#
# Author:: Tim Dysinger (<tim@dysinger.net>)
# Author:: Benjamin Black (<bb@chef.io>)
# Author:: Christopher Brown (<cb@chef.io>)
# Author:: Tim Smith (<tsmith@chef.io>)
# Copyright:: Copyright (c) 2009-2016 Chef Software, Inc.
# License:: Apache License, Version 2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# How we detect EC2 from easiest to hardest & least reliable
# 1. Ohai ec2 hint exists. This always works
# 2. Xen hypervisor UUID starts with 'ec2'. This catches Linux HVM & paravirt instances
# 3. DMI data mentions amazon. This catches HVM instances in a VPC
# 4. Kernel data mentioned Amazon. This catches Windows HVM & paravirt instances

require "ohai/mixin/ec2_metadata"
require "base64"

Ohai.plugin(:EC2) do
  include Ohai::Mixin::Ec2Metadata

  provides "ec2"

  depends "dmi"
  depends "kernel"

  # look for amazon string in dmi bios data
  # this gets us detection of HVM instances that are within a VPC
  def has_ec2_dmi?
    begin
      # detect a version of '4.2.amazon'
      if dmi[:bios][:all_records][0][:Version] =~ /amazon/
        Ohai::Log.debug("Plugin EC2: has_ec2_dmi? == true")
        return true
      end
    rescue NoMethodError
      # dmi[:bios][:all_records][0][:Version] may not exist
    end
    Ohai::Log.debug("Plugin EC2: has_ec2_dmi? == false")
    return false
  end

  # looks for a xen UUID that starts with ec2
  # this gets us detection of Linux HVM and Paravirt hosts
  def has_ec2_xen_uuid?
    if ::File.exist?("/sys/hypervisor/uuid")
      if ::File.read("/sys/hypervisor/uuid") =~ /^ec2/
        Ohai::Log.debug("Plugin EC2: has_ec2_xen_uuid? == true")
        return true
      end
    end
    Ohai::Log.debug("Plugin EC2: has_ec2_xen_uuid? == false")
    return false
  end

  # looks for the Amazon.com Organization in Windows Kernel data
  # this gets us detection of Windows systems
  def has_amazon_org?
    begin
      # detect an Organization of 'Amazon.com'
      if kernel[:os_info][:organization] =~ /Amazon/
        Ohai::Log.debug("Plugin EC2: has_amazon_org? == true")
        return true
      end
    rescue NoMethodError
      # kernel[:os_info][:organization] may not exist
    end
    Ohai::Log.debug("Plugin EC2: has_amazon_org? == false")
    return false
  end

  def looks_like_ec2?
    return true if hint?("ec2")

    # Even if it looks like EC2 try to connect first
    if has_ec2_xen_uuid? || has_ec2_dmi? || has_amazon_org?
      return true if can_metadata_connect?(Ohai::Mixin::Ec2Metadata::EC2_METADATA_ADDR, 80)
    end
  end

  collect_data do
    if looks_like_ec2?
      Ohai::Log.debug("Plugin EC2: looks_like_ec2? == true")
      ec2 Mash.new
      fetch_metadata.each do |k, v|
        # fetch_metadata returns IAM security credentials, including the IAM user's
        # secret access key. We'd rather not have ohai send this information
        # to the server.
        # http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AESDG-chapter-instancedata.html#instancedata-data-categories
        next if k == "iam" && !hint?("iam")
        ec2[k] = v
      end
      ec2[:userdata] = fetch_userdata
      # ASCII-8BIT is equivalent to BINARY in this case
      if ec2[:userdata] && ec2[:userdata].encoding.to_s == "ASCII-8BIT"
        Ohai::Log.debug("Plugin EC2: Binary UserData Found. Storing in base64")
        ec2[:userdata] = Base64.encode64(ec2[:userdata])
      end
    else
      Ohai::Log.debug("Plugin EC2: looks_like_ec2? == false")
      false
    end
  end
end