From dfa0bd234182480eaf1722edebb7ff465dd0d861 Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Tue, 31 May 2016 15:47:15 +0200
Subject: [PATCH] Merge #8080: Do not use mempool for GETDATA for tx accepted
 after the last mempool req.

7e908c7 Do not use mempool for GETDATA for tx accepted after the last mempool req. (Gregory Maxwell)
---
 src/net.cpp            |  1 +
 src/net.h              |  2 ++
 src/net_processing.cpp |  5 ++++-
 src/txmempool.cpp      | 10 +++++++++-
 src/txmempool.h        |  1 +
 5 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/net.cpp b/src/net.cpp
index ff893f71a..6a6189f1a 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2679,6 +2679,7 @@ CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn
     fRelayTxes = false;
     fSentAddr = false;
     pfilter = new CBloomFilter();
+    timeLastMempoolReq = 0;
     nLastBlockTime = 0;
     nLastTXTime = 0;
     nPingNonceSent = 0;
diff --git a/src/net.h b/src/net.h
index efcaf8240..78330e69d 100644
--- a/src/net.h
+++ b/src/net.h
@@ -766,6 +766,8 @@ public:
     std::atomic<int64_t> nLastBlockTime;
     std::atomic<int64_t> nLastTXTime;
 
+    // Last time a "MEMPOOL" request was serviced.
+    std::atomic<int64_t> timeLastMempoolReq;
     // Ping time measurement:
     // The pong reply we're expecting, or 0 if no pong expected.
     uint64_t nPingNonceSent;
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 229379e8b..eaeee1e0f 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -898,7 +898,10 @@ void static ProcessGetData(CNode* pfrom, const Consensus::Params& consensusParam
 
                 if (!pushed && inv.type == MSG_TX) {
                     CTransaction tx;
-                    if (mempool.lookup(inv.hash, tx)) {
+                    int64_t txtime;
+                    // To protect privacy, do not answer getdata using the mempool when
+                    // that TX couldn't have been INVed in reply to a MEMPOOL request.
+                    if (mempool.lookup(inv.hash, tx, txtime) && txtime <= pfrom->timeLastMempoolReq) {
                         connman.PushMessage(pfrom, NetMsgType::TX, tx);
                         pushed = true;
                     }
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 17bfaa3cb..23efd790e 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -925,15 +925,23 @@ void CTxMemPool::queryHashes(vector<uint256>& vtxid)
     std::sort(vtxid.begin(), vtxid.end(), DepthAndScoreComparator(this));
 }
 
-bool CTxMemPool::lookup(uint256 hash, CTransaction& result) const
+
+bool CTxMemPool::lookup(uint256 hash, CTransaction& result, int64_t& time) const
 {
     LOCK(cs);
     indexed_transaction_set::const_iterator i = mapTx.find(hash);
     if (i == mapTx.end()) return false;
     result = i->GetTx();
+    time = i->GetTime();
     return true;
 }
 
+bool CTxMemPool::lookup(uint256 hash, CTransaction& result) const
+{
+    int64_t time;
+    return CTxMemPool::lookup(hash, result, time);
+}
+
 bool CTxMemPool::lookupFeeRate(const uint256& hash, CFeeRate& feeRate) const
 {
     LOCK(cs);
diff --git a/src/txmempool.h b/src/txmempool.h
index 07ffbd70e..4e6d327c2 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -648,6 +648,7 @@ public:
     }
 
     bool lookup(uint256 hash, CTransaction& result) const;
+    bool lookup(uint256 hash, CTransaction& result, int64_t& time) const;
     bool lookupFeeRate(const uint256& hash, CFeeRate& feeRate) const;
 
     /** Estimate fee rate needed to get into the next nBlocks