http2irc/http2irc.py

import aiohttp
import aiohttp.web
import asyncio
import base64
import collections
import concurrent.futures
import importlib.util
import inspect
import itertools
import logging
import os.path
import signal
import ssl
import string
import sys
import toml


logger = logging.getLogger('http2irc')
SSL_CONTEXTS = {'yes': True, 'no': False, 'insecure': ssl.SSLContext()}


class InvalidConfig(Exception):
	'''Error in configuration file'''


def is_valid_pem(path, withCert):
	'''Very basic check whether something looks like a valid PEM certificate'''
	try:
		with open(path, 'rb') as fp:
			contents = fp.read()

		# All of these raise exceptions if something's wrong...
		if withCert:
			assert contents.startswith(b'-----BEGIN CERTIFICATE-----\n')
			endCertPos = contents.index(b'-----END CERTIFICATE-----\n')
			base64.b64decode(contents[28:endCertPos].replace(b'\n', b''), validate = True)
			assert contents[endCertPos + 26:].startswith(b'-----BEGIN PRIVATE KEY-----\n')
		else:
			assert contents.startswith(b'-----BEGIN PRIVATE KEY-----\n')
			endCertPos = -26 # Please shoot me.
		endKeyPos = contents.index(b'-----END PRIVATE KEY-----\n')
		base64.b64decode(contents[endCertPos + 26 + 28: endKeyPos].replace(b'\n', b''), validate = True)
		assert contents[endKeyPos + 26:] == b''
		return True
	except: # Yes, really
		return False


class Config(dict):
	def __init__(self, filename):
		super().__init__()
		self._filename = filename

		with open(self._filename, 'r') as fp:
			obj = toml.load(fp)

		# Sanity checks
		if any(x not in ('logging', 'irc', 'web', 'maps') for x in obj.keys()):
			raise InvalidConfig('Unknown sections found in base object')
		if any(not isinstance(x, collections.abc.Mapping) for x in obj.values()):
			raise InvalidConfig('Invalid section type(s), expected objects/dicts')
		if 'logging' in obj:
			if any(x not in ('level', 'format') for x in obj['logging']):
				raise InvalidConfig('Unknown key found in log section')
			if 'level' in obj['logging'] and obj['logging']['level'] not in ('DEBUG', 'INFO', 'WARNING', 'ERROR'):
				raise InvalidConfig('Invalid log level')
			if 'format' in obj['logging']:
				if not isinstance(obj['logging']['format'], str):
					raise InvalidConfig('Invalid log format')
				try:
					#TODO: Replace with logging.Formatter's validate option (3.8+); this test does not cover everything that could be wrong (e.g. invalid format spec or conversion)
					# This counts the number of replacement fields. Formatter.parse yields tuples whose second value is the field name; if it's None, there is no field (e.g. literal text).
					assert sum(1 for x in string.Formatter().parse(obj['logging']['format']) if x[1] is not None) > 0
				except (ValueError, AssertionError) as e:
					raise InvalidConfig('Invalid log format: parsing failed') from e
		if 'irc' in obj:
			if any(x not in ('host', 'port', 'ssl', 'nick', 'real', 'certfile', 'certkeyfile') for x in obj['irc']):
				raise InvalidConfig('Unknown key found in irc section')
			if 'host' in obj['irc'] and not isinstance(obj['irc']['host'], str): #TODO: Check whether it's a valid hostname
				raise InvalidConfig('Invalid IRC host')
			if 'port' in obj['irc'] and (not isinstance(obj['irc']['port'], int) or not 1 <= obj['irc']['port'] <= 65535):
				raise InvalidConfig('Invalid IRC port')
			if 'ssl' in obj['irc'] and obj['irc']['ssl'] not in ('yes', 'no', 'insecure'):
				raise InvalidConfig(f'Invalid IRC SSL setting: {obj["irc"]["ssl"]!r}')
			if 'nick' in obj['irc'] and not isinstance(obj['irc']['nick'], str): #TODO: Check whether it's a valid nickname
				raise InvalidConfig('Invalid IRC nick')
			if len(IRCClientProtocol.nick_command(obj['irc']['nick'])) > 510:
				raise InvalidConfig('Invalid IRC nick: NICK command too long')
			if 'real' in obj['irc'] and not isinstance(obj['irc']['real'], str):
				raise InvalidConfig('Invalid IRC realname')
			if len(IRCClientProtocol.user_command(obj['irc']['nick'], obj['irc']['real'])) > 510:
				raise InvalidConfig('Invalid IRC nick/realname combination: USER command too long')
			if ('certfile' in obj['irc']) != ('certkeyfile' in obj['irc']):
				raise InvalidConfig('Invalid IRC cert config: needs both certfile and certkeyfile')
			if 'certfile' in obj['irc']:
				if not isinstance(obj['irc']['certfile'], str):
					raise InvalidConfig('Invalid certificate file: not a string')
				obj['irc']['certfile'] = os.path.abspath(os.path.join(os.path.dirname(self._filename), obj['irc']['certfile']))
				if not os.path.isfile(obj['irc']['certfile']):
					raise InvalidConfig('Invalid certificate file: not a regular file')
				if not is_valid_pem(obj['irc']['certfile'], True):
					raise InvalidConfig('Invalid certificate file: not a valid PEM cert')
			if 'certkeyfile' in obj['irc']:
				if not isinstance(obj['irc']['certkeyfile'], str):
					raise InvalidConfig('Invalid certificate key file: not a string')
				obj['irc']['certkeyfile'] = os.path.abspath(os.path.join(os.path.dirname(self._filename), obj['irc']['certkeyfile']))
				if not os.path.isfile(obj['irc']['certkeyfile']):
					raise InvalidConfig('Invalid certificate key file: not a regular file')
				if not is_valid_pem(obj['irc']['certkeyfile'], False):
					raise InvalidConfig('Invalid certificate key file: not a valid PEM key')
		if 'web' in obj:
			if any(x not in ('host', 'port') for x in obj['web']):
				raise InvalidConfig('Unknown key found in web section')
			if 'host' in obj['web'] and not isinstance(obj['web']['host'], str): #TODO: Check whether it's a valid hostname (must resolve I guess?)
				raise InvalidConfig('Invalid web hostname')
			if 'port' in obj['web'] and (not isinstance(obj['web']['port'], int) or not 1 <= obj['web']['port'] <= 65535):
				raise InvalidConfig('Invalid web port')
		if 'maps' in obj:
			seenWebPaths = {}
			for key, map_ in obj['maps'].items():
				if not isinstance(key, str) or not key:
					raise InvalidConfig(f'Invalid map key {key!r}')
				if not isinstance(map_, collections.abc.Mapping):
					raise InvalidConfig(f'Invalid map for {key!r}')
				if any(x not in ('webpath', 'ircchannel', 'auth', 'module', 'moduleargs', 'overlongmode') for x in map_):
					raise InvalidConfig(f'Unknown key(s) found in map {key!r}')

				if 'webpath' not in map_:
					map_['webpath'] = f'/{key}'
				if not isinstance(map_['webpath'], str):
					raise InvalidConfig(f'Invalid map {key!r} web path: not a string')
				if not map_['webpath'].startswith('/'):
					raise InvalidConfig(f'Invalid map {key!r} web path: does not start at the root')
				if map_['webpath'] in seenWebPaths:
					raise InvalidConfig(f'Invalid map {key!r} web path: collides with map {seenWebPaths[map_["webpath"]]!r}')
				seenWebPaths[map_['webpath']] = key

				if 'ircchannel' not in map_:
					map_['ircchannel'] = f'#{key}'
				if not isinstance(map_['ircchannel'], str):
					raise InvalidConfig(f'Invalid map {key!r} IRC channel: not a string')
				if not map_['ircchannel'].startswith('#') and not map_['ircchannel'].startswith('&'):
					raise InvalidConfig(f'Invalid map {key!r} IRC channel: does not start with # or &')
				if any(x in map_['ircchannel'][1:] for x in (' ', '\x00', '\x07', '\r', '\n', ',')):
					raise InvalidConfig(f'Invalid map {key!r} IRC channel: contains forbidden characters')
				if len(map_['ircchannel']) > 200:
					raise InvalidConfig(f'Invalid map {key!r} IRC channel: too long')

				if 'auth' in map_:
					if map_['auth'] is not False and not isinstance(map_['auth'], str):
						raise InvalidConfig(f'Invalid map {key!r} auth: must be false or a string')
					if isinstance(map_['auth'], str) and ':' not in map_['auth']:
							raise InvalidConfig(f'Invalid map {key!r} auth: must contain a colon')

				if 'module' in map_:
					# If the path is relative, try to evaluate it relative to either the config file or this file; some modules are in the repo, but this also allows overriding them.
					for basePath in (os.path.dirname(self._filename), os.path.dirname(__file__)):
						if os.path.isfile(os.path.join(basePath, map_['module'])):
							map_['module'] = os.path.abspath(os.path.join(basePath, map_['module']))
							break
					else:
						raise InvalidConfig(f'Module {map_["module"]!r} in map {key!r} is not a file')
				if 'moduleargs' in map_:
					if not isinstance(map_['moduleargs'], list):
						raise InvalidConfig(f'Invalid module args for {key!r}: not an array')
					if 'module' not in map_:
						raise InvalidConfig(f'Module args cannot be specified without a module for {key!r}')
				if 'overlongmode' in map_:
					if not isinstance(map_['overlongmode'], str):
						raise InvalidConfig(f'Invalid map {key!r} overlongmode: not a string')
					if map_['overlongmode'] not in ('split', 'truncate'):
						raise InvalidConfig(f'Invalid map {key!r} overlongmode: unsupported value')

		# Default values
		finalObj = {'logging': {'level': 'INFO', 'format': '{asctime} {levelname} {name} {message}'}, 'irc': {'host': 'irc.hackint.org', 'port': 6697, 'ssl': 'yes', 'nick': 'h2ibot', 'real': 'I am an http2irc bot.', 'certfile': None, 'certkeyfile': None}, 'web': {'host': '127.0.0.1', 'port': 8080}, 'maps': {}}

		# Fill in default values for the maps
		for key, map_ in obj['maps'].items():
			# webpath is already set above for duplicate checking
			# ircchannel is set above for validation
			if 'auth' not in map_:
				map_['auth'] = False
			if 'module' not in map_:
				map_['module'] = None
			if 'moduleargs' not in map_:
				map_['moduleargs'] = []
			if 'overlongmode' not in map_:
				map_['overlongmode'] = 'split'

		# Load modules
		modulePaths = {} # path: str -> (extraargs: int, key: str)
		for key, map_ in obj['maps'].items():
			if map_['module'] is not None:
				if map_['module'] not in modulePaths:
					modulePaths[map_['module']] = (len(map_['moduleargs']), key)
				elif modulePaths[map_['module']][0] != len(map_['moduleargs']):
					raise InvalidConfig(f'Module {map_["module"]!r} process function extra argument inconsistency between {key!r} and {modulePaths[map_["module"]][1]!r}')
		modules = {} # path: str -> module: module
		for i, (path, (extraargs, _)) in enumerate(modulePaths.items()):
			try:
				# Build a name that is virtually guaranteed to be unique across a process.
				# Although importlib does not seem to perform any caching as of CPython 3.8, this is not guaranteed by spec.
				spec = importlib.util.spec_from_file_location(f'http2irc-module-{id(self)}-{i}', path)
				module = importlib.util.module_from_spec(spec)
				spec.loader.exec_module(module)
			except Exception as e: # This is ugly, but exec_module can raise virtually any exception
				raise InvalidConfig(f'Loading module {path!r} failed: {e!s}')
			if not hasattr(module, 'process'):
				raise InvalidConfig(f'Module {path!r} does not have a process function')
			if not inspect.iscoroutinefunction(module.process):
				raise InvalidConfig(f'Module {path!r} process attribute is not a coroutine function')
			nargs = len(inspect.signature(module.process).parameters)
			if nargs != 1 + extraargs:
				raise InvalidConfig(f'Module {path!r} process function takes {nargs} parameter{"s" if nargs > 1 else ""}, not {1 + extraargs}')
			modules[path] = module

		# Replace module value in maps
		for map_ in obj['maps'].values():
			if 'module' in map_ and map_['module'] is not None:
				map_['module'] = modules[map_['module']]

		# Merge in what was read from the config file and set keys on self
		for key in ('logging', 'irc', 'web', 'maps'):
			if key in obj:
				finalObj[key].update(obj[key])
			self[key] = finalObj[key]

	def __repr__(self):
		return f'<Config(logging={self["logging"]!r}, irc={self["irc"]!r}, web={self["web"]!r}, maps={self["maps"]!r})>'

	def reread(self):
		return Config(self._filename)


class MessageQueue:
	# An object holding onto the messages received from nodeping
	# This is effectively a reimplementation of parts of asyncio.Queue with some specific additional code.
	# Unfortunately, asyncio.Queue's extensibility (_init, _put, and _get methods) is undocumented, so I don't want to rely on that.
	# Differences to asyncio.Queue include:
	#  - No maxsize
	#  - No put coroutine (not necessary since the queue can never be full)
	#  - Only one concurrent getter
	#  - putleft_nowait to put to the front of the queue (so that the IRC client can put a message back when delivery fails)

	logger = logging.getLogger('http2irc.MessageQueue')

	def __init__(self):
		self._getter = None  # None | asyncio.Future
		self._queue = collections.deque()

	async def get(self):
		if self._getter is not None:
			raise RuntimeError('Cannot get concurrently')
		if len(self._queue) == 0:
			self._getter = asyncio.get_running_loop().create_future()
			self.logger.debug('Awaiting getter')
			try:
				await self._getter
			except asyncio.CancelledError:
				self.logger.debug('Cancelled getter')
				self._getter = None
				raise
			self.logger.debug('Awaited getter')
			self._getter = None
		# For testing the cancellation/putting back onto the queue
		#self.logger.debug('Delaying message queue get')
		#await asyncio.sleep(3)
		#self.logger.debug('Done delaying')
		return self.get_nowait()

	def get_nowait(self):
		if len(self._queue) == 0:
			raise asyncio.QueueEmpty
		return self._queue.popleft()

	def put_nowait(self, item):
		self._queue.append(item)
		if self._getter is not None and not self._getter.cancelled():
			self._getter.set_result(None)

	def putleft_nowait(self, *item):
		self._queue.extendleft(reversed(item))
		if self._getter is not None and not self._getter.cancelled():
			self._getter.set_result(None)

	def qsize(self):
		return len(self._queue)


class IRCClientProtocol(asyncio.Protocol):
	logger = logging.getLogger('http2irc.IRCClientProtocol')

	def __init__(self, messageQueue, connectionClosedEvent, loop, config, channels):
		self.messageQueue = messageQueue
		self.connectionClosedEvent = connectionClosedEvent
		self.loop = loop
		self.config = config
		self.buffer = b''
		self.connected = False
		self.channels = channels # Currently joined/supposed-to-be-joined channels; set(str)
		self.unconfirmedMessages = []
		self.pongReceivedEvent = asyncio.Event()
		self.sasl = bool(self.config['irc']['certfile'] and self.config['irc']['certkeyfile'])
		self.authenticated = False
		self.usermask = None

	@staticmethod
	def nick_command(nick: str):
		return b'NICK ' + nick.encode('utf-8')

	@staticmethod
	def user_command(nick: str, real: str):
		nickb = nick.encode('utf-8')
		return b'USER ' + nickb + b' ' + nickb + b' ' + nickb + b' :' + real.encode('utf-8')

	def _maybe_set_usermask(self, usermask):
		if b'@' in usermask and b'!' in usermask.split(b'@')[0] and all(x not in usermask for x in (b' ', b'*', b'#', b'&')):
			self.usermask = usermask
			self.logger.debug(f'Usermask is now {usermask!r}')

	def connection_made(self, transport):
		self.logger.info('IRC connected')
		self.transport = transport
		self.connected = True
		if self.sasl:
			self.send(b'CAP REQ :sasl')
		self.send(self.nick_command(self.config['irc']['nick']))
		self.send(self.user_command(self.config['irc']['nick'], self.config['irc']['real']))

	def _send_join_part(self, command, channels):
		'''Split a JOIN or PART into multiple messages as necessary'''
		# command: b'JOIN' or b'PART'; channels: set[str]

		channels = [x.encode('utf-8') for x in channels]
		if len(command) + sum(1 + len(x) for x in channels) <= 510: # Total length = command + (separator + channel name for each channel, where the separator is a space for the first and then a comma)
			# Everything fits into one command.
			self.send(command + b' ' + b','.join(channels))
			return

		# List too long, need to split.
		limit = 510 - len(command)
		lengths = [1 + len(x) for x in channels]  # separator + channel name
		chanLengthAcceptable = [l <= limit for l in lengths]
		if not all(chanLengthAcceptable):
			# There are channel names that are too long to even fit into one message on their own; filter them out and warn about them.
			# This should never happen since the config reader would already filter it out.
			tooLongChannels = [x for x, a in zip(channels, chanLengthAcceptable) if not a]
			channels = [x for x, a in zip(channels, chanLengthAcceptable) if a]
			lengths = [l for l, a in zip(lengths, chanLengthAcceptable) if a]
			for channel in tooLongChannels:
				self.logger.warning(f'Cannot {command} {channel}: name too long')
		runningLengths = list(itertools.accumulate(lengths))  # entry N = length of all entries up to and including channel N, including separators
		offset = 0
		while channels:
			i = next((x[0] for x in enumerate(runningLengths) if x[1] - offset > limit), -1)
			if i == -1: # Last batch
				i = len(channels)
			self.send(command + b' ' + b','.join(channels[:i]))
			offset = runningLengths[i-1]
			channels = channels[i:]
			runningLengths = runningLengths[i:]

	def update_channels(self, channels: set):
		channelsToPart = self.channels - channels
		channelsToJoin = channels - self.channels
		self.channels = channels

		if self.connected:
			if channelsToPart:
				self._send_join_part(b'PART', channelsToPart)
			if channelsToJoin:
				self._send_join_part(b'JOIN', channelsToJoin)

	def send(self, data):
		self.logger.debug(f'Send: {data!r}')
		if len(data) > 510:
			raise RuntimeError(f'IRC message too long ({len(data)} > 510): {data!r}')
		self.transport.write(data + b'\r\n')

	async def _get_message(self):
		self.logger.debug(f'Message queue {id(self.messageQueue)} length: {self.messageQueue.qsize()}')
		messageFuture = asyncio.create_task(self.messageQueue.get())
		done, pending = await asyncio.wait((messageFuture, self.connectionClosedEvent.wait()), return_when = concurrent.futures.FIRST_COMPLETED)
		if self.connectionClosedEvent.is_set():
			if messageFuture in pending:
				self.logger.debug('Cancelling messageFuture')
				messageFuture.cancel()
				try:
					await messageFuture
				except asyncio.CancelledError:
					self.logger.debug('Cancelled messageFuture')
					pass
			else:
				# messageFuture is already done but we're stopping, so put the result back onto the queue
				self.messageQueue.putleft_nowait(messageFuture.result())
			return None, None
		assert messageFuture in done, 'Invalid state: messageFuture not in done futures'
		return messageFuture.result()

	async def send_messages(self):
		while self.connected:
			self.logger.debug(f'Trying to get a message')
			channel, message, overlongmode = await self._get_message()
			self.logger.debug(f'Got message: {message!r}')
			if message is None:
				break
			channelB = channel.encode('utf-8')
			messageB = message.encode('utf-8')
			usermaskPrefixLength = 1 + (len(self.usermask) if self.usermask else 100) + 1
			if usermaskPrefixLength + len(b'PRIVMSG ' + channelB + b' :' + messageB) > 510:
				# Message too long, need to split or truncate. First try to split on spaces, then on codepoints. Ideally, would use graphemes between, but that's too complicated.
				self.logger.debug(f'Message too long, overlongmode = {overlongmode}')
				prefix = b'PRIVMSG ' + channelB + b' :'
				prefixLength = usermaskPrefixLength + len(prefix) # Need to account for the origin prefix included by the ircd when sending to others
				maxMessageLength = 510 - prefixLength # maximum length of the message part within each line
				if overlongmode == 'truncate':
					maxMessageLength -= 3 # Make room for an ellipsis at the end
				messages = []
				while message:
					if overlongmode == 'truncate' and messages:
						break # Only need the first message on truncation
					if len(messageB) <= maxMessageLength:
						messages.append(message)
						break

					spacePos = messageB.rfind(b' ', 0, maxMessageLength + 1)
					if spacePos != -1:
						messages.append(messageB[:spacePos].decode('utf-8'))
						messageB = messageB[spacePos + 1:]
						message = messageB.decode('utf-8')
						continue

					# No space found, need to search for a suitable codepoint location.
					pMessage = message[:maxMessageLength] # at most 510 codepoints which expand to at least 510 bytes
					pLengths = [len(x.encode('utf-8')) for x in pMessage] # byte size of each codepoint
					pRunningLengths = list(itertools.accumulate(pLengths)) # byte size up to each codepoint
					if pRunningLengths[-1] <= maxMessageLength: # Special case: entire pMessage is short enough
						messages.append(pMessage)
						message = message[maxMessageLength:]
						messageB = message.encode('utf-8')
						continue
					cutoffIndex = next(x[0] for x in enumerate(pRunningLengths) if x[1] > maxMessageLength)
					messages.append(message[:cutoffIndex])
					message = message[cutoffIndex:]
					messageB = message.encode('utf-8')
				if overlongmode == 'split':
					for msg in reversed(messages):
						self.messageQueue.putleft_nowait((channel, msg, overlongmode))
				elif overlongmode == 'truncate':
					self.messageQueue.putleft_nowait((channel, messages[0] + '…', overlongmode))
			else:
				self.logger.info(f'Sending {message!r} to {channel!r}')
				self.unconfirmedMessages.append((channel, message, overlongmode))
				self.send(b'PRIVMSG ' + channelB + b' :' + messageB)
				await asyncio.sleep(1) # Rate limit

	async def confirm_messages(self):
		while self.connected:
			await asyncio.wait((asyncio.sleep(60), self.connectionClosedEvent.wait()), return_when = concurrent.futures.FIRST_COMPLETED)  # Confirm once per minute
			if not self.connected: # Disconnected while sleeping, can't confirm unconfirmed messages, requeue them directly
				self.messageQueue.putleft_nowait(*self.unconfirmedMessages)
				self.unconfirmedMessages = []
				break
			if not self.unconfirmedMessages:
				self.logger.debug('No messages to confirm')
				continue
			self.logger.debug('Trying to confirm message delivery')
			self.pongReceivedEvent.clear()
			self.send(b'PING :42')
			await asyncio.wait((asyncio.sleep(5), self.pongReceivedEvent.wait()), return_when = concurrent.futures.FIRST_COMPLETED)
			self.logger.debug(f'Message delivery successful: {self.pongReceivedEvent.is_set()}')
			if not self.pongReceivedEvent.is_set():
				# No PONG received in five seconds, assume connection's dead
				self.logger.warning(f'Message delivery confirmation failed, putting {len(self.unconfirmedMessages)} messages back into the queue')
				self.messageQueue.putleft_nowait(*self.unconfirmedMessages)
				self.transport.close()
			self.unconfirmedMessages = []

	def data_received(self, data):
		self.logger.debug(f'Data received: {data!r}')
		# Split received data on CRLF. If there's any data left in the buffer, prepend it to the first message and process that.
		# Then, process all messages except the last one (since data might not end on a CRLF) and keep the remainder in the buffer.
		# If data does end with CRLF, all messages will have been processed and the buffer will be empty again.
		messages = data.split(b'\r\n')
		if self.buffer:
			self.message_received(self.buffer + messages[0])
			messages = messages[1:]
		for message in messages[:-1]:
			self.message_received(message)
		self.buffer = messages[-1]

	def message_received(self, message):
		self.logger.debug(f'Message received: {message!r}')
		rawMessage = message
		if message.startswith(b':') and b' ' in message:
			# Prefixed message, extract command + parameters (the prefix cannot contain a space)
			message = message.split(b' ', 1)[1]

		# PING/PONG
		if message.startswith(b'PING '):
			self.send(b'PONG ' + message[5:])
		elif message.startswith(b'PONG '):
			self.pongReceivedEvent.set()

		# SASL
		elif message.startswith(b'CAP ') and self.sasl:
			if message[message.find(b' ', 4) + 1:] == b'ACK :sasl':
				self.send(b'AUTHENTICATE EXTERNAL')
			else:
				self.logger.error(f'Received unexpected CAP reply {message!r}, terminating connection')
				self.transport.close()
		elif message == b'AUTHENTICATE +':
			self.send(b'AUTHENTICATE +')
		elif message.startswith(b'900 '): # "You are now logged in", includes the usermask
			words = message.split(b' ')
			if len(words) >= 3 and b'!' in words[2] and b'@' in words[2]:
				if b'!~' not in words[2]:
					# At least Charybdis seems to always return the user without a tilde, even if identd failed. Assume no identd and account for that extra tilde.
					words[2] = words[2].replace(b'!', b'!~', 1)
				self._maybe_set_usermask(words[2])
		elif message.startswith(b'903 '): # SASL auth successful
			self.authenticated = True
			self.send(b'CAP END')
		elif any(message.startswith(x) for x in (b'902 ', b'904 ', b'905 ', b'906 ', b'908 ')):
			self.logger.error('SASL error, terminating connection')
			self.transport.close()

		# NICK errors
		elif any(message.startswith(x) for x in (b'431 ', b'432 ', b'433 ', b'436 ')):
			self.logger.error(f'Failed to set nickname: {message!r}, terminating connection')
			self.transport.close()

		# USER errors
		elif any(message.startswith(x) for x in (b'461 ', b'462 ')):
			self.logger.error(f'Failed to register: {message!r}, terminating connection')
			self.transport.close()

		# JOIN errors
		elif any(message.startswith(x) for x in (b'405 ', b'471 ', b'473 ', b'474 ', b'475 ')):
			self.logger.error(f'Failed to join channel: {message!r}, terminating connection')
			self.transport.close()

		# PART errors
		elif message.startswith(b'442 '):
			self.logger.error(f'Failed to part channel: {message!r}')

		# JOIN/PART errors
		elif message.startswith(b'403 '):
			self.logger.error(f'Failed to join or part channel: {message!r}')

		# PRIVMSG errors
		elif any(message.startswith(x) for x in (b'401 ', b'404 ', b'407 ', b'411 ', b'412 ', b'413 ', b'414 ')):
			self.logger.error(f'Failed to send message: {message!r}')

		# Connection registration reply
		elif message.startswith(b'001 '):
			self.logger.info('IRC connection registered')
			if self.sasl and not self.authenticated:
				self.logger.error('IRC connection registered but not authenticated, terminating connection')
				self.transport.close()
				return
			self._send_join_part(b'JOIN', self.channels)
			asyncio.create_task(self.send_messages())
			asyncio.create_task(self.confirm_messages())

		# JOIN success
		elif message.startswith(b'JOIN ') and not self.usermask:
			# If this is my own join message, it should contain the usermask in the prefix
			if rawMessage.startswith(b':' + self.config['irc']['nick'].encode('utf-8') + b'!') and b' ' in rawMessage:
				usermask = rawMessage.split(b' ', 1)[0][1:]
				self._maybe_set_usermask(usermask)

		# Services host change
		elif message.startswith(b'396 '):
			words = message.split(b' ')
			if len(words) >= 3:
				# Sanity check inspired by irssi src/irc/core/irc-servers.c
				if not any(x in words[2] for x in (b'*', b'?', b'!', b'#', b'&', b' ')) and not any(words[2].startswith(x) for x in (b'@', b':', b'-')) and words[2][-1:] != b'-':
					if b'@' in words[2]: # user@host
						self._maybe_set_usermask(self.config['irc']['nick'].encode('utf-8') + b'!' + words[2])
					else: # host (get user from previous mask or settings)
						if self.usermask:
							user = self.usermask.split(b'@')[0].split(b'!')[1]
						else:
							user = b'~' + self.config['irc']['nick'].encode('utf-8')
						self._maybe_set_usermask(self.config['irc']['nick'].encode('utf-8') + b'!' + user + b'@' + words[2])

	def connection_lost(self, exc):
		self.logger.info('IRC connection lost')
		self.connected = False
		self.connectionClosedEvent.set()


class IRCClient:
	logger = logging.getLogger('http2irc.IRCClient')

	def __init__(self, messageQueue, config):
		self.messageQueue = messageQueue
		self.config = config
		self.channels = {map_['ircchannel'] for map_ in config['maps'].values()}

		self._transport = None
		self._protocol = None

	def update_config(self, config):
		needReconnect = self.config['irc'] != config['irc']
		self.config = config
		if self._transport: # if currently connected:
			if needReconnect:
				self._transport.close()
			else:
				self.channels = {map_['ircchannel'] for map_ in config['maps'].values()}
				self._protocol.update_channels(self.channels)

	def _get_ssl_context(self):
		ctx = SSL_CONTEXTS[self.config['irc']['ssl']]
		if self.config['irc']['certfile'] and self.config['irc']['certkeyfile']:
			if ctx is True:
				ctx = ssl.create_default_context()
			if isinstance(ctx, ssl.SSLContext):
				ctx.load_cert_chain(self.config['irc']['certfile'], keyfile = self.config['irc']['certkeyfile'])
		return ctx

	async def run(self, loop, sigintEvent):
		connectionClosedEvent = asyncio.Event()
		while True:
			connectionClosedEvent.clear()
			try:
				self._transport, self._protocol = await loop.create_connection(lambda: IRCClientProtocol(self.messageQueue, connectionClosedEvent, loop, self.config, self.channels), self.config['irc']['host'], self.config['irc']['port'], ssl = self._get_ssl_context())
				try:
					await asyncio.wait((connectionClosedEvent.wait(), sigintEvent.wait()), return_when = concurrent.futures.FIRST_COMPLETED)
				finally:
					self._transport.close() #TODO BaseTransport.close is asynchronous and then triggers the protocol's connection_lost callback; need to wait for connectionClosedEvent again perhaps to correctly handle ^C?
			except (ConnectionRefusedError, asyncio.TimeoutError) as e:
				self.logger.error(str(e))
			await asyncio.wait((asyncio.sleep(5), sigintEvent.wait()), return_when = concurrent.futures.FIRST_COMPLETED)
			if sigintEvent.is_set():
				break


class WebServer:
	logger = logging.getLogger('http2irc.WebServer')

	def __init__(self, messageQueue, config):
		self.messageQueue = messageQueue
		self.config = config

		self._paths = {} # '/path' => ('#channel', auth, module, moduleargs)  where auth is either False (no authentication) or the HTTP header value for basic auth

		self._app = aiohttp.web.Application()
		self._app.add_routes([aiohttp.web.post('/{path:.+}', self.post)])

		self.update_config(config)
		self._configChanged = asyncio.Event()

	def update_config(self, config):
		self._paths = {map_['webpath']: (map_['ircchannel'], f'Basic {base64.b64encode(map_["auth"].encode("utf-8")).decode("utf-8")}' if map_['auth'] else False, map_['module'], map_['moduleargs'], map_['overlongmode']) for map_ in config['maps'].values()}
		needRebind = self.config['web'] != config['web']
		self.config = config
		if needRebind:
			self._configChanged.set()

	async def run(self, stopEvent):
		while True:
			runner = aiohttp.web.AppRunner(self._app)
			await runner.setup()
			site = aiohttp.web.TCPSite(runner, self.config['web']['host'], self.config['web']['port'])
			await site.start()
			await asyncio.wait((stopEvent.wait(), self._configChanged.wait()), return_when = concurrent.futures.FIRST_COMPLETED)
			await runner.cleanup()
			if stopEvent.is_set():
				break
			self._configChanged.clear()

	async def post(self, request):
		self.logger.info(f'Received request {id(request)} from {request.remote!r} for {request.path!r} with body {(await request.read())!r}')
		try:
			channel, auth, module, moduleargs, overlongmode = self._paths[request.path]
		except KeyError:
			self.logger.info(f'Bad request {id(request)}: no path {request.path!r}')
			raise aiohttp.web.HTTPNotFound()
		if auth:
			authHeader = request.headers.get('Authorization')
			if not authHeader or authHeader != auth:
				self.logger.info(f'Bad request {id(request)}: authentication failed: {authHeader!r} != {auth}')
				raise aiohttp.web.HTTPForbidden()
		if module is not None:
			self.logger.debug(f'Processing request {id(request)} using {module!r}')
			try:
				message = await module.process(request, *moduleargs)
			except aiohttp.web.HTTPException as e:
				raise e
			except Exception as e:
				self.logger.error(f'Bad request {id(request)}: exception in module process function: {type(e).__module__}.{type(e).__name__}: {e!s}')
				raise aiohttp.web.HTTPBadRequest()
			if '\r' in message or '\n' in message:
				self.logger.error(f'Bad request {id(request)}: module process function returned message with linebreaks: {message!r}')
				raise aiohttp.web.HTTPBadRequest()
		else:
			self.logger.debug(f'Processing request {id(request)} using default processor')
			message = await self._default_process(request)
		self.logger.info(f'Accepted request {id(request)}, putting message {message!r} for {channel} into message queue')
		self.messageQueue.put_nowait((channel, message, overlongmode))
		raise aiohttp.web.HTTPOk()

	async def _default_process(self, request):
		try:
			message = await request.text()
		except Exception as e:
			self.logger.info(f'Bad request {id(request)}: exception while reading request data: {e!s}')
			raise aiohttp.web.HTTPBadRequest() # Yes, it's always the client's fault. :-)
		self.logger.debug(f'Request {id(request)} payload: {message!r}')
		# Strip optional [CR] LF at the end of the payload
		if message.endswith('\r\n'):
			message = message[:-2]
		elif message.endswith('\n'):
			message = message[:-1]
		if '\r' in message or '\n' in message:
			self.logger.info('Bad request {id(request)}: linebreaks in message')
			raise aiohttp.web.HTTPBadRequest()
		return message


def configure_logging(config):
	#TODO: Replace with logging.basicConfig(..., force = True) (Py 3.8+)
	root = logging.getLogger()
	root.setLevel(getattr(logging, config['logging']['level']))
	root.handlers = [] #FIXME: Undocumented attribute of logging.Logger
	formatter = logging.Formatter(config['logging']['format'], style = '{')
	stderrHandler = logging.StreamHandler()
	stderrHandler.setFormatter(formatter)
	root.addHandler(stderrHandler)


async def main():
	if len(sys.argv) != 2:
		print('Usage: http2irc.py CONFIGFILE', file = sys.stderr)
		sys.exit(1)
	configFile = sys.argv[1]
	config = Config(configFile)
	configure_logging(config)

	loop = asyncio.get_running_loop()

	messageQueue = MessageQueue()

	irc = IRCClient(messageQueue, config)
	webserver = WebServer(messageQueue, config)

	sigintEvent = asyncio.Event()
	def sigint_callback():
		global logger
		nonlocal sigintEvent
		logger.info('Got SIGINT, stopping')
		sigintEvent.set()
	loop.add_signal_handler(signal.SIGINT, sigint_callback)

	def sigusr1_callback():
		global logger
		nonlocal config, irc, webserver
		logger.info('Got SIGUSR1, reloading config')
		try:
			newConfig = config.reread()
		except InvalidConfig as e:
			logger.error(f'Config reload failed: {e!s} (old config remains active)')
			return
		config = newConfig
		configure_logging(config)
		irc.update_config(config)
		webserver.update_config(config)
	loop.add_signal_handler(signal.SIGUSR1, sigusr1_callback)

	await asyncio.gather(irc.run(loop, sigintEvent), webserver.run(sigintEvent))


if __name__ == '__main__':
	asyncio.run(main())