Xss问题解决方案

xss跨站脚本攻击问题最主要是呈现在html页面的脚本被执行导致的结果，可分为两个方便作屏蔽

后台屏蔽

在前端上传的各个参数后，对其进行转义后再保存至数据库，属于暴力式转义，一般不建议。下面是写的例子

1.创建HttpServletRequest新对象，覆盖其中的getParameterMap()方法，其会被ServletModelAttributeMethodProcessor处理方法参数时被调用，具体的读者可自行分析

package com.jing.springboot.test;

import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

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

import org.springframework.util.MultiValueMap;

public class FormHttpRequestWrapper extends HttpServletRequestWrapper {

    // 采用spring的MultiValueMap集合
	private MultiValueMap<String, String> paramsMap;

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

	public FormHttpRequestWrapper(HttpServletRequest request, MultiValueMap<String, String> paramMap) {
		super(request);
		this.paramsMap = paramMap;
	}

	@Override
	public String getParameter(String name) {
		String param = super.getParameter(name);
		return param == null ? paramsMap.getFirst(name) : param;
	}

	@Override
	public Map<String, String[]> getParameterMap() {
		Map<String, String[]> paramterMap = super.getParameterMap();

		Set<Entry<String, List<String>>> mapSets = paramsMap.entrySet();
		for (Entry<String, List<String>> mapSet : mapSets) {
			String key = mapSet.getKey();
			List<String> values = mapSet.getValue();
			paramterMap.put(key, values.toArray(new String[values.size()]));
		}

		return paramterMap;
	}

	@Override
	public Enumeration<String> getParameterNames() {
		return super.getParameterNames();
	}

	@Override
	public String[] getParameterValues(String name) {
		List<String> multiValues = paramsMap.get(name);
		String[] oldValues = super.getParameterValues(name);

		Set<String> trueValues = new HashSet<String>(oldValues.length + multiValues.size());
		for (String multi : multiValues) {
			trueValues.add(multi);
		}

		for (String old : oldValues) {
			trueValues.add(old);
		}

		return trueValues.toArray(new String[trueValues.size()]);
	}
}

2.创建参数拦截filter类过滤器，对每次的POST请求或者PUT请求作下拦截

package com.jing.springboot.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.FormHttpMessageConverter;
import org.springframework.http.converter.support.AllEncompassingFormHttpMessageConverter;
import org.springframework.util.MultiValueMap;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.util.HtmlUtils;

public class HttpContentFormFilter extends OncePerRequestFilter {

	private List<MediaType> supportMediaTypes = new ArrayList<MediaType>();

	private FormHttpMessageConverter messageConverter = new AllEncompassingFormHttpMessageConverter();

	public HttpContentFormFilter() {
		supportMediaTypes.add(MediaType.APPLICATION_FORM_URLENCODED);
	}

	@Override
	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
			throws ServletException, IOException {
		String method = request.getMethod();
		String contentType = request.getContentType();

		if (methodEqual(method) && mediaEqual(contentType)) {
			HttpInputMessage httpInputMessage = new FormHttpInputMessage(request);

			// 采用FormHttpMessageConverter对象读取参数集合
			MultiValueMap<String, String> springMultiValueMap = messageConverter.read(null, httpInputMessage);

			// 使用spring自带的HtmlUtils工具类来转义html标签
			useSpringHtmlEscape(springMultiValueMap);

			// 重新构造request对象，将转义后的参数存进去
			FormHttpRequestWrapper httpRequestWrapper = new FormHttpRequestWrapper(request, springMultiValueMap);

			filterChain.doFilter(httpRequestWrapper, response);
		} else {
			filterChain.doFilter(request, response);
		}
	}

	private boolean methodEqual(String reqMethod) {
		if (reqMethod.equals("POST") || reqMethod.equals("PUT")) {
			return true;
		}

		return false;
	}

	private boolean mediaEqual(String mediaType) {
		boolean isSupport = false;
		for (MediaType type : supportMediaTypes) {
			isSupport = type.includes(new MediaType(mediaType));
			if (isSupport) {
				break;
			}
		}

		return isSupport;
	}

	private void useSpringHtmlEscape(MultiValueMap<String, String> map) {
		Set<Entry<String, List<String>>> mapEntrySet = map.entrySet();
		for (Entry<String, List<String>> mapEntry : mapEntrySet) {
			mapEntry.setValue(escapeHtml(mapEntry.getValue()));
		}
	}

	private List<String> escapeHtml(List<String> values) {
		List<String> escapeValues = new ArrayList<String>(values.size());
		for (String value : values) {
			escapeValues.add(HtmlUtils.htmlEscape(value));
		}

		return escapeValues;
	}

	private class FormHttpInputMessage implements HttpInputMessage {

		private HttpServletRequest request;

		public FormHttpInputMessage(HttpServletRequest request) {
			this.request = request;
		}

		@Override
		public HttpHeaders getHeaders() {
			HttpHeaders headers = new HttpHeaders();
			Enumeration<String> headerNames = request.getHeaderNames();
			while (headerNames.hasMoreElements()) {
				String name = headerNames.nextElement();
				String headerValue = request.getHeader(name);
				headers.add(headerNames.nextElement(), headerValue);
			}

			return headers;
		}

		@Override
		public InputStream getBody() throws IOException {
			return request.getInputStream();
		}

	}

}

3.web.xml配置

<filter>
	<filter-name>httpFormFilter</filter-name>
	<filter-class>com.jing.springboot.test.HttpContentFormFilter</filter-class>
</filter>

<filter-mapping>
	<filter-name>httpFormFilter</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>

前端屏蔽

对上传的数据不作html过滤，对返回的数据呈现在页面上使用html标签过滤，建议采用，写一个专门的公用类即可

//html标签转义成自定义字符
function html2Escape(sHtml) { 
    return sHtml.replace(/[<>&"]/g,function(c){
        return {'<':'&lt;','>':'&gt;','&':'&amp;','"':'&quot;'}[c];
    }); 
}

总结

xss问题属于被动式攻击，一般很容易被忽略，在项目的安全检测中遇到此问题，在此作下笔记方便以后查阅