add a script that can modify existing licenses

src/modify.license.rb

@@ -0,0 +1,71 @@
+#!/usr/bin/env ruby
+# encoding: utf-8
+
+require 'base64'
+require 'json'
+require 'openssl'
+require 'tempfile'
+require 'optparse'
+require_relative '../lib/license/encryptor'
+
+public_key_path = nil
+in_file = nil
+
+OptionParser.new do |opts|
+  opts.banner = "Usage: xxx.rb [options]"
+
+  opts.on("-k", "--public-key PATH", "Specify public key file (required)") do |v|
+    public_key_path = File.expand_path(v)
+  end
+
+  opts.on("-i", "--in PATH", "input license path") do |v|
+    in_file = File.expand_path(v)
+  end
+
+  opts.on("-h", "--help", "Prints this help") do
+    puts opts
+    exit
+  end
+end
+            .parse!
+
+if in_file.nil? || public_key_path.nil?
+  puts "[!] missing required options"
+  puts "[!] use -h for help"
+  exit 1
+end
+
+content = File.read(in_file)
+attributes = JSON.parse(Base64.decode64(content))
+
+PUBLIC_KEY = OpenSSL::PKey::RSA.new File.read(public_key_path)
+decryptor = Gitlab::License::Encryptor.new(PUBLIC_KEY)
+plain_license = decryptor.decrypt(content)
+edited_json = nil
+
+Tempfile.create(['json_edit', '.json']) do |file|
+  file.write(JSON.pretty_generate(JSON.parse(plain_license)))
+  file.flush
+
+  system("vim #{file.path}")
+  file.rewind
+  edited_json = file.read
+end
+
+edited_json = JSON.generate(JSON.parse(edited_json))
+
+cipher = OpenSSL::Cipher::AES128.new(:CBC)
+cipher.encrypt
+cipher.key = PUBLIC_KEY.public_decrypt(Base64.decode64(attributes['key']))
+cipher.iv = Base64.decode64(attributes['iv'])
+
+encrypted_data = cipher.update(edited_json) + cipher.final
+
+encryption_data = {
+  'data' => Base64.encode64(encrypted_data),
+  'key' => attributes['key'],
+  'iv' => attributes['iv']
+}
+
+json_data = JSON.dump(encryption_data)
+puts Base64.encode64(json_data)