Don't automatically restore saved DNS settings when switching networks

smol tweaks to nameserver test queries

fix restoreDNS errors

add some debugging information

fix wront type in log msg

set send logs command timeout to 5 mins

when the runningIface is no longer up, attempt to find a new interface

prefer default route, ignore non physical interfaces

prefer default route, ignore non physical interfaces

add max context timeout on performLeakingQuery with more debug logs

cmd/cli/prog.go

@@ -626,9 +626,31 @@ func (p *prog) setDNS() {
 		return
 	}
 	logger := mainLog.Load().With().Str("iface", p.runningIface).Logger()
-	netIface, err := netInterface(p.runningIface)
-	if err != nil {
-		logger.Error().Err(err).Msg("could not get interface")
+
+	const maxDNSRetryAttempts = 3
+	const retryDelay = 1 * time.Second
+	var netIface *net.Interface
+	var err error
+	for attempt := 1; attempt <= maxDNSRetryAttempts; attempt++ {
+		netIface, err = netInterface(p.runningIface)
+		if err == nil {
+			break
+		}
+		if attempt < maxDNSRetryAttempts {
+			// Try to find a different working interface
+			newIface := findWorkingInterface(p.runningIface)
+			if newIface != p.runningIface {
+				p.runningIface = newIface
+				logger = mainLog.Load().With().Str("iface", p.runningIface).Logger()
+				logger.Info().Msg("switched to new interface")
+				continue
+			}
+
+			logger.Warn().Err(err).Int("attempt", attempt).Msg("could not get interface, retrying...")
+			time.Sleep(retryDelay)
+			continue
+		}
+		logger.Error().Err(err).Msg("could not get interface after all attempts")
 		return
 	}
 	if err := setupNetworkManager(); err != nil {
@@ -766,6 +788,7 @@ func (p *prog) resetDNS() {
 		logger.Error().Err(err).Msg("could not get interface")
 		return
 	}
+
 	if err := restoreNetworkManager(); err != nil {
 		logger.Error().Err(err).Msg("could not restore NetworkManager")
 		return
@@ -781,6 +804,131 @@ func (p *prog) resetDNS() {
 	}
 }
 
+// findWorkingInterface looks for a network interface with a valid IP configuration
+func findWorkingInterface(currentIface string) string {
+	// Helper to check if IP is valid (not link-local)
+	isValidIP := func(ip net.IP) bool {
+		return ip != nil &&
+			!ip.IsLinkLocalUnicast() &&
+			!ip.IsLinkLocalMulticast() &&
+			!ip.IsLoopback() &&
+			!ip.IsUnspecified()
+	}
+
+	// Helper to check if interface has valid IP configuration
+	hasValidIPConfig := func(iface *net.Interface) bool {
+		if iface == nil || iface.Flags&net.FlagUp == 0 {
+			return false
+		}
+
+		addrs, err := iface.Addrs()
+		if err != nil {
+			mainLog.Load().Debug().
+				Str("interface", iface.Name).
+				Err(err).
+				Msg("failed to get interface addresses")
+			return false
+		}
+
+		for _, addr := range addrs {
+			// Check for IP network
+			if ipNet, ok := addr.(*net.IPNet); ok {
+				if isValidIP(ipNet.IP) {
+					return true
+				}
+			}
+		}
+		return false
+	}
+
+	// Get default route interface
+	defaultRoute, err := netmon.DefaultRoute()
+	if err != nil {
+		mainLog.Load().Debug().
+			Err(err).
+			Msg("failed to get default route")
+	} else {
+		mainLog.Load().Debug().
+			Str("default_route_iface", defaultRoute.InterfaceName).
+			Msg("found default route")
+	}
+
+	// Get all interfaces
+	ifaces, err := net.Interfaces()
+	if err != nil {
+		mainLog.Load().Error().Err(err).Msg("failed to list network interfaces")
+		return currentIface // Return current interface as fallback
+	}
+
+	var firstWorkingIface string
+	var currentIfaceValid bool
+
+	// Single pass through interfaces
+	for _, iface := range ifaces {
+		// Must be physical (has MAC address)
+		if len(iface.HardwareAddr) == 0 {
+			continue
+		}
+		// Skip interfaces that are:
+		// - Loopback
+		// - Not up
+		// - Point-to-point (like VPN tunnels)
+		if iface.Flags&net.FlagLoopback != 0 ||
+			iface.Flags&net.FlagUp == 0 ||
+			iface.Flags&net.FlagPointToPoint != 0 {
+			continue
+		}
+
+		if !hasValidIPConfig(&iface) {
+			continue
+		}
+
+		// Found working physical interface
+		if err == nil && defaultRoute.InterfaceName == iface.Name {
+			// Found interface with default route - use it immediately
+			mainLog.Load().Info().
+				Str("old_iface", currentIface).
+				Str("new_iface", iface.Name).
+				Msg("switching to interface with default route")
+			return iface.Name
+		}
+
+		// Keep track of first working interface as fallback
+		if firstWorkingIface == "" {
+			firstWorkingIface = iface.Name
+		}
+
+		// Check if this is our current interface
+		if iface.Name == currentIface {
+			currentIfaceValid = true
+		}
+	}
+
+	// Return interfaces in order of preference:
+	// 1. Current interface if it's still valid
+	if currentIfaceValid {
+		mainLog.Load().Debug().
+			Str("interface", currentIface).
+			Msg("keeping current interface")
+		return currentIface
+	}
+
+	// 2. First working interface found
+	if firstWorkingIface != "" {
+		mainLog.Load().Info().
+			Str("old_iface", currentIface).
+			Str("new_iface", firstWorkingIface).
+			Msg("switching to first working physical interface")
+		return firstWorkingIface
+	}
+
+	// 3. Fall back to current interface if nothing else works
+	mainLog.Load().Warn().
+		Str("current_iface", currentIface).
+		Msg("no working physical interface found, keeping current")
+	return currentIface
+}
+
 // leakOnUpstreamFailure reports whether ctrld should leak query to OS resolver when failed to connect all upstreams.
 func (p *prog) leakOnUpstreamFailure() bool {
 	if ptr := p.cfg.Service.LeakOnUpstreamFailure; ptr != nil {
@@ -1049,7 +1197,16 @@ func savedStaticDnsSettingsFilePath(iface *net.Interface) string {
 func savedStaticNameservers(iface *net.Interface) []string {
 	file := savedStaticDnsSettingsFilePath(iface)
 	if data, _ := os.ReadFile(file); len(data) > 0 {
-		return strings.Split(string(data), ",")
+		saveValues := strings.Split(string(data), ",")
+		returnValues := []string{}
+		// check each one, if its in loopback range, remove it
+		for _, v := range saveValues {
+			if net.ParseIP(v).IsLoopback() {
+				continue
+			}
+			returnValues = append(returnValues, v)
+		}
+		return returnValues
 	}
 	return nil
 }