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, 3 insertions, 2 deletions

diff --git a/src/simplewallet/simplewallet.cpp b/src/simplewallet/simplewallet.cpp
index f59af575e..c5bed37df 100644
--- a/src/simplewallet/simplewallet.cpp
+++ b/src/simplewallet/simplewallet.cpp
@@ -3215,7 +3215,6 @@ bool simple_wallet::scan_tx(const std::vector<std::string> &args)
     }
     txids.insert(txid);
   }
-  std::vector<crypto::hash> txids_v(txids.begin(), txids.end());
 
   if (!m_wallet->is_trusted_daemon()) {
     message_writer(console_color_red, true) << tr("WARNING: this operation may reveal the txids to the remote node and affect your privacy");
@@ -3228,7 +3227,9 @@ bool simple_wallet::scan_tx(const std::vector<std::string> &args)
   LOCK_IDLE_SCOPE();
   m_in_manual_refresh.store(true);
   try {
-    m_wallet->scan_tx(txids_v);
+    m_wallet->scan_tx(txids);
+  } catch (const tools::error::wont_reprocess_recent_txs_via_untrusted_daemon &e) {
+    fail_msg_writer() << e.what() << ". Either connect to a trusted daemon by passing --trusted-daemon when starting the wallet, or use rescan_bc to rescan the chain.";
   } catch (const std::exception &e) {
     fail_msg_writer() << e.what();
   }