Class: RubyDNS::Transaction

Inherits:
Object
  • Object
show all
Includes:
EventMachine::Deferrable
Defined in:
lib/rubydns/transaction.rb

Overview

This class provides all details of a single DNS question and answer. This is used by the DSL to provide DNS related functionality.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(server, query, question, resource_class, answer) ⇒ Transaction

Returns a new instance of Transaction.



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# File 'lib/rubydns/transaction.rb', line 30

def initialize(server, query, question, resource_class, answer)
	@server = server
	@query = query
	@question = question
	@resource_class = resource_class
	@answer = answer

	@deferred = false
	@question_appended = false
end

Instance Attribute Details

#answer ⇒ Object (readonly)

The current full answer to the incoming query.



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# File 'lib/rubydns/transaction.rb', line 52

def answer
  @answer
end

#query ⇒ Object (readonly)

The incoming query which is a set of questions.



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# File 'lib/rubydns/transaction.rb', line 46

def query
  @query
end

#question ⇒ Object (readonly)

The question that this transaction represents.



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# File 'lib/rubydns/transaction.rb', line 49

def question
  @question
end

#resource_class ⇒ Object (readonly)

The resource_class that was requested. This is typically used to generate a response.



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# File 'lib/rubydns/transaction.rb', line 43

def resource_class
  @resource_class
end

Instance Method Details

#append!(*resources) ⇒ Object

Append a given set of resources to the answer. The last argument can optionally be a hash of options.

options[:ttl]

Specify the TTL for the resource

options[:name]

Override the name (question) of the response.

This function can be used to supply multiple responses to a given question. For example, each argument is expected to be an instantiated resource from Resolv::DNS::Resource module.



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# File 'lib/rubydns/transaction.rb', line 173

def append! (*resources)
	append_question!

	options = resources.last.kind_of?(Hash) ? resources.pop.dup : {}
	options[:ttl] ||= 16000
	options[:name] ||= @question.to_s + "."

	resources.each do |resource|
		@server.logger.debug "add_answer: #{resource.inspect} #{resource.class::TypeValue} #{resource.class::ClassValue}"
		@answer.add_answer(options[:name], options[:ttl], resource)
	end

	# Raise an exception if there was something wrong with the resource
	@answer.encode

	true
end

#append_query!(name, resource_class = nil) ⇒ Object

Run a new query through the rules with the given name and resource type. The results of this query are appended to the current transactions answer.



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# File 'lib/rubydns/transaction.rb', line 66

def append_query!(name, resource_class = nil)
	Transaction.new(@server, @query, name, resource_class || @resource_class, @answer).process
end

#append_question! ⇒ Object 



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# File 'lib/rubydns/transaction.rb', line 220

def append_question!
	if @answer.question.size == 0
		@answer.add_question(@question, @resource_class) unless @question_appended
	end
end

#defer! ⇒ Object 



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# File 'lib/rubydns/transaction.rb', line 78

def defer!
	@deferred = true
end

#failure!(rcode) ⇒ Object

This function indicates that there was a failure to resolve the given question. The single argument must be an integer error code, typically given by the constants in Resolv::DNS::RCode.

The easiest way to use this function it to simply supply a symbol. Here is a list of the most commonly used ones:

:NoError

No error occurred.

:FormErr:: The incoming data was not formatted correctly.

:ServFail

The operation caused a server failure (internal error, etc).

:NXDomain

Non-eXistant Domain (domain record does not exist).

:NotImp

The operation requested is not implemented.

:Refused

The operation was refused by the server.

:NotAuth

The server is not authoritive for the zone.

See www.rfc-editor.org/rfc/rfc2929.txt for more information about DNS error codes (specifically, page 3).



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# File 'lib/rubydns/transaction.rb', line 208

def failure! (rcode)
	append_question!

	if rcode.kind_of? Symbol
		@answer.rcode = Resolv::DNS::RCode.const_get(rcode)
	else
		@answer.rcode = rcode.to_i
	end

	true
end

#name ⇒ Object

Return the name of the question, which is typically the requested hostname.



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# File 'lib/rubydns/transaction.rb', line 55

def name
	@question.to_s
end

#passthrough(resolver, options = {}, &block) ⇒ Object

Use the given resolver to respond to the question. If recursion is not requested, the result is failure!(:Refused). If the resolver does not respond, the result is failure!(:NXDomain)

If a block is supplied, this function yields with the reply and reply_name if successful. This block is responsible for doing something useful with the reply, such as merging it or conditionally discarding it.

A second argument, options, provides some control over the passthrough process. :force => true, ensures that the query will occur even if recursion is not requested.



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# File 'lib/rubydns/transaction.rb', line 111

def passthrough(resolver, options = {}, &block)
	if @query.rd || options[:force]
		# Resolver is asynchronous, so we are now deferred:
		defer!

		resolver.query(name, resource_class) do |response|
			case response
			when RubyDNS::Message
				yield response
				succeed(response)
			else
				fail(response)
			end
		end
	else
		failure!(:Refused)
	end
	
	true
end

#passthrough!(resolver, options = {}, &block) ⇒ Object

Use the given resolver to respond to the question. The default functionality is implemented by passthrough, and if a reply is received, it will be merged with the answer for this transaction.

If a block is supplied, this function yields with the reply and reply_name if successful. This could be used, for example, to update a cache or modify the reply.



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# File 'lib/rubydns/transaction.rb', line 89

def passthrough!(resolver, options = {}, &block)
	passthrough(resolver, options) do |response|
		if block_given?
			yield response
		end
		
		@answer.merge!(response)
	end
	
	true
end

#process(&finished) ⇒ Object 



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# File 'lib/rubydns/transaction.rb', line 70

def process(&finished)
	@server.process(name, @resource_class, self)

	unless @deferred
		succeed(self)
	end
end

#respond!(*data) ⇒ Object

Respond to the given query with a resource record. The arguments to this function depend on the resource_class requested. The last argument can optionally be a hash of options.

options[:resource_class]

Override the default resource_class

options[:ttl]

Specify the TTL for the resource

options[:name]

Override the name (question) of the response.

for A records

respond!("1.2.3.4")

for MX records

respond!("mail.blah.com", 10)

This function instantiates the resource class with the supplied arguments, and then passes it to append!.

See Resolv::DNS::Resource for more information about the various resource_classs available. www.ruby-doc.org/stdlib/libdoc/resolv/rdoc/index.html



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# File 'lib/rubydns/transaction.rb', line 149

def respond! (*data)
	options = data.last.kind_of?(Hash) ? data.pop : {}
	resource_class = options[:resource_class] || @resource_class
	
	if resource_class == nil
		raise ArgumentError, "Could not instantiate resource #{resource_class}!"
	end
	
	@server.logger.info "Resource class: #{resource_class.inspect}"
	resource = resource_class.new(*data)
	@server.logger.info "Resource: #{resource.inspect}"
	
	append!(resource, options)
end

#to_s ⇒ Object

Suitable for debugging purposes



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# File 'lib/rubydns/transaction.rb', line 60

def to_s
	"#{name} #{@resource_class.name}"
end