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Merge pull request #148 from clue-labs/selective-transport
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Add SelectiveTransportExecutor to retry with TCP if UDP is truncated and automatically select transport protocol when no explicit scheme is given in Factory
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jsor authored Aug 13, 2019
2 parents c94f002 + 994b019 commit 6792a5f
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49 changes: 49 additions & 0 deletions README.md
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Expand Up @@ -19,6 +19,7 @@ easily be used to create a DNS server.
* [Advanced usage](#advanced-usage)
* [UdpTransportExecutor](#udptransportexecutor)
* [TcpTransportExecutor](#tcptransportexecutor)
* [SelectiveTransportExecutor](#selectivetransportexecutor)
* [HostsFileExecutor](#hostsfileexecutor)
* [Install](#install)
* [Tests](#tests)
Expand Down Expand Up @@ -350,6 +351,54 @@ $executor = new CoopExecutor(
packages. Higher-level components should take advantage of the Socket
component instead of reimplementing this socket logic from scratch.

### SelectiveTransportExecutor

The `SelectiveTransportExecutor` class can be used to
Send DNS queries over a UDP or TCP/IP stream transport.

This class will automatically choose the correct transport protocol to send
a DNS query to your DNS server. It will always try to send it over the more
efficient UDP transport first. If this query yields a size related issue
(truncated messages), it will retry over a streaming TCP/IP transport.

For more advanced usages one can utilize this class directly.
The following example looks up the `IPv6` address for `reactphp.org`.

```php
$executor = new SelectiveTransportExecutor($udpExecutor, $tcpExecutor);

$executor->query(
new Query($name, Message::TYPE_AAAA, Message::CLASS_IN)
)->then(function (Message $message) {
foreach ($message->answers as $answer) {
echo 'IPv6: ' . $answer->data . PHP_EOL;
}
}, 'printf');
```

Note that this executor only implements the logic to select the correct
transport for the given DNS query. Implementing the correct transport logic,
implementing timeouts and any retry logic is left up to the given executors,
see also [`UdpTransportExecutor`](#udptransportexecutor) and
[`TcpTransportExecutor`](#tcptransportexecutor) for more details.

Note that this executor is entirely async and as such allows you to execute
any number of queries concurrently. You should probably limit the number of
concurrent queries in your application or you're very likely going to face
rate limitations and bans on the resolver end. For many common applications,
you may want to avoid sending the same query multiple times when the first
one is still pending, so you will likely want to use this in combination with
a `CoopExecutor` like this:

```php
$executor = new CoopExecutor(
new SelectiveTransportExecutor(
$datagramExecutor,
$streamExecutor
)
);
```

### HostsFileExecutor

Note that the above `UdpTransportExecutor` class always performs an actual DNS query.
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2 changes: 1 addition & 1 deletion composer.json
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Expand Up @@ -7,7 +7,7 @@
"php": ">=5.3.0",
"react/cache": "^1.0 || ^0.6 || ^0.5",
"react/event-loop": "^1.0 || ^0.5",
"react/promise": "^2.1 || ^1.2.1",
"react/promise": "^2.7 || ^1.2.1",
"react/promise-timer": "^1.2"
},
"require-dev": {
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85 changes: 85 additions & 0 deletions src/Query/SelectiveTransportExecutor.php
Original file line number Diff line number Diff line change
@@ -0,0 +1,85 @@
<?php

namespace React\Dns\Query;

use React\Promise\Promise;

/**
* Send DNS queries over a UDP or TCP/IP stream transport.
*
* This class will automatically choose the correct transport protocol to send
* a DNS query to your DNS server. It will always try to send it over the more
* efficient UDP transport first. If this query yields a size related issue
* (truncated messages), it will retry over a streaming TCP/IP transport.
*
* For more advanced usages one can utilize this class directly.
* The following example looks up the `IPv6` address for `reactphp.org`.
*
* ```php
* $executor = new SelectiveTransportExecutor($udpExecutor, $tcpExecutor);
*
* $executor->query(
* new Query($name, Message::TYPE_AAAA, Message::CLASS_IN)
* )->then(function (Message $message) {
* foreach ($message->answers as $answer) {
* echo 'IPv6: ' . $answer->data . PHP_EOL;
* }
* }, 'printf');
* ```
*
* Note that this executor only implements the logic to select the correct
* transport for the given DNS query. Implementing the correct transport logic,
* implementing timeouts and any retry logic is left up to the given executors,
* see also [`UdpTransportExecutor`](#udptransportexecutor) and
* [`TcpTransportExecutor`](#tcptransportexecutor) for more details.
*
* Note that this executor is entirely async and as such allows you to execute
* any number of queries concurrently. You should probably limit the number of
* concurrent queries in your application or you're very likely going to face
* rate limitations and bans on the resolver end. For many common applications,
* you may want to avoid sending the same query multiple times when the first
* one is still pending, so you will likely want to use this in combination with
* a `CoopExecutor` like this:
*
* ```php
* $executor = new CoopExecutor(
* new SelectiveTransportExecutor(
* $datagramExecutor,
* $streamExecutor
* )
* );
* ```
*/
class SelectiveTransportExecutor implements ExecutorInterface
{
private $datagramExecutor;
private $streamExecutor;

public function __construct(ExecutorInterface $datagramExecutor, ExecutorInterface $streamExecutor)
{
$this->datagramExecutor = $datagramExecutor;
$this->streamExecutor = $streamExecutor;
}

public function query(Query $query)
{
$stream = $this->streamExecutor;
$pending = $this->datagramExecutor->query($query);

return new Promise(function ($resolve, $reject) use (&$pending, $stream, $query) {
$pending->then(
$resolve,
function ($e) use (&$pending, $stream, $query, $resolve, $reject) {
if ($e->getCode() === (\defined('SOCKET_EMSGSIZE') ? \SOCKET_EMSGSIZE : 90)) {
$pending = $stream->query($query)->then($resolve, $reject);
} else {
$reject($e);
}
}
);
}, function () use (&$pending) {
$pending->cancel();
$pending = null;
});
}
}
8 changes: 6 additions & 2 deletions src/Query/UdpTransportExecutor.php
Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,8 @@ public function query(Query $query)
$queryData = $this->dumper->toBinary($request);
if (isset($queryData[512])) {
return \React\Promise\reject(new \RuntimeException(
'DNS query for ' . $query->name . ' failed: Query too large for UDP transport'
'DNS query for ' . $query->name . ' failed: Query too large for UDP transport',
\defined('SOCKET_EMSGSIZE') ? \SOCKET_EMSGSIZE : 90
));
}

Expand Down Expand Up @@ -172,7 +173,10 @@ public function query(Query $query)
\fclose($socket);

if ($response->tc) {
$deferred->reject(new \RuntimeException('DNS query for ' . $query->name . ' failed: The server returned a truncated result for a UDP query, but retrying via TCP is currently not supported'));
$deferred->reject(new \RuntimeException(
'DNS query for ' . $query->name . ' failed: The server returned a truncated result for a UDP query',
\defined('SOCKET_EMSGSIZE') ? \SOCKET_EMSGSIZE : 90
));
return;
}

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44 changes: 30 additions & 14 deletions src/Resolver/Factory.php
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Expand Up @@ -10,6 +10,7 @@
use React\Dns\Query\ExecutorInterface;
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;
Expand Down Expand Up @@ -84,24 +85,39 @@ private function createExecutor($nameserver, LoopInterface $loop)
$parts = \parse_url($nameserver);

if (isset($parts['scheme']) && $parts['scheme'] === 'tcp') {
$executor = new TimeoutExecutor(
new TcpTransportExecutor($nameserver, $loop),
5.0,
$loop
);
$executor = $this->createTcpExecutor($nameserver, $loop);
} elseif (isset($parts['scheme']) && $parts['scheme'] === 'udp') {
$executor = $this->createUdpExecutor($nameserver, $loop);
} else {
$executor = new RetryExecutor(
new TimeoutExecutor(
new UdpTransportExecutor(
$nameserver,
$loop
),
5.0,
$loop
)
$executor = new SelectiveTransportExecutor(
$this->createUdpExecutor($nameserver, $loop),
$this->createTcpExecutor($nameserver, $loop)
);
}

return new CoopExecutor($executor);
}

private function createTcpExecutor($nameserver, LoopInterface $loop)
{
return new TimeoutExecutor(
new TcpTransportExecutor($nameserver, $loop),
5.0,
$loop
);
}

private function createUdpExecutor($nameserver, LoopInterface $loop)
{
return new RetryExecutor(
new TimeoutExecutor(
new UdpTransportExecutor(
$nameserver,
$loop
),
5.0,
$loop
)
);
}
}
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