Naive (HTTP) socket server baseline

server.php

<?php

$host = '0.0.0.0';
$port = 8080;
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1);
socket_bind($socket, $host, $port);
socket_listen($socket);
socket_set_nonblock($socket);
echo "Listening on {$host}:{$port}\n\n";
$sockets = [$socket];

while (true)  {
    $readableSockets = $sockets;
    $null = null;

    if (!socket_select($readableSockets, $null, $null, 0, 10)) {
        continue;
    }

    $index = array_search($socket, $readableSockets, true);

    if ($index !== false) {
        if ($client = socket_accept($socket)) {
            $sockets[] = $client;
        }

        unset($readableSockets[$index]);
    }

    foreach ($readableSockets as $readableSocket) {
        $request = '';

        while ($length = @socket_recv($readableSocket, $data, 1024, 0)) {
            $request .= $data;
        }

        $index = array_search($readableSocket, $sockets, true);
        unset($sockets[$index]);
        $error = socket_last_error($readableSocket);

        if ($error === SOCKET_ECONNRESET) {
            socket_clear_error($readableSocket);
            continue;
        }

        echo "Received: \n{$request}";
        $headers = [
            'HTTP/1.1 200 OK ',
            'Content-Type: text/html',
            '',
            '',
        ];
        $body = 'TEST';
        $response = implode("\r\n", $headers) . $body;
        @socket_write($client, $response, strlen($response));
        @socket_close($client);
    }
}