Question

我有以下代码来更新我的数据库（更改密码）。我知道我使用的方法有点旧，但该网站仅用作测试。我已经从其他网站复制了代码并且之前使用过它来执行INSERT查询（不是UPDATE）。

由于某种原因，数据库没有更新，我收到以下错误消息：

阵警告：无法修改标头信息 - 已在/ home / content / 47/11368447 / html / CCC / changepassword中发送的标头（在/home/content/47/11368447/html/CCC/changepassword.php:64处开始输出）。第75行的PHP 重定向到stafflist.php

我是php的新手，感谢我能得到的所有帮助。

以下是代码：

// First we execute our common code to connection to the database and start the session 
require("common.php"); 

  $id = $_GET['id'];

// This if statement checks to determine whether the registration form has been submitted 
// If it has, then the registration code is run, otherwise the form is displayed 
if(!empty($_POST)) 
{  
    // Ensure that the user has entered a non-empty password 
    if(empty($_POST['password'])) 
    { 
        die("Please enter a password."); 
    } 

    // Ensure that the user has entered a non-empty username 
    if(empty($_POST['confirmpassword'])) 
    { 
        // Note that die() is generally a terrible way of handling user errors 
        // like this.  It is much better to display the error with the form 
        // and allow the user to correct their mistake.  However, that is an 
        // exercise for you to implement yourself. 
        die("Please confirm your password."); 
    } 

     if ($_POST['password'] == $_POST['confirmpassword']) {

    // An INSERT query is used to add new rows to a database table. 
    // Again, we are using special tokens (technically called parameters) to 
    // protect against SQL injection attacks. 
    $query = "UPDATE Staff SET password=:password, salt=:salt WHERE id=:id"; 

    // A salt is randomly generated here to protect again brute force attacks 
    // and rainbow table attacks.  The following statement generates a hex 
    // representation of an 8 byte salt.  Representing this in hex provides 
    // no additional security, but makes it easier for humans to read. 
    $salt = dechex(mt_rand(0, 2147483647)) . dechex(mt_rand(0, 2147483647)); 

    // This hashes the password with the salt so that it can be stored securely 
    // in your database.  The output of this next statement is a 64 byte hex 
    // string representing the 32 byte sha256 hash of the password.  The original 
    // password cannot be recovered from the hash. 
    $password = hash('sha256', $_POST['password'] . $salt); 

    // Next we hash the hash value 65536 more times.  The purpose of this is to 
    // protect against brute force attacks.  Now an attacker must compute the hash 65537 
    // times for each guess they make against a password, whereas if the password 
    // were hashed only once the attacker would have been able to make 65537 different  
    // guesses in the same amount of time instead of only one. 
    for($round = 0; $round < 65536; $round++) 
    { 
        $password = hash('sha256', $password . $salt); 
    }  

    try 
    { 
        // Execute the query to create the user 
        $stmt = $db->prepare($query); 
        $stmt->execute(array(
        ':password' => $password,
        ':salt' => $salt,
        ':id' => $id)); 
        echo $db->errorInfo();

    } 
    catch(PDOException $ex) 
    { 
        // Note: On a production website, you should not output $ex->getMessage(). 
        // It may provide an attacker with helpful information about your code.  
        die("Failed to run query: " . $ex->getMessage()); 
    } 

    // This redirects the user back to the login page after they register 
    header("Location: stafflist.php");

     // Calling die or exit after performing a redirect using the header function 
    // is critical.  The rest of your PHP script will continue to execute and 
    // will be sent to the user if you do not die or exit. 
    die("Redirecting to stafflist.php"); 

}

die("Passwords do not match.");  
}

谢谢，乔

Answer 1

此错误表示您在使用标题或会话类之前输出了一些内容。

仔细检查代码中的空格字符或其他输出，以确保在此行之前没有echo任何内容：

header("Location: stafflist.php");

Answer 2

我认为您的die()之一在控件到达行header("Location: stafflist.php");之前被触发

最有可能的是，die()正在向response写出一些内容。在写完header之后，您无法设置response值。

Answer 3

验证您使用的是ANSI编码还是没有BOM的UTF-8，因为使用UTF-8（带BOM）会在文件的最开头发送字符，这会弄乱您的标题。

警告：无法修改标头信息 - 已经由...发送的标头 - 无法更新数据库

3 个答案: