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如何将 PHP 会话数据保存到数据库而不是文件系统中?

更新时间：2023-01-22 11:53:06

在几个小时的调试过程中，我发现在大量 Google 搜索中找到的参考文章以及 Stack Overflow 答案的重要子集，例如 此处、此处和此处均提供无效或过时的信息.

可能导致将会话数据保存到数据库时出现[严重] 问题的事情:

  • 虽然所有在线示例都声明您可以填充"session_set_save_handler，但没有一个声明您还必须设置register_shutdown_function('session_write_close') 也是(参考).

  • 一些(较旧的)指南引用了过时的 SQL 数据库结构，不应该使用.将会话数据保存到数据库所需的数据库结构是:id/access/data.而已.不需要像我在一些指南"和示例中看到的那样使用各种额外的时间戳列.

    • 一些较旧的指南也有过时的 MySQL 语法，例如 DELETE * FROM ...

  • [在我的问题中提出的] 类必须实施 SessionHandlerInterface .我已经看到指南(上面引用的)给出了 sessionHandler 的实现，这不是一个合适的接口.也许以前版本的 PHP 有一个稍微不同的方法(可能

  • 会话类方法必须返回 PHP 手册中规定的值.同样，可能继承自 5.4 之前的 PHP，但我阅读的两个指南指出 class->open 返回要读取的行，而 PHP手册声明需要返回true或false 仅.

  • 这是我的原始问题的原因:我使用的是自定义会话名称(实际上 id 作为会话名称和会话 id 是同一回事！)根据 这篇非常好的 *** 帖子，这生成了一个会话名称128 个字符长.由于会话名称是破解会话并使用 进行破解所需的唯一密钥会话劫持 那么更长的名称/ID 是一件非常好的事情.

    • 但是，这导致了一个问题，因为MySQL 正在悄悄地将会话 ID 切成 32 个字符而不是 128 个字符，因此它永远无法找到会话数据在数据库中.这是一个完全无声的问题(可能是由于我的数据库连接类没有抛出此类警告).但这是需要注意的.如果您在从数据库中检索会话时遇到任何问题，请首先检查 完整 会话 ID 是否可以存储在提供的字段中.

除此之外，还有一些额外的细节需要添加:

PHP 手册页(上面链接)显示了一堆不适合类对象的行:

$handler = new MySessionHandler();session_set_save_handler($handler, true);session_start();

如果你把它放在类构造函数中它也能正常工作:

class MySessionHandler 实现 SessionHandlerInterface {私人 $database = null;公共函数 __construct(){$this->database = new Database(whatever);//设置处理程序以覆盖 SESSIONsession_set_save_handler(数组($this，打开")，数组($this，关闭")，数组($this，读")，数组($this，写")，数组($this，销毁")，数组($this，gc"));register_shutdown_function('session_write_close');session_start();}...}

这意味着要在输出页面上启动会话，您只需要:

供参考，完整的 Session 通信类如下，这适用于 PHP 5.6(可能是 7，但尚未在 7 上测试)

database = new DatabaseObject($sessionDBconnectionUrl);//设置处理程序以覆盖 SESSIONsession_set_save_handler(数组($this，打开")，数组($this，关闭")，数组($this，读")，数组($this，写")，数组($this，销毁")，数组($this，gc"));register_shutdown_function('session_write_close');session_start();}/*** 打开*/公共函数 open($savepath, $id){//如果成功$this->database->getSelect("SELECT `data` FROM session WHERE id = ?LIMIT 1",$id,TRUE);if($this->database->selectRowsFoundCounter() == 1){//返回真返回真；}//返回假返回假；}/*** 读*/公共函数读取($ id){//设置查询$readRow = $this->database->getSelect('SELECT `data` FROM session WHERE id = ?LIMIT 1', $id,TRUE);if ($this->database->selectRowsFoundCounter() > 0) {返回 $readRow['data'];} 别的 {返回 '​​';}}/*** 写*/公共函数写($id，$data){//创建时间戳$访问=时间()；//设置查询$dataReplace[0] = $id;$dataReplace[1] = $access;$dataReplace[2] = $data;if ($this->database->noReturnQuery('REPLACE INTO session(id,access,`data`) VALUES (?, ?, ?)', $dataReplace)) {返回真；} 别的 {返回假；}}/*** 破坏*/公共函数销毁($ id){//设置查询if ($this->database->noReturnQuery('DELETE FROM session WHERE id = ?LIMIT 1', $id)) {返回真；} 别的 {返回假；}}/*** 关闭*/公共函数关闭(){//关闭数据库连接if($this->database->dbiLink->close){//返回真返回真；}//返回假返回假；}/*** 垃圾收集*/公共函数 gc($max){//计算什么是旧的$old = time() - $max;if ($this->database->noReturnQuery('DELETE FROM session WHERE access ', $old)) {返回真；} 别的 {返回假；}}公共函数 __destruct(){$this->close();}}

用法:如类代码文本正上方所示.

I have two websites, One is TLS and one is not, both are for the same client but I need the websites to share with each other (and only each other) common data for users, orders, accounts etc.

This would normally be done with $_SESSION data but I obviously these can't work across other sites, and I have found that I can store session data in a database (MySQL) rather than in the file system.

I have dug around and found This useful guide as well as this older but useful guide. I also found this guide which has slightly more up to date MySQL.

I have written an interface class but it only partly works, it stores the session data in the database, but it doesn't retrieve it. I have also used the suggested method from the PHP manual.

My MySQL (as copied from first couple of the above links):

CREATE TABLE `sessions` (
  `id` varchar(32) COLLATE utf8_unicode_ci NOT NULL,
  `access` int(10) NOT NULL,
  `data` text COLLATE utf8_unicode_ci NOT NULL,
  UNIQUE KEY `id` (`id`)
) ENGINE=InnoDb DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

Please Note: Before I show you my interface class please know that the Db connetion uses my own custom made interface and that works perfectly, in itself.

The $sessionDBconnectionUrl contains the Session Database connection details as I am keeping sessions on a seperate Database from the main website contents.

My interface class (as based on all the above links)

<?php
/***
 * Created by PhpStorm.
 ***/
class HafSessionHandler implements SessionHandler {
    private $database = null;
    
    public function __construct($sessionDBconnectionUrl){

        if(!empty($sessionDBconnectionUrl) && file_exists($_SERVER['DOCUMENT_ROOT'].$sessionDBconnectionUrl)) {
            require_once "class.dataBase.php";
            // Instantiate new Database object
            $this->database = new Database($sessionDBconnectionUrl);
        }
        else {
            error_log("Session could not initialise class.");
        }
        
    }

    /**
     * Open
     */
    public function open($savepath, $id){
         $openRow = $this->database->getSelect("SELECT `data` FROM sessions WHERE id = ? LIMIT 1",$id);
    if($this->database->selectRowsFoundCounter() == 1){
        // Return True
        return $openRow['data'];
        }
    else {
        // Return False
        return ' ';
    }
    /**
     * Read
     */
    public function read($id)
    {
        // Set query
        $readRow = $this->database->getSelect('SELECT `data` FROM sessions WHERE id = ? LIMIT 1', $id,TRUE);
        if ($this->database->selectRowsFoundCounter() > 0) {
            return $readRow['data'];
        } else {
            error_log("could not read session id ".$id);
            return '';
        }
    }

    /**
     * Write
     */
    public function write($id, $data)
    {
        $access = time();
        // Set query
        $dataReplace[0] = $id;
        $dataReplace[1] = $access;
        $dataReplace[2] = $data;
        if ($this->database->noReturnQuery('REPLACE INTO sessions(id,access,`data`) VALUES (?, ?, ?)', $dataReplace)) {
            return TRUE;
        } else {
            return FALSE;
        }
    }

    /**
     * Destroy
     */
    public function destroy($id)
    {
        // Set query
        if ($this->database->noReturnQuery('DELETE * FROM sessions WHERE id = ? ', $id)) {
            return TRUE;
        } else {

            return FALSE;
        }
    }
    /**
     * Close
     */
    public function close(){
        // Close the database connection
        // If successful
        if($this->database->dbiLink->close){
            // Return True
            return true;
        }
        // Return False
        return false;
    }

    /**
     * Garbage Collection
     */
    public function gc($max)
    {
        // Calculate what is to be deemed old
        $old = time() - $max;

        // Set query
        if ($this->database->noReturnQuery('DELETE * FROM sessions WHERE access < ?', $old)) {
            return TRUE;
        } else {
            return FALSE;
        }
    }
    
    public function __destruct()
    {
        $this->close();
    }

}

My Test Page (written from scratch!)

<?php
require "class.sessionHandler.inc.php";
$HSH = new HafSessionHandler("connection.session.dbxlink.php");
session_set_save_handler( $HSH, TRUE );
session_start();

print "<p>Hello this is an index page</p>";
$_SESSION['horses'] = "treesx3";
$_SESSION['tiespan'] = (int)$_SESSION['tiespan']+7;

print "<p>There should be some session data in the database now. <a href='index3.php'>link</a></p>";
var_dump($_SESSION);


exit;

Issue:

The test pages I run save the data to the database ok but they do not seem to retrieve the data,

I have error logging enabled and no PHP errors are reported. No critical MySQL errors are reported.

Why doesn't it work?

I have found over the course of several hours debugging that the referenced articles found on numerous Google searches as well as a significant subset of Stack Overflow answers such as here, here and here all provide invalid or outdated information.

Things that can cause [critical] issues with saving session data to a database:

  • While all the examples online state that you can "fill" the session_set_save_handler, none of them state that you must also set the register_shutdown_function('session_write_close') too (reference).

  • Several (older) guides refer to an outdated SQL Database structure, and should not be used. The database structure that you need for saving session data to the database is: id/access/data. That's it. no need for various extra timestamp columns as I've seen on a few "guides" and examples.

    • Several of the older guides also have outdated MySQL syntax such as DELETE * FROM ...

  • The class [made in my question] must implement the SessionHandlerInterface . I have seen guides (referenced above) that give the implementation of sessionHandler which is not a suitable interface. Perhaps previous versions of PHP had a slightly different method (probably <5.4).

  • The session class methods must return the values set out by the PHP manual. Again, probably inherited from pre-5.4 PHP but two guides I read stated that class->open returns the row to be read, whereas the PHP manual states that it needs to return true or false only.

  • This is the cause of my Original Issue: I was using custom session names (actually id's as session names and session id's are the same thing!) as per this very good *** post and this was generating a session name that was 128 characters long. As the session name is the sole key that is needed to be cracked to compromise a session and take over with a session hijacking then a longer name/id is a very good thing.

    • But, this caused an issue because MySQL was silently slicing the session id down to just 32 characters instead of 128, so it was never able to find the session data in the database. This was a completely silent issue (maybe due to my database connection class not throwing warnings of such things). But this is the one to watch out for. If you have any issues with retrieving sessions from a database first check is that the full session id can be stored in the field provided.

So with all that out of the way there are some extra details to add as well:

The PHP manual page (linked above) shows an unsuitable pile of lines for a class object:

$handler = new MySessionHandler();
session_set_save_handler($handler, true);
session_start();

Whereas it works just as well if you put this in the class constructor:

class MySessionHandler implements SessionHandlerInterface {

    private $database = null;

public function __construct(){

    $this->database = new Database(whatever);

    // Set handler to overide SESSION
    session_set_save_handler(
        array($this, "open"),
        array($this, "close"),
        array($this, "read"),
        array($this, "write"),
        array($this, "destroy"),
        array($this, "gc")
        );
    register_shutdown_function('session_write_close');
    session_start();
    }
...
}

This means that to then start a session on your output page all you need is:

<?php
require "path/to/sessionhandler.class.php"; 
new MySessionHandler();

//Bang session has been setup and started and works

For reference the complete Session communication class is as follows, this works with PHP 5.6 (and probably 7 but not tested on 7 yet)

<?php
/***
 * Created by PhpStorm.
 ***/
class MySessionHandler implements SessionHandlerInterface {
    private $database = null;

    public function __construct($sessionDBconnectionUrl){
        /***
         * Just setting up my own database connection. Use yours as you need.
         ***/ 

            require_once "class.database.include.php";
            $this->database = new DatabaseObject($sessionDBconnectionUrl);

        // Set handler to overide SESSION
        session_set_save_handler(
            array($this, "open"),
            array($this, "close"),
            array($this, "read"),
            array($this, "write"),
            array($this, "destroy"),
            array($this, "gc")
        );
        register_shutdown_function('session_write_close');
        session_start();
    }

    /**
     * Open
     */
    public function open($savepath, $id){
        // If successful
        $this->database->getSelect("SELECT `data` FROM sessions WHERE id = ? LIMIT 1",$id,TRUE);
        if($this->database->selectRowsFoundCounter() == 1){
            // Return True
            return true;
        }
        // Return False
        return false;
    }
    /**
     * Read
     */
    public function read($id)
    {
        // Set query
        $readRow = $this->database->getSelect('SELECT `data` FROM sessions WHERE id = ? LIMIT 1', $id,TRUE);
        if ($this->database->selectRowsFoundCounter() > 0) {
            return $readRow['data'];
        } else {
            return '';
        }
    }

    /**
     * Write
     */
    public function write($id, $data)
    {
        // Create time stamp
        $access = time();

        // Set query
        $dataReplace[0] = $id;
        $dataReplace[1] = $access;
        $dataReplace[2] = $data;
        if ($this->database->noReturnQuery('REPLACE INTO sessions(id,access,`data`) VALUES (?, ?, ?)', $dataReplace)) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Destroy
     */
    public function destroy($id)
    {
        // Set query
        if ($this->database->noReturnQuery('DELETE FROM sessions WHERE id = ? LIMIT 1', $id)) {
            return true;
        } else {

            return false;
        }
    }
    /**
     * Close
     */
    public function close(){
        // Close the database connection
        if($this->database->dbiLink->close){
            // Return True
            return true;
        }
        // Return False
        return false;
    }

    /**
     * Garbage Collection
     */
    public function gc($max)
    {
        // Calculate what is to be deemed old
        $old = time() - $max;

        if ($this->database->noReturnQuery('DELETE FROM sessions WHERE access < ?', $old)) {
            return true;
        } else {
            return false;
        }
    }

    public function __destruct()
    {
        $this->close();
    }

}

Usage: As shown just above the class code text.

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