WEB安全实战--XSS 攻击的解决方案（二）

首先，项目中需要引入 xssProtect-0.1.jar、antlr-3.0.1.jar、antlr-runtime-3.0.1.jar 等3个 jar 包。

然后，封装 request，代码如下。

package com.htsc.pos.web.filter.xss;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
    HttpServletRequest orgRequest = null;  
      
    public XssHttpServletRequestWrapper(HttpServletRequest request) {  
        super(request);  
        orgRequest = request;  
    }  
      
    /** 
    * 覆盖getParameter方法，将参数名和参数值都做xss过滤。<br/> 
    * 如果需要获得原始的值，则通过super.getParameterValues(name)来获取<br/> 
    * getParameterNames,getParameterValues和getParameterMap也可能需要覆盖 
    */  
    @Override  
    public String getParameter(String name) {  
        String value = super.getParameter(xssEncode(name));  
        if (value != null) {  
            value = xssEncode(value);  
        }  
        return value;  
    }  
      
    /** 
    * 覆盖getHeader方法，将参数名和参数值都做xss过滤。<br/> 
    * 如果需要获得原始的值，则通过super.getHeaders(name)来获取<br/> 
    * getHeaderNames 也可能需要覆盖 
    */  
    @Override  
    public String getHeader(String name) {  
        String value = super.getHeader(xssEncode(name));  
        if (value != null) {  
            value = xssEncode(value);  
        }  
        return value;  
    }  
      
    /** 
    * 将容易引起xss漏洞的半角字符直接替换成全角字符 
    * 
    * @param s 
    * @return 
    */  
    private static String xssEncode(String s) {  
        if (s == null || s.isEmpty()) {  
            return s;  
        }  
        StringBuilder sb = new StringBuilder(s.length() + 16);  
        for (int i = 0; i < s.length(); i++) {  
            char c = s.charAt(i);  
            switch (c) {  
                case '>':  
                    sb.append('＞');//全角大于号  
                    break;  
                case '<':  
                    sb.append('＜');//全角小于号  
                    break;  
                case '\'':  
                    sb.append('‘');//全角单引号  
                    break;  
                case '\"':  
                    sb.append('“');//全角双引号  
                    break;  
                case '&':  
                    sb.append('＆');//全角  
                    break;  
                case '\\':  
                    sb.append('＼');//全角斜线  
                    break;  
                case '#':  
                    sb.append('＃');//全角井号  
                    break;
                default:  
                    sb.append(c);  
                break;  
            }
        }  
        return sb.toString();  
    }  
      
    /** 
    * 获取最原始的request 
    * 
    * @return 
    */  
    public HttpServletRequest getOrgRequest() {  
        return orgRequest;  
    }  
    /** 
    * 获取最原始的request的静态方法 
    * 
    * @return 
    */  
    public static HttpServletRequest getOrgRequest(HttpServletRequest req) {  
        if(req instanceof XssHttpServletRequestWrapper){  
            return ((XssHttpServletRequestWrapper)req).getOrgRequest();  
        }  
      
        return req;  
    }  
}

新建XssFilter过滤器

package com.htsc.pos.web.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import com.htsc.pos.web.filter.xss.XssHttpServletRequestWrapper;

public class XssFilter implements Filter {

    public void init(FilterConfig config) throws ServletException {  
    }  
      
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {  
        XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);  
        chain.doFilter(xssRequest, response);  
    }
      
    public void destroy() {  
    }  
}

配置web.xml文件

<!-- 过滤替换特殊字符，防止xss攻击 -->
    <filter>
        <filter-name>XssFilter</filter-name>
        <filter-class>
            com.htsc.pos.web.filter.XssFilter
        </filter-class>
    </filter>
    <filter-mapping>
        <filter-name>XssFilter</filter-name>
        <url-pattern>*.do</url-pattern>
    </filter-mapping>