[tor-bugs] #4847 [Tor Bridge]: Bridges binding only to an IPv6 address doesn't work

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#4847: Bridges binding only to an IPv6 address doesn't work
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 Reporter:  ln5         |          Owner:  ln5                
     Type:  defect      |         Status:  assigned           
 Priority:  normal      |      Milestone:  Tor: 0.2.3.x-final 
Component:  Tor Bridge  |        Version:  Tor: 0.2.3.10-alpha
 Keywords:  ipv6        |         Parent:  #5788              
   Points:              |   Actualpoints:                     
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Changes (by ln5):

  * status:  new => assigned


Comment:

 A bridge without an IPv4 OR port returns 404 when asked for
 "/tor/server/authority.z" because it doesn't have a descriptor for
 itself (router.c:desc_routerinfo is NULL).

 This is because router_get_advertised_or_port() uses
 get_primary_or_port() which looks for IPv4 ports only which has other
 implications as well:

 1. a relay without an IPv4 OR port doesn't have a descriptor for
    itself (the root cause of this bug, see
    router_rebuild_descriptor()) and doesn't consider itself
    publishable and won't upload its descriptor (see
    decide_if_publishable_server())

 2. a relay doesn't realize when its IPv6 OR port changes (see
    retry_all_listeners())

 3. directory authorities on IPv6 don't work well (see init_keys() and
    dirserv_generate_networkstatus_vote_obj())

 I think that we should start by fixing the places where we ask "what's
 _the_ OR port?" when what we really want to know is "do we have an OR
 port?".  This should be a good start at fixing point 1 above.  The
 question about what to put in the "router" line for a relay without an
 IPv4 OR port arises.  Proposal 186 suggests listing a magic IPv4
 address (127.1.1.1) and flag such relays with a new flag indicating
 that they're running but not on the address listed in the "r" line.
 We might want to do this sooner than anticipated for supporting relays
 without an IPv4 OR port.

 Points 2 and 3 are addressed in #6026 and #6027 respectively.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4847#comment:5>
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