回答

服务端可以用自签名的ssl证书，示例如下：

<?php
$server = new Swoole\Server('0.0.0.0', 9501, SWOOLE_PROCESS, SWOOLE_SOCK_TCP | SWOOLE_SSL);
$server->set(array(
    'ssl_cert_file'         => __DIR__ . '/config/ssl.crt',
    'ssl_key_file'          => __DIR__ . '/config/ssl.key',
    'ssl_verify_peer'       => true,
    'ssl_allow_self_signed' => true,
    'ssl_client_cert_file'  => __DIR__ . '/config/ca.crt',
));

<?php
$client = new Swoole\Client(SWOOLE_SOCK_TCP | SWOOLE_SSL);

$client->set(array(
    'ssl_cert_file' => __DIR__.'/ca/client-cert.pem',
    'ssl_key_file' => __DIR__.'/ca/client-key.pem',
    'ssl_allow_self_signed' => true,
    'ssl_verify_peer' => true,
    'ssl_cafile' => __DIR__.'/ca/ca-cert.pem',
));
if (!$client->connect('127.0.0.1', 9501, -1))
{
    exit("connect failed. Error: {$client->errCode}\n");
}
echo "connect ok\n";
$client->send("hello world-" . str_repeat('A', $i) . "\n");
echo $client->recv();