ChatServer - Buoi 7

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

#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) {
        printf("Dang ket noi...\n");
        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* helloMsg = "Dang nhap theo cu phap \"CONNECT] [your_id]\".\n";
    send(client, helloMsg, strlen(helloMsg), 0);

    BOOL isRegistered = FALSE;
    

    while (1) {

        // nhan du lieu dau vao
        ret = recv(client, buf, sizeof(buf), 0);
        if (ret <= 0) {
            closesocket(client);
            return 0;
        }

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

        
        if (!isRegistered) { // chua login

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

                if (strcmp(cmd, "CONNECT") == 0) {

                    if (ret == 2) {

                        int i;
                        for (i = 0; i < numClients; i++) {
                            if (strcmp(id, ids[i]) == 0) {
                                break;
                            }
                        }
                        // kiem tra co trung ID hay khong
                        if (i < numClients) {
                            const char* errorMsg = "CONNECT ERROR: ID da duoc su dung. Hay chon ID khac.\n";
                            send(client, errorMsg, strlen(errorMsg), 0);
                        }
                        else {
                            const char* okMsg = "CONNECT OK.\n";
                            send(client, okMsg, strlen(okMsg), 0);
                            isRegistered = TRUE;

                            EnterCriticalSection(&cs);

                            ids[numClients] = id;
                            clients[numClients] = client;
                            numClients++;

                            LeaveCriticalSection(&cs);

                            // thong bao cho cac User khac co nguoi dang nhap 
                            char noticeUserLogin[64];
                            sprintf(noticeUserLogin, "%s: %s %s", "CONNECT ", id, " - Co User dang nhap\n");

                            for (int i = 0; i < numClients; i++)
                            {
                                if (client != clients[i]) {
                                    send(clients[i], noticeUserLogin, sizeof(noticeUserLogin), 0);
                                }
                            }
                        }

                    }else{
                         const char* errorMsg = "CONNECT ERROR Sai cu phap lenh CONNECT.\n";
                         send(client, errorMsg, strlen(errorMsg), 0);
                    }
                }
                else {
                    const char* errorMsg = "ERROR Lenh khong hop le.\n";
                    send(client, errorMsg, strlen(errorMsg), 0);
                }
        }
        
        else { // Da login
            char sendBuf[32];
            ret = sscanf(buf, "%s", cmd);
            // Gui tin nhan
            if (strcmp(cmd, "SEND") == 0) {
                char target[32];
                ret = sscanf(buf + strlen(cmd) + 1, "%s", target);// Doc ALL hay ID

                const char* errorMsg = "ERROR error_message - Gui tin nhan that bai.\n";
                const char* okMsg = "OK - Gui tin nhan thanh cong.\n";


                if (ret == -1) {
                    const char* errorMsg = "SEND ERROR Sai cu phap lenh SEND.\n";
                    send(client, errorMsg, strlen(errorMsg), 0);
                }
                else {
                    // Send ALL
                    if (strcmp(target, "ALL") == 0) {
                        sprintf(sendBuf, "MESSAGE_ALL %s %s", id, buf + strlen(cmd) + 1);
                        for (int i = 0; i < numClients; i++)
                            if (clients[i] != client) {
                                send(clients[i], sendBuf, strlen(sendBuf), 0);
                                send(client, okMsg, strlen(okMsg), 0);
                            }
                    }
                    else {
                        sprintf(sendBuf, "MESSAGE %s %s", id, buf + strlen(cmd) + 1);
                        int check = 0; // kiem tra xem co gui duoc tin nhan khong
                        for (int i = 0; i < numClients; i++)
                            if (strcmp(ids[i], cmd + 1) == 0) {
                                send(clients[i], sendBuf, strlen(sendBuf), 0);
                                send(client, okMsg, strlen(okMsg), 0);
                                check = 1;
                            }
                        if (check == 0) {
                            send(client, errorMsg, strlen(errorMsg), 0);
                        }
                    }
                }
            }
            // list user are connecting
            if (strcmp(cmd, "LIST") == 0) {
                char listUser[256] = "List Client: ";
                for (int i = 0; i < numClients; i++)
                    if (clients[i] != client) {
                        strcat(listUser, ids[i]);
                        strcat(listUser, " ");
                    }
                send(client, listUser, strlen(listUser), 0);
            }

            // Logout
            if (strcmp(cmd, "EXIT") == 0) {
                char noticeUserLogout[64];
                sprintf(noticeUserLogout, "%s: %s %s", "DISCONNECT ", id, " - Co User dang xuat\n");
                const char* okMsg = "OK - Dang xuat thanh cong.\n";
                isRegistered = FALSE;
                send(client, okMsg, strlen(okMsg), 0);
                RemoveClient(client);
                for (int i = 0; i < numClients; i++)
                    send(client, noticeUserLogout, strlen(noticeUserLogout), 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--;
}