Thread: recieve data, then send data to all other clients

i have just slightly modified the code from gametutorials.com on allowing multiple connections to a server. what i tried to do with this code is, when a client sends a message to the server the server sends that message to all other clients connected to the server. I thought that this code would work:

Code:

#pragma comment(lib, "wsock32.lib")
#include <winsock.h>
#include <windows.h>
int startupServerForListening(unsigned short port);
void shutdownServer(int socket);
HANDLE threadHandle;
HANDLE mutexHandle;
FD_SET allsockets;
bool gQuitFlag = false;

void acceptingThreadProcedure(int* serverSocket) {
	
	int mySocket = *serverSocket;
	
	for (;;) {
		unsigned int clientSocket = accept(mySocket, 0, 0);
		
		if (clientSocket == SOCKET_ERROR) {
			MessageBox(0,"Accept Failed!","",0);
			gQuitFlag = true;
			return;
			
		} else {
			
			WaitForSingleObject(mutexHandle, INFINITE);
			FD_SET(clientSocket, &allsockets);
			ReleaseMutex(mutexHandle);
			MessageBox(0,"Client Connected","",0);
		}
	}
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
				   LPSTR lpCmdLine, int nCmdShow){
	int serverSocket;
	
	serverSocket = startupServerForListening(7654);
	
	if (serverSocket == -1) {
		MessageBox(0,"ERROR","",0);
		return 0;
	}
	mutexHandle = CreateMutex(NULL, false, NULL);
	if (mutexHandle == NULL) {
		MessageBox(0,"Error creating mutex","",0);
		shutdownServer(serverSocket);
		return 0;
	}
	int threadId;
	threadHandle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)acceptingThreadProcedure, &serverSocket, 0, (LPDWORD)&threadId);
	if (threadHandle == NULL) {
		MessageBox(0,"ERROR STARTING LISTENING THREAD","",0);
		shutdownServer(serverSocket);
		return 0;
	}
	Sleep(1000);
	FD_ZERO(&allsockets);
	
	for (;;) {
		if (gQuitFlag) {
			break;
		}
		Sleep(400);
		
		WaitForSingleObject(mutexHandle, INFINITE);
		FD_SET tmpallsockets = allsockets;
		ReleaseMutex(mutexHandle);
		if (tmpallsockets.fd_count == 0) {
			continue;
		}
		timeval waitTime;
		waitTime.tv_sec = 0;
		waitTime.tv_usec = 0;
		int result = select(tmpallsockets.fd_count, &tmpallsockets, NULL, NULL, &waitTime);
		if (result == 0) {
			continue;
		}
		
		if (result == SOCKET_ERROR) {
			MessageBox(0,"ERROR IN SELECT", "",0);
			continue;
		}
		
		for (unsigned int i = 0; i < tmpallsockets.fd_count; i++) {
			
			unsigned int clientSocket = tmpallsockets.fd_array[i];
			int nBytes;
#define MAX_MESSAGE_SIZE 4096
			char buffer[MAX_MESSAGE_SIZE];
			
			nBytes = recv(clientSocket, buffer, sizeof(buffer), 0);
			if (nBytes == SOCKET_ERROR) {
				int error = WSAGetLastError();
				if (error == WSAECONNRESET) {
					WaitForSingleObject(mutexHandle, INFINITE);
					FD_CLR(clientSocket, &allsockets);
					ReleaseMutex(mutexHandle);
					closesocket(clientSocket);
					
					MessageBox(0,"A client disconnected","",0);
					
					continue;
					
				} else {
					MessageBox(0,"SEND FAILED, SERVER TERMINATING","",0);
					gQuitFlag = true;
					break;
					
				}
			}
			if (nBytes == 0) {
				WaitForSingleObject(mutexHandle, INFINITE);
				FD_CLR(clientSocket, &allsockets);
				ReleaseMutex(mutexHandle);
				closesocket(clientSocket);
				MessageBox(0,"A CLIENT DISCONNECTED","",0);
				continue;
			}
			buffer[sizeof(buffer)] = '\0';
			for (i=0; i < tmpallsockets.fd_count; i++) {
				unsigned int clientSocketout = tmpallsockets.fd_array[i];
				if(clientSocket == SOCKET_ERROR){
					MessageBox(0,"error","",0);
				}
				nBytes = send(clientSocketout, buffer, sizeof(buffer), 0);
				MessageBox(0,"message sent","",0);
				if (nBytes == SOCKET_ERROR) {
					int error = WSAGetLastError();
					if (error == WSAECONNRESET) {
						WaitForSingleObject(mutexHandle, INFINITE);
						FD_CLR(clientSocket, &allsockets);
						ReleaseMutex(mutexHandle);
						closesocket(clientSocket);
						
						MessageBox(0,"A client disconnected","",0);
						
						continue;
						
					} else {
						MessageBox(0,"SEND FAILED, SERVER TERMINATING","",0);
						gQuitFlag = true;
						break;
						
					}
				}
				if (nBytes == 0) {
					WaitForSingleObject(mutexHandle, INFINITE);
					FD_CLR(clientSocket, &allsockets);
					ReleaseMutex(mutexHandle);
					closesocket(clientSocket);
					MessageBox(0,"A CLIENT DISCONNECTED","",0);
					continue;
				}
				
			}
		}
	}
	shutdownServer(serverSocket);
	return 0;
}

int startupServerForListening(unsigned short port) {
    int error;
	WSAData wsaData;
	if ((error = WSAStartup(MAKEWORD(2, 2), &wsaData)) == SOCKET_ERROR) {
		return -1;
	}
	int mySocket = socket(AF_INET, SOCK_STREAM, 0);
	if (mySocket == SOCKET_ERROR) {
		return -1;
	}
	struct sockaddr_in server;
	server.sin_family = AF_INET;
	server.sin_port = htons(port);
	server.sin_addr.s_addr = INADDR_ANY;
	if (bind(mySocket, (sockaddr*)&server, sizeof(server)) == SOCKET_ERROR) {
		closesocket(mySocket);
		return -1;
	}
	if (listen(mySocket, 5) == SOCKET_ERROR) {
		closesocket(mySocket);
		return -1;
	}
	
	return mySocket;
}

void shutdownServer(int socket) {
	
	WaitForSingleObject(threadHandle, INFINITE);
	CloseHandle(threadHandle);
	CloseHandle(mutexHandle);
	closesocket(socket);
	WSACleanup();
}

but it doesn't, it recieves the message from a client then sends that same message back to the client that sent it, but to nobody else, just the client that sent it. and i really don't know why it's doing it.
Could you please tell me why it's doing what it is?