1 files changed, 98 insertions, 21 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 54f9f89c4d..755bec47b8 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -13,17 +13,25 @@
 #include "checkqueue.h"
 #include "consensus/consensus.h"
 #include "consensus/validation.h"
+#include "hash.h"
 #include "init.h"
 #include "merkleblock.h"
 #include "net.h"
 #include "policy/policy.h"
 #include "pow.h"
+#include "primitives/block.h"
+#include "primitives/transaction.h"
+#include "script/script.h"
+#include "script/sigcache.h"
+#include "script/standard.h"
+#include "tinyformat.h"
 #include "txdb.h"
 #include "txmempool.h"
 #include "ui_interface.h"
 #include "undo.h"
 #include "util.h"
 #include "utilmoneystr.h"
+#include "utilstrencodings.h"
 #include "validationinterface.h"
 
 #include <sstream>
@@ -154,6 +162,29 @@ namespace {
      */
     map<uint256, NodeId> mapBlockSource;
 
+    /**
+     * Filter for transactions that were recently rejected by
+     * AcceptToMemoryPool. These are not rerequested until the chain tip
+     * changes, at which point the entire filter is reset. Protected by
+     * cs_main.
+     *
+     * Without this filter we'd be re-requesting txs from each of our peers,
+     * increasing bandwidth consumption considerably. For instance, with 100
+     * peers, half of which relay a tx we don't accept, that might be a 50x
+     * bandwidth increase. A flooding attacker attempting to roll-over the
+     * filter using minimum-sized, 60byte, transactions might manage to send
+     * 1000/sec if we have fast peers, so we pick 120,000 to give our peers a
+     * two minute window to send invs to us.
+     *
+     * Decreasing the false positive rate is fairly cheap, so we pick one in a
+     * million to make it highly unlikely for users to have issues with this
+     * filter.
+     *
+     * Memory used: 1.7MB
+     */
+    boost::scoped_ptr<CRollingBloomFilter> recentRejects;
+    uint256 hashRecentRejectsChainTip;
+
     /** Blocks that are in flight, and that are in the queue to be downloaded. Protected by cs_main. */
     struct QueuedBlock {
         uint256 hash;
@@ -896,9 +927,10 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
         }
 
         if (fRejectAbsurdFee && nFees > ::minRelayTxFee.GetFee(nSize) * 10000)
-            return error("AcceptToMemoryPool: absurdly high fees %s, %d > %d",
-                         hash.ToString(),
-                         nFees, ::minRelayTxFee.GetFee(nSize) * 10000);
+            return state.Invalid(error("AcceptToMemoryPool: absurdly high fees %s, %d > %d",
+                                       hash.ToString(),
+                                       nFees, ::minRelayTxFee.GetFee(nSize) * 10000),
+                                 REJECT_HIGHFEE, "absurdly-high-fee");
 
         // Check against previous transactions
         // This is done last to help prevent CPU exhaustion denial-of-service attacks.
@@ -1196,9 +1228,11 @@ void static InvalidChainFound(CBlockIndex* pindexNew)
       pindexNew->GetBlockHash().ToString(), pindexNew->nHeight,
       log(pindexNew->nChainWork.getdouble())/log(2.0), DateTimeStrFormat("%Y-%m-%d %H:%M:%S",
       pindexNew->GetBlockTime()));
+    CBlockIndex *tip = chainActive.Tip();
+    assert (tip);
     LogPrintf("%s:  current best=%s  height=%d  log2_work=%.8g  date=%s\n", __func__,
-      chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(), log(chainActive.Tip()->nChainWork.getdouble())/log(2.0),
-      DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()));
+      tip->GetBlockHash().ToString(), chainActive.Height(), log(tip->nChainWork.getdouble())/log(2.0),
+      DateTimeStrFormat("%Y-%m-%d %H:%M:%S", tip->GetBlockTime()));
     CheckForkWarningConditions();
 }
 
@@ -1207,7 +1241,8 @@ void static InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state
     if (state.IsInvalid(nDoS)) {
         std::map<uint256, NodeId>::iterator it = mapBlockSource.find(pindex->GetBlockHash());
         if (it != mapBlockSource.end() && State(it->second)) {
-            CBlockReject reject = {state.GetRejectCode(), state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), pindex->GetBlockHash()};
+            assert(state.GetRejectCode() < 0x100);
+            CBlockReject reject = {(unsigned char)state.GetRejectCode(), state.GetRejectReason().substr(0, MAX_REJECT_MESSAGE_LENGTH), pindex->GetBlockHash()};
             State(it->second)->rejects.push_back(reject);
             if (nDoS > 0)
                 Misbehaving(it->second, nDoS);
@@ -2726,9 +2761,15 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
 
     // Try to process all requested blocks that we don't have, but only
     // process an unrequested block if it's new and has enough work to
-    // advance our tip.
+    // advance our tip, and isn't too many blocks ahead.
     bool fAlreadyHave = pindex->nStatus & BLOCK_HAVE_DATA;
     bool fHasMoreWork = (chainActive.Tip() ? pindex->nChainWork > chainActive.Tip()->nChainWork : true);
+    // Blocks that are too out-of-order needlessly limit the effectiveness of
+    // pruning, because pruning will not delete block files that contain any
+    // blocks which are too close in height to the tip.  Apply this test
+    // regardless of whether pruning is enabled; it should generally be safe to
+    // not process unrequested blocks.
+    bool fTooFarAhead = (pindex->nHeight > int(chainActive.Height() + MIN_BLOCKS_TO_KEEP));
 
     // TODO: deal better with return value and error conditions for duplicate
     // and unrequested blocks.
@@ -2736,6 +2777,7 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
     if (!fRequested) {  // If we didn't ask for it:
         if (pindex->nTx != 0) return true;  // This is a previously-processed block that was pruned
         if (!fHasMoreWork) return true;     // Don't process less-work chains
+        if (fTooFarAhead) return true;      // Block height is too high
     }
 
     if ((!CheckBlock(block, state)) || !ContextualCheckBlock(block, state, pindex->pprev)) {
@@ -3233,6 +3275,7 @@ void UnloadBlockIndex()
     setDirtyBlockIndex.clear();
     setDirtyFileInfo.clear();
     mapNodeState.clear();
+    recentRejects.reset(NULL);
 
     BOOST_FOREACH(BlockMap::value_type& entry, mapBlockIndex) {
         delete entry.second;
@@ -3253,6 +3296,10 @@ bool LoadBlockIndex()
 bool InitBlockIndex() {
     const CChainParams& chainparams = Params();
     LOCK(cs_main);
+
+    // Initialize global variables that cannot be constructed at startup.
+    recentRejects.reset(new CRollingBloomFilter(120000, 0.000001));
+
     // Check whether we're already initialized
     if (chainActive.Genesis() != NULL)
         return true;
@@ -3383,7 +3430,7 @@ bool LoadExternalBlockFile(FILE* fileIn, CDiskBlockPos *dbp)
                     }
                 }
             } catch (const std::exception& e) {
-                LogPrintf("%s: Deserialize or I/O error - %s", __func__, e.what());
+                LogPrintf("%s: Deserialize or I/O error - %s\n", __func__, e.what());
             }
         }
     } catch (const std::runtime_error& e) {
@@ -3655,10 +3702,21 @@ bool static AlreadyHave(const CInv& inv) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
     {
     case MSG_TX:
         {
-            bool txInMap = false;
-            txInMap = mempool.exists(inv.hash);
-            return txInMap || mapOrphanTransactions.count(inv.hash) ||
-                pcoinsTip->HaveCoins(inv.hash);
+            assert(recentRejects);
+            if (chainActive.Tip()->GetBlockHash() != hashRecentRejectsChainTip)
+            {
+                // If the chain tip has changed previously rejected transactions
+                // might be now valid, e.g. due to a nLockTime'd tx becoming valid,
+                // or a double-spend. Reset the rejects filter and give those
+                // txs a second chance.
+                hashRecentRejectsChainTip = chainActive.Tip()->GetBlockHash();
+                recentRejects->reset();
+            }
+
+            return recentRejects->contains(inv.hash) ||
+                   mempool.exists(inv.hash) ||
+                   mapOrphanTransactions.count(inv.hash) ||
+                   pcoinsTip->HaveCoins(inv.hash);
         }
     case MSG_BLOCK:
         return mapBlockIndex.count(inv.hash);
@@ -3844,7 +3902,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         if (!vRecv.empty())
             vRecv >> addrFrom >> nNonce;
         if (!vRecv.empty()) {
-            vRecv >> LIMITED_STRING(pfrom->strSubVer, 256);
+            vRecv >> LIMITED_STRING(pfrom->strSubVer, MAX_SUBVERSION_LENGTH);
             pfrom->cleanSubVer = SanitizeString(pfrom->strSubVer);
         }
         if (!vRecv.empty())
@@ -4258,6 +4316,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                         // Probably non-standard or insufficient fee/priority
                         LogPrint("mempool", "   removed orphan tx %s\n", orphanHash.ToString());
                         vEraseQueue.push_back(orphanHash);
+                        assert(recentRejects);
+                        recentRejects->insert(orphanHash);
                     }
                     mempool.check(pcoinsTip);
                 }
@@ -4275,11 +4335,24 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             unsigned int nEvicted = LimitOrphanTxSize(nMaxOrphanTx);
             if (nEvicted > 0)
                 LogPrint("mempool", "mapOrphan overflow, removed %u tx\n", nEvicted);
-        } else if (pfrom->fWhitelisted) {
-            // Always relay transactions received from whitelisted peers, even
-            // if they are already in the mempool (allowing the node to function
-            // as a gateway for nodes hidden behind it).
-            RelayTransaction(tx);
+        } else {
+            // AcceptToMemoryPool() returned false, possibly because the tx is
+            // already in the mempool; if the tx isn't in the mempool that
+            // means it was rejected and we shouldn't ask for it again.
+            if (!mempool.exists(tx.GetHash())) {
+                assert(recentRejects);
+                recentRejects->insert(tx.GetHash());
+            }
+            if (pfrom->fWhitelisted) {
+                // Always relay transactions received from whitelisted peers, even
+                // if they were rejected from the mempool, allowing the node to
+                // function as a gateway for nodes hidden behind it.
+                //
+                // FIXME: This includes invalid transactions, which means a
+                // whitelisted peer could get us banned! We may want to change
+                // that.
+                RelayTransaction(tx);
+            }
         }
         int nDoS = 0;
         if (state.IsInvalid(nDoS))
@@ -4360,8 +4433,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         pfrom->AddInventoryKnown(inv);
 
         CValidationState state;
-        // Process all blocks from whitelisted peers, even if not requested.
-        ProcessNewBlock(state, pfrom, &block, pfrom->fWhitelisted, NULL);
+        // Process all blocks from whitelisted peers, even if not requested,
+        // unless we're still syncing with the network.
+        // Such an unrequested block may still be processed, subject to the
+        // conditions in AcceptBlock().
+        bool forceProcessing = pfrom->fWhitelisted && !IsInitialBlockDownload();
+        ProcessNewBlock(state, pfrom, &block, forceProcessing, NULL);
         int nDoS;
         if (state.IsInvalid(nDoS)) {
             pfrom->PushMessage("reject", strCommand, state.GetRejectCode(),
@@ -4778,7 +4855,7 @@ bool SendMessages(CNode* pto, bool fSendTrickle)
             {
                 // Periodically clear addrKnown to allow refresh broadcasts
                 if (nLastRebroadcast)
-                    pnode->addrKnown.clear();
+                    pnode->addrKnown.reset();
 
                 // Rebroadcast our address
                 AdvertizeLocal(pnode);