Class: Heroic::SNS::Message

Inherits:
Object
  • Object
show all
Defined in:
lib/heroic/sns/message.rb

Overview

Encapsulates an SNS message. Since Endpoint takes care of authenticating the message, most of the time you will simply be interested in retrieving the subject and body from the message and acting on it.

See: docs.aws.amazon.com/sns/latest/gsg/json-formats.html

Instance Method Summary collapse

Constructor Details

#initialize(json) ⇒ Message

Returns a new instance of Message.



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# File 'lib/heroic/sns/message.rb', line 32

def initialize(json)
  @msg = ::JSON.parse(json)
rescue JSON::ParserError => e
  raise Error.new("failed to parse message as JSON: #{e.message}")
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 99

def ==(other)
  other.is_a?(Message) && @msg == other.instance_variable_get(:@msg)
end

#body ⇒ Object

The message payload. As far as Amazon and this class are concerned, the message payload is just a string of bytes. If you are expecting, for example, a JSON object, you will need to pass this to a JSON parser.



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# File 'lib/heroic/sns/message.rb', line 81

def body
  @msg['Message']
end

#hash ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 103

def hash
  @msg.hash
end

#id ⇒ Object

A Universally Unique Identifier, unique for each message published. For a notification that Amazon SNS resends during a retry, the message ID of the original message is used.



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# File 'lib/heroic/sns/message.rb', line 51

def id
  @msg['MessageId']
end

#signature ⇒ Object

The message signature data, Base-64 decoded.



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# File 'lib/heroic/sns/message.rb', line 69

def signature
  Base64::decode64(@msg['Signature'])
end

#signature_version ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 60

def signature_version
  @msg['SignatureVersion']
end

#signing_cert_url ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 64

def signing_cert_url
  @msg['SigningCertURL']
end

#subject ⇒ Object

The message may not have a subject.



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# File 'lib/heroic/sns/message.rb', line 74

def subject
  @msg['Subject']
end

#subscribe_url ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 85

def subscribe_url
  @msg['SubscribeURL']
end

#timestamp ⇒ Object

The timestamp when the message was published, as a Time object.



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# File 'lib/heroic/sns/message.rb', line 56

def timestamp
  Time.xmlschema(@msg['Timestamp'])
end

#to_json ⇒ Object

Returns a JSON serialization of the message. Note that it may not be identical to the serialization that was retrieved from the network.



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# File 'lib/heroic/sns/message.rb', line 117

def to_json
  @msg.to_json
end

#to_s ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 107

def to_s
  string = "<SNSMessage:\n"
  @msg.each do |k,v|
    string << sprintf("  %s: %s\n", k, v.inspect)
  end
  string << ">"
end

#token ⇒ Object

The token is used to confirm subscriptions via the SNS API. If you visit the subscribe_url, you can ignore this field.



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# File 'lib/heroic/sns/message.rb', line 95

def token
  @msg['Token']
end

#topic_arn ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 44

def topic_arn
  @msg['TopicArn']
end

#type ⇒ Object

The message type will be one of SubscriptionConfirmation, UnsubscribeConfirmation, and Notification.



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# File 'lib/heroic/sns/message.rb', line 40

def type
  @msg['Type']
end

#unsubscribe_url ⇒ Object 



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# File 'lib/heroic/sns/message.rb', line 89

def unsubscribe_url
  @msg['UnsubscribeURL']
end

#verify! ⇒ Object

Verifies the message signature. Raises Error if it is not valid.

See: docs.aws.amazon.com/sns/latest/gsg/SendMessageToHttp.verify.signature.html

Raises:



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# File 'lib/heroic/sns/message.rb', line 124

def verify!
  age = Time.now - timestamp
  raise Error.new("timestamp is in the future, age: #{age}", self) if age < 0
  raise Error.new("timestamp is too old", self) if age > MAXIMUM_ALLOWED_AGE
  if signature_version != '1'
    raise Error.new("unknown signature version: #{signature_version}", self)
  end
  if signing_cert_url !~ VALID_AWS_URL_PATTERN
    raise Error.new("signing certificate is not from amazonaws.com", self)
  end
  text = string_to_sign # will warn of invalid Type
  cert = CERTIFICATE_CACHE.get(signing_cert_url)
  digest = OpenSSL::Digest::SHA1.new
  unless cert.public_key.verify(digest, signature, text)
    raise Error.new("message signature is invalid", self)
  end
end