ipn/ipnlocal/local.go

@@ -1867,7 +1867,7 @@ func (b *LocalBackend) setControlClientStatusLocked(c controlclient.Client, st c
 		}
 
 		b.e.SetNetworkMap(st.NetMap)
-		b.MagicConn().SetDERPMap(st.NetMap.DERPMap, false)
+		b.MagicConn().SetDERPMapWithoutReSTUN(st.NetMap.DERPMap)
 		if c == nil && st.NetMap.Cached && st.NetMap.SelfNode.Valid() {
 			// Loading from a cached netmap (c == nil means no live control
 			// client). Pre-seed the home DERP from the cached self node so
@@ -3445,7 +3445,7 @@ func (b *LocalBackend) DebugForceNetmapUpdate() {
 	nm := b.currentNode().NetMap()
 	b.e.SetNetworkMap(nm)
 	if nm != nil {
-		b.MagicConn().SetDERPMap(nm.DERPMap, true)
+		b.MagicConn().SetDERPMap(nm.DERPMap)
 	}
 	b.setNetMapLocked(nm)
 }
@@ -4903,7 +4903,7 @@ func (b *LocalBackend) setPrefsLocked(newp *ipn.Prefs) ipn.PrefsView {
 	}
 
 	if netMap != nil {
-		b.MagicConn().SetDERPMap(netMap.DERPMap, true)
+		b.MagicConn().SetDERPMap(netMap.DERPMap)
 	}
 
 	if !oldp.WantRunning() && newp.WantRunning && cc != nil {

wgengine/bench/wg.go

@@ -156,8 +156,8 @@ func setupWGTest(b *testing.B, logf logger.Logf, traf *TrafficGen, a1, a2 netip.
 	})
 
 	// Not using DERP in this test (for now?).
-	s1.MagicSock.Get().SetDERPMap(&tailcfg.DERPMap{}, true)
-	s2.MagicSock.Get().SetDERPMap(&tailcfg.DERPMap{}, true)
+	s1.MagicSock.Get().SetDERPMap(&tailcfg.DERPMap{})
+	s2.MagicSock.Get().SetDERPMap(&tailcfg.DERPMap{})
 
 	wait.Wait()
 }

wgengine/magicsock/derp.go

@@ -793,10 +793,23 @@ func (c *Conn) SetOnlyTCP443(v bool) {
 // SetDERPMap controls which (if any) DERP servers are used.
 // A nil value means to disable DERP; it's disabled by default.
 //
-// If doReStun is false, the post setting ReSTUN is not performed.
-// This flag is used for setting the map from a cache to make it possible to
-// also set the homeDERP from cache.
-func (c *Conn) SetDERPMap(dm *tailcfg.DERPMap, doReStun bool) {
+// SetDERPMap triggers a ReSTUN after updating the map. Callers that want to
+// set the map without triggering a ReSTUN should use [Conn.SetDERPMapWithoutReSTUN]
+// instead.
+func (c *Conn) SetDERPMap(dm *tailcfg.DERPMap) {
+	c.setDERPMap(dm, true)
+}
+
+// SetDERPMapWithoutReSTUN is like [Conn.SetDERPMap] but does not trigger a
+// ReSTUN after updating the map.
+//
+// It is used for setting the map from a cache, so the homeDERP can be set
+// from cache before any STUN happens.
+func (c *Conn) SetDERPMapWithoutReSTUN(dm *tailcfg.DERPMap) {
+	c.setDERPMap(dm, false)
+}
+
+func (c *Conn) setDERPMap(dm *tailcfg.DERPMap, doReStun bool) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 

wgengine/magicsock/derp_test.go

@@ -116,15 +116,15 @@ func TestSetDERPMapDoReStun(t *testing.T) {
 	// spawning updateEndpoints.
 	c.everHadKey = true
 
-	// Should not trigger a ReSTUN.
-	c.SetDERPMap(derpMap1, false)
+	// SetDERPMapWithoutReSTUN should not trigger a ReSTUN.
+	c.SetDERPMapWithoutReSTUN(derpMap1)
 	if reSTUNCalls != 0 {
-		t.Errorf("SetDERPMap(dm, doReStun=false): got %d ReSTUN calls, want 0", reSTUNCalls)
+		t.Errorf("SetDERPMapWithoutReSTUN: got %d ReSTUN calls, want 0", reSTUNCalls)
 	}
 
-	// doReStun=true: should trigger a ReSTUN.
-	c.SetDERPMap(derpMap2, true)
+	// SetDERPMap should trigger a ReSTUN.
+	c.SetDERPMap(derpMap2)
 	if reSTUNCalls != 1 {
-		t.Errorf("SetDERPMap(dm, doReStun=true): got %d ReSTUN calls, want 1", reSTUNCalls)
+		t.Errorf("SetDERPMap: got %d ReSTUN calls, want 1", reSTUNCalls)
 	}
 }

wgengine/magicsock/magicsock_test.go

@@ -203,7 +203,7 @@ func newMagicStackWithKey(t testing.TB, logf logger.Logf, ln nettype.PacketListe
 	if err != nil {
 		t.Fatalf("constructing magicsock: %v", err)
 	}
-	conn.SetDERPMap(derpMap, true)
+	conn.SetDERPMap(derpMap)
 	if err := conn.SetPrivateKey(privateKey); err != nil {
 		t.Fatalf("setting private key in magicsock: %v", err)
 	}
@@ -435,7 +435,7 @@ func TestNewConn(t *testing.T) {
 		t.Fatal("LocalPort returned 0")
 	}
 
-	conn.SetDERPMap(stuntest.DERPMapOf(stunAddr.String()), true)
+	conn.SetDERPMap(stuntest.DERPMapOf(stunAddr.String()))
 	conn.SetPrivateKey(key.NewNode())
 
 	go func() {
@@ -567,7 +567,7 @@ func TestDERPActiveFuncCalledAfterConnect(t *testing.T) {
 	}
 	defer conn.Close()
 
-	conn.SetDERPMap(derpMap, true)
+	conn.SetDERPMap(derpMap)
 	if err := conn.SetPrivateKey(key.NewNode()); err != nil {
 		t.Fatal(err)
 	}