CasperSecurity
<?php
namespace React\Dns\Resolver;
use React\Cache\ArrayCache;
use React\Cache\CacheInterface;
use React\Dns\Config\Config;
use React\Dns\Config\HostsFile;
use React\Dns\Query\CachingExecutor;
use React\Dns\Query\CoopExecutor;
use React\Dns\Query\ExecutorInterface;
use React\Dns\Query\FallbackExecutor;
use React\Dns\Query\HostsFileExecutor;
use React\Dns\Query\RetryExecutor;
use React\Dns\Query\SelectiveTransportExecutor;
use React\Dns\Query\TcpTransportExecutor;
use React\Dns\Query\TimeoutExecutor;
use React\Dns\Query\UdpTransportExecutor;
use React\EventLoop\Loop;
use React\EventLoop\LoopInterface;
final class Factory
{
/**
* Creates a DNS resolver instance for the given DNS config
*
* As of v1.7.0 it's recommended to pass a `Config` object instead of a
* single nameserver address. If the given config contains more than one DNS
* nameserver, all DNS nameservers will be used in order. The primary DNS
* server will always be used first before falling back to the secondary or
* tertiary DNS server.
*
* @param Config|string $config DNS Config object (recommended) or single nameserver address
* @param ?LoopInterface $loop
* @return \React\Dns\Resolver\ResolverInterface
* @throws \InvalidArgumentException for invalid DNS server address
* @throws \UnderflowException when given DNS Config object has an empty list of nameservers
*/
public function create($config, $loop = null)
{
if ($loop !== null && !$loop instanceof LoopInterface) { // manual type check to support legacy PHP < 7.1
throw new \InvalidArgumentException('Argument #2 ($loop) expected null|React\EventLoop\LoopInterface');
}
$executor = $this->decorateHostsFileExecutor($this->createExecutor($config, $loop ?: Loop::get()));
return new Resolver($executor);
}
/**
* Creates a cached DNS resolver instance for the given DNS config and cache
*
* As of v1.7.0 it's recommended to pass a `Config` object instead of a
* single nameserver address. If the given config contains more than one DNS
* nameserver, all DNS nameservers will be used in order. The primary DNS
* server will always be used first before falling back to the secondary or
* tertiary DNS server.
*
* @param Config|string $config DNS Config object (recommended) or single nameserver address
* @param ?LoopInterface $loop
* @param ?CacheInterface $cache
* @return \React\Dns\Resolver\ResolverInterface
* @throws \InvalidArgumentException for invalid DNS server address
* @throws \UnderflowException when given DNS Config object has an empty list of nameservers
*/
public function createCached($config, $loop = null, $cache = null)
{
if ($loop !== null && !$loop instanceof LoopInterface) { // manual type check to support legacy PHP < 7.1
throw new \InvalidArgumentException('Argument #2 ($loop) expected null|React\EventLoop\LoopInterface');
}
if ($cache !== null && !$cache instanceof CacheInterface) { // manual type check to support legacy PHP < 7.1
throw new \InvalidArgumentException('Argument #3 ($cache) expected null|React\Cache\CacheInterface');
}
// default to keeping maximum of 256 responses in cache unless explicitly given
if (!($cache instanceof CacheInterface)) {
$cache = new ArrayCache(256);
}
$executor = $this->createExecutor($config, $loop ?: Loop::get());
$executor = new CachingExecutor($executor, $cache);
$executor = $this->decorateHostsFileExecutor($executor);
return new Resolver($executor);
}
/**
* Tries to load the hosts file and decorates the given executor on success
*
* @param ExecutorInterface $executor
* @return ExecutorInterface
* @codeCoverageIgnore
*/
private function decorateHostsFileExecutor(ExecutorInterface $executor)
{
try {
$executor = new HostsFileExecutor(
HostsFile::loadFromPathBlocking(),
$executor
);
} catch (\RuntimeException $e) {
// ignore this file if it can not be loaded
}
// Windows does not store localhost in hosts file by default but handles this internally
// To compensate for this, we explicitly use hard-coded defaults for localhost
if (DIRECTORY_SEPARATOR === '\\') {
$executor = new HostsFileExecutor(
new HostsFile("127.0.0.1 localhost\n::1 localhost"),
$executor
);
}
return $executor;
}
/**
* @param Config|string $nameserver
* @param LoopInterface $loop
* @return CoopExecutor
* @throws \InvalidArgumentException for invalid DNS server address
* @throws \UnderflowException when given DNS Config object has an empty list of nameservers
*/
private function createExecutor($nameserver, LoopInterface $loop)
{
if ($nameserver instanceof Config) {
if (!$nameserver->nameservers) {
throw new \UnderflowException('Empty config with no DNS servers');
}
// Hard-coded to check up to 3 DNS servers to match default limits in place in most systems (see MAXNS config).
// Note to future self: Recursion isn't too hard, but how deep do we really want to go?
$primary = reset($nameserver->nameservers);
$secondary = next($nameserver->nameservers);
$tertiary = next($nameserver->nameservers);
if ($tertiary !== false) {
// 3 DNS servers given => nest first with fallback for second and third
return new CoopExecutor(
new RetryExecutor(
new FallbackExecutor(
$this->createSingleExecutor($primary, $loop),
new FallbackExecutor(
$this->createSingleExecutor($secondary, $loop),
$this->createSingleExecutor($tertiary, $loop)
)
)
)
);
} elseif ($secondary !== false) {
// 2 DNS servers given => fallback from first to second
return new CoopExecutor(
new RetryExecutor(
new FallbackExecutor(
$this->createSingleExecutor($primary, $loop),
$this->createSingleExecutor($secondary, $loop)
)
)
);
} else {
// 1 DNS server given => use single executor
$nameserver = $primary;
}
}
return new CoopExecutor(new RetryExecutor($this->createSingleExecutor($nameserver, $loop)));
}
/**
* @param string $nameserver
* @param LoopInterface $loop
* @return ExecutorInterface
* @throws \InvalidArgumentException for invalid DNS server address
*/
private function createSingleExecutor($nameserver, LoopInterface $loop)
{
$parts = \parse_url($nameserver);
if (isset($parts['scheme']) && $parts['scheme'] === 'tcp') {
$executor = $this->createTcpExecutor($nameserver, $loop);
} elseif (isset($parts['scheme']) && $parts['scheme'] === 'udp') {
$executor = $this->createUdpExecutor($nameserver, $loop);
} else {
$executor = new SelectiveTransportExecutor(
$this->createUdpExecutor($nameserver, $loop),
$this->createTcpExecutor($nameserver, $loop)
);
}
return $executor;
}
/**
* @param string $nameserver
* @param LoopInterface $loop
* @return TimeoutExecutor
* @throws \InvalidArgumentException for invalid DNS server address
*/
private function createTcpExecutor($nameserver, LoopInterface $loop)
{
return new TimeoutExecutor(
new TcpTransportExecutor($nameserver, $loop),
5.0,
$loop
);
}
/**
* @param string $nameserver
* @param LoopInterface $loop
* @return TimeoutExecutor
* @throws \InvalidArgumentException for invalid DNS server address
*/
private function createUdpExecutor($nameserver, LoopInterface $loop)
{
return new TimeoutExecutor(
new UdpTransportExecutor(
$nameserver,
$loop
),
5.0,
$loop
);
}
}