Add comments to AttemptToEvictConnection

src/net.cpp

@@ -950,13 +950,20 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
     }
 
     // Protect connections with certain characteristics
+
+    // Deterministically select 4 peers to protect by netgroup.
+    // An attacker cannot predict which netgroups will be protected.
     static CompareNetGroupKeyed comparerNetGroupKeyed;
     std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), comparerNetGroupKeyed);
     vEvictionCandidates.erase(vEvictionCandidates.end() - std::min(4, static_cast<int>(vEvictionCandidates.size())), vEvictionCandidates.end());
 
+    // Protect the 8 nodes with the best ping times.
+    // An attacker cannot manipulate this metric without physically moving nodes closer to the target.
     std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), ReverseCompareNodeMinPingTime);
     vEvictionCandidates.erase(vEvictionCandidates.end() - std::min(8, static_cast<int>(vEvictionCandidates.size())), vEvictionCandidates.end());
 
+    // Protect the 64 nodes which have been connected the longest.
+    // This replicates the existing implicit behavior.
     std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), ReverseCompareNodeTimeConnected);
     vEvictionCandidates.erase(vEvictionCandidates.end() - std::min(64, static_cast<int>(vEvictionCandidates.size())), vEvictionCandidates.end());