[ruby-core:27620] [Bug #2614] Resolv.[getaddress] should fail gracefully on OSX when offline

Bug #2614: Resolv.[getaddress] should fail gracefully on OSX when offline
http://redmine.ruby-lang.org/issues/show/2614

Author: Ronald Tse
Status: Open, Priority: Normal
Category: lib
ruby -v: 1.9.1

Hi Guys,

When OSX isn't connected to the internet, Resolv.getaddress fails abruptly due to a NoMethodError in Resolv::DNS::Config.lazy_initialize.

On OSX, /etc/resolv.conf exists only when it is connected to a network. When OSX is not (or unable) connected to any network, /etc/resolv.conf does not exist. 

The cause of the NoMethodError is due to return of an uninitialized variable named "config_hash" in Resolv::DNS::Config.default_config_hash. Its only callee "lazy_initialize", expects an empty hash to be returned instead of "nil" on parsing errors (e.g. when /etc/resolv.conf does not exist).

The fix is simply to move the initialization of "config_hash" to the beginning of the function. Please see the patch attached.


Hope this helps.

Best,
Ron


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NOTES
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When OSX disconnected from internet:

irb(main):001:0> load "/opt/local/lib/ruby/1.9.1/resolv.rb"
=> true
irb(main):002:0> Resolv.getaddress "www.ruby-lang.org"
NoMethodError: undefined method `include?' for nil:NilClass
	from /opt/local/lib/ruby/1.9.1/resolv.rb:853:in `block in lazy_initialize'
	from <internal:prelude>:8:in `synchronize'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:832:in `lazy_initialize'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:332:in `block in lazy_initialize'
	from <internal:prelude>:8:in `synchronize'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:330:in `lazy_initialize'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:472:in `each_resource'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:381:in `each_address'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:115:in `block in each_address'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:114:in `each'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:114:in `each_address'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:92:in `getaddress'
	from /opt/local/lib/ruby/1.9.1/resolv.rb:43:in `getaddress'
	from (irb):2
	from /opt/local/bin/irb:12:in `<main>'


When OSX connected to internet:

irb(main):003:0>Resolv.getaddress "www.ruby-lang.org"
=> "221.186.184.68"


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