Async DNS resolver for ReactPHP.
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.
Table of contents
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!
$config = React\Dns\Config\Config::loadSystemConfigBlocking();
if (!$config->nameservers) {
$config->nameservers[] = '8.8.8.8';
}
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->create($config);
$dns->resolve('igor.io')->then(function ($ip) {
echo "Host: $ip\n";
});See also the first example.
The Config class can be used to load the system default config. This is an
operation that may access the filesystem and block. Ideally, this method should
thus be executed only once before the loop starts and not repeatedly while it is
running.
Note that this class may return an empty configuration if the system config
can not be loaded. As such, you'll likely want to apply a default nameserver
as above if none can be found.
Note that the factory loads the hosts file from the filesystem once when creating the resolver instance. Ideally, this method should thus be executed only once before the loop starts and not repeatedly while it is running.
But there's more.
You can cache results by configuring the resolver to use a CachedExecutor:
$config = React\Dns\Config\Config::loadSystemConfigBlocking();
if (!$config->nameservers) {
$config->nameservers[] = '8.8.8.8';
}
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->createCached($config);
$dns->resolve('igor.io')->then(function ($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 an in memory cache. This is particularly useful for long running scripts where the same hostnames have to be looked up multiple times.
See also the third example.
By default, the above will use an in memory cache.
You can also specify a custom cache implementing CacheInterface to handle the record cache instead:
$cache = new React\Cache\ArrayCache();
$factory = new React\Dns\Resolver\Factory();
$dns = $factory->createCached('8.8.8.8', null, $cache);See also the wiki for possible cache implementations.
The resolve(string $domain): PromiseInterface<string> method can be used to
resolve the given $domain name to a single IPv4 address (type A query).
$resolver->resolve('reactphp.org')->then(function ($ip) {
echo 'IP for reactphp.org is ' .