From cf1c0cb3ed0492f80d338c8e1390048737dd1d5c Mon Sep 17 00:00:00 2001
From: zzz <zzz@mail.i2p>
Date: Tue, 26 Feb 2019 17:17:00 +0000
Subject: [PATCH] SSU: Fix RTT/RTO calculations (ticket #2443)
---
.../i2p/router/transport/udp/ACKSender.java | 2 +-
.../transport/udp/EstablishmentManager.java | 4 +-
.../transport/udp/InboundEstablishState.java | 8 ++++
.../transport/udp/OutboundEstablishState.java | 7 +++
.../i2p/router/transport/udp/PeerState.java | 44 ++++++++++++-------
.../router/transport/udp/UDPTransport.java | 2 +-
6 files changed, 47 insertions(+), 20 deletions(-)
diff --git a/router/java/src/net/i2p/router/transport/udp/ACKSender.java b/router/java/src/net/i2p/router/transport/udp/ACKSender.java
index 60976d285b..6f01a3f625 100644
--- a/router/java/src/net/i2p/router/transport/udp/ACKSender.java
+++ b/router/java/src/net/i2p/router/transport/udp/ACKSender.java
@@ -62,7 +62,7 @@ class ACKSender implements Runnable {
public synchronized void shutdown() {
_alive = false;
- PeerState poison = new PeerState(_context, _transport, new byte[4], 0, null, false);
+ PeerState poison = new PeerState(_context, _transport, new byte[4], 0, null, false, 0);
poison.setTheyRelayToUsAs(POISON_PS);
_peersToACK.offer(poison);
for (int i = 1; i <= 5 && !_peersToACK.isEmpty(); i++) {
diff --git a/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java b/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java
index d0b999604f..94be6ca25e 100644
--- a/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java
+++ b/router/java/src/net/i2p/router/transport/udp/EstablishmentManager.java
@@ -694,7 +694,7 @@ class EstablishmentManager {
RouterIdentity remote = state.getConfirmedIdentity();
PeerState peer = new PeerState(_context, _transport,
- state.getSentIP(), state.getSentPort(), remote.calculateHash(), true);
+ state.getSentIP(), state.getSentPort(), remote.calculateHash(), true, state.getRTT());
peer.setCurrentCipherKey(state.getCipherKey());
peer.setCurrentMACKey(state.getMACKey());
peer.setWeRelayToThemAs(state.getSentRelayTag());
@@ -813,7 +813,7 @@ class EstablishmentManager {
_outboundByClaimedAddress.remove(claimed, state);
_outboundByHash.remove(remote.calculateHash(), state);
PeerState peer = new PeerState(_context, _transport,
- state.getSentIP(), state.getSentPort(), remote.calculateHash(), false);
+ state.getSentIP(), state.getSentPort(), remote.calculateHash(), false, state.getRTT());
peer.setCurrentCipherKey(state.getCipherKey());
peer.setCurrentMACKey(state.getMACKey());
peer.setTheyRelayToUsAs(state.getReceivedRelayTag());
diff --git a/router/java/src/net/i2p/router/transport/udp/InboundEstablishState.java b/router/java/src/net/i2p/router/transport/udp/InboundEstablishState.java
index 418876cc09..7e64a95280 100644
--- a/router/java/src/net/i2p/router/transport/udp/InboundEstablishState.java
+++ b/router/java/src/net/i2p/router/transport/udp/InboundEstablishState.java
@@ -64,6 +64,8 @@ class InboundEstablishState {
private int _createdSentCount;
// default true
private boolean _introductionRequested = true;
+
+ private int _rtt;
public enum InboundState {
/** nothin known yet */
@@ -296,6 +298,8 @@ class InboundEstablishState {
*/
public synchronized long getNextSendTime() { return _nextSend; }
+ synchronized int getRTT() { return _rtt; }
+
/** RemoteHostId, uniquely identifies an attempt */
RemoteHostId getRemoteHostId() { return _remoteHostId; }
@@ -356,6 +360,10 @@ class InboundEstablishState {
_currentState = InboundState.IB_STATE_CONFIRMED_PARTIALLY;
}
+ if (_createdSentCount == 1) {
+ _rtt = (int) ( _context.clock().now() - _lastSend );
+ }
+
packetReceived();
}
diff --git a/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState.java b/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState.java
index dd8fb6ac8b..bf9c284bd3 100644
--- a/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState.java
+++ b/router/java/src/net/i2p/router/transport/udp/OutboundEstablishState.java
@@ -74,6 +74,7 @@ class OutboundEstablishState {
private long _confirmedSentTime;
private long _requestSentTime;
private long _introSentTime;
+ private int _rtt;
public enum OutboundState {
/** nothin sent yet */
@@ -179,6 +180,8 @@ class OutboundEstablishState {
* @since 0.9.24
*/
public boolean needIntroduction() { return _needIntroduction; }
+
+ synchronized int getRTT() { return _rtt; }
/**
* Queue a message to be sent after the session is established.
@@ -304,6 +307,10 @@ class OutboundEstablishState {
_currentState == OutboundState.OB_STATE_INTRODUCED ||
_currentState == OutboundState.OB_STATE_PENDING_INTRO)
_currentState = OutboundState.OB_STATE_CREATED_RECEIVED;
+
+ if (_requestSentCount == 1) {
+ _rtt = (int) (_context.clock().now() - _requestSentTime);
+ }
packetReceived();
}
diff --git a/router/java/src/net/i2p/router/transport/udp/PeerState.java b/router/java/src/net/i2p/router/transport/udp/PeerState.java
index aa08bd9459..8bedd2ff38 100644
--- a/router/java/src/net/i2p/router/transport/udp/PeerState.java
+++ b/router/java/src/net/i2p/router/transport/udp/PeerState.java
@@ -314,10 +314,10 @@ public class PeerState {
*/
public static final int MAX_MTU = Math.max(LARGE_MTU, MAX_IPV6_MTU);
- private static final int MIN_RTO = 100 + ACKSender.ACK_FREQUENCY;
- private static final int INIT_RTO = 3*1000;
- public static final int INIT_RTT = INIT_RTO / 2;
- private static final int MAX_RTO = 15*1000;
+ private static final int MIN_RTO = 1000;
+ private static final int INIT_RTO = 1000;
+ private static final int INIT_RTT = 0;
+ private static final int MAX_RTO = 60*1000;
private static final int CLOCK_SKEW_FUDGE = (ACKSender.ACK_FREQUENCY * 2) / 3;
/**
@@ -336,8 +336,11 @@ public class PeerState {
private static final long RESEND_ACK_TIMEOUT = 5*60*1000;
+ /**
+ * @param rtt from the EstablishState, or 0 if not available
+ */
public PeerState(RouterContext ctx, UDPTransport transport,
- byte[] remoteIP, int remotePort, Hash remotePeer, boolean isInbound) {
+ byte[] remoteIP, int remotePort, Hash remotePeer, boolean isInbound, int rtt) {
_context = ctx;
_log = ctx.logManager().getLog(PeerState.class);
_transport = transport;
@@ -366,9 +369,14 @@ public class PeerState {
}
//_mtuLastChecked = -1;
_lastACKSend = -1;
+
_rto = INIT_RTO;
_rtt = INIT_RTT;
- _rttDeviation = _rtt;
+ if (rtt > 0)
+ recalculateTimeouts(rtt);
+ else
+ _rttDeviation = _rtt;
+
_inboundMessages = new HashMap<Long, InboundMessageState>(8);
_outboundMessages = new CachedIteratorCollection<OutboundMessageState>();
//_outboundQueue = new CoDelPriorityBlockingQueue(ctx, "UDP-PeerState", 32);
@@ -1226,16 +1234,18 @@ public class PeerState {
* Caller should synch on this
*/
private void recalculateTimeouts(long lifetime) {
- // the rttDev calculation matches that recommended in RFC 2988 (beta = 1/4)
- _rttDeviation = _rttDeviation + (int)(0.25d*(Math.abs(lifetime-_rtt)-_rttDeviation));
+ if (_rtt <= 0) {
+ // first measurement
+ _rtt = (int) lifetime;
+ _rttDeviation = (int)(lifetime / 2);
+ } else {
+ // the rttDev calculation matches that recommended in RFC 2988 (beta = 1/4)
+ _rttDeviation = (int)( 0.75*_rttDeviation + 0.25*Math.abs(lifetime-_rtt) );
- float scale = RTT_DAMPENING;
- // the faster we are going, the slower we want to reduce the rtt
- //if (_sendBps > 0)
- // scale = lifetime / ((float)lifetime + (float)_sendBps);
- //if (scale < 0.001f) scale = 0.001f;
+ float scale = RTT_DAMPENING;
- _rtt = (int)(_rtt*(1.0f-scale) + (scale)*lifetime);
+ _rtt = (int)(_rtt*(1.0f-scale) + (scale)*lifetime);
+ }
// K = 4
_rto = Math.min(MAX_RTO, Math.max(minRTO(), _rtt + (_rttDeviation<<2)));
//if (_log.shouldLog(Log.DEBUG))
@@ -1821,13 +1831,15 @@ public class PeerState {
+ " remaining"
+ " for message " + state.getMessageId() + ": " + state);
- if (state.getPushCount() > 0)
+ int rto = getRTO();
+ if (state.getPushCount() > 0) {
_retransmitter = state;
+ rto = Math.min(MAX_RTO, rto << state.getPushCount()); // Section 5.5 RFC 6298
+ }
if (state.push())
_messagesSent++;
- int rto = getRTO();
state.setNextSendTime(now + rto);
//if (peer.getSendWindowBytesRemaining() > 0)
diff --git a/router/java/src/net/i2p/router/transport/udp/UDPTransport.java b/router/java/src/net/i2p/router/transport/udp/UDPTransport.java
index 0681fd8a1f..0bc4de39b1 100644
--- a/router/java/src/net/i2p/router/transport/udp/UDPTransport.java
+++ b/router/java/src/net/i2p/router/transport/udp/UDPTransport.java
@@ -2723,7 +2723,7 @@ public class UDPTransport extends TransportImpl implements TimedWeightedPriority
for (PeerState peer : _peersByIdent.values()) {
if ((!includeEverybody) && now - peer.getLastReceiveTime() > 5*60*1000)
continue; // skip old peers
- if (peer.getRTT() > PeerState.INIT_RTT - 250)
+ if (peer.getRTT() > 1250)
continue; // Big RTT makes for a poor calculation
skews.addElement(Long.valueOf(peer.getClockSkew() / 1000));
}
--
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