Class: Net::DNS::MDNS::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/net/dns/mdns.rb

Overview

:nodoc:

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/net/dns/mdns.rb', line 314

def initialize
  @asked = Hash.new { |h,k| h[k] = Hash.new }

  @cached = Hash.new { |h,k| h[k] = (Hash.new { |a,b| a[b] = Array.new }) }
end

Instance Attribute Details

#asked ⇒ Object (readonly)

asked: Hash -> Hash -> Question



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# File 'lib/net/dns/mdns.rb', line 309

def asked
  @asked
end

#cached ⇒ Object (readonly)

cached: Hash -> Hash -> Array -> Answer



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# File 'lib/net/dns/mdns.rb', line 312

def cached
  @cached
end

Instance Method Details

#add_question(qu) ⇒ Object

Return the question if we added it, or nil if question is already being asked.



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# File 'lib/net/dns/mdns.rb', line 321

def add_question(qu)
  if qu && !@asked[qu.name][qu.type]
    @asked[qu.name][qu.type] = qu
  end
end

#answers_for(name, type) ⇒ Object 



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# File 'lib/net/dns/mdns.rb', line 369

def answers_for(name, type)
  answers = []
  if( name.to_s == '*' )
    @cached.keys.each { |n| answers += answers_for(n, type) }
  elsif( type == IN::ANY )
    @cached[name].each { |rtype,rdata| answers += rdata }
  else
    answers += @cached[name][type]
  end
  answers
end

#asked?(name, type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/net/dns/mdns.rb', line 381

def asked?(name, type)
  return true if name.to_s == '*'

  t = @asked[name][type] || @asked[name][IN::ANY]

  # TODO - true if (Time.now - t) < some threshold...

  t
end

#cache_answer(an) ⇒ Object

Return cached answer, or nil if answer wasn’t cached.



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# File 'lib/net/dns/mdns.rb', line 336

def cache_answer(an)
  answers = @cached[an.name][an.type]

  if( an.absolute? )
    # Replace all answers older than a ~1 sec [mDNS].
    # If the data is the same, don't delete it, we don't want it to look new.
    now_m1 = Time.now.to_i - 1
    answers.delete_if { |a| a.toa < now_m1 && a.data != an.data }
  end

  old_an = answers.detect { |a| a.name == an.name && a.data == an.data }

  if( !old_an )
    # new answer, cache it
    answers << an
  elsif( an.ttl == 0 )
    # it's a "remove" notice, replace old_an
    answers.delete( old_an )
    answers << an
  elsif( an.expiry > old_an.expiry)
    # it's a fresher record than we have, cache it but the data is the
    # same so don't report it as cached
    answers.delete( old_an )
    answers << an
    an = nil
  else
    # don't cache it
    an = nil
  end

  an
end

#cache_question(name, type) ⇒ Object

Cache question. Increase the number of times we’ve seen it.



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# File 'lib/net/dns/mdns.rb', line 328

def cache_question(name, type)
  if qu = @asked[name][type]
    qu.update
  end
  qu
end