[tor-bugs] #9546 [Tor]: Link handshake fails with "Received unexpected cell command 10" on a bridge

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#9546: Link handshake fails with "Received unexpected cell command 10" on a bridge
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 Reporter:  zwol                                |          Owner:                    
     Type:  defect                              |         Status:  needs_review      
 Priority:  major                               |      Milestone:  Tor: 0.2.4.x-final
Component:  Tor                                 |        Version:  Tor: 0.2.4.15-rc  
 Keywords:  tor-bridge tor-client 023-backport  |         Parent:                    
   Points:                                      |   Actualpoints:                    
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Comment(by nickm):

 Replying to [comment:20 arma]:
 > Why do our bridges decide they're too cool to follow the spec? :)

 Looking at the commit logs doesn't shine much light on this.

 As near as I can guess, the rationales might have been:
    * They don't need to have authenticated incoming connections.

    * It's a little weird to let a relay authenticate a connection to a
 bridge such that the bridge will use that connection for extending
 circuits to that relay.

 But I'm not actually seeing a flaw there -- this happens already on
 relay<->relay connections to no ill effect.  Further, any relay that
 wanted to create an authenticated connection to a bridge could do so by
 using the v1 or v2 handshake, by acting as a client and extending to
 itself, or something like that.

 So I'm adding another commit to these branches to cause bridges to send
 AUTH_CHALLENGE cells.  Please review?

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/9546#comment:22>
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