Asynchronous echo server (incomplete)

asynch-echo-inc.c

#undef UNICODE

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>

// Need to link with Ws2_32.lib
#pragma comment (lib, "Ws2_32.lib")
// #pragma comment (lib, "Mswsock.lib")

#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "27015"

#define NUM_WORKER_THREADS 4

struct ClientSession {
    WSAOVERLAPPED Overlapped;
    SOCKET        ClientSocket;
    char          RecvBuf[DEFAULT_BUFLEN];
    WSABUF        WsaBuf;
};

DWORD __stdcall WorkerThread(LPVOID _iocp) {
    HANDLE iocp = (HANDLE)_iocp;

    struct ClientSession * Session;

    printf(":: WORKER STARTED ::\n");
    for (;;) {
        DWORD        numberOfBytes;
        ULONG_PTR    completionKey;
        LPOVERLAPPED overlapped;
        GetQueuedCompletionStatus(
            iocp,
            &numberOfBytes,
            &completionKey,
            &overlapped,
            INFINITE
        );
        Session = (struct ClientSession *)overlapped;
        
        if (numberOfBytes == 0) {
            printf("-- Connection closed --\n");
            shutdown(Session->ClientSocket, SD_SEND);
            closesocket(Session->ClientSocket);
            free(Session);
            break;
        } else {
            DWORD Flags = 0;
            printf(".. received %d bytes\n", numberOfBytes);
            WSARecv(Session->ClientSocket, &Session->WsaBuf, 1, NULL, &Flags, overlapped, NULL);
        }
    }
    return 0;
}

int __cdecl main(void) 
{
    WSADATA wsaData;
    int iResult;

    SOCKET ListenSocket = INVALID_SOCKET;
    SOCKET ClientSocket = INVALID_SOCKET;

    struct addrinfo *result = NULL;
    struct addrinfo hints;

    int iSendResult;
    char recvbuf[DEFAULT_BUFLEN];
    int recvbuflen = DEFAULT_BUFLEN;
    
    HANDLE iocp;
    int i;
    
    struct ClientSession * Session;

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;

    // Resolve the server address and port
    iResult = getaddrinfo(NULL, DEFAULT_PORT, &hints, &result);
    if ( iResult != 0 ) {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    // Create a SOCKET for connecting to server
    ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
    if (ListenSocket == INVALID_SOCKET) {
        printf("socket failed with error: %ld\n", WSAGetLastError());
        freeaddrinfo(result);
        WSACleanup();
        return 1;
    }

    // Setup the TCP listening socket
    iResult = bind( ListenSocket, result->ai_addr, (int)result->ai_addrlen);
    if (iResult == SOCKET_ERROR) {
        printf("bind failed with error: %d\n", WSAGetLastError());
        freeaddrinfo(result);
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }

    freeaddrinfo(result);

    /* Cria o I/O completion port com factor de concorrência igual
       ao número de processadores. */
    iocp = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);

    for (i = 0; i < NUM_WORKER_THREADS; ++i) {
        CreateThread(NULL, 0, WorkerThread, iocp, 0, NULL);
    }
    
    iResult = listen(ListenSocket, SOMAXCONN);
    if (iResult == SOCKET_ERROR) {
        printf("listen failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }

    for (;;) {
        DWORD Flags = 0;

        // Accept a client socket
        ClientSocket = accept(ListenSocket, NULL, NULL);
        if (ClientSocket == INVALID_SOCKET) {
            printf("accept failed with error: %d\n", WSAGetLastError());
            closesocket(ListenSocket);
            WSACleanup();
            return 1;
        }

        printf("++ Connection established ++ \n");
        
        Session = (struct ClientSession *)malloc(sizeof (struct ClientSession));
        Session->ClientSocket = ClientSocket;
        Session->WsaBuf.buf = Session->RecvBuf;
        Session->WsaBuf.len = sizeof Session->RecvBuf;
        
        // Associar o socket ao I/O completion port
        CreateIoCompletionPort((HANDLE)ClientSocket, iocp, (ULONG_PTR)NULL, 0);
        
        // Iniciar leitura assíncrona
        ZeroMemory(&Session->Overlapped, sizeof (WSAOVERLAPPED));
        WSARecv(ClientSocket, &Session->WsaBuf, 1, NULL, &Flags, (LPWSAOVERLAPPED)Session, NULL);
    }
 
    // No longer need server socket
    closesocket(ListenSocket);
    WSACleanup();

    return 0;
}