UDP

The UDP component provides a non-blocking API for sending and receiving datagrams over UDP.

It uses two distinct types for type-safe socket usage:

• Socket -- an unconnected socket for sending/receiving to arbitrary addresses.
• ConnectedSocket -- a connected socket for communicating with a single peer.

Usage

use Psl\Async;
use Psl\Network\Address;
use Psl\UDP;

$server = UDP\Socket::bind('127.0.0.1', 0);
$serverAddress = $server->getLocalAddress();

Async\concurrently([
    'server' => static function () use ($server): void {
        [$data, $sender] = $server->receiveFrom(1024);
        $server->sendTo("echo: {$data}", $sender);
        $server->close();
    },
    'client' => static function () use ($serverAddress): void {
        $client = UDP\Socket::bind('127.0.0.1', 0);
        $client->sendTo('hello', Address::udp($serverAddress->host, $serverAddress->port ?? 0));
        [$response, $_] = $client->receiveFrom(1024);
        $client->close();
    },
]);

Design

Unconnected vs. Connected Sockets

An unconnected Socket can send to and receive from any address using sendTo() and receiveFrom(). When you call connect() on it, the original socket is closed and a ConnectedSocket is returned. The connected socket uses simpler send() and receive() methods since the peer is fixed.

use Psl\Async;
use Psl\UDP;

$server = UDP\Socket::bind('127.0.0.1', 0);
$serverAddress = $server->getLocalAddress();

Async\concurrently([
    'server' => static function () use ($server): void {
        [$data, $sender] = $server->receiveFrom(1024);
        $server->sendTo("echo: {$data}", $sender);
        $server->close();
    },
    'client' => static function () use ($serverAddress): void {
        // Start with an unconnected socket
        $socket = UDP\Socket::bind('127.0.0.1', 0);

        // Connect returns a ConnectedSocket -- the original socket is closed
        $connected = $socket->connect($serverAddress->host, $serverAddress->port ?? 0);

        // $socket is now closed -- only $connected is usable
        $connected->send('hello');
        $_ = $connected->receive(512);
        $connected->close();
    },
]);

You can also create a connected socket directly:

use Psl\Async;
use Psl\UDP;

$server = UDP\Socket::bind('127.0.0.1', 0);
$serverAddress = $server->getLocalAddress();

Async\concurrently([
    'server' => static function () use ($server): void {
        [$data, $sender] = $server->receiveFrom(1024);
        $server->sendTo("echo: {$data}", $sender);
        $server->close();
    },
    'client' => static function () use ($serverAddress): void {
        // Create a connected socket directly
        $socket = UDP\connect($serverAddress->host, $serverAddress->port ?? 0);
        $socket->send('hello');
        $_ = $socket->receive(512);
        $socket->close();
    },
]);

Configuration

UDP\Socket::bind() accepts a BindConfiguration to control address reuse, port reuse, and broadcast. Configuration objects are immutable with with* builder methods.

Examples

Echo Server

use Psl\Async;
use Psl\Network\Address;
use Psl\UDP;

$socket = UDP\Socket::bind('127.0.0.1', 0);
$serverAddress = $socket->getLocalAddress();
echo "Listening on {$serverAddress->toString()}\n";

Async\concurrently([
    'server' => static function () use ($socket): void {
        // Echo one datagram then shut down
        [$data, $sender] = $socket->receiveFrom(65_507);
        $socket->sendTo($data, $sender);
        $socket->close();
    },
    'client' => static function () use ($serverAddress): void {
        $client = UDP\Socket::bind('127.0.0.1');
        $client->sendTo('ping', Address::udp($serverAddress->host, $serverAddress->port ?? 0));
        [$response, $_] = $client->receiveFrom(1024);
        echo "Got: {$response}\n";
        $client->close();
    },
]);

Peek

use Psl\Async;
use Psl\Network\Address;
use Psl\UDP;

$socket = UDP\Socket::bind('127.0.0.1');
$serverAddress = $socket->getLocalAddress();

Async\concurrently([
    'server' => static function () use ($socket): void {
        // Peek at data without consuming it
        [$data, $_sender] = $socket->peekFrom(1024);
        echo "Peeked: {$data}\n";

        // Same data is still available for receiveFrom()
        [$data, $_sender] = $socket->receiveFrom(1024);
        echo "Received: {$data}\n";

        $socket->close();
    },
    'client' => static function () use ($serverAddress): void {
        $client = UDP\Socket::bind('127.0.0.1');
        $client->sendTo('hello', Address::udp($serverAddress->host, $serverAddress->port ?? 0));
        $client->close();
    },
]);

See src/Psl/UDP/ for the full API.