[tor-bugs] #23819 [Core Tor/Tor]: Support IPv6 link-local interface addresses

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#23819: Support IPv6 link-local interface addresses
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 Reporter:  Zakhar           |          Owner:  (none)
     Type:  enhancement      |         Status:  needs_revision
 Priority:  Medium           |      Milestone:  Tor: 0.3.3.x-final
Component:  Core Tor/Tor     |        Version:
 Severity:  Normal           |     Resolution:
 Keywords:  ipv6 link-local  |  Actual Points:  1
Parent ID:                   |         Points:  1
 Reviewer:                   |        Sponsor:
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Comment (by Zakhar):

 Thanks for the code review.

 There is probably a possibility to do the change with a local structure
 since the patch is limited to address.c/address.h, but then, should you
 need link-local ipv6 addresses elsewhere, you would have to patch again.

 So yes, it adds 4 bytes to every address, but that is compliant with
 RFC4007 Section 4 that speaks about ipv6 addresses. Since ipv6 addresses
 are in fact 20 bytes long (if you don't want to rule out link-local
 addresses) I though it could be a more durable patch to go directly to the
 target 20 bytes.

 Should you prefer a local patch for address.c/address.h, I can look into
 that.

 I'll also look into the coding style (spaces and line length) and how to
 add the documentation in the man.

 A last word about a '''limitation''' I forgot: I didn't change the
 printing. I mean now it accepts a parameter like:

 `TransPort [fe80::12:34%eth0]:9040`

 But you still get printed out that it successfully binds to [fe80::12:34],
 that is the %eth0 is stripped out.
 That was to keep the patch as short as possible, but to go into details,
 we should also keep that bit of the address and print it out nicely.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/23819#comment:5>
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