refactored and corrected identity testing, prompt user when a session is initiated by an unsubscribed jid

src/common/exceptions.py

@@ -45,8 +45,16 @@ class SessionBusNotPresent(Exception):
 	def __str__(self):
 		return _('Session bus is not available.\nTry reading http://trac.gajim.org/wiki/GajimDBus')
 
+class NegotiationError(Exception):
+	'''A session negotiation failed'''
+	pass
+
+class DecryptionError(Exception):
+	'''A message couldn't be decrypted into usable XML'''
+	pass
+
 class GajimGeneralException(Exception):
-	'''This exception ir our general exception'''
+	'''This exception is our general exception'''
 	def __init__(self, text=''):
 		Exception.__init__(self)
 		self.text = text

src/common/stanza_session.py

@@ -2,6 +2,7 @@ import gajim
 
 from common import xmpp
 from common import helpers
+from common import exceptions
 
 import random
 import string
@@ -47,12 +48,13 @@ class StanzaSession(object):
 		return "".join([random.choice(string.letters) for x in xrange(0,32)])
 
 	def send(self, msg):
-		if self.thread_id:
+		if self.thread_id and isinstance(msg, xmpp.Message):
 			msg.setThread(self.thread_id)
 
 		msg.setAttr('to', self.jid)
 		self.conn.send_stanza(msg)
 	
+		if isinstance(msg, xmpp.Message):
 			self.last_send = time.time()
 
 	def reject_negotiation(self, body = None):
@@ -291,7 +293,7 @@ class EncryptedStanzaSession(StanzaSession):
 		try:
 			parsed = xmpp.Node(node='<node>' + plaintext + '</node>')
 		except:
-			raise DecryptionError
+			raise exceptions.DecryptionError
 
 		for child in parsed.getChildren():
 			stanza.addChild(node=child)
@@ -446,7 +448,7 @@ class EncryptedStanzaSession(StanzaSession):
 		self.n_o = base64.b64decode(form['my_nonce'])
 
 		dhhashes = form.getField('dhhashes').getValues()
-		self.He = dhhashes[group_order].encode("utf8")
+		self.He = base64.b64decode(dhhashes[group_order].encode("utf8"))
 
 		bytes = int(self.n / 8)
 
@@ -586,13 +588,8 @@ class EncryptedStanzaSession(StanzaSession):
 		e = self.decode_mpi(base64.b64decode(form['dhkeys']))
 		p = dh.primes[self.modp]
 
-		if (not self.sha256(self.encode_mpi(e)) == self.He): or \
+		if (self.sha256(self.encode_mpi(e)) != self.He) or (not 1 < e < (p - 1)):
-		(not e > 1 and e < (p - 1)):
+			raise exceptions.NegotiationError, "invalid DH value 'e'"
-			err = xmpp.Error(response, xmpp.ERR_FEATURE_NOT_IMPLEMENTED)
-			err.T.error.T.text.setData("invalid DH value 'e'")
-			self.send(err)
-			self.status = None
-			return
 
 		k = self.sha256(self.encode_mpi(self.powmod(e, self.y, p)))
 
@@ -605,11 +602,7 @@ class EncryptedStanzaSession(StanzaSession):
 		m_a_calculated = self.hmac(self.km_o, self.encode_mpi(self.c_o) + id_a)
 
 		if m_a_calculated != m_a:
-			err = xmpp.Error(response, xmpp.ERR_FEATURE_NOT_IMPLEMENTED)
+			raise exceptions.NegotiationError, 'calculated m_a differs from received m_a'
-			err.T.error.T.text.setData('calculated m_a differs from received m_a')
-			self.send(err)
-			self.status = None
-			return
 
 		mac_a = self.decrypt(id_a)
 
@@ -619,11 +612,7 @@ class EncryptedStanzaSession(StanzaSession):
 		mac_a_calculated = self.hmac(self.ks_o, self.n_s + self.n_o + self.encode_mpi(e) + self.form_a + form_a2)
 
 		if mac_a_calculated != mac_a:
-			err = xmpp.Error(response, xmpp.ERR_FEATURE_NOT_IMPLEMENTED)
+			raise exceptions.NegotiationError, 'calculated mac_a differs from received mac_a'
-			err.T.error.T.text.setData('calculated mac_a differs from received mac_a')
-			self.send(err)
-			self.status = None
-			return
 
 		# 4.5.4 generating bob's final session keys
 		self.srs = ''
@@ -653,7 +642,8 @@ class EncryptedStanzaSession(StanzaSession):
 		form_b2 = ''.join(map(lambda el: xmpp.c14n.c14n(el), x.getChildren()))
 
 		old_c_s = self.c_s
-		mac_b = self.hmac(self.n_o + self.n_s + self.encode_mpi(self.d) + self.form_b + form_b2, self.ks_s)
+
+		mac_b = self.hmac(self.ks_s, self.n_o + self.n_s + self.encode_mpi(self.d) + self.form_b + form_b2)
 		id_b = self.encrypt(mac_b)
 
 		m_b = self.hmac(self.km_s, self.encode_mpi(old_c_s) + id_b)
@@ -703,27 +693,20 @@ class EncryptedStanzaSession(StanzaSession):
 		m_b = base64.b64decode(form['mac'])
 		id_b = base64.b64decode(form['identity'])
 
-		m_b_calculated = self.hmac(self.encode_mpi(self.c_o) + id_b, self.km_o)
+		m_b_calculated = self.hmac(self.km_o, self.encode_mpi(self.c_o) + id_b)
 
 		if m_b_calculated != m_b:
-			err = xmpp.Error(response, xmpp.ERR_FEATURE_NOT_IMPLEMENTED)
+			raise exceptions.NegotiationError, 'calculated m_b differs from received m_b'
-			err.T.error.T.text.setData('calculated m_b differs from received m_b')
-			self.send(err)
-			self.status = None
-			return
 
 		mac_b = self.decrypt(id_b)
 
-		form_b2 = ''.join(map(lambda el: xmpp.c14n.c14n(el), form.getChildren()))
+		macable_children = filter(lambda x: x.getVar() not in ('mac', 'identity'), form.getChildren())
+		form_b2 = ''.join(map(lambda el: xmpp.c14n.c14n(el), macable_children))
 
-		mac_b_calculated = self.hmac(self.n_s + self.n_o + self.encode_mpi(self.d) + self.form_b + form_b2, self.ks_o)
+		mac_b_calculated = self.hmac(self.ks_o, self.n_s + self.n_o + self.encode_mpi(self.d) + self.form_b + form_b2)
 
 		if mac_b_calculated != mac_b:
-			err = xmpp.Error(response, xmpp.ERR_FEATURE_NOT_IMPLEMENTED)
+			raise exceptions.NegotiationError, 'calculated mac_b differs from received mac_b'
-			err.T.error.T.text.setData('calculated mac_b differs from received mac_b')
-			self.send(err)
-			self.status = None
-			return
 
 # Note: If Alice discovers an error then she SHOULD ignore any encrypted content she received in the stanza.
 	
@@ -782,6 +765,13 @@ class EncryptedStanzaSession(StanzaSession):
 		
 		self.enable_encryption = False
 
+	def fail_bad_negotiation(self, reason):
+		'''they've tried to feed us a bogus value, send an error and cancel everything.'''
+		err = xmpp.Error(xmpp.Message(), xmpp.ERR_FEATURE_NOT_IMPLEMENTED)
+		err.T.error.T.text.setData(reason)
+		self.send(err)
+		self.status = None
+
 	def is_loggable(self):
 		name = self.conn.name
 		no_log_for = gajim.config.get_per('accounts', name, 'no_log_for')

src/gajim.py

@@ -1669,29 +1669,25 @@ class Interface:
 		# bob responds
 		if form.getType() == 'form' and u'e2e' in \
 		map(lambda x: x[1], form.getField('security').getOptions()):
-			contact = gajim.contacts.get_contact(account, jid.getStripped(), jid.getResource())
+			def continue_with_negotiation(*args):
-
+				if len(args):
-			if gajim.SHOW_LIST[gajim.connections[account].connected] == 'invisible' or \
+					self.dialog.destroy()
-			contact.sub not in ('from', 'both'):
-				return
 
 				negotiated, not_acceptable, ask_user = session.verify_options_bob(form)
 
 				if ask_user:
 					def accept_nondefault_options(widget):
+						self.dialog.destroy()
 						negotiated.update(ask_user)
 						session.respond_e2e_bob(form, negotiated, not_acceptable)
 
-					dialog.destroy()
-
 					def reject_nondefault_options(widget):
+						self.dialog.destroy()
 						for key in ask_user.keys():
 							not_acceptable.append(key)
 						session.respond_e2e_bob(form, negotiated, not_acceptable)
 
-					dialog.destroy()
+					self.dialog = dialogs.YesNoDialog(_('Confirm these session options'),
-
-				dialog = dialogs.YesNoDialog(_('Confirm these session options'),
 						_('''The remote client wants to negotiate an session with these features:
 
 	%s
@@ -1702,6 +1698,22 @@ Are these options acceptable?''') % (negotiation.describe_features(ask_user)),
 				else:
 					session.respond_e2e_bob(form, negotiated, not_acceptable)
 
+			def ignore_negotiation(widget):
+				self.dialog.destroy()
+				return
+			
+			contact = gajim.contacts.get_contact_with_highest_priority(account, str(jid))
+				
+			if gajim.SHOW_LIST[gajim.connections[account].connected] == 'invisible' or not contact or\
+			contact.sub not in ('from', 'both'):
+				self.dialog = dialogs.YesNoDialog(_('Start session?'),
+					_('''%s would like to start a session with you. Should I respond?''') % jid,
+							on_response_yes = continue_with_negotiation,
+							on_response_no = ignore_negotiation,
+					)
+			else:
+				continue_with_negotiation()
+
 			return
 
 		# alice accepts
@@ -1727,16 +1739,24 @@ Are these options acceptable?''') % (negotiation.describe_features(ask_user)),
 						on_response_no = reject_nondefault_options)
 			else:
 				session.accept_e2e_alice(form, negotiated)
-				
 				negotiation.show_sas_dialog(jid, session.sas)
 
 			return
 		elif session.status == 'responded-e2e' and form.getType() == 'result':
+			try:
 				session.accept_e2e_bob(form)
+			except exceptions.NegotiationError, details: 
+				session.fail_bad_negotiation(details)
+			else:
 				negotiation.show_sas_dialog(jid, session.sas)
+
 			return
 		elif session.status == 'identified-alice' and form.getType() == 'result':
+			try:
 				session.final_steps_alice(form)
+			except exceptions.NegotiationError, details: 
+				session.fail_bad_negotiation(details)
+
 			return
 		
 		if form.getField('terminate'):