ajax - Why are $_POST variables getting escaped in PHP?

Question

When my PHP script receives data from an AJAX POST request, the $_POST variables are escaped. The really strange thing is that this only happens on my production server (running PHP 5.2.12 on Linux) and not on my local server (running PHP 5.3.1 on Windows).

Here is the AJAX code:

var pageRequest = false;
if(window.XMLHttpRequest)     pageRequest = new XMLHttpRequest();
else if(window.ActiveXObject) pageRequest = new ActiveXObject("Microsoft.XMLHTTP");

pageRequest.onreadystatechange = function() { }

var q_str = 'data=' + " ' ";

pageRequest.open('POST','unnamed_page.php',true);

pageRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
pageRequest.setRequestHeader("Content-length", q_str.length);
pageRequest.setRequestHeader("Connection", "close");

pageRequest.send(q_str);

Is there any reason this is happening? And how should I fix this so that it works on both servers?

Edit: I have the following settings for magic_quotes:

                     Local   Master

magic_quotes_gpc     On      On
magic_quotes_runtime Off     Off
magic_quotes_sybase  Off     Off

Answer 1

You probably have magic quotes enabled on the Linux server: magic_quotes

When magic_quotes are on, all ' (single-quote), " (double quote), (backslash) and NUL's are escaped with a backslash automatically.

They're a good thing to disable, as they are going to be removed from PHP 6 onwards anyway. You should also be able to disable them inside your script: set-magic-quotes-runtime You can't deactivate the part of magic_quotes responsible for escaping POST data during runtime. If you can, disable it in php.ini. If you can't do that, do a check whether the magic_quotes are enabled, and do a stripslashes() on any content you fetch from POST:

if (get_magic_quotes_gpc())  
 $my_post_var = stripslashes($_POST["my_post_var"]);