Merge pull request #92 from pmazzini/route

[rtnl] add RouteGet method

rtnl/route.go

@@ -1,6 +1,7 @@
 package rtnl
 
 import (
+	"errors"
 	"net"
 
 	"github.com/jsimonetti/rtnetlink/internal/unix"
@@ -8,6 +9,12 @@ import (
 	"github.com/jsimonetti/rtnetlink"
 )
 
+// Route represents a route table entry
+type Route struct {
+	Gateway   net.IP
+	Interface *net.Interface
+}
+
 // generating route message
 func genRouteMessage(ifc *net.Interface, dst net.IPNet, gw net.IP, options ...RouteOption) (rm *rtnetlink.RouteMessage, err error) {
 
@@ -93,3 +100,35 @@ func (c *Conn) RouteDel(ifc *net.Interface, dst net.IPNet) error {
 	}
 	return c.Conn.Route.Delete(tx)
 }
+
+// RouteGet gets a single route to the given destination address.
+func (c *Conn) RouteGet(dst net.IP) (*Route, error) {
+	af, err := addrFamily(dst)
+	if err != nil {
+		return nil, err
+	}
+	attr := rtnetlink.RouteAttributes{
+		Dst: dst,
+	}
+	tx := &rtnetlink.RouteMessage{
+		Family:     uint8(af),
+		Table:      unix.RT_TABLE_MAIN,
+		Attributes: attr,
+	}
+	rx, err := c.Conn.Route.Get(tx)
+	if err != nil {
+		return nil, err
+	}
+	if len(rx) == 0 {
+		return nil, errors.New("route wrong length")
+	}
+	ifindex := int(rx[0].Attributes.OutIface)
+	iface, err := c.LinkByIndex(ifindex)
+	if err != nil {
+		return nil, err
+	}
+	return &Route{
+		Gateway:   rx[0].Attributes.Gateway,
+		Interface: iface,
+	}, nil
+}

rtnl/route_live_test.go

@@ -0,0 +1,38 @@
+// +build integration
+
+package rtnl
+
+import (
+	"net"
+	"testing"
+)
+
+func TestLiveRoute(t *testing.T) {
+	c, err := Dial(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	route, err := c.RouteGet(net.ParseIP("8.8.8.8"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("got route: %v", route)
+	if route.Gateway.IsUnspecified() {
+		t.Error("zero route.Gateway, expected non-zero")
+	}
+	if route.Gateway.IsLoopback() {
+		t.Error("lo route.Gatway, expected non lo")
+	}
+	if route.Interface == nil {
+		t.Error("nil route.Interface, expected non-nil")
+	}
+	if len(route.Interface.Name) == 0 {
+		t.Error("zero-length route.Interface.Name")
+	}
+	if hardwareAddrIsUnspecified(route.Interface.HardwareAddr) {
+		t.Error("zero route.Interface.HardwareAddr, expected non-zero")
+	}
+}