text: # Copyright 2012-2014 Amazon.com, Inc. or its affiliates. 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. A copy of
  # the License is located at
  #
  # http://aws.amazon.com/apache2.0/
  #
  # or in the "license" file accompanying this file. This file 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.
  
  """Builtin event handlers.
  
  This module contains builtin handlers for events emitted by botocore.
  """
  
  import base64
  import logging
  import xml.etree.cElementTree
  import copy
  import re
  import warnings
  import uuid
  
  from botocore.compat import (
      unquote, json, six, unquote_str, ensure_bytes, get_md5,
      MD5_AVAILABLE, OrderedDict, urlsplit, urlunsplit, XMLParseError
  )
  from botocore.docs.utils import AutoPopulatedParam
  from botocore.docs.utils import HideParamFromOperations
  from botocore.docs.utils import AppendParamDocumentation
  from botocore.signers import add_generate_presigned_url
  from botocore.signers import add_generate_presigned_post
  from botocore.signers import add_generate_db_auth_token
  from botocore.exceptions import ParamValidationError
  from botocore.exceptions import AliasConflictParameterError
  from botocore.exceptions import UnsupportedTLSVersionWarning
  from botocore.exceptions import MissingServiceIdError
  from botocore.utils import percent_encode, SAFE_CHARS
  from botocore.utils import switch_host_with_param
  from botocore.utils import hyphenize_service_id
  from botocore.utils import conditionally_calculate_md5
  
  from botocore import retryhandler
  from botocore import utils
  from botocore import translate
  import botocore
  import botocore.auth
  
  
  logger = logging.getLogger(__name__)
  
  REGISTER_FIRST = object()
  REGISTER_LAST = object()
  # From the S3 docs:
  # The rules for bucket names in the US Standard region allow bucket names
  # to be as long as 255 characters, and bucket names can contain any
  # combination of uppercase letters, lowercase letters, numbers, periods
  # (.), hyphens (-), and underscores (_).
  VALID_BUCKET = re.compile(r'^[a-zA-Z0-9.\-_]{1,255}$')
  VALID_S3_ARN = re.compile(
      r'^arn:(aws).*:s3:[a-z\-0-9]+:[0-9]{12}:accesspoint[/:]'
      r'[a-zA-Z0-9\-]{1,63}$'
  )
  VERSION_ID_SUFFIX = re.compile(r'\?versionId=[^\s]+$')
  
  SERVICE_NAME_ALIASES = {
      'runtime.sagemaker': 'sagemaker-runtime'
  }
  
  
  def handle_service_name_alias(service_name, **kwargs):
      return SERVICE_NAME_ALIASES.get(service_name, service_name)
  
  
  def check_for_200_error(response, **kwargs):
      # From: http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectCOPY.html
      # There are two opportunities for a copy request to return an error. One
      # can occur when Amazon S3 receives the copy request and the other can
      # occur while Amazon S3 is copying the files. If the error occurs before
      # the copy operation starts, you receive a standard Amazon S3 error. If the
      # error occurs during the copy operation, the error response is embedded in
      # the 200 OK response. This means that a 200 OK response can contain either
      # a success or an error. Make sure to design your application to parse the
      # contents of the response and handle it appropriately.
      #
      # So this handler checks for this case.  Even though the server sends a
      # 200 response, conceptually this should be handled exactly like a
      # 500 response (with respect to raising exceptions, retries, etc.)
      # We're connected *before* all the other retry logic handlers, so as long
      # as we switch the error code to 500, we'll retry the error as expected.
      if response is None:
          # A None response can happen if an exception is raised while
          # trying to retrieve the response.  See Endpoint._get_response().
          return
      http_response, parsed = response
      if _looks_like_special_case_error(http_response):
          logger.debug("Error found for response with 200 status code, "
                       "errors: %s, changing status code to "
                       "500.", parsed)
          http_response.status_code = 500
  
  
  def _looks_like_special_case_error(http_response):
      if http_response.status_code == 200:
          try:
              parser = xml.etree.cElementTree.XMLParser(
                  target=xml.etree.cElementTree.TreeBuilder(),
                  encoding='utf-8')
              parser.feed(http_response.content)
              root = parser.close()
          except XMLParseError:
              # In cases of network disruptions, we may end up with a partial
              # streamed response from S3. We need to treat these cases as
              # 500 Service Errors and try again.
              return True
          if root.tag == 'Error':
              return True
      return False
  
  
  def set_operation_specific_signer(context, signing_name, **kwargs):
      """ Choose the operation-specific signer.
  
      Individual operations may have a different auth type than the service as a
      whole. This will most often manifest as operations that should not be
      authenticated at all, but can include other auth modes such as sigv4
      without body signing.
      """
      auth_type = context.get('auth_type')
  
      # Auth type will be None if the operation doesn't have a configured auth
      # type.
      if not auth_type:
          return
  
      # Auth type will be the string value 'none' if the operation should not
      # be signed at all.
      if auth_type == 'none':
          return botocore.UNSIGNED
  
      if auth_type.startswith('v4'):
          signature_version = 'v4'
          if signing_name == 's3':
              signature_version = 's3v4'
  
          # If the operation needs an unsigned body, we set additional context
          # allowing the signer to be aware of this.
          if auth_type == 'v4-unsigned-body':
              context['payload_signing_enabled'] = False
  
          return signature_version
  
  
  def decode_console_output(parsed, **kwargs):
      if 'Output' in parsed:
          try:
              # We're using 'replace' for errors because it is
              # possible that console output contains non string
              # chars we can't utf-8 decode.
              value = base64.b64decode(six.b(parsed['Output'])).decode(
                  'utf-8', 'replace')
              parsed['Output'] = value
          except (ValueError, TypeError, AttributeError):
              logger.debug('Error decoding base64', exc_info=True)
  
  
  def generate_idempotent_uuid(params, model, **kwargs):
      for name in model.idempotent_members:
          if name not in params:
              params[name] = str(uuid.uuid4())
              logger.debug("injecting idempotency token (%s) into param '%s'." %
                           (params[name], name))
  
  
  def decode_quoted_jsondoc(value):
      try:
          value = json.loads(unquote(value))
      except (ValueError, TypeError):
          logger.debug('Error loading quoted JSON', exc_info=True)
      return value
  
  
  def json_decode_template_body(parsed, **kwargs):
      if 'TemplateBody' in parsed:
          try:
              value = json.loads(
                  parsed['TemplateBody'], object_pairs_hook=OrderedDict)
              parsed['TemplateBody'] = value
          except (ValueError, TypeError):
              logger.debug('error loading JSON', exc_info=True)
  
  
  def validate_bucket_name(params, **kwargs):
      if 'Bucket' not in params:
          return
      bucket = params['Bucket']
      if not VALID_BUCKET.search(bucket) and not VALID_S3_ARN.search(bucket):
          error_msg = (
              'Invalid bucket name "%s": Bucket name must match '
              'the regex "%s" or be an ARN matching the regex "%s"' % (
                  bucket, VALID_BUCKET.pattern, VALID_S3_ARN.pattern))
          raise ParamValidationError(report=error_msg)
  
  
  def sse_md5(params, **kwargs):
      """
      S3 server-side encryption requires the encryption key to be sent to the
      server base64 encoded, as well as a base64-encoded MD5 hash of the
      encryption key. This handler does both if the MD5 has not been set by
      the caller.
      """
      _sse_md5(params, 'SSECustomer')
  
  
  def copy_source_sse_md5(params, **kwargs):
      """
      S3 server-side encryption requires the encryption key to be sent to the
      server base64 encoded, as well as a base64-encoded MD5 hash of the
      encryption key. This handler does both if the MD5 has not been set by
      the caller specifically if the parameter is for the copy-source sse-c key.
      """
      _sse_md5(params, 'CopySourceSSECustomer')
  
  
  def _sse_md5(params, sse_member_prefix='SSECustomer'):
      if not _needs_s3_sse_customization(params, sse_member_prefix):
          return
  
      sse_key_member = sse_member_prefix + 'Key'
      sse_md5_member = sse_member_prefix + 'KeyMD5'
      key_as_bytes = params[sse_key_member]
      if isinstance(key_as_bytes, six.text_type):
          key_as_bytes = key_as_bytes.encode('utf-8')
      key_md5_str = base64.b64encode(
          get_md5(key_as_bytes).digest()).decode('utf-8')
      key_b64_encoded = base64.b64encode(key_as_bytes).decode('utf-8')
      params[sse_key_member] = key_b64_encoded
      params[sse_md5_member] = key_md5_str
  
  
  def _needs_s3_sse_customization(params, sse_member_prefix):
      return (params.get(sse_member_prefix + 'Key') is not None and
              sse_member_prefix + 'KeyMD5' not in params)
  
  
  def disable_signing(**kwargs):
      """
      This handler disables request signing by setting the signer
      name to a special sentinel value.
      """
      return botocore.UNSIGNED
  
  
  def add_expect_header(model, params, **kwargs):
      if model.http.get('method', '') not in ['PUT', 'POST']:
          return
      if 'body' in params:
          body = params['body']
          if hasattr(body, 'read'):
              # Any file like object will use an expect 100-continue
              # header regardless of size.
              logger.debug("Adding expect 100 continue header to request.")
              params['headers']['Expect'] = '100-continue'
  
  
  class DeprecatedServiceDocumenter(object):
      def __init__(self, replacement_service_name):
          self._replacement_service_name = replacement_service_name
  
      def inject_deprecation_notice(self, section, event_name, **kwargs):
          section.style.start_important()
          section.write('This service client is deprecated. Please use ')
          section.style.ref(
              self._replacement_service_name,
              self._replacement_service_name,
          )
          section.write(' instead.')
          section.style.end_important()
  
  
  def document_copy_source_form(section, event_name, **kwargs):
      if 'request-example' in event_name:
          parent = section.get_section('structure-value')
          param_line = parent.get_section('CopySource')
          value_portion = param_line.get_section('member-value')
          value_portion.clear_text()
          value_portion.write("'string' or {'Bucket': 'string', "
                              "'Key': 'string', 'VersionId': 'string'}")
      elif 'request-params' in event_name:
          param_section = section.get_section('CopySource')
          type_section = param_section.get_section('param-type')
          type_section.clear_text()
          type_section.write(':type CopySource: str or dict')
          doc_section = param_section.get_section('param-documentation')
          doc_section.clear_text()
          doc_section.write(
              "The name of the source bucket, key name of the source object, "
              "and optional version ID of the source object.  You can either "
              "provide this value as a string or a dictionary.  The "
              "string form is {bucket}/{key} or "
              "{bucket}/{key}?versionId={versionId} if you want to copy a "
              "specific version.  You can also provide this value as a "
              "dictionary.  The dictionary format is recommended over "
              "the string format because it is more explicit.  The dictionary "
              "format is: {'Bucket': 'bucket', 'Key': 'key', 'VersionId': 'id'}."
              "  Note that the VersionId key is optional and may be omitted."
          )
  
  
  def handle_copy_source_param(params, **kwargs):
      """Convert CopySource param for CopyObject/UploadPartCopy.
  
      This handler will deal with two cases:
  
          * CopySource provided as a string.  We'll make a best effort
            to URL encode the key name as required.  This will require
            parsing the bucket and version id from the CopySource value
            and only encoding the key.
          * CopySource provided as a dict.  In this case we're
            explicitly given the Bucket, Key, and VersionId so we're
            able to encode the key and ensure this value is serialized
            and correctly sent to S3.
  
      """
      source = params.get('CopySource')
      if source is None:
          # The call will eventually fail but we'll let the
          # param validator take care of this.  It will
          # give a better error message.
          return
      if isinstance(source, six.string_types):
          params['CopySource'] = _quote_source_header(source)
      elif isinstance(source, dict):
          params['CopySource'] = _quote_source_header_from_dict(source)
  
  
  def _quote_source_header_from_dict(source_dict):
      try:
          bucket = source_dict['Bucket']
          key = percent_encode(source_dict['Key'], safe=SAFE_CHARS + '/')
          version_id = source_dict.get('VersionId')
      except KeyError as e:
          raise ParamValidationError(
              report='Missing required parameter: %s' % str(e))
      final = '%s/%s' % (bucket, key)
      if version_id is not None:
          final += '?versionId=%s' % version_id
      return final
  
  
  def _quote_source_header(value):
      result = VERSION_ID_SUFFIX.search(value)
      if result is None:
          return percent_encode(value, safe=SAFE_CHARS + '/')
      else:
          first, version_id = value[:result.start()], value[result.start():]
          return percent_encode(first, safe=SAFE_CHARS + '/') + version_id
  
  
  def _get_cross_region_presigned_url(request_signer, request_dict, model,
                                      source_region, destination_region):
      # The better way to do this is to actually get the
      # endpoint_resolver and get the endpoint_url given the
      # source region.  In this specific case, we know that
      # we can safely replace the dest region with the source
      # region because of the supported EC2 regions, but in
      # general this is not a safe assumption to make.
      # I think eventually we should try to plumb through something
      # that allows us to resolve endpoints from regions.
      request_dict_copy = copy.deepcopy(request_dict)
      request_dict_copy['body']['DestinationRegion'] = destination_region
      request_dict_copy['url'] = request_dict['url'].replace(
          destination_region, source_region)
      request_dict_copy['method'] = 'GET'
      request_dict_copy['headers'] = {}
      return request_signer.generate_presigned_url(
          request_dict_copy, region_name=source_region,
          operation_name=model.name)
  
  
  def _get_presigned_url_source_and_destination_regions(request_signer, params):
      # Gets the source and destination regions to be used
      destination_region = request_signer._region_name
      source_region = params.get('SourceRegion')
      return source_region, destination_region
  
  
  def inject_presigned_url_ec2(params, request_signer, model, **kwargs):
      # The customer can still provide this, so we should pass if they do.
      if 'PresignedUrl' in params['body']:
          return
      src, dest = _get_presigned_url_source_and_destination_regions(
          request_signer, params['body'])
      url = _get_cross_region_presigned_url(
          request_signer, params, model, src, dest)
      params['body']['PresignedUrl'] = url
      # EC2 Requires that the destination region be sent over the wire in
      # addition to the source region.
      params['body']['DestinationRegion'] = dest
  
  
  def inject_presigned_url_rds(params, request_signer, model, **kwargs):
      # SourceRegion is not required for RDS operations, so it's possible that
      # it isn't set. In that case it's probably a local copy so we don't need
      # to do anything else.
      if 'SourceRegion' not in params['body']:
          return
  
      src, dest = _get_presigned_url_source_and_destination_regions(
          request_signer, params['body'])
  
      # Since SourceRegion isn't actually modeled for RDS, it needs to be
      # removed from the request params before we send the actual request.
      del params['body']['SourceRegion']
  
      if 'PreSignedUrl' in params['body']:
          return
  
      url = _get_cross_region_presigned_url(
          request_signer, params, model, src, dest)
      params['body']['PreSignedUrl'] = url
  
  
  def json_decode_policies(parsed, model, **kwargs):
      # Any time an IAM operation returns a policy document
      # it is a string that is json that has been urlencoded,
      # i.e urlencode(json.dumps(policy_document)).
      # To give users something more useful, we will urldecode
      # this value and json.loads() the result so that they have
      # the policy document as a dictionary.
      output_shape = model.output_shape
      if output_shape is not None:
          _decode_policy_types(parsed, model.output_shape)
  
  
  def _decode_policy_types(parsed, shape):
      # IAM consistently uses the policyDocumentType shape to indicate
      # strings that have policy documents.
      shape_name = 'policyDocumentType'
      if shape.type_name == 'structure':
          for member_name, member_shape in shape.members.items():
              if member_shape.type_name == 'string' and \
                      member_shape.name == shape_name and \
                      member_name in parsed:
                  parsed[member_name] = decode_quoted_jsondoc(
                      parsed[member_name])
              elif member_name in parsed:
                  _decode_policy_types(parsed[member_name], member_shape)
      if shape.type_name == 'list':
          shape_member = shape.member
          for item in parsed:
              _decode_policy_types(item, shape_member)
  
  
  def parse_get_bucket_location(parsed, http_response, **kwargs):
      # s3.GetBucketLocation cannot be modeled properly.  To
      # account for this we just manually parse the XML document.
      # The "parsed" passed in only has the ResponseMetadata
      # filled out.  This handler will fill in the LocationConstraint
      # value.
      if http_response.raw is None:
          return
      response_body = http_response.content
      parser = xml.etree.cElementTree.XMLParser(
          target=xml.etree.cElementTree.TreeBuilder(),
          encoding='utf-8')
      parser.feed(response_body)
      root = parser.close()
      region = root.text
      parsed['LocationConstraint'] = region
  
  
  def base64_encode_user_data(params, **kwargs):
      if 'UserData' in params:
          if isinstance(params['UserData'], six.text_type):
              # Encode it to bytes if it is text.
              params['UserData'] = params['UserData'].encode('utf-8')
          params['UserData'] = base64.b64encode(
              params['UserData']).decode('utf-8')
  
  
  def document_base64_encoding(param):
      description = ('**This value will be base64 encoded automatically. Do '
                     'not base64 encode this value prior to performing the '
                     'operation.**')
      append = AppendParamDocumentation(param, description)
      return append.append_documentation
  
  
  def validate_ascii_metadata(params, **kwargs):
      """Verify S3 Metadata only contains ascii characters.
  
      From: http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingMetadata.html
  
      "Amazon S3 stores user-defined metadata in lowercase. Each name, value pair
      must conform to US-ASCII when using REST and UTF-8 when using SOAP or
      browser-based uploads via POST."
  
      """
      metadata = params.get('Metadata')
      if not metadata or not isinstance(metadata, dict):
          # We have to at least type check the metadata as a dict type
          # because this handler is called before param validation.
          # We'll go ahead and return because the param validator will
          # give a descriptive error message for us.
          # We might need a post-param validation event.
          return
      for key, value in metadata.items():
          try:
              key.encode('ascii')
              value.encode('ascii')
          except UnicodeEncodeError as e:
              error_msg = (
                  'Non ascii characters found in S3 metadata '
                  'for key "%s", value: "%s".  \nS3 metadata can only '
                  'contain ASCII characters. ' % (key, value)
              )
              raise ParamValidationError(
                  report=error_msg)
  
  
  def fix_route53_ids(params, model, **kwargs):
      """
      Check for and split apart Route53 resource IDs, setting
      only the last piece. This allows the output of one operation
      (e.g. ``'foo/1234'``) to be used as input in another
      operation (e.g. it expects just ``'1234'``).
      """
      input_shape = model.input_shape
      if not input_shape or not hasattr(input_shape, 'members'):
          return
  
      members = [name for (name, shape) in input_shape.members.items()
                 if shape.name in ['ResourceId', 'DelegationSetId']]
  
      for name in members:
          if name in params:
              orig_value = params[name]
              params[name] = orig_value.split('/')[-1]
              logger.debug('%s %s -> %s', name, orig_value, params[name])
  
  
  def inject_account_id(params, **kwargs):
      if params.get('accountId') is None:
          # Glacier requires accountId, but allows you
          # to specify '-' for the current owners account.
          # We add this default value if the user does not
          # provide the accountId as a convenience.
          params['accountId'] = '-'
  
  
  def add_glacier_version(model, params, **kwargs):
      request_dict = params
      request_dict['headers']['x-amz-glacier-version'] = model.metadata[
          'apiVersion']
  
  
  def add_accept_header(model, params, **kwargs):
      if params['headers'].get('Accept', None) is None:
          request_dict = params
          request_dict['headers']['Accept'] = 'application/json'
  
  
  def add_glacier_checksums(params, **kwargs):
      """Add glacier checksums to the http request.
  
      This will add two headers to the http request:
  
          * x-amz-content-sha256
          * x-amz-sha256-tree-hash
  
      These values will only be added if they are not present
      in the HTTP request.
  
      """
      request_dict = params
      headers = request_dict['headers']
      body = request_dict['body']
      if isinstance(body, six.binary_type):
          # If the user provided a bytes type instead of a file
          # like object, we're temporarily create a BytesIO object
          # so we can use the util functions to calculate the
          # checksums which assume file like objects.  Note that
          # we're not actually changing the body in the request_dict.
          body = six.BytesIO(body)
      starting_position = body.tell()
      if 'x-amz-content-sha256' not in headers:
          headers['x-amz-content-sha256'] = utils.calculate_sha256(
              body, as_hex=True)
      body.seek(starting_position)
      if 'x-amz-sha256-tree-hash' not in headers:
          headers['x-amz-sha256-tree-hash'] = utils.calculate_tree_hash(body)
      body.seek(starting_position)
  
  
  def document_glacier_tree_hash_checksum():
      doc = '''
          This is a required field.
  
          Ideally you will want to compute this value with checksums from
          previous uploaded parts, using the algorithm described in
          `Glacier documentation <http://docs.aws.amazon.com/amazonglacier/latest/dev/checksum-calculations.html>`_.
  
          But if you prefer, you can also use botocore.utils.calculate_tree_hash()
          to compute it from raw file by::
  
              checksum = calculate_tree_hash(open('your_file.txt', 'rb'))
  
          '''
      return AppendParamDocumentation('checksum', doc).append_documentation
  
  
  def document_cloudformation_get_template_return_type(section, event_name, **kwargs):
      if 'response-params' in event_name:
          template_body_section = section.get_section('TemplateBody')
          type_section = template_body_section.get_section('param-type')
          type_section.clear_text()
          type_section.write('(*dict*) --')
      elif 'response-example' in event_name:
          parent = section.get_section('structure-value')
          param_line = parent.get_section('TemplateBody')
          value_portion = param_line.get_section('member-value')
          value_portion.clear_text()
          value_portion.write('{}')
  
  
  def switch_host_machinelearning(request, **kwargs):
      switch_host_with_param(request, 'PredictEndpoint')
  
  
  def check_openssl_supports_tls_version_1_2(**kwargs):
      import ssl
      try:
          openssl_version_tuple = ssl.OPENSSL_VERSION_INFO
          if openssl_version_tuple < (1, 0, 1):
              warnings.warn(
                  'Currently installed openssl version: %s does not '
                  'support TLS 1.2, which is required for use of iot-data. '
                  'Please use python installed with openssl version 1.0.1 or '
                  'higher.' % (ssl.OPENSSL_VERSION),
                  UnsupportedTLSVersionWarning
              )
      # We cannot check the openssl version on python2.6, so we should just
      # pass on this conveniency check.
      except AttributeError:
          pass
  
  
  def change_get_to_post(request, **kwargs):
      # This is useful when we need to change a potentially large GET request
      # into a POST with x-www-form-urlencoded encoding.
      if request.method == 'GET' and '?' in request.url:
          request.headers['Content-Type'] = 'application/x-www-form-urlencoded'
          request.method = 'POST'
          request.url, request.data = request.url.split('?', 1)
  
  
  def set_list_objects_encoding_type_url(params, context, **kwargs):
      if 'EncodingType' not in params:
          # We set this context so that we know it wasn't the customer that
          # requested the encoding.
          context['encoding_type_auto_set'] = True
          params['EncodingType'] = 'url'
  
  
  def decode_list_object(parsed, context, **kwargs):
      # This is needed because we are passing url as the encoding type. Since the
      # paginator is based on the key, we need to handle it before it can be
      # round tripped.
      #
      # From the documentation: If you specify encoding-type request parameter,
      # Amazon S3 includes this element in the response, and returns encoded key
      # name values in the following response elements:
      # Delimiter, Marker, Prefix, NextMarker, Key.
      _decode_list_object(
          top_level_keys=['Delimiter', 'Marker', 'NextMarker'],
          nested_keys=[('Contents', 'Key'), ('CommonPrefixes', 'Prefix')],
          parsed=parsed,
          context=context
      )
  
  
  def decode_list_object_v2(parsed, context, **kwargs):
      # From the documentation: If you specify encoding-type request parameter,
      # Amazon S3 includes this element in the response, and returns encoded key
      # name values in the following response elements:
      # Delimiter, Prefix, ContinuationToken, Key, and StartAfter.
      _decode_list_object(
          top_level_keys=['Delimiter', 'Prefix', 'StartAfter'],
          nested_keys=[('Contents', 'Key'), ('CommonPrefixes', 'Prefix')],
          parsed=parsed,
          context=context
      )
  
  
  def decode_list_object_versions(parsed, context, **kwargs):
      # From the documentation: If you specify encoding-type request parameter,
      # Amazon S3 includes this element in the response, and returns encoded key
      # name values in the following response elements:
      # KeyMarker, NextKeyMarker, Prefix, Key, and Delimiter.
      _decode_list_object(
          top_level_keys=[
              'KeyMarker',
              'NextKeyMarker',
              'Prefix',
              'Delimiter',
          ],
          nested_keys=[
              ('Versions', 'Key'),
              ('DeleteMarkers', 'Key'),
              ('CommonPrefixes', 'Prefix'),
          ],
          parsed=parsed,
          context=context
      )
  
  
  def _decode_list_object(top_level_keys, nested_keys, parsed, context):
      if parsed.get('EncodingType') == 'url' and \
                      context.get('encoding_type_auto_set'):
          # URL decode top-level keys in the response if present.
          for key in top_level_keys:
              if key in parsed:
                  parsed[key] = unquote_str(parsed[key])
          # URL decode nested keys from the response if present.
          for (top_key, child_key) in nested_keys:
              if top_key in parsed:
                  for member in parsed[top_key]:
                      member[child_key] = unquote_str(member[child_key])
  
  
  def convert_body_to_file_like_object(params, **kwargs):
      if 'Body' in params:
          if isinstance(params['Body'], six.string_types):
              params['Body'] = six.BytesIO(ensure_bytes(params['Body']))
          elif isinstance(params['Body'], six.binary_type):
              params['Body'] = six.BytesIO(params['Body'])
  
  
  def _add_parameter_aliases(handler_list):
      # Mapping of original parameter to parameter alias.
      # The key is <service>.<operation>.parameter
      # The first part of the key is used for event registration.
      # The last part is the original parameter name and the value is the
      # alias to expose in documentation.
      aliases = {
          'ec2.*.Filter': 'Filters',
          'logs.CreateExportTask.from': 'fromTime',
          'cloudsearchdomain.Search.return': 'returnFields'
      }
  
      for original, new_name in aliases.items():
          event_portion, original_name = original.rsplit('.', 1)
          parameter_alias = ParameterAlias(original_name, new_name)
  
          # Add the handlers to the list of handlers.
          # One handler is to handle when users provide the alias.
          # The other handler is to update the documentation to show only
          # the alias.
          parameter_build_event_handler_tuple = (
              'before-parameter-build.' + event_portion,
              parameter_alias.alias_parameter_in_call,
              REGISTER_FIRST
          )
          docs_event_handler_tuple = (
              'docs.*.' + event_portion + '.complete-section',
              parameter_alias.alias_parameter_in_documentation)
          handler_list.append(parameter_build_event_handler_tuple)
          handler_list.append(docs_event_handler_tuple)
  
  
  class ParameterAlias(object):
      def __init__(self, original_name, alias_name):
          self._original_name = original_name
          self._alias_name = alias_name
  
      def alias_parameter_in_call(self, params, model, **kwargs):
          if model.input_shape:
              # Only consider accepting the alias if it is modeled in the
              # input shape.
              if self._original_name in model.input_shape.members:
                  if self._alias_name in params:
                      if self._original_name in params:
                          raise AliasConflictParameterError(
                              original=self._original_name,
                              alias=self._alias_name,
                              operation=model.name
                          )
                      # Remove the alias parameter value and use the old name
                      # instead.
                      params[self._original_name] = params.pop(self._alias_name)
  
      def alias_parameter_in_documentation(self, event_name, section, **kwargs):
          if event_name.startswith('docs.request-params'):
              if self._original_name not in section.available_sections:
                  return
              # Replace the name for parameter type
              param_section = section.get_section(self._original_name)
              param_type_section = param_section.get_section('param-type')
              self._replace_content(param_type_section)
  
              # Replace the name for the parameter description
              param_name_section = param_section.get_section('param-name')
              self._replace_content(param_name_section)
          elif event_name.startswith('docs.request-example'):
              section = section.get_section('structure-value')
              if self._original_name not in section.available_sections:
                  return
              # Replace the name for the example
              param_section = section.get_section(self._original_name)
              self._replace_content(param_section)
  
      def _replace_content(self, section):
          content = section.getvalue().decode('utf-8')
          updated_content = content.replace(
              self._original_name, self._alias_name)
          section.clear_text()
          section.write(updated_content)
  
  
  class ClientMethodAlias(object):
      def __init__(self, actual_name):
          """ Aliases a non-extant method to an existing method.
  
          :param actual_name: The name of the method that actually exists on
              the client.
          """
          self._actual = actual_name
  
      def __call__(self, client, **kwargs):
          return getattr(client, self._actual)
  
  
  class HeaderToHostHoister(object):
      """Takes a header and moves it to the front of the hoststring.
      """
      _VALID_HOSTNAME = re.compile(r'(?!-)[a-z\d-]{1,63}(?<!-)$', re.IGNORECASE)
  
      def __init__(self, header_name):
          self._header_name = header_name
  
      def hoist(self, params, **kwargs):
          """Hoist a header to the hostname.
  
          Hoist a header to the beginning of the hostname with a suffix "." after
          it. The original header should be removed from the header map. This
          method is intended to be used as a target for the before-call event.
          """
          if self._header_name not in params['headers']:
              return
          header_value = params['headers'][self._header_name]
          self._ensure_header_is_valid_host(header_value)
          original_url = params['url']
          new_url = self._prepend_to_host(original_url, header_value)
          params['url'] = new_url
  
      def _ensure_header_is_valid_host(self, header):
          match = self._VALID_HOSTNAME.match(header)
          if not match:
              raise ParamValidationError(report=(
                  'Hostnames must contain only - and alphanumeric characters, '
                  'and between 1 and 63 characters long.'
              ))
  
      def _prepend_to_host(self, url, prefix):
          url_components = urlsplit(url)
          parts = url_components.netloc.split('.')
          parts = [prefix] + parts
          new_netloc = '.'.join(parts)
          new_components = (
              url_components.scheme,
              new_netloc,
              url_components.path,
              url_components.query,
              ''
          )
          new_url = urlunsplit(new_components)
          return new_url
  
  
  def inject_api_version_header_if_needed(model, params, **kwargs):
      if not model.is_endpoint_discovery_operation:
          return
      params['headers']['x-amz-api-version'] = model.service_model.api_version
  
  
  # This is a list of (event_name, handler).
  # When a Session is created, everything in this list will be
  # automatically registered with that Session.
  
  BUILTIN_HANDLERS = [
      ('choose-service-name', handle_service_name_alias),
      ('getattr.mturk.list_hi_ts_for_qualification_type',
       ClientMethodAlias('list_hits_for_qualification_type')),
      ('before-parameter-build.s3.UploadPart',
       convert_body_to_file_like_object, REGISTER_LAST),
      ('before-parameter-build.s3.PutObject',
       convert_body_to_file_like_object, REGISTER_LAST),
      ('creating-client-class', add_generate_presigned_url),
      ('creating-client-class.s3', add_generate_presigned_post),
      ('creating-client-class.iot-data', check_openssl_supports_tls_version_1_2),
      ('after-call.iam', json_decode_policies),
  
      ('after-call.ec2.GetConsoleOutput', decode_console_output),
      ('after-call.cloudformation.GetTemplate', json_decode_template_body),
      ('after-call.s3.GetBucketLocation', parse_get_bucket_location),
  
      ('before-parameter-build', generate_idempotent_uuid),
  
      ('before-parameter-build.s3', validate_bucket_name),
  
      ('before-parameter-build.s3.ListObjects',
       set_list_objects_encoding_type_url),
      ('before-parameter-build.s3.ListObjectsV2',
       set_list_objects_encoding_type_url),
      ('before-parameter-build.s3.ListObjectVersions',
       set_list_objects_encoding_type_url),
      ('before-parameter-build.s3.CopyObject',
       handle_copy_source_param),
      ('before-parameter-build.s3.UploadPartCopy',
       handle_copy_source_param),
      ('before-parameter-build.s3.CopyObject', validate_ascii_metadata),
      ('before-parameter-build.s3.PutObject', validate_ascii_metadata),
      ('before-parameter-build.s3.CreateMultipartUpload',
       validate_ascii_metadata),
      ('docs.*.s3.CopyObject.complete-section', document_copy_source_form),
      ('docs.*.s3.UploadPartCopy.complete-section', document_copy_source_form),
  
      ('before-call.s3', add_expect_header),
      ('before-call.glacier', add_glacier_version),
      ('before-call.apigateway', add_accept_header),
      ('before-call.s3.PutObject', conditionally_calculate_md5),
      ('before-call.s3.UploadPart', conditionally_calculate_md5),
      ('before-call.glacier.UploadArchive', add_glacier_checksums),
      ('before-call.glacier.UploadMultipartPart', add_glacier_checksums),
      ('before-call.ec2.CopySnapshot', inject_presigned_url_ec2),
      ('request-created.machinelearning.Predict', switch_host_machinelearning),
      ('needs-retry.s3.UploadPartCopy', check_for_200_error, REGISTER_FIRST),
      ('needs-retry.s3.CopyObject', check_for_200_error, REGISTER_FIRST),
      ('needs-retry.s3.CompleteMultipartUpload', check_for_200_error,
       REGISTER_FIRST),
      ('choose-signer.cognito-identity.GetId', disable_signing),
      ('choose-signer.cognito-identity.GetOpenIdToken', disable_signing),
      ('choose-signer.cognito-identity.UnlinkIdentity', disable_signing),
      ('choose-signer.cognito-identity.GetCredentialsForIdentity',
          disable_signing),
      ('choose-signer.sts.AssumeRoleWithSAML', disable_signing),
      ('choose-signer.sts.AssumeRoleWithWebIdentity', disable_signing),
      ('choose-signer', set_operation_specific_signer),
      ('before-parameter-build.s3.HeadObject', sse_md5),
      ('before-parameter-build.s3.GetObject', sse_md5),
      ('before-parameter-build.s3.PutObject', sse_md5),
      ('before-parameter-build.s3.CopyObject', sse_md5),
      ('before-parameter-build.s3.CopyObject', copy_source_sse_md5),
      ('before-parameter-build.s3.CreateMultipartUpload', sse_md5),
      ('before-parameter-build.s3.UploadPart', sse_md5),
      ('before-parameter-build.s3.UploadPartCopy', sse_md5),
      ('before-parameter-build.s3.UploadPartCopy', copy_source_sse_md5),
      ('before-parameter-build.ec2.RunInstances', base64_encode_user_data),
      ('before-parameter-build.autoscaling.CreateLaunchConfiguration',
       base64_encode_user_data),
      ('before-parameter-build.route53', fix_route53_ids),
      ('before-parameter-build.glacier', inject_account_id),
      ('after-call.s3.ListObjects', decode_list_object),
      ('after-call.s3.ListObjectsV2', decode_list_object_v2),
      ('after-call.s3.ListObjectVersions', decode_list_object_versions),
  
      # Cloudsearchdomain search operation will be sent by HTTP POST
      ('request-created.cloudsearchdomain.Search',
       change_get_to_post),
      # Glacier documentation customizations
      ('docs.*.glacier.*.complete-section',
       AutoPopulatedParam('accountId', 'Note: this parameter is set to "-" by'
                          'default if no value is not specified.')
       .document_auto_populated_param),
      ('docs.*.glacier.UploadArchive.complete-section',
       AutoPopulatedParam('checksum').document_auto_populated_param),
      ('docs.*.glacier.UploadMultipartPart.complete-section',
       AutoPopulatedParam('checksum').document_auto_populated_param),
      ('docs.request-params.glacier.CompleteMultipartUpload.complete-section',
       document_glacier_tree_hash_checksum()),
      # Cloudformation documentation customizations
      ('docs.*.cloudformation.GetTemplate.complete-section',
       document_cloudformation_get_template_return_type),
  
      # UserData base64 encoding documentation customizations
      ('docs.*.ec2.RunInstances.complete-section',
       document_base64_encoding('UserData')),
      ('docs.*.autoscaling.CreateLaunchConfiguration.complete-section',
       document_base64_encoding('UserData')),
  
      # EC2 CopySnapshot documentation customizations
      ('docs.*.ec2.CopySnapshot.complete-section',
       AutoPopulatedParam('PresignedUrl').document_auto_populated_param),
      ('docs.*.ec2.CopySnapshot.complete-section',
       AutoPopulatedParam('DestinationRegion').document_auto_populated_param),
      # S3 SSE documentation modifications
      ('docs.*.s3.*.complete-section',
       AutoPopulatedParam('SSECustomerKeyMD5').document_auto_populated_param),
      # S3 SSE Copy Source documentation modifications
      ('docs.*.s3.*.complete-section',
       AutoPopulatedParam(
          'CopySourceSSECustomerKeyMD5').document_auto_populated_param),
      # Add base64 information to Lambda
      ('docs.*.lambda.UpdateFunctionCode.complete-section',
       document_base64_encoding('ZipFile')),
      # The following S3 operations cannot actually accept a ContentMD5
      ('docs.*.s3.*.complete-section',
       HideParamFromOperations(
           's3', 'ContentMD5',
           ['DeleteObjects', 'PutBucketAcl', 'PutBucketCors',
            'PutBucketLifecycle', 'PutBucketLogging', 'PutBucketNotification',
            'PutBucketPolicy', 'PutBucketReplication', 'PutBucketRequestPayment',
            'PutBucketTagging', 'PutBucketVersioning', 'PutBucketWebsite',
            'PutObjectAcl']).hide_param),
  
      #############
      # RDS
      #############
      ('creating-client-class.rds', add_generate_db_auth_token),
  
      ('before-call.rds.CopyDBClusterSnapshot',
       inject_presigned_url_rds),
      ('before-call.rds.CreateDBCluster',
       inject_presigned_url_rds),
      ('before-call.rds.CopyDBSnapshot',
       inject_presigned_url_rds),
      ('before-call.rds.CreateDBInstanceReadReplica',
       inject_presigned_url_rds),
  
      # RDS PresignedUrl documentation customizations
      ('docs.*.rds.CopyDBClusterSnapshot.complete-section',
       AutoPopulatedParam('PreSignedUrl').document_auto_populated_param),
      ('docs.*.rds.CreateDBCluster.complete-section',
       AutoPopulatedParam('PreSignedUrl').document_auto_populated_param),
      ('docs.*.rds.CopyDBSnapshot.complete-section',
       AutoPopulatedParam('PreSignedUrl').document_auto_populated_param),
      ('docs.*.rds.CreateDBInstanceReadReplica.complete-section',
       AutoPopulatedParam('PreSignedUrl').document_auto_populated_param),
  
      #############
      # Neptune
      #############
      ('before-call.neptune.CopyDBClusterSnapshot',
       inject_presigned_url_rds),
      ('before-call.neptune.CreateDBCluster',
       inject_presigned_url_rds),
  
      # Neptune PresignedUrl documentation customizations
      ('docs.*.neptune.CopyDBClusterSnapshot.complete-section',
       AutoPopulatedParam('PreSignedUrl').document_auto_populated_param),
      ('docs.*.neptune.CreateDBCluster.complete-section',
       AutoPopulatedParam('PreSignedUrl').document_auto_populated_param),
  
      #############
      # DocDB
      #############
      ('before-call.docdb.CopyDBClusterSnapshot',
       inject_presigned_url_rds),
  
      # DocDB PresignedUrl documentation customizations
      ('docs.*.docdb.CopyDBClusterSnapshot.complete-section',
       AutoPopulatedParam('PreSignedUrl').document_auto_populated_param),
  
      #############
      # S3 Control
      #############
      ('before-call.s3-control.*',
       HeaderToHostHoister('x-amz-account-id').hoist),
  
      ###########
      # SMS Voice
       ##########
      ('docs.title.sms-voice',
       DeprecatedServiceDocumenter(
           'pinpoint-sms-voice').inject_deprecation_notice),
      ('before-call', inject_api_version_header_if_needed),
  
  ]
  _add_parameter_aliases(BUILTIN_HANDLERS)
  