Source code for dhcpkit.ipv6.server.worker

Worker process for handling requests using multiprocessing.
import logging
import logging.handlers
import os
import re
import signal
import sys
from multiprocessing import Queue, current_process

from dhcpkit.ipv6.messages import Message, RelayForwardMessage, RelayReplyMessage
from dhcpkit.ipv6.options import InterfaceIdOption, Option, RelayMessageOption
from dhcpkit.ipv6.server.listeners import IncomingPacketBundle, Replier
from dhcpkit.ipv6.server.message_handler import MessageHandler
from dhcpkit.ipv6.server.queue_logger import WorkerQueueHandler
from dhcpkit.ipv6.server.statistics import ServerStatistics
from dhcpkit.ipv6.server.transaction_bundle import TransactionBundle
from typing import Iterable

logger = None
""":type: logging.Logger"""

logging_handler = None
""":type: WorkerQueueHandler"""

current_message_handler = None
""":type: MessageHandler"""

shared_statistics = None
""":type: ServerStatistics"""

[docs]def setup_worker(message_handler: MessageHandler, logging_queue: Queue, lowest_log_level: int, statistics: ServerStatistics, master_pid: int): """ This function will be called after a new worker process has been created. Its purpose is to set the global variables in this specific worker process so that they can be reused across multiple requests. Otherwise we would have to pickle them each and every time, and because they are static that would be a waste. :param message_handler: The message handler for the incoming requests :param logging_queue: The queue where we can deposit log messages so the main process can log them :param lowest_log_level: The lowest log level that is going to be handled by the main process :param statistics: Container for shared memory with statistics counters :param master_pid: The PID of the master process, in case we have critical errors while initialising """ try: # Let's shorten the process name a bit by removing everything except the "Worker-x" bit at the end this_process = current_process() = re.sub(r'^.*(Worker-\d+)$', r'\1', # Ignore normal signal handling signal.signal(signal.SIGINT, lambda signum, frame: None) signal.signal(signal.SIGTERM, lambda signum, frame: None) signal.signal(signal.SIGHUP, lambda signum, frame: None) # Save the logger, don't let it filter, send everything to the queue global logger logger = logging.getLogger() logger.setLevel(logging.NOTSET) global logging_handler logging_handler = WorkerQueueHandler(logging_queue) logging_handler.setLevel(lowest_log_level) logger.addHandler(logging_handler) # Save the message handler global current_message_handler current_message_handler = message_handler global shared_statistics shared_statistics = statistics # Run the per-process startup code for the message handler and its children message_handler.worker_init() except Exception as e: if logger: logger.error("Error initialising worker: {}".format(e)) # Signal our predicament os.kill(master_pid, signal.SIGUSR1) # Redirect to stderr to prevent stack traces on console sys.stderr = open(os.devnull, 'w') raise e
[docs]def parse_incoming_request(incoming_packet: IncomingPacketBundle) -> TransactionBundle: """ Parse the incoming packet and add a RelayServerMessage around it containing the meta-data received from the listener. :param incoming_packet: The received packet :return: The parsed message in a transaction bundle """ # Parse message and validate length, incoming_message = Message.parse( incoming_message.validate() # Determine the next hop count and construct useful log messages if isinstance(incoming_message, RelayForwardMessage): next_hop_count = incoming_message.hop_count + 1 else: next_hop_count = 0 # Collect the relay options relay_options = [] """:type: List[Option]""" relay_options.extend(incoming_packet.relay_options) relay_options.append(RelayMessageOption(relayed_message=incoming_message)) # Pretend to be an internal relay and wrap the message like a relay would wrapped_message = RelayForwardMessage(hop_count=next_hop_count, link_address=incoming_packet.link_address, peer_address=incoming_packet.source_address, options=relay_options) # Create the transaction bundle return TransactionBundle(incoming_message=wrapped_message, received_over_multicast=incoming_packet.received_over_multicast, received_over_tcp=incoming_packet.received_over_tcp, marks=incoming_packet.marks)
[docs]def verify_response(outgoing_message: Message): """ generate the outgoing packet and check the RelayServerMessage around it. :param outgoing_message: The reply message """ # Verify that the outer relay message makes sense if not isinstance(outgoing_message, RelayReplyMessage): raise ValueError("The reply has to be wrapped in a RelayReplyMessage") reply = outgoing_message.relayed_message if not reply: raise ValueError("The RelayReplyMessage does not contain a message")
[docs]def get_interface_name_from_options(options: Iterable[Option]): """ Get the interface name from the given options and decode it as unicode :param options: A list of options :return: The interface name """ for option in options: if isinstance(option, InterfaceIdOption): try: # Found: decode return option.interface_id.decode(encoding='utf-8', errors='replace') except UnicodeDecodeError: pass # Fallback return 'unknown'
[docs]def handle_message(incoming_packet: IncomingPacketBundle, replier: Replier): """ Handle a single incoming request. This is supposed to be called in a separate worker thread that has been initialised with setup_worker(). :param incoming_packet: The raw incoming request :param replier: The object that will send replies for us :returns: The packet to reply with and the destination """ # Set the log_id to make it easier to correlate log messages logging_handler.log_id = incoming_packet.message_id # Get the interface name from the incoming packet bundle interface_name = get_interface_name_from_options(incoming_packet.relay_options) # Until we parsed the packet we can only update global and interface statistics statistics = shared_statistics.get_update_set(interface_name=interface_name) try: try: # Parse the packet bundle = parse_incoming_request(incoming_packet) except Exception as e: logger.error("Error while parsing request: {}".format(e)) # Count the packet on the statistics counters that we have statistics.count_incoming_packet() statistics.count_unparsable_packet() return # Now we know more: update all statistics and count the packet on all statistics = shared_statistics.get_update_set(interface_name=interface_name, bundle=bundle) statistics.count_incoming_packet() try: current_message_handler.handle(bundle, statistics) for outgoing_message in bundle.outgoing_messages: verify_response(outgoing_message) statistics.count_outgoing_packet() try: replier.send_reply(outgoing_message) except ValueError as e: logger.error("Handler returned invalid message: {}".format(e)) except Exception as e: logger.exception("Error while handling request: {}".format(e)) statistics.count_handling_error() finally: # Always reset the log_id when leaving logging_handler.log_id = None