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Nodejs的DNS模块包涵有关DNS查询和操作的方法,下面介绍该模块的基本用法以及实现一个DNS查询小工具。

1.获取DNS服务器地址

使用getServers方法,该方法返回一个IP地址组成的数组,如下所示:

const dns = require('dns');
const servers = dns.getServers();
console.log(servers);

返回结果为:

[ '114.114.114.114', '8.8.8.8',
'fec0:0:0:ffff::1', '114.114.114.114',
'8.8.8.8', '114.114.114.114',
'8.8.8.8' ]

2.使用系统特性域名解析获取IP地址

使用dns.lookup(hostname[, options], callback)方法,options参数包涵以下属性:

  • family:地址协议族,必须为4或6的整数
  • hints:设置getaddrinfo的标志,dns.ADDRCONFIG 或者 dns.V4MAPPED(ipv4映射成ipv6)
  • all:false(默认),布尔值,如设置为true,则返回IP数组,否则返回单个IP地址

callback回调函数有三个参数(err,address,family),如果options的all属性设置为true,则只有(err,addresses)参数且addresses为一个数组,数组元素为{address,family}对象。使用如下所示:

dns.lookup('www.baidu.com',(err,address,family)=>{
  if(err) throw err;
  console.log('百度网站的IP地址是:'+address+'地址协议族是:IPV'+family);
});

结果如下:

E:\developmentdocument\nodejsdemo>node dns-example.js
百度网站的IP地址是:14.215.177.37地址协议族是:IPV4

设置options的all为true时,结果如下:

dns.lookup('www.baidu.com',{family:4,all:!0,hints:dns.ADDRCONFIG|dns.V4MAPPED},(err,addresses)=>{
  if(err) throw err;
  addresses.forEach((ele,idx,arr)=>{
    console.log('百度网站的IP地址'+(idx+1)+'是:'+ele.address);
  });
});

结果如下:

E:\developmentdocument\nodejsdemo>node dns-example.js
百度网站的IP地址1是:14.215.177.38
百度网站的IP地址2是:14.215.177.37

3.根据IP和端口获取主机名

使用dns.lookupService(address, port, callback)方法,该方法依赖getnameinfo底层函数。
callback函数有三个参数(err, hostname, service),service是protocol,为http或https,使用如下所示:

dns.lookupService('127.0.0.1',80,(err,hostname,service)=>{
  if(err) console.log(err);
  console.log('该IP对应的主机为:'+hostname+' 协议为:'+service);
});

结果如下:

E:\developmentdocument\nodejsdemo>node dns-example.js
该IP对应的主机为:www.test.zmx.com 协议为:http

4.使用网络域名解析获取IP地址

使用dns.resolve(hostname[, rrtype], callback)方法,rrtype有以下选择:

  • 'A':IPV4,default
  • 'AAAA':IPV6
  • 'MX' - mail exchange records 邮件交换记录
  • 'TXT' - text records 域名配置说明
  • 'SRV' - SRV records 服务器提供的服务
  • 'PTR' - PTR records
  • 'NS' - name server records 域名服务器
  • 'CNAME' - canonical name records 别名记录
  • 'SOA' - start of authority record 起始授权机构
  • 'NAPTR' - name authority pointer record

callback函数有(err, addresses)两个参数,addresses是一个数组,具体成员需要看具体的rrtype,使用如下所示:

//获取IPV4
dns.resolve('www.qq.com','A',(err,address)=>{
  if(err) throw err;
  console.log(address);//结果为[ '14.17.32.211', '14.17.42.40', '59.37.96.63' ]
});
//获取IPV6
dns.resolve('www.qq.com','AAAA',(err,address)=>{
  if(err) throw err;
  console.log(address);//结果为[ '240e:ff:f040:28::a' ]
});
//获取SOA信息
dns.resolve('www.qq.com','SOA',(err,address)=>{
  if(err) throw err;
  console.log(address);
  //结果为
  { nsname: 'ns-tel1.qq.com',
   hostmaster: 'webmaster.qq.com',
   serial: 1380440321,
   refresh: 300,
   retry: 600,
   expire: 86400,
   minttl: 300 }
});
//获取别名CNAME
dns.resolve('www.baidu.com','CNAME',(err,address)=>{
  if(err) throw err;
  console.log(address);//结果为[ 'www.a.shifen.com' ]
});

resovle还存在很多快捷方法,例如:resolve4,resolve6,resolveCname...等等

5.反向域名解析

使用dns.reverse(ip, callback)方法,callback有两个参数(err, hostnames),hostnames是一个域名数组,使用如下所示:

dns.reverse('114.114.114.114',(err,hostnames)=>{
  if(err) throw err;
  console.log(hostnames);//结果为[ 'public1.114dns.com' ]
});

学完了以上的知识后,可以做个DNS查询的小工具,如下所示:

第一步,写个HTML静态页面,如下:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>DNS查询工具</title>
  <style type="text/css">
    html,body{ width: 100%; height: 100%; }
    body{ display: flex; align-items: center; justify-content: center; flex-direction: column; }
    *{ margin:0; padding: 0; }
    ul{ list-style: none; }
    .res{line-height: 24px; color:#333; }
    .clearfix:after{ display: block; content:''; height: 0; visibility: hidden; clear: both;}
    .fl{ float:left; }
    .g-wrap{ display: flex; width:560px; height: 40px; }
    .u-list{position: relative; flex:1; }
    .u-inp{flex:3; border:1px solid #ccc; border-left: none; border-right:none; padding:11px 0 11px 10px;}
    .u-btn{ flex:1; }
    .list{ display: none; position: absolute; left: 0px; top:40px; width: 100%; border:1px solid #ccc; border-top:none; border-bottom:none; box-sizing: content-box; }
    .item{ height: 30px; line-height: 30px; text-align: center; color: #666; border-bottom: 1px solid #ccc; cursor:pointer;}
    .item:hover{ color:#0087dc; }
    .u-list .type{ display: block; width: 100%; line-height: 38px; border:1px solid #ccc; text-align: center; color:#666; text-decoration: none; }
    .u-list .type:after{ content: ''; position: absolute; width:0; height:0; border:8px solid transparent; border-top-color:#ccc; right:4px; top:16px;}
    .u-inp input{ width: 100%; border:none; outline: none; height: 18px; line-height: 18px; color:#666; vertical-align: top; font-size: 14px; }
    .u-btn .btn{ display: block; line-height: 40px; text-align: center; background-color: #0087dc; color:#fff; font-size: 16px; cursor:pointer; transition: background-color .3s;}
    .u-btn .btn:hover{ background-color: #0060b2; }
  </style>
</head>
<body>
  <div id="res" class="res"></div>
  <div class="g-wrap clearfix">
    <div class="u-list fl">
      <a href="javascript:;" class="type" id="type" data-value="A">IPV4</a>
      <ul id="list" class="list">
        <li class="item" data-value="A">IPV4</li>
        <li class="item" data-value="AAAA">IPV6</li>
        <li class="item" data-value="CNAME">CNAME</li>
        <li class="item" data-value="SOA">SOA</li>
      </ul>
    </div>
    <div class="u-inp fl">
      <input type="text" class="host" id="host" placeholder="请输入域名">
    </div>
    <div class="u-btn fl">
      <span class="btn" id="btn">查询</span>
    </div>
  </div>
  <script>
    function hide(el){
      el.style.display = 'none';
    }
    function show(el){
      el.style.display = 'block';
    }
    function dealResult(responseText){
      var ips = [],
        result = '';
      ips = JSON.parse(responseText).ips;
      if(Array.isArray(ips)){
        result = ips.length > 0 "POST",
        url = "/dnslookup";

      xhr.open(method, url, true);
      xhr.onreadystatechange = function() {
        if (xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
          dealResult(xhr.responseText);
        }
      };
      xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
      xhr.send('host='+hostname+'&rrtype='+rrtype);
    },!1);
  </script>
</body>
</html>

接着编写服务端代码,如下:

var http = require('http'),
  url = require('url'),
  dns = require('dns'),
  qs  = require('querystring'),
  fs  = require('fs');

function router(req,res,pathname){
  switch(pathname){
    case '/dnslookup':
      lookup(req,res);
      break;
    default:
      showIndex(req,res);
  }
}

function showIndex(req,res){
  var pagePath = __dirname+'/'+'dns-lookup.html';
  var html = fs.readFileSync(pagePath);
  res.end(html);
}

function lookup(req,res){
  var postData = '';
  req.on('data',function(data){
    postData+=data;
  });
  req.on('end',function(data){
    var json = qs.parse(postData);
    var hostname = json.host;
    var rrtype = json.rrtype;
    dns.resolve(hostname,rrtype,function(err,adresses){
      if(err){
        res.end(JSON.stringify({errcode:1,ips:[]}));
      }
      res.end(JSON.stringify({errcode:0,ips:adresses}));
    });
    
  });
}

http.createServer(function(req,res){
  var pathname = url.parse(req.url).pathname;
  req.setEncoding("utf8");
  res.writeHead(200,{'Content-Type':'text/html'});
  router(req,res,pathname);
}).listen(3000,'127.0.0.1');

运行效果如下:浅析Node.js:DNS模块的使用

到此这个小工具便完成了。

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。

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