File Server via Winsock (S->C)

// FileServer.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include "stdio.h"
#include "conio.h"
#include "winsock2.h"
#include "ws2tcpip.h"

struct Client
{
    SOCKET c;
    SOCKADDR_IN cAddr;
};

SOCKET s;
SOCKADDR_IN sAddr;
int nClient = 0;
Client *fClient[1024];

DWORD WINAPI ReceiverThread(LPVOID Param) {
    int i = (int)Param;
    int j = 0;
    int len;
    int filesize = 0;
    char buf[1024];
    char msg[1024];

    printf("Client %d da ket noi.\n", i);
    while (true) {
        len = recv(fClient[i]->c, buf, 1024, 0);
        if (len > 0) {
            buf[len-1] = 0;
            if (strnicmp(buf, "GET ", 4) == 0) {
                char filename[100];
                memcpy(filename, &buf[4], strlen(buf) - 4);
                filename[strlen(buf) - 4] = 0;
                FILE *fp = fopen(filename, "rb");
                if (fp != NULL) {

                    fseek(fp, 0, SEEK_END);
                    filesize = ftell(fp);
                    fseek(fp, 0, SEEK_END);
                    sprintf(msg, "%d", filesize);
                    send(fClient[i]->c, msg, strlen(msg), 0);

                    rewind(fp);
                    int checksize = 0;
                    char* buffer;
                    buffer = (char*)malloc(4096);
                    while (checksize < filesize) {
                        int Read = fread_s(buffer, 4096, sizeof(char), 4096, fp);
                        int Sent = send(fClient[i]->c, buffer, Read, 0);
                        checksize += Sent;
                    }
                }
                else {
                    send(fClient[i]->c, "FAILED file not found.\n", sizeof("FAILED file not found.\n"), 0);
                }
            }
            else {
                send(fClient[i]->c, "FAILED Unknown command.\n", sizeof("FAILED Unknown command.\n"), 0);
            }
        }
    }

    return 0;
}

int main()
{
    WSADATA wsadata;
    int ret = WSAStartup(MAKEWORD(2, 2), &wsadata);

    s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    sAddr.sin_family = AF_INET;
    sAddr.sin_addr.s_addr = ntohs(INADDR_ANY);
    sAddr.sin_port = htons(10008);

    ret = bind(s, (sockaddr*)&sAddr, sizeof(sAddr));
    ret = listen(s, 16);

    printf("Waiting for client...\n");

    int clientlen = sizeof(SOCKADDR_IN);
    int i;
    bool tachluong = false;
    for (i = 0; i < 1024; i++) fClient[i] = 0;

    while (true) {
        for (i = 0; i < nClient; i++)
            if (fClient[i] == 0) break;
        fClient[i] = new Client;
        fClient[i]->c = accept(s, (sockaddr*)&fClient[i]->cAddr, &clientlen);
        CreateThread(0, 0, ReceiverThread, (LPVOID)i, 0, 0);
        if (i == nClient) nClient++;
    }

    closesocket(s);
    WSACleanup();
    getch();
    return 0;
}