arsing / mqtt Goto Github PK

Currently all encoding errors are fatal client errors, so packets that can't be encoded because their payloads are too large, etc will kill the Client.

• For publish requests, the payload might be too large, so use the ack sender to send back a PublishError::PayloadTooLarge error. The other EncodeError errors can't happen.

• For (un)subscription requests, the topic filter string can be too large, so send back a SubscriptionError::TopicFilterTooLarge error. The other EncodeError errors can't happen.

• For (un)subscription packets in general, the payload can be too large if there are a lot of subscriptions or long subscriptions. The Client should split them up into multiple packets in this case. The other EncodeError errors shouldn't happen.

• For CONNECT packets, the username / password / will might be too large, or the keep-alive time could be too high. Return an error from the Client::new constructor.

Currently the Client uses a Framed to encode the packet. Detecting and handling these errors probably means the packets have to be encoded proactively by the inner clients (client::publish, client::subscriptions) so that they can send back an error / split the packets. So it probably can't continue using a Framed.