#
# Cookbook Name:: firewall
# Provider:: rule_iptables
#
# Copyright 2012, computerlyrik
#
# 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.
#
require 'poise'

class Chef
  class Provider::FirewallRuleIptables < Provider
    include Poise
    include Chef::Mixin::ShellOut
    include FirewallCookbook::Helpers

    def action_allow
      apply_rule(:allow)
    end

    def action_deny
      apply_rule(:deny)
    end

    def action_reject
      apply_rule(:reject)
    end

    def action_redirect
      apply_rule(:redirect)
    end

    def action_masquerade
      apply_rule(:masquerade)
    end

    def action_log
      apply_rule(:log)
    end

    def action_remove
      # TODO: specify which target to delete
      # for now this will remove raw + all targeted lines
      remove_rule(:allow)
      remove_rule(:deny)
      remove_rule(:reject)
      remove_rule(:redirect)
      remove_rule(:masquerade)
    end

    private

    CHAIN = { :in => 'INPUT', :out => 'OUTPUT', :pre => 'PREROUTING', :post => 'POSTROUTING' } unless defined? CHAIN # , nil => "FORWARD"}
    TARGET = { :allow => 'ACCEPT', :reject => 'REJECT', :deny => 'DROP', :masquerade => 'MASQUERADE', :redirect => 'REDIRECT', :log => 'LOG --log-prefix "iptables: " --log-level 7' } unless defined? TARGET

    def apply_rule(type = nil)
      firewall_commands = determine_iptables_commands
      firewall_commands.each do |firewall_command|
        ipv6 = (firewall_command == 'ip6tables') ? true : false
        if new_resource.position
          firewall_command << ' -I '
        else
          firewall_command << ' -A '
        end

        # TODO: implement logging for :connections :packets
        firewall_rule = build_firewall_rule(type)

        Chef::Log.debug("#{new_resource}: #{firewall_rule}")
        if rule_exists?(firewall_rule, ipv6)
          Chef::Log.info("#{new_resource} #{type} rule exists... won't apply")
        else
          cmdstr = firewall_command + firewall_rule
          converge_by("firewall_rule[#{new_resource.name}] #{firewall_rule}") do
            notifying_block do
              shell_out!(cmdstr) # shell_out! is already logged
              new_resource.updated_by_last_action(true)
            end
          end
        end
      end
    end

    def remove_rule(type = nil)
      firewall_commands = determine_iptables_commands
      firewall_commands.each do |firewall_command|
        ipv6 = (firewall_command == 'ip6tables') ? true : false

        # TODO: implement logging for :connections :packets
        firewall_rule = build_firewall_rule(type)

        Chef::Log.debug("#{new_resource}: #{firewall_rule}")
        if rule_exists?(firewall_rule, ipv6)
          cmdstr = firewall_command + firewall_rule
          converge_by("firewall_rule[#{new_resource.name}] #{firewall_rule}") do
            notifying_block do
              shell_out!(cmdstr) # shell_out! is already logged
              new_resource.updated_by_last_action(true)
            end
          end
        else
          Chef::Log.info("#{new_resource} #{type} rule does not exist... won't remove")
        end
      end
    end

    def ipv4_rule?
      if (new_resource.source && IPAddr.new(new_resource.source).ipv4?) ||
         (new_resource.destination && IPAddr.new(new_resource.destination).ipv4?)
        true
      else
        false
      end
    end

    def ipv6_rule?
      if (new_resource.source && IPAddr.new(new_resource.source).ipv6?) ||
         (new_resource.destination && IPAddr.new(new_resource.destination).ipv6?)
        true
      else
        false
      end
    end

    def determine_iptables_commands
      if ipv4_rule?
        commands = ['iptables']
      elsif ipv6_rule?
        commands = ['ip6tables']
      else # no source or destination address, add rules for both ipv4 and ipv6
        commands = %w(iptables ip6tables)
      end
      commands
    end

    def build_firewall_rule(type = nil)
      if new_resource.raw
        firewall_rule = new_resource.raw.strip
      else
        firewall_rule = ''
        if new_resource.direction
          firewall_rule << "#{CHAIN[new_resource.direction.to_sym]} "
        else
          firewall_rule << 'FORWARD '
        end
        firewall_rule << "#{new_resource.position} " if new_resource.position

        if [:pre, :post].include?(new_resource.direction)
          firewall_rule << '-t nat '
        end

        # Iptables order of prameters is important here see example output below:
        # -A INPUT -s 1.2.3.4/32 -d 5.6.7.8/32 -i lo -p tcp -m tcp -m state --state NEW -m comment --comment "hello" -j DROP
        firewall_rule << "-s #{ip_with_mask(new_resource.source)} " if new_resource.source && new_resource.source != '0.0.0.0/0'
        firewall_rule << "-d #{new_resource.destination} " if new_resource.destination

        firewall_rule << "-i #{new_resource.interface} " if new_resource.interface
        firewall_rule << "-o #{new_resource.dest_interface} " if new_resource.dest_interface

        firewall_rule << "-p #{new_resource.protocol} " if new_resource.protocol
        firewall_rule << '-m tcp ' if new_resource.protocol.to_sym == :tcp

        # using multiport here allows us to simplify our greps and rule building
        firewall_rule << "-m multiport --sports #{port_to_s(new_resource.source_port)} " if new_resource.source_port
        firewall_rule << "-m multiport --dports #{port_to_s(dport_calc)} " if dport_calc

        firewall_rule << "-m state --state #{new_resource.stateful.is_a?(Array) ? new_resource.stateful.join(',').upcase : new_resource.stateful.upcase} " if new_resource.stateful
        firewall_rule << "-m comment --comment \"#{new_resource.description}\" "
        firewall_rule << "-j #{TARGET[type]} "
        firewall_rule << "--to-ports #{new_resource.redirect_port} " if type == 'redirect'
        firewall_rule.strip!
      end
      firewall_rule
    end

    def rule_exists?(rule, ipv6 = false)
      fail 'no rule supplied' unless rule
      if new_resource.position
        detect_rule = rule.gsub(/#{CHAIN[new_resource.direction]}\s(\d+)/, '\1' + " -A #{CHAIN[new_resource.direction]}")
      else
        detect_rule = rule
      end

      # match quotes generously
      detect_rule = detect_rule.gsub(/'/, "'*")
      detect_rule = detect_rule.gsub(/"/, '"*')

      line_number = 0
      match = shell_out!(ipv6 ? 'ip6tables-save' : 'iptables-save').stdout.lines.find do |line|
        next if line !~ /#{CHAIN[new_resource.direction]}/
        next if line[0] != '-'
        line_number += 1
        line = "#{line_number} #{line}" if new_resource.position
        # Chef::Log.debug("matching: [#{detect_rule}] to [#{line.chomp.rstrip}]")
        line =~ /#{detect_rule}/
      end

      match
    rescue Mixlib::ShellOut::ShellCommandFailed
      Chef::Log.debug("#{new_resource} check fails with: " + match.inspect)
      Chef::Log.debug("#{new_resource} assuming #{rule} rule does not exist")
      false
    end

    def dport_calc
      new_resource.dest_port || new_resource.port
    end

    def ip_with_mask(ip)
      if ip.include?('/')
        ip
      elsif ipv4_rule?
        "#{ip}/32"
      elsif ipv6_rule?
        "#{ip}/128"
      else
        ip
      end
    end
  end
end