Bug #11864: Resolv incorrectly accepts invalid hostnames and caches records between sessions

• Status: Third Party's Issue
• Assignee: -
• Target version: -
• ruby -v: ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN

[breadtk (Osman Surkatty)]

Hello,

While working on a DNS related project I noticed that Resolv's getaddresses() and getaddress() functions will incorrectly accepts an empty String and additionally returns a cached record if a new IRB session is invoked. Resolv correctly rejects nil or empty arguments, but I believe the issue here is that the validation of String should require at a minimum a single valid String character.

Here is an example of what I mean:

$ irb
irb(main):001:0> RUBY_VERSION
=> "2.2.3"
irb(main):002:0> require 'resolv'
=> true
irb(main):003:0> Resolv.getaddresses("surkatty.org")
=> ["54.244.9.126"]
irb(main):004:0> Resolv.getaddresses("example.com")
=> ["93.184.216.34"]
irb(main):005:0> Resolv.getaddresses("NX")
=> []
irb(main):006:0> Resolv.getaddresses("")
=> ["54.244.9.126"]
irb(main):007:0> Resolv.getaddresses()
ArgumentError: wrong number of arguments (0 for 1)
	from /usr/local/Cellar/ruby/2.2.3/lib/ruby/2.2.0/resolv.rb:48:in `getaddresses'
	from (irb):7
	from /usr/local/bin/irb:11:in `<main>'
irb(main):008:0>

On line 006:0, I would have expected Resolv.getaddresses("") to return either:

1. Raise an ArgumentError or some other indicating an invalid String was passed
2. Return an empty Array

I've also attached a screenshot from my commandline showing the output between IRB sessions as well.

[breadtk (Osman Surkatty)]

• Assignee set to akr (Akira Tanaka)

Assigning directly to Akira Tanaka, the Resolv maintainer per https://bugs.ruby-lang.org/projects/ruby/wiki/MaintainersStdlib

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Status changed from Open to Third Party's Issue
• Assignee deleted (akr (Akira Tanaka))

It returned an empty list for an empty name on Darwin 15, but returned a random list on Darwin 14.
Seems a bug of OS X 10.10.
You may want to request Apple to backport the fix.

[nobu (Nobuyoshi Nakada)]

Correction.

The previous result was when VPN is connected, and the answer seemed a list of private addresses over VPN.
After disconnecting the VPN, an empty list returned.

I'm not sure if this is your case, however, check your network environment.