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[PAN-1683] Fix handling of remote connection limit (PegaSysEng#1676)
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* Fix bugs

Fix remote connection fraction calculation (order of operations bug),
remove early return, allow all remote connections to be prohibited,
change disconnect reason to TOO_MANY_PEERS.

* Fix comment
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@mbaxter @AbdelStark
mbaxter authored and AbdelStark committed Jul 12, 2019
1 parent 4057647 commit 002bb6a
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Showing 3 changed files with 120 additions and 22 deletions.
4 changes: 2 additions & 2 deletions ethereum/p2p/src/main/java/tech/pegasys/pantheon/ethereum/p2p/config/RlpxConfiguration.java
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Original file line number Diff line number Diff line change
Expand Up @@ -102,8 +102,8 @@ public double getFractionRemoteWireConnectionsAllowed() {
public RlpxConfiguration setFractionRemoteWireConnectionsAllowed(
final double fractionRemoteWireConnectionsAllowed) {
checkState(
fractionRemoteWireConnectionsAllowed > 0.0,
"Fraction of remote connections allowed must be positive.");
fractionRemoteWireConnectionsAllowed >= 0.0 && fractionRemoteWireConnectionsAllowed <= 1.0,
"Fraction of remote connections allowed must be between 0.0 and 1.0 (inclusive).");
this.fractionRemoteWireConnectionsAllowed = fractionRemoteWireConnectionsAllowed;
return this;
}
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7 changes: 2 additions & 5 deletions ethereum/p2p/src/main/java/tech/pegasys/pantheon/ethereum/p2p/rlpx/RlpxAgent.java
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Original file line number Diff line number Diff line change
Expand Up @@ -341,7 +341,7 @@ private void handleIncomingConnection(final PeerConnection peerConnection) {
LOG.warn(
"Fraction of remotely initiated connection is too high, rejecting incoming connection. (max ratio allowed: {})",
fractionRemoteConnectionsAllowed);
peerConnection.disconnect(DisconnectReason.SUBPROTOCOL_TRIGGERED);
peerConnection.disconnect(DisconnectReason.TOO_MANY_PEERS);
return;
}

Expand Down Expand Up @@ -397,11 +397,8 @@ private boolean remoteConnectionExceedsLimit() {
.filter(RlpxConnection::isActive)
.filter(RlpxConnection::initiatedRemotely)
.count());
if (remotelyInitiatedConnectionsCount == 0) {
return false;
}
final double fractionRemoteConnections =
(double) remotelyInitiatedConnectionsCount + 1 / (double) maxPeers;
(double) (remotelyInitiatedConnectionsCount + 1) / (double) maxPeers;
return fractionRemoteConnections > fractionRemoteConnectionsAllowed;
}

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131 changes: 116 additions & 15 deletions ethereum/p2p/src/test/java/tech/pegasys/pantheon/ethereum/p2p/rlpx/RlpxAgentTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,7 @@
import java.util.stream.Stream;

import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;

public class RlpxAgentTest {
Expand Down Expand Up @@ -320,19 +321,122 @@ public void incomingConnection_maxPeersExceeded()
}

@Test
public void connect_failsWhenFractionOfRemoteConnectionsTooHigh() {
startAgentWithMaxPeersAndEnableLimitRemoteConnections(3);
// Connect 1 peer (locally initiated)
agent.connect(createPeer());
// Connect 1 peer (remotely initiated)
connectionInitializer.simulateIncomingConnection(connection(createPeer()));
// Add remotely initiated connection, this one must be rejected because the fraction of remote
// connections is 0.5
public void incomingConnection_afterMaxRemotelyInitiatedConnectionsHaveBeenEstablished() {
final int maxPeers = 10;
final int maxRemotePeers = 8;
final double maxRemotePeersFraction = (double) maxRemotePeers / (double) maxPeers;
config.setLimitRemoteWireConnectionsEnabled(true);
config.setFractionRemoteWireConnectionsAllowed(maxRemotePeersFraction);
startAgentWithMaxPeers(maxPeers);

// Connect max remote peers
for (int i = 0; i < maxRemotePeers; i++) {
final Peer remotelyInitiatedPeer = createPeer();
final MockPeerConnection incomingConnection = connection(remotelyInitiatedPeer);
connectionInitializer.simulateIncomingConnection(incomingConnection);
assertThat(incomingConnection.getDisconnectReason()).isEmpty();
}

// Next remote connection should be rejected
final Peer remotelyInitiatedPeer = createPeer();
final MockPeerConnection incomingConnection = connection(remotelyInitiatedPeer);
connectionInitializer.simulateIncomingConnection(incomingConnection);
assertThat(incomingConnection.getDisconnectReason())
.contains(DisconnectReason.SUBPROTOCOL_TRIGGERED);
assertThat(incomingConnection.getDisconnectReason()).contains(DisconnectReason.TOO_MANY_PEERS);
}

@Test
public void connect_afterMaxRemotelyInitiatedConnectionsHaveBeenEstablished() {
final int maxPeers = 10;
final int maxRemotePeers = 8;
final double maxRemotePeersFraction = (double) maxRemotePeers / (double) maxPeers;
config.setLimitRemoteWireConnectionsEnabled(true);
config.setFractionRemoteWireConnectionsAllowed(maxRemotePeersFraction);
startAgentWithMaxPeers(maxPeers);

// Connect max remote peers
for (int i = 0; i < maxRemotePeers; i++) {
final Peer remotelyInitiatedPeer = createPeer();
final MockPeerConnection incomingConnection = connection(remotelyInitiatedPeer);
connectionInitializer.simulateIncomingConnection(incomingConnection);
assertThat(incomingConnection.getDisconnectReason()).isEmpty();
}

// Subsequent local connection should be permitted up to maxPeers
for (int i = 0; i < (maxPeers - maxRemotePeers); i++) {
final Peer peer = createPeer();
final CompletableFuture<PeerConnection> connection = agent.connect(peer);
assertThat(connection).isDone();
assertThat(connection).isNotCompletedExceptionally();
assertThat(agent.getPeerConnection(peer)).contains(connection);
}
}

@Test
public void incomingConnection_withMaxRemotelyInitiatedConnectionsAt100Percent() {
final int maxPeers = 10;
final double maxRemotePeersFraction = 1.0;
config.setLimitRemoteWireConnectionsEnabled(true);
config.setFractionRemoteWireConnectionsAllowed(maxRemotePeersFraction);
startAgentWithMaxPeers(maxPeers);

// Connect max remote peers
for (int i = 0; i < maxPeers; i++) {
final Peer remotelyInitiatedPeer = createPeer();
final MockPeerConnection incomingConnection = connection(remotelyInitiatedPeer);
connectionInitializer.simulateIncomingConnection(incomingConnection);
assertThat(incomingConnection.getDisconnectReason()).isEmpty();
}
}

@Test
public void connect_withMaxRemotelyInitiatedConnectionsAt100Percent() {
final int maxPeers = 10;
final double maxRemotePeersFraction = 1.0;
config.setLimitRemoteWireConnectionsEnabled(true);
config.setFractionRemoteWireConnectionsAllowed(maxRemotePeersFraction);
startAgentWithMaxPeers(maxPeers);

// Connect max peers locally
for (int i = 0; i < maxPeers; i++) {
final Peer peer = createPeer();
final CompletableFuture<PeerConnection> connection = agent.connect(peer);
assertThat(connection).isDone();
assertThat(connection).isNotCompletedExceptionally();
assertThat(agent.getPeerConnection(peer)).contains(connection);
}
}

@Test
public void incomingConnection_withMaxRemotelyInitiatedConnectionsAtZeroPercent() {
final int maxPeers = 10;
final double maxRemotePeersFraction = 0.0;
config.setLimitRemoteWireConnectionsEnabled(true);
config.setFractionRemoteWireConnectionsAllowed(maxRemotePeersFraction);
startAgentWithMaxPeers(maxPeers);

// First remote connection should be rejected
final Peer remotelyInitiatedPeer = createPeer();
final MockPeerConnection incomingConnection = connection(remotelyInitiatedPeer);
connectionInitializer.simulateIncomingConnection(incomingConnection);
assertThat(incomingConnection.getDisconnectReason()).contains(DisconnectReason.TOO_MANY_PEERS);
}

@Test
public void connect_withMaxRemotelyInitiatedConnectionsAtZeroPercent() {
final int maxPeers = 10;
final double maxRemotePeersFraction = 0.0;
config.setLimitRemoteWireConnectionsEnabled(true);
config.setFractionRemoteWireConnectionsAllowed(maxRemotePeersFraction);
startAgentWithMaxPeers(maxPeers);

// Connect max local peers
for (int i = 0; i < maxPeers; i++) {
final Peer peer = createPeer();
final CompletableFuture<PeerConnection> connection = agent.connect(peer);
assertThat(connection).isDone();
assertThat(connection).isNotCompletedExceptionally();
assertThat(agent.getPeerConnection(peer)).contains(connection);
}
}

@Test
Expand Down Expand Up @@ -394,6 +498,7 @@ public void connect_succeedsForExemptPeerWhenMaxExemptPeersConnected() {
}

@Test
@Ignore("Ignore while PAN-1683 is being reworked")
public void incomingConnection_maxPeersExceeded_incomingConnectionExemptFromLimits()
throws ExecutionException, InterruptedException {
final Peer peerA = createPeer();
Expand Down Expand Up @@ -448,6 +553,7 @@ public void incomingConnection_maxPeersExceeded_existingConnectionExemptFromLimi
}

@Test
@Ignore("Ignore while PAN-1683 is being reworked")
public void incomingConnection_maxPeersExceeded_allConnectionsExemptFromLimits()
throws ExecutionException, InterruptedException {
final Peer peerA = createPeer();
Expand Down Expand Up @@ -818,11 +924,6 @@ private void startAgentWithMaxPeers(final int maxPeers) {
startAgent();
}

private void startAgentWithMaxPeersAndEnableLimitRemoteConnections(final int maxPeers) {
config.setLimitRemoteWireConnectionsEnabled(true);
startAgentWithMaxPeers(maxPeers);
}

private void startAgent(final BytesValue nodeId) {
agent.start();
localNode.setEnode(enodeBuilder().nodeId(nodeId).build());
Expand Down

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