php - how to create a socket server in my webhost - php

Question

I've a webhost and I want to create a socket connection with my application .
I've this code :
<?php
$host = "127.0.0.1";
$port = 25003;
// don't timeout!
set_time_limit(0);
if (!extension_loaded('sockets')) {
die('The sockets extension is not loaded.');
}
// create socket
$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die("Could not create socket\n");
// bind socket to port
$result = socket_bind($socket, $host, $port) or die("Could not bind to socket\n");
// start listening for connections
$result = socket_listen($socket, 3) or die("Could not set up socket listener\n");
// accept incoming connections
// spawn another socket to handle communication
$spawn = socket_accept($socket) or die("Could not accept incoming connection\n");
// read client input
$input = socket_read($spawn, 1024) or die("Could not read input\n");
// clean up input string
$input = trim($input);
echo "Client Message : " . $input;
// reverse client input and send back
$output = strrev($input) . "\n";
socket_write($spawn, $output, strlen($output)) or die("Could not write output\n");
// close sockets
socket_close($spawn);
socket_close($socket);
?>
when I run the page , it returns "Could not create socket"
I'm running the code on a share web service
what is the problem ? How can I fix it ?

Answer 1

I tried your code on my machine with XAMPP installed and is working, it actually does open that port, I tested with telnet through putty. Answering to your questions I think like #Jon Stirling said your hosting does not allow you to create a socket. That's why hosting companies sell web hostings packages and virtual private servers, if you want to bind a port you should look for a VPS.

Answer 2

I am sure you have solved this and moved jobs since you posted it but as someone who has just gone through this I would like to direct everyone who lands here to this page:
https://www.php.net/manual/en/function.socket-select.php
I was looking for a way to have a socket server that does not chew up CPU cycles and only does something when there is something to do. That solution blocks while it is waiting for connections to do something then it processes them.
Pay special attention to the comments about setting $tv_sec to null as this is the "Make Work" flag that prevents chewing up the CPU.
This allows one to create a socket server in PHP that does not chew up CPU and also processes multiple connections.
The only missing piece of the puzzle is disconnecting clients that do not disconnect themselves.
Unless there is a connection timeout that can be set I think the solution is to set $tv_sec to some suitable value, like 2 seconds, and then track the time a connection has been connected then disconnect it if it breaches some time. The downside to this is it will use CPU but if you unblock every 2 seconds then you can use that to process timeouts etc. Otherwise, you have to rely on clients disconnecting. That may not be an issue for you but in my particular usecase it is.