Fsockopen UDP connection problem

@Vanker

Are you remembering to add udp:// in front of the server address? http://php.net/manual/en/function.fsockopen.php#example-5028

@Vanker

It’s really dependent on what you’re passing as $host. I’ll use 111.222.33.44 as our fake IP.

Instead of using something such as:

$this->fp = fsockopen('111.222.33.44', 29070, $this->errno, $this->errstr, 5);

… then it most likely will fail or cause problems. Instead, I’d recommend prefixing the IP with udp.

$this->fp = fsockopen('udp://111.222.33.44', 29070, $this->errno, $this->errstr, 5);

I created a very basic function to test fsockopen, this is what I used.

function udpStatus( $host, $port )
{
    $fp = fsockopen( "udp://" . $host, $port, $errNum, $errStr, 1.0 );

    if ( ! $fp )
    {
        return false;
    }
    else
    {
        fclose( $fp );

        return true;
    }
}

In the function, you can see that $host is prefixed with udp://. We can then run a conditional check using:

if ( udpStatus( 'HOST_OR_IP', 29070 ) )
{
    echo 'Connection Status: Success';
}
else
{
    echo 'Connection Status: Failed';
}

Replace HOST_OR_IP with the host or IP you’re connecting to.

With the udp:// prefix, the result from one Droplet connecting to another is Success. If we remove the prefix from the function, it fails.

@Vanker

Doing a little more digging :-). On the same two NYC 3 Droplets, I setup one droplet as a sender and the other as a receiver for UDP.

One the first droplet, I created a file called udp.php and within it, I used the core example that PHP provides for socket_create.

<?php
$sock = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);

$msg = "Ping!";
$len = strlen($msg);

socket_sendto($sock, $msg, $len, 0, 'REMOTE_IP', 29070);
socket_close($sock);

Where REMOTE_IP is the IP of the second Droplet that is supposed to receive the message. All the above is going to do is send a message “Ping!”.

On the second Droplet, I created a PHP file called receiver.php and within it, I placed:

<?php
//Create socket.
$socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
if (!$socket) { die("socket_create failed.\n"); }

//Set socket options.
socket_set_nonblock($socket);
socket_set_option($socket, SOL_SOCKET, SO_BROADCAST, 1);
socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1);
if (defined('SO_REUSEPORT'))
    socket_set_option($socket, SOL_SOCKET, SO_REUSEPORT, 1);

//Bind to any address & port 29070.
if(!socket_bind($socket, '0.0.0.0', 29070))
    die("socket_bind failed.\n");

//Wait for data.
$read = array($socket); $write = NULL; $except = NULL;
while(socket_select($read, $write, $except, NULL)) {

    //Read received packets with a maximum size of 5120 bytes.
    while(is_string($data = socket_read($socket, 5120))) {
        echo $data;
    }

}

That snippet came from here

On the second droplet, to start the receiver, all I did was run php receiver.php from the command line. Since it’s within a while loop, it’ll keep running until I exit the script.

I then went to the other droplet and ran php udp.php and “Ping!” shows up on the other end, as was expected.

So you may want to look in to the Sockets Library instead of using fsockopen in this particular case.

http://php.net/manual/en/book.sockets.php