No longer allow "free" transactions

Remove -limitfreerelay and always enforce minRelayTxFee in the mempool (except from disconnected blocks)

Remove -relaypriority, the option was only used for the ability to allow free transactions to be relayed regardless of their priority.  Both notions no longer apply.

10 files changed, 10 insertions, 53 deletions

diff --git a/qa/rpc-tests/abandonconflict.py b/qa/rpc-tests/abandonconflict.py
index b32d4e2ce0..5a860e4392 100755
--- a/qa/rpc-tests/abandonconflict.py
+++ b/qa/rpc-tests/abandonconflict.py
@@ -80,7 +80,6 @@ class AbandonConflictTest(BitcoinTestFramework):
 
         # Restart the node with a higher min relay fee so the parent tx is no longer in mempool
         # TODO: redo with eviction
-        # Note had to make sure tx did not have AllowFree priority
         stop_node(self.nodes[0],0)
         self.nodes[0]=start_node(0, self.options.tmpdir, ["-debug","-logtimemicros","-minrelaytxfee=0.0001"])
 
diff --git a/qa/rpc-tests/smartfees.py b/qa/rpc-tests/smartfees.py
index 5a2b90767d..4289c7b0b6 100755
--- a/qa/rpc-tests/smartfees.py
+++ b/qa/rpc-tests/smartfees.py
@@ -188,8 +188,7 @@ class EstimateFeeTest(BitcoinTestFramework):
 
         # Now we can connect the other nodes, didn't want to connect them earlier
         # so the estimates would not be affected by the splitting transactions
-        # Node1 mines small blocks but that are bigger than the expected transaction rate,
-        # and allows free transactions.
+        # Node1 mines small blocks but that are bigger than the expected transaction rate.
         # NOTE: the CreateNewBlock code starts counting block size at 1,000 bytes,
         # (17k is room enough for 110 or so transactions)
         self.nodes.append(start_node(1, self.options.tmpdir,
diff --git a/src/init.cpp b/src/init.cpp
index c6026646d0..3276ec9f13 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -444,8 +444,6 @@ std::string HelpMessage(HelpMessageMode mode)
     {
         strUsage += HelpMessageOpt("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS));
         strUsage += HelpMessageOpt("-mocktime=<n>", "Replace actual time with <n> seconds since epoch (default: 0)");
-        strUsage += HelpMessageOpt("-limitfreerelay=<n>", strprintf("Continuously rate-limit free transactions to <n>*1000 bytes per minute (default: %u)", DEFAULT_LIMITFREERELAY));
-        strUsage += HelpMessageOpt("-relaypriority", strprintf("Require high priority for relaying free or low-fee transactions (default: %u)", DEFAULT_RELAYPRIORITY));
         strUsage += HelpMessageOpt("-maxsigcachesize=<n>", strprintf("Limit size of signature cache to <n> MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_SIZE));
         strUsage += HelpMessageOpt("-maxtipage=<n>", strprintf("Maximum tip age in seconds to consider node in initial block download (default: %u)", DEFAULT_MAX_TIP_AGE));
     }
@@ -975,7 +973,7 @@ bool AppInitParameterInteraction()
     if (nConnectTimeout <= 0)
         nConnectTimeout = DEFAULT_CONNECT_TIMEOUT;
 
-    // Fee-per-kilobyte amount considered the same as "free"
+    // Fee-per-kilobyte amount required for mempool acceptance and relay
     // If you are mining, be careful setting this:
     // if you set it to zero then
     // a transaction spammer can cheaply fill blocks using
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 3ec1a1c27d..71a0a1de22 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1853,7 +1853,7 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
                             LogPrint("mempool", "   invalid orphan tx %s\n", orphanHash.ToString());
                         }
                         // Has inputs but not accepted to mempool
-                        // Probably non-standard or insufficient fee/priority
+                        // Probably non-standard or insufficient fee
                         LogPrint("mempool", "   removed orphan tx %s\n", orphanHash.ToString());
                         vEraseQueue.push_back(orphanHash);
                         if (!orphanTx.HasWitness() && !stateDummy.CorruptionPossible()) {
@@ -3249,9 +3249,8 @@ bool SendMessages(CNode* pto, CConnman& connman, const std::atomic<bool>& interr
                 static CFeeRate default_feerate(DEFAULT_MIN_RELAY_TX_FEE);
                 static FeeFilterRounder filterRounder(default_feerate);
                 CAmount filterToSend = filterRounder.round(currentFilter);
-                // If we don't allow free transactions, then we always have a fee filter of at least minRelayTxFee
-                if (GetArg("-limitfreerelay", DEFAULT_LIMITFREERELAY) <= 0)
-                    filterToSend = std::max(filterToSend, ::minRelayTxFee.GetFeePerK());
+                // We always have a fee filter of at least minRelayTxFee
+                filterToSend = std::max(filterToSend, ::minRelayTxFee.GetFeePerK());
                 if (filterToSend != pto->lastSentFeeFilter) {
                     connman.PushMessage(pto, msgMaker.Make(NetMsgType::FEEFILTER, filterToSend));
                     pto->lastSentFeeFilter = filterToSend;
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 140cb4840b..3045fa2b53 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -61,7 +61,7 @@ UniValue getinfo(const JSONRPCRequest& request)
             "  \"keypoolsize\": xxxx,        (numeric) how many new keys are pre-generated\n"
             "  \"unlocked_until\": ttt,      (numeric) the timestamp in seconds since epoch (midnight Jan 1 1970 GMT) that the wallet is unlocked for transfers, or 0 if the wallet is locked\n"
             "  \"paytxfee\": x.xxxx,         (numeric) the transaction fee set in " + CURRENCY_UNIT + "/kB\n"
-            "  \"relayfee\": x.xxxx,         (numeric) minimum relay fee for non-free transactions in " + CURRENCY_UNIT + "/kB\n"
+            "  \"relayfee\": x.xxxx,         (numeric) minimum relay fee for transactions in " + CURRENCY_UNIT + "/kB\n"
             "  \"errors\": \"...\"           (string) any error messages\n"
             "}\n"
             "\nExamples:\n"
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index f590db5efa..a7169749c3 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -417,7 +417,7 @@ UniValue getnetworkinfo(const JSONRPCRequest& request)
             "  }\n"
             "  ,...\n"
             "  ],\n"
-            "  \"relayfee\": x.xxxxxxxx,                (numeric) minimum relay fee for non-free transactions in " + CURRENCY_UNIT + "/kB\n"
+            "  \"relayfee\": x.xxxxxxxx,                (numeric) minimum relay fee for transactions in " + CURRENCY_UNIT + "/kB\n"
             "  \"incrementalfee\": x.xxxxxxxx,          (numeric) minimum fee increment for mempool limiting or BIP 125 replacement in " + CURRENCY_UNIT + "/kB\n"
             "  \"localaddresses\": [                    (array) list of local addresses\n"
             "  {\n"
diff --git a/src/txmempool.h b/src/txmempool.h
index 4af85195c8..9af65bd077 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -30,18 +30,6 @@
 class CAutoFile;
 class CBlockIndex;
 
-inline double AllowFreeThreshold()
-{
-    return COIN * 144 / 250;
-}
-
-inline bool AllowFree(double dPriority)
-{
-    // Large (in bytes) low-priority (new, small-coin) transactions
-    // need a fee.
-    return dPriority > AllowFreeThreshold();
-}
-
 /** Fake height value used in CCoins to signify they are only in the memory pool (since 0.8) */
 static const unsigned int MEMPOOL_HEIGHT = 0x7FFFFFFF;
 
diff --git a/src/validation.cpp b/src/validation.cpp
index e84b1a7281..a21dc25a55 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -753,32 +753,11 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
         CAmount mempoolRejectFee = pool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nSize);
         if (mempoolRejectFee > 0 && nModifiedFees < mempoolRejectFee) {
             return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool min fee not met", false, strprintf("%d < %d", nFees, mempoolRejectFee));
-        } else if (GetBoolArg("-relaypriority", DEFAULT_RELAYPRIORITY) && nModifiedFees < ::minRelayTxFee.GetFee(nSize) && !AllowFree(entry.GetPriority(chainActive.Height() + 1))) {
-            // Require that free transactions have sufficient priority to be mined in the next block.
-            return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "insufficient priority");
         }
 
-        // Continuously rate-limit free (really, very-low-fee) transactions
-        // This mitigates 'penny-flooding' -- sending thousands of free transactions just to
-        // be annoying or make others' transactions take longer to confirm.
-        if (fLimitFree && nModifiedFees < ::minRelayTxFee.GetFee(nSize))
-        {
-            static CCriticalSection csFreeLimiter;
-            static double dFreeCount;
-            static int64_t nLastTime;
-            int64_t nNow = GetTime();
-
-            LOCK(csFreeLimiter);
-
-            // Use an exponentially decaying ~10-minute window:
-            dFreeCount *= pow(1.0 - 1.0/600.0, (double)(nNow - nLastTime));
-            nLastTime = nNow;
-            // -limitfreerelay unit is thousand-bytes-per-minute
-            // At default rate it would take over a month to fill 1GB
-            if (dFreeCount + nSize >= GetArg("-limitfreerelay", DEFAULT_LIMITFREERELAY) * 10 * 1000)
-                return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "rate limited free transaction");
-            LogPrint("mempool", "Rate limit dFreeCount: %g => %g\n", dFreeCount, dFreeCount+nSize);
-            dFreeCount += nSize;
+        // No transactions are allowed below minRelayTxFee except from disconnected blocks
+        if (fLimitFree && nModifiedFees < ::minRelayTxFee.GetFee(nSize)) {
+            return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "min relay fee not met");
         }
 
         if (nAbsurdFee && nFees > nAbsurdFee)
diff --git a/src/validation.h b/src/validation.h
index 9c606f2419..43f0dbae34 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -122,8 +122,6 @@ static const int64_t BLOCK_DOWNLOAD_TIMEOUT_BASE = 1000000;
 /** Additional block download timeout per parallel downloading peer (i.e. 5 min) */
 static const int64_t BLOCK_DOWNLOAD_TIMEOUT_PER_PEER = 500000;
 
-static const unsigned int DEFAULT_LIMITFREERELAY = 0;
-static const bool DEFAULT_RELAYPRIORITY = true;
 static const int64_t DEFAULT_MAX_TIP_AGE = 24 * 60 * 60;
 /** Maximum age of our tip in seconds for us to be considered current for fee estimation */
 static const int64_t MAX_FEE_ESTIMATION_TIP_AGE = 3 * 60 * 60;
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index cf3c6ee121..ba16cdf267 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3842,9 +3842,6 @@ bool CWallet::ParameterInteraction()
     bSpendZeroConfChange = GetBoolArg("-spendzeroconfchange", DEFAULT_SPEND_ZEROCONF_CHANGE);
     fWalletRbf = GetBoolArg("-walletrbf", DEFAULT_WALLET_RBF);
 
-    if (GetBoolArg("-sendfreetransactions", false))
-        InitWarning("The argument -sendfreetransactions is no longer supported.");
-
     return true;
 }