简单网络编程--TCP SERVER 端

一个服务器，接受客户连接，返回客户IP地址，并关闭连接。

一个服务器程序的基本步骤：

1. winsock library 的初始化

2. 创建socket

3. 服务器地址

4. bind->listen

5. 等待客户连接 accept

6. 处理客户接入

7. 关闭 socket

8. 释放资源：winsock library

// SimpleTcpServer.cpp : Defines the entry point for the console application.

//

#include
"stdafx.h"

#include
<winsock2.h>

#pragma comment(lib,
"ws2_32"
)

#include
"SimpleTcpServer.h"

#include
<conio.h>

#ifdef _DEBUG

#define
new

DEBUG_NEW

#undef THIS_FILE

static

char

THIS_FILE[] = __FILE__
;

#endif

/////////////////////////////////////////////////////////////////////////////

// The one and only application object

//z 2011-05-22 21:23:03@is2120

CWinApp theApp;

using

namespace

std;

UINT  ServerThread(LPVOID pParam);

int

_tmain(int

argc, TCHAR* argv[], TCHAR* envp[])

{

int

nRetCode = 0
;

// initialize MFC and print and error on failure

if
(!AfxWinInit(::GetModuleHandle(NULL
), NULL
, ::GetCommandLine(), 0
))

{

//
TODO

: change error code to suit your needs

cerr << _T("Fatal Error: MFC initialization failed"
) << endl;

nRetCode = 1
;

}

else

{

//
TODO

: code your application's behavior here.

/*

CString strHello;

strHello.LoadString(IDS_HELLO);

cout << (LPCTSTR)strHello << endl;

*/

int

nRetCode = 0
;

cout << "Press ESCAPE to terminate program
/r/n
"
;

AfxBeginThread(ServerThread,0
);

while
(_getch()!=27
);

return

nRetCode;

}

return

nRetCode;

}

UINT  ServerThread(LPVOID pParam)

{

cout << "Starting up TCP server
/r/n
"
;

//A SOCKET is simply a typedef for an unsigned int.

//In Unix, socket handles were just about same as file

//handles which were again unsigned ints.

//Since this cannot be entirely true under Windows

//a new data type called SOCKET was defined.

SOCKET server;

//WSADATA is a struct that is filled up by the call

//to WSAStartup

WSADATA wsaData;

//The sockaddr_in specifies the address of the socket

//for TCP/IP sockets. Other protocols use similar structures.

sockaddr_in local;

//WSAStartup initializes the program for calling WinSock.

//The first parameter specifies the highest version of the

//WinSock specification, the program is allowed to use.

int

wsaret=WSAStartup(0x101
,&wsaData);

//WSAStartup returns zero on success.

//If it fails we exit.

if
(wsaret!=0
)

{

return

0
;

}

//Now we populate the sockaddr_in structure

local.sin_family=AF_INET; //Address family

local.sin_addr.s_addr=INADDR_ANY; //Wild card IP address

local.sin_port=htons((u_short)20248
); //port to use

//the socket function creates our SOCKET

server=socket(AF_INET,SOCK_STREAM,0
);

//If the socket() function fails we exit

if
(server==INVALID_SOCKET)

{

return

0
;

}

//bind links the socket we just created with the sockaddr_in

//structure. Basically it connects the socket with

//the local address and a specified port.

//If it returns non-zero quit, as this indicates error

if
(bind(server,(sockaddr*)&local,sizeof
(local))!=0
)

{

return

0
;

}

//listen instructs the socket to listen for incoming

//connections from clients. The second arg is the backlog

if
(listen(server,10
)!=0
)

{

return

0
;

}

//we will need variables to hold the client socket.

//thus we declare them here.

SOCKET client;

sockaddr_in from;

int

fromlen=sizeof
(from);

while
(true
)//we are looping endlessly

{

char

temp[512
];

//accept() will accept an incoming

//client connection

client=accept(server,

(struct

sockaddr*)&from,&fromlen);

sprintf(temp,"Your IP is
%s
/r/n
"
,inet_ntoa(from.sin_addr));

//we simply send this string to the client

send(client,temp,strlen(temp),0
);

cout << "Connection from "
<< inet_ntoa(from.sin_addr) <<"
/r/n
"
;

//close the client socket

closesocket(client);

}

//closesocket() closes the socket and releases the socket descriptor

closesocket(server);

//originally this function probably had some use

//currently this is just for backward compatibility

//but it is safer to call it as I still believe some

//implementations use this to terminate use of WS2_32.DLL

WSACleanup();

return

0
;

}