Php – Mysteriously empty $_POST array

PHP

I have the following HTML/PHP page:

<?php
if(empty($_SERVER['CONTENT_TYPE'])) {
    $type = "application/x-www-form-urlencoded";
    $_SERVER['CONTENT_TYPE'] = $type;
}

echo "<pre>";
var_dump($_POST);
var_dump(file_get_contents("php://input"));
echo "</pre>";
?>

<form method="post" action="test.php">
<input type="text" name="test[1]" />
<input type="text" name="test[2]" />
<input type="text" name="test[3]" />
<input type="submit" name="action" value="Go" />
</form>

As you can see, the form will submit and the expected output is a POST array with one array in it containing the filled in values and one entry "action" with the value "Go" (the button). However, no matter what values I enter in the fields; the result is always:

array(2) {
  ["test"]=>
  string(0) ""
  ["action"]=>
  string(2) "Go"
}
string(16) "test=&action=Go&"

Somehow, the array named test is emptied, the "action" variable does make it through.

I've used the Live HTTP Headers extension for Firefox to check whether the POST fields get submitted, and they do. The relevant information from Live HTTP Headers (with a, b and c filled in as values in the textboxes):

Content-Type: application/x-www-form-urlencoded
Content-Length: 51
test%5B1%5D=a&test%5B2%5D=b&test%5B3%5D=c&action=Go

Does anybody have any idea as to why this is happening? I'm freaking out on this one, it has cost me so much time already…

Update:

We've tried this on different servers, on Windows boxes it does work, on the Ubuntu server with PHP version 5.2.4 (with Suhosin), it doesn't. It even works on a different server, also with Ubuntu and the same PHP version, also with Suhosin installed.

I've diffed the two files, this is the output (diff php.ini phps.ini):

270c270
< memory_limit = 32M
---
> memory_limit = 16M      ; Maximum amount of memory a script may consume (16MB)
415c415
< variables_order = "EGCSP"
---
> variables_order = "EGPCS"
491d490
< include_path = ".:"
1253a1253,1254
> extension=mcrypt.so
>

In this phps.ini is the one from the server on which it works and php.ini is the current one. Looks as if there are no problems here, right?

Best Answer

There's a number of possible reasons why the post array could be empty - chances have that it comes back to human/developer error. I experienced this exact issue when upgrading from PHP 5.2 to 5.4, it was simple but it took hours of troubleshooting to find the bug. In our config.php file we had the below statement to process $_POST arrays:

if (!get_magic_quotes_gpc()) {
    if (isset($_POST)) {
        foreach ($_POST as $key => $value) {
            $_POST[$key] =  trim(addslashes($value));
        }
    }

Magic quotes was once on, and in PHP versions up to 5.2 the above worked fine but anything above version 5.2 it won't process and an empty array is returned.

If you don't have error_reporting() switched on I suggest that you do and I'm sure you'll be able to troubleshoot the issue.

You should also check for deprecated system features, like "magic_quotes" as using them simply fails to return results. I hope this helps. Best of luck. JCS :)

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