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网络通信
一、网络通信
1. 网络通信基本原理
通信必要条件:
主机之间须要有传输介质(数据信号的传输)
主机上必须有网卡设施(数据信号的调制与解调制)
主机之间须要协商网络速率
图示:
2. 网络通信形式
交换机通信
路由器通信
图示:(利用 Mac 地址,定位主机)
毛病:
交换机的接口数量有下限
局域网存在大量主机会造成播送风暴(任意一条音讯都须要其它机器接管,再确认受否无效)
路由器应用 (连贯局域网) 图示:
3. 网络层次模型
OSI 七层模型:
数据的封装与解封装(TCP/IP 五层协定模式):
参考:https://blog.csdn.net/weixin_…
4.tcp 协定
tcp 报文构造图解:
常见管制字段:
三次握手图解:
四次挥手图解:
为什么挥手中,两头两次不能合并呢?
一个服务端会服务于多个客户端,服务端接管到音讯后,不肯定能即便将后果及时传回
TCP 协定总结:
TCP 处于传输层,基于端口,面向连贯
主机之间要想通信须要先建设双向数据通道
TCP 的握手与挥手实质上都是四次
二、创立 TCP 通信
Net 模块实现了底层通信接口
通信过程:
创立服务端:接管和回写客户端数据
创立客户端:发送和接管服务端数据
数据传输:内置服务事件和办法读写数据
外围内置通信事件:
listening 事件:调用 server.listen 办法之后触发
connection 事件:新的连贯建设时触发
close 事件:当 server 敞开时触发
error 事件:当谬误呈现的时候触发
通信事件 & 办法:
data 事件:当接管到数据的时候触发该事件
write 办法:在 socket 上发送数据,默认是 UTF8 编码
end 操作:当 socket 的一端发送 FIN 包时触发,完结可读端
1.net 模块应用
node 中 tcp 连贯的创立与通信:
server:
const net = require('net');
// 创立服务端实例
const server = net.createServer();
const PORT = 1234;
const HOST = 'localhost';
// 监听该端口
server.listen(PORT, HOST);
server.on('listening',()=>{console.log(` 服务端曾经开启在 ${HOST}:${PORT}`);
});
// 就收音讯,回写音讯 socket 双工流
server.on('connection',(socket)=>{console.log('有客户端连贯');
socket.on('data',(chunk)=>{const msg = chunk.toString();
console.log('client:'+msg);
// 回写音讯
socket.write(Buffer.from('hello client'));
})
});
server.on('close',()=>{console.log('服务端曾经敞开');
})
server.on('error',(err)=>{console.log('服务端产生谬误',err);
})
client:
const net = require('net');
const client = net.createConnection({
port: 1234,
host: '127.0.0.1'
})
client.on('connect', () => {client.write('hello server');
})
client.on('data',(chunk)=>{console.log('server:'+chunk.toString());
});
client.on('err',()=>{console.log('客户端产生谬误');
});
client.on('close',()=>{console.log('客户端曾经敞开');
})
2.TCP 粘包问题
问题展现:
client 代码:
client.on('connect', () => {client.write('hello server');
client.write('hello server');
client.write('hello server');
client.write('hello server');
})
server 代码:
server.on('connection',(socket)=>{console.log('有客户端连贯');
socket.on('data',(chunk)=>{const msg = chunk.toString();
console.log('client:'+msg);
// 回写音讯
socket.write(Buffer.from('hello client'));
})
});
后果展现:
‘client:’ 打印了一次,呈现了粘包问题,
1. 间断发送数据
client 代码:
let dataArr = [
'hello server',
'hello server-2',
'hello server-3',
'hello server-4',
]
client.on('connect', () => {for (let i = 0; i < dataArr.length; i++) {(function (val, index) {setTimeout(() => {client.write(val)
}, 1000 * (index + 1))
})(dataArr[i], i)
}
})
正确成果:
2. 数据的封包与拆包
约定包的构造:
数据传输过程:
进行数据编码,获取二进制数据包
按规定拆解数据,获取指定长度的数据
Buffer 数据读写:
writeInt16BE:将 value 从指定地位写入
readInt16BE:从指定地位开始读取数据
封包与拆包类实现:
class MyTransformCode {constructor() {
this.packageHeaderLen = 4;
this.serialNum = 0;
this.serialLen = 2;
}
// 编码
encode(data, serialNum) {let body = Buffer.from(data);
// 01 先依照指定的长度申请一个缓冲区
const headerBuf = Buffer.alloc(this.packageHeaderLen);
// 02 再把数据写入缓冲区
headerBuf.writeInt16BE(serialNum || this.serialNum);
headerBuf.writeInt16BE(body.length, this.serialLen);
if (serialNum === undefined) {this.serialNum++;}
return Buffer.concat([headerBuf, body]);
}
decode(buffer) {let headerBuf = buffer.slice(0, this.packageHeaderLen);
const bodyBuf = buffer.slice(this.packageHeaderLen);
return {serialNum: headerBuf.readInt16BE(),
bodyLength: headerBuf.readInt16BE(this.serialLen),
body: bodyBuf.toString()}
}
// 获取包长度
getPackageLen(buffer){if(buffer.length < this.packageHeaderLen){return 0;}else{return this.packageHeaderLen+buffer.readInt16BE(this.serialLen);
}
}
}
应用:
const MyTransform = require('./03-myTransform');
let ts = new MyTransform();
let str1 = '江江学习';
let encodeBuf = ts.encode(str1,1);
console.log(ts.decode(encodeBuf));
let len = ts.getPackageLen(encodeBuf);
console.log(len)
封包解决粘包:
// server
server.on('connection', (socket) => {console.log('有客户端连贯');
socket.on('data', (chunk) => {if (overageBuffer) {chunk = Buffer.concat([overageBuffer, chunk]);
overageBuffer = null;
}
let packageLen = 0;
while (packageLen = ts.getPackageLen(chunk)) {const packageCon = chunk.slice(0, packageLen);
chunk = chunk.slice(packageLen);
const ret = ts.decode(packageCon);
console.log(ret);
// 回写音讯
socket.write(ts.encode(ret.body, ret.serialNum));
}
overageBuffer = chunk;
})
});
// client
client.on('connect', () => {client.write(ts.encode('拉钩教育'));
client.write(ts.encode('拉钩教育'));
client.write(ts.encode('拉钩教育'));
client.write(ts.encode('拉钩教育'));
client.write(ts.encode('拉钩教育'));
client.write(ts.encode('拉钩教育'));
})
client.on('data', (chunk) => {if (overageBuffer) {chunk = Buffer.concat([overageBuffer, chunk]);
overageBuffer = null;
}
let packageLen = 0;
while (packageLen = ts.getPackageLen(chunk)) {const packageCon = chunk.slice(0, packageLen);
chunk = chunk.slice(packageLen);
const ret = ts.decode(packageCon);
console.log(ret);
}
overageBuffer = chunk;
});
三、Http 协定
1. 应用 http 模块
开启一个 http 服务器:
const http = require('http');
let server = http.createServer((req,res)=>{res.end('hello world');
});
server.listen(1234,()=>{console.log('server is listening 1234');
})
获取 http 申请信息:
const http = require('http');
const url = require('url');
const server = http.createServer((req,res)=>{
// 申请门路
let {pathname,query} = url.parse(req.url,true);
console.log('pahtinfo:',pathname,'----',query)
// 申请办法
console.log('method:',req.method);
// 版本号
console.log('httpVersion:',req.httpVersion);
// 申请头
console.log('headers:',req.headers);
let arr = []
// 申请体
req.on('data',(data)=>{arr.push(data);
});
req.on('end',()=>{console.log('body:',Buffer.concat(arr).toString())
})
res.end('hello client')
});
server.listen(1234,()=>{console.log('server is listening 1234');
})
设置 http 响应:
const http = require('http');
const server = http.createServer((req,res)=>{console.log('request enter');
// 设置响应状态码
res.statusCode = 302;
// 设置响应头信息
res.setHeader('Content-Type','text/html;charset=utf-8');
// res.write('ok');
res.end('江江');
});
server.listen(1234,()=>{console.log('servet is listening 1234');
})
2. 客户端代理
agent-server 代码:
const http = require('http');
const url = require('url');
const qeurystring = require('querystring');
const server = http.createServer((req, res) => {let { pathname, query} = url.parse(req.url, true);
console.log(pathname, '---', query);
let arr = [];
req.on('data', (data) => {arr.push(data);
})
req.on('end', () => {let obj = Buffer.concat(arr).toString();
if(req.headers['content-type'] == 'application/json'){let ret = JSON.parse(obj);
ret.add = 'add';
res.end(JSON.stringify(ret));
}else if(req.headers['content-type'] == 'application/x-www-form-urlencoded'){let ret = qeurystring.parse(obj);
res.end(JSON.stringify(ret));
}
})
})
server.listen(1234, () => {console.log('server is listening 1234');
})
agent-client 代码:
const http = require('http');
let options = {
host: 'localhost',
port: 1234,
path: '/',
method: 'POST',
headers: {'Content-Type': 'application/x-www-form-urlencoded',}
}
let req = http.request(options, (res) => {let arr = [];
res.on('data',(chunk)=>{arr.push(chunk);
})
res.on('end',()=>{console.log(Buffer.concat(arr).toString());
})
})
// req.end(`{"name":"zhangsan"}`)
req.end(`a=1&b=2`)
3. 代理客户端跨域
内部服务器代码:
const http = require('http');
const server = http.createServer((req, res) => {let arr = [];
req.on('data',(data)=>{arr.push(data);
})
req.on('end',()=>{console.log(Buffer.concat(arr).toString());
res.end('内部服务 i 器端数据');
})
})
server.listen(1234, () => {console.log('内部服务端启动了');
})
代理客户服务器:
const http = require('http');
let options = {
host: 'localhost',
port: 1234,
path: '/',
method: 'POST'
}
let server = http.createServer((request, response) => {let req = http.request(options, (res) => {let arr = [];
res.on('data', (data) => {arr.push(data);
})
res.on('end', () => {let ret = Buffer.concat(arr).toString();
response.setHeader('Content-Type', 'text/html;charset=utf-8');
console.log('ret', ret)
response.end(ret)
})
})
req.end('hello world');
})
server.listen(2345, () => {console.log('本地服务端曾经启动');
})
正文完