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hasherstore.go
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hasherstore.go
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// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package storage
import (
"context"
"fmt"
"sync/atomic"
ch "github.com/ethereum/go-ethereum/swarm/chunk"
"github.com/ethereum/go-ethereum/swarm/storage/encryption"
"golang.org/x/crypto/sha3"
)
type hasherStore struct {
store ChunkStore
toEncrypt bool
hashFunc SwarmHasher
hashSize int // content hash size
refSize int64 // reference size (content hash + possibly encryption key)
errC chan error // global error channel
doneC chan struct{} // closed by Close() call to indicate that count is the final number of chunks
quitC chan struct{} // closed to quit unterminated routines
// nrChunks is used with atomic functions
// it is required to be at the end of the struct to ensure 64bit alignment for arm architecture
// see: https://golang.org/pkg/sync/atomic/#pkg-note-BUG
nrChunks uint64 // number of chunks to store
}
// NewHasherStore creates a hasherStore object, which implements Putter and Getter interfaces.
// With the HasherStore you can put and get chunk data (which is just []byte) into a ChunkStore
// and the hasherStore will take core of encryption/decryption of data if necessary
func NewHasherStore(store ChunkStore, hashFunc SwarmHasher, toEncrypt bool) *hasherStore {
hashSize := hashFunc().Size()
refSize := int64(hashSize)
if toEncrypt {
refSize += encryption.KeyLength
}
h := &hasherStore{
store: store,
toEncrypt: toEncrypt,
hashFunc: hashFunc,
hashSize: hashSize,
refSize: refSize,
errC: make(chan error),
doneC: make(chan struct{}),
quitC: make(chan struct{}),
}
return h
}
// Put stores the chunkData into the ChunkStore of the hasherStore and returns the reference.
// If hasherStore has a chunkEncryption object, the data will be encrypted.
// Asynchronous function, the data will not necessarily be stored when it returns.
func (h *hasherStore) Put(ctx context.Context, chunkData ChunkData) (Reference, error) {
c := chunkData
var encryptionKey encryption.Key
if h.toEncrypt {
var err error
c, encryptionKey, err = h.encryptChunkData(chunkData)
if err != nil {
return nil, err
}
}
chunk := h.createChunk(c)
h.storeChunk(ctx, chunk)
return Reference(append(chunk.Address(), encryptionKey...)), nil
}
// Get returns data of the chunk with the given reference (retrieved from the ChunkStore of hasherStore).
// If the data is encrypted and the reference contains an encryption key, it will be decrypted before
// return.
func (h *hasherStore) Get(ctx context.Context, ref Reference) (ChunkData, error) {
addr, encryptionKey, err := parseReference(ref, h.hashSize)
if err != nil {
return nil, err
}
chunk, err := h.store.Get(ctx, addr)
if err != nil {
return nil, err
}
chunkData := ChunkData(chunk.Data())
toDecrypt := (encryptionKey != nil)
if toDecrypt {
var err error
chunkData, err = h.decryptChunkData(chunkData, encryptionKey)
if err != nil {
return nil, err
}
}
return chunkData, nil
}
// Close indicates that no more chunks will be put with the hasherStore, so the Wait
// function can return when all the previously put chunks has been stored.
func (h *hasherStore) Close() {
close(h.doneC)
}
// Wait returns when
// 1) the Close() function has been called and
// 2) all the chunks which has been Put has been stored
func (h *hasherStore) Wait(ctx context.Context) error {
defer close(h.quitC)
var nrStoredChunks uint64 // number of stored chunks
var done bool
doneC := h.doneC
for {
select {
// if context is done earlier, just return with the error
case <-ctx.Done():
return ctx.Err()
// doneC is closed if all chunks have been submitted, from then we just wait until all of them are also stored
case <-doneC:
done = true
doneC = nil
// a chunk has been stored, if err is nil, then successfully, so increase the stored chunk counter
case err := <-h.errC:
if err != nil {
return err
}
nrStoredChunks++
}
// if all the chunks have been submitted and all of them are stored, then we can return
if done {
if nrStoredChunks >= atomic.LoadUint64(&h.nrChunks) {
return nil
}
}
}
}
func (h *hasherStore) createHash(chunkData ChunkData) Address {
hasher := h.hashFunc()
hasher.ResetWithLength(chunkData[:8]) // 8 bytes of length
hasher.Write(chunkData[8:]) // minus 8 []byte length
return hasher.Sum(nil)
}
func (h *hasherStore) createChunk(chunkData ChunkData) *chunk {
hash := h.createHash(chunkData)
chunk := NewChunk(hash, chunkData)
return chunk
}
func (h *hasherStore) encryptChunkData(chunkData ChunkData) (ChunkData, encryption.Key, error) {
if len(chunkData) < 8 {
return nil, nil, fmt.Errorf("Invalid ChunkData, min length 8 got %v", len(chunkData))
}
key, encryptedSpan, encryptedData, err := h.encrypt(chunkData)
if err != nil {
return nil, nil, err
}
c := make(ChunkData, len(encryptedSpan)+len(encryptedData))
copy(c[:8], encryptedSpan)
copy(c[8:], encryptedData)
return c, key, nil
}
func (h *hasherStore) decryptChunkData(chunkData ChunkData, encryptionKey encryption.Key) (ChunkData, error) {
if len(chunkData) < 8 {
return nil, fmt.Errorf("Invalid ChunkData, min length 8 got %v", len(chunkData))
}
decryptedSpan, decryptedData, err := h.decrypt(chunkData, encryptionKey)
if err != nil {
return nil, err
}
// removing extra bytes which were just added for padding
length := ChunkData(decryptedSpan).Size()
for length > ch.DefaultSize {
length = length + (ch.DefaultSize - 1)
length = length / ch.DefaultSize
length *= uint64(h.refSize)
}
c := make(ChunkData, length+8)
copy(c[:8], decryptedSpan)
copy(c[8:], decryptedData[:length])
return c, nil
}
func (h *hasherStore) RefSize() int64 {
return h.refSize
}
func (h *hasherStore) encrypt(chunkData ChunkData) (encryption.Key, []byte, []byte, error) {
key := encryption.GenerateRandomKey(encryption.KeyLength)
encryptedSpan, err := h.newSpanEncryption(key).Encrypt(chunkData[:8])
if err != nil {
return nil, nil, nil, err
}
encryptedData, err := h.newDataEncryption(key).Encrypt(chunkData[8:])
if err != nil {
return nil, nil, nil, err
}
return key, encryptedSpan, encryptedData, nil
}
func (h *hasherStore) decrypt(chunkData ChunkData, key encryption.Key) ([]byte, []byte, error) {
encryptedSpan, err := h.newSpanEncryption(key).Encrypt(chunkData[:8])
if err != nil {
return nil, nil, err
}
encryptedData, err := h.newDataEncryption(key).Encrypt(chunkData[8:])
if err != nil {
return nil, nil, err
}
return encryptedSpan, encryptedData, nil
}
func (h *hasherStore) newSpanEncryption(key encryption.Key) encryption.Encryption {
return encryption.New(key, 0, uint32(ch.DefaultSize/h.refSize), sha3.NewLegacyKeccak256)
}
func (h *hasherStore) newDataEncryption(key encryption.Key) encryption.Encryption {
return encryption.New(key, int(ch.DefaultSize), 0, sha3.NewLegacyKeccak256)
}
func (h *hasherStore) storeChunk(ctx context.Context, chunk *chunk) {
atomic.AddUint64(&h.nrChunks, 1)
go func() {
select {
case h.errC <- h.store.Put(ctx, chunk):
case <-h.quitC:
}
}()
}
func parseReference(ref Reference, hashSize int) (Address, encryption.Key, error) {
encryptedRefLength := hashSize + encryption.KeyLength
switch len(ref) {
case AddressLength:
return Address(ref), nil, nil
case encryptedRefLength:
encKeyIdx := len(ref) - encryption.KeyLength
return Address(ref[:encKeyIdx]), encryption.Key(ref[encKeyIdx:]), nil
default:
return nil, nil, fmt.Errorf("Invalid reference length, expected %v or %v got %v", hashSize, encryptedRefLength, len(ref))
}
}