XSS攻击解决方案之一（过滤器）

一、XssFilter.java

package com.stylefeng.roses.core.xss;


import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.List;


public class XssFilter implements Filter {

    FilterConfig filterConfig = null;

    private List urlExclusion = null;

    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }

    public void destroy() {
        this.filterConfig = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        String servletPath = httpServletRequest.getServletPath();

        if (urlExclusion != null && urlExclusion.contains(servletPath)) {
            chain.doFilter(request, response);
        } else {
            chain.doFilter(new XssHttpServletRequestWrapper((HttpServletRequest) request), response);
        }
    }

    public List getUrlExclusion() {
        return urlExclusion;
    }

    public void setUrlExclusion(List urlExclusion) {
        this.urlExclusion = urlExclusion;
    }
}

二、配置web.xml文件

    
		XssFilter
		com.powersi.hygeia.web.filter.XssFilter
		
	
	
		XssFilter
		业务
	
	

三、其实核心在XssHttpServletRequestWrapper中的cleanXSS方法（定义了转义的字符）。

package com.stylefeng.roses.core.xss;


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


public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {

    public XssHttpServletRequestWrapper(HttpServletRequest servletRequest) {

        super(servletRequest);

    }

    public String[] getParameterValues(String parameter) {

        String[] values = super.getParameterValues(parameter);

        if (values == null) {

            return null;

        }

        int count = values.length;

        String[] encodedValues = new String[count];

        for (int i = 0; i < count; i++) {

            encodedValues[i] = cleanXSS(values[i]);

        }

        return encodedValues;

    }

    public String getParameter(String parameter) {

        String value = super.getParameter(parameter);

        if (value == null) {

            return null;

        }

        return cleanXSS(value);

    }

    public String getHeader(String name) {

        String value = super.getHeader(name);

        if (value == null)

            return null;

        return cleanXSS(value);

    }

    private String cleanXSS(String value) {

        //You'll need to remove the spaces from the html entities below

        value = value.replaceAll("<", "& lt;").replaceAll(">", "& gt;");

        value = value.replaceAll("\\(", "& #40;").replaceAll("\\)", "& #41;");

        value = value.replaceAll("'", "& #39;");

        value = value.replaceAll("eval\\((.*)\\)", "");

        value = value.replaceAll("[\\\"\\\'][\\s]*javascript:(.*)[\\\"\\\']", "\"\"");

        value = value.replaceAll("script", "");

        return value;

    }


}