hst: optionally reject insecure options

This prevents inadvertent use of insecure compatibility features.

Closes #30.

Signed-off-by: Ophestra <cat@gensokyo.uk>

hst/config.go

@@ -140,21 +140,29 @@ var (
 	ErrInsecure = errors.New("configuration is insecure")
 )
 
+const (
+	// VAllowInsecure allows use of compatibility options considered insecure
+	// under any configuration, to work around ecosystem-wide flaws.
+	VAllowInsecure = 1 << iota
+)
+
 // Validate checks [Config] and returns [AppError] if an invalid value is encountered.
-func (config *Config) Validate() error {
+func (config *Config) Validate(flags int) error {
+	const step = "validate configuration"
+
 	if config == nil {
-		return &AppError{Step: "validate configuration", Err: ErrConfigNull,
+		return &AppError{Step: step, Err: ErrConfigNull,
 			Msg: "invalid configuration"}
 	}
 
 	// this is checked again in hsu
 	if config.Identity < IdentityStart || config.Identity > IdentityEnd {
-		return &AppError{Step: "validate configuration", Err: ErrIdentityBounds,
+		return &AppError{Step: step, Err: ErrIdentityBounds,
 			Msg: "identity " + strconv.Itoa(config.Identity) + " out of range"}
 	}
 
 	if config.SchedPolicy < 0 || config.SchedPolicy > ext.SCHED_LAST {
-		return &AppError{Step: "validate configuration", Err: ErrSchedPolicyBounds,
+		return &AppError{Step: step, Err: ErrSchedPolicyBounds,
 			Msg: "scheduling policy " +
 				strconv.Itoa(int(config.SchedPolicy)) +
 				" out of range"}
@@ -168,34 +176,51 @@ func (config *Config) Validate() error {
 	}
 
 	if config.Container == nil {
-		return &AppError{Step: "validate configuration", Err: ErrConfigNull,
+		return &AppError{Step: step, Err: ErrConfigNull,
 			Msg: "configuration missing container state"}
 	}
 	if config.Container.Home == nil {
-		return &AppError{Step: "validate configuration", Err: ErrConfigNull,
+		return &AppError{Step: step, Err: ErrConfigNull,
 			Msg: "container configuration missing path to home directory"}
 	}
 	if config.Container.Shell == nil {
-		return &AppError{Step: "validate configuration", Err: ErrConfigNull,
+		return &AppError{Step: step, Err: ErrConfigNull,
 			Msg: "container configuration missing path to shell"}
 	}
 	if config.Container.Path == nil {
-		return &AppError{Step: "validate configuration", Err: ErrConfigNull,
+		return &AppError{Step: step, Err: ErrConfigNull,
 			Msg: "container configuration missing path to initial program"}
 	}
 
 	for key := range config.Container.Env {
 		if strings.IndexByte(key, '=') != -1 || strings.IndexByte(key, 0) != -1 {
-			return &AppError{Step: "validate configuration", Err: ErrEnviron,
+			return &AppError{Step: step, Err: ErrEnviron,
 				Msg: "invalid environment variable " + strconv.Quote(key)}
 		}
 	}
 
-	if et := config.Enablements.Unwrap(); !config.DirectPulse && et&EPulse != 0 {
-		return &AppError{Step: "validate configuration", Err: ErrInsecure,
+	et := config.Enablements.Unwrap()
+	if !config.DirectPulse && et&EPulse != 0 {
+		return &AppError{Step: step, Err: ErrInsecure,
 			Msg: "enablement PulseAudio is insecure and no longer supported"}
 	}
 
+	if flags&VAllowInsecure == 0 {
+		switch {
+		case et&EWayland != 0 && config.DirectWayland:
+			return &AppError{Step: step, Err: ErrInsecure,
+				Msg: "direct_wayland is insecure and no longer supported"}
+
+		case et&EPipeWire != 0 && config.DirectPipeWire:
+			return &AppError{Step: step, Err: ErrInsecure,
+				Msg: "direct_pipewire is insecure and no longer supported"}
+
+		case et&EPulse != 0 && config.DirectPulse:
+			return &AppError{Step: step, Err: ErrInsecure,
+				Msg: "direct_pulse is insecure and no longer supported"}
+		}
+	}
+
 	return nil
 }