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rename dirnode2.py to dirnode.py
This commit is contained in:
Brian Warner
352
src/allmydata/dirnode.py
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352
src/allmydata/dirnode.py
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@ -0,0 +1,352 @@
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import os
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from zope.interface import implements
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from twisted.internet import defer
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import simplejson
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from allmydata.mutable import NotMutableError
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from allmydata.interfaces import IMutableFileNode, IDirectoryNode,\
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IURI, IFileNode, \
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IVerifierURI
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from allmydata.util import hashutil
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from allmydata.util.hashutil import netstring
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from allmydata.uri import NewDirectoryURI
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from pycryptopp.cipher.aes import AES
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from allmydata.mutable import MutableFileNode
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def split_netstring(data, numstrings, allow_leftover=False):
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"""like string.split(), but extracts netstrings. If allow_leftover=False,
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returns numstrings elements, and throws ValueError if there was leftover
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data. If allow_leftover=True, returns numstrings+1 elements, in which the
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last element is the leftover data (possibly an empty string)"""
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elements = []
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assert numstrings >= 0
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while data:
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colon = data.index(":")
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length = int(data[:colon])
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string = data[colon+1:colon+1+length]
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assert len(string) == length
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elements.append(string)
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assert data[colon+1+length] == ","
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data = data[colon+1+length+1:]
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if len(elements) == numstrings:
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break
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if len(elements) < numstrings:
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raise ValueError("ran out of netstrings")
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if allow_leftover:
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return tuple(elements + [data])
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if data:
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raise ValueError("leftover data in netstrings")
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return tuple(elements)
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class NewDirectoryNode:
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implements(IDirectoryNode)
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filenode_class = MutableFileNode
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def __init__(self, client):
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self._client = client
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def __repr__(self):
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return "<%s %s %s>" % (self.__class__.__name__, self.is_readonly() and "RO" or "RW", hasattr(self, '_uri') and self._uri.abbrev())
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def init_from_uri(self, myuri):
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self._uri = IURI(myuri)
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self._node = self.filenode_class(self._client)
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self._node.init_from_uri(self._uri.get_filenode_uri())
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return self
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def create(self, wait_for_numpeers=None):
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"""
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Returns a deferred that eventually fires with self once the directory
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has been created (distributed across a set of storage servers).
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"""
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# first we create a MutableFileNode with empty_contents, then use its
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# URI to create our own.
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self._node = self.filenode_class(self._client)
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empty_contents = self._pack_contents({})
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d = self._node.create(empty_contents, wait_for_numpeers=wait_for_numpeers)
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d.addCallback(self._filenode_created)
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return d
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def _filenode_created(self, res):
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self._uri = NewDirectoryURI(self._node._uri)
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return self
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def _read(self):
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d = self._node.download_to_data()
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d.addCallback(self._unpack_contents)
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return d
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def _encrypt_rwcap(self, rwcap):
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assert isinstance(rwcap, str)
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IV = os.urandom(16)
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key = hashutil.mutable_rwcap_key_hash(IV, self._node.get_writekey())
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cryptor = AES(key)
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crypttext = cryptor.process(rwcap)
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mac = hashutil.hmac(key, IV + crypttext)
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assert len(mac) == 32
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return IV + crypttext + mac
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def _decrypt_rwcapdata(self, encwrcap):
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IV = encwrcap[:16]
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crypttext = encwrcap[16:-32]
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mac = encwrcap[-32:]
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key = hashutil.mutable_rwcap_key_hash(IV, self._node.get_writekey())
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if mac != hashutil.hmac(key, IV+crypttext):
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raise hashutil.IntegrityCheckError("HMAC does not match, crypttext is corrupted")
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cryptor = AES(key)
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plaintext = cryptor.process(crypttext)
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return plaintext
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def _create_node(self, child_uri):
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return self._client.create_node_from_uri(child_uri)
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def _unpack_contents(self, data):
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# the directory is serialized as a list of netstrings, one per child.
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# Each child is serialized as a list of four netstrings: (name,
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# rocap, rwcap, metadata), in which the name,rocap,metadata are in
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# cleartext. The rwcap is formatted as:
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# pack("16ss32s", iv, AES(H(writekey+iv), plaintextrwcap), mac)
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assert isinstance(data, str)
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# an empty directory is serialized as an empty string
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if data == "":
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return {}
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writeable = not self.is_readonly()
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children = {}
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while len(data) > 0:
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entry, data = split_netstring(data, 1, True)
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name, rocap, rwcapdata, metadata_s = split_netstring(entry, 4)
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if writeable:
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rwcap = self._decrypt_rwcapdata(rwcapdata)
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child = self._create_node(rwcap)
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else:
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child = self._create_node(rocap)
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metadata = simplejson.loads(metadata_s)
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assert isinstance(metadata, dict)
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children[name] = (child, metadata)
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return children
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def _pack_contents(self, children):
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# expects children in the same format as _unpack_contents
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assert isinstance(children, dict)
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entries = []
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for name in sorted(children.keys()):
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child, metadata = children[name]
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assert (IFileNode.providedBy(child)
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or IMutableFileNode.providedBy(child)
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or IDirectoryNode.providedBy(child)), children
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assert isinstance(metadata, dict)
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rwcap = child.get_uri() # might be RO if the child is not writeable
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rocap = child.get_readonly_uri()
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entry = "".join([netstring(name),
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netstring(rocap),
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netstring(self._encrypt_rwcap(rwcap)),
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netstring(simplejson.dumps(metadata))])
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entries.append(netstring(entry))
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return "".join(entries)
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def is_readonly(self):
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return self._node.is_readonly()
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def is_mutable(self):
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return self._node.is_mutable()
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def get_uri(self):
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return self._uri.to_string()
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def get_readonly_uri(self):
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return self._uri.get_readonly().to_string()
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def get_verifier(self):
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return self._uri.get_verifier().to_string()
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def check(self):
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"""Perform a file check. See IChecker.check for details."""
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pass # TODO
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def list(self):
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"""I return a Deferred that fires with a dictionary mapping child
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name to a tuple of (IFileNode or IDirectoryNode, metadata)."""
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return self._read()
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def has_child(self, name):
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"""I return a Deferred that fires with a boolean, True if there
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exists a child of the given name, False if not."""
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d = self._read()
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d.addCallback(lambda children: children.has_key(name))
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return d
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def _get(self, children, name):
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child = children.get(name)
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if child is None:
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raise KeyError(name)
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return child[0]
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def get(self, name):
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"""I return a Deferred that fires with the named child node,
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which is either an IFileNode or an IDirectoryNode."""
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d = self._read()
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d.addCallback(self._get, name)
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return d
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def get_metadata_for(self, name):
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d = self._read()
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d.addCallback(lambda children: children[name][1])
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return d
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def get_child_at_path(self, path):
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"""Transform a child path into an IDirectoryNode or IFileNode.
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I perform a recursive series of 'get' operations to find the named
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descendant node. I return a Deferred that fires with the node, or
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errbacks with IndexError if the node could not be found.
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The path can be either a single string (slash-separated) or a list of
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path-name elements.
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"""
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if not path:
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return defer.succeed(self)
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if isinstance(path, (str, unicode)):
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path = path.split("/")
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childname = path[0]
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remaining_path = path[1:]
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d = self.get(childname)
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if remaining_path:
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def _got(node):
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return node.get_child_at_path(remaining_path)
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d.addCallback(_got)
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return d
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def set_uri(self, name, child_uri, metadata={}, wait_for_numpeers=None):
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"""I add a child (by URI) at the specific name. I return a Deferred
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that fires with the child node when the operation finishes. I will
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replace any existing child of the same name.
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The child_uri could be for a file, or for a directory (either
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read-write or read-only, using a URI that came from get_uri() ).
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If this directory node is read-only, the Deferred will errback with a
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NotMutableError."""
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return self.set_node(name, self._create_node(child_uri), metadata, wait_for_numpeers=wait_for_numpeers)
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def set_node(self, name, child, metadata={}, wait_for_numpeers=None):
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"""I add a child at the specific name. I return a Deferred that fires
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when the operation finishes. This Deferred will fire with the child
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node that was just added. I will replace any existing child of the
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same name.
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If this directory node is read-only, the Deferred will errback with a
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NotMutableError."""
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if self.is_readonly():
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return defer.fail(NotMutableError())
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d = self._read()
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def _add(children):
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children[name] = (child, metadata)
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new_contents = self._pack_contents(children)
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return self._node.replace(new_contents, wait_for_numpeers=wait_for_numpeers)
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d.addCallback(_add)
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d.addCallback(lambda res: child)
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return d
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def add_file(self, name, uploadable, wait_for_numpeers=None):
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"""I upload a file (using the given IUploadable), then attach the
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resulting FileNode to the directory at the given name. I return a
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Deferred that fires (with the IFileNode of the uploaded file) when
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the operation completes."""
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if self.is_readonly():
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return defer.fail(NotMutableError())
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d = self._client.upload(uploadable, wait_for_numpeers=wait_for_numpeers)
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d.addCallback(self._client.create_node_from_uri)
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d.addCallback(lambda node: self.set_node(name, node, wait_for_numpeers=wait_for_numpeers))
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return d
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def delete(self, name):
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"""I remove the child at the specific name. I return a Deferred that
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fires (with the node just removed) when the operation finishes."""
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if self.is_readonly():
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return defer.fail(NotMutableError())
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d = self._read()
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def _delete(children):
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old_child, metadata = children[name]
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del children[name]
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new_contents = self._pack_contents(children)
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d = self._node.replace(new_contents)
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def _done(res):
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return old_child
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d.addCallback(_done)
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return d
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d.addCallback(_delete)
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return d
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def create_empty_directory(self, name, wait_for_numpeers=None):
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"""I create and attach an empty directory at the given name. I return
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a Deferred that fires (with the new directory node) when the
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operation finishes."""
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if self.is_readonly():
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return defer.fail(NotMutableError())
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d = self._client.create_empty_dirnode(wait_for_numpeers=wait_for_numpeers)
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def _created(child):
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d = self.set_node(name, child, wait_for_numpeers=wait_for_numpeers)
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d.addCallback(lambda res: child)
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return d
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d.addCallback(_created)
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return d
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def move_child_to(self, current_child_name, new_parent,
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new_child_name=None, wait_for_numpeers=None):
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"""I take one of my children and move them to a new parent. The child
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is referenced by name. On the new parent, the child will live under
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'new_child_name', which defaults to 'current_child_name'. I return a
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Deferred that fires when the operation finishes."""
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if self.is_readonly() or new_parent.is_readonly():
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return defer.fail(NotMutableError())
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if new_child_name is None:
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new_child_name = current_child_name
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d = self.get(current_child_name)
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def sn(child):
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return new_parent.set_node(new_child_name, child,
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wait_for_numpeers=wait_for_numpeers)
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d.addCallback(sn)
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d.addCallback(lambda child: self.delete(current_child_name))
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return d
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def build_manifest(self):
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"""Return a frozenset of verifier-capability strings for all nodes
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(directories and files) reachable from this one."""
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# this is just a tree-walker, except that following each edge
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# requires a Deferred.
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manifest = set()
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manifest.add(self.get_verifier())
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d = self._build_manifest_from_node(self, manifest)
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def _done(res):
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# LIT nodes have no verifier-capability: their data is stored
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# inside the URI itself, so there is no need to refresh anything.
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# They indicate this by returning None from their get_verifier
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# method. We need to remove any such Nones from our set. We also
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# want to convert all these caps into strings.
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return frozenset([IVerifierURI(cap).to_string()
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for cap in manifest
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if cap is not None])
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d.addCallback(_done)
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return d
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def _build_manifest_from_node(self, node, manifest):
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d = node.list()
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def _got_list(res):
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dl = []
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for name, (child, metadata) in res.iteritems():
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verifier = child.get_verifier()
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if verifier not in manifest:
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manifest.add(verifier)
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if IDirectoryNode.providedBy(child):
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dl.append(self._build_manifest_from_node(child,
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manifest))
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if dl:
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return defer.DeferredList(dl)
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d.addCallback(_got_list)
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return d
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# use client.create_dirnode() to make one of these
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Block a user