lnwallet: initialize first 255 accounts

This fixes lightninglabs/loop#437 by adding all accounts that are used
in liquidity products such as Loop or Pool. Since both of these products
use key families below 255, we can get by with that number.
The alternative to creating way too many accounts (which increases the
default wallet size by ~250kB) would be to hard code the exact accounts
used by Loop (99) and Pool (210). But that sounds like a bad idea given
that there could always be more accounts being added to those (or other)
products. By making sure the first 255 accounts exist, we have a lot
more flexibility in those products for choosing key families.

lntest/itest/lnd_remote_signer_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/btcsuite/btcutil"
+	"github.com/btcsuite/btcutil/hdkeychain"
 	"github.com/btcsuite/btcwallet/waddrmgr"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnrpc"
@@ -39,76 +40,6 @@ var (
 		Xpub: "tpubDDWAWrSLRSFrG1KdqXMQQyTKYGSKLKaY7gxpvK7RdV3e3Dkhvu" +
 			"W2GgsFvsPN4RGmuoYtUgZ1LHZE8oftz7T4mzc1BxGt5rt8zJcVQi" +
 			"KTPPV",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyMultiSig),
-		Xpub: "tpubDDXFHr67Ro2tHKVWG2gNjjijKUH1Lyv5NKFYdJnuaLGVNBVwyV" +
-			"5AbykhR43iy8wYozEMbw2QfmAqZhb8gnuL5mm9sZh8YsR6FjGAbe" +
-			"w1xoT",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyRevocationBase),
-		Xpub: "tpubDDXFHr67Ro2tKkccDqNfDqZpd5wCs2n6XRV2Uh185DzCTbkDaE" +
-			"d9v7P837zZTYBNVfaRriuxgGVgxbGjDui4CKxyzBzwz4aAZxjn2P" +
-			"hNcQy",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyHtlcBase),
-		Xpub: "tpubDDXFHr67Ro2tNH4KH41i4oTsWfRjFigoH1Ee7urvHow51opH9x" +
-			"J7mu1qSPMPVtkVqQZ5tE4NTuFJPrbDqno7TQietyUDmPTwyVviJb" +
-			"GCwXk",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyPaymentBase),
-		Xpub: "tpubDDXFHr67Ro2tQj5Zvav2ALhkU6dRQAhEtNPnYJVBC8hs2U1A9e" +
-			"cqxRY3XTiJKBDD7e8tudhmTRs8aGWJAiAXJN5kXy3Hi6cmiwGWjX" +
-			"K5Cv5",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyDelayBase),
-		Xpub: "tpubDDXFHr67Ro2tSSR2LLBJtotxx2U45cuESLWKA72YT9td3SzVKH" +
-			"AptzDEx5chsUNZ4WRMY5h6HJxRSebjRatxQKX1uUsux1LvKS1wsf" +
-			"NJ2PH",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyRevocationRoot),
-		Xpub: "tpubDDXFHr67Ro2tTwzfWvNoMoPpZbxdMEfe1WhbXJxvXikGixPa4g" +
-			"gSRZeGx6T5yxVHTVT3rjVh35Veqsowj7emX8SZfXKDKDKcLduXCe" +
-			"WPUU3",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyNodeKey),
-		Xpub: "tpubDDXFHr67Ro2tYEDS2EByRedfsUoEwBtrzVbS1qdPrX6sAkUYGL" +
-			"rZWvMmQv8KZDZ4zd9r8WzM9bJ2nGp7XuNVC4w2EBtWg7i76gbrmu" +
-			"EWjQh",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyStaticBackup),
-		Xpub: "tpubDDXFHr67Ro2tYpwnFJEQaM8eAPM2UV5uY6gFgXeSzS5aC5T9Tf" +
-			"zXuawYKBbQMZJn8qHXLafY4tAutoda1aKP5h6Nbgy3swPbnhWbFj" +
-			"S5wnX",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyTowerSession),
-		Xpub: "tpubDDXFHr67Ro2tddKpAjUegXqt7EGxRXnHkeLbUkfuFMGbLJYgRp" +
-			"G4ew5pMmGg2nmcGmHFQ29w3juNhd8N5ZZ8HwJdymC4f5ukQLJ4yg" +
-			"9rEr3",
-	}, {
-		Purpose:  keychain.BIP0043Purpose,
-		CoinType: harnessNetParams.HDCoinType,
-		Account:  uint32(keychain.KeyFamilyTowerID),
-		Xpub: "tpubDDXFHr67Ro2tgE89V8ZdgMytC2Jq1iT9ttGhdzR1X7haQJNBmX" +
-			"t8kau6taC6DGASYzbrjmo9z9w6JQFcaLNqbhS2h2PVSzKf79j265" +
-			"Zi8hF",
 	}}
 )
 
@@ -181,7 +112,7 @@ func testRemoteSigner(net *lntest.NetworkHarness, t *harnessTest) {
 		password := []byte("itestpassword")
 		var (
 			signerNodePubKey  = nodePubKey
-			watchOnlyAccounts = accounts
+			watchOnlyAccounts = deriveCustomScopeAccounts(t.t)
 			signer            *lntest.HarnessNode
 			err               error
 		)
@@ -261,3 +192,55 @@ func testRemoteSigner(net *lntest.NetworkHarness, t *harnessTest) {
 		}
 	}
 }
+
+// deriveCustomScopeAccounts derives the first 255 default accounts of the custom lnd
+// internal key scope.
+func deriveCustomScopeAccounts(t *testing.T) []*lnrpc.WatchOnlyAccount {
+	allAccounts := make([]*lnrpc.WatchOnlyAccount, 0, 255+len(accounts))
+	allAccounts = append(allAccounts, accounts...)
+
+	extendedRootKey, err := hdkeychain.NewKeyFromString(rootKey)
+	require.NoError(t, err)
+
+	path := []uint32{
+		keychain.BIP0043Purpose + hdkeychain.HardenedKeyStart,
+		harnessNetParams.HDCoinType + hdkeychain.HardenedKeyStart,
+	}
+	coinTypeKey, err := derivePath(extendedRootKey, path)
+	require.NoError(t, err)
+	for idx := uint32(0); idx <= 255; idx++ {
+		accountPath := []uint32{idx + hdkeychain.HardenedKeyStart}
+		accountKey, err := derivePath(coinTypeKey, accountPath)
+		require.NoError(t, err)
+
+		accountXPub, err := accountKey.Neuter()
+		require.NoError(t, err)
+
+		allAccounts = append(allAccounts, &lnrpc.WatchOnlyAccount{
+			Purpose:  keychain.BIP0043Purpose,
+			CoinType: harnessNetParams.HDCoinType,
+			Account:  idx,
+			Xpub:     accountXPub.String(),
+		})
+	}
+
+	return allAccounts
+}
+
+// derivePath derives the given path from an extended key.
+func derivePath(key *hdkeychain.ExtendedKey, path []uint32) (
+	*hdkeychain.ExtendedKey, error) {
+
+	var (
+		currentKey = key
+		err        error
+	)
+	for _, pathPart := range path {
+		currentKey, err = currentKey.Derive(pathPart)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return currentKey, nil
+}

lnwallet/btcwallet/btcwallet.go

@@ -323,17 +323,13 @@ func (b *BtcWallet) Start() error {
 	err = walletdb.Update(b.db, func(tx walletdb.ReadWriteTx) error {
 		addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
 
-		for _, keyFam := range keychain.VersionZeroKeyFamilies {
-			// If this is the multi-sig key family, then we can
-			// return early as this is the default account that's
-			// created.
-			if keyFam == keychain.KeyFamilyMultiSig {
-				continue
-			}
-
+		// Generate all accounts that we could ever need. This includes
+		// all lnd key families as well as some key families used in
+		// external liquidity tools.
+		for keyFam := uint32(1); keyFam <= 255; keyFam++ {
 			// Otherwise, we'll check if the account already exists,
 			// if so, we can once again bail early.
-			_, err := scope.AccountName(addrmgrNs, uint32(keyFam))
+			_, err := scope.AccountName(addrmgrNs, keyFam)
 			if err == nil {
 				continue
 			}
@@ -341,7 +337,7 @@ func (b *BtcWallet) Start() error {
 			// If we reach this point, then the account hasn't yet
 			// been created, so we'll need to create it before we
 			// can proceed.
-			err = scope.NewRawAccount(addrmgrNs, uint32(keyFam))
+			err = scope.NewRawAccount(addrmgrNs, keyFam)
 			if err != nil {
 				return err
 			}