[tor-bugs] #24546 [Core Tor/Tor]: Use tor_addr_is_v4() rather than family, or reject all v6-mapped IPv4 addresses

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#24546: Use tor_addr_is_v4() rather than family, or reject all v6-mapped IPv4
addresses
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  neel
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  unspecified
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  unspecified
 Severity:  Normal                               |     Resolution:
 Keywords:  tor-dirauth, ipv6,                   |  Actual Points:
  033-triage-20180320, 033-removed-20180320,     |
  035-triaged-in-20180711,                       |
  040-deferred-20190220                          |
Parent ID:                                       |         Points:  1
 Reviewer:  ahf, teor                            |        Sponsor:
                                                 |  SponsorV-can
-------------------------------------------------+-------------------------

Comment (by teor):

 Hi, I saw your comments on the pull request.

 Replying to [comment:23 teor]:
 > I am concerned about the size of the diff in commit 53ff26b. It changes
 over 100 lines. It contains at least one logic error that passed review.
 There could be more.
 >
 > Here are our options for moving forward:
 > 1. Use an automated tool like coccinelle to do the changes in 53ff26b.
 Then we can verify the output using the tool. We should also turn
 tor_addr_is_*() into inline header functions, so they are more efficient.

 I can understand that you don't want to use an automated tool. But we
 can't review a hundred lines of very similar changes effectively. We've
 already missed one mistake even though we did multiple reviews, and there
 could be more.

 > 2. Delete the function tor_addr_is_v4(), and replace all its uses with
 `tor_addr_family(addr) == AF_INET`. There are only 13 uses of
 tor_addr_is_v4() in master, so the diff should be much smaller and easier
 to review.
 >
 > I prefer option 2, because we will end up with fewer functions, and less
 code complexity. And the overall diff will be smaller.

 Would you like to do a new pull request that removes tor_addr_is_v4()?
 You could use your existing first and last commits
 56ec375359032eee15cbda9a6d5960cdd5a28135 and
 1d5c703ec2e2d418180f9cdeba1140b9dbaf730d. Then add a commit that removes
 tor_addr_is_v4(), which should only be about 20-30 changed lines.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24546#comment:25>
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