Feature #13097


Deprecate Socket.gethostbyaddr and Socket.gethostbyname

Added by vo.x (Vit Ondruch) almost 6 years ago. Updated about 5 years ago.

Target version:


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?

Updated by vo.x (Vit Ondruch) almost 6 years ago

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

Updated by normalperson (Eric Wong) almost 6 years ago


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.

Updated by shyouhei (Shyouhei Urabe) almost 6 years ago

  • Tracker changed from Bug to Feature

Updated by nobu (Nobuyoshi Nakada) almost 6 years ago

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

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?

Updated by matz (Yukihiro Matsumoto) almost 6 years ago

I agree with Eric. Documentation deprecation is preferable.


Updated by shyouhei (Shyouhei Urabe) over 5 years ago

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.

Actions #9

Updated by akr (Akira Tanaka) about 5 years ago

  • 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("")'
 " \x01\x02\x00\r\xFF\xFF\xF1\x02\x16>\xFF\xFEKe\x1C",
 "\xCB\xB2\x89:"] 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.


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