Class: OverSIP::SIP::TcpReactor

Inherits:
Reactor
  • Object
show all
Defined in:
lib/oversip/sip/listeners/tcp_reactor.rb

Direct Known Subclasses

TcpClient, TcpServer, TlsTunnelReactor

Constant Summary collapse

HEADERS_MAX_SIZE =

Max size (bytes) of the buffered data when receiving message headers (avoid DoS attacks).

16384

Constants included from MessageProcessor

MessageProcessor::MSG_TYPE

Constants included from Logger

Logger::SYSLOG_POSIXMQ_MAPPING

Instance Method Summary collapse

Methods inherited from Reactor

#initialize, #receive_senderror, reliable_transport_listener?

Methods included from Logger

close, #fatal, fg_system_msg2str, init_logger_mq, load_methods, #log_id, syslog_system_msg2str, syslog_user_msg2str

Constructor Details

This class inherits a constructor from OverSIP::SIP::Reactor

Instance Method Details

#get_body ⇒ Object

parse_headers



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# File 'lib/oversip/sip/listeners/tcp_reactor.rb', line 157

def get_body
  # Return false until the buffer gets all the body.
  return false if @buffer.size < @body_length

  ### TODO: Creo que es mejor forzarlo a BINARY y no a UTF-8. Aunque IOBuffer ya lo saca siempre en BINARY.
  # ¿Por qué lo forcé a UTF-8?
  # RESPUESTA: Si no lo hago y resulta que el body no es UTF-8 válido, al añadir el body a los headers (que
  # se generan como un string en UTF-8 (aunque contengan símbolos no UTF-8) fallaría. O todo UTF-8 (aunque
  # tenga símbolos inválidos) o todo BINARY.
  @msg.body = @buffer.read(@body_length).force_encoding(::Encoding::UTF_8)
  @state = :finished
  return true
end

#parse_headers ⇒ Object 



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# File 'lib/oversip/sip/listeners/tcp_reactor.rb', line 47

def parse_headers
  return false if @buffer.empty?

  # Parse the currently buffered data. If parsing fails @parser_nbytes gets nil value.
  unless @parser_nbytes = @parser.execute(@buffer.to_str, @parser_nbytes)
    # The parsed data is invalid, however some data could be parsed so @parsed.parsed
    # can be:
    # - SIP::Request
    # - SIP::Response
    # - nil (the message is so wrong that cannot be neither a request or response).
    if wrong_message = @parser.parsed
      log_system_warn "parsing error for #{MSG_TYPE[wrong_message.class]}: \"#{@parser.error}\""
    else
      log_system_warn "parsing error: \"#{@parser.error}\""
    end

    close_connection_after_writing
    @state = :ignore
    return false
  end

  # Avoid flood attacks in TCP (very long headers).
  if @parser_nbytes > HEADERS_MAX_SIZE
    log_system_warn "DoS attack detected: headers size exceedes #{HEADERS_MAX_SIZE} bytes, closing connection with #{remote_desc}"
    close_connection
    # After closing client connection some data can still arrrive to "receive_data()"
    # (explained in EM documentation). By setting @state = :ignore we ensure such
    # remaining data is not processed.
    @state = :ignore
    return false
  end

  # If the parsing has not finished, it is correct in TCP so return false and wait for more data under :headers state.
  return false  unless @parser.finished?

  # At this point we've got a SIP::Request, SIP::Response or :outbound_keepalive symbol.
  @msg = @parser.parsed

  # Clear parsed data from the buffer.
  @buffer.read(@parser_nbytes)

  # Received data is a Outbound keealive.
  if @msg == :outbound_keepalive
    log_system_debug "Outbound keepalive received, replying single CRLF"  if $oversip_debug
    # Reply a single CRLF over the same connection.
    send_data CRLF
    # If TCP then go back to :init state so possible remaining data would be processed.
    @state = :init
    return true
  end

  @parser.post_parsing

  # Here we have received the entire headers of a SIP request or response. Fill some
  # attributes.
  @msg.connection = self
  @msg.transport = self.class.transport
  @msg.source_ip = @remote_ip
  @msg.source_port = @remote_port
  @msg.source_ip_type = @remote_ip_type || self.class.ip_type

  unless valid_message?
    close_connection_after_writing
    @state = :ignore
    return false
  end

  add_via_received_rport if @msg.request?

  unless check_via_branch
    close_connection_after_writing
    @state = :ignore
    return false
  end

  # Examine Content-Length header.
  # In SIP over TCP Content-Length header is mandatory.
  if (@body_length = @msg.content_length)
    # There is body (or should be).
    if @body_length > 0
      @state = :body
      # Return true to continue in get_body() method.
      return true
    # No body.
    else
      # Set :finished state and return true to process the parsed message.
      @state = :finished
      return true
    end
  # No Content-Length, invalid message!
  else
    # Log it and reply a 400 Bad Request (if it's a request).
    # Close the connection, set :ignore state and return false to leave
    # receive_data().
    if @msg.request?
      unless @msg.sip_method == :ACK
        log_system_warn "request body size doesn't match Content-Length => 400"
        @msg.reply 400, "Body size doesn't match Content-Length"
      else
        log_system_warn "ACK body size doesn't match Content-Length, ignoring it"
      end
    else
      log_system_warn "response has not Content-Length header, ignoring it"
    end
    close_connection_after_writing
    @state = :ignore
    return false
  end
end

#receive_data(data) ⇒ Object 



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# File 'lib/oversip/sip/listeners/tcp_reactor.rb', line 9

def receive_data data
  @state == :ignore and return
  @buffer << data

  while (case @state
    when :init
      @parser.reset
      @parser_nbytes = 0
      @state = :headers

    when :headers
      parse_headers
      # TODO: Add a timer for the case in which an attacker sends us slow headers that never end:
      #   http://ha.ckers.org/slowloris/.

    when :body
      get_body

    when :finished
      # Invoke the custom logic for requests.
      if @msg.request?
        process_request
      else
        process_response
      end

      # Set state to :init.
      @state = :init
      # Return true to continue processing possible remaining data.
      true

    when :ignore
      false
    end)
  end  # while

end

#send_sip_msg(msg, ip = nil, port = nil) ⇒ Object

Parameters ip and port are just included because they are needed in UDP, so the API remains equal.



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# File 'lib/oversip/sip/listeners/tcp_reactor.rb', line 173

def send_sip_msg msg, ip=nil, port=nil
  if self.error?
    log_system_notice "SIP message could not be sent, connection is closed"
    return false
  end
  send_data msg
  true
end