From 66b07247a7a9e48e082502338176cc06edf61474 Mon Sep 17 00:00:00 2001
From: Gregory Maxwell <greg@xiph.org>
Date: Mon, 11 Apr 2016 01:09:34 +0000
Subject: Only send one GetAddr response per connection.

This conserves resources from abusive peers that just send
 getaddr in a loop. Also makes correlating addr messages
 against INVs less effective.
---
 src/main.cpp | 8 ++++++++
 src/net.cpp  | 1 +
 src/net.h    | 1 +
 3 files changed, 10 insertions(+)

(limited to 'src')

diff --git a/src/main.cpp b/src/main.cpp
index f5c7e11d6e..df494b226d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -5214,6 +5214,14 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
             return true;
         }
 
+        // Only send one GetAddr response per connection to reduce resource waste
+        //  and discourage addr stamping of INV announcements.
+        if (pfrom->fSentAddr) {
+            LogPrint("net", "Ignoring repeated \"getaddr\". peer=%d\n", pfrom->id);
+            return true;
+        }
+        pfrom->fSentAddr = true;
+
         pfrom->vAddrToSend.clear();
         vector<CAddress> vAddr = addrman.GetAddr();
         BOOST_FOREACH(const CAddress &addr, vAddr)
diff --git a/src/net.cpp b/src/net.cpp
index e8cc753a48..77310fb162 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2384,6 +2384,7 @@ CNode::CNode(SOCKET hSocketIn, const CAddress& addrIn, const std::string& addrNa
     nNextAddrSend = 0;
     nNextInvSend = 0;
     fRelayTxes = false;
+    fSentAddr = false;
     pfilter = new CBloomFilter();
     nPingNonceSent = 0;
     nPingUsecStart = 0;
diff --git a/src/net.h b/src/net.h
index ab9eb68d85..230fd5bf40 100644
--- a/src/net.h
+++ b/src/net.h
@@ -358,6 +358,7 @@ public:
     // b) the peer may tell us in its version message that we should not relay tx invs
     //    unless it loads a bloom filter.
     bool fRelayTxes;
+    bool fSentAddr;
     CSemaphoreGrant grantOutbound;
     CCriticalSection cs_filter;
     CBloomFilter* pfilter;
-- 
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