Class: Dnsruby::SelectThread

Inherits:
Object
  • Object
show all
Includes:
Singleton
Defined in:
lib/dnsruby/select_thread.rb

Overview

:nodoc: all

Defined Under Namespace

Classes: QuerySettings, SelectWakeup

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SelectThread

This singleton class runs a continuous select loop which

listens for responses on all of the in-use sockets.
When a new query is sent, the thread is woken up, and
the socket is added to the select loop (and the new timeout
calculated).
Note that a combination of the socket and the packet ID is
sufficient to uniquely identify the query to the select thread.

But how do we find the response queue for a particular query?
Hash of client_id->[query, client_queue, socket]
and socket->[client_id]

@todo@ should we implement some of cancel function?



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# File 'lib/dnsruby/select_thread.rb', line 44

def initialize
  @@mutex = Mutex.new
  @@mutex.synchronize {
    @@in_select=false
    #         @@notifier,@@notified=IO.pipe
    @@sockets = Set.new
    @@timeouts = Hash.new
    #     @@mutex.synchronize do
    @@query_hash = Hash.new
    @@socket_hash = Hash.new
    @@socket_is_persistent = Hash.new
    @@observers = Hash.new
    @@tcp_buffers=Hash.new
    @@socket_remaining_queries = Hash.new
    @@tick_observers = []
    @@queued_exceptions=[]
    @@queued_responses=[]
    @@queued_validation_responses=[]
    @@wakeup_sockets = get_socket_pair
    @@sockets << @@wakeup_sockets[1]

    #  Suppress reverse lookups
    BasicSocket.do_not_reverse_lookup = true
    #     end
    #  Now start the select thread
    @@select_thread = Thread.new { do_select }

    #         # Start the validator thread
    #         @@validator = ValidatorThread.instance
  }
end

Instance Method Details

#add_observer(client_queue, observer) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 767

def add_observer(client_queue, observer)
  @@mutex.synchronize {
    @@observers[client_queue]=observer
    check_select_thread_synchronized # Is this really necessary? The client should start the thread by sending a query, really...
    if (!@@tick_observers.include?observer)
      @@tick_observers.push(observer)
    end
  }
end

#add_to_select(query_settings) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 127

def add_to_select(query_settings)
  #  Add the query to sockets, and then wake the select thread up
  @@mutex.synchronize {
    check_select_thread_synchronized
    #  @TODO@ This assumes that all client_query_ids are unique!
    #  Would be a good idea at least to check this...
    @@query_hash[query_settings.client_query_id]=query_settings
    @@socket_hash[query_settings.socket] ||= []
    @@socket_hash[query_settings.socket] << query_settings.client_query_id
    @@socket_remaining_queries[query_settings.socket] ||= query_settings.tcp_pipelining_max_queries if query_settings.tcp_pipelining_max_queries != :infinite
    @@timeouts[query_settings.client_query_id]=query_settings.endtime
    @@sockets << query_settings.socket
    @@socket_is_persistent[query_settings.socket] = query_settings.is_persistent_socket
  }
  wake_up_select_thread
end

#check_select_thread_synchronized ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 152

def check_select_thread_synchronized
  if (!@@select_thread.alive?)
    Dnsruby.log.debug{"Restarting select thread"}
    @@select_thread = Thread.new {
      do_select
    }
  end
end

#clean_up_closed_sockets ⇒ Object

Removes closed sockets from @@sockets, and returns an array containing 1 exception for each closed socket contained in @@socket_hash.



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# File 'lib/dnsruby/select_thread.rb', line 253

def clean_up_closed_sockets
  @@mutex.synchronize do
    closed_sockets_in_hash = @@sockets.select(&:closed?).select { |s| @@socket_hash[s] }
    @@sockets.delete_if { | socket | socket.closed? }
    closed_sockets_in_hash.each_with_object([]) do |socket, exceptions|
      @@socket_hash[socket].each do | client_id |
        exceptions << [SocketEofResolvError.new("TCP socket closed before all answers received"), socket, client_id]
      end
    end
  end
  exceptions
end

#decrement_remaining_queries(socket) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 393

def decrement_remaining_queries(socket)
  if @@socket_remaining_queries[socket]
    @@socket_remaining_queries[socket] -= 1
  end
end

#do_select ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 169

def do_select
  unused_loop_count = 0
  last_tick_time = Time.now - 10
  while true do
    if (last_tick_time < (Time.now - 0.5))
      send_tick_to_observers # ONLY NEED TO SEND THIS TWICE A SECOND - NOT EVERY SELECT!!!
      last_tick_time = Time.now
    end
    send_queued_exceptions
    send_queued_responses
    send_queued_validation_responses
    timeout = tick_time = 0.1 # We provide a timer service to various Dnsruby classes
    sockets, timeouts, has_observer = @@mutex.synchronize { [@@sockets.to_a, @@timeouts.values, !@@observers.empty?] }
    if (timeouts.length > 0)
      timeouts.sort!
      timeout = timeouts[0] - Time.now
      if (timeout <= 0)
        process_timeouts
        timeout = 0
        next
      end
    end
    ready=nil
    if (has_observer && (timeout > tick_time))
      timeout = tick_time
    end
    #         next if (timeout < 0)
    begin
      ready, _write, _errors = IO.select(sockets, nil, nil, timeout)
    rescue SelectWakeup
      #  If SelectWakeup, then just restart this loop - the select call will be made with the new data
      next
    rescue IOError, EncodeError
      exceptions = clean_up_closed_sockets
      exceptions.each { |exception| send_exception_to_client(*exception) }

      next
    end
    if ready && ready.include?(@@wakeup_sockets[1])
      ready.delete(@@wakeup_sockets[1])
      wakeup_msg = "loop"
      begin
        while wakeup_msg && wakeup_msg.length > 0
          wakeup_msg = @@wakeup_sockets[1].recv_nonblock(20)
        end
      rescue
        #  do nothing
      end
    end
    if (ready == nil)
      #  process the timeouts
      process_timeouts
      unused_loop_count+=1
    else
      process_ready(ready)
      unused_loop_count=0
      # process_error(errors)
    end
    @@mutex.synchronize do
      if (unused_loop_count > 10 && @@query_hash.empty? && @@observers.empty?)
        Dnsruby.log.debug("Try stop select loop")

        non_persistent_sockets = @@sockets.select { |s| ! @@socket_is_persistent[s] }
        non_persistent_sockets.each do |socket|
          socket.close rescue nil
          @@sockets.delete(socket)
        end

        Dnsruby.log.debug("Deleted #{non_persistent_sockets.size} non-persistent sockets," +
                          " #{@@sockets.count} persistent sockets remain.")
        @@socket_hash.clear

        if @@sockets.empty?
          Dnsruby.log.debug("Stopping select loop")
          return
        end
      end
    end
    #               }
  end
end

#get_active_ids(queries, id) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 271

def get_active_ids(queries, id)
  queries.keys.select { |client_query_id| client_query_id[1].header.id == id }
end

#get_client_id_from_answerfrom(socket, answerip, answerport) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 606

def get_client_id_from_answerfrom(socket, answerip, answerport)
  #  @TODO@ Can get rid of this, as there is only one query per socket
  client_id=nil
  #  Figure out client id from answerfrom
  @@mutex.synchronize{
    ids = @@socket_hash[socket]
    ids.each do |id|
      #  Does this id speak to this dest_server?
      query_settings = @@query_hash[id]
      if (answerip == query_settings.dest_server && answerport == query_settings.dest_port)
        #  We have a match
        client_id = id
        break
      end
    end
  }
  return client_id
end

#get_incoming_data(socket, packet_size) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 480

def get_incoming_data(socket, packet_size)
  answerfrom,answerip,answerport,answersize=nil
  ans,buf = nil
  is_tcp = tcp?(socket)

  begin
    if is_tcp
      #  Call TCP read here - that will take care of reading the 2 byte length,
      #  and then the full packet - without blocking select.
      buf = tcp_read(socket)
      if (!buf) # Wait for the buffer to comletely fill
        #             handle_recvfrom_failure(socket, "")
        return
      end
    else
      #  @TODO@ Can we get recvfrom to stop issuing PTR queries when we already
      #  know both the FQDN and the IP address?
      if (ret = socket.recvfrom(packet_size))
        buf = ret[0]
        answerport=ret[1][1]
        answerfrom=ret[1][2]
        answerip=ret[1][3]
        answersize=(buf.length)
      else
        #  recvfrom failed - why?
        Dnsruby.log.error{"Error - recvfrom failed from #{socket}"}
        handle_recvfrom_failure(socket, "")
        return
      end
    end
  rescue Exception => e
    Dnsruby.log.error{"Error - recvfrom failed from #{socket}, exception : #{e}"}
    handle_recvfrom_failure(socket, e)
    return
  end
  Dnsruby.log.debug{";; answer from #{answerfrom} : #{answersize} bytes\n"}

  begin
    ans = Message.decode(buf)

    if is_tcp
      @@mutex.synchronize do
        ids = get_active_ids(@@query_hash, ans.header.id)
        if ids.empty?
          Dnsruby.log.error("Decode error from #{answerip} but can't determine packet id")
          #todo add error event? The problem is we don't have a valid id so we don't
          #know which client queue to send the exception to
        end
        answerfrom = @@query_hash[ids[0]].dest_server
        answerip = answerfrom
        answerport = @@query_hash[ids[0]].dest_port
      end
    end

  rescue Exception => e
    Dnsruby.log.error("Decode error! #{e.class}, #{e}\nfor msg (length=#{buf.length}) : #{buf}")
    client_id=get_client_id_from_answerfrom(socket, answerip, answerport)
    if (client_id == nil)
      Dnsruby.log.error{"Decode error from #{answerip} but can't determine packet id"}
    end
    #  We should check if the TC bit is set (if we can get that far)
    if ((DecodeError === e) && (e.partial_message.header.tc))
      Dnsruby.log.error{"Decode error (from {answerip})! Header shows truncation, so trying again over TCP"}
      #  If it is, then we should retry over TCP
      sent = false
      @@mutex.synchronize{
        client_ids = @@socket_hash[socket]
        #  get the queries associated with them
        client_ids.each do |id|
          query_header_id=nil
          query_header_id = @@query_hash[id].query.header.id
          if (query_header_id == e.partial_message.header.id)
            #  process the response
            client_queue = nil
            res = nil
            query=nil
            client_queue = @@query_hash[id].client_queue
            res = @@query_hash[id].single_resolver
            query = @@query_hash[id].query

            #  NOW RESEND OVER TCP!
            Thread.new {
              res.send_async(query, client_queue, id, true)
            }
            sent = true
          end
        end
      }
      if !sent
        send_exception_to_client(e, socket, client_id)
      end

    else
      send_exception_to_client(e, socket, client_id)
    end
    return
  end

  if (ans!= nil)
    Dnsruby.log.debug{"#{ans}"}
    ans.answerfrom=(answerfrom)
    ans.answersize=(answersize)
    ans.answerip =(answerip)
  end
  return ans, buf
end

#get_socket_pair ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 76

def get_socket_pair
  #  Emulate socketpair on platforms which don't support it
  srv = nil
  begin
    srv = TCPServer.new('localhost', 0)
  rescue Errno::EADDRNOTAVAIL, SocketError # OSX Snow Leopard issue - need to use explicit IP
    begin
      srv = TCPServer.new('127.0.0.1', 0)
    rescue Error # Try IPv6
      srv = TCPServer.new('::1', 0)
    end
  end
  rsock = TCPSocket.new(srv.addr[3], srv.addr[1])
  lsock = srv.accept
  srv.close
  return [lsock, rsock]
end

#handle_recvfrom_failure(socket, exception) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 587

def handle_recvfrom_failure(socket, exception)
  #   No way to notify the client about this error, unless there was only one connection on the socket
  #  Not a problem, as there only will ever be one connection on the socket (Kaminsky attack mitigation)
  ids_for_socket = []
  @@mutex.synchronize{
    ids_for_socket = @@socket_hash[socket]
  }
  if (ids_for_socket.length == 1)
    answerfrom=nil
    @@mutex.synchronize{
      query_settings = @@query_hash[ids_for_socket[0]]
      answerfrom=query_settings.dest_server
    }
    send_exception_to_client(OtherResolvError.new("recvfrom failed from #{answerfrom}; #{exception}"), socket, ids_for_socket[0])
  else
    Dnsruby.log.fatal{"Recvfrom failed from #{socket}, no way to tell query id"}
  end
end

#max_attained?(socket) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dnsruby/select_thread.rb', line 399

def max_attained?(socket)
  remaining = @@socket_remaining_queries[socket]
  attained = persistent?(socket) && remaining && remaining <= 0
  Dnsruby.log.debug("Max queries per conn attained") if attained
  attained
end

#notify_queue_observers(client_queue, client_query_id) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 794

def notify_queue_observers(client_queue, client_query_id)
  #  If any observers are known for this query queue then notify them
  observer=nil
  @@mutex.synchronize {
    observer = @@observers[client_queue]
  }
  if (observer)
    observer.handle_queue_event(client_queue, client_query_id)
  end
end

#persistent?(socket) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dnsruby/select_thread.rb', line 370

def persistent?(socket)
  @@socket_is_persistent[socket]
end

#process_error(errors) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 266

def process_error(errors)
  Dnsruby.log.debug{"Error! #{errors.inspect}"}
  #  @todo@ Process errors [can we do this in single socket environment?]
end

#process_message(msg, bytes, socket) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 298

def process_message(msg, bytes, socket)
  @@mutex.synchronize do
    ids = get_active_ids(@@query_hash, msg.header.id)
    return if ids.empty? # should be only one
  end

  answerip = msg.answerip.downcase
  answerfrom = msg.answerfrom.downcase
  answeripaddr = IPAddr.new(answerip)
  dest_server = IPAddr.new("0.0.0.0")

  begin
    destserveripaddr = IPAddr.new(dest_server)
  rescue ArgumentError
    #  Host name not IP address
  end

  if (dest_server && (dest_server != '0.0.0.0') &&
      (answeripaddr != destserveripaddr) &&
      (answerfrom != dest_server))
    Dnsruby.log.warn("Unsolicited response received from #{answerip} instead of #{query_settings.dest_server}")
  else
    send_response_to_client(msg, bytes, socket)
  end
end

#process_ready(ready) ⇒ Object

@@query_hash=query_settings



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# File 'lib/dnsruby/select_thread.rb', line 276

def process_ready(ready)
  persistent_sockets, nonpersistent_sockets = @@mutex.synchronize { ready.partition { |socket| persistent?(socket) } }

  nonpersistent_sockets.each do |socket|
    query_settings =  @@mutex.synchronize { @@query_hash[@@socket_hash[socket][0]] }
    next if !query_settings

    udp_packet_size = query_settings.udp_packet_size
    msg, bytes = get_incoming_data(socket, udp_packet_size)

    process_message(msg, bytes, socket) if msg

    ready.delete(socket)
  end

  persistent_sockets.each do |socket|
    msg, bytes = get_incoming_data(socket, 0)
    process_message(msg, bytes, socket) if msg
    ready.delete(socket)
  end
end

#process_timeouts ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 406

def process_timeouts
  # NOTE: It's @@timeouts we need to protect; after the clone we're ok
  timeouts = @@mutex.synchronize { @@timeouts.clone }
  time_now = Time.now
  timeouts.each do |client_id, timeout|
    if timeout < time_now
      send_exception_to_client(ResolvTimeout.new("Query timed out"), nil, client_id)
    end
  end
end

#push_exception_to_select(client_id, client_queue, err, msg) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 637

def push_exception_to_select(client_id, client_queue, err, msg)
  @@mutex.synchronize{
    @@queued_exceptions.push([client_id, client_queue, err, msg])
  }
  #  Make sure select loop is running!
  if (@@select_thread && @@select_thread.alive?)
  else
    @@select_thread = Thread.new {
      do_select
    }
  end
  wake_up_select_thread
end

#push_response_to_select(client_id, client_queue, msg, query, res) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 651

def push_response_to_select(client_id, client_queue, msg, query, res)
  #  This needs to queue the response TO THE SELECT THREAD, which then needs
  #  to send it out from its normal loop.
  Dnsruby.log.debug{"Pushing response to client queue direct from resolver or validator"}
  @@mutex.synchronize{
    err = nil
    if (msg.rcode == RCode.NXDOMAIN)
      err = NXDomain.new
    end
    @@queued_responses.push([client_id, client_queue, msg, err, query, res])
  }
  #  Make sure select loop is running!
  if (@@select_thread && @@select_thread.alive?)
  else
    @@select_thread = Thread.new {
      do_select
    }
  end
  wake_up_select_thread
end

#push_to_client(client_id, client_queue, msg, err, query, res) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 748

def push_to_client(client_id, client_queue, msg, err, query, res)
  #  @TODO@ Really need to let the client know that we have received a valid response!
  #  Can do that by calling notify_observers here, but with an identifier which
  #  defines the response to be a "Response received - validating. Please stop sending"
  #  type of response.
  client_queue.push([client_id, Resolver::EventType::RECEIVED, msg, err])
  notify_queue_observers(client_queue, client_id)

  if (!err || (err.instance_of?(NXDomain)))
    # 
    #  This method now needs to push the response to the validator,
    #  which will then take responsibility for delivering it to the client.
    #  The validator will need access to the queue observers -
    validator = ValidatorThread.new(client_id, client_queue, msg, err, query ,self, res)
    validator.run
    #       @@validator.add_to_queue([client_id, client_queue, msg, err, query, self, res])
  end
end

#push_validation_response_to_select(client_id, client_queue, msg, err, query, res) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 672

def push_validation_response_to_select(client_id, client_queue, msg, err, query, res)
  #  This needs to queue the response TO THE SELECT THREAD, which then needs
  #  to send it out from its normal loop.
  Dnsruby.log.debug{"Pushing response to client queue direct from resolver or validator"}
  @@mutex.synchronize{
    @@queued_validation_responses.push([client_id, client_queue, msg, err, query, res])
  }
  #  Make sure select loop is running!
  if (@@select_thread && @@select_thread.alive?)
  else
    @@select_thread = Thread.new {
      do_select
    }
  end
  wake_up_select_thread
end

#remove_id(id) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 374

def remove_id(id)

  @@mutex.synchronize do
    socket = @@query_hash[id].socket
    @@timeouts.delete(id)
    @@query_hash.delete(id)
    @@socket_hash[socket].delete(id)

    decrement_remaining_queries(socket) if persistent?(socket)

    if !persistent?(socket) || max_attained?(socket)
      @@sockets.delete(socket)
      @@socket_hash.delete(socket)
      Dnsruby.log.debug("Closing socket #{socket}")
      socket.close rescue nil
    end
  end
end

#remove_observer(client_queue, observer) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 777

def remove_observer(client_queue, observer)
  @@mutex.synchronize {
    if (@@observers[client_queue]==observer)
      #           @@observers.delete(observer)
      @@observers.delete(client_queue)
    else
      if (@@observers[client_queue] == nil)
      end
      Dnsruby.log.error{"remove_observer called with wrong observer for queue"}
      raise ArgumentError.new("remove_observer called with wrong observer for queue")
    end
    if (!@@observers.values.include?observer)
      @@tick_observers.delete(observer)
    end
  }
end

#select_thread_alive? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dnsruby/select_thread.rb', line 161

def select_thread_alive?
  ret=true
  @@mutex.synchronize{
    ret = @@select_thread.alive?
  }
  return ret
end

#send_exception_to_client(err, socket, client_id, msg = nil) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 625

def send_exception_to_client(err, socket, client_id, msg=nil)
  #  find the client response queue
  client_queue = nil
  @@mutex.synchronize {
    client_queue = @@query_hash[client_id].client_queue
  }
  remove_id(client_id)
  #       push_to_client(client_id, client_queue, msg, err)
  client_queue.push([client_id, Resolver::EventType::ERROR, msg, err])
  notify_queue_observers(client_queue, client_id)
end

#send_queued_exceptions ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 689

def send_queued_exceptions
  exceptions = []
  @@mutex.synchronize{
    exceptions = @@queued_exceptions
    @@queued_exceptions = []
  }

  exceptions.each do |item|
    client_id, client_queue, err, msg = item
    #         push_to_client(client_id, client_queue, msg, err)
    client_queue.push([client_id, Resolver::EventType::ERROR, msg, err])
    notify_queue_observers(client_queue, client_id)
  end
end

#send_queued_responses ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 704

def send_queued_responses
  responses = []
  @@mutex.synchronize{
    responses = @@queued_responses
    @@queued_responses = []
  }

  responses.each do |item|
    client_id, client_queue, msg, err, query, res = item
    #         push_to_client(client_id, client_queue, msg, err)
    client_queue.push([client_id, Resolver::EventType::RECEIVED, msg, err])
    notify_queue_observers(client_queue, client_id)
    #  Do we need to validate this? The response has come from the cache -
    #  validate it only if it has not been validated already
    #  So, if we need to validate it, send it to the validation thread
    #  Otherwise, send VALIDATED to the requester.
    if (((msg.security_level == Message::SecurityLevel.UNCHECKED) ||
            (msg.security_level == Message::SecurityLevel.INDETERMINATE)) &&
          (ValidatorThread.requires_validation?(query, msg, err, res)))
      validator = ValidatorThread.new(client_id, client_queue, msg, err, query ,self, res)
      validator.run
    else
      PacketSender.cache(query, msg) # The validator won't cache it, so we'd better do it now
      client_queue.push([client_id, Resolver::EventType::VALIDATED, msg, err])
      notify_queue_observers(client_queue, client_id)
    end
  end
end

#send_queued_validation_responses ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 733

def send_queued_validation_responses
  responses = []
  @@mutex.synchronize{
    responses = @@queued_validation_responses
    @@queued_validation_responses = []
  }

  responses.each do |item|
    client_id, client_queue, msg, err, _query, _res = item
    #         push_to_client(client_id, client_queue, msg, err)
    client_queue.push([client_id, Resolver::EventType::VALIDATED, msg, err])
    notify_queue_observers(client_queue, client_id)
  end
end

#send_response_to_client(msg, bytes, socket) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 324

def send_response_to_client(msg, bytes, socket)
  #  Figure out which client_ids we were expecting on this socket, then see if any header ids match up
  #  @TODO@ Can get rid of this, as we only have one query per socket.
  client_ids=[]
  @@mutex.synchronize{
    client_ids = @@socket_hash[socket].clone
  }
  #  get the queries associated with them
  client_ids.each do |id|
    query_header_id=nil
    @@mutex.synchronize{
      query_header_id = @@query_hash[id].query.header.id
    }
    if (query_header_id == msg.header.id)
      #  process the response
      client_queue = nil
      res = nil
      query=nil
      @@mutex.synchronize{
        client_queue = @@query_hash[id].client_queue
        res = @@query_hash[id].single_resolver
        query = @@query_hash[id].query
      }
      tcp = tcp?(socket)
      #  At this point, we should check if the response is OK
      if (ret = res.check_response(msg, bytes, query, client_queue, id, tcp))
        remove_id(id)
        exception = msg.get_exception
        if (ret.kind_of?TsigError)
          exception = ret
        end
        Dnsruby.log.debug{"Pushing response to client queue"}
        push_to_client(id, client_queue, msg, exception, query, res)
        #             client_queue.push([id, msg, exception])
        #             notify_queue_observers(client_queue, id)
      else
        #  Sending query again - don't return response
      end
      return
    end
  end
  #  If not, then we have an error
  Dnsruby.log.error{"Stray packet - " + msg.inspect + "\n from " + socket.inspect}
  print("Stray packet - " + msg.question()[0].qname.to_s + " from " + msg.answerip.to_s + ", #{client_ids.length} client_ids\n")
end

#send_tick_to_observers ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 805

def send_tick_to_observers
  #  If any observers are known then send them a tick
  tick_observers=nil
  @@mutex.synchronize {
    tick_observers = @@tick_observers
  }
  tick_observers.each do |observer|
    observer.tick
  end
end

#tcp?(socket) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dnsruby/select_thread.rb', line 117

def tcp?(socket)
  type = socket.getsockopt(Socket::SOL_SOCKET, Socket::SO_TYPE)
  [Socket::SOCK_STREAM].pack("i") == type.data
end

#tcp_read(socket) ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 417

def tcp_read(socket)
  #  Keep buffer for all TCP sockets, and return
  #  to select after reading available data. Once all data has been received,
  #  then process message.
  buf = +""
  expected_length = 0
  @@mutex.synchronize {
    buf, expected_length = @@tcp_buffers[socket]
    if (!buf)
      buf = +""
      expected_length = 2
      @@tcp_buffers[socket]=[buf, expected_length]
    end
  }
  if (buf.length() < expected_length)
    begin
      input, = socket.recv_nonblock(expected_length-buf.length)
      if (input=="")
        Dnsruby.log.debug("EOF from server - no bytes read - closing socket")
        socket.close #EOF closed by server, if we were interrupted we need to resend

        exceptions = @@mutex.synchronize do
          @@sockets.delete(socket) #remove ourselves from select, app will have to retry
          #maybe fire an event
          @@socket_hash[socket].map do | client_id |
            [SocketEofResolvError.new("TCP socket closed before all answers received"), socket, client_id]
          end
        end

        exceptions.each { |exception| send_exception_to_client(*exception) }

        return false
      end
      buf << input if input
    rescue
      #  Oh well - better luck next time!
      return false
    end
  end
  #  If data is complete, then return it.
  if (buf.length == expected_length)
    if (expected_length == 2)
      #  We just read the data_length field. Now we need to start reading that many bytes.
      @@mutex.synchronize {
        answersize = buf.unpack('n')[0]
        @@tcp_buffers[socket] = [+"", answersize]
      }
      return tcp_read(socket)
    else
      #  We just read the data - now return it
      @@mutex.synchronize {
        @@tcp_buffers.delete(socket)
      }
      return buf
    end
  else
    @@mutex.synchronize {
      @@tcp_buffers[socket]=[buf, expected_length]
    }
    return false
  end
end

#udp?(socket) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dnsruby/select_thread.rb', line 122

def udp?(socket)
  type = socket.getsockopt(Socket::SOL_SOCKET, Socket::SO_TYPE)
  [Socket::SOCK_DGRAM].pack("i") == type.data
end

#wake_up_select_thread ⇒ Object 



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# File 'lib/dnsruby/select_thread.rb', line 144

def wake_up_select_thread
  begin
    @@wakeup_sockets[0].send("wakeup!", 0)
  rescue Exception
    #          do nothing
  end
end