Winsock2 – 如何在客户端使用IOCP

我最近开始在Windows上学习IOCP，并阅读以下文章：

http://www.codeproject.com/Tips/95363/Another-TCP-echo-server-using-IOCP

您可以从以下位置下载该文章的示例：

http://dl.dropbox.com/u/281215/documentation/iocp-1.00.html

该示例包含两个简单的应用程序 – iocp_echo_server和TcpEchoClient 。

我知道IOCP通常用在客户端/服务器模型的服务器端，但是我想用IOCP创build一个客户端。

到目前为止，我已经尝试修改上面的客户端示例，以便每当服务器向客户端发送响应时，它都会自动拾取，但不起作用。

我已经离开了iocp_echo_server.c。 我的修改版本的TcpEchoClient.c如下所示：

//TcpEchoClient.c - a minimalistic echo client // ----------------------------------------------------------------------------- // C language includes #include <stdio.h> #include <winsock2.h> #include "mswsock.h" // for AcceptEx #include <stdlib.h> // exit #include <string.h> // Windows includes #include <windows.h> #pragma warning(disable: 4996) // sprintf // ----------------------------------------------------------------------------- // configuration enum { BUFLEN = 1000, SERVICE_PORT = 4000, SERVER_ADDRESS = INADDR_LOOPBACK }; enum // socket operations { OP_NONE, OP_ACCEPT, OP_READ, OP_WRITE }; typedef struct _SocketState // socket state & control { char operation; SOCKET socket; DWORD length; char buf[1024]; } SocketState; // variables static HANDLE cpl_port; static SOCKET sock; static SocketState sock_state; static WSAOVERLAPPED sock_ovl; static LPFN_ACCEPTEX pfAcceptEx; static GUID GuidAcceptEx = WSAID_ACCEPTEX; static int msgNumber; static char msgBuf[BUFLEN]; static struct sockaddr_in sin; // prototypes static void createConnection(void); static void createSocket(void); static void init(void); static void initWinsock(void); static void prepareEndpoint(void); static void recvBuffer(void); static void run(void); static void sendBuffer(void); static SOCKET create_accepting_socket(void); static void create_io_completion_port(void); static BOOL get_completion_status(DWORD*, SocketState**,WSAOVERLAPPED**); // ----------------------------------------------------------------------------- void main(void) { init(); run(); } // ----------------------------------------------------------------------------- static void createConnection(void) { printf("* connecting\n"); if (WSAConnect(sock, (LPSOCKADDR)&sin, sizeof(sin), NULL, NULL, NULL, NULL) == SOCKET_ERROR) { int err = WSAGetLastError(); printf("* error %d in connect\n", err); exit(1); } printf("* connected\n"); } // ----------------------------------------------------------------------------- static void createSocket(void) { sock = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED); if (sock == INVALID_SOCKET) { int err = WSAGetLastError(); printf("* error %d creating socket\n", err); exit(1); } // for use by AcceptEx sock_state.socket = 0; // to be updated later sock_state.operation = OP_ACCEPT; if (CreateIoCompletionPort((HANDLE)sock, cpl_port, (ULONG_PTR)&sock_state, 0) != cpl_port) { int err = WSAGetLastError(); printf("* error %d in listener\n", err); exit(1); } } // ----------------------------------------------------------------------------- static void init(void) { initWinsock(); create_io_completion_port(); createSocket(); prepareEndpoint(); createConnection(); } // ----------------------------------------------------------------------------- static void initWinsock(void) { WSADATA wsaData; if (WSAStartup(0x202, &wsaData) == SOCKET_ERROR) { int err = WSAGetLastError(); printf("* error %d in WSAStartup\n", err); exit(1); } } // ----------------------------------------------------------------------------- static void prepareEndpoint(void) { sin.sin_family = AF_INET; sin.sin_addr.s_addr = htonl(SERVER_ADDRESS); sin.sin_port = htons(SERVICE_PORT); // bind_listening_socket() { //if (bind(sock, (SOCKADDR*)&sin, sizeof(sin)) == SOCKET_ERROR) //{ // printf("* error in bind!\n"); // exit(1); //} } // start_listening() { //if (listen(sock, 100) == SOCKET_ERROR) //{ // printf("* error in listen!\n"); // exit(1); //} //printf("* started listening for connection requests...\n"); } // load_accept_ex() { //DWORD dwBytes; // black magic for me!!! // You do not need to call in your code WSAIoctl. You can directly use AcceptEx and adds Mswsock.lib. //WSAIoctl(sock, SIO_GET_EXTENSION_FUNCTION_POINTER, &GuidAcceptEx, sizeof(GuidAcceptEx), &pfAcceptEx, sizeof(pfAcceptEx), &dwBytes, NULL, NULL); } // start_accepting() { //SOCKET acceptor = create_accepting_socket(); //DWORD expected = sizeof(struct sockaddr_in) + 16; //printf("* started accepting connections...\n"); // uses listener's completion key and overlapped structure //sock_state.socket = acceptor; //memset(&sock_ovl, 0, sizeof(WSAOVERLAPPED)); // starts asynchronous accept //if (!pfAcceptEx(sock, acceptor, sock_state.buf, 0 /* no recv */, expected, expected, NULL, &sock_ovl)) //{ // int err = WSAGetLastError(); // if (err != ERROR_IO_PENDING) // { // printf("* error %d in AcceptEx\n", err); // exit(1); // } //} } } // ----------------------------------------------------------------------------- static void recvBuffer(void) { char* buf = msgBuf; int pendingLen = BUFLEN; printf("* receiving reply\n"); while (pendingLen > 0) { int partialLen = recv(sock, buf, pendingLen, 0); if (partialLen > 0) { pendingLen -= partialLen; buf += partialLen; continue; } // ------ if (partialLen == 0) { printf("* connection closed by the server\n"); } else // partialLen < 0 { int err = WSAGetLastError(); printf("* error %d in recv\n", err); } exit(1); } } // ----------------------------------------------------------------------------- static void run(void) { DWORD length; BOOL resultOk; WSAOVERLAPPED* ovl_res; SocketState* socketState; for (;;) { sendBuffer(); resultOk = get_completion_status(&length, &socketState, &ovl_res); recvBuffer(); } } // ----------------------------------------------------------------------------- static void sendBuffer(void) { char* buf = msgBuf; int pendingLen = BUFLEN; printf("* sending message\n"); sprintf(msgBuf, "%05 *****", msgNumber++); while (pendingLen > 0) { int partialLen = send(sock, buf, pendingLen, 0); if (partialLen > 0) { pendingLen -= partialLen; buf += partialLen; continue; } // ----------- if (partialLen == 0) { printf("* connection closed by the server\n"); } else // partialLen < 0 { int err = WSAGetLastError(); printf("* error %d in send\n", err); } exit(1); } } // ----------------------------------------------------------------------------- static SOCKET create_accepting_socket(void) { SOCKET acceptor = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP); if (acceptor == INVALID_SOCKET) { printf("* error creating accept socket!\n"); exit(1); } return acceptor; } // ----------------------------------------------------------------------------- static void create_io_completion_port(void) { cpl_port = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0); if (!cpl_port) { int err = WSAGetLastError(); printf("* error %d in line %d CreateIoCompletionPort\n", err, __LINE__); exit(1); } } // ----------------------------------------------------------------------------- static BOOL get_completion_status(DWORD* length, SocketState** socketState, WSAOVERLAPPED** ovl_res) { BOOL resultOk; *ovl_res = NULL; *socketState = NULL; resultOk = GetQueuedCompletionStatus(cpl_port, length, (PULONG_PTR)socketState, ovl_res, INFINITE); if (!resultOk) { DWORD err = GetLastError(); printf("* error %d getting completion port status!!!\n", err); } if (!*socketState || !*ovl_res) { printf("* don't know what to do, aborting!!!\n"); exit(1); } return resultOk; } // ----------------------------------------------------------------------------- // the end 

当服务器通过调用发送响应时：

 WSASend(socketState->socket, &wsabuf, 1, NULL, 0, ovl, NULL) 

我期望它被这条线上的客户端拾起：

 resultOk = get_completion_status(&length, &socketState, &ovl_res); 

但它不…

有人能告诉我我做错了什么吗？

编辑：

我已经采取了以下几点：

• 在客户端，您使用WSAConnect（）创build出站连接。
• 调用WSARecv（）和WSASend（）以在需要时开始读/写操作
• 如果要使用I / O完成端口，则必须使用WSASend / WSARecv。

并试图创build一个简单的基于IOCP的客户端：

 #include <iostream> #include <winsock2.h> #pragma comment(lib,"ws2_32.lib") static DWORD WINAPI ClientWorkerThread(LPVOID lpParameter); int main(void) { WSADATA WsaDat; if (WSAStartup(MAKEWORD(2, 2), &WsaDat) != NO_ERROR) return 0; // Step 1 - Create an I/O completion port. HANDLE hCompletionPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0); if (!hCompletionPort) return 0; // Step 2 - Find how many processors. SYSTEM_INFO systemInfo; GetSystemInfo(&systemInfo); const int nNumberOfProcessors = systemInfo.dwNumberOfProcessors; // Step 3 - Create worker threads. for (int i = 0; i < nNumberOfProcessors; i++) { HANDLE hThread = CreateThread(NULL, 0, ClientWorkerThread, hCompletionPort, 0, NULL); CloseHandle(hThread); } // Step 4 - Create a socket. SOCKET Socket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED); if (Socket == INVALID_SOCKET) return 0; struct hostent *host; if ((host = gethostbyname("localhost")) == NULL) return 0; SOCKADDR_IN SockAddr; SockAddr.sin_family = AF_INET; SockAddr.sin_addr.s_addr = *((unsigned long*)host->h_addr); SockAddr.sin_port = htons(8888); // Step 5 - Associate the socket with the I/O completion port. CreateIoCompletionPort((HANDLE)Socket, hCompletionPort, (ULONG_PTR)0, 0); if (WSAConnect(Socket, (SOCKADDR*)(&SockAddr), sizeof(SockAddr), NULL, NULL, NULL, NULL) == SOCKET_ERROR) return 0; char buffer[1000]; memset(buffer, 0, 999); WSABUF wsaBuf = {strlen(buffer), buffer}; DWORD dwSendBytes = 0; DWORD dwReceivedBytes = 0; DWORD dwFlags = 0; WSAOVERLAPPED wsaOverlapped; SecureZeroMemory((PVOID)&wsaOverlapped, sizeof(wsaOverlapped)); wsaOverlapped.hEvent = WSACreateEvent(); for(;;) { WSARecv(Socket, &wsaBuf, 1, &dwReceivedBytes, &dwFlags, &wsaOverlapped, NULL); std::cout << wsaBuf.buf; //WSASend(Socket, &wsaBuf, 1, &dwSendBytes, 0, &wsaOverlapped, NULL); int nError = WSAGetLastError(); if(nError != WSAEWOULDBLOCK&&nError != 0) { std::cout << "Winsock error code: " << nError << "\r\n"; std::cout << "Server disconnected!\r\n"; shutdown(Socket, SD_SEND); closesocket(Socket); break; } Sleep(1000); } WSACleanup(); system("PAUSE"); return 0; } static DWORD WINAPI ClientWorkerThread(LPVOID lpParameter) { HANDLE hCompletionPort = (HANDLE)lpParameter; DWORD dwBytesTransferred = 0; while (TRUE) { BOOL bRet = GetQueuedCompletionStatus(hCompletionPort, &dwBytesTransferred, (LPDWORD)0, (LPOVERLAPPED*)0, INFINITE); } return 0; } 

我知道有几件事我做错了，但我不知道它们是什么。

有人可以看看我的代码，并给我一些提示吗？

非常感谢

编辑2：

对不起，这篇文章太长了。

在阅读了下面的Remy的评论之后，我又试图实现一个基于IOCP的客户端，但是我仍然不确定自己是否在正确的轨道上。

我真的很感激，如果有人可以看看我的新代码（在VS2010编译罚款和错误检查省略），并给我一些反馈。

NonBlockingClient：

 #include <iostream> #include <winsock2.h> #pragma comment(lib, "ws2_32.lib") static DWORD WINAPI ClientWorkerThread(LPVOID lpParameter); typedef struct _PER_HANDLE_DATA { SOCKET Socket; } PER_HANDLE_DATA, * LPPER_HANDLE_DATA; typedef struct { WSAOVERLAPPED wsaOverlapped; WSABUF wsaBuf; int OperationType; } PER_IO_DATA, * LPPER_IO_DATA; int main(void) { WSADATA WsaDat; WSAStartup(MAKEWORD(2, 2), &WsaDat); // Step 1 - Create an I/O completion port. HANDLE hCompletionPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0); // Step 2 - Find how many processors. SYSTEM_INFO systemInfo; GetSystemInfo(&systemInfo); // Step 3 - Create worker threads. for (int i = 0; i < (int)systemInfo.dwNumberOfProcessors; i++) { HANDLE hThread = CreateThread(NULL, 0, ClientWorkerThread, hCompletionPort, 0, NULL); CloseHandle(hThread); } // Step 4 - Create a socket. SOCKET Socket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED); PER_HANDLE_DATA *pPerHandleData = new PER_HANDLE_DATA; pPerHandleData->Socket = Socket; struct hostent *host; host = gethostbyname("localhost"); SOCKADDR_IN SockAddr; SockAddr.sin_family = AF_INET; SockAddr.sin_addr.s_addr = *((unsigned long*)host->h_addr); SockAddr.sin_port = htons(8888); // Step 5 - Associate the socket with the I/O completion port. CreateIoCompletionPort((HANDLE)Socket, hCompletionPort, (DWORD)pPerHandleData, 0); WSAConnect(Socket, (SOCKADDR*)(&SockAddr), sizeof(SockAddr), NULL, NULL, NULL, NULL); static char buffer[1000]; memset(buffer, 0, 999); PER_IO_DATA *pPerIoData = new PER_IO_DATA; pPerIoData->wsaBuf.buf = buffer; pPerIoData->wsaBuf.len = sizeof(buffer); DWORD dwSendBytes = 0; DWORD dwReceivedBytes = 0; DWORD dwFlags = 0; SecureZeroMemory((PVOID)&pPerIoData->wsaOverlapped, sizeof(pPerIoData->wsaOverlapped)); pPerIoData->wsaOverlapped.hEvent = WSACreateEvent(); WSARecv(Socket, &pPerIoData->wsaBuf, 1, &dwReceivedBytes, &dwFlags, &pPerIoData->wsaOverlapped, NULL); std::cout << pPerIoData->wsaBuf.buf; for (;;) { int nError = WSAGetLastError(); if (nError != WSAEWOULDBLOCK&&nError != 0) { std::cout << "Winsock error code: " << nError << "\r\n"; std::cout << "Server disconnected!\r\n"; shutdown(Socket, SD_SEND); closesocket(Socket); break; } Sleep(1000); } delete pPerHandleData; delete pPerIoData; WSACleanup(); return 0; } static DWORD WINAPI ClientWorkerThread(LPVOID lpParameter) { HANDLE hCompletionPort = (HANDLE)lpParameter; DWORD bytesCopied = 0; OVERLAPPED *overlapped = 0; LPPER_HANDLE_DATA PerHandleData; LPPER_IO_DATA PerIoData; DWORD SendBytes, RecvBytes; DWORD Flags; BOOL bRet; while (TRUE) { bRet = GetQueuedCompletionStatus(hCompletionPort, &bytesCopied, (LPDWORD)&PerHandleData, (LPOVERLAPPED*)&PerIoData, INFINITE); if (bytesCopied == 0) { break; } else { Flags = 0; ZeroMemory(&(PerIoData->wsaOverlapped), sizeof(WSAOVERLAPPED)); PerIoData->wsaBuf.len = 1000; WSARecv(PerHandleData->Socket, &(PerIoData->wsaBuf), 1, &RecvBytes, &Flags, &(PerIoData->wsaOverlapped), NULL); } } return 0; } 

NonBlockingServer：

 #include <iostream> #include <winsock2.h> #pragma comment(lib,"ws2_32.lib") int main() { WSADATA WsaDat; WSAStartup(MAKEWORD(2,2), &WsaDat); SOCKET listenSocket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED); SOCKADDR_IN server; server.sin_family = AF_INET; server.sin_addr.s_addr = INADDR_ANY; server.sin_port = htons(8888); bind(listenSocket, (SOCKADDR*)(&server), sizeof(server)); listen(listenSocket, 1); SOCKET acceptSocket = SOCKET_ERROR; sockaddr_in saClient; int nClientSize = sizeof(saClient); while (acceptSocket == SOCKET_ERROR) { std::cout << "Waiting for incoming connections...\r\n"; acceptSocket = WSAAccept(listenSocket, (SOCKADDR*)&saClient, &nClientSize, NULL, NULL); } std::cout << "Client connected!\r\n\r\n"; char *szMessage = "Welcome to the server!\r\n"; WSAOVERLAPPED SendOverlapped; DWORD SendBytes; WSABUF DataBuf; DataBuf.len = 1000; DataBuf.buf = szMessage; SecureZeroMemory((PVOID)&SendOverlapped, sizeof(WSAOVERLAPPED)); SendOverlapped.hEvent = WSACreateEvent(); for (;;) { WSASend(acceptSocket, &DataBuf, 1, &SendBytes, 0, &SendOverlapped, NULL); int nError = WSAGetLastError(); if (nError != WSAEWOULDBLOCK && nError != 0) { std::cout << "Winsock error code: " << nError << "\r\n"; std::cout << "Client disconnected!\r\n"; shutdown(acceptSocket, SD_SEND); closesocket(acceptSocket); break; } Sleep(1000); } WSACleanup(); return 0; } 

再次感谢！

 #include <iostream> #include <string> #include <winsock2.h> #pragma comment(lib, "ws2_32.lib") typedef struct { WSAOVERLAPPED Overlapped; SOCKET Socket; WSABUF wsaBuf; char Buffer[1024]; DWORD Flags; } PER_IO_DATA, * LPPER_IO_DATA; static DWORD WINAPI ClientWorkerThread(LPVOID lpParameter) { HANDLE hCompletionPort = (HANDLE)lpParameter; DWORD NumBytesRecv = 0; ULONG CompletionKey; LPPER_IO_DATA PerIoData; while (GetQueuedCompletionStatus(hCompletionPort, &NumBytesRecv, &CompletionKey, (LPOVERLAPPED*)&PerIoData, INFINITE)) { if (!PerIoData) continue; if (NumBytesRecv == 0) { std::cout << "server disconnected!\r\n\r\n"; } else { // use PerIoData->Buffer as needed... std::cout << std::string(PerIoData->Buffer, NumBytesRecv); PerIoData->wsaBuf.len = sizeof(PerIoData->Buffer); PerIoData->Flags = 0; if (WSARecv(PerIoData->Socket, &(PerIoData->wsaBuf), 1, &NumBytesRecv, &(PerIoData->Flags), &(PerIoData->Overlapped), NULL) == 0) continue; if (WSAGetLastError() == WSA_IO_PENDING) continue; } closesocket(PerIoData->Socket); delete PerIoData; } return 0; } int main(void) { WSADATA WsaDat; if (WSAStartup(MAKEWORD(2, 2), &WsaDat) != 0) return 0; HANDLE hCompletionPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0); if (!hCompletionPort) return 0; SYSTEM_INFO systemInfo; GetSystemInfo(&systemInfo); for (DWORD i = 0; i < systemInfo.dwNumberOfProcessors; ++i) { HANDLE hThread = CreateThread(NULL, 0, ClientWorkerThread, hCompletionPort, 0, NULL); CloseHandle(hThread); } SOCKET Socket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED); if (Socket == INVALID_SOCKET) return 0; SOCKADDR_IN SockAddr; SockAddr.sin_family = AF_INET; SockAddr.sin_addr.s_addr = inet_addr("127.0.0.1"); SockAddr.sin_port = htons(8888); CreateIoCompletionPort((HANDLE)Socket, hCompletionPort, 0, 0); if (WSAConnect(Socket, (SOCKADDR*)(&SockAddr), sizeof(SockAddr), NULL, NULL, NULL, NULL) == SOCKET_ERROR) return 0; PER_IO_DATA *pPerIoData = new PER_IO_DATA; ZeroMemory(pPerIoData, sizeof(PER_IO_DATA)); pPerIoData->Socket = Socket; pPerIoData->Overlapped.hEvent = WSACreateEvent(); pPerIoData->wsaBuf.buf = pPerIoData->Buffer; pPerIoData->wsaBuf.len = sizeof(pPerIoData->Buffer); DWORD dwNumRecv; if (WSARecv(Socket, &(pPerIoData->wsaBuf), 1, &dwNumRecv, &(pPerIoData->Flags), &(pPerIoData->Overlapped), NULL) == SOCKET_ERROR) { if (WSAGetLastError() != WSA_IO_PENDING) { delete pPerIoData; return 0; } } while (TRUE) Sleep(1000); shutdown(Socket, SD_BOTH); closesocket(Socket); WSACleanup(); return 0; } 

 #include <iostream> #include <winsock2.h> #pragma comment(lib,"ws2_32.lib") typedef struct { WSAOVERLAPPED Overlapped; SOCKET Socket; WSABUF wsaBuf; char Buffer[1024]; DWORD BytesSent; DWORD BytesToSend; } PER_IO_DATA, * LPPER_IO_DATA; static DWORD WINAPI serverWorkerThread(LPVOID lpParameter) { HANDLE hCompletionPort = (HANDLE)lpParameter; DWORD NumBytesSent = 0; ULONG CompletionKey; LPPER_IO_DATA PerIoData; while (GetQueuedCompletionStatus(hCompletionPort, &NumBytesSent, &CompletionKey, (LPOVERLAPPED*)&PerIoData, INFINITE)) { if (!PerIoData) continue; if (NumBytesSent == 0) { std::cout << "Client disconnected!\r\n\r\n"; } else { PerIoData->BytesSent += NumBytesSent; if (PerIoData->BytesSent < PerIoData->BytesToSend) { PerIoData->wsaBuf.buf = &(PerIoData->Buffer[PerIoData->BytesSent]); PerIoData->wsaBuf.len = (PerIoData->BytesToSend - PerIoData->BytesSent); } else { PerIoData->wsaBuf.buf = PerIoData->Buffer; PerIoData->wsaBuf.len = strlen(PerIoData->Buffer); PerIoData->BytesSent = 0; PerIoData->BytesToSend = PerIoData->wsaBuf.len; } if (WSASend(PerIoData->Socket, &(PerIoData->wsaBuf), 1, &NumBytesSent, 0, &(PerIoData->Overlapped), NULL) == 0) continue; if (WSAGetLastError() == WSA_IO_PENDING) continue; } closesocket(PerIoData->Socket); delete PerIoData; } return 0; } int main() { WSADATA WsaDat; if (WSAStartup(MAKEWORD(2,2), &WsaDat) != 0) return 0; HANDLE hCompletionPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0); if (!hCompletionPort) return 0; SYSTEM_INFO systemInfo; GetSystemInfo(&systemInfo); for (DWORD i = 0; i < systemInfo.dwNumberOfProcessors; ++i) { HANDLE hThread = CreateThread(NULL, 0, serverWorkerThread, hCompletionPort, 0, NULL); CloseHandle(hThread); } SOCKET listenSocket = WSASocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, NULL, 0, WSA_FLAG_OVERLAPPED); if (listenSocket == INVALID_SOCKET) return 0; SOCKADDR_IN server; ZeroMemory(&server, sizeof(server)); server.sin_family = AF_INET; server.sin_addr.s_addr = INADDR_ANY; server.sin_port = htons(8888); if (bind(listenSocket, (SOCKADDR*)(&server), sizeof(server)) != 0) return 0; if (listen(listenSocket, 1) != 0) return 0; std::cout << "Waiting for incoming connection...\r\n"; SOCKET acceptSocket; do { sockaddr_in saClient; int nClientSize = sizeof(saClient); acceptSocket = WSAAccept(listenSocket, (SOCKADDR*)&saClient, &nClientSize, NULL, NULL); } while (acceptSocket == INVALID_SOCKET); std::cout << "Client connected!\r\n\r\n"; CreateIoCompletionPort((HANDLE)acceptSocket, hCompletionPort, 0, 0); LPPER_IO_DATA pPerIoData = new PER_IO_DATA; ZeroMemory(pPerIoData, sizeof(PER_IO_DATA)); strcpy(pPerIoData->Buffer, "Welcome to the server!\r\n"); pPerIoData->Overlapped.hEvent = WSACreateEvent(); pPerIoData->Socket = acceptSocket; pPerIoData->wsaBuf.buf = pPerIoData->Buffer; pPerIoData->wsaBuf.len = strlen(pPerIoData->Buffer); pPerIoData->BytesToSend = pPerIoData->wsaBuf.len; DWORD dwNumSent; if (WSASend(acceptSocket, &(pPerIoData->wsaBuf), 1, &dwNumSent, 0, &(pPerIoData->Overlapped), NULL) == SOCKET_ERROR) { if (WSAGetLastError() != WSA_IO_PENDING) { delete pPerIoData; return 0; } } while (TRUE) Sleep(1000); shutdown(acceptSocket, SD_BOTH); closesocket(acceptSocket); WSACleanup(); return 0; }