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 of multiple calls to this when the case closing ‘}’ hasn’t arrived yet



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# File 'lib/rjr/util/json_parser.rb', line 21

def self.extract_json_from(data) 
  return nil if data.nil? || data.empty?
  # start at beginning of data, find opening quote
  start  = 0
  start += 1 until start == data.length || data[start].chr == '{'

  escaped    = false
  in_quotes  = false
  quote_char = nil
  open_brackets = mark = 0

  # iterate over data stream
  start.upto(data.length - 1).each { |i|

    # toggle escaped flag in case of '\' or '\\'
    if in_quotes && data[i].chr == '\\'
      escaped = !escaped

    else
      # ignore escaped chars
      if !escaped

        # ignore brackets in quotes
        if !in_quotes
          if data[i].chr == '{'
            open_brackets += 1

          elsif data[i].chr == '}'
            open_brackets -= 1
          end
        end

        # track opening quote
        if data[i].chr == "'" || data[i].chr == '"'
          if !in_quotes
            in_quotes  = true
            quote_char = data[i]
          elsif quote_char == data[i]
            in_quotes = false
          end
        end
      end

      escaped = false
    end


    # finish at end of one json message
    if open_brackets == 0
      mark = i
      break
    end
  }
  
  return nil if mark == 0
  return data[start..mark], data[(mark+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 87

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 121

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 105

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 93

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