I wrote the current top voted comment on this and wanted to add something. The existing code from my previous comment generates it's nonces in an insecure way-
<?php
$_SESSION['nonce'] = md5(microtime(true));
?>
Since "microtime" is predictable it makes brute forcing the nonce much easier. A better option would be something that utilizes randomness, such as-
<?php
bin2hex(openssl_random_pseudo_bytes(32))
?>
PHP - Manual: session_regenerate_id
2024-11-14
session_regenerate_id
(PHP 4 >= 4.3.2, PHP 5, PHP 7, PHP 8)
session_regenerate_id — 使用新生成的会话 ID 更新现有会话 ID
说明
session_regenerate_id(bool
$delete_old_session = false): boolsession_regenerate_id() 在不修改当前会话中数据的前提下使用新的 ID 替换原有会话 ID。
如果启用了 session.use_trans_sid 选项， 那么必须在调用 session_regenerate_id() 函数之后开始进行输出工作， 否则会导致使用原有的会话 ID。
警告
当前的 session_regenerate_id 并没有很好的处理在诸如移动数据网络和 WiFi 网络不稳定的场景。 因此，调用 session_regenerate_id 函数 可能会导致会话丢失。
你不应该直接销毁旧的会话所关联的数据， 而是应该使用时间戳机制来控制对于已经失效的会话 ID 的访问。 否则，可能会在并发访问的场景下导致会话数据不一致、 会话丢失等情况，甚至可能引发客户端（浏览器）创建很多无用的会话 ID。 但是，另外一方面来讲，立即删除会话中的数据 可以防止会话劫持攻击。
参数
-
delete_old_session -
是否删除原 ID 所关联的会话存储文件。 如果你需要避免会话并发访问冲突，那么不应该立即删除会话中的数据。 如果你需要防止会话劫持攻击，那么可以立即删除会话数据。
返回值
成功时返回 true， 或者在失败时返回 false。
范例
示例 #1 A session_regenerate_id() 示例
<?php
// 注意：下列不是完整的代码，只是一个示例
session_start();
// 检查会话被销毁的时间戳
if (isset($_SESSION['destroyed'])
&& $_SESSION['destroyed'] < time() - 300) {
// 通常不会发生这种情况。如果发生，那么可能是由于不稳定的网络状况或者被攻击导致的
// 移除用户会话中的认证信息
remove_all_authentication_flag_from_active_sessions($_SESSION['userid']);
throw(new DestroyedSessionAccessException);
}
$old_sessionid = session_id();
// 设置会话销毁时间戳
$_SESSION['destroyed'] = time(); // 从 PHP 7.0.0 开始, session_regenerate_id() 会自动保存会话数据
// 如果直接调用 session_regenerate_id() 函数可能会导致会话丢失的情况，
// 参见下面的例程
session_regenerate_id();
// 新创建的会话不需要时间戳
unset($_SESSION['destroyed']);
$new_sessionid = session_id();
echo "Old Session: $old_sessionid<br />";
echo "New Session: $new_sessionid<br />";
print_r($_SESSION);
?>
当前的会话模块未能很好的处理在网络不稳定的时候导致会话丢失的场景。 你需要自行管理会话 ID 避免调用 session_regenerate_id 导致会话丢失。
示例 #2 Avoiding lost session by session_regenerate_id()
<?php
// 注意：下列不是完整的代码，只是一个示例
// my_session_start() 和 my_session_regenerate_id()
// 函数可以避免在网络不稳定的情况下导致会话丢失的问题。
// 并且还可以避免用户会话被攻击者利用
function my_session_start() {
session_start();
if (isset($_SESSION['destroyed'])) {
if ($_SESSION['destroyed'] < time()-300) {
// 通常不会发生这种情况。如果发生，那么可能是由于不稳定的网络状况或者被攻击导致的
// 移除用户会话中的认证信息
remove_all_authentication_flag_from_active_sessions($_SESSION['userid']);
throw(new DestroyedSessionAccessException);
}
if (isset($_SESSION['new_session_id'])) {
// 尚未完全过期，可能是由于网络不稳定引起的。
// 尝试再次设置正确的会话 ID cookie。
// 注意：如果你需要移除认证标记，那么不要尝试再次设置会话 ID。
session_commit();
session_id($_SESSION['new_session_id']);
// 现在有了新的会话 ID 了。
session_start();
return;
}
}
}
function my_session_regenerate_id() {
// 如果由于不稳定的网络导致没有创建会话 ID，
// 那么就创建一个
$new_session_id = session_create_id();
$_SESSION['new_session_id'] = $new_session_id;
// 设置销毁时间戳
$_SESSION['destroyed'] = time();
// 保存并关闭会话
session_commit();
// 使用新的会话 ID 开始会话
session_id($new_session_id);
ini_set('session.use_strict_mode', 0);
session_start();
ini_set('session.use_strict_mode', 1);
// 新的会话不需要这 2 个数据了
unset($_SESSION['destroyed']);
unset($_SESSION['new_session_id']);
}
?>
参见
- session_id() - 获取/设置当前会话 ID
- session_create_id() - Create new session id
- session_start() - 启动新会话或者重用现有会话
- session_destroy() - 销毁一个会话中的全部数据
- session_reset() - Re-initialize session array with original values
- session_name() - 读取/设置会话名称
add a note
User Contributed Notes 25 notes
tedivm at tedivm dot com ¶
6 years ago
tedivm at tedivm dot com ¶
13 years ago
I wrote the following code for a project I'm working on- it attempts to resolve the regenerate issue, as well as deal with a couple of other session related things.
I tried to make it a little more generic and usable (for instance, in the full version it throws different types of exceptions for the different types of session issues), so hopefully someone might find it useful.
<?php
function regenerateSession($reload = false)
{
// This token is used by forms to prevent cross site forgery attempts
if(!isset($_SESSION['nonce']) || $reload)
$_SESSION['nonce'] = md5(microtime(true));
if(!isset($_SESSION['IPaddress']) || $reload)
$_SESSION['IPaddress'] = $_SERVER['REMOTE_ADDR'];
if(!isset($_SESSION['userAgent']) || $reload)
$_SESSION['userAgent'] = $_SERVER['HTTP_USER_AGENT'];
//$_SESSION['user_id'] = $this->user->getId();
// Set current session to expire in 1 minute
$_SESSION['OBSOLETE'] = true;
$_SESSION['EXPIRES'] = time() + 60;
// Create new session without destroying the old one
session_regenerate_id(false);
// Grab current session ID and close both sessions to allow other scripts to use them
$newSession = session_id();
session_write_close();
// Set session ID to the new one, and start it back up again
session_id($newSession);
session_start();
// Don't want this one to expire
unset($_SESSION['OBSOLETE']);
unset($_SESSION['EXPIRES']);
}
function checkSession()
{
try{
if($_SESSION['OBSOLETE'] && ($_SESSION['EXPIRES'] < time()))
throw new Exception('Attempt to use expired session.');
if(!is_numeric($_SESSION['user_id']))
throw new Exception('No session started.');
if($_SESSION['IPaddress'] != $_SERVER['REMOTE_ADDR'])
throw new Exception('IP Address mixmatch (possible session hijacking attempt).');
if($_SESSION['userAgent'] != $_SERVER['HTTP_USER_AGENT'])
throw new Exception('Useragent mixmatch (possible session hijacking attempt).');
if(!$this->loadUser($_SESSION['user_id']))
throw new Exception('Attempted to log in user that does not exist with ID: ' . $_SESSION['user_id']);
if(!$_SESSION['OBSOLETE'] && mt_rand(1, 100) == 1)
{
$this->regenerateSession();
}
return true;
}catch(Exception $e){
return false;
}
}
?>
ei dot rik dot ops dot tad at gmail dot com ¶
6 years ago
In PHP 5.6 (and probably older versions), session_regenerate_id(true) do not trigger a read() call to the session handler for the new session id.
In PHP 7, read() is triggered during session_regenerate_id(true). Nice to know when working with custom session handlers.
ross at kndr dot org ¶
17 years ago
In a previous note, php at 5mm de describes how to prevent session hijacking by
ensuring that the session id provided matches the HTTP_USER_AGENT and REMOTE_ADDR fields that were present when the session id was first issued. It should be noted that HTTP_USER_AGENT is supplied by the client, and so can be easily modified by a malicious user. Also, the client IP addresses can be spoofed, although that's a bit more difficult. Care should be taken when relying on the session for authentication.
gr at gr5 dot org ¶
10 years ago
If you are trying to maintain 2 active sessions don't use session_regenerate_id(). Especially if the first session is closed and it's time to open the second. Because the session id is cached you also have to explicitly set it the second time.
<?php
session_name('PHPSESSID'); // redundant - here for clarity
session_start();
// ...do stuff
session_write_close();
// now switch to session 2...
session_name('PHPSESSID_2');
if (isset($_COOKIE['phpsessid_2']))
session_id($_COOKIE['phpsessid_2']); // not doing this will simply reopen the first session again
else
session_id(sha1(mt_rand()); // dont use session_regenerate_id() here. Not creating a new id will create two cookies with same session id and same session variables
session_start();
// ... do stuff with session 2
session_write_close();
?>
babel at nosqamplease sympatico ca ¶
18 years ago
To add to php at 5mm de's comments:
If the session is held over https, it's even better to save the client's cert or ssl session id instead of the hostname or ip, as it's proxy-transparent and more secure.
spmtrap at yahoo dot com ¶
10 years ago
`session_regenerate_id` sends a new cookie but doesn't overwrite the value stored in `$_COOKIE`. After calling `session_destroy`, the open session ID is discarded, so simply restarting the session with `session_start` (as done in Ben Johnson's code) will re-open the original, though now empty, session for the current request (subsequent requests will use the new session ID). Instead of `session_destroy`+`session_start`, use the `$delete_old_session` parameter to `session_regenerate_id` to delete the previous session data.
<?php
session_start();
/* Create a new session, deleting the previous session data. */
session_regenerate_id(TRUE);
/* erase data carried over from previous session */
$_SESSION=array();
?>
To start a new session and leave the old untouched, simply leave out the argument to `session_regenerate_id`.
php at cny dot de ¶
17 years ago
Also note that REMOTE_ADDR may change on every request if the user comes through a proxy farm. Most AOL-users do.
k-gun !! mail ¶
5 years ago
Document example is wrong with usage of "session.use_strict_mode" according to RFC (says: "warning error for session_id() when use_strice_mode=1" on https://wiki.php.net/rfc/strict_sessions).
So, this directive affects "session_id()" not "session_start()". So usage must be like this;
<?php
// first set ini
ini_set('session.use_strict_mode', '0');
// and
session_id($sid);
// then
// maybe run this: ini_restore('session.use_strict_mode');
// then go on...
?>
Refs (ctrl+f & use_strict_mode);
https://wiki.php.net/rfc/strict_sessions
https://wiki.php.net/rfc/session-create-id
http://php.net/manual/en/function.session-id.php#119997
madsen at sjovedyr.dk ¶
18 years ago
I had problems with a proxy changing a visitors session_id-cookie, so he'd get a LOT of errors when visiting my site.
I handled the bogus session-id's like this. (Note: It only works in versions > 4.3.2.)
<?php
// Start a session and suppress error-messages.
@session_start();
// Catch bogus session-id's.
if (!preg_match("/^[0-9a-z]*$/i", session_id())) {
// Output a warning about the messed up session-id.
$error->handleError("WARN", "Your session id is messed up, you might not be able to use some features on this site.");
// Generate a fresh session-id.
session_regenerate_id();
}
// Site contents.
?>
Hope someone can use it.
antomsa at hotmail dot it ¶
9 months ago
<?php
function my_session_regenerate_id() {
...
session_start();
...
unset($_SESSION['destroyed']);
unset($_SESSION['new_session_id']);
}
?>
Within my_session_regenerate_id(), unset($_SESSION['destroyed']) and
unset($_SESSION['new_session_id']) are useless because session_start() will open an empty session. They would be needed if built-in session_regenerate_id() was called.
soapergem at gmail dot com ¶
13 years ago
This can be a very dangerous function if you're not careful about how you handle things, because even though it generates a whole new set of session data, it keeps the old data "open" until the script terminates, locking out any other scripts trying to run concurrently with the old session id.
Recently I came across a situation where I wanted to explicitly pass in a session ID, copy the data from that session into a *new* session, and then continue operating under that new session, thereby allowing other scripts to use the old one concurrently. But I quickly found that these "other scripts" would not execute until the first script finished--even though it had already started a new session--because it kept the old session open.
So if you're trying to copy over session data to a new session to free up the old session for continued, concurrent use, here's some code to ensure nobody's feet get stepped on:
<?php
// get session id of an existing session
$sid = $_GET['sid'];
// start the old session to retrieve $_SESSION data
session_id($sid);
session_start();
// start a new session; this copies the $_SESSION data over
session_regenerate_id();
// hang on to the new session id
$sid = session_id();
// close the old and new sessions
session_write_close();
// re-open the new session
session_id($sid);
session_start();
/* main code here */
?>
This could probably be encapsulated into a function with one parameter as well to save space if it was a repeated thing.
Nicolas dot Chachereau at Infomaniak dot ch ¶
17 years ago
Session_destroy() does not only destroy the data associated with the current session_id (i.e. the file if you use the default session save handler), but also the session itself: if you call session_destroy() and then session_regenerate_id(), it will return false, and session_id() won't return anything. In order to manipulate a session after destroying it, you need to restart it.
So in fact, the code mentionned by chris won't work. If you want to destroy the file associated with the old session_id, try the following:
<?php
session_start();
$old_sessid = session_id();
session_regenerate_id();
$new_sessid = session_id();
session_id($old_sessid);
session_destroy();
//If you don't copy the $_SESSION array, you won't be able to use the data associated with the old session id.
$old_session = $_SESSION;
session_id($new_sessid);
session_start();
$_SESSION = $old_session;
//...
?>
Note: this technique will send 3 Set-Cookie headers (one on each session_start() and one on session_regenerate_id()). I don't think this is a problem, but if it appears to be one, you could either leave it alone and wait for the garbage collector to catch the file associated with the old session, or try to delete the file with unlink().
primenetworkzx at gmail dot com ¶
14 years ago
If you are storing your session data in a database you have to manually update the session_id in the database. The session_set_save_handler() will not do it for you.
function UpdateSessID() {
$old_sess_id = session_id();
session_regenerate_id(false);
$new_sess_id = session_id();
$query = "UPDATE `session_table` SET `session_id` = '$new_sess_id' WHERE session_id = '$old_sess_id'";
mysql_query($query);
}
Be sure to set session_regenerate_id() to FALSE since it's not really necessary to delete the whole record from MySQL and add it again. That's unnecessary overhead. Only changing the id matters.
mikebranttx at gmail dot com ¶
5 years ago
Note that in current PHP 7.2 nightly builds example #2 above will not work as shown. You will get following error upon trying to turn strict mode back on after session_start():
"ini_set(): A session is active. You cannot change the session module's ini settings at this time"
I suppose this means that for any session where you perform session ID regeneration or session ID forwarding (from a session for which a recent session ID regeneration was performed to the new session ID). That you will just have to live with strict mode being disabled for the remainder of that active session.
I don't know that this is really a security concern so long as you are following a single-session per request design (i.e. you are not working with multiple concurrent sessions).
dyer85 at gmail dot com ¶
16 years ago
There could be a potential problem with elger at NOSPAM dot yellowbee dot nl's a few posts below. In the code, was used the REQUEST_URI server variable, which, in some cases might already contain the query string. Therefore, always apending '?whatever=foo' would occasionally cause the script to malfunction. I suggest using PHP_SELF, which will not contain the query string after the file.
chris at knowledge dot tee-vee ¶
17 years ago
licp - no, session_regenerate_id() does not destroy any saved session data.
elger, I prefer the following order
[code]
// populate $_SESSION with any previously saved session data for the current session_id
session_start();
...
// delete any saved data associated with current session_id, $_SESSION is not changed
session_destroy();
// change session_id, $_SESSION not altered
session_regenerate_id();
...
// save any $_SESSION data under the current session_id
session_close();
[/code]
kgm_india at yahoo dot co dot in ¶
8 years ago
as far as I have understood reading this online notes,
session_name() is the name which is identified as session a through the cookies or http links.
session_id is like a transaction within a session_name() and one session_name may have many session_id
each session_id has the corresponding data stored.
session_id are used in read and write callback under a session_name
whatever it is, first call the
session_name(),
then call session_id ()
and then call start_session()
start_session will open the session_name, then check the session_id called before and use it in the read or write call back for storing or retrieving data
calling start_session() without session_name or session_id will use the default session_name and the default session_id in that order
I hope if the order is followed there should not be any problems.
do not call session_name or session_id after start_session(), if you are specific on using them.
thank you for others note.
sopel ¶
16 years ago
for php 5.1> user probably worth visiting is http://ilia.ws/archives/47-session_regenerate_id-Improvement.html
raido dot aasoja at gmail dot com ¶
11 years ago
A note on lost sessions and trying to fix it with session_regenerate_id:
Make sure that you're not trying to push SimpleXML object to the session. It just won't go without first converting it to array. :)
elger at NOSPAM dot yellowbee dot nl ¶
17 years ago
Take good notice of the new cookie being sent on calling session_regenerate_id on cookie-enabled sessions.
Make sure your page is reloaded otherwise you'll get an "session_destroy(): Session object destruction failed" error. So here are the examples:
Wrong:
<?php
session_start();
session_regenerate_id();
session_destroy();
?>
Correct-like:
<?php
if (!$_GET['mode']){
session_start();
session_regenerate_id();
header('location: '.$_SERVER['REQUEST_URI'].'?mode=destroy');
} else {
session_start();
session_destroy();
}
?>
I noted this because googleing on the previous mentioned error leads to all kinds of bug reports, but not to the solution. (which is, of course, to read the manual)
Ben Johnson ¶
11 years ago
To "start a new session", try the following:
<?php
session_start();
session_regenerate_id();
session_destroy();
unset($_SESSION);
session_start();
?>
licp at hotmail dot com ¶
17 years ago
By inspecting the source code, I am not sure that after session_regenerate_id() run, the original session data does not destroy (still keeps at the system) that sniffers still hijack by applying original session identifier.
In addition, I find that if user-level session storage handler is used. session_regenerate_id() does not work.
php at 5mm de ¶
18 years ago
This feature seems to create a new session ID without clearing the old session data. This is a very important feature for security validation:
$usedns = TRUE; // for eliminating failture by proxys using IP chains, but slower
$useragent = getenv("HTTP_USER_AGENT");
$host = getenv("REMOTE_ADDR");
$dns = $global['dns'] ? @gethostbyaddr($host):$host;
session_start();
if(session_is_registered('securitycheck')) {
if(
(($_SESSION['session']['host'] != $this->host) && !$usedns)
|| ($_SESSION['session']['dns'] != $this->dns)
|| ($_SESSION['session']['useragent'] != $this->useragent)
) {
session_regenerate_id();
session_unset();
}
} else {
$currentdata = array();
$currentdata['host'] = $this->host;
$currentdata['dns'] = $this->dns;
$currentdata['useragent'] = $this->useragent;
session_register('securitycheck', $currentdata);
}
If sombody steals an active SID (e.g. by referrer or injection attack), he can?t be validated because of either the host / dns or useragent and will get a new (empty) SID, without interrupting the original session.
Please mail me for any comments: php at 5mm de
官方地址：https://www.php.net/manual/en/function.session-regenerate-id.php
IT
PHP
编程语言
Linux
开发编程
科技
Elasticsearch
HTML/CSS/XML
网络
JAVA
NoSQL
数据库
面试
C/C++
Golang
Git
算法
操作系统
正则表达式
Redis
互联网
MySql
JavaScript
运维
软件
国际
架构设计
Mac OS
TCP/IP
Excel
Vim
Windows
Socket
Oracle
VR
MongoDB
Python
运营
MemCache
商业
硬件
电子
娱乐
设计
nginx
摄影
游戏
WordPress
HTTP
团建
数码电器
广告
--
php7 安装fileinfo扩展
preg_split — 通过一个正则表达式分隔字符串
php位值,解决 PHP 中 usort 在值相同时改变原始位置的问题
[PHP] inet_pton/inet_ntop IP地址转换函数
array_multisort() 多字段排序
PHPMailer设置utf8 PHPMailer字符集CharSet
ADORecordSet对象
adodb手册
PHP 8.1
[鸟哥]PHP_INT_MIN 和 -9223372036854775808
opcache预加载
Composer的Packagist资源
mysql面试题
[鸟哥]PHP FFI详解 - 一种全新的PHP扩展方式
PHP7添加redis扩展
PHP mkdir()写出来的权限与mode值不符合
Packagist / Composer 中国全量镜像
常用的php ADODB使用方法集锦
[原创]诡异的php-fpm超时问题
php中几种注释规范