1 files changed, 30 insertions, 24 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 0067e9a2b2..e1a0973352 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -625,34 +625,11 @@ unsigned int LimitOrphanTxSize(unsigned int nMaxOrphans)
 
 bool IsStandardTx(const CTransaction& tx, string& reason)
 {
-    AssertLockHeld(cs_main);
     if (tx.nVersion > CTransaction::CURRENT_VERSION || tx.nVersion < 1) {
         reason = "version";
         return false;
     }
 
-    // Treat non-final transactions as non-standard to prevent a specific type
-    // of double-spend attack, as well as DoS attacks. (if the transaction
-    // can't be mined, the attacker isn't expending resources broadcasting it)
-    // Basically we don't want to propagate transactions that can't be included in
-    // the next block.
-    //
-    // However, IsFinalTx() is confusing... Without arguments, it uses
-    // chainActive.Height() to evaluate nLockTime; when a block is accepted, chainActive.Height()
-    // is set to the value of nHeight in the block. However, when IsFinalTx()
-    // is called within CBlock::AcceptBlock(), the height of the block *being*
-    // evaluated is what is used. Thus if we want to know if a transaction can
-    // be part of the *next* block, we need to call IsFinalTx() with one more
-    // than chainActive.Height().
-    //
-    // Timestamps on the other hand don't get any special treatment, because we
-    // can't know what timestamp the next block will have, and there aren't
-    // timestamp applications where it matters.
-    if (!IsFinalTx(tx, chainActive.Height() + 1)) {
-        reason = "non-final";
-        return false;
-    }
-
     // Extremely large transactions with lots of inputs can cost the network
     // almost as much to process as they cost the sender in fees, because
     // computing signature hashes is O(ninputs*txsize). Limiting transactions
@@ -941,6 +918,26 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
                          error("AcceptToMemoryPool : nonstandard transaction: %s", reason),
                          REJECT_NONSTANDARD, reason);
 
+    // Only accept nLockTime-using transactions that can be mined in the next
+    // block; we don't want our mempool filled up with transactions that can't
+    // be mined yet.
+    //
+    // However, IsFinalTx() is confusing... Without arguments, it uses
+    // chainActive.Height() to evaluate nLockTime; when a block is accepted,
+    // chainActive.Height() is set to the value of nHeight in the block.
+    // However, when IsFinalTx() is called within CBlock::AcceptBlock(), the
+    // height of the block *being* evaluated is what is used. Thus if we want
+    // to know if a transaction can be part of the *next* block, we need to
+    // call IsFinalTx() with one more than chainActive.Height().
+    //
+    // Timestamps on the other hand don't get any special treatment, because we
+    // can't know what timestamp the next block will have, and there aren't
+    // timestamp applications where it matters.
+    if (!IsFinalTx(tx, chainActive.Height() + 1))
+        return state.DoS(0,
+                         error("AcceptToMemoryPool : non-final"),
+                         REJECT_NONSTANDARD, "non-final");
+
     // is it already in the memory pool?
     uint256 hash = tx.GetHash();
     if (pool.exists(hash))
@@ -1030,6 +1027,11 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
                                       hash.ToString(), nFees, txMinFee),
                              REJECT_INSUFFICIENTFEE, "insufficient fee");
 
+        // Require that free transactions have sufficient priority to be mined in the next block.
+        if (GetBoolArg("-relaypriority", true) && nFees < ::minRelayTxFee.GetFee(nSize) && !AllowFree(view.GetPriority(tx, chainActive.Height() + 1))) {
+            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.
@@ -1049,7 +1051,7 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
             // At default rate it would take over a month to fill 1GB
             if (dFreeCount >= GetArg("-limitfreerelay", 15)*10*1000)
                 return state.DoS(0, error("AcceptToMemoryPool : free transaction rejected by rate limiter"),
-                                 REJECT_INSUFFICIENTFEE, "insufficient priority");
+                                 REJECT_INSUFFICIENTFEE, "rate limited free transaction");
             LogPrint("mempool", "Rate limit dFreeCount: %g => %g\n", dFreeCount, dFreeCount+nSize);
             dFreeCount += nSize;
         }
@@ -1882,6 +1884,7 @@ enum FlushStateMode {
 bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode) {
     LOCK(cs_main);
     static int64_t nLastWrite = 0;
+    try {
     if ((mode == FLUSH_STATE_ALWAYS) ||
         ((mode == FLUSH_STATE_PERIODIC || mode == FLUSH_STATE_IF_NEEDED) && pcoinsTip->GetCacheSize() > nCoinCacheSize) ||
         (mode == FLUSH_STATE_PERIODIC && GetTimeMicros() > nLastWrite + DATABASE_WRITE_INTERVAL * 1000000)) {
@@ -1921,6 +1924,9 @@ bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode) {
         }
         nLastWrite = GetTimeMicros();
     }
+    } catch (const std::runtime_error& e) {
+        return state.Abort(std::string("System error while flushing: ") + e.what());
+    }
     return true;
 }