Question

我正在编写一个服务器/客户端通信系统，客户端请求登录服务器并可以请求查看其他客户端的在线状态。我可以使客户端登录正常，但是当我尝试登录（成功）然后发送请求其他客户端信息的另一个数据包时，服务器不会收到该数据包。

服务器的主要部分，而不是从bind Server开始的技术连接：

Users client[2]; //I intialized them already

//Bind
bind(WelcomeSocket, (sockaddr*)&SvrAddr, sizeof(SvrAddr));

//listening
listen(WelcomeSocket, 5);

//temp users
Users temp;

//while loop for the connection 
while (1) {

    ConnectionSocket = accept(WelcomeSocket, NULL, NULL);



    if (recv(ConnectionSocket, RxBuffer, sizeof(RxBuffer), 0))
        cout << "WORKEDDDDDDDD" << endl;

    memcpy(&temp, RxBuffer, sizeof(struct Users));

    cout << temp.message << temp.userName << endl << endl;

    //check which message type is being sent
    switch(temp.message) {

    //if message type 1
    case 1 :
        for (int i = 0; i < 2; i++) {

            //if receieved username matches with any username in the database
            if (strcmp(temp.userName, client[i].userName) == 0) {

                //assign the recieved users information to the matched one in database
                strcpy(client[i].userName, temp.userName);
                client[i].online = true;
                client[i].message = 2;

                cout << client[i].userName << endl << client[i].online << endl;

                //send the acknowledgement packet
                send(ConnectionSocket, (char *)&client[i], sizeof(struct Users), 0);
            }

        }
        closesocket(ConnectionSocket);
        break;

    //if message type 3
    case 3 :
        cout << "3";
        break;

    default :
        break;

    }

}

closesocket(ConnectionSocket);
WSACleanup();
}

客户：

connect(ClientSocket, (sockaddr*)&SvrAddr, sizeof(SvrAddr));



//cout << "Name: ";
//cin >> login;

//Send request to login
int log;
char * name = new char[128];
char * request = new char[128];
Users client;
Users talkto;



    cout << "To login press (1). ";
    cin >> log;
    flushall();

    if (log == 1) {

        cout << "Username : ";
        cin.getline(name, 128, '\n');
        flushall();

        //Set client login info
        strcpy(client.userName, name);
        client.message = 1;



        send(ClientSocket, (char *)&client, sizeof(struct Users), 0);


        //Recieve acknowledgement
        recv(ClientSocket, RxBuffer, sizeof(RxBuffer), 0);
        //create temp users
        Users temp;

        memcpy(&temp, RxBuffer, sizeof(struct Users));



        if (temp.message == 2) {

            cout << "Enter user for user information: ";
            cin.getline(talkto.userName, 128, '\n');
            flushall();
            talkto.message = 3;

            //send request for user information packet
            if (send(ClientSocket, (char *)&talkto, sizeof(struct Users), 0))
            cout << "SENDT" << endl;
        }

        //cout << temp.userName << endl << temp.online << endl << temp.message;

        closesocket(ClientSocket);


WSACleanup();

}

用户的结构

struct Users {

int message;
char userName[50];
char ipAddress[50];
int PortNumber;
bool online;

};

不确定为什么它不会多次接收信息

Answer 1

对于每个客户端连接，您的服务器执行accept-recv-send-closesocket。周期。

服务器处理第一个数据包后，将关闭与客户端的连接。您需要在客户端发送每个数据包之前建立新连接（但这可能会使您的登录过程无效）或使服务器能够维持多个并发客户端连接在无限循环中轮询它们，可能在单独的线程中（一个或多个）。

Answer 2

ConnectionSocket = accept(WelcomeSocket, NULL, NULL);

你应该把它放在循环之前，而不是在里面，因为accept函数正在等待另一个客户端，阻止你接收另一个数据包。

此外，当您的recv调用返回0时，表示连接已关闭，并且它是流的结尾，因此当recv返回0或某些时，您应该从循环中断意外SOCKET_ERROR。

如何连续发送和接收数据包？

2 个答案: