Gracefully handle unrecognized options in /etc/resolv.conf #52
Description
Describe the bug
hickory-dns fails fast if it sees an option it does not recognize in /etc/resolv.conf. This behaviour is problematic as this means options cannot be added to a machine unless all resolvers on the system support it.
Ideally, hickory-dns should (optionally) warn about the unrecognized option and proceed. It'd be nice for hickory-dns to support the new option I used as well but in general, being able to gracefully handle new options is the priority here :)
To Reproduce
I added an additional option no-aaaa (introduced here) to /etc/resolv.conf for glibc. This caused cargo to fail installing Rust packages as it internally uses hickory-dns.
Sample /etc/resolf.conf:
gautham@myhost:~$ cat /etc/resolv.conf
nameserver 127.0.0.1
options edns0 no-aaaa
search foo.org
Error encountered: https://github.com/hickory-dns/hickory-dns/blob/dc5627135a916d9c118b11db0c97fb19adcbe908/crates/resolver/src/system_conf/unix.rs#L40
> INFO resolve:fetch_crate_matched{crate_name="eza" registry_url=https://index.crates.io/ version_req=*}:do_send_request{request=Request { method: GET, url: Url { scheme: "https", cannot_be_a_base: false, username: "", password: None, host: Some(Domain("[index.crates.io](http://index.crates.io/)")), port: None, path: "/config.json", query: None, fragment: None }, headers: {} } url=https://index.crates.io/config.json}: Received timeout error from reqwest. Delay future request by 200ms
> ERROR Fatal error:
> × For crate eza: could not GET https://index.crates.io/config.json: error sending request
> ├─▶ could not GET https://index.crates.io/config.json: error sending request
> ├─▶ error sending request
> ├─▶ client error (Connect)
> ├─▶ tunnel error: failed to create underlying connection
> ├─▶ dns error
> ╰─▶ proto error: io error: Error parsing resolv.conf: option at line 2 is not recognized
Expected behavior
Since this is unsupported by hickory-dns, this should have printed a warning once and continued to process the request. Printing logs per query will cause spamming.
System:
- OS: Ubuntu
- Architecture: ARM
- Version: Noble