2.10 网络报文的数据格式定义及使用
网络报文包含两个部分，头和体。
服务端
// Created by Surser on 2020/1/17.
// Copyright © 2020 Surser. All rights reserved.
//
#ifdef _WIN32
#include<windows.h>
#include<WinSock2.h>
#else
#include <unistd.h>
#include<arpa/inet.h>
#include<string.h>
#define SOCKET int
#define INVALID_SOCKET (SOCKET) (~0)
#define SOCKET_ERROR (-1)
#endif
#include <stdio.h>
#include<thread>
#include<iostream>
using namespace std;
enum CMD
{
CMD_LOGIN,
CMD_LOGOUT,
CMD_ERROR
};
struct DataHeader
{
short dataLength;
short cmd;
};
//DataPacket
struct Login
{
char userName[32];
char PassWord[32];
};
struct LoginResult
{
int result;
};
struct Logout
{
char userName[32];
};
struct LogoutResult{
int result;
};
int main(int argc, const char * argv[]) {
//
//1. 建立一个socket 三个参数变量，1 ip编码方式 ipv4；2 流式，面向字节流的；3 TCP；
SOCKET _sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
//2. bind 绑定用于接受客户端连接的端口
sockaddr_in _sin = {};
_sin.sin_family = AF_INET;
_sin.sin_port = htons(4567); //网络和本机字节序编码不同，需要转换，一个是大端编码，一个是小端编码
_sin.sin_addr.s_addr = INADDR_ANY; // 本机ip地址
if(SOCKET_ERROR == ::bind(_sock, (sockaddr*)&_sin, sizeof(sockaddr_in))){
cout<<"ERROR!绑定用于接受客户端连接的端口失败！\n";
}
else{
cout<<"绑定用于接受客户端连接的端口成功！\n";
}
//3. listen 监听网络端口
if(SOCKET_ERROR == listen(_sock, 5)){
cout<<"ERROR!监听网络端口失败！\n";
}
else{
cout<<"监听网络端口成功！\n";
}
//4. accept 等待接受客户端连接
sockaddr_in clientAddr = {};
socklen_t nAddrLen = sizeof(sockaddr_in);
SOCKET _cSock = INVALID_SOCKET;
_cSock = accept(_sock, (sockaddr*)&clientAddr, &nAddrLen);
if(INVALID_SOCKET == _cSock){
cout<<"ERROR!接收到无效客户端SOCKET！\n";
}
cout<<"新客户端加入：socket = "<<(int)_cSock<<"IP="<< inet_ntoa(clientAddr.sin_addr)<<"\n";
while(true)
{
DataHeader header = {};
//5. 接受客户端请求
int nLen = recv(_cSock, (char *)&header, sizeof(header), 0);
if(nLen<=0){
cout<<"客户端已退出，任务结束。\n";
break;
}
cout<<"收到命令："<<header.cmd<<"数据长度："<<header.dataLength<<"\n";
switch (header.cmd) {
case CMD_LOGIN:
{
Login login = {};
recv(_cSock, (char *)&login, sizeof(login), 0);
//忽略判断用户密码是否正确的过程
LoginResult ret = {1};
send(_cSock, (char*)&header, sizeof(header), 0);
send(_cSock, (char*)&ret, sizeof(ret), 0);
}
break;
case CMD_LOGOUT:
{
Logout logout = {};
recv(_cSock, (char *)&logout, sizeof(logout), 0);
//忽略判断用户密码是否正确的过程
LogoutResult ret = {1};
send(_cSock, (char*)&header, sizeof(header), 0);
send(_cSock, (char*)&ret, sizeof(ret), 0);
}
break;
default:
header.cmd = CMD_ERROR;
header.dataLength = 0;
send(_cSock, (char*)&header, sizeof(header), 0);
break;
}
}
//8. 关闭套接字closesocket
close(_sock);
//
cout<<"服务器已退出。\n";
getchar();
return 0;
}
``
客户端：
```cpp
//
// main.cpp
// hellocpp
//
// Created by Surser on 2020/1/17.
// Copyright © 2020 Surser. All rights reserved.
//
#ifdef _WIN32
#include<windows.h>
#include<WinSock2.h>
#else
#include <unistd.h>
#include<arpa/inet.h>
#include<string.h>
#define SOCKET int
#define INVALID_SOCKET (SOCKET) (~0)
#define SOCKET_ERROR (-1)
#endif
#include <stdio.h>
#include<thread>
#include<iostream>
using namespace std;
enum CMD
{
CMD_LOGIN,
CMD_LOGOUT,
CMD_ERROR
};
struct DataHeader
{
short dataLength;
short cmd;
};
//DataPacket
struct Login
{
char userName[32];
char PassWord[32];
};
struct LoginResult
{
int result;
};
struct Logout
{
char userName[32];
};
struct LogoutResult{
int result;
};
int main(int argc, const char * argv[]) {
// 1.建立一个socket
SOCKET _sock = socket(AF_INET, SOCK_STREAM, 0);
if(INVALID_SOCKET == _sock){
cout<<"错误！建立套接字失败\n";
}
else{
cout<<"建立套接字成功\n";
}
// 2.连接服务器connect
sockaddr_in _sin = {};
_sin.sin_family = AF_INET;
_sin.sin_port = htons(4567);
_sin.sin_addr.s_addr = inet_addr("127.0.0.1");
int ret = connect(_sock, (sockaddr *) &_sin, sizeof(sockaddr_in));
if(SOCKET_ERROR == ret){
cout<<"错误！连接服务器失败\n";
}
else{
cout<<"连接服务器成功\n";
}
while (true)
{
// 3.输入请求命令
char cmdBuf[128]={};
cin>>cmdBuf;
// 4.处理请求命令
if(0 == strcmp(cmdBuf, "exit"))
{
cout<<"收到exit，任务结束。\n";
break;
}
else if( 0 == strcmp(cmdBuf, "login"))
{
Login login = {"fjt","fjtmm"};
DataHeader dh = {sizeof(login), CMD_LOGIN};
//5.向服务器发送请求命令
send(_sock, (const char*)&dh, sizeof(dh), 0);
send(_sock, (const char*)&login, sizeof(login), 0);
// 接受服务器返回的数据
DataHeader retHeader = {};
LoginResult loginRet = {};
recv(_sock, (char*) &retHeader, sizeof(retHeader), 0);
recv(_sock, (char*) &loginRet, sizeof(loginRet), 0);
cout<<"LoginResult:"<<loginRet.result;
}
else if( 0 == strcmp(cmdBuf, "logout"))
{
Logout logout = {"fjt"};
DataHeader dh = {sizeof(logout), CMD_LOGOUT};
send(_sock, (const char*)&dh, sizeof(dh), 0);
send(_sock, (const char*)&logout, sizeof(logout), 0);
// 接受服务器返回的数据
DataHeader retHeader = {};
LoginResult logoutRet = {};
recv(_sock, (char*) &retHeader, sizeof(retHeader), 0);
recv(_sock, (char*) &logoutRet, sizeof(logoutRet), 0);
cout<<"LogoutRet:"<<logoutRet.result;
}
else {
cout<< "不支持命令，请重新输入\n";
}
}
// 7.关闭套接字close
close(_sock);
cout<<"客户端已退出。\n";
getchar();
return 0;
}
2.15 将多次收发报文数据升级为一次收发
- update: 之前报文数据分为头部和身体两个部分进行收发，容易出次。这里升级为一次收发，另身体部分公有继承头部。
https://github.com/surserrr/learn_socket/tree/4d6b4fdf9876332cf5b8bd1912a64fffb45357f7
