如何验证 HTTP 文件下载？

Question

在我的网站中，我有一个 php 脚本，它启动文件下载而不显示文件的完整路径，代码如下所示：

$path = '../examples/test.zip';
$type = "application/zip";

header("Expires: 0");
header("Pragma: no-cache");
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: pre-check=0, post-check=0, max-age=0');
header("Content-Description: File Transfer");
header("Content-Type: " . $type);
header("Content-Length: " .(string)(filesize($path)) );
header('Content-Disposition: attachment; filename="'.basename($path).'"');
header("Content-Transfer-Encoding: binary\n");

readfile($path); // outputs the content of the file

exit();

有一种方法可以在启动下载之前添加 HTTP 身份验证吗？

提前致谢！

---

编辑1： 感谢 André Hoffmann，我已经通过使用 HTTP 基本身份验证解决了这个问题！ 但是如果我想使用如下所示的 HTTP 摘要身份验证，我该怎么办？ 我尝试在以下行之后编写上面的代码：“echo '您的登录方式为：'。$data['username'];” ...但我收到一条错误消息，说我不能两次修改标题！

<?php

$realm = 'Restricted area';

//user => password
$users = array('admin' => 'mypass', 'guest' => 'guest');


if (empty($_SERVER['PHP_AUTH_DIGEST'])) {
    header('HTTP/1.1 401 Unauthorized');
    header('WWW-Authenticate: Digest realm="'.$realm.
           '",qop="auth",nonce="'.uniqid().'",opaque="'.md5($realm).'"');

    die('Text to send if user hits Cancel button');
}


// analyze the PHP_AUTH_DIGEST variable
if (!($data = http_digest_parse($_SERVER['PHP_AUTH_DIGEST'])) ||
    !isset($users[$data['username']]))
    die('Wrong Credentials!');


// generate the valid response
$A1 = md5($data['username'] . ':' . $realm . ':' . $users[$data['username']]);
$A2 = md5($_SERVER['REQUEST_METHOD'].':'.$data['uri']);
$valid_response = md5($A1.':'.$data['nonce'].':'.$data['nc'].':'.$data['cnonce'].':'.$data['qop'].':'.$A2);

if ($data['response'] != $valid_response){
    die('Wrong Credentials!');
}

// ok, valid username & password
echo 'Your are logged in as: ' . $data['username'];


// function to parse the http auth header
function http_digest_parse($txt)
{
    // protect against missing data
    $needed_parts = array('nonce'=>1, 'nc'=>1, 'cnonce'=>1, 'qop'=>1, 'username'=>1, 'uri'=>1, 'response'=>1);
    $data = array();
    $keys = implode('|', array_keys($needed_parts));

    preg_match_all('@(' . $keys . ')=(?:([\'"])([^\2]+?)\2|([^\s,]+))@', $txt, $matches, PREG_SET_ORDER);

    foreach ($matches as $m) {
        $data[$m[1]] = $m[3] ? $m[3] : $m[4];
        unset($needed_parts[$m[1]]);
    }

    return $needed_parts ? false : $data;
}

?>

---

解决方案：

感谢安德烈和安东尼，我可以编写解决方案：

<?php

$realm = 'Restricted area';

//user => password
$users = array('admin' => 'mypass', 'guest' => 'guest');


if (empty($_SERVER['PHP_AUTH_DIGEST'])) {
    header('HTTP/1.1 401 Unauthorized');
    header('WWW-Authenticate: Digest realm="'.$realm.
           '",qop="auth",nonce="'.uniqid().'",opaque="'.md5($realm).'"');

    die('Text to send if user hits Cancel button');
}


// analyze the PHP_AUTH_DIGEST variable
if (!($data = http_digest_parse($_SERVER['PHP_AUTH_DIGEST'])) ||
    !isset($users[$data['username']]))
    die('Wrong Credentials!');


// generate the valid response
$A1 = md5($data['username'] . ':' . $realm . ':' . $users[$data['username']]);
$A2 = md5($_SERVER['REQUEST_METHOD'].':'.$data['uri']);
$valid_response = md5($A1.':'.$data['nonce'].':'.$data['nc'].':'.$data['cnonce'].':'.$data['qop'].':'.$A2);

if ($data['response'] != $valid_response){
    die('Wrong Credentials!');
}

// ok, valid username & password ... start the download
$path = '../examples/test.zip';
$type = "application/zip";

header("Expires: 0");
header("Pragma: no-cache");
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: pre-check=0, post-check=0, max-age=0');
header("Content-Description: File Transfer");
header("Content-Type: " . $type);
header("Content-Length: " .(string)(filesize($path)) );
header('Content-Disposition: attachment; filename="'.basename($path).'"');
header("Content-Transfer-Encoding: binary\n");

readfile($path); // outputs the content of the file

exit();


// function to parse the http auth header
function http_digest_parse($txt)
{
    // protect against missing data
    $needed_parts = array('nonce'=>1, 'nc'=>1, 'cnonce'=>1, 'qop'=>1, 'username'=>1, 'uri'=>1, 'response'=>1);
    $data = array();
    $keys = implode('|', array_keys($needed_parts));

    preg_match_all('@(' . $keys . ')=(?:([\'"])([^\2]+?)\2|([^\s,]+))@', $txt, $matches, PREG_SET_ORDER);

    foreach ($matches as $m) {
        $data[$m[1]] = $m[3] ? $m[3] : $m[4];
        unset($needed_parts[$m[1]]);
    }

    return $needed_parts ? false : $data;
}

?>

Answer 1

当然，请参阅手册。

<?php
if (!isset($_SERVER['PHP_AUTH_USER'])) {
    header('WWW-Authenticate: Basic realm="My Realm"');
    header('HTTP/1.0 401 Unauthorized');
    echo 'Text to send if user hits Cancel button';
    exit;
} else {
    //check $_SERVER['PHP_AUTH_USER'] and $_SERVER['PHP_AUTH_PW']
    if ($valid) {
        //start download

        $path = '../examples/test.zip';
        $type = "application/zip";

        header("Expires: 0");
        header("Pragma: no-cache");
        header('Cache-Control: no-store, no-cache, must-revalidate');
        header('Cache-Control: pre-check=0, post-check=0, max-age=0');
        header("Content-Description: File Transfer");
        header("Content-Type: " . $type);
        header("Content-Length: " .(string)(filesize($path)) );
        header('Content-Disposition: attachment; filename="'.basename($path).'"');
        header("Content-Transfer-Encoding: binary\n");

        readfile($path); // outputs the content of the file

        exit();
    } else {
        //show error
    }
}

更新：

基于 .htaccess 的身份验证实际上允许多个用户使用。
将其放入您的 .htaccess 中：

AuthType Basic
AuthName "Password Required"
AuthUserFile passwords.file
AuthGroupFile groups.file

可以使用 apache 附带的 htpasswd 工具创建包含密码的文件 passwords.file。
文件 groups.file 应该与此类似：

GroupName: rbowen dpitts sungo rshersey

在这里，您基本上只列出应该有权访问该目录的用户。

另请参阅此教程。

Answer 2

您是否在脚本回显“您已成功登录为...”后尝试启动下载？

将任何内容输出到屏幕后，您无法设置任何标题。一旦您回显或打印或其他什么，您就开始了 HTTP 响应的正文部分，这意味着标头已设置。

顺便说一句，如果您尝试设置标题，然后给出“您已登录”位，则会卡在文件中，而不是输出到屏幕。

您想要做的是让脚本输出“您已登录”并重定向到发送下载标头的脚本。用户将看不到第二页，因为标题设置为“附件”。这就是典型的“您的下载将立即开始”页面的工作方式。