Switch from CertFP to the more reliable and secure SASL EXTERNAL

config.example.toml

@@ -5,7 +5,7 @@
 	#ssl = 'yes'
 	#nick = 'h2ibot'
 	#real = 'I am an http2irc bot.'
-	# Certificate and key for CertFP authentication with NickServ; certfile is a string containing the path to a .pem file which has the certificate and the key, certkeyfile similarly for one containing only the key; default values are empty (None in Python) to disable CertFP authentication
+	# Certificate and key for SASL EXTERNAL authentication with NickServ; certfile is a string containing the path to a .pem file which has the certificate and the key, certkeyfile similarly for one containing only the key; default values are empty (None in Python) to disable authentication; the connection is terminated if authentication fails
 	#certfile =
 	#certkeyfile =
 

http2irc.py

@@ -255,12 +255,16 @@ class IRCClientProtocol(asyncio.Protocol):
 		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
 
 	def connection_made(self, transport):
 		self.logger.info('IRC connected')
 		self.transport = transport
 		self.connected = True
 		nickb = self.config['irc']['nick'].encode('utf-8')
+		if self.sasl:
+			self.send(b'CAP REQ :sasl')
 		self.send(b'NICK ' + nickb)
 		self.send(b'USER ' + nickb + b' ' + nickb + b' ' + nickb + b' :' + self.config['irc']['real'].encode('utf-8'))
 
@@ -357,8 +361,22 @@ class IRCClientProtocol(asyncio.Protocol):
 			self.send(b'PONG ' + message[5:])
 		elif message.startswith(b'PONG '):
 			self.pongReceivedEvent.set()
+		elif message.startswith(b'CAP ') and self.sasl and message[message.find(b' ', 4) + 1:] == b'ACK :sasl':
+			self.send(b'AUTHENTICATE EXTERNAL')
+		elif message == b'AUTHENTICATE +':
+			self.send(b'AUTHENTICATE +')
+		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()
 		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(b'JOIN ' + ','.join(self.channels).encode('utf-8')) #TODO: Split if too long
 			asyncio.create_task(self.send_messages())
 			asyncio.create_task(self.confirm_messages())