Using Sockets

The sockets components provides a simple interface for making TCP connections. The Socket class is itself a stream implementing IInputStream and IOutputStream allowing for varying data types to be written to and read from the connection.

Like with all Orolyn IO interfaces, calls to the socket’s IO bound APIs block execution, but release control of the current task when executed within a concurrent environment.

Making a connection

Connection with sockets are performed by providing the necessary endpoint. For example to connect to an IP address we can use the following example.

Create a netcat server with port 9999:

netcat -k -l 0.0.0.0 9999

use Orolyn\Net\IPAddress;
use Orolyn\Net\IPEndPoint;
use Orolyn\Net\Sockets\Socket;

$socket = new Socket();
$socket->connect(new IPEndPoint(IPAddress::parse('0.0.0.0'), 9999));

$socket->write("Hello, World!\n");

In this example we can also use the StreamWriter:

use Orolyn\IO\StreamWriter;

$writer = new StreamWriter($socket);
$writer->writeLine('Hello, World!');
$socket->flush();

Example:

Server terminal

netcat -k -l 0.0.0.0 9999

Client terminal

php sockets.php

Server output

Hello, World!

Reading data from a socket

We can also read data from the socket. Here is an example of connecting to an HTTP server and making a simple HTTP transaction. For this example we are connecting via a DNS endpoint. To learn more about resolving domain names see documentation on the DnsResolver.

$socket = new Socket();
$socket->connect(new DnsEndPoint('google.com', 80));

$message = <<<EOF
GET / HTTP/1.0
Host: google.com


EOF;

$socket->write($message);
$socket->flush();

$response = '';

while (!$socket->isEndOfStream()) {
    if (0 < $available = $socket->getBytesAvailable()) {
        $response .= $socket->read($available);
    }

    usleep(100);
}

echo $response;

Client terminal

php domain-connect.php

Output

HTTP/1.0 301 Moved Permanently
Location: http://www.google.com/
Content-Type: text/html; charset=UTF-8
Date: Sun, 05 Jun 2022 16:55:14 GMT
Expires: Tue, 05 Jul 2022 16:55:14 GMT
Cache-Control: public, max-age=2592000
Server: gws
Content-Length: 219
X-XSS-Protection: 0
X-Frame-Options: SAMEORIGIN

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="http://www.google.com/">here</A>.
</BODY></HTML>

Concurrency

Guides on concurrency with sockets