// VerifyProof checks merkle proofs. The given proof must contain the
// value for key in a trie with the given root hash. VerifyProof
// returns an error if the proof contains invalid trie nodes or the
// wrong value.
func VerifyProof(rootHash common.Hash, key []byte, proof []rlp.RawValue) (value []byte, err error) {
	key = compactHexDecode(key)
	sha := sha3.NewKeccak256()
	wantHash := rootHash.Bytes()
	for i, buf := range proof {
		sha.Reset()
		sha.Write(buf)
		if !bytes.Equal(sha.Sum(nil), wantHash) {
			return nil, fmt.Errorf("bad proof node %d: hash mismatch", i)
		}
		n, err := decodeNode(buf)
		if err != nil {
			return nil, fmt.Errorf("bad proof node %d: %v", i, err)
		}
		keyrest, cld := get(n, key)
		switch cld := cld.(type) {
		case nil:
			if i != len(proof)-1 {
				return nil, fmt.Errorf("key mismatch at proof node %d", i)
			} else {
				// The trie doesn't contain the key.
				return nil, nil
			}
		case hashNode:
			key = keyrest
			wantHash = cld
		case valueNode:
			if i != len(proof)-1 {
				return nil, errors.New("additional nodes at end of proof")
			}
			return cld, nil
		}
	}
	return nil, errors.New("unexpected end of proof")
}

// GetTransaction retrieves a specific transaction from the database, along with
// its added positional metadata.
func GetTransaction(db ethdb.Database, hash common.Hash) (*types.Transaction, common.Hash, uint64, uint64) {
	// Retrieve the transaction itself from the database
	data, _ := db.Get(hash.Bytes())
	if len(data) == 0 {
		return nil, common.Hash{}, 0, 0
	}
	var tx types.Transaction
	if err := rlp.DecodeBytes(data, &tx); err != nil {
		return nil, common.Hash{}, 0, 0
	}
	// Retrieve the blockchain positional metadata
	data, _ = db.Get(append(hash.Bytes(), txMetaSuffix...))
	if len(data) == 0 {
		return nil, common.Hash{}, 0, 0
	}
	var meta struct {
		BlockHash  common.Hash
		BlockIndex uint64
		Index      uint64
	}
	if err := rlp.DecodeBytes(data, &meta); err != nil {
		return nil, common.Hash{}, 0, 0
	}
	return &tx, meta.BlockHash, meta.BlockIndex, meta.Index
}

// AddSubTrie registers a new trie to the sync code, rooted at the designated parent.
func (s *TrieSync) AddSubTrie(root common.Hash, depth int, parent common.Hash, callback TrieSyncLeafCallback) {
	// Short circuit if the trie is empty or already known
	if root == emptyRoot {
		return
	}
	blob, _ := s.database.Get(root.Bytes())
	if local, err := decodeNode(blob); local != nil && err == nil {
		return
	}
	// Assemble the new sub-trie sync request
	node := node(hashNode(root.Bytes()))
	req := &request{
		object:   &node,
		hash:     root,
		depth:    depth,
		callback: callback,
	}
	// If this sub-trie has a designated parent, link them together
	if parent != (common.Hash{}) {
		ancestor := s.requests[parent]
		if ancestor == nil {
			panic(fmt.Sprintf("sub-trie ancestor not found: %x", parent))
		}
		ancestor.deps++
		req.parents = append(req.parents, ancestor)
	}
	s.schedule(req)
}

// HashToUrl(contenthash) resolves the url for contenthash using UrlHint
// resolution is costless non-transactional
// implemented as direct retrieval from  db
// if we use content addressed storage, this step is no longer necessary
func (self *Registrar) HashToUrl(chash common.Hash) (uri string, err error) {
	if zero.MatchString(UrlHintAddr) {
		return "", fmt.Errorf("UrlHint address is not set")
	}
	// look up in URL reg
	var str string = " "
	var idx uint32
	for len(str) > 0 {
		mapaddr := storageMapping(storageIdx2Addr(1), chash[:])
		key := storageAddress(storageFixedArray(mapaddr, storageIdx2Addr(idx)))
		hex := self.backend.StorageAt(UrlHintAddr[2:], key)
		str = string(common.Hex2Bytes(hex[2:]))
		l := 0
		for (l < len(str)) && (str[l] == 0) {
			l++
		}

		str = str[l:]
		uri = uri + str
		idx++
	}

	if len(uri) == 0 {
		err = fmt.Errorf("HashToUrl: URL hint not found for '%v'", chash.Hex())
	}
	return
}

// WriteHeadFastBlockHash stores the fast head block's hash.
func WriteHeadFastBlockHash(db ethdb.Database, hash common.Hash) error {
	if err := db.Put(headFastKey, hash.Bytes()); err != nil {
		glog.Fatalf("failed to store last fast block's hash into database: %v", err)
		return err
	}
	return nil
}

// WriteCanonicalHash stores the canonical hash for the given block number.
func WriteCanonicalHash(db ethdb.Database, hash common.Hash, number uint64) error {
	key := append(blockNumPrefix, big.NewInt(int64(number)).Bytes()...)
	if err := db.Put(key, hash.Bytes()); err != nil {
		glog.Fatalf("failed to store number to hash mapping into database: %v", err)
		return err
	}
	return nil
}

// GetTd retrieves a block's total difficulty corresponding to the hash, nil if
// none found.
func GetTd(db ethdb.Database, hash common.Hash) *big.Int {
	data, _ := db.Get(append(append(blockPrefix, hash.Bytes()...), tdSuffix...))
	if len(data) == 0 {
		return nil
	}
	td := new(big.Int)
	if err := rlp.Decode(bytes.NewReader(data), td); err != nil {
		glog.V(logger.Error).Infof("invalid block total difficulty RLP for hash %x: %v", hash, err)
		return nil
	}
	return td
}

func (self *StateObject) GetState(key common.Hash) common.Hash {
	strkey := key.Str()
	value, exists := self.storage[strkey]
	if !exists {
		value = self.getAddr(key)
		if (value != common.Hash{}) {
			self.storage[strkey] = value
		}
	}

	return value
}

// WriteBody serializes the body of a block into the database.
func WriteBody(db ethdb.Database, hash common.Hash, body *types.Body) error {
	data, err := rlp.EncodeToBytes(body)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, hash.Bytes()...), bodySuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store block body into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block body [%x…]", hash.Bytes()[:4])
	return nil
}

// WriteTd serializes the total difficulty of a block into the database.
func WriteTd(db ethdb.Database, hash common.Hash, td *big.Int) error {
	data, err := rlp.EncodeToBytes(td)
	if err != nil {
		return err
	}
	key := append(append(blockPrefix, hash.Bytes()...), tdSuffix...)
	if err := db.Put(key, data); err != nil {
		glog.Fatalf("failed to store block total difficulty into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block total difficulty [%x…]: %v", hash.Bytes()[:4], td)
	return nil
}

// GetTransactionReceipt returns the transaction receipt for the given transaction hash.
func (s *PublicTransactionPoolAPI) GetTransactionReceipt(txHash common.Hash) (map[string]interface{}, error) {
	receipt := core.GetReceipt(s.chainDb, txHash)
	if receipt == nil {
		glog.V(logger.Debug).Infof("receipt not found for transaction %s", txHash.Hex())
		return nil, nil
	}

	tx, _, err := getTransaction(s.chainDb, s.txPool, txHash)
	if err != nil {
		glog.V(logger.Debug).Infof("%v\n", err)
		return nil, nil
	}

	txBlock, blockIndex, index, err := getTransactionBlockData(s.chainDb, txHash)
	if err != nil {
		glog.V(logger.Debug).Infof("%v\n", err)
		return nil, nil
	}

	from, err := tx.From()
	if err != nil {
		glog.V(logger.Debug).Infof("%v\n", err)
		return nil, nil
	}

	fields := map[string]interface{}{
		"blockHash":         txBlock,
		"blockNumber":       rpc.NewHexNumber(blockIndex),
		"transactionHash":   txHash,
		"transactionIndex":  rpc.NewHexNumber(index),
		"from":              from,
		"to":                tx.To(),
		"gasUsed":           rpc.NewHexNumber(receipt.GasUsed),
		"cumulativeGasUsed": rpc.NewHexNumber(receipt.CumulativeGasUsed),
		"contractAddress":   nil,
		"logs":              receipt.Logs,
	}

	if receipt.Logs == nil {
		fields["logs"] = []vm.Logs{}
	}

	// If the ContractAddress is 20 0x0 bytes, assume it is not a contract creation
	if bytes.Compare(receipt.ContractAddress.Bytes(), bytes.Repeat([]byte{0}, 20)) != 0 {
		fields["contractAddress"] = receipt.ContractAddress
	}

	return fields, nil
}

// New creates a trie with an existing root node from db.
//
// If root is the zero hash or the sha3 hash of an empty string, the
// trie is initially empty and does not require a database. Otherwise,
// New will panic if db is nil and returns a MissingNodeError if root does
// not exist in the database. Accessing the trie loads nodes from db on demand.
func New(root common.Hash, db Database) (*Trie, error) {
	trie := &Trie{db: db, originalRoot: root}
	if (root != common.Hash{}) && root != emptyRoot {
		if db == nil {
			panic("trie.New: cannot use existing root without a database")
		}
		if v, _ := trie.db.Get(root[:]); len(v) == 0 {
			return nil, &MissingNodeError{
				RootHash: root,
				NodeHash: root,
			}
		}
		trie.root = hashNode(root.Bytes())
	}
	return trie, nil
}

func getTransaction(chainDb ethdb.Database, txPool *core.TxPool, txHash common.Hash) (*types.Transaction, bool, error) {
	txData, err := chainDb.Get(txHash.Bytes())
	isPending := false
	tx := new(types.Transaction)

	if err == nil && len(txData) > 0 {
		if err := rlp.DecodeBytes(txData, tx); err != nil {
			return nil, isPending, err
		}
	} else {
		// pending transaction?
		tx = txPool.GetTransaction(txHash)
		isPending = true
	}

	return tx, isPending, nil
}

// HashToHash(key) resolves contenthash for key (a hash) using HashReg
// resolution is costless non-transactional
// implemented as direct retrieval from  db
func (self *Registrar) HashToHash(khash common.Hash) (chash common.Hash, err error) {
	if zero.MatchString(HashRegAddr) {
		return common.Hash{}, fmt.Errorf("HashReg address is not set")
	}

	// look up in hashReg
	at := HashRegAddr[2:]
	key := storageAddress(storageMapping(storageIdx2Addr(1), khash[:]))
	hash := self.backend.StorageAt(at, key)

	if hash == "0x0" || len(hash) < 3 || (hash == common.Hash{}.Hex()) {
		err = fmt.Errorf("HashToHash: content hash not found for '%v'", khash.Hex())
		return
	}
	copy(chash[:], common.Hex2BytesFixed(hash[2:], 32))
	return
}

// WriteBlockReceipts stores all the transaction receipts belonging to a block
// as a single receipt slice. This is used during chain reorganisations for
// rescheduling dropped transactions.
func WriteBlockReceipts(db ethdb.Database, hash common.Hash, receipts types.Receipts) error {
	// Convert the receipts into their storage form and serialize them
	storageReceipts := make([]*types.ReceiptForStorage, len(receipts))
	for i, receipt := range receipts {
		storageReceipts[i] = (*types.ReceiptForStorage)(receipt)
	}
	bytes, err := rlp.EncodeToBytes(storageReceipts)
	if err != nil {
		return err
	}
	// Store the flattened receipt slice
	if err := db.Put(append(blockReceiptsPrefix, hash.Bytes()...), bytes); err != nil {
		glog.Fatalf("failed to store block receipts into database: %v", err)
		return err
	}
	glog.V(logger.Debug).Infof("stored block receipts [%x…]", hash.Bytes()[:4])
	return nil
}

// getTransactionBlockData fetches the meta data for the given transaction from the chain database. This is useful to
// retrieve block information for a hash. It returns the block hash, block index and transaction index.
func getTransactionBlockData(chainDb ethdb.Database, txHash common.Hash) (common.Hash, uint64, uint64, error) {
	var txBlock struct {
		BlockHash  common.Hash
		BlockIndex uint64
		Index      uint64
	}

	blockData, err := chainDb.Get(append(txHash.Bytes(), 0x0001))
	if err != nil {
		return common.Hash{}, uint64(0), uint64(0), err
	}

	reader := bytes.NewReader(blockData)
	if err = rlp.Decode(reader, &txBlock); err != nil {
		return common.Hash{}, uint64(0), uint64(0), err
	}

	return txBlock.BlockHash, txBlock.BlockIndex, txBlock.Index, nil
}

// AddRawEntry schedules the direct retrieval of a state entry that should not be
// interpreted as a trie node, but rather accepted and stored into the database
// as is. This method's goal is to support misc state metadata retrievals (e.g.
// contract code).
func (s *TrieSync) AddRawEntry(hash common.Hash, depth int, parent common.Hash) {
	// Short circuit if the entry is empty or already known
	if hash == emptyState {
		return
	}
	if blob, _ := s.database.Get(hash.Bytes()); blob != nil {
		return
	}
	// Assemble the new sub-trie sync request
	req := &request{
		hash:  hash,
		depth: depth,
	}
	// If this sub-trie has a designated parent, link them together
	if parent != (common.Hash{}) {
		ancestor := s.requests[parent]
		if ancestor == nil {
			panic(fmt.Sprintf("raw-entry ancestor not found: %x", parent))
		}
		ancestor.deps++
		req.parents = append(req.parents, ancestor)
	}
	s.schedule(req)
}

// handleMsg is invoked whenever an inbound message is received from a remote
// peer. The remote connection is torn down upon returning any error.
func (pm *ProtocolManager) handleMsg(p *peer) error {
	// Read the next message from the remote peer, and ensure it's fully consumed
	msg, err := p.rw.ReadMsg()
	if err != nil {
		return err
	}
	if msg.Size > ProtocolMaxMsgSize {
		return errResp(ErrMsgTooLarge, "%v > %v", msg.Size, ProtocolMaxMsgSize)
	}
	defer msg.Discard()

	// Handle the message depending on its contents
	switch {
	case msg.Code == StatusMsg:
		// Status messages should never arrive after the handshake
		return errResp(ErrExtraStatusMsg, "uncontrolled status message")

	case p.version < eth62 && msg.Code == GetBlockHashesMsg:
		// Retrieve the number of hashes to return and from which origin hash
		var request getBlockHashesData
		if err := msg.Decode(&request); err != nil {
			return errResp(ErrDecode, "%v: %v", msg, err)
		}
		if request.Amount > uint64(downloader.MaxHashFetch) {
			request.Amount = uint64(downloader.MaxHashFetch)
		}
		// Retrieve the hashes from the block chain and return them
		hashes := pm.blockchain.GetBlockHashesFromHash(request.Hash, request.Amount)
		if len(hashes) == 0 {
			glog.V(logger.Debug).Infof("invalid block hash %x", request.Hash.Bytes()[:4])
		}
		return p.SendBlockHashes(hashes)

	case p.version < eth62 && msg.Code == GetBlockHashesFromNumberMsg:
		// Retrieve and decode the number of hashes to return and from which origin number
		var request getBlockHashesFromNumberData
		if err := msg.Decode(&request); err != nil {
			return errResp(ErrDecode, "%v: %v", msg, err)
		}
		if request.Amount > uint64(downloader.MaxHashFetch) {
			request.Amount = uint64(downloader.MaxHashFetch)
		}
		// Calculate the last block that should be retrieved, and short circuit if unavailable
		last := pm.blockchain.GetBlockByNumber(request.Number + request.Amount - 1)
		if last == nil {
			last = pm.blockchain.CurrentBlock()
			request.Amount = last.NumberU64() - request.Number + 1
		}
		if last.NumberU64() < request.Number {
			return p.SendBlockHashes(nil)
		}
		// Retrieve the hashes from the last block backwards, reverse and return
		hashes := []common.Hash{last.Hash()}
		hashes = append(hashes, pm.blockchain.GetBlockHashesFromHash(last.Hash(), request.Amount-1)...)

		for i := 0; i < len(hashes)/2; i++ {
			hashes[i], hashes[len(hashes)-1-i] = hashes[len(hashes)-1-i], hashes[i]
		}
		return p.SendBlockHashes(hashes)

	case p.version < eth62 && msg.Code == BlockHashesMsg:
		// A batch of hashes arrived to one of our previous requests
		var hashes []common.Hash
		if err := msg.Decode(&hashes); err != nil {
			break
		}
		// Deliver them all to the downloader for queuing
		err := pm.downloader.DeliverHashes(p.id, hashes)
		if err != nil {
			glog.V(logger.Debug).Infoln(err)
		}

	case p.version < eth62 && msg.Code == GetBlocksMsg:
		// Decode the retrieval message
		msgStream := rlp.NewStream(msg.Payload, uint64(msg.Size))
		if _, err := msgStream.List(); err != nil {
			return err
		}
		// Gather blocks until the fetch or network limits is reached
		var (
			hash   common.Hash
			bytes  common.StorageSize
			blocks []*types.Block
		)
		for len(blocks) < downloader.MaxBlockFetch && bytes < softResponseLimit {
			//Retrieve the hash of the next block
			err := msgStream.Decode(&hash)
			if err == rlp.EOL {
				break
			} else if err != nil {
				return errResp(ErrDecode, "msg %v: %v", msg, err)
			}
			// Retrieve the requested block, stopping if enough was found
			if block := pm.blockchain.GetBlock(hash); block != nil {
				blocks = append(blocks, block)
				bytes += block.Size()
			}
		}
//.........这里部分代码省略.........

// DeleteReceipt removes all receipt data associated with a transaction hash.
func DeleteReceipt(db ethdb.Database, hash common.Hash) {
	db.Delete(append(receiptsPrefix, hash.Bytes()...))
}

// DeleteTransaction removes all transaction data associated with a hash.
func DeleteTransaction(db ethdb.Database, hash common.Hash) {
	db.Delete(hash.Bytes())
	db.Delete(append(hash.Bytes(), txMetaSuffix...))
}