Socket Programming with PHP

TL;DR

Explanation

Two socket APIs in PHP: (1) Sockets extension (socket_create, socket_bind, socket_listen, socket_accept) — low-level, POSIX-like. (2) Stream sockets (stream_socket_client, stream_socket_server) — higher level, supports SSL, uses fread/fwrite. For most cases, use Guzzle (HTTP), AMQP libraries (queues), or ReactPHP/Swoole for async sockets. Raw sockets are useful for: custom TCP/UDP protocols, network diagnostics, building WebSocket servers. Non-blocking sockets with socket_set_nonblock and socket_select() enable handling multiple connections. PHP's socket support is blocking by default — use ReactPHP or Swoole for production async networking.

Common Misconception

Why It Matters

Common Mistakes

• Using blocking sockets in production servers — limits to one connection at a time.
• Not setting SO_REUSEADDR — port in use errors after restart.
• Not handling partial reads — TCP streams can split messages across packets.

Code Examples

// Blocking TCP server — handles one connection at a time:
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_bind($socket, '0.0.0.0', 8080);
socket_listen($socket);
$client = socket_accept($socket); // Blocks until connection

// Non-blocking with stream sockets:
$server = stream_socket_server('tcp://0.0.0.0:8080', $errno, $errstr);
stream_set_blocking($server, false);

while (true) {
    $client = @stream_socket_accept($server, 0);
    if ($client) {
        $data = fread($client, 1024);
        fwrite($client, "HTTP/1.1 200 OK\r\n\r\nHello");
        fclose($client);
    }
    // In production: use ReactPHP or Swoole for proper async
}

References

• ↗ https://www.php.net/manual/en/book.sockets.php
• ↗ https://reactphp.org

Tags

Related Terms