From 2d281b681e13d177995cf21a07c109287467d5e0 Mon Sep 17 00:00:00 2001
From: Marek Hajduczenia <mxhajduczenia@gmail.com>
Date: Wed, 15 Apr 2026 16:34:41 -0600
Subject: [PATCH] internal/tsutil: preserve advertised routes when toggling
 exit node

AdvertiseExitNode was creating a fresh empty Prefs struct, so toggling
the exit node switch sent an update that replaced all existing
advertised routes. Fetch current prefs first so subnet routes are
preserved, matching the pattern already used by AdvertiseRoutes.

Fixes #257
---
 internal/tsutil/client.go | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/internal/tsutil/client.go b/internal/tsutil/client.go
index 7ab90f4..dc9c0ac 100644
--- a/internal/tsutil/client.go
+++ b/internal/tsutil/client.go
@@ -117,11 +117,14 @@ func SetUseExitNode(ctx context.Context, use bool) error {
 // AdvertiseExitNode enables and disables exit node advertisement for
 // the current node.
 func AdvertiseExitNode(ctx context.Context, enable bool) error {
-	var prefs ipn.Prefs
+	prefs, err := Prefs(ctx)
+	if err != nil {
+		return fmt.Errorf("get prefs: %w", err)
+	}
 	prefs.SetAdvertiseExitNode(enable)
 
-	_, err := localClient.EditPrefs(ctx, &ipn.MaskedPrefs{
-		Prefs:              prefs,
+	_, err = localClient.EditPrefs(ctx, &ipn.MaskedPrefs{
+		Prefs:              *prefs,
 		AdvertiseRoutesSet: true,
 	})
 	if err != nil {