# standard module for determining whether a given hostname or IP has access to
# the requested resource

require 'ipaddr'
require 'puppet/util/logging'

module Puppet
  class AuthStoreError < Puppet::Error; end
  class AuthorizationError < Puppet::Error; end

  class Network::AuthStore
    include Puppet::Util::Logging

    # Is a given combination of name and ip address allowed?  If either input
    # is non-nil, then both inputs must be provided.  If neither input
    # is provided, then the authstore is considered local and defaults to "true".
    def allowed?(name, ip)
      if name or ip
        # This is probably unnecessary, and can cause some weirdness in
        # cases where we're operating over localhost but don't have a real
        # IP defined.
        raise Puppet::DevError, _("Name and IP must be passed to 'allowed?'") unless name and ip
        # else, we're networked and such
      else
        # we're local
        return true
      end

      # yay insecure overrides
      return true if globalallow?

      if decl = declarations.find { |d| d.match?(name, ip) }
        return decl.result
      end

      info _("defaulting to no access for %{name}") % { name: name }
      false
    end

    # Mark a given pattern as allowed.
    def allow(pattern)
      # a simple way to allow anyone at all to connect
      if pattern == "*"
        @globalallow = true
      else
        store(:allow, pattern)
      end

      nil
    end

    def allow_ip(pattern)
      store(:allow_ip, pattern)
    end

    # Deny a given pattern.
    def deny(pattern)
      store(:deny, pattern)
    end

    def deny_ip(pattern)
      store(:deny_ip, pattern)
    end

    # Is global allow enabled?
    def globalallow?
      @globalallow
    end

    # does this auth store has any rules?
    def empty?
      @globalallow.nil? && @declarations.size == 0
    end

    def initialize
      @globalallow = nil
      @declarations = []
    end

    def to_s
      "authstore"
    end

    def interpolate(match)
      @modified_declarations = @declarations.collect { |ace| ace.interpolate(match) }.sort
    end

    def reset_interpolation
      @modified_declarations = nil
    end

    private

    # Returns our ACEs list, but if we have a modification of it, let's return
    # it. This is used if we want to override the this purely immutable list
    # by a modified version.
    def declarations
      @modified_declarations || @declarations
    end

    # Store the results of a pattern into our hash.  Basically just
    # converts the pattern and sticks it into the hash.
    def store(type, pattern)
      @declarations << Declaration.new(type, pattern)
      @declarations.sort!

      nil
    end

    # A single declaration.  Stores the info for a given declaration,
    # provides the methods for determining whether a declaration matches,
    # and handles sorting the declarations appropriately.
    class Declaration
      include Puppet::Util
      include Comparable

      # The type of declaration: either :allow or :deny
      attr_reader :type
      VALID_TYPES = [ :allow, :deny, :allow_ip, :deny_ip ]

      attr_accessor :name

      # The pattern we're matching against.  Can be an IPAddr instance,
      # or an array of strings, resulting from reversing a hostname
      # or domain name.
      attr_reader :pattern

      # The length.  Only used for iprange and domain.
      attr_accessor :length

      # Sort the declarations most specific first.
      def <=>(other)
        compare(exact?, other.exact?) ||
        compare(ip?, other.ip?)  ||
        ((length != other.length) &&  (other.length <=> length)) ||
        compare(deny?, other.deny?) ||
        ( ip? ? pattern.to_s <=> other.pattern.to_s : pattern <=> other.pattern)
      end

      def deny?
        type == :deny
      end

      def exact?
        @exact == :exact
      end

      def initialize(type, pattern)
        self.type = type
        self.pattern = pattern
      end

      # Are we an IP type?
      def ip?
        name == :ip
      end

      # Does this declaration match the name/ip combo?
      def match?(name, ip)
        if ip?
          pattern.include?(IPAddr.new(ip))
        else
          matchname?(name)
        end
      end

      # Set the pattern appropriately.  Also sets the name and length.
      def pattern=(pattern)
        if [:allow_ip, :deny_ip].include?(self.type)
          parse_ip(pattern)
        else
          parse(pattern)
        end
        @orig = pattern
      end

      # Mapping a type of statement into a return value.
      def result
        [:allow, :allow_ip].include?(type)
      end

      def to_s
        "#{type}: #{pattern}"
      end

      # Set the declaration type.  Either :allow or :deny.
      def type=(type)
        type = type.intern
        raise ArgumentError, _("Invalid declaration type %{type}") % { type: type } unless VALID_TYPES.include?(type)
        @type = type
      end

      # interpolate a pattern to replace any
      # backreferences by the given match
      # for instance if our pattern is $1.reductivelabs.com
      # and we're called with a MatchData whose capture 1 is puppet
      # we'll return a pattern of puppet.reductivelabs.com
      def interpolate(match)
        clone = dup
        if @name == :dynamic
          clone.pattern = clone.pattern.reverse.collect do |p|
            p.gsub(/\$(\d)/) { |m| match[$1.to_i] }
          end.join(".")
        end
        clone
      end

      private

      # Returns nil if both values are true or both are false, returns
      # -1 if the first is true, and 1 if the second is true.  Used
      # in the <=> operator.
      def compare(me, them)
        (me and them) ? nil : me ? -1 : them ? 1 : nil
      end

      # Does the name match our pattern?
      def matchname?(name)
        case @name
          when :domain, :dynamic, :opaque
            name = munge_name(name)
            (pattern == name) or (not exact? and pattern.zip(name).all? { |p,n| p == n })
          when :regex
            Regexp.new(pattern.slice(1..-2)).match(name)
        end
      end

      # Convert the name to a common pattern.
      def munge_name(name)
        # Change to name.downcase.split(".",-1).reverse for FQDN support
        name.downcase.split(".").reverse
      end

      # Parse our input pattern and figure out what kind of allowable
      # statement it is.  The output of this is used for later matching.
      Octet = '(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])'
      IPv4 = "#{Octet}\.#{Octet}\.#{Octet}\.#{Octet}"
      IPv6_full    = "_:_:_:_:_:_:_:_|_:_:_:_:_:_::_?|_:_:_:_:_::((_:)?_)?|_:_:_:_::((_:){0,2}_)?|_:_:_::((_:){0,3}_)?|_:_::((_:){0,4}_)?|_::((_:){0,5}_)?|::((_:){0,6}_)?"
      IPv6_partial = "_:_:_:_:_:_:|_:_:_:_::(_:)?|_:_::(_:){0,2}|_::(_:){0,3}"
      # It should be:
      #     IP = "#{IPv4}|#{IPv6_full}|(#{IPv6_partial}#{IPv4})".gsub(/_/,'([0-9a-fA-F]{1,4})').gsub(/\(/,'(?:')
      # but ruby's ipaddr lib doesn't support the hybrid format
      IP = "#{IPv4}|#{IPv6_full}".gsub(/_/,'([0-9a-fA-F]{1,4})').gsub(/\(/,'(?:')

      def parse_ip(value)
        @name = :ip
        @exact, @length, @pattern = *case value
        when /^(?:#{IP})\/(\d+)$/                                 # 12.34.56.78/24, a001:b002::efff/120, c444:1000:2000::9:192.168.0.1/112
          [:inexact, $1.to_i, IPAddr.new(value)]
        when /^(#{IP})$/                                          # 10.20.30.40,
          [:exact, nil, IPAddr.new(value)]
        when /^(#{Octet}\.){1,3}\*$/                              # an ip address with a '*' at the end
          segments = value.split(".")[0..-2]
          bits = 8*segments.length
          [:inexact, bits, IPAddr.new((segments+[0,0,0])[0,4].join(".") + "/#{bits}")]
        else
          raise AuthStoreError, _("Invalid IP pattern %{value}") % { value: value }
        end
      end

      def parse(value)
        @name,@exact,@length,@pattern = *case value
        when /^(\w[-\w]*\.)+[-\w]+$/                              # a full hostname
          # Change to /^(\w[-\w]*\.)+[-\w]+\.?$/ for FQDN support
          [:domain,:exact,nil,munge_name(value)]
        when /^\*(\.(\w[-\w]*)){1,}$/                             # *.domain.com
          host_sans_star = munge_name(value)[0..-2]
          [:domain,:inexact,host_sans_star.length,host_sans_star]
        when /\$\d+/                                              # a backreference pattern ala $1.reductivelabs.com or 192.168.0.$1 or $1.$2
          [:dynamic,:exact,nil,munge_name(value)]
        when /^\w[-.@\w]*$/                                       # ? Just like a host name but allow '@'s and ending '.'s
          [:opaque,:exact,nil,[value]]
        when /^\/.*\/$/                                           # a regular expression
          [:regex,:inexact,nil,value]
        else
          raise AuthStoreError, "Invalid pattern #{value}"
        end
      end
    end
  end
end

