net: update zoneCache on cache misses to cover appearing interfaces

performance differences are in measurement noise as per benchcmp:

benchmark                            old ns/op     new ns/op     delta
BenchmarkUDP6LinkLocalUnicast-12     5012          5009          -0.06%

Fixes #28535

Change-Id: Id022e2ed089ce8388a2398e755848ec94e77e653
Reviewed-on: https://go-review.googlesource.com/c/146941
Run-TryBot: Mikio Hara <mikioh.public.networking@gmail.com>
Reviewed-by: Mikio Hara <mikioh.public.networking@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/net/interface_linux_test.go b/src/net/interface_linux_test.go
index 6959ddb3d9..0699fec636 100644
--- a/src/net/interface_linux_test.go
+++ b/src/net/interface_linux_test.go
@@ -35,6 +35,31 @@ func (ti *testInterface) setBroadcast(suffix int) error {
 	return nil
 }
 
+func (ti *testInterface) setLinkLocal(suffix int) error {
+	ti.name = fmt.Sprintf("gotest%d", suffix)
+	xname, err := exec.LookPath("ip")
+	if err != nil {
+		return err
+	}
+	ti.setupCmds = append(ti.setupCmds, &exec.Cmd{
+		Path: xname,
+		Args: []string{"ip", "link", "add", ti.name, "type", "dummy"},
+	})
+	ti.setupCmds = append(ti.setupCmds, &exec.Cmd{
+		Path: xname,
+		Args: []string{"ip", "address", "add", ti.local, "dev", ti.name},
+	})
+	ti.teardownCmds = append(ti.teardownCmds, &exec.Cmd{
+		Path: xname,
+		Args: []string{"ip", "address", "del", ti.local, "dev", ti.name},
+	})
+	ti.teardownCmds = append(ti.teardownCmds, &exec.Cmd{
+		Path: xname,
+		Args: []string{"ip", "link", "delete", ti.name, "type", "dummy"},
+	})
+	return nil
+}
+
 func (ti *testInterface) setPointToPoint(suffix int) error {
 	ti.name = fmt.Sprintf("gotest%d", suffix)
 	xname, err := exec.LookPath("ip")