Class: DNSTraverse::Fingerprint

Inherits:
Object
  • Object
show all
Includes:
FingerprintRules
Defined in:
lib/dnstraverse/fingerprint.rb

Constant Summary collapse

FINGERPRINT_TIMEOUT = 
'query timed out'.freeze

Constants included from FingerprintRules

FingerprintRules::INITRULE, FingerprintRules::IQ, FingerprintRules::QY, FingerprintRules::RULESET

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(args = {}) ⇒ Fingerprint

Returns a new instance of Fingerprint.



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# File 'lib/dnstraverse/fingerprint.rb', line 29

def initialize(args = {})
  @version_style = args[:version_style] || :append
  cfg = Dnsruby::Config.new
  rescfg = { :nameserver => cfg.nameserver, :ndots => cfg.ndots,
    :apply_domain => false, :apply_search_list => false}
  resargs = { :config_info => rescfg, :use_tcp => false, :recurse => false,
    :packet_timeout => 2, :retry_times => 1, :retry_delay => 1,
    :dnssec => false, :ignore_truncation => true, :src_address => '0.0.0.0',
    :udp_size => 512 }
  @resolver = Dnsruby::Resolver.new(resargs)
  @resolver.udp_size = 512
  #Dnsruby.log.level = Logger::DEBUG
  #Log.level = Logger::DEBUG
end

Instance Attribute Details

#version_style ⇒ Object

:none, :override, :append



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# File 'lib/dnstraverse/fingerprint.rb', line 27

def version_style
  @version_style
end

Instance Method Details

#decode_query(querystr) ⇒ Object 



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# File 'lib/dnstraverse/fingerprint.rb', line 145

def decode_query(querystr)
  qname, qclass, qtype = querystr.split(/\s+/)
  if qtype == "CLASS0" then # crappy data
    qtype = qclass
    qclass = "CLASS0"
  end
  q = Dnsruby::Question.new(qname, qtype, qclass)
  return q
end

#fingerprint(ip) ⇒ Object 



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# File 'lib/dnstraverse/fingerprint.rb', line 44

def fingerprint(ip)
  return process(ip, INITRULE[:header], INITRULE[:query], RULESET)
end

#fp2header(headerstr) ⇒ Object 



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# File 'lib/dnstraverse/fingerprint.rb', line 124

def fp2header(headerstr)
  list = headerstr.split(/,/)
  h = Dnsruby::Header.new
  h.qr = list.shift == '1' ? true : false
  opcode = list.shift
  opcode = "Notify" if opcode == "NS_NOTIFY_OP"
  h.opcode = opcode
  h.aa = list.shift == '1' ? true : false
  h.tc = list.shift == '1' ? true : false
  h.rd = list.shift == '1' ? true : false
  h.ra = list.shift == '1' ? true : false
  h.ad = list.shift == '1' ? true : false
  h.cd = list.shift == '1' ? true : false
  h.rcode = list.shift
  h.qdcount = list.shift.to_i
  h.ancount = list.shift.to_i
  h.nscount = list.shift.to_i
  h.arcount = list.shift.to_i
  return h
end

#header2fp(header) ⇒ Object 



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# File 'lib/dnstraverse/fingerprint.rb', line 111

def header2fp(header)
  list = [ header.qr, header.opcode, header.aa, header.tc, header.rd,
  header.ra, header.ad, header.cd, header.get_header_rcode, header.qdcount,
  header.ancount, header.nscount, header.arcount ]
  list.map! do | item |
    next '0' if item.instance_of? FalseClass
    next '1' if item.instance_of? TrueClass
    next "NS_NOTIFY_OP" if item == "Notify"
    item
  end
  return list.join(',').upcase
end

#probe(ip, headerstr, query) ⇒ Object 



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# File 'lib/dnstraverse/fingerprint.rb', line 155

def probe(ip, headerstr, query)
  @resolver.nameserver = ip
  @resolver.dnssec = false
  msg = Dnsruby::Message.new
  msg.header = fp2header(headerstr)
  msg.add_question(decode_query(query))
  result, error = @resolver.send_plain_message(msg)
  ans = result || error
  return nil, FINGERPRINT_TIMEOUT if ans.is_a? Dnsruby::ResolvTimeout
  return nil, ans.to_s if ans.is_a? Exception
  return ans, nil
end

#process(ip, header, query, ruleset) ⇒ Object 



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# File 'lib/dnstraverse/fingerprint.rb', line 48

def process(ip, header, query, ruleset)
  ret = Hash.new
  answer, errstr = probe(ip, header, query)
  id = answer ? header2fp(answer.header) : errstr
  Log.debug { "query = #{query}, id = #{id}" }
  for rule in ruleset do
    raise "Missing fingerprint" unless rule.has_key?(:fingerprint)
    next unless id =~ /#{rule[:fingerprint]}/
    if rule.has_key?(:result) then
      result = rule[:result]
      if result.is_a? String
        ret[:state] = result
        ret[:error] = result
        ret[:id] = id
        return ret
      end
      for k in [:vendor, :product, :option] do
        ret[k] = result[k] if result.has_key?(k) and result[k].length > 0
      end
      case @version_style
      when :none
        ret[:version] = result[:version]
      when :append
        ver = query_version(ip, result[:qv])
        ver = query_version(ip, "version.bind") unless ver
        ret[:version] = result[:version]
        ret[:version]+= " (#{ver})" if ver
      when :override
        ver = query_version(ip, result[:qv])
        ver = query_version(ip, "version.bind") unless ver
        ret[:version] = ver ? ver : result[:version]
      end
      return ret
    end
    if rule.has_key?(:state) then
      ret[:state] = rule[:state]
      ret[:error] = "No match found"
      ret[:id] = id
      return ret
    end
    query = rule[:query] if rule.has_key?(:query)
    if rule.has_key?(:header) and rule.has_key?(:ruleset) then
      return process(ip, rule[:header], query, rule[:ruleset])
    end
    raise "Invalid ruleset -- no next step"
  end
  raise "Invalid ruleset -- fell off end"
end

#query_version(ip, name) ⇒ Object 



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# File 'lib/dnstraverse/fingerprint.rb', line 97

def query_version(ip, name)
  @resolver.nameserver = ip
  @resolver.dnssec = false
  begin
    msg = @resolver.query(name, 'TXT', 'CH')
    if msg.answer.size > 0 then
      ver = msg.answer[0].data.sub(/[^0-9a-zA-Z. :!?-]/, '')
      return ver.length > 0 ? ver : nil
    end
  rescue Exception
    return nil
  end
end