chore(portforward): move vpn gateway obtention within port forwarding service

internal/provider/utils/noportforward.go

@@ -4,16 +4,11 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"net/http"
-	"net/netip"
 )
 
 type NoPortForwarder interface {
-	PortForward(ctx context.Context, client *http.Client,
-		logger Logger, gateway netip.Addr, serverName string) (
-		port uint16, err error)
-	KeepPortForward(ctx context.Context, port uint16, gateway netip.Addr,
-		serverName string, logger Logger) (err error)
+	PortForward(ctx context.Context, objects PortForwardObjects) (port uint16, err error)
+	KeepPortForward(ctx context.Context, objects PortForwardObjects) (err error)
 }
 
 type NoPortForwarding struct {
@@ -28,12 +23,11 @@ func NewNoPortForwarding(providerName string) *NoPortForwarding {
 
 var ErrPortForwardingNotSupported = errors.New("custom port forwarding obtention is not supported")
 
-func (n *NoPortForwarding) PortForward(context.Context, *http.Client,
-	Logger, netip.Addr, string) (port uint16, err error) {
+func (n *NoPortForwarding) PortForward(context.Context, PortForwardObjects) (
+	port uint16, err error) {
 	return 0, fmt.Errorf("%w: for %s", ErrPortForwardingNotSupported, n.providerName)
 }
 
-func (n *NoPortForwarding) KeepPortForward(context.Context, uint16, netip.Addr,
-	string, Logger) (err error) {
+func (n *NoPortForwarding) KeepPortForward(context.Context, PortForwardObjects) (err error) {
 	return fmt.Errorf("%w: for %s", ErrPortForwardingNotSupported, n.providerName)
 }

internal/provider/utils/portforward.go

@@ -0,0 +1,27 @@
+package utils
+
+import (
+	"net/http"
+	"net/netip"
+)
+
+// PortForwardObjects contains fields that may or may not need to be set
+// depending on the port forwarding provider code.
+type PortForwardObjects struct {
+	// Logger is a logger, used by both Private Internet Access and ProtonVPN.
+	Logger Logger
+	// Gateway is the VPN gateway IP address, used by Private Internet Access
+	// and ProtonVPN.
+	Gateway netip.Addr
+	// Client is used to query the VPN gateway for Private Internet Access.
+	Client *http.Client
+	// ServerName is used by Private Internet Access for port forwarding,
+	// and to look up the server data from storage.
+	// TODO use server data directly to remove storage dependency for port
+	// forwarding implementation.
+	ServerName string
+}
+
+type Routing interface {
+	VPNLocalGatewayIP(vpnInterface string) (gateway netip.Addr, err error)
+}