// 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
}

// 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
}

// 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)
}

// 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
}

// 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(wantHash, 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")
}

// 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
}

// 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
}

// 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 panics if db is nil or 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}
	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, ErrMissingRoot
		}
		trie.root = hashNode(root.Bytes())
	}
	return trie, nil
}

// 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
}

// checkStateConsistency checks that all nodes in a state trie are indeed present.
func checkStateConsistency(db ethdb.Database, root common.Hash) error {
	// Create and iterate a state trie rooted in a sub-node
	if _, err := db.Get(root.Bytes()); err != nil {
		return nil // Consider a non existent state consistent
	}
	state, err := New(root, db)
	if err != nil {
		return err
	}
	it := NewNodeIterator(state)
	for it.Next() {
	}
	return it.Error
}

// GetState returns the storage value at the given address from either the cache
// or the trie
func (self *StateObject) GetState(ctx context.Context, key common.Hash) (common.Hash, error) {
	strkey := key.Str()
	value, exists := self.storage[strkey]
	if !exists {
		var err error
		value, err = self.getAddr(ctx, key)
		if err != nil {
			return common.Hash{}, err
		}
		if (value != common.Hash{}) {
			self.storage[strkey] = value
		}
	}

	return value, nil
}

func (self *XEth) doSign(from common.Address, hash common.Hash, didUnlock bool) ([]byte, error) {
	sig, err := self.backend.AccountManager().Sign(accounts.Account{Address: from}, hash.Bytes())
	if err == accounts.ErrLocked {
		if didUnlock {
			return nil, fmt.Errorf("signer account still locked after successful unlock")
		}
		if !self.frontend.UnlockAccount(from.Bytes()) {
			return nil, fmt.Errorf("could not unlock signer account")
		}
		// retry signing, the account should now be unlocked.
		return self.doSign(from, hash, true)
	} else if err != nil {
		return nil, err
	}
	return sig, 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
}

// 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")

	// Block header query, collect the requested headers and reply
	case msg.Code == GetBlockHeadersMsg:
		// Decode the complex header query
		var query getBlockHeadersData
		if err := msg.Decode(&query); err != nil {
			return errResp(ErrDecode, "%v: %v", msg, err)
		}
		hashMode := query.Origin.Hash != (common.Hash{})

		// Gather headers until the fetch or network limits is reached
		var (
			bytes   common.StorageSize
			headers []*types.Header
			unknown bool
		)
		for !unknown && len(headers) < int(query.Amount) && bytes < softResponseLimit && len(headers) < downloader.MaxHeaderFetch {
			// Retrieve the next header satisfying the query
			var origin *types.Header
			if hashMode {
				origin = pm.blockchain.GetHeader(query.Origin.Hash)
			} else {
				origin = pm.blockchain.GetHeaderByNumber(query.Origin.Number)
			}
			if origin == nil {
				break
			}
			headers = append(headers, origin)
			bytes += estHeaderRlpSize

			// Advance to the next header of the query
			switch {
			case query.Origin.Hash != (common.Hash{}) && query.Reverse:
				// Hash based traversal towards the genesis block
				for i := 0; i < int(query.Skip)+1; i++ {
					if header := pm.blockchain.GetHeader(query.Origin.Hash); header != nil {
						query.Origin.Hash = header.ParentHash
					} else {
						unknown = true
						break
					}
				}
			case query.Origin.Hash != (common.Hash{}) && !query.Reverse:
				// Hash based traversal towards the leaf block
				var (
					current = origin.Number.Uint64()
					next    = current + query.Skip + 1
				)
				if next <= current {
					infos, _ := json.MarshalIndent(p.Peer.Info(), "", "  ")
					glog.V(logger.Warn).Infof("%v: GetBlockHeaders skip overflow attack (current %v, skip %v, next %v)\nMalicious peer infos: %s", p, current, query.Skip, next, infos)
					unknown = true
				} else {
					if header := pm.blockchain.GetHeaderByNumber(next); header != nil {
						if pm.blockchain.GetBlockHashesFromHash(header.Hash(), query.Skip+1)[query.Skip] == query.Origin.Hash {
							query.Origin.Hash = header.Hash()
						} else {
							unknown = true
						}
					} else {
						unknown = true
					}
				}
			case query.Reverse:
				// Number based traversal towards the genesis block
				if query.Origin.Number >= query.Skip+1 {
					query.Origin.Number -= (query.Skip + 1)
				} else {
					unknown = true
				}

			case !query.Reverse:
				// Number based traversal towards the leaf block
				query.Origin.Number += (query.Skip + 1)
			}
		}
		return p.SendBlockHeaders(headers)

	case msg.Code == BlockHeadersMsg:
		// A batch of headers arrived to one of our previous requests
		var headers []*types.Header
		if err := msg.Decode(&headers); err != nil {
//.........这里部分代码省略.........

func (self *StateObject) SetState(k, value common.Hash) {
	self.storage[k.Str()] = value
	self.dirty = true
}

// banBlocks retrieves a batch of blocks from a peer feeding us invalid hashes,
// and bans the head of the retrieved batch.
//
// This method only fetches one single batch as the goal is not ban an entire
// (potentially long) invalid chain - wasting a lot of time in the meanwhile -,
// but rather to gradually build up a blacklist if the peer keeps reconnecting.
func (d *Downloader) banBlocks(peerId string, head common.Hash) error {
	glog.V(logger.Debug).Infof("Banning a batch out of %d blocks from %s", d.queue.Pending(), peerId)

	// Ask the peer being banned for a batch of blocks from the banning point
	peer := d.peers.Peer(peerId)
	if peer == nil {
		return nil
	}
	request := d.queue.Reserve(peer, MaxBlockFetch)
	if request == nil {
		return nil
	}
	if err := peer.Fetch(request); err != nil {
		return err
	}
	// Wait a bit for the reply to arrive, and ban if done so
	timeout := time.After(blockHardTTL)
	for {
		select {
		case <-d.cancelCh:
			return errCancelBlockFetch

		case <-timeout:
			return errTimeout

		case <-d.hashCh:
			// Out of bounds hashes received, ignore them

		case blockPack := <-d.blockCh:
			blocks := blockPack.blocks

			// Short circuit if it's a stale cross check
			if len(blocks) == 1 {
				block := blocks[0]
				if _, ok := d.checks[block.Hash()]; ok {
					delete(d.checks, block.Hash())
					break
				}
			}
			// Short circuit if it's not from the peer being banned
			if blockPack.peerId != peerId {
				break
			}
			// Short circuit if no blocks were returned
			if len(blocks) == 0 {
				return errors.New("no blocks returned to ban")
			}
			// Reconstruct the original chain order and ensure we're banning the correct blocks
			types.BlockBy(types.Number).Sort(blocks)
			if bytes.Compare(blocks[0].Hash().Bytes(), head.Bytes()) != 0 {
				return errors.New("head block not the banned one")
			}
			index := 0
			for _, block := range blocks[1:] {
				if bytes.Compare(block.ParentHash().Bytes(), blocks[index].Hash().Bytes()) != 0 {
					break
				}
				index++
			}
			// Ban the head hash and phase out any excess
			d.banned.Add(blocks[index].Hash())
			for d.banned.Size() > maxBannedHashes {
				var evacuate common.Hash

				d.banned.Each(func(item interface{}) bool {
					// Skip any hard coded bans
					if core.BadHashes[item.(common.Hash)] {
						return true
					}
					evacuate = item.(common.Hash)
					return false
				})
				d.banned.Remove(evacuate)
			}
			glog.V(logger.Debug).Infof("Banned %d blocks from: %s", index+1, peerId)
			return nil
		}
	}
}