Add allmulti to link attributes

Provide the status of the allmulticast option via the highlevel
link attributes instead of requiring raw flag handling.

link.go

@@ -35,6 +35,7 @@ type LinkAttrs struct {
 	Alias        string
 	Statistics   *LinkStatistics
 	Promisc      int
+	Allmulti     int
 	Xdp          *LinkXdp
 	EncapType    string
 	Protinfo     *Protinfo

link_linux.go

@@ -153,7 +153,6 @@ func (h *Handle) LinkSetAllmulticastOn(link Link) error {
 	msg := nl.NewIfInfomsg(unix.AF_UNSPEC)
 	msg.Change = unix.IFF_ALLMULTI
 	msg.Flags = unix.IFF_ALLMULTI
-
 	msg.Index = int32(base.Index)
 	req.AddData(msg)
 
@@ -1624,7 +1623,7 @@ func execGetLink(req *nl.NetlinkRequest) (Link, error) {
 	}
 }
 
-// linkDeserialize deserializes a raw message received from netlink into
+// LinkDeserialize deserializes a raw message received from netlink into
 // a link object.
 func LinkDeserialize(hdr *unix.NlMsghdr, m []byte) (Link, error) {
 	msg := nl.DeserializeIfInfomsg(m)
@@ -1642,6 +1641,9 @@ func LinkDeserialize(hdr *unix.NlMsghdr, m []byte) (Link, error) {
 	if msg.Flags&unix.IFF_PROMISC != 0 {
 		base.Promisc = 1
 	}
+	if msg.Flags&unix.IFF_ALLMULTI != 0 {
+		base.Allmulti = 1
+	}
 	var (
 		link      Link
 		stats32   *LinkStatistics32

link_test.go

@@ -2647,7 +2647,7 @@ func TestLinkSetAllmulticast(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if link.Attrs().RawFlags&unix.IFF_ALLMULTI != uint32(unix.IFF_ALLMULTI) {
+	if link.Attrs().Allmulti != 1 {
 		t.Fatal("IFF_ALLMULTI was not set")
 	}
 
@@ -2660,7 +2660,7 @@ func TestLinkSetAllmulticast(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if link.Attrs().RawFlags&unix.IFF_ALLMULTI != 0 {
+	if link.Attrs().Allmulti != 0 {
 		t.Fatal("IFF_ALLMULTI is still set")
 	}