Only execute script if entered email is from a specific domain

Question

I am trying to create a script that will only execute its actions if the email address the user enters is from a specific domain. I created a regex that seems to work when testing it via regex utility, but when its used in my PHP script, it tells me that valid emails are invalid. In this case, I want any email that is from @secondgearsoftware.com, @secondgearllc.com or asia.secondgearsoftware.com to echo success and all others to be rejected.

$pattern = '/\b[A-Z0-9\._%+-]+@((secondgearsoftware|secondgearllc|euro\.secondgearsoftware|asia\.secondgearsoftware)+\.)+com/';
$email = urldecode($_POST['email']);
if (preg_match($pattern, $email))
{
    echo 'success';
}
else
{
    echo 'opposite success';
}

I am not really sure what's futzed with the pattern. Any help would be appreciated.

Answer 1

You probably need to use /\b[A-Z0-9\._%+-]+@((euro\.|asia\.)secondgearsoftware|secondgearllc)\.com/i (note the i at the end) in order to make the regex case-insensitive. I also dropped the +s as they allow for infinite repetition which doesn't make sense in this case.

Answer 2

Your regular expression is a bit off (it will allow [email protected]) and can be simplified:

$pattern = '/@((euro\.|asia\.)?secondgearsoftware|secondgearllc)\.com$/i';

I've made it case-insensitive and anchored it to the end of the string.

There doesn't seem to be a need to check what's before the "@" - you should have a proper validation routine for that if necessary, but it seems you just want to check if the email address belongs to one of these domains.

Answer 3

I suggest you drop the regex and simply use stristr to check if it matches. Something like this should work:

<?php
// Fill out as needed
$domains = array('secondgearsoftware.com', 'secondgearllc.com');

$email = urldecode($_POST['email']);
$found = false;
for(i=0;i<count($domains);i++)
{
    if ($domains[i] == stristr($email, $domains[i]))
        $found = true;
}

if ($found) ...
?>

The function stristr returns the e-mail address from the part where it found a match to the end, which should be the same as the match in this case. Technically there could be something prior to the domains (fkdskjfsdksfks.secondgeartsoftware.com), but you can just insert "@domainneeded.com" to prevent this. This code is also slightly longer, but easily extended with new domains without worrying about regex.

Answer 4

Here's an easy to maintain solution using regular expressions

$domains = array(
    'secondgearsoftware',
    'secondgearllc',
    'euro\.secondgearsoftware',
    'asia\.secondgearsoftware'
);
preg_match("`@(" .implode("|", $domains). ")\.com$`i", $userProvidedEmail);

Here's a couple of tests:

$tests = array(
    '[email protected]',
    '[email protected]',
    '[email protected]',
    '[email protected]',
    '[email protected]',
    '[email protected]',
    '[email protected]',
    '[email protected]'
);

foreach ( $tests as $test ) { 
    echo preg_match("`@(" .implode("|", $domains). ")\.com$`i", $test), 
         " <- $test\n";
}

Result (1 is passing of course)

1 <- [email protected]
1 <- [email protected]
0 <- [email protected]
0 <- [email protected]
0 <- [email protected]
1 <- [email protected]
0 <- [email protected]
1 <- [email protected]