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".
FileDownloader takes a verify cap and produces ciphertext, instead of taking a read cap and producing plaintext.
FileDownloader does all integrity checking including the mandatory ciphertext hash tree and the optional ciphertext flat hash, rather than expecting its target to do some of that checking.
Rename immutable.download.Output to immutable.download.DecryptingOutput. An instance of DecryptingOutput can be passed to FileDownloader to use as the latter's target. Text pushed to the DecryptingOutput is decrypted and then pushed to *its* target.
DecryptingOutput satisfies the IConsumer interface, and if its target also satisfies IConsumer, then it forwards and pause/unpause signals to its producer (which is the FileDownloader).
This patch also changes some logging code to use the new logging mixin class.
Check integrity of a segment and decrypt the segment one block-sized buffer at a time instead of copying the buffers together into one segment-sized buffer (reduces peak memory usage, I think, and is probably a tad faster/less CPU, depending on your encoding parameters).
Refactor FileDownloader so that processing of segments and of tail-segment share as much code is possible.
FileDownloader and FileNode take caps as instances of URI (Python objects), not as strings.
This was somewhat sad; the assertion didn't say what path caused the
error, what went wrong. So... silently skip over things that are
neither dirs nor files.
pyflakes pointed out to me that I had committed some code that is untested, since it uses an undefined name. This patch exercises that code -- the validation of the ciphertext hash tree -- by corrupting some of the share files in a very specific way, and also fixes the bug.
Once again I inserted a bug into the code, and once again it was hidden by something catching arbitrary exception/failure and assuming that it means the server failed to provide valid data.
We were not making sure that we really got all the crypttext hashes during download. If a server were to return less than the complete set of crypttext hashes, then our subsequent attempt to verify the correctness of the ciphertext would fail. (And it wouldn't be obvious without very careful debugging why it had failed.)
This patch makes it so that you keep trying to get ciphertext hashes until you have a full set or you run out of servers to ask.
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/.
Maybe it already got one of the corrupted hashes from a different server and it doesn't double-check that the hash from every server is correct. Or another problem. But in any case I'm marking this as TODO because an even better (more picky) verifier is less urgent than repairer.
Brian noticed that the constant was wrong, and in fixing that I noticed that we should be saturating instead of modding.
This code would never matter unless a server downgraded or a share migrated from Tahoe >= v1.3.0 to Tahoe < v1.3.0. Even in that case, this bug would never matter unless the share size were exactly 4,294,967,296 bytes long.
Brian, for good reason, wanted this to be spelled "2**32" instead of "4294967296", but I couldn't stand to see a couple of more Python bytecodes interpreted in the middle of a core, frequent operation on the server like immutable share creation.
