CreateThread loop - c

Question

I'm trying make asynchronous server listener with C++ .I can write simple listener without asynchronous but now i have problem with CreateThread.
For example if client has been connected console gives me result about this + sniffer can fix it, after 10 sec client must send me again same packet with different data. my console does not gives me result about that packet but sniffer can see that packet... please if anyone can see my problem explain me.
#include <winsock2.h>
#include <windows.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
DWORD WINAPI SocketHandler(void*);
int main(int argv, char** argc){
//The port you want the server to listen on
int host_port = 7878;
//Initialize socket support WINDOWS ONLY!
unsigned short wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 2, 2 );
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 || ( LOBYTE( wsaData.wVersion ) != 2 ||
HIBYTE( wsaData.wVersion ) != 2 )) {
fprintf(stderr, "Could not find useable sock dll %d\n",WSAGetLastError());
}
//Initialize sockets and set any options
int hsock;
int * p_int ;
hsock = socket(AF_INET, SOCK_STREAM, 0);
if(hsock == -1){
printf("Error initializing socket %d\n",WSAGetLastError());
}
p_int = (int*)malloc(sizeof(int));
*p_int = 1;
if( (setsockopt(hsock, SOL_SOCKET, SO_REUSEADDR, (char*)p_int, sizeof(int)) == -1 )||
(setsockopt(hsock, SOL_SOCKET, SO_KEEPALIVE, (char*)p_int, sizeof(int)) == -1 ) ){
printf("Error setting options %d\n", WSAGetLastError());
free(p_int);
}
free(p_int);
//Bind and listen
struct sockaddr_in my_addr;
my_addr.sin_family = AF_INET ;
my_addr.sin_port = htons(host_port);
memset(&(my_addr.sin_zero), 0, 8);
my_addr.sin_addr.s_addr = INADDR_ANY ;
if( bind( hsock, (struct sockaddr*)&my_addr, sizeof(my_addr)) == -1 ){
fprintf(stderr,"Error binding to socket, make sure nothing else is listening on this port %d\n",WSAGetLastError());
}
if(listen( hsock, 10) == -1 ){
fprintf(stderr, "Error listening %d\n",WSAGetLastError());
}
//Now lets to the server stuff
int* csock;
sockaddr_in sadr;
int addr_size = sizeof(SOCKADDR);
while(true){
printf("waiting for a connection\n");
csock = (int*)malloc(sizeof(int));
if((*csock = accept( hsock, (SOCKADDR*)&sadr, &addr_size))!= INVALID_SOCKET ){
printf("Received connection from %s",inet_ntoa(sadr.sin_addr));
CreateThread(0,0,&SocketHandler, (void*)csock , 0,0);
}
else{
fprintf(stderr, "Error accepting %d\n",WSAGetLastError());
}
}
}
DWORD WINAPI SocketHandler(void* lp){
int *csock = (int*)lp;
char buffer[1024];
int buffer_len = 1024;
int bytecount;
memset(buffer, 0, buffer_len);
if((bytecount = recv(*csock, buffer, buffer_len, 0))==SOCKET_ERROR){
fprintf(stderr, "Error receiving data %d\n", WSAGetLastError());
}
printf("Received bytes %d\n Received string \"%s\"\n", bytecount, buffer);
char buff[1] = {0x11};
if((bytecount = send(*csock, buff, 1, 0))==SOCKET_ERROR){
fprintf(stderr, "Error sending data %d\n", WSAGetLastError());
}
printf("Sent bytes: %d. Send Message: %s\n ", bytecount,buff);
free(csock);
}

Answer 1

A race condition is most likely the cause of your problem. You declare csock on the stack and then pass it to SocketHandler. The trouble is, it's quite possible that the value of csock changes before SocketHandler gets it and makes a copy since csock = accept() is in a loop. The solution is to dynamically allocate csock using malloc and then have SocketHandler free it.
Even if this isn't the cause of your specific problem, this code can never be reliable until you fix that.

Answer 2

CreateThread doesn't loop or anything. You need to put the code in there inside a loop. Something like this:
DWORD WINAPI SocketHandler(void* lp) {
for(;;) {
/* Code here */
}
return EXIT_SUCCESS;
}