自学教程：C++ Listen函数代码示例

void main(){	CallDll();	SocketStartup();//startup the WSA	Listen();}

DWORD CTcpServerSocketHelper::Start(ITcpServerSocketHelper_Event *pEvent,									DWORD dwListenPort/*=0*/,BOOL bReadData/*=TRUE*/){	DWORD dwResult = -1;	DWORD threadID = 0;	m_pEvent = pEvent;	m_dwListenPort = dwListenPort;	if (!CreateTcpSocket(TRUE))	{		dwResult = 1;		goto Exit0;	}	BOOL bOpt = TRUE;	::setsockopt (m_Socket, SOL_SOCKET, SO_REUSEADDR, (const char*)&bOpt, sizeof (bOpt));	if (!Bind())	{		dwResult = 2;		goto Exit0;	}	if (!Listen())	{		dwResult = 3;		goto Exit0;	}	m_hTerminateAcceptThreadEvent = ::CreateEvent(NULL, TRUE, FALSE,NULL);	if (!m_hTerminateAcceptThreadEvent)	{		dwResult = 4;		goto Exit0;	}	m_hAcceptThreadHandle = (HANDLE)::CreateThread( NULL, 0, 		(LPTHREAD_START_ROUTINE)_AcceptThreadProc, this, 0, &threadID );	if (!m_hAcceptThreadHandle)	{		dwResult = 5;		goto Exit0;	}	if (bReadData)	{		m_hTerminateReadDataThreadEvent = ::CreateEvent(NULL, TRUE, FALSE,NULL);		if (!m_hTerminateReadDataThreadEvent)		{			dwResult = 6;			goto Exit0;		}		m_hReadDataThreadHandle = (HANDLE)::CreateThread( NULL, 0, 			(LPTHREAD_START_ROUTINE)_ReadDataThreadProc, this, 0, &threadID );		if (!m_hReadDataThreadHandle)		{			goto Exit0;		}	}	dwResult = 0;Exit0:	if (0 != dwResult)	{		Stop();	}	if (dwResult == 0)	{		return m_dwListenPort;	}	return (DWORD)-1;}

// MAINint main(int argc, char **argv) {   // Local variables   int pid;   int port;   int listenfd;   int connfd;   struct sockaddr_in clientAddr;   socklen_t clientSize = sizeof(clientAddr);   FILE* logFile;   // gets port number   if(argc == 2) {      port = atoi(argv[1]);   } else {      perror("Invalid arguments.");      exit(1);   }   // opens log file   logFile = fopen("log.txt", "a+");   // creates listen socket   listenfd = listenSocket(port);   // starts listening   Listen(listenfd, LISTENQUEUE);    for ( ; ; ) {      // accepts a connection      connfd = Accept(listenfd, (struct sockaddr *)&clientAddr, &clientSize);      // prints the info      PrintConnectionInfo(clientAddr);      // log      logConnection(logFile, clientAddr);      // fork      if((pid = fork()) == 0) {         // child process closes the listen socket         close(listenfd);                  // process         process(connfd, clientAddr);                  // child process closes the connection         close(connfd);          // prints info of disconnection         printDisconnectInfo(clientAddr);         // log         logDisconnection(logFile, clientAddr);         // finished execution         exit(0);       }      // parent process closes the connection with client      close(connfd);   }   // closes log file   fclose(logFile);   return(0);}

//!! textbook p146 ch 6.11 poll 模板intmain(int argc, char **argv){    int                 i, maxi, listenfd, connfd, sockfd;    int                 nready;    ssize_t             n;    char                buf[MAXLINE];    socklen_t           clilen;    struct pollfd       client[OPEN_MAX];    struct sockaddr_in  cliaddr, servaddr;    listenfd = Socket(AF_INET, SOCK_STREAM, 0);    bzero(&servaddr, sizeof(servaddr));    servaddr.sin_family      = AF_INET;    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);    servaddr.sin_port        = htons(SERV_PORT);    Bind(listenfd, (SA *) &servaddr, sizeof(servaddr));    Listen(listenfd, LISTENQ);    client[0].fd = listenfd;    client[0].events = POLLRDNORM;    for (i = 1; i < OPEN_MAX; i++)        client[i].fd = -1;      /* -1 indicates available entry */    maxi = 0;                   /* max index into client[] array *//* end fig01 *//* include fig02 */    for ( ; ; ) {        nready = Poll(client, maxi+1, INFTIM);        if (client[0].revents & POLLRDNORM) {   /* new client connection */            clilen = sizeof(cliaddr);            connfd = Accept(listenfd, (SA *) &cliaddr, &clilen);#ifdef  NOTDEF            printf("new client: %s/n", Sock_ntop((SA *) &cliaddr, clilen));#endif            for (i = 1; i < OPEN_MAX; i++)                if (client[i].fd < 0) {                    client[i].fd = connfd;  /* save descriptor */                    break;                }            if (i == OPEN_MAX)                err_quit("too many clients");            client[i].events = POLLRDNORM;            if (i > maxi)                maxi = i;               /* max index in client[] array */            if (--nready <= 0)                continue;               /* no more readable descriptors */        }        for (i = 1; i <= maxi; i++) {   /* check all clients for data */            if ( (sockfd = client[i].fd) < 0)                continue;            if (client[i].revents & (POLLRDNORM | POLLERR)) {                if ( (n = read(sockfd, buf, MAXLINE)) < 0) {                    if (errno == ECONNRESET) {                            /*4connection reset by client */#ifdef  NOTDEF                        printf("client[%d] aborted connection/n", i);#endif                        Close(sockfd);                        client[i].fd = -1;                    } else                        err_sys("read error");                } else if (n == 0) {                        /*4connection closed by client */#ifdef  NOTDEF                    printf("client[%d] closed connection/n", i);#endif                    Close(sockfd);                    client[i].fd = -1;                } else                    Writen(sockfd, buf, n);                if (--nready <= 0)                    break;              /* no more readable descriptors */            }        }    }}

// Management port Listen threadvoid NiListenThread(THREAD *thread, void *param){	NAT *n = (NAT *)param;	SOCK *a;	UINT i;	bool b = false;	// Validate arguments	if (thread == NULL || param == NULL)	{		return;	}	// Initialize the management list	n->AdminList = NewList(NULL);	while (true)	{		a = Listen(DEFAULT_NAT_ADMIN_PORT);		if (b == false)		{			b = true;			NoticeThreadInit(thread);		}		if (a != NULL)		{			break;		}		Wait(n->HaltEvent, NAT_ADMIN_PORT_LISTEN_INTERVAL);		if (n->Halt)		{			return;		}	}	n->AdminListenSock = a;	AddRef(a->ref);	// Waiting	while (true)	{		SOCK *s = Accept(a);		THREAD *t;		NAT_ADMIN *admin;		if (s == NULL)		{			break;		}		if (n->Halt)		{			ReleaseSock(s);			break;		}		admin = ZeroMalloc(sizeof(NAT_ADMIN));		admin->Nat = n;		admin->Sock = s;		t = NewThread(NiAdminThread, admin);		WaitThreadInit(t);		ReleaseThread(t);	}	// Disconnect all management connections	LockList(n->AdminList);	{		for (i = 0;i < LIST_NUM(n->AdminList);i++)		{			NAT_ADMIN *a = LIST_DATA(n->AdminList, i);			Disconnect(a->Sock);			WaitThread(a->Thread, INFINITE);			ReleaseThread(a->Thread);			ReleaseSock(a->Sock);			Free(a);		}	}	UnlockList(n->AdminList);	ReleaseList(n->AdminList);	ReleaseSock(a);}

int main(int argc, char **argv){    int i, maxi, listenfd, connfd, sockfd;	int nready;	ssize_t n;	char buf[MAXLINE];	socklen_t clilen;	struct pollfd client[OPEN_MAX];	struct sockaddr_in cliaddr, servaddr;	listenfd = Socket(AF_INET, SOCK_STREAM, 0);	bzero(&servaddr, sizeof(servaddr));	servaddr.sin_family = AF_INET;	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);	servaddr.sin_port = htons(SERV_PORT);	Bind(listenfd, (SA *)&servaddr, sizeof(servaddr));	Listen(listenfd, LISTENQ);	client[0].fd = listenfd;	client[0].events = POLLIN;	for (i = 1; i < OPEN_MAX; i++)		client[1].fd = -1;	maxi = 0;	for ( ; ; )	{		nready = Poll(client, maxi + 1, INFTIM);		if (client[0].revents & POLLIN)   /* new client connection */		{            clilen = sizeof(cliaddr);			connfd = Accept(listenfd, (SA *)&cliaddr, &clilen);			for (i = 1; i < OPEN_MAX; i++)				if (client[i].fd < 0)				{					client[i].fd = connfd;   /* save descriptor */					break;				}			if (i == OPEN_MAX)                err_quit("too many clients");            			client[i].events = POLLIN;			if (i > maxi)				maxi = i;   /* max index in client[] array */			if (--nready <= 0)				continue;   /* no more readable descriptors */		}		for (i = 1; i <= maxi; i++)   /* check all clients for data */		{            if ((sockfd = client[i].fd) < 0)				continue;			if (client[i].revents & (POLLIN | POLLERR))			{				if ((n = read(sockfd, buf, MAXLINE)) < 0)				{					if (errno == ECONNRESET)   /* connection reset by client */					{                        Close(sockfd);						client[i].fd = -1;					}					else						err_sys("read error");				}				else if (n == 0)   /* connection closed by client */				{					Close(sockfd);					client[i].fd = -1;				}				else				    Writen(sockfd, buf, n);				if (--nready <= 0)   /* no more readable descriptors */					break;			}		}	}}

/* We can write a simple version of a TCP daytime server, which will work * with the daytime client. * * TCP服务器端一般要执行的步骤是: socket()->填充结构体(协议类型,本机ip地址, * 本机端口)->bind()->listen()->accept()->使用连接描述符进行读写. * TCP客户端一般要执行的步骤是: socket()->填充结构体(协议类型,服务器ip地址, * 服务器已知端口)->connect() */int main(void){    int listenfd, connfd;    struct sockaddr_in servaddr;    char buf[BUFSIZ];    time_t ticks;    /* 1. Create a TCP socket */    listenfd = Socket(AF_INET, SOCK_STREAM, 0);    /* 2. Bind server's well-known port to socket     * The server's well-known port (13 for the daytime service) is bound     * to the socket by filling in an Internet socket address structure and     * calling bind(). We specify the IP address as INADDR_ANY, which allows     * the server to accept a client connection on any interface, in case     * the server host has multiple interfaces.     *     * 以普通用户运行该程序时,会报错: bind error: Permission denied     * 此时,错误码是EACCES. 查看man bind手册,对该错误码解释为:     * EACCES The address is protected, and the user is not the superuser.     *     * 在Linux中,只有 root 用户可以绑定 1024 以下的端口.     * 查看 man 7 ip 手册,里面有如下说明:     * The port numbers below 1024 are called privileged ports (or     * sometimes: reserved ports). Only privileged processes (i.e., those     * having the CAP_NET_BIND_SERVICE capability) may bind to these sockets     * 所以运行该程序时,要用root用户或者sudo命令来运行.     * 另外, 13 这个端口可能被占用导致绑定不成功. Linux下,查看端口是否被占     * 用的方法是: netstat -apn | grep <端口号>. 例如: netstat -apn|grep 13     */    memset(&servaddr, 0, sizeof(servaddr));    servaddr.sin_family = AF_INET;    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);    servaddr.sin_port = htons(13);    Bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));    /* 3. Convert socket to listening socket     * By calling listen(), the socket is converted into a listening socket,     * on which incomming connections from clients will be accepted by the     * kernel. These three steps, socket(), bind(), and listen(), are the     * normal steps for any TCP server to prepare what we call the listening     * descriptor (listenfd in this example).     */    Listen(listenfd, LISTENQ);    for (; ;) {        /* 4. Accept client connection, send reply         * Normally, the server process is put to sleep in the call to         * accept(), waiting for a client connection to arrive and be         * accepted. A TCP connection uses what is called a three-way         * handshake to establish a connection. When this handshake         * completes, accept() returns, and the return value from the         * function is a new descriptor (connfd) that is called the         * connected descriptor. This new descriptor is used for         * communication with the new client. A new descriptor is returned         * by accept() for each client that connects to our server.         */        connfd = Accept(listenfd, NULL, NULL);        /* The current time and date are returned by the library function         * time(), which returns the number of seconds since the Unix         * Eproch: 00:00:00 January 1, 1970, Coordinated Universal Time(UTC)         * The next library function, ctime(), converts this integer value         * into a human-readable string sush as: Mon May 26 20:58:40 2003         */        ticks = time(NULL);        snprintf(buf, sizeof(buf), "%.24s/r/n", ctime(&ticks));        Write(connfd, buf, strlen(buf));        /* 5. Terminate connection         * The server closes its connection with the client by calling         * close(). This initiates the normal TCP connection termination         * sequence: a FIN is sent in each direction and each FIN is         * acknowledged by the other end.         */        Close(connfd);    }    return 0;}

//bool CListenSocket::StartListening()//{//	bListening = true;////	// Creating the socket with SO_REUSEADDR may solve LowID issues if emule was restarted//	// quickly or started after a crash, but(!) it will also create another problem. If the//	// socket is already used by some other application (e.g. a 2nd emule), we though bind//	// to that socket leading to the situation that 2 applications are listening at the same//	// port!//	if (!Create(thePrefs.GetPort(), SOCK_STREAM, FD_ACCEPT, CT2CA(theApp.GetBindAddress()), FALSE/*bReuseAddr*/)) // Added by thilon on 2006.10.18, for [BindToAdapter]//		return false;////	// Rejecting a connection with conditional WSAAccept and not using SO_CONDITIONAL_ACCEPT//	// -------------------------------------------------------------------------------------//	// recv: SYN//	// send: SYN ACK (!)//	// recv: ACK//	// send: ACK RST//	// recv: PSH ACK + OP_HELLO packet//	// send: RST//	// --- 455 total bytes (depending on OP_HELLO packet)//	// In case SO_CONDITIONAL_ACCEPT is not used, the TCP/IP stack establishes the connection//	// before WSAAccept has a chance to reject it. That's why the remote peer starts to send//	// it's first data packet.//	// ---//	// Not using SO_CONDITIONAL_ACCEPT gives us 6 TCP packets and the OP_HELLO data. We//	// have to lookup the IP only 1 time. This is still way less traffic than rejecting the//	// connection by closing it after the 'Accept'.////	// Rejecting a connection with conditional WSAAccept and using SO_CONDITIONAL_ACCEPT//	// ---------------------------------------------------------------------------------//	// recv: SYN//	// send: ACK RST//	// recv: SYN//	// send: ACK RST//	// recv: SYN//	// send: ACK RST//	// --- 348 total bytes//	// The TCP/IP stack tries to establish the connection 3 times until it gives up. //	// Furthermore the remote peer experiences a total timeout of ~ 1 minute which is//	// supposed to be the default TCP/IP connection timeout (as noted in MSDN).//	// ---//	// Although we get a total of 6 TCP packets in case of using SO_CONDITIONAL_ACCEPT,//	// it's still less than not using SO_CONDITIONAL_ACCEPT. But, we have to lookup//	// the IP 3 times instead of 1 time.////	//if (thePrefs.GetConditionalTCPAccept() && !thePrefs.GetProxySettings().UseProxy) {//	//	int iOptVal = 1;//	//	VERIFY( SetSockOpt(SO_CONDITIONAL_ACCEPT, &iOptVal, sizeof iOptVal) );//	//}////	if (!Listen())//		return false;////	m_port = thePrefs.GetPort();////	//// Added by thilon on 2006.10.19, for IFWS - [ICSFirewall]//	//if(thePrefs.GetICFSupport())//	//{//	//	bool bResult = (theApp.m_pFirewallOpener->OpenPort(m_port, NAT_PROTOCOL_TCP, EMULE_DEFAULTRULENAME_TCP, thePrefs.GetICFClearOnClose() /*|| thePrefs.GetUseRandomPorts()*/));//	//	theApp.QueueLogLine(false, GetResString(bResult ? IDS_FO_TEMPTCP_S : IDS_FO_TEMPTCP_F), m_port);//	//}////	if(mapping)//	{//		theApp.RemoveUPnPNatPort(mapping);//	}////	if(thePrefs.GetUPnPNat())//	{//		mapping = new CUPnP::UPNPNAT_MAPPING;//		mapping->ref = &mapping;////		mapping->internalPort = mapping->externalPort = thePrefs.GetPort();//		mapping->protocol = CUPnP::UNAT_TCP;//		mapping->description = "TCP Port";//		if(theApp.AddUPnPNatPort(mapping, thePrefs.GetUPnPNatTryRandom()))//			thePrefs.SetUPnPTCPExternal(mapping->externalPort);//	}//	/*else//	{//		thePrefs.SetUPnPTCPExternal(thePrefs.GetPort());//	}*/////	bListening = true;//	return true;//}//upnp_endbool CListenSocket::StartListening(){	//ADDED by fengwen on 2007/03/21	<begin> :	
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