A very simple IRC bot. It does nothing.

ircbot.py

import re
import socket

from tornado import ioloop
from tornado import iostream


RE_ORIGIN = re.compile(r'([^!]*)!?([^@]*)@?(.*)')


def parse_origin(raw_origin):
    """Parse a string similar to 'FSX!~FSX@hostname'
    into 'FSX', '~FSX' and 'hostname'"""

    match = RE_ORIGIN.match(raw_origin or '')
    return match.groups() # Nickname, username, hostname


class IrcClient(object):

    def __init__(self, host, port, ssl=False):
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)

        if ssl:
            self._stream = iostream.SSLIOStream(s)
        else:
            self._stream = iostream.IOStream(s)

        self._stream.connect((host, port), self._handle_connect)

    def _handle_connect(self):
        # Send nick and channels

        self._write(('NICK', 'TestBot'))
        self._write(('USER', 'TestBot', '+iw', 'TestBot'), 'TestBot')
        self._write(('JOIN',), '#somerandomchannel')

        self._stream.read_until('\r\n', self._on_read)

    def _on_read(self, data):
        print '<< %r' % data

        # Split source from data
        if data.startswith(':'):
            source, data = data[1:].split(' ', 1)
        else:
            source = None

        # Split arguments from message
        if ' :' in data:
            args, data = data.split(' :', 1)
        else:
            args, data = data, ''
        args = args.split()

        # Parse the source (where the data comes from)
        nickname, username, hostname = parse_origin(source)

        # Respond to server ping to keep connection alive
        if args[0] == 'PING':
            self._write(('PONG', data))

        self._stream.read_until('\r\n', self._on_read)

    def _write(self, args, text=None):
        if text is not None:
            self._stream.write('%s :%s\r\n' % (' '.join(args), text))
        else:
            self._stream.write('%s\r\n' % ' '.join(args))


if __name__ == '__main__':
    IrcClient('irc.rizon.net', 9999, True)
    ioloop.IOLoop.instance().start()