lbcd/rpcserver.go

// Copyright (c) 2013 Conformal Systems LLC.
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"code.google.com/p/go.crypto/ripemd160"
	"code.google.com/p/go.net/websocket"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"github.com/conformal/btcchain"
	"github.com/conformal/btcdb"
	"github.com/conformal/btcjson"
	"github.com/conformal/btcscript"
	"github.com/conformal/btcutil"
	"github.com/conformal/btcwire"
	"math/big"
	"net"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
)

// Errors
var (
	// ErrBadParamsField describes an error where the parameters JSON
	// field cannot be properly parsed.
	ErrBadParamsField = errors.New("bad params field")
)

// rpcServer holds the items the rpc server may need to access (config,
// shutdown, main server, etc.)
type rpcServer struct {
	started   int32
	shutdown  int32
	server    *server
	ws        wsContext
	wg        sync.WaitGroup
	rpcport   string
	username  string
	password  string
	listeners []net.Listener
	quit      chan int
}

// wsContext holds the items the RPC server needs to handle websocket
// connections for wallets.
type wsContext struct {
	// walletListeners holds a map of each currently connected wallet
	// listener as the key.  The value is ignored, as this is only used as
	// a set.  A mutex is used to prevent incorrect multiple access.
	walletListeners struct {
		sync.RWMutex
		m map[chan []byte]bool
	}

	// requests holds all wallet notification requests.
	requests wsRequests

	// Any chain notifications meant to be received by every connected
	// wallet are sent across this channel.
	walletNotificationMaster chan []byte
}

// wsRequests maps request contexts for wallet notifications to a
// wallet notification channel.  A Mutex is used to protect incorrect
// concurrent access to the map.
type wsRequests struct {
	sync.Mutex
	m map[chan []byte]*requestContexts
}

// getOrCreateContexts gets the request contexts, or creates and adds a
// new context if one for this wallet is not already present.
func (r *wsRequests) getOrCreateContexts(walletNotification chan []byte) *requestContexts {
	rc, ok := r.m[walletNotification]
	if !ok {
		rc = &requestContexts{
			txRequests:      make(map[addressHash]interface{}),
			spentRequests:   make(map[btcwire.OutPoint]interface{}),
			minedTxRequests: make(map[btcwire.ShaHash]bool),
		}
		r.m[walletNotification] = rc
	}
	return rc
}

// AddTxRequest adds the request context for new transaction notifications.
func (r *wsRequests) AddTxRequest(walletNotification chan []byte, addr addressHash, id interface{}) {
	r.Lock()
	defer r.Unlock()

	rc := r.getOrCreateContexts(walletNotification)
	rc.txRequests[addr] = id
}

// AddSpentRequest adds a request context for notifications of a spent
// Outpoint.
func (r *wsRequests) AddSpentRequest(walletNotification chan []byte, op *btcwire.OutPoint, id interface{}) {
	r.Lock()
	defer r.Unlock()

	rc := r.getOrCreateContexts(walletNotification)
	rc.spentRequests[*op] = id
}

// RemoveSpentRequest removes a request context for notifications of a
// spent Outpoint.
func (r *wsRequests) RemoveSpentRequest(walletNotification chan []byte, op *btcwire.OutPoint) {
	r.Lock()
	defer r.Unlock()

	rc := r.getOrCreateContexts(walletNotification)
	delete(rc.spentRequests, *op)
}

// AddMinedTxRequest adds request contexts for notifications of a
// mined transaction.
func (r *wsRequests) AddMinedTxRequest(walletNotification chan []byte, txID *btcwire.ShaHash) {
	r.Lock()
	defer r.Unlock()

	rc := r.getOrCreateContexts(walletNotification)
	rc.minedTxRequests[*txID] = true
}

// RemoveMinedTxRequest removes request contexts for notifications of a
// mined transaction.
func (r *wsRequests) RemoveMinedTxRequest(walletNotification chan []byte, txID *btcwire.ShaHash) {
	r.Lock()
	defer r.Unlock()

	rc := r.getOrCreateContexts(walletNotification)
	delete(rc.minedTxRequests, *txID)
}

// CloseListeners removes all request contexts for notifications sent
// to a wallet notification channel and closes the channel to stop all
// goroutines currently serving that wallet.
func (r *wsRequests) CloseListeners(walletNotification chan []byte) {
	r.Lock()
	defer r.Unlock()

	delete(r.m, walletNotification)
	close(walletNotification)
}

type addressHash [ripemd160.Size]byte

// requestContexts holds all requests for a single wallet connection.
type requestContexts struct {
	// txRequests maps between a 160-byte pubkey hash and the JSON
	// id of the requester so replies can be correctly routed back
	// to the correct btcwallet callback.
	txRequests map[addressHash]interface{}

	// spentRequests maps between an Outpoint of an unspent
	// transaction output and the JSON id of the requester so
	// replies can be correctly routed back to the correct
	// btcwallet callback.
	spentRequests map[btcwire.OutPoint]interface{}

	// minedTxRequests holds a set of transaction IDs (tx hashes) of
	// transactions created by a wallet. A wallet may request
	// notifications of when a tx it created is mined into a block and
	// removed from the mempool.  Once a tx has been mined into a
	// block, wallet may remove the raw transaction from its unmined tx
	// pool.
	minedTxRequests map[btcwire.ShaHash]bool
}

// Start is used by server.go to start the rpc listener.
func (s *rpcServer) Start() {
	if atomic.AddInt32(&s.started, 1) != 1 {
		return
	}

	log.Trace("RPCS: Starting RPC server")
	rpcServeMux := http.NewServeMux()
	httpServer := &http.Server{Handler: rpcServeMux}
	rpcServeMux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		login := s.username + ":" + s.password
		auth := "Basic " + base64.StdEncoding.EncodeToString([]byte(login))
		authhdr := r.Header["Authorization"]
		if len(authhdr) > 0 && authhdr[0] == auth {
			jsonRPCRead(w, r, s)
		} else {
			log.Warnf("RPCS: Auth failure.")
			jsonAuthFail(w, r, s)
		}
	})
	go s.walletListenerDuplicator()
	rpcServeMux.Handle("/wallet", websocket.Handler(func(ws *websocket.Conn) {
		s.walletReqsNotifications(ws)
	}))
	for _, listener := range s.listeners {
		s.wg.Add(1)
		go func(listener net.Listener) {
			log.Infof("RPCS: RPC server listening on %s", listener.Addr())
			httpServer.Serve(listener)
			log.Tracef("RPCS: RPC listener done for %s", listener.Addr())
			s.wg.Done()
		}(listener)
	}
}

// Stop is used by server.go to stop the rpc listener.
func (s *rpcServer) Stop() error {
	if atomic.AddInt32(&s.shutdown, 1) != 1 {
		log.Infof("RPCS: RPC server is already in the process of shutting down")
		return nil
	}
	log.Warnf("RPCS: RPC server shutting down")
	for _, listener := range s.listeners {
		err := listener.Close()
		if err != nil {
			log.Errorf("RPCS: Problem shutting down rpc: %v", err)
			return err
		}
	}
	log.Infof("RPCS: RPC server shutdown complete")
	s.wg.Wait()
	close(s.quit)
	return nil
}

// newRPCServer returns a new instance of the rpcServer struct.
func newRPCServer(s *server) (*rpcServer, error) {
	rpc := rpcServer{
		server: s,
		quit:   make(chan int),
	}
	// Get values from config
	rpc.rpcport = cfg.RPCPort
	rpc.username = cfg.RPCUser
	rpc.password = cfg.RPCPass

	// initialize memory for websocket connections
	rpc.ws.requests.m = make(map[chan []byte]*requestContexts)
	rpc.ws.walletListeners.m = make(map[chan []byte]bool)
	rpc.ws.walletNotificationMaster = make(chan []byte)

	// IPv4 listener.
	var listeners []net.Listener
	listenAddr4 := net.JoinHostPort("127.0.0.1", rpc.rpcport)
	listener4, err := net.Listen("tcp4", listenAddr4)
	if err != nil {
		log.Errorf("RPCS: Couldn't create listener: %v", err)
		return nil, err
	}
	listeners = append(listeners, listener4)

	// IPv6 listener.
	listenAddr6 := net.JoinHostPort("::1", rpc.rpcport)
	listener6, err := net.Listen("tcp6", listenAddr6)
	if err != nil {
		log.Errorf("RPCS: Couldn't create listener: %v", err)
		return nil, err
	}
	listeners = append(listeners, listener6)

	rpc.listeners = listeners

	return &rpc, err
}

// jsonAuthFail sends a message back to the client if the http auth is rejected.
func jsonAuthFail(w http.ResponseWriter, r *http.Request, s *rpcServer) {
	fmt.Fprint(w, "401 Unauthorized.\n")
}

// jsonRPCRead is the RPC wrapper around the jsonRead function to handles
// reading and responding to RPC messages.
func jsonRPCRead(w http.ResponseWriter, r *http.Request, s *rpcServer) {
	r.Close = true
	if atomic.LoadInt32(&s.shutdown) != 0 {
		return
	}
	body, err := btcjson.GetRaw(r.Body)
	if err != nil {
		log.Errorf("RPCS: Error getting json message: %v", err)
		return
	}

	// Error is intentionally ignored here.  It's used in in the
	// websocket handler to tell when a method is not supported by
	// the standard RPC API, and is not needed here.  Error logging
	// is done inside jsonRead, so no need to log the error here.
	reply, _ := jsonRead(body, s, nil)
	log.Tracef("[RPCS] reply: %v", reply)

	msg, err := btcjson.MarshallAndSend(reply, w)
	if err != nil {
		log.Errorf(msg)
		return
	}
	log.Debugf(msg)
}

type commandHandler func(*rpcServer, btcjson.Cmd, chan []byte) (interface{}, error)

var handlers = map[string]commandHandler{
	"addnode":              handleAddNode,
	"decoderawtransaction": handleDecodeRawTransaction,
	"getbestblockhash":     handleGetBestBlockHash,
	"getblock":             handleGetBlock,
	"getblockcount":        handleGetBlockCount,
	"getblockhash":         handleGetBlockHash,
	"getconnectioncount":   handleGetConnectionCount,
	"getdifficulty":        handleGetDifficulty,
	"getgenerate":          handleGetGenerate,
	"gethashespersec":      handleGetHashesPerSec,
	"getpeerinfo":          handleGetPeerInfo,
	"getrawmempool":        handleGetRawMempool,
	"getrawtransaction":    handleGetRawTransaction,
	"sendrawtransaction":   handleSendRawTransaction,
	"setgenerate":          handleSetGenerate,
	"stop":                 handleStop,
}

// handleDecodeRawTransaction handles decoderawtransaction commands.
func handleAddNode(s *rpcServer, cmd btcjson.Cmd,
	walletNotification chan []byte) (interface{}, error) {
	c := cmd.(*btcjson.AddNodeCmd)

	addr := normalizePeerAddress(c.Addr)
	var err error
	switch c.SubCmd {
	case "add":
		err = s.server.AddAddr(addr, true)
	case "remove":
		err = s.server.RemoveAddr(addr)
	case "onetry":
		err = s.server.AddAddr(addr, false)
	default:
		err = errors.New("Invalid subcommand for addnode")
	}

	// no data returned unless an error.
	return nil, err
}

// handleDecodeRawTransaction handles decoderawtransaction commands.
func handleDecodeRawTransaction(s *rpcServer, cmd btcjson.Cmd,
	walletNotification chan []byte) (interface{}, error) {
	// TODO: use c.HexTx and fill result with info.
	return btcjson.TxRawDecodeResult{}, nil
}

// handleGetBestBlockHash implements the getbestblockhash command.
func handleGetBestBlockHash(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	var sha *btcwire.ShaHash
	sha, _, err := s.server.db.NewestSha()
	if err != nil {
		log.Errorf("RPCS: Error getting newest sha: %v", err)
		return nil, btcjson.ErrBestBlockHash
	}

	return sha.String, nil
}

// handleGetBlock implements the getblock command.
func handleGetBlock(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	c := cmd.(*btcjson.GetBlockCmd)
	sha, err := btcwire.NewShaHashFromStr(c.Hash)
	if err != nil {
		log.Errorf("RPCS: Error generating sha: %v", err)
		return nil, btcjson.ErrBlockNotFound
	}
	blk, err := s.server.db.FetchBlockBySha(sha)
	if err != nil {
		log.Errorf("RPCS: Error fetching sha: %v", err)
		return nil, btcjson.ErrBlockNotFound
	}
	idx := blk.Height()
	buf, err := blk.Bytes()
	if err != nil {
		log.Errorf("RPCS: Error fetching block: %v", err)
		return nil, btcjson.ErrBlockNotFound
	}

	txList, _ := blk.TxShas()

	txNames := make([]string, len(txList))
	for i, v := range txList {
		txNames[i] = v.String()
	}

	_, maxidx, err := s.server.db.NewestSha()
	if err != nil {
		log.Errorf("RPCS: Cannot get newest sha: %v", err)
		return nil, btcjson.ErrBlockNotFound
	}

	blockHeader := &blk.MsgBlock().Header
	blockReply := btcjson.BlockResult{
		Hash:          c.Hash,
		Version:       blockHeader.Version,
		MerkleRoot:    blockHeader.MerkleRoot.String(),
		PreviousHash:  blockHeader.PrevBlock.String(),
		Nonce:         blockHeader.Nonce,
		Time:          blockHeader.Timestamp.Unix(),
		Confirmations: uint64(1 + maxidx - idx),
		Height:        idx,
		Tx:            txNames,
		Size:          len(buf),
		Bits:          strconv.FormatInt(int64(blockHeader.Bits), 16),
		Difficulty:    getDifficultyRatio(blockHeader.Bits),
	}

	// Get next block unless we are already at the top.
	if idx < maxidx {
		var shaNext *btcwire.ShaHash
		shaNext, err = s.server.db.FetchBlockShaByHeight(int64(idx + 1))
		if err != nil {
			log.Errorf("RPCS: No next block: %v", err)
			return nil, btcjson.ErrBlockNotFound
		}
		blockReply.NextHash = shaNext.String()
	}

	return blockReply, nil
}

// handleGetBlockCount implements the getblockcount command.
func handleGetBlockCount(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	_, maxidx, err := s.server.db.NewestSha()
	if err != nil {
		log.Errorf("RPCS: Error getting newest sha: %v", err)
		return nil, btcjson.ErrBlockCount
	}

	return maxidx, nil
}

// handleGetBlockHash implements the getblockhash command.
func handleGetBlockHash(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	c := cmd.(*btcjson.GetBlockHashCmd)
	sha, err := s.server.db.FetchBlockShaByHeight(c.Index)
	if err != nil {
		log.Errorf("[RCPS] Error getting block: %v", err)
		return nil, btcjson.ErrOutOfRange
	}

	return sha.String(), nil
}

// handleGetConnectionCount implements the getconnectioncount command.
func handleGetConnectionCount(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	return s.server.ConnectedCount(), nil
}

// handleGetDifficulty implements the getdifficulty command.
func handleGetDifficulty(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	sha, _, err := s.server.db.NewestSha()
	if err != nil {
		log.Errorf("RPCS: Error getting sha: %v", err)
		return nil, btcjson.ErrDifficulty
	}
	blk, err := s.server.db.FetchBlockBySha(sha)
	if err != nil {
		log.Errorf("RPCS: Error getting block: %v", err)
		return nil, btcjson.ErrDifficulty
	}
	blockHeader := &blk.MsgBlock().Header

	return getDifficultyRatio(blockHeader.Bits), nil
}

// handleGetGenerate implements the getgenerate command.
func handleGetGenerate(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	// btcd does not do mining so we can hardcode replies here.
	return false, nil
}

// handleGetHashesPerSec implements the gethashespersec command.
func handleGetHashesPerSec(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	// btcd does not do mining so we can hardcode replies here.
	return 0, nil
}

// handleGetPeerInfo implements the getpeerinfo command.
func handleGetPeerInfo(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	return s.server.PeerInfo(), nil
}

// handleGetRawMempool implements the getrawmempool command.
func handleGetRawMempool(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	hashes := s.server.txMemPool.TxShas()
	hashStrings := make([]string, len(hashes))
	for i := 0; i < len(hashes); i++ {
		hashStrings[i] = hashes[i].String()
	}
	return hashStrings, nil
}

// handleGetRawTransaction implements the getrawtransaction command.
func handleGetRawTransaction(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	c := cmd.(*btcjson.GetRawTransactionCmd)
	if c.Verbose {
		// TODO: check error code. tx is not checked before
		// this point.
		txSha, _ := btcwire.NewShaHashFromStr(c.Txid)
		txList, err := s.server.db.FetchTxBySha(txSha)
		if err != nil {
			log.Errorf("RPCS: Error fetching tx: %v", err)
			return nil, btcjson.ErrNoTxInfo
		}

		lastTx := len(txList) - 1
		txS := txList[lastTx].Tx
		blksha := txList[lastTx].BlkSha
		blk, err := s.server.db.FetchBlockBySha(blksha)
		if err != nil {
			log.Errorf("RPCS: Error fetching sha: %v", err)
			return nil, btcjson.ErrBlockNotFound
		}
		idx := blk.Height()

		txOutList := txS.TxOut
		voutList := make([]btcjson.Vout, len(txOutList))

		txInList := txS.TxIn
		vinList := make([]btcjson.Vin, len(txInList))

		for i, v := range txInList {
			vinList[i].Sequence = float64(v.Sequence)
			disbuf, _ := btcscript.DisasmString(v.SignatureScript)
			vinList[i].ScriptSig.Asm = strings.Replace(disbuf, " ", "", -1)
			vinList[i].Vout = i + 1
			log.Debugf(disbuf)
		}

		for i, v := range txOutList {
			voutList[i].N = i
			voutList[i].Value = float64(v.Value) / 100000000
			isbuf, _ := btcscript.DisasmString(v.PkScript)
			voutList[i].ScriptPubKey.Asm = isbuf
			voutList[i].ScriptPubKey.ReqSig = strings.Count(isbuf, "OP_CHECKSIG")
			_, addrhash, err := btcscript.ScriptToAddrHash(v.PkScript)
			if err != nil {
				// TODO: set and return error?
				log.Errorf("RPCS: Error getting address hash for %v: %v", txSha, err)
			}
			if addr, err := btcutil.EncodeAddress(addrhash, s.server.btcnet); err != nil {
				// TODO: set and return error?
				addrList := make([]string, 1)
				addrList[0] = addr
				voutList[i].ScriptPubKey.Addresses = addrList
			}
		}

		_, maxidx, err := s.server.db.NewestSha()
		if err != nil {
			log.Errorf("RPCS: Cannot get newest sha: %v", err)
			return nil, btcjson.ErrNoNewestBlockInfo
		}
		confirmations := uint64(1 + maxidx - idx)

		blockHeader := &blk.MsgBlock().Header
		txReply := btcjson.TxRawResult{
			Txid:     c.Txid,
			Vout:     voutList,
			Vin:      vinList,
			Version:  txS.Version,
			LockTime: txS.LockTime,
			// This is not a typo, they are identical in
			// bitcoind as well.
			Time:          blockHeader.Timestamp.Unix(),
			Blocktime:     blockHeader.Timestamp.Unix(),
			BlockHash:     blksha.String(),
			Confirmations: confirmations,
		}
		return txReply, nil
	} else {
		// Don't return details
		// not used yet
		return nil, nil
	}
}

// handleSendRawTransaction implements the sendrawtransaction command.
func handleSendRawTransaction(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	c := cmd.(*btcjson.SendRawTransactionCmd)
	// Deserialize and send off to tx relay
	serializedTx, err := hex.DecodeString(c.HexTx)
	if err != nil {
		return nil, btcjson.ErrDecodeHexString
	}
	msgtx := btcwire.NewMsgTx()
	err = msgtx.Deserialize(bytes.NewBuffer(serializedTx))
	if err != nil {
		err := btcjson.Error{
			Code:    btcjson.ErrDeserialization.Code,
			Message: "Unable to deserialize raw tx",
		}
		return nil, err
	}
	tx := btcutil.NewTx(msgtx)
	err = s.server.txMemPool.ProcessTransaction(tx)
	if err != nil {
		log.Errorf("RPCS: Failed to process transaction: %v", err)
		err = btcjson.Error{
			Code:    btcjson.ErrDeserialization.Code,
			Message: "Failed to process transaction",
		}
		return nil, err
	}

	txsha := tx.Sha()

	// If called from websocket code, add a mined tx hashes
	// request.
	if walletNotification != nil {
		s.ws.requests.AddMinedTxRequest(walletNotification, txsha)
	}

	return txsha.String(), nil
}

// handleSetGenerate implements the setgenerate command.
func handleSetGenerate(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	// btcd does not do mining so we can hardcode replies here.
	return nil, nil
}

// handleStop implements the stop command.
func handleStop(s *rpcServer, cmd btcjson.Cmd, walletNotification chan []byte) (interface{}, error) {
	s.server.Stop()
	return "btcd stopping.", nil
}

// jsonRead abstracts the JSON unmarshalling and reply handling used
// by both RPC and websockets.  If called from websocket code, a non-nil
// wallet notification channel can be used to automatically register
// various notifications for the wallet.
func jsonRead(body []byte, s *rpcServer, walletNotification chan []byte) (reply btcjson.Reply, err error) {
	cmd, err := btcjson.ParseMarshaledCmd(body)
	if err != nil {
		var id interface{}
		if cmd != nil {
			// Unmarshaling a valid JSON-RPC message succeeded.  Use
			// the provided id for errors.
			id = cmd.Id()
		}

		if jsonErr, ok := err.(btcjson.Error); ok {
			reply = btcjson.Reply{
				Result: nil,
				Error:  &jsonErr,
				Id:     &id,
			}
		} else {
			reply = btcjson.Reply{
				Result: nil,
				Error:  &jsonErr,
				Id:     &id,
			}
		}

		log.Tracef("RPCS: reply: %v", reply)

		return reply, err
	}
	log.Tracef("RPCS: received: %v", cmd)

	id := cmd.Id()

	handler, ok := handlers[cmd.Method()]
	if !ok {
		reply = btcjson.Reply{
			Result: nil,
			Error:  &btcjson.ErrMethodNotFound,
			Id:     &id,
		}
		return reply, btcjson.ErrMethodNotFound
	}

	result, err := handler(s, cmd, walletNotification)
	if err != nil {
		if jsonErr, ok := err.(btcjson.Error); ok {
			reply = btcjson.Reply{
				Error: &jsonErr,
				Id:    &id,
			}
			err = errors.New(jsonErr.Message)
		} else {
			// In the case where we did not have a btcjson
			// error to begin with, make a new one to send,
			// but this really should not happen.
			rawJSONError := btcjson.Error{
				Code:    btcjson.ErrInternal.Code,
				Message: err.Error(),
			}
			reply = btcjson.Reply{
				Error: &rawJSONError,
				Id:    &id,
			}
		}
	} else {
		reply = btcjson.Reply{
			Result: result,
			Id:     &id,
		}
	}

	return reply, err
}

func jsonWSRead(walletNotification chan []byte, replychan chan *btcjson.Reply, body []byte, s *rpcServer) error {
	var message btcjson.Message
	err := json.Unmarshal(body, &message)
	if err != nil {
		reply := btcjson.Reply{
			Result: nil,
			Error:  &btcjson.ErrParse,
			Id:     nil,
		}

		log.Tracef("RPCS: reply: %v", reply)

		replychan <- &reply
		return fmt.Errorf("RPCS: Error unmarshalling json message: %v", err)
	}
	log.Tracef("RPCS: received: %v", message)

	var rawReply btcjson.Reply
	defer func() {
		replychan <- &rawReply
		close(replychan)
	}()

	// Deal with commands
	switch message.Method {
	case "getcurrentnet":
		var net btcwire.BitcoinNet
		if cfg.TestNet3 {
			net = btcwire.TestNet3
		} else {
			net = btcwire.MainNet
		}
		rawReply = btcjson.Reply{
			Result: float64(net),
			Id:     &message.Id,
		}

	case "rescan":
		var addr string
		minblock, maxblock := int64(0), btcdb.AllShas
		params, ok := message.Params.([]interface{})
		if !ok {
			return ErrBadParamsField
		}
		for i, v := range params {
			switch v.(type) {
			case string:
				if i == 0 {
					addr = v.(string)
				}
			case float64:
				if i == 1 {
					minblock = int64(v.(float64))
				} else if i == 2 {
					maxblock = int64(v.(float64))
				}
			}
		}
		addrhash, _, err := btcutil.DecodeAddress(addr)
		if err != nil {
			return err
		}

		// FetchHeightRange may not return a complete list of block shas for
		// the given range, so fetch range as many times as necessary.
		for {
			blkshalist, err := s.server.db.FetchHeightRange(minblock, maxblock)
			if err != nil {
				return err
			}
			if len(blkshalist) == 0 {
				break
			}

			for i := range blkshalist {
				blk, err := s.server.db.FetchBlockBySha(&blkshalist[i])
				if err != nil {
					return err
				}
				txShaList, err := blk.TxShas()
				if err != nil {
					return err
				}
				txList := s.server.db.FetchTxByShaList(txShaList)
				for _, txReply := range txList {
					if txReply.Err != nil || txReply.Tx == nil {
						continue
					}
					for _, txout := range txReply.Tx.TxOut {
						_, txaddrhash, err := btcscript.ScriptToAddrHash(txout.PkScript)
						if err != nil {
							return err
						}
						if !bytes.Equal(addrhash, txaddrhash) {
							reply := btcjson.Reply{
								Result: txReply.Sha,
								Error:  nil,
								Id:     &message.Id,
							}
							replychan <- &reply
						}
					}
				}
			}

			if maxblock-minblock > int64(len(blkshalist)) {
				minblock += int64(len(blkshalist))
			} else {
				break
			}
		}

		rawReply = btcjson.Reply{
			Result: nil,
			Error:  nil,
			Id:     &message.Id,
		}

	case "notifynewtxs":
		params, ok := message.Params.([]interface{})
		if !ok || len(params) != 1 {
			rawReply = btcjson.Reply{
				Result: nil,
				Error:  &btcjson.ErrInvalidParams,
				Id:     &message.Id,
			}
			return ErrBadParamsField
		}
		addr, ok := params[0].(string)
		if !ok {
			rawReply = btcjson.Reply{
				Result: nil,
				Error:  &btcjson.ErrInvalidParams,
				Id:     &message.Id,
			}
			return ErrBadParamsField
		}
		addrhash, _, err := btcutil.DecodeAddress(addr)
		if err != nil {
			jsonError := btcjson.Error{
				Code:    btcjson.ErrInvalidParams.Code,
				Message: "Cannot decode address",
			}
			rawReply = btcjson.Reply{
				Result: nil,
				Error:  &jsonError,
				Id:     &message.Id,
			}
			return ErrBadParamsField
		}
		var hash addressHash
		copy(hash[:], addrhash)
		s.ws.requests.AddTxRequest(walletNotification, hash, message.Id)

		rawReply = btcjson.Reply{
			Result: nil,
			Error:  nil,
			Id:     &message.Id,
		}

	case "notifyspent":
		params, ok := message.Params.([]interface{})
		if !ok || len(params) != 2 {
			rawReply = btcjson.Reply{
				Result: nil,
				Error:  &btcjson.ErrInvalidParams,
				Id:     &message.Id,
			}
			return ErrBadParamsField
		}
		hashBE, ok1 := params[0].(string)
		index, ok2 := params[1].(float64)
		if !ok1 || !ok2 {
			rawReply = btcjson.Reply{
				Result: nil,
				Error:  &btcjson.ErrInvalidParams,
				Id:     &message.Id,
			}
			return ErrBadParamsField
		}
		hash, err := btcwire.NewShaHashFromStr(hashBE)
		if err != nil {
			jsonError := btcjson.Error{
				Code:    btcjson.ErrInvalidParams.Code,
				Message: "Hash string cannot be parsed.",
			}
			rawReply = btcjson.Reply{
				Result: nil,
				Error:  &jsonError,
				Id:     &message.Id,
			}
			return ErrBadParamsField
		}
		op := btcwire.NewOutPoint(hash, uint32(index))
		s.ws.requests.AddSpentRequest(walletNotification, op, message.Id)

		rawReply = btcjson.Reply{
			Result: nil,
			Error:  nil,
			Id:     &message.Id,
		}

	default:
		rawReply = btcjson.Reply{
			Result: nil,
			Error:  &btcjson.ErrMethodNotFound,
			Id:     &message.Id,
		}
	}
	return btcjson.ErrMethodNotFound
}

// getDifficultyRatio returns the proof-of-work difficulty as a multiple of the
// minimum difficulty using the passed bits field from the header of a block.
func getDifficultyRatio(bits uint32) float64 {
	// The minimum difficulty is the max possible proof-of-work limit bits
	// converted back to a number.  Note this is not the same as the the
	// proof of work limit directly because the block difficulty is encoded
	// in a block with the compact form which loses precision.
	max := btcchain.CompactToBig(activeNetParams.powLimitBits)
	target := btcchain.CompactToBig(bits)

	difficulty := new(big.Rat).SetFrac(max, target)
	outString := difficulty.FloatString(2)
	diff, err := strconv.ParseFloat(outString, 64)
	if err != nil {
		log.Errorf("RPCS: Cannot get difficulty: %v", err)
		return 0
	}
	return diff
}

// AddWalletListener adds a channel to listen for new messages from a
// wallet.
func (s *rpcServer) AddWalletListener(c chan []byte) {
	s.ws.walletListeners.Lock()
	s.ws.walletListeners.m[c] = true
	s.ws.walletListeners.Unlock()
}

// RemoveWalletListener removes a wallet listener channel.
func (s *rpcServer) RemoveWalletListener(c chan []byte) {
	s.ws.walletListeners.Lock()
	delete(s.ws.walletListeners.m, c)
	s.ws.walletListeners.Unlock()
}

// walletListenerDuplicator listens for new wallet listener channels
// and duplicates messages sent to walletNotificationMaster to all
// connected listeners.
func (s *rpcServer) walletListenerDuplicator() {
	// Duplicate all messages sent across walletNotificationMaster to each
	// listening wallet.
	for {
		select {
		case ntfn := <-s.ws.walletNotificationMaster:
			s.ws.walletListeners.RLock()
			for c := range s.ws.walletListeners.m {
				c <- ntfn
			}
			s.ws.walletListeners.RUnlock()

		case <-s.quit:
			return
		}
	}
}

// walletReqsNotifications is the handler function for websocket
// connections from a btcwallet instance.  It reads messages from wallet and
// sends back replies, as well as notififying wallets of chain updates.
func (s *rpcServer) walletReqsNotifications(ws *websocket.Conn) {
	// Add wallet notification channel so this handler receives btcd chain
	// notifications.
	c := make(chan []byte)
	s.AddWalletListener(c)
	defer s.RemoveWalletListener(c)

	// msgs is a channel for all messages received over the websocket.
	msgs := make(chan []byte)

	// Receive messages from websocket and send across reqs until the
	// connection is lost.
	go func() {
		for {
			select {
			case <-s.quit:
				close(msgs)
				return
			default:
				var m []byte
				if err := websocket.Message.Receive(ws, &m); err != nil {
					close(msgs)
					return
				}
				msgs <- m
			}
		}
	}()

	for {
		select {
		case m, ok := <-msgs:
			if !ok {
				// Wallet disconnected.
				return
			}
			// Handle request here.
			go s.websocketJSONHandler(c, m)
		case ntfn, _ := <-c:
			// Send btcd notification to btcwallet instance over
			// websocket.
			if err := websocket.Message.Send(ws, ntfn); err != nil {
				// Wallet disconnected.
				return
			}
		case <-s.quit:
			// Server closed.
			return
		}
	}
}

// websocketJSONHandler parses and handles a marshalled json message,
// sending the marshalled reply to a wallet notification channel.
func (s *rpcServer) websocketJSONHandler(walletNotification chan []byte, msg []byte) {
	s.wg.Add(1)
	reply, err := jsonRead(msg, s, walletNotification)
	s.wg.Done()

	if err != btcjson.ErrMethodNotFound {
		replyBytes, err := json.Marshal(reply)
		if err != nil {
			log.Errorf("RPCS: Error marshalling reply: %v", err)
		}
		walletNotification <- replyBytes
		return
	}

	// Try websocket extensions
	replychan := make(chan *btcjson.Reply)
	go func() {
		for {
			select {
			case reply, ok := <-replychan:
				if !ok {
					// no more replies expected.
					return
				}
				if reply == nil {
					continue
				}
				log.Tracef("[RPCS] reply: %v", *reply)
				replyBytes, err := json.Marshal(reply)
				if err != nil {
					log.Errorf("RPCS: Error Marshalling reply: %v", err)
					return
				}
				walletNotification <- replyBytes

			case <-s.quit:
				return
			}
		}
	}()
	s.wg.Add(1)
	err = jsonWSRead(walletNotification, replychan, msg, s)
	s.wg.Done()
}

// NotifyBlockConnected creates and marshalls a JSON message to notify
// of a new block connected to the main chain.  The notification is sent
// to each connected wallet.
func (s *rpcServer) NotifyBlockConnected(block *btcutil.Block) {
	s.ws.walletListeners.RLock()
	for wltNtfn := range s.ws.walletListeners.m {
		// Create notification with basic information filled in.
		// This data is the same for every connected wallet.
		hash, err := block.Sha()
		if err != nil {
			log.Error("Bad block; connected block notification dropped.")
			return
		}
		ntfnResult := struct {
			Hash     string   `json:"hash"`
			Height   int64    `json:"height"`
			MinedTXs []string `json:"minedtxs"`
		}{
			Hash:   hash.String(),
			Height: block.Height(),
		}

		// Fill in additional wallet-specific notifications.  If there
		// is no request context for this wallet, no need to give this
		// wallet any extra notifications.
		if cxt := s.ws.requests.m[wltNtfn]; cxt != nil {
			// Create list of all txs created by this wallet that appear in this
			// block.
			minedTxShas := make([]string, 0, len(cxt.minedTxRequests))

			// TxShas does not return a non-nil error.
			txShaList, _ := block.TxShas()
			txList := s.server.db.FetchTxByShaList(txShaList)
			for _, txReply := range txList {
				if txReply.Err != nil {
					continue
				}
				if _, ok := cxt.minedTxRequests[*txReply.Sha]; ok {
					minedTxShas = append(minedTxShas, txReply.Sha.String())
					s.ws.requests.RemoveMinedTxRequest(wltNtfn, txReply.Sha)
				}
			}

			ntfnResult.MinedTXs = minedTxShas
		}

		var id interface{} = "btcd:blockconnected"
		ntfn := btcjson.Reply{
			Result: ntfnResult,
			Id:     &id,
		}
		m, _ := json.Marshal(ntfn)
		wltNtfn <- m
	}
	s.ws.walletListeners.RUnlock()
}

// NotifyBlockDisconnected creates and marshals a JSON message to notify
// of a new block disconnected from the main chain.  The notification is sent
// to each connected wallet.
func (s *rpcServer) NotifyBlockDisconnected(block *btcutil.Block) {
	var id interface{} = "btcd:blockdisconnected"
	hash, err := block.Sha()
	if err != nil {
		log.Error("Bad block; connected block notification dropped.")
		return
	}
	ntfn := btcjson.Reply{
		Result: struct {
			Hash   string `json:"hash"`
			Height int64  `json:"height"`
		}{
			Hash:   hash.String(),
			Height: block.Height(),
		},
		Id: &id,
	}
	m, _ := json.Marshal(ntfn)
	s.ws.walletNotificationMaster <- m
}

// NotifyBlockTXs creates and marshals a JSON message to notify wallets
// of new transactions (with both spent and unspent outputs) for a watched
// address.
func (s *rpcServer) NotifyBlockTXs(db btcdb.Db, block *btcutil.Block) {
	// Build a map of in-flight transactions to see if any of the inputs in
	// this block are referencing other transactions earlier in this block.
	txInFlight := map[btcwire.ShaHash]int{}
	transactions := block.Transactions()
	spent := make([][]bool, len(transactions))
	for i, tx := range transactions {
		spent[i] = make([]bool, len(tx.MsgTx().TxOut))
		txInFlight[*tx.Sha()] = i
	}

	// The newBlockNotifyCheckTxOut current needs spent data.  This can
	// this can ultimately be optimized out by making sure the notifications
	// are in order.  For now, just create the spent data.
	for i, tx := range transactions[1:] {
		for _, txIn := range tx.MsgTx().TxIn {
			originHash := &txIn.PreviousOutpoint.Hash
			if inFlightIndex, ok := txInFlight[*originHash]; ok &&
				i >= inFlightIndex {

				prevIndex := txIn.PreviousOutpoint.Index
				spent[inFlightIndex][prevIndex] = true
			}
		}
	}

	for i, tx := range transactions {
		go s.newBlockNotifyCheckTxIn(tx)
		go s.newBlockNotifyCheckTxOut(block, tx, spent[i])
	}
}

// newBlockNotifyCheckTxIn is a helper function to iterate through
// each transaction input of a new block and perform any checks and
// notify listening frontends when necessary.
func (s *rpcServer) newBlockNotifyCheckTxIn(tx *btcutil.Tx) {
	for wltNtfn, cxt := range s.ws.requests.m {
		for _, txin := range tx.MsgTx().TxIn {
			for op, id := range cxt.spentRequests {
				if txin.PreviousOutpoint != op {
					continue
				}

				reply := &btcjson.Reply{
					Result: struct {
						TxHash string `json:"txhash"`
						Index  uint32 `json:"index"`
					}{
						TxHash: op.Hash.String(),
						Index:  uint32(op.Index),
					},
					Error: nil,
					Id:    &id,
				}
				replyBytes, err := json.Marshal(reply)
				if err != nil {
					log.Errorf("RPCS: Unable to marshal spent notification: %v", err)
					continue
				}
				wltNtfn <- replyBytes
				s.ws.requests.RemoveSpentRequest(wltNtfn, &op)
			}
		}
	}
}

// newBlockNotifyCheckTxOut is a helper function to iterate through
// each transaction output of a new block and perform any checks and
// notify listening frontends when necessary.
func (s *rpcServer) newBlockNotifyCheckTxOut(block *btcutil.Block, tx *btcutil.Tx, spent []bool) {
	for wltNtfn, cxt := range s.ws.requests.m {
		for i, txout := range tx.MsgTx().TxOut {
			_, txaddrhash, err := btcscript.ScriptToAddrHash(txout.PkScript)
			if err != nil {
				log.Debug("Error getting payment address from tx; dropping any Tx notifications.")
				break
			}
			for addr, id := range cxt.txRequests {
				if !bytes.Equal(addr[:], txaddrhash) {
					continue
				}
				blkhash, err := block.Sha()
				if err != nil {
					log.Error("Error getting block sha; dropping Tx notification.")
					break
				}
				txaddr, err := btcutil.EncodeAddress(txaddrhash, s.server.btcnet)
				if err != nil {
					log.Error("Error encoding address; dropping Tx notification.")
					break
				}
				reply := &btcjson.Reply{
					Result: struct {
						Sender    string `json:"sender"`
						Receiver  string `json:"receiver"`
						BlockHash string `json:"blockhash"`
						Height    int64  `json:"height"`
						TxHash    string `json:"txhash"`
						Index     uint32 `json:"index"`
						Amount    int64  `json:"amount"`
						PkScript  string `json:"pkscript"`
						Spent     bool   `json:"spent"`
					}{
						Sender:    "Unknown", // TODO(jrick)
						Receiver:  txaddr,
						BlockHash: blkhash.String(),
						Height:    block.Height(),
						TxHash:    tx.Sha().String(),
						Index:     uint32(i),
						Amount:    txout.Value,
						PkScript:  btcutil.Base58Encode(txout.PkScript),
						Spent:     spent[i],
					},
					Error: nil,
					Id:    &id,
				}
				replyBytes, err := json.Marshal(reply)
				if err != nil {
					log.Errorf("RPCS: Unable to marshal tx notification: %v", err)
					continue
				}
				wltNtfn <- replyBytes
			}
		}
	}
}