from zope.interface import Interface from foolscap.schema import StringConstraint, ListOf, TupleOf, SetOf, DictOf, \ ChoiceOf from foolscap import RemoteInterface, Referenceable HASH_SIZE=32 Hash = StringConstraint(maxLength=HASH_SIZE, minLength=HASH_SIZE)# binary format 32-byte SHA256 hash Nodeid = StringConstraint(maxLength=20, minLength=20) # binary format 20-byte SHA1 hash FURL = StringConstraint(1000) StorageIndex = StringConstraint(16) URI = StringConstraint(300) # kind of arbitrary DirnodeURI = StringConstraint(300, regexp=r'^URI:DIR(-RO)?:pb://[a-z0-9]+@[^/]+/[^:]+:[a-z0-9]+$') MAX_BUCKETS = 200 # per peer # MAX_SEGMENT_SIZE in encode.py is 1 MiB (this constraint allows k = 1) ShareData = StringConstraint(2**20) URIExtensionData = StringConstraint(1000) LeaseRenewSecret = Hash # used to protect bucket lease renewal requests LeaseCancelSecret = Hash # used to protect bucket lease cancellation requests class RIIntroducerClient(RemoteInterface): def new_peers(furls=SetOf(FURL)): return None def set_encoding_parameters(parameters=(int, int, int)): """Advise the client of the recommended k-of-n encoding parameters for this grid. 'parameters' is a tuple of (k, desired, n), where 'n' is the total number of shares that will be created for any given file, while 'k' is the number of shares that must be retrieved to recover that file, and 'desired' is the minimum number of shares that must be placed before the uploader will consider its job a success. n/k is the expansion ratio, while k determines the robustness. Introducers should specify 'n' according to the expected size of the grid (there is no point to producing more shares than there are peers), and k according to the desired reliability-vs-overhead goals. Note that setting k=1 is equivalent to simple replication. """ return None class RIIntroducer(RemoteInterface): def hello(node=RIIntroducerClient, furl=FURL): return None class RIClient(RemoteInterface): def get_versions(): """Return a tuple of (my_version, oldest_supported) strings. Each string can be parsed by an allmydata.util.version.Version instance, and then compared. The first goal is to make sure that nodes are not confused by speaking to an incompatible peer. The second goal is to enable the development of backwards-compatibility code. This method is likely to change in incompatible ways until we get the whole compatibility scheme nailed down. """ return TupleOf(str, str) def get_service(name=str): return Referenceable def get_nodeid(): return Nodeid class RIBucketWriter(RemoteInterface): def write(offset=int, data=ShareData): return None def close(): """ If the data that has been written is incomplete or inconsistent then the server will throw the data away, else it will store it for future retrieval. """ return None class RIBucketReader(RemoteInterface): def read(offset=int, length=int): return ShareData TestVector = ListOf(TupleOf(int, int, str, str)) # elements are (offset, length, operator, specimen) # operator is one of "lt, le, eq, ne, ge, gt" # nop always passes and is used to fetch data while writing. # you should use length==len(specimen) for everything except nop DataVector = ListOf(TupleOf(int, ShareData)) # (offset, data). This limits us to 30 writes of 1MiB each per call TestAndWriteVectorsForShares = DictOf(int, TupleOf(TestVector, DataVector, ChoiceOf(None, int))) # new_length ReadVector = ListOf(TupleOf(int, int)) ReadData = ListOf(ShareData) # returns data[offset:offset+length] for each element of TestVector class RIStorageServer(RemoteInterface): def allocate_buckets(storage_index=StorageIndex, renew_secret=LeaseRenewSecret, cancel_secret=LeaseCancelSecret, sharenums=SetOf(int, maxLength=MAX_BUCKETS), allocated_size=int, canary=Referenceable): """ @param storage_index: the index of the bucket to be created or increfed. @param sharenums: these are the share numbers (probably between 0 and 99) that the sender is proposing to store on this server. @param renew_secret: This is the secret used to protect bucket refresh This secret is generated by the client and stored for later comparison by the server. Each server is given a different secret. @param cancel_secret: Like renew_secret, but protects bucket decref. @param canary: If the canary is lost before close(), the bucket is deleted. @return: tuple of (alreadygot, allocated), where alreadygot is what we already have and is what we hereby agree to accept. New leases are added for shares in both lists. """ return TupleOf(SetOf(int, maxLength=MAX_BUCKETS), DictOf(int, RIBucketWriter, maxKeys=MAX_BUCKETS)) def renew_lease(storage_index=StorageIndex, renew_secret=LeaseRenewSecret): """ Renew the lease on a given bucket. Some networks will use this, some will not. """ def cancel_lease(storage_index=StorageIndex, cancel_secret=LeaseCancelSecret): """ Cancel the lease on a given bucket. If this was the last lease on the bucket, the bucket will be deleted. """ def get_buckets(storage_index=StorageIndex): return DictOf(int, RIBucketReader, maxKeys=MAX_BUCKETS) def slot_readv(storage_index=StorageIndex, shares=ListOf(int), readv=ReadVector): """Read a vector from the numbered shares associated with the given storage index. An empty shares list means to return data from all known shares. Returns a dictionary with one key per share.""" return DictOf(int, ReadData) # shnum -> results def slot_testv_and_readv_and_writev(storage_index=StorageIndex, secrets=TupleOf(Hash, Hash, Hash), tw_vectors=TestAndWriteVectorsForShares, r_vector=ReadVector, ): """General-purpose test-and-set operation for mutable slots. Perform a bunch of comparisons against the existing shares. If they all pass, then apply a bunch of write vectors to those shares. Then use the read vectors to extract data from all the shares and return the data. This method is, um, large. The goal is to allow clients to update all the shares associated with a mutable file in a single round trip. @param storage_index: the index of the bucket to be created or increfed. @param write_enabler: a secret that is stored along with the slot. Writes are accepted from any caller who can present the matching secret. A different secret should be used for each slot*server pair. @param renew_secret: This is the secret used to protect bucket refresh This secret is generated by the client and stored for later comparison by the server. Each server is given a different secret. @param cancel_secret: Like renew_secret, but protects bucket decref. The 'secrets' argument is a tuple of (write_enabler, renew_secret, cancel_secret). The first is required to perform any write. The latter two are used when allocating new shares. To simply acquire a new lease on existing shares, use an empty testv and an empty writev. Each share can have a separate test vector (i.e. a list of comparisons to perform). If all vectors for all shares pass, then all writes for all shares are recorded. Each comparison is a 4-tuple of (offset, length, operator, specimen), which effectively does a bool( (read(offset, length)) OPERATOR specimen ) and only performs the write if all these evaluate to True. Basic test-and-set uses 'eq'. Write-if-newer uses a seqnum and (offset, length, 'lt', specimen). Write-if-same-or-newer uses 'le'. Reads from the end of the container are truncated, and missing shares behave like empty ones, so to assert that a share doesn't exist (for use when creating a new share), use (0, 1, 'eq', ''). The write vector will be applied to the given share, expanding it if necessary. A write vector applied to a share number that did not exist previously will cause that share to be created. Each write vector is accompanied by a 'new_length' argument. If new_length is not None, use it to set the size of the container. This can be used to pre-allocate space for a series of upcoming writes, or truncate existing data. If the container is growing, new_length will be applied before datav. If the container is shrinking, it will be applied afterwards. The read vector is used to extract data from all known shares, *before* any writes have been applied. The same vector is used for all shares. This captures the state that was tested by the test vector. This method returns two values: a boolean and a dict. The boolean is True if the write vectors were applied, False if not. The dict is keyed by share number, and each value contains a list of strings, one for each element of the read vector. If the write_enabler is wrong, this will raise BadWriteEnablerError. To enable share migration, the exception will have the nodeid used for the old write enabler embedded in it, in the following string:: The write enabler was recorded by nodeid '%s'. Note that the nodeid here is encoded using the same base32 encoding used by Foolscap and allmydata.util.idlib.nodeid_b2a(). """ return TupleOf(bool, DictOf(int, ReadData)) class IStorageBucketWriter(Interface): def put_block(segmentnum=int, data=ShareData): """@param data: For most segments, this data will be 'blocksize' bytes in length. The last segment might be shorter. @return: a Deferred that fires (with None) when the operation completes """ def put_plaintext_hashes(hashes=ListOf(Hash, maxLength=2**20)): """ @return: a Deferred that fires (with None) when the operation completes """ def put_crypttext_hashes(hashes=ListOf(Hash, maxLength=2**20)): """ @return: a Deferred that fires (with None) when the operation completes """ def put_block_hashes(blockhashes=ListOf(Hash, maxLength=2**20)): """ @return: a Deferred that fires (with None) when the operation completes """ def put_share_hashes(sharehashes=ListOf(TupleOf(int, Hash), maxLength=2**20)): """ @return: a Deferred that fires (with None) when the operation completes """ def put_uri_extension(data=URIExtensionData): """This block of data contains integrity-checking information (hashes of plaintext, crypttext, and shares), as well as encoding parameters that are necessary to recover the data. This is a serialized dict mapping strings to other strings. The hash of this data is kept in the URI and verified before any of the data is used. All buckets for a given file contain identical copies of this data. The serialization format is specified with the following pseudocode: for k in sorted(dict.keys()): assert re.match(r'^[a-zA-Z_\-]+$', k) write(k + ':' + netstring(dict[k])) @return: a Deferred that fires (with None) when the operation completes """ def close(): """Finish writing and close the bucket. The share is not finalized until this method is called: if the uploading client disconnects before calling close(), the partially-written share will be discarded. @return: a Deferred that fires (with None) when the operation completes """ class IStorageBucketReader(Interface): def get_block(blocknum=int): """Most blocks will be the same size. The last block might be shorter than the others. @return: ShareData """ def get_plaintext_hashes(): """ @return: ListOf(Hash, maxLength=2**20) """ def get_crypttext_hashes(): """ @return: ListOf(Hash, maxLength=2**20) """ def get_block_hashes(): """ @return: ListOf(Hash, maxLength=2**20) """ def get_share_hashes(): """ @return: ListOf(TupleOf(int, Hash), maxLength=2**20) """ def get_uri_extension(): """ @return: URIExtensionData """ # hm, we need a solution for forward references in schemas from foolscap.schema import Any RIMutableDirectoryNode_ = Any() # TODO: how can we avoid this? FileNode_ = Any() # TODO: foolscap needs constraints on copyables DirectoryNode_ = Any() # TODO: same AnyNode_ = ChoiceOf(FileNode_, DirectoryNode_) EncryptedThing = str class RIVirtualDriveServer(RemoteInterface): def get_public_root_uri(): """Obtain the URI for this server's global publically-writable root directory. This returns a read-write directory URI. If this vdrive server does not offer a public root, this will raise an exception.""" return DirnodeURI def create_directory(index=Hash, write_enabler=Hash): """Create a new (empty) directory, unattached to anything else. This returns the same index that was passed in. """ return Hash def get(index=Hash, key=Hash): """Retrieve a named child of the given directory. 'index' specifies which directory is being accessed, and is generally the hash of the read key. 'key' is the hash of the read key and the child name. This operation returns a pair of encrypted strings. The first string is meant to be decrypted by the Write Key and provides read-write access to the child. If this directory holds read-only access to the child, this first string will be an empty string. The second string is meant to be decrypted by the Read Key and provides read-only access to the child. When the child is a read-write directory, the encrypted URI:DIR-RO will be in the read slot, and the encrypted URI:DIR will be in the write slot. When the child is a read-only directory, the encrypted URI:DIR-RO will be in the read slot and the write slot will be empty. When the child is a CHK file, the encrypted URI:CHK will be in the read slot, and the write slot will be empty. This might raise IndexError if there is no child by the desired name. """ return (EncryptedThing, EncryptedThing) def list(index=Hash): """List the contents of a directory. This returns a list of (NAME, WRITE, READ) tuples. Each value is an encrypted string (although the WRITE value may sometimes be an empty string). NAME: the child name, encrypted with the Read Key WRITE: the child write URI, encrypted with the Write Key, or an empty string if this child is read-only READ: the child read URI, encrypted with the Read Key """ return ListOf((EncryptedThing, EncryptedThing, EncryptedThing), maxLength=1000, ) def set(index=Hash, write_enabler=Hash, key=Hash, name=EncryptedThing, write=EncryptedThing, read=EncryptedThing): """Set a child object. I will replace any existing child of the same name. """ def delete(index=Hash, write_enabler=Hash, key=Hash): """Delete a specific child. This uses the hashed key to locate a specific child, and deletes it. """ class IURI(Interface): def init_from_string(uri): """Accept a string (as created by my to_string() method) and populate this instance with its data. I am not normally called directly, please use the module-level uri.from_string() function to convert arbitrary URI strings into IURI-providing instances.""" def is_readonly(): """Return False if this URI be used to modify the data. Return True if this URI cannot be used to modify the data.""" def is_mutable(): """Return True if the data can be modified by *somebody* (perhaps someone who has a more powerful URI than this one).""" def get_readonly(): """Return another IURI instance, which represents a read-only form of this one. If is_readonly() is True, this returns self.""" def get_verifier(): """Return an instance that provides IVerifierURI, which can be used to check on the availability of the file or directory, without providing enough capabilities to actually read or modify the contents. This may return None if the file does not need checking or verification (e.g. LIT URIs). """ def to_string(): """Return a string of printable ASCII characters, suitable for passing into init_from_string.""" class IVerifierURI(Interface): def init_from_string(uri): """Accept a string (as created by my to_string() method) and populate this instance with its data. I am not normally called directly, please use the module-level uri.from_string() function to convert arbitrary URI strings into IURI-providing instances.""" def to_string(): """Return a string of printable ASCII characters, suitable for passing into init_from_string.""" class IDirnodeURI(Interface): """I am a URI which represents a dirnode.""" class IFileURI(Interface): """I am a URI which represents a filenode.""" def get_size(): """Return the length (in bytes) of the file that I represent.""" class IMutableFileURI(Interface): """I am a URI which represents a mutable filenode.""" pass class INewDirectoryURI(Interface): pass class IFileNode(Interface): def download(target): """Download the file's contents to a given IDownloadTarget""" def download_to_data(): """Download the file's contents. Return a Deferred that fires with those contents.""" def get_uri(): """Return the URI that can be used by others to get access to this file. """ def get_size(): """Return the length (in bytes) of the data this node represents.""" def get_verifier(): """Return an IVerifierURI instance that represents the 'verifiy/refresh capability' for this node. The holder of this capability will be able to renew the lease for this node, protecting it from garbage-collection. They will also be able to ask a server if it holds a share for the file or directory. """ def check(): """Perform a file check. See IChecker.check for details.""" class IMutableFileNode(IFileNode): def download_to_data(): """Download the file's contents. Return a Deferred that fires with those contents. If there are multiple retrievable versions in the grid (because you failed to avoid simultaneous writes, see docs/mutable.txt), this will return the first version that it can reconstruct, and will silently ignore the others. In the future, a more advanced API will signal and provide access to the multiple heads.""" def replace(newdata): """Replace the old contents with the new data. Returns a Deferred that fires (with None) when the operation is complete. If the node detects that there are multiple outstanding versions of the file, this will raise ConsistencyError, and may leave the distributed file in an unusual state (the node will try to ensure that at least one version of the file remains retrievable, but it may or may not be the one you just tried to upload). You should respond to this by downloading the current contents of the file and retrying the replace() operation. """ def get_uri(): pass def get_verifier(): pass def check(): pass def get_writekey(): """Return this filenode's writekey, or None if the node does not have write-capability. This may be used to assist with data structures that need to make certain data available only to writers, such as the read-write child caps in dirnodes. The recommended process is to have reader-visible data be submitted to the filenode in the clear (where it will be encrypted by the filenode using the readkey), but encrypt writer-visible data using this writekey. """ class IDirectoryNode(Interface): def is_mutable(): """Return True if this directory is mutable, False if it is read-only. """ def get_uri(): """Return the directory URI that can be used by others to get access to this directory node. If this node is read-only, the URI will only offer read-only access. If this node is read-write, the URI will offer read-write acess. If you have read-write access to a directory and wish to share merely read-only access with others, use get_immutable_uri(). The dirnode ('1') URI returned by this method can be used in set_uri() on a different directory ('2') to 'mount' a reference to this directory ('1') under the other ('2'). This URI is just a string, so it can be passed around through email or other out-of-band protocol. """ def get_immutable_uri(): """Return the directory URI that can be used by others to get read-only access to this directory node. The result is a read-only URI, regardless of whether this dirnode is read-only or read-write. If you have merely read-only access to this dirnode, get_immutable_uri() will return the same thing as get_uri(). """ def get_verifier(): """Return an IVerifierURI instance that represents the 'verifiy/refresh capability' for this node. The holder of this capability will be able to renew the lease for this node, protecting it from garbage-collection. They will also be able to ask a server if it holds a share for the file or directory. """ def check(): """Perform a file check. See IChecker.check for details.""" def list(): """I return a Deferred that fires with a dictionary mapping child name to an IFileNode or IDirectoryNode.""" def has_child(name): """I return a Deferred that fires with a boolean, True if there exists a child of the given name, False if not.""" def get(name): """I return a Deferred that fires with a specific named child node, either an IFileNode or an IDirectoryNode.""" def get_child_at_path(path): """Transform a child path into an IDirectoryNode or IFileNode. I perform a recursive series of 'get' operations to find the named descendant node. I return a Deferred that fires with the node, or errbacks with IndexError if the node could not be found. The path can be either a single string (slash-separated) or a list of path-name elements. """ def set_uri(name, child_uri): """I add a child (by URI) at the specific name. I return a Deferred that fires when the operation finishes. I will replace any existing child of the same name. The child_uri could be for a file, or for a directory (either read-write or read-only, using a URI that came from get_uri() ). If this directory node is read-only, the Deferred will errback with a NotMutableError.""" def set_node(name, child): """I add a child at the specific name. I return a Deferred that fires when the operation finishes. This Deferred will fire with the child node that was just added. I will replace any existing child of the same name. If this directory node is read-only, the Deferred will errback with a NotMutableError.""" def add_file(name, uploadable): """I upload a file (using the given IUploadable), then attach the resulting FileNode to the directory at the given name. I return a Deferred that fires (with the IFileNode of the uploaded file) when the operation completes.""" def delete(name): """I remove the child at the specific name. I return a Deferred that fires when the operation finishes.""" def create_empty_directory(name): """I create and attach an empty directory at the given name. I return a Deferred that fires when the operation finishes.""" def move_child_to(current_child_name, new_parent, new_child_name=None): """I take one of my children and move them to a new parent. The child is referenced by name. On the new parent, the child will live under 'new_child_name', which defaults to 'current_child_name'. I return a Deferred that fires when the operation finishes.""" def build_manifest(): """Return a frozenset of verifier-capability strings for all nodes (directories and files) reachable from this one.""" class ICodecEncoder(Interface): def set_params(data_size, required_shares, max_shares): """Set up the parameters of this encoder. This prepares the encoder to perform an operation that converts a single block of data into a number of shares, such that a future ICodecDecoder can use a subset of these shares to recover the original data. This operation is invoked by calling encode(). Once the encoding parameters are set up, the encode operation can be invoked multiple times. set_params() prepares the encoder to accept blocks of input data that are exactly 'data_size' bytes in length. The encoder will be prepared to produce 'max_shares' shares for each encode() operation (although see the 'desired_share_ids' to use less CPU). The encoding math will be chosen such that the decoder can get by with as few as 'required_shares' of these shares and still reproduce the original data. For example, set_params(1000, 5, 5) offers no redundancy at all, whereas set_params(1000, 1, 10) provides 10x redundancy. Numerical Restrictions: 'data_size' is required to be an integral multiple of 'required_shares'. In general, the caller should choose required_shares and max_shares based upon their reliability requirements and the number of peers available (the total storage space used is roughly equal to max_shares*data_size/required_shares), then choose data_size to achieve the memory footprint desired (larger data_size means more efficient operation, smaller data_size means smaller memory footprint). In addition, 'max_shares' must be equal to or greater than 'required_shares'. Of course, setting them to be equal causes encode() to degenerate into a particularly slow form of the 'split' utility. See encode() for more details about how these parameters are used. set_params() must be called before any other ICodecEncoder methods may be invoked. """ def get_encoder_type(): """Return a short string that describes the type of this encoder. There is required to be a global table of encoder classes. This method returns an index into this table; the value at this index is an encoder class, and this encoder is an instance of that class. """ def get_serialized_params(): # TODO: maybe, maybe not """Return a string that describes the parameters of this encoder. This string can be passed to the decoder to prepare it for handling the encoded shares we create. It might contain more information than was presented to set_params(), if there is some flexibility of parameter choice. This string is intended to be embedded in the URI, so there are several restrictions on its contents. At the moment I'm thinking that this means it may contain hex digits and hyphens, and nothing else. The idea is that the URI contains something like '%s:%s:%s' % (encoder.get_encoder_name(), encoder.get_serialized_params(), b2a(crypttext_hash)), and this is enough information to construct a compatible decoder. """ def get_block_size(): """Return the length of the shares that encode() will produce. """ def encode_proposal(data, desired_share_ids=None): """Encode some data. 'data' must be a string (or other buffer object), and len(data) must be equal to the 'data_size' value passed earlier to set_params(). This will return a Deferred that will fire with two lists. The first is a list of shares, each of which is a string (or other buffer object) such that len(share) is the same as what get_share_size() returned earlier. The second is a list of shareids, in which each is an integer. The lengths of the two lists will always be equal to each other. The user should take care to keep each share closely associated with its shareid, as one is useless without the other. The length of this output list will normally be the same as the value provided to the 'max_shares' parameter of set_params(). This may be different if 'desired_share_ids' is provided. 'desired_share_ids', if provided, is required to be a sequence of ints, each of which is required to be >= 0 and < max_shares. If not provided, encode() will produce 'max_shares' shares, as if 'desired_share_ids' were set to range(max_shares). You might use this if you initially thought you were going to use 10 peers, started encoding, and then two of the peers dropped out: you could use desired_share_ids= to skip the work (both memory and CPU) of producing shares for the peers which are no longer available. """ def encode(inshares, desired_share_ids=None): """Encode some data. This may be called multiple times. Each call is independent. inshares is a sequence of length required_shares, containing buffers (i.e. strings), where each buffer contains the next contiguous non-overlapping segment of the input data. Each buffer is required to be the same length, and the sum of the lengths of the buffers is required to be exactly the data_size promised by set_params(). (This implies that the data has to be padded before being passed to encode(), unless of course it already happens to be an even multiple of required_shares in length.) ALSO: the requirement to break up your data into 'required_shares' chunks before calling encode() feels a bit surprising, at least from the point of view of a user who doesn't know how FEC works. It feels like an implementation detail that has leaked outside the abstraction barrier. Can you imagine a use case in which the data to be encoded might already be available in pre-segmented chunks, such that it is faster or less work to make encode() take a list rather than splitting a single string? ALSO ALSO: I think 'inshares' is a misleading term, since encode() is supposed to *produce* shares, so what it *accepts* should be something other than shares. Other places in this interface use the word 'data' for that-which-is-not-shares.. maybe we should use that term? 'desired_share_ids', if provided, is required to be a sequence of ints, each of which is required to be >= 0 and < max_shares. If not provided, encode() will produce 'max_shares' shares, as if 'desired_share_ids' were set to range(max_shares). You might use this if you initially thought you were going to use 10 peers, started encoding, and then two of the peers dropped out: you could use desired_share_ids= to skip the work (both memory and CPU) of producing shares for the peers which are no longer available. For each call, encode() will return a Deferred that fires with two lists, one containing shares and the other containing the shareids. The get_share_size() method can be used to determine the length of the share strings returned by encode(). Each shareid is a small integer, exactly as passed into 'desired_share_ids' (or range(max_shares), if desired_share_ids was not provided). The shares and their corresponding shareids are required to be kept together during storage and retrieval. Specifically, the share data is useless by itself: the decoder needs to be told which share is which by providing it with both the shareid and the actual share data. This function will allocate an amount of memory roughly equal to:: (max_shares - required_shares) * get_share_size() When combined with the memory that the caller must allocate to provide the input data, this leads to a memory footprint roughly equal to the size of the resulting encoded shares (i.e. the expansion factor times the size of the input segment). """ # rejected ideas: # # returning a list of (shareidN,shareN) tuples instead of a pair of # lists (shareids..,shares..). Brian thought the tuples would # encourage users to keep the share and shareid together throughout # later processing, Zooko pointed out that the code to iterate # through two lists is not really more complicated than using a list # of tuples and there's also a performance improvement # # having 'data_size' not required to be an integral multiple of # 'required_shares'. Doing this would require encode() to perform # padding internally, and we'd prefer to have any padding be done # explicitly by the caller. Yes, it is an abstraction leak, but # hopefully not an onerous one. class ICodecDecoder(Interface): def set_serialized_params(params): """Set up the parameters of this encoder, from a string returned by encoder.get_serialized_params().""" def get_needed_shares(): """Return the number of shares needed to reconstruct the data. set_serialized_params() is required to be called before this.""" def decode(some_shares, their_shareids): """Decode a partial list of shares into data. 'some_shares' is required to be a sequence of buffers of sharedata, a subset of the shares returned by ICodecEncode.encode(). Each share is required to be of the same length. The i'th element of their_shareids is required to be the shareid of the i'th buffer in some_shares. This returns a Deferred which fires with a sequence of buffers. This sequence will contain all of the segments of the original data, in order. The sum of the lengths of all of the buffers will be the 'data_size' value passed into the original ICodecEncode.set_params() call. To get back the single original input block of data, use ''.join(output_buffers), or you may wish to simply write them in order to an output file. Note that some of the elements in the result sequence may be references to the elements of the some_shares input sequence. In particular, this means that if those share objects are mutable (e.g. arrays) and if they are changed, then both the input (the 'some_shares' parameter) and the output (the value given when the deferred is triggered) will change. The length of 'some_shares' is required to be exactly the value of 'required_shares' passed into the original ICodecEncode.set_params() call. """ class IEncoder(Interface): """I take an object that provides IEncryptedUploadable, which provides encrypted data, and a list of shareholders. I then encode, hash, and deliver shares to those shareholders. I will compute all the necessary Merkle hash trees that are necessary to validate the crypttext that eventually comes back from the shareholders. I provide the URI Extension Block Hash, and the encoding parameters, both of which must be included in the URI. I do not choose shareholders, that is left to the IUploader. I must be given a dict of RemoteReferences to storage buckets that are ready and willing to receive data. """ def set_size(size): """Specify the number of bytes that will be encoded. This must be peformed before get_serialized_params() can be called. """ def set_params(params): """Override the default encoding parameters. 'params' is a tuple of (k,d,n), where 'k' is the number of required shares, 'd' is the shares_of_happiness, and 'n' is the total number of shares that will be created. Encoding parameters can be set in three ways. 1: The Encoder class provides defaults (3/7/10). 2: the Encoder can be constructed with an 'options' dictionary, in which the needed_and_happy_and_total_shares' key can be a (k,d,n) tuple. 3: set_params((k,d,n)) can be called. If you intend to use set_params(), you must call it before get_share_size or get_param are called. """ def set_encrypted_uploadable(u): """Provide a source of encrypted upload data. 'u' must implement IEncryptedUploadable. When this is called, the IEncryptedUploadable will be queried for its length and the storage_index that should be used. This returns a Deferred that fires with this Encoder instance. This must be performed before start() can be called. """ def get_param(name): """Return an encoding parameter, by name. 'storage_index': return a string with the (16-byte truncated SHA-256 hash) storage index to which these shares should be pushed. 'share_counts': return a tuple describing how many shares are used: (needed_shares, shares_of_happiness, total_shares) 'num_segments': return an int with the number of segments that will be encoded. 'segment_size': return an int with the size of each segment. 'block_size': return the size of the individual blocks that will be delivered to a shareholder's put_block() method. By knowing this, the shareholder will be able to keep all blocks in a single file and still provide random access when reading them. # TODO: can we avoid exposing this? 'share_size': an int with the size of the data that will be stored on each shareholder. This is aggregate amount of data that will be sent to the shareholder, summed over all the put_block() calls I will ever make. It is useful to determine this size before asking potential shareholders whether they will grant a lease or not, since their answers will depend upon how much space we need. TODO: this might also include some amount of overhead, like the size of all the hashes. We need to decide whether this is useful or not. 'serialized_params': a string with a concise description of the codec name and its parameters. This may be passed into the IUploadable to let it make sure that the same file encoded with different parameters will result in different storage indexes. Once this is called, set_size() and set_params() may not be called. """ def set_shareholders(shareholders): """Tell the encoder where to put the encoded shares. 'shareholders' must be a dictionary that maps share number (an integer ranging from 0 to n-1) to an instance that provides IStorageBucketWriter. This must be performed before start() can be called.""" def start(): """Begin the encode/upload process. This involves reading encrypted data from the IEncryptedUploadable, encoding it, uploading the shares to the shareholders, then sending the hash trees. set_encrypted_uploadable() and set_shareholders() must be called before this can be invoked. This returns a Deferred that fires with a tuple of (uri_extension_hash, needed_shares, total_shares, size) when the upload process is complete. This information, plus the encryption key, is sufficient to construct the URI. """ class IDecoder(Interface): """I take a list of shareholders and some setup information, then download, validate, decode, and decrypt data from them, writing the results to an output file. I do not locate the shareholders, that is left to the IDownloader. I must be given a dict of RemoteReferences to storage buckets that are ready to send data. """ def setup(outfile): """I take a file-like object (providing write and close) to which all the plaintext data will be written. TODO: producer/consumer . Maybe write() should return a Deferred that indicates when it will accept more data? But probably having the IDecoder be a producer is easier to glue to IConsumer pieces. """ def set_shareholders(shareholders): """I take a dictionary that maps share identifiers (small integers) to RemoteReferences that provide RIBucketReader. This must be called before start().""" def start(): """I start the download. This process involves retrieving data and hash chains from the shareholders, using the hashes to validate the data, decoding the shares into segments, decrypting the segments, then writing the resulting plaintext to the output file. I return a Deferred that will fire (with self) when the download is complete. """ class IDownloadTarget(Interface): def open(size): """Called before any calls to write() or close(). If an error occurs before any data is available, fail() may be called without a previous call to open(). 'size' is the length of the file being downloaded, in bytes.""" def write(data): """Output some data to the target.""" def close(): """Inform the target that there is no more data to be written.""" def fail(why): """fail() is called to indicate that the download has failed. 'why' is a Failure object indicating what went wrong. No further methods will be invoked on the IDownloadTarget after fail().""" def register_canceller(cb): """The FileDownloader uses this to register a no-argument function that the target can call to cancel the download. Once this canceller is invoked, no further calls to write() or close() will be made.""" def finish(): """When the FileDownloader is done, this finish() function will be called. Whatever it returns will be returned to the invoker of Downloader.download. """ class IDownloader(Interface): def download(uri, target): """Perform a CHK download, sending the data to the given target. 'target' must provide IDownloadTarget. Returns a Deferred that fires (with the results of target.finish) when the download is finished, or errbacks if something went wrong.""" class IEncryptedUploadable(Interface): def get_size(): """This behaves just like IUploadable.get_size().""" def set_serialized_encoding_parameters(serialized_encoding_parameters): """Tell me what encoding parameters will be used for my data. 'serialized_encoding_parameters' is a string which indicates how the data will be encoded (codec name, blocksize, number of shares). I may use this when get_storage_index() is called, to influence the index that I return. Or, I may just ignore it. set_serialized_encoding_parameters() may be called 0 or 1 times. If called, it must be called before get_storage_index(). """ def get_storage_index(): """Return a Deferred that fires with a 16-byte storage index. This value may be influenced by the parameters earlier set by set_serialized_encoding_parameters(). """ def set_segment_size(segment_size): """Set the segment size, to allow the IEncryptedUploadable to accurately create the plaintext segment hash tree. This must be called before any calls to read_encrypted.""" def read_encrypted(length): """This behaves just like IUploadable.read(), but returns crypttext instead of plaintext. set_segment_size() must be called before the first call to read_encrypted().""" def get_plaintext_segment_hashtree_nodes(num_segments): """Get the nodes of a merkle hash tree over the plaintext segments. This returns a Deferred which fires with a sequence of hashes. Each hash is a node of a merkle hash tree, generally obtained from:: tuple(HashTree(segment_hashes)) 'num_segments' is used to assert that the number of segments that the IEncryptedUploadable handled matches the number of segments that the encoder was expecting. """ def get_plaintext_hash(): """Get the hash of the whole plaintext. This returns a Deferred which fires with a tagged SHA-256 hash of the whole plaintext, obtained from hashutil.plaintext_hash(data). """ def close(): """Just like IUploadable.close().""" class IUploadable(Interface): def get_size(): """Return a Deferred that will fire with the length of the data to be uploaded, in bytes. This will be called before the data is actually used, to compute encoding parameters. """ def set_serialized_encoding_parameters(serialized_encoding_parameters): """Tell me what encoding parameters will be used for my data. 'serialized_encoding_parameters' is a string which indicates how the data will be encoded (codec name, blocksize, number of shares). I may use this when get_encryption_key() is called, to influence the key that I return. Or, I may just ignore it. set_serialized_encoding_parameters() may be called 0 or 1 times. If called, it must be called before get_encryption_key(). """ def get_encryption_key(): """Return a Deferred that fires with a 16-byte AES key. This key will be used to encrypt the data. The key will also be hashed to derive the StorageIndex. Uploadables which want to achieve convergence should hash their file contents and the serialized_encoding_parameters to form the key (which of course requires a full pass over the data). Uploadables can use the upload.ConvergentUploadMixin class to achieve this automatically. Uploadables which do not care about convergence (or do not wish to make multiple passes over the data) can simply return a strongly-random 16 byte string. get_encryption_key() may be called multiple times: the IUploadable is required to return the same value each time. """ def read(length): """Return a Deferred that fires with a list of strings (perhaps with only a single element) which, when concatenated together, contain the next 'length' bytes of data. If EOF is near, this may provide fewer than 'length' bytes. The total number of bytes provided by read() before it signals EOF must equal the size provided by get_size(). If the data must be acquired through multiple internal read operations, returning a list instead of a single string may help to reduce string copies. 'length' will typically be equal to (min(get_size(),1MB)/req_shares), so a 10kB file means length=3kB, 100kB file means length=30kB, and >=1MB file means length=300kB. This method provides for a single full pass through the data. Later use cases may desire multiple passes or access to only parts of the data (such as a mutable file making small edits-in-place). This API will be expanded once those use cases are better understood. """ def close(): """The upload is finished, and whatever filehandle was in use may be closed.""" class IUploader(Interface): def upload(uploadable): """Upload the file. 'uploadable' must impement IUploadable. This returns a Deferred which fires with the URI of the file.""" def upload_ssk(write_capability, new_version, uploadable): """TODO: how should this work?""" def upload_data(data): """Like upload(), but accepts a string.""" def upload_filename(filename): """Like upload(), but accepts an absolute pathname.""" def upload_filehandle(filehane): """Like upload(), but accepts an open filehandle.""" class IChecker(Interface): def check(uri_to_check): """Accepts an IVerifierURI, and checks upon the health of its target. For now, uri_to_check must be an IVerifierURI. In the future we expect to relax that to be anything that can be adapted to IVerifierURI (like read-only or read-write dirnode/filenode URIs). This returns a Deferred. For dirnodes, this fires with either True or False (dirnodes are not distributed, so their health is a boolean). For filenodes, this fires with a tuple of (needed_shares, total_shares, found_shares, sharemap). The first three are ints. The basic health of the file is found_shares / needed_shares: if less than 1.0, the file is unrecoverable. The sharemap has a key for each sharenum. The value is a list of (binary) nodeids who hold that share. If two shares are kept on the same nodeid, they will fail as a pair, and overall reliability is decreased. The IChecker instance remembers the results of the check. By default, these results are stashed in RAM (and are forgotten at shutdown). If a file named 'checker_results.db' exists in the node's basedir, it is used as a sqlite database of results, making them persistent across runs. To start using this feature, just 'touch checker_results.db', and the node will initialize it properly the next time it is started. """ def verify(uri_to_check): """Accepts an IVerifierURI, and verifies the crypttext of the target. This is a more-intensive form of checking. For verification, the file's crypttext contents are retrieved, and the associated hash checks are performed. If a storage server is holding a corrupted share, verification will detect the problem, but checking will not. This returns a Deferred that fires with True if the crypttext hashes look good, and will probably raise an exception if anything goes wrong. For dirnodes, 'verify' is the same as 'check', so the Deferred will fire with True or False. Verification currently only uses a minimal subset of peers, so a lot of share corruption will not be caught by it. We expect to improve this in the future. """ def checker_results_for(uri_to_check): """Accepts an IVerifierURI, and returns a list of previously recorded checker results. This method performs no checking itself: it merely reports the results of checks that have taken place in the past. Each element of the list is a two-entry tuple: (when, results). The 'when' values are timestamps (float seconds since epoch), and the results are as defined in the check() method. Note: at the moment, this is specified to return synchronously. We might need to back away from this in the future. """ class IVirtualDrive(Interface): """I am a service that may be available to a client. Within any client program, this service can be retrieved by using client.getService('vdrive'). """ def have_public_root(): """Return a Boolean, True if get_public_root() will work.""" def get_public_root(): """Get the public read-write directory root. This returns a Deferred that fires with an IDirectoryNode instance corresponding to the global shared root directory.""" def have_private_root(): """Return a Boolean, True if get_public_root() will work.""" def get_private_root(): """Get the private directory root. This returns a Deferred that fires with an IDirectoryNode instance corresponding to this client's private root directory.""" def get_node_at_path(path): """Transform a path into an IDirectoryNode or IFileNode. The path can either be a single string or a list of path-name elements. The former is generated from the latter by using .join('/'). If the first element of this list is '~', the rest will be interpreted relative to the local user's private root directory. Otherwse it will be interpreted relative to the global public root directory. As a result, the following three values of 'path' are equivalent:: '/dirname/foo.txt' 'dirname/foo.txt' ['dirname', 'foo.txt'] This method returns a Deferred that fires with the node in question, or errbacks with an IndexError if the target node could not be found. """ def get_node(uri): """Transform a URI (or IURI) into an IDirectoryNode or IFileNode. This returns a Deferred that will fire with an instance that provides either IDirectoryNode or IFileNode, as appropriate.""" def create_directory(): """Return a new IDirectoryNode that is empty and not linked by anything.""" class NotCapableError(Exception): """You have tried to write to a read-only node.""" class BadWriteEnablerError(Exception): pass class NotMutableError(Exception): pass class RIControlClient(RemoteInterface): def wait_for_client_connections(num_clients=int): """Do not return until we have connections to at least NUM_CLIENTS storage servers. """ def upload_from_file_to_uri(filename=str): """Upload a file to the grid. This accepts a filename (which must be absolute) that points to a file on the node's local disk. The node will read the contents of this file, upload it to the grid, then return the URI at which it was uploaded. """ return URI def download_from_uri_to_file(uri=URI, filename=str): """Download a file from the grid, placing it on the node's local disk at the given filename (which must be absolute[?]). Returns the absolute filename where the file was written.""" return str # debug stuff def get_memory_usage(): """Return a dict describes the amount of memory currently in use. The keys are 'VmPeak', 'VmSize', and 'VmData'. The values are integers, measuring memory consupmtion in bytes.""" return DictOf(str, int) def speed_test(count=int, size=int): """Write 'count' tempfiles to disk, all of the given size. Measure how long (in seconds) it takes to upload them all to the servers. Then measure how long it takes to download all of them. Returns a tuple of (upload_time, download_time). """ return (float, float) def measure_peer_response_time(): """Send a short message to each connected peer, and measure the time it takes for them to respond to it. This is a rough measure of the application-level round trip time. @return: a dictionary mapping peerid to a float (RTT time in seconds) """ return DictOf(Nodeid, float)