# VMware vSphere Python SDK
# Copyright (c) 2008-2013 VMware, Inc. All Rights Reserved.
#
# 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.
from __future__ import absolute_import

from six import PY2
from six import PY3
from six import reraise
from six.moves import http_client

if PY3:
    long = int
    basestring = str
from six import u
import sys
import os
import socket
import subprocess
import time
from six.moves.urllib.parse import urlparse
from datetime import datetime
from xml.parsers.expat import ParserCreate
# We have our own escape functionality.
# from xml.sax.saxutils import escape
if PY2:
    from cStringIO import StringIO

if PY3:
    from io import StringIO
from pyVmomi.VmomiSupport import *
from pyVmomi.StubAdapterAccessorImpl import StubAdapterAccessorMixin
import pyVmomi.Iso8601
import base64
from xml.parsers.expat import ExpatError
import copy
import contextlib

try:
   USERWORLD = os.uname()[0] == 'VMkernel'
except:
   USERWORLD = False

# Timeout value used for idle connections in client connection pool.
# Default value is 900 seconds (15 minutes).
CONNECTION_POOL_IDLE_TIMEOUT_SEC = 900

NS_SEP = " "

XML_ENCODING = 'UTF-8'
XML_HEADER = '<?xml version="1.0" encoding="{0}"?>'.format(XML_ENCODING)

XMLNS_SOAPENC = "http://schemas.xmlsoap.org/soap/encoding/"
XMLNS_SOAPENV = "http://schemas.xmlsoap.org/soap/envelope/"

XSI_TYPE = XMLNS_XSI + NS_SEP + u('type')

# Note: Must make a copy to use the SOAP_NSMAP
# TODO: Change to frozendict, if available
SOAP_NSMAP = { XMLNS_SOAPENC: 'soapenc', XMLNS_SOAPENV: 'soapenv',
               XMLNS_XSI: 'xsi', XMLNS_XSD: 'xsd' }

SOAP_ENVELOPE_TAG = "{0}:Envelope".format(SOAP_NSMAP[XMLNS_SOAPENV])
SOAP_HEADER_TAG = "{0}:Header".format(SOAP_NSMAP[XMLNS_SOAPENV])
SOAP_FAULT_TAG = "{0}:Fault".format(SOAP_NSMAP[XMLNS_SOAPENV])
SOAP_BODY_TAG = "{0}:Body".format(SOAP_NSMAP[XMLNS_SOAPENV])

SOAP_ENVELOPE_START = '<{0} '.format(SOAP_ENVELOPE_TAG) + \
                      ' '.join(['xmlns:' + prefix + '="' + urn + '"' \
                                for urn, prefix in iteritems(SOAP_NSMAP)]) + \
                      '>\n'
SOAP_ENVELOPE_END = "\n</{0}>".format(SOAP_ENVELOPE_TAG)
SOAP_HEADER_START = "<{0}>".format(SOAP_HEADER_TAG)
SOAP_HEADER_END = "</{0}>".format(SOAP_HEADER_TAG)
SOAP_BODY_START = "<{0}>".format(SOAP_BODY_TAG)
SOAP_BODY_END = "</{0}>".format(SOAP_BODY_TAG)
SOAP_START = SOAP_ENVELOPE_START + SOAP_BODY_START + '\n'
SOAP_END = '\n' + SOAP_BODY_END + SOAP_ENVELOPE_END

WSSE_PREFIX = "wsse"
WSSE_HEADER_TAG = "{0}:Security".format(WSSE_PREFIX)
WSSE_NS_URL = "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
WSSE_NS = 'xmlns:{0}="{1}"'.format(WSSE_PREFIX, WSSE_NS_URL)
WSSE_HEADER_START = "<{0} {1}>".format(WSSE_HEADER_TAG, WSSE_NS)
WSSE_HEADER_END = "</{0}>".format(WSSE_HEADER_TAG)

## MethodFault type
MethodFault = GetVmodlType("vmodl.MethodFault")
## Localized MethodFault type
LocalizedMethodFault = GetVmodlType("vmodl.LocalizedMethodFault")

def encode(string, encoding):
    if PY2:
        return string.encode(encoding)
    return u(string)

## Escape <, >, &
def XmlEscape(xmlStr):
    escaped = xmlStr.replace("&", "&amp;").replace(">", "&gt;").replace("<", "&lt;")
    return escaped

## Get the start tag, end tag, and text handlers of a class
def GetHandlers(obj):
   return (obj.StartElementHandler,
           obj.EndElementHandler,
           obj.CharacterDataHandler,
           obj.StartNamespaceDeclHandler,
           obj.EndNamespaceDeclHandler)

## Set the start tag, end tag, and text handlers of a parser
def SetHandlers(obj, handlers):
   (obj.StartElementHandler,
    obj.EndElementHandler,
    obj.CharacterDataHandler,
    obj.StartNamespaceDeclHandler,
    obj.EndNamespaceDeclHandler) = handlers

## Serialize an object
#
# This function assumes CheckField(info, val) was already called
# @param val the value to serialize
# @param info the field
# @param version the version
# @param nsMap a dict of xml ns -> prefix
# @return the serialized object as a string
def Serialize(val, info=None, version=None, nsMap=None, encoding=None):
   if version is None:
      try:
         if isinstance(val, list):
            itemType = val.Item
            version = itemType._version
         else:
            if val is None:
               # neither val nor version is given
               return ''
            # Pick up the version from val
            version = val._version
      except AttributeError:
         version = BASE_VERSION
   if info is None:
      info = Object(name="object", type=object, version=version, flags=0)

   writer = StringIO()
   SoapSerializer(writer, version, nsMap, encoding).Serialize(val, info)
   return writer.getvalue()

## Serialize fault detail
#
# Serializes a fault as the content of the detail element in a
# soapenv:Fault (i.e. without a LocalizedMethodFault wrapper).
#
# This function assumes CheckField(info, val) was already called
# @param val the value to serialize
# @param info the field
# @param version the version
# @param nsMap a dict of xml ns -> prefix
# @return the serialized object as a string
def SerializeFaultDetail(val, info=None, version=None, nsMap=None, encoding=None):
   if version is None:
      try:
         if not isinstance(val, MethodFault):
            raise TypeError('{0} is not a MethodFault'.format(str(val)))
         version = val._version
      except AttributeError:
         version = BASE_VERSION
   if info is None:
      info = Object(name="object", type=object, version=version, flags=0)

   writer = StringIO()
   SoapSerializer(writer, version, nsMap, encoding).SerializeFaultDetail(val, info)
   return writer.getvalue()

## SOAP serializer
#
class SoapSerializer:
   """ SoapSerializer """
   ## Serializer constructor
   #
   # @param writer File writer
   # @param version the version
   # @param nsMap a dict of xml ns -> prefix
   def __init__(self, writer, version, nsMap, encoding):
      """ Constructor """
      self.writer = writer
      self.version = version
      self.nsMap = nsMap and nsMap or {}
      self.encoding = encoding and encoding or XML_ENCODING
      for ns, prefix in iteritems(self.nsMap):
         if prefix == '':
            self.defaultNS = ns
            break
      else:
         self.defaultNS = ''

      # Additional attr for outermost tag
      self.outermostAttrs = ''

      # Fill in required xmlns, if not defined
      for nsPrefix, ns, attrName in [('xsi', XMLNS_XSI, 'xsiPrefix'),
                                     ('xsd', XMLNS_XSD, 'xsdPrefix')]:
         prefix = self.nsMap.get(ns)
         if not prefix:
            prefix = nsPrefix
            self.outermostAttrs += ' xmlns:{0}="{1}"'.format(prefix, ns)
            self.nsMap = self.nsMap.copy()
            self.nsMap[ns] = prefix
         setattr(self, attrName, prefix + ":")


   ## Serialize an object
   #
   # This function assumes CheckField(info, val) was already called
   # @param val the value to serialize
   # @param info the field
   def Serialize(self, val, info):
      """ Serialize an object """
      self._Serialize(val, info, self.defaultNS)

   ## Serialize fault detail
   #
   # Serializes a fault as the content of the detail element in a
   # soapenv:Fault (i.e. without a LocalizedMethodFault wrapper).
   #
   # This function assumes CheckField(info, val) was already called
   # @param val the value to serialize
   # @param info the field
   def SerializeFaultDetail(self, val, info):
      """ Serialize an object """
      self._SerializeDataObject(val, info, '', self.defaultNS)

   def _NSPrefix(self, ns):
      """ Get xml ns prefix. self.nsMap must be set """
      if ns == self.defaultNS:
         return ''
      prefix = self.nsMap[ns]
      return prefix and prefix + ':' or ''

   def _QName(self, typ, defNS):
      """ Get fully qualified wsdl name (prefix:name) """
      attr = ''
      ns, name = GetQualifiedWsdlName(typ)
      if ns == defNS:
         prefix = ''
      else:
         try:
            prefix = self.nsMap[ns]
         except KeyError:
            # We have not seen this ns before
            prefix = ns.split(':', 1)[-1]
            attr = ' xmlns:{0}="{1}"'.format(prefix, ns)
      return attr, prefix and prefix + ':' + name or name

   ## Serialize an object (internal)
   #
   # @param val the value to serialize
   # @param info the field
   # @param defNS the default namespace
   def _Serialize(self, val, info, defNS):
      """ Serialize an object """
      if not IsChildVersion(self.version, info.version):
         return

      if val is None:
         if info.flags & F_OPTIONAL:
            return
         else:
            raise TypeError('Field "{0}" is not optional'.format(info.name))
      elif isinstance(val, list) and len(val) == 0:
         if info.type is object:
            # Make sure an empty array assigned to Any is typed
            if not isinstance(val, Array):
               raise TypeError('Field "{0}": Cannot assign empty native python array to an Any'.format(info.name))
         elif info.flags & F_OPTIONAL:
            # Skip optional non-Any
            return
         else:
             raise TypeError('Field "{0}" not optional'.format(info.name))

      if self.outermostAttrs:
         attr = self.outermostAttrs
         self.outermostAttrs = None
      else:
         attr = ''
      currDefNS = defNS
      # Emit default ns if tag ns is not the same
      currTagNS = GetWsdlNamespace(info.version)
      if currTagNS != defNS:
         attr += ' xmlns="{0}"'.format(currTagNS)
         currDefNS = currTagNS

      if isinstance(val, DataObject):
         if isinstance(val, MethodFault):
            newVal = LocalizedMethodFault(fault=val, localizedMessage=val.msg)
            if info.type is object:
               faultType = object
            else:
               faultType = LocalizedMethodFault
            newInfo = Object(name=info.name, type=faultType,
                             version=info.version, flags=info.flags)
            self._SerializeDataObject(newVal, newInfo, attr, currDefNS)
         else:
            self._SerializeDataObject(val, info, attr, currDefNS)
      elif isinstance(val, ManagedObject):
         if info.type is object:
            nsattr, qName = self._QName(ManagedObject, currDefNS)
            attr += '{0} {1}type="{2}"'.format(nsattr, self.xsiPrefix, qName)
         if val._serverGuid is not None:
            attr += ' serverGuid="{0}"'.format(val._serverGuid)
         # val in vim type attr is not namespace qualified
         # TODO: Add a new "typens" attr?
         ns, name = GetQualifiedWsdlName(Type(val))
         attr += ' type="{0}"'.format(name)
         self.writer.write('<{0}{1}>{2}</{3}>'.format(info.name, attr,
                                              encode(val._moId, self.encoding),
                                              info.name))
      elif isinstance(val, list):
         if info.type is object:
            itemType = val.Item
            if (itemType is ManagedMethod or itemType is PropertyPath
            or  itemType is type):
               tag = 'string'
               typ = GetVmodlType("string[]")
            elif issubclass(itemType, ManagedObject):
               tag = 'ManagedObjectReference'
               typ = ManagedObject.Array
            else:
               tag = GetWsdlName(itemType)
               typ = Type(val)
            nsattr, qName = self._QName(typ, currDefNS)

            # For WSDL, since we set tag of ManagedObjects to ManagedObjectReferences,
            # the name of its array should be ArrayOfManagedObjectReference
            if qName.endswith("ArrayOfManagedObject"):
               qName += "Reference"

            attr += '{0} {1}type="{2}"'.format(nsattr, self.xsiPrefix, qName)
            self.writer.write('<{0}{1}>'.format(info.name, attr))

            itemInfo = Object(name=tag, type=itemType,
                              version=info.version, flags=info.flags)
            for it in val:
               self._Serialize(it, itemInfo, currDefNS)
            self.writer.write('</{0}>'.format(info.name))
         else:
            itemType = info.type.Item
            itemInfo = Object(name=info.name, type=itemType,
                              version=info.version, flags=info.flags)
            for it in val:
               self._Serialize(it, itemInfo, defNS)
      elif isinstance(val, type) or isinstance(val, type(Exception)):
         if info.type is object:
            attr += ' {0}type="{1}string"'.format(self.xsiPrefix, self.xsdPrefix)
         self.writer.write('<{0}{1}>{2}</{0}>'.format(
                           info.name, attr, GetWsdlName(val)))
      elif isinstance(val, ManagedMethod):
         if info.type is object:
            attr += ' {0}type="{1}string"'.format(self.xsiPrefix, self.xsdPrefix)
         self.writer.write('<{0}{1}>{2}</{0}>'.format(
                              info.name, attr, val.info.wsdlName))
      elif isinstance(val, datetime):
         if info.type is object:
            nsattr, qName = self._QName(Type(val), currDefNS)
            attr += '{0} {1}type="{2}"'.format(nsattr, self.xsiPrefix, qName)
         result = Iso8601.ISO8601Format(val)
         self.writer.write('<{0}{1}>{2}</{0}>'.format(info.name, attr, result))
      elif isinstance(val, binary):
         if info.type is object:
            nsattr, qName = self._QName(Type(val), currDefNS)
            attr += '{0} {1}type="{2}"'.format(nsattr, self.xsiPrefix, qName)
         result = base64.b64encode(val)
         self.writer.write('<{0}{1}>{2}</{0}>'.format(info.name, attr, result))
      elif isinstance(val, bool):
         if info.type is object:
            nsattr, qName = self._QName(Type(val), currDefNS)
            attr += '{0} {1}type="{2}"'.format(nsattr, self.xsiPrefix, qName)
         result = val and "true" or "false"
         self.writer.write('<{0}{1}>{2}</{0}>'.format(info.name, attr, result))
      else:
         if info.type is object:
            if isinstance(val, PropertyPath):
               attr += ' {0}type="{1}string"'.format(self.xsiPrefix, self.xsdPrefix)
            else:
               nsattr, qName = self._QName(Type(val), currDefNS)
               attr += '{0} {1}type="{2}"'.format(nsattr, self.xsiPrefix, qName)
         if not isinstance(val, text_type):
            # Use UTF-8 rather than self.encoding.  self.encoding is for
            # output of serializer, while 'val' is our input.  And regardless
            # of what our output is, our input should be always UTF-8.  Yes,
            # it means that if you emit output in other encoding than UTF-8,
            # you cannot serialize it again once more.  That's feature, not
            # a bug.
            val = str(val)
            if PY2:
               val = val.decode('UTF-8')
         result = XmlEscape(val)
         self.writer.write('<{0}{1}>{2}</{0}>'.format(info.name, attr,
                                                      encode(result,
                                                             self.encoding)))

   ## Serialize a a data object (internal)
   #
   # @param val the value to serialize
   # @param info the field
   # @param attr attributes to serialized in the outermost elementt
   # @param currDefNS the current default namespace
   def _SerializeDataObject(self, val, info, attr, currDefNS):
      if info.flags & F_LINK:
         # Attribute is a link and Object is present instead of its key.
         # We need to serialize just the key and not the entire object
         self._Serialize(val.key, info, currDefNS)
         return
      dynType = GetCompatibleType(Type(val), self.version)
      if dynType != info.type:
         nsattr, qName = self._QName(dynType, currDefNS)
         attr += '{0} {1}type="{2}"'.format(nsattr, self.xsiPrefix, qName)
      self.writer.write('<{0}{1}>'.format(info.name, attr))
      if dynType is LocalizedMethodFault:
         # Serialize a MethodFault as LocalizedMethodFault on wire
         # See PR 670229
         for prop in val._GetPropertyList():
            propVal = getattr(val, prop.name)
            if prop.name == 'fault':
               propVal = copy.copy(propVal)
               propVal.msg = None
               self._SerializeDataObject(propVal, prop, '', currDefNS)
            else:
               self._Serialize(propVal, prop, currDefNS)
      else:
         for prop in val._GetPropertyList():
            self._Serialize(getattr(val, prop.name), prop, currDefNS)

      self.writer.write('</{0}>'.format(info.name))


class ParserError(KeyError):
    # NOTE (hartsock): extends KeyError since parser logic is written to
    # catch KeyError types. Normally, I would want PerserError to be a root
    # type for all parser faults.
    pass

def ReadDocument(parser, data):
   # NOTE (hartsock): maintaining library internal consistency here, this is
   # a refactoring that rolls up some repeated code blocks into a method so
   # that we can refactor XML parsing behavior in a single place.
   if not isinstance(data, str):
       data = data.read()
   try:
      parser.Parse(data)
   except Exception:
       # wrap all parser faults with additional information for later
       # bug reporting on the XML parser code itself.
       (ec, ev, tb) = sys.exc_info()
       line = parser.CurrentLineNumber
       col = parser.CurrentColumnNumber
       pe = ParserError("xml document: "
                        "{0} parse error at: "
                        "line:{1}, col:{2}".format(data, line, col))
       # use six.reraise for python 2.x and 3.x compatability
       reraise(ParserError, pe, tb)

## Deserialize an object from a file or string
#
# This function will deserialize one top-level XML node.
# @param data the data to deserialize (a file object or string)
# @param resultType expected result type
# @param stub stub for moRef deserialization
# @return the deserialized object
def Deserialize(data, resultType=object, stub=None):
   parser = ParserCreate(namespace_separator=NS_SEP)
   ds = SoapDeserializer(stub)
   ds.Deserialize(parser, resultType)
   ReadDocument(parser, data)
   return ds.GetResult()


## Expat deserializer namespace handler
class ExpatDeserializerNSHandlers:
   def __init__(self, nsMap=None):
      # nsMap is a dict of ns prefix to a stack (list) of namespaces
      # The last element of the stack is current namespace
      if not nsMap:
         nsMap = {}
      self.nsMap = nsMap

   ## Get current default ns
   def GetCurrDefNS(self):
      namespaces = self.nsMap.get(None)
      if namespaces:
         ns = namespaces[-1]
      else:
         ns = ""
      return ns

   ## Get namespace and wsdl name from tag
   def GetNSAndWsdlname(self, tag):
      """ Map prefix:name tag into ns, name """
      idx = tag.find(":")
      if idx >= 0:
         prefix, name = tag[:idx], tag[idx + 1:]
      else:
         prefix, name = None, tag
      # Map prefix to ns
      ns = self.nsMap[prefix][-1]
      return ns, name

   ## Handle namespace begin
   def StartNamespaceDeclHandler(self, prefix, uri):
      namespaces = self.nsMap.get(prefix)
      if namespaces:
         namespaces.append(uri)
      else:
         self.nsMap[prefix] = [uri]

   ## Handle namespace end
   def EndNamespaceDeclHandler(self, prefix):
      self.nsMap[prefix].pop()


## SOAP -> Python Deserializer
class SoapDeserializer(ExpatDeserializerNSHandlers):
   ## Constructor
   #
   # @param self self
   # @param stub Stub adapter to use for deserializing moRefs
   def __init__(self, stub=None, version=None):
      ExpatDeserializerNSHandlers.__init__(self)
      self.stub = stub
      if version:
         self.version = version
      elif self.stub:
         self.version = self.stub.version
      else:
         self.version = None
      self.result = None

   ## Deserialize a SOAP object
   #
   # @param self self
   # @param parser an expat parser
   # @param resultType the static type of the result
   # @param isFault true if the response is a fault response
   # @param nsMap a dict of prefix -> [xml ns stack]
   # @return the deserialized object
   def Deserialize(self, parser, resultType=object, isFault=False, nsMap=None):
      self.isFault = isFault
      self.parser = parser
      self.origHandlers = GetHandlers(parser)
      SetHandlers(parser, GetHandlers(self))
      self.resultType = resultType
      self.stack = []
      self.data = ""
      self.serverGuid = None
      if issubclass(resultType, list):
         self.result = resultType()
      else:
         self.result = None
      if not nsMap:
         nsMap = {}
      self.nsMap = nsMap

   ## Get the result of deserialization
   #  The links will not be resolved. User needs to explicitly resolve them
   #  using LinkResolver.
   def GetResult(self):
      return self.result

   def SplitTag(self, tag):
      """ Split tag into ns, name """
      idx = tag.find(NS_SEP)
      if idx >= 0:
         return tag[:idx], tag[idx + 1:]
      else:
         return "", tag

   def LookupWsdlType(self, ns, name, allowManagedObjectReference=False):
      """ Lookup wsdl type. Handle special case for some vmodl version """
      try:
         return GetWsdlType(ns, name)
      except KeyError:
         if allowManagedObjectReference:
            if name.endswith('ManagedObjectReference') and ns == XMLNS_VMODL_BASE:
               return GetWsdlType(ns, name[:-len('Reference')])
         # WARNING!!! This is a temporary hack to get around server not
         # honoring @service tag (see bug 521744). Once it is fix, I am
         # going to back out this change
         if name.endswith('ManagedObjectReference') and allowManagedObjectReference:
            return GetWsdlType(XMLNS_VMODL_BASE, name[:-len('Reference')])
         return GuessWsdlType(name)

   ## Handle an opening XML tag
   def StartElementHandler(self, tag, attr):
      self.data = ""
      self.serverGuid = None
      deserializeAsLocalizedMethodFault = True
      if not self.stack:
         if self.isFault:
            ns, name = self.SplitTag(tag)
            objType = self.LookupWsdlType(ns, name[:-5])
            # Only top level soap fault should be deserialized as method fault
            deserializeAsLocalizedMethodFault = False
         else:
            objType = self.resultType
      elif isinstance(self.stack[-1], list):
         objType = self.stack[-1].Item
      elif isinstance(self.stack[-1], DataObject):
         # TODO: Check ns matches DataObject's namespace
         ns, name = self.SplitTag(tag)
         objType = self.stack[-1]._GetPropertyInfo(name).type

         # LocalizedMethodFault <fault> tag should be deserialized as method fault
         if name == "fault" and isinstance(self.stack[-1], LocalizedMethodFault):
            deserializeAsLocalizedMethodFault = False
      else:
         raise TypeError("Invalid type for tag {0}".format(tag))

      xsiType = attr.get(XSI_TYPE)
      if xsiType:
         # Ignore dynamic type for TypeName, MethodName, PropertyPath
         # @bug 150459
         if not (objType is type or objType is ManagedMethod or \
                                    objType is PropertyPath):
            ns, name = self.GetNSAndWsdlname(xsiType)
            dynType = self.LookupWsdlType(ns, name, allowManagedObjectReference=True)
            # TODO: Should be something like...
            #   dynType must be narrower than objType, except for
            #   ManagedObjectReference
            if not (issubclass(dynType, list) and issubclass(objType, list)):
               objType = dynType
      else:
         if issubclass(objType, list):
            objType = objType.Item

      if self.version:
         objType = GetCompatibleType(objType, self.version)
      if issubclass(objType, ManagedObject):
         typeAttr = attr[u('type')]
         # val in vim type attr is not namespace qualified
         # However, this doesn't hurt to strip out namespace
         # TODO: Get the ns from "typens" attr?
         ns, name = self.GetNSAndWsdlname(typeAttr)
         if u('serverGuid') in attr:
            self.serverGuid = attr[u('serverGuid')]
         self.stack.append(GuessWsdlType(name))
      elif issubclass(objType, DataObject) or issubclass(objType, list):
         if deserializeAsLocalizedMethodFault and issubclass(objType, Exception):
            objType = LocalizedMethodFault
         self.stack.append(objType())
      else:
         self.stack.append(objType)

   ## Handle a closing XML tag
   def EndElementHandler(self, tag):
      try:
         obj = self.stack.pop()
      except IndexError:
         SetHandlers(self.parser, self.origHandlers)
         handler = self.parser.EndElementHandler
         del self.parser, self.origHandlers, self.stack, self.resultType
         if handler:
            return handler(tag)
         return

      data = self.data
      if isinstance(obj, type) or isinstance(obj, type(Exception)):
         if obj is type:
            if data is None or data == '':
               obj = None
            else:
               try:
                  # val in type val is not namespace qualified
                  # However, this doesn't hurt to strip out namespace
                  ns, name = self.GetNSAndWsdlname(data)
                  obj = GuessWsdlType(name)
               except KeyError:
                  raise TypeError(data)
         elif obj is ManagedMethod:
            # val in Method val is not namespace qualified
            # However, this doesn't hurt to strip out namespace
            ns, name = self.GetNSAndWsdlname(data)
            obj = GuessWsdlMethod(name)
         elif obj is bool:
            if data == "0" or data.lower() == "false":
               obj = bool(False)
            elif data == "1" or data.lower() == "true":
               obj = bool(True)
            else:
               raise TypeError(data)
         elif obj is binary:
            # Raise type error if decode failed
            obj = obj(base64.b64decode(data))
         elif obj is str:
            try:
               obj = str(data)
            except ValueError:
               obj = data
         elif obj is datetime:
            obj = pyVmomi.Iso8601.ParseISO8601(data)
            if not obj:
               raise TypeError(data)
         # issubclass is very expensive. Test last
         elif issubclass(obj, ManagedObject):
            obj = obj(data, self.stub, self.serverGuid)
         elif issubclass(obj, Enum):
            obj = getattr(obj, data)
         else:
            obj = obj(data)
      elif isinstance(obj, LocalizedMethodFault):
         obj.fault.msg = obj.localizedMessage
         obj = obj.fault

      if self.stack:
         top = self.stack[-1]
         if isinstance(top, list):
            top.append(obj)
         elif isinstance(top, DataObject):
            ns, name = self.SplitTag(tag)
            info = top._GetPropertyInfo(name)

            if not isinstance(obj, list) and issubclass(info.type, list):
               getattr(top, info.name).append(obj)
            else:
               setattr(top, info.name, obj)
         else:
            ns, name = self.SplitTag(tag)
            setattr(top, name, obj)
      else:
         if not isinstance(obj, list) and issubclass(self.resultType, list):
            self.result.append(obj)
         else:
            self.result = obj
            SetHandlers(self.parser, self.origHandlers)
            del self.parser, self.origHandlers, self.stack, self.resultType

   ## Handle text data
   def CharacterDataHandler(self, data):
      self.data += data


## SOAP Response Deserializer class
class SoapResponseDeserializer(ExpatDeserializerNSHandlers):
   ## Constructor
   #
   # @param self self
   # @param stub Stub adapter to use for deserializing moRefs
   def __init__(self, stub):
      ExpatDeserializerNSHandlers.__init__(self)
      self.stub = stub
      self.deser = SoapDeserializer(stub)
      self.soapFaultTag = XMLNS_SOAPENV + NS_SEP + "Fault"

   ## Deserialize a SOAP response
   #
   # @param self self
   # @param response the response (a file object or a string)
   # @param resultType expected result type
   # @param nsMap a dict of prefix -> [xml ns stack]
   # @return the deserialized object
   def Deserialize(self, response, resultType, nsMap=None):
      self.resultType = resultType
      self.stack = []
      self.msg = ""
      self.deser.result = None
      self.isFault = False
      self.parser = ParserCreate(namespace_separator=NS_SEP)
      try: # buffer_text only in python >= 2.3
         self.parser.buffer_text = True
      except AttributeError:
         pass
      if not nsMap:
         nsMap = {}
      self.nsMap = nsMap
      SetHandlers(self.parser, GetHandlers(self))
      ReadDocument(self.parser, response)
      result = self.deser.GetResult()
      if self.isFault:
         if result is None:
            result = GetVmodlType("vmodl.RuntimeFault")()
         result.msg = self.msg
      del self.resultType, self.stack, self.parser, self.msg, self.data, self.nsMap
      return result

   ## Handle an opening XML tag
   def StartElementHandler(self, tag, attr):
      self.data = ""
      if tag == self.soapFaultTag:
         self.isFault = True
      elif self.isFault and tag == "detail":
         self.deser.Deserialize(self.parser, object, True, self.nsMap)
      elif tag.endswith("Response"):
         self.deser.Deserialize(self.parser, self.resultType, False, self.nsMap)

   ## Handle text data
   def CharacterDataHandler(self, data):
      self.data += data

   ## Handle a closing XML tag
   def EndElementHandler(self, tag):
      if self.isFault and tag == "faultstring":
         try:
            self.msg = str(self.data)
         except ValueError:
            self.msg = self.data

## Base class that implements common functionality for stub adapters.
## Method that must be provided by the implementation class:
## -- InvokeMethod(ManagedObject mo, Object methodInfo, Object[] args)
class StubAdapterBase(StubAdapterAccessorMixin):
   def __init__(self, version):
      StubAdapterAccessorMixin.__init__(self)
      self.ComputeVersionInfo(version)

   ## Compute the version information for the specified namespace
   #
   # @param ns the namespace
   def ComputeVersionInfo(self, version):
      versionNS = GetVersionNamespace(version)
      if versionNS.find("/") >= 0:
         self.versionId = '"urn:{0}"'.format(versionNS)
      else:
         self.versionId = ''
      self.version = version

## Base class that implements common functionality for SOAP-based stub adapters.
## Method that must be provided by the implementation class:
## -- InvokeMethod(ManagedObject mo, Object methodInfo, Object[] args)
class SoapStubAdapterBase(StubAdapterBase):
   ## Serialize a VMOMI request to SOAP
   #
   # @param version API version
   # @param mo the 'this'
   # @param info method info
   # @param args method arguments
   # @return the serialized request
   def SerializeRequest(self, mo, info, args):
      if not IsChildVersion(self.version, info.version):
         raise GetVmodlType("vmodl.fault.MethodNotFound")(receiver=mo,
                                                          method=info.name)
      nsMap = SOAP_NSMAP.copy()
      defaultNS = GetWsdlNamespace(self.version)
      nsMap[defaultNS] = ''

      # Add xml header and soap envelope
      result = [XML_HEADER, '\n', SOAP_ENVELOPE_START]

      # Add request context and samlToken to soap header, if exists
      reqContexts = GetRequestContext()
      samlToken = getattr(self, 'samlToken', None)

      if reqContexts or samlToken:
         result.append(SOAP_HEADER_START)
         for key, val in iteritems(reqContexts):
            # Note: Support req context of string type only
            if not isinstance(val, basestring):
               raise TypeError("Request context key ({0}) has non-string value ({1}) of {2}".format(key, val, type(val)))
            ret = Serialize(val,
                            Object(name=key, type=str, version=self.version),
                            self.version,
                            nsMap)
            result.append(ret)
         if samlToken:
            result.append('{0} {1} {2}'.format(WSSE_HEADER_START,
                                               samlToken,
                                               WSSE_HEADER_END))
         result.append(SOAP_HEADER_END)
         result.append('\n')

      # Serialize soap body
      result.extend([SOAP_BODY_START,
                       '<{0} xmlns="{1}">'.format(info.wsdlName, defaultNS),
                       Serialize(mo, Object(name="_this", type=ManagedObject,
                                            version=self.version),
                                 self.version, nsMap)])

      # Serialize soap request parameters
      for (param, arg) in zip(info.params, args):
         result.append(Serialize(arg, param, self.version, nsMap))
      result.extend(['</{0}>'.format(info.wsdlName), SOAP_BODY_END, SOAP_ENVELOPE_END])
      return ''.join(result)

## Subclass of HTTPConnection that connects over a Unix domain socket
## instead of a TCP port.  The path of the socket is passed in place of
## the hostname.  Fairly gross but does the job.
# NOTE (hartsock): rewrite this class as a wrapper, see HTTPSConnectionWrapper
# below for a guide.
class UnixSocketConnection(http_client.HTTPConnection):
   # The HTTPConnection ctor expects a single argument, which it interprets
   # as the host to connect to; for UnixSocketConnection, we instead interpret
   # the parameter as the filesystem path of the Unix domain socket.
   def __init__(self, path):
      # Pass '' as the host to HTTPConnection; it doesn't really matter
      # what we pass (since we've overridden the connect method) as long
      # as it's a valid string.
      http_client.HTTPConnection.__init__(self, '')
      self.path = path

   def connect(self):
      # Hijack the connect method of HTTPConnection to connect to the
      # specified Unix domain socket instead.  Obey the same contract
      # as HTTPConnection.connect, which puts the socket in self.sock.
      sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
      sock.connect(self.path)
      self.sock = sock

try:
   # The ssl module is not available in python versions less than 2.6
   SSL_THUMBPRINTS_SUPPORTED = True

   import ssl
   import hashlib

   def _VerifyThumbprint(thumbprint, connection):
      '''If there is a thumbprint, connect to the server and verify that the
      SSL certificate matches the given thumbprint.  An exception is thrown
      if there is a mismatch.'''
      if thumbprint and isinstance(connection, http_client.HTTPSConnection):
         if not connection.sock:
            connection.connect()
         derCert = connection.sock.getpeercert(True)
         sha1 = hashlib.sha1()
         sha1.update(derCert)
         sha1Digest = sha1.hexdigest().lower()
         if sha1Digest != thumbprint:
            raise Exception("Server has wrong SHA1 thumbprint: {0} "
                            "(required) != {1} (server)".format(
                            thumbprint, sha1Digest))

   # Function used to wrap sockets with SSL
   _SocketWrapper = ssl.wrap_socket

except ImportError:
   SSL_THUMBPRINTS_SUPPORTED = False

   def _VerifyThumbprint(thumbprint, connection):
      if thumbprint and isinstance(connection, http_client.HTTPSConnection):
         raise Exception(
            "Thumbprint verification not supported on python < 2.6")

   def _SocketWrapper(rawSocket, keyfile, certfile, *args, **kwargs):
      wrappedSocket = socket.ssl(rawSocket, keyfile, certfile)
      return http_client.FakeSocket(rawSocket, wrappedSocket)

## https connection wrapper
#
# NOTE (hartsock): do not override core library types or implementations
# directly because this makes brittle code that is too easy to break and
# closely tied to implementation details we do not control. Instead, wrap
# the core object to introduce additional behaviors.
#
# Purpose:
# Support ssl.wrap_socket params which are missing from httplib
# HTTPSConnection (e.g. ca_certs)
# Note: Only works iff the ssl params are passing in as kwargs
class HTTPSConnectionWrapper(object):
   def __init__(self, *args, **kwargs):
      wrapped = http_client.HTTPSConnection(*args, **kwargs)
      # Extract ssl.wrap_socket param unknown to httplib.HTTPConnection,
      # and push back the params in connect()
      self._sslArgs = {}
      tmpKwargs = kwargs.copy()
      for key in ["server_side", "cert_reqs", "ssl_version", "ca_certs",
                  "do_handshake_on_connect", "suppress_ragged_eofs",
                  "ciphers"]:
         if key in tmpKwargs:
            self._sslArgs[key] = tmpKwargs.pop(key)
      self._wrapped = wrapped

   ## Override connect to allow us to pass in additional ssl paramters to
   #  ssl.wrap_socket (e.g. cert_reqs, ca_certs for ca cert verification)
   def connect(self, wrapped):
      if len(self._sslArgs) == 0 or hasattr(self, '_baseclass'):
         # No override
         return wrapped.connect

      # Big hack. We have to copy and paste the httplib connect fn for
      # each python version in order to handle extra ssl paramters. Yuk!
      if hasattr(self, "source_address"):
         # Python 2.7
         sock = socket.create_connection((self.host, self.port),
                                         self.timeout, self.source_address)
         if wrapped._tunnel_host:
            wrapped.sock = sock
            wrapped._tunnel()
         wrapped.sock = ssl.wrap_socket(sock, self.key_file, self.cert_file, **self._sslArgs)
      elif hasattr(self, "timeout"):
         # Python 2.6
         sock = socket.create_connection((self.host, self.port), self.timeout)
         wrapped.sock = ssl.wrap_socket(sock, self.key_file, self.cert_file, **self._sslArgs)

      return wrapped.connect

      # TODO: Additional verification of peer cert if needed
      #cert_reqs = self._sslArgs.get("cert_reqs", ssl.CERT_NONE)
      #ca_certs = self._sslArgs.get("ca_certs", None)
      #if cert_reqs != ssl.CERT_NONE and ca_certs:
      #   if hasattr(self.sock, "getpeercert"):
      #      # TODO: verify peer cert
      #      dercert = self.sock.getpeercert(False)
      #      # pemcert = ssl.DER_cert_to_PEM_cert(dercert)

   def __getattr__(self, item):
       if item == 'connect':
           return self.connect(self._wrapped)
       return getattr(self._wrapped, item)

## Stand-in for the HTTPSConnection class that will connect to a proxy and
## issue a CONNECT command to start an SSL tunnel.
class SSLTunnelConnection(object):
   # @param proxyPath The path to pass to the CONNECT command.
   def __init__(self, proxyPath):
      self.proxyPath = proxyPath

   # Connects to a proxy server and initiates a tunnel to the destination
   # specified by proxyPath.  If successful, a new HTTPSConnection is returned.
   #
   # @param path The destination URL path.
   # @param key_file The SSL key file to use when wrapping the socket.
   # @param cert_file The SSL certificate file to use when wrapping the socket.
   # @param kwargs In case caller passed in extra parameters not handled by
   #        SSLTunnelConnection
   def __call__(self, path, key_file=None, cert_file=None, **kwargs):
      # Don't pass any keyword args that HTTPConnection won't understand.
      for arg in kwargs.keys():
         if arg not in ("port", "strict", "timeout", "source_address"):
            del kwargs[arg]
      tunnel = http_client.HTTPConnection(path, **kwargs)
      tunnel.request('CONNECT', self.proxyPath)
      resp = tunnel.getresponse()
      tunnelSocket = resp.fp
      if resp.status != 200:
        raise httplib.HTTPException("{0} {1}".format(resp.status, resp.reason))
      retval = http_client.HTTPSConnection(path)
      retval.sock = _SocketWrapper(tunnelSocket,
                                   keyfile=key_file, certfile=cert_file)
      return retval


class GzipReader:
   GZIP        = 1
   DEFLATE     = 2

   def __init__(self, rfile, encoding=GZIP, readChunkSize=512):
      self.rfile = rfile
      self.chunks = []
      self.bufSize = 0 # Remaining buffer
      assert(encoding in (GzipReader.GZIP, GzipReader.DEFLATE))
      self.encoding = encoding
      self.unzip = None
      self.readChunkSize = readChunkSize

   def _CreateUnzip(self, firstChunk):
      import zlib
      if self.encoding == GzipReader.GZIP:
         wbits = zlib.MAX_WBITS + 16
      elif self.encoding == GzipReader.DEFLATE:
         # Sniff out real deflate format
         chunkLen = len(firstChunk)
         # Assume raw deflate
         wbits = -zlib.MAX_WBITS
         if firstChunk[:3] == ['\x1f', '\x8b', '\x08']:
            # gzip: Apache mod_deflate will send gzip. Yurk!
            wbits = zlib.MAX_WBITS + 16
         elif chunkLen >= 2:
            b0 = ord(firstChunk[0])
            b1 = ord(firstChunk[1])
            if (b0 & 0xf) == 8 and (((b0 * 256 + b1)) % 31) == 0:
               # zlib deflate
               wbits = min(((b0 & 0xf0) >> 4) + 8, zlib.MAX_WBITS)
      else:
         assert(False)
      self.unzip = zlib.decompressobj(wbits)
      return self.unzip

   def read(self, bytes=-1):
      chunks = self.chunks
      bufSize = self.bufSize

      while bufSize < bytes or bytes == -1:
         # Read and decompress
         chunk = self.rfile.read(self.readChunkSize)

         if self.unzip == None:
            self._CreateUnzip(chunk)

         if chunk:
            inflatedChunk = self.unzip.decompress(chunk)
            bufSize += len(inflatedChunk)
            chunks.append(inflatedChunk)
         else:
            # Returns whatever we have
            break

      if bufSize <= bytes or bytes == -1:
         leftoverBytes = 0
         leftoverChunks = []
      else:
         leftoverBytes = bufSize - bytes
         # Adjust last chunk to hold only the left over bytes
         lastChunk = chunks.pop()
         chunks.append(lastChunk[:-leftoverBytes])
         leftoverChunks = [lastChunk[-leftoverBytes:]]

      self.chunks = leftoverChunks
      self.bufSize = leftoverBytes

      buf = "".join(chunks)
      return buf

## SOAP stub adapter object
class SoapStubAdapter(SoapStubAdapterBase):
   ## Constructor
   #
   # The endpoint can be specified individually as either a host/port
   # combination, or with a URL (using a url= keyword).
   #
   # @param self self
   # @param host host
   # @param port port (pass negative port number for no SSL)
   # @param **** Deprecated. Please use version instead **** ns API namespace
   # @param path location of SOAP VMOMI service
   # @param url URL (overrides host, port, path if set)
   # @param sock unix domain socket path (overrides host, port, url if set)
   # @param poolSize size of HTTP connection pool
   # @param certKeyFile The path to the PEM-encoded SSL private key file.
   # @param certFile The path to the PEM-encoded SSL certificate file.
   # @param httpProxyHost The host name of the proxy server.
   # @param httpProxyPort The proxy server port.
   # @param sslProxyPath Path to use when tunneling through VC's reverse proxy.
   # @param thumbprint The SHA1 thumbprint of the server's SSL certificate.
   #   Some use a thumbprint of the form xx:xx:xx..:xx.  We ignore the ":"
   #   characters.  If set to None, any thumbprint is accepted.
   # @param cacertsFile CA certificates file in PEM format
   # @param version API version
   # @param connectionPoolTimeout Timeout in secs for idle connections in client pool. Use -1 to disable any timeout.
   # @param samlToken SAML Token that should be used in SOAP security header for login
   def __init__(self, host='localhost', port=443, ns=None, path='/sdk',
                url=None, sock=None, poolSize=5,
                certFile=None, certKeyFile=None,
                httpProxyHost=None, httpProxyPort=80, sslProxyPath=None,
                thumbprint=None, cacertsFile=None, version=None,
                acceptCompressedResponses=True,
                connectionPoolTimeout=CONNECTION_POOL_IDLE_TIMEOUT_SEC,
                samlToken=None):
      if ns:
         assert(version is None)
         version = versionMap[ns]
      elif not version:
         version = 'vim.version.version1'
      SoapStubAdapterBase.__init__(self, version=version)
      self.cookie = ""
      if sock:
         self.scheme = UnixSocketConnection
         # Store sock in the host member variable because that's where
         # the UnixSocketConnection ctor expects to find it -- see above
         self.host = sock
      elif url:
         scheme, self.host, urlpath = urlparse.urlparse(url)[:3]
         # Only use the URL path if it's sensible, otherwise use the path
         # keyword argument as passed in.
         if urlpath not in ('', '/'):
            path = urlpath
         self.scheme = scheme == "http" and http_client.HTTPConnection \
                    or scheme == "https" and HTTPSConnectionWrapper
      else:
         port, self.scheme = port < 0 and (-port, http_client.HTTPConnection) \
                                       or (port, HTTPSConnectionWrapper)
         if host.find(':') != -1:  # is IPv6?
            host = '[' + host + ']'
         self.host = '{0}:{1}'.format(host, port)

      self.path = path
      if thumbprint:
         self.thumbprint = thumbprint.replace(":", "").lower()
         if len(self.thumbprint) != 40:
           raise Exception("Invalid SHA1 thumbprint -- {0}".format(thumbprint))
      else:
         self.thumbprint = None

      if sslProxyPath:
         self.scheme = SSLTunnelConnection(sslProxyPath)
      elif httpProxyHost:
         if self.scheme == HTTPSConnectionWrapper:
            self.scheme = SSLTunnelConnection(self.host)
         else:
            if url:
               self.path = url
            else:
               self.path = "http://{0}/{1}".format(self.host, path)
         # Swap the actual host with the proxy.
         self.host = "{0}:{1}".format(httpProxyHost, httpProxyPort)
      self.poolSize = poolSize
      self.pool = []
      self.connectionPoolTimeout = connectionPoolTimeout
      self.lock = threading.Lock()
      self.schemeArgs = {}
      if certKeyFile:
         self.schemeArgs['key_file'] = certKeyFile
      if certFile:
         self.schemeArgs['cert_file'] = certFile
      if cacertsFile:
         self.schemeArgs['ca_certs'] = cacertsFile
         self.schemeArgs['cert_reqs'] = ssl.CERT_REQUIRED
      self.samlToken = samlToken
      self.requestModifierList = []
      self._acceptCompressedResponses = acceptCompressedResponses


   # Context modifier used to modify the SOAP request.
   # @param func The func that takes in the serialized message and modifies the
   #   the request. The func is appended to the requestModifierList and then
   #   popped after the request is modified.
   @contextlib.contextmanager
   def requestModifier(self, func):
      self.requestModifierList.append(func)
      try:
         yield
      finally:
         self.requestModifierList.pop()
   ## Invoke a managed method
   #
   # @param self self
   # @param mo the 'this'
   # @param info method info
   # @param args arguments
   # @param outerStub If not-None, this should be a reference to the wrapping
   #   stub adapter.  Any ManagedObject references returned from this method
   #   will have outerStub in their _stub field.  Note that this also changes
   #   the return type to a tuple containing the HTTP status and the
   #   deserialized object so that it's easier to distinguish an API error from
   #   a connection error.
   def InvokeMethod(self, mo, info, args, outerStub=None):
      if outerStub is None:
         outerStub = self

      headers = {'Cookie' : self.cookie,
                 'SOAPAction' : self.versionId,
                 'Content-Type': 'text/xml; charset={0}'.format(XML_ENCODING)}
      if self._acceptCompressedResponses:
         headers['Accept-Encoding'] = 'gzip, deflate'
      req = self.SerializeRequest(mo, info, args)
      for modifier in self.requestModifierList:
         req = modifier(req)
      conn = self.GetConnection()
      try:
         conn.request('POST', self.path, req, headers)
         resp = conn.getresponse()
      except (socket.error, http_client.HTTPException):
         # The server is probably sick, drop all of the cached connections.
         self.DropConnections()
         raise
      # NOTE (hartsocks): this cookie handling code should go away in a future
      # release. The string 'set-cookie' and 'Set-Cookie' but both are
      # acceptable, but the supporting library may have a bug making it
      # case sensitive when it shouldn't be. The term 'set-cookie' will occur
      # more frequently than 'Set-Cookie' based on practical testing.
      cookie = resp.getheader('set-cookie')
      if cookie is None:
          # try case-sensitive header for compatibility
          cookie = resp.getheader('Set-Cookie')
      status = resp.status

      if cookie:
         self.cookie = cookie
      if status == 200 or status == 500:
         try:
            fd = resp
            encoding = resp.getheader('Content-Encoding', 'identity').lower()
            if encoding == 'gzip':
               fd = GzipReader(resp, encoding=GzipReader.GZIP)
            elif encoding == 'deflate':
               fd = GzipReader(resp, encoding=GzipReader.DEFLATE)
            deserializer = SoapResponseDeserializer(outerStub)
            obj = deserializer.Deserialize(fd, info.result)
         except Exception as exc:
            conn.close()
            # NOTE (hartsock): This feels out of place. As a rule the lexical
            # context that opens a connection should also close it. However,
            # in this code the connection is passed around and closed in other
            # contexts (ie: methods) that we are blind to here. Refactor this.

            # The server might be sick, drop all of the cached connections.
            self.DropConnections()
            raise exc
         else:
            resp.read()
            self.ReturnConnection(conn)
         if outerStub != self:
            return (status, obj)
         if status == 200:
            return obj
         else:
            raise obj # pylint: disable-msg=E0702
      else:
         conn.close()
         raise http_client.HTTPException("{0} {1}".format(resp.status, resp.reason))

   ## Clean up connection pool to throw away idle timed-out connections
   #  SoapStubAdapter lock must be acquired before this method is called.
   def _CloseIdleConnections(self):
      if self.connectionPoolTimeout >= 0:
         currentTime = time.time()
         idleConnections = []
         for conn, lastAccessTime in self.pool:
            idleTime = currentTime - lastAccessTime
            if idleTime >= self.connectionPoolTimeout:
               i = self.pool.index((conn, lastAccessTime))
               idleConnections = self.pool[i:]
               self.pool = self.pool[:i]
               break

         for conn, _ in idleConnections:
            conn.close()

   ## Get a HTTP connection from the pool
   def GetConnection(self):
      self.lock.acquire()
      self._CloseIdleConnections()
      if self.pool:
         result, _ = self.pool.pop(0)
         self.lock.release()
      else:
         self.lock.release()
         result = self.scheme(self.host, **self.schemeArgs)

         # Always disable NAGLE algorithm
         #
         # Python httplib (2.6 and below) is splitting a http request into 2
         # packets (header and body). It first send the header, but will not
         # send the body until it receives the ack (for header) from server
         # [NAGLE at work]. The delayed ack time on ESX is around 40 - 100 ms
         # (depends on version) and can go up to 200 ms. This effectively slow
         # down each pyVmomi call by the same amount of time.
         #
         # Disable NAGLE on client will force both header and body packets to
         # get out immediately, and eliminated the delay
         #
         # This bug is fixed in python 2.7, however, only if the request
         # body is a string (which is true for now)
         if sys.version_info[:2] < (2,7):
            self.DisableNagle(result)

         _VerifyThumbprint(self.thumbprint, result)

      return result

   ## Drop all cached connections to the server.
   def DropConnections(self):
      self.lock.acquire()
      oldConnections = self.pool
      self.pool = []
      self.lock.release()
      for conn, _ in oldConnections:
         conn.close()

   ## Return a HTTP connection to the pool
   def ReturnConnection(self, conn):
      self.lock.acquire()
      self._CloseIdleConnections()
      if len(self.pool) < self.poolSize:
         self.pool.insert(0, (conn, time.time()))
         self.lock.release()
      else:
         self.lock.release()
         # NOTE (hartsock): this seems to violate good coding practice in that
         # the lexical context that opens a connection should also be the
         # same context responsible for closing it.
         conn.close()

   ## Disable nagle on a http connections
   def DisableNagle(self, conn):
      # Override connections' connect function to force disable NAGLE
      if self.scheme != UnixSocketConnection and getattr(conn, "connect"):
         orgConnect = conn.connect
         def ConnectDisableNagle(*args, **kwargs):
            orgConnect(*args, **kwargs)
            sock = getattr(conn, "sock")
            if sock:
               try:
                  sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
               except Exception:
                  pass
         conn.connect = ConnectDisableNagle


HEADER_SECTION_END = '\r\n\r\n'

## Parse an HTTP response into its headers and body
def ParseHttpResponse(httpResponse):
   headerEnd = httpResponse.find(HEADER_SECTION_END)
   if headerEnd == -1:
      return ('', '')
   headerEnd += len(HEADER_SECTION_END);
   headerText = httpResponse[:headerEnd]
   bodyText = httpResponse[headerEnd:]
   return (headerText, bodyText)


## SOAP-over-stdio stub adapter object
class SoapCmdStubAdapter(SoapStubAdapterBase):
   ## Constructor
   #
   # @param self self
   # @param cmd command to execute
   # @param ns API namespace
   def __init__(self, cmd, version='vim.version.version1'):
      SoapStubAdapterBase.__init__(self, version=version)
      self.cmd = cmd
      self.systemError = GetVmodlType('vmodl.fault.SystemError')

   ## Invoke a managed method
   #
   # @param self self
   # @param mo the 'this'
   # @param info method info
   # @param args arguments
   def InvokeMethod(self, mo, info, args):
      argv = self.cmd.split()
      req = self.SerializeRequest(mo, info, args)
      env = dict(os.environ)
      env['REQUEST_METHOD'] = 'POST'
      env['CONTENT_LENGTH'] = str(len(req))
      env['HTTP_SOAPACTION'] = self.versionId[1:-1]
      p = subprocess.Popen(argv,
                           stdin=subprocess.PIPE,
                           stdout=subprocess.PIPE,
                           stderr=subprocess.PIPE,
                           env=env)
      (outText, errText) = p.communicate(req)
      if p.returncode < 0:
         # Process died with a signal
         errText = "Process terminated with signal {0}\n{1}".format(-p.returncode, errText)
         raise self.systemError(msg=errText, reason=errText)

      try:
         (responseHeaders, responseBody) = ParseHttpResponse(outText)
         obj = SoapResponseDeserializer(self).Deserialize(responseBody, info.result)
      except:
         errText = "Failure parsing SOAP response ({0})\n{1}}".format(outText, errText)
         raise self.systemError(msg=errText, reason=errText)

      if p.returncode == 0:
         return obj
      elif obj is None:
         raise self.systemError(msg=errText, reason=errText)
      else:
         raise obj # pylint: disable-msg=E0702


class SessionOrientedStub(StubAdapterBase):
   '''A session-oriented stub adapter that will relogin to the destination if a
   session-oriented exception is thrown.


   Here's an example.  First, we setup the communication substrate:

   >>> soapStub = SoapStubAdapter(host="192.168.1.2", ns="vim25/5.0")

   Create a SessionOrientedStub that uses the stub we just created for talking
   to the server:

   >>> from pyVim.connect import VimSessionOrientedStub
   >>> sessionStub = VimSessionOrientedStub(
   ...     soapStub,
   ...     VimSessionOrientedStub.makeUserLoginMethod("root", "vmware"))

   Perform some privileged operations without needing to explicitly login:

   >>> si = Vim.ServiceInstance("ServiceInstance", sessionStub)
   >>> si.content.sessionManager.sessionList
   >>> si.content.sessionManager.Logout()
   >>> si.content.sessionManager.sessionList
   '''

   STATE_UNAUTHENTICATED = 0
   STATE_AUTHENTICATED = 1

   SESSION_EXCEPTIONS = tuple()

   def __init__(self, soapStub, loginMethod, retryDelay=0.1, retryCount=4):
      '''Construct a SessionOrientedStub.

      The stub starts off in the "unauthenticated" state, so it will call the
      loginMethod on the first invocation of a method.  If a communication error
      is encountered, the stub will wait for retryDelay seconds and then try to
      call the method again.  If the server throws an exception that is in the
      SESSION_EXCEPTIONS tuple, it will be caught and the stub will transition
      back into the "unauthenticated" state so that another login will be
      performed.

      @param soapStub The communication substrate.
      @param loginMethod A function that takes a single parameter, soapStub, and
        performs the necessary operations to authenticate with the server.
      @param retryDelay The amount of time to sleep before retrying after a
        communication error.
      @param retryCount The number of times to retry connecting to the server.
      '''
      assert callable(loginMethod)
      assert retryCount >= 0
      StubAdapterBase.__init__(self, version=soapStub.version)

      self.lock = threading.Lock()
      self.soapStub = soapStub
      self.state = self.STATE_UNAUTHENTICATED

      self.loginMethod = loginMethod
      self.retryDelay = retryDelay
      self.retryCount = retryCount

   def InvokeMethod(self, mo, info, args):
      # This retry logic is replicated in InvokeAccessor and the two copies need
      # to be in sync
      retriesLeft = self.retryCount
      while retriesLeft > 0:
         try:
            if self.state == self.STATE_UNAUTHENTICATED:
               self._CallLoginMethod()
            # Invoke the method
            status, obj = self.soapStub.InvokeMethod(mo, info, args, self)
         except (socket.error, http_client.HTTPException, ExpatError):
            if self.retryDelay and retriesLeft:
               time.sleep(self.retryDelay)
            retriesLeft -= 1
            continue

         if status == 200:
            # Normal return from the server, return the object to the caller.
            return obj

         # An exceptional return from the server
         if isinstance(obj, self.SESSION_EXCEPTIONS):
            # Our session might've timed out, change our state and retry.
            self._SetStateUnauthenticated()
         else:
            # It's an exception from the method that was called, send it up.
            raise obj

      # Raise any socket/httplib errors caught above.
      raise SystemError()

   ## Retrieve a managed property
   #
   # @param self self
   # @param mo managed object
   # @param info property info
   def InvokeAccessor(self, mo, info):
      # This retry logic is replicated in InvokeMethod and the two copies need
      # to be in sync
      retriesLeft = self.retryCount
      while retriesLeft > 0:
         try:
            if self.state == self.STATE_UNAUTHENTICATED:
               self._CallLoginMethod()
            # Invoke the method
            obj = StubAdapterBase.InvokeAccessor(self, mo, info)
         except (socket.error, http_client.HTTPException, ExpatError):
            if self.retryDelay and retriesLeft:
               time.sleep(self.retryDelay)
            retriesLeft -= 1
            continue
         except Exception as e:
            if isinstance(e, self.SESSION_EXCEPTIONS):
               # Our session might've timed out, change our state and retry.
               self._SetStateUnauthenticated()
            else:
               raise e
         return obj
      # Raise any socket/httplib errors caught above.
      raise SystemError()

   ## Handle the login method call
   #
   #  This method calls the login method on the soap stub and changes the state
   #  to authenticated
   def _CallLoginMethod(self):
      try:
         self.lock.acquire()
         if self.state == self.STATE_UNAUTHENTICATED:
            self.loginMethod(self.soapStub)
            self.state = self.STATE_AUTHENTICATED
      finally:
         self.lock.release()

   ## Change the state to unauthenticated
   def _SetStateUnauthenticated(self):
      self.lock.acquire()
      if self.state == self.STATE_AUTHENTICATED:
         self.state = self.STATE_UNAUTHENTICATED
      self.lock.release()