From 269950891462565d1984cb69420e859f5451b037 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Mon, 17 Aug 2020 11:49:43 +0300
Subject: [PATCH] wallet: emit proper multisignature

In case when a signature needs to be added to multisig
we must first find corresponding signer, not append new witness.
---
 pkg/rpc/server/client_test.go |  9 +++++----
 pkg/wallet/account.go         | 12 ++++++++++--
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/pkg/rpc/server/client_test.go b/pkg/rpc/server/client_test.go
index 9bcff6063..dea10aabe 100644
--- a/pkg/rpc/server/client_test.go
+++ b/pkg/rpc/server/client_test.go
@@ -109,10 +109,10 @@ func TestAddNetworkFee(t *testing.T) {
 
 	t.Run("Multi", func(t *testing.T) {
 		tx := transaction.New(testchain.Network(), []byte{byte(opcode.PUSH1)}, 0)
-		accs := getAccounts(t, 3)
-		pubs := keys.PublicKeys{accs[1].PrivateKey().PublicKey(), accs[2].PrivateKey().PublicKey()}
-		require.NoError(t, accs[1].ConvertMultisig(1, pubs))
-		require.NoError(t, accs[2].ConvertMultisig(1, pubs))
+		accs := getAccounts(t, 4)
+		pubs := keys.PublicKeys{accs[1].PrivateKey().PublicKey(), accs[2].PrivateKey().PublicKey(), accs[3].PrivateKey().PublicKey()}
+		require.NoError(t, accs[1].ConvertMultisig(2, pubs))
+		require.NoError(t, accs[2].ConvertMultisig(2, pubs))
 		tx.Signers = []transaction.Signer{
 			{
 				Account: accs[0].PrivateKey().GetScriptHash(),
@@ -126,6 +126,7 @@ func TestAddNetworkFee(t *testing.T) {
 		require.NoError(t, c.AddNetworkFee(tx, 10, accs[0], accs[1]))
 		require.NoError(t, accs[0].SignTx(tx))
 		require.NoError(t, accs[1].SignTx(tx))
+		require.NoError(t, accs[2].SignTx(tx))
 		cFee, _ := core.CalculateNetworkFee(accs[0].Contract.Script)
 		cFeeM, _ := core.CalculateNetworkFee(accs[1].Contract.Script)
 		require.Equal(t, int64(io.GetVarSize(tx))*feePerByte+cFee+cFeeM+10, tx.NetworkFee)
diff --git a/pkg/wallet/account.go b/pkg/wallet/account.go
index 6ec829f21..393bf22a7 100644
--- a/pkg/wallet/account.go
+++ b/pkg/wallet/account.go
@@ -104,9 +104,17 @@ func (a *Account) SignTx(t *transaction.Transaction) error {
 	}
 	sign := a.privateKey.Sign(data)
 
+	verif := a.getVerificationScript()
+	invoc := append([]byte{byte(opcode.PUSHDATA1), 64}, sign...)
+	for i := range t.Scripts {
+		if bytes.Equal(t.Scripts[i].VerificationScript, verif) {
+			t.Scripts[i].InvocationScript = append(t.Scripts[i].InvocationScript, invoc...)
+			return nil
+		}
+	}
 	t.Scripts = append(t.Scripts, transaction.Witness{
-		InvocationScript:   append([]byte{byte(opcode.PUSHDATA1), 64}, sign...),
-		VerificationScript: a.getVerificationScript(),
+		InvocationScript:   invoc,
+		VerificationScript: verif,
 	})
 
 	return nil