Overview

Trust-DNS Async-Std Resolver is a library which implements the DNS resolver using the Trust-DNS Resolver library.

This library contains implementations for IPv4 (A) and IPv6 (AAAA) resolution, more features are in the works. It is built on top of the async-std async-io project, this allows it to be integrated into other systems using the async-std and futures libraries. The Trust-DNS project contains other libraries for DNS: a client library for raw protocol usage, a server library for hosting zones, and variations on the TLS implementation over rustls and native-tls.

Features

• Various IPv4 and IPv6 lookup strategies
• /etc/resolv.conf based configuration on Unix/Posix systems
• NameServer pools with performance based priority usage
• Caching of query results
• NxDomain/NoData caching (negative caching)
• TBD (in tokio impl): DNSSec validation
• Generic Record Type Lookup
• CNAME chain resolution
• experimental mDNS support (enable with mdns feature)
• TBD (in tokio impl): DNS over TLS (utilizing native-tls, rustls, and openssl; native-tls or rustls are recommended)
• TBD (in tokio impl): DNS over HTTPS (currently only supports rustls)

Example

use std::net::*;
use async_std::prelude::*;
use async_std_resolver::{resolver, config};

#[async_std::main]
async fn main() {
  // Construct a new Resolver with default configuration options
  let resolver = resolver(
    config::ResolverConfig::default(),
    config::ResolverOpts::default(),
  ).await.expect("failed to connect resolver");

  // Lookup the IP addresses associated with a name.
  // This returns a future that will lookup the IP addresses, it must be run in the Core to
  //  to get the actual result.
  let mut response = resolver.lookup_ip("www.example.com.").await.unwrap();

  // There can be many addresses associated with the name,
  //  this can return IPv4 and/or IPv6 addresses
  let address = response.iter().next().expect("no addresses returned!");
  if address.is_ipv4() {
    assert_eq!(address, IpAddr::V4(Ipv4Addr::new(93, 184, 216, 34)));
  } else {
    assert_eq!(address, IpAddr::V6(Ipv6Addr::new(0x2606, 0x2800, 0x220, 0x1, 0x248, 0x1893, 0x25c8, 0x1946)));
  }
}

Minimum Rust Version

The current minimum rustc version for this project is 1.40

Versioning

Trust-DNS does its best job to follow semver. Trust-DNS will be promoted to 1.0 upon stabilization of the publicly exposed APIs. This does not mean that Trust-DNS will necessarily break on upgrades between 0.x updates. Whenever possible, old APIs will be deprecated with notes on what replaced those deprecations. Trust-DNS will make a best effort to never break software which depends on it due to API changes, though this can not be guaranteed. Deprecated interfaces will be maintained for at minimum one major release after that in which they were deprecated (where possible), with the exception of the upgrade to 1.0 where all deprecated interfaces will be planned to be removed.