[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:  major      |      Milestone:     
Component:  Obfsproxy  |        Version:     
 Keywords:             |         Parent:     
   Points:             |   Actualpoints:     
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Comment(by asn):

 I'd like some help:
 https://gitweb.torproject.org/obfsproxy.git/blob/HEAD:/src/network.c#l613

 It seems like that if the arguments to
 `bufferevent_socket_connect_hostname()` are well-formed, the function
 will always return 0. This means that if the DNS lookup fail, it will
 go into `pending_socks_cb()` (since the callbacks were set before the
 connect_hostname() call), then into `error_or_eof()`, then it will
 free the whole circuit, and then it will continue happily to line623
 which is `bufferevent_enable(buf, EV_READ|EV_WRITE);`.  that causes a
 segfault.  I'm encountering this problem while trying to solve
 #5156. We currently don't have this problem because we assert out in
 `pending_socks_cb()`.


 So the question is, how should we avoid continuing if
 `bufferevent_socket_connect_hostname()` fails immediately?  Or maybe
 this is not the correct question to ask?

 Also, is this a bug of libevent? Or does the callback approach
 prohibit evutil_getaddrinfo_async() from knowing whether it should
 return an error?

 I uploaded a branch of my current progress in 'bug5156_tmp'.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5156#comment:8>
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