# acl-1.0 - simple Access Control List
#
# $Date: 2000/12/25 18:24:44 $
# Copyright (c) 2000 Masatoshi SEKI
#
# acl.rb is copyrighted free software by Masatoshi SEKI.
# You can redistribute it and/or modify it under the same term as Ruby.

class ACL
  VERSION=["1.0.1", "$Id: acl.rb,v 1.8 2000/12/25 18:24:44 mas Exp $"]
  class ACLEntry
    def initialize(str)
      if str == '*' or str == 'all'
	@pat = [:all]
      elsif str =~ /^[0-9*]+\.[0-9*]+\.[0-9*]+\.[0-9*]+$/
	@pat = [:ip, dot_pat_ip(str)]
      elsif str =~ /^(([0-9a-f:]+)|(\*)):([0-9*]+\.[0-9*]+\.[0-9*]+\.[0-9*]+)$/
	ipv6hexpart = $1
	ipv4address = $4
	@pat = [:ip, dot_pat_ipv6(ipv6hexpart, ipv4address)]
      else
	@pat = [:name, dot_pat(str)]
      end
    end

    private
    def dot_pat_str(str)
      list = str.split('.').collect { |s|
	(s == '*') ? '.+' : s
      }
      list.join("\\.")
    end

    private
    def dot_pat(str)
      exp = "^" + dot_pat_str(str) + "$"
      Regexp.new(exp)
    end

    private
    def dot_pat_ip(str)
      exp = "^([0-9a-fA-F:]+:)?" + dot_pat_str(str) + "$"
      Regexp.new(exp)
    end

    private
    def dot_pat_ipv6(hexpart, addr)
      hexpart = "[0-9a-fA-F:]+" if hexpart == '*'
      exp = hexpart + ":" + dot_pat_str(addr) + "$"
      Regexp.new(exp)
    end

    public
    def match(addr)
      case @pat[0]
      when :all
	true
      when :ip
	(@pat[1] =~ addr[3]) ? true : false
      when :name
	(@pat[1] =~ addr[2]) ? true : false
      else
	false
      end
    end
  end

  class ACLList
    def initialize
      @list = []
    end

    public
    def match(addr)
      @list.each do |e|
	return true if e.match(addr)
      end
      false
    end

    public
    def add(str)
      @list.push(ACLEntry.new(str))
    end
  end

  DENY_ALLOW = 0
  ALLOW_DENY = 1

  def initialize(list=nil, order = DENY_ALLOW)
    @order = order
    @deny = ACLList.new
    @allow = ACLList.new
    install_list(list) if list
  end

  public
  def allow_socket?(soc)
    allow_addr?(soc.peeraddr)
  end

  public
  def allow_addr?(addr)
    case @order
    when DENY_ALLOW
      return true if @allow.match(addr)
      return false if @deny.match(addr)
      return true
    when ALLOW_DENY
      return false if @deny.match(addr)
      return true if @allow.match(addr)
      return false
    else
      false
    end
  end

  public
  def install_list(list)
    for i in (0..(list.size/2-1))
      case list[i*2].downcase
      when 'allow'
	@allow.add(list[i*2+1])
      when 'deny'
	@deny.add(list[i*2+1])
      else
	raise "Invalid ACL entry #{list.to_s}"
      end
    end
  end
end

if __FILE__ == $0
  # example
  list = %w(deny all
	    allow 192.168.1.1
            allow ::ffff:192.168.1.2
            allow *:192.168.1.3
            )

  addr = ["AF_INET", 10, "lc630", "192.168.1.3"]

  acl = ACL.new
  p acl.allow_addr?(addr)

  acl = ACL.new(list, ACL::DENY_ALLOW)
  p acl.allow_addr?(addr)
end