Improve server to deal with multiple clients - c++

Question

I'm trying to create a server that talks with 2 clients, 1 in each time. After the talking with one client, the server sends a message to both clients.
I found a basic code of a server, and I tried to upgrade it to accept multiple number of connections, and I saw 2 ways of it : threads, or doing array of sockets, but I couldn't understand it.
Can someone explain me how to use threads and give examples please?
This is the code :
int main()
{
WSADATA WsaDat;
if (WSAStartup(MAKEWORD(2, 2), &WsaDat) != 0)
{
std::cout << "WSA Initialization failed!\r\n";
WSACleanup();
system("PAUSE");
return 0;
}
SOCKET Socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (Socket == INVALID_SOCKET)
{
std::cout << "Socket creation failed.\r\n";
WSACleanup();
system("PAUSE");
return 0;
}
SOCKADDR_IN serverInf;
serverInf.sin_family = AF_INET;
serverInf.sin_addr.s_addr = INADDR_ANY;
serverInf.sin_port = htons(8888);
if (bind(Socket, (SOCKADDR*)(&serverInf), sizeof(serverInf)) == SOCKET_ERROR)
{
std::cout << "Unable to bind socket!\r\n";
WSACleanup();
system("PAUSE");
return 0;
}
listen(Socket, 1);
SOCKET TempSock = SOCKET_ERROR;
while (TempSock == SOCKET_ERROR)
{
std::cout << "Waiting for incoming connections...\r\n";
TempSock = accept(Socket, NULL, NULL);
}
// If iMode!=0, non-blocking mode is enabled.
u_long iMode = 1;
ioctlsocket(Socket, FIONBIO, &iMode);
Socket = TempSock;
std::cout << "Client connected!\r\n\r\n";
// Main loop
for (;;)
{
char *szMessage = "Welcome to the server!\r\n";
send(Socket, szMessage, strlen(szMessage), 0);
int nError = WSAGetLastError();
if (nError != WSAEWOULDBLOCK&&nError != 0)
{
std::cout << "Winsock error code: " << nError << "\r\n";
std::cout << "Client disconnected!\r\n";
// Shutdown our socket
shutdown(Socket, SD_SEND);
// Close our socket entirely
closesocket(Socket);
break;
}
Sleep(1000);
}
WSACleanup();
system("PAUSE");
return 0;
}

Answer 1

To do so you need one server socket and a clientsocket array like this:
SERVER:
ACCEPT:
int clientsock[2];
minsocks = 0;
numsocks = 2;
while(minsock < numsocks)
{
clientsock[minsock] = accept(serversock,
(struct sockaddr *) &clientaddr,
(socklen_t *)&clientaddrlen);
minsock++;
}
RECIEVE:
char message[6];
int data;
int limit = 6;
for(int i = 0; i < NUMSOCK; i++)
{
int in = recv(clientsock[i], &message[index], limit, 0);
if(in > 0)
{
index += in;
limit -= in;
}
else if ( in == 0 )
printf("Connection closed\n");
else
printf("recv failed: %d\n", WSAGetLastError());
}
This should be a good beginning for you to start with.
Threads - C version
pthread_t sniffer_thread;
if( pthread_create( &sniffer_thread , NULL , connection_handler , (void*) new_sock) < 0)
{
perror("could not create thread");
return 1;
}
//Now join the thread , so that we dont terminate before the thread
//pthread_join( sniffer_thread , NULL);
puts("Handler assigned");
}
/*
* This will handle connection for each client
* */
void *connection_handler(void *socket_desc)
{
//Get the socket descriptor
int sock = *(int*)socket_desc;
int read_size;
char *message , client_message[2000];
while(in != 0)
{
int in = recv(socket_desc, &client_message[index], limit, 0);
if(in > 0)
{
index += in;
limit -= in;
}
else
printf("recv failed: %d\n", WSAGetLastError());
}
//Free the socket pointer
free(socket_desc);
return 0;
}