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https://issues.apache.org/jira/browse/CAMEL-26349?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Serdar Gökay reassigned CAMEL-26349:
------------------------------------
Assignee: Serdar Gökay
> camel-paho-mqtt5 - a CamelPahoMqtt5MsgProperties header shared by several
> publishes (split, multicast, loop) gets a topic alias written into it by
> Paho, so messages arrive on the wrong topic
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: CAMEL-26349
> URL: https://issues.apache.org/jira/browse/CAMEL-26349
> Project: Camel
> Issue Type: Bug
> Components: camel-paho-mqtt5
> Affects Versions: 4.23.0
> Environment: Camel 4.23.0, Eclipse Paho mqttv5 client 1.2.5,
> Mosquitto 2.0.22 (default max_topic_alias 10), JDK 25
> Reporter: Serdar Gökay
> Assignee: Serdar Gökay
> Priority: Minor
>
> An MQTT-to-MQTT route that consumes from {{paho-mqtt5}}, splits each message
> and publishes every part to its own topic with
> {{CamelPahoMqtt5OverrideTopic}} delivers some payloads on the wrong topic,
> with no error and no log line.
> The cause is one {{MqttProperties}} object used by several publishes:
> # The consumer puts the received message's {{MqttProperties}} object in the
> {{CamelPahoMqtt5MsgProperties}} header ({{PahoMqtt5Consumer.createExchange}}).
> # Split, multicast, recipient list, loop and wire tap copy header references,
> so every publish of the exchange tree sees the same object.
> # The producer passes the object from that header to
> {{MqttMessage.setProperties}} without copying it
> ({{PahoMqtt5Producer.process}}).
> # Paho 1.2.5 keeps the caller's object ({{MqttAsyncClient.publish}} creates
> {{new MqttPublish(topic, message, message.getProperties())}}) and
> {{ClientState.send}} writes the outgoing topic alias into it.
> # Once the connection has used the Topic Alias Maximum the broker granted in
> CONNACK (mosquitto default 10), {{ClientState.send}} assigns no alias for a
> new topic but does not clear the alias left by the previous publish. The
> packet goes out with the new topic name and that alias, the broker maps the
> alias to the new topic, and later alias-only publishes for the old topic are
> delivered on the new topic.
> A route that publishes once per received message is not affected, because
> each received message has its own properties object.
> Reproducer (Camel JBang 4.23.0, mosquitto 2.0.22 with its default
> configuration on port 18883), repro.camel.yaml:
> {noformat}
> - route:
> id: trigger
> from:
> uri: timer:trigger
> parameters: {period: 1000, repeatCount: 5, delay: 3000}
> steps:
> - setBody: {constant: "{{items}}"}
> - to:
> uri: "paho-mqtt5:{{root}}/in/x"
> parameters: {brokerUrl: "tcp://127.0.0.1:18883"}
> - route:
> id: relay
> from:
> uri: "paho-mqtt5:{{root}}/in/x"
> parameters: {brokerUrl: "tcp://127.0.0.1:18883"}
> steps:
> - convertBodyTo: {type: java.lang.String}
> - choice:
> when:
> - simple: "{{strip}} == true"
> steps:
> - removeHeader: {name: CamelPahoMqtt5MsgProperties}
> - split:
> tokenize: ","
> steps:
> - setHeader:
> name: CamelPahoMqtt5OverrideTopic
> simple: "{{root}}/out/${body}"
> - to:
> uri: "paho-mqtt5:{{root}}/out/unrouted"
> parameters: {brokerUrl: "tcp://127.0.0.1:18883"}
> - route:
> id: check
> from:
> uri: "paho-mqtt5:{{root}}/out/#"
> parameters: {brokerUrl: "tcp://127.0.0.1:18883"}
> steps:
> - convertBodyTo: {type: java.lang.String}
> - choice:
> when:
> - simple: "${header.CamelMqttTopic} == '{{root}}/out/${body}'"
> steps:
> - log: "RESULT OK topic=${header.CamelMqttTopic}
> body=${body}"
> otherwise:
> steps:
> - log: "RESULT MISMATCH topic=${header.CamelMqttTopic}
> body=${body}"
> {noformat}
> {noformat}
> camel run repro.camel.yaml --max-seconds=20 --prop root=check30 --prop
> items=1,2,3,...,30 --prop strip=false
> {noformat}
> Results (5 batches each; a mismatch is a payload delivered on another item's
> topic):
> ||Items per message||CamelPahoMqtt5MsgProperties||Broker
> max_topic_alias||Correct||Wrong topic||
> |30|kept|10 (default)|146|4|
> |30|removed before split|10 (default)|150|0|
> |10|kept|10 (default)|50|0|
> |11|kept|10 (default)|51|4|
> |30|kept|0|150|0|
> With 30 items, from the second batch on the payload for out/10 arrives on
> out/30, the last topic that alias 10 was mapped to.
> Affected: 4.7.0 (CAMEL-20754) up to 4.23.0 and main.
> Suggested fix: the producer builds a new {{MqttProperties}} with only the
> publish properties from the header (payload format indicator, message expiry
> interval, content type, response topic, correlation data, user properties)
> and leaves out the topic alias, which belongs to one connection, and
> subscription identifiers, which a client must not send (MQTT 5 section
> 3.3.4). {{MqttProperties}} has no copy constructor, so the copy is field by
> field.
> Workaround: remove the {{CamelPahoMqtt5MsgProperties}} header before
> publishing, or disable topic aliases on the broker.
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