서버

/*
## 소켓 서버 : 1 v n - overlapped event
1. socket()			: 소켓생성
2. bind()			: 소켓설정
3. listen()			: 수신대기열생성
4. accept()			: 연결대기
5. read()&write()
	WIN recv()&send	: 데이터 읽고쓰기
6. close()
	WIN closesocket	: 소켓종료
*/

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

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

#define MAX_BUFFER		1024
#define SERVER_PORT		3500

struct SOCKETINFO
{
	WSAOVERLAPPED overlapped;
	WSABUF dataBuffer;
	SOCKET socket;
	char messageBuffer[MAX_BUFFER];
	int receiveBytes;
	int sendBytes;
};
struct THREADINFO
{
	SOCKETINFO **sockets;
	WSAEVENT *events;
	int *eventCount;	
};

CRITICAL_SECTION criticalSection;

DWORD WINAPI makeThread(LPVOID workerThreadInfo);

int _tmain(int argc, _TCHAR* argv[])
{
	struct SOCKETINFO *sockets[WSA_MAXIMUM_WAIT_EVENTS];
	WSAEVENT events[WSA_MAXIMUM_WAIT_EVENTS];

	int totalIndex = 0;
	int listenSocketIndex = 0;


	// 임계영역 초기화
	InitializeCriticalSection(&criticalSection);
		
	// Winsock Start - windock.dll 로드
	WSADATA WSAData;
	if (WSAStartup(MAKEWORD(2, 2), &WSAData) != 0)
	{
		printf("Error - Can not load 'winsock.dll' file\n");
		return 1;
	}

	// 1. 소켓생성  
	SOCKET listenSocket = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, WSA_FLAG_OVERLAPPED);
	if (listenSocket == INVALID_SOCKET)
	{
		printf("Error - Invalid socket\n");
		return 1;
	}

	// 서버정보 객체설정
	SOCKADDR_IN serverAddr;
	memset(&serverAddr, 0, sizeof(SOCKADDR_IN));
	serverAddr.sin_family = PF_INET;
	serverAddr.sin_port = htons(SERVER_PORT);
	serverAddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);

	// 2. 소켓설정
	if (bind(listenSocket, (struct sockaddr*)&serverAddr, sizeof(SOCKADDR_IN)) == SOCKET_ERROR)
	{
		printf("Error - Fail bind\n");
		// 6. 소켓종료
		closesocket(listenSocket);
		// Winsock End
		WSACleanup();
		return 1;
	}

	// 3. 수신대기열생성
	if (listen(listenSocket, 5) == SOCKET_ERROR)
	{
		printf("Error - Fail listen\n");
		// 6. 소켓종료
		closesocket(listenSocket);
		// Winsock End
		WSACleanup();
		return 1;
	}

	// 스레드 객체 설정	
	struct THREADINFO *workerThreadInfo;
	workerThreadInfo = (struct THREADINFO *)malloc(sizeof(struct THREADINFO));
	unsigned long threadId;	
		
	// - 소켓생성
	sockets[listenSocketIndex] = (struct SOCKETINFO *)malloc(sizeof(struct SOCKETINFO));
	memset((struct SOCKETINFO *)sockets[listenSocketIndex], 0x00, sizeof(struct SOCKETINFO));
	sockets[listenSocketIndex]->socket = listenSocket;
	sockets[listenSocketIndex]->receiveBytes = 0;
	sockets[listenSocketIndex]->sendBytes = 0;
	
	// - 이벤트 객체 생성
	events[listenSocketIndex] = WSACreateEvent();
	if (events[listenSocketIndex] == WSA_INVALID_EVENT)
	{
		printf("Error - Event Create Failure\n");
		return 1;
	}
	
	// 스레드 생성
	totalIndex = listenSocketIndex + 1;
	workerThreadInfo->eventCount = &totalIndex;
	workerThreadInfo->sockets = sockets;
	workerThreadInfo->events = events;
	
	HANDLE hThread = CreateThread(NULL, 0, makeThread, workerThreadInfo, 0, &threadId);
	if (hThread == NULL)
	{
		printf("Error - Thread Create Failure\n");
		return 1;
	}
	
	SOCKADDR_IN clientAddr;
	int addrLen = sizeof(SOCKADDR_IN);
	memset(&clientAddr, 0, addrLen);
	SOCKET clientSocket;
	SOCKETINFO *socketInfo;
	DWORD receiveBytes;
	DWORD flags;
	
	while (1)
	{
		clientSocket = accept(listenSocket, (struct sockaddr *)&clientAddr, &addrLen);
		if (clientSocket == INVALID_SOCKET)
		{
			printf("Error - Accept Failure\n");
			return 1;
		}

		// CriticalSection - START
		EnterCriticalSection(&criticalSection);
		
		socketInfo = (struct SOCKETINFO *)malloc(sizeof(struct SOCKETINFO));
		memset((void *)socketInfo, 0x00, sizeof(struct SOCKETINFO));
				
		sockets[totalIndex] = socketInfo;
		socketInfo->socket = clientSocket;
		socketInfo->dataBuffer.len = MAX_BUFFER;
		socketInfo->dataBuffer.buf = sockets[totalIndex]->messageBuffer;

		events[totalIndex] = WSACreateEvent();
		socketInfo->overlapped.hEvent = events[totalIndex];

		flags = 0;
		WSARecv(sockets[totalIndex]->socket, &sockets[totalIndex]->dataBuffer, 1, &receiveBytes, &flags, &(sockets[totalIndex]->overlapped), NULL);

		totalIndex = totalIndex + 1;

		LeaveCriticalSection(&criticalSection);
		// CriticalSection - END

		// event 오브젝트를 신호대기상태로 만든다.
		WSASetEvent(events[listenSocketIndex]);
	}

	// 6-2. 리슨 소켓종료
	closesocket(listenSocket);

	// Winsock End
	WSACleanup();
	
	return 0;
}

DWORD WINAPI makeThread(LPVOID workerThreadInfo)
{
	struct THREADINFO *threadInfo = (struct THREADINFO *)workerThreadInfo;
	int eventNumber;	
	struct SOCKETINFO *eventSocket;
	DWORD receiveBytes;
	DWORD flags;
	
	while (1)
	{
		// 이벤트 대기
		eventNumber = WSAWaitForMultipleEvents(*threadInfo->eventCount, threadInfo->events, FALSE, WSA_INFINITE, FALSE);
		if (eventNumber == WSA_WAIT_FAILED)
		{
			printf("Error - Wait Failure\n");
			continue;
		}
		
		// 이벤트 리셋 : 이벤트가 일어난 소켓을 찾아내고 이벤트 객체는 다시 대기상태가 된다.
		eventSocket = threadInfo->sockets[eventNumber - WSA_WAIT_EVENT_0];
		WSAResetEvent(threadInfo->events[eventNumber - WSA_WAIT_EVENT_0]);

		// 듣기소켓 관련해서는 처리하지 않는다.
		if ((eventNumber - WSA_WAIT_EVENT_0) == 0)
		{			
			continue;
		}

		// 중첩 소켓을 이용해 데이터를 처리 : 다른일을 처리하고 있다가 데이터 입력이 완료되면 이벤트가 발생 하도록 해준다.
		// ==> 리눅스와 달리 데이터 입력시 유저모드와 커널모드의 변환을 최소화해서 성능을 향상시킨다.
		if (WSAGetOverlappedResult(eventSocket->socket, &(eventSocket->overlapped), &receiveBytes, FALSE, &flags) == FALSE || receiveBytes == 0)
		{
			// 데이터 입력이 없다면 소켓 & 이벤트 객체를 닫고 메모리에서 해제한다.
			closesocket(eventSocket->socket);
			free(eventSocket);
			WSACloseEvent(threadInfo->events[eventNumber - WSA_WAIT_EVENT_0]);
			
			// 임계영역을 만들고 소캣과 이벤트 객체 저장소를 정리한다.
			EnterCriticalSection(&criticalSection);
			
			if (eventNumber - WSA_WAIT_EVENT_0 + 1 != *threadInfo->eventCount)
			{
				for (int i = eventNumber - WSA_WAIT_EVENT_0; i < *threadInfo->eventCount; i++)
				{
					threadInfo->sockets[i] = threadInfo->sockets[i + 1];
					threadInfo->events[i] = threadInfo->events[i + 1];
				}
			}
			*threadInfo->eventCount = *threadInfo->eventCount - 1;
			LeaveCriticalSection(&criticalSection);
			continue;
		}
		printf("TRACE - Receive message : %s (%d bytes)\n", eventSocket->messageBuffer, receiveBytes);

		// 이벤트 소캣 초기화
		memset((void *)&eventSocket->overlapped, 0x00, sizeof(WSAOVERLAPPED));
		eventSocket->overlapped.hEvent = threadInfo->events[eventNumber - WSA_WAIT_EVENT_0];
		eventSocket->dataBuffer.len = MAX_BUFFER;
		eventSocket->dataBuffer.buf = eventSocket->messageBuffer;

		int sendBytes = send(eventSocket->socket, eventSocket->messageBuffer, strlen(eventSocket->messageBuffer), 0);
		if (sendBytes > 0)
		{
			printf("TRACE - Send message : %s (%d bytes)\n", eventSocket->messageBuffer, sendBytes);
		}
		if (WSARecv(eventSocket->socket, &(eventSocket->dataBuffer), 1, &receiveBytes, &flags, &(eventSocket->overlapped), NULL) == SOCKET_ERROR)
		{
			if (WSAGetLastError() != ERROR_IO_PENDING)
			{
				printf("Error - IO pending Failure\n");
				return 1;
			}
		}
	}
	
	return 1;
}

클라이언트

/*
## 소켓 서버 : 1 v n - overlapped event
1. socket()			: 소켓생성
2. connect()		: 연결요청
3. read()&write()
	WIN recv()&send	: 데이터 읽고쓰기
4. close()
	WIN closesocket	: 소켓종료
*/

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

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

#define MAX_BUFFER		1024
#define SERVER_IP		"127.0.0.1"
#define SERVER_PORT		3500

int _tmain(int argc, _TCHAR* argv[])
{	
	// Winsock Start - winsock.dll 로드
	WSADATA WSAData;
	if (WSAStartup(MAKEWORD(2, 0), &WSAData) != 0)
	{
		printf("Error - Can not load 'winsock.dll' file\n");
		return 1;
	}

	// 1. 소켓생성
	SOCKET listenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
	if (listenSocket == INVALID_SOCKET)
	{
		printf("Error - Invalid socket\n");
		return 1;
	}

	// 서버정보 객체설정
	SOCKADDR_IN serverAddr;
	memset(&serverAddr, 0, sizeof(SOCKADDR_IN));
	serverAddr.sin_family = AF_INET;
	serverAddr.sin_port = htons(SERVER_PORT);
	serverAddr.sin_addr.S_un.S_addr = inet_addr(SERVER_IP);

	// 2. 연결요청
	if (connect(listenSocket, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) == SOCKET_ERROR)
	{
		printf("Error - Fail to connect\n");
		// 4. 소켓종료
		closesocket(listenSocket);
		// Winsock End
		WSACleanup();
		return 1;
	}
	else
	{
		printf("Server Connected\n* Enter Message\n->");
	}
	
	while (1)
	{		
		// 메시지 입력
		char messageBuffer[MAX_BUFFER];
		int i, bufferLen;
		for (i = 0; 1; i++)
		{
			messageBuffer[i] = getchar();
			if (messageBuffer[i] == '\n')
			{
				messageBuffer[i++] = '\0';
				break;
			}
		}
		bufferLen = i;
		
		// 3-1. 데이터 쓰기
		int sendBytes = send(listenSocket, messageBuffer, bufferLen, 0);
		if (sendBytes > 0)
		{
			printf("TRACE - Send message : %s (%d bytes)\n", messageBuffer, sendBytes);
			// 3-2. 데이터 읽기
			int receiveBytes = recv(listenSocket, messageBuffer, MAX_BUFFER, 0);
			if (receiveBytes > 0)
			{
				printf("TRACE - Receive message : %s (%d bytes)\n* Enter Message\n->", messageBuffer, receiveBytes);
			}			
		}
		
	}		

	// 4. 소켓종료
	closesocket(listenSocket);

	// Winsock End
	WSACleanup();
	
	return 0;
}