The DNS search path on Windows is now restored when Telepresence quits

The DNS search path that Telepresence uses to simulate the DNS lookup
functionality in the connected cluster namespace was not removed by a
`telepresence quit`, resulting in connectivity problems from the
workstation. Telepresence will now remove the entries that it has added
to the search list when it quits.

Signed-off-by: Thomas Hallgren <[email protected]>

CHANGELOG.yml

@@ -33,6 +33,12 @@ items:
   - version: 2.17.1
     date: (TBD)
     notes:
+      - type: bugfix
+        title: The DNS search path on Windows is now restored when Telepresence quits
+        body: The DNS search path that Telepresence uses to simulate the DNS lookup functionality in the connected
+          cluster namespace was not removed by a <code>telepresence quit</code>, resulting in connectivity problems
+          from the workstation. Telepresence will now remove the entries that it has added to the search list when
+          it quits.
       - type: bugfix
         title: Multiple services ports using the same target port would not get intercepted correctly.
         body: Intercepts didn't work when multiple service ports were using the same container port. Telepresence would

pkg/client/rootd/dns/server_windows.go

@@ -31,6 +31,11 @@ func (s *Server) Worker(c context.Context, dev vif.Device, configureDNS func(net
 	g := dgroup.NewGroup(c, dgroup.GroupConfig{})
 	g.Go("Server", func(c context.Context) error {
 		// No need to close listener. It's closed by the dns server.
+		defer func() {
+			c, cancel := context.WithTimeout(context.WithoutCancel(c), 5*time.Second)
+			_ = dev.SetDNS(c, s.clusterDomain, s.config.RemoteIp, nil)
+			cancel()
+		}()
 		s.processSearchPaths(g, s.updateRouterDNS, dev)
 		return s.Run(c, make(chan struct{}), []net.PacketConn{listener}, nil, s.resolveInCluster)
 	})

pkg/vif/device_windows.go

@@ -203,22 +203,26 @@ func (t *nativeDevice) setDNS(ctx context.Context, clusterDomain string, server
 	if err != nil {
 		return err
 	}
-	// Windows does not use a dot suffix in the search path.
-	clusterDomain = strings.TrimSuffix(clusterDomain, ".")
-
 	// Put our new search path in front of other entries. Then include those
 	// that don't end with our cluster domain (these are entries that aren't
 	// managed by Telepresence).
 	uniq := make(map[string]int, len(searchList)+len(gss))
 	i := 0
 	for _, gs := range searchList {
+		gs = strings.TrimSuffix(gs, ".")
 		if _, ok := uniq[gs]; !ok {
 			uniq[gs] = i
 			i++
 		}
 	}
+	clusterDomainDot := "." + clusterDomain
+	clusterDomain = strings.TrimSuffix(clusterDomainDot, ".")
+	ours := func(gs string) bool {
+		return strings.HasSuffix(gs, clusterDomain) || strings.HasSuffix(gs, clusterDomainDot) || gs == "tel2-search"
+	}
+
 	for _, gs := range gss {
-		if !strings.HasSuffix(gs, clusterDomain) {
+		if !ours(gs) {
 			if _, ok := uniq[gs]; !ok {
 				uniq[gs] = i
 				i++
@@ -241,7 +245,7 @@ func psList(values []string) string {
 			sb.WriteByte(',')
 		}
 		sb.WriteByte('"')
-		sb.WriteString(strings.TrimSuffix(gs, "."))
+		sb.WriteString(gs)
 		sb.WriteByte('"')
 	}
 	sb.WriteByte(')')
@@ -311,7 +315,9 @@ func (t *nativeDevice) setRegistryGlobalSearchList(ctx context.Context, gss []st
 		dlog.Errorf(ctx, `creating/opening registry value %s\%s failed: %v`, tcpParamKey, searchListKey, err)
 	} else {
 		defer rk.Close()
-		if err = rk.SetStringValue(searchListKey, strings.Join(gss, ",")); err != nil {
+		rv := strings.Join(gss, ",")
+		dlog.Debugf(ctx, `setting registry value %s\%s to %s`, tcpParamKey, searchListKey, rv)
+		if err = rk.SetStringValue(searchListKey, rv); err != nil {
 			dlog.Errorf(ctx, `setting registry value %s\%s failed: %v`, tcpParamKey, searchListKey, err)
 		}
 	}