ensure syslog parser gets an EOF-terminated reader on udp receive

[joshuapare]

PR Description

Simple fix to convert the incoming datagram into a bytes reader that the ParseStream can handle. currently it freezes up because the datagrams are sent as is without separation so the reader routine blocks until an interrupt.

Which issue(s) this PR fixes

Fixes #5197

PR Checklist

• CHANGELOG.md updated
• Tests updated

[tpaschalis]

cc @erikbaranowski do I correctly remember you'd investigated this issue in the past? Could you take a look here?

[erikbaranowski]

This looks good. @joshuapare can we add a test to syslogtarget_test.go to demonstrate the scenario that is now working with this fix?

[rfratto]

@joshuapare Do you still have time to work on this? It looks like all we need is a test for the fix, and then this is good to be merged :)

This looks good. @joshuapare can we add a test to syslogtarget_test.go to demonstrate the scenario that is now working with this fix?

[rfratto]

I looked through the existing code, and I think there's enough tests to prove that this doesn't break anything, even if we don't have a test for testing this specific case, I think we can just merge this for now. If it breaks again we'll want a regression test for sure.

[erikbaranowski]

seconded @rfratto. let's get this fix out and give it a try.