feat: udp conntrack for lan interface

[LostAttractor]

Background

Previously, the wan interface had implemented udp conntrack
This PR implemented udp conntrack for lan interface.

Checklist

• The Pull Request has been fully tested
• There's an entry in the CHANGELOGS
• There is a user-facing docs PR against https://github.com/daeuniverse/dae

Full Changelogs

• Implement udp conntrack for lan interface.

Test Result

You can use those python codes for testing,
Try to initiate a request from wan to lan. You should be able to observe that DAE skips the packet instead of routing it.
You could try to have reply packets routed to a node and observe whether dae0 has the reply packet.

server:

import socket

def udp_server(host='::', port=12345):
    """A UDP server supporting IPv6 and proper cleanup."""
    server_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
    try:
        server_socket.bind((host, port))
        print(f"UDP server listening on [{host}]:{port}")

        while True:
            message, client_address = server_socket.recvfrom(1024)  # Buffer size 1024 bytes
            print(f"Received message: {message.decode()} from {client_address}")
            server_socket.sendto(b"ACK", client_address)
    except KeyboardInterrupt:
        print("Server shutting down...")
    finally:
        server_socket.close()
        print("Socket closed.")

if __name__ == "__main__":
    udp_server()

client:

import socket

def udp_client(host="::", port=12345):
    # Detect address family based on the provided server_host
    addr_info = socket.getaddrinfo(host, port, socket.AF_UNSPEC, socket.SOCK_DGRAM)

    # Use the first address returned (IPv6 preferred if available)
    family, socktype, proto, canonname, sockaddr = addr_info[0]

    client_socket = socket.socket(family, socktype, proto)
    client_socket.settimeout(2)  # Timeout for the response

    try:
        client_socket.sendto(b"Test", sockaddr)
        print(f"Sent to {sockaddr}")

        response, server = client_socket.recvfrom(1024)
        print(f"Received response: {response.decode()} from {server}")
    except socket.timeout:
        print("No response received, server might be unreachable.")
    except Exception as e:
        print(f"An error occurred: {e}")
    finally:
        client_socket.close()
        print("Client socket closed.")

if __name__ == "__main__":
    udp_client(host="127.0.0.1", port=23339)

[jschwinger233]

Would you like to add some test as part of CI? I'm inclined to cover this in bpf unit test.

[LostAttractor]

Would you like to add some test as part of CI? I'm inclined to cover this in bpf unit test.

I write some simple python udp server/client for testing the symmetric udp datapath.
But it seems that udp conntrack is not working, even udp conntrack for wan interface in the main branch is not working
I remember it used to be worked, and I needed some time to figure it out.

I don’t know much about the CI for dae or for ebpf part. But I will have a try.

[LostAttractor]

Would you like to add some test as part of CI? I'm inclined to cover this in bpf unit test.

I write some simple python udp server/client for testing the symmetric udp datapath. But it seems that udp conntrack is not working, even udp conntrack for wan interface in the main branch is not working I remember it used to be worked, and I needed some time to figure it out.

I don’t know much about the CI for dae or for ebpf part. But I will have a try.

There is no problem with the code. My unit tests are not working correctly, but I have completed some debugging functions. Since I use ipv6 for testing, my device has multiple addresses, and SOCK_DRGAM uses the default route with SLAAC address by default (instead of symmetric routing). This is inconsistent with the address used by my DNS server by default, causing the test failed.

I have already added the python code for testing in test result section.
Should I keep this pr as draft until I finish the CI part?