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amphp/socket

AMPHP is a collection of event-driven libraries for PHP designed with fibers and concurrency in mind. amphp/socket is a library for establishing and encrypting non-blocking sockets. It provides a socket abstraction for clients and servers. It abstracts the really low levels of non-blocking streams in PHP.

Installation

This package can be installed as a Composer dependency.

composer require amphp/socket

Requirements

amphp/socket heavily relies on amphp/byte-stream, specifically its ReadableStream and WritableStream interfaces.

Connecting to a Server

amphp/socket allows clients to connect to servers via TCP, UDP, or Unix domain sockets. You can establish a socket connection using Amp\Socket\connect(). It will automatically resolve DNS names and retries other IPs if a connection fails and multiple IPs are available.

// You can customize connect() options using ConnectContext
$connectContext = (new Amp\Socket\ConnectContext)
        ->withConnectTimeout(5);

// You can optionally pass a Cancellation object to cancel a pending connect() operation
$deferredCancellation = new Amp\DeferredCancellation();

$socket = connect('amphp.org:80', $connectContext, $deferredCancellation->getCancellation());

Encrypted Connections / TLS

If you want to connect via TLS, use Amp\Socket\connectTls() instead or call $socket->setupTls() on the returned socket.

Handling Connections

Socket implements ReadableStream and WritableStream, so everything from amphp/byte-stream applies for receiving and sending data.

#!/usr/bin/env php
<?php // basic (and dumb) HTTP client

require __DIR__ . '/../vendor/autoload.php';

// This is a very simple HTTP client that just prints the response without parsing.
// league/uri required for this example.

use Amp\ByteStream;
use Amp\Socket\ClientTlsContext;
use Amp\Socket\ConnectContext;
use League\Uri\Http;
use function Amp\Socket\connect;
use function Amp\Socket\connectTls;

$stdout = ByteStream\getStdout();

if (\count($argv) !== 2) {
    $stdout->write('Usage: examples/simple-http-client.php <url>' . PHP_EOL);
    exit(1);
}

$uri = Http::createFromString($argv[1]);
$host = $uri->getHost();
$port = $uri->getPort() ?? ($uri->getScheme() === 'https' ? 443 : 80);
$path = $uri->getPath() ?: '/';

$connectContext = (new ConnectContext)
        ->withTlsContext(new ClientTlsContext($host));

$socket = $uri->getScheme() === 'http'
        ? connect($host . ':' . $port, $connectContext)
        : connectTls($host . ':' . $port, $connectContext);

$socket->write("GET {$path} HTTP/1.1\r\nHost: $host\r\nConnection: close\r\n\r\n");

ByteStream\pipe($socket, $stdout);

Server

amphp/socket allows listening for incoming TCP connections as well as connections via Unix domain sockets. It defaults to secure TLS settings if you decide to enable TLS.

Listening and Accepting Connections

Use Amp\Socket\Socket\listen() to listen on a port or unix domain socket. It's a wrapper around stream_socket_server that gives useful error message on failures via exceptions.

Once you're listening, accept clients using Server::accept(). It returns a Socket that returns once a new client has been accepted. It's usually called within a while loop:

$server = Socket\listen("tcp://127.0.0.1:1337");

while ($client = $server->accept()) {
    // You shouldn't spend too much time here, because that blocks accepting another client, so we use async():
    async(function () use ($client) {
        // Handle client connection here
    });
}

Handling Connections

Socket implements ReadableStream and WritableStream, so everything from amphp/byte-stream applies for receiving and sending data. It's best to handle clients in their own coroutine, while letting the server accept all clients as soon as there are new clients.

#!/usr/bin/env php
<?php // basic (and dumb) HTTP server

require __DIR__ . '/../vendor/autoload.php';

// This is a very simple HTTP server that just prints a message to each client that connects.
// It doesn't check whether the client sent an HTTP request.

// You might notice that your browser opens several connections instead of just one,
// even when only making one request.

use Amp\Socket;
use function Amp\async;

$server = Socket\listen('127.0.0.1:0');

echo 'Listening for new connections on ' . $server->getAddress() . ' ...' . PHP_EOL;
echo 'Open your browser and visit http://' . $server->getAddress() . '/' . PHP_EOL;

while ($socket = $server->accept()) {
    async(function () use ($socket) {
        $address = $socket->getRemoteAddress();
        $ip = $address->getHost();
        $port = $address->getPort();

        echo "Accepted connection from {$address}." . PHP_EOL;

        $body = "Hey, your IP is {$ip} and your local port used is {$port}.";
        $bodyLength = \strlen($body);

        $socket->write("HTTP/1.1 200 OK\r\nConnection: close\r\nContent-Length: {$bodyLength}\r\n\r\n{$body}");
        $socket->end();
    });
}

Closing Connections

Once you're done with a client, close the connection using Socket::close(). If you want to wait for all data to be successfully written before closing the connection, use Socket::end(). See above for an example.

Server Address

Sometimes you don't know the address the server is listening on, e.g. because you listed to tcp://127.0.0.1:0, which assigns a random free port. You can use Server::getAddress() to get the address the server is bound to.

Server Shutdown

Once you're done with the server socket, close the socket. That means, the server won't listen on the specified location anymore. Use Server::close() to close the server socket.

Encrypted Connections / TLS

As already mentioned in the documentation for Amp\Socket\Socket\listen(), you need to enable TLS manually after accepting connections. For a TLS server socket, you listen on the tcp:// protocol on a specified address. After accepting clients, call $socket->setupTls() where $socket is the socket returned from SocketServer::accept().

Warning Any data transmitted before Socket::setupTls() completes will be transmitted in clear text. Don't attempt to read from the socket or write to it manually. Doing so will read the raw TLS handshake data that's supposed to be read by OpenSSL.

Self-Signed Certificates

There's no option to allow self-signed certificates in ClientTlsContext since it is no more secure than disabling peer verification. To safely use a self-signed certificate, disable peer verification and require fingerprint verification of the certificate using ClientTlsContext::withPeerFingerprint().

Security

If you discover any security related issues, please email me@kelunik.com instead of using the issue tracker.

License

The MIT License (MIT). Please see LICENSE for more information.