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Merge #8084: Add recently accepted blocks and txn to AttemptToEvictConnection.

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6ee7f05 Allow disconnecting a netgroup with only one member in eviction. (Gregory Maxwell)
5d0ca81 Add recently accepted blocks and txn to AttemptToEvictConnection. (Gregory Maxwell)
This commit is contained in:
Wladimir J. van der Laan
2016-06-16 11:03:16 +02:00
parent 0a64777b90 6ee7f05622
commit e4bb4a85a5
4 changed files with 61 additions and 17 deletions
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55
src/net.cpp
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@@ -841,6 +841,11 @@ struct NodeEvictionCandidate
NodeId id;
int64_t nTimeConnected;
int64_t nMinPingUsecTime;
int64_t nLastBlockTime;
int64_t nLastTXTime;
bool fNetworkNode;
bool fRelayTxes;
bool fBloomFilter;
CAddress addr;
uint64_t nKeyedNetGroup;
};
@@ -857,7 +862,24 @@ static bool ReverseCompareNodeTimeConnected(const NodeEvictionCandidate &a, cons
static bool CompareNetGroupKeyed(const NodeEvictionCandidate &a, const NodeEvictionCandidate &b) {
return a.nKeyedNetGroup < b.nKeyedNetGroup;
};
}
static bool CompareNodeBlockTime(const NodeEvictionCandidate &a, const NodeEvictionCandidate &b)
{
// There is a fall-through here because it is common for a node to have many peers which have not yet relayed a block.
if (a.nLastBlockTime != b.nLastBlockTime) return a.nLastBlockTime < b.nLastBlockTime;
if (a.fNetworkNode != b.fNetworkNode) return b.fNetworkNode;
return a.nTimeConnected > b.nTimeConnected;
}
static bool CompareNodeTXTime(const NodeEvictionCandidate &a, const NodeEvictionCandidate &b)
{
// There is a fall-through here because it is common for a node to have more than a few peers that have not yet relayed txn.
if (a.nLastTXTime != b.nLastTXTime) return a.nLastTXTime < b.nLastTXTime;
if (a.fRelayTxes != b.fRelayTxes) return b.fRelayTxes;
if (a.fBloomFilter != b.fBloomFilter) return a.fBloomFilter;
return a.nTimeConnected > b.nTimeConnected;
}
/** Try to find a connection to evict when the node is full.
* Extreme care must be taken to avoid opening the node to attacker
@@ -867,7 +889,7 @@ static bool CompareNetGroupKeyed(const NodeEvictionCandidate &a, const NodeEvict
* to forge. In order to partition a node the attacker must be
* simultaneously better at all of them than honest peers.
*/
static bool AttemptToEvictConnection(bool fPreferNewConnection) {
static bool AttemptToEvictConnection() {
std::vector<NodeEvictionCandidate> vEvictionCandidates;
{
LOCK(cs_vNodes);
@@ -879,7 +901,9 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
continue;
if (node->fDisconnect)
continue;
NodeEvictionCandidate candidate = {node->id, node->nTimeConnected, node->nMinPingUsecTime, node->addr, node->nKeyedNetGroup};
NodeEvictionCandidate candidate = {node->id, node->nTimeConnected, node->nMinPingUsecTime,
node->nLastBlockTime, node->nLastTXTime, node->fNetworkNode,
node->fRelayTxes, node->pfilter != NULL, node->addr, node->nKeyedNetGroup};
vEvictionCandidates.push_back(candidate);
}
}
@@ -902,6 +926,20 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
if (vEvictionCandidates.empty()) return false;
// 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;
// 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;
// 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);
@@ -930,13 +968,6 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) {
// Reduce to the network group with the most connections
vEvictionCandidates = std::move(mapAddrCounts[naMostConnections]);
// Do not disconnect peers if there is only one unprotected connection from their network group.
// This step excessively favors netgroup diversity, and should be removed once more protective criteria are established.
if (vEvictionCandidates.size() <= 1)
// unless we prefer the new connection (for whitelisted peers)
if (!fPreferNewConnection)
return false;
// Disconnect from the network group with the most connections
NodeId evicted = vEvictionCandidates.front().id;
LOCK(cs_vNodes);
@@ -1002,7 +1033,7 @@ static void AcceptConnection(const ListenSocket& hListenSocket) {
if (nInbound >= nMaxInbound)
{
if (!AttemptToEvictConnection(whitelisted)) {
if (!AttemptToEvictConnection()) {
// No connection to evict, disconnect the new connection
LogPrint("net", "failed to find an eviction candidate - connection dropped (full)\n");
CloseSocket(hSocket);
@@ -2380,6 +2411,8 @@ CNode::CNode(SOCKET hSocketIn, const CAddress& addrIn, const std::string& addrNa
fSentAddr = false;
pfilter = new CBloomFilter();
timeLastMempoolReq = 0;
nLastBlockTime = 0;
nLastTXTime = 0;
nPingNonceSent = 0;
nPingUsecStart = 0;
nPingUsecTime = 0;