import os, struct, itertools from zope.interface import implements from twisted.internet import defer from allmydata.interfaces import IMutableFileNode, IMutableFileURI from allmydata.util import hashutil, mathutil from allmydata.uri import WriteableSSKFileURI from allmydata.Crypto.Cipher import AES from allmydata import hashtree, codec from allmydata.encode import NotEnoughPeersError class NeedMoreDataError(Exception): def __init__(self, needed_bytes): Exception.__init__(self) self.needed_bytes = needed_bytes class UncoordinatedWriteError(Exception): pass HEADER_LENGTH = struct.calcsize(">BQ32s BBQQ LLLLLQQ") def unpack_share(data): assert len(data) >= HEADER_LENGTH o = {} (version, seqnum, root_hash, k, N, segsize, datalen, o['signature'], o['share_hash_chain'], o['block_hash_tree'], o['IV'], o['share_data'], o['enc_privkey'], o['EOF']) = struct.unpack(">BQ32s" + "BBQQ" + "LLLLLQQ", data[:HEADER_LENGTH]) assert version == 0 if len(data) < o['EOF']: raise NeedMoreDataError(o['EOF']) pubkey = data[HEADER_LENGTH:o['signature']] signature = data[o['signature']:o['share_hash_chain']] share_hash_chain_s = data[o['share_hash_chain']:o['block_hash_tree']] share_hash_format = ">H32s" hsize = struct.calcsize(share_hash_format) assert len(share_hash_chain_s) % hsize == 0, len(share_hash_chain_s) share_hash_chain = [] for i in range(0, len(share_hash_chain_s), hsize): chunk = share_hash_chain_s[i:i+hsize] (hid, h) = struct.unpack(share_hash_format, chunk) share_hash_chain.append( (hid, h) ) block_hash_tree_s = data[o['block_hash_tree']:o['IV']] assert len(block_hash_tree_s) % 32 == 0, len(block_hash_tree_s) block_hash_tree = [] for i in range(0, len(block_hash_tree_s), 32): block_hash_tree.append(block_hash_tree_s[i:i+32]) IV = data[o['IV']:o['share_data']] share_data = data[o['share_data']:o['enc_privkey']] enc_privkey = data[o['enc_privkey']:o['EOF']] return (seqnum, root_hash, k, N, segsize, datalen, pubkey, signature, share_hash_chain, block_hash_tree, IV, share_data, enc_privkey) def pack_checkstring(seqnum, root_hash): return struct.pack(">BQ32s", 0, # version, seqnum, root_hash) def unpack_checkstring(checkstring): cs_len = struct.calcsize(">BQ32s") version, seqnum, root_hash = struct.unpack(">BQ32s", checkstring[:cs_len]) assert version == 0 # TODO: just ignore the share return (seqnum, root_hash) def pack_prefix(seqnum, root_hash, required_shares, total_shares, segment_size, data_length): prefix = struct.pack(">BQ32s" + "BBQQ", 0, # version, seqnum, root_hash, required_shares, total_shares, segment_size, data_length, ) return prefix def pack_offsets(verification_key_length, signature_length, share_hash_chain_length, block_hash_tree_length, IV_length, share_data_length, encprivkey_length): post_offset = HEADER_LENGTH offsets = {} o1 = offsets['signature'] = post_offset + verification_key_length o2 = offsets['share_hash_chain'] = o1 + signature_length o3 = offsets['block_hash_tree'] = o2 + share_hash_chain_length assert IV_length == 16 o4 = offsets['IV'] = o3 + block_hash_tree_length o5 = offsets['share_data'] = o4 + IV_length o6 = offsets['enc_privkey'] = o5 + share_data_length o7 = offsets['EOF'] = o6 + encprivkey_length return struct.pack(">LLLLLQQ", offsets['signature'], offsets['share_hash_chain'], offsets['block_hash_tree'], offsets['IV'], offsets['share_data'], offsets['enc_privkey'], offsets['EOF']) # use client.create_mutable_file() to make one of these class MutableFileNode: implements(IMutableFileNode) def __init__(self, client): self._client = client self._pubkey = None # filled in upon first read self._privkey = None # filled in if we're mutable self._sharemap = {} # known shares, shnum-to-[nodeids] self._current_data = None # SDMF: we're allowed to cache the contents self._current_roothash = None # ditto self._current_seqnum = None # ditto def init_from_uri(self, myuri): # we have the URI, but we have not yet retrieved the public # verification key, nor things like 'k' or 'N'. If and when someone # wants to get our contents, we'll pull from shares and fill those # in. self._uri = IMutableFileURI(myuri) self._writekey = self._uri.writekey self._readkey = self._uri.readkey self._storage_index = self._uri.storage_index return self def create(self, initial_contents): """Call this when the filenode is first created. This will generate the keys, generate the initial shares, allocate shares, and upload the initial contents. Returns a Deferred that fires (with the MutableFileNode instance you should use) when it completes. """ self._privkey = "very private" self._pubkey = "public" self._writekey = hashutil.ssk_writekey_hash(self._privkey) self._fingerprint = hashutil.ssk_pubkey_fingerprint_hash(self._pubkey) self._uri = WriteableSSKFileURI(self._writekey, self._fingerprint) d = defer.succeed(None) return d def get_write_enabler(self, nodeid): return hashutil.ssk_write_enabler_hash(self._writekey, nodeid) def get_renewal_secret(self, nodeid): crs = self._client.get_renewal_secret() frs = hashutil.file_renewal_secret_hash(crs, self._storage_index) return hashutil.bucket_renewal_secret_hash(frs, nodeid) def get_cancel_secret(self, nodeid): ccs = self._client.get_cancel_secret() fcs = hashutil.file_cancel_secret_hash(ccs, self._storage_index) return hashutil.bucket_cancel_secret_hash(fcs, nodeid) def get_writekey(self): return self._writekey def get_uri(self): return self._uri.to_string() def is_mutable(self): return self._uri.is_mutable() def __hash__(self): return hash((self.__class__, self.uri)) def __cmp__(self, them): if cmp(type(self), type(them)): return cmp(type(self), type(them)) if cmp(self.__class__, them.__class__): return cmp(self.__class__, them.__class__) return cmp(self.uri, them.uri) def get_verifier(self): return IMutableFileURI(self._uri).get_verifier() def check(self): verifier = self.get_verifier() return self._client.getServiceNamed("checker").check(verifier) def download(self, target): #downloader = self._client.getServiceNamed("downloader") #return downloader.download(self.uri, target) raise NotImplementedError def download_to_data(self): #downloader = self._client.getServiceNamed("downloader") #return downloader.download_to_data(self.uri) return defer.succeed("this isn't going to fool you, is it") def replace(self, newdata): return defer.succeed(None) class Retrieve: def __init__(self, filenode): self._node = filenode class DictOfSets(dict): def add(self, key, value): if key in self: self[key].add(value) else: self[key] = set([value]) class Publish: """I represent a single act of publishing the mutable file to the grid.""" def __init__(self, filenode): self._node = filenode def publish(self, newdata): """Publish the filenode's current contents. Returns a Deferred that fires (with None) when the publish has done as much work as it's ever going to do, or errbacks with ConsistencyError if it detects a simultaneous write.""" # 1: generate shares (SDMF: files are small, so we can do it in RAM) # 2: perform peer selection, get candidate servers # 2a: send queries to n+epsilon servers, to determine current shares # 2b: based upon responses, create target map # 3: send slot_testv_and_readv_and_writev messages # 4: as responses return, update share-dispatch table # 4a: may need to run recovery algorithm # 5: when enough responses are back, we're done old_roothash = self._node._current_roothash old_seqnum = self._node._current_seqnum readkey = self._node.readkey required_shares = self._node.required_shares total_shares = self._node.total_shares privkey = self._node.privkey pubkey = self._node.pubkey d = defer.succeed(newdata) d.addCallback(self._encrypt_and_encode, readkey, required_shares, total_shares) d.addCallback(self._generate_shares, old_seqnum+1, privkey, self._encprivkey, pubkey) d.addCallback(self._query_peers, total_shares) d.addCallback(self._send_shares) d.addCallback(self._maybe_recover) d.addCallback(lambda res: None) return d def _encrypt_and_encode(self, newdata, readkey, required_shares, total_shares): IV = os.urandom(16) key = hashutil.ssk_readkey_data_hash(IV, readkey) enc = AES.new(key=key, mode=AES.MODE_CTR, counterstart="\x00"*16) crypttext = enc.encrypt(newdata) # now apply FEC self.MAX_SEGMENT_SIZE = 1024*1024 segment_size = min(self.MAX_SEGMENT_SIZE, len(crypttext)) # this must be a multiple of self.required_shares segment_size = mathutil.next_multiple(segment_size, required_shares) self.num_segments = mathutil.div_ceil(len(crypttext), segment_size) assert self.num_segments == 1 # SDMF restrictions fec = codec.CRSEncoder() fec.set_params(segment_size, required_shares, total_shares) piece_size = fec.get_block_size() crypttext_pieces = [] for offset in range(0, len(crypttext), piece_size): piece = crypttext[offset:offset+piece_size] if len(piece) < piece_size: pad_size = piece_size - len(piece) piece = piece + "\x00"*pad_size crypttext_pieces.append(piece) assert len(piece) == piece_size d = fec.encode(crypttext_pieces) d.addCallback(lambda shares: (shares, required_shares, total_shares, segment_size, len(crypttext), IV) ) return d def _generate_shares(self, (shares_and_shareids, required_shares, total_shares, segment_size, data_length, IV), seqnum, privkey, encprivkey, pubkey): (shares, share_ids) = shares_and_shareids assert len(shares) == len(share_ids) assert len(shares) == total_shares all_shares = {} block_hash_trees = {} share_hash_leaves = [None] * len(shares) for i in range(len(shares)): share_data = shares[i] shnum = share_ids[i] all_shares[shnum] = share_data # build the block hash tree. SDMF has only one leaf. leaves = [hashutil.block_hash(share_data)] t = hashtree.HashTree(leaves) block_hash_trees[shnum] = block_hash_tree = list(t) share_hash_leaves[shnum] = t[0] for leaf in share_hash_leaves: assert leaf is not None share_hash_tree = hashtree.HashTree(share_hash_leaves) share_hash_chain = {} for shnum in range(total_shares): needed_hashes = share_hash_tree.needed_hashes(shnum) share_hash_chain[shnum] = dict( [ (i, share_hash_tree[i]) for i in needed_hashes ] ) root_hash = share_hash_tree[0] assert len(root_hash) == 32 prefix = pack_prefix(seqnum, root_hash, required_shares, total_shares, segment_size, data_length) # now pack the beginning of the share. All shares are the same up # to the signature, then they have divergent share hash chains, # then completely different block hash trees + IV + share data, # then they all share the same encprivkey at the end. The sizes # of everything are the same for all shares. signature = privkey.sign(prefix) verification_key = pubkey.serialize() final_shares = {} for shnum in range(total_shares): shc = share_hash_chain[shnum] share_hash_chain_s = "".join([struct.pack(">H32s", i, shc[i]) for i in sorted(shc.keys())]) bht = block_hash_trees[shnum] for h in bht: assert len(h) == 32 block_hash_tree_s = "".join(bht) share_data = all_shares[shnum] offsets = pack_offsets(len(verification_key), len(signature), len(share_hash_chain_s), len(block_hash_tree_s), len(IV), len(share_data), len(encprivkey)) final_shares[shnum] = "".join([prefix, offsets, verification_key, signature, share_hash_chain_s, block_hash_tree_s, IV, share_data, encprivkey]) return (seqnum, root_hash, final_shares) def _query_peers(self, (seqnum, root_hash, final_shares), total_shares): self._new_seqnum = seqnum self._new_root_hash = root_hash self._new_shares = final_shares storage_index = self._node._uri.storage_index peerlist = self._node._client.get_permuted_peers(storage_index, include_myself=False) # we don't include ourselves in the N peers, but we *do* push an # extra copy of share[0] to ourselves so we're more likely to have # the signing key around later. This way, even if all the servers die # and the directory contents are unrecoverable, at least we can still # push out a new copy with brand-new contents. current_share_peers = DictOfSets() reachable_peers = {} EPSILON = total_shares / 2 partial_peerlist = itertools.islice(peerlist, total_shares + EPSILON) peer_storage_servers = {} dl = [] for (permutedid, peerid, conn) in partial_peerlist: d = self._do_query(conn, peerid, peer_storage_servers) d.addCallback(self._got_query_results, peerid, permutedid, reachable_peers, current_share_peers) dl.append(d) d = defer.DeferredList(dl) d.addCallback(self._got_all_query_results, total_shares, reachable_peers, seqnum, current_share_peers, peer_storage_servers) # TODO: add an errback to, probably to ignore that peer return d def _do_query(self, conn, peerid, peer_storage_servers): d = conn.callRemote("get_service", "storageserver") def _got_storageserver(ss): peer_storage_servers[peerid] = ss return ss.callRemote("readv_slots", [(0, 2000)]) d.addCallback(_got_storageserver) return d def _got_query_results(self, datavs, peerid, permutedid, reachable_peers, current_share_peers): assert isinstance(datavs, dict) reachable_peers[peerid] = permutedid for shnum, datav in datavs.items(): assert len(datav) == 1 data = datav[0] r = unpack_share(data) share = (shnum, r[0], r[1]) # shnum,seqnum,R current_share_peers[shnum].add( (peerid, r[0], r[1]) ) def _got_all_query_results(self, res, total_shares, reachable_peers, new_seqnum, current_share_peers, peer_storage_servers): # now that we know everything about the shares currently out there, # decide where to place the new shares. # if an old share X is on a node, put the new share X there too. # TODO: 1: redistribute shares to achieve one-per-peer, by copying # shares from existing peers to new (less-crowded) ones. The # old shares must still be updated. # TODO: 2: move those shares instead of copying them, to reduce future # update work shares_needing_homes = range(total_shares) target_map = DictOfSets() # maps shnum to set((peerid,oldseqnum,oldR)) shares_per_peer = DictOfSets() for shnum in range(total_shares): for oldplace in current_share_peers.get(shnum, []): (peerid, seqnum, R) = oldplace if seqnum >= new_seqnum: raise UncoordinatedWriteError() target_map.add(shnum, oldplace) shares_per_peer.add(peerid, shnum) if shnum in shares_needing_homes: shares_needing_homes.remove(shnum) # now choose homes for the remaining shares. We prefer peers with the # fewest target shares, then peers with the lowest permuted index. If # there are no shares already in place, this will assign them # one-per-peer in the normal permuted order. while shares_needing_homes: if not reachable_peers: raise NotEnoughPeersError("ran out of peers during upload") shnum = shares_needing_homes.pop(0) possible_homes = reachable_peers.keys() possible_homes.sort(lambda a,b: cmp( (len(shares_per_peer.get(a, [])), reachable_peers[a]), (len(shares_per_peer.get(b, [])), reachable_peers[b]) )) target_peerid = possible_homes[0] target_map.add(shnum, (target_peerid, None, None) ) shares_per_peer.add(target_peerid, shnum) assert not shares_needing_homes return (target_map, peer_storage_servers) def _send_shares(self, (target_map, peer_storage_servers) ): # we're finally ready to send out our shares. If we encounter any # surprises here, it's because somebody else is writing at the same # time. (Note: in the future, when we remove the _query_peers() step # and instead speculate about [or remember] which shares are where, # surprises here are *not* indications of UncoordinatedWriteError, # and we'll need to respond to them more gracefully. my_checkstring = pack_checkstring(self._new_seqnum, self._new_root_hash) peer_messages = {} expected_old_shares = {} for shnum, peers in target_map.items(): for (peerid, old_seqnum, old_root_hash) in peers: testv = [(0, len(my_checkstring), "ge", my_checkstring)] new_share = self._new_shares[shnum] writev = [(0, new_share)] if peerid not in peer_messages: peer_messages[peerid] = {} peer_messages[peerid][shnum] = (testv, writev, None) if peerid not in expected_old_shares: expected_old_shares[peerid] = {} expected_old_shares[peerid][shnum] = (old_seqnum, old_root_hash) read_vector = [(0, len(my_checkstring))] dl = [] # ok, send the messages! self._surprised = False dispatch_map = DictOfSets() for peerid, tw_vectors in peer_messages.items(): write_enabler = self._node.get_write_enabler(peerid) renew_secret = self._node.get_renewal_secret(peerid) cancel_secret = self._node.get_cancel_secret(peerid) secrets = (write_enabler, renew_secret, cancel_secret) d = self._do_testreadwrite(peerid, peer_storage_servers, secrets, tw_vectors, read_vector) d.addCallback(self._got_write_answer, tw_vectors, my_checkstring, peerid, expected_old_shares[peerid], dispatch_map) dl.append(d) d = defer.DeferredList(dl) d.addCallback(lambda res: (self._surprised, dispatch_map)) return d def _do_testreadwrite(self, peerid, peer_storage_servers, secrets, tw_vectors, read_vector): conn = peer_storage_servers[peerid] storage_index = self._node._uri.storage_index d = conn.callRemote("slot_testv_and_readv_and_writev", storage_index, secrets, tw_vectors, read_vector) return d def _got_write_answer(self, answer, tw_vectors, my_checkstring, peerid, expected_old_shares, dispatch_map): wrote, read_data = answer surprised = False if not wrote: # surprise! our testv failed, so the write did not happen surprised = True for shnum, (old_cs,) in read_data.items(): old_seqnum, old_root_hash = unpack_checkstring(old_cs) if wrote and shnum in tw_vectors: current_cs = my_checkstring else: current_cs = old_cs current_seqnum, current_root_hash = unpack_checkstring(current_cs) dispatch_map.add(shnum, (peerid, current_seqnum, current_root_hash)) if shnum not in expected_old_shares: # surprise! there was a share we didn't know about surprised = True else: seqnum, root_hash = expected_old_shares[shnum] if seqnum is not None: if seqnum != old_seqnum or root_hash != old_root_hash: # surprise! somebody modified the share on us surprised = True if surprised: self._surprised = True def _maybe_recover(self, (surprised, dispatch_map)): if not surprised: return print "RECOVERY NOT YET IMPLEMENTED" # but dispatch_map will help us do it raise UncoordinatedWriteError("I was surprised!")