From 8c2717f96a54d1bf0d543a78afc766913a3cf9ac Mon Sep 17 00:00:00 2001
From: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com>
Date: Fri, 28 Feb 2025 13:51:07 -0500
Subject: [PATCH] ipn/ipnlocal: send vipServices info via c2n even it's
 incomplete (#15166)

This commit updates the logic of vipServicesFromPrefsLocked, so that it would return the vipServices list
even when service host is only advertising the service but not yet serving anything. This makes control
always get accurate state of service host in terms of serving a service.

Fixes tailscale/corp#26843

Signed-off-by: KevinLiang10 <37811973+KevinLiang10@users.noreply.github.com>
---
 ipn/ipnlocal/local.go | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/ipn/ipnlocal/local.go b/ipn/ipnlocal/local.go
index fec5c166f..4f94a55a1 100644
--- a/ipn/ipnlocal/local.go
+++ b/ipn/ipnlocal/local.go
@@ -8222,15 +8222,13 @@ func (b *LocalBackend) vipServiceHash(services []*tailcfg.VIPService) string {
 func (b *LocalBackend) vipServicesFromPrefsLocked(prefs ipn.PrefsView) []*tailcfg.VIPService {
 	// keyed by service name
 	var services map[tailcfg.ServiceName]*tailcfg.VIPService
-	if !b.serveConfig.Valid() {
-		return nil
-	}
-
-	for svc, config := range b.serveConfig.Services().All() {
-		mak.Set(&services, svc, &tailcfg.VIPService{
-			Name:  svc,
-			Ports: config.ServicePortRange(),
-		})
+	if b.serveConfig.Valid() {
+		for svc, config := range b.serveConfig.Services().All() {
+			mak.Set(&services, svc, &tailcfg.VIPService{
+				Name:  svc,
+				Ports: config.ServicePortRange(),
+			})
+		}
 	}
 
 	for _, s := range prefs.AdvertiseServices().All() {