debugging save/restore staticinterface settings

postRun should not restore static settings put back validInterface check better debug logs for os resolver init, use mutex to prevent duplicate initializations use WMI instead of registry keys for static DNS data on Windows use WMI instead of registry keys for static DNS data on Windows use winipcfg DNS method use WMI with registry fallback go back to registry method restore saved static configs on stop and uninstall restore ipv6 DHCP if no saved static ipv6 addresses do not save loopback IPs for static configs handle watchdog interface changed for new interfaces dont overwrite static file on start when staticdns is set to loopback dont overwrite static file on start when staticdns is set to loopback dont overwrite static file on start when staticdns is set to loopback no need to resetDNS on start, uninstall already takes care of this
2026-07-04 01:07:49 +02:00 · 2025-02-19 02:30:10 -05:00
parent a582195cec
commit 332f8ccc37
6 changed files with 182 additions and 53 deletions
@@ -147,15 +147,32 @@ func restoreDNS(iface *net.Interface) (err error) {
 			}
 		}

-		for _, ns := range [][]string{v4ns, v6ns} {
-			if len(ns) == 0 {
-				continue
-			}
-			mainLog.Load().Debug().Msgf("setting static DNS for interface %q", iface.Name)
-			err = setDNS(iface, ns)
+		luid, err := winipcfg.LUIDFromIndex(uint32(iface.Index))
+		if err != nil {
+			return fmt.Errorf("restoreDNS: %w", err)
+		}

-			if err != nil {
-				return err
+		if len(v4ns) > 0 {
+			mainLog.Load().Debug().Msgf("restoring IPv4 static DNS for interface %q: %v", iface.Name, v4ns)
+			if err := setDNS(iface, v4ns); err != nil {
+				return fmt.Errorf("restoreDNS (IPv4): %w", err)
+			}
+		} else {
+			mainLog.Load().Debug().Msgf("restoring IPv4 DHCP for interface %q", iface.Name)
+			if err := luid.SetDNS(windows.AF_INET, nil, nil); err != nil {
+				return fmt.Errorf("restoreDNS (IPv4 clear): %w", err)
+			}
+		}
+
+		if len(v6ns) > 0 {
+			mainLog.Load().Debug().Msgf("restoring IPv6 static DNS for interface %q: %v", iface.Name, v6ns)
+			if err := setDNS(iface, v6ns); err != nil {
+				return fmt.Errorf("restoreDNS (IPv6): %w", err)
+			}
+		} else {
+			mainLog.Load().Debug().Msgf("restoring IPv6 DHCP for interface %q", iface.Name)
+			if err := luid.SetDNS(windows.AF_INET6, nil, nil); err != nil {
+				return fmt.Errorf("restoreDNS (IPv6 clear): %w", err)
 			}
 		}
 	}
@@ -180,43 +197,65 @@ func currentDNS(iface *net.Interface) []string {
 	return ns
 }

-// currentStaticDNS returns the current static DNS settings of given interface.
+// currentStaticDNS checks both the IPv4 and IPv6 paths for static DNS values using keys
+// like "NameServer" and "ProfileNameServer".
 func currentStaticDNS(iface *net.Interface) ([]string, error) {
 	luid, err := winipcfg.LUIDFromIndex(uint32(iface.Index))
 	if err != nil {
-		return nil, fmt.Errorf("winipcfg.LUIDFromIndex: %w", err)
+		return nil, fmt.Errorf("fallback winipcfg.LUIDFromIndex: %w", err)
 	}
 	guid, err := luid.GUID()
 	if err != nil {
-		return nil, fmt.Errorf("luid.GUID: %w", err)
+		return nil, fmt.Errorf("fallback luid.GUID: %w", err)
 	}
+
 	var ns []string
-	for _, path := range []string{v4InterfaceKeyPathFormat, v6InterfaceKeyPathFormat} {
-		found := false
+	keyPaths := []string{v4InterfaceKeyPathFormat, v6InterfaceKeyPathFormat}
+	for _, path := range keyPaths {
 		interfaceKeyPath := path + guid.String()
 		k, err := registry.OpenKey(registry.LOCAL_MACHINE, interfaceKeyPath, registry.QUERY_VALUE)
 		if err != nil {
-			return nil, fmt.Errorf("%s: %w", interfaceKeyPath, err)
+			mainLog.Load().Debug().Err(err).Msgf("failed to open registry key %q for interface %q; trying next key", interfaceKeyPath, iface.Name)
+			continue
 		}
-		for _, key := range []string{"NameServer", "ProfileNameServer"} {
-			if found {
-				continue
-			}
-			value, _, err := k.GetStringValue(key)
-			if err != nil && !errors.Is(err, registry.ErrNotExist) {
-				return nil, fmt.Errorf("%s: %w", key, err)
-			}
-			if len(value) > 0 {
-				found = true
-				for _, e := range strings.Split(value, ",") {
-					ns = append(ns, strings.TrimRight(e, "\x00"))
+		func() {
+			defer k.Close()
+			for _, keyName := range []string{"NameServer", "ProfileNameServer"} {
+				value, _, err := k.GetStringValue(keyName)
+				if err != nil && !errors.Is(err, registry.ErrNotExist) {
+					mainLog.Load().Debug().Err(err).Msgf("error reading %s registry key", keyName)
+					continue
+				}
+				if len(value) > 0 {
+					mainLog.Load().Debug().Msgf("found static DNS for interface %q: %s", iface.Name, value)
+					parsed := parseDNSServers(value)
+					ns = append(ns, parsed...)
 				}
 			}
-		}
+		}()
+	}
+	if len(ns) == 0 {
+		mainLog.Load().Debug().Msgf("no static DNS values found for interface %q", iface.Name)
 	}
 	return ns, nil
 }

+// parseDNSServers splits a DNS server string that may be comma- or space-separated,
+// and trims any extraneous whitespace or null characters.
+func parseDNSServers(val string) []string {
+	fields := strings.FieldsFunc(val, func(r rune) bool {
+		return r == ' ' || r == ','
+	})
+	var servers []string
+	for _, f := range fields {
+		trimmed := strings.TrimSpace(f)
+		if len(trimmed) > 0 {
+			servers = append(servers, trimmed)
+		}
+	}
+	return servers
+}
+
 // addDnsServerForwarders adds given nameservers to DNS server forwarders list,
 // and also removing old forwarders if provided.
 func addDnsServerForwarders(nameservers, old []string) error {