PHP Query String Limit

Question

I have PHP 5.1.6 (cli) installed and whenever the GET query string is more than 128 characters it fails with HTTP 406 Not Acceptable error. Any suggestions how I can fix this so can use more than 128 characters? POST is not an option.

The error is being returned by the server so don't think it's browser issue. And the reason I think it's PHP and not Apache is because it works fine with an HTML file.

GET /test.php?phptestof129characterstring-NEW-WOVEN-FENCE-PANELS-GARDEN_W0QQitemZ200303392512QQihZ010QQcategoryZ139954QQtcZphotoQQcmdZViewItem
HTTP/1.1
Host: *****
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-gb,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Cookie: agent_name=Tim

HTTP/1.1 406 Not Acceptable
Date: Tue, 03 Feb 2009 12:05:33 GMT
Server: Apache/2.2.3 (Red Hat)
X-Powered-By: PHP/5.1.6
Content-Length: 0
Connection: close
Content-Type: text/html

---

GET /test.html?phptestof129characterstring-NEW-WOVEN-FENCE-PANELS-GARDEN_W0QQitemZ200303392512QQihZ010QQcategoryZ139954QQtcZphotoQQcmdZViewItem
HTTP/1.1
Host: *****
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.0.5) Gecko/2008120122 Firefox/3.0.5
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-gb,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Cookie: agent_name=Tim

HTTP/1.1 200 OK
Date: Tue, 03 Feb 2009 12:18:19 GMT
Server: Apache/2.2.3 (Red Hat)
Last-Modified: Fri, 19 Dec 2008 15:01:17 GMT
ETag: "156960d-221-94be8940"
Accept-Ranges: bytes
Content-Length: 545
Connection: close
Content-Type: text/html

Answer 1

Do you have mod_security enabled on your webserver? It sounds like something it would do. If so, you may be able to disable locally inside your <VirtualHost> block or with an .htaccess file for v1.x

<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>

Version 2.x has different configuration syntax:

<IfModule mod_security2.c>
    SecRuleEngine Off
</IfModule>

That's a bit of a brute force approach, you may want to read the documentation to see how you might allow particular URIs to pass through. See also Handling False Positives and Creating Custom Rules

Answer 2

As a work-around, you can try using Javascript to put the data in cookies. The cookies will be sent automatically with every GET request, and give you an extra 2KB of data space (if I'm not mistaken).

This is very risky if you don't want to transmit that data with every request, so generally speaking I would recommend against it.

Answer 3

It's a long shot, but try adding:

header('Content-Type: text/html');

to your server-side code. If that doesn't help, check your Apache configuration, maybe it's misconfigured so that PHP files can't emit text/html MIME type. If that doesn't help, how about setting up Apache so that .html files are treated as PHP and rename the target script to .html?

BTW, from http://www.checkupdown.com/status/E406.html :

A client (e.g. your Web browser or our CheckUpDown robot) can indicate to the Web server characteristics of the data it will accept back from the Web server. This is done using 'accept headers' of the following types:

• Accept: The MIME types accepted by the client. For example, a browser may only accept back types of data (HTML files, GIF files etc.) it knows how to process.
• Accept-Charset: The character sets accepted by the client.
• Accept-Encoding: The data encoding accepted by the client e.g. the file formats it understands.
• Accept-Language: The natural languages (English, German etc.) accepted by the client.
• Accept-Ranges: Whether the client accepts ranges of bytes from the resource i.e. a portion of the resource.

If the Web server detects that the data it wants to return is not acceptable to the client, it returns a header containing the 406 error code.

Answer 4

Have found answer thanks to comment from Ben.

Although this generates 406 error: test.php?129+characters

This works fine: test.php?data=129+characters

So my guess is that in the first instance PHP is attempting to use the 129 characters as name in $_GET array whereas the second example has only 4 characters for the name and the rest is assigned as value, so array must have 128 character limit for index name.