From 6d9ad7fe5def7cc9ed8cadd2585fc914f351839e Mon Sep 17 00:00:00 2001
From: Andrey Bobelev <andrey@bobelev.com>
Date: Wed, 14 May 2025 15:04:31 +0300
Subject: [PATCH 1/2] chore(derp): prioritize loading DERP maps from URLs

This allows users to override default entries provided via URL
---
 hscontrol/derp/derp.go | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/hscontrol/derp/derp.go b/hscontrol/derp/derp.go
index 9d358598..8f2e0753 100644
--- a/hscontrol/derp/derp.go
+++ b/hscontrol/derp/derp.go
@@ -86,25 +86,6 @@ func GetDERPMap(cfg types.DERPConfig) *tailcfg.DERPMap {
 		derpMaps = append(derpMaps, cfg.DERPMap)
 	}
 
-	for _, path := range cfg.Paths {
-		log.Debug().
-			Str("func", "GetDERPMap").
-			Str("path", path).
-			Msg("Loading DERPMap from path")
-		derpMap, err := loadDERPMapFromPath(path)
-		if err != nil {
-			log.Error().
-				Str("func", "GetDERPMap").
-				Str("path", path).
-				Err(err).
-				Msg("Could not load DERP map from path")
-
-			break
-		}
-
-		derpMaps = append(derpMaps, derpMap)
-	}
-
 	for _, addr := range cfg.URLs {
 		derpMap, err := loadDERPMapFromURL(addr)
 		log.Debug().
@@ -124,6 +105,25 @@ func GetDERPMap(cfg types.DERPConfig) *tailcfg.DERPMap {
 		derpMaps = append(derpMaps, derpMap)
 	}
 
+	for _, path := range cfg.Paths {
+		log.Debug().
+			Str("func", "GetDERPMap").
+			Str("path", path).
+			Msg("Loading DERPMap from path")
+		derpMap, err := loadDERPMapFromPath(path)
+		if err != nil {
+			log.Error().
+				Str("func", "GetDERPMap").
+				Str("path", path).
+				Err(err).
+				Msg("Could not load DERP map from path")
+
+			break
+		}
+
+		derpMaps = append(derpMaps, derpMap)
+	}
+
 	derpMap := mergeDERPMaps(derpMaps)
 
 	log.Trace().Interface("derpMap", derpMap).Msg("DERPMap loaded")

From 7a2016ca62e4b1d28e4a341dda3563e3a0edddeb Mon Sep 17 00:00:00 2001
From: Andrey Bobelev <andrey@bobelev.com>
Date: Wed, 14 May 2025 15:24:40 +0300
Subject: [PATCH 2/2] 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, 5 insertions(+), 1 deletion(-)

diff --git a/hscontrol/derp/derp.go b/hscontrol/derp/derp.go
index 8f2e0753..95fdacc8 100644
--- a/hscontrol/derp/derp.go
+++ b/hscontrol/derp/derp.go
@@ -73,7 +73,11 @@ func mergeDERPMaps(derpMaps []*tailcfg.DERPMap) *tailcfg.DERPMap {
 
 	for _, derpMap := range derpMaps {
 		for id, region := range derpMap.Regions {
-			result.Regions[id] = region
+			if region == nil {
+				delete(result.Regions, id)
+			} else {
+				result.Regions[id] = region
+			}
 		}
 	}