Files
nym/common/http-api-client/src/dns.rs
T

776 lines
27 KiB
Rust

// Copyright 2023 - Nym Technologies SA <contact@nymtech.net>
// SPDX-License-Identifier: Apache-2.0
//! DNS resolver configuration for internal lookups.
//!
//! The resolver itself is the set combination of the cloudflare, and quad9 endpoints supporting DoH
//! and DoT.
//!
//! ```rust
//! use nym_http_api_client::HickoryDnsResolver;
//! # use nym_http_api_client::ResolveError;
//! # type Err = ResolveError;
//! # async fn run() -> Result<(), Err> {
//! let resolver = HickoryDnsResolver::default();
//! resolver.resolve_str("example.com").await?;
//! # Ok(())
//! # }
//! ```
//!
//! ## Fallbacks
//!
//! **System Resolver --** This resolver supports an optional fallback mechanism where, should the
//! DNS-over-TLS resolution fail, a followup resolution will be done using the hosts configured
//! default (e.g. `/etc/resolve.conf` on linux).
//!
//! This is disabled by default and can be enabled using `enable_system_fallback`.
//!
//! **Static Table --** There is also a second optional fallback mechanism that allows a static map
//! to be used as a last resort. This can help when DNS encounters errors due to blocked resolvers
//! or unknown conditions. This is enabled by default, and can be customized if building a new
//! resolver.
//!
//! ## IPv4 / IPv6
//!
//! By default the resolver uses only IPv4 nameservers, and is configured to do `A` lookups first,
//! and only do `AAAA` if no `A` record is available.
//!
//! ---
//!
//! Requires the `dns-over-https-rustls`, `webpki-roots` feature for the `hickory-resolver` crate
#![deny(missing_docs)]
use crate::ClientBuilder;
use std::{
collections::HashMap,
net::{IpAddr, SocketAddr},
str::FromStr,
sync::{Arc, LazyLock},
time::Duration,
};
use hickory_resolver::{
TokioResolver,
config::{NameServerConfig, NameServerConfigGroup, ResolverConfig, ResolverOpts},
lookup_ip::LookupIpIntoIter,
name_server::TokioConnectionProvider,
};
use once_cell::sync::OnceCell;
use reqwest::dns::{Addrs, Name, Resolve, Resolving};
use tracing::*;
mod constants;
mod static_resolver;
pub(crate) use static_resolver::*;
pub(crate) const DEFAULT_POSITIVE_LOOKUP_CACHE_TTL: Duration = Duration::from_secs(1800);
pub(crate) const DEFAULT_OVERALL_LOOKUP_TIMEOUT: Duration = Duration::from_secs(10);
pub(crate) const DEFAULT_QUERY_TIMEOUT: Duration = Duration::from_secs(5);
impl ClientBuilder {
/// Override the DNS resolver implementation used by the underlying http client.
pub fn dns_resolver<R: Resolve + 'static>(mut self, resolver: Arc<R>) -> Self {
self.reqwest_client_builder = self.reqwest_client_builder.dns_resolver(resolver);
self.use_secure_dns = false;
self
}
/// Override the DNS resolver implementation used by the underlying http client.
pub fn no_hickory_dns(mut self) -> Self {
self.use_secure_dns = false;
self
}
}
// n.b. static items do not call [`Drop`] on program termination, so this won't be deallocated.
// this is fine, as the OS can deallocate the terminated program faster than we can free memory
// but tools like valgrind might report "memory leaks" as it isn't obvious this is intentional.
static SHARED_RESOLVER: LazyLock<HickoryDnsResolver> = LazyLock::new(|| {
tracing::debug!("Initializing shared DNS resolver");
HickoryDnsResolver {
use_shared: false, // prevent infinite recursion
..Default::default()
}
});
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
/// Error occurring while resolving a hostname into an IP address.
pub enum ResolveError {
#[error("invalid name: {0}")]
InvalidNameError(String),
#[error("hickory-dns resolver error: {0}")]
ResolveError(#[from] hickory_resolver::ResolveError),
#[error("high level lookup timed out")]
Timeout,
#[error("hostname not found in static lookup table")]
StaticLookupMiss,
}
impl ResolveError {
/// Returns true if the error is a timeout.
pub fn is_timeout(&self) -> bool {
matches!(self, ResolveError::Timeout)
}
}
/// Wrapper around an `AsyncResolver`, which implements the `Resolve` trait.
///
/// Typical use involves instantiating using the `Default` implementation and then resolving using
/// methods or trait implementations.
///
/// The default initialization uses a shared underlying `AsyncResolver`. If a thread local resolver
/// is required use `thread_resolver()` to build a resolver with an independently instantiated
/// internal `AsyncResolver`.
#[derive(Debug, Clone)]
pub struct HickoryDnsResolver {
// Since we might not have been called in the context of a
// Tokio Runtime in initialization, so we must delay the actual
// construction of the resolver.
state: Arc<OnceCell<TokioResolver>>,
fallback: Option<Arc<OnceCell<TokioResolver>>>,
static_base: Option<Arc<OnceCell<StaticResolver>>>,
use_shared: bool,
/// Overall timeout for dns lookup associated with any individual host resolution. For example,
/// use of retries, server_ordering_strategy, etc. ends absolutely if this timeout is reached.
overall_dns_timeout: Duration,
}
impl Default for HickoryDnsResolver {
fn default() -> Self {
Self {
state: Default::default(),
fallback: Default::default(),
static_base: Some(Default::default()),
use_shared: true,
overall_dns_timeout: DEFAULT_OVERALL_LOOKUP_TIMEOUT,
}
}
}
impl Resolve for HickoryDnsResolver {
fn resolve(&self, name: Name) -> Resolving {
let resolver = self.state.clone();
let maybe_fallback = self.fallback.clone();
let maybe_static = self.static_base.clone();
let use_shared = self.use_shared;
let overall_dns_timeout = self.overall_dns_timeout;
Box::pin(async move {
resolve(
name,
resolver,
maybe_fallback,
maybe_static,
use_shared,
overall_dns_timeout,
)
.await
.map_err(|e| Box::new(e) as Box<dyn std::error::Error + Send + Sync>)
})
}
}
async fn resolve(
name: Name,
resolver: Arc<OnceCell<TokioResolver>>,
maybe_fallback: Option<Arc<OnceCell<TokioResolver>>>,
maybe_static: Option<Arc<OnceCell<StaticResolver>>>,
independent: bool,
overall_dns_timeout: Duration,
) -> Result<Addrs, ResolveError> {
let resolver = resolver.get_or_init(|| HickoryDnsResolver::new_resolver(independent));
// try checking the static table to see if any of the addresses in the table have been
// looked up previously within the timeout to where we are not yet ready to try the
// default resolver yet again.
if let Some(ref static_resolver) = maybe_static {
let resolver =
static_resolver.get_or_init(|| HickoryDnsResolver::new_static_fallback(independent));
if let Some(addrs) = resolver.pre_resolve(name.as_str()) {
let addrs: Addrs =
Box::new(addrs.into_iter().map(|ip_addr| SocketAddr::new(ip_addr, 0)));
return Ok(addrs);
}
}
// Attempt a lookup using the primary resolver
let resolve_fut = tokio::time::timeout(overall_dns_timeout, resolver.lookup_ip(name.as_str()));
let primary_err = match resolve_fut.await {
Err(_) => ResolveError::Timeout,
Ok(Ok(lookup)) => {
let addrs: Addrs = Box::new(SocketAddrs {
iter: lookup.into_iter(),
});
return Ok(addrs);
}
Ok(Err(e)) => {
// on failure use the fall back system configured DNS resolver
if !e.is_no_records_found() {
warn!("primary DNS failed w/ error: {e}");
}
e.into()
}
};
// If the primary resolver encountered an error, attempt a lookup using the fallback
// resolver if one is configured.
if let Some(ref fallback) = maybe_fallback {
let resolver =
fallback.get_or_try_init(|| HickoryDnsResolver::new_resolver_system(independent))?;
let resolve_fut =
tokio::time::timeout(overall_dns_timeout, resolver.lookup_ip(name.as_str()));
if let Ok(Ok(lookup)) = resolve_fut.await {
let addrs: Addrs = Box::new(SocketAddrs {
iter: lookup.into_iter(),
});
return Ok(addrs);
}
}
// If no record has been found and a static map of fallback addresses is configured
// check the table for our entry
if let Some(ref static_resolver) = maybe_static {
debug!("checking static");
let resolver =
static_resolver.get_or_init(|| HickoryDnsResolver::new_static_fallback(independent));
if let Ok(addrs) = resolver.resolve(name).await {
return Ok(addrs);
}
}
Err(primary_err)
}
struct SocketAddrs {
iter: LookupIpIntoIter,
}
impl Iterator for SocketAddrs {
type Item = SocketAddr;
fn next(&mut self) -> Option<Self::Item> {
self.iter.next().map(|ip_addr| SocketAddr::new(ip_addr, 0))
}
}
impl HickoryDnsResolver {
/// Attempt to resolve a domain name to a set of ['IpAddr']s
pub async fn resolve_str(
&self,
name: &str,
) -> Result<impl Iterator<Item = IpAddr> + use<>, ResolveError> {
let n =
Name::from_str(name).map_err(|_| ResolveError::InvalidNameError(name.to_string()))?;
resolve(
n,
self.state.clone(),
self.fallback.clone(),
self.static_base.clone(),
self.use_shared,
self.overall_dns_timeout,
)
.await
.map(|addrs| addrs.map(|socket_addr| socket_addr.ip()))
}
/// Create a (lazy-initialized) resolver that is not shared across threads.
pub fn thread_resolver() -> Self {
Self {
use_shared: false,
..Default::default()
}
}
fn new_resolver(use_shared: bool) -> TokioResolver {
// using a closure here is slightly gross, but this makes sure that if the
// lazy-init returns an error it can be handled by the client
if use_shared {
SHARED_RESOLVER.state.get_or_init(new_resolver).clone()
} else {
new_resolver()
}
}
fn new_resolver_system(use_shared: bool) -> Result<TokioResolver, ResolveError> {
// using a closure here is slightly gross, but this makes sure that if the
// lazy-init returns an error it can be handled by the client
if !use_shared || SHARED_RESOLVER.fallback.is_none() {
new_resolver_system()
} else {
Ok(SHARED_RESOLVER
.fallback
.as_ref()
.unwrap()
.get_or_try_init(new_resolver_system)?
.clone())
}
}
fn new_static_fallback(use_shared: bool) -> StaticResolver {
if use_shared && let Some(ref shared_resolver) = SHARED_RESOLVER.static_base {
shared_resolver
.get_or_init(new_default_static_fallback)
.clone()
} else {
new_default_static_fallback()
}
}
/// Enable fallback to the system default resolver if the primary (DoX) resolver fails
pub fn enable_system_fallback(&mut self) -> Result<(), ResolveError> {
self.fallback = Some(Default::default());
let _ = self
.fallback
.as_ref()
.unwrap()
.get_or_try_init(new_resolver_system)?;
// IF THIS INSTANCE IS A FRONT FOR THE SHARED RESOLVER SHOULDN'T THIS FN ENABLE THE SYSTEM FALLBACK FOR THE SHARED RESOLVER TOO?
// if self.use_shared {
// SHARED_RESOLVER.enable_system_fallback()?;
// }
Ok(())
}
/// Disable fallback resolution. If the primary resolver fails the error is
/// returned immediately
pub fn disable_system_fallback(&mut self) {
self.fallback = None;
// // IF THIS INSTANCE IS A FRONT FOR THE SHARED RESOLVER SHOULDN'T THIS FN ENABLE THE SYSTEM FALLBACK FOR THE SHARED RESOLVER TOO?
// if self.use_shared {
// SHARED_RESOLVER.fallback = None;
// }
}
/// Get the current map of hostname to address in use by the fallback static lookup if one
/// exists.
pub fn get_static_fallbacks(&self) -> Option<HashMap<String, Vec<IpAddr>>> {
Some(self.static_base.as_ref()?.get()?.get_addrs())
}
/// Set (or overwrite) the map of addresses used in the fallback static hostname lookup
pub fn set_static_fallbacks(&mut self, addrs: HashMap<String, Vec<IpAddr>>) {
let cell = OnceCell::new();
cell.set(StaticResolver::new(addrs))
.expect("infallible assign");
self.static_base = Some(Arc::new(cell));
}
/// Successfully resolved addresses are cached for a minimum of 30 minutes
/// Individual lookup Timeouts are set to 3 seconds
/// Number of retries after lookup failure before giving up is set to (default) to 2
/// Lookup order is set to (default) A then AAAA
/// Number or parallel lookup is set to (default) 2
/// Nameserver selection uses the (default) EWMA statistics / performance based strategy
fn default_options() -> ResolverOpts {
let mut opts = ResolverOpts::default();
// Always cache successful responses for queries received by this resolver for 30 min minimum.
opts.positive_min_ttl = Some(DEFAULT_POSITIVE_LOOKUP_CACHE_TTL);
opts.timeout = DEFAULT_QUERY_TIMEOUT;
opts.attempts = 0;
opts
}
/// Get the list of currently available nameserver configs.
pub fn all_configured_name_servers(&self) -> Vec<NameServerConfig> {
default_nameserver_group().to_vec()
}
/// Get the list of currently used nameserver configs.
pub fn active_name_servers(&self) -> Vec<NameServerConfig> {
if !self.use_shared {
return self
.state
.get()
.map(|r| r.config().name_servers().to_vec())
.unwrap_or(self.all_configured_name_servers());
}
SHARED_RESOLVER.active_name_servers()
}
/// Do a trial resolution using each nameserver individually to test which are working and which
/// fail to complete a lookup. This will always try the full set of default configured resolvers.
pub async fn trial_nameservers(&self) {
let nameservers = default_nameserver_group();
for (ns, result) in trial_nameservers_inner(&nameservers).await {
if let Err(e) = result {
warn!("trial {ns:?} errored: {e}");
} else {
info!("trial {ns:?} succeeded");
}
}
}
}
/// Create a new resolver with a custom DoT based configuration. The options are overridden to look
/// up for both IPv4 and IPv6 addresses to work with "happy eyeballs" algorithm.
///
/// Individual lookup Timeouts are set to 3 seconds
/// Number of retries after lookup failure before giving up Defaults to 2
/// Lookup order is set to (default) A then AAAA
///
/// Caches successfully resolved addresses for 30 minutes to prevent continual use of remote lookup.
/// This resolver is intended to be used for OUR API endpoints that do not rapidly rotate IPs.
fn new_resolver() -> TokioResolver {
let name_servers = default_nameserver_group_ipv4_only();
configure_and_build_resolver(name_servers)
}
fn configure_and_build_resolver<G>(name_servers: G) -> TokioResolver
where
G: Into<NameServerConfigGroup>,
{
let options = HickoryDnsResolver::default_options();
let name_servers: NameServerConfigGroup = name_servers.into();
info!("building new configured resolver");
debug!("configuring resolver with {options:?}, {name_servers:?}");
let config = ResolverConfig::from_parts(None, Vec::new(), name_servers);
let mut resolver_builder =
TokioResolver::builder_with_config(config, TokioConnectionProvider::default());
resolver_builder = resolver_builder.with_options(options);
resolver_builder.build()
}
fn filter_ipv4(nameservers: impl AsRef<[NameServerConfig]>) -> Vec<NameServerConfig> {
nameservers
.as_ref()
.iter()
.filter(|ns| ns.socket_addr.is_ipv4())
.cloned()
.collect()
}
#[allow(unused)]
fn filter_ipv6(nameservers: impl AsRef<[NameServerConfig]>) -> Vec<NameServerConfig> {
nameservers
.as_ref()
.iter()
.filter(|ns| ns.socket_addr.is_ipv6())
.cloned()
.collect()
}
#[allow(unused)]
fn default_nameserver_group() -> NameServerConfigGroup {
let mut name_servers = NameServerConfigGroup::quad9_tls();
name_servers.merge(NameServerConfigGroup::quad9_https());
name_servers.merge(NameServerConfigGroup::cloudflare_tls());
name_servers.merge(NameServerConfigGroup::cloudflare_https());
name_servers
}
fn default_nameserver_group_ipv4_only() -> NameServerConfigGroup {
filter_ipv4(&default_nameserver_group() as &[NameServerConfig]).into()
}
#[allow(unused)]
fn default_nameserver_group_ipv6_only() -> NameServerConfigGroup {
filter_ipv6(&default_nameserver_group() as &[NameServerConfig]).into()
}
/// Create a new resolver with the default configuration, which reads from the system DNS config
/// (i.e. `/etc/resolve.conf` in unix). The options are overridden to look up for both IPv4 and IPv6
/// addresses to work with "happy eyeballs" algorithm.
fn new_resolver_system() -> Result<TokioResolver, ResolveError> {
let mut resolver_builder = TokioResolver::builder_tokio()?;
let options = HickoryDnsResolver::default_options();
info!("building new fallback system resolver");
debug!("fallback system resolver with {options:?}");
resolver_builder = resolver_builder.with_options(options);
Ok(resolver_builder.build())
}
fn new_default_static_fallback() -> StaticResolver {
StaticResolver::new(constants::default_static_addrs())
}
/// Do a trial resolution using each nameserver individually to test which are working and which
/// fail to complete a lookup.
async fn trial_nameservers_inner(
name_servers: &[NameServerConfig],
) -> Vec<(NameServerConfig, Result<(), ResolveError>)> {
let mut trial_lookups = tokio::task::JoinSet::new();
for name_server in name_servers {
let ns = name_server.clone();
trial_lookups.spawn(async { (ns.clone(), trial_lookup(ns, "example.com").await) });
}
trial_lookups.join_all().await
}
/// Create an independent resolver that has only the provided nameserver and do one lookup for the
/// provided query target.
async fn trial_lookup(name_server: NameServerConfig, query: &str) -> Result<(), ResolveError> {
debug!("running ns trial {name_server:?} query={query}");
let resolver = configure_and_build_resolver(vec![name_server]);
match tokio::time::timeout(DEFAULT_OVERALL_LOOKUP_TIMEOUT, resolver.ipv4_lookup(query)).await {
Ok(Ok(_)) => Ok(()),
Ok(Err(e)) => Err(e.into()),
Err(_) => Err(ResolveError::Timeout),
}
}
#[cfg(test)]
mod test {
use super::*;
use itertools::Itertools;
use std::collections::HashMap;
use std::{
net::{IpAddr, Ipv4Addr, Ipv6Addr},
time::Instant,
};
/// IP addresses guaranteed to fail attempts to resolve
///
/// Addresses drawn from blocks set off by RFC5737 (ipv4) and RFC3849 (ipv6)
const GUARANTEED_BROKEN_IPS_1: &[IpAddr] = &[
IpAddr::V4(Ipv4Addr::new(192, 0, 2, 1)),
IpAddr::V4(Ipv4Addr::new(198, 51, 100, 1)),
IpAddr::V6(Ipv6Addr::new(0x2001, 0x0db8, 0, 0, 0, 0, 0, 0x1111)),
IpAddr::V6(Ipv6Addr::new(0x2001, 0x0db8, 0, 0, 0, 0, 0, 0x1001)),
];
#[tokio::test]
async fn reqwest_with_custom_dns() {
let var_name = HickoryDnsResolver::default();
let resolver = var_name;
let client = reqwest::ClientBuilder::new()
.dns_resolver(resolver)
.build()
.unwrap();
let resp = client
.get("http://ifconfig.me:80")
.send()
.await
.unwrap()
.bytes()
.await
.unwrap();
assert!(!resp.is_empty());
}
#[tokio::test]
async fn dns_lookup() -> Result<(), ResolveError> {
let resolver = HickoryDnsResolver::default();
let domain = "ifconfig.me";
let addrs = resolver.resolve_str(domain).await?;
assert!(addrs.into_iter().next().is_some());
Ok(())
}
#[tokio::test]
async fn static_resolver_as_fallback() -> Result<(), ResolveError> {
let example_domain = "non-existent.nymvpn.com";
let mut resolver = HickoryDnsResolver {
..Default::default()
};
let result = resolver.resolve_str(example_domain).await;
assert!(result.is_err()); // should be NXDomain
resolver.static_base = Some(Default::default());
let mut addr_map = HashMap::new();
let example_ip4: IpAddr = "10.10.10.10".parse().unwrap();
let example_ip6: IpAddr = "dead::beef".parse().unwrap();
addr_map.insert(example_domain.to_string(), vec![example_ip4, example_ip6]);
resolver.set_static_fallbacks(addr_map);
let mut addrs = resolver.resolve_str(example_domain).await?;
assert!(addrs.contains(&example_ip4));
assert!(addrs.contains(&example_ip6));
Ok(())
}
// Test the nameserver trial functionality with mostly nameservers guaranteed to be broken and
// one that should work.
#[tokio::test]
async fn trial_nameservers() {
let good_cf_ip = IpAddr::V4(Ipv4Addr::new(1, 1, 1, 1));
let mut ns_ips = GUARANTEED_BROKEN_IPS_1.to_vec();
ns_ips.push(good_cf_ip);
let broken_ns_https = NameServerConfigGroup::from_ips_https(
&ns_ips,
443,
"cloudflare-dns.com".to_string(),
true,
);
let inner = configure_and_build_resolver(broken_ns_https);
// create a new resolver that won't mess with the shared resolver used by other tests
let resolver = HickoryDnsResolver {
use_shared: false,
state: Arc::new(OnceCell::with_value(inner)),
static_base: Some(Default::default()),
..Default::default()
};
let name_servers = resolver.state.get().unwrap().config().name_servers();
for (ns, result) in trial_nameservers_inner(name_servers).await {
if ns.socket_addr.ip() == good_cf_ip {
assert!(result.is_ok())
} else {
assert!(result.is_err())
}
}
}
mod failure_test {
use super::*;
// Create a resolver that behaves the same as the custom configured router, except for the fact
// that it is guaranteed to fail.
fn build_broken_resolver() -> Result<TokioResolver, ResolveError> {
info!("building new faulty resolver");
let mut broken_ns_group = NameServerConfigGroup::from_ips_tls(
GUARANTEED_BROKEN_IPS_1,
853,
"cloudflare-dns.com".to_string(),
true,
);
let broken_ns_https = NameServerConfigGroup::from_ips_https(
GUARANTEED_BROKEN_IPS_1,
443,
"cloudflare-dns.com".to_string(),
true,
);
broken_ns_group.merge(broken_ns_https);
Ok(configure_and_build_resolver(broken_ns_group))
}
#[tokio::test]
async fn dns_lookup_failures() -> Result<(), ResolveError> {
let time_start = std::time::Instant::now();
let r = OnceCell::new();
r.set(build_broken_resolver().expect("failed to build resolver"))
.expect("broken resolver init error");
// create a new resolver that won't mess with the shared resolver used by other tests
let resolver = HickoryDnsResolver {
use_shared: false,
state: Arc::new(r),
overall_dns_timeout: Duration::from_secs(5),
..Default::default()
};
build_broken_resolver()?;
let domain = "ifconfig.me";
let result = resolver.resolve_str(domain).await;
assert!(result.is_err_and(|e| matches!(e, ResolveError::Timeout)));
let duration = time_start.elapsed();
assert!(duration < resolver.overall_dns_timeout + Duration::from_secs(1));
Ok(())
}
#[tokio::test]
async fn fallback_to_static() -> Result<(), ResolveError> {
let r = OnceCell::new();
r.set(build_broken_resolver().expect("failed to build resolver"))
.expect("broken resolver init error");
// create a new resolver that won't mess with the shared resolver used by other tests
let resolver = HickoryDnsResolver {
use_shared: false,
state: Arc::new(r),
static_base: Some(Default::default()),
overall_dns_timeout: Duration::from_secs(5),
..Default::default()
};
build_broken_resolver()?;
// successful lookup using fallback to static resolver
let domain = "nymvpn.com";
let _ = resolver
.resolve_str(domain)
.await
.expect("failed to resolve address in static lookup");
// unsuccessful lookup - primary times out, and not in static table
let domain = "non-existent.nymtech.net";
let result = resolver.resolve_str(domain).await;
assert!(result.is_err_and(|e| matches!(e, ResolveError::Timeout)));
Ok(())
}
#[test]
fn default_resolver_uses_ipv4_only_nameservers() {
let resolver = HickoryDnsResolver::thread_resolver();
resolver
.active_name_servers()
.iter()
.all(|cfg| cfg.socket_addr.is_ipv4());
SHARED_RESOLVER
.active_name_servers()
.iter()
.all(|cfg| cfg.socket_addr.is_ipv4());
}
#[tokio::test]
#[ignore]
// this test is dependent of external network setup -- i.e. blocking all traffic to the default
// resolvers. Otherwise the default resolvers will succeed without using the static fallback,
// making the test pointless
async fn dns_lookup_failure_on_shared() -> Result<(), ResolveError> {
let time_start = Instant::now();
let r = OnceCell::new();
r.set(build_broken_resolver().expect("failed to build resolver"))
.expect("broken resolver init error");
// create a new resolver that won't mess with the shared resolver used by other tests
let resolver = HickoryDnsResolver::default();
// successful lookup using fallback to static resolver
let domain = "rpc.nymtech.net";
let _ = resolver
.resolve_str(domain)
.await
.expect("failed to resolve address in static lookup");
println!(
"{}ms resolved {domain}",
(Instant::now() - time_start).as_millis()
);
// unsuccessful lookup - primary times out, and not in static table
let domain = "non-existent.nymtech.net";
let result = resolver.resolve_str(domain).await;
assert!(result.is_err());
// assert!(result.is_err_and(|e| matches!(e, ResolveError::Timeout)));
// assert!(result.is_err_and(|e| matches!(e, ResolveError::ResolveError(e) if e.is_nx_domain())));
Ok(())
}
}
}