XSS漏洞解决方案之一：过滤器

<!-- 解决xss漏洞 -->
<filter>
<filter-name>xssFilter</filter-name>
<filter-class>com.baidu.rigel.sandbox.core.filter.XSSFilter</filter-class>
</filter>

<!-- 解决xss漏洞 -->
<filter-mapping>
<filter-name>xssFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

package com.rigel.sandbox.core.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.rigel.sandbox.core.util.XssHttpServletRequestWrapper;

public class XSSFilter implements Filter {

@Override
public void init(FilterConfig filterConfig) throws ServletException {
}

@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {

XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper(
(HttpServletRequest) request);
chain.doFilter(xssRequest, response);
}

@Override
public void destroy() {
}

}

package com.rigel.sandbox.core.util;

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(">");// 转义大于号
break;
case '<':
sb.append("<");// 转义小于号
break;
case '\'':
sb.append("'");// 转义单引号
break;
case '\"':
sb.append(""");// 转义双引号
break;
case '&':
sb.append("&");// 转义&
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;
}
}