Fix MQTT client ID mapping in MqttBackend (and derived classes) #15

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opened 2022-07-05 01:38:39 +02:00 by blacklight · 0 comments

blacklight commented

2022-07-05 01:38:39 +02:00

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MqttBackend._get_client currently stores listeners in a <host, port, handler_id> mapping.

The problem with this approach is that client_id defaults to the current device/host name.

This means that two listeners that point to the same MQTT broker but subscribe to different sets of channels will have a client ID collision.

In order to prevent this issue, we need to generate a different client ID if a <host, port> pair already exists.

[`MqttBackend._get_client`](https://git.platypush.tech/platypush/platypush/-/blob/master/platypush/backend/mqtt/__init__.py#L258) currently stores listeners in a `<host, port, handler_id>` mapping. The problem with this approach is that `client_id` defaults to the current device/host name. This means that two listeners that point to the same MQTT broker but subscribe to different sets of channels will have a client ID collision. In order to prevent this issue, we need to generate a different client ID if a `<host, port>` pair already exists.