wallet: fix another facet of "did I get some monero" information leak

We get new pool txes before processing any tx, pool or not.
This ensures that if we're asked for a password, this does not
cause a measurable delay in the txpool query after the last
block query.

src/simplewallet/simplewallet.cpp

@@ -8356,7 +8356,11 @@ bool simple_wallet::get_transfers(std::vector<std::string>& local_args, std::vec
       m_in_manual_refresh.store(true, std::memory_order_relaxed);
       epee::misc_utils::auto_scope_leave_caller scope_exit_handler = epee::misc_utils::create_scope_leave_handler([&](){m_in_manual_refresh.store(false, std::memory_order_relaxed);});
 
-      m_wallet->update_pool_state();
+      std::vector<std::pair<cryptonote::transaction, bool>> process_txs;
+      m_wallet->update_pool_state(process_txs);
+      if (!process_txs.empty())
+        m_wallet->process_pool_state(process_txs);
+
       std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> payments;
       m_wallet->get_unconfirmed_payments(payments, m_current_subaddress_account, subaddr_indices);
       for (std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>>::const_iterator i = payments.begin(); i != payments.end(); ++i) {
@@ -10002,7 +10006,11 @@ bool simple_wallet::show_transfer(const std::vector<std::string> &args)
 
   try
   {
-    m_wallet->update_pool_state();
+    std::vector<std::pair<cryptonote::transaction, bool>> process_txs;
+    m_wallet->update_pool_state(process_txs);
+    if (!process_txs.empty())
+      m_wallet->process_pool_state(process_txs);
+
     std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> pool_payments;
     m_wallet->get_unconfirmed_payments(pool_payments, m_current_subaddress_account);
     for (std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>>::const_iterator i = pool_payments.begin(); i != pool_payments.end(); ++i) {

src/wallet/wallet2.cpp

@@ -2829,7 +2829,7 @@ void wallet2::remove_obsolete_pool_txs(const std::vector<crypto::hash> &tx_hashe
 }
 
 //----------------------------------------------------------------------------------------------------
-void wallet2::update_pool_state(bool refreshed)
+void wallet2::update_pool_state(std::vector<std::pair<cryptonote::transaction, bool>> &process_txs, bool refreshed)
 {
   MTRACE("update_pool_state start");
 
@@ -3019,13 +3019,7 @@ void wallet2::update_pool_state(bool refreshed)
                     [tx_hash](const std::pair<crypto::hash, bool> &e) { return e.first == tx_hash; });
                 if (i != txids.end())
                 {
-                  process_new_transaction(tx_hash, tx, std::vector<uint64_t>(), 0, 0, time(NULL), false, true, tx_entry.double_spend_seen, {});
-                  m_scanned_pool_txs[0].insert(tx_hash);
-                  if (m_scanned_pool_txs[0].size() > 5000)
-                  {
-                    std::swap(m_scanned_pool_txs[0], m_scanned_pool_txs[1]);
-                    m_scanned_pool_txs[0].clear();
-                  }
+                  process_txs.push_back(std::make_pair(tx, tx_entry.double_spend_seen));
                 }
                 else
                 {
@@ -3056,6 +3050,24 @@ void wallet2::update_pool_state(bool refreshed)
   MTRACE("update_pool_state end");
 }
 //----------------------------------------------------------------------------------------------------
+void wallet2::process_pool_state(const std::vector<std::pair<cryptonote::transaction, bool>> &txs)
+{
+  const time_t now = time(NULL);
+  for (const auto &e: txs)
+  {
+    const cryptonote::transaction &tx = e.first;
+    const bool double_spend_seen = e.second;
+    const crypto::hash tx_hash = get_transaction_hash(tx);
+    process_new_transaction(tx_hash, tx, std::vector<uint64_t>(), 0, 0, now, false, true, double_spend_seen, {});
+    m_scanned_pool_txs[0].insert(tx_hash);
+    if (m_scanned_pool_txs[0].size() > 5000)
+    {
+      std::swap(m_scanned_pool_txs[0], m_scanned_pool_txs[1]);
+      m_scanned_pool_txs[0].clear();
+    }
+  }
+}
+//----------------------------------------------------------------------------------------------------
 void wallet2::fast_refresh(uint64_t stop_height, uint64_t &blocks_start_height, std::list<crypto::hash> &short_chain_history, bool force)
 {
   std::vector<crypto::hash> hashes;
@@ -3259,6 +3271,14 @@ void wallet2::refresh(bool trusted_daemon, uint64_t start_height, uint64_t & blo
   });
 
   auto scope_exit_handler_hwdev = epee::misc_utils::create_scope_leave_handler([&](){hwdev.computing_key_images(false);});
+
+  // get updated pool state first, but do not process those txes just yet,
+  // since that might cause a password prompt, which would introduce a data
+  // leak allowing a passive adversary with traffic analysis capability to
+  // infer when we get an incoming output
+  std::vector<std::pair<cryptonote::transaction, bool>> process_pool_txs;
+  update_pool_state(process_pool_txs, refreshed);
+
   bool first = true, last = false;
   while(m_run.load(std::memory_order_relaxed))
   {
@@ -3389,8 +3409,8 @@ void wallet2::refresh(bool trusted_daemon, uint64_t start_height, uint64_t & blo
   try
   {
     // If stop() is called we don't need to check pending transactions
-    if (check_pool && m_run.load(std::memory_order_relaxed))
-      update_pool_state(refreshed);
+    if (check_pool && m_run.load(std::memory_order_relaxed) && !process_pool_txs.empty())
+      process_pool_state(process_pool_txs);
   }
   catch (...)
   {

src/wallet/wallet2.h

@@ -1219,7 +1219,8 @@ private:
     bool import_key_images(signed_tx_set & signed_tx, size_t offset=0, bool only_selected_transfers=false);
     crypto::public_key get_tx_pub_key_from_received_outs(const tools::wallet2::transfer_details &td) const;
 
-    void update_pool_state(bool refreshed = false);
+    void update_pool_state(std::vector<std::pair<cryptonote::transaction, bool>> &process_txs, bool refreshed = false);
+    void process_pool_state(const std::vector<std::pair<cryptonote::transaction, bool>> &txs);
     void remove_obsolete_pool_txs(const std::vector<crypto::hash> &tx_hashes);
 
     std::string encrypt(const char *plaintext, size_t len, const crypto::secret_key &skey, bool authenticated = true) const;

src/wallet/wallet_rpc_server.cpp

@@ -2438,7 +2438,10 @@ namespace tools
 
     if (req.pool)
     {
-      m_wallet->update_pool_state();
+      std::vector<std::pair<cryptonote::transaction, bool>> process_txs;
+      m_wallet->update_pool_state(process_txs);
+      if (!process_txs.empty())
+        m_wallet->process_pool_state(process_txs);
 
       std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> payments;
       m_wallet->get_unconfirmed_payments(payments, account_index, subaddr_indices);
@@ -2518,7 +2521,10 @@ namespace tools
       }
     }
 
-    m_wallet->update_pool_state();
+    std::vector<std::pair<cryptonote::transaction, bool>> process_txs;
+    m_wallet->update_pool_state(process_txs);
+    if (!process_txs.empty())
+      m_wallet->process_pool_state(process_txs);
 
     std::list<std::pair<crypto::hash, tools::wallet2::pool_payment_details>> pool_payments;
     m_wallet->get_unconfirmed_payments(pool_payments, req.account_index);