From 0ee018b40724342afa16dcf448024fb2e974a0e9 Mon Sep 17 00:00:00 2001
From: moneromooo-monero <moneromooo-monero@users.noreply.github.com>
Date: Sun, 2 Apr 2017 11:13:15 +0100
Subject: [PATCH] wallet2: do not go over the target tx size if many
 destinations

If using a large input and many destinations, the code would
generate as many outputs as it could using that input, even if
it would bring the resulting tx above the max tx size.
---
 src/wallet/wallet2.cpp | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index ed31f34a..941ee8af 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -4102,6 +4102,14 @@ static size_t estimate_rct_tx_size(int n_inputs, int mixin, int n_outputs)
   return size;
 }
 
+static size_t estimate_tx_size(bool use_rct, int n_inputs, int mixin, int n_outputs)
+{
+  if (use_rct)
+    return estimate_rct_tx_size(n_inputs, mixin, n_outputs + 1);
+  else
+    return n_inputs * (mixin+1) * APPROXIMATE_INPUT_BYTES;
+}
+
 std::vector<size_t> wallet2::pick_preferred_rct_inputs(uint64_t needed_money) const
 {
   std::vector<size_t> picks;
@@ -4409,7 +4417,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_2(std::vector<cryp
     }
     else
     {
-      while (!dsts.empty() && dsts[0].amount <= available_amount)
+      while (!dsts.empty() && dsts[0].amount <= available_amount && estimate_tx_size(use_rct, tx.selected_transfers.size(), fake_outs_count, tx.dsts.size()) < TX_SIZE_TARGET(upper_transaction_size_limit))
       {
         // we can fully pay that destination
         LOG_PRINT_L2("We can fully pay " << get_account_address_as_str(m_testnet, dsts[0].addr) <<
@@ -4420,7 +4428,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_2(std::vector<cryp
         pop_index(dsts, 0);
       }
 
-      if (available_amount > 0 && !dsts.empty()) {
+      if (available_amount > 0 && !dsts.empty() && estimate_tx_size(use_rct, tx.selected_transfers.size(), fake_outs_count, tx.dsts.size()) < TX_SIZE_TARGET(upper_transaction_size_limit)) {
         // we can partially fill that destination
         LOG_PRINT_L2("We can partially pay " << get_account_address_as_str(m_testnet, dsts[0].addr) <<
           " for " << print_money(available_amount) << "/" << print_money(dsts[0].amount));
@@ -4441,11 +4449,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_2(std::vector<cryp
     }
     else
     {
-      size_t estimated_rct_tx_size;
-      if (use_rct)
-        estimated_rct_tx_size = estimate_rct_tx_size(tx.selected_transfers.size(), fake_outs_count, tx.dsts.size() + 1);
-      else
-        estimated_rct_tx_size = tx.selected_transfers.size() * (fake_outs_count+1) * APPROXIMATE_INPUT_BYTES;
+      const size_t estimated_rct_tx_size = estimate_tx_size(use_rct, tx.selected_transfers.size(), fake_outs_count, tx.dsts.size());
       try_tx = dsts.empty() || (estimated_rct_tx_size >= TX_SIZE_TARGET(upper_transaction_size_limit));
     }
 
@@ -4633,11 +4637,7 @@ std::vector<wallet2::pending_tx> wallet2::create_transactions_from(const crypton
     // here, check if we need to sent tx and start a new one
     LOG_PRINT_L2("Considering whether to create a tx now, " << tx.selected_transfers.size() << " inputs, tx limit "
       << upper_transaction_size_limit);
-    size_t estimated_rct_tx_size;
-    if (use_rct)
-      estimated_rct_tx_size = estimate_rct_tx_size(tx.selected_transfers.size(), fake_outs_count, tx.dsts.size() + 1);
-    else
-      estimated_rct_tx_size = tx.selected_transfers.size() * (fake_outs_count+1) * APPROXIMATE_INPUT_BYTES;
+    const size_t estimated_rct_tx_size = estimate_tx_size(use_rct, tx.selected_transfers.size(), fake_outs_count, tx.dsts.size() + 1);
     bool try_tx = (unused_dust_indices.empty() && unused_transfers_indices.empty()) || ( estimated_rct_tx_size >= TX_SIZE_TARGET(upper_transaction_size_limit));
 
     if (try_tx) {