ChatServerWSAAsync

#include <stdio.h>

#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <winsock2.h>
#pragma warning(disable:4996)
#pragma comment(lib, "ws2_32")

#define WM_SOCKET WM_USER + 1

BOOL CALLBACK WinProc(HWND, UINT, WPARAM, LPARAM);
void RemoveClient(CLIENT_INFO*, int*, int*);

typedef struct {
	SOCKET client;
	BOOL isRegistered;
	char* id;
} CLIENT_INFO;

CLIENT_INFO clients[64];
int numClients = 0;

int main()
{
    WSADATA wsa;
    WSAStartup(MAKEWORD(2, 2), &wsa);

    SOCKADDR_IN addr;
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    addr.sin_port = htons(9000);

    SOCKET listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    bind(listener, (SOCKADDR*)&addr, sizeof(addr));
    listen(listener, 5);

	WNDCLASS wndclass;
	const CHAR* providerClass = "AsyncSelect";
	HWND window;

	wndclass.style = 0;
	wndclass.lpfnWndProc = (WNDPROC)WinProc;
	wndclass.cbClsExtra = 0;
	wndclass.cbWndExtra = 0;
	wndclass.hInstance = NULL;
	wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
	wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wndclass.lpszMenuName = NULL;
	wndclass.lpszClassName = (LPCWSTR)providerClass;

	if (RegisterClass(&wndclass) == 0)
		return NULL;

	// Create a window
	if ((window = CreateWindow((LPCWSTR)providerClass, L"", WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
		NULL, NULL, NULL, NULL)) == NULL)
		return NULL;

	WSAAsyncSelect(listener, window, WM_SOCKET, FD_ACCEPT);

	MSG msg; // truyen nhan du lieu
	while (GetMessage(&msg, NULL, 0, 0) > 0)
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

}

BOOL CALLBACK WinProc(HWND hWnd, UINT wMsg, WPARAM wParam, LPARAM lParam)
{
	int index;
	if (wMsg == WM_SOCKET) 
	{
		// kiem tra loi
		if (WSAGETSELECTERROR(lParam))
		{
			closesocket(wParam);
			return TRUE;
		}

		// chap nhan ket noi
		if (WSAGETSELECTEVENT(lParam) == FD_ACCEPT)
		{
			SOCKET client = accept(wParam, NULL, NULL);
			printf("New client accepted: %d\n", client);

			CLIENT_INFO clientInfo;
			clientInfo.client = client;
			clientInfo.isRegistered = FALSE;
			clientInfo.id = NULL;

			clients[numClients] = clientInfo;
			numClients++;

			const char* helloMsg = "Dang nhap theo cu phap \"[client_id:] [your_id]\".\n";
			send(client, helloMsg, strlen(helloMsg), 0);

			WSAAsyncSelect(client, hWnd, WM_SOCKET, FD_READ | FD_CLOSE); // them 2 mat na READ, CLOSE
			// (soket client, cua so , ma thong diep, su kien) => CALLBACk lai duoc goi
		}

		// client dk giai phong ben tren nen se luwu vao wParam
		if (WSAGETSELECTEVENT(lParam) == FD_READ)
		{
			char buf[256];
			const char* errorMsg = "Sai cu phap. Hay nhap lai.\n";
			int ret;
			ret = recv(wParam, buf, sizeof(buf), 0);

			
			for (int i = 0; i < numClients; i++)
			{
				if (clients[i].client == wParam) {
					index = i;
					break;
				}
			}

			char cmd[16], id[32], tmp[32];
			
			buf[ret] = 0;
			printf("Received: %s\n", buf);
			

			if (!clients[index].isRegistered) {

				ret = sscanf(buf, "%s %s %s", cmd, id, tmp);

				 // kiem tra cu phap
				 if (ret == 2) {
					 if (strcmp(cmd, "client_id:") == 0) {
						 const char* okMsg = "Dang nhap thanh cong. Hay nhap thong diep de chuyen tiep.\n";
						 send(wParam, okMsg, strlen(okMsg), 0);

						 clients[index].id = id;
						 clients[index].isRegistered = TRUE;
					 }
					 else {
						 send(wParam, errorMsg, strlen(errorMsg), 0);
					 }
				 }else{
					 send(wParam, errorMsg, strlen(errorMsg), 0);
				 }
			}
			else {
				char sendBuf[256];
				ret = sscanf(buf, "%s", cmd);
				if (ret == -1 || cmd[0] != '@'){
					send(wParam, errorMsg, strlen(errorMsg), 0);
				}
				else {
					char* id = clients[index].id;
					sprintf(sendBuf, "%s: %s", id, buf + strlen(cmd) + 1);
					if (strcmp(cmd, "@all") == 0)
					{
						// Chuyen tiep tin nhan den cac client khac
						for (int i = 0; i < numClients; i++)
							if (clients[i].client != wParam)
								send(clients[i].client, sendBuf, strlen(sendBuf), 0);
					}
					else
					{
						for (int i = 0; i < numClients; i++)
							if (strcmp(clients[i].id, cmd + 1) == 0)
								send(clients[i].client, sendBuf, strlen(sendBuf), 0);
					}
				}

			}
		}

		if (WSAGETSELECTEVENT(lParam) == FD_CLOSE)
		{
			RemoveClient(clients, &numClients, &index);
			closesocket(wParam);
		}
	}
}
void RemoveClient(CLIENT_INFO* clients, int* numClients, int* i)
{
	if (*i < *numClients - 1)
		clients[*i] = clients[*numClients - 1];
	free(clients[*i].id);
	*numClients = *numClients - 1;
	*i = *i - 1;
}