From d29feaef79587092b89e8efaa2221620b5c08683 Mon Sep 17 00:00:00 2001
From: Andrey Bobelev <andrey@bobelev.com>
Date: Wed, 14 May 2025 15:24:40 +0300
Subject: [PATCH] chore(derp): allow nil regions in DERPMaps

Previously, nil regions were not properly handled. This change allows users to disable regions in DERPMaps.

Particularly useful to disable some official regions.
---
 hscontrol/derp/derp.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hscontrol/derp/derp.go b/hscontrol/derp/derp.go
index 839de9b5..479bfe5c 100644
--- a/hscontrol/derp/derp.go
+++ b/hscontrol/derp/derp.go
@@ -82,6 +82,12 @@ func mergeDERPMaps(derpMaps []*tailcfg.DERPMap) *tailcfg.DERPMap {
 		maps.Copy(result.Regions, derpMap.Regions)
 	}
 
+	for id, region := range result.Regions {
+		if region == nil {
+			delete(result.Regions, id)
+		}
+	}
+
 	return &result
 }