# TCP, UDP ## TCP, UDP, HTTP, HTTPS 網路七層協議 TCP的特色在於傳輸資料時，會有握手的過程，以確保雙方身份，所以花的時間多一點。而UDP的特色在於傳輸資料時，不需要驗證資料，不保證正確性，發送端不知道數據是否會正確接收，所以速度較快速一般瀏覽網頁時使用的協議是HTTP與HTTPS，其主要是基於TCP，為TCP往上之發展 ## Node.js中的TCP 在node.js主要使用`net`這個核心模組來提供TCP的相關功能，一般主要是在做與硬體溝通時會使用到具有TCP中的TCP server與 TCP client的兩種類型 ### 實作 1.進入資料夾第10章中的TCP資料夾，執行test1.js來執行TCP server 2.開啟另一個terminal，一樣進入資料夾第10章中的TCP資料夾，執行test2.js 3.結合Repl 將client test2.js改為如下 ``` var net = require('net'); var HOST = 'localhost'; var PORT = 8000; var client = new net.Socket(); //建立一個新的socket實例 client.connect(PORT, HOST, function() { console.log('CONNECTED TO: ' + HOST + ':' + PORT); client.write('hello,this is from client!');//發送給server數據 const repl = require('repl'); var test = repl.start('請輸入: ').context; test.hello = function() { client.write('client說了hello!'); } //之後啟動client後輸入hello() }); client.on('data', function(data) { console.log('DATA: ' + data); }); client.on('close', function() { console.log('Connection closed'); }); ``` 利用 net module 製作 HTTP server ```javascript const net = require('net'); const server = net.createServer((socket) => { socket.on('data', data => { console.log(data.toString()) socket.end(` HTTP/1.1 200 OK\r\nContent-type: text/html\r\n test `) }) }).on('error', (err) => { // Handle errors here. throw err; }); // Grab an arbitrary unused port. server.listen(8124, () => { console.log('opened server on', 8124); }); ``` ## Node.js中的UDP 主要使用名為`dgram`的核心模組全名為`UDP / Datagram Sockets` ### 實作 1.進入資料夾第10章中的UDP資料夾，執行test1.js來執行UDP server 2.開啟另一個terminal，一樣進入資料夾第10章中的UDP資料夾，執行test2.js 3.實作UDP廣播機制 UDP具有TCP所沒擁有的技能(廣播封包)，可以把封包廣播給區網內的每一台電腦使用廣播封包時，LAN 上面的每台電腦都會被迫處理這類封包 ### UDP廣播 (需要兩台以上電腦在同一個區網內才可測試) 接收方(所有區網上其他電腦所架設的UDP server) ``` var udp = require("dgram"); var socket = udp.createSocket('udp4',function(msg){ console.log(msg.toString()) }); socket.bind(8080); ``` 廣播方client ``` var udp = require("dgram"); var client = udp.createSocket("udp4",function(){}); client.on("listening",function(){ client.setBroadcast(true); }) process.stdin.on("data",function(data){ client.send(data,0,data.length,8080,"255.255.255.255"); }); ``` ### 但IPv6 不支援廣播，只支援群播（multicasting），所以可將程式碼改為如下 server ``` var news = [ "hello", "this is multicasting", ]; var dgram = require('dgram'); var server = dgram.createSocket("udp4"); server.bind(); server.setBroadcast(true) server.setMulticastTTL(128); //有關TTL 可參考https://nodejs.org/api/dgram.html#dgram_socket_addmembership_multicastaddress_multicastinterface server.addMembership('230.185.192.108'); //可參考如下 //https://nodejs.org/api/dgram.html#dgram_socket_addmembership_multicastaddress_multicastinterface //https://en.wikipedia.org/wiki/Multicast_address setInterval(broadcastNew, 3000); function broadcastNew() { var message = new Buffer(news[Math.floor(Math.random()*news.length)]); server.send(message, 0, message.length, 8088, "230.185.192.108"); console.log("Sent " + message + " to the wire..."); //server.close(); } ``` client ``` var PORT = 8088; var HOST = '192.168.0.102'; var dgram = require('dgram'); var client = dgram.createSocket('udp4'); client.on('listening', function () { var address = client.address(); console.log('UDP Client listening on ' + address.address + ":" + address.port); client.setBroadcast(true) client.setMulticastTTL(128); client.addMembership('230.185.192.108',HOST); }); client.on('message', function (message, remote) { console.log('A: Epic Command Received. Preparing Relay.'); console.log('B: From: ' + remote.address + ':' + remote.port +' - ' + message); }); client.bind(PORT, HOST); ``` 以上參考至可參考一篇不錯的文章: --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://easonwang.gitbook.io/class/tcpudphttphttps.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.