[tor-bugs] #25055 [Core Tor/Tor]: string_is_valid_hostname() returns true for IPv4 addresses

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#25055: string_is_valid_hostname() returns true for IPv4 addresses
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 Reporter:  teor               |          Owner:  (none)
     Type:  defect             |         Status:  needs_revision
 Priority:  Medium             |      Milestone:  Tor: 0.3.4.x-final
Component:  Core Tor/Tor       |        Version:
 Severity:  Normal             |     Resolution:
 Keywords:  IPv6 IPv4 tor-dns  |  Actual Points:
Parent ID:                     |         Points:  1
 Reviewer:                     |        Sponsor:
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Comment (by teor):

 Replying to [comment:14 rl1987]:
 > What am I missing? What are the action points to get this finished?

 Replying to [comment:12 teor]:
 > let's not break as soon as IETF slightly changes the IDN or other DNS
 formats, please.

 Please make the hostname validation check for alphanumeric, hyphen, and
 underscore in every component.
 Do not check for the precise punycode format as of 2018, that's fragile,
 and will break if the IDN format is changed, or a new DNS format is added.

 If you wish, you can exclude IPv4 addresses, which would otherwise match
 the new hostname check.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25055#comment:15>
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