[client] Cleanup firewall state on startup (#2768)

client/firewall/nftables/state_linux.go

@@ -0,0 +1,47 @@
+package nftables
+
+import (
+	"fmt"
+
+	"github.com/netbirdio/netbird/client/iface"
+	"github.com/netbirdio/netbird/client/iface/device"
+)
+
+type InterfaceState struct {
+	NameStr       string          `json:"name"`
+	WGAddress     iface.WGAddress `json:"wg_address"`
+	UserspaceBind bool            `json:"userspace_bind"`
+}
+
+func (i *InterfaceState) Name() string {
+	return i.NameStr
+}
+
+func (i *InterfaceState) Address() device.WGAddress {
+	return i.WGAddress
+}
+
+func (i *InterfaceState) IsUserspaceBind() bool {
+	return i.UserspaceBind
+}
+
+type ShutdownState struct {
+	InterfaceState *InterfaceState `json:"interface_state,omitempty"`
+}
+
+func (s *ShutdownState) Name() string {
+	return "nftables_state"
+}
+
+func (s *ShutdownState) Cleanup() error {
+	nft, err := Create(s.InterfaceState)
+	if err != nil {
+		return fmt.Errorf("create nftables manager: %w", err)
+	}
+
+	if err := nft.Reset(nil); err != nil {
+		return fmt.Errorf("reset nftables manager: %w", err)
+	}
+
+	return nil
+}