RestClient does not suppport _ in url

[Kizoku-Dev]

Describe the bug

I configured the base url through the application.yml. My url is working as I can request it through postman for exemple.
The URL is : http://test.some_url.domain.com
As you can see there is an _ in the URL. If I run the app with this when I try to make a call through the rest client, it try to connect to locahost instead of my URL.
But when I try an URL without _ or when I call my rest service through the IP instead of the URL it works.

Expected behavior

Rest client connect to my URL in order to process my call.

Actual behavior

Rest client try to connect to localhost.

How to Reproduce?

No response

Output of uname -a or ver

No response

Output of java -version

No response

GraalVM version (if different from Java)

No response

Quarkus version or git rev

2.15.3

Build tool (ie. output of mvnw --version or gradlew --version)

No response

Additional information

When I use the URL with an _ I can see that my rest client is build with the URL in its authority field.

When I use the URL without an _ or with an IP I can see that my rest client is build with the URL in its host field.

[geoand]

Very interesting...

We'll take a look soon

[quarkus-bot]

/cc @Sgitario (rest-client), @cescoffier (rest-client)

[gsmet]

Hmmm, is _ actually valid in domain names?

[geoand]

I'm looking into that now

[geoand]

It appears that host names are limited to letters-digits-hyphen according to RFC 1123, section 2.1 "Host Names and Numbers".

[gsmet]

I'm not saying we should fix this but the error we throw is a bit weird to me.

@Kizoku-Dev if you provide a small reproducer, I will have a look at trying to improve the user feedback.

[gsmet]

My guess is that you should have a better error message with the following PR: #30490 .

I'm closing this. If you can come up with a small reproducer, please attach it so I can make sure the error message is now actionable.