package com.filter;

import com.utils.StringUtils;
import org.springframework.stereotype.Component;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * sql注入过滤器
 */
@Component
@WebFilter(urlPatterns = "/*", filterName = "SQLInjection")
public class SqlInjectFilter implements Filter {
    private static String regx = "(?:‘)|(?:--)|(/\\*(?:.|[\\n\\r])*?\\*/)|(\\b(select|update|and|or|delete|insert|trancate|char|into|substr|ascii|declare|exec|count|master|into|drop|execute)\\b)";
    private static Set<String> notAllowedKeyWords = new HashSet<String>(0);
    private static String replacedString = "INVALID";
    static {
        String keyStr[] = regx.split("\\|");
        for (String str : keyStr) {
            notAllowedKeyWords.add(str);
        }
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) servletRequest;
        Map parametersMap = servletRequest.getParameterMap();
        Iterator it = parametersMap.entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            String[] value = (String[]) entry.getValue();
            for (int i = 0; i < value.length; i++) {
                if (null != value[i] && checkSqlKeyWords(value[i])) {
　　　　　　　　　　　　/*可根据业务场景切换*/
                    value[i] = cleanSqlKeyWords(value[i]);
//                    servletRequest.setAttribute("err", "您输入的参数有非法字符，请输入正确的参数！");
//                    servletRequest.setAttribute("pageUrl", req.getRequestURI());
//                    servletRequest.getRequestDispatcher(servletRequest.getServletContext().getContextPath() + "/error").forward(servletRequest, servletResponse);
//                    return ;
                }
            }
        }
        filterChain.doFilter(servletRequest,servletResponse);
    }

    private String cleanSqlKeyWords(String value){
        String paramValue = value;
        for (String keyWord : notAllowedKeyWords) {
            if (paramValue.length() > keyWord.length() && (paramValue.contains(" "+keyWord)||paramValue.contains(keyWord+" ")||paramValue.contains(" "+keyWord+" ")||paramValue.contains(keyWord))) {
                paramValue = paramValue.replace(keyWord,"");
            }
        }
        return paramValue;
    }

    public boolean checkSqlKeyWords(String value){
        String paramValue = value;
        for (String keyword : notAllowedKeyWords) {
            if (paramValue.length() > keyword.length() && (paramValue.contains(" "+keyword)||paramValue.contains(keyword+" ")||paramValue.contains(" "+keyword+" ")||paramValue.contains(keyword))) {
                return true;
            }
        }
        return false;
    }

    @Override
    public void destroy(){

    }

}