这种 CSRF 保护是如何工作的？
以下是取自 Facebook 身份验证页面的示例。将数据添加到会话然后使用 JavaScript 重定向到 URL 背后的想法是什么？另外为什么要对 uniqid 进行 md5 哈希？
<?php
$app_id = "YOUR_APP_ID";
$app_secret = "YOUR_APP_SECRET";
$my_url = "YOUR_URL";
session_start();
$code = $_REQUEST["code"];
if(empty($code)) {
$_SESSION['state'] = md5(uniqid(rand(), TRUE)); //CSRF protection
$dialog_url = "http://www.facebook.com/dialog/oauth?client_id="
. $app_id . "&redirect_uri=" . urlencode($my_url) . "&state="
. $_SESSION['state'];
echo("<script> top.location.href='" . $dialog_url . "'</script>");
}
if($_REQUEST['state'] == $_SESSION['state']) {
$token_url = "https://graph.facebook.com/oauth/access_token?"
. "client_id=" . $app_id . "&redirect_uri=" . urlencode($my_url)
. "&client_secret=" . $app_secret . "&code=" . $code;
$response = file_get_contents($token_url);
$params = null;
parse_str($response, $params);
$graph_url = "https://graph.facebook.com/me?access_token="
. $params['access_token'];
$user = json_decode(file_get_contents($graph_url));
echo("Hello " . $user->name);
}
else {
echo("The state does not match. You may be a victim of CSRF.");
}
?>
The following is an example taken from Facebook's authentication page. What is the idea behind adding data to the session and then redirecting to a URL using javascript? Also why do an md5 hash of a uniqid?
<?php
$app_id = "YOUR_APP_ID";
$app_secret = "YOUR_APP_SECRET";
$my_url = "YOUR_URL";
session_start();
$code = $_REQUEST["code"];
if(empty($code)) {
$_SESSION['state'] = md5(uniqid(rand(), TRUE)); //CSRF protection
$dialog_url = "http://www.facebook.com/dialog/oauth?client_id="
. $app_id . "&redirect_uri=" . urlencode($my_url) . "&state="
. $_SESSION['state'];
echo("<script> top.location.href='" . $dialog_url . "'</script>");
}
if($_REQUEST['state'] == $_SESSION['state']) {
$token_url = "https://graph.facebook.com/oauth/access_token?"
. "client_id=" . $app_id . "&redirect_uri=" . urlencode($my_url)
. "&client_secret=" . $app_secret . "&code=" . $code;
$response = file_get_contents($token_url);
$params = null;
parse_str($response, $params);
$graph_url = "https://graph.facebook.com/me?access_token="
. $params['access_token'];
$user = json_decode(file_get_contents($graph_url));
echo("Hello " . $user->name);
}
else {
echo("The state does not match. You may be a victim of CSRF.");
}
?>
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我知道这可能会被安排，因为它是维基百科链接，但您可以在这里找到 csrf 的完整解释 http://en.wikipedia.org/wiki/Cross-site_request_forgery，一旦您完全理解它是什么，您就会明白每个用户拥有唯一的令牌如何可以防止 它。预防部分列出了使用每用户令牌作为预防方法。
I know this will probably get slated as it is a wikipedia link, but you can find a full explanation of csrf here http://en.wikipedia.org/wiki/Cross-site_request_forgery, once you fully understand what it is you will understand how having a unique token per user can protect against it. The prevention section lists using a per-user token as a method of prevention.
它确保您仅在响应站点发起的操作时被重定向到此处。请阅读 https://www.owasp.org/index 来了解 CSRF。 php/Cross-Site_Request_Forgery_%28CSRF%29。
It ensures that you are being redirected here only in response to an action initiated by the site. Read up on CSRF at https://www.owasp.org/index.php/Cross-Site_Request_Forgery_%28CSRF%29.
通过生成一个难以（不可能）猜测的值并将其存储在会话中以及通过请求发送它，该脚本可以验证它是否是由其自身而不是其他地方调用的。在其他地方，难以猜测的价值将是未知的，因此无法提供。
By generating a hard (impossible) to guess value ans storing it in a session as well as sending it with a request, this script can verify if it was called by itself instead of somewhere else. somewhere else the hard to guess value would be unknwon and could thus not be supplied.