Class: RJR::JSONParser

Inherits:
Object show all
Defined in:
lib/rjr/util/json_parser.rb

Overview

Provides utilities / helpers to parse json in a sane/safe manner

Class Method Summary collapse

Class Method Details

.extract_json_from(data) ⇒ Object

Extract and return a single json message from a data string.

Returns the message and remaining portion of the data string, if message is found, else nil

TODO efficiency can probably be optimized in the case closing ‘}’ hasn’t arrived yet

FIXME if uneven brackets appears in string data (such as in params) this will break, detect when in string and ignore in counts



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# File 'lib/rjr/util/json_parser.rb', line 24

def self.extract_json_from(data) 
  return nil if data.nil? || data.empty?
  start  = 0
  start += 1 until start == data.length || data[start].chr == '{'
  on = mi = 0 
  start.upto(data.length - 1).each { |i|
    if data[i].chr == '{'
      on += 1
    elsif data[i].chr == '}'
      on -= 1
    end

    if on == 0
      mi = i
      break
    end
  }
  
  return nil if mi == 0
  return data[start..mi], data[(mi+1)..-1]
end

.invalid_json_class?(jc) ⇒ Boolean

Return bool indicating if json class is invalid in context of rjr & cannot be parsed.

An invalid class is one not on whitelist if enabled or one not in ruby class heirachy.

Implements a safe mechanism which to validate json data to parse

Returns:

  • (Boolean) 


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# File 'lib/rjr/util/json_parser.rb', line 54

def self.invalid_json_class?(jc)
  Class.whitelist_json_classes ||= false
  Class.whitelist_json_classes ?
    !Class.permitted_json_classes.include?(jc) : jc.to_s.to_class.nil?
end

.parse(js) ⇒ Object

Two stage json parser. For more details why this is required see json issue:

https://github.com/flori/json/issues/179

FIXME this will only work for json >= 1.7.6 where create_additions is defined



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# File 'lib/rjr/util/json_parser.rb', line 88

def self.parse(js)
  jp = ::JSON.parse js, :create_additions => false
  if jp.is_a?(Array)
    validate_json_array(jp)
  elsif jp.is_a?(Hash)
    validate_json_hash(jp)
  else
    return jp
  end
  ::JSON.parse js, :create_additions => true
end

.validate_json_array(ja) ⇒ Object 



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# File 'lib/rjr/util/json_parser.rb', line 72

def self.validate_json_array(ja)
  ja.each { |jai|
    if jai.is_a?(Array)
      validate_json_array(jai)
    elsif jai.is_a?(Hash)
      validate_json_hash(jai)
    end
  }
end

.validate_json_hash(jh) ⇒ Object 



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# File 'lib/rjr/util/json_parser.rb', line 60

def self.validate_json_hash(jh)
  jh.each { |k,v|
    if k == ::JSON.create_id && invalid_json_class?(v)
      raise ArgumentError, "can't create json class #{v}"
    elsif v.is_a?(Array)
      validate_json_array(v)
    elsif v.is_a?(Hash)
      validate_json_hash(v)
    end
  }
end