Spring Security实现禁止用户重复登陆（配置及原理）

系统使用了Spring Security做权限管理，现在对于系统的用户，需要改动配置，实现无法多地登陆。

 

一、SpringMVC项目，配置如下：

首先在修改Security相关的XML，我这里是spring-security.xml，修改UsernamePasswordAuthenticationFilter相关Bean的构造配置

加入

<property name="sessionAuthenticationStrategy" ref="sas" />

新增sas的Bean及其相关配置

<bean id="sas" class="org.springframework.security.web.authentication.session.CompositeSessionAuthenticationStrategy">
        <constructor-arg>
            <list>
                <bean class="org.springframework.security.web.authentication.session.ConcurrentSessionControlAuthenticationStrategy">
                    <constructor-arg ref="sessionRegistry"/>
                    <!-- 这里是配置session数量，此处为1，表示同一个用户同时只会有一个session在线 --> 
                    <property name="maximumSessions" value="1" />
                    <property name="exceptionIfMaximumExceeded" value="false" />
                </bean>
                <bean class="org.springframework.security.web.authentication.session.SessionFixationProtectionStrategy">
                </bean>
                <bean class="org.springframework.security.web.authentication.session.RegisterSessionAuthenticationStrategy">
                    <constructor-arg ref="sessionRegistry"/>
                </bean>
            </list>
        </constructor-arg>
    </bean>

    <bean id="sessionRegistry"
                class="org.springframework.security.core.session.SessionRegistryImpl" />

加入ConcurrentSessionFilter相关Bean配置

<bean id="concurrencyFilter"
                class="org.springframework.security.web.session.ConcurrentSessionFilter">
        <constructor-arg name="sessionRegistry" ref="sessionRegistry" />
        <constructor-arg name="sessionInformationExpiredStrategy" ref="redirectSessionInformationExpiredStrategy" />
    </bean>


    <bean id="redirectSessionInformationExpiredStrategy"
                class="org.springframework.security.web.session.SimpleRedirectSessionInformationExpiredStrategy">
        <constructor-arg name="invalidSessionUrl" value="/login.html" />
    </bean>

二、SpringBoot项目，配置如下：

待补充。。。。。

 

三、Bean配置说明

SessionAuthenticationStrategy：该接口中存在onAuthentication方法用于对新登录用户进行session相关的校验。

查看UsernamePasswordAuthenticationFilter及其父类代码，可以发现在doFilter中存在sessionStrategy.onAuthentication(authResult, request, response);方法

但UsernamePasswordAuthenticationFilter中的sessionStrategy对象默认为NullAuthenticatedSessionStrategy，即不对session进行相关验证。

如本文配置，建立id为sas的CompositeSessionAuthenticationStrategy的Bean对象。

CompositeSessionAuthenticationStrategy可以理解为一个托管类，托管所有实现SessionAuthenticationStrategy接口的对象，用来批量托管执行onAuthentication函数

这里CompositeSessionAuthenticationStrategy中注入了三个对象，关注ConcurrentSessionControlAuthenticationStrategy，它实现了对于session并发的控制

UsernamePasswordAuthenticationFilter的Bean中注入新配置的sas，用于替换原本的NullAuthenticatedSessionStrategy
ConcurrentSessionFilter的Bean用来验证session是否失效，并通过SimpleRedirectSessionInformationExpiredStrategy将失败访问进行跳转。

四、代码流程说明（这里模拟用户现在A处登录，随后用户在B处登录，之后A处再进行操作时会返回失败，提示重新登录）

1、用户在A处登录，UsernamePasswordAuthenticationFilter调用sessionStrategy.onAuthentication进行session验证

2、ConcurrentSessionControlAuthenticationStrategy中的onAuthentication开始进行session验证，服务器中保存了登录后的session

/**
     * In addition to the steps from the superclass, the sessionRegistry will be updated
     * with the new session information.
     */
    public void onAuthentication(Authentication authentication,
            HttpServletRequest request, HttpServletResponse response) {

        //根据所登录的用户信息，查询相对应的现存session列表
        final List<SessionInformation> sessions = sessionRegistry.getAllSessions(
                authentication.getPrincipal(), false);

        int sessionCount = sessions.size();
        //获取session并发数量，对于XML中的maximumSessions
        int allowedSessions = getMaximumSessionsForThisUser(authentication);

        //判断现有session列表数量和并发控制数间的关系
        //如果是首次登录，根据xml配置，这里应该是0<1，程序将会继续向下执行，
        //最终执行到SessionRegistryImpl的registerNewSession进行新session的保存
        if (sessionCount < allowedSessions) {
            // They haven't got too many login sessions running at present
            return;
        }

        if (allowedSessions == -1) {
            // We permit unlimited logins
            return;
        }

        if (sessionCount == allowedSessions) {
            //获取本次http请求的session
            HttpSession session = request.getSession(false);

            if (session != null) {
                // Only permit it though if this request is associated with one of the
                // already registered sessions
                for (SessionInformation si : sessions) {
                    //循环已保存的session列表，判断本次http请求session是否已经保存
                    if (si.getSessionId().equals(session.getId())) {
                        //本次http请求是有效请求，返回执行下一个filter
                        return;
                    }
                }
            }
            // If the session is null, a new one will be created by the parent class,
            // exceeding the allowed number
        }

        //本次http请求为新请求，进入具体判断
        allowableSessionsExceeded(sessions, allowedSessions, sessionRegistry);
    }

/**
     * Allows subclasses to customise behaviour when too many sessions are detected.
     *
     * @param sessions either <code>null</code> or all unexpired sessions associated with
     * the principal
     * @param allowableSessions the number of concurrent sessions the user is allowed to
     * have
     * @param registry an instance of the <code>SessionRegistry</code> for subclass use
     *
     */
    protected void allowableSessionsExceeded(List<SessionInformation> sessions,
            int allowableSessions, SessionRegistry registry)
            throws SessionAuthenticationException {
        //根据exceptionIfMaximumExceeded判断是否要将新http请求拒绝
        //exceptionIfMaximumExceeded也可以在XML中配置
        if (exceptionIfMaximumExceeded || (sessions == null)) {
            throw new SessionAuthenticationException(messages.getMessage(
                    "ConcurrentSessionControlAuthenticationStrategy.exceededAllowed",
                    new Object[] { Integer.valueOf(allowableSessions) },
                    "Maximum sessions of {0} for this principal exceeded"));
        }

        // Determine least recently used session, and mark it for invalidation
        SessionInformation leastRecentlyUsed = null;

        //若不拒绝新请求，遍历现存seesion列表
        for (SessionInformation session : sessions) {
            //获取上一次/已存的session信息
            if ((leastRecentlyUsed == null)
                    || session.getLastRequest()
                            .before(leastRecentlyUsed.getLastRequest())) {
                leastRecentlyUsed = session;
            }
        }

        //将上次session信息写为无效（欺骗）
        leastRecentlyUsed.expireNow();
    }

3、用户在B处登录，再次通过ConcurrentSessionControlAuthenticationStrategy的检查，将A处登录的session置于无效状态，并在session列表中添加本次session

4、用户在A处尝试进行其他操作，ConcurrentSessionFilter进行Session相关的验证，发现A处用户已经失效，提示重新登录

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;

    //获取本次http请求的session
        HttpSession session = request.getSession(false);
    
        if (session != null) {
            //从本地session关系表中取出本次http访问的具体session信息
            SessionInformation info = sessionRegistry.getSessionInformation(session
                    .getId());
           //如果存在信息，则继续执行
            if (info != null) {
                //判断session是否已经失效（这一步在本文4.2中被执行）
                if (info.isExpired()) {
                    // Expired - abort processing
                    if (logger.isDebugEnabled()) {
                        logger.debug("Requested session ID "
                                + request.getRequestedSessionId() + " has expired.");
                    }
                    //执行登出操作
                    doLogout(request, response);

                    //从XML配置中的redirectSessionInformationExpiredStrategy获取URL重定向信息，页面跳转到登录页面
                    this.sessionInformationExpiredStrategy.onExpiredSessionDetected(new SessionInformationExpiredEvent(info, request, response));
                    return;
                }
                else {
                    // Non-expired - update last request date/time
                    sessionRegistry.refreshLastRequest(info.getSessionId());
                }
            }
        }

        chain.doFilter(request, response);
    }

5、A处用户只能再次登录，这时B处用户session将会失效重登，如此循环