net/url: should Parse accept hostnames with leading hyphens?

[xeoncross]

What version of Go are you using (go version)?

go version go1.7.4 darwin/amd64

What did you do?

I have tested with multiple invalid strings and found that url.Parse() and url.ParseRequestURI() allow invalid URL strings without an error.

u, err := url.Parse("http://-10:10/foobar")

https://play.golang.org/p/_qvse6f4C9

What did you expect to see?

An Error. -10:10 is not a URL, an IP 4/6, or a CIDR.

What did you see instead?

net/url allows invalid hostnames

[bradfitz]

This looks like a joke or meme instead of a bug report.

Feel free to re-file if you want to be serious.

[xeoncross]

I removed the photo. I don't think a new issue is needed. I'll just leave this here for future google searches.

[bradfitz]

So the question is whether url.Parse should be strict about enforcing that a DNS name can't begin with a hyphen (and can only contain hyphens in the middle/end)?

But those rules only apply to certain schemes.

The URL spec (RFC 3986) says:

      host        = IP-literal / IPv4address / reg-name
...
   reg-name      = *( unreserved / pct-encoded / sub-delims )
...
   unreserved    = ALPHA / DIGIT / "-" / "." / "_" / "~"

So it seems like hyphens are valid anywhere.

Do you have a counterargument?

[xeoncross]

No counterargument.