* stop using IURI as an adapter
* pass cap strings around instead of URI instances
* move filenode/dirnode creation duties from Client to new NodeMaker class
* move other Client duties to KeyGenerator, SecretHolder, History classes
* stop passing Client reference to dirnode/filenode constructors
- pass less-powerful references instead, like StorageBroker or Uploader
* always create DirectoryNodes by wrapping a filenode (mutable for now)
* remove some specialized mock classes from unit tests
Detailed list of changes (done one at a time, then merged together)
always pass a string to create_node_from_uri(), not an IURI instance
always pass a string to IFilesystemNode constructors, not an IURI instance
stop using IURI() as an adapter, switch on cap prefix in create_node_from_uri()
client.py: move SecretHolder code out to a separate class
test_web.py: hush pyflakes
client.py: move NodeMaker functionality out into a separate object
LiteralFileNode: stop storing a Client reference
immutable Checker: remove Client reference, it only needs a SecretHolder
immutable Upload: remove Client reference, leave SecretHolder and StorageBroker
immutable Repairer: replace Client reference with StorageBroker and SecretHolder
immutable FileNode: remove Client reference
mutable.Publish: stop passing Client
mutable.ServermapUpdater: get StorageBroker in constructor, not by peeking into Client reference
MutableChecker: reference StorageBroker and History directly, not through Client
mutable.FileNode: removed unused indirection to checker classes
mutable.FileNode: remove Client reference
client.py: move RSA key generation into a separate class, so it can be passed to the nodemaker
move create_mutable_file() into NodeMaker
test_dirnode.py: stop using FakeClient mockups, use NoNetworkGrid instead. This simplifies the code, but takes longer to run (17s instead of 6s). This should come down later when other cleanups make it possible to use simpler (non-RSA) fake mutable files for dirnode tests.
test_mutable.py: clean up basedir names
client.py: move create_empty_dirnode() into NodeMaker
dirnode.py: get rid of DirectoryNode.create
remove DirectoryNode.init_from_uri, refactor NodeMaker for customization, simplify test_web's mock Client to match
stop passing Client to DirectoryNode, make DirectoryNode.create_with_mutablefile the normal DirectoryNode constructor, start removing client from NodeMaker
remove Client from NodeMaker
move helper status into History, pass History to web.Status instead of Client
test_mutable.py: fix minor typo
we actually exercise during tests) into more specific exceptions, so they
don't get optimized away. The best rule to follow is probably this: if an
exception is worth testing, then it's part of the API, and AssertionError
should never be part of the API. Closes#749.
The idea is that future versions of Tahoe will add new URI types that this
version won't recognize, but might store them in directories that we *can*
read. We should handle these "objects from the future" as best we can.
Previous releases of Tahoe would just explode. With this change, we'll
continue to be able to work with everything else in the directory.
The code change is to wrap anything we don't recognize as an UnknownNode
instance (as opposed to a FileNode or DirectoryNode). Then webapi knows how
to render these (mostly by leaving fields blank), deep-check knows to skip
over them, deep-stats counts them in "count-unknown". You can rename and
delete these things, but you can't add new ones (because we wouldn't know how
to generate a readcap to put into the dirnode's rocap slot, and because this
lets us catch typos better).
and deny the Helper the ability to mount a partial-information-guessing
attack. This will probably break compatibility between new clients and very
old (pre-1.0) helpers.
This implements an immutable repairer by marrying a CiphertextDownloader to a CHKUploader. It extends the IDownloadTarget interface so that the downloader can provide some metadata that the uploader requires.
The processing is incremental -- it uploads the first segments before it finishes downloading the whole file. This is necessary so that you can repair large files without running out of RAM or using a temporary file on the repairer.
It requires only a verifycap, not a readcap. That is: it doesn't need or use the decryption key, only the integrity check codes.
There are several tests marked TODO and several instances of XXX in the source code. I intend to open tickets to document further improvements to functionality and testing, but the current version is probably good enough for Tahoe-1.3.0.
It used to be a map from shnum to a string saying "placed this share on XYZ server". The new definition is more in keeping with the "sharemap" object that results from immutable file checking and repair, and it is more useful to the repairer, which is a consumer of immutable upload results.
Rename "downloadable" to "target".
Rename "u" to "v" in FileDownloader.__init__().
Rename "_uri" to "_verifycap" in FileDownloader.
Rename "_downloadable" to "_target" in FileDownloader.
Rename "FileDownloader" to "CiphertextDownloader".
This makes Uploader take an EncryptedUploadable object instead of an Uploadable object. I also changed it to return a verify cap instead of a tuple of the bits of data that one finds in a verify cap.
This will facilitate hooking together an Uploader and a Downloader to make a Repairer.
Also move offloaded.py into src/allmydata/immutable/.
The code for validating the share hash tree and the block hash tree has been rewritten to make sure it handles all cases, to share metadata about the file (such as the share hash tree, block hash trees, and UEB) among different share downloads, and not to require hashes to be stored on the server unnecessarily, such as the roots of the block hash trees (not needed since they are also the leaves of the share hash tree), and the root of the share hash tree (not needed since it is also included in the UEB). It also passes the latest tests including handling corrupted shares well.
ValidatedReadBucketProxy takes a share_hash_tree argument to its constructor, which is a reference to a share hash tree shared by all ValidatedReadBucketProxies for that immutable file download.
ValidatedReadBucketProxy requires the block_size and share_size to be provided in its constructor, and it then uses those to compute the offsets and lengths of blocks when it needs them, instead of reading those values out of the share. The user of ValidatedReadBucketProxy therefore has to have first used a ValidatedExtendedURIProxy to compute those two values from the validated contents of the URI. This is pleasingly simplifies safety analysis: the client knows which span of bytes corresponds to a given block from the validated URI data, rather than from the unvalidated data stored on the storage server. It also simplifies unit testing of verifier/repairer, because now it doesn't care about the contents of the "share size" and "block size" fields in the share. It does not relieve the need for share data v2 layout, because we still need to store and retrieve the offsets of the fields which come after the share data, therefore we still need to use share data v2 with its 8-byte fields if we want to store share data larger than about 2^32.
Specify which subset of the block hashes and share hashes you need while downloading a particular share. In the future this will hopefully be used to fetch only a subset, for network efficiency, but currently all of them are fetched, regardless of which subset you specify.
ReadBucketProxy hides the question of whether it has "started" or not (sent a request to the server to get metadata) from its user.
Download is optimized to do as few roundtrips and as few requests as possible, hopefully speeding up download a bit.
There are a lot of different ways that a share could be corrupted, or that attempting to download it might fail. These tests attempt to exercise many of those ways and require the checker/verifier/repairer to handle each kind of failure well.
I get confused about whether a given argument or return value is a uri-as-string or uri-as-object. This patch adds a lot of assertions that it is one or the other, and also changes CheckerResults to take objects not strings.
In the future, I hope that we generally use Python objects except when importing into or exporting from the Python interpreter e.g. over the wire, the UI, or a stored file.
Refactor into a class the logic of asking each server in turn until one of them gives an answer
that validates. It is called ValidatedThingObtainer.
Refactor the downloading and verification of the URI Extension Block into a class named
ValidatedExtendedURIProxy.
The new logic of validating UEBs is minimalist: it doesn't require the UEB to contain any
unncessary information, but of course it still accepts such information for backwards
compatibility (so that this new download code is able to download files uploaded with old, and
for that matter with current, upload code).
The new logic of validating UEBs follows the practice of doing all validation up front. This
practice advises one to isolate the validation of incoming data into one place, so that all of
the rest of the code can assume only valid data.
If any redundant information is present in the UEB+URI, the new code cross-checks and asserts
that it is all fully consistent. This closes some issues where the uploader could have
uploaded inconsistent redundant data, which would probably have caused the old downloader to
simply reject that download after getting a Python exception, but perhaps could have caused
greater harm to the old downloader.
I removed the notion of selecting an erasure codec from codec.py based on the string that was
passed in the UEB. Currently "crs" is the only such string that works, so
"_assert(codec_name == 'crs')" is simpler and more explicit. This is also in keeping with the
"validate up front" strategy -- now if someone sets a different string than "crs" in their UEB,
the downloader will reject the download in the "validate this UEB" function instead of in a
separate "select the codec instance" function.
I removed the code to check plaintext hashes and plaintext Merkle Trees. Uploaders do not
produce this information any more (since it potentially exposes confidential information about
the file), and the unit tests for it were disabled. The downloader before this patch would
check that plaintext hash or plaintext merkle tree if they were present, but not complain if
they were absent. The new downloader in this patch complains if they are present and doesn't
check them. (We might in the future re-introduce such hashes over the plaintext, but encrypt
the hashes which are stored in the UEB to preserve confidentiality. This would be a double-
check on the correctness of our own source code -- the current Merkle Tree over the ciphertext
is already sufficient to guarantee the integrity of the download unless there is a bug in our
Merkle Tree or AES implementation.)
This patch increases the lines-of-code count by 8 (from 17,770 to 17,778), and reduces the
uncovered-by-tests lines-of-code count by 24 (from 1408 to 1384). Those numbers would be more
meaningful if we omitted src/allmydata/util/ from the test-coverage statistics.
