Bai hoc tuan 7 ChatSerer

#include <iostream>
#include <WS2tcpip.h>
#include <winSock2.h>

#pragma comment(lib, "ws2_32")
#pragma warning(disable:4996) 

DWORD WINAPI ClientThread(LPVOID);
void RemoveClient(SOCKET);

char* ids[64];
SOCKET clients[64];
int numClients = 0;

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

    InitializeCriticalSection(&cs);

    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);

    while (1) {
        SOCKET client = accept(listener, NULL, NULL);
        printf("Ket noi moi : %d\n", client);

        CreateThread(0, 0, ClientThread, &client, 0, 0);
    }

    DeleteCriticalSection(&cs);

}

DWORD WINAPI ClientThread(LPVOID lpParam) {
    SOCKET client = *(SOCKET*)lpParam;

    char buf[256];
    int ret;

    char cmd[16], id[32], tmp[32];

    const char* errorMsg = "Sai cu phap xin moi nhap lai\n";
    const char* helloMsg = "Dang nhap theo cu phap \"[id:] [your_id]\".\n";
    const char* logout = "Dang xuat thanh cong\n ";
   

    send(client, helloMsg, strlen(helloMsg),0);

    int checkLogin = 0;

    char sendBuf[256];

   
    while (1) {
        //kiem tra dang nhap 
        if (checkLogin == 0) {
            ret = recv(client, buf, sizeof(buf), 0);
            if (ret <= 0) {
                closesocket(client);
                return 0;
            }

            buf[ret] = 0;
            printf("Received: %s", buf);

            //kiem tra cu phap
            ret = sscanf(buf, "%s %s %s", cmd, id, tmp);

            if (ret == 2) {
                if (strcmp(cmd, "id:") == 0) {
                    const char* okMsg = "Dang nhap thanh cong\nDang xuat theo cu phap [exit]\n";
                    send(client, okMsg, strlen(okMsg), 0);

                    EnterCriticalSection(&cs);
                    ids[numClients] = id;
                    clients[numClients] = client;
                    numClients++;
                    // thong bao cho cac user khac co nguoi dang nhap 
                    char noticeUser[256];
                    sprintf(noticeUser, "%s: %s %s", "User: ", id, " da tham gia nhom chat");
                    for (int i = 0; i < numClients; i++)
                    {
                        if (client != clients[i]) {
                            send(clients[i], noticeUser, sizeof(noticeUser), 0);
                        }
                    }
                    checkLogin = 1;
                    LeaveCriticalSection(&cs);
                }
                else {
                    send(client, errorMsg, strlen(errorMsg), 0);
                }
            }
            else {
                send(client, errorMsg, strlen(errorMsg), 0);
            }
        }
        // chuyen tiep tin nhan
        if (checkLogin == 1) {
            ret = recv(client, buf, sizeof(buf), 0);
            if (ret <= 0) {
                closesocket(client);
                return 0;
            }
            buf[ret] = 0;
            printf("Recevied: %s\n", buf);
            // Đăng xuất gan lai checklogin = 0
            if (strcmp(buf,"exit") == 0) {
                send(client, logout, strlen(logout), 0);
                printf("Co user: %s dang xuat\n", client);
                RemoveClient(client);
                checkLogin = 0;
            }
            else {
                ret = sscanf(buf, "%s", cmd);

                if (ret == -1 || cmd[0] != '@') {
                    send(client, errorMsg, strlen(errorMsg), 0);
                }
                else {
                    sprintf(sendBuf, "%s: %s", id, buf + strlen(cmd) + 1);

                    if (strcmp(cmd, "@all") == 0) {
                        // chuyen tiep tin nhan
                        for (int i = 0; i < numClients; i++)
                        {
                            if (client != clients[i]) {
                                send(clients[i], sendBuf, sizeof(sendBuf), 0);
                            }
                        }
                    }
                    else {
                        for (int i = 0; i < numClients; i++)
                        {
                            if (strcmp(ids[i], cmd + 1) == 0) {
                                send(clients[i], sendBuf, sizeof(sendBuf), 0);
                            }
                        }
                    }
                }
            }
        }
    }

    RemoveClient(client);
    closesocket(client);
}

void RemoveClient(SOCKET client)
{
    int i = 0;
    for (; i < numClients; i++)
        if (clients[i] == client) break;

    if (i < numClients - 1)
        clients[i] = clients[numClients - 1];
    numClients--;
}