lnd: refactor getTLSConfig

lnd.go

@@ -7,6 +7,7 @@ package lnd
 import (
 	"context"
 	"crypto/tls"
+	"crypto/x509"
 	"errors"
 	"fmt"
 	"io/ioutil"
@@ -217,11 +218,13 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 	}
 
 	// Only process macaroons if --no-macaroons isn't set.
-	serverOpts, restDialOpts, restListen, cleanUp, err := getTLSConfig(cfg)
+        tlsManager := NewTLSManager(cfg)
+	serverOpts, restDialOpts, restListen, cleanUp,
+		err := tlsManager.getConfig()
+
 	if err != nil {
 		return mkErr("unable to load TLS credentials: %v", err)
 	}
-
 	defer cleanUp()
 
 	// If we have chosen to start with a dedicated listener for the
@@ -630,147 +633,38 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 	return nil
 }
 
-// getTLSConfig returns a TLS configuration for the gRPC server and credentials
+// TLSManager generates/renews a TLS certificate when needed and returns the
+// certificate configuration options needed for gRPC and REST.
+type TLSManager struct {
+	cfg *Config
+}
+
+// NewTLSManager returns a reference to a new TLSManager.
+func NewTLSManager(cfg *Config) *TLSManager {
+	return &TLSManager{
+		cfg: cfg,
+	}
+}
+
+// getConfig returns a TLS configuration for the gRPC server and credentials
 // and a proxy destination for the REST reverse proxy.
-func getTLSConfig(cfg *Config) ([]grpc.ServerOption, []grpc.DialOption,
+func (t *TLSManager) getConfig() ([]grpc.ServerOption, []grpc.DialOption,
 	func(net.Addr) (net.Listener, error), func(), error) {
 
-	// Ensure we create TLS key and certificate if they don't exist.
-	if !fileExists(cfg.TLSCertPath) && !fileExists(cfg.TLSKeyPath) {
-		rpcsLog.Infof("Generating TLS certificates...")
-		err := cert.GenCertPair(
-			"lnd autogenerated cert", cfg.TLSCertPath,
-			cfg.TLSKeyPath, cfg.TLSExtraIPs, cfg.TLSExtraDomains,
-			cfg.TLSDisableAutofill, cfg.TLSCertDuration,
-		)
-		if err != nil {
-			return nil, nil, nil, nil, err
-		}
-		rpcsLog.Infof("Done generating TLS certificates")
+	tlsCfg, cleanUp, err := t.generateOrRenewCert()
+	if err != nil {
+		return nil, nil, nil, nil, err
 	}
 
-	certData, parsedCert, err := cert.LoadCert(
-		cfg.TLSCertPath, cfg.TLSKeyPath,
+	// Now that we know that we have a ceritificate, let's generate the
+	// required config options.
+	restCreds, err := credentials.NewClientTLSFromFile(
+		t.cfg.TLSCertPath, "",
 	)
 	if err != nil {
 		return nil, nil, nil, nil, err
 	}
 
-	// We check whether the certificate we have on disk match the IPs and
-	// domains specified by the config. If the extra IPs or domains have
-	// changed from when the certificate was created, we will refresh the
-	// certificate if auto refresh is active.
-	refresh := false
-	if cfg.TLSAutoRefresh {
-		refresh, err = cert.IsOutdated(
-			parsedCert, cfg.TLSExtraIPs,
-			cfg.TLSExtraDomains, cfg.TLSDisableAutofill,
-		)
-		if err != nil {
-			return nil, nil, nil, nil, err
-		}
-	}
-
-	// If the certificate expired or it was outdated, delete it and the TLS
-	// key and generate a new pair.
-	if time.Now().After(parsedCert.NotAfter) || refresh {
-		ltndLog.Info("TLS certificate is expired or outdated, " +
-			"generating a new one")
-
-		err := os.Remove(cfg.TLSCertPath)
-		if err != nil {
-			return nil, nil, nil, nil, err
-		}
-
-		err = os.Remove(cfg.TLSKeyPath)
-		if err != nil {
-			return nil, nil, nil, nil, err
-		}
-
-		rpcsLog.Infof("Renewing TLS certificates...")
-		err = cert.GenCertPair(
-			"lnd autogenerated cert", cfg.TLSCertPath,
-			cfg.TLSKeyPath, cfg.TLSExtraIPs, cfg.TLSExtraDomains,
-			cfg.TLSDisableAutofill, cfg.TLSCertDuration,
-		)
-		if err != nil {
-			return nil, nil, nil, nil, err
-		}
-		rpcsLog.Infof("Done renewing TLS certificates")
-
-		// Reload the certificate data.
-		certData, _, err = cert.LoadCert(
-			cfg.TLSCertPath, cfg.TLSKeyPath,
-		)
-		if err != nil {
-			return nil, nil, nil, nil, err
-		}
-	}
-
-	tlsCfg := cert.TLSConfFromCert(certData)
-
-	restCreds, err := credentials.NewClientTLSFromFile(cfg.TLSCertPath, "")
-	if err != nil {
-		return nil, nil, nil, nil, err
-	}
-
-	// If Let's Encrypt is enabled, instantiate autocert to request/renew
-	// the certificates.
-	cleanUp := func() {}
-	if cfg.LetsEncryptDomain != "" {
-		ltndLog.Infof("Using Let's Encrypt certificate for domain %v",
-			cfg.LetsEncryptDomain)
-
-		manager := autocert.Manager{
-			Cache:      autocert.DirCache(cfg.LetsEncryptDir),
-			Prompt:     autocert.AcceptTOS,
-			HostPolicy: autocert.HostWhitelist(cfg.LetsEncryptDomain),
-		}
-
-		srv := &http.Server{
-			Addr:    cfg.LetsEncryptListen,
-			Handler: manager.HTTPHandler(nil),
-		}
-		shutdownCompleted := make(chan struct{})
-		cleanUp = func() {
-			err := srv.Shutdown(context.Background())
-			if err != nil {
-				ltndLog.Errorf("Autocert listener shutdown "+
-					" error: %v", err)
-
-				return
-			}
-			<-shutdownCompleted
-			ltndLog.Infof("Autocert challenge listener stopped")
-		}
-
-		go func() {
-			ltndLog.Infof("Autocert challenge listener started "+
-				"at %v", cfg.LetsEncryptListen)
-
-			err := srv.ListenAndServe()
-			if err != http.ErrServerClosed {
-				ltndLog.Errorf("autocert http: %v", err)
-			}
-			close(shutdownCompleted)
-		}()
-
-		getCertificate := func(h *tls.ClientHelloInfo) (
-			*tls.Certificate, error) {
-
-			lecert, err := manager.GetCertificate(h)
-			if err != nil {
-				ltndLog.Errorf("GetCertificate: %v", err)
-				return &certData, nil
-			}
-
-			return lecert, err
-		}
-
-		// The self-signed tls.cert remains available as fallback.
-		tlsCfg.GetCertificate = getCertificate
-	}
-
 	serverCreds := credentials.NewTLS(tlsCfg)
 	serverOpts := []grpc.ServerOption{grpc.Creds(serverCreds)}
 
@@ -791,7 +685,7 @@ func getTLSConfig(cfg *Config) ([]grpc.ServerOption, []grpc.DialOption,
 	restListen := func(addr net.Addr) (net.Listener, error) {
 		// For restListen we will call ListenOnAddress if TLS is
 		// disabled.
-		if cfg.DisableRestTLS {
+		if t.cfg.DisableRestTLS {
 			return lncfg.ListenOnAddress(addr)
 		}
 
@@ -801,6 +695,191 @@ func getTLSConfig(cfg *Config) ([]grpc.ServerOption, []grpc.DialOption,
 	return serverOpts, restDialOpts, restListen, cleanUp, nil
 }
 
+// generateOrRenewCert generates a new TLS certificate if we're not using one
+// yet or renews it if it's outdated.
+func (t *TLSManager) generateOrRenewCert() (*tls.Config, func(), error) {
+	// Genereate a TLS pair if we don't have one yet.
+	err := t.createTLSPair()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	certData, parsedCert, err := cert.LoadCert(
+		t.cfg.TLSCertPath, t.cfg.TLSKeyPath,
+	)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Check to see if the certificate needs to be renewed. If it does, we
+	// return the newly generated certificate data instead.
+	reloadedCertData, err := t.certMaintenance(parsedCert)
+	if err != nil {
+		return nil, nil, err
+	}
+	if reloadedCertData != nil {
+		certData = *reloadedCertData
+	}
+
+	tlsCfg := cert.TLSConfFromCert(certData)
+
+	cleanUp := t.setUpLetsEncrypt(&certData, tlsCfg)
+
+	return tlsCfg, cleanUp, nil
+}
+
+// If a TLS pair doesn't exist yet, create them and write them to disk.
+func (t *TLSManager) createTLSPair() error {
+	// Ensure we create TLS key and certificate if they don't exist.
+	if fileExists(t.cfg.TLSCertPath) || fileExists(t.cfg.TLSKeyPath) {
+		return nil
+	}
+
+	rpcsLog.Infof("Generating TLS certificates...")
+	err := cert.GenCertPair(
+		"lnd autogenerated cert", t.cfg.TLSCertPath,
+		t.cfg.TLSKeyPath, t.cfg.TLSExtraIPs,
+		t.cfg.TLSExtraDomains, t.cfg.TLSDisableAutofill,
+		t.cfg.TLSCertDuration,
+	)
+	rpcsLog.Infof("Done generating TLS certificates")
+
+	return err
+}
+
+// certMaintenance checks if the certificate IP and domains matches the config,
+// and renews the certificate if either this data is outdated or the
+// certificate is expired.
+func (t *TLSManager) certMaintenance(
+	parsedCert *x509.Certificate) (*tls.Certificate, error) {
+
+	// We check whether the certificate we have on disk match the IPs and
+	// domains specified by the config. If the extra IPs or domains have
+	// changed from when the certificate was created, we will refresh the
+	// certificate if auto refresh is active.
+	refresh := false
+	var err error
+	if t.cfg.TLSAutoRefresh {
+		refresh, err = cert.IsOutdated(
+			parsedCert, t.cfg.TLSExtraIPs,
+			t.cfg.TLSExtraDomains, t.cfg.TLSDisableAutofill,
+		)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// If the certificate expired or it was outdated, delete it and the TLS
+	// key and generate a new pair.
+	if !time.Now().After(parsedCert.NotAfter) && !refresh {
+		return nil, nil
+	}
+
+	ltndLog.Info("TLS certificate is expired or outdated, " +
+		"generating a new one")
+
+	err = os.Remove(t.cfg.TLSCertPath)
+	if err != nil {
+		return nil, err
+	}
+
+	err = os.Remove(t.cfg.TLSKeyPath)
+	if err != nil {
+		return nil, err
+	}
+
+	rpcsLog.Infof("Renewing TLS certificates...")
+	err = cert.GenCertPair(
+		"lnd autogenerated cert", t.cfg.TLSCertPath,
+		t.cfg.TLSKeyPath, t.cfg.TLSExtraIPs,
+		t.cfg.TLSExtraDomains, t.cfg.TLSDisableAutofill,
+		t.cfg.TLSCertDuration,
+	)
+	if err != nil {
+		return nil, err
+	}
+	rpcsLog.Infof("Done renewing TLS certificates")
+
+	// Reload the certificate data.
+	reloadedCertData, _, err := cert.LoadCert(
+		t.cfg.TLSCertPath, t.cfg.TLSKeyPath,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &reloadedCertData, nil
+}
+
+// setUpLetsEncrypt automatically generates a Let's Encrypt certificate if the
+// option is set.
+func (t *TLSManager) setUpLetsEncrypt(certData *tls.Certificate,
+	tlsCfg *tls.Config) func() {
+
+	// If Let's Encrypt is enabled, instantiate autocert to request/renew
+	// the certificates.
+	cleanUp := func() {}
+	if t.cfg.LetsEncryptDomain == "" {
+		return cleanUp
+	}
+
+	ltndLog.Infof("Using Let's Encrypt certificate for domain %v",
+		t.cfg.LetsEncryptDomain)
+
+	manager := autocert.Manager{
+		Cache:  autocert.DirCache(t.cfg.LetsEncryptDir),
+		Prompt: autocert.AcceptTOS,
+		HostPolicy: autocert.HostWhitelist(
+			t.cfg.LetsEncryptDomain,
+		),
+	}
+
+	srv := &http.Server{
+		Addr:    t.cfg.LetsEncryptListen,
+		Handler: manager.HTTPHandler(nil),
+	}
+	shutdownCompleted := make(chan struct{})
+	cleanUp = func() {
+		err := srv.Shutdown(context.Background())
+		if err != nil {
+			ltndLog.Errorf("Autocert listener shutdown "+
+				" error: %v", err)
+
+			return
+		}
+		<-shutdownCompleted
+		ltndLog.Infof("Autocert challenge listener stopped")
+	}
+
+	go func() {
+		ltndLog.Infof("Autocert challenge listener started "+
+			"at %v", t.cfg.LetsEncryptListen)
+
+		err := srv.ListenAndServe()
+		if err != http.ErrServerClosed {
+			ltndLog.Errorf("autocert http: %v", err)
+		}
+		close(shutdownCompleted)
+	}()
+
+	getCertificate := func(h *tls.ClientHelloInfo) (
+		*tls.Certificate, error) {
+
+		lecert, err := manager.GetCertificate(h)
+		if err != nil {
+			ltndLog.Errorf("GetCertificate: %v", err)
+			return certData, nil
+		}
+
+		return lecert, err
+	}
+
+	// The self-signed tls.cert remains available as fallback.
+	tlsCfg.GetCertificate = getCertificate
+
+	return cleanUp
+}
+
 // fileExists reports whether the named file or directory exists.
 // This function is taken from https://github.com/btcsuite/btcd
 func fileExists(name string) bool {

server_test.go

@@ -71,7 +71,8 @@ func TestTLSAutoRegeneration(t *testing.T) {
 		TLSCertDuration: 42 * time.Hour,
 		RPCListeners:    rpcListeners,
 	}
-	_, _, _, cleanUp, err := getTLSConfig(cfg)
+	tlsManager := NewTLSManager(cfg)
+	_, _, _, cleanUp, err := tlsManager.getConfig()
 	if err != nil {
 		t.Fatalf("couldn't retrieve TLS config")
 	}