node.js--dns解析demo

浏览数：51 / 时间：2015年06月09日

//引入模块
var http = require(‘http‘),
    url = require(‘url‘),
    querystring = require(‘querystring‘),
    fs = require(‘fs‘),
    dns = require(‘dns‘);

//展现填写页面。由res.end输出查询的form表单
var goIndex = function(req, res){
    res.end("<html>" +
        "<head>" +
        "<title>DNS查询</title>" +
        "<meta http-equiv=‘content-type‘ content=‘text/html;charset=utf-8‘>" +
        "</head>" +
        "<body>" +
        "<form action=‘/parse‘ method=‘post‘>" +
        "<input type=‘text‘ name=‘search_dns‘/>" +
        "<input type=‘submit‘ value=‘查询‘ />" +
        "</form>" +
        "</body>" +
        "</html>");
};

//dns解析函数。通过dns模块的dns.resolve解析，解析成功执行回调,回调中把值写到参数函数的入参中
var goDns = function(postData, callback){
    var domainValue = querystring.parse(postData).search_dns; //获取post数据中的search_dns
    dns.resolve(domainValue, function(err, addresses){
        if(!addresses){
            addresses = [‘域名不存在‘];
        }
        callback(domainValue, addresses);
    });
};

//dns解析。获取post过来的数据，用dns模块进行解析，输出解析结果
var parseDns = function(req, res){
    //读取post过来的数据
    var postData = ‘‘;
    //req请求对象有addListener方法，‘data‘事件是有数据传送到服务端时触发，‘end‘是在数据发送完毕时触发
    req.addListener(‘data‘, function(dataChunk){
        postData += dataChunk;
    });
    req.addListener(‘end‘, function(){//数据完全传送完毕，进行dns解析
        goDns(postData, function(domain, addresses){//回调中输出解析结果展示页面
            res.end("<html>" +
                "<head>" +
                "<meta http-equiv=‘content-type‘ content=‘text/html;charset=utf-8‘>" +
                "</head>" +
                "<div>" +
                "domain: <span>" + domain + "</span>" +
                "ip:" + addresses.join(‘,‘) +
                "</div>" +
                "</html>");
        });
    });
};

var router = function(req, res, pathname){
    switch(pathname){
        case ‘/parse‘ :
            parseDns(req, res);
            break;
        default :
            goIndex(req, res);
    }
};

http.createServer(function(req, res){
    //获取请求相对路径
    var pathname = url.parse(req.url).pathname;
    //将请求设置为utf-8防止乱码
    req.setEncoding(‘utf8‘);
    //写返回的头
    res.writeHead(200, {‘Content-Type‘ : ‘text/html‘});
    //router请求路径若为/parse则进行dns解析，若不是则展示填写页面
    router(req, res, pathname);
})
    .listen(3000, ‘127.0.0.1‘);