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Alessandro Crugnola on October 11, 2007 in amfphp

AMFPHP and mbstring

These days I was working on a flex 2/amfphp project and I discovered a very strange issue accidentally.
With PHP 5.2.4 installed both on local and remote server, the local amfphp works and the remote gave errors.

Connecting to the service browser I was receiving the error "Channel.Ping.Failed" error and investingating a bit more in the fault message I discovered that the source error was:

The class {Amf3Broker} could not be found under the class path {/var/htdocs/amfphp/services/amfphp/Amf3Broker.php} 

and the Amf3Broker php class does not exists anywhere in amfphp! But in the Actions.php file on line 78 I found this:

	$uriclasspath = "amfphp/Amf3Broker.php";
	$classpath = $baseClassPath . "amfphp/Amf3Broker.php";
	$classname = "Amf3Broker";
	$methodname = "handleMessage";

That's the strange thing because the $handled variable should be true 'cause usually the first request sent by flash is a $messageType = "flex.messaging.messages.CommandMessage". So I continued in my investigation logging all the messages that php was receiving.
So at the end I discovered that amfphp didn't deserialize the amf data correctly! All the packet were corrupted (that's why $messageType wasn't handled), all the strings were not correctly parsed.
Finally I discovered the reason. It's because mbstring.
The only difference between the remote server and the local server is the php.ini setting about mbstring overload and the others mbstring settings.
The remote server has mbstring.func_overload = 2, that means all the strings functions are affected and that's why the amfphp methods were returing corrupted data.
In fact I just changed this method into AMFDeserializer.php:

    function readBuffer($len)
    	$data = substr($this->raw_data,$this->current_byte,$len);
    	$this->current_byte += $len;
    	return $data;


    function readBuffer($len)
    	$data = "";
    	for($i = 0; $i < $len; $i++)
    		$data .= $this->raw_data{$i + $this->current_byte};
    	$this->current_byte += $len;
    	return $data;

 and the original error disappeared! Obviously I got other errors later, that's because there are many other string functions in amfphp.. but at least I found the cause.

In fact, removing the mbstring.func_overload in the php.ini everything worked again! 



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I tried the changes you suggested, from removing mbstring.func_overload to setting it to all of its possible values, even to altering AMFDeserializer.php, all to no avail. Finally, I decided to search the net, and found that most hits resulted in a blog post to this one! Cool, but not helpful. Finally, I located a forum post: Kake said, and I quote: "Ultimately, I discovered the problem was user error in my case. I had a service named Gallery which had a number of methods in it. After I connected to the gateway, I tried calling one of the methods, but without prefacing the service name. I guess working in Flex fuddled up my thinking, since you connect to a specific service there. At any rate, once I changed my NetConnection calls from this:"loadGallery", new Responder()); to this:"Gallery.loadGallery", new Responder()); it worked just fine. The broker problem resulted from it not being able to find a way to handle root-level methods not associated with a service. It works great now, and is very fast. And I'm still dumb... "
Same here: none of both works me neither
I'm on a shared host, so cannot remove php.ini settings, but I CAN override them. I tried: [mbstring] mbstring.func_overload = 0 and: [mbstring] mbstring.func_overload = 7 ... but neither worked. I tried your code change, but that didn't work either. What were your mbstring php.ini settings on your local host?

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