// newServer creates a new instance of the server which is to listen using the
// passed listener address.
func newServer(listenAddrs []string, notifier chainntnfs.ChainNotifier,
	bio lnwallet.BlockChainIO, wallet *lnwallet.LightningWallet,
	chanDB *channeldb.DB) (*server, error) {

	privKey, err := wallet.GetIdentitykey()
	if err != nil {
		return nil, err
	}

	listeners := make([]net.Listener, len(listenAddrs))
	for i, addr := range listenAddrs {
		listeners[i], err = brontide.NewListener(privKey, addr)
		if err != nil {
			return nil, err
		}
	}

	serializedPubKey := privKey.PubKey().SerializeCompressed()
	s := &server{
		bio:           bio,
		chainNotifier: notifier,
		chanDB:        chanDB,
		fundingMgr:    newFundingManager(wallet),
		invoices:      newInvoiceRegistry(chanDB),
		lnwallet:      wallet,
		identityPriv:  privKey,
		// TODO(roasbeef): derive proper onion key based on rotation
		// schedule
		sphinx:      sphinx.NewRouter(privKey, activeNetParams.Params),
		lightningID: fastsha256.Sum256(serializedPubKey),
		listeners:   listeners,
		peers:       make(map[int32]*peer),
		newPeers:    make(chan *peer, 100),
		donePeers:   make(chan *peer, 100),
		queries:     make(chan interface{}),
		quit:        make(chan struct{}),
	}

	// If the debug HTLC flag is on, then we invoice a "master debug"
	// invoice which all outgoing payments will be sent and all incoming
	// HTLC's with the debug R-Hash immediately settled.
	if cfg.DebugHTLC {
		kiloCoin := btcutil.Amount(btcutil.SatoshiPerBitcoin * 1000)
		s.invoices.AddDebugInvoice(kiloCoin, *debugPre)
		srvrLog.Debugf("Debug HTLC invoice inserted, preimage=%x, hash=%x",
			debugPre[:], debugHash[:])
	}

	s.utxoNursery = newUtxoNursery(notifier, wallet)

	// Create a new routing manager with ourself as the sole node within
	// the graph.
	selfVertex := hex.EncodeToString(serializedPubKey)
	s.routingMgr = routing.NewRoutingManager(graph.NewID(selfVertex), nil)
	s.htlcSwitch = newHtlcSwitch(serializedPubKey, s.routingMgr)

	s.rpcServer = newRpcServer(s)

	return s, nil
}

// newPeer creates a new peer from an establish connection object, and a
// pointer to the main server.
func newPeer(conn net.Conn, server *server, addr *lnwire.NetAddress,
	inbound bool) (*peer, error) {

	nodePub := addr.IdentityKey

	p := &peer{
		conn:        conn,
		lightningID: wire.ShaHash(fastsha256.Sum256(nodePub.SerializeCompressed())),
		addr:        addr,

		id:      atomic.AddInt32(&numNodes, 1),
		inbound: inbound,

		server: server,

		lastNMessages: make(map[lnwire.Message]struct{}),

		sendQueueSync: make(chan struct{}, 1),
		sendQueue:     make(chan outgoinMsg, 1),
		outgoingQueue: make(chan outgoinMsg, outgoingQueueLen),

		barrierInits:     make(chan wire.OutPoint),
		newChanBarriers:  make(map[wire.OutPoint]chan struct{}),
		activeChannels:   make(map[wire.OutPoint]*lnwallet.LightningChannel),
		htlcManagers:     make(map[wire.OutPoint]chan lnwire.Message),
		chanSnapshotReqs: make(chan *chanSnapshotReq),
		newChannels:      make(chan *lnwallet.LightningChannel, 1),

		localCloseChanReqs:  make(chan *closeLinkReq),
		remoteCloseChanReqs: make(chan *lnwire.CloseRequest),

		queueQuit: make(chan struct{}),
		quit:      make(chan struct{}),
	}

	// Initiate the pending channel identifier properly depending on if this
	// node is inbound or outbound. This value will be used in an increasing
	// manner to track pending channels.
	if inbound {
		p.nextPendingChannelID = 1 << 63
	} else {
		p.nextPendingChannelID = 0
	}

	// Fetch and then load all the active channels we have with this
	// remote peer from the database.
	activeChans, err := server.chanDB.FetchOpenChannels(p.addr.IdentityKey)
	if err != nil {
		peerLog.Errorf("unable to fetch active chans "+
			"for peer %v: %v", p, err)
		return nil, err
	}
	peerLog.Debugf("Loaded %v active channels from database with peerID(%v)",
		len(activeChans), p.id)
	if err := p.loadActiveChannels(activeChans); err != nil {
		return nil, err
	}

	return p, nil
}

func putInvoice(invoices *bolt.Bucket, invoiceIndex *bolt.Bucket,
	i *Invoice, invoiceNum uint32) error {

	// Create the invoice key which is just the big-endian representation
	// of the invoice number.
	var invoiceKey [4]byte
	byteOrder.PutUint32(invoiceKey[:], invoiceNum)

	// Increment the num invoice counter index so the next invoice bares
	// the proper ID.
	var scratch [4]byte
	invoiceCounter := invoiceNum + 1
	byteOrder.PutUint32(scratch[:], invoiceCounter)
	if err := invoiceIndex.Put(numInvoicesKey, scratch[:]); err != nil {
		return err
	}

	// Add the payment hash to the invoice index. This'll let us quickly
	// identify if we can settle an incoming payment, and also to possibly
	// allow a single invoice to have multiple payment installations.
	paymentHash := fastsha256.Sum256(i.Terms.PaymentPreimage[:])
	if err := invoiceIndex.Put(paymentHash[:], invoiceKey[:]); err != nil {
		return err
	}

	// Finally, serialize the invoice itself to be written to the disk.
	var buf bytes.Buffer
	if err := serializeInvoice(&buf, i); err != nil {
		return nil
	}

	return invoices.Put(invoiceKey[:], buf.Bytes())
}

// witnessScriptHash generates a pay-to-witness-script-hash public key script
// paying to a version 0 witness program paying to the passed redeem script.
func witnessScriptHash(witnessScript []byte) ([]byte, error) {
	bldr := txscript.NewScriptBuilder()

	bldr.AddOp(txscript.OP_0)
	scriptHash := fastsha256.Sum256(witnessScript)
	bldr.AddData(scriptHash[:])
	return bldr.Script()
}

// authPKH...
func (c *LNDConn) authPKH(
	myId *btcec.PrivateKey, theirPKH, localEphPubBytes []byte) error {
	if c.Authed {
		return fmt.Errorf("%s already authed", c.RemotePub)
	}
	if len(theirPKH) != 20 {
		return fmt.Errorf("remote PKH must be 20 bytes, got %d",
			len(theirPKH))
	}

	// Send 53 bytes: our pubkey, and the remote's pubkey hash.
	var greetingMsg [53]byte
	copy(greetingMsg[:33], myId.PubKey().SerializeCompressed())
	copy(greetingMsg[:33], theirPKH)
	if _, err := c.Conn.Write(greetingMsg[:]); err != nil {
		return err
	}

	// Wait for their response.
	// TODO(tadge): add timeout here
	//  * NOTE(roasbeef): read timeout should be set on the underlying
	//    net.Conn.
	resp := make([]byte, 53)
	if _, err := c.Conn.Read(resp); err != nil {
		return err
	}

	// Parse their long-term public key, and generate the DH proof.
	theirPub, err := btcec.ParsePubKey(resp[:33], btcec.S256())
	if err != nil {
		return err
	}
	idDH := fastsha256.Sum256(btcec.GenerateSharedSecret(myId, theirPub))
	fmt.Printf("made idDH %x\n", idDH)
	theirDHproof := btcutil.Hash160(append(localEphPubBytes, idDH[:]...))

	// Verify that their DH proof matches the one we just generated.
	if bytes.Equal(resp[33:], theirDHproof) == false {
		return fmt.Errorf("Invalid DH proof %x", theirDHproof)
	}

	// If their DH proof checks out, then send our own.
	myDHproof := btcutil.Hash160(append(c.RemotePub.SerializeCompressed(), idDH[:]...))
	if _, err = c.Conn.Write(myDHproof); err != nil {
		return err
	}

	// Proof sent, auth complete.
	c.RemotePub = theirPub
	theirAdr := btcutil.Hash160(theirPub.SerializeCompressed())
	copy(c.RemoteLNId[:], theirAdr[:16])
	c.Authed = true

	return nil
}

// UnregisterLink requets the htlcSwitch to unregiser the new active link. An
// unregistered link will no longer be considered a candidate to forward
// HTLC's.
func (h *htlcSwitch) UnregisterLink(remotePub *btcec.PublicKey, chanPoint *wire.OutPoint) {
	done := make(chan struct{}, 1)
	rawPub := remotePub.SerializeCompressed()

	h.linkControl <- &unregisterLinkMsg{
		chanInterface: fastsha256.Sum256(rawPub),
		chanPoint:     chanPoint,
		remoteID:      rawPub,
		done:          done,
	}

	<-done
}

// checkAuthHeader checks the HTTP Basic authentication supplied by a client
// in the HTTP request r.  It errors with ErrNoAuth if the request does not
// contain the Authorization header, or another non-nil error if the
// authentication was provided but incorrect.
//
// This check is time-constant.
func (s *Server) checkAuthHeader(r *http.Request) error {
	authhdr := r.Header["Authorization"]
	if len(authhdr) == 0 {
		return ErrNoAuth
	}

	authsha := fastsha256.Sum256([]byte(authhdr[0]))
	cmp := subtle.ConstantTimeCompare(authsha[:], s.authsha[:])
	if cmp != 1 {
		return errors.New("bad auth")
	}
	return nil
}

// DeriveKey derives the underlying secret key and ensures it matches the
// expected digest.  This should only be called after previously calling the
// Zero function or on an initial Unmarshal.
func (sk *SecretKey) DeriveKey(password *[]byte) error {
	if err := sk.deriveKey(password); err != nil {
		return err
	}

	// verify password
	digest := fastsha256.Sum256(sk.Key[:])
	if subtle.ConstantTimeCompare(digest[:], sk.Parameters.Digest[:]) != 1 {
		return ErrInvalidPassword
	}

	return nil
}

// invalidAuth checks whether a websocket request is a valid (parsable)
// authenticate request and checks the supplied username and passphrase
// against the server auth.
func (s *Server) invalidAuth(req *btcjson.Request) bool {
	cmd, err := btcjson.UnmarshalCmd(req)
	if err != nil {
		return false
	}
	authCmd, ok := cmd.(*btcjson.AuthenticateCmd)
	if !ok {
		return false
	}
	// Check credentials.
	login := authCmd.Username + ":" + authCmd.Passphrase
	auth := "Basic " + base64.StdEncoding.EncodeToString([]byte(login))
	authSha := fastsha256.Sum256([]byte(auth))
	return subtle.ConstantTimeCompare(authSha[:], s.authsha[:]) != 1
}

// authPubKey...
func (c *LNDConn) authPubKey(
	myId *btcec.PrivateKey, remotePubBytes, localEphPubBytes []byte) error {
	if c.Authed {
		return fmt.Errorf("%s already authed", c.RemotePub)
	}

	// Since we already know their public key, we can immediately generate
	// the DH proof without an additional round-trip.
	theirPub, err := btcec.ParsePubKey(remotePubBytes, btcec.S256())
	if err != nil {
		return err
	}
	theirPKH := btcutil.Hash160(remotePubBytes)
	idDH := fastsha256.Sum256(btcec.GenerateSharedSecret(myId, theirPub))
	myDHproof := btcutil.Hash160(append(c.RemotePub.SerializeCompressed(), idDH[:]...))

	// Send over the 73 byte authentication message: my pubkey, their
	// pubkey hash, DH proof.
	var authMsg [73]byte
	copy(authMsg[:33], myId.PubKey().SerializeCompressed())
	copy(authMsg[33:], theirPKH)
	copy(authMsg[53:], myDHproof)
	if _, err = c.Conn.Write(authMsg[:]); err != nil {
		return nil
	}

	// Await, their response. They should send only the 20-byte DH proof.
	resp := make([]byte, 20)
	_, err = c.Conn.Read(resp)
	if err != nil {
		return err
	}

	// Verify that their proof matches our locally computed version.
	theirDHproof := btcutil.Hash160(append(localEphPubBytes, idDH[:]...))
	if bytes.Equal(resp, theirDHproof) == false {
		return fmt.Errorf("invalid DH proof %x", theirDHproof)
	}

	// Proof checks out, auth complete.
	c.RemotePub = theirPub
	theirAdr := btcutil.Hash160(theirPub.SerializeCompressed())
	copy(c.RemoteLNId[:], theirAdr[:16])
	c.Authed = true

	return nil
}

// createCipherConn....
func (l *Listener) createCipherConn(lnConn *LNDConn) (*btcec.PrivateKey, error) {
	var err error
	var theirEphPubBytes []byte

	// First, read and deserialize their ephemeral public key.
	theirEphPubBytes, err = readClear(lnConn.Conn)
	if err != nil {
		return nil, err
	}
	if len(theirEphPubBytes) != 33 {
		return nil, fmt.Errorf("Got invalid %d byte eph pubkey %x\n",
			len(theirEphPubBytes), theirEphPubBytes)
	}
	theirEphPub, err := btcec.ParsePubKey(theirEphPubBytes, btcec.S256())
	if err != nil {
		return nil, err
	}

	// Once we've parsed and verified their key, generate, and send own
	// ephemeral key pair for use within this session.
	myEph, err := btcec.NewPrivateKey(btcec.S256())
	if err != nil {
		return nil, err
	}
	if _, err := writeClear(lnConn.Conn, myEph.PubKey().SerializeCompressed()); err != nil {
		return nil, err
	}

	// Now that we have both keys, do non-interactive diffie with ephemeral
	// pubkeys, sha256 for good luck.
	sessionKey := fastsha256.Sum256(
		btcec.GenerateSharedSecret(myEph, theirEphPub),
	)

	lnConn.chachaStream, err = chacha20poly1305.New(sessionKey[:])

	// display private key for debug only
	fmt.Printf("made session key %x\n", sessionKey)

	lnConn.remoteNonceInt = 1 << 63
	lnConn.myNonceInt = 0

	lnConn.RemotePub = theirEphPub
	lnConn.Authed = false

	return myEph, nil
}

// AddInvoice inserts the targeted invoice into the database. If the invoice
// has *any* payment hashes which already exists within the database, then the
// insertion will be aborted and rejected due to the strict policy banning any
// duplicate payment hashes.
func (d *DB) AddInvoice(i *Invoice) error {
	if len(i.Memo) > MaxMemoSize {
		return fmt.Errorf("max length a memo is %v, and invoice "+
			"of length %v was provided", MaxMemoSize, len(i.Memo))
	}
	if len(i.Receipt) > MaxReceiptSize {
		return fmt.Errorf("max length a receipt is %v, and invoice "+
			"of length %v was provided", MaxReceiptSize,
			len(i.Receipt))
	}

	return d.store.Update(func(tx *bolt.Tx) error {
		invoices, err := tx.CreateBucketIfNotExists(invoiceBucket)
		if err != nil {
			return err
		}

		invoiceIndex, err := invoices.CreateBucketIfNotExists(invoiceIndexBucket)
		if err != nil {
			return err
		}

		// Ensure that an invoice an identical payment hash doesn't
		// already exist within the index.
		paymentHash := fastsha256.Sum256(i.Terms.PaymentPreimage[:])
		if invoiceIndex.Get(paymentHash[:]) != nil {
			return ErrDuplicateInvoice
		}

		// If the current running payment ID counter hasn't yet been
		// created, then create it now.
		var invoiceNum uint32
		invoiceCounter := invoiceIndex.Get(numInvoicesKey)
		if invoiceCounter == nil {
			var scratch [4]byte
			byteOrder.PutUint32(scratch[:], invoiceNum)
			if err := invoiceIndex.Put(numInvoicesKey, scratch[:]); err != nil {
				return nil
			}
		} else {
			invoiceNum = byteOrder.Uint32(invoiceCounter)
		}

		return putInvoice(invoices, invoiceIndex, i, invoiceNum)
	})
}

// AddInvoice attempts to add a new invoice to the invoice database. Any
// duplicated invoices are rejected, therefore all invoices *must* have a
// unique payment preimage.
func (r *rpcServer) AddInvoice(ctx context.Context,
	invoice *lnrpc.Invoice) (*lnrpc.AddInvoiceResponse, error) {

	preImage := invoice.RPreimage
	preimageLength := len(preImage)
	if preimageLength != 32 {
		return nil, fmt.Errorf("payment preimage must be exactly "+
			"32 bytes, is instead %v", preimageLength)
	}

	if len(invoice.Memo) > channeldb.MaxMemoSize {
		return nil, fmt.Errorf("memo too large: %v bytes "+
			"(maxsize=%v)", len(invoice.Memo), channeldb.MaxMemoSize)
	}
	if len(invoice.Receipt) > channeldb.MaxReceiptSize {
		return nil, fmt.Errorf("receipt too large: %v bytes "+
			"(maxsize=%v)", len(invoice.Receipt), channeldb.MaxReceiptSize)
	}

	i := &channeldb.Invoice{
		CreationDate: time.Now(),
		Memo:         []byte(invoice.Memo),
		Receipt:      invoice.Receipt,
		Terms: channeldb.ContractTerm{
			Value: btcutil.Amount(invoice.Value),
		},
	}
	copy(i.Terms.PaymentPreimage[:], preImage)

	rpcsLog.Tracef("[addinvoice] adding new invoice %v",
		newLogClosure(func() string {
			return spew.Sdump(i)
		}))

	if err := r.server.invoices.AddInvoice(i); err != nil {
		return nil, err
	}

	rHash := fastsha256.Sum256(preImage)
	return &lnrpc.AddInvoiceResponse{
		RHash: rHash[:],
	}, nil
}

// addDebugInvoice adds a debug invoice for the specified amount, identified
// by the passed preimage. Once this invoice is added, sub-systems within the
// daemon add/forward HTLC's are able to obtain the proper preimage required
// for redemption in the case that we're the final destination.
func (i *invoiceRegistry) AddDebugInvoice(amt btcutil.Amount, preimage wire.ShaHash) {
	paymentHash := wire.ShaHash(fastsha256.Sum256(preimage[:]))

	invoice := &channeldb.Invoice{
		CreationDate: time.Now(),
		Terms: channeldb.ContractTerm{
			Value:           amt,
			PaymentPreimage: preimage,
		},
	}

	i.Lock()
	i.debugInvoices[paymentHash] = invoice
	i.Unlock()

	ltndLog.Debugf("Adding debug invoice %v", newLogClosure(func() string {
		return spew.Sdump(invoice)
	}))
}

// NewSecretKey returns a SecretKey structure based on the passed parameters.
func NewSecretKey(password *[]byte, N, r, p int) (*SecretKey, error) {
	sk := SecretKey{
		Key: (*CryptoKey)(&[KeySize]byte{}),
	}
	// setup parameters
	sk.Parameters.N = N
	sk.Parameters.R = r
	sk.Parameters.P = p
	_, err := io.ReadFull(prng, sk.Parameters.Salt[:])
	if err != nil {
		return nil, err
	}

	// derive key
	err = sk.deriveKey(password)
	if err != nil {
		return nil, err
	}

	// store digest
	sk.Parameters.Digest = fastsha256.Sum256(sk.Key[:])

	return &sk, nil
}

// DoubleSha256 calculates sha256(sha256(b)) and returns the resulting bytes.
func DoubleSha256(b []byte) []byte {
	first := fastsha256.Sum256(b)
	second := fastsha256.Sum256(first[:])
	return second[:]
}

// DoubleSha256SH calculates sha256(sha256(b)) and returns the resulting bytes
// as a ShaHash.
func DoubleSha256SH(b []byte) ShaHash {
	first := fastsha256.Sum256(b)
	return ShaHash(fastsha256.Sum256(first[:]))
}

func TestRFC6979(t *testing.T) {
	// Test vectors matching Trezor and CoreBitcoin implementations.
	// - https://github.com/trezor/trezor-crypto/blob/9fea8f8ab377dc514e40c6fd1f7c89a74c1d8dc6/tests.c#L432-L453
	// - https://github.com/oleganza/CoreBitcoin/blob/e93dd71207861b5bf044415db5fa72405e7d8fbc/CoreBitcoin/BTCKey%2BTests.m#L23-L49
	tests := []struct {
		key       string
		msg       string
		nonce     string
		signature string
	}{
		{
			"cca9fbcc1b41e5a95d369eaa6ddcff73b61a4efaa279cfc6567e8daa39cbaf50",
			"sample",
			"2df40ca70e639d89528a6b670d9d48d9165fdc0febc0974056bdce192b8e16a3",
			"3045022100af340daf02cc15c8d5d08d7735dfe6b98a474ed373bdb5fbecf7571be52b384202205009fb27f37034a9b24b707b7c6b79ca23ddef9e25f7282e8a797efe53a8f124",
		},
		{
			// This signature hits the case when S is higher than halforder.
			// If S is not canonicalized (lowered by halforder), this test will fail.
			"0000000000000000000000000000000000000000000000000000000000000001",
			"Satoshi Nakamoto",
			"8f8a276c19f4149656b280621e358cce24f5f52542772691ee69063b74f15d15",
			"3045022100934b1ea10a4b3c1757e2b0c017d0b6143ce3c9a7e6a4a49860d7a6ab210ee3d802202442ce9d2b916064108014783e923ec36b49743e2ffa1c4496f01a512aafd9e5",
		},
		{
			"fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364140",
			"Satoshi Nakamoto",
			"33a19b60e25fb6f4435af53a3d42d493644827367e6453928554f43e49aa6f90",
			"3045022100fd567d121db66e382991534ada77a6bd3106f0a1098c231e47993447cd6af2d002206b39cd0eb1bc8603e159ef5c20a5c8ad685a45b06ce9bebed3f153d10d93bed5",
		},
		{
			"f8b8af8ce3c7cca5e300d33939540c10d45ce001b8f252bfbc57ba0342904181",
			"Alan Turing",
			"525a82b70e67874398067543fd84c83d30c175fdc45fdeee082fe13b1d7cfdf1",
			"304402207063ae83e7f62bbb171798131b4a0564b956930092b33b07b395615d9ec7e15c022058dfcc1e00a35e1572f366ffe34ba0fc47db1e7189759b9fb233c5b05ab388ea",
		},
		{
			"0000000000000000000000000000000000000000000000000000000000000001",
			"All those moments will be lost in time, like tears in rain. Time to die...",
			"38aa22d72376b4dbc472e06c3ba403ee0a394da63fc58d88686c611aba98d6b3",
			"30450221008600dbd41e348fe5c9465ab92d23e3db8b98b873beecd930736488696438cb6b0220547fe64427496db33bf66019dacbf0039c04199abb0122918601db38a72cfc21",
		},
		{
			"e91671c46231f833a6406ccbea0e3e392c76c167bac1cb013f6f1013980455c2",
			"There is a computer disease that anybody who works with computers knows about. It's a very serious disease and it interferes completely with the work. The trouble with computers is that you 'play' with them!",
			"1f4b84c23a86a221d233f2521be018d9318639d5b8bbd6374a8a59232d16ad3d",
			"3045022100b552edd27580141f3b2a5463048cb7cd3e047b97c9f98076c32dbdf85a68718b0220279fa72dd19bfae05577e06c7c0c1900c371fcd5893f7e1d56a37d30174671f6",
		},
	}

	for i, test := range tests {
		privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), decodeHex(test.key))
		hash := fastsha256.Sum256([]byte(test.msg))

		// Ensure deterministically generated nonce is the expected value.
		gotNonce := btcec.TstNonceRFC6979(privKey.D, hash[:]).Bytes()
		wantNonce := decodeHex(test.nonce)
		if !bytes.Equal(gotNonce, wantNonce) {
			t.Errorf("NonceRFC6979 #%d (%s): Nonce is incorrect: "+
				"%x (expected %x)", i, test.msg, gotNonce,
				wantNonce)
			continue
		}

		// Ensure deterministically generated signature is the expected value.
		gotSig, err := privKey.Sign(hash[:])
		if err != nil {
			t.Errorf("Sign #%d (%s): unexpected error: %v", i,
				test.msg, err)
			continue
		}
		gotSigBytes := gotSig.Serialize()
		wantSigBytes := decodeHex(test.signature)
		if !bytes.Equal(gotSigBytes, wantSigBytes) {
			t.Errorf("Sign #%d (%s): mismatched signature: %x "+
				"(expected %x)", i, test.msg, gotSigBytes,
				wantSigBytes)
			continue
		}
	}
}

// Dial...
func (c *Conn) Dial(address string, remoteId []byte) error {
	var err error
	if c.conn != nil {
		return fmt.Errorf("connection already established")
	}

	// Before dialing out to the remote host, verify that `remoteId` is either
	// a pubkey or a pubkey hash.
	if len(remoteId) != 33 && len(remoteId) != 20 {
		return fmt.Errorf("must supply either remote pubkey or " +
			"pubkey hash")
	}

	// First, open the TCP connection itself.
	c.conn, err = net.Dial("tcp", address)
	if err != nil {
		return err
	}

	// Calc remote LNId; need this for creating pbx connections just because
	// LNid is in the struct does not mean it's authed!
	if len(remoteId) == 20 {
		copy(c.remoteLNId[:], remoteId[:16])
	} else {
		theirAdr := btcutil.Hash160(remoteId)
		copy(c.remoteLNId[:], theirAdr[:16])
	}

	// Make up an ephemeral keypair for this session.
	ourEphemeralPriv, err := btcec.NewPrivateKey(btcec.S256())
	if err != nil {
		return err
	}
	ourEphemeralPub := ourEphemeralPriv.PubKey()

	// Sned 1. Send my ephemeral pubkey. Can add version bits.
	if _, err = writeClear(c.conn, ourEphemeralPub.SerializeCompressed()); err != nil {
		return err
	}

	// Read, then deserialize their ephemeral public key.
	theirEphPubBytes, err := readClear(c.conn)
	if err != nil {
		return err
	}
	theirEphPub, err := btcec.ParsePubKey(theirEphPubBytes, btcec.S256())
	if err != nil {
		return err
	}

	// Do non-interactive diffie with ephemeral pubkeys. Sha256 for good
	// luck.
	sessionKey := fastsha256.Sum256(
		btcec.GenerateSharedSecret(ourEphemeralPriv, theirEphPub),
	)

	// Now that we've derive the session key, we can initialize the
	// chacha20poly1305 AEAD instance which will be used for the remainder of
	// the session.
	c.chachaStream, err = chacha20poly1305.New(sessionKey[:])
	if err != nil {
		return err
	}

	// display private key for debug only
	fmt.Printf("made session key %x\n", sessionKey)

	c.myNonceInt = 1 << 63
	c.remoteNonceInt = 0

	c.remotePub = theirEphPub
	c.authed = false

	// Session is now open and confidential but not yet authenticated...
	// So auth!
	if len(remoteId) == 20 {
		// Only know pubkey hash (20 bytes).
		err = c.authPKH(remoteId, ourEphemeralPub.SerializeCompressed())
	} else {
		// Must be 33 byte pubkey.
		err = c.authPubKey(remoteId, ourEphemeralPub.SerializeCompressed())
	}
	if err != nil {
		return err
	}

	return nil
}

// SendPayment dispatches a bi-directional streaming RPC for sending payments
// through the Lightning Network. A single RPC invocation creates a persistent
// bi-directional stream allowing clients to rapidly send payments through the
// Lightning Network with a single persistent connection.
func (r *rpcServer) SendPayment(paymentStream lnrpc.Lightning_SendPaymentServer) error {
	const queryTimeout = time.Duration(time.Second * 10)
	errChan := make(chan error, 1)
	payChan := make(chan *lnrpc.SendRequest)

	// Launch a new goroutine to handle reading new payment requests from
	// the client. This way we can handle errors independently of blocking
	// and waiting for the next payment request to come through.
	go func() {
		for {
			select {
			case <-r.quit:
				errChan <- nil
				return
			default:
				// Receive the next pending payment within the
				// stream sent by the client. If we read the
				// EOF sentinel, then the client has closed the
				// stream, and we can exit normally.
				nextPayment, err := paymentStream.Recv()
				if err == io.EOF {
					errChan <- nil
					return
				} else if err != nil {
					errChan <- err
					return
				}

				payChan <- nextPayment
			}
		}
	}()

	for {
		select {
		case err := <-errChan:
			return err
		case nextPayment := <-payChan:
			// Query the routing table for a potential path to the
			// destination node. If a path is ultimately
			// unavailable, then an error will be returned.
			destNode := hex.EncodeToString(nextPayment.Dest)
			targetVertex := graph.NewID(destNode)
			path, err := r.server.routingMgr.FindPath(targetVertex,
				queryTimeout)
			if err != nil {
				return err
			}
			rpcsLog.Tracef("[sendpayment] selected route: %v", path)

			// If we're in debug HTLC mode, then all outgoing
			// HTLC's will pay to the same debug rHash. Otherwise,
			// we pay to the rHash specified within the RPC
			// request.
			var rHash [32]byte
			if cfg.DebugHTLC {
				rHash = debugHash
			} else {
				copy(rHash[:], nextPayment.PaymentHash)
			}

			// Generate the raw encoded sphinx packet to be
			// included along with the HTLC add message.  We snip
			// off the first hop from the path as within the
			// routing table's star graph, we're always the first
			// hop.
			sphinxPacket, err := generateSphinxPacket(path[1:], rHash[:])
			if err != nil {
				return err
			}

			// Craft an HTLC packet to send to the routing
			// sub-system. The meta-data within this packet will be
			// used to route the payment through the network.
			htlcAdd := &lnwire.HTLCAddRequest{
				Amount:           lnwire.CreditsAmount(nextPayment.Amt),
				RedemptionHashes: [][32]byte{rHash},
				OnionBlob:        sphinxPacket,
			}
			firstHopPub, err := hex.DecodeString(path[1].String())
			if err != nil {
				return err
			}
			destAddr := wire.ShaHash(fastsha256.Sum256(firstHopPub))
			htlcPkt := &htlcPacket{
				dest: destAddr,
				msg:  htlcAdd,
			}

			// TODO(roasbeef): semaphore to limit num outstanding
			// goroutines.
			go func() {
				// Finally, send this next packet to the
				// routing layer in order to complete the next
				// payment.
				// TODO(roasbeef): this should go through the
//.........这里部分代码省略.........