text: # Copyright 2017 New Vector Ltd
  # Copyright 2019-2021 The Matrix.org Foundation C.I.C
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  import atexit
  import gc
  import logging
  import os
  import signal
  import socket
  import sys
  import traceback
  import warnings
  from typing import (
      TYPE_CHECKING,
      Any,
      Awaitable,
      Callable,
      Collection,
      Dict,
      Iterable,
      List,
      NoReturn,
      Optional,
      Tuple,
      cast,
  )
  
  from cryptography.utils import CryptographyDeprecationWarning
  from matrix_common.versionstring import get_distribution_version_string
  
  import twisted
  from twisted.internet import defer, error, reactor as _reactor
  from twisted.internet.interfaces import IOpenSSLContextFactory, IReactorSSL, IReactorTCP
  from twisted.internet.protocol import ServerFactory
  from twisted.internet.tcp import Port
  from twisted.logger import LoggingFile, LogLevel
  from twisted.protocols.tls import TLSMemoryBIOFactory
  from twisted.python.threadpool import ThreadPool
  
  from synapse.api.constants import MAX_PDU_SIZE
  from synapse.app import check_bind_error
  from synapse.app.phone_stats_home import start_phone_stats_home
  from synapse.config.homeserver import HomeServerConfig
  from synapse.config.server import ManholeConfig
  from synapse.crypto import context_factory
  from synapse.events.presence_router import load_legacy_presence_router
  from synapse.events.spamcheck import load_legacy_spam_checkers
  from synapse.events.third_party_rules import load_legacy_third_party_event_rules
  from synapse.handlers.auth import load_legacy_password_auth_providers
  from synapse.logging.context import PreserveLoggingContext
  from synapse.logging.opentracing import init_tracer
  from synapse.metrics import install_gc_manager, register_threadpool
  from synapse.metrics.background_process_metrics import wrap_as_background_process
  from synapse.metrics.jemalloc import setup_jemalloc_stats
  from synapse.types import ISynapseReactor
  from synapse.util.caches.lrucache import setup_expire_lru_cache_entries
  from synapse.util.daemonize import daemonize_process
  from synapse.util.gai_resolver import GAIResolver
  from synapse.util.rlimit import change_resource_limit
  
  if TYPE_CHECKING:
      from synapse.server import HomeServer
  
  # Twisted injects the global reactor to make it easier to import, this confuses
  # mypy which thinks it is a module. Tell it that it a more proper type.
  reactor = cast(ISynapseReactor, _reactor)
  
  
  logger = logging.getLogger(__name__)
  
  # list of tuples of function, args list, kwargs dict
  _sighup_callbacks: List[
      Tuple[Callable[..., None], Tuple[Any, ...], Dict[str, Any]]
  ] = []
  
  
  def register_sighup(func: Callable[..., None], *args: Any, **kwargs: Any) -> None:
      """
      Register a function to be called when a SIGHUP occurs.
  
      Args:
          func: Function to be called when sent a SIGHUP signal.
          *args, **kwargs: args and kwargs to be passed to the target function.
      """
      _sighup_callbacks.append((func, args, kwargs))
  
  
  def start_worker_reactor(
      appname: str,
      config: HomeServerConfig,
      run_command: Callable[[], None] = reactor.run,
  ) -> None:
      """Run the reactor in the main process
  
      Daemonizes if necessary, and then configures some resources, before starting
      the reactor. Pulls configuration from the 'worker' settings in 'config'.
  
      Args:
          appname: application name which will be sent to syslog
          config: config object
          run_command: callable that actually runs the reactor
      """
  
      logger = logging.getLogger(config.worker.worker_app)
  
      start_reactor(
          appname,
          soft_file_limit=config.server.soft_file_limit,
          gc_thresholds=config.server.gc_thresholds,
          pid_file=config.worker.worker_pid_file,
          daemonize=config.worker.worker_daemonize,
          print_pidfile=config.server.print_pidfile,
          logger=logger,
          run_command=run_command,
      )
  
  
  def start_reactor(
      appname: str,
      soft_file_limit: int,
      gc_thresholds: Optional[Tuple[int, int, int]],
      pid_file: Optional[str],
      daemonize: bool,
      print_pidfile: bool,
      logger: logging.Logger,
      run_command: Callable[[], None] = reactor.run,
  ) -> None:
      """Run the reactor in the main process
  
      Daemonizes if necessary, and then configures some resources, before starting
      the reactor
  
      Args:
          appname: application name which will be sent to syslog
          soft_file_limit:
          gc_thresholds:
          pid_file: name of pid file to write to if daemonize is True
          daemonize: true to run the reactor in a background process
          print_pidfile: whether to print the pid file, if daemonize is True
          logger: logger instance to pass to Daemonize
          run_command: callable that actually runs the reactor
      """
  
      def run() -> None:
          logger.info("Running")
          setup_jemalloc_stats()
          change_resource_limit(soft_file_limit)
          if gc_thresholds:
              gc.set_threshold(*gc_thresholds)
          install_gc_manager()
          run_command()
  
      # make sure that we run the reactor with the sentinel log context,
      # otherwise other PreserveLoggingContext instances will get confused
      # and complain when they see the logcontext arbitrarily swapping
      # between the sentinel and `run` logcontexts.
      #
      # We also need to drop the logcontext before forking if we're daemonizing,
      # otherwise the cputime metrics get confused about the per-thread resource usage
      # appearing to go backwards.
      with PreserveLoggingContext():
          if daemonize:
              assert pid_file is not None
  
              if print_pidfile:
                  print(pid_file)
  
              daemonize_process(pid_file, logger)
          run()
  
  
  def quit_with_error(error_string: str) -> NoReturn:
      message_lines = error_string.split("\n")
      line_length = min(max(len(line) for line in message_lines), 80) + 2
      sys.stderr.write("*" * line_length + "\n")
      for line in message_lines:
          sys.stderr.write(" %s\n" % (line.rstrip(),))
      sys.stderr.write("*" * line_length + "\n")
      sys.exit(1)
  
  
  def handle_startup_exception(e: Exception) -> NoReturn:
      # Exceptions that occur between setting up the logging and forking or starting
      # the reactor are written to the logs, followed by a summary to stderr.
      logger.exception("Exception during startup")
      quit_with_error(
          f"Error during initialisation:\n   {e}\nThere may be more information in the logs."
      )
  
  
  def redirect_stdio_to_logs() -> None:
      streams = [("stdout", LogLevel.info), ("stderr", LogLevel.error)]
  
      for (stream, level) in streams:
          oldStream = getattr(sys, stream)
          loggingFile = LoggingFile(
              logger=twisted.logger.Logger(namespace=stream),
              level=level,
              encoding=getattr(oldStream, "encoding", None),
          )
          setattr(sys, stream, loggingFile)
  
      print("Redirected stdout/stderr to logs")
  
  
  def register_start(cb: Callable[..., Awaitable], *args: Any, **kwargs: Any) -> None:
      """Register a callback with the reactor, to be called once it is running
  
      This can be used to initialise parts of the system which require an asynchronous
      setup.
  
      Any exception raised by the callback will be printed and logged, and the process
      will exit.
      """
  
      async def wrapper() -> None:
          try:
              await cb(*args, **kwargs)
          except Exception:
              # previously, we used Failure().printTraceback() here, in the hope that
              # would give better tracebacks than traceback.print_exc(). However, that
              # doesn't handle chained exceptions (with a __cause__ or __context__) well,
              # and I *think* the need for Failure() is reduced now that we mostly use
              # async/await.
  
              # Write the exception to both the logs *and* the unredirected stderr,
              # because people tend to get confused if it only goes to one or the other.
              #
              # One problem with this is that if people are using a logging config that
              # logs to the console (as is common eg under docker), they will get two
              # copies of the exception. We could maybe try to detect that, but it's
              # probably a cost we can bear.
              logger.fatal("Error during startup", exc_info=True)
              print("Error during startup:", file=sys.__stderr__)
              traceback.print_exc(file=sys.__stderr__)
  
              # it's no use calling sys.exit here, since that just raises a SystemExit
              # exception which is then caught by the reactor, and everything carries
              # on as normal.
              os._exit(1)
  
      reactor.callWhenRunning(lambda: defer.ensureDeferred(wrapper()))
  
  
  def listen_metrics(bind_addresses: Iterable[str], port: int) -> None:
      """
      Start Prometheus metrics server.
      """
      from synapse.metrics import RegistryProxy, start_http_server
  
      for host in bind_addresses:
          logger.info("Starting metrics listener on %s:%d", host, port)
          start_http_server(port, addr=host, registry=RegistryProxy)
  
  
  def listen_manhole(
      bind_addresses: Collection[str],
      port: int,
      manhole_settings: ManholeConfig,
      manhole_globals: dict,
  ) -> None:
      # twisted.conch.manhole 21.1.0 uses "int_from_bytes", which produces a confusing
      # warning. It's fixed by https://github.com/twisted/twisted/pull/1522), so
      # suppress the warning for now.
      warnings.filterwarnings(
          action="ignore",
          category=CryptographyDeprecationWarning,
          message="int_from_bytes is deprecated",
      )
  
      from synapse.util.manhole import manhole
  
      listen_tcp(
          bind_addresses,
          port,
          manhole(settings=manhole_settings, globals=manhole_globals),
      )
  
  
  def listen_tcp(
      bind_addresses: Collection[str],
      port: int,
      factory: ServerFactory,
      reactor: IReactorTCP = reactor,
      backlog: int = 50,
  ) -> List[Port]:
      """
      Create a TCP socket for a port and several addresses
  
      Returns:
          list of twisted.internet.tcp.Port listening for TCP connections
      """
      r = []
      for address in bind_addresses:
          try:
              r.append(reactor.listenTCP(port, factory, backlog, address))
          except error.CannotListenError as e:
              check_bind_error(e, address, bind_addresses)
  
      # IReactorTCP returns an object implementing IListeningPort from listenTCP,
      # but we know it will be a Port instance.
      return r  # type: ignore[return-value]
  
  
  def listen_ssl(
      bind_addresses: Collection[str],
      port: int,
      factory: ServerFactory,
      context_factory: IOpenSSLContextFactory,
      reactor: IReactorSSL = reactor,
      backlog: int = 50,
  ) -> List[Port]:
      """
      Create an TLS-over-TCP socket for a port and several addresses
  
      Returns:
          list of twisted.internet.tcp.Port listening for TLS connections
      """
      r = []
      for address in bind_addresses:
          try:
              r.append(
                  reactor.listenSSL(port, factory, context_factory, backlog, address)
              )
          except error.CannotListenError as e:
              check_bind_error(e, address, bind_addresses)
  
      # IReactorSSL incorrectly declares that an int is returned from listenSSL,
      # it actually returns an object implementing IListeningPort, but we know it
      # will be a Port instance.
      return r  # type: ignore[return-value]
  
  
  def refresh_certificate(hs: "HomeServer") -> None:
      """
      Refresh the TLS certificates that Synapse is using by re-reading them from
      disk and updating the TLS context factories to use them.
      """
      if not hs.config.server.has_tls_listener():
          return
  
      hs.config.tls.read_certificate_from_disk()
      hs.tls_server_context_factory = context_factory.ServerContextFactory(hs.config)
  
      if hs._listening_services:
          logger.info("Updating context factories...")
          for i in hs._listening_services:
              # When you listenSSL, it doesn't make an SSL port but a TCP one with
              # a TLS wrapping factory around the factory you actually want to get
              # requests. This factory attribute is public but missing from
              # Twisted's documentation.
              if isinstance(i.factory, TLSMemoryBIOFactory):
                  addr = i.getHost()
                  logger.info(
                      "Replacing TLS context factory on [%s]:%i", addr.host, addr.port
                  )
                  # We want to replace TLS factories with a new one, with the new
                  # TLS configuration. We do this by reaching in and pulling out
                  # the wrappedFactory, and then re-wrapping it.
                  i.factory = TLSMemoryBIOFactory(
                      hs.tls_server_context_factory, False, i.factory.wrappedFactory
                  )
          logger.info("Context factories updated.")
  
  
  async def start(hs: "HomeServer") -> None:
      """
      Start a Synapse server or worker.
  
      Should be called once the reactor is running.
  
      Will start the main HTTP listeners and do some other startup tasks, and then
      notify systemd.
  
      Args:
          hs: homeserver instance
      """
      reactor = hs.get_reactor()
  
      # We want to use a separate thread pool for the resolver so that large
      # numbers of DNS requests don't starve out other users of the threadpool.
      resolver_threadpool = ThreadPool(name="gai_resolver")
      resolver_threadpool.start()
      reactor.addSystemEventTrigger("during", "shutdown", resolver_threadpool.stop)
      reactor.installNameResolver(
          GAIResolver(reactor, getThreadPool=lambda: resolver_threadpool)
      )
  
      # Register the threadpools with our metrics.
      register_threadpool("default", reactor.getThreadPool())
      register_threadpool("gai_resolver", resolver_threadpool)
  
      # Set up the SIGHUP machinery.
      if hasattr(signal, "SIGHUP"):
  
          @wrap_as_background_process("sighup")
          async def handle_sighup(*args: Any, **kwargs: Any) -> None:
              # Tell systemd our state, if we're using it. This will silently fail if
              # we're not using systemd.
              sdnotify(b"RELOADING=1")
  
              for i, args, kwargs in _sighup_callbacks:
                  i(*args, **kwargs)
  
              sdnotify(b"READY=1")
  
          # We defer running the sighup handlers until next reactor tick. This
          # is so that we're in a sane state, e.g. flushing the logs may fail
          # if the sighup happens in the middle of writing a log entry.
          def run_sighup(*args: Any, **kwargs: Any) -> None:
              # `callFromThread` should be "signal safe" as well as thread
              # safe.
              reactor.callFromThread(handle_sighup, *args, **kwargs)
  
          signal.signal(signal.SIGHUP, run_sighup)
  
          register_sighup(refresh_certificate, hs)
  
      # Load the certificate from disk.
      refresh_certificate(hs)
  
      # Start the tracer
      init_tracer(hs)  # noqa
  
      # Instantiate the modules so they can register their web resources to the module API
      # before we start the listeners.
      module_api = hs.get_module_api()
      for module, config in hs.config.modules.loaded_modules:
          m = module(config=config, api=module_api)
          logger.info("Loaded module %s", m)
  
      load_legacy_spam_checkers(hs)
      load_legacy_third_party_event_rules(hs)
      load_legacy_presence_router(hs)
      load_legacy_password_auth_providers(hs)
  
      # If we've configured an expiry time for caches, start the background job now.
      setup_expire_lru_cache_entries(hs)
  
      # It is now safe to start your Synapse.
      hs.start_listening()
      hs.get_datastores().main.db_pool.start_profiling()
      hs.get_pusherpool().start()
  
      # Log when we start the shut down process.
      hs.get_reactor().addSystemEventTrigger(
          "before", "shutdown", logger.info, "Shutting down..."
      )
  
      setup_sentry(hs)
      setup_sdnotify(hs)
  
      # If background tasks are running on the main process, start collecting the
      # phone home stats.
      if hs.config.worker.run_background_tasks:
          start_phone_stats_home(hs)
  
      # We now freeze all allocated objects in the hopes that (almost)
      # everything currently allocated are things that will be used for the
      # rest of time. Doing so means less work each GC (hopefully).
      #
      # PyPy does not (yet?) implement gc.freeze()
      if hasattr(gc, "freeze"):
          gc.collect()
          gc.freeze()
  
          # Speed up shutdowns by freezing all allocated objects. This moves everything
          # into the permanent generation and excludes them from the final GC.
          atexit.register(gc.freeze)
  
  
  def setup_sentry(hs: "HomeServer") -> None:
      """Enable sentry integration, if enabled in configuration"""
  
      if not hs.config.metrics.sentry_enabled:
          return
  
      import sentry_sdk
  
      sentry_sdk.init(
          dsn=hs.config.metrics.sentry_dsn,
          release=get_distribution_version_string("matrix-synapse"),
      )
  
      # We set some default tags that give some context to this instance
      with sentry_sdk.configure_scope() as scope:
          scope.set_tag("matrix_server_name", hs.config.server.server_name)
  
          app = (
              hs.config.worker.worker_app
              if hs.config.worker.worker_app
              else "synapse.app.homeserver"
          )
          name = hs.get_instance_name()
          scope.set_tag("worker_app", app)
          scope.set_tag("worker_name", name)
  
  
  def setup_sdnotify(hs: "HomeServer") -> None:
      """Adds process state hooks to tell systemd what we are up to."""
  
      # Tell systemd our state, if we're using it. This will silently fail if
      # we're not using systemd.
      sdnotify(b"READY=1\nMAINPID=%i" % (os.getpid(),))
  
      hs.get_reactor().addSystemEventTrigger(
          "before", "shutdown", sdnotify, b"STOPPING=1"
      )
  
  
  sdnotify_sockaddr = os.getenv("NOTIFY_SOCKET")
  
  
  def sdnotify(state: bytes) -> None:
      """
      Send a notification to systemd, if the NOTIFY_SOCKET env var is set.
  
      This function is based on the sdnotify python package, but since it's only a few
      lines of code, it's easier to duplicate it here than to add a dependency on a
      package which many OSes don't include as a matter of principle.
  
      Args:
          state: notification to send
      """
      if not isinstance(state, bytes):
          raise TypeError("sdnotify should be called with a bytes")
      if not sdnotify_sockaddr:
          return
      addr = sdnotify_sockaddr
      if addr[0] == "@":
          addr = "\0" + addr[1:]
  
      try:
          with socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM) as sock:
              sock.connect(addr)
              sock.sendall(state)
      except Exception as e:
          # this is a bit surprising, since we don't expect to have a NOTIFY_SOCKET
          # unless systemd is expecting us to notify it.
          logger.warning("Unable to send notification to systemd: %s", e)
  
  
  def max_request_body_size(config: HomeServerConfig) -> int:
      """Get a suitable maximum size for incoming HTTP requests"""
  
      # Other than media uploads, the biggest request we expect to see is a fully-loaded
      # /federation/v1/send request.
      #
      # The main thing in such a request is up to 50 PDUs, and up to 100 EDUs. PDUs are
      # limited to 65536 bytes (possibly slightly more if the sender didn't use canonical
      # json encoding); there is no specced limit to EDUs (see
      # https://github.com/matrix-org/matrix-doc/issues/3121).
      #
      # in short, we somewhat arbitrarily limit requests to 200 * 64K (about 12.5M)
      #
      max_request_size = 200 * MAX_PDU_SIZE
  
      # if we have a media repo enabled, we may need to allow larger uploads than that
      if config.media.can_load_media_repo:
          max_request_size = max(max_request_size, config.media.max_upload_size)
  
      return max_request_size
  