lntest: define BackendCfg and btcd impl

BackendCfg is an interface that can be backed by different Bitcoin node
implementations. We currently use the btcdHarness as our chain backend.

lntest/btcd.go

@@ -0,0 +1,87 @@
+package lntest
+
+import (
+	"encoding/hex"
+	"fmt"
+	"os"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/btcsuite/btcd/integration/rpctest"
+	"github.com/btcsuite/btcd/rpcclient"
+)
+
+// logDir is the name of the temporary log directory.
+const logDir = "./.backendlogs"
+
+// BtcdBackendConfig is an implementation of the BackendConfig interface
+// backed by a btcd node.
+type BtcdBackendConfig struct {
+	// RPCConfig houses the connection config to the backing btcd instance.
+	RPCConfig rpcclient.ConnConfig
+
+	// P2PAddress is the p2p address of the btcd instance.
+	P2PAddress string
+}
+
+// GenArgs returns the arguments needed to be passed to LND at startup for
+// using this node as a chain backend.
+func (b BtcdBackendConfig) GenArgs() []string {
+	var args []string
+	encodedCert := hex.EncodeToString(b.RPCConfig.Certificates)
+	args = append(args, "--bitcoin.node=btcd")
+	args = append(args, fmt.Sprintf("--btcd.rpchost=%v", b.RPCConfig.Host))
+	args = append(args, fmt.Sprintf("--btcd.rpcuser=%v", b.RPCConfig.User))
+	args = append(args, fmt.Sprintf("--btcd.rpcpass=%v", b.RPCConfig.Pass))
+	args = append(args, fmt.Sprintf("--btcd.rawrpccert=%v", encodedCert))
+
+	return args
+}
+
+// P2PAddr returns the address of this node to be used when connection over the
+// Bitcoin P2P network.
+func (b BtcdBackendConfig) P2PAddr() string {
+	return b.P2PAddress
+}
+
+// NewBtcdBackend starts a new rpctest.Harness and returns a BtcdBackendConfig
+// for that node.
+func NewBtcdBackend() (*BtcdBackendConfig, func(), error) {
+	args := []string{
+		"--rejectnonstd",
+		"--txindex",
+		"--trickleinterval=100ms",
+		"--debuglevel=debug",
+		"--logdir=" + logDir,
+	}
+	netParams := &chaincfg.SimNetParams
+	chainBackend, err := rpctest.New(netParams, nil, args)
+	if err != nil {
+		return nil, nil, fmt.Errorf("unable to create btcd node: %v", err)
+	}
+
+	if err := chainBackend.SetUp(false, 0); err != nil {
+		return nil, nil, fmt.Errorf("unable to set up btcd backend: %v", err)
+	}
+
+	bd := &BtcdBackendConfig{
+		RPCConfig:  chainBackend.RPCConfig(),
+		P2PAddress: chainBackend.P2PAddress(),
+	}
+
+	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 + "/btcd.log"
+		err := CopyFile("./output_btcd_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
+}