wallet2: fix rescanning tx via scan_tx

- Detach & re-process txs >= lowest scan height
- ensures that if a user calls scan_tx(tx1) after scanning tx2,
the wallet correctly processes tx1 and tx2
- if a user provides a tx with a height higher than the wallet's
last scanned height, the wallet will scan starting from that tx's
height
- scan_tx requires trusted daemon iff need to re-process existing
txs: in addition to querying a daemon for txids, if a user
provides a txid of a tx with height *lower* than any *already*
scanned txs in the wallet, then the wallet will also query the
daemon for all the *higher* txs as well. This is likely
unexpected behavior to a caller, and so to protect a caller from
revealing txid's to an untrusted daemon in an unexpected way,
require the daemon be trusted.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/wallet/api/wallet.cpp b/src/wallet/api/wallet.cpp
index 085f4f9df..8d7364cba 100644
--- a/src/wallet/api/wallet.cpp
+++ b/src/wallet/api/wallet.cpp
@@ -1302,11 +1302,15 @@ bool WalletImpl::scanTransactions(const std::vector<std::string> &txids)
         }
         txids_u.insert(txid);
     }
-    std::vector<crypto::hash> txids_v(txids_u.begin(), txids_u.end());
 
     try
     {
-        m_wallet->scan_tx(txids_v);
+        m_wallet->scan_tx(txids_u);
+    }
+    catch (const tools::error::wont_reprocess_recent_txs_via_untrusted_daemon &e)
+    {
+        setStatusError(e.what());
+        return false;
     }
     catch (const std::exception &e)
     {