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-rw-r--r--src/net.cpp49
1 files changed, 20 insertions, 29 deletions
diff --git a/src/net.cpp b/src/net.cpp
index 5eaeaab8f6..935cb81901 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -961,6 +961,16 @@ static bool CompareNodeTXTime(const NodeEvictionCandidate &a, const NodeEviction
return a.nTimeConnected > b.nTimeConnected;
}
+
+//! Sort an array by the specified comparator, then erase the last K elements.
+template<typename T, typename Comparator>
+static void EraseLastKElements(std::vector<T> &elements, Comparator comparator, size_t k)
+{
+ std::sort(elements.begin(), elements.end(), comparator);
+ size_t eraseSize = std::min(k, elements.size());
+ elements.erase(elements.end() - eraseSize, elements.end());
+}
+
/** Try to find a connection to evict when the node is full.
* Extreme care must be taken to avoid opening the node to attacker
* triggered network partitioning.
@@ -990,42 +1000,23 @@ bool CConnman::AttemptToEvictConnection()
}
}
- if (vEvictionCandidates.empty()) return false;
-
// Protect connections with certain characteristics
// Deterministically select 4 peers to protect by netgroup.
// An attacker cannot predict which netgroups will be protected
- std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), CompareNetGroupKeyed);
- vEvictionCandidates.erase(vEvictionCandidates.end() - std::min(4, static_cast<int>(vEvictionCandidates.size())), vEvictionCandidates.end());
-
- if (vEvictionCandidates.empty()) return false;
-
+ EraseLastKElements(vEvictionCandidates, CompareNetGroupKeyed, 4);
// Protect the 8 nodes with the lowest minimum ping time.
// 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());
-
- if (vEvictionCandidates.empty()) return false;
-
+ EraseLastKElements(vEvictionCandidates, ReverseCompareNodeMinPingTime, 8);
// Protect 4 nodes that most recently sent us transactions.
// An attacker cannot manipulate this metric without performing useful work.
- std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), CompareNodeTXTime);
- vEvictionCandidates.erase(vEvictionCandidates.end() - std::min(4, static_cast<int>(vEvictionCandidates.size())), vEvictionCandidates.end());
-
- if (vEvictionCandidates.empty()) return false;
-
+ EraseLastKElements(vEvictionCandidates, CompareNodeTXTime, 4);
// Protect 4 nodes that most recently sent us blocks.
// An attacker cannot manipulate this metric without performing useful work.
- std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), CompareNodeBlockTime);
- vEvictionCandidates.erase(vEvictionCandidates.end() - std::min(4, static_cast<int>(vEvictionCandidates.size())), vEvictionCandidates.end());
-
- if (vEvictionCandidates.empty()) return false;
-
+ EraseLastKElements(vEvictionCandidates, CompareNodeBlockTime, 4);
// Protect the half of the remaining nodes which have been connected the longest.
// This replicates the non-eviction implicit behavior, and precludes attacks that start later.
- std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), ReverseCompareNodeTimeConnected);
- vEvictionCandidates.erase(vEvictionCandidates.end() - static_cast<int>(vEvictionCandidates.size() / 2), vEvictionCandidates.end());
+ EraseLastKElements(vEvictionCandidates, ReverseCompareNodeTimeConnected, vEvictionCandidates.size() / 2);
if (vEvictionCandidates.empty()) return false;
@@ -1036,12 +1027,12 @@ bool CConnman::AttemptToEvictConnection()
int64_t nMostConnectionsTime = 0;
std::map<uint64_t, std::vector<NodeEvictionCandidate> > mapNetGroupNodes;
for (const NodeEvictionCandidate &node : vEvictionCandidates) {
- mapNetGroupNodes[node.nKeyedNetGroup].push_back(node);
- int64_t grouptime = mapNetGroupNodes[node.nKeyedNetGroup][0].nTimeConnected;
- size_t groupsize = mapNetGroupNodes[node.nKeyedNetGroup].size();
+ std::vector<NodeEvictionCandidate> &group = mapNetGroupNodes[node.nKeyedNetGroup];
+ group.push_back(node);
+ int64_t grouptime = group[0].nTimeConnected;
- if (groupsize > nMostConnections || (groupsize == nMostConnections && grouptime > nMostConnectionsTime)) {
- nMostConnections = groupsize;
+ if (group.size() > nMostConnections || (group.size() == nMostConnections && grouptime > nMostConnectionsTime)) {
+ nMostConnections = group.size();
nMostConnectionsTime = grouptime;
naMostConnections = node.nKeyedNetGroup;
}