client/eth: implement Exists

Exists works by trying to load the keystore and checking for > 1
wallets. Remove unused "appdir" setting from custom config. Just use
CreateWalletParams.DataDir.

client/asset/eth/config.go

@@ -15,7 +15,6 @@ import (
 
 // Config holds the parameters needed to initialize an ETH wallet.
 type Config struct {
-	AppDir         string  `ini:"appdir"`
 	NodeListenAddr string  `ini:"nodelistenaddr"`
 	GasFee         float64 `ini:"gasfee"`
 }

client/asset/eth/eth.go

@@ -28,6 +28,7 @@ import (
 	"github.com/decred/dcrd/hdkeychain/v3"
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/accounts/keystore"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -44,6 +45,8 @@ const (
 	defaultGasFee       = 82  // gwei
 	defaultGasFeeLimit  = 200 // gwei
 	defaultSendGasLimit = 21_000
+
+	walletTypeGeth = "geth"
 )
 
 var (
@@ -61,20 +64,14 @@ var (
 				"wallet.  Units: gwei / gas",
 			DefaultValue: defaultGasFeeLimit,
 		},
-		{
-			Key:          "appdir",
-			DisplayName:  "DCR Dex Ethereum directory location.",
-			Description:  "Location of the ethereum client data. This SHOULD NOT be a directory used by other ethereum applications. The default is recommended.",
-			DefaultValue: defaultAppDir,
-		},
 	}
 	// WalletInfo defines some general information about a Ethereum wallet.
 	WalletInfo = &asset.WalletInfo{
 		Name:     "Ethereum",
 		UnitInfo: dexeth.UnitInfo,
 		AvailableWallets: []*asset.WalletDefinition{
 			{
-				Type:              "geth",
+				Type:              walletTypeGeth,
 				Tab:               "Internal",
 				Description:       "Use the built-in DEX wallet with snap sync",
 				ConfigOpts:        configOpts,
@@ -125,7 +122,12 @@ func (d *Driver) Info() *asset.WalletInfo {
 
 // Exists checks the existence of the wallet.
 func (d *Driver) Exists(walletType, dataDir string, settings map[string]string, net dex.Network) (bool, error) {
-	return false, errors.New("unimplemented")
+	if walletType != walletTypeGeth {
+		return false, fmt.Errorf("wallet type %q unrecognized", walletType)
+	}
+	keyStoreDir := filepath.Join(getWalletDir(dataDir, net), "keystore")
+	ks := keystore.NewKeyStore(keyStoreDir, keystore.LightScryptN, keystore.LightScryptP)
+	return len(ks.Wallets()) > 0, nil
 }
 
 func (d *Driver) Create(params *asset.CreateWalletParams) error {
@@ -195,6 +197,9 @@ func (*ExchangeWallet) Info() *asset.WalletInfo {
 // CreateWallet creates a new internal ETH wallet and stores the private key
 // derived from the wallet seed.
 func CreateWallet(createWalletParams *asset.CreateWalletParams) error {
+	if createWalletParams.Type != walletTypeGeth {
+		return fmt.Errorf("wallet type %q unrecognized", createWalletParams.Type)
+	}
 	walletDir := getWalletDir(createWalletParams.DataDir, createWalletParams.Net)
 	node, err := prepareNode(&nodeConfig{
 		net:    createWalletParams.Net,

client/asset/eth/eth_test.go

@@ -15,6 +15,7 @@ import (
 	"fmt"
 	"math/big"
 	"math/rand"
+	"os"
 	"strings"
 	"testing"
 	"time"
@@ -1742,6 +1743,51 @@ func TestSwapConfirmation(t *testing.T) {
 	checkResult(false, 1, true)
 }
 
+func TestDriverExists(t *testing.T) {
+	drv := &Driver{}
+	tmpDir, _ := os.MkdirTemp("", "")
+	defer os.RemoveAll(tmpDir)
+
+	settings := map[string]string{}
+
+	// no wallet
+	exists, err := drv.Exists(walletTypeGeth, tmpDir, settings, dex.Simnet)
+	if err != nil {
+		t.Fatalf("Exists error for no geth wallet: %v", err)
+	}
+	if exists {
+		t.Fatalf("Uninitiated wallet exists")
+	}
+
+	// Create the wallet.
+	err = CreateWallet(&asset.CreateWalletParams{
+		Type:     walletTypeGeth,
+		Seed:     encode.RandomBytes(32),
+		Pass:     encode.RandomBytes(32),
+		Settings: settings,
+		DataDir:  tmpDir,
+		Net:      dex.Simnet,
+		Logger:   tLogger,
+	})
+	if err != nil {
+		t.Fatalf("CreateWallet error: %v", err)
+	}
+
+	// exists
+	exists, err = drv.Exists(walletTypeGeth, tmpDir, settings, dex.Simnet)
+	if err != nil {
+		t.Fatalf("Exists error for existent geth wallet: %v", err)
+	}
+	if !exists {
+		t.Fatalf("Initiated wallet doesn't exist")
+	}
+
+	// Wrong wallet type
+	if _, err := drv.Exists("not-geth", tmpDir, settings, dex.Simnet); err == nil {
+		t.Fatalf("no error for unknown wallet type")
+	}
+}
+
 func TestLocktimeExpired(t *testing.T) {
 	var secretHash [32]byte
 	copy(secretHash[:], encode.RandomBytes(32))

client/asset/eth/node.go

@@ -140,7 +140,12 @@ func SetSimnetGenesis(sng string) {
 
 // prepareNode sets up a geth node, but does not start it.
 func prepareNode(cfg *nodeConfig) (*node.Node, error) {
-	stackConf := &node.Config{DataDir: cfg.appDir}
+	stackConf := &node.Config{
+		DataDir: cfg.appDir,
+		// KeyStoreDir is set the same as the geth default, but we rely on this
+		// location for Exists, so protect against future geth changes.
+		KeyStoreDir: filepath.Join(cfg.appDir, "keystore"),
+	}
 
 	stackConf.Logger = &ethLogger{dl: cfg.logger}
 

client/asset/eth/nodeclient_harness_test.go

@@ -217,12 +217,12 @@ func TestMain(m *testing.M) {
 
 func setupWallet(walletDir, seed, listenAddress string) error {
 	settings := map[string]string{
-		"appdir":         walletDir,
 		"nodelistenaddr": listenAddress,
 	}
 	seedB, _ := hex.DecodeString(seed)
 	walletPass, _ := hex.DecodeString(pw)
 	createWalletParams := asset.CreateWalletParams{
+		Type:     walletTypeGeth,
 		Seed:     seedB,
 		Pass:     walletPass,
 		Settings: settings,