Possible Duplicate:
PHP: “Notice: Undefined variable” and “Notice: Undefined index”
So, I am currently learning PHP and was reading on a book about the md5 function for passwords, so I decided to give it a try and see how it goes. I also decided to use the POST method rather than the GET, since I saw people saying that it is safer and doesn't let the variables appearing on the URL.
For my testing project I made a very simple form, which follows:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title></title>
</head>
<body>
<form action="dologin" method="POST">
<table border="0">
<tbody>
<tr>
<td>Username:</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>Password:</td>
<td><input type="password" name="password"></td>
</tr>
</tbody>
</table>
<input type="submit" value="Login">
</form>
</body>
</html>
The problem is that when I enter the values on BOTH fields and click "Login" I get the following output on the other PHP file.
Notice: Undefined index: username in C:\xampp\htdocs\md5\home\dologin\index.php on line 11
Username non existent
Here follows the code for the "/dologin/index.php" file
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title></title>
</head>
<body>
<?php
mysql_connect("localhost", "root") or die(mysql_error());
mysql_select_db("test") or die(mysql_error());
$query = "SELECT password FROM users WHERE username='".$_POST['username']."'";
$result = mysql_query($query);
$row = mysql_num_rows($result);
if(isset($row)){
$password = (mysql_result($result,$row - 1));
$enteredpassword = md5("w@#$@#".$_GET['password']."^#3f%#^");
if($password == $enteredpassword){
if(!isset($_COOKIE['PHPSESSID'])){
session_start();
}
$_SERVER['LOGIN_STATUS'] = true;
} else {
die("Access denied");
}
} else {
die("Username non existent");
}
?>
</body>
</html>
Any help at all on my issue is very much appreciated, thank you for reading.
This question is related to
php
http-post
undefined-index
first of all,
be sure that there is a post
if(isset($_POST['username'])) {
// check if the username has been set
}
second, and most importantly, sanitize the data, meaning that
$query = "SELECT password FROM users WHERE username='".$_POST['username']."'";
is deadly dangerous, instead use
$query = "SELECT password FROM users WHERE username='".mysql_real_escape_string($_POST['username'])."'";
and please research the subject sql injection
You should check if the POST['username'] is defined. Use this above:
$username = "";
if(isset($_POST['username'])){
$username = $_POST['username'];
}
"SELECT password FROM users WHERE username='".$username."'"
Source: Stackoverflow.com