PHP, Structures and Functions Acting on a Disk system


<?php

res|false fsockopen ( str $hostname , 
                                 int $port = -1 , 
                              int &$error_code = null , 
                              str &$error_message = null , 
                      float|null $timeout = null )


where,

$hostname = The remote TCP/IP to connect

$port = The port number
             
&$error_code = The error system-level 

&$error_message = The error message

$timeout = The connection timeout

?>

$hostname

If OpenSSL support is installed, you may prefix the $hostname with either ssl:// or tls:// to use an SSL or TLS client connection over TCP/IP to connect to the remote host.

$port

The port number that cam be omitted and skipped to -1 for transports that do not use ports, such as unix://.

&$error_code

The number of that occurred in the system-level in the connetion call.

If &$error_code = 0 and the function returs FALSE indicates that an error occurred before the connetion call, this is an indication of a problem with the initializing the socket.

&$error_message

The error message.

$timeout

The connection timeout, in seconds.

This function returns a file pointer as RESOURCE on SUCCESS.

This function returns a FALSE on ERROR.

This function returns E_WARNING if $hostname is not a valid domain.

This file pointer may be used together with fgets, fgetss, fwrite, fclose and feof.

Since the PHP 8.0.0 $timout is nullable.

EXERCISE


<?php

echo "Open a server socket<br>";

for ($i=0; $i<100; $i++) {
  $port = rand(10000, 65000);
  /* Setup socket server */
  $server = @stream_socket_server("tcp://127.0.0.1:$port");
  if ($server) {
    break;
  }
}

// Initialise all required variables
$hostname = 'tcp://127.0.0.1'; 
// loopback address
$errno = null;
$errstr = null;
$timeout = 1.5;

echo "<br><br>Calling fsockopen() with all possible arguments:<br>";
$client = fsockopen($hostname, $port, $errno, $errstr, $timeout);
var_dump($client);
fclose($client);

echo "<br><br>Calling fsockopen() with mandatory arguments:<br>";
$second_client = fsockopen($hostname, $port);
var_dump($second_client);
fclose($second_client);

echo "<br><br>Calling fsockopen() with address and port in same string:<br>";
$address = $hostname . ':' . $port;
$third_client = fsockopen($address);
var_dump($third_client);
fclose($third_client);

?>

EXERCISE


<?php

echo "Open a server socket<br>";
for ($i=0; $i<100; $i++) {
  $port = rand(10000, 65000);
  /* Setup socket server */
  $server = @stream_socket_server("tcp://127.0.0.1:$port");
  if ($server) {
    break;
  }
}

echo "<br><br>Calling fsockopen() 
        without a protocol in the hostname string:<br>";
$hostname = '127.0.0.1';
$client = fsockopen($hostname, $port);
var_dump($client);
fclose($client);

echo "<br><br>Calling fsockopen() 
             with address and port in same string, without a protocol:<br>";
$address = $hostname . ':' . $port;
$second_client = fsockopen($address);
var_dump($second_client);
fclose($second_client);

echo "Done";
?>

EXERCISE


<?php

$hostname = 'udp://127.0.0.1';
$port = '31337';

echo "Open a server socket<br>";
$server = stream_socket_server($hostname . ':' . 
$port, $errno, $errstr, STREAM_SERVER_BIND);

echo "<br><br>Calling fsockopen():<br>";
$client = fsockopen($hostname, $port);
var_dump($client);

echo "<br><br>Pass some data between the sockets:<br>";
fwrite($client, "0123456789");
var_dump(fread($server, 10));
fclose($client);

echo "<br><br>Calling fsockopen() with 
              address and port in same string:<br>";
$address = $hostname . ':' . $port;
$second_client = fsockopen($address);
var_dump($second_client);

echo "<br><br>Pass some data between the sockets:<br>";
fwrite($second_client, "0123456789");
var_dump(fread($server, 10));
fclose($second_client);

?>

EXERCISE


<?php

// error condition

echo "Attempting to connect to a non-existent socket<br>";
$hostname = 'tcp://127.0.0.1'; 
// loopback address
$port = 31337;
$errno = null;
$errstr = null;
$timeout = 1.5;
var_dump( fsockopen($hostname, $port, $errno, $errstr, $timeout) );
var_dump($errstr);

echo "<br><br>Attempting to connect using an invalid protocol<br>";
$hostname = 'invalid://127.0.0.1'; 
// loopback address
$port = 31337;
$errno = null;
$errstr = null;
$timeout = 1.5;
var_dump( fsockopen($hostname, $port, $errno, $errstr, $timeout) );
var_dump($errstr);

?>