Adding support for RTA_VIA

Signed-off-by: Steve Shaw <shaw38@gmail.com>

route.go

@@ -45,6 +45,7 @@ type Route struct {
 	MPLSDst          *int
 	NewDst           Destination
 	Encap            Encap
+	Via              Destination
 	MTU              int
 	Window           int
 	Rtt              int
@@ -79,6 +80,9 @@ func (r Route) String() string {
 	if r.Encap != nil {
 		elems = append(elems, fmt.Sprintf("Encap: %s", r.Encap))
 	}
+	if r.Via != nil {
+		elems = append(elems, fmt.Sprintf("Via: %s", r.Via))
+	}
 	elems = append(elems, fmt.Sprintf("Src: %s", r.Src))
 	if len(r.MultiPath) > 0 {
 		elems = append(elems, fmt.Sprintf("Gw: %s", r.MultiPath))
@@ -107,6 +111,7 @@ func (r Route) Equal(x Route) bool {
 		r.Flags == x.Flags &&
 		(r.MPLSDst == x.MPLSDst || (r.MPLSDst != nil && x.MPLSDst != nil && *r.MPLSDst == *x.MPLSDst)) &&
 		(r.NewDst == x.NewDst || (r.NewDst != nil && r.NewDst.Equal(x.NewDst))) &&
+		(r.Via == x.Via || (r.Via != nil && r.Via.Equal(x.Via))) &&
 		(r.Encap == x.Encap || (r.Encap != nil && r.Encap.Equal(x.Encap)))
 }
 
@@ -136,6 +141,7 @@ type NexthopInfo struct {
 	Flags     int
 	NewDst    Destination
 	Encap     Encap
+	Via       Destination
 }
 
 func (n *NexthopInfo) String() string {
@@ -147,6 +153,9 @@ func (n *NexthopInfo) String() string {
 	if n.Encap != nil {
 		elems = append(elems, fmt.Sprintf("Encap: %s", n.Encap))
 	}
+	if n.Via != nil {
+		elems = append(elems, fmt.Sprintf("Via: %s", n.Via))
+	}
 	elems = append(elems, fmt.Sprintf("Weight: %d", n.Hops+1))
 	elems = append(elems, fmt.Sprintf("Gw: %s", n.Gw))
 	elems = append(elems, fmt.Sprintf("Flags: %s", n.ListFlags()))

route_linux.go

@@ -1,6 +1,8 @@
 package netlink
 
 import (
+	"bytes"
+	"encoding/binary"
 	"fmt"
 	"net"
 	"strings"
@@ -446,6 +448,62 @@ func (e *SEG6LocalEncap) Equal(x Encap) bool {
 	return true
 }
 
+type Via struct {
+	AddrFamily int
+	Addr       net.IP
+}
+
+func (v *Via) Equal(x Destination) bool {
+	o, ok := x.(*Via)
+	if !ok {
+		return false
+	}
+	if v.AddrFamily == x.Family() && v.Addr.Equal(o.Addr) {
+		return true
+	}
+	return false
+}
+
+func (v *Via) String() string {
+	return fmt.Sprintf("Family: %d, Address: %s", v.AddrFamily, v.Addr.String())
+}
+
+func (v *Via) Family() int {
+	return v.AddrFamily
+}
+
+func (v *Via) Encode() ([]byte, error) {
+	buf := &bytes.Buffer{}
+	err := binary.Write(buf, native, uint16(v.AddrFamily))
+	if err != nil {
+		return nil, err
+	}
+	err = binary.Write(buf, native, v.Addr)
+	if err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+func (v *Via) Decode(b []byte) error {
+	native := nl.NativeEndian()
+	if len(b) < 6 {
+		return fmt.Errorf("decoding failed: buffer too small (%d bytes)", len(b))
+	}
+	v.AddrFamily = int(native.Uint16(b[0:2]))
+	if v.AddrFamily == nl.FAMILY_V4 {
+		v.Addr = net.IP(b[2:6])
+		return nil
+	} else if v.AddrFamily == nl.FAMILY_V6 {
+		if len(b) < 18 {
+			return fmt.Errorf("decoding failed: buffer too small (%d bytes)", len(b))
+		}
+		v.Addr = net.IP(b[2:])
+		return nil
+	}
+	return fmt.Errorf("decoding failed: address family %d unknown", v.AddrFamily)
+}
+
 // RouteAdd will add a route to the system.
 // Equivalent to: `ip route add $route`
 func RouteAdd(route *Route) error {
@@ -567,6 +625,14 @@ func (h *Handle) routeHandle(route *Route, req *nl.NetlinkRequest, msg *nl.RtMsg
 		rtAttrs = append(rtAttrs, nl.NewRtAttr(unix.RTA_GATEWAY, gwData))
 	}
 
+	if route.Via != nil {
+		buf, err := route.Via.Encode()
+		if err != nil {
+			return fmt.Errorf("failed to encode RTA_VIA: %v", err)
+		}
+		rtAttrs = append(rtAttrs, nl.NewRtAttr(unix.RTA_VIA, buf))
+	}
+
 	if len(route.MultiPath) > 0 {
 		buf := []byte{}
 		for _, nh := range route.MultiPath {
@@ -609,6 +675,13 @@ func (h *Handle) routeHandle(route *Route, req *nl.NetlinkRequest, msg *nl.RtMsg
 				}
 				children = append(children, nl.NewRtAttr(unix.RTA_ENCAP, buf))
 			}
+			if nh.Via != nil {
+				buf, err := nh.Via.Encode()
+				if err != nil {
+					return err
+				}
+				children = append(children, nl.NewRtAttr(unix.RTA_VIA, buf))
+			}
 			rtnh.Children = children
 			buf = append(buf, rtnh.Serialize()...)
 		}
@@ -907,6 +980,12 @@ func deserializeRoute(m []byte) (Route, error) {
 						encapType = attr
 					case unix.RTA_ENCAP:
 						encap = attr
+					case unix.RTA_VIA:
+						d := &Via{}
+						if err := d.Decode(attr.Value); err != nil {
+							return nil, nil, err
+						}
+						info.Via = d
 					}
 				}
 
@@ -944,6 +1023,12 @@ func deserializeRoute(m []byte) (Route, error) {
 				return route, err
 			}
 			route.NewDst = d
+		case unix.RTA_VIA:
+			v := &Via{}
+			if err := v.Decode(attr.Value); err != nil {
+				return route, err
+			}
+			route.Via = v
 		case unix.RTA_ENCAP_TYPE:
 			encapType = attr
 		case unix.RTA_ENCAP:

route_test.go

@@ -1339,3 +1339,69 @@ func TestMTURouteAddDel(t *testing.T) {
 		t.Fatal("Route not removed properly")
 	}
 }
+
+func TestRouteViaAddDel(t *testing.T) {
+	minKernelRequired(t, 5, 4)
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+
+	_, err := RouteList(nil, FAMILY_V4)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	link, err := LinkByName("lo")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := LinkSetUp(link); err != nil {
+		t.Fatal(err)
+	}
+
+	route := &Route{
+		LinkIndex: link.Attrs().Index,
+		Dst: &net.IPNet{
+			IP:   net.IPv4(192, 168, 0, 0),
+			Mask: net.CIDRMask(24, 32),
+		},
+		MultiPath: []*NexthopInfo{
+			{
+				LinkIndex: link.Attrs().Index,
+				Via: &Via{
+					AddrFamily: FAMILY_V6,
+					Addr:       net.ParseIP("2001::1"),
+				},
+			},
+		},
+	}
+
+	if err := RouteAdd(route); err != nil {
+		t.Fatalf("route: %v, err: %v", route, err)
+	}
+
+	routes, err := RouteList(link, FAMILY_V4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(routes) != 1 {
+		t.Fatal("Route not added properly")
+	}
+
+	got := routes[0].Via
+	want := route.MultiPath[0].Via
+	if !want.Equal(got) {
+		t.Fatalf("Route Via attribute does not match; got: %s, want: %s", got, want)
+	}
+
+	if err := RouteDel(route); err != nil {
+		t.Fatal(err)
+	}
+	routes, err = RouteList(link, FAMILY_V4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(routes) != 0 {
+		t.Fatal("Route not removed properly")
+	}
+}