Use TLS+auth for frontend connections.

This change is mostly a copy paste job from the TLS listeners and
autogenerated cert code from btcd.

README.md

@@ -110,9 +110,6 @@ messages they originated from.
 
 ## TODO
 
-- Require authentication before wallet functionality can be accessed
-- Serve frontend websocket connections over TLS
-- Rescan the blockchain for missed transactions
 - Documentation (specifically the websocket API additions)
 - Code cleanup
 - Optimize

config.go

@@ -36,10 +36,12 @@ const (
 )
 
 var (
-	btcwalletHomeDir  = btcutil.AppDataDir("btcwallet", false)
-	defaultCAFile     = filepath.Join(btcwalletHomeDir, defaultCAFilename)
-	defaultConfigFile = filepath.Join(btcwalletHomeDir, defaultConfigFilename)
-	defaultDataDir    = btcwalletHomeDir
+	btcwalletHomeDir   = btcutil.AppDataDir("btcwallet", false)
+	defaultCAFile      = filepath.Join(btcwalletHomeDir, defaultCAFilename)
+	defaultConfigFile  = filepath.Join(btcwalletHomeDir, defaultConfigFilename)
+	defaultDataDir     = btcwalletHomeDir
+	defaultRPCKeyFile  = filepath.Join(btcwalletHomeDir, "rpc.key")
+	defaultRPCCertFile = filepath.Join(btcwalletHomeDir, "rpc.cert")
 )
 
 type config struct {
@@ -52,6 +54,8 @@ type config struct {
 	DataDir     string `short:"D" long:"datadir" description:"Directory to store wallets and transactions"`
 	Username    string `short:"u" long:"username" description:"Username for btcd authorization"`
 	Password    string `short:"P" long:"password" description:"Password for btcd authorization"`
+	RPCCert     string `long:"rpccert" description:"File containing the certificate file"`
+	RPCKey      string `long:"rpckey" description:"File containing the certificate key"`
 	MainNet     bool   `long:"mainnet" description:"*DISABLED* Use the main Bitcoin network (default testnet3)"`
 	Proxy       string `long:"proxy" description:"Connect via SOCKS5 proxy (eg. 127.0.0.1:9050)"`
 	ProxyUser   string `long:"proxyuser" description:"Username for proxy server"`
@@ -128,6 +132,8 @@ func loadConfig() (*config, []string, error) {
 		Connect:    netParams(defaultBtcNet).connect,
 		SvrPort:    netParams(defaultBtcNet).svrPort,
 		DataDir:    defaultDataDir,
+		RPCKey:     defaultRPCKeyFile,
+		RPCCert:    defaultRPCCertFile,
 	}
 
 	// A config file in the current directory takes precedence.

sockets.go

@@ -18,10 +18,16 @@ package main
 
 import (
 	"code.google.com/p/go.net/websocket"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	_ "crypto/sha512" // for cert generation
 	"crypto/tls"
 	"crypto/x509"
+	"crypto/x509/pkix"
 	"encoding/base64"
 	"encoding/json"
+	"encoding/pem"
 	"errors"
 	"fmt"
 	"github.com/conformal/btcjson"
@@ -29,9 +35,12 @@ import (
 	"github.com/conformal/btcwire"
 	"github.com/conformal/btcws"
 	"github.com/conformal/go-socks"
+	"math/big"
 	"net"
 	"net/http"
+	"os"
 	"sync"
+	"time"
 )
 
 var (
@@ -91,6 +100,8 @@ var (
 // config, shutdown, etc.)
 type server struct {
 	port      string
+	username  string
+	password  string
 	wg        sync.WaitGroup
 	listeners []net.Listener
 }
@@ -98,13 +109,32 @@ type server struct {
 // newServer returns a new instance of the server struct.
 func newServer() (*server, error) {
 	s := server{
-		port: cfg.SvrPort,
+		port:     cfg.SvrPort,
+		username: cfg.Username,
+		password: cfg.Password,
+	}
+
+	// Check for existence of cert file and key file
+	if !fileExists(cfg.RPCKey) && !fileExists(cfg.RPCCert) {
+		// if both files do not exist, we generate them.
+		err := genKey(cfg.RPCKey, cfg.RPCCert)
+		if err != nil {
+			return nil, err
+		}
+	}
+	keypair, err := tls.LoadX509KeyPair(cfg.RPCCert, cfg.RPCKey)
+	if err != nil {
+		return nil, err
+	}
+
+	tlsConfig := tls.Config{
+		Certificates: []tls.Certificate{keypair},
 	}
 
 	// IPv4 listener.
 	var listeners []net.Listener
 	listenAddr4 := net.JoinHostPort("127.0.0.1", s.port)
-	listener4, err := net.Listen("tcp4", listenAddr4)
+	listener4, err := tls.Listen("tcp4", listenAddr4, &tlsConfig)
 	if err != nil {
 		log.Errorf("RPCS: Couldn't create listener: %v", err)
 		return nil, err
@@ -113,7 +143,7 @@ func newServer() (*server, error) {
 
 	// IPv6 listener.
 	listenAddr6 := net.JoinHostPort("::1", s.port)
-	listener6, err := net.Listen("tcp6", listenAddr6)
+	listener6, err := tls.Listen("tcp6", listenAddr6, &tlsConfig)
 	if err != nil {
 		log.Errorf("RPCS: Couldn't create listener: %v", err)
 		return nil, err
@@ -125,6 +155,97 @@ func newServer() (*server, error) {
 	return &s, nil
 }
 
+// genkey generates a key/cert pair to the paths provided.
+// TODO(oga) wrap errors with fmt.Errorf for more context?
+func genKey(key, cert string) error {
+	log.Infof("Generating TLS certificates...")
+	priv, err := ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
+	if err != nil {
+		return err
+	}
+
+	notBefore := time.Now()
+	notAfter := notBefore.Add(10 * 365 * 24 * time.Hour)
+
+	// end of ASN.1 time
+	endOfTime := time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
+	if notAfter.After(endOfTime) {
+		notAfter = endOfTime
+	}
+
+	template := x509.Certificate{
+		SerialNumber: new(big.Int).SetInt64(0),
+		Subject: pkix.Name{
+			Organization: []string{"btcwallet autogenerated cert"},
+		},
+		NotBefore: notBefore,
+		NotAfter:  notAfter,
+
+		KeyUsage:    x509.KeyUsageKeyEncipherment | x509.KeyUsageCertSign,
+		ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		IsCA:        true, // so can sign self.
+		BasicConstraintsValid: true,
+	}
+
+	host, err := os.Hostname()
+	if err != nil {
+		return err
+	}
+	template.DNSNames = append(template.DNSNames, host, "localhost")
+
+	needLocalhost := true
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return err
+	}
+	for _, a := range addrs {
+		ip, _, err := net.ParseCIDR(a.String())
+		if err == nil {
+			if ip.String() == "127.0.0.1" {
+				needLocalhost = false
+			}
+			template.IPAddresses = append(template.IPAddresses, ip)
+		}
+	}
+	if needLocalhost {
+		localHost := net.ParseIP("127.0.0.1")
+		template.IPAddresses = append(template.IPAddresses, localHost)
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template,
+		&template, &priv.PublicKey, priv)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to create certificate: %v\n", err)
+		os.Exit(-1)
+	}
+
+	certOut, err := os.Create(cert)
+	if err != nil {
+		return err
+	}
+	pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
+	certOut.Close()
+
+	keyOut, err := os.OpenFile(key, os.O_WRONLY|os.O_CREATE|os.O_TRUNC,
+		0600)
+	if err != nil {
+		os.Remove(cert)
+		return err
+	}
+	keybytes, err := x509.MarshalECPrivateKey(priv)
+	if err != nil {
+		os.Remove(key)
+		os.Remove(cert)
+		return err
+	}
+	pem.Encode(keyOut, &pem.Block{Type: "EC PRIVATE KEY", Bytes: keybytes})
+	keyOut.Close()
+
+	log.Info("Done generating TLS certificates")
+
+	return nil
+}
+
 // handleRPCRequest processes a JSON-RPC request from a frontend.
 func (s *server) handleRPCRequest(w http.ResponseWriter, r *http.Request) {
 	frontend := make(chan []byte)
@@ -535,6 +656,8 @@ func (s *server) Start() {
 	// Use a sync.Once to insure no extra duplicators run.
 	go duplicateOnce.Do(frontendListenerDuplicator)
 
+	log.Trace("Starting RPC server")
+
 	// TODO(jrick): We need some sort of authentication before websocket
 	// connections are allowed, and perhaps TLS on the server as well.
 	serveMux := http.NewServeMux()
@@ -542,7 +665,21 @@ func (s *server) Start() {
 	serveMux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		s.handleRPCRequest(w, r)
 	})
-	serveMux.Handle("/frontend", websocket.Handler(frontendSendRecv))
+	wsServer := websocket.Server{
+		Handler: websocket.Handler(func(ws *websocket.Conn) {
+			frontendSendRecv(ws)
+		}),
+		Handshake: func(_ *websocket.Config, r *http.Request) error {
+			login := s.username + ":" + s.password
+			auth := "Basic " + base64.StdEncoding.EncodeToString([]byte(login))
+			authhdr := r.Header["Authorization"]
+			if len(authhdr) <= 0 || authhdr[0] != auth {
+				return errors.New("auth failure")
+			}
+			return nil
+		},
+	}
+	serveMux.Handle("/frontend", wsServer)
 	for _, listener := range s.listeners {
 		s.wg.Add(1)
 		go func(listener net.Listener) {