small improvements

[fopina]

I've opened this to portswigger's fork of yours - PortSwigger#2

In case you want to merge them sooner :) (and care to comment as you're actually the developer and I only noticed after opening the PR)

[dnet]

I like the invalid port, but what's the purpose/advantage of the test without lookups?

[fopina]

Include test without any lookups: in some setups, some lookups fail. to avoid missing true positives, add one iteration without any

quote from the other PR.
in some scenarios the hostName (and many other lookups) fail.

so far, I’ve seen the env:USER as the one that always works, but I rather do a blank test without any to flag it vulnerable at least.

Hostname extraction can easily be done after, if it works.

not sure about reasons for failed hostnams (yet), but I assume either weird hostnames that are not allowed//complaint dns requests or some different log4j version..