Do not store Merkle branches in the wallet.

Assume that when a wallet transaction has a valid block hash and transaction position
in it, the transaction is actually there. We're already trusting wallet data in a
much more fundamental way anyway.

To prevent backward compatibility issues, a new record is used for storing the
block locator in the wallet. Old wallets will see a wallet file synchronized up
to the genesis block, and rescan automatically.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/wallet/walletdb.cpp b/src/wallet/walletdb.cpp
index c1eb184581..0624e442d1 100644
--- a/src/wallet/walletdb.cpp
+++ b/src/wallet/walletdb.cpp
@@ -131,12 +131,14 @@ bool CWalletDB::EraseWatchOnly(const CScript &dest)
 bool CWalletDB::WriteBestBlock(const CBlockLocator& locator)
 {
     nWalletDBUpdated++;
-    return Write(std::string("bestblock"), locator);
+    Write(std::string("bestblock"), CBlockLocator()); // Write empty block locator so versions that require a merkle branch automatically rescan
+    return Write(std::string("bestblock_nomerkle"), locator);
 }
 
 bool CWalletDB::ReadBestBlock(CBlockLocator& locator)
 {
-    return Read(std::string("bestblock"), locator);
+    if (Read(std::string("bestblock"), locator) && !locator.vHave.empty()) return true;
+    return Read(std::string("bestblock_nomerkle"), locator);
 }
 
 bool CWalletDB::WriteOrderPosNext(int64_t nOrderPosNext)