Merge pull request ElementsProject#1433 from kilrau/reduce-default-dust-relay-fee

feat: reduce default dust relay fee

Author: psgreco

src/policy/policy.h

@@ -55,7 +55,7 @@ static const unsigned int MAX_STANDARD_SCRIPTSIG_SIZE = 1650;
  * standard and should be done with care and ideally rarely. It makes sense to
  * only increase the dust limit after prior releases were already not creating
  * outputs below the new threshold */
-static const unsigned int DUST_RELAY_TX_FEE = 3000;
+static const unsigned int DUST_RELAY_TX_FEE = 100;
 /**
  * Standard script verification flags that standard transactions will comply
  * with. However scripts violating these flags may still be present in valid
@@ -89,6 +89,9 @@ static constexpr unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCR
 static constexpr unsigned int STANDARD_LOCKTIME_VERIFY_FLAGS = LOCKTIME_VERIFY_SEQUENCE |
                                                                LOCKTIME_MEDIAN_TIME_PAST;
 
+// ELEMENTS: keep a copy of the upstream default dust relay fee rate
+static const unsigned int DUST_RELAY_TX_FEE_BITCOIN = 3000;
+
 CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee);
 
 bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee);

src/test/transaction_tests.cpp

@@ -795,6 +795,7 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
     CheckIsStandard(t);
 
     // Check dust with default relay fee:
+    dustRelayFee = CFeeRate(DUST_RELAY_TX_FEE_BITCOIN); // ELEMENTS: use the Bitcoin default dust relay feerate
     CAmount nDustThreshold = 182 * dustRelayFee.GetFeePerK() / 1000;
     BOOST_CHECK_EQUAL(nDustThreshold, 546);
     // dust:
@@ -830,7 +831,7 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
     // not dust:
     t.vout[0].nValue = 674;
     CheckIsStandard(t);
-    dustRelayFee = CFeeRate(DUST_RELAY_TX_FEE);
+    dustRelayFee = CFeeRate(DUST_RELAY_TX_FEE_BITCOIN); // ELEMENTS: use the Bitcoin default dust relay feerate
 
     t.vout[0].scriptPubKey = CScript() << OP_1;
     CheckIsNotStandard(t, "scriptpubkey");

test/functional/mempool_accept.py

@@ -46,6 +46,7 @@ def set_test_params(self):
             '-txindex',
             '-txindex','-permitbaremultisig=0',
             '-multi_data_permitted=1', # Elements test
+            '-dustrelayfee=0.00003000', # ELEMENTS: use the Bitcoin default dust relay fee rate
         ]] * self.num_nodes
         self.supports_cli = False