// 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"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/swarm/storage/encryption"
)
type chunkEncryption struct {
spanEncryption encryption.Encryption
dataEncryption encryption.Encryption
}
type hasherStore struct {
store ChunkStore
hashFunc SwarmHasher
chunkEncryption *chunkEncryption
hashSize int // content hash size
refSize int64 // reference size (content hash + possibly encryption key)
wg *sync.WaitGroup
closed chan struct{}
}
func newChunkEncryption(chunkSize, refSize int64) *chunkEncryption {
return &chunkEncryption{
spanEncryption: encryption.New(0, uint32(chunkSize/refSize), sha3.NewKeccak256),
dataEncryption: encryption.New(int(chunkSize), 0, sha3.NewKeccak256),
}
}
// 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(chunkStore ChunkStore, hashFunc SwarmHasher, toEncrypt bool) *hasherStore {
var chunkEncryption *chunkEncryption
hashSize := hashFunc().Size()
refSize := int64(hashSize)
if toEncrypt {
refSize += encryption.KeyLength
chunkEncryption = newChunkEncryption(DefaultChunkSize, refSize)
}
return &hasherStore{
store: chunkStore,
hashFunc: hashFunc,
chunkEncryption: chunkEncryption,
hashSize: hashSize,
refSize: refSize,
wg: &sync.WaitGroup{},
closed: make(chan struct{}),
}
}
// 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(chunkData ChunkData) (Reference, error) {
c := chunkData
size := chunkData.Size()
var encryptionKey encryption.Key
if h.chunkEncryption != nil {
var err error
c, encryptionKey, err = h.encryptChunkData(chunkData)
if err != nil {
return nil, err
}
}
chunk := h.createChunk(c, size)
h.storeChunk(chunk)
return Reference(append(chunk.Addr, 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(ref Reference) (ChunkData, error) {
key, encryptionKey, err := parseReference(ref, h.hashSize)
if err != nil {
return nil, err
}
toDecrypt := (encryptionKey != nil)
chunk, err := h.store.Get(key)
if err != nil {
return nil, err
}
chunkData := chunk.SData
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.closed)
}
// 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 {
<-h.closed
h.wg.Wait()
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, chunkSize int64) *Chunk {
hash := h.createHash(chunkData)
chunk := NewChunk(hash, nil)
chunk.SData = chunkData
chunk.Size = chunkSize
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))
}
encryptionKey, err := encryption.GenerateRandomKey()
if err != nil {
return nil, nil, err
}
encryptedSpan, err := h.chunkEncryption.spanEncryption.Encrypt(chunkData[:8], encryptionKey)
if err != nil {
return nil, nil, err
}
encryptedData, err := h.chunkEncryption.dataEncryption.Encrypt(chunkData[8:], encryptionKey)
if err != nil {
return nil, nil, err
}
c := make(ChunkData, len(encryptedSpan)+len(encryptedData))
copy(c[:8], encryptedSpan)
copy(c[8:], encryptedData)
return c, encryptionKey, 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, err := h.chunkEncryption.spanEncryption.Decrypt(chunkData[:8], encryptionKey)
if err != nil {
return nil, err
}
decryptedData, err := h.chunkEncryption.dataEncryption.Decrypt(chunkData[8:], encryptionKey)
if err != nil {
return nil, err
}
// removing extra bytes which were just added for padding
length := ChunkData(decryptedSpan).Size()
for length > DefaultChunkSize {
length = length + (DefaultChunkSize - 1)
length = length / DefaultChunkSize
length *= h.refSize
}
c := make(ChunkData, length+8)
copy(c[:8], decryptedSpan)
copy(c[8:], decryptedData[:length])
return c[:length+8], nil
}
func (h *hasherStore) RefSize() int64 {
return h.refSize
}
func (h *hasherStore) storeChunk(chunk *Chunk) {
h.wg.Add(1)
go func() {
<-chunk.dbStoredC
h.wg.Done()
}()
h.store.Put(chunk)
}
func parseReference(ref Reference, hashSize int) (Address, encryption.Key, error) {
encryptedKeyLength := hashSize + encryption.KeyLength
switch len(ref) {
case KeyLength:
return Address(ref), nil, nil
case encryptedKeyLength:
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, encryptedKeyLength, len(ref))
}
}
