Class: RubyDNS::Transaction

Inherits:
Object
  • Object
show all
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.

The main functions to complete the trasaction are: #append! (evaluate a new query and append the results), #passthrough! (pass the query to an upstream server), #respond! (compute a specific response) and #fail! (fail with an error code).

Constant Summary collapse

DEFAULT_TTL =

The default time used for responses (24 hours).

86400

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(server, query, question, resource_class, answer, options = {}) ⇒ Transaction

Returns a new instance of Transaction.



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# File 'lib/rubydns/transaction.rb', line 35

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

	@options = options

	@question_appended = false

	@fiber = nil
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 59

def answer
  @answer
end

#options ⇒ Object (readonly)

Any options or configuration associated with the given transaction.



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# File 'lib/rubydns/transaction.rb', line 62

def options
  @options
end

#query ⇒ Object (readonly)

The incoming query which is a set of questions.



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# File 'lib/rubydns/transaction.rb', line 53

def query
  @query
end

#question ⇒ Object (readonly)

The question that this transaction represents.



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# File 'lib/rubydns/transaction.rb', line 56

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 50

def resource_class
  @resource_class
end

Instance Method Details

#[](key) ⇒ Object 



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# File 'lib/rubydns/transaction.rb', line 64

def [] key
	@options[key]
end

#add(resources, options = {}) ⇒ Object

Append a list of resources.

By default resources are appended to the answers section, but this can be changed by setting options[:section] to either :authority or :additional.

The time-to-live (TTL) of the resources can be specified using options[:ttl] and defaults to DEFAULT_TTL.



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# File 'lib/rubydns/transaction.rb', line 163

def add(resources, options = {})
	# Use the default options if provided:
	options = options.merge(@options)
	
	ttl = options[:ttl] || DEFAULT_TTL
	name = options[:name] || @question.to_s + "."
	
	section = (options[:section] || 'answer').to_sym
	method = "add_#{section}".to_sym
	
	resources.each do |resource|
		@server.logger.debug "#{method}: #{resource.inspect} #{resource.class::TypeValue} #{resource.class::ClassValue}"
		
		@answer.send(method, name, ttl, resource)
	end
end

#append!(name, resource_class = nil, options = {}) ⇒ 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 transaction's answer.



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# File 'lib/rubydns/transaction.rb', line 79

def append!(name, resource_class = nil, options = {})
	Transaction.new(@server, @query, name, resource_class || @resource_class, @answer, options).process
end

#fail!(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 RFC2929 for more information about DNS error codes (specifically, page 3).

This function will complete deferred transactions.



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# File 'lib/rubydns/transaction.rb', line 195

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

#failure!(*args) ⇒ Object

Deprecated. 


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# File 'lib/rubydns/transaction.rb', line 206

def failure!(*args)
	@server.logger.warn "failure! is deprecated, use fail! instead"
	
	fail!(*args)
end

#name ⇒ Object

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



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# File 'lib/rubydns/transaction.rb', line 69

def name
	@question.to_s
end

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

Use the given resolver to respond to the question.

A block must be supplied, and provided a valid response is received from the upstream server, this function yields with the reply and reply_name.

If options[:name] is provided, this overrides the default query name sent to the upstream server. The same logic applies to options[:resource_class].



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# File 'lib/rubydns/transaction.rb', line 113

def passthrough(resolver, options = {}, &block)
	query_name = options[:name] || name
	query_resource_class = options[:resource_class] || resource_class
	
	response = @server.defer do |handle|
		resolver.query(query_name, query_resource_class) do |response|
			# Not sure if this is potentially a race condition? Could fiber.resume occur before Fiber.yield?
			handle.resume(response)
		end
	end
	
	case response
	when RubyDNS::Message
		yield response
	when RubyDNS::ResolutionFailure
		fail!(:ServFail)
	else
		throw PassthroughError.new("Bad response from query: #{response.inspect}")
	end
end

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

Use the given resolver to respond to the question. Uses passthrough to do the lookup and merges the result.

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.

If recursion is not requested, the result is fail!(:Refused). This check is ignored if an explicit options[:name] or options[:force] is given.

If the resolver does not respond, the result is fail!(:NXDomain).



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# File 'lib/rubydns/transaction.rb', line 90

def passthrough!(resolver, options = {}, &block)
	if @query.rd || options[:force] || options[:name]
		passthrough(resolver, options) do |response|
			if block_given?
				yield response
			end
			
			# Recursion is available and is being used:
			# See issue #26 for more details.
			@answer.ra = 1
			
			@answer.merge!(response)
		end
	else
		raise PassthroughError.new("Request is not recursive!")
	end
end

#process ⇒ Object

A helper method to process the transaction on the given server. Unless the transaction is deferred, it will #succeed on completion.



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# File 'lib/rubydns/transaction.rb', line 213

def process
	@server.process(name, @resource_class, self)
end

#respond!(*args) ⇒ Object

The last argument can optionally be a hash of options. If options[:resource_class] is provided, it overrides the default resource class of transaction. Additional options are passed to #append!.

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



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# File 'lib/rubydns/transaction.rb', line 141

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

#to_s ⇒ Object

Shows the question name and resource class. Suitable for debugging purposes.



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# File 'lib/rubydns/transaction.rb', line 74

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