server.go: replace call to removePeer with Disconnect in DisconnectPeer

docs/release-notes/release-notes-0.15.1.md

@@ -34,10 +34,14 @@
 * [Update the urfave/cli package](https://github.com/lightningnetwork/lnd/pull/6682) because
   of a flag parsing bug.
 
+* [DisconnectPeer no longer interferes with the peerTerminationWatcher. This previously caused
+  force closes.](https://github.com/lightningnetwork/lnd/pull/6655)
+
 # Contributors (Alphabetical Order)
 
 * Elle Mouton
 * ErikEk
+* Eugene Siegel
 * Oliver Gugger
 * Priyansh Rastogi
 * Yong Yu

lntest/itest/lnd_switch_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lntest"
 	"github.com/lightningnetwork/lnd/lntest/wait"
+	"github.com/stretchr/testify/require"
 )
 
 // testSwitchCircuitPersistence creates a multihop network to ensure the sender
@@ -451,13 +452,23 @@ func testSwitchOfflineDelivery(net *lntest.NetworkHarness, t *harnessTest) {
 		t.Fatalf("htlc mismatch: %v", predErr)
 	}
 
+	peerReq := &lnrpc.PeerEventSubscription{}
+	peerClient, err := dave.SubscribePeerEvents(ctxb, peerReq)
+	require.NoError(t.t, err)
+
 	// First, disconnect Dave and Alice so that their link is broken.
 	if err := net.DisconnectNodes(dave, net.Alice); err != nil {
 		t.Fatalf("unable to disconnect alice from dave: %v", err)
 	}
 
+	// Wait to receive the PEER_OFFLINE event before reconnecting them.
+	peerEvent, err := peerClient.Recv()
+	require.NoError(t.t, err)
+	require.Equal(t.t, lnrpc.PeerEvent_PEER_OFFLINE, peerEvent.GetType())
+
 	// Then, reconnect them to ensure Dave doesn't just fail back the htlc.
-	net.ConnectNodes(t.t, dave, net.Alice)
+	// We use EnsureConnected here in case they have already re-connected.
+	net.EnsureConnected(t.t, dave, net.Alice)
 
 	// Wait to ensure that the payment remain are not failed back after
 	// reconnecting. All node should report the number payments initiated
@@ -476,6 +487,16 @@ func testSwitchOfflineDelivery(net *lntest.NetworkHarness, t *harnessTest) {
 		t.Fatalf("unable to disconnect alice from dave: %v", err)
 	}
 
+	// Wait to receive the PEER_ONLINE and then the PEER_OFFLINE event
+	// before advancing.
+	peerEvent2, err := peerClient.Recv()
+	require.NoError(t.t, err)
+	require.Equal(t.t, lnrpc.PeerEvent_PEER_ONLINE, peerEvent2.GetType())
+
+	peerEvent3, err := peerClient.Recv()
+	require.NoError(t.t, err)
+	require.Equal(t.t, lnrpc.PeerEvent_PEER_OFFLINE, peerEvent3.GetType())
+
 	// Now restart carol without hodl mode, to settle back the outstanding
 	// payments.
 	carol.SetExtraArgs(nil)

server.go

@@ -4217,11 +4217,9 @@ func (s *server) DisconnectPeer(pubKey *btcec.PublicKey) error {
 	delete(s.persistentPeers, pubStr)
 	delete(s.persistentPeersBackoff, pubStr)
 
-	// Remove the current peer from the server's internal state and signal
-	// that the peer termination watcher does not need to execute for this
-	// peer.
-	s.removePeer(peer)
-	s.ignorePeerTermination[peer] = struct{}{}
+	// Remove the peer by calling Disconnect. Previously this was done with
+	// removePeer, which bypassed the peerTerminationWatcher.
+	peer.Disconnect(fmt.Errorf("server: DisconnectPeer called"))
 
 	return nil
 }