From 79c02c88b347f1408a2db307db2654917f9b0bcc Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter@wuille.net>
Date: Wed, 2 Jun 2021 13:54:41 -0700
Subject: Randomize message processing peer order

---
 src/net.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/net.cpp b/src/net.cpp
index 6f9f17ed4e..9c6cb379d2 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2173,6 +2173,7 @@ void CConnman::OpenNetworkConnection(const CAddress& addrConnect, bool fCountFai
 
 void CConnman::ThreadMessageHandler()
 {
+    FastRandomContext rng;
     while (!flagInterruptMsgProc)
     {
         std::vector<CNode*> vNodesCopy;
@@ -2186,6 +2187,11 @@ void CConnman::ThreadMessageHandler()
 
         bool fMoreWork = false;
 
+        // Randomize the order in which we process messages from/to our peers.
+        // This prevents attacks in which an attacker exploits having multiple
+        // consecutive connections in the vNodes list.
+        Shuffle(vNodesCopy.begin(), vNodesCopy.end(), rng);
+
         for (CNode* pnode : vNodesCopy)
         {
             if (pnode->fDisconnect)
-- 
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