POST METHOD PROBLEM (If input http://,ftp://)

[eluser]Unknown[/eluser]
After I input http:// in textfield or textarea. I can't echo that variable(show nothing). please kindly check code as below.

It's work when i test on localhost . But when i test on external server It's not work.
And when i tested without CI (only php) like below It's work also.

Code:

<form method="post" action="doTest.php">
Website: <input type="text" name="website">
<input type="submit">
</form>

doTest.php

Code:

<?
echo $_POST['website'];
?>

environment:Codeigniter, Godaddy(php5.4 cpanel) Thank you in advance.

This is my code in CI:

Simple Code: Controller (Welcome)

Code:

public function test()
{
    $this->load->view('test');
}
public function doTest()
{
    $var = $this->input->post('bio');
    echo $var;
}

View (test.php):

Code:

<form action='../welcome/doTest' method="post">
<input class="form-control" type="text" name="bio"/>
<button class="btn btn-default" type="submit">Submit</button>
&lt;/form&gt;

work List:

aaaaa
'http://' (single quote added)
htp
://

not work:

http://
http://www.example.com
ftp://


sorry for poor english, Thank you in advance.