Fixed change address (#22)

* implements change address

* fix

* fix

* test double call

* "already have address" ignored

* eth address as a constant

* btc address as a constant

---------

Co-authored-by: dpiatkivskyi <dmytro.piatkikvskyi@gmailcom>

run/btcwallet.go

@@ -13,6 +13,7 @@ import (
 	_ "net/http/pprof" // nolint:gosec
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 
 	"github.com/btcsuite/btcwallet/walletdb"
@@ -22,6 +23,8 @@ import (
 	"github.com/stroomnetwork/btcwallet/wallet"
 )
 
+const ethChangeAddr = "0x7b3f4f4b3cCf7f3fDf3f3f3f3f3f3f3f3f3f3f3f"
+
 var (
 	cfg *Config
 )
@@ -146,6 +149,12 @@ func doInit(signer frost.Signer, pk1, pk2 *btcec.PublicKey, bitcoindConfig *chai
 			return nil, err
 		}
 		w.AddressMapStorage = storage
+
+		changeAddressKey, err := w.GenerateKeyFromEthAddressAndImport(ethChangeAddr)
+		if err != nil && !strings.Contains(err.Error(), "already have address") {
+			return nil, fmt.Errorf("cannot import change address: %w", err)
+		}
+		w.ChangeAddressKey = changeAddressKey
 	}
 
 	// Add interrupt handlers to shut down the various process components

run/signer_with_wallet_example.go

@@ -14,6 +14,8 @@ import (
 	"time"
 )
 
+const btcAddr = "sb1pgdyx9mulkelunyg9rkj384sajls7xx2y3jlagdpup2l2wl6tppasvgf8z0"
+
 func Example() {
 	// Use all processor cores.
 	runtime.GOMAXPROCS(runtime.NumCPU())
@@ -39,7 +41,7 @@ func Example() {
 	time.Sleep(2 * time.Second)
 
 	w.Unlock([]byte("passphrase"), time.After(10*time.Minute))
-	_, err = w.ImportBtcAddressWithEthAddr("sb1pgdyx9mulkelunyg9rkj384sajls7xx2y3jlagdpup2l2wl6tppasvgf8z0", "0x7b3f4f4b3cCf7f3fDf3f3f3f3f3f3f3f3f3f3f3f")
+	_, err = w.GenerateAndImportKeyWithCheck(btcAddr, ethChangeAddr)
 
 	f := false
 	if f {

wallet/createtx.go

@@ -174,7 +174,7 @@ func (w *Wallet) txToOutputsWithRedemptionId(outputs []*wire.TxOut,
 	var tx *txauthor.AuthoredTx
 	err = walletdb.Update(w.db, func(dbtx walletdb.ReadWriteTx) error {
 		addrmgrNs, changeSource, err := w.addrMgrWithChangeSource(
-			dbtx, changeKeyScope, account,
+			dbtx, changeKeyScope, account, w.ChangeAddressKey,
 		)
 		if err != nil {
 			return err
@@ -471,13 +471,12 @@ func inputYieldsPositively(credit *wire.TxOut,
 // addresses will come from the specified key scope and account, unless a key
 // scope is not specified. In that case, change addresses will always come from
 // the P2WKH key scope.
-func (w *Wallet) addrMgrWithChangeSource(dbtx walletdb.ReadWriteTx,
-	changeKeyScope *waddrmgr.KeyScope, account uint32) (
-	walletdb.ReadWriteBucket, *txauthor.ChangeSource, error) {
+func (w *Wallet) addrMgrWithChangeSource(dbtx walletdb.ReadWriteTx, changeKeyScope *waddrmgr.KeyScope, account uint32,
+	changeAddress *btcec.PublicKey) (walletdb.ReadWriteBucket, *txauthor.ChangeSource, error) {
 
 	// Determine the address type for change addresses of the given
 	// account.
-	if changeKeyScope == nil {
+	if changeKeyScope == nil || changeAddress != nil {
 		changeKeyScope = &waddrmgr.KeyScopeBIP0086
 	}
 	addrType := waddrmgr.ScopeAddrMap[*changeKeyScope].InternalAddrType
@@ -521,6 +520,9 @@ func (w *Wallet) addrMgrWithChangeSource(dbtx walletdb.ReadWriteTx,
 			changeAddr btcutil.Address
 			err        error
 		)
+		if changeAddress != nil {
+			return txscript.PayToTaprootScript(changeAddress)
+		}
 		if account == waddrmgr.ImportedAddrAccount {
 			changeAddr, err = w.newChangeAddress(
 				addrmgrNs, 0, *changeKeyScope,

wallet/frost_signing_test.go

@@ -36,7 +36,7 @@ func TestFrostSigning(t *testing.T) {
 	err = w.Unlock([]byte("world"), time.After(10*time.Minute))
 	require.NoError(t, err)
 
-	pubKey, err := w.ImportBtcAddressWithEthAddr("", "0x7b3f4f4b3cCf7f3fDf3f3f3f3f3f3f3f3f3f3f3f")
+	pubKey, err := w.GenerateKeyFromEthAddressAndImport("0x7b3f4f4b3cCf7f3fDf3f3f3f3f3f3f3f3f3f3f3f")
 	require.NoError(t, err)
 
 	p2shAddr, err := txscript.PayToTaprootScript(pubKey)

wallet/import_btc_addr.go

@@ -9,32 +9,52 @@ import (
 	"github.com/stroomnetwork/frost/crypto"
 )
 
-func (w *Wallet) ImportBtcAddressWithEthAddr(btcAddr, ethAddr string) (*btcec.PublicKey, error) {
+func (w *Wallet) GenerateAndImportKeyWithCheck(btcAddr, ethAddr string) (*btcec.PublicKey, error) {
 
-	lc, err := w.lcFromEthAddr(ethAddr)
+	key, importedAddress, err := w.generateKeyFromEthAddressAndImport(ethAddr)
 	if err != nil {
 		return nil, err
 	}
 
+	if importedAddress != nil {
+		if btcAddr != "" && importedAddress.Address().EncodeAddress() != btcAddr {
+			return nil, fmt.Errorf("address mismatch: %s != %s",
+				importedAddress.Address().EncodeAddress(), btcAddr)
+		}
+
+	}
+
+	return key, nil
+}
+
+func (w *Wallet) GenerateKeyFromEthAddressAndImport(ethAddr string) (*btcec.PublicKey, error) {
+	key, _, err := w.generateKeyFromEthAddressAndImport(ethAddr)
+	return key, err
+}
+
+func (w *Wallet) generateKeyFromEthAddressAndImport(ethAddr string) (*btcec.PublicKey, waddrmgr.ManagedAddress, error) {
+
+	lc, err := w.lcFromEthAddr(ethAddr)
+	if err != nil {
+		return nil, nil, err
+	}
+
 	pubKey := lc.GetCombinedPubKey()
 	importedAddress, err := w.ImportPublicKeyReturnAddress(pubKey, waddrmgr.TaprootPubKey)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
-	if importedAddress != nil {
-		address := importedAddress.Address().EncodeAddress()
-		if btcAddr != "" && address != btcAddr {
-			return nil, fmt.Errorf("address mismatch: %s != %s",
-				importedAddress.Address().EncodeAddress(), btcAddr)
-		}
-		err := w.AddressMapStorage.SetEthAddress(address, ethAddr)
-		if err != nil {
-			return nil, err
-		}
+	if importedAddress == nil {
+		return nil, nil, fmt.Errorf("imported address is nil")
+	}
+
+	err = w.AddressMapStorage.SetEthAddress(importedAddress.Address().EncodeAddress(), ethAddr)
+	if err != nil {
+		return nil, nil, err
 	}
 
-	return pubKey, nil
+	return pubKey, importedAddress, nil
 }
 
 func (w *Wallet) lcFromEthAddr(ethAddrStr string) (*crypto.LinearCombination, error) {

wallet/psbt.go

@@ -170,9 +170,7 @@ func (w *Wallet) FundPsbt(packet *psbt.Packet, keyScope *waddrmgr.KeyScope,
 		// We also need a change source which needs to be able to insert
 		// a new change address into the database.
 		err = walletdb.Update(w.db, func(dbtx walletdb.ReadWriteTx) error {
-			_, changeSource, err := w.addrMgrWithChangeSource(
-				dbtx, opts.changeKeyScope, account,
-			)
+			_, changeSource, err := w.addrMgrWithChangeSource(dbtx, opts.changeKeyScope, account, nil)
 			if err != nil {
 				return err
 			}

wallet/wallet.go

@@ -126,10 +126,11 @@ type Wallet struct {
 	publicPassphrase []byte
 
 	// Data stores
-	db          walletdb.DB
-	Manager     *waddrmgr.Manager
-	TxStore     *wtxmgr.Store
-	FrostSigner frost.Signer
+	db               walletdb.DB
+	Manager          *waddrmgr.Manager
+	TxStore          *wtxmgr.Store
+	FrostSigner      frost.Signer
+	ChangeAddressKey *btcec.PublicKey
 
 	AddressMapStorage *AddressMapStorage
 	Pk1, Pk2          *btcec.PublicKey