lnwallet: add basic tests for cooperative channel closure

This commit adds a basic test for cooperative channel closure. The
current test ensures correctness of the cooperative closure procedure
initiated by either the channel initiator, or the channel responder.

htlcswitch.go

@@ -173,7 +173,7 @@ out:
 					continue
 				}
 
-				hswcLog.Tracef("Sending %v to %x", amt, dest)
+				hswcLog.Tracef("Sending %v to %x", amt, dest[:])
 
 				// TODO(roasbeef): peer downstream should set chanPoint
 				wireMsg.ChannelPoint = link.chanPoint

lnwallet/channel.go

@@ -1275,7 +1275,7 @@ func (lc *LightningChannel) ForceClose() error {
 // settle any inflight.
 func (lc *LightningChannel) InitCooperativeClose() ([]byte, *wire.ShaHash, error) {
 	lc.Lock()
-	defer lc.Unlock() // TODO(roasbeef): coarser graiend locking
+	defer lc.Unlock()
 
 	// If we're already closing the channel, then ignore this request.
 	if lc.status == channelClosing || lc.status == channelClosed {
@@ -1317,7 +1317,7 @@ func (lc *LightningChannel) InitCooperativeClose() ([]byte, *wire.ShaHash, error
 // a signed+valid closure transaction to the network.
 func (lc *LightningChannel) CompleteCooperativeClose(remoteSig []byte) (*wire.MsgTx, error) {
 	lc.Lock()
-	defer lc.Unlock() // TODO(roasbeef): coarser graiend locking
+	defer lc.Unlock()
 
 	// If we're already closing the channel, then ignore this request.
 	if lc.status == channelClosing || lc.status == channelClosed {
@@ -1339,9 +1339,9 @@ func (lc *LightningChannel) CompleteCooperativeClose(remoteSig []byte) (*wire.Ms
 	// the 2-of-2 multi-sig needed to redeem the funding output.
 	redeemScript := lc.channelState.FundingRedeemScript
 	hashCache := txscript.NewTxSigHashes(closeTx)
+	capacity := int64(lc.channelState.Capacity)
 	closeSig, err := txscript.RawTxInWitnessSignature(closeTx,
-		hashCache, 0, int64(lc.channelState.Capacity),
-		redeemScript, txscript.SigHashAll,
+		hashCache, 0, capacity, redeemScript, txscript.SigHashAll,
 		lc.channelState.OurMultiSigKey)
 	if err != nil {
 		return nil, err
@@ -1355,7 +1355,16 @@ func (lc *LightningChannel) CompleteCooperativeClose(remoteSig []byte) (*wire.Ms
 		theirKey, remoteSig)
 	closeTx.TxIn[0].Witness = witness
 
-	// TODO(roasbeef): VALIDATE
+	// Validate the finalized transaction to ensure the output script is
+	// properly met, and that the remote peer supplied a valid signature.
+	vm, err := txscript.NewEngine(lc.fundingP2WSH, closeTx, 0,
+		txscript.StandardVerifyFlags, nil, hashCache, capacity)
+	if err != nil {
+		return nil, err
+	}
+	if err := vm.Execute(); err != nil {
+		return nil, err
+	}
 
 	return closeTx, nil
 }

lnwallet/channel_test.go

@@ -442,5 +442,46 @@ func TestSimpleAddSettleWorkflow(t *testing.T) {
 }
 
 func TestCooperativeChannelClosure(t *testing.T) {
-	// * add validation of their sig
+	// Create a test channel which will be used for the duration of this
+	// unittest. The channel will be funded evenly with Alice having 5 BTC,
+	// and Bob having 5 BTC.
+	aliceChannel, bobChannel, cleanUp, err := createTestChannels()
+	if err != nil {
+		t.Fatalf("unable to create test channels: %v", err)
+	}
+	defer cleanUp()
+
+	// First we test the channel initiator requesting a cooperative close.
+	sig, txid, err := aliceChannel.InitCooperativeClose()
+	if err != nil {
+		t.Fatalf("unable to initiate alice cooperative close: %v", err)
+	}
+	closeTx, err := bobChannel.CompleteCooperativeClose(sig)
+	if err != nil {
+		t.Fatalf("unable to complete alice cooperative close: %v", err)
+	}
+	bobCloseSha := closeTx.TxSha()
+	if !bobCloseSha.IsEqual(txid) {
+		t.Fatalf("alice's transactions doesn't match: %x vs %x",
+			bobCloseSha[:], txid[:])
+	}
+
+	aliceChannel.status = channelOpen
+	bobChannel.status = channelOpen
+
+	// Next we test the channel recipient requesting a cooperative closure.
+	// First we test the channel initiator requesting a cooperative close.
+	sig, txid, err = bobChannel.InitCooperativeClose()
+	if err != nil {
+		t.Fatalf("unable to initiate bob cooperative close: %v", err)
+	}
+	closeTx, err = aliceChannel.CompleteCooperativeClose(sig)
+	if err != nil {
+		t.Fatalf("unable to complete bob cooperative close: %v", err)
+	}
+	aliceCloseSha := closeTx.TxSha()
+	if !aliceCloseSha.IsEqual(txid) {
+		t.Fatalf("bob's closure transactions don't match: %x vs %x",
+			aliceCloseSha[:], txid[:])
+	}
 }

server.go

@@ -228,7 +228,7 @@ type openChanResp struct {
 	chanPoint *wire.OutPoint
 }
 
-// peerManager handles any requests to modify the server's internal state of
+// queryHandler handles any requests to modify the server's internal state of
 // all active peers, or query/mutate the server's global state. Additionally,
 // any queries directed at peers will be handled by this goroutine.
 //