refactor: tidy up tls cert stuff

internal/app/bridge/bridge.go

@@ -19,12 +19,14 @@
 package bridge
 
 import (
+	"crypto/tls"
 	"time"
 
 	"github.com/ProtonMail/proton-bridge/internal/api"
 	"github.com/ProtonMail/proton-bridge/internal/app/base"
 	"github.com/ProtonMail/proton-bridge/internal/bridge"
 	"github.com/ProtonMail/proton-bridge/internal/config/settings"
+	pkgTLS "github.com/ProtonMail/proton-bridge/internal/config/tls"
 	"github.com/ProtonMail/proton-bridge/internal/constants"
 	"github.com/ProtonMail/proton-bridge/internal/frontend"
 	"github.com/ProtonMail/proton-bridge/internal/frontend/types"
@@ -58,9 +60,9 @@ func New(base *base.Base) *cli.App {
 }
 
 func run(b *base.Base, c *cli.Context) error { // nolint[funlen]
-	tls, err := b.TLS.GetConfig()
+	tlsConfig, err := loadTLSConfig(b)
 	if err != nil {
-		logrus.WithError(err).Fatal("Failed to create TLS config")
+		logrus.WithError(err).Fatal("Failed to load TLS config")
 	}
 
 	bridge := bridge.New(b.Locations, b.Cache, b.Settings, b.CrashHandler, b.Listener, b.CM, b.Creds)
@@ -78,7 +80,7 @@ func run(b *base.Base, c *cli.Context) error { // nolint[funlen]
 		imap.NewIMAPServer(
 			c.String("log-imap") == "client" || c.String("log-imap") == "all",
 			c.String("log-imap") == "server" || c.String("log-imap") == "all",
-			imapPort, tls, imapBackend, b.Listener).ListenAndServe()
+			imapPort, tlsConfig, imapBackend, b.Listener).ListenAndServe()
 	}()
 
 	go func() {
@@ -87,7 +89,7 @@ func run(b *base.Base, c *cli.Context) error { // nolint[funlen]
 		useSSL := b.Settings.GetBool(settings.SMTPSSLKey)
 		smtp.NewSMTPServer(
 			c.Bool("log-smtp"),
-			smtpPort, useSSL, tls, smtpBackend, b.Listener).ListenAndServe()
+			smtpPort, useSSL, tlsConfig, smtpBackend, b.Listener).ListenAndServe()
 	}()
 
 	// Bridge supports no-window option which we should use for autostart.
@@ -140,6 +142,44 @@ func run(b *base.Base, c *cli.Context) error { // nolint[funlen]
 	return f.Loop()
 }
 
+func loadTLSConfig(b *base.Base) (*tls.Config, error) {
+	if !b.TLS.HasCerts() {
+		if err := generateTLSCerts(b); err != nil {
+			return nil, err
+		}
+	}
+
+	tlsConfig, err := b.TLS.GetConfig()
+	if err == nil {
+		return tlsConfig, nil
+	}
+
+	logrus.WithError(err).Error("Failed to load TLS config, regenerating certificates")
+
+	if err := generateTLSCerts(b); err != nil {
+		return nil, err
+	}
+
+	return b.TLS.GetConfig()
+}
+
+func generateTLSCerts(b *base.Base) error {
+	template, err := pkgTLS.NewTLSTemplate()
+	if err != nil {
+		return errors.Wrap(err, "failed to generate TLS template")
+	}
+
+	if err := b.TLS.GenerateCerts(template); err != nil {
+		return errors.Wrap(err, "failed to generate TLS certs")
+	}
+
+	if err := b.TLS.InstallCerts(); err != nil {
+		return errors.Wrap(err, "failed to install TLS certs")
+	}
+
+	return nil
+}
+
 func checkAndHandleUpdate(u types.Updater, f frontend.Frontend, autoUpdate bool) {
 	version, err := u.Check()
 	if err != nil {

internal/config/tls/cert_store_darwin.go

@@ -0,0 +1,53 @@
+// Copyright (c) 2021 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ProtonMail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package tls
+
+import "os/exec"
+
+func addTrustedCert(certPath string) error {
+	return exec.Command( // nolint[gosec]
+		"/usr/bin/security",
+		"execute-with-privileges",
+		"/usr/bin/security",
+		"add-trusted-cert",
+		"-d",
+		"-r", "trustRoot",
+		"-p", "ssl",
+		"-k", "/Library/Keychains/System.keychain",
+		certPath,
+	).Run()
+}
+
+func removeTrustedCert(certPath string) error {
+	return exec.Command( // nolint[gosec]
+		"/usr/bin/security",
+		"execute-with-privileges",
+		"/usr/bin/security",
+		"remove-trusted-cert",
+		"-d",
+		certPath,
+	).Run()
+}
+
+func (t *TLS) InstallCerts() error {
+	return addTrustedCert(t.getTLSCertPath())
+}
+
+func (t *TLS) UninstallCerts() error {
+	return removeTrustedCert(t.getTLSCertPath())
+}

internal/config/tls/cert_store_linux.go

@@ -0,0 +1,26 @@
+// Copyright (c) 2021 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ProtonMail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package tls
+
+func (t *TLS) InstallCerts() error {
+	return nil // Linux doesn't have a root cert store.
+}
+
+func (t *TLS) UninstallCerts() error {
+	return nil // Linux doesn't have a root cert store.
+}

internal/config/tls/cert_store_windows.go

@@ -0,0 +1,26 @@
+// Copyright (c) 2021 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ProtonMail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package tls
+
+func (t *TLS) InstallCerts() error {
+	return nil // NOTE(GODT-986): Install certs to root cert store?
+}
+
+func (t *TLS) UninstallCerts() error {
+	return nil // NOTE(GODT-986): Uninstall certs from root cert store?
+}

internal/config/tls/tls.go

@@ -28,12 +28,10 @@ import (
 	"math/big"
 	"net"
 	"os"
-	"os/exec"
 	"path/filepath"
-	"runtime"
 	"time"
 
-	"github.com/sirupsen/logrus"
+	"github.com/pkg/errors"
 )
 
 type TLS struct {
@@ -46,8 +44,15 @@ func New(settingsPath string) *TLS {
 	}
 }
 
-var tlsTemplate = x509.Certificate{ //nolint[gochecknoglobals]
-	SerialNumber: big.NewInt(-1),
+// NewTLSTemplate creates a new TLS template certificate with a random serial number.
+func NewTLSTemplate() (*x509.Certificate, error) {
+	serialNumber, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to generate serial number")
+	}
+
+	return &x509.Certificate{
+		SerialNumber: serialNumber,
 		Subject: pkix.Name{
 			Country:            []string{"CH"},
 			Organization:       []string{"Proton Technologies AG"},
@@ -61,9 +66,10 @@ var tlsTemplate = x509.Certificate{ //nolint[gochecknoglobals]
 		IPAddresses:           []net.IP{net.ParseIP("127.0.0.1")},
 		NotBefore:             time.Now(),
 		NotAfter:              time.Now().Add(20 * 365 * 24 * time.Hour),
+	}, nil
 }
 
-var ErrTLSCertExpireSoon = fmt.Errorf("TLS certificate will expire soon")
+var ErrTLSCertExpiresSoon = fmt.Errorf("TLS certificate will expire soon")
 
 // getTLSCertPath returns path to certificate; used for TLS servers (IMAP, SMTP).
 func (t *TLS) getTLSCertPath() string {
@@ -75,110 +81,78 @@ func (t *TLS) getTLSKeyPath() string {
 	return filepath.Join(t.settingsPath, "key.pem")
 }
 
-// GenerateConfig generates certs and keys at the given filepaths and returns a TLS Config which holds them.
-// See https://golang.org/src/crypto/tls/generate_cert.go
-func (t *TLS) GenerateConfig() (tlsConfig *tls.Config, err error) {
+// HasCerts returns whether TLS certs have been generated.
+func (t *TLS) HasCerts() bool {
+	if _, err := os.Stat(t.getTLSCertPath()); err != nil {
+		return false
+	}
+
+	if _, err := os.Stat(t.getTLSKeyPath()); err != nil {
+		return false
+	}
+
+	return true
+}
+
+// GenerateCerts generates certs from the given template.
+func (t *TLS) GenerateCerts(template *x509.Certificate) error {
 	priv, err := rsa.GenerateKey(rand.Reader, 2048)
 	if err != nil {
-		err = fmt.Errorf("failed to generate private key: %s", err)
-		return
+		return errors.Wrap(err, "failed to generate private key")
 	}
 
-	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
-	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	derBytes, err := x509.CreateCertificate(rand.Reader, template, template, &priv.PublicKey, priv)
 	if err != nil {
-		err = fmt.Errorf("failed to generate serial number: %s", err)
-		return
-	}
-
-	tlsTemplate.SerialNumber = serialNumber
-	derBytes, err := x509.CreateCertificate(rand.Reader, &tlsTemplate, &tlsTemplate, &priv.PublicKey, priv)
-	if err != nil {
-		err = fmt.Errorf("failed to create certificate: %s", err)
-		return
+		return errors.Wrap(err, "failed to create certificate")
 	}
 
 	certOut, err := os.Create(t.getTLSCertPath())
 	if err != nil {
-		return
+		return err
 	}
 	defer certOut.Close() // nolint[errcheck]
-	err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
-	if err != nil {
-		return
+
+	if err := pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes}); err != nil {
+		return err
 	}
 
 	keyOut, err := os.OpenFile(t.getTLSKeyPath(), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 	if err != nil {
-		return
+		return err
 	}
 	defer keyOut.Close() // nolint[errcheck]
-	err = pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)})
-	if err != nil {
-		return
+
+	if err := pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)}); err != nil {
+		return err
 	}
 
-	return loadTLSConfig(t.getTLSCertPath(), t.getTLSKeyPath())
+	return nil
 }
 
 // GetConfig tries to load TLS config or generate new one which is then returned.
-func (t *TLS) GetConfig() (tlsConfig *tls.Config, err error) {
-	certPath := t.getTLSCertPath()
-	keyPath := t.getTLSKeyPath()
-	tlsConfig, err = loadTLSConfig(certPath, keyPath)
+func (t *TLS) GetConfig() (*tls.Config, error) {
+	c, err := tls.LoadX509KeyPair(t.getTLSCertPath(), t.getTLSKeyPath())
 	if err != nil {
-		logrus.WithError(err).Warn("Cannot load cert, generating a new one")
-		tlsConfig, err = t.GenerateConfig()
-		if err != nil {
-			return
-		}
-
-		if runtime.GOOS == "darwin" {
-			if err := exec.Command( // nolint[gosec]
-				"/usr/bin/security",
-				"execute-with-privileges",
-				"/usr/bin/security",
-				"add-trusted-cert",
-				"-d",
-				"-r", "trustRoot",
-				"-p", "ssl",
-				"-k", "/Library/Keychains/System.keychain",
-				certPath,
-			).Run(); err != nil {
-				logrus.WithError(err).Error("Failed to add cert to system keychain")
-			}
-		}
-	}
-
-	tlsConfig.ServerName = "127.0.0.1"
-	tlsConfig.ClientAuth = tls.VerifyClientCertIfGiven
-
-	caCertPool := x509.NewCertPool()
-	caCertPool.AddCert(tlsConfig.Certificates[0].Leaf)
-	tlsConfig.RootCAs = caCertPool
-	tlsConfig.ClientCAs = caCertPool
-
-	return tlsConfig, err
-}
-
-func loadTLSConfig(certPath, keyPath string) (tlsConfig *tls.Config, err error) {
-	c, err := tls.LoadX509KeyPair(certPath, keyPath)
-	if err != nil {
-		return
+		return nil, errors.Wrap(err, "failed to load keypair")
 	}
 
 	c.Leaf, err = x509.ParseCertificate(c.Certificate[0])
 	if err != nil {
-		return
-	}
-
-	tlsConfig = &tls.Config{
-		Certificates: []tls.Certificate{c},
+		return nil, errors.Wrap(err, "failed to parse certificate")
 	}
 
 	if time.Now().Add(31 * 24 * time.Hour).After(c.Leaf.NotAfter) {
-		err = ErrTLSCertExpireSoon
-		return
+		return nil, ErrTLSCertExpiresSoon
 	}
-	return
+
+	caCertPool := x509.NewCertPool()
+	caCertPool.AddCert(c.Leaf)
+
+	return &tls.Config{
+		Certificates: []tls.Certificate{c},
+		ServerName:   "127.0.0.1",
+		ClientAuth:   tls.VerifyClientCertIfGiven,
+		RootCAs:      caCertPool,
+		ClientCAs:    caCertPool,
+	}, nil
 }

internal/config/tls/tls_test.go

@@ -19,46 +19,59 @@ package tls
 
 import (
 	"io/ioutil"
-	"os"
-	"path/filepath"
-	"runtime"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/require"
 )
 
-func TestTLSKeyRenewal(t *testing.T) {
-	// Remove keys.
-	configPath := "/tmp"
-	certPath := filepath.Join(configPath, "cert.pem")
-	keyPath := filepath.Join(configPath, "key.pem")
-	_ = os.Remove(certPath)
-	_ = os.Remove(keyPath)
-
+func TestGetOldConfig(t *testing.T) {
 	dir, err := ioutil.TempDir("", "test-tls")
 	require.NoError(t, err)
 
+	// Create new tls object.
 	tls := New(dir)
 
-	// Put old key there.
+	// Create new TLS template.
+	tlsTemplate, err := NewTLSTemplate()
+	require.NoError(t, err)
+
+	// Make the template be an old key.
 	tlsTemplate.NotBefore = time.Now().Add(-365 * 24 * time.Hour)
 	tlsTemplate.NotAfter = time.Now()
-	cert, err := tls.GenerateConfig()
-	require.Equal(t, err, ErrTLSCertExpireSoon)
-	require.Equal(t, len(cert.Certificates), 1)
-	time.Sleep(time.Second)
-	now, notValidAfter := time.Now(), cert.Certificates[0].Leaf.NotAfter
-	require.True(t, now.After(notValidAfter), "old certificate expected to not be valid at %v but have valid until %v", now, notValidAfter)
 
-	// Renew key.
+	// Generate the certs from the template.
+	require.NoError(t, tls.GenerateCerts(tlsTemplate))
+
+	// Generate the config from the certs -- it's going to expire soon so we don't want to use it.
+	_, err = tls.GetConfig()
+	require.Equal(t, err, ErrTLSCertExpiresSoon)
+}
+
+func TestGetValidConfig(t *testing.T) {
+	dir, err := ioutil.TempDir("", "test-tls")
+	require.NoError(t, err)
+
+	// Create new tls object.
+	tls := New(dir)
+
+	// Create new TLS template.
+	tlsTemplate, err := NewTLSTemplate()
+	require.NoError(t, err)
+
+	// Make the template be a new key.
 	tlsTemplate.NotBefore = time.Now()
 	tlsTemplate.NotAfter = time.Now().Add(2 * 365 * 24 * time.Hour)
-	cert, err = tls.GetConfig()
-	if runtime.GOOS != "darwin" { // Darwin is not supported.
+
+	// Generate the certs from the template.
+	require.NoError(t, tls.GenerateCerts(tlsTemplate))
+
+	// Generate the config from the certs -- it's not going to expire soon so we want to use it.
+	config, err := tls.GetConfig()
 	require.NoError(t, err)
-	}
-	require.Equal(t, len(cert.Certificates), 1)
-	now, notValidAfter = time.Now(), cert.Certificates[0].Leaf.NotAfter
+	require.Equal(t, len(config.Certificates), 1)
+
+	// Check the cert is valid.
+	now, notValidAfter := time.Now(), config.Certificates[0].Leaf.NotAfter
 	require.False(t, now.After(notValidAfter), "new certificate expected to be valid at %v but have valid until %v", now, notValidAfter)
 }