你可以请专家给我一些关于这段代码的信息吗？我错过了一些安全漏洞？你能看到任何潜在的威胁吗？我可以做得更好吗？
我还在学习:)谢谢
<?php
if (isset($_POST['username'])) {
$username = mysql_real_escape_string($_POST['username']);
$password = mysql_real_escape_string($_POST['password']);
$password2 = mysql_real_escape_string($_POST['password2']);
$encrypted_password = md5($password);
// remove eventuakl space
foreach($_POST as $key => $val) $_POST[$key] = trim($val);
// check if username is taken
$query = mysql_query("SELECT COUNT(*) FROM users WHERE username = '$username'");
if (mysql_result($query, 0) > 0) {
$reg_error[] = 0;
}
// make sure username only cosist of at least 3 letters, numbers or _ -
if (!preg_match('/^[a-zA-Z0-9_-]{3,}$/', $username)) {
$reg_error[] = 4;
}
// check for empty fields
if (empty($username) || empty($password) || empty($password2)) {
$reg_error[] = 2;
}
// check if the passwords match
if ($password != $password2) {
$reg_error[] = 3;
}
// save if error is unset
if (!isset($reg_error)) {
mysql_query("INSERT INTO users (username, password, registered, registration_ip)
VALUES('$username', '$encrypted_password', '".time()."', '".$_SERVER['SERVER_ADDR']."')");
$_SESSION['id'] = mysql_insert_id();
header('refresh: 3; url=/home');
}
}
?>
的login.php
if (isset($_POST['username'])) {
$username = mysql_real_escape_string($_POST['username']);
$password = mysql_real_escape_string($_POST['password']);
$md5_password = md5($password);
$query = mysql_query("SELECT id FROM users WHERE username = '$username' and password = '$md5_password'");
if (mysql_num_rows($query) == 0) {
header("Location: ".$_SERVER['REQUEST_URI']."");
exit;
}
// set session
$_SESSION['id'] = mysql_result($query, 0, 'id');
header("Location: /");
exit;