chore(all): return concrete types, accept interfaces

- Remove exported interfaces unused locally
- Define interfaces to accept arguments
- Return concrete types, not interfaces

internal/routing/routing.go

@@ -8,37 +8,37 @@ import (
 	"github.com/qdm12/gluetun/internal/netlink"
 )
 
-type ReadWriter interface {
-	Reader
-	Writer
-}
-
-type Reader interface {
-	DefaultRouteGetter
-	LocalNetworksGetter
-	VPNGetter
-}
-
-type VPNGetter interface {
-	VPNDestinationIPGetter
-	VPNLocalGatewayIPGetter
-}
-
-type Writer interface {
-	Setuper
-	TearDowner
-	OutboundRoutesSetter
+type NetLinker interface {
+	AddrList(link netlink.Link, family int) (
+		addresses []netlink.Addr, err error)
+	AddrAdd(link netlink.Link, addr *netlink.Addr) error
+	IsWireguardSupported() (ok bool, err error)
+	RouteList(link netlink.Link, family int) (
+		routes []netlink.Route, err error)
+	RouteAdd(route *netlink.Route) error
+	RouteDel(route *netlink.Route) error
+	RouteReplace(route *netlink.Route) error
+	RuleList(family int) (rules []netlink.Rule, err error)
+	RuleAdd(rule *netlink.Rule) error
+	RuleDel(rule *netlink.Rule) error
+	LinkList() (links []netlink.Link, err error)
+	LinkByName(name string) (link netlink.Link, err error)
+	LinkByIndex(index int) (link netlink.Link, err error)
+	LinkAdd(link netlink.Link) (err error)
+	LinkDel(link netlink.Link) (err error)
+	LinkSetUp(link netlink.Link) (err error)
+	LinkSetDown(link netlink.Link) (err error)
 }
 
 type Routing struct {
-	netLinker       netlink.NetLinker
+	netLinker       NetLinker
 	logger          Logger
 	outboundSubnets []net.IPNet
 	stateMutex      sync.RWMutex
 }
 
 // New creates a new routing instance.
-func New(netLinker netlink.NetLinker, logger Logger) *Routing {
+func New(netLinker NetLinker, logger Logger) *Routing {
 	return &Routing{
 		netLinker: netLinker,
 		logger:    logger,