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Class: Resolv

Relationships & Source Files
Namespace Children
Modules:
LOC
Classes:
DNS, Hosts, IPv4, IPv6, MDNS, ResolvTimeout
Exceptions:
ResolvError
Inherits: Object
Defined in: lib/resolv.rb

Overview

Resolv is a thread-aware DNS resolver library written in Ruby. Resolv can handle multiple DNS requests concurrently without blocking the entire Ruby interpreter.

See also resolv-replace.rb to replace the libc resolver with Resolv.

Resolv can look up various DNS resources using the DNS module directly.

Examples:

p Resolv.getaddress "www.ruby-lang.org"
p Resolv.getname "210.251.121.214"

Resolv::DNS.open do |dns|
  ress = dns.getresources "www.ruby-lang.org", Resolv::DNS::Resource::IN::A
  p ress.map(&:address)
  ress = dns.getresources "ruby-lang.org", Resolv::DNS::Resource::IN::MX
  p ress.map { |r| [r.exchange.to_s, r.preference] }
end

Bugs

  • NIS is not supported.

  • /etc/nsswitch.conf is not supported.

Constant Summary

Class Method Summary

Instance Method Summary

Constructor Details

.new(resolvers = nil, use_ipv6: nil) ⇒ Resolv

Creates a new Resolv using resolvers.

[ GitHub ] 

  


# File 'lib/resolv.rb', line 87



def initialize(resolvers=nil, use_ipv6: nil)
  @resolvers = resolvers || [Hosts.new, DNS.new(DNS::Config.default_config_hash.merge(use_ipv6: use_ipv6))]
end


  







Class Method Details



  

    .each_address(name, &block)  
  



  

    

Iterates over all IP addresses for name.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 59



def self.each_address(name, &block)
  DefaultResolver.each_address(name, &block)
end


  








  

    .each_name(address, &proc)  
  



  

    

Iterates over all hostnames for address.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 80



def self.each_name(address, &proc)
  DefaultResolver.each_name(address, &proc)
end


  








  

    .getaddress(name)  
  



  

    

Looks up the first IP address for name.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 45



def self.getaddress(name)
  DefaultResolver.getaddress(name)
end


  








  

    .getaddresses(name)  
  



  

    

Looks up all IP address for name.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 52



def self.getaddresses(name)
  DefaultResolver.getaddresses(name)
end


  








  

    .getname(address)  
  



  

    

Looks up the hostname of address.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 66



def self.getname(address)
  DefaultResolver.getname(address)
end


  








  

    .getnames(address)  
  



  

    

Looks up all hostnames for address.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 73



def self.getnames(address)
  DefaultResolver.getnames(address)
end


  







Instance Method Details



  

    #each_address(name)  
  



  

    

Iterates over all IP addresses for name.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 111



def each_address(name)
  if AddressRegex =~ name
    yield name
    return
  end
  yielded = false
  @resolvers.each {|r|
    r.each_address(name) {|address|
      yield address.to_s
      yielded = true
    }
    return if yielded
  }
end


  








  

    #each_name(address)  
  



  

    

Iterates over all hostnames for address.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 146



def each_name(address)
  yielded = false
  @resolvers.each {|r|
    r.each_name(address) {|name|
      yield name.to_s
      yielded = true
    }
    return if yielded
  }
end


  








  

    #getaddress(name)  
  



  

    

Looks up the first IP address for name.


  





  
Raises:


    
  
  • 
    (ResolvError)
  
    • 





  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 94



def getaddress(name)
  each_address(name) {|address| return address}
  raise ResolvError.new("no address for #{name}")
end


  








  

    #getaddresses(name)  
  



  

    

Looks up all IP address for name.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 102



def getaddresses(name)
  ret = []
  each_address(name) {|address| ret << address}
  return ret
end


  








  

    #getname(address)  
  



  

    

Looks up the hostname of address.


  





  
Raises:


    
  
  • 
    (ResolvError)
  
    • 





  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 129



def getname(address)
  each_name(address) {|name| return name}
  raise ResolvError.new("no name for #{address}")
end


  








  

    #getnames(address)  
  



  

    

Looks up all hostnames for address.


  



  [ GitHub ]


  

  


# File 'lib/resolv.rb', line 137



def getnames(address)
  ret = []
  each_name(address) {|name| ret << name}
  return ret
end