Here's my minimal D code (server.d):


module server;

import core.thread;
import std.socket;
import std.experimental.logger;


class Server : Thread
{
private:
	Socket listener;
	int backlog;
	string address;
	ushort port;
	SocketSet sockSet;
	Socket[] clients;
	bool running;

public:
	this(ushort port, string address="") {
		super(& run);
		
		if (address == "")
			address = "DESKTOP-T49RGUJ";

		this.port = port;
		this.address = address;
		backlog = int.max;
		listener = null;
		running = false;
	}

	bool setupSocket() {
		try {
			listener = new Socket(AddressFamily.INET, SocketType.STREAM);
			listener.bind(new InternetAddress(address, port));
			sockSet = new SocketSet();
		}
		catch (Exception e) {
			log(LogLevel.critical, e.toString());
			return false;
		}
		return true;
	}

	void start() {
		if (listener is null)
		{
			if (! setupSocket())
				return;
		}
		running = true;
		if (! isRunning) super.start();
	}

	void stop() {
		running = false;
	}

private:
	void run() {
		char[1024] buffer;

		while(running) {
			sockSet.reset();
			sockSet.add(listener);
			foreach (client; clients)
				sockSet.add(client);
				if (Socket.select(sockSet, null, null)) {
					foreach (client; clients)
					{
						if (sockSet.isSet(client)) {
							auto got = client.receive(buffer);
							client.send(buffer[0 .. got]);
						}
					}
					if (sockSet.isSet(listener)) {
						auto newSocket = listener.accept();
						newSocket.send("Hello!\n");
						clients ~= newSocket;
					}

				}
		}
	}
}


And here's the simple python client (main.py):


from PyQt5.QtWidgets import QApplication, QMainWindow
import sys
import socket
import settings


if __name__ == "__main__":
    app = QApplication([])

    window = QMainWindow()
    window.show()

    host = socket.gethostname()
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    #sock.bind((host, 0))            # have os choose random available port
    print(host)
    sock.connect((host, settings.debugPort))

    try:

        # Send data
        message = 'This is the message.  It will be repeated.'
        print(sys.stderr, 'sending "%s"' % message)
        sock.sendall(message.encode())

        # Look for the response
        amount_received = 0
        amount_expected = len(message)

        while amount_received < amount_expected:
            data = sock.recv(16)
            amount_received += len(data)
            print(sys.stderr, 'received "%s"' % data)

    finally:
        print(sys.stderr, 'closing socket')
        sock.close()


    sys.exit(app.exec_())


---

The client throws:

builtins.ConnectionRefusedError: [WinError 10061] No connection could be made because the target machine actively refused it


Now, true this is python & D, but the client is generic and minimal so bear with me.

Thanks.

I've also tried 'localhost' on both sides.

I've tried opening the port for TCP with windows 10 firewall settings.  Same result.

What tool would best help me debug this?  Wireshark or is that too low level?

On Friday, 22 September 2017 at 04:25:00 UTC, Enjoys Math wrote:
> I've tried opening the port for TCP with windows 10 firewall settings.  Same result.
>
> What tool would best help me debug this?  Wireshark or is that too low level?


I've used Hercules: http://www.hw-group.com/products/hercules/index_en.html

I set up a TCP server with it, and it got the message sent from python.  Therefore there is something wrong with the D server.

On Friday, 22 September 2017 at 04:37:44 UTC, Enjoys Math wrote:
> On Friday, 22 September 2017 at 04:25:00 UTC, Enjoys Math wrote:
>> I've tried opening the port for TCP with windows 10 firewall settings.  Same result.
>>
>> What tool would best help me debug this?  Wireshark or is that too low level?
>
>
> I've used Hercules: http://www.hw-group.com/products/hercules/index_en.html
>
> I set up a TCP server with it, and it got the message sent from python.  Therefore there is something wrong with the D server.

Could it be that you need to call `super(&run);` at the end of your constructor, after your data initialisation?

On Friday, 22 September 2017 at 05:43:24 UTC, Nicholas Wilson wrote:
> On Friday, 22 September 2017 at 04:37:44 UTC, Enjoys Math wrote:
>> On Friday, 22 September 2017 at 04:25:00 UTC, Enjoys Math wrote:
>>> I've tried opening the port for TCP with windows 10 firewall settings.  Same result.
>>>
>>> What tool would best help me debug this?  Wireshark or is that too low level?
>>
>>
>> I've used Hercules: http://www.hw-group.com/products/hercules/index_en.html
>>
>> I set up a TCP server with it, and it got the message sent from python.  Therefore there is something wrong with the D server.
>
> Could it be that you need to call `super(&run);` at the end of your constructor, after your data initialisation?

Nope, the run() method gets called.

On Friday, 22 September 2017 at 04:06:08 UTC, Enjoys Math wrote:
>
> Here's my minimal D code (server.d):
> public:
> 	this(ushort port, string address="") {
> 		super(& run);
> 		
> 		if (address == "")
> 			address = "DESKTOP-T49RGUJ";
>
> 		this.port = port;
> 		this.address = address;
.........
> 			listener.bind(new InternetAddress(address, port));

It seems to me, you pass invalid address to bind(). InternetAddress takes ipv4 dot notation string x.x.x.x, and for bind you are to supply INADDR_ANY

On 23/09/2017 3:26 AM, Sergei Degtiarev wrote:
> On Friday, 22 September 2017 at 04:06:08 UTC, Enjoys Math wrote:
>>
>> Here's my minimal D code (server.d):
>> public:
>>     this(ushort port, string address="") {
>>         super(& run);
>>
>>         if (address == "")
>>             address = "DESKTOP-T49RGUJ";
>>
>>         this.port = port;
>>         this.address = address;
> .........
>>             listener.bind(new InternetAddress(address, port));
> 
> It seems to me, you pass invalid address to bind(). InternetAddress takes ipv4 dot notation string x.x.x.x, and for bind you are to supply INADDR_ANY
> 

For DNS resolution:
https://dlang.org/phobos/std_socket.html#.getAddress

On Saturday, 23 September 2017 at 02:50:25 UTC, rikki cattermole wrote:
> On 23/09/2017 3:26 AM, Sergei Degtiarev wrote:
>> On Friday, 22 September 2017 at 04:06:08 UTC, Enjoys Math wrote:
>>>
>>> Here's my minimal D code (server.d):
>>> public:
>>>     this(ushort port, string address="") {
>>>         super(& run);
>>>
>>>         if (address == "")
>>>             address = "DESKTOP-T49RGUJ";
>>>
>>>         this.port = port;
>>>         this.address = address;
>> .........
>>>             listener.bind(new InternetAddress(address, port));
>> 
>> It seems to me, you pass invalid address to bind(). InternetAddress takes ipv4 dot notation string x.x.x.x, and for bind you are to supply INADDR_ANY
>> 
>
> For DNS resolution:
> https://dlang.org/phobos/std_socket.html#.getAddress

Right, but in this case, it would be sufficient to bind socket to INADDR_ANY.