DNS(LabelIsNotAscii)

[jedahan]

using the chromecast example but switching to compantion-link._tcp.local, some names panic. Not sure what the best course of action is, to support UTF-8 maybe?

[dylanmckay]

What error message/source location do you get from the panic?

I am surprised that UTF-8 has issues.

[LinusU]

I'm also running into this, but it's only panicing since I have an unwrap in my code though (as in the example)

thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: Error(Dns(LabelIsNotAscii)

[dylanmckay]

I suspect this will have to be fixed in the upstream dns-parser repository here.

Either:

• The mDNS servers you are connecting to are using non-ascii data for names
  • The DNS standard explicitly allows this

  • Although the Domain Name System supports non-ASCII characters, applications such as e-mail and web browsers restrict the characters which can be used as domain names for purposes such as a hostname

    • https://en.wikipedia.org/wiki/Internationalized_domain_name
• The dns-parser is incorrectly parsing the name, reading out of bounds where adjacent binary data is located

I suspect the first one is more likely.

As far as I can see in dns-parser/src/name.rs, it will always reject non-ASCII names, so perhaps the parser needs to be extended to support UTF-8 values.

[wez]

Sort of related to this, but on the other end of the spectrum; while probing for elgato lights (_elg._tcp.local), I get lots of this eprintln output happening, which is pretty undesirable:

https://github.com/dylanmckay/mdns/blob/master/src/mdns.rs#L101

LabelIsNotAscii, [<hundreds of bytes in decimal here>]

I appreciate that discovery doesn't completely give up for these because I do occasionally get proper responses from this, but I wonder if we can do something to control this unconditional output?

Two ideas come to mind:

• Adopt the log crate and log::debug these messages
• Make that stream return an enum with either a valid response or the dns_parser error

what do you think?

[wez]

I forked dns-parser to make it handle utf8 in labels and that cured my immediate problem; the commits are referenced above

[dylanmckay]

Adopt the log crate and log::debug these messages

Your wish is my command: 2.0.0...2.0.2

If you have any patches to send my way related to the other things, they are welcome :)