Module: ActiveElasticJob::MD5MessageDigestCalculation

Included in:
ActiveJob::QueueAdapters::ActiveElasticJobAdapter
Defined in:
lib/active_elastic_job/md5_message_digest_calculation.rb

Overview

This module provides methods that calculate the MD5 digest for Amazon SQS message bodies and message attributes. The digest can be used to verify that Amazon SQS received the message correctly.

Example:

extend ActiveElasticJob::MD5MessageDigestCalculation

resp = Aws::SQS::Client.new.send_message(
  queue_url: queue_url,
  message_body: body,
  message_attributes: attributes
)

if resp.md5_of_message_body != md5_of_message_body(body)
  raise "Returned digest of message body is invalid!"
end

if resp.md5_of_message_attributes != md5_of_message_attributes(attributes)
  raise "Returned digest of message attributes is invalid!"
end

Constant Summary collapse

TRANSPORT_TYPE_ENCODINGS = 
{
  'String' => 1,
  'Binary' => 2,
  'Number' => 1
}
CHARSET_ENCODING = 
Encoding::UTF_8

Instance Method Summary collapse

Instance Method Details

#md5_of_message_attributes(message_attributes) ⇒ Object

Returns MD5 digest of message_attributes.

The calculation follows the official algorithm which is specified by Amazon.



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# File 'lib/active_elastic_job/md5_message_digest_calculation.rb', line 43

def md5_of_message_attributes(message_attributes)
  encoded = message_attributes.each.with_object({ }) do |(name, v), hash|
    hash[name.to_s] = ""
    data_type = v['data_type'] || v[:data_type]

    hash[name.to_s] << encode_length_and_bytes(name.to_s) <<
      encode_length_and_bytes(data_type) <<
      [ TRANSPORT_TYPE_ENCODINGS[data_type] ].pack('C')

    if string_value = v['string_value'] || v[:string_value]
      hash[name.to_s] << encode_length_and_string(string_value)
    elsif binary_value = v['binary_value'] || v[:binary_value]
      hash[name.to_s] << encode_length_and_bytes(binary_value)
    end
  end

  buffer = encoded.keys.sort.reduce("") do |b, name|
    b << encoded[name]
  end
  OpenSSL::Digest::MD5.hexdigest(buffer)
end

#md5_of_message_body(message_body) ⇒ Object

Returns MD5 digest of message_body.



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# File 'lib/active_elastic_job/md5_message_digest_calculation.rb', line 35

def md5_of_message_body(message_body)
  OpenSSL::Digest::MD5.hexdigest(message_body)
end