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.



35
36
37
38
39
40
41
42
43
44
45
46
47
 
# 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.



59
60
61
 
# File 'lib/rubydns/transaction.rb', line 59

def answer
  @answer
end

#options ⇒ Object (readonly)

Any options or configuration associated with the given transaction.



62
63
64
 
# File 'lib/rubydns/transaction.rb', line 62

def options
  @options
end

#query ⇒ Object (readonly)

The incoming query which is a set of questions.



53
54
55
 
# File 'lib/rubydns/transaction.rb', line 53

def query
  @query
end

#question ⇒ Object (readonly)

The question that this transaction represents.



56
57
58
 
# 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.



50
51
52
 
# File 'lib/rubydns/transaction.rb', line 50

def resource_class
  @resource_class
end

Instance Method Details

#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.



159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
 
# File 'lib/rubydns/transaction.rb', line 159

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.



75
76
77
 
# File 'lib/rubydns/transaction.rb', line 75

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.



191
192
193
194
195
196
197
198
199
 
# File 'lib/rubydns/transaction.rb', line 191

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. 


202
203
204
205
206
 
# File 'lib/rubydns/transaction.rb', line 202

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.



65
66
67
 
# File 'lib/rubydns/transaction.rb', line 65

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].



109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
 
# File 'lib/rubydns/transaction.rb', line 109

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).



86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
 
# File 'lib/rubydns/transaction.rb', line 86

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.



209
210
211
 
# File 'lib/rubydns/transaction.rb', line 209

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).



137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
 
# File 'lib/rubydns/transaction.rb', line 137

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.



70
71
72
 
# File 'lib/rubydns/transaction.rb', line 70

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