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# -*- coding: utf-8 -*-
# MinIO Python Library for Amazon S3 Compatible Cloud Storage,
# (C) 2015-2020 MinIO, Inc.
#
# 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.
"""
minio.signer
~~~~~~~~~~~~~~~
This module implements all helpers for AWS Signature version '4' support.
:copyright: (c) 2015 by MinIO, Inc.
:license: Apache 2.0, see LICENSE for more details.
"""
import hashlib
import hmac
import re
from collections import OrderedDict
from urllib.parse import SplitResult
from . import time
from .helpers import queryencode, sha256_hash
SIGN_V4_ALGORITHM = 'AWS4-HMAC-SHA256'
_MULTI_SPACE_REGEX = re.compile(r"( +)")
def _hmac_hash(key, data, hexdigest=False):
"""Return HMacSHA256 digest of given key and data."""
hasher = hmac.new(key, data, hashlib.sha256)
return hasher.hexdigest() if hexdigest else hasher.digest()
def _get_scope(date, region, service_name):
"""Get scope string."""
return f"{time.to_signer_date(date)}/{region}/{service_name}/aws4_request"
def _get_canonical_headers(headers):
"""Get canonical headers."""
canonical_headers = {}
for key, values in headers.items():
key = key.lower()
if key not in (
"authorization",
"user-agent",
):
values = values if isinstance(values, (list, tuple)) else [values]
canonical_headers[key] = ",".join([
_MULTI_SPACE_REGEX.sub(" ", value) for value in values
])
canonical_headers = OrderedDict(sorted(canonical_headers.items()))
signed_headers = ";".join(canonical_headers.keys())
canonical_headers = "\n".join(
[f"{key}:{value}" for key, value in canonical_headers.items()],
)
return canonical_headers, signed_headers
def _get_canonical_query_string(query):
"""Get canonical query string."""
query = query or ""
return "&".join(
[
"=".join(pair) for pair in sorted(
[params.split("=") for params in query.split("&")],
)
],
)
def _get_canonical_request_hash(method, url, headers, content_sha256):
"""Get canonical request hash."""
canonical_headers, signed_headers = _get_canonical_headers(headers)
canonical_query_string = _get_canonical_query_string(url.query)
# CanonicalRequest =
# HTTPRequestMethod + '\n' +
# CanonicalURI + '\n' +
# CanonicalQueryString + '\n' +
# CanonicalHeaders + '\n\n' +
# SignedHeaders + '\n' +
# HexEncode(Hash(RequestPayload))
canonical_request = (
f"{method}\n"
f"{url.path or '/'}\n"
f"{canonical_query_string}\n"
f"{canonical_headers}\n\n"
f"{signed_headers}\n"
f"{content_sha256}"
)
return sha256_hash(canonical_request), signed_headers
def _get_string_to_sign(date, scope, canonical_request_hash):
"""Get string-to-sign."""
return (
f"AWS4-HMAC-SHA256\n{time.to_amz_date(date)}\n{scope}\n"
f"{canonical_request_hash}"
)
def _get_signing_key(secret_key, date, region, service_name):
"""Get signing key."""
date_key = _hmac_hash(
("AWS4" + secret_key).encode(),
time.to_signer_date(date).encode(),
)
date_region_key = _hmac_hash(date_key, region.encode())
date_region_service_key = _hmac_hash(
date_region_key, service_name.encode(),
)
return _hmac_hash(date_region_service_key, b"aws4_request")
def _get_signature(signing_key, string_to_sign):
"""Get signature."""
return _hmac_hash(signing_key, string_to_sign.encode(), hexdigest=True)
def _get_authorization(access_key, scope, signed_headers, signature):
"""Get authorization."""
return (
f"AWS4-HMAC-SHA256 Credential={access_key}/{scope}, "
f"SignedHeaders={signed_headers}, Signature={signature}"
)
def _sign_v4(
service_name,
method,
url,
region,
headers,
credentials,
content_sha256,
date,
):
"""Do signature V4 of given request for given service name."""
scope = _get_scope(date, region, service_name)
canonical_request_hash, signed_headers = _get_canonical_request_hash(
method, url, headers, content_sha256,
)
string_to_sign = _get_string_to_sign(date, scope, canonical_request_hash)
signing_key = _get_signing_key(
credentials.secret_key, date, region, service_name,
)
signature = _get_signature(signing_key, string_to_sign)
authorization = _get_authorization(
credentials.access_key, scope, signed_headers, signature,
)
headers["Authorization"] = authorization
return headers
def sign_v4_s3(
method,
url,
region,
headers,
credentials,
content_sha256,
date,
):
"""Do signature V4 of given request for S3 service."""
return _sign_v4(
"s3",
method,
url,
region,
headers,
credentials,
content_sha256,
date,
)
def sign_v4_sts(
method,
url,
region,
headers,
credentials,
content_sha256,
date,
):
"""Do signature V4 of given request for STS service."""
return _sign_v4(
"sts",
method,
url,
region,
headers,
credentials,
content_sha256,
date,
)
def _get_presign_canonical_request_hash( # pylint: disable=invalid-name
method, url, access_key, scope, date, expires,
):
"""Get canonical request hash for presign request."""
x_amz_credential = queryencode(access_key + "/" + scope)
canonical_headers, signed_headers = "host:" + url.netloc, "host"
query = url.query+"&" if url.query else ""
query += (
f"X-Amz-Algorithm=AWS4-HMAC-SHA256"
f"&X-Amz-Credential={x_amz_credential}"
f"&X-Amz-Date={time.to_amz_date(date)}"
f"&X-Amz-Expires={expires}"
f"&X-Amz-SignedHeaders={signed_headers}"
)
parts = list(url)
parts[3] = query
url = SplitResult(*parts)
canonical_query_string = _get_canonical_query_string(query)
# CanonicalRequest =
# HTTPRequestMethod + '\n' +
# CanonicalURI + '\n' +
# CanonicalQueryString + '\n' +
# CanonicalHeaders + '\n\n' +
# SignedHeaders + '\n' +
# HexEncode(Hash(RequestPayload))
canonical_request = (
f"{method}\n"
f"{url.path or '/'}\n"
f"{canonical_query_string}\n"
f"{canonical_headers}\n\n"
f"{signed_headers}\n"
f"UNSIGNED-PAYLOAD"
)
return sha256_hash(canonical_request), url
def presign_v4(
method,
url,
region,
credentials,
date,
expires,
):
"""Do signature V4 of given presign request."""
scope = _get_scope(date, region, "s3")
canonical_request_hash, url = _get_presign_canonical_request_hash(
method, url, credentials.access_key, scope, date, expires,
)
string_to_sign = _get_string_to_sign(date, scope, canonical_request_hash)
signing_key = _get_signing_key(credentials.secret_key, date, region, "s3")
signature = _get_signature(signing_key, string_to_sign)
parts = list(url)
parts[3] = url.query + "&X-Amz-Signature=" + queryencode(signature)
url = SplitResult(*parts)
return url
def get_credential_string(access_key, date, region):
"""Get credential string of given access key, date and region."""
return f"{access_key}/{time.to_signer_date(date)}/{region}/s3/aws4_request"
def post_presign_v4(data, secret_key, date, region):
"""Do signature V4 of given presign POST form-data."""
return _get_signature(
_get_signing_key(secret_key, date, region, "s3"),
data,
)