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:
if(!$handled)
{
$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;
}

into:
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!

Charset handling proposal in AMFPHP

Patrick Mineault makes a proposal for the charset handling in AMFPHP

[..] that should put an end to problems with Unicode and native character set handling between PHP and Flash, a problem that has palgued AMFPHP for a long time

To use charset handling in the new CVS version, you will need to call the setCharsetHandler function from your gateway.php file, like this:

$gateway->setCharsetHandler("iconv", "latin1", "latin1");

Detail for setCharsetHandler method: setCharsetHandler(string mode, string phpCharset, string sqlCharset) The mode can be: 1. none (don’t do anything) 2. iconv (uses the iconv libray for reencoding) 3. mbstring (uses the mbstring library for reencoding) 4. recode (uses the recode library for reencoding) 5. utf8_decode (uses the XML function utf8_decode and encode for reencoding – ISO-8859-1 only) I haven’t tested it already, but I’m sure this is a great step toward a solution of the charset problem!

http://www.amfphp.org/wiki/doku.php?id=charset_issue