Question

I am trying to write a Server application wrapper, as I would with any application and I’ve searched for over a week for a at least decent guide or tutorial on asynchronous sockets( this wrapper has to be asynchronous ) and so far what i could do is this:

#ifndef _SERVER_H
#define _SERVER_H

#include "asynserv.h" // header file with the important lib includes
#include <map>

namespace Connections
{
    DWORD WINAPI MainThread(LPVOID lParam); // Main thread
    DWORD WINAPI DataThread(LPVOID lParam); // thread that will be created for each client
    struct ClientServer // struct to keep a server and a client pair.
    {
    public:
        struct Client* Client;
        class Server* Server;
    };
    struct Client // a struct wrapper to keep clients
    {
    public:
        Client(SOCKET Connection, int BufferSize, UINT ID);
        ~Client();
        SOCKET WorkerSocket;
        char Buffer[255];
        bool Connected;
        int RecvSize;
        UINT UID;
        void Send(char * Data);
        void Disconnect();
    };
    class Server
    {
    private:
        SOCKET WorkerSocket;
        SOCKADDR_IN EndPnt;
        UINT ID;
        int CBufferSize;
    public:
        Server(int Port, int Backlog, int BufferSize);
        ~Server();
        __event void ClientRecieved(Client* Clientr, char * RecData);
        bool Enabled;
        int Port;
        int Backlog;
        HWND ReqhWnd;
        std::map<UINT, Client*> ClientPool;
        void WaitForConnections(Server*);
        void WaitForData(Client*);
        void InvokeClientDC(UINT);
        void Startup();
        void Shutdown();
    };
}
#endif

Server.cpp:

#include "Server.h"

namespace Connections
{
    void Server::Startup()
    {
        WSADATA wsa;
        WSAStartup(0x0202, &wsa);
        this->WorkerSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        this->EndPnt.sin_addr.s_addr = ADDR_ANY;
        this->EndPnt.sin_family = AF_INET;
        this->EndPnt.sin_port = htons(this->Port);
        this->Enabled = true;
        this->ID = 0;
        bind(this->WorkerSocket, (SOCKADDR*)&this->EndPnt, sizeof(this->EndPnt));
        printf("[AsynServer]Bound..\n");
        listen(this->WorkerSocket, this->Backlog);
                CreateThread(NULL, NULL, &MainThread, this, NULL, NULL);
    }
    void Server::WaitForConnections(Server * Ser)
    {
        WSAEVENT Handler = WSA_INVALID_EVENT;
        while(Ser->Enabled)
        {
            Handler = WSACreateEvent();
            WSAEventSelect(Ser->WorkerSocket, Handler, FD_ACCEPT);
            WaitForSingleObject(Handler, INFINITE);
            SOCKET accptsock = accept(Ser->WorkerSocket, NULL, NULL);
            Client * NewClient = new Client(accptsock, 255, Ser->ID++);
            NewClient->Connected = true;
            printf("[AsynServer]Client connected.\n");
            ClientServer * OurStruct = new ClientServer();
            OurStruct->Server = Ser;
            OurStruct->Client = NewClient;
            CreateThread(NULL, NULL, &DataThread, OurStruct, NULL, NULL);
        }
    }
    void Server::WaitForData(Client * RClient)
    {
        WSAEVENT Tem = WSA_INVALID_EVENT;
        Tem = WSACreateEvent();
        WSAEventSelect(RClient->WorkerSocket, Tem, FD_READ);
        while(RClient->Connected)
        {
            WaitForSingleObject(Tem, INFINITE);
            RClient->RecvSize = recv(RClient->WorkerSocket, RClient->Buffer, 255, NULL);
            if(RClient->RecvSize > 0)
            {
                RClient->Buffer[RClient->RecvSize] = '\0';
                __raise this->ClientRecieved(RClient, RClient->Buffer);
                Sleep(50);
            }
        }
        return;
    }
    DWORD WINAPI MainThread(LPVOID lParam)
    {
        ((Server*)lParam)->WaitForConnections((Server*)lParam);
        return 0;
    }
    DWORD WINAPI DataThread(LPVOID lParam)
    {
        ClientServer * Sta = ((ClientServer*)lParam);
        Sta->Server->WaitForData(Sta->Client);
        return 0;
    }
}

Now after creating the server instance and creating the main thread, i can accept clients simultaneously and read data they send, but after TWO connections my CPU lags up till 100% usage..
I guess my method is incorrect, so my question is can someone point out a possible flaw in my code, or just point me out a decent guide for asynchronous sockets, provided that i have already searched for over a week with no results( probably my despair is hindering me from choosing the correct keywords 😐 ).
Thanks in advance and sorry about the huge piece of code, trimmed it as long as it allowed.

Mfg,
SimpleButPerfect.

Answer 1

1st bug:
In Server::WaitForConnections you create the HEVENT (Handler = WSACreateEvent() ) every time the while loop executes without destroying it. Move the HEVENT creation outside the while loop.

2nd bug:
Your buffer is 255 long (char) but you do this:
RClient->Buffer[RClient->RecvSize] = ‘\0’;
where RClient->RecvSize can be the exaclty of the size of your buffer – that means you make a classis “buffer overrun”.

I hope this helps.
Dominik