基于socket的简单网络程序设计

基于socket的简单网络程序设计

1、实验目的与要求：

（1）初步掌握TCP和UDP方式的网络编程模式。

（2）能运用Winsock提供的API函数接口进行网络程序的编写。

2、实验准备和说明：

（1）要求掌握流式和数据报socket的编程模式和实现。

（2）创建本次实验工作文件夹“…\实验\实验4”。

3、实验内容与步骤：

      1）工程的创建

在VC6里边新建一个工程，选择：Win32
Console Application，输入工程名。具体方法：启动VC6.0，进入【文件】->【新建】，然后在【新建工程】的对话框中选择：Win32
Console Application，输入一个工程名ntTcpClient及保存路径“…\实验\实验4”，点击【确定】

2）Winsock的初始化

在Windows环境下进行网络程序设计时，所有的Winsock函数都是从ws2_32.dll导出的，我们可以通过#pragma
comment(lib, "ws2_32.lib")语句链接到该库文件。但在使用Winsock函数之前还必须调用WSAStartup函数对库资源进行初始化工作，使用完毕后，在退出程序之前，我们还必须调用WSACleanup函数来释放库资源。

3）新建文件ntTcpClient.cpp

<span style="font-size:18px;">#include <stdio.h>
#include <stdlib.h>
#include "winsock2.h"

//winsock 2.2 library
#pragma comment(lib,"ws2_32.lib")

#define PORT  8888
#define ADDR  "127.0.0.1"

int main(int argc, char* argv[])
{
WSADATA	wsock;
SOCKET sconnection;
SOCKADDR_IN          serAddr;
int                  nRet=0;
char                 buf[100];

//初始化Winsock 2.2

printf("\nInitialising Winsock...\n");
if (WSAStartup(MAKEWORD(2,2),&wsock) != 0)
{
fprintf(stderr,"WSAStartup() failed %d\n, WSAGetLastError()");
exit(0);
}
printf("Initialised successfully.\n");

//创建监听Socket
printf("\nCreating TCP Socket...\n");
if ((sconnection = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP))
== INVALID_SOCKET)
{
printf("Creation of socket failed %d\n", WSAGetLastError());
WSACleanup();
return 0;
}
printf("TCP Socket Created successfully.\n");
//设置OCKADDR_IN地址结构
serAddr.sin_family = AF_INET;
serAddr.sin_port = htons(PORT);
//serAddr.sin_addr.s_addr = INADDR_ANY;
serAddr.sin_addr.s_addr = inet_addr(ADDR);
//连接服务端
printf("Connecting to %s:%d...\n",
inet_ntoa(serAddr.sin_addr), htons(serAddr.sin_port));
if (connect(sconnection, (SOCKADDR *) &serAddr, sizeof(serAddr))
== SOCKET_ERROR)
{
printf("connection failed with error %d\n", WSAGetLastError());
closesocket(sconnection);
WSACleanup();
return 0;
}
printf("connection successfully.\n");
printf("Trying to send  messages.\n");
//收发处理
for(int i=0;;i++)
{
memset(buf,0,sizeof(buf));
printf("\nMessage to be sent:");
gets(buf);
if ((nRet = send(sconnection, buf, strlen(buf), 0)) == SOCKET_ERROR)
{
printf("send failed with error %d\n", WSAGetLastError());
closesocket(sconnection);
WSACleanup();
return 0;
}

printf("The  data  was sent to %s successfully.\n",inet_ntoa(serAddr.sin_addr));
if(strncmp(buf,"exit",sizeof("exit"))==0)
break;
memset(buf,0,sizeof(buf));

if ((nRet = recv(sconnection, buf, sizeof(buf), 0))
== SOCKET_ERROR)
{
printf("recv failed with error %d\n", WSAGetLastError());
}
printf("The following data  was received from %s successfully.\n",
inet_ntoa(serAddr.sin_addr));
printf(buf);
}
printf("Closing the connection.\n");

closesocket(sconnection);
WSACleanup();

return 0;
}
</span>

4）编译运行

5）重建工程ntTcpServer

#include "stdafx.h"
#include <stdlib.h>
#include "winsock2.h"

//winsock 2.2 library
#pragma comment(lib,"ws2_32.lib")

#define PORT 8888
#define ADDR "127.0.0.1"

int main(int argc, char* argv[])
{
WSADATA wsock;
SOCKET listensocket,newconnection;
SOCKADDR_IN serAddr,cliAddr;
int cliAddrLen=sizeof(cliAddr);
int nRet=0;
char buf[100];

//初始化Winsock 2.2
printf("\nInitialising Winsock...\n");
if (WSAStartup(MAKEWORD(2,2),&wsock) != 0)
{
fprintf(stderr,"WSAStartup() failed %d\n, WSAGetLastError()");
exit(0);
}
printf("Initialised successfully.\n");

//创建监听Socket
printf("\nCreating TCP Socket...\n");
if ((listensocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP))
== INVALID_SOCKET)
{
printf("Creation of socket failed %d\n", WSAGetLastError());
WSACleanup();
return 0;
}
printf("TCP Socket Created successfully.\n");
//设置SOCKADDR_IN地址结构
serAddr.sin_family = AF_INET;
serAddr.sin_port = htons(PORT);
// serAddr.sin_addr.s_addr = INADDR_ANY;
serAddr.sin_addr.s_addr = inet_addr(ADDR);
//绑定套接字
if (bind(listensocket, (SOCKADDR *)&serAddr,
sizeof(serAddr))== SOCKET_ERROR)
{
printf("bind failed with error %d\n", WSAGetLastError());
closesocket(listensocket);
WSACleanup();
return 0;
}

//监听连接
if (listen(listensocket, 5) == SOCKET_ERROR)
{
printf("listen failed with error %d\n", WSAGetLastError());
closesocket(listensocket);
WSACleanup();
return 0;
}

printf("Waiting for a connection on port %d.\n", PORT);

//接受连接
if ((newconnection = accept(listensocket, (SOCKADDR *) &cliAddr,
&cliAddrLen)) == INVALID_SOCKET)
{
printf("accept failed with error %d\n", WSAGetLastError());
closesocket(listensocket);
WSACleanup();
return 0;
}

printf("successfully got a connection from %s:%d.\n",
inet_ntoa(cliAddr.sin_addr), ntohs(cliAddr.sin_port));

//此时可以继续监听新的连接，或者停止监听进行数据收发
closesocket(listensocket);

printf("Waiting to receive data...\n");

memset(buf,0,sizeof(buf));
for(int i=0;;i++)
{
if ((nRet = recv(newconnection, buf, sizeof(buf), 0))
== SOCKET_ERROR)
{
printf("recv failed with error %d\n", WSAGetLastError());
closesocket(newconnection);
WSACleanup();
return 0;
}
//显示接收到的数据
printf(buf);
printf("\n");
//若发现exit，则退出处理循环
if(strncmp(buf,"exit",sizeof("exit"))==0)
{
printf("exit the receiving loop\n");
break;
}
if((nRet = send(newconnection,buf,strlen(buf),0))
==SOCKET_ERROR)
{
printf("send failed with error %d\n", WSAGetLastError());
}
}
//关闭已连接套接字
closesocket(newconnection);

WSACleanup();
return 0;
}


6）编译运行，并尝试nTcpServer与nTcpClient进行通信

7）创建工程nUdpClient与nUdpServer

//nUdpServer代码
#include <stdio.h>

#include "winsock2.h"

//winsock 2.2 library
#pragma comment(lib,"ws2_32.lib")

#define PORT 8888
#define ADDR "127.0.0.1"

int main(int argc, char* argv[])
{
WSADATA wsock;
SOCKET sersocket;
SOCKADDR_IN serAddr;
int serAddrsize=sizeof(serAddr);
int nRet=0;
char buf[1024];

//初始化Winsock 2.2
printf("\nInitialising Winsock...\n");
if (WSAStartup(MAKEWORD(2,2),&wsock) != 0)
{
fprintf(stderr,"WSAStartup() failed %d\n, WSAGetLastError()");
exit(0);
}
printf("Initialised successfully.\n");

//创建socket
printf("\nCreating UDP Socket...\n");
if ((sersocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))
== INVALID_SOCKET)
{
printf("Creation of socket failed %d\n", WSAGetLastError());
WSACleanup();
return 0;
}

printf("UDP Socket Created successfully.\n");

//设置SOCKADDR_IN地址结构
serAddr.sin_family = AF_INET;
serAddr.sin_port = htons(PORT);
// serAddr.sin_addr.s_addr = INADDR_ANY;
serAddr.sin_addr.s_addr = inet_addr(ADDR);
//绑定套接字
if (bind(sersocket, (SOCKADDR *)&serAddr,
sizeof(serAddr))== SOCKET_ERROR)
{
printf("bind failed with error %d\n", WSAGetLastError());
closesocket(sersocket);
WSACleanup();
return 0;
}

printf("Waiting to receive data...\n");

for(int i=0;;i++)
{
if ((nRet = recvfrom(sersocket, buf, sizeof(buf), 0,
(SOCKADDR *)&serAddr, &serAddrsize)) == SOCKET_ERROR)
{
printf("ERROR: recvfrom failed with error %d\n", WSAGetLastError());
closesocket(sersocket);
WSACleanup();
return 0;
}
//显示接收到的数据
printf(buf);
printf("\n");
if ((nRet = sendto(sersocket, buf, strlen(buf), 0,
(SOCKADDR *)&serAddr, sizeof(serAddr))) == SOCKET_ERROR)
{
printf("ERROR: sendto failed with error %d\n", WSAGetLastError());
closesocket(sersocket);
WSACleanup();
return 0;
}

//若发现”exit”，则退出处理循环
if(strncmp(buf,"exit",sizeof("exit"))==0)
{
printf("exit the receiving loop\n");
break;
}
}

//关闭套接字
closesocket(sersocket);

WSACleanup();
return 0;
}

//nUdpClient代码
#include <stdio.h>
#include "winsock2.h"

//winsock 2.2 library
#pragma comment(lib,"ws2_32.lib")

#define PORT  8888
#define ADDR  "127.0.0.1"

int main(int argc, char* argv[])
{
WSADATA	wsock;
SOCKET clisocket;
SOCKADDR_IN  serAddr;
int   serAddrsize=sizeof(serAddr);
int   nRet=0;
char  buf[1024];

//初始化Winsock 2.2
printf("\nInitialising Winsock...\n");
if (WSAStartup(MAKEWORD(2,2),&wsock) != 0)
{
fprintf(stderr,"WSAStartup() failed %d\n, WSAGetLastError()");
exit(0);
}
printf("Initialised successfully.\n");

//创建socket
printf("\nCreating UDP Socket...\n");
if ((clisocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))
== INVALID_SOCKET)
{
printf("Creation of socket failed %d\n", WSAGetLastError());
WSACleanup();
return 0;
}

//设置SOCKADDR_IN地址结构
serAddr.sin_family = AF_INET;
serAddr.sin_port = htons(PORT);
//   serAddr.sin_addr.s_addr = INADDR_ANY;
serAddr.sin_addr.s_addr = inet_addr(ADDR);

printf("UDP Socket Created successfully.\n");

printf("Trying to send  messages.\n");
for(int i=0;;i++)
{
memset(buf,0,sizeof(buf));
printf("\nMessage to be sent:");
gets(buf);
if ((nRet = sendto(clisocket, buf,strlen(buf), 0,
(SOCKADDR *)&serAddr, sizeof(serAddr))) == SOCKET_ERROR)
{
printf("ERROR: sendto failed with error %d\n", WSAGetLastError());
closesocket(clisocket);
WSACleanup();
return 0;
}
printf("The  data  was sent to %s successfully.\n",inet_ntoa(serAddr.sin_addr));
if(strncmp(buf,"exit",sizeof("exit"))==0)
break;
memset(buf,0,sizeof(buf));

if ((nRet = recvfrom(clisocket, buf, sizeof(buf), 0,
(SOCKADDR *)&serAddr, &serAddrsize)) == SOCKET_ERROR)
{
printf("ERROR: recvfrom failed with error %d\n", WSAGetLastError());
closesocket(clisocket);
WSACleanup();
return 0;
}
//显示接收到的数据
printf("The following data  was received from %s successfully.\n",
inet_ntoa(serAddr.sin_addr));
printf(buf);
}

closesocket(clisocket);
WSACleanup();
return 0;
}

8）编译运行nUdpClient与nUdpServer，并尝试在它们之间进行通信