Enable and test SPV mode for remote wallets

.github/workflows/go.yml

@@ -53,7 +53,7 @@ jobs:
       fail-fast: false
       matrix:
         go: [1.14]
-        testsuite: ["unit-race", "itest-only", "itest-only walletimpl=remotewallet", "itest-only walletimpl=embedded_dcrw"]
+        testsuite: ["unit-race", "itest-only", "itest-only walletimpl=remotewallet", "itest-only walletimpl=embedded_dcrw", "itest-only walletimpl=remotewallet backend=spv"]
     steps:
       - name: Set up Go
         uses: actions/setup-go@v1

chainregistry.go

@@ -317,6 +317,13 @@ func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
 			srvrLog.Info("Using underlying wallet for chain operations")
 		}
 
+	case "spv":
+		// TODO: support SPV mode with an embedded wallet.
+		if conn == nil {
+			return nil, fmt.Errorf("SPV mode is not supported when " +
+				"using an embedded wallet. Use --node=dcrd or " +
+				"--node=dcrw")
+		}
 	default:
 		return nil, fmt.Errorf("unknown node type: %s",
 			cfg.Node)

config.go

@@ -238,7 +238,7 @@ type config struct {
 	BackupFilePath     string `long:"backupfilepath" description:"The target location of the channel backup file"`
 
 	ChainDir            string           `long:"chaindir" description:"The directory to store the chain's data within."`
-	Node                string           `long:"node" description:"The blockchain interface to use." choice:"dcrd" choice:"dcrw"`
+	Node                string           `long:"node" description:"The blockchain interface to use." choice:"dcrd" choice:"dcrw" choice:"spv"`
 	TestNet3            bool             `long:"testnet" description:"Use the test network"`
 	SimNet              bool             `long:"simnet" description:"Use the simulation test network"`
 	RegTest             bool             `long:"regtest" description:"Use the regression test network"`
@@ -676,7 +676,9 @@ func loadConfig() (*config, error) {
 				"credentials for dcrd: %v", err)
 			return nil, err
 		}
-
+	case "spv":
+		// In SPV mode we use the underlying wallet for chain
+		// operations.
 	default:
 		str := "%s: only dcrd mode supported for Decred at " +
 			"this time"

lntest/itest/lnd_test.go

@@ -2400,6 +2400,13 @@ func assertMinerBlockHeightDelta(t *harnessTest,
 func testOpenChannelAfterReorg(net *lntest.NetworkHarness, t *harnessTest) {
 	var ctxb = context.Background()
 
+	// Currently disabled due to
+	// https://github.com/decred/dcrwallet/issues/1710. Re-assess after
+	// that is fixed.
+	if net.BackendCfg.Name() == "spv" {
+		t.Skipf("Skipping for SPV for the moment")
+	}
+
 	// Set up a new miner that we can use to cause a reorg.
 	args := []string{"--rejectnonstd", "--txindex"}
 	tempMiner, err := testutils.NewSetupRPCTest(
@@ -8714,6 +8721,13 @@ func testRevokedCloseRetributionRemoteHodlSecondLevel(net *lntest.NetworkHarness
 	t *harnessTest) {
 	ctxb := context.Background()
 
+	// Currently disabled in SPV due to
+	// https://github.com/decred/dcrlnd/issues/96. Re-assess after that is
+	// fixed.
+	if net.BackendCfg.Name() == "spv" {
+		t.Skipf("Skipping for SPV for the moment")
+	}
+
 	const (
 		initialBalance = int64(dcrutil.AtomsPerCoin)
 		chanAmt        = defaultChanAmt

lntest/itest/onchain.go

@@ -24,8 +24,8 @@ import (
 func testCPFP(net *lntest.NetworkHarness, t *harnessTest) {
 	// Skip this test for neutrino, as it's not aware of mempool
 	// transactions.
-	if net.BackendCfg.Name() == "neutrino" {
-		t.Skipf("skipping reorg test for neutrino backend")
+	if net.BackendCfg.Name() == "spv" {
+		t.Skipf("skipping cpfp test for spv backend")
 	}
 
 	// We'll start the test by sending Alice some coins, which she'll use to

lntest/remotewallet.go → lntest/remotewallet-dcrw.go

@@ -1,4 +1,4 @@
-// +build remotewallet
+// +build remotewallet,!spv
 
 package lntest
 

lntest/remotewallet-spv.go

@@ -0,0 +1,11 @@
+// +build remotewallet,spv
+
+package lntest
+
+func useRemoteWallet() bool {
+	return true
+}
+
+func useDcrwNode() bool {
+	return false
+}

lntest/spv.go

@@ -0,0 +1,171 @@
+// +build spv
+
+package lntest
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"testing"
+
+	pb "decred.org/dcrwallet/rpc/walletrpc"
+	"github.com/decred/dcrd/chaincfg/v2"
+	"github.com/decred/dcrd/rpctest"
+	"github.com/decred/dcrlnd/internal/testutils"
+)
+
+// logDir is the name of the temporary log directory.
+const logDir = "./.backendlogs"
+
+// SpvBackendConfig is an implementation of the BackendConfig interface
+// backed by a btcd node.
+type SpvBackendConfig struct {
+	// connectAddr is the address that SPV clients may use to connect to
+	// this node via the p2p interface.
+	connectAddr string
+
+	// harness is this backend's node.
+	harness *rpctest.Harness
+
+	// miner is the backing miner used during tests.
+	miner *rpctest.Harness
+}
+
+// GenArgs returns the arguments needed to be passed to LND at startup for
+// using this node as a chain backend.
+func (b SpvBackendConfig) GenArgs() []string {
+	return []string{
+		"--node=spv",
+	}
+}
+
+func (b SpvBackendConfig) StartWalletSync(loader pb.WalletLoaderServiceClient, password []byte) error {
+	req := &pb.SpvSyncRequest{
+		SpvConnect:        []string{b.connectAddr},
+		DiscoverAccounts:  true,
+		PrivatePassphrase: password,
+	}
+
+	stream, err := loader.SpvSync(context.Background(), req)
+	if err != nil {
+		return err
+	}
+
+	syncDone := make(chan error)
+	go func() {
+		for {
+			resp, err := stream.Recv()
+			if err != nil {
+				syncDone <- err
+				return
+			}
+			if resp.Synced {
+				close(syncDone)
+				break
+			}
+		}
+
+		// After sync is complete, just drain the notifications until
+		// the connection is closed.
+		for {
+			_, err := stream.Recv()
+			if err != nil {
+				return
+			}
+		}
+	}()
+
+	return <-syncDone
+}
+
+// ConnectMiner connects the backend to the underlying miner.
+func (b SpvBackendConfig) ConnectMiner() error {
+	return rpctest.ConnectNode(b.harness, b.miner)
+}
+
+// DisconnectMiner disconnects the backend to the underlying miner.
+func (b SpvBackendConfig) DisconnectMiner() error {
+	return rpctest.RemoveNode(context.Background(), b.harness, b.miner)
+}
+
+// Name returns the name of the backend type.
+func (b SpvBackendConfig) Name() string {
+	return "spv"
+}
+
+func unsafeFindP2PAddr(miner, chainBackend *rpctest.Harness) (string, error) {
+	// This assumes the miner doesn't have any connections yet.
+	err := rpctest.ConnectNode(miner, chainBackend)
+	if err != nil {
+		return "", err
+	}
+
+	peers, err := miner.Node.GetPeerInfo(context.Background())
+	if err != nil {
+		return "", err
+	}
+
+	err = rpctest.RemoveNode(context.Background(), miner, chainBackend)
+	if err != nil {
+		return "", err
+	}
+
+	return peers[0].Addr, nil
+}
+
+// NewBackend starts a new rpctest.Harness and returns a SpvBackendConfig for
+// that node.
+func NewBackend(t *testing.T, miner *rpctest.Harness) (*SpvBackendConfig, func(), error) {
+	args := []string{
+		// rejectnonstd cannot be used in decred due to votes in simnet
+		// using a non-standard signature script.
+		//
+		// "--rejectnonstd",
+		"--txindex",
+		"--debuglevel=debug",
+		"--logdir=" + logDir,
+	}
+	netParams := chaincfg.SimNetParams()
+	chainBackend, err := testutils.NewSetupRPCTest(
+		t, 5, netParams, nil, args, false, 0,
+	)
+	if err != nil {
+		return nil, nil, fmt.Errorf("unable to create dcrd node: %v", err)
+	}
+
+	// FIXME: This is really brittle and needs to be fixed with a specific
+	// call in the upstream dcrd/rpctest package.
+	//
+	// Determine the p2p address by having the miner connect to this node
+	// and figuring out the address from the miner.
+	connectAddr, err := unsafeFindP2PAddr(miner, chainBackend)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	bd := &SpvBackendConfig{
+		connectAddr: connectAddr,
+		harness:     chainBackend,
+		miner:       miner,
+	}
+
+	// Connect this newly created node to the miner.
+	rpctest.ConnectNode(chainBackend, miner)
+
+	cleanUp := func() {
+		chainBackend.TearDown()
+
+		// After shutting down the chain backend, we'll make a copy of
+		// the log file before deleting the temporary log dir.
+		logFile := logDir + "/" + netParams.Name + "/dcrd.log"
+		err := CopyFile("./output_dcrd_chainbackend.log", logFile)
+		if err != nil {
+			fmt.Printf("unable to copy file: %v\n", err)
+		}
+		if err = os.RemoveAll(logDir); err != nil {
+			fmt.Printf("Cannot remove dir %s: %v\n", logDir, err)
+		}
+	}
+
+	return bd, cleanUp, nil
+}