PHP if statement not working as expected with filter_var

Question

I have a form which posts variables through to a PHP processing script.

Before the processing script begins I would like to sanitize the posted variables:

$Contact_Name = filter_var($_POST['contactName'], FILTER_SANITIZE_STRING);
$Company = filter_var($_POST['company'], FILTER_SANITIZE_STRING);
$Telephone = filter_var($_POST['telephone'],FILTER_SANITIZE_NUMBER_INT);

So far. So good.

But sanitizing and validating the email is a real pain.

$Email = $_POST['email'];
$Sanitised_Email = filter_var($Email, FILTER_SANITIZE_EMAIL);
$Email_is_valid = filter_var($Email, FILTER_VALIDATE_EMAIL);

If $Sanitised_Email isn't the same as $Email, I want to go back to the form page:

if ($Sanitised_Email != $Email) {
header('Location: http://'.$_SERVER['HTTP_HOST'].'/form.php');
}

If $Email_is_valid is false, I want to go back to the form page:

if ($Email_is_valid == FALSE) {
header('Location: http://'.$_SERVER['HTTP_HOST'].'/form.php');
}

Neither of these two if statements work when I enter an email which is both invalid and in need of sanitisation such as:

i.am.(totally)invalid@asanemailaddress

What am I doing wrong? Have I messed up my syntax somewhere?

Why do you need to sanitize instead of just checking if the supplied address is valid? — PeeHaa
– PeeHaa, Commented Feb 5, 2016 at 19:23
One other note: consider passing an error message back to the form rather than a plain-jane re-direct (thus likely leaving the user wondering why the form didn't submit). You could improve your current method with a simple url parameter that triggers an error display on the form, for example. — devlin carnate
– devlin carnate, Commented Feb 5, 2016 at 19:25
Do you want to check wether the sanitized email is valid after its been cleaned? Or do you really want to run both functions on the user input email? — dmgig
– dmgig, Commented Feb 5, 2016 at 19:27
After looking @RocketHazmat is it possible your "HTTP_HOST" is not returning anything? I've had that not be populated (or populated incorrectly) as a server variable before. stackoverflow.com/questions/2297403/http-host-vs-server-name — dmgig
– dmgig, Commented Feb 5, 2016 at 19:29
is the code you mentioned at the top of the PHP page and are you sure you have not already sent output before trying to send header information. — Dave
– Dave, Commented Feb 5, 2016 at 19:42

Daniel MK · Accepted Answer · 2016-02-05 19:35:35Z

2

Syntax seems good. I think your problem is that you are not ending your script after setting header. Change it to:

if (condition) {
        header('Location: www.example.com');
        exit();
}

Learn how to debug your code, you can simply echo something to know if you are entering a structure or not. A good practice is also to create a function to redirect pages, it's quick, clean and save some lines:

function redirect($page){
        header('Location: http://'.$_SERVER['HTTP_HOST']."/$page.php");
        exit();
}

answered Feb 5, 2016 at 19:35

Daniel MK

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2 Comments

Rounin Over a year ago

That's a priceless answer, @Daniel MK - thank you so much! The problem, as you correctly identified was that I wasn't ending the script with exit(); after setting the header. (I've used header('Location: '); several times before, but only ever at the end of scripts, so I've never been aware that this is necessary.) Setting up a redirect(page); function is a great idea and using echo statements to verify whether conditions are being followed properly is a very smart time-saver. Thank you for all your tips. If I could give you extra points, I would.

Daniel MK Over a year ago

I'm glad I've helped you, you're welcome, thanks for your nice words =)

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