text: # Copyright (c) 2010-2012 OpenStack, LLC.
  #
  # 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 os
  import signal
  import time
  import mimetools
  from itertools import chain
  from StringIO import StringIO
  
  import eventlet
  from eventlet import greenio, GreenPool, sleep, wsgi, listen
  from paste.deploy import loadapp, appconfig
  from eventlet.green import socket, ssl
  from webob import Request
  from urllib import unquote
  
  from swift.common.utils import capture_stdio, disable_fallocate, \
      drop_privileges, get_logger, NullLogger, TRUE_VALUES, \
      validate_configuration
  
  
  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
      retry_until = time.time() + 30
      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, 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 30 seconds' %
                          bind_addr)
      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_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
  
  
  # TODO: pull pieces of this out to test
  def run_wsgi(conf_file, app_section, *args, **kwargs):
      """
      Loads common settings from conf, then instantiates app and runs
      the server using the specified number of workers.
  
      :param conf_file: Path to paste.deploy style configuration file
      :param app_section: App name from conf file to load config from
      """
  
      try:
          conf = appconfig('config:%s' % conf_file, name=app_section)
      except Exception, e:
          print "Error trying to load config %s: %s" % (conf_file, e)
          return
      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 conf.get('disable_fallocate', 'no').lower() in TRUE_VALUES:
          disable_fallocate()
  
      # 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 application can be loaded before proceeding.
      loadapp('config:%s' % conf_file, global_conf={'log_name': log_name})
  
      # redirect errors to logger and close stdio
      capture_stdio(logger)
  
      def run_server():
          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('poll')
          eventlet.patcher.monkey_patch(all=False, socket=True)
          monkey_patch_mimetools()
          app = loadapp('config:%s' % conf_file,
                        global_conf={'log_name': log_name})
          pool = GreenPool(size=1024)
          try:
              wsgi.server(sock, app, NullLogger(), custom_pool=pool)
          except socket.error, err:
              if err[0] != errno.EINVAL:
                  raise
          pool.waitall()
  
      worker_count = int(conf.get('workers', '1'))
      # Useful for profiling [no forks].
      if worker_count == 0:
          run_server()
          return
  
      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()
                  logger.notice('Child %d exiting normally' % os.getpid())
                  return
              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, 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')
  
  
  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
          # Results from the last call to self._start_response.
          self._response_status = None
          self._response_headers = None
          self._response_exc_info = None
  
      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.
          """
          resp = iter(self.app(env, self._start_response))
          try:
              first_chunk = resp.next()
          except StopIteration:
              return iter([])
          else:  # We got a first_chunk
              return chain([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'):
      """
      Makes a new webob.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.
      :returns: Fresh webob.Request object.
      """
      query_string = None
      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)
      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):
      """
      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.
      :returns: Fresh WSGI environment.
      """
      newenv = {}
      for name in ('eventlet.posthooks', 'HTTP_USER_AGENT', 'HTTP_HOST',
                   'PATH_INFO', 'QUERY_STRING', 'REMOTE_USER', 'REQUEST_METHOD',
                   'SERVER_NAME', 'SERVER_PORT', '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
      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']
      newenv['swift.authorize'] = lambda req: None
      newenv['swift.authorize_override'] = True
      newenv['REMOTE_USER'] = '.wsgi.pre_authed'
      newenv['wsgi.input'] = StringIO('')
      return newenv
  