php - preg_match to sanitize input for the best security
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I am working on a wordpress website (i am new to web development). I installed a theme and now I am looking to improve it and make it suit my needs. Regarding the register form, the theme's code to check for invalid characters in the password is this:
else if(preg_match("/^([a-zA-Z0-9@#-_$%^&+=!?]{1,20})$/", $data['user_password'])==0) {
SendtoUSER::$messages[]=__('Forbidden characters detected', 'mytheme');
and for the username is this
if(preg_match('/[@\s]/', $username)) {
$valid=false;
}
I did some research and i understand most of the expression"/^([a-zA-Z0-9@#-_$%^&+=!?]{1,20})$/" - what i don't get is why ; is still valid to use (i observed that removing#-_prevents; from working, so is#-_ an inverval?) My question is what@#-_$%^&+=!? means in the expression? Is this code good enough, what are some good practices to implement preg_match for max security? Thanks in advance for your reply.
Answer
Solution:
I guess in WordPress, thesanitize_text_field will be the best solution to do it. You can validate it:
if ( sanitize_text_field( $data['user_password'] ) !== $data['user_password'] ) {
$valid=false;
}
Also, I've checked how it works on the Profile page, and it looks like in the core, it validates as:
$pass1 = trim( $_POST['pass1'] );
//...
// Check for "\" in password.
if ( false !== strpos( wp_unslash( $pass1 ), '\\' ) ) {
$errors->add( 'pass', __( '<strong>Error</strong>: Passwords may not contain the character "\\".' ), array( 'form-field' => 'pass1' ) );
}
Probably the best solution is copying the WordPress solution as well.
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