chore(all): replace netlink library for more flexibility (#3107)

internal/netlink/link_test.go

@@ -0,0 +1,85 @@
+//go:build linux
+
+package netlink
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_NetLink_LinkList(t *testing.T) {
+	t.Parallel()
+
+	netlink := &NetLink{}
+
+	initialLinks, err := netlink.LinkList()
+	require.NoError(t, err)
+	require.NotEmpty(t, initialLinks)
+
+	loopbackFound := false
+	for _, link := range initialLinks {
+		if link.Name != "lo" {
+			continue
+		}
+		loopbackFound = true
+		assert.Equal(t, DeviceTypeLoopback, link.DeviceType)
+		break
+	}
+	assert.True(t, loopbackFound, "loopback interface not found")
+
+	testLink := Link{
+		Name: makeLinkName(),
+		// note if [Link.VirtualType] is set, [Link.DeviceType]
+		// is ignored and gets set to [DeviceTypeNone] in LinkAdd.
+		DeviceType:  DeviceTypeNone,
+		VirtualType: "wireguard",
+		MTU:         1420,
+	}
+	index, err := netlink.LinkAdd(testLink)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		_ = netlink.LinkDel(index)
+	})
+
+	links, err := netlink.LinkList()
+	require.NoError(t, err)
+
+	testLink.Index = index
+	for _, link := range links {
+		if link.Name != testLink.Name {
+			continue
+		}
+		assert.Equal(t, testLink, link)
+		return
+	}
+	t.Errorf("created link %q not found", testLink.Name)
+}
+
+func Test_NetLink_LinkSetMTU(t *testing.T) {
+	t.Parallel()
+
+	netlink := &NetLink{}
+
+	testLink := Link{
+		Name:        makeLinkName(),
+		DeviceType:  DeviceTypeNone,
+		VirtualType: "wireguard",
+		MTU:         1420,
+	}
+	index, err := netlink.LinkAdd(testLink)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		_ = netlink.LinkDel(index)
+	})
+	testLink.Index = index
+
+	err = netlink.LinkSetMTU(index, 1500)
+	require.NoError(t, err)
+
+	link, err := netlink.LinkByIndex(index)
+	require.NoError(t, err)
+	testLink.MTU = 1500
+	assert.Equal(t, testLink, link)
+}