防止SQL注入和XSS攻击Filter

nbsp;今天系统使用IBM的安全漏洞扫描工具扫描出一堆漏洞，下面的filter主要是解决防止SQL注入和XSS攻击

一个是Filter负责将请求的request包装一下。

一个是request包装器，负责过滤掉非法的字符。

将这个过滤器配置上以后，世界总算清净多了。。

代码如下：

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;

/**
 * <code>{@link CharLimitFilter}</code>
 *
 * 拦截防止sql注入
 *
 * @author Administrator
 */
public class XssFilter implements Filter {

    /* (non-Javadoc)
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException,
            ServletException {

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

    }

}

包装器：

/**
 * <code>{@link XssHttpServletRequestWrapper}</code>
 *
 * TODO : document me
 *
 * @author Administrator
 */
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 || "".equals(s)) {
            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;
    }

}