Maint: refactor internal/routing

- Split Go files better
- Reduce public API for exported errors

internal/routing/default.go

@@ -0,0 +1,68 @@
+package routing
+
+import (
+	"errors"
+	"fmt"
+	"net"
+
+	"github.com/qdm12/gluetun/internal/netlink"
+)
+
+var (
+	ErrRouteDefaultNotFound = errors.New("default route not found")
+)
+
+type DefaultRouteGetter interface {
+	DefaultRoute() (defaultInterface string, defaultGateway net.IP, err error)
+}
+
+func (r *Routing) DefaultRoute() (defaultInterface string, defaultGateway net.IP, err error) {
+	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
+	if err != nil {
+		return "", nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
+	}
+	for _, route := range routes {
+		if route.Dst == nil {
+			defaultGateway = route.Gw
+			linkIndex := route.LinkIndex
+			link, err := r.netLinker.LinkByIndex(linkIndex)
+			if err != nil {
+				return "", nil, fmt.Errorf("%w: for default route at index %d: %s", ErrLinkByIndex, linkIndex, err)
+			}
+			attributes := link.Attrs()
+			defaultInterface = attributes.Name
+			r.logger.Info("default route found: interface " + defaultInterface +
+				", gateway " + defaultGateway.String())
+			return defaultInterface, defaultGateway, nil
+		}
+	}
+	return "", nil, fmt.Errorf("%w: in %d route(s)", ErrRouteDefaultNotFound, len(routes))
+}
+
+type DefaultIPGetter interface {
+	DefaultIP() (defaultIP net.IP, err error)
+}
+
+func (r *Routing) DefaultIP() (ip net.IP, err error) {
+	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
+	}
+
+	defaultLinkName := ""
+	for _, route := range routes {
+		if route.Dst == nil {
+			linkIndex := route.LinkIndex
+			link, err := r.netLinker.LinkByIndex(linkIndex)
+			if err != nil {
+				return nil, fmt.Errorf("%w: for default route at index %d: %s", ErrLinkByIndex, linkIndex, err)
+			}
+			defaultLinkName = link.Attrs().Name
+		}
+	}
+	if defaultLinkName == "" {
+		return nil, fmt.Errorf("%w: in %d route(s)", ErrLinkDefaultNotFound, len(routes))
+	}
+
+	return r.assignedIP(defaultLinkName)
+}

internal/routing/enable.go

@@ -17,6 +17,7 @@ var (
 	ErrIPRuleAdd          = errors.New("cannot add IP rule")
 	ErrIPRuleDelete       = errors.New("cannot delete IP rule")
 	ErrRouteAdd           = errors.New("cannot add route")
+	ErrRouteDelete        = errors.New("cannot delete route")
 	ErrSubnetsOutboundSet = errors.New("cannot set outbound subnets routes")
 )
 

internal/routing/errors.go

@@ -0,0 +1,11 @@
+package routing
+
+import (
+	"errors"
+)
+
+var (
+	ErrLinkByIndex         = errors.New("cannot obtain link by index")
+	ErrLinkDefaultNotFound = errors.New("default link not found")
+	ErrRoutesList          = errors.New("cannot list routes")
+)

internal/routing/ip.go

@@ -0,0 +1,39 @@
+package routing
+
+import (
+	"errors"
+	"fmt"
+	"net"
+)
+
+func IPIsPrivate(ip net.IP) bool {
+	return ip.IsPrivate() || ip.IsLoopback() ||
+		ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast()
+}
+
+var (
+	errInterfaceIPNotFound = errors.New("IP address not found for interface")
+	errInterfaceListAddr   = errors.New("cannot list interface addresses")
+	errInterfaceNotFound   = errors.New("network interface not found")
+)
+
+func (r *Routing) assignedIP(interfaceName string) (ip net.IP, err error) {
+	iface, err := net.InterfaceByName(interfaceName)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %s: %s", errInterfaceNotFound, interfaceName, err)
+	}
+	addresses, err := iface.Addrs()
+	if err != nil {
+		return nil, fmt.Errorf("%w: %s: %s", errInterfaceListAddr, interfaceName, err)
+	}
+	for _, address := range addresses {
+		switch value := address.(type) {
+		case *net.IPAddr:
+			return value.IP, nil
+		case *net.IPNet:
+			return value.IP, nil
+		}
+	}
+	return nil, fmt.Errorf("%w: interface %s in %d addresses",
+		errInterfaceIPNotFound, interfaceName, len(addresses))
+}

internal/routing/local.go

@@ -0,0 +1,121 @@
+package routing
+
+import (
+	"errors"
+	"fmt"
+	"net"
+
+	"github.com/qdm12/gluetun/internal/netlink"
+)
+
+var (
+	ErrLinkList              = errors.New("cannot list links")
+	ErrLinkLocalNotFound     = errors.New("local link not found")
+	ErrSubnetDefaultNotFound = errors.New("default subnet not found")
+	ErrSubnetLocalNotFound   = errors.New("local subnet not found")
+)
+
+type LocalNetwork struct {
+	IPNet         *net.IPNet
+	InterfaceName string
+	IP            net.IP
+}
+
+type LocalSubnetGetter interface {
+	LocalSubnet() (defaultSubnet net.IPNet, err error)
+}
+
+func (r *Routing) LocalSubnet() (defaultSubnet net.IPNet, err error) {
+	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
+	if err != nil {
+		return defaultSubnet, fmt.Errorf("%w: %s", ErrRoutesList, err)
+	}
+
+	defaultLinkIndex := -1
+	for _, route := range routes {
+		if route.Dst == nil {
+			defaultLinkIndex = route.LinkIndex
+			break
+		}
+	}
+	if defaultLinkIndex == -1 {
+		return defaultSubnet, fmt.Errorf("%w: in %d route(s)", ErrLinkDefaultNotFound, len(routes))
+	}
+
+	for _, route := range routes {
+		if route.Gw != nil || route.LinkIndex != defaultLinkIndex {
+			continue
+		}
+		defaultSubnet = *route.Dst
+		r.logger.Info("local subnet found: " + defaultSubnet.String())
+		return defaultSubnet, nil
+	}
+
+	return defaultSubnet, fmt.Errorf("%w: in %d routes", ErrSubnetDefaultNotFound, len(routes))
+}
+
+type LocalNetworksGetter interface {
+	LocalNetworks() (localNetworks []LocalNetwork, err error)
+}
+
+func (r *Routing) LocalNetworks() (localNetworks []LocalNetwork, err error) {
+	links, err := r.netLinker.LinkList()
+	if err != nil {
+		return localNetworks, fmt.Errorf("%w: %s", ErrLinkList, err)
+	}
+
+	localLinks := make(map[int]struct{})
+
+	for _, link := range links {
+		if link.Attrs().EncapType != "ether" {
+			continue
+		}
+
+		localLinks[link.Attrs().Index] = struct{}{}
+		r.logger.Info("local ethernet link found: " + link.Attrs().Name)
+	}
+
+	if len(localLinks) == 0 {
+		return localNetworks, fmt.Errorf("%w: in %d links", ErrLinkLocalNotFound, len(links))
+	}
+
+	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_V4)
+	if err != nil {
+		return localNetworks, fmt.Errorf("%w: %s", ErrRoutesList, err)
+	}
+
+	for _, route := range routes {
+		if route.Gw != nil || route.Dst == nil {
+			continue
+		} else if _, ok := localLinks[route.LinkIndex]; !ok {
+			continue
+		}
+
+		var localNet LocalNetwork
+
+		localNet.IPNet = route.Dst
+		r.logger.Info("local ipnet found: " + localNet.IPNet.String())
+
+		link, err := r.netLinker.LinkByIndex(route.LinkIndex)
+		if err != nil {
+			return localNetworks, fmt.Errorf("%w: at index %d: %s", ErrLinkByIndex, route.LinkIndex, err)
+		}
+
+		localNet.InterfaceName = link.Attrs().Name
+
+		ip, err := r.assignedIP(localNet.InterfaceName)
+		if err != nil {
+			return localNetworks, err
+		}
+
+		localNet.IP = ip
+
+		localNetworks = append(localNetworks, localNet)
+	}
+
+	if len(localNetworks) == 0 {
+		return localNetworks, fmt.Errorf("%w: in %d routes", ErrSubnetLocalNotFound, len(routes))
+	}
+
+	return localNetworks, nil
+}

internal/routing/mutate.go

@@ -1,126 +0,0 @@
-package routing
-
-import (
-	"bytes"
-	"errors"
-	"fmt"
-	"net"
-	"strconv"
-
-	"github.com/qdm12/gluetun/internal/netlink"
-)
-
-var (
-	ErrRouteReplace = errors.New("cannot replace route")
-	ErrRouteDelete  = errors.New("cannot delete route")
-	ErrRuleAdd      = errors.New("cannot add routing rule")
-	ErrRuleDel      = errors.New("cannot delete routing rule")
-)
-
-func (r *Routing) addRouteVia(destination net.IPNet, gateway net.IP, iface string, table int) error {
-	destinationStr := destination.String()
-	r.logger.Info("adding route for " + destinationStr)
-	r.logger.Debug("ip route replace " + destinationStr +
-		" via " + gateway.String() +
-		" dev " + iface +
-		" table " + strconv.Itoa(table))
-
-	link, err := r.netLinker.LinkByName(iface)
-	if err != nil {
-		return fmt.Errorf("%w: interface %s: %s", ErrLinkByName, iface, err)
-	}
-	route := netlink.Route{
-		Dst:       &destination,
-		Gw:        gateway,
-		LinkIndex: link.Attrs().Index,
-		Table:     table,
-	}
-	if err := r.netLinker.RouteReplace(&route); err != nil {
-		return fmt.Errorf("%w: for subnet %s at interface %s: %s",
-			ErrRouteReplace, destinationStr, iface, err)
-	}
-	return nil
-}
-
-func (r *Routing) deleteRouteVia(destination net.IPNet, gateway net.IP, iface string, table int) (err error) {
-	destinationStr := destination.String()
-	r.logger.Info("deleting route for " + destinationStr)
-	r.logger.Debug("ip route delete " + destinationStr +
-		" via " + gateway.String() +
-		" dev " + iface +
-		" table " + strconv.Itoa(table))
-
-	link, err := r.netLinker.LinkByName(iface)
-	if err != nil {
-		return fmt.Errorf("%w: for interface %s: %s", ErrLinkByName, iface, err)
-	}
-	route := netlink.Route{
-		Dst:       &destination,
-		Gw:        gateway,
-		LinkIndex: link.Attrs().Index,
-		Table:     table,
-	}
-	if err := r.netLinker.RouteDel(&route); err != nil {
-		return fmt.Errorf("%w: for subnet %s at interface %s: %s",
-			ErrRouteDelete, destinationStr, iface, err)
-	}
-	return nil
-}
-
-func (r *Routing) addIPRule(src net.IP, table, priority int) error {
-	r.logger.Debug("ip rule add from " + src.String() +
-		" lookup " + strconv.Itoa(table) +
-		" pref " + strconv.Itoa(priority))
-
-	rule := netlink.NewRule()
-	rule.Src = netlink.NewIPNet(src)
-	rule.Priority = priority
-	rule.Table = table
-
-	rules, err := r.netLinker.RuleList(netlink.FAMILY_ALL)
-	if err != nil {
-		return fmt.Errorf("%w: %s", ErrRulesList, err)
-	}
-	for _, existingRule := range rules {
-		if existingRule.Src != nil &&
-			existingRule.Src.IP.Equal(rule.Src.IP) &&
-			bytes.Equal(existingRule.Src.Mask, rule.Src.Mask) &&
-			existingRule.Priority == rule.Priority &&
-			existingRule.Table == rule.Table {
-			return nil // already exists
-		}
-	}
-
-	if err := r.netLinker.RuleAdd(rule); err != nil {
-		return fmt.Errorf("%w: for rule %q: %s", ErrRuleAdd, rule, err)
-	}
-	return nil
-}
-
-func (r *Routing) deleteIPRule(src net.IP, table, priority int) error {
-	r.logger.Debug("ip rule del from " + src.String() +
-		" lookup " + strconv.Itoa(table) +
-		" pref " + strconv.Itoa(priority))
-
-	rule := netlink.NewRule()
-	rule.Src = netlink.NewIPNet(src)
-	rule.Priority = priority
-	rule.Table = table
-
-	rules, err := r.netLinker.RuleList(netlink.FAMILY_ALL)
-	if err != nil {
-		return fmt.Errorf("%w: %s", ErrRulesList, err)
-	}
-	for _, existingRule := range rules {
-		if existingRule.Src != nil &&
-			existingRule.Src.IP.Equal(rule.Src.IP) &&
-			bytes.Equal(existingRule.Src.Mask, rule.Src.Mask) &&
-			existingRule.Priority == rule.Priority &&
-			existingRule.Table == rule.Table {
-			if err := r.netLinker.RuleDel(rule); err != nil {
-				return fmt.Errorf("%w: for rule %q: %s", ErrRuleDel, rule, err)
-			}
-		}
-	}
-	return nil
-}

internal/routing/outboundsubnets.go

@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	ErrAddOutboundSubnet = errors.New("cannot add outbound subnet to routes")
+	errAddOutboundSubnet = errors.New("cannot add outbound subnet to routes")
 )
 
 type OutboundRoutesSetter interface {
@@ -25,7 +25,7 @@ func (r *Routing) SetOutboundRoutes(outboundSubnets []net.IPNet) error {
 }
 
 func (r *Routing) setOutboundRoutes(outboundSubnets []net.IPNet,
-	defaultInterfaceName string, defaultGateway net.IP) error {
+	defaultInterfaceName string, defaultGateway net.IP) (err error) {
 	r.stateMutex.Lock()
 	defer r.stateMutex.Unlock()
 
@@ -36,20 +36,32 @@ func (r *Routing) setOutboundRoutes(outboundSubnets []net.IPNet,
 		return nil
 	}
 
-	r.removeOutboundSubnets(subnetsToRemove, defaultInterfaceName, defaultGateway)
-	return r.addOutboundSubnets(subnetsToAdd, defaultInterfaceName, defaultGateway)
+	warnings := r.removeOutboundSubnets(subnetsToRemove, defaultInterfaceName, defaultGateway)
+	for _, warning := range warnings {
+		r.logger.Warn("cannot remove outdated outbound subnet from routing: " + warning)
+	}
+
+	err = r.addOutboundSubnets(subnetsToAdd, defaultInterfaceName, defaultGateway)
+	if err != nil {
+		return fmt.Errorf("%w: %s", errAddOutboundSubnet, err)
+	}
+
+	return nil
 }
 
 func (r *Routing) removeOutboundSubnets(subnets []net.IPNet,
-	defaultInterfaceName string, defaultGateway net.IP) {
+	defaultInterfaceName string, defaultGateway net.IP) (warnings []string) {
 	for _, subNet := range subnets {
 		const table = 0
 		if err := r.deleteRouteVia(subNet, defaultGateway, defaultInterfaceName, table); err != nil {
-			r.logger.Error("cannot remove outdated outbound subnet from routing: " + err.Error())
+			warnings = append(warnings, err.Error())
 			continue
 		}
+
 		r.outboundSubnets = subnet.RemoveSubnetFromSubnets(r.outboundSubnets, subNet)
 	}
+
+	return warnings
 }
 
 func (r *Routing) addOutboundSubnets(subnets []net.IPNet,
@@ -57,7 +69,7 @@ func (r *Routing) addOutboundSubnets(subnets []net.IPNet,
 	for _, subnet := range subnets {
 		const table = 0
 		if err := r.addRouteVia(subnet, defaultGateway, defaultInterfaceName, table); err != nil {
-			return fmt.Errorf("%w: %s: %s", ErrAddOutboundSubnet, subnet, err)
+			return fmt.Errorf("%w: for subnet %s", err, subnet)
 		}
 		r.outboundSubnets = append(r.outboundSubnets, subnet)
 	}

internal/routing/reader.go

@@ -1,270 +0,0 @@
-package routing
-
-import (
-	"bytes"
-	"errors"
-	"fmt"
-	"net"
-
-	"github.com/qdm12/gluetun/internal/netlink"
-)
-
-type LocalNetwork struct {
-	IPNet         *net.IPNet
-	InterfaceName string
-	IP            net.IP
-}
-
-var (
-	ErrInterfaceIPNotFound       = errors.New("IP address not found for interface")
-	ErrInterfaceListAddr         = errors.New("cannot list interface addresses")
-	ErrInterfaceNotFound         = errors.New("network interface not found")
-	ErrLinkByIndex               = errors.New("cannot obtain link by index")
-	ErrLinkByName                = errors.New("cannot obtain link by name")
-	ErrLinkDefaultNotFound       = errors.New("default link not found")
-	ErrLinkList                  = errors.New("cannot list links")
-	ErrLinkLocalNotFound         = errors.New("local link not found")
-	ErrRouteDefaultNotFound      = errors.New("default route not found")
-	ErrRoutesList                = errors.New("cannot list routes")
-	ErrRulesList                 = errors.New("cannot list rules")
-	ErrSubnetDefaultNotFound     = errors.New("default subnet not found")
-	ErrSubnetLocalNotFound       = errors.New("local subnet not found")
-	ErrVPNDestinationIPNotFound  = errors.New("VPN destination IP address not found")
-	ErrVPNLocalGatewayIPNotFound = errors.New("VPN local gateway IP address not found")
-)
-
-type DefaultRouteGetter interface {
-	DefaultRoute() (defaultInterface string, defaultGateway net.IP, err error)
-}
-
-func (r *Routing) DefaultRoute() (defaultInterface string, defaultGateway net.IP, err error) {
-	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
-	if err != nil {
-		return "", nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
-	}
-	for _, route := range routes {
-		if route.Dst == nil {
-			defaultGateway = route.Gw
-			linkIndex := route.LinkIndex
-			link, err := r.netLinker.LinkByIndex(linkIndex)
-			if err != nil {
-				return "", nil, fmt.Errorf("%w: for default route at index %d: %s", ErrLinkByIndex, linkIndex, err)
-			}
-			attributes := link.Attrs()
-			defaultInterface = attributes.Name
-			r.logger.Info("default route found: interface " + defaultInterface +
-				", gateway " + defaultGateway.String())
-			return defaultInterface, defaultGateway, nil
-		}
-	}
-	return "", nil, fmt.Errorf("%w: in %d route(s)", ErrRouteDefaultNotFound, len(routes))
-}
-
-type DefaultIPGetter interface {
-	DefaultIP() (defaultIP net.IP, err error)
-}
-
-func (r *Routing) DefaultIP() (ip net.IP, err error) {
-	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
-	if err != nil {
-		return nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
-	}
-
-	defaultLinkName := ""
-	for _, route := range routes {
-		if route.Dst == nil {
-			linkIndex := route.LinkIndex
-			link, err := r.netLinker.LinkByIndex(linkIndex)
-			if err != nil {
-				return nil, fmt.Errorf("%w: for default route at index %d: %s", ErrLinkByIndex, linkIndex, err)
-			}
-			defaultLinkName = link.Attrs().Name
-		}
-	}
-	if defaultLinkName == "" {
-		return nil, fmt.Errorf("%w: in %d route(s)", ErrLinkDefaultNotFound, len(routes))
-	}
-
-	return r.assignedIP(defaultLinkName)
-}
-
-type LocalSubnetGetter interface {
-	LocalSubnet() (defaultSubnet net.IPNet, err error)
-}
-
-func (r *Routing) LocalSubnet() (defaultSubnet net.IPNet, err error) {
-	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
-	if err != nil {
-		return defaultSubnet, fmt.Errorf("%w: %s", ErrRoutesList, err)
-	}
-
-	defaultLinkIndex := -1
-	for _, route := range routes {
-		if route.Dst == nil {
-			defaultLinkIndex = route.LinkIndex
-			break
-		}
-	}
-	if defaultLinkIndex == -1 {
-		return defaultSubnet, fmt.Errorf("%w: in %d route(s)", ErrLinkDefaultNotFound, len(routes))
-	}
-
-	for _, route := range routes {
-		if route.Gw != nil || route.LinkIndex != defaultLinkIndex {
-			continue
-		}
-		defaultSubnet = *route.Dst
-		r.logger.Info("local subnet found: " + defaultSubnet.String())
-		return defaultSubnet, nil
-	}
-
-	return defaultSubnet, fmt.Errorf("%w: in %d routes", ErrSubnetDefaultNotFound, len(routes))
-}
-
-type LocalNetworksGetter interface {
-	LocalNetworks() (localNetworks []LocalNetwork, err error)
-}
-
-func (r *Routing) LocalNetworks() (localNetworks []LocalNetwork, err error) {
-	links, err := r.netLinker.LinkList()
-	if err != nil {
-		return localNetworks, fmt.Errorf("%w: %s", ErrLinkList, err)
-	}
-
-	localLinks := make(map[int]struct{})
-
-	for _, link := range links {
-		if link.Attrs().EncapType != "ether" {
-			continue
-		}
-
-		localLinks[link.Attrs().Index] = struct{}{}
-		r.logger.Info("local ethernet link found: " + link.Attrs().Name)
-	}
-
-	if len(localLinks) == 0 {
-		return localNetworks, fmt.Errorf("%w: in %d links", ErrLinkLocalNotFound, len(links))
-	}
-
-	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_V4)
-	if err != nil {
-		return localNetworks, fmt.Errorf("%w: %s", ErrRoutesList, err)
-	}
-
-	for _, route := range routes {
-		if route.Gw != nil || route.Dst == nil {
-			continue
-		} else if _, ok := localLinks[route.LinkIndex]; !ok {
-			continue
-		}
-
-		var localNet LocalNetwork
-
-		localNet.IPNet = route.Dst
-		r.logger.Info("local ipnet found: " + localNet.IPNet.String())
-
-		link, err := r.netLinker.LinkByIndex(route.LinkIndex)
-		if err != nil {
-			return localNetworks, fmt.Errorf("%w: at index %d: %s", ErrLinkByIndex, route.LinkIndex, err)
-		}
-
-		localNet.InterfaceName = link.Attrs().Name
-
-		ip, err := r.assignedIP(localNet.InterfaceName)
-		if err != nil {
-			return localNetworks, err
-		}
-
-		localNet.IP = ip
-
-		localNetworks = append(localNetworks, localNet)
-	}
-
-	if len(localNetworks) == 0 {
-		return localNetworks, fmt.Errorf("%w: in %d routes", ErrSubnetLocalNotFound, len(routes))
-	}
-
-	return localNetworks, nil
-}
-
-func (r *Routing) assignedIP(interfaceName string) (ip net.IP, err error) {
-	iface, err := net.InterfaceByName(interfaceName)
-	if err != nil {
-		return nil, fmt.Errorf("%w: %s: %s", ErrInterfaceNotFound, interfaceName, err)
-	}
-	addresses, err := iface.Addrs()
-	if err != nil {
-		return nil, fmt.Errorf("%w: %s: %s", ErrInterfaceListAddr, interfaceName, err)
-	}
-	for _, address := range addresses {
-		switch value := address.(type) {
-		case *net.IPAddr:
-			return value.IP, nil
-		case *net.IPNet:
-			return value.IP, nil
-		}
-	}
-	return nil, fmt.Errorf("%w: interface %s in %d addresses",
-		ErrInterfaceIPNotFound, interfaceName, len(addresses))
-}
-
-type VPNDestinationIPGetter interface {
-	VPNDestinationIP() (ip net.IP, err error)
-}
-
-func (r *Routing) VPNDestinationIP() (ip net.IP, err error) {
-	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
-	if err != nil {
-		return nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
-	}
-
-	defaultLinkIndex := -1
-	for _, route := range routes {
-		if route.Dst == nil {
-			defaultLinkIndex = route.LinkIndex
-			break
-		}
-	}
-	if defaultLinkIndex == -1 {
-		return nil, fmt.Errorf("%w: in %d route(s)", ErrLinkDefaultNotFound, len(routes))
-	}
-
-	for _, route := range routes {
-		if route.LinkIndex == defaultLinkIndex &&
-			route.Dst != nil &&
-			!IPIsPrivate(route.Dst.IP) &&
-			bytes.Equal(route.Dst.Mask, net.IPMask{255, 255, 255, 255}) {
-			return route.Dst.IP, nil
-		}
-	}
-	return nil, fmt.Errorf("%w: in %d routes", ErrVPNDestinationIPNotFound, len(routes))
-}
-
-type VPNLocalGatewayIPGetter interface {
-	VPNLocalGatewayIP(vpnIntf string) (ip net.IP, err error)
-}
-
-func (r *Routing) VPNLocalGatewayIP(vpnIntf string) (ip net.IP, err error) {
-	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
-	if err != nil {
-		return nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
-	}
-	for _, route := range routes {
-		link, err := r.netLinker.LinkByIndex(route.LinkIndex)
-		if err != nil {
-			return nil, fmt.Errorf("%w: %s", ErrLinkByIndex, err)
-		}
-		interfaceName := link.Attrs().Name
-		if interfaceName == vpnIntf &&
-			route.Dst != nil &&
-			route.Dst.IP.Equal(net.IP{0, 0, 0, 0}) {
-			return route.Gw, nil
-		}
-	}
-	return nil, fmt.Errorf("%w: in %d routes", ErrVPNLocalGatewayIPNotFound, len(routes))
-}
-
-func IPIsPrivate(ip net.IP) bool {
-	return ip.IsPrivate() || ip.IsLoopback() ||
-		ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast()
-}

internal/routing/routes.go

@@ -0,0 +1,70 @@
+package routing
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+
+	"github.com/qdm12/gluetun/internal/netlink"
+)
+
+var (
+	errLinkByName = errors.New("cannot obtain link by name")
+)
+
+func (r *Routing) addRouteVia(destination net.IPNet, gateway net.IP,
+	iface string, table int) error {
+	destinationStr := destination.String()
+	r.logger.Info("adding route for " + destinationStr)
+	r.logger.Debug("ip route replace " + destinationStr +
+		" via " + gateway.String() +
+		" dev " + iface +
+		" table " + strconv.Itoa(table))
+
+	link, err := r.netLinker.LinkByName(iface)
+	if err != nil {
+		return fmt.Errorf("%w: interface %s: %s", errLinkByName, iface, err)
+	}
+
+	route := netlink.Route{
+		Dst:       &destination,
+		Gw:        gateway,
+		LinkIndex: link.Attrs().Index,
+		Table:     table,
+	}
+	if err := r.netLinker.RouteReplace(&route); err != nil {
+		return fmt.Errorf("%w: for subnet %s at interface %s",
+			err, destinationStr, iface)
+	}
+
+	return nil
+}
+
+func (r *Routing) deleteRouteVia(destination net.IPNet, gateway net.IP,
+	iface string, table int) (err error) {
+	destinationStr := destination.String()
+	r.logger.Info("deleting route for " + destinationStr)
+	r.logger.Debug("ip route delete " + destinationStr +
+		" via " + gateway.String() +
+		" dev " + iface +
+		" table " + strconv.Itoa(table))
+
+	link, err := r.netLinker.LinkByName(iface)
+	if err != nil {
+		return fmt.Errorf("%w: for interface %s: %s", errLinkByName, iface, err)
+	}
+
+	route := netlink.Route{
+		Dst:       &destination,
+		Gw:        gateway,
+		LinkIndex: link.Attrs().Index,
+		Table:     table,
+	}
+	if err := r.netLinker.RouteDel(&route); err != nil {
+		return fmt.Errorf("%w: for subnet %s at interface %s",
+			err, destinationStr, iface)
+	}
+
+	return nil
+}

internal/routing/rules.go

@@ -0,0 +1,73 @@
+package routing
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+
+	"github.com/qdm12/gluetun/internal/netlink"
+)
+
+var (
+	errRulesList = errors.New("cannot list rules")
+)
+
+func (r *Routing) addIPRule(src net.IP, table, priority int) error {
+	r.logger.Debug("ip rule add from " + src.String() +
+		" lookup " + strconv.Itoa(table) +
+		" pref " + strconv.Itoa(priority))
+
+	rule := netlink.NewRule()
+	rule.Src = netlink.NewIPNet(src)
+	rule.Priority = priority
+	rule.Table = table
+
+	rules, err := r.netLinker.RuleList(netlink.FAMILY_ALL)
+	if err != nil {
+		return fmt.Errorf("%w: %s", errRulesList, err)
+	}
+	for _, existingRule := range rules {
+		if existingRule.Src != nil &&
+			existingRule.Src.IP.Equal(rule.Src.IP) &&
+			bytes.Equal(existingRule.Src.Mask, rule.Src.Mask) &&
+			existingRule.Priority == rule.Priority &&
+			existingRule.Table == rule.Table {
+			return nil // already exists
+		}
+	}
+
+	if err := r.netLinker.RuleAdd(rule); err != nil {
+		return fmt.Errorf("%w: for rule: %s", err, rule)
+	}
+	return nil
+}
+
+func (r *Routing) deleteIPRule(src net.IP, table, priority int) error {
+	r.logger.Debug("ip rule del from " + src.String() +
+		" lookup " + strconv.Itoa(table) +
+		" pref " + strconv.Itoa(priority))
+
+	rule := netlink.NewRule()
+	rule.Src = netlink.NewIPNet(src)
+	rule.Priority = priority
+	rule.Table = table
+
+	rules, err := r.netLinker.RuleList(netlink.FAMILY_ALL)
+	if err != nil {
+		return fmt.Errorf("%w: %s", errRulesList, err)
+	}
+	for _, existingRule := range rules {
+		if existingRule.Src != nil &&
+			existingRule.Src.IP.Equal(rule.Src.IP) &&
+			bytes.Equal(existingRule.Src.Mask, rule.Src.Mask) &&
+			existingRule.Priority == rule.Priority &&
+			existingRule.Table == rule.Table {
+			if err := r.netLinker.RuleDel(rule); err != nil {
+				return fmt.Errorf("%w: for rule: %s", err, rule)
+			}
+		}
+	}
+	return nil
+}

internal/routing/vpn.go

@@ -0,0 +1,71 @@
+package routing
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"net"
+
+	"github.com/qdm12/gluetun/internal/netlink"
+)
+
+var (
+	ErrVPNDestinationIPNotFound  = errors.New("VPN destination IP address not found")
+	ErrVPNLocalGatewayIPNotFound = errors.New("VPN local gateway IP address not found")
+)
+
+type VPNDestinationIPGetter interface {
+	VPNDestinationIP() (ip net.IP, err error)
+}
+
+func (r *Routing) VPNDestinationIP() (ip net.IP, err error) {
+	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
+	}
+
+	defaultLinkIndex := -1
+	for _, route := range routes {
+		if route.Dst == nil {
+			defaultLinkIndex = route.LinkIndex
+			break
+		}
+	}
+	if defaultLinkIndex == -1 {
+		return nil, fmt.Errorf("%w: in %d route(s)", ErrLinkDefaultNotFound, len(routes))
+	}
+
+	for _, route := range routes {
+		if route.LinkIndex == defaultLinkIndex &&
+			route.Dst != nil &&
+			!IPIsPrivate(route.Dst.IP) &&
+			bytes.Equal(route.Dst.Mask, net.IPMask{255, 255, 255, 255}) {
+			return route.Dst.IP, nil
+		}
+	}
+	return nil, fmt.Errorf("%w: in %d routes", ErrVPNDestinationIPNotFound, len(routes))
+}
+
+type VPNLocalGatewayIPGetter interface {
+	VPNLocalGatewayIP(vpnIntf string) (ip net.IP, err error)
+}
+
+func (r *Routing) VPNLocalGatewayIP(vpnIntf string) (ip net.IP, err error) {
+	routes, err := r.netLinker.RouteList(nil, netlink.FAMILY_ALL)
+	if err != nil {
+		return nil, fmt.Errorf("%w: %s", ErrRoutesList, err)
+	}
+	for _, route := range routes {
+		link, err := r.netLinker.LinkByIndex(route.LinkIndex)
+		if err != nil {
+			return nil, fmt.Errorf("%w: %s", ErrLinkByIndex, err)
+		}
+		interfaceName := link.Attrs().Name
+		if interfaceName == vpnIntf &&
+			route.Dst != nil &&
+			route.Dst.IP.Equal(net.IP{0, 0, 0, 0}) {
+			return route.Gw, nil
+		}
+	}
+	return nil, fmt.Errorf("%w: in %d routes", ErrVPNLocalGatewayIPNotFound, len(routes))
+}