reader)
557 # We do them all at once, or else we screw up list indexing.
558 for (reader, f) in bad_readers:
559 self._mark_bad_share(reader, f)
561 if len(self._active_readers) >= self._required_shares:
562 return self._download_current_segment()
564 return self._failed()
566 return self._add_active_peers()
568 return self._download_current_segment()
569 # The next step will assert that it has enough active
570 # readers to fetch shares; we just need to remove it.
571 dl.addCallback(_check_results)
575 def _try_to_validate_prefix(self, prefix, reader):
577 I check that the prefix returned by a candidate server for
578 retrieval matches the prefix that the servermap knows about
579 (and, hence, the prefix that was validated earlier). If it does,
580 I return True, which means that I approve of the use of the
581 candidate server for segment retrieval. If it doesn't, I return
582 False, which means that another server must be chosen.
592 offsets_tuple) = self.verinfo
593 if known_prefix != prefix:
594 self.log("prefix from share %d doesn't match" % reader.shnum)
595 raise UncoordinatedWriteError("Mismatched prefix -- this could "
596 "indicate an uncoordinated write")
597 # Otherwise, we're okay -- no issues.
600 def _remove_reader(self, reader):
602 At various points, we will wish to remove a peer from
603 consideration and/or use. These include, but are not necessarily
606 - A connection error.
607 - A mismatched prefix (that is, a prefix that does not match
608 our conception of the version information string).
609 - A failing block hash, salt hash, or share hash, which can
610 indicate disk failure/bit flips, or network trouble.
612 This method will do that. I will make sure that the
613 (shnum,reader) combination represented by my reader argument is
614 not used for anything else during this download. I will not
615 advise the reader of any corruption, something that my callers
616 may wish to do on their own.
618 # TODO: When you're done writing this, see if this is ever
619 # actually used for something that _mark_bad_share isn't. I have
620 # a feeling that they will be used for very similar things, and
621 # that having them both here is just going to be an epic amount
622 # of code duplication.
624 # (well, okay, not epic, but meaningful)
625 self.log("removing reader %s" % reader)
626 # Remove the reader from _active_readers
627 self._active_readers.remove(reader)
628 # TODO: self.readers.remove(reader)?
629 for shnum in list(self.remaining_sharemap.keys()):
630 self.remaining_sharemap.discard(shnum, reader.peerid)
633 def _mark_bad_share(self, reader, f):
635 I mark the (peerid, shnum) encapsulated by my reader argument as
636 a bad share, which means that it will not be used anywhere else.
638 There are several reasons to want to mark something as a bad
639 share. These include:
641 - A connection error to the peer.
642 - A mismatched prefix (that is, a prefix that does not match
643 our local conception of the version information string).
644 - A failing block hash, salt hash, share hash, or other
647 This method will ensure that readers that we wish to mark bad
648 (for these reasons or other reasons) are not used for the rest
649 of the download. Additionally, it will attempt to tell the
650 remote peer (with no guarantee of success) that its share is
653 self.log("marking share %d on server %s as bad" % \
654 (reader.shnum, reader))
655 prefix = self.verinfo[-2]
656 self.servermap.mark_bad_share(reader.peerid,
659 self._remove_reader(reader)
660 self._bad_shares.add((reader.peerid, reader.shnum, f))
661 self._status.problems[reader.peerid] = f
662 self._last_failure = f
663 self.notify_server_corruption(reader.peerid, reader.shnum,
667 def _download_current_segment(self):
669 I download, validate, decode, decrypt, and assemble the segment
670 that this Retrieve is currently responsible for downloading.
672 assert len(self._active_readers) >= self._required_shares
673 if self._current_segment <= self._last_segment:
674 d = self._process_segment(self._current_segment)
676 d = defer.succeed(None)
677 d.addBoth(self._turn_barrier)
678 d.addCallback(self._check_for_done)
682 def _turn_barrier(self, result):
684 I help the download process avoid the recursion limit issues
687 return fireEventually(result)
690 def _process_segment(self, segnum):
692 I download, validate, decode, and decrypt one segment of the
693 file that this Retrieve is retrieving. This means coordinating
694 the process of getting k blocks of that file, validating them,
695 assembling them into one segment with the decoder, and then
698 self.log("processing segment %d" % segnum)
700 # TODO: The old code uses a marker. Should this code do that
701 # too? What did the Marker do?
702 assert len(self._active_readers) >= self._required_shares
704 # We need to ask each of our active readers for its block and
705 # salt. We will then validate those. If validation is
706 # successful, we will assemble the results into plaintext.
708 for reader in self._active_readers:
709 started = time.time()
710 d = reader.get_block_and_salt(segnum, queue=True)
711 d2 = self._get_needed_hashes(reader, segnum)
712 dl = defer.DeferredList([d, d2], consumeErrors=True)
713 dl.addCallback(self._validate_block, segnum, reader, started)
714 dl.addErrback(self._validation_or_decoding_failed, [reader])
717 dl = defer.DeferredList(ds)
719 dl.addCallback(lambda ignored: "")
720 dl.addCallback(self._set_segment)
722 dl.addCallback(self._maybe_decode_and_decrypt_segment, segnum)
726 def _maybe_decode_and_decrypt_segment(self, blocks_and_salts, segnum):
728 I take the results of fetching and validating the blocks from a
729 callback chain in another method. If the results are such that
730 they tell me that validation and fetching succeeded without
731 incident, I will proceed with decoding and decryption.
732 Otherwise, I will do nothing.
734 self.log("trying to decode and decrypt segment %d" % segnum)
736 for block_and_salt in blocks_and_salts:
737 if not block_and_salt[0] or block_and_salt[1] == None:
738 self.log("some validation operations failed; not proceeding")
742 self.log("everything looks ok, building segment %d" % segnum)
743 d = self._decode_blocks(blocks_and_salts, segnum)
744 d.addCallback(self._decrypt_segment)
745 d.addErrback(self._validation_or_decoding_failed,
746 self._active_readers)
747 # check to see whether we've been paused before writing
749 d.addCallback(self._check_for_paused)
750 d.addCallback(self._set_segment)
753 return defer.succeed(None)
756 def _set_segment(self, segment):
758 Given a plaintext segment, I register that segment with the
759 target that is handling the file download.
761 self.log("got plaintext for segment %d" % self._current_segment)
762 if self._current_segment == self._start_segment:
763 # We're on the first segment. It's possible that we want
764 # only some part of the end of this segment, and that we
765 # just downloaded the whole thing to get that part. If so,
766 # we need to account for that and give the reader just the
767 # data that they want.
768 n = self._offset % self._segment_size
769 self.log("stripping %d bytes off of the first segment" % n)
770 self.log("original segment length: %d" % len(segment))
771 segment = segment[n:]
772 self.log("new segment length: %d" % len(segment))
774 if self._current_segment == self._last_segment and self._read_length is not None:
775 # We're on the last segment. It's possible that we only want
776 # part of the beginning of this segment, and that we
777 # downloaded the whole thing anyway. Make sure to give the
778 # caller only the portion of the segment that they want to
780 extra = self._read_length
781 if self._start_segment != self._last_segment:
782 extra -= self._segment_size - \
783 (self._offset % self._segment_size)
784 extra %= self._segment_size
785 self.log("original segment length: %d" % len(segment))
786 segment = segment[:extra]
787 self.log("new segment length: %d" % len(segment))
788 self.log("only taking %d bytes of the last segment" % extra)
791 self._consumer.write(segment)
793 # we don't care about the plaintext if we are doing a verify.
795 self._current_segment += 1
798 def _validation_or_decoding_failed(self, f, readers):
800 I am called when a block or a salt fails to correctly validate, or when
801 the decryption or decoding operation fails for some reason. I react to
802 this failure by notifying the remote server of corruption, and then
803 removing the remote peer from further activity.
805 assert isinstance(readers, list)
806 bad_shnums = [reader.shnum for reader in readers]
808 self.log("validation or decoding failed on share(s) %s, peer(s) %s "
809 ", segment %d: %s" % \
810 (bad_shnums, readers, self._current_segment, str(f)))
811 for reader in readers:
812 self._mark_bad_share(reader, f)
816 def _validate_block(self, results, segnum, reader, started):
818 I validate a block from one share on a remote server.
820 # Grab the part of the block hash tree that is necessary to
821 # validate this block, then generate the block hash root.
822 self.log("validating share %d for segment %d" % (reader.shnum,
824 elapsed = time.time() - started
825 self._status.add_fetch_timing(reader.peerid, elapsed)
826 self._set_current_status("validating blocks")
827 # Did we fail to fetch either of the things that we were
828 # supposed to? Fail if so.
829 if not results[0][0] and results[1][0]:
830 # handled by the errback handler.
832 # These all get batched into one query, so the resulting
833 # failure should be the same for all of them, so we can just
835 assert isinstance(results[0][1], failure.Failure)
838 raise CorruptShareError(reader.peerid,
840 "Connection error: %s" % str(f))
842 block_and_salt, block_and_sharehashes = results
843 block, salt = block_and_salt[1]
844 blockhashes, sharehashes = block_and_sharehashes[1]
846 blockhashes = dict(enumerate(blockhashes[1]))
847 self.log("the reader gave me the following blockhashes: %s" % \
849 self.log("the reader gave me the following sharehashes: %s" % \
850 sharehashes[1].keys())
851 bht = self._block_hash_trees[reader.shnum]
853 if bht.needed_hashes(segnum, include_leaf=True):
855 bht.set_hashes(blockhashes)
856 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
858 raise CorruptShareError(reader.peerid,
860 "block hash tree failure: %s" % e)
862 if self._version == MDMF_VERSION:
863 blockhash = hashutil.block_hash(salt + block)
865 blockhash = hashutil.block_hash(block)
866 # If this works without an error, then validation is
869 bht.set_hashes(leaves={segnum: blockhash})
870 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
872 raise CorruptShareError(reader.peerid,
874 "block hash tree failure: %s" % e)
876 # Reaching this point means that we know that this segment
877 # is correct. Now we need to check to see whether the share
878 # hash chain is also correct.
879 # SDMF wrote share hash chains that didn't contain the
880 # leaves, which would be produced from the block hash tree.
881 # So we need to validate the block hash tree first. If
882 # successful, then bht[0] will contain the root for the
883 # shnum, which will be a leaf in the share hash tree, which
884 # will allow us to validate the rest of the tree.
885 if self.share_hash_tree.needed_hashes(reader.shnum,
886 include_leaf=True) or \
889 self.share_hash_tree.set_hashes(hashes=sharehashes[1],
890 leaves={reader.shnum: bht[0]})
891 except (hashtree.BadHashError, hashtree.NotEnoughHashesError, \
893 raise CorruptShareError(reader.peerid,
895 "corrupt hashes: %s" % e)
897 self.log('share %d is valid for segment %d' % (reader.shnum,
899 return {reader.shnum: (block, salt)}
902 def _get_needed_hashes(self, reader, segnum):
904 I get the hashes needed to validate segnum from the reader, then return
905 to my caller when this is done.
907 bht = self._block_hash_trees[reader.shnum]
908 needed = bht.needed_hashes(segnum, include_leaf=True)
909 # The root of the block hash tree is also a leaf in the share
910 # hash tree. So we don't need to fetch it from the remote
911 # server. In the case of files with one segment, this means that
912 # we won't fetch any block hash tree from the remote server,
913 # since the hash of each share of the file is the entire block
914 # hash tree, and is a leaf in the share hash tree. This is fine,
915 # since any share corruption will be detected in the share hash
918 self.log("getting blockhashes for segment %d, share %d: %s" % \
919 (segnum, reader.shnum, str(needed)))
920 d1 = reader.get_blockhashes(needed, queue=True, force_remote=True)
921 if self.share_hash_tree.needed_hashes(reader.shnum):
922 need = self.share_hash_tree.needed_hashes(reader.shnum)
923 self.log("also need sharehashes for share %d: %s" % (reader.shnum,
925 d2 = reader.get_sharehashes(need, queue=True, force_remote=True)
927 d2 = defer.succeed({}) # the logic in the next method
929 dl = defer.DeferredList([d1, d2], consumeErrors=True)
933 def _decode_blocks(self, blocks_and_salts, segnum):
935 I take a list of k blocks and salts, and decode that into a
936 single encrypted segment.
939 # We want to merge our dictionaries to the form
940 # {shnum: blocks_and_salts}
942 # The dictionaries come from validate block that way, so we just
943 # need to merge them.
944 for block_and_salt in blocks_and_salts:
945 d.update(block_and_salt[1])
947 # All of these blocks should have the same salt; in SDMF, it is
948 # the file-wide IV, while in MDMF it is the per-segment salt. In
949 # either case, we just need to get one of them and use it.
951 # d.items()[0] is like (shnum, (block, salt))
952 # d.items()[0][1] is like (block, salt)
953 # d.items()[0][1][1] is the salt.
954 salt = d.items()[0][1][1]
955 # Next, extract just the blocks from the dict. We'll use the
956 # salt in the next step.
957 share_and_shareids = [(k, v[0]) for k, v in d.items()]
958 d2 = dict(share_and_shareids)
961 for shareid, share in d2.items():
962 shareids.append(shareid)
965 self._set_current_status("decoding")
966 started = time.time()
967 assert len(shareids) >= self._required_shares, len(shareids)
968 # zfec really doesn't want extra shares
969 shareids = shareids[:self._required_shares]
970 shares = shares[:self._required_shares]
971 self.log("decoding segment %d" % segnum)
972 if segnum == self._num_segments - 1:
973 d = defer.maybeDeferred(self._tail_decoder.decode, shares, shareids)
975 d = defer.maybeDeferred(self._segment_decoder.decode, shares, shareids)
976 def _process(buffers):
977 segment = "".join(buffers)
978 self.log(format="now decoding segment %(segnum)s of %(numsegs)s",
980 numsegs=self._num_segments,
982 self.log(" joined length %d, datalength %d" %
983 (len(segment), self._data_length))
984 if segnum == self._num_segments - 1:
985 size_to_use = self._tail_data_size
987 size_to_use = self._segment_size
988 segment = segment[:size_to_use]
989 self.log(" segment len=%d" % len(segment))
990 self._status.accumulate_decode_time(time.time() - started)
992 d.addCallback(_process)
996 def _decrypt_segment(self, segment_and_salt):
998 I take a single segment and its salt, and decrypt it. I return
999 the plaintext of the segment that is in my argument.
1001 segment, salt = segment_and_salt
1002 self._set_current_status("decrypting")
1003 self.log("decrypting segment %d" % self._current_segment)
1004 started = time.time()
1005 key = hashutil.ssk_readkey_data_hash(salt, self._node.get_readkey())
1006 decryptor = AES(key)
1007 plaintext = decryptor.process(segment)
1008 self._status.accumulate_decrypt_time(time.time() - started)
1012 def notify_server_corruption(self, peerid, shnum, reason):
1013 ss = self.servermap.connections[peerid]
1014 ss.callRemoteOnly("advise_corrupt_share",
1015 "mutable", self._storage_index, shnum, reason)
1018 def _try_to_validate_privkey(self, enc_privkey, reader):
1019 alleged_privkey_s = self._node._decrypt_privkey(enc_privkey)
1020 alleged_writekey = hashutil.ssk_writekey_hash(alleged_privkey_s)
1021 if alleged_writekey != self._node.get_writekey():
1022 self.log("invalid privkey from %s shnum %d" %
1023 (reader, reader.shnum),
1024 level=log.WEIRD, umid="YIw4tA")
1026 self.servermap.mark_bad_share(reader.peerid, reader.shnum,
1028 e = CorruptShareError(reader.peerid,
1031 f = failure.Failure(e)
1032 self._bad_shares.add((reader.peerid, reader.shnum, f))
1036 self.log("got valid privkey from shnum %d on reader %s" %
1037 (reader.shnum, reader))
1038 privkey = rsa.create_signing_key_from_string(alleged_privkey_s)
1039 self._node._populate_encprivkey(enc_privkey)
1040 self._node._populate_privkey(privkey)
1041 self._need_privkey = False
1044 def _check_for_done(self, res):
1046 I check to see if this Retrieve object has successfully finished
1049 I can exit in the following ways:
1050 - If there are no more segments to download, then I exit by
1051 causing self._done_deferred to fire with the plaintext
1052 content requested by the caller.
1053 - If there are still segments to be downloaded, and there
1054 are enough active readers (readers which have not broken
1055 and have not given us corrupt data) to continue
1056 downloading, I send control back to
1057 _download_current_segment.
1058 - If there are still segments to be downloaded but there are
1059 not enough active peers to download them, I ask
1060 _add_active_peers to add more peers. If it is successful,
1061 it will call _download_current_segment. If there are not
1062 enough peers to retrieve the file, then that will cause
1063 _done_deferred to errback.
1065 self.log("checking for doneness")
1066 if self._current_segment > self._last_segment:
1067 # No more segments to download, we're done.
1068 self.log("got plaintext, done")
1071 if len(self._active_readers) >= self._required_shares:
1072 # More segments to download, but we have enough good peers
1073 # in self._active_readers that we can do that without issue,
1074 # so go nab the next segment.
1075 self.log("not done yet: on segment %d of %d" % \
1076 (self._current_segment + 1, self._num_segments))
1077 return self._download_current_segment()
1079 self.log("not done yet: on segment %d of %d, need to add peers" % \
1080 (self._current_segment + 1, self._num_segments))
1081 return self._add_active_peers()
1086 I am called by _check_for_done when the download process has
1087 finished successfully. After making some useful logging
1088 statements, I return the decrypted contents to the owner of this
1089 Retrieve object through self._done_deferred.
1091 self._running = False
1092 self._status.set_active(False)
1094 self._status.timings['total'] = now - self._started
1095 self._status.timings['fetch'] = now - self._started_fetching
1096 self._status.set_status("Finished")
1097 self._status.set_progress(1.0)
1099 # remember the encoding parameters, use them again next time
1100 (seqnum, root_hash, IV, segsize, datalength, k, N, prefix,
1101 offsets_tuple) = self.verinfo
1102 self._node._populate_required_shares(k)
1103 self._node._populate_total_shares(N)
1106 ret = list(self._bad_shares)
1107 self.log("done verifying, found %d bad shares" % len(ret))
1109 # TODO: upload status here?
1110 ret = self._consumer
1111 self._consumer.unregisterProducer()
1112 eventually(self._done_deferred.callback, ret)
1117 I am called by _add_active_peers when there are not enough
1118 active peers left to complete the download. After making some
1119 useful logging statements, I return an exception to that effect
1120 to the caller of this Retrieve object through
1121 self._done_deferred.
1123 self._running = False
1124 self._status.set_active(False)
1126 self._status.timings['total'] = now - self._started
1127 self._status.timings['fetch'] = now - self._started_fetching
1128 self._status.set_status("Failed")
1131 ret = list(self._bad_shares)
1133 format = ("ran out of peers: "
1134 "have %(have)d of %(total)d segments "
1135 "found %(bad)d bad shares "
1136 "encoding %(k)d-of-%(n)d")
1137 args = {"have": self._current_segment,
1138 "total": self._num_segments,
1139 "need": self._last_segment,
1140 "k": self._required_shares,
1141 "n": self._total_shares,
1142 "bad": len(self._bad_shares)}
1143 e = NotEnoughSharesError("%s, last failure: %s" % \
1144 (format % args, str(self._last_failure)))
1145 f = failure.Failure(e)
1147 eventually(self._done_deferred.callback, ret)