Feature #13097: Deprecate Socket.gethostbyaddr and Socket.gethostbyname

• Status: Closed
• Assignee: -
• Target version: -

[vo.x (Vit Ondruch)]

Is there a reason to keep these methods around? They were marked obsolete by POSIX.1-2001 and the POSIX.1-2008 removes the specifications of gethostbyname, gethostbyaddr recommending the use of getaddrinfo and getnameinfo instead. If they are kept because of Ruby backward compatibility, shouldn't they be re-implemented by these modern interfaces?

[vo.x (Vit Ondruch)]

If nothing else, I would consider right if documentation discouraged their use ...

[shevegen (Robert A. Heiler)]

I have no pro or con opinion, just adding links for people who just want to click on stuff for the corresponding docu:

https://ruby-doc.org/stdlib-2.4.0/libdoc/socket/rdoc/Socket.html#method-c-gethostbyaddr

https://ruby-doc.org/stdlib-2.4.0/libdoc/socket/rdoc/Socket.html#method-c-gethostbyname

[normalperson (Eric Wong)]

[e-mail] wrote:

If nothing else, I would consider right if documentation discouraged their use ...

I support documentation discouraging their use.

I'm against a warning message at runtime; that's just annoying
to non-programmers. Let's not break existing code or try to
force people into caring.

[shyouhei (Shyouhei Urabe)]

• Tracker changed from Bug to Feature

[nobu (Nobuyoshi Nakada)]

https://github.com/ruby/ruby/compare/trunk...nobu:feature/deprecate_method

[nobu (Nobuyoshi Nakada)]

$ ruby -rsocket -e 'host = "ci.ruby-lang.org"; ai = Addrinfo.ip(host); p Socket.gethostbyname(host), Socket.getaddrinfo(host, nil), ai, ai.canonname'
["ci.ruby-lang.org", [], 2, "4\xC0P\xDB"]
[["AF_INET", 0, "52.192.80.219", "52.192.80.219", 2, 2, 17], ["AF_INET", 0, "52.192.80.219", "52.192.80.219", 2, 1, 6]]
#<Addrinfo: 52.192.80.219 (ci.ruby-lang.org)>
nil

Socket.gethostbyname returns the hostname, but getaddrinfo not.
And Addrinfo#inspect shows the name but it provides canonname only.
Perhaps we need Addrinfo#inspectname or something, before deprecating Socket.gethostbyname?

[matz (Yukihiro Matsumoto)]

I agree with Eric. Documentation deprecation is preferable.

Matz.

[shyouhei (Shyouhei Urabe)]

Is it difficult to implement our Socket.gethostbyname on top of getaddrinfo(3) ? I see no need to use gethostbyname(3) directly to provide the feature. If that is possible, I think we don't need to deprecate.

[akr (Akira Tanaka)]

• Status changed from Open to Closed

Applied in changeset trunk|r60266.

---

Deprecation document for gethostbyname,gethostbyaddr.

[Feature #13097]

I confirmed current ruby (Ruby 2.4 and trunk) uses
gethostbyname() and gethostbyaddr().

Socket.gethostbyname uses getaddrinfo() and gethostbyname().
Socket.gethostbyaddr uses gethostbyaddr().

Socket.gethostbyname uses gethostbyname() to obtain alias hostnames.

RFC 3493 defines getaddrinfo()/getnameinfo() and
describes the problems of gethostbyname()/gethostbyaddr().
The problems are difficult protocol handling and thread-unsafety.

Since Ruby has GVL, the thread-unsafety doesn't cause wrong result.
But it may block other threads until finishing DNS query.

Socket.gethostbyname has the protocol handling problem.
It returns only one address family:

% ruby -rpp -rsocket -e 'pp Socket.gethostbyname("www.wide.ad.jp")'
["www.wide.ad.jp",
 [],
 10,
 " \x01\x02\x00\r\xFF\xFF\xF1\x02\x16>\xFF\xFEKe\x1C",
 "\xCB\xB2\x89:"]

www.wide.ad.jp has one IPv6 address and one IPv4 address.
But Socket.gethostbyname returns only one address family, 10 (AF_INET6),
which is the address family of the first address.

Also, Socket.gethostbyname and Socket.gethostbyaddr uses
4-bytes binary IPv4 address and 16-bytes binary IPv6 address.
This is not usual in other socket API in Ruby.
(Most socket API uses binary sockaddr string or Addrinfo object)

I think Socket.gethostbyname and Socket.gethostbyaddr are too far
from recommendable API.

So, I added deprecation description for documents for them.