feat(validation): reject server filters ignored for some VPN providers

internal/configuration/settings/helpers/belong.go

@@ -15,9 +15,16 @@ func IsOneOf(value string, choices ...string) (ok bool) {
 	return false
 }
 
-var ErrValueNotOneOf = errors.New("value is not one of the possible choices")
+var (
+	ErrNoChoice      = errors.New("one or more values is set but there is no possible value available")
+	ErrValueNotOneOf = errors.New("value is not one of the possible choices")
+)
 
 func AreAllOneOf(values, choices []string) (err error) {
+	if len(values) > 0 && len(choices) == 0 {
+		return ErrNoChoice
+	}
+
 	set := make(map[string]struct{}, len(choices))
 	for _, choice := range choices {
 		choice = strings.ToLower(choice)

internal/configuration/settings/serverselection.go

@@ -1,6 +1,7 @@
 package settings
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"strings"
@@ -37,16 +38,16 @@ type ServerSelection struct { //nolint:maligned
 	Numbers []uint16
 	// Hostnames is the list of hostnames to filter VPN servers with.
 	Hostnames []string
-	// OwnedOnly is true if only VPN provider owned servers
+	// OwnedOnly is true if VPN provider servers that are not owned
 	// should be filtered. This is used with Mullvad.
 	OwnedOnly *bool
-	// FreeOnly is true if only free VPN servers
-	// should be filtered. This is used with ProtonVPN.
+	// FreeOnly is true if VPN servers that are not free should
+	// be filtered. This is used with ProtonVPN and VPN Unlimited.
 	FreeOnly *bool
-	// FreeOnly is true if only free VPN servers
-	// should be filtered. This is used with ProtonVPN.
+	// StreamOnly is true if VPN servers not for streaming should
+	// be filtered. This is used with VPNUnlimited.
 	StreamOnly *bool
-	// MultiHopOnly is true if only multihop VPN servers
+	// MultiHopOnly is true if VPN servers that are not multihop
 	// should be filtered. This is used with Surfshark.
 	MultiHopOnly *bool
 
@@ -58,6 +59,13 @@ type ServerSelection struct { //nolint:maligned
 	Wireguard WireguardSelection
 }
 
+var (
+	ErrOwnedOnlyNotSupported    = errors.New("owned only filter is not supported")
+	ErrFreeOnlyNotSupported     = errors.New("free only filter is not supported")
+	ErrStreamOnlyNotSupported   = errors.New("stream only filter is not supported")
+	ErrMultiHopOnlyNotSupported = errors.New("multi hop only filter is not supported")
+)
+
 func (ss *ServerSelection) validate(vpnServiceProvider string,
 	allServers models.AllServers) (err error) {
 	switch ss.VPN {
@@ -66,8 +74,71 @@ func (ss *ServerSelection) validate(vpnServiceProvider string,
 		return fmt.Errorf("%w: %s", ErrVPNTypeNotValid, ss.VPN)
 	}
 
-	var countryChoices, regionChoices, cityChoices,
-		ispChoices, nameChoices, hostnameChoices []string
+	countryChoices, regionChoices, cityChoices,
+		ispChoices, nameChoices, hostnameChoices, err := getLocationFilterChoices(vpnServiceProvider, ss, allServers)
+	if err != nil {
+		return err // already wrapped error
+	}
+
+	err = validateServerFilters(*ss, countryChoices, regionChoices, cityChoices,
+		ispChoices, nameChoices, hostnameChoices)
+	if err != nil {
+		if errors.Is(err, helpers.ErrNoChoice) {
+			return fmt.Errorf("for VPN service provider %s: %w", vpnServiceProvider, err)
+		}
+		return err // already wrapped error
+	}
+
+	if *ss.OwnedOnly &&
+		vpnServiceProvider != constants.Mullvad {
+		return fmt.Errorf("%w: for VPN service provider %s",
+			ErrOwnedOnlyNotSupported, vpnServiceProvider)
+	}
+
+	if *ss.FreeOnly &&
+		!helpers.IsOneOf(vpnServiceProvider,
+			constants.Protonvpn,
+			constants.VPNUnlimited,
+		) {
+		return fmt.Errorf("%w: for VPN service provider %s",
+			ErrFreeOnlyNotSupported, vpnServiceProvider)
+	}
+
+	if *ss.StreamOnly &&
+		!helpers.IsOneOf(vpnServiceProvider,
+			constants.Protonvpn,
+			constants.VPNUnlimited,
+		) {
+		return fmt.Errorf("%w: for VPN service provider %s",
+			ErrStreamOnlyNotSupported, vpnServiceProvider)
+	}
+
+	if *ss.MultiHopOnly &&
+		vpnServiceProvider != constants.Surfshark {
+		return fmt.Errorf("%w: for VPN service provider %s",
+			ErrStreamOnlyNotSupported, vpnServiceProvider)
+	}
+
+	if ss.VPN == constants.OpenVPN {
+		err = ss.OpenVPN.validate(vpnServiceProvider)
+		if err != nil {
+			return fmt.Errorf("OpenVPN server selection settings validation failed: %w", err)
+		}
+	} else {
+		err = ss.Wireguard.validate(vpnServiceProvider)
+		if err != nil {
+			return fmt.Errorf("Wireguard server selection settings validation failed: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func getLocationFilterChoices(vpnServiceProvider string, ss *ServerSelection,
+	allServers models.AllServers) (
+	countryChoices, regionChoices, cityChoices,
+	ispChoices, nameChoices, hostnameChoices []string,
+	err error) {
 	switch vpnServiceProvider {
 	case constants.Custom:
 	case constants.Cyberghost:
@@ -151,7 +222,7 @@ func (ss *ServerSelection) validate(vpnServiceProvider string,
 		// TODO v4 remove
 		regionChoices = append(regionChoices, validation.SurfsharkRetroLocChoices()...)
 		if err := helpers.AreAllOneOf(ss.Regions, regionChoices); err != nil {
-			return fmt.Errorf("%w: %s", ErrRegionNotValid, err)
+			return nil, nil, nil, nil, nil, nil, fmt.Errorf("%w: %s", ErrRegionNotValid, err)
 		}
 		// Retro compatibility
 		// TODO remove in v4
@@ -179,28 +250,11 @@ func (ss *ServerSelection) validate(vpnServiceProvider string,
 		cityChoices = validation.WindscribeCityChoices(servers)
 		hostnameChoices = validation.WindscribeHostnameChoices(servers)
 	default:
-		return fmt.Errorf("%w: %s", ErrVPNProviderNameNotValid, vpnServiceProvider)
+		return nil, nil, nil, nil, nil, nil, fmt.Errorf("%w: %s", ErrVPNProviderNameNotValid, vpnServiceProvider)
 	}
 
-	err = validateServerFilters(*ss, countryChoices, regionChoices, cityChoices,
-		ispChoices, nameChoices, hostnameChoices)
-	if err != nil {
-		return err // already wrapped error
-	}
-
-	if ss.VPN == constants.OpenVPN {
-		err = ss.OpenVPN.validate(vpnServiceProvider)
-		if err != nil {
-			return fmt.Errorf("OpenVPN server selection settings validation failed: %w", err)
-		}
-	} else {
-		err = ss.Wireguard.validate(vpnServiceProvider)
-		if err != nil {
-			return fmt.Errorf("Wireguard server selection settings validation failed: %w", err)
-		}
-	}
-
-	return nil
+	return countryChoices, regionChoices, cityChoices,
+		ispChoices, nameChoices, hostnameChoices, nil
 }
 
 // validateServerFilters validates filters against the choices given as arguments.
@@ -208,40 +262,28 @@ func (ss *ServerSelection) validate(vpnServiceProvider string,
 func validateServerFilters(settings ServerSelection,
 	countryChoices, regionChoices, cityChoices, ispChoices,
 	nameChoices, hostnameChoices []string) (err error) {
-	if countryChoices != nil {
-		if err := helpers.AreAllOneOf(settings.Countries, countryChoices); err != nil {
-			return fmt.Errorf("%w: %s", ErrCountryNotValid, err)
-		}
+	if err := helpers.AreAllOneOf(settings.Countries, countryChoices); err != nil {
+		return fmt.Errorf("%w: %s", ErrCountryNotValid, err)
 	}
 
-	if regionChoices != nil {
-		if err := helpers.AreAllOneOf(settings.Regions, regionChoices); err != nil {
-			return fmt.Errorf("%w: %s", ErrRegionNotValid, err)
-		}
+	if err := helpers.AreAllOneOf(settings.Regions, regionChoices); err != nil {
+		return fmt.Errorf("%w: %s", ErrRegionNotValid, err)
 	}
 
-	if cityChoices != nil {
-		if err := helpers.AreAllOneOf(settings.Cities, cityChoices); err != nil {
-			return fmt.Errorf("%w: %s", ErrCityNotValid, err)
-		}
+	if err := helpers.AreAllOneOf(settings.Cities, cityChoices); err != nil {
+		return fmt.Errorf("%w: %s", ErrCityNotValid, err)
 	}
 
-	if ispChoices != nil {
-		if err := helpers.AreAllOneOf(settings.ISPs, ispChoices); err != nil {
-			return fmt.Errorf("%w: %s", ErrISPNotValid, err)
-		}
+	if err := helpers.AreAllOneOf(settings.ISPs, ispChoices); err != nil {
+		return fmt.Errorf("%w: %s", ErrISPNotValid, err)
 	}
 
-	if hostnameChoices != nil {
-		if err := helpers.AreAllOneOf(settings.Hostnames, hostnameChoices); err != nil {
-			return fmt.Errorf("%w: %s", ErrHostnameNotValid, err)
-		}
+	if err := helpers.AreAllOneOf(settings.Hostnames, hostnameChoices); err != nil {
+		return fmt.Errorf("%w: %s", ErrHostnameNotValid, err)
 	}
 
-	if nameChoices != nil {
-		if err := helpers.AreAllOneOf(settings.Names, nameChoices); err != nil {
-			return fmt.Errorf("%w: %s", ErrNameNotValid, err)
-		}
+	if err := helpers.AreAllOneOf(settings.Names, nameChoices); err != nil {
+		return fmt.Errorf("%w: %s", ErrNameNotValid, err)
 	}
 
 	return nil