Question

我对套接字编程完全不熟悉。我试图了解套接字编程和处理多个连接时的不同实践。我已经实现了以下功能。

服务器连接到多个客户端。 C1，C2，C3 ...... CN。
服务器向客户端发送一个时隙。
服务器向客户端发送消息以发送消息。（发送
有限期间的留言）
客户端在限定时间内发送消息
一旦首次连接的客户端是服务器发送消息的时间到下一个发送消息的客户等等。

这是我的工作代码。

Server.cpp

    #include "stdafx.h"
    #pragma comment(lib,"ws2_32.lib")
    #include <WinSock2.h>
    #include <string>
    #include <iostream>
    #include<conio.h>

    #define DEFAULT_NC_TIME  20
    #define MAX_CLIENTS 2
    SOCKET Connections[MAX_CLIENTS];
    int TotalConnections = 0;

    #include <vector>
    #include<time.h>


void wait ( int seconds )
{
    clock_t endwait;
    endwait = clock () + seconds * CLOCKS_PER_SEC ;
    while (clock() < endwait) {}
}

void ClientHandlerThread(int index) //index = the index in the SOCKET Connections array
    {
    int bufferlength; //Holds the length of the message a client sent
    while (true)
    {
        recv(Connections[index], (char*)&bufferlength, sizeof(int), NULL); //get buffer length
        char * buffer = new char[bufferlength+1]; //Allocate buffer
        buffer[bufferlength] = '\0';
        recv(Connections[index], buffer, bufferlength, NULL); //get buffer message from client
        std::cout << buffer << std::endl;
        delete[] buffer; 
    }
    }

void emitMessageToClient(int indexOfClient, int ts){
        std::string buftest="You are ready to transmit Message.\n";
        int size = buftest.size(); //Get size of message in bytes and store it in int size
        send(Connections[indexOfClient], (char*)&ts, sizeof(int), NULL); //send Timeslot Duration to the client i
        send(Connections[indexOfClient], (char*)&size, sizeof(int), NULL); //send Size of message
        send(Connections[indexOfClient], buftest.c_str(), buftest.size(), NULL); //send Message
        }


int main()
    {
    //Winsock Startup
    WSAData wsaData;
    WORD DllVersion = MAKEWORD(2, 1);
    if (WSAStartup(DllVersion, &wsaData) != 0)
    {
        MessageBoxA(NULL, "WinSock startup failed", "Error", MB_OK | MB_ICONERROR);
        return 0;
    }

    SOCKADDR_IN addr;
    int addrlen = sizeof(addr);
    addr.sin_addr.s_addr = inet_addr("127.0.0.1"); 
    addr.sin_port = htons(1111); 
    addr.sin_family = AF_INET;

    SOCKET sListen = socket(AF_INET, SOCK_STREAM, NULL);
    bind(sListen, (SOCKADDR*)&addr, sizeof(addr));
    listen(sListen, SOMAXCONN); 

    SOCKET newConnection; //Socket to hold the client's connection
    int ConnectionCounter = 0; //# of client connections
    for (int i = 0; i < MAX_CLIENTS; i++)
    {

        newConnection = accept(sListen, (SOCKADDR*)&addr, &addrlen);
        if (newConnection == 0)
        {
            std::cout << "Failed to accept the client's connection." << std::endl;
        }
        else
        {
            std::cout << "Client "<<i<<" Connected!" << std::endl;
            Connections[i] = newConnection; 
            TotalConnections += 1; //Increment total # of clients that have connected
        }
    }

    int ts = DEFAULT_NC_TIME / (TotalConnections + 1); // caculating time slot for each of connected node including server 
    std::cout<<"\nPress any key to start transmission: ";
    getche();
    for(int i= 0; i < TotalConnections; i++){

        emitMessageToClient(i, ts);
        CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientHandlerThread, (LPVOID)(i), NULL, NULL);
        wait(ts);
        if(i == (TotalConnections - 1)){
           i = 0;
        }
    }
    system("pause");
    return 0;
}

Client.cpp

        #include "stdafx.h"
    #pragma comment(lib,"ws2_32.lib") //Required for WinSock
    #include <WinSock2.h> //For win sockets
    #include <string> //For std::string
    #include <iostream> //For std::cout, std::endl, std::cin.getline
    #include <time.h>
    #include <vector>
    #include <conio.h>
    SOCKET Connection;//This client's connection to the server

    void wait ( int seconds )
    {
        clock_t endwait;
        endwait = clock () + seconds * CLOCKS_PER_SEC ;
        while (clock() < endwait) {}
    }

    void ClientThread()
    {
        int bufferlength; //Holds the length of the message we are receiving
        int ts; // holds timeslot duration for this client
        while (true)
        {
            recv(Connection, (char*)&ts, sizeof(int), NULL); //receive timeslot
            recv(Connection, (char*)&bufferlength, sizeof(int), NULL); //receive bufferlength
            char * buffer = new char[bufferlength+1];
            buffer[bufferlength] = '\0'; 
            recv(Connection, buffer, bufferlength, NULL);
            std::cout << buffer << std::endl; //print out buffer
            std::string userinput; //holds the user's chat message

            for (int n= ts; n>0; n--)
           {
            userinput = "First client sending message...";
            int bufferlength = userinput.size(); //Find buffer length
            send(Connection, (char*)&bufferlength, sizeof(int), NULL); //Send length of buffer
            send(Connection, userinput.c_str(), bufferlength, NULL); //Send buffer
            wait (1);
           }
            delete[] buffer; //Deallocate buffer
        }
    }

    int main()
    {
        //Winsock Startup
        WSAData wsaData;
        WORD DllVersion = MAKEWORD(2, 1);
        if (WSAStartup(DllVersion, &wsaData) != 0)
        {
            MessageBoxA(NULL, "Winsock startup failed", "Error", MB_OK | MB_ICONERROR);
            return 0;
        }

        SOCKADDR_IN addr; 
        int sizeofaddr = sizeof(addr);
        addr.sin_addr.s_addr = inet_addr("127.0.0.1"); 
        addr.sin_port = htons(1111);
        addr.sin_family = AF_INET;

        Connection = socket(AF_INET, SOCK_STREAM, NULL);
        if (connect(Connection, (SOCKADDR*)&addr, sizeofaddr) != 0)
        {
            MessageBoxA(NULL, "Failed to Connect", "Error", MB_OK | MB_ICONERROR);
            return 0; //Failed to Connect
        }

        std::cout << "Connected!" << std::endl;
        CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientThread, NULL, NULL, NULL);

        getche();
        return 0;
    }

一旦服务器向所有连接的客户端发送消息。服务器希望再次向其第一个客户端发送消息以再次发送消息。（周期性地）

问题

如果服务器将所有客户端c1，c2，c3转换为Cn并再次与他的第一个客户端C1通信，我该如何实现。（周期性地）我使用了这个检查

 if(i == (TotalConnections - 1)){
       i = 0;
 }

但是程序崩溃了。

Answer 1

通过将i设置回0，您会创建一个无限循环，因为i永远不会变得足够大以使循环结束。

for(int i= 0; i < TotalConnections; i++) {

    emitMessageToClient(i, ts);
    CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientHandlerThread, (LPVOID)(i), NULL, NULL);
    wait(ts);

    // This will create an infinite loop
    if(i == (TotalConnections - 1))
    {
        i = 0;
    }
}

您可以做的是等到循环结束后重新访问第一个连接：

for(int i= 0; i < TotalConnections; i++) {

    emitMessageToClient(i, ts);
    CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientHandlerThread, (LPVOID)(i), NULL, NULL);
    wait(ts);
}

// now the loop is over, revisit the first connection 
// if it exists      
if(TotalConnections > 0) {

    emitMessageToClient(0, ts);
    CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientHandlerThread, (LPVOID)(0), NULL, NULL);
    wait(ts);
}

在c ++中处理单个服务器和多个客户端

1 个答案: