[tor-bugs] #9498 [Tor]: Allow bridge descriptors to contain no address if they are not being published

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#9498: Allow bridge descriptors to contain no address if they are not being
published
-------------------------+--------------------------------------------------
 Reporter:  nwf          |          Owner:                  
     Type:  enhancement  |         Status:  new             
 Priority:  minor        |      Milestone:                  
Component:  Tor          |        Version:  Tor: unspecified
 Keywords:               |         Parent:                  
   Points:               |   Actualpoints:                  
-------------------------+--------------------------------------------------
 To strengthen an "isolating proxy"-style approach to client security, I'd
 like to allow a Tor bridge node to not reveal its external address(es) in
 its bridge descriptor.  The following patch leaves the address as 0.0.0.0
 when it's not going to be published:

 {{{
 diff --git a/src/or/router.c b/src/or/router.c
 index 1063eda..30749b9 100644
 --- a/src/or/router.c
 +++ b/src/or/router.c
 @@ -1772,7 +1772,7 @@ router_rebuild_descriptor(int force)
  {
    routerinfo_t *ri;
    extrainfo_t *ei;
 -  uint32_t addr;
 +  uint32_t addr = 0;
    char platform[256];
    int hibernating = we_are_hibernating();
    const or_options_t *options = get_options();
 @@ -1780,11 +1780,16 @@ router_rebuild_descriptor(int force)
    if (desc_clean_since && !force)
      return 0;

 -  if (router_pick_published_address(options, &addr) < 0 ||
 -      router_get_advertised_or_port(options) == 0) {
 +  /* If we're not trying to publish our descriptor, it's OK to use
 0.0.0.0
 +   * as the address therein.
 +   */
 +  if ((options->PublishServerDescriptor_ != NO_DIRINFO) &&
 +      (router_pick_published_address(options, &addr) < 0 ||
 +       router_get_advertised_or_port(options) == 0)) {
      /* Stop trying to rebuild our descriptor every second. We'll
       * learn that it's time to try again when ip_address_changed()
       * marks it dirty. */
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/9498>
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