[tor-bugs] #5156 [Obfsproxy]: assertion failure at src/network.c:931: circ

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#5156: assertion failure at src/network.c:931: circ
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 Reporter:  arma       |          Owner:  asn
     Type:  defect     |         Status:  new
 Priority:  normal     |      Milestone:     
Component:  Obfsproxy  |        Version:     
 Keywords:             |         Parent:     
   Points:             |   Actualpoints:     
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Comment(by asn):

 Replying to [comment:3 nickm]:
 > Ah, it looks like there's an ordering bug here.
 bufferevent_connect_hostname is allowed to complete immediately while it
 is called, but the function calling it assumes that it's okay to set up
 the ->circuit pointer after the open_outbound_hostname call returns.
 >
 > So the right fix here seems to be setting the circuit earlier, I guess?

 So I see, I didn't know that bufferevent callbacks are triggered
 immediately. I thought they were triggered on the next libevent loop;
 seems like this is the behavior of deferred callbacks, though.

 So, does `simple_server_listener_cb()` and `simple_client_listener_cb()`
 have the same problem? `open_outbound()` seems to do `bufferevent_setcb`
 and `bufferevent_socket_connect` before setting up the circuit.

 I'm wondering, do we have any more instances of this bug?

 I'll do some more research, try to reproduce it, and then try to make a
 patch.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5156#comment:4>
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