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https://issues.apache.org/jira/browse/ARTEMIS-4646?focusedWorklogId=905779&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-905779
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ASF GitHub Bot logged work on ARTEMIS-4646:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 19/Feb/24 22:40
Start Date: 19/Feb/24 22:40
Worklog Time Spent: 10m
Work Description: jbertram commented on code in PR #4823:
URL: https://github.com/apache/activemq-artemis/pull/4823#discussion_r1495064560
##########
artemis-protocols/artemis-mqtt-protocol/src/main/java/org/apache/activemq/artemis/core/protocol/mqtt/MQTTSessionState.java:
##########
@@ -461,8 +459,14 @@ public int generateMqttId(long messageId, long consumerId)
{
synchronized (dataStoreLock) {
Integer id = artemisToMqttMessageMap.get(generateKey(messageId,
consumerId));
if (id == null) {
- ids.compareAndSet(Short.MAX_VALUE, 1);
- id = ids.addAndGet(1);
+ do {
+ if (currentId == 0xffff) {
Review Comment:
You can use
`org.apache.activemq.artemis.core.protocol.mqtt.MQTTUtil#TWO_BYTE_INT_MAX` here
instead of `0xffff`.
Issue Time Tracking
-------------------
Worklog Id: (was: 905779)
Time Spent: 20m (was: 10m)
> Unacknowledged MQTT message ID is reused after ID generator wraparound
> ----------------------------------------------------------------------
>
> Key: ARTEMIS-4646
> URL: https://issues.apache.org/jira/browse/ARTEMIS-4646
> Project: ActiveMQ Artemis
> Issue Type: Bug
> Components: MQTT
> Reporter: Albertas Vyšniauskas
> Priority: Major
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Hello,
> MQTT message IDs are currently generated by incrementing *ids* variable in
> *{color:#000000}{color:#000000}OutboundStore{color}{color}* class and do not
> perform any additional checks before trusting that it is unique. This works
> great until one or more MQTT messages are not acknowledged in timely manner
> while receiving and acknowledging other messages. A different message with
> the same ID will be sent after 32767 additional messages are received and
> acknowledged.
> There are also more issues with MQTT message ID generation:
> # *AtomicInteger* is used for *ids* variable, but all accesses and
> modifications are done in synchronized context, so there is no need for it to
> be atomic.
> # Maximum allowed *ids* value before wraparound is {*}Short.MAX_VALUE{*},
> but MQTT protocol allows values in the range of 1 to 65535 (all unsigned
> short values except 0).
> # Wraparound is done to value 1 and is immediately incremented thus skipping
> message ID 1 and using 2 as first ID after wraparound.
> # There is a harmless but wrong attempt to remove from *mqttToServerIds*
> hash map by non-MQTT message ID in the following code:
> \{_}mqttToServerIds.remove(p.getA());{_}. It is harmless because _p.getA()_
> returns *Long* value and will never match any key in *mqttToServerIds* hash
> map which uses *Integer* keys.{*}{*}
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