Socket编程-----基础

Socket的概念：

Socket，即套接字，用于描述地址和端口，是一个通信链的句柄。

应用程序通过Socket像网络发出请求或者回应。

什么事客户/服务器模式：

在TCP/IP网络应用中，通信的两个进程相互作用的主要模式是客户/服务器模式，即客户端向服务器发出请求，服务器接收请求后，提供相应的服务。客户/服务器模式的建立基于以下两点：

1：建立网络的起因是网络中软硬件资源、运算能力和信息不均等，需要共享，从而造就拥有众多资源的主机提供服务，资源较少的客户请求服务这一非对等作用

2：网间进程通信完全是异步的，相互通信的进程间既不存在父子关系，又不共享内存缓冲区

因此需要一种机制为希望通信的进程间建立联系，为二者的数据交换提供同步，这就是基于客户/服务端模式的TCP/IP

（这部分内容摘自socket编程原理）

需要做什么：

客户端：建立Socket，通过端口号和地址确定目标服务器，使用Connect连接到服务器，send发送消息，等待处理，通信完成后调用CloseSocket关闭Socket

服务端：建立Socket，声明自身的端口号和地址并绑定到Socket，使用Listen打开监听，然后不断用Accept去查看是否有连接，如果有，捕获Socket，并通过Recv获取消息的内容，通信完成后调用CloseSocket关闭这个对应Accept到的Socket，如果不再需要等待任何客户端连接，那么用CloseSocket关闭掉自身的Socket

代码示例

客户端：这里创建一个CLientNet类，用于表示一个客户

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#pragma once /* ClinetNet.h： 用于表示一个客户的网络操作 */ #include <stdio.h> #include<windows.h> #pragma comment(lib, "Ws2_32.lib") class CClientNet { public: //连接上指定服务器 int Connect(int port,const char* address); //发送信息 int SendMsg(const char* msg,int len); //关闭 void Close(); private: SOCKET m_sock; };

#pragma once

/*
ClinetNet.h：
用于表示一个客户的网络操作
*/

#include <stdio.h>
#include<windows.h>

#pragma comment(lib, "Ws2_32.lib")

class CClientNet
{
public:
//连接上指定服务器
int Connect(int port,const char* address);
//发送信息
int SendMsg(const char* msg,int len);
//关闭
void Close();

private:
SOCKET m_sock;
};

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/* CLientNet.cpp */ #include "ClientNet.h" int CClientNet::Connect( int port,const char* address ) { int rlt = 0; //用于记录错误信息并输出 int iErrMsg; //启动WinSock WSAData wsaData; iErrMsg = WSAStartup(MAKEWORD(1,1),&wsaData); if (iErrMsg != NO_ERROR) //有错误 { printf("failed with wsaStartup error : %d\n",iErrMsg); rlt = 1; return rlt; } //创建Socket m_sock = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); if (m_sock == INVALID_SOCKET) //创建Socket失败 { printf("socket failed with error : %d\n",WSAGetLastError()); rlt = 2; return rlt; } //目标服务器数据 sockaddr_in sockaddrServer; sockaddrServer.sin_family = AF_INET; sockaddrServer.sin_port = port; sockaddrServer.sin_addr.s_addr = inet_addr(address); //连接,sock与目标服务器连接 iErrMsg = connect(m_sock,(sockaddr*)&sockaddrServer,sizeof(sockaddrServer)); if (iErrMsg < 0) { printf("connect failed with error : %d\n",iErrMsg); rlt = 3; return rlt; } return rlt; } int CClientNet::SendMsg(const char* msg,int len) { int rlt = 0; int iErrMsg = 0; //发送消息，指定sock发送消息 iErrMsg = send(m_sock,msg,len,0); if (iErrMsg < 0) //发送失败 { printf("send msg failed with error : %d\n",iErrMsg); rlt = 1; return rlt; } return rlt; } void CClientNet::Close() { closesocket(m_sock); }

/*
CLientNet.cpp
*/
#include "ClientNet.h"

int CClientNet::Connect( int port,const char* address )
{
int rlt = 0;

//用于记录错误信息并输出
int iErrMsg;
//启动WinSock
WSAData wsaData;
iErrMsg = WSAStartup(MAKEWORD(1,1),&wsaData);
if (iErrMsg != NO_ERROR)
//有错误
{
printf("failed with wsaStartup error : %d\n",iErrMsg);

rlt = 1;
return rlt;
}

//创建Socket
m_sock = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if (m_sock == INVALID_SOCKET)
//创建Socket失败
{
printf("socket failed with error : %d\n",WSAGetLastError());

rlt = 2;
return rlt;
}

//目标服务器数据
sockaddr_in sockaddrServer;
sockaddrServer.sin_family = AF_INET;
sockaddrServer.sin_port = port;
sockaddrServer.sin_addr.s_addr = inet_addr(address);

//连接,sock与目标服务器连接
iErrMsg = connect(m_sock,(sockaddr*)&sockaddrServer,sizeof(sockaddrServer));
if (iErrMsg < 0)
{
printf("connect failed with error : %d\n",iErrMsg);

rlt = 3;
return rlt;
}

return rlt;
}

int CClientNet::SendMsg(const char* msg,int len)
{
int rlt = 0;

int iErrMsg = 0;

//发送消息，指定sock发送消息
iErrMsg = send(m_sock,msg,len,0);
if (iErrMsg < 0)
//发送失败
{
printf("send msg failed with error : %d\n",iErrMsg);

rlt = 1;
return rlt;
}

return rlt;
}

void CClientNet::Close()
{
closesocket(m_sock);
}

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#include "ClientNet.h"

void main()
{
CClientNet client;

//连接到127.0.0.1（即本地）,端口号为8888的服务端

printf("Connect\n");
client.Connect(8888,"127.0.0.1");

//发送消息
printf("send msg\n");
client.SendMsg("hello\0",sizeof("hello\0"));

//关闭socket
printf("close\n");
client.Close();

system("pause");
}

#include "ClientNet.h"

void main()
{
CClientNet client;

//连接到127.0.0.1（即本地）,端口号为8888的服务端
printf("Connect\n");
client.Connect(8888,"127.0.0.1");

//发送消息
printf("send msg\n");
client.SendMsg("hello\0",sizeof("hello\0"));

//关闭socket
printf("close\n");
client.Close();

system("pause");
}

服务端代码：

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#pragma once /* ServerNet.h 用于表示服务端的网络操作 */ #include <stdio.h> #include <winsock.h> #pragma comment (lib,"ws2_32.lib") class CServerNet { public: //初始化服务器,返回0表示成功 int Init(const char* address,int port); //更新数据 void Run(); private: SOCKET m_sock; };

#pragma once

/*
ServerNet.h
用于表示服务端的网络操作

*/

#include <stdio.h>
#include <winsock.h>

#pragma comment (lib,"ws2_32.lib")

class CServerNet
{
public:

//初始化服务器,返回0表示成功
int Init(const char* address,int port);

//更新数据
void Run();

private:
SOCKET m_sock;
};

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/*
ServerNet.cpp
*/
#include "ServerNet.h"

int CServerNet::Init( const char* address,int port )
{
int rlt = 0;

//用于记录错误信息，并输出
int iErrorMsg;

//初始化WinSock
WSAData wsaData;
iErrorMsg = WSAStartup(MAKEWORD(1,1),&wsaData);

if (iErrorMsg != NO_ERROR)
{
//初始化WinSock失败
printf("wsastartup failed with error : %d\n",iErrorMsg);

rlt = 1;
return rlt;
}

//创建服务端Socket
m_sock = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if (m_sock == INVALID_SOCKET)

{
//创建Socket异常
printf("socket failed with error : %d\n",WSAGetLastError());

rlt = 2;
return rlt;
}

//声明信息
sockaddr_in serverAddr;
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = port;
serverAddr.sin_addr.s_addr = inet_addr(address);

//绑定
iErrorMsg = bind(m_sock,(sockaddr*)&serverAddr,sizeof(serverAddr));
if (iErrorMsg < 0)
{
//绑定失败
printf("bind failed with error : %d\n",iErrorMsg);
rlt = 3;
return rlt;
}

return rlt;
}

void CServerNet::Run()
{
//公开连接
listen(m_sock,5);

sockaddr_in tcpAddr;
int len = sizeof(sockaddr);
SOCKET newSocket;
char buf[1024];
int rval;

do
{
//接收信息
newSocket = accept(m_sock,(sockaddr*)&tcpAddr,&len);

if (newSocket == INVALID_SOCKET)
{
//非可用socket

}
else
{
//新socket连接
printf("new socket connect : %d\n",newSocket);

//消息处理
do
{
printf("process\n");
//接收数据
memset(buf,0,sizeof(buf));
rval = recv(newSocket,buf,1024,0);

if (rval == SOCKET_ERROR)
//这应该是个异常，当客户端没有调用closeSocket就直接退出游戏的时候，将会进入这里

printf("recv socket error\n");

if (rval == 0)
//recv返回0表示正常退出

printf("ending connection");
else
//显示接收到的数据
printf("recv %s\n",buf);

}while(rval != 0);

//关闭对应Accept的socket
closesocket(newSocket);
}

} while (1);

//关闭自身的Socket
closesocket(m_sock);
}

/*
ServerNet.cpp
*/
#include "ServerNet.h"

int CServerNet::Init( const char* address,int port )
{
int rlt = 0;

//用于记录错误信息，并输出
int iErrorMsg;

//初始化WinSock
WSAData wsaData;
iErrorMsg = WSAStartup(MAKEWORD(1,1),&wsaData);

if (iErrorMsg != NO_ERROR)
{
//初始化WinSock失败
printf("wsastartup failed with error : %d\n",iErrorMsg);

rlt = 1;
return rlt;
}

//创建服务端Socket
m_sock = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if (m_sock == INVALID_SOCKET)

{
//创建Socket异常
printf("socket failed with error : %d\n",WSAGetLastError());

rlt = 2;
return rlt;
}

//声明信息
sockaddr_in serverAddr;
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = port;
serverAddr.sin_addr.s_addr = inet_addr(address);

//绑定
iErrorMsg = bind(m_sock,(sockaddr*)&serverAddr,sizeof(serverAddr));
if (iErrorMsg < 0)
{
//绑定失败
printf("bind failed with error : %d\n",iErrorMsg);
rlt = 3;
return rlt;
}

return rlt;
}

void CServerNet::Run()
{
//公开连接
listen(m_sock,5);

sockaddr_in tcpAddr;
int len = sizeof(sockaddr);
SOCKET newSocket;
char buf[1024];
int rval;

do
{
//接收信息
newSocket = accept(m_sock,(sockaddr*)&tcpAddr,&len);

if (newSocket == INVALID_SOCKET)
{
//非可用socket

}
else
{
//新socket连接
printf("new socket connect : %d\n",newSocket);

//消息处理
do
{
printf("process\n");
//接收数据
memset(buf,0,sizeof(buf));
rval = recv(newSocket,buf,1024,0);

if (rval == SOCKET_ERROR)
//这应该是个异常，当客户端没有调用closeSocket就直接退出游戏的时候，将会进入这里
printf("recv socket error\n");

if (rval == 0)
//recv返回0表示正常退出
printf("ending connection");
else
//显示接收到的数据
printf("recv %s\n",buf);

}while(rval != 0);

//关闭对应Accept的socket
closesocket(newSocket);
}

} while (1);

//关闭自身的Socket
closesocket(m_sock);
}

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#include "ServerNet.h" int main(int argc, char **argv) { CServerNet serverNet; int iRlt = serverNet.Init("127.0.0.1",8888); if (iRlt == 0) { printf("init ok...\n"); serverNet.Run(); } else printf("serverNet init failed with error : %d\n",iRlt); system("pause"); }

#include "ServerNet.h"

int main(int argc, char **argv)
{
CServerNet serverNet;
int iRlt = serverNet.Init("127.0.0.1",8888);
if (iRlt == 0)
{
printf("init ok...\n");
serverNet.Run();
}
else
printf("serverNet init failed with error : %d\n",iRlt);
system("pause");
}