前段时间做了个TCP/IP通讯的项目，现记录一下一些关键的内容

先构建一个服务端：

#include "stdafx.h"
#include <WinSock2.h>
#include <iostream>
#include <fstream>
#include <direct.h>
#pragma comment(lib,"ws2_32.lib")   //静态加入一个lib文件
int main()
{
	//开始时创建文件夹
	string pathname[5] = { "D:/*****",
						"D:/******",
						"D:/******" ,
						"D:/******",
						"D:/******" };
	for (int i = 0; i < 5; i++)
	{
		if (0 !=pathname[i].c_str())
		{
			// if this folder not exist, create a new one.
			_mkdir(pathname[i].c_str());   // 返回 0 表示创建成功，-1 表示失败
		}
	}
	

	WORD sockVersion = MAKEWORD(2, 2);
	WSADATA wsaData;
	if (WSAStartup(sockVersion, &wsaData) != 0)
		return 0;
	SOCKET listenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
	if (listenSocket == INVALID_SOCKET)
	{
		printf("套接字创建失败");
		WSACleanup();
		return 0;
	}
	/*绑定IP和端口*/
	//配置监听地址和端口
	sockaddr_in addrListen;
	addrListen.sin_family = AF_INET;     //指定IP格式
	addrListen.sin_port = htons(4001);   //绑定端口号
	//addrListen.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");  
	addrListen.sin_addr.S_un.S_addr = INADDR_ANY;    //表示任何IP 
	if (bind(listenSocket, (SOCKADDR*)&addrListen, sizeof(addrListen)) == SOCKET_ERROR)  //(SOCKADDR*)
	{
		printf("绑定失败");
		closesocket(listenSocket);
		return 0;
	}
	/*开始监听*/
	if (listen(listenSocket, 5) == SOCKET_ERROR)
	{
		printf("监听出错");
		closesocket(listenSocket);
		return 0;
	}
	/*等待连接，连接后建立一个新的套接字*/
	SOCKET revSocket;  //对应此时所建立连接的套接字的句柄
	sockaddr_in remoteAddr;   //接收连接到服务器上的地址信息
	int remoteAddrLen = sizeof(remoteAddr);
	printf("等待连接...\n");
	/*等待客户端请求，服务器接收请求*/
	revSocket = accept(listenSocket, (SOCKADDR*)&remoteAddr, &remoteAddrLen);  //等待客户端接入，直到有客户端连接上来为止
	if (revSocket == INVALID_SOCKET)
	{
		printf("客户端发出请求，服务器接收请求失败：\n", WSAGetLastError());
		closesocket(listenSocket);
		WSACleanup();
		return 0;
	}
	else
	{
		printf("客服端与服务器建立连接成功：%s \n", inet_ntoa(remoteAddr.sin_addr));
	}
	char revData[2048];
	memset(revData, 0, 2048);
	while (true)
	{
		
		/*通过建立的连接进行通信*/
		int res = recv(revSocket, revData, 2048, 0);
		if (res <= 0)
		{
			if(res==0)
				printf("Connection closed\n");
			else
				printf("recv failed: %d\n", WSAGetLastError());
			printf("等待连接...\n");
			revSocket = accept(listenSocket, (SOCKADDR*)&remoteAddr, &remoteAddrLen);  //等待客户端接入，直到有客户端连接上来为止
			if (revSocket == INVALID_SOCKET)
			{
				printf("客户端发出请求，服务器接收请求失败：\n", WSAGetLastError());
				closesocket(listenSocket);
				WSACleanup();
				return 0;
			}
			else
			{
				printf("客服端与服务器建立连接成功：%s \n", inet_ntoa(remoteAddr.sin_addr));
			}
		}

		int len = 0;
		while ((BYTE)(revData[len]) != 0 && len<2048)
		{
			len++;              //读取revData的实际长度
		}
		fstream ftxt;           //写入txt
		ftxt.open("./data.txt", ios::out | ios::app | ios::binary);
		if (ftxt.fail())
		{
			cout << "can not open it" << endl;
			getchar();
			return 0;
		}
		ftxt.write(revData, len);
		ftxt.close();
		memset(revData, 0, 2048);
	}

在客服端中：

#include<winsock.h>
HICON m_hIcon;
SOCKET socket_client;
WORD ver = MAKEWORD(2, 0);
WSADATA wsadata;
if (WSAStartup(ver, &wsadata))
{
	MessageBox(_T("load winsock dll failing"), _T("load"));
	return FALSE;
}
//create socket
//socket_client = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
socket_client = socket(AF_INET, SOCK_STREAM, 0);
if (INVALID_SOCKET == socket_client)
{
	MessageBox(_T("create socket failing"), _T("create"));
	return FALSE;
}
//connet server
sockaddr_in addr;
memset(&addr, 0, sizeof(sockaddr_in));
addr.sin_family = AF_INET;
//addr.sin_port = htons(10000);
addr.sin_port = htons(4001);
//addr.sin_addr.S_un.S_addr = inet_addr("192.168.1.127");
char IP[20];
memset(IP, 0, 20);
GetPrivateProfileString("SET", "IP", "", IP, 20, "./IP.ini");
//addr.sin_addr.S_un.S_addr = inet_addr("192.168.1.49");
addr.sin_addr.S_un.S_addr = inet_addr(IP);
if (connect(socket_client, (sockaddr*)&addr, sizeof(sockaddr)))
{
	MessageBox(_T("connect server failed"), _T("connect"));
	return FALSE;
}

//在适当的位置向下发送数据
char send_flag[] = { 0xc0,0x03,0xc0 };
send(socket_client, send_flag, 3, NULL);