java defense xss attack

.There
are many concepts and solutions about xss on the Internet, you can refer to this:

http://www.cnblogs.com/TankXiao/archive/2012/03/21/2337194.html#xsshappen

Here we talk about our solutions in recent projects , mainly uses the org.apache.commons.lang3.StringEscapeUtils.escapeHtml4() method of the commons-lang3-3.1.jar package.

The solution process is mainly in two steps of user input and display output: escape special characters such as <>" ' & when inputting, and use jstl's fn:excapeXml("fff") method when outputting.

Among them, the filtering during input is Use a filter to implement, the

implementation process:

add a filter to web.xml

<filter>
        <filter-name>XssEscape</filter-name>
        <filter-class>cn.pconline.morden.filter.XssFilter</filter-class >
    </filter>
    <filter-mapping>
        <filter-name>XssEscape</filter-name>
        <url-pattern>/*</url-pattern>

    </filter-mapping>



package cn.pconline.morden.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;

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

    @Override
    public void destroy() {
    }
}



package cn.pconline.morden.filter;

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

import org.apache.commons.lang3.StringEscapeUtils;

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {

    public XssHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
    }

    @Override
    public String getHeader(String name) {
        return StringEscapeUtils.escapeHtml4(super.getHeader(name));
    }

    @Override
    public String getQueryString() {
        return StringEscapeUtils.escapeHtml4(super.getQueryString());
    }

    @Override
    public String getParameter(String name) {
        return StringEscapeUtils.escapeHtml4(super.getParameter(name));
    }

    @Override
    public String[] getParameterValues(String name) {
        String[] values = super.getParameterValues(name);
        if(values != null) {
            int length = values.length;
            String[] escapseValues = new String[length];
            for(int i = 0; i < length; i++){
                escapseValues[i] = StringEscapeUtils.escapeHtml4(values[i]);
            }
            return escapseValues;
        }
        return super.getParameterValues(name);
    }
   
}