Socket_recvfrom issues

php_dev

Hey all,

I have a script that sends a simple message on a socket, and then awaits a reply.  As it is waiting reply, it is echoing some simple graphics to let the user know something is still happening.  The message sent, or even the one received is not important-- however my code always freezes before the loop can take effect.  Something in socket_recvfrom is not letting it continue listening on the first try.  My code is posted below.

$out=" ";
$count=0;
$port_test=NULL;
$from=NULL;
do {
	$count=$count+1;
	echo something to entertain user
	flush();
	ob_flush();
	$test=socket_recvfrom($sock,$out, 1024, 2, $from, $port_test);
	sleep(2);
	if($out=="WAITDONE"){
		$count=31;
	}
}while($count < 30);

Is there some sort of setting for recv_from that will allow it to simply check, and then continue on. Right now the remote host has to send some garbage message to get things moving onto the next iteration.

Any help would be appreciated!

sneakyimp

I'm not certain, but I believe that the function socket_recvfrom is a 'blocking' function -- meaning that code execution halts while you are waiting for it to complete doing whatever it is doing. It is possible to set a socket to not block using [man]socket_set_nonblock[/man], but this would just result in an error occurring if you try to call socket_recvfrom before any data is there to be read.

You might try outputting some HTML to show graphics BEFORE you call socket_recvfrom. This may not work either due to buffering behavior between the server and browser.

php_dev

I think you must be right. In my script, I output a few graphics, and then make the initial call to socket_recvfrom and it halts until the other program sends me something-- even garbage data just to get it into the loop. I appreciate the help! This is some new territory for me, but I agree with you--all of my tests seem to indicate that the function needs something to be on the socket before it returns a value.

Thanks again!

sneakyimp

You might consider putting the graphics in one file which contains an IFRAME and then load your socket code into the IFRAME. Your socket code could output some Javascript in the IFRAME which reloads the main window with the subsequent steps.

Or you could do AJAX or something.