IRC client experiments

server.py

from socket import create_server

MAX_SOCKETS = 1024
BUFFER_SIZE = 4096

sockets = [(0, None)] * MAX_SOCKETS
buffers = [b''] * MAX_SOCKETS

connections = []

# invert EOF behavior
def fancyrecv(socket, buffersize):
    if 0 == buffersize:
        return b''
    try:
        buffer = socket.recv(buffersize)
    except BlockingIOError:
        return b''
    if 0 == len(buffer):
        raise EOFError
    else:
        return buffer

server = create_server(("localhost", 6667))
server.setblocking(False)

# FIXME: server should gracefully handle interrupts for termination
while True:

    # handle connections
    # one per iteration

    try:
        (socket, _) = server.accept()
        socket.setblocking(False)
        i = [x[1] for x in sockets].index(None)
        sockets[i] = (1 + sockets[i][0], socket)
        buffers[i] = b''
        connections.append(i)
        print(f"received connection {i}")
    except BlockingIOError:
        pass
    except ValueError:
        socket.close()


    # read from connections

    for (n, i) in enumerate(connections):
        try:
            recvbuf = fancyrecv(sockets[i][1], BUFFER_SIZE - len(buffers[i]))
            if recvbuf:
                print(f"{i} > {recvbuf}")
            buffers[i] += recvbuf
        except EOFError:
            sockets[i][1].close()
            sockets[i] = (sockets[i][0], None)
            connections[n] = None
            print(f"closed connection {i}")

    connections = [x for x in connections if x is not None]

test_irc_connection.py

import socket, time

f = open('test_irc_connection.txt', 'w')

def write(s):
    f.write(s + '\n')
    print(s)

write("connect to localhost without a password")
with socket.socket() as server:
    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server.bind(("localhost", 6667))
    server.listen()
    (conn, addr) = server.accept()
    conn.setblocking(False)
    for i in range(3):
        try:
            buffer = conn.recv(4096)
            write(''.join(f'{i}> {x}\n' for x in buffer.decode().splitlines()))
        except BlockingIOError:
            pass
        time.sleep(0.1)

time.sleep(2)

write("connect to localhost with a password")
with socket.socket() as server:
    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server.bind(("localhost", 6667))
    server.listen()
    (conn, addr) = server.accept()
    conn.setblocking(False)
    for i in range(3):
        try:
            buffer = conn.recv(4096)
            write(''.join(f'{i}> {x}\n' for x in buffer.decode().splitlines()))
        except BlockingIOError:
            pass
        time.sleep(0.1)

time.sleep(2)