feat(portforwarding): VPN_PORT_FORWARDING_DOWN_COMMAND option

Dockerfile

@@ -126,6 +126,7 @@ ENV VPN_SERVICE_PROVIDER=pia \
     VPN_PORT_FORWARDING_USERNAME= \
     VPN_PORT_FORWARDING_PASSWORD= \
     VPN_PORT_FORWARDING_UP_COMMAND= \
+    VPN_PORT_FORWARDING_DOWN_COMMAND= \
     # # Cyberghost only:
     OPENVPN_CERT= \
     OPENVPN_KEY= \

internal/configuration/settings/portforward.go

@@ -33,6 +33,10 @@ type PortForwarding struct {
 	// It can be the empty string to indicate not to run a command.
 	// It cannot be nil in the internal state.
 	UpCommand *string `json:"up_command"`
+	// DownCommand is the command to use after the port forwarding goes down.
+	// It can be the empty string to indicate to NOT run a command.
+	// It cannot be nil in the internal state.
+	DownCommand *string `json:"down_command"`
 	// ListeningPort is the port traffic would be redirected to from the
 	// forwarded port. The redirection is disabled if it is set to 0, which
 	// is its default as well.
@@ -89,6 +93,7 @@ func (p *PortForwarding) Copy() (copied PortForwarding) {
 		Provider:      gosettings.CopyPointer(p.Provider),
 		Filepath:      gosettings.CopyPointer(p.Filepath),
 		UpCommand:     gosettings.CopyPointer(p.UpCommand),
+		DownCommand:   gosettings.CopyPointer(p.DownCommand),
 		ListeningPort: gosettings.CopyPointer(p.ListeningPort),
 		Username:      p.Username,
 		Password:      p.Password,
@@ -100,6 +105,7 @@ func (p *PortForwarding) OverrideWith(other PortForwarding) {
 	p.Provider = gosettings.OverrideWithPointer(p.Provider, other.Provider)
 	p.Filepath = gosettings.OverrideWithPointer(p.Filepath, other.Filepath)
 	p.UpCommand = gosettings.OverrideWithPointer(p.UpCommand, other.UpCommand)
+	p.DownCommand = gosettings.OverrideWithPointer(p.DownCommand, other.DownCommand)
 	p.ListeningPort = gosettings.OverrideWithPointer(p.ListeningPort, other.ListeningPort)
 	p.Username = gosettings.OverrideWithComparable(p.Username, other.Username)
 	p.Password = gosettings.OverrideWithComparable(p.Password, other.Password)
@@ -110,6 +116,7 @@ func (p *PortForwarding) setDefaults() {
 	p.Provider = gosettings.DefaultPointer(p.Provider, "")
 	p.Filepath = gosettings.DefaultPointer(p.Filepath, "/tmp/gluetun/forwarded_port")
 	p.UpCommand = gosettings.DefaultPointer(p.UpCommand, "")
+	p.DownCommand = gosettings.DefaultPointer(p.DownCommand, "")
 	p.ListeningPort = gosettings.DefaultPointer(p.ListeningPort, 0)
 }
 
@@ -142,9 +149,11 @@ func (p PortForwarding) toLinesNode() (node *gotree.Node) {
 	}
 	node.Appendf("Forwarded port file path: %s", filepath)
 
-	command := *p.UpCommand
-	if command != "" {
-		node.Appendf("Forwarded port command: %s", command)
+	if *p.UpCommand != "" {
+		node.Appendf("Forwarded port up command: %s", *p.UpCommand)
+	}
+	if *p.DownCommand != "" {
+		node.Appendf("Forwarded port down command: %s", *p.DownCommand)
 	}
 
 	if p.Username != "" {
@@ -178,6 +187,9 @@ func (p *PortForwarding) read(r *reader.Reader) (err error) {
 	p.UpCommand = r.Get("VPN_PORT_FORWARDING_UP_COMMAND",
 		reader.ForceLowercase(false))
 
+	p.DownCommand = r.Get("VPN_PORT_FORWARDING_DOWN_COMMAND",
+		reader.ForceLowercase(false))
+
 	p.ListeningPort, err = r.Uint16Ptr("VPN_PORT_FORWARDING_LISTENING_PORT")
 	if err != nil {
 		return err

internal/portforward/loop.go

@@ -44,6 +44,7 @@ func NewLoop(settings settings.PortForwarding, routing Routing,
 				Enabled:       settings.Enabled,
 				Filepath:      *settings.Filepath,
 				UpCommand:     *settings.UpCommand,
+				DownCommand:   *settings.DownCommand,
 				ListeningPort: *settings.ListeningPort,
 			},
 		},

internal/portforward/service/command.go

@@ -9,7 +9,7 @@ import (
 	"github.com/qdm12/gluetun/internal/command"
 )
 
-func runUpCommand(ctx context.Context, cmder Cmder, logger Logger,
+func runCommand(ctx context.Context, cmder Cmder, logger Logger,
 	commandTemplate string, ports []uint16,
 ) (err error) {
 	portStrings := make([]string, len(ports))

internal/portforward/service/command_test.go

@@ -11,7 +11,7 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func Test_Service_runUpCommand(t *testing.T) {
+func Test_Service_runCommand(t *testing.T) {
 	t.Parallel()
 	ctrl := gomock.NewController(t)
 
@@ -22,7 +22,7 @@ func Test_Service_runUpCommand(t *testing.T) {
 	logger := NewMockLogger(ctrl)
 	logger.EXPECT().Info("1234,5678")
 
-	err := runUpCommand(ctx, cmder, logger, commandTemplate, ports)
+	err := runCommand(ctx, cmder, logger, commandTemplate, ports)
 
 	require.NoError(t, err)
 }

internal/portforward/service/settings.go

@@ -13,6 +13,7 @@ type Settings struct {
 	PortForwarder  PortForwarder
 	Filepath       string
 	UpCommand      string
+	DownCommand    string
 	Interface      string // needed for PIA, PrivateVPN and ProtonVPN, tun0 for example
 	ServerName     string // needed for PIA
 	CanPortForward bool   // needed for PIA
@@ -26,6 +27,7 @@ func (s Settings) Copy() (copied Settings) {
 	copied.PortForwarder = s.PortForwarder
 	copied.Filepath = s.Filepath
 	copied.UpCommand = s.UpCommand
+	copied.DownCommand = s.DownCommand
 	copied.Interface = s.Interface
 	copied.ServerName = s.ServerName
 	copied.CanPortForward = s.CanPortForward
@@ -40,6 +42,7 @@ func (s *Settings) OverrideWith(update Settings) {
 	s.PortForwarder = gosettings.OverrideWithComparable(s.PortForwarder, update.PortForwarder)
 	s.Filepath = gosettings.OverrideWithComparable(s.Filepath, update.Filepath)
 	s.UpCommand = gosettings.OverrideWithComparable(s.UpCommand, update.UpCommand)
+	s.DownCommand = gosettings.OverrideWithComparable(s.DownCommand, update.DownCommand)
 	s.Interface = gosettings.OverrideWithComparable(s.Interface, update.Interface)
 	s.ServerName = gosettings.OverrideWithComparable(s.ServerName, update.ServerName)
 	s.CanPortForward = gosettings.OverrideWithComparable(s.CanPortForward, update.CanPortForward)

internal/portforward/service/start.go

@@ -74,7 +74,7 @@ func (s *Service) Start(ctx context.Context) (runError <-chan error, err error)
 	s.portMutex.Unlock()
 
 	if s.settings.UpCommand != "" {
-		err = runUpCommand(ctx, s.cmder, s.logger, s.settings.UpCommand, ports)
+		err = runCommand(ctx, s.cmder, s.logger, s.settings.UpCommand, ports)
 		if err != nil {
 			err = fmt.Errorf("running up command: %w", err)
 			s.logger.Error(err.Error())

internal/portforward/service/stop.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"time"
 )
 
 func (s *Service) Stop() (err error) {
@@ -30,6 +31,17 @@ func (s *Service) cleanup() (err error) {
 	s.portMutex.Lock()
 	defer s.portMutex.Unlock()
 
+	if s.settings.DownCommand != "" {
+		const downTimeout = 60 * time.Second
+		ctx, cancel := context.WithTimeout(context.Background(), downTimeout)
+		defer cancel()
+		err = runCommand(ctx, s.cmder, s.logger, s.settings.DownCommand, s.ports)
+		if err != nil {
+			err = fmt.Errorf("running down command: %w", err)
+			s.logger.Error(err.Error())
+		}
+	}
+
 	for _, port := range s.ports {
 		err = s.portAllower.RemoveAllowedPort(context.Background(), port)
 		if err != nil {