use saved static nameservers stored for the default router interface when doing nameserver discovery

fix bad logger usages

patch darwin interface name

patch darwin interface name, debugging

make resetDNS check for static config on startup, optionally restoring static confiration as needed

fix netmon logging

cmd/cli/dns_proxy.go

@@ -20,7 +20,6 @@ import (
 	"golang.org/x/sync/errgroup"
 	"tailscale.com/net/netmon"
 	"tailscale.com/net/tsaddr"
-	"tailscale.com/types/logger"
 
 	"github.com/Control-D-Inc/ctrld"
 	"github.com/Control-D-Inc/ctrld/internal/controld"
@@ -1179,7 +1178,10 @@ func FlushDNSCache() error {
 
 // monitorNetworkChanges starts monitoring for network interface changes
 func (p *prog) monitorNetworkChanges(ctx context.Context) error {
-	mon, err := netmon.New(logger.WithPrefix(mainLog.Load().Printf, "netmon: "))
+	mon, err := netmon.New(func(format string, args ...any) {
+		// Always fetch the latest logger (and inject the prefix)
+		mainLog.Load().Printf("netmon: "+format, args...)
+	})
 	if err != nil {
 		return fmt.Errorf("creating network monitor: %w", err)
 	}
@@ -1457,7 +1459,10 @@ func (p *prog) handleRecovery(reason RecoveryReason) {
 	// Immediately remove our DNS settings from the interface.
 	// set recoveryRunning to true to prevent watchdogs from putting the listener back on the interface
 	p.recoveryRunning.Store(true)
-	p.resetDNS()
+	// we do not want to restore any static DNS settings
+	// we must try to get the DHCP values, any static DNS settings
+	// will be appended to nameservers from the saved interface values
+	p.resetDNS(false, false)
 
 	// For an OS failure, reinitialize OS resolver nameservers immediately.
 	if reason == RecoveryReasonOSFailure {