利用异步通知I/O模型实现回声服务器端（windows）

#include <stdio.h>
#include <string.h>
#include <winsock2.h>

#define BUF_SIZE 100

void CompressSockets(SOCKET hSockArr[], int idx, int total);
void CompressEvents(WSAEVENT hEventArr[], int idx, int total);
void ErrorHanding(char *msg);

int main(int argc, char *argv[])
{
	WSADATA wsaData;
	SOCKET hServSock, hClntSock;
	SOCKADDR_IN servAdr, clntAdr;

	SOCKET hSockArr[WSA_MAXIMUM_WAIT_EVENTS];
	WSAEVENT hEventArr[WSA_MAXIMUM_WAIT_EVENTS];
	WSAEVENT newEvent;
	WSANETWORKEVENTS netEvents;

	int numOfClntSock = 0;
	int strLen, i;
	int postInfo, startIdx;
	int clntAdrLen;
	char msg[BUF_SIZE];

	if (argc != 2)
	{
		printf("Usage: %s <port>
", argv[0]);
		exit(1);
	}
	if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
		ErrorHanding("WSAStartUp() error!");

	hServSock = socket(AF_INET, SOCK_STREAM, 0);
	memset(&servAdr, 0, sizeof(servAdr));
	servAdr.sin_family = AF_INET;
	servAdr.sin_addr.s_addr = htonl(INADDR_ANY);
	servAdr.sin_port = htons(atoi(argv[1]));

	if (bind(hServSock, (SOCKADDR *) &servAdr, sizeof(servAdr)) == SOCKET_ERROR)
		ErrorHanding("bind() error");

	if (listen(hServSock, 5) == SOCKET_ERROR)
		ErrorHanding("listen() error");

	newEvent = WSACreateEvent();
	if (WSAEventSelect(hServSock, newEvent, FD_ACCEPT) == SOCKET_ERROR)
		ErrorHanding("WSAEventSelect() error");

	hSockArr[numOfClntSock] = hServSock;
	hEventArr[numOfClntSock] = newEvent;
	numOfClntSock ++;

	while (1)
	{
		postInfo = WSAWaitForMultipleEvents(numOfClntSock, hEventArr, FALSE, INFINITE, FALSE);
		startIdx = postInfo - WSA_WAIT_EVENT_0;

		for (i = startIdx; i < numOfClntSock; i++)
		{
			int sigEventIdx = WSAWaitForMultipleEvents(1, &hEventArr[i], TRUE, 0, FALSE);
			if (sigEventIdx == WSA_WAIT_FAILED || WSA_WAIT_TIMEOUT)
			{
				continue;
			}
			else
			{
				sigEventIdx = i;
				WSAEnumNetworkEvents(hSockArr[sigEventIdx], hEventArr[sigEventIdx], &netEvents);
				if (netEvents.lNetworkEvents & FD_ACCEPT) //请求连接时
				{
					if (netEvents.iErrorCode[FD_ACCEPT_BIT] != 0)
					{
						puts("Accept Error");
						break;
					}
					clntAdrLen = sizeof(clntAdr);
					hClntSock = accept(hSockArr[sigEventIdx], (SOCKADDR *)&clntAdr, &clntAdrLen);
					newEvent = WSACreateEvent();
					WSAEventSelect(hClntSock, newEvent, FD_READ | FD_CLOSE);

					hEventArr[numOfClntSock] = newEvent;
					hSockArr[numOfClntSock] = hClntSock;
					numOfClntSock++;
					puts("connected new client ...");
				}

				if (netEvents.lNetworkEvents & FD_READ) //接收数据时
				{
					if (netEvents.iErrorCode[FD_READ_BIT] != 0)
					{
						puts("Read Error");
						break;
					}
					strLen = recv(hSockArr[sigEventIdx], msg, sizeof(msg), 0);
					send(hSockArr[sigEventIdx], msg, strLen, 0);
				}

				if (netEvents.lNetworkEvents & FD_CLOSE) //断开连接时
				{
					if (netEvents.iErrorCode[FD_CLOSE_BIT] != 0)
					{
						puts("Close Error");
						break;
					}
					WSACloseEvent(hEventArr[sigEventIdx]);
					closesocket(hSockArr[sigEventIdx]);

					numOfClntSock --;
					CompressSockets(hSockArr, sigEventIdx, numOfClntSock);
					CompressEvents(hEventArr, sigEventIdx, numOfClntSock);
				}
			}
		}
	}
	WSACleanup();
	return 0;
} // end of main function

void CompressSockets(SOCKET hSockArr[], int idx, int total)
{
	int i;
	for (i = idx; i < total; i++)
		hSockArr[i] = hSockArr[i + 1];
}

void CompressEvents(WSAEVENT hEventArr[], int idx, int total)
{
	int i;
	for (i = idx; i < total; i++)
		hEventArr[i] = hEventArr[i + 1];
}

void ErrorHanding(char *msg)
{
	fputs(msg, stderr);
	fputc('
', stderr);
	exit(1);
}

别忘了，项目中需要添加ws2_32.lib