Ignore IPv6 nameservers to prevent Socket::ResolutionError

[Watson1978]

The DNSResolver currently does not support IPv6 and initializes an IPv4 (AF_INET) UDP socket.

cool.io/lib/cool.io/dns_resolver.rb

Lines 8 to 10 in 28366d0

	# Word to the wise: I don't know what I'm doing here. This was cobbled together
	# as best I could with extremely limited knowledge of the DNS format. There's
	# obviously a ton of stuff it doesn't support (like IPv6 and TCP).

However, modern OS environments often include IPv6 addresses in /etc/resolv.conf by default.

When the resolver attempts to send a query to an IPv6 nameserver using the IPv4 socket, it crashes with: Socket::ResolutionError: getaddrinfo: Address family for hostname not supported

This will fix following error:

$ rspec spec/dns_spec.rb

DNS
  connects to valid domains (FAILED - 1)
  fires on_resolve_failed for invalid domains (FAILED - 2)
  resolve localhost even though hosts is empty
  resolve missing localhost even though hosts entries exist

Failures:

  1) DNS connects to valid domains
     Failure/Error: @socket.send request_message, 0, @nameservers.first, DNS_PORT

     Socket::ResolutionError:
       getaddrinfo: Address family for hostname not supported
     # ./lib/cool.io/dns_resolver.rb:118:in 'UDPSocket#send'
     # ./lib/cool.io/dns_resolver.rb:118:in 'Coolio::DNSResolver#send_request'
     # ./lib/cool.io/dns_resolver.rb:86:in 'Coolio::DNSResolver#attach'
     # (eval at ./lib/cool.io/meta.rb:15):3:in 'Coolio::TCPSocket#attach'
     # ./spec/dns_spec.rb:28:in 'block (2 levels) in <top (required)>'
     # /home/watson/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/rspec-core-3.13.6/lib/rspec/core/example.rb:263:in 'BasicObject#instance_exec'
     # /home/watson/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/rspec-core-3.13.6/lib/rspec/core/example.rb:263:in 'block in RSpec::Core::Example#run'
     # /home/watson/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/rspec-core-3.13.6/lib/rspec/core/example.rb:511:in 'block in RSpec::Core::Example#with_around_and_singleton_context_hooks'
     # /home/watson/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/rspec-core-3.13.6/lib/rspec/core/example.rb:468:in 'block in RSpec::Core::Example#with_around_example_hooks'
     # /home/watson/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/rspec-core-3.13.6/lib/rspec/core/hooks.rb:486:in 'block in RSpec::Core::Hooks::HookCollections#run'
     # /home/watson/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/rspec-core-3.13.6/lib/rspec/core/hooks.rb:624:in 'RSpec::Core::Hooks::HookCollections#run_around_example_hooks_for'
     # /home/watson/.rbenv/versions/4.0.1/lib/ruby/gems/4.0.0/gems/rspec-core-3.13.6/lib/rspec/core/hooks.rb:486:in 'RSpec::Core::Hooks::Hoo
...

Types of Changes

• Bug fix.

Contribution

• I added tests for my changes.
• I tested my changes locally.
• I agree to the Developer's Certificate of Origin 1.1.