Thread: Running two UDP server simultaneously using select()

Hello to everyone,

I'm trying to run two UDP server using the function select().
Here is the code, further information follows below:

Code:

int main(void)
{
	int port1 = 1234;
	int port2 = 1322;
	fd_set read;
	const int buf = 1024;
	char data[buf];
	char data_2[buf];
	long size;
	int ret;
	int max_socket_number;

	ConnLessServer testServer1(port1); //first server is opened with given port
	ConnLessServer testServer2(port2); //second server is opened with given port

	FD_ZERO(&read);
	FD_SET(testServer1.getSocket(), &read); //returns the socket filedeskriptor
	FD_SET(testServer2.getSocket(), &read);
	
	fd_vector.push_back(testServer1.getSocket());
	fd_vector.push_back(testServer2.getSocket());
	
	max_socket_number = *max_element(fd_vector.begin(), fd_vector.end());
		
	do
	{
		ret = select(max_socket_number + 1, &read, NULL, NULL, NULL);
		std::cout << std::endl << ret << std::endl;
		if(FD_ISSET(testServer1.getSocket(), &read))
		{
			testServer1.receive(data, size, buf);
			fprintf(stdout, "Server 1: %ld %s\n", size, data);
		}
		if(FD_ISSET(testServer2.getSocket(), &read))
		{
			testServer2.receive(data_2, size, buf);
			fprintf(stdout, "Server 2: %ld %s\n", size, data_2);
		}
	}
	while (0 != strcmp(data_2, "quit"));
	
	testServer1.close();
	testServer2.close();
	
	return 0;
}

Intention is to send messages to the first socket, which works fine.
The second socket is intented to receive one message, after which the "do-while"-loop should be left.

Problem is, that the second message doesn't seem to be recognized and the message "quit" is ignored. Using a debugger, everything seems to work fine, "quit" is received and the loop is left.

In case, more information is needed, I can post some code of the member functions, I wrote myself (e.g. for the class ConnLessServer).

Best regards,
PiJ.