const USAGE: &'static str = "Usage: wrong-dns [@ipv4-server] RTYPE...

const USAGE: &str = "Usage: wrong-dns [@ipv4-server|@[ipv6-server]] RTYPE...

Port is always udp/53. Default server is CloudFlare 1.1.1.3.";

Port is always udp/53. Default server is CloudFlare 1.1.1.3";

    for rtype in args.rtypes.into_iter() {
        let q = naughty_question(rtype);
        assert!(resolv.query(q).await.is_err());

    for rtype in args.rtypes {
        print!("{rtype}: ");
        let q = naughty_question(&rtype);
        let res = resolv.query(q).await;
        match res {
            Err(e) if e.kind() == tokio::io::ErrorKind::TimedOut => {
                println!("server ignored us!")
            }
            Err(e) => Err(e)?,
            Ok(answer) => {
                println!("{:?}", answer.as_octets())
            }
        };

fn naughty_question(qtype: Rtype) -> Question<Dname<Vec<u8>>> {

fn naughty_question(qtype: &Rtype) -> Question<Dname<Vec<u8>>> {

        qtype,

        qtype.clone(),

#[test]
fn it_is_different() {
    assert!(
        !Question::from((Dname::vec_from_str("example.").unwrap(), Rtype::Any))
            .eq(&naughty_question(&Rtype::Any))
    );
}

                if val.starts_with('@') {
                    server = val[1..].into();

                if let Some(ip) = val.strip_prefix('@') {
                    server = ip.to_string();

There seems to be a defect-attractor in DNS-packet construction. When people writes `.`-ending in a DNS name in config (eg in order to avoid search-suffix behaviour), some software will construct an invalid DNS question:

There is a defect-attractor in DNS-packet construction. When people writes `.`-ending in a DNS name in config (eg in order to avoid search-suffix behaviour), some software will construct an invalid DNS question:

-  haproxy < 1.8
-  gnupg dirmngr
-  nongnu LWIP

-  haproxy, before 2020 https://github.com/haproxy/haproxy/issues/435
-  gnupg dirmngr, in 2017 https://dev.gnupg.org/T3517#106524
-  nongnu LWIP, in 2020 https://savannah.nongnu.org/bugs/?58473#comment3

For more background, https://jvns.ca/blog/2022/09/12/why-do-domain-names-end-with-a-dot-/
There is a different case from 2001, where a (windows-based?) client sent TYPE & CLASS as little-endian, not big-endian, giving TYPE256 CLASS256 https://groups.google.com/g/comp.protocols.dns.bind/c/pIVLil7p8wA/m/Y0bxMyn5bI0J

> a single ping, comrade. just one, for range. -- Marko Ramius
Catching in wireshark/tshark:
`dns.qry.class > 1`
In tcpdump
`udp port 53 and dns.query.class > 1`?

#[test]
fn it_is_different() {
    assert!(
        !Question::from((Dname::vec_from_str("example.").unwrap(), Rtype::Any))
            .eq(&naughty_question(Rtype::Any))
    );
}

I chose NLnet's `domain` crate, because it is self-contained, comes

I chose NLnet Labs' `domain` crate, because it is self-contained, comes

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bind9 and cloudflare DNS servers, quad-9, ???, ??? politely return `Not Implemented`, while `resolved`, google dns, adguard