From e68172ed9fd0e35d4e848142e9b36ffcc41de254 Mon Sep 17 00:00:00 2001
From: Ethan Heilman <ethan@geographicslab.org>
Date: Thu, 27 Oct 2016 13:55:39 -0400
Subject: Add test-before-evict discipline to addrman
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Changes addrman to use the test-before-evict discipline in which an
address is to be evicted from the tried table is first tested and if
it is still online it is not evicted.

Adds tests to provide test coverage for this change.

This change was suggested as Countermeasure 3 in
Eclipse Attacks on Bitcoin’s Peer-to-Peer Network, Ethan Heilman,
Alison Kendler, Aviv Zohar, Sharon Goldberg. ePrint Archive Report
2015/263. March 2015.
---
 src/net.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'src/net.cpp')

diff --git a/src/net.cpp b/src/net.cpp
index 201914685c..e08ce0fd33 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1824,11 +1824,18 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
             }
         }
 
+        addrman.ResolveCollisions();
+
         int64_t nANow = GetAdjustedTime();
         int nTries = 0;
         while (!interruptNet)
         {
-            CAddrInfo addr = addrman.Select(fFeeler);
+            CAddrInfo addr = addrman.SelectTriedCollision();
+
+            // SelectTriedCollision returns an invalid address if it is empty.
+            if (!fFeeler || !addr.IsValid()) {
+                addr = addrman.Select(fFeeler);
+            }
 
             // if we selected an invalid address, restart
             if (!addr.IsValid() || setConnected.count(addr.GetGroup()) || IsLocal(addr))
-- 
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