Remove factor of 3 from definition of dust.

This redefines dust to be the value of an output such that it would
cost that value in fees to (create and) spend the output at the dust
relay rate.  The previous definition was that it would cost 1/3 of the
value.  The default dust relay rate is correspondingly increased to
3000 sat/kB so the actual default dust output value of 546 satoshis
for a non-segwit output remains unchanged.  This commit is a refactor
only unless a dustrelayfee is passed on the commandline in which case
that number now needs to be increased by a factor of 3 to get the same
behavior.  -dustrelayfee is a hidden command line option.

Note: It's not exactly a refactor due to edge case changes in rounding
as evidenced by the required change to the unit test.

1 files changed, 5 insertions, 5 deletions

diff --git a/src/test/transaction_tests.cpp b/src/test/transaction_tests.cpp
index 39f9f58604..6654634bf1 100644
--- a/src/test/transaction_tests.cpp
+++ b/src/test/transaction_tests.cpp
@@ -692,7 +692,7 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
     BOOST_CHECK(IsStandardTx(t, reason));
 
     // Check dust with default relay fee:
-    CAmount nDustThreshold = 182 * dustRelayFee.GetFeePerK()/1000 * 3;
+    CAmount nDustThreshold = 182 * dustRelayFee.GetFeePerK()/1000;
     BOOST_CHECK_EQUAL(nDustThreshold, 546);
     // dust:
     t.vout[0].nValue = nDustThreshold - 1;
@@ -702,13 +702,13 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
     BOOST_CHECK(IsStandardTx(t, reason));
 
     // Check dust with odd relay fee to verify rounding:
-    // nDustThreshold = 182 * 1234 / 1000 * 3
-    dustRelayFee = CFeeRate(1234);
+    // nDustThreshold = 182 * 3702 / 1000
+    dustRelayFee = CFeeRate(3702);
     // dust:
-    t.vout[0].nValue = 672 - 1;
+    t.vout[0].nValue = 673 - 1;
     BOOST_CHECK(!IsStandardTx(t, reason));
     // not dust:
-    t.vout[0].nValue = 672;
+    t.vout[0].nValue = 673;
     BOOST_CHECK(IsStandardTx(t, reason));
     dustRelayFee = CFeeRate(DUST_RELAY_TX_FEE);