Dns Component

Async DNS resolver.

The main point of the DNS component is to provide async DNS resolution. However, it is really a toolkit for working with DNS messages, and could easily be used to create a DNS server.

Basic usage

The most basic usage is to just create a resolver through the resolver factory. All you need to give it is a nameserver, then you can start resolving names, baby!

    $loop = React\EventLoop\Factory::create();
    $factory = new React\Dns\Resolver\Factory();
    $dns = $factory->create('8.8.8.8', $loop);

    $dns->resolve('igor.io')->then(function ($ip) {
        echo "Host: $ip\n";
    });

But there's more.

Caching

You can cache results by configuring the resolver to use a CachedExecutor:

    $loop = React\EventLoop\Factory::create();
    $factory = new React\Dns\Resolver\Factory();
    $dns = $factory->createCached('8.8.8.8', $loop);

    $dns->resolve('igor.io')->then(function ($ip) {
        echo "Host: $ip\n";
    });

    ...

    $dns->resolve('igor.io')->then(function ($ip) {
        echo "Host: $ip\n";
    });

If the first call returns before the second, only one query will be executed. The second result will be served from cache.

Todo

• Implement message body parsing for types other than A and CNAME: NS, SOA, PTR, MX, TXT, AAAA
• Implement authority and additional message parts
• Respect /etc/hosts

References

• RFC1034 Domain Names - Concepts and Facilities
• RFC1035 Domain Names - Implementation and Specification