Mini Shell
# Copyright 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.
import datetime
import weakref
import json
import base64
import botocore
import botocore.auth
from botocore.compat import six, OrderedDict
from botocore.awsrequest import create_request_object, prepare_request_dict
from botocore.exceptions import UnknownSignatureVersionError
from botocore.exceptions import UnknownClientMethodError
from botocore.exceptions import UnsupportedSignatureVersionError
from botocore.utils import fix_s3_host, datetime2timestamp
class RequestSigner(object):
"""
An object to sign requests before they go out over the wire using
one of the authentication mechanisms defined in ``auth.py``. This
class fires two events scoped to a service and operation name:
* choose-signer: Allows overriding the auth signer name.
* before-sign: Allows mutating the request before signing.
Together these events allow for customization of the request
signing pipeline, including overrides, request path manipulation,
and disabling signing per operation.
:type service_id: botocore.model.ServiceId
:param service_id: The service id for the service, e.g. ``S3``
:type region_name: string
:param region_name: Name of the service region, e.g. ``us-east-1``
:type signing_name: string
:param signing_name: Service signing name. This is usually the
same as the service name, but can differ. E.g.
``emr`` vs. ``elasticmapreduce``.
:type signature_version: string
:param signature_version: Signature name like ``v4``.
:type credentials: :py:class:`~botocore.credentials.Credentials`
:param credentials: User credentials with which to sign requests.
:type event_emitter: :py:class:`~botocore.hooks.BaseEventHooks`
:param event_emitter: Extension mechanism to fire events.
"""
def __init__(self, service_id, region_name, signing_name,
signature_version, credentials, event_emitter):
self._region_name = region_name
self._signing_name = signing_name
self._signature_version = signature_version
self._credentials = credentials
self._service_id = service_id
# We need weakref to prevent leaking memory in Python 2.6 on Linux 2.6
self._event_emitter = weakref.proxy(event_emitter)
@property
def region_name(self):
return self._region_name
@property
def signature_version(self):
return self._signature_version
@property
def signing_name(self):
return self._signing_name
def handler(self, operation_name=None, request=None, **kwargs):
# This is typically hooked up to the "request-created" event
# from a client's event emitter. When a new request is created
# this method is invoked to sign the request.
# Don't call this method directly.
return self.sign(operation_name, request)
def sign(self, operation_name, request, region_name=None,
signing_type='standard', expires_in=None, signing_name=None):
"""Sign a request before it goes out over the wire.
:type operation_name: string
:param operation_name: The name of the current operation, e.g.
``ListBuckets``.
:type request: AWSRequest
:param request: The request object to be sent over the wire.
:type region_name: str
:param region_name: The region to sign the request for.
:type signing_type: str
:param signing_type: The type of signing to perform. This can be one of
three possible values:
* 'standard' - This should be used for most requests.
* 'presign-url' - This should be used when pre-signing a request.
* 'presign-post' - This should be used when pre-signing an S3 post.
:type expires_in: int
:param expires_in: The number of seconds the presigned url is valid
for. This parameter is only valid for signing type 'presign-url'.
:type signing_name: str
:param signing_name: The name to use for the service when signing.
"""
explicit_region_name = region_name
if region_name is None:
region_name = self._region_name
if signing_name is None:
signing_name = self._signing_name
signature_version = self._choose_signer(
operation_name, signing_type, request.context)
# Allow mutating request before signing
self._event_emitter.emit(
'before-sign.{0}.{1}'.format(
self._service_id.hyphenize(), operation_name),
request=request, signing_name=signing_name,
region_name=self._region_name,
signature_version=signature_version, request_signer=self,
operation_name=operation_name
)
if signature_version != botocore.UNSIGNED:
kwargs = {
'signing_name': signing_name,
'region_name': region_name,
'signature_version': signature_version
}
if expires_in is not None:
kwargs['expires'] = expires_in
signing_context = request.context.get('signing', {})
if not explicit_region_name and signing_context.get('region'):
kwargs['region_name'] = signing_context['region']
if signing_context.get('signing_name'):
kwargs['signing_name'] = signing_context['signing_name']
try:
auth = self.get_auth_instance(**kwargs)
except UnknownSignatureVersionError as e:
if signing_type != 'standard':
raise UnsupportedSignatureVersionError(
signature_version=signature_version)
else:
raise e
auth.add_auth(request)
def _choose_signer(self, operation_name, signing_type, context):
"""
Allow setting the signature version via the choose-signer event.
A value of `botocore.UNSIGNED` means no signing will be performed.
:param operation_name: The operation to sign.
:param signing_type: The type of signing that the signer is to be used
for.
:return: The signature version to sign with.
"""
signing_type_suffix_map = {
'presign-post': '-presign-post',
'presign-url': '-query'
}
suffix = signing_type_suffix_map.get(signing_type, '')
signature_version = self._signature_version
if signature_version is not botocore.UNSIGNED and not \
signature_version.endswith(suffix):
signature_version += suffix
handler, response = self._event_emitter.emit_until_response(
'choose-signer.{0}.{1}'.format(
self._service_id.hyphenize(), operation_name),
signing_name=self._signing_name, region_name=self._region_name,
signature_version=signature_version, context=context)
if response is not None:
signature_version = response
# The suffix needs to be checked again in case we get an improper
# signature version from choose-signer.
if signature_version is not botocore.UNSIGNED and not \
signature_version.endswith(suffix):
signature_version += suffix
return signature_version
def get_auth_instance(self, signing_name, region_name,
signature_version=None, **kwargs):
"""
Get an auth instance which can be used to sign a request
using the given signature version.
:type signing_name: string
:param signing_name: Service signing name. This is usually the
same as the service name, but can differ. E.g.
``emr`` vs. ``elasticmapreduce``.
:type region_name: string
:param region_name: Name of the service region, e.g. ``us-east-1``
:type signature_version: string
:param signature_version: Signature name like ``v4``.
:rtype: :py:class:`~botocore.auth.BaseSigner`
:return: Auth instance to sign a request.
"""
if signature_version is None:
signature_version = self._signature_version
cls = botocore.auth.AUTH_TYPE_MAPS.get(signature_version)
if cls is None:
raise UnknownSignatureVersionError(
signature_version=signature_version)
# If there's no credentials provided (i.e credentials is None),
# then we'll pass a value of "None" over to the auth classes,
# which already handle the cases where no credentials have
# been provided.
frozen_credentials = None
if self._credentials is not None:
frozen_credentials = self._credentials.get_frozen_credentials()
kwargs['credentials'] = frozen_credentials
if cls.REQUIRES_REGION:
if self._region_name is None:
raise botocore.exceptions.NoRegionError()
kwargs['region_name'] = region_name
kwargs['service_name'] = signing_name
auth = cls(**kwargs)
return auth
# Alias get_auth for backwards compatibility.
get_auth = get_auth_instance
def generate_presigned_url(self, request_dict, operation_name,
expires_in=3600, region_name=None,
signing_name=None):
"""Generates a presigned url
:type request_dict: dict
:param request_dict: The prepared request dictionary returned by
``botocore.awsrequest.prepare_request_dict()``
:type operation_name: str
:param operation_name: The operation being signed.
:type expires_in: int
:param expires_in: The number of seconds the presigned url is valid
for. By default it expires in an hour (3600 seconds)
:type region_name: string
:param region_name: The region name to sign the presigned url.
:type signing_name: str
:param signing_name: The name to use for the service when signing.
:returns: The presigned url
"""
request = create_request_object(request_dict)
self.sign(operation_name, request, region_name,
'presign-url', expires_in, signing_name)
request.prepare()
return request.url
class CloudFrontSigner(object):
'''A signer to create a signed CloudFront URL.
First you create a cloudfront signer based on a normalized RSA signer::
import rsa
def rsa_signer(message):
private_key = open('private_key.pem', 'r').read()
return rsa.sign(
message,
rsa.PrivateKey.load_pkcs1(private_key.encode('utf8')),
'SHA-1') # CloudFront requires SHA-1 hash
cf_signer = CloudFrontSigner(key_id, rsa_signer)
To sign with a canned policy::
signed_url = cf_signer.generate_signed_url(
url, date_less_than=datetime(2015, 12, 1))
To sign with a custom policy::
signed_url = cf_signer.generate_signed_url(url, policy=my_policy)
'''
def __init__(self, key_id, rsa_signer):
"""Create a CloudFrontSigner.
:type key_id: str
:param key_id: The CloudFront Key Pair ID
:type rsa_signer: callable
:param rsa_signer: An RSA signer.
Its only input parameter will be the message to be signed,
and its output will be the signed content as a binary string.
The hash algorithm needed by CloudFront is SHA-1.
"""
self.key_id = key_id
self.rsa_signer = rsa_signer
def generate_presigned_url(self, url, date_less_than=None, policy=None):
"""Creates a signed CloudFront URL based on given parameters.
:type url: str
:param url: The URL of the protected object
:type date_less_than: datetime
:param date_less_than: The URL will expire after that date and time
:type policy: str
:param policy: The custom policy, possibly built by self.build_policy()
:rtype: str
:return: The signed URL.
"""
if (date_less_than is not None and policy is not None or
date_less_than is None and policy is None):
e = 'Need to provide either date_less_than or policy, but not both'
raise ValueError(e)
if date_less_than is not None:
# We still need to build a canned policy for signing purpose
policy = self.build_policy(url, date_less_than)
if isinstance(policy, six.text_type):
policy = policy.encode('utf8')
if date_less_than is not None:
params = ['Expires=%s' % int(datetime2timestamp(date_less_than))]
else:
params = ['Policy=%s' % self._url_b64encode(policy).decode('utf8')]
signature = self.rsa_signer(policy)
params.extend([
'Signature=%s' % self._url_b64encode(signature).decode('utf8'),
'Key-Pair-Id=%s' % self.key_id,
])
return self._build_url(url, params)
def _build_url(self, base_url, extra_params):
separator = '&' if '?' in base_url else '?'
return base_url + separator + '&'.join(extra_params)
def build_policy(self, resource, date_less_than,
date_greater_than=None, ip_address=None):
"""A helper to build policy.
:type resource: str
:param resource: The URL or the stream filename of the protected object
:type date_less_than: datetime
:param date_less_than: The URL will expire after the time has passed
:type date_greater_than: datetime
:param date_greater_than: The URL will not be valid until this time
:type ip_address: str
:param ip_address: Use 'x.x.x.x' for an IP, or 'x.x.x.x/x' for a subnet
:rtype: str
:return: The policy in a compact string.
"""
# Note:
# 1. Order in canned policy is significant. Special care has been taken
# to ensure the output will match the order defined by the document.
# There is also a test case to ensure that order.
# SEE: http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-creating-signed-url-canned-policy.html#private-content-canned-policy-creating-policy-statement
# 2. Albeit the order in custom policy is not required by CloudFront,
# we still use OrderedDict internally to ensure the result is stable
# and also matches canned policy requirement.
# SEE: http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-creating-signed-url-custom-policy.html
moment = int(datetime2timestamp(date_less_than))
condition = OrderedDict({"DateLessThan": {"AWS:EpochTime": moment}})
if ip_address:
if '/' not in ip_address:
ip_address += '/32'
condition["IpAddress"] = {"AWS:SourceIp": ip_address}
if date_greater_than:
moment = int(datetime2timestamp(date_greater_than))
condition["DateGreaterThan"] = {"AWS:EpochTime": moment}
ordered_payload = [('Resource', resource), ('Condition', condition)]
custom_policy = {"Statement": [OrderedDict(ordered_payload)]}
return json.dumps(custom_policy, separators=(',', ':'))
def _url_b64encode(self, data):
# Required by CloudFront. See also:
# http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/private-content-linux-openssl.html
return base64.b64encode(
data).replace(b'+', b'-').replace(b'=', b'_').replace(b'/', b'~')
def add_generate_db_auth_token(class_attributes, **kwargs):
class_attributes['generate_db_auth_token'] = generate_db_auth_token
def generate_db_auth_token(self, DBHostname, Port, DBUsername, Region=None):
"""Generates an auth token used to connect to a db with IAM credentials.
:type DBHostname: str
:param DBHostname: The hostname of the database to connect to.
:type Port: int
:param Port: The port number the database is listening on.
:type DBUsername: str
:param DBUsername: The username to log in as.
:type Region: str
:param Region: The region the database is in. If None, the client
region will be used.
:return: A presigned url which can be used as an auth token.
"""
region = Region
if region is None:
region = self.meta.region_name
params = {
'Action': 'connect',
'DBUser': DBUsername,
}
request_dict = {
'url_path': '/',
'query_string': '',
'headers': {},
'body': params,
'method': 'GET'
}
# RDS requires that the scheme not be set when sent over. This can cause
# issues when signing because the Python url parsing libraries follow
# RFC 1808 closely, which states that a netloc must be introduced by `//`.
# Otherwise the url is presumed to be relative, and thus the whole
# netloc would be treated as a path component. To work around this we
# introduce https here and remove it once we're done processing it.
scheme = 'https://'
endpoint_url = '%s%s:%s' % (scheme, DBHostname, Port)
prepare_request_dict(request_dict, endpoint_url)
presigned_url = self._request_signer.generate_presigned_url(
operation_name='connect', request_dict=request_dict,
region_name=region, expires_in=900, signing_name='rds-db'
)
return presigned_url[len(scheme):]
class S3PostPresigner(object):
def __init__(self, request_signer):
self._request_signer = request_signer
def generate_presigned_post(self, request_dict, fields=None,
conditions=None, expires_in=3600,
region_name=None):
"""Generates the url and the form fields used for a presigned s3 post
:type request_dict: dict
:param request_dict: The prepared request dictionary returned by
``botocore.awsrequest.prepare_request_dict()``
:type fields: dict
:param fields: A dictionary of prefilled form fields to build on top
of.
:type conditions: list
:param conditions: A list of conditions to include in the policy. Each
element can be either a list or a structure. For example:
[
{"acl": "public-read"},
{"bucket": "mybucket"},
["starts-with", "$key", "mykey"]
]
:type expires_in: int
:param expires_in: The number of seconds the presigned post is valid
for.
:type region_name: string
:param region_name: The region name to sign the presigned post to.
:rtype: dict
:returns: A dictionary with two elements: ``url`` and ``fields``.
Url is the url to post to. Fields is a dictionary filled with
the form fields and respective values to use when submitting the
post. For example:
{'url': 'https://mybucket.s3.amazonaws.com
'fields': {'acl': 'public-read',
'key': 'mykey',
'signature': 'mysignature',
'policy': 'mybase64 encoded policy'}
}
"""
if fields is None:
fields = {}
if conditions is None:
conditions = []
# Create the policy for the post.
policy = {}
# Create an expiration date for the policy
datetime_now = datetime.datetime.utcnow()
expire_date = datetime_now + datetime.timedelta(seconds=expires_in)
policy['expiration'] = expire_date.strftime(botocore.auth.ISO8601)
# Append all of the conditions that the user supplied.
policy['conditions'] = []
for condition in conditions:
policy['conditions'].append(condition)
# Store the policy and the fields in the request for signing
request = create_request_object(request_dict)
request.context['s3-presign-post-fields'] = fields
request.context['s3-presign-post-policy'] = policy
self._request_signer.sign(
'PutObject', request, region_name, 'presign-post')
# Return the url and the fields for th form to post.
return {'url': request.url, 'fields': fields}
def add_generate_presigned_url(class_attributes, **kwargs):
class_attributes['generate_presigned_url'] = generate_presigned_url
def generate_presigned_url(self, ClientMethod, Params=None, ExpiresIn=3600,
HttpMethod=None):
"""Generate a presigned url given a client, its method, and arguments
:type ClientMethod: string
:param ClientMethod: The client method to presign for
:type Params: dict
:param Params: The parameters normally passed to
``ClientMethod``.
:type ExpiresIn: int
:param ExpiresIn: The number of seconds the presigned url is valid
for. By default it expires in an hour (3600 seconds)
:type HttpMethod: string
:param HttpMethod: The http method to use on the generated url. By
default, the http method is whatever is used in the method's model.
:returns: The presigned url
"""
client_method = ClientMethod
params = Params
if params is None:
params = {}
expires_in = ExpiresIn
http_method = HttpMethod
context = {
'is_presign_request': True,
'use_global_endpoint': _should_use_global_endpoint(self),
}
request_signer = self._request_signer
serializer = self._serializer
try:
operation_name = self._PY_TO_OP_NAME[client_method]
except KeyError:
raise UnknownClientMethodError(method_name=client_method)
operation_model = self.meta.service_model.operation_model(
operation_name)
params = self._emit_api_params(params, operation_model, context)
# Create a request dict based on the params to serialize.
request_dict = serializer.serialize_to_request(
params, operation_model)
# Switch out the http method if user specified it.
if http_method is not None:
request_dict['method'] = http_method
# Prepare the request dict by including the client's endpoint url.
prepare_request_dict(
request_dict, endpoint_url=self.meta.endpoint_url, context=context)
# Generate the presigned url.
return request_signer.generate_presigned_url(
request_dict=request_dict, expires_in=expires_in,
operation_name=operation_name)
def add_generate_presigned_post(class_attributes, **kwargs):
class_attributes['generate_presigned_post'] = generate_presigned_post
def generate_presigned_post(self, Bucket, Key, Fields=None, Conditions=None,
ExpiresIn=3600):
"""Builds the url and the form fields used for a presigned s3 post
:type Bucket: string
:param Bucket: The name of the bucket to presign the post to. Note that
bucket related conditions should not be included in the
``conditions`` parameter.
:type Key: string
:param Key: Key name, optionally add ${filename} to the end to
attach the submitted filename. Note that key related conditions and
fields are filled out for you and should not be included in the
``Fields`` or ``Conditions`` parameter.
:type Fields: dict
:param Fields: A dictionary of prefilled form fields to build on top
of. Elements that may be included are acl, Cache-Control,
Content-Type, Content-Disposition, Content-Encoding, Expires,
success_action_redirect, redirect, success_action_status,
and x-amz-meta-.
Note that if a particular element is included in the fields
dictionary it will not be automatically added to the conditions
list. You must specify a condition for the element as well.
:type Conditions: list
:param Conditions: A list of conditions to include in the policy. Each
element can be either a list or a structure. For example:
[
{"acl": "public-read"},
["content-length-range", 2, 5],
["starts-with", "$success_action_redirect", ""]
]
Conditions that are included may pertain to acl,
content-length-range, Cache-Control, Content-Type,
Content-Disposition, Content-Encoding, Expires,
success_action_redirect, redirect, success_action_status,
and/or x-amz-meta-.
Note that if you include a condition, you must specify
the a valid value in the fields dictionary as well. A value will
not be added automatically to the fields dictionary based on the
conditions.
:type ExpiresIn: int
:param ExpiresIn: The number of seconds the presigned post
is valid for.
:rtype: dict
:returns: A dictionary with two elements: ``url`` and ``fields``.
Url is the url to post to. Fields is a dictionary filled with
the form fields and respective values to use when submitting the
post. For example:
{'url': 'https://mybucket.s3.amazonaws.com
'fields': {'acl': 'public-read',
'key': 'mykey',
'signature': 'mysignature',
'policy': 'mybase64 encoded policy'}
}
"""
bucket = Bucket
key = Key
fields = Fields
conditions = Conditions
expires_in = ExpiresIn
if fields is None:
fields = {}
else:
fields = fields.copy()
if conditions is None:
conditions = []
post_presigner = S3PostPresigner(self._request_signer)
serializer = self._serializer
# We choose the CreateBucket operation model because its url gets
# serialized to what a presign post requires.
operation_model = self.meta.service_model.operation_model(
'CreateBucket')
# Create a request dict based on the params to serialize.
request_dict = serializer.serialize_to_request(
{'Bucket': bucket}, operation_model)
# Prepare the request dict by including the client's endpoint url.
prepare_request_dict(
request_dict, endpoint_url=self.meta.endpoint_url,
context={
'is_presign_request': True,
'use_global_endpoint': _should_use_global_endpoint(self),
},
)
# Append that the bucket name to the list of conditions.
conditions.append({'bucket': bucket})
# If the key ends with filename, the only constraint that can be
# imposed is if it starts with the specified prefix.
if key.endswith('${filename}'):
conditions.append(["starts-with", '$key', key[:-len('${filename}')]])
else:
conditions.append({'key': key})
# Add the key to the fields.
fields['key'] = key
return post_presigner.generate_presigned_post(
request_dict=request_dict, fields=fields, conditions=conditions,
expires_in=expires_in)
def _should_use_global_endpoint(client):
if client.meta.partition != 'aws':
return False
s3_config = client.meta.config.s3
if s3_config:
if s3_config.get('use_dualstack_endpoint', False):
return False
if s3_config.get('us_east_1_regional_endpoint') == 'regional' and \
client.meta.config.region_name == 'us-east-1':
return False
return True
Zerion Mini Shell 1.0