cmd/tsconnect, logpolicy: fixes for wasm_js.go

* updates to LocalBackend require metrics to be passed in which are now initialized
* os.MkdirTemp isn't supported in wasm/js so we simply return empty
  string for logger
* adds a UDP dialer which was missing and led to the dialer being
  incompletely initialized

Fixes #10454 and #8272

Signed-off-by: Christian <christian@devzero.io>

cmd/tsconnect/wasm/wasm_js.go

@@ -108,6 +108,7 @@ func newIPN(jsConfig js.Value) map[string]any {
 		SetSubsystem:  sys.Set,
 		ControlKnobs:  sys.ControlKnobs(),
 		HealthTracker: sys.HealthTracker(),
+		Metrics:       sys.UserMetricsRegistry(),
 	})
 	if err != nil {
 		log.Fatal(err)
@@ -128,6 +129,9 @@ func newIPN(jsConfig js.Value) map[string]any {
 	dialer.NetstackDialTCP = func(ctx context.Context, dst netip.AddrPort) (net.Conn, error) {
 		return ns.DialContextTCP(ctx, dst)
 	}
+	dialer.NetstackDialUDP = func(ctx context.Context, dst netip.AddrPort) (net.Conn, error) {
+		return ns.DialContextUDP(ctx, dst)
+	}
 	sys.NetstackRouter.Set(true)
 	sys.Tun.Get().Start()
 

logpolicy/logpolicy.go

@@ -230,6 +230,9 @@ func LogsDir(logf logger.Logf) string {
 			logf("logpolicy: using $STATE_DIRECTORY, %q", systemdStateDir)
 			return systemdStateDir
 		}
+	case "js":
+		logf("logpolicy: no logs directory in the browser")
+		return ""
 	}
 
 	// Default to e.g. /var/lib/tailscale or /var/db/tailscale on Unix.