[tor-bugs] #19026 [Circumvention/Snowflake]: Remove local LAN address ICE candidates

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#19026: Remove local LAN address ICE candidates
-------------------------------------+-----------------------------
 Reporter:  dcf                      |          Owner:  arlolra
     Type:  enhancement              |         Status:  merge_ready
 Priority:  Medium                   |      Milestone:
Component:  Circumvention/Snowflake  |        Version:
 Severity:  Normal                   |     Resolution:
 Keywords:                           |  Actual Points:
Parent ID:                           |         Points:
 Reviewer:  cohosh                   |        Sponsor:
-------------------------------------+-----------------------------

Comment (by dcf):

 Sorry to bring it up at this late stage, but the
 [https://github.com/pion/sdp pion/sdp] package is an alternative to string
 operations. There's a
 [https://godoc.org/github.com/pion/sdp#SessionDescription
 SessionDescription] type with
 [https://godoc.org/github.com/pion/sdp#SessionDescription.Marshal Marshal]
 and [https://godoc.org/github.com/pion/sdp#SessionDescription.Unmarshal
 Unmarshal] methods, containing an array of
 [https://godoc.org/github.com/pion/sdp#Attribute Attribute]s that each
 have a [https://godoc.org/github.com/pion/sdp#Attribute.ToICECandidate
 ToICECandidate] method.

 Replying to [comment:6 cohosh]:
 > - {{{FIXME: Should this check ip.IsLoopback() and others?}}} I'd like to
 include `0.0.0.0` and `127.0.0.1` addresses in this, especially after dcf
 found #33157.

 I feel that the 0.0.0.0 is unrelated to anything involving candidate
 addresses. 0.0.0.0 is appearing in the `o=` origin field and the `c=`
 connection information field (the latter is what `remoteIPFromSDP` looks
 at), not in an `a=candidate` attribute.

 However, I imagine that if a LAN address appears as a `a=candidate`, that
 may also cause it to appear in `o=` or `c=`, and we may have to
 additionally deal with that when #33157 is figured out.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19026#comment:12>
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