[tor-bugs] #4817 [Tor Relay]: Auth failures don't differentiate failure types

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#4817: Auth failures don't differentiate failure types
-----------------------+----------------------------------------------------
 Reporter:  atagar     |          Owner:     
     Type:  defect     |         Status:  new
 Priority:  trivial    |      Milestone:     
Component:  Tor Relay  |        Version:     
 Keywords:             |         Parent:     
   Points:             |   Actualpoints:     
-----------------------+----------------------------------------------------
 The control-spec has a couple status codes for authentication failures...

 514 Authentication required
 515 Bad authentication

 The 515 status is used for both rejection of the authentication
 credentials and of the authentication method entirely. For instance...

 Rejected Credentials:

 {{{
 AUTHENTICATE "blarg"
 515 Authentication failed: Password did not match HashedControlPassword
 value from configuration
 Connection closed by foreign host.
 }}}

 Rejected Authentication Method:

 {{{
 AUTHENTICATE
 515 Authentication failed: Password did not match HashedControlPassword
 value from configuration. Maybe you tried a plain text password? If so,
 the standard requires that you put it in double quotes.
 Connection closed by foreign host.
 }}}

 This means that controllers need to read the message to translate these
 responses into an exception type. Needless to say this isn't great since
 it leads to sadness if we change or provide localization of the messages.

 In stem's case I provide a warning in the pydocs and attempt to use the
 message...

 {{{
 """
 Authenticates to a control socket that uses a password (via the
 HashedControlPassword torrc option). Quotes in the password are escaped.

 If authentication fails tor will disconnect and we'll make a best effort
 attempt to re-establish the connection. This may not succeed, so check
 is_alive() before using the socket further.

 For general usage use the authenticate() function instead.

 note: If you use this function directly, rather than authenticate(), we
 may
 mistakenly raise a PasswordAuthRejected rather than IncorrectPassword.
 This
 is because we rely on tor's error messaging which is liable to change in
 future versions.
 """

 ...

 # if we got anything but an OK response then error
 if str(auth_response) != "OK":
   try: control_socket.connect()
   except: pass

   # all we have to go on is the error message from tor...
   # Password did not match HashedControlPassword value value from
 configuration...
   # Password did not match HashedControlPassword *or*...

   if "Password did not match HashedControlPassword" in str(auth_response):
     raise IncorrectPassword(str(auth_response), auth_response)
   else:
     raise PasswordAuthRejected(str(auth_response), auth_response)
 }}}

 https://gitweb.torproject.org/stem.git/blob/HEAD:/stem/connection.py#l468

 I do this for both the authenticate_password and authenticate_cookie
 functions. In general this won't be very visible to library users since
 they'll usually use the authenticate() function instead, which has a
 PROTOCOLINFO response so it doesn't have this issue.

 Feel free to resolve this as 'wont fix'. This isn't an issue if controller
 users do PROTOCOLINFO first, and the AUTHENTICATE function has no notion
 of the authentication type being attempted so it would be difficult for
 tor to differentiate those issues, even if it wanted to. Mostly just
 noting a minor gotcha I encountered while writing stem. :)

 Cheers! -Damian

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4817>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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