ama-team / cookbook-ssh-private-keys

# rubocop:disable Style/Documentation

require 'English'

require_relative 'exception/invalid_key_exception'

require_relative 'exception/ssh_keygen_missing_exception'

module AMA

  module Chef

    module SSHPrivateKeys

      class SSHKeygenHandler

        def initialize(binary)

          @binary = binary

        end

        def public_key_fingerprint(public_key)

          execution = run_with_temporary_file(public_key) do |path|

            return [@binary, '-l', '-f', path]

          end

          if execution.error

            message = 'Failed to generate fingerprint for ' \

              "public key #{public_key}"

            raise_execution_exception(execution, message)

          end

          execution

        end

        # @param [AMA::Chef::SSHPrivateKeys::Model::KeyPair] pair

        # @return [AMA::Chef::SSHPrivateKeys::Model::PublicKey]

        def generate_public_key(pair)

          execution = run_with_temporary_file(pair.private_key) do |path|

            [@binary, '-y', '-f', path, '-P', pair.passphrase.to_s]

          end

          if execution.error?

            message = "Failed to create public key from private key #{pair.id}"

            raise_execution_exception(execution, message)

          end

          raw = execution.stdout.chomp

          match_data = /([\w\-]+)\s+([^\s]+)\s*(.*)/.match(raw)

          unless match_data

            msg = "Failed to read public key created from private key: #{raw}"

            raise_invalid_key_exception(msg)

          end

          AMA::Chef::SSHPrivateKeys::Model::PublicKey.new.tap do |key|

            key.type = match_data[1]

            key.data = match_data[2]

            key.comment = match_data[3]

          end

        end

        def self.locate_binary

          execution = ::Mixlib::ShellOut.new('which', 'ssh-keygen')

          execution.run_command

          execution.error? ? nil : execution.stdout.lines.first.chomp

        end

        def self.locate_binary!

          binary = locate_binary

          return binary if binary

          raise(

            AMA::Chef::SSHPrivateKeys::Exception::SSHKeygenMissingException,

            'Failed to locate ssh-keygen binary for key validation'

          )

        end

        private

        def execute(*command)

          ::Chef::Log.debug("Executing command: #{command}")

          ::Mixlib::ShellOut.new(*command).tap(&:run_command)

        end

        def run_with_temporary_file(content)

          with_temporary_file(content) do |path|

            execute(*yield(path))

          end

        end

        def with_temporary_file(content)

          target = Tempfile.new(['ama-ssh-private-keys-'])

          ::IO.write(target.path, content)

          begin

            return yield(target.path)

          ensure

            target.close(true)

          end

        end

        def raise_execution_exception(execution, *message)

          message.push("STDOUT: #{execution.stdout}")

          message.push("STDERR: #{execution.stderr}")

          raise_invalid_key_exception(*message)

        end

      end

    end

  end

end