Question

I am currently wrapping BSD sockets for the first time and also unit test my results along the way. Anyways I came across a problem while writing a simple test to test my Acceptor and TcpSocket class which is related to reusing the local host address, i.e.

Pseudocode:

//server thread
{
    //binds, listens and accepts on port 50716 on localhost
    TcpAcceptor acceptor(Resolver::fromService("50716"));
    //i get a ECONNREFUSED error inside the accept function when trying to create newSock
    TcpSocket newSock = acceptor.accept();
}

//connect in the main thread
TcpSocket connectionSocket(Resolver::resolve(Resolver::Query("localhost", "50716")));

Is it even possible to listen and connect on the same host/port? Is there any way to run a simple client/server test on the same machine/host?

Thanks!

EDIT:

Cool, things work now! Just for reference, I also noticed in the process that you don’t even need to use a thread, even if you use blocking sockets to perform a simple test, if you decouple listen from accept like this:

//server socket
TcpAcceptor acceptor;
acceptor.bind(Resolver::fromService("0"));
acceptor.listen();

//client socket, blocks until connection is established
TcpSocket clientSock(SocketAddress("127.0.0.1", acceptor.address().port()));

//accept the connection, blocks until one accept is done
TcpSocket connectionSock = acceptor.accept();

//send a test message to the client
size_t numBytesSent = connectionSock.send(ByteArray("Hello World!"));

//read the message on the client socket
ByteArray msg(12);
size_t bytesReceived = clientSock.receive(msg);
std::cout<<"Num Bytes received: "<<bytesReceived<<std::endl;
std::cout<<"Message: "<<msg<<std::endl;

building the tests like this allows for nice and simple test cases even for the blocking functions.

Answer 1

Yes, it’s possible. There is no such restriction that a server and a client must be different processes. One thread can open/listen a socket and other thread can connect to it.