Unable to Close TCP Client Connection about tokio-modbus

[flosse]

@DBTaylor Thanks for your feedback.
We'll try to reproduce this soon.
Probably this issue is related to the outdated tokio-proto crate (see #18).
The next version of tokio-modbus will definitely get rid of it and will use the new async/await features of Rust. So if you're interested to help feel free to contact us :)

[flosse]

@uklotzde If you're bored: can you have a look at this?

[DBTaylor]

@flosse Thanks for the quick response. Monday I'll put together a minimal program that reproduces this - I'll also check it on a Tier 1 target to make sure it's not a target specific issue. Glad to hear async/await support is coming - way easier to read than future combinators. I would totally help if I had any idea what I was doing.

[DBTaylor]

@flosse here is a reproduction: https://github.com/DBTaylor/modbus-tcp-leak

It appears to be target agnostic. This issue sounds related, but it appears to have been fixed:
tokio-rs/tokio-proto#194

[flosse]

@DBTaylor Thanks for the example repo. I can reproduce the behavior on my machine.

I tried to build it with the current tokio-proto master but unfortunately it's still the same :(

[uklotzde]

I've prepared a quick fix:

#34

[patch.crates-io]
tokio-modbus = { git = "https://github.com/uklotzde/tokio-modbus.git", branch = "tcp_disconnect" }

After invoking disconnect() the connections will enter TIME_WAIT and should disappear after ~30 seconds (depending on your config). Does this solve your issues?

[DBTaylor]

@uklotzde yep that works!

[uklotzde]

Great, I will prepare a release.

Your example with the testing instructions was a great help to quickly solve this bug!