text: # Copyright (c) 2010-2012 OpenStack Foundation
  #
  # 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.
  
  """WSGI tools for use with swift."""
  
  import errno
  import inspect
  import os
  import signal
  import time
  import mimetools
  from swift import gettext_ as _
  from StringIO import StringIO
  
  import eventlet
  import eventlet.debug
  from eventlet import greenio, GreenPool, sleep, wsgi, listen
  from paste.deploy import loadwsgi
  from eventlet.green import socket, ssl
  from urllib import unquote
  
  from swift.common import utils
  from swift.common.swob import Request
  from swift.common.utils import capture_stdio, disable_fallocate, \
      drop_privileges, get_logger, NullLogger, config_true_value, \
      validate_configuration, get_hub, config_auto_int_value, \
      CloseableChain
  
  try:
      import multiprocessing
      CPU_COUNT = multiprocessing.cpu_count() or 1
  except (ImportError, NotImplementedError):
      CPU_COUNT = 1
  
  
  class NamedConfigLoader(loadwsgi.ConfigLoader):
      """
      Patch paste.deploy's ConfigLoader so each context object will know what
      config section it came from.
      """
  
      def get_context(self, object_type, name=None, global_conf=None):
          context = super(NamedConfigLoader, self).get_context(
              object_type, name=name, global_conf=global_conf)
          context.name = name
          return context
  
  
  loadwsgi.ConfigLoader = NamedConfigLoader
  
  
  class ConfigDirLoader(NamedConfigLoader):
      """
      Read configuration from multiple files under the given path.
      """
  
      def __init__(self, conf_dir):
          # parent class uses filename attribute when building error messages
          self.filename = conf_dir = conf_dir.strip()
          defaults = {
              'here': os.path.normpath(os.path.abspath(conf_dir)),
              '__file__': os.path.abspath(conf_dir)
          }
          self.parser = loadwsgi.NicerConfigParser(conf_dir, defaults=defaults)
          self.parser.optionxform = str  # Don't lower-case keys
          utils.read_conf_dir(self.parser, conf_dir)
  
  
  def _loadconfigdir(object_type, uri, path, name, relative_to, global_conf):
      if relative_to:
          path = os.path.normpath(os.path.join(relative_to, path))
      loader = ConfigDirLoader(path)
      if global_conf:
          loader.update_defaults(global_conf, overwrite=False)
      return loader.get_context(object_type, name, global_conf)
  
  
  # add config_dir parsing to paste.deploy
  loadwsgi._loaders['config_dir'] = _loadconfigdir
  
  
  def wrap_conf_type(f):
      """
      Wrap a function whos first argument is a paste.deploy style config uri,
      such that you can pass it an un-adorned raw filesystem path and the config
      directive (either config: or config_dir:) will be added automatically
      based on the type of filesystem entity at the given path (either a file or
      directory) before passing it through to the paste.deploy function.
      """
      def wrapper(conf_path, *args, **kwargs):
          if os.path.isdir(conf_path):
              conf_type = 'config_dir'
          else:
              conf_type = 'config'
          conf_uri = '%s:%s' % (conf_type, conf_path)
          return f(conf_uri, *args, **kwargs)
      return wrapper
  
  
  appconfig = wrap_conf_type(loadwsgi.appconfig)
  
  
  def monkey_patch_mimetools():
      """
      mimetools.Message defaults content-type to "text/plain"
      This changes it to default to None, so we can detect missing headers.
      """
  
      orig_parsetype = mimetools.Message.parsetype
  
      def parsetype(self):
          if not self.typeheader:
              self.type = None
              self.maintype = None
              self.subtype = None
              self.plisttext = ''
          else:
              orig_parsetype(self)
  
      mimetools.Message.parsetype = parsetype
  
  
  def get_socket(conf, default_port=8080):
      """Bind socket to bind ip:port in conf
  
      :param conf: Configuration dict to read settings from
      :param default_port: port to use if not specified in conf
  
      :returns : a socket object as returned from socket.listen or
                 ssl.wrap_socket if conf specifies cert_file
      """
      bind_addr = (conf.get('bind_ip', '0.0.0.0'),
                   int(conf.get('bind_port', default_port)))
      address_family = [addr[0] for addr in socket.getaddrinfo(
          bind_addr[0], bind_addr[1], socket.AF_UNSPEC, socket.SOCK_STREAM)
          if addr[0] in (socket.AF_INET, socket.AF_INET6)][0]
      sock = None
      bind_timeout = int(conf.get('bind_timeout', 30))
      retry_until = time.time() + bind_timeout
      warn_ssl = False
      while not sock and time.time() < retry_until:
          try:
              sock = listen(bind_addr, backlog=int(conf.get('backlog', 4096)),
                            family=address_family)
              if 'cert_file' in conf:
                  warn_ssl = True
                  sock = ssl.wrap_socket(sock, certfile=conf['cert_file'],
                                         keyfile=conf['key_file'])
          except socket.error as err:
              if err.args[0] != errno.EADDRINUSE:
                  raise
              sleep(0.1)
      if not sock:
          raise Exception(_('Could not bind to %s:%s '
                            'after trying for %s seconds') % (
                                bind_addr[0], bind_addr[1], bind_timeout))
      sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
      # in my experience, sockets can hang around forever without keepalive
      sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
      sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
      if hasattr(socket, 'TCP_KEEPIDLE'):
          sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 600)
      if warn_ssl:
          ssl_warning_message = _('WARNING: SSL should only be enabled for '
                                  'testing purposes. Use external SSL '
                                  'termination for a production deployment.')
          get_logger(conf).warning(ssl_warning_message)
          print(ssl_warning_message)
      return sock
  
  
  class RestrictedGreenPool(GreenPool):
      """
      Works the same as GreenPool, but if the size is specified as one, then the
      spawn_n() method will invoke waitall() before returning to prevent the
      caller from doing any other work (like calling accept()).
      """
      def __init__(self, size=1024):
          super(RestrictedGreenPool, self).__init__(size=size)
          self._rgp_do_wait = (size == 1)
  
      def spawn_n(self, *args, **kwargs):
          super(RestrictedGreenPool, self).spawn_n(*args, **kwargs)
          if self._rgp_do_wait:
              self.waitall()
  
  
  class PipelineWrapper(object):
      """
      This class provides a number of utility methods for
      modifying the composition of a wsgi pipeline.
      """
  
      def __init__(self, context):
          self.context = context
  
      def __contains__(self, entry_point_name):
          try:
              self.index(entry_point_name)
              return True
          except ValueError:
              return False
  
      def startswith(self, entry_point_name):
          """
          Tests if the pipeline starts with the given entry point name.
  
          :param entry_point_name: entry point of middleware or app (Swift only)
  
          :returns: True if entry_point_name is first in pipeline, False
          otherwise
          """
          try:
              first_ctx = self.context.filter_contexts[0]
          except IndexError:
              first_ctx = self.context.app_context
          return first_ctx.entry_point_name == entry_point_name
  
      def _format_for_display(self, ctx):
          if ctx.entry_point_name:
              return ctx.entry_point_name
          elif inspect.isfunction(ctx.object):
              # ctx.object is a reference to the actual filter_factory
              # function, so we pretty-print that. It's not the nice short
              # entry point, but it beats "<unknown>".
              #
              # These happen when, instead of something like
              #
              #    use = egg:swift#healthcheck
              #
              # you have something like this:
              #
              #    paste.filter_factory = \
              #        swift.common.middleware.healthcheck:filter_factory
              return "%s:%s" % (inspect.getmodule(ctx.object).__name__,
                                ctx.object.__name__)
          else:
              # No idea what this is
              return "<unknown context>"
  
      def __str__(self):
          parts = [self._format_for_display(ctx)
                   for ctx in self.context.filter_contexts]
          parts.append(self._format_for_display(self.context.app_context))
          return " ".join(parts)
  
      def create_filter(self, entry_point_name):
          """
          Creates a context for a filter that can subsequently be added
          to a pipeline context.
  
          :param entry_point_name: entry point of the middleware (Swift only)
  
          :returns: a filter context
          """
          spec = 'egg:swift#' + entry_point_name
          ctx = loadwsgi.loadcontext(loadwsgi.FILTER, spec,
                                     global_conf=self.context.global_conf)
          ctx.protocol = 'paste.filter_factory'
          return ctx
  
      def index(self, entry_point_name):
          """
          Returns the first index of the given entry point name in the pipeline.
  
          Raises ValueError if the given module is not in the pipeline.
          """
          for i, ctx in enumerate(self.context.filter_contexts):
              if ctx.entry_point_name == entry_point_name:
                  return i
          raise ValueError("%s is not in pipeline" % (entry_point_name,))
  
      def insert_filter(self, ctx, index=0):
          """
          Inserts a filter module into the pipeline context.
  
          :param ctx: the context to be inserted
          :param index: (optional) index at which filter should be
                        inserted in the list of pipeline filters. Default
                        is 0, which means the start of the pipeline.
          """
          self.context.filter_contexts.insert(index, ctx)
  
  
  def loadcontext(object_type, uri, name=None, relative_to=None,
                  global_conf=None):
      add_conf_type = wrap_conf_type(lambda x: x)
      return loadwsgi.loadcontext(object_type, add_conf_type(uri), name=name,
                                  relative_to=relative_to,
                                  global_conf=global_conf)
  
  
  def loadapp(conf_file, global_conf):
      """
      Loads a context from a config file, and if the context is a pipeline
      then presents the app with the opportunity to modify the pipeline.
      """
      ctx = loadcontext(loadwsgi.APP, conf_file, global_conf=global_conf)
      if ctx.object_type.name == 'pipeline':
          # give app the opportunity to modify the pipeline context
          app = ctx.app_context.create()
          func = getattr(app, 'modify_wsgi_pipeline', None)
          if func:
              func(PipelineWrapper(ctx))
      return ctx.create()
  
  
  def run_server(conf, logger, sock, global_conf=None):
      # Ensure TZ environment variable exists to avoid stat('/etc/localtime') on
      # some platforms. This locks in reported times to the timezone in which
      # the server first starts running in locations that periodically change
      # timezones.
      os.environ['TZ'] = time.strftime("%z", time.gmtime())
  
      wsgi.HttpProtocol.default_request_version = "HTTP/1.0"
      # Turn off logging requests by the underlying WSGI software.
      wsgi.HttpProtocol.log_request = lambda *a: None
      # Redirect logging other messages by the underlying WSGI software.
      wsgi.HttpProtocol.log_message = \
          lambda s, f, *a: logger.error('ERROR WSGI: ' + f % a)
      wsgi.WRITE_TIMEOUT = int(conf.get('client_timeout') or 60)
  
      eventlet.hubs.use_hub(get_hub())
      eventlet.patcher.monkey_patch(all=False, socket=True)
      eventlet_debug = config_true_value(conf.get('eventlet_debug', 'no'))
      eventlet.debug.hub_exceptions(eventlet_debug)
      # utils.LogAdapter stashes name in server; fallback on unadapted loggers
      if not global_conf:
          if hasattr(logger, 'server'):
              log_name = logger.server
          else:
              log_name = logger.name
          global_conf = {'log_name': log_name}
      app = loadapp(conf['__file__'], global_conf=global_conf)
      max_clients = int(conf.get('max_clients', '1024'))
      pool = RestrictedGreenPool(size=max_clients)
      try:
          wsgi.server(sock, app, NullLogger(), custom_pool=pool)
      except socket.error as err:
          if err[0] != errno.EINVAL:
              raise
      pool.waitall()
  
  
  #TODO(clayg): pull more pieces of this to test more
  def run_wsgi(conf_path, app_section, *args, **kwargs):
      """
      Runs the server using the specified number of workers.
  
      :param conf_path: Path to paste.deploy style configuration file/directory
      :param app_section: App name from conf file to load config from
      :returns: 0 if successful, nonzero otherwise
      """
      # Load configuration, Set logger and Load request processor
      try:
          (conf, logger, log_name) = \
              _initrp(conf_path, app_section, *args, **kwargs)
      except ConfigFileError as e:
          print e
          return 1
  
      # bind to address and port
      sock = get_socket(conf, default_port=kwargs.get('default_port', 8080))
      # remaining tasks should not require elevated privileges
      drop_privileges(conf.get('user', 'swift'))
  
      # Ensure the configuration and application can be loaded before proceeding.
      global_conf = {'log_name': log_name}
      if 'global_conf_callback' in kwargs:
          kwargs['global_conf_callback'](conf, global_conf)
      loadapp(conf_path, global_conf=global_conf)
  
      # set utils.FALLOCATE_RESERVE if desired
      reserve = int(conf.get('fallocate_reserve', 0))
      if reserve > 0:
          utils.FALLOCATE_RESERVE = reserve
      # redirect errors to logger and close stdio
      capture_stdio(logger)
  
      worker_count = config_auto_int_value(conf.get('workers'), CPU_COUNT)
  
      # Useful for profiling [no forks].
      if worker_count == 0:
          run_server(conf, logger, sock, global_conf=global_conf)
          return 0
  
      def kill_children(*args):
          """Kills the entire process group."""
          logger.error('SIGTERM received')
          signal.signal(signal.SIGTERM, signal.SIG_IGN)
          running[0] = False
          os.killpg(0, signal.SIGTERM)
  
      def hup(*args):
          """Shuts down the server, but allows running requests to complete"""
          logger.error('SIGHUP received')
          signal.signal(signal.SIGHUP, signal.SIG_IGN)
          running[0] = False
  
      running = [True]
      signal.signal(signal.SIGTERM, kill_children)
      signal.signal(signal.SIGHUP, hup)
      children = []
      while running[0]:
          while len(children) < worker_count:
              pid = os.fork()
              if pid == 0:
                  signal.signal(signal.SIGHUP, signal.SIG_DFL)
                  signal.signal(signal.SIGTERM, signal.SIG_DFL)
                  run_server(conf, logger, sock)
                  logger.notice('Child %d exiting normally' % os.getpid())
                  return 0
              else:
                  logger.notice('Started child %s' % pid)
                  children.append(pid)
          try:
              pid, status = os.wait()
              if os.WIFEXITED(status) or os.WIFSIGNALED(status):
                  logger.error('Removing dead child %s' % pid)
                  children.remove(pid)
          except OSError as err:
              if err.errno not in (errno.EINTR, errno.ECHILD):
                  raise
          except KeyboardInterrupt:
              logger.notice('User quit')
              break
      greenio.shutdown_safe(sock)
      sock.close()
      logger.notice('Exited')
      return 0
  
  
  class ConfigFileError(Exception):
      pass
  
  
  def _initrp(conf_path, app_section, *args, **kwargs):
      try:
          conf = appconfig(conf_path, name=app_section)
      except Exception as e:
          raise ConfigFileError("Error trying to load config from %s: %s" %
                                (conf_path, e))
  
      validate_configuration()
  
      # pre-configure logger
      log_name = conf.get('log_name', app_section)
      if 'logger' in kwargs:
          logger = kwargs.pop('logger')
      else:
          logger = get_logger(conf, log_name,
                              log_to_console=kwargs.pop('verbose', False),
                              log_route='wsgi')
  
      # disable fallocate if desired
      if config_true_value(conf.get('disable_fallocate', 'no')):
          disable_fallocate()
  
      monkey_patch_mimetools()
      return (conf, logger, log_name)
  
  
  def init_request_processor(conf_path, app_section, *args, **kwargs):
      """
      Loads common settings from conf
      Sets the logger
      Loads the request processor
  
      :param conf_path: Path to paste.deploy style configuration file/directory
      :param app_section: App name from conf file to load config from
      :returns: the loaded application entry point
      :raises ConfigFileError: Exception is raised for config file error
      """
      (conf, logger, log_name) = _initrp(conf_path, app_section, *args, **kwargs)
      app = loadapp(conf_path, global_conf={'log_name': log_name})
      return (app, conf, logger, log_name)
  
  
  class WSGIContext(object):
      """
      This class provides a means to provide context (scope) for a middleware
      filter to have access to the wsgi start_response results like the request
      status and headers.
      """
      def __init__(self, wsgi_app):
          self.app = wsgi_app
  
      def _start_response(self, status, headers, exc_info=None):
          """
          Saves response info without sending it to the remote client.
          Uses the same semantics as the usual WSGI start_response.
          """
          self._response_status = status
          self._response_headers = headers
          self._response_exc_info = exc_info
  
      def _app_call(self, env):
          """
          Ensures start_response has been called before returning.
          """
          self._response_status = None
          self._response_headers = None
          self._response_exc_info = None
          resp = self.app(env, self._start_response)
          # if start_response has been called, just return the iter
          if self._response_status is not None:
              return resp
          resp = iter(resp)
          try:
              first_chunk = resp.next()
          except StopIteration:
              return iter([])
          else:  # We got a first_chunk
              return CloseableChain([first_chunk], resp)
  
      def _get_status_int(self):
          """
          Returns the HTTP status int from the last called self._start_response
          result.
          """
          return int(self._response_status.split(' ', 1)[0])
  
      def _response_header_value(self, key):
          "Returns str of value for given header key or None"
          for h_key, val in self._response_headers:
              if h_key.lower() == key.lower():
                  return val
          return None
  
  
  def make_pre_authed_request(env, method=None, path=None, body=None,
                              headers=None, agent='Swift', swift_source=None):
      """
      Makes a new swob.Request based on the current env but with the
      parameters specified. Note that this request will be preauthorized.
  
      :param env: The WSGI environment to base the new request on.
      :param method: HTTP method of new request; default is from
                     the original env.
      :param path: HTTP path of new request; default is from the
                   original env. path should be compatible with what you
                   would send to Request.blank. path should be quoted and it
                   can include a query string. for example:
                   '/a%20space?unicode_str%E8%AA%9E=y%20es'
      :param body: HTTP body of new request; empty by default.
      :param headers: Extra HTTP headers of new request; None by
                      default.
      :param agent: The HTTP user agent to use; default 'Swift'. You
                    can put %(orig)s in the agent to have it replaced
                    with the original env's HTTP_USER_AGENT, such as
                    '%(orig)s StaticWeb'. You also set agent to None to
                    use the original env's HTTP_USER_AGENT or '' to
                    have no HTTP_USER_AGENT.
      :param swift_source: Used to mark the request as originating out of
                           middleware. Will be logged in proxy logs.
      :returns: Fresh swob.Request object.
      """
      query_string = None
      path = path or ''
      if path and '?' in path:
          path, query_string = path.split('?', 1)
      newenv = make_pre_authed_env(env, method, path=unquote(path), agent=agent,
                                   query_string=query_string,
                                   swift_source=swift_source)
      if not headers:
          headers = {}
      if body:
          return Request.blank(path, environ=newenv, body=body, headers=headers)
      else:
          return Request.blank(path, environ=newenv, headers=headers)
  
  
  def make_pre_authed_env(env, method=None, path=None, agent='Swift',
                          query_string=None, swift_source=None):
      """
      Returns a new fresh WSGI environment with escalated privileges to
      do backend checks, listings, etc. that the remote user wouldn't
      be able to accomplish directly.
  
      :param env: The WSGI environment to base the new environment on.
      :param method: The new REQUEST_METHOD or None to use the
                     original.
      :param path: The new path_info or none to use the original. path
                   should NOT be quoted. When building a url, a Webob
                   Request (in accordance with wsgi spec) will quote
                   env['PATH_INFO'].  url += quote(environ['PATH_INFO'])
      :param query_string: The new query_string or none to use the original.
                           When building a url, a Webob Request will append
                           the query string directly to the url.
                           url += '?' + env['QUERY_STRING']
      :param agent: The HTTP user agent to use; default 'Swift'. You
                    can put %(orig)s in the agent to have it replaced
                    with the original env's HTTP_USER_AGENT, such as
                    '%(orig)s StaticWeb'. You also set agent to None to
                    use the original env's HTTP_USER_AGENT or '' to
                    have no HTTP_USER_AGENT.
      :param swift_source: Used to mark the request as originating out of
                           middleware. Will be logged in proxy logs.
      :returns: Fresh WSGI environment.
      """
      newenv = {}
      for name in ('eventlet.posthooks', 'HTTP_USER_AGENT', 'HTTP_HOST',
                   'PATH_INFO', 'QUERY_STRING', 'REMOTE_USER', 'REQUEST_METHOD',
                   'SCRIPT_NAME', 'SERVER_NAME', 'SERVER_PORT', 'HTTP_ORIGIN',
                   'SERVER_PROTOCOL', 'swift.cache', 'swift.source',
                   'swift.trans_id'):
          if name in env:
              newenv[name] = env[name]
      if method:
          newenv['REQUEST_METHOD'] = method
      if path:
          newenv['PATH_INFO'] = path
          newenv['SCRIPT_NAME'] = ''
      if query_string is not None:
          newenv['QUERY_STRING'] = query_string
      if agent:
          newenv['HTTP_USER_AGENT'] = (
              agent % {'orig': env.get('HTTP_USER_AGENT', '')}).strip()
      elif agent == '' and 'HTTP_USER_AGENT' in newenv:
          del newenv['HTTP_USER_AGENT']
      if swift_source:
          newenv['swift.source'] = swift_source
      newenv['swift.authorize'] = lambda req: None
      newenv['swift.authorize_override'] = True
      newenv['REMOTE_USER'] = '.wsgi.pre_authed'
      newenv['wsgi.input'] = StringIO('')
      if 'SCRIPT_NAME' not in newenv:
          newenv['SCRIPT_NAME'] = ''
      return newenv
  