🚀 go-pugleaf

Andrue Cope [TeamB] wrote:

>Actually sending a single broadcast request would probably be better
>but a minor constraint here is development time. This project isn't
>worth spending days on unfortunately and is so rarely used that the
>occasional flood of a few hundred pings going round our network can be
>tolerated :)

	server sets up a TCP listen()
	client and server sets up a UDP Recv Any
	client UDP broadcasts a datagram with a "request" flag in it.
	client sees the datagram, ignores it because it is a request.
	server sees the datagram, that it is a request, and if
		not-busy  replies with a datagram "answer" datagram.
	server sees the answer datagram and ignores it.
	client sees the answer datgram and logs it.
	After 1 second, client displays the list of answers.
	client selects one and TCP connects to it.
	server accepts() incoming connection
	server turns off it's UDP Recv Any.

Since you have TCP running, here's UDPListen...

static	SOCKET	ListenSocket;	//global so main can use it
struct	UDPPACKET	u;	// define UDPPACKET as you like

/* Thread */
#pragma	argsused
static unsigned long _stdcall UdpListeningThread(void*x)
{
struct	 sockaddr_in	ListenAddr;
struct	 sockaddr_in	SenderAddr;
	int		SenderAddrSize = sizeof(SenderAddr);
	int		t = TRUE;
	int		received;

//-----------------------------------------------
// Create a receiver socket to receive datagrams
//Notify("Creating UDP Socket");
ListenSocket = socket( AF_INET, SOCK_DGRAM, IPPROTO_UDP );
if( ListenSocket != INVALID_SOCKET )
{
    /* need this for multiple listeners */
    if( 0 == setsockopt( ListenSocket, SOL_SOCKET,
	 SO_REUSEADDR, (char*)&t, sizeof(t) ))
    {
	//-----------------------------------------------
	// Bind the socket to any address and the specified port.
	ListenAddr.sin_family = AF_INET;
	ListenAddr.sin_port = htons( UDP_CS_PORT );
	ListenAddr.sin_addr.s_addr = htonl( INADDR_ANY );

	//Notify("Binding UDP Socket");
	if( SOCKET_ERROR  != bind( ListenSocket,
			 (SOCKADDR *) &ListenAddr,
			 sizeof(ListenAddr) ) )
	{
	    while( !Canceled )
	    {
		Aborted = FALSE;
		//-----------------------------------------------
		// Call the recvfrom function to receive datagrams on
		// the bound socket.
		// This blocks. Close ListenSocket from MainThread to
		// blast us out.
		//Notify( "Ready to Receive Connections..." );
		received = recvfrom( ListenSocket, (char*)&u,
				 sizeof(UDPPACKET), 0,
				 (SOCKADDR *)&SenderAddr,
				 &SenderAddrSize );

We know who this datagram came from:
	wsprintf( entry,"Received %d bytes from %s:%d - %.11s\r\n",
			received,
			inet_ntoa(SenderAddr.sin_addr),
			ntohs(SenderAddr.sin_port),
			 &u.Name );

If you have the server pass it's name in the datagram (u.Name), it'll
make the picklist easier.