PHP registration form print error - php

Question

Finished making a php/mysql login system. I've also made a registration system that works, but I need to make it print out a error in the html if the email/username is already registered or if the username or password from the inputs is missing etc.
As it is now, it will automatically die and prints out the error message on a empty page.
It looks like this:
if(empty($_POST['password']))
{
die("Please enter a password");
}
I have tried this:
$errors = array();
if(empty($_POST['password']))
{
$errors[] = 'Please enter a password';
}
And then print it out inside the html. But it will ignore the password input and just register the user account anyway (with a encrypted password, in phpmyadmin).
It looks like has to die someway, but how should i do it?
Here's the whole code:
<?php
require("*mysql_connection file*");
if(!empty($_POST))
{
if(empty($_POST['username']))
{
die("Please enter a username.");
}
$errors = array();
if(empty($_POST['password']))
{
$errors[] = 'Please enter your password';
}
if(!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL))
{
die("Invalid E-Mail Address");
}
$query = "
SELECT
1
FROM users
WHERE
username = :username
";
$query_params = array(
':username' => $_POST['username']
);
try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die("Failed to run query: " . $ex->getMessage());
}
$row = $stmt->fetch();
if($row)
{
die("This username is already in use");
}
$query = "
SELECT
1
FROM users
WHERE
email = :email
";
$query_params = array(
':email' => $_POST['email']
);
try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die("Failed to run query: " . $ex->getMessage());
}
$row = $stmt->fetch();
if($row)
{
die("Email already registered.");
}
$query = "
INSERT INTO users (
username,
password,
salt,
email
) VALUES (
:username,
:password,
:salt,
:email
)
";
$salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647));
$password = hash('sha256', $_POST['password'] . $salt);
for($round = 0; $round < 65536; $round++)
{
$password = hash('sha256', $password . $salt);
}
$query_params = array(
':username' => $_POST['username'],
':password' => $password,
':salt' => $salt,
':email' => $_POST['email']
);
try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die("Failed to run query: " . $ex->getMessage());
}
header("Location: *login page*");
die("Redirecting to *login page*");
}
?>

Answer 1

<?php
require("*mysql_connection file*");
if(!empty($_POST))
{
if(empty($_POST['username']))
{
die("Please enter a username.");
}
$errors = array();
if(empty($_POST['password']))
{
$errors[] = 'Please enter your password';
}
if(!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL))
{
die("Invalid E-Mail Address");
}
$query = "
SELECT
1
FROM users
WHERE
username = :username
";
$query_params = array(
':username' => $_POST['username']
);
try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die("Failed to run query: " . $ex->getMessage());
}
$row = $stmt->fetch();
if($row)
{
die("This username is already in use");
}
$query = "
SELECT
1
FROM users
WHERE
email = :email
";
$query_params = array(
':email' => $_POST['email']
);
try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die("Failed to run query: " . $ex->getMessage());
}
$row = $stmt->fetch();
if($row)
{
die("Email already registered.");
}
$query = "
INSERT INTO users (
username,
password,
salt,
email
) VALUES (
:username,
:password,
:salt,
:email
)
";
$salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647));
$password = hash('sha256', $_POST['password'] . $salt);
for($round = 0; $round < 65536; $round++)
{
$password = hash('sha256', $password . $salt);
}
$query_params = array(
':username' => $_POST['username'],
':password' => $password,
':salt' => $salt,
':email' => $_POST['email']
);
if (empty($errors)) { /********* EDITS ***********/
try
{
$stmt = $db->prepare($query);
$result = $stmt->execute($query_params);
}
catch(PDOException $ex)
{
die("Failed to run query: " . $ex->getMessage());
}
}/********* EDITS ***********/
header("Location: *login page*");
die("Redirecting to *login page*");
}
?>
It's far from optimal, but I can't be arsed to rewrite your whole code.
Major remark is to use openssl_random_pseudo_bytes instead of your own stuff to make up for salt, or you can just take IV out of mcrypt family of functions.

Answer 2

Try this :-
if(""== trim($_POST['password']))
{
die("Please enter a password");
}
else //password is entered
{
//your code
}