Port numbers with 5+ digits get truncated

[jimmy-mcelwain]

See #374 (reply in thread)

Port numbers with 5 or more digits get truncated when trying to connect.

If I have a valid port in the config file 16510, I would have to connect to 1651 on the docker side. If I specify port 88888 in the config file (I am aware that this is not a valid port), then I can still connect properly if I specify port 8888 when I start the docker container.

This is a problem if a user puts a valid 5 digit port number in the config file.

That is caused by this line upstream here. MAX_PORT_LEN is set to 5, but in reality snprintf is truncating at 4 so it has space to put the null character. I haven't looked anywhere yet to see if this is an intentional design choice, but I doubt that it is. I can look more into it soon.

[jimmy-mcelwain]

Opened an issue micro-ROS/rmw_microxrcedds#314.

For the time being should we validate the port manually? Even if it gets fixed upstream it might be a long time before it makes its way here.

Less important/maybe we shouldn't do this, but we could also set an alarm if the port is < 1024 since those are the well known ports and usually aren't recommended for developers.

[jimmy-mcelwain]

A fix was merged upstream micro-ROS/rmw_microxrcedds#315. It might be a while before it makes its way into a release, though. Not sure what the best option for us is, for now.

[ted-miller]

I think we should just wait for the next release/tag on their end. It looks like it'll happen in May/June. (https://github.com/micro-ROS/rmw_microxrcedds/tags) The easy fix in the meantime is to use the suggested port that we provide in the yaml file.

[gavanderhoorn]

It would not be much work bumping rmw_microxrcedds to include the fix and use it as part of libmicroros. We could also wait for a release upstream and then bump on our side.

We'd need another release of MotoROS2 though to get that fix included.