Other(refactor): Sort safe.Mutex types before locking to prevent deadlocks

This change implements safe.Mutex and safe.RWMutex, which wrap the
sync.Mutex and sync.RWMutex types and are assigned a globally unique
integer ID. The safe.Lock and safe.RLock methods sort the mutexes
by this integer ID before locking to ensure that locks for a given
set of mutexes are always performed in the same order, avoiding
deadlocks.

internal/bridge/bridge.go

@@ -52,7 +52,7 @@ type Bridge struct {
 
 	// users holds authorized users.
 	users     map[string]*user.User
-	usersLock sync.RWMutex
+	usersLock safe.RWMutex
 
 	// api manages user API clients.
 	api        *liteapi.Manager
@@ -226,7 +226,9 @@ func newBridge(
 
 	bridge := &Bridge{
 		vault: vault,
-		users: make(map[string]*user.User),
+
+		users:     make(map[string]*user.User),
+		usersLock: safe.NewRWMutex(),
 
 		api:        api,
 		proxyCtl:   proxyCtl,
@@ -363,7 +365,7 @@ func (bridge *Bridge) Close(ctx context.Context) {
 		for _, user := range bridge.users {
 			user.Close()
 		}
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 
 	// Stop all ongoing tasks.
 	bridge.tasks.Wait()
@@ -433,7 +435,7 @@ func (bridge *Bridge) onStatusUp() {
 		for _, user := range bridge.users {
 			user.OnStatusUp()
 		}
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 
 	bridge.goLoad()
 }
@@ -445,7 +447,7 @@ func (bridge *Bridge) onStatusDown() {
 		for _, user := range bridge.users {
 			user.OnStatusDown()
 		}
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 
 	bridge.tasks.Once(func(ctx context.Context) {
 		backoff := time.Second

internal/bridge/configure.go

@@ -64,5 +64,5 @@ func (bridge *Bridge) ConfigureAppleMail(userID, address string) error {
 			addresses,
 			user.BridgePass(),
 		)
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }

internal/bridge/settings.go

@@ -161,7 +161,7 @@ func (bridge *Bridge) SetGluonDir(ctx context.Context, newGluonDir string) error
 		}
 
 		return nil
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }
 
 func (bridge *Bridge) GetProxyAllowed() bool {
@@ -189,7 +189,7 @@ func (bridge *Bridge) SetShowAllMail(show bool) error {
 		}
 
 		return bridge.vault.SetShowAllMail(show)
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }
 
 func (bridge *Bridge) GetAutostart() bool {
@@ -288,7 +288,7 @@ func (bridge *Bridge) FactoryReset(ctx context.Context) {
 				logrus.WithError(err).Error("failed to delete vault user")
 			}
 		}
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 
 	// Then delete all files.
 	if err := bridge.locator.Clear(); err != nil {

internal/bridge/smtp_backend.go

@@ -58,7 +58,7 @@ func (s *smtpSession) AuthPlain(username, password string) error {
 		}
 
 		return fmt.Errorf("invalid username or password")
-	}, &s.usersLock)
+	}, s.usersLock)
 }
 
 func (s *smtpSession) Reset() {
@@ -92,5 +92,5 @@ func (s *smtpSession) Data(r io.Reader) error {
 		}
 
 		return user.SendMail(s.authID, s.from, s.to, r)
-	}, &s.usersLock)
+	}, s.usersLock)
 }

internal/bridge/user.go

@@ -80,7 +80,7 @@ func (bridge *Bridge) GetUserInfo(userID string) (UserInfo, error) {
 		}
 
 		return info, nil
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }
 
 // QueryUserInfo queries the user info by username or address.
@@ -93,7 +93,7 @@ func (bridge *Bridge) QueryUserInfo(query string) (UserInfo, error) {
 		}
 
 		return UserInfo{}, ErrNoSuchUser
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }
 
 // LoginAuth begins the login process. It returns an authorized client that might need 2FA.
@@ -105,7 +105,7 @@ func (bridge *Bridge) LoginAuth(ctx context.Context, username string, password [
 
 	if ok := safe.RLockRet(func() bool {
 		return mapHas(bridge.users, auth.UID)
-	}, &bridge.usersLock); ok {
+	}, bridge.usersLock); ok {
 		if err := client.AuthDelete(ctx); err != nil {
 			logrus.WithError(err).Warn("Failed to delete auth")
 		}
@@ -201,7 +201,7 @@ func (bridge *Bridge) LogoutUser(ctx context.Context, userID string) error {
 		})
 
 		return nil
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }
 
 // DeleteUser deletes the given user.
@@ -225,7 +225,7 @@ func (bridge *Bridge) DeleteUser(ctx context.Context, userID string) error {
 		})
 
 		return nil
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }
 
 // SetAddressMode sets the address mode for the given user.
@@ -260,7 +260,7 @@ func (bridge *Bridge) SetAddressMode(ctx context.Context, userID string, mode va
 		})
 
 		return nil
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 }
 
 func (bridge *Bridge) loginUser(ctx context.Context, client *liteapi.Client, authUID, authRef string, keyPass []byte) (string, error) {
@@ -295,7 +295,7 @@ func (bridge *Bridge) loadUsers(ctx context.Context) error {
 
 		if safe.RLockRet(func() bool {
 			return mapHas(bridge.users, user.UserID())
-		}, &bridge.usersLock) {
+		}, bridge.usersLock) {
 			return nil
 		}
 
@@ -419,7 +419,7 @@ func (bridge *Bridge) addUserWithVault(
 	// Finally, save the user in the bridge.
 	safe.Lock(func() {
 		bridge.users[apiUser.ID] = user
-	}, &bridge.usersLock)
+	}, bridge.usersLock)
 
 	return nil
 }

internal/bridge/user_events.go

@@ -49,7 +49,7 @@ func (bridge *Bridge) handleUserEvent(ctx context.Context, user *user.User, even
 			defer delete(bridge.users, user.ID())
 
 			bridge.logoutUser(ctx, user, false)
-		}, &bridge.usersLock)
+		}, bridge.usersLock)
 	}
 
 	return nil