Add a config var to require SASL auth when connecting.

src/conf.py

@@ -383,6 +383,9 @@ def registerNetwork(name, password='', ssl=True, sasl_username='',
     registerGlobalValue(sasl, 'mechanisms', SpaceSeparatedListOfSaslMechanisms(
         ['ecdsa-nist256p-challenge', 'external', 'plain'], _("""Determines
         what SASL mechanisms will be tried and in which order.""")))
+    registerGlobalValue(sasl, 'required', registry.Boolean(False,
+        _("""Determines whether the bot will abort the connection if the
+        none of the enabled SASL mechanism succeeded.""")))
     registerGlobalValue(network, 'socksproxy', registry.String('',
         _("""If not empty, determines the hostname of the socks proxy that
         will be used to connect to this network.""")))

src/irclib.py

@@ -1081,6 +1081,9 @@ class Irc(IrcCommandDispatcher, log.Firewalled):
             self.sasl_current_mechanism = self.sasl_next_mechanisms.pop(0)
             self.sendMsg(ircmsgs.IrcMsg(command='AUTHENTICATE',
                 args=(self.sasl_current_mechanism.upper(),)))
+        elif conf.supybot.networks.get(self.network).sasl.required():
+            log.error('None of the configured SASL mechanisms succeeded, '
+                    'aborting connection.')
         else:
             self.sasl_current_mechanism = None
             self.endCapabilityNegociation()