Module: Cerner::OAuth1a::Internal

Defined in:
lib/cerner/oauth1a/internal.rb

Overview

Internal: Internal utility methods

Class Method Summary collapse

Class Method Details

.constant_time_compare(left, right) ⇒ Object

Internal: Compares two Strings using a constant time algorithm to protect against timing attacks.

left - The left String right - The right String

Return true if left and right match, false otherwise.



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# File 'lib/cerner/oauth1a/internal.rb', line 72

def self.constant_time_compare(left, right)
  max_size = [left.bytesize, right.bytesize].max
  # convert left and right to array of bytes (Integer)
  left = left.unpack('C*')
  right = right.unpack('C*')

  # if either array is not the max size, expand it with zeros
  # having equal arrays keeps the algorithm execution time constant
  left = left.fill(0, left.size, max_size - left.size) if left.size < max_size
  right = right.fill(0, right.size, max_size - right.size) if right.size < max_size

  result = 0
  left.each_with_index do |left_value, i|
    # XOR the two bytes, if equal, the operation is 0
    # OR the XOR operation with the previous result
    result |= left_value ^ right[i]
  end

  # if every comparison resuled in 0, then left and right are equal
  result.zero?
end

.convert_to_http_uri(url:, name: 'url') ⇒ Object

Internal: Convert an fully qualified URL String into a URI with some verification checks

keywords - The keyword arguments:

:url  - A String or a URI instance to convert to a URI instance.
:name - The parameter name of the URL for invoking methods.

Returns a URI::HTTP or URI::HTTPS

Raises ArgumentError if url is nil, invalid or not an HTTP/HTTPS URI

Raises:

  • (ArgumentError) 


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# File 'lib/cerner/oauth1a/internal.rb', line 32

def self.convert_to_http_uri(url:, name: 'url')
  raise ArgumentError, "#{name} is nil" unless url

  if url.is_a?(URI)
    uri = url
  else
    begin
      uri = URI(url)
    rescue URI::InvalidURIError
      # raise argument error with cause
      raise ArgumentError, "#{name} is invalid"
    end
  end

  raise ArgumentError, "#{name} must be an HTTP or HTTPS URI" unless uri.is_a?(URI::HTTP)

  uri
end

.convert_to_time(time:, name: 'time') ⇒ Object

Internal: Convert a time value into a Time instance.

keywords - The keyword arguments:

:time - Time or any object with a #to_i that returns an Integer.
:name - The parameter name of the data for invoking methods.

Returns a Time instance in the UTC time zone.

Raises:

  • (ArgumentError) 


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# File 'lib/cerner/oauth1a/internal.rb', line 17

def self.convert_to_time(time:, name: 'time')
  raise ArgumentError, "#{name} is nil" unless time

  time.is_a?(Time) ? time.utc : Time.at(time.to_i).utc
end

.generate_nonce ⇒ Object

Internal: Generate a Nonce for invocations of the Access Token service.

Returns a String containing the nonce.



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# File 'lib/cerner/oauth1a/internal.rb', line 54

def self.generate_nonce
  SecureRandom.hex
end

.generate_timestamp ⇒ Object

Internal: Generate a Timestamp for invocations of the Access Token service.

Returns an Integer representing the number of seconds since the epoch.



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# File 'lib/cerner/oauth1a/internal.rb', line 61

def self.generate_timestamp
  Time.now.to_i
end