Question

How to disconnect from a telnet session using PHP ?Using this below code i read the telnet output.But i want to disconnect from telnet session if data can’t receive in $output variable within 3 second. How i do that.Please see my code below:

$fp = fsockopen("localhost", 80, $errno, $errstr, 30);
if (!$fp) {
    echo "$errstr ($errno)<br />\n";
} else {
    $out = "GET / HTTP/1.1\r\n";
    $out .= "Connection: Close\r\n\r\n";
    fwrite($fp, $out);
    $output=fread($fp,128);//Here we read the output value from socket        
    fclose($fp);                
    echo $output;               
}

Answer 1

Are you running under linux or Windows? In Linux you could fork the application to run the telnet session in parallel and have the main thread terminate the session after a given time if no output is received.

In Windows you could probably do a loop that does an fread() on the socket and keep track of time spent without getting any data and closing the socket after a given time.

Edit:
I just remembered that you don’t have to keep track of this manually 🙂
You could probably do something like

// Set socket timeout to 10 seconds
socket_set_timeout($fp, 10)

...

 $output=fread($fp,128);//Here we read the output value from socket  
if($output == false) {
  // Code to run if timeout occured
  echo "We timed out!";
}
...