From 8de9bb53af32f7f6b09c06f831f2c0a7b4e95303 Mon Sep 17 00:00:00 2001
From: Gavin Andresen <gavinandresen@gmail.com>
Date: Wed, 24 Apr 2013 18:27:00 -0400
Subject: Define dust transaction outputs, and make them non-standard

---
 src/wallet.cpp | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

(limited to 'src/wallet.cpp')

diff --git a/src/wallet.cpp b/src/wallet.cpp
index c7eb4f74e8..1554b15768 100644
--- a/src/wallet.cpp
+++ b/src/wallet.cpp
@@ -1162,7 +1162,12 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, int64> >& vecSend, CW
                 double dPriority = 0;
                 // vouts to the payees
                 BOOST_FOREACH (const PAIRTYPE(CScript, int64)& s, vecSend)
-                    wtxNew.vout.push_back(CTxOut(s.second, s.first));
+                {
+                    CTxOut txout(s.second, s.first);
+                    if (txout.IsDust())
+                        return false;
+                    wtxNew.vout.push_back(txout);
+                }
 
                 // Choose coins to use
                 set<pair<const CWalletTx*,unsigned int> > setCoins;
@@ -1208,9 +1213,21 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, int64> >& vecSend, CW
                     CScript scriptChange;
                     scriptChange.SetDestination(vchPubKey.GetID());
 
-                    // Insert change txn at random position:
-                    vector<CTxOut>::iterator position = wtxNew.vout.begin()+GetRandInt(wtxNew.vout.size()+1);
-                    wtxNew.vout.insert(position, CTxOut(nChange, scriptChange));
+                    CTxOut newTxOut(nChange, scriptChange);
+
+                    // Never create dust outputs; if we would, just
+                    // add the dust to the fee.
+                    if (newTxOut.IsDust())
+                    {
+                        nFeeRet += nChange;
+                        reservekey.ReturnKey();
+                    }
+                    else
+                    {
+                        // Insert change txn at random position:
+                        vector<CTxOut>::iterator position = wtxNew.vout.begin()+GetRandInt(wtxNew.vout.size()+1);
+                        wtxNew.vout.insert(position, newTxOut);
+                    }
                 }
                 else
                     reservekey.ReturnKey();
-- 
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