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# -*- coding: utf-8 -*-
import hmac
from hashlib import sha1 as sha
py3k = False
try:
from urlparse import urlparse, unquote
from base64 import encodestring
except:
py3k = True
from urllib.parse import urlparse, unquote
from base64 import encodebytes as encodestring
from email.utils import formatdate
from requests.auth import AuthBase
class S3Auth(AuthBase):
"""Attaches AWS Authentication to the given Request object."""
service_base_url = 's3.amazonaws.com'
# List of Query String Arguments of Interest
special_params = [
'acl', 'location', 'logging', 'partNumber', 'policy', 'requestPayment',
'torrent', 'versioning', 'versionId', 'versions', 'website', 'uploads',
'uploadId', 'response-content-type', 'response-content-language',
'response-expires', 'response-cache-control', 'delete', 'lifecycle',
'response-content-disposition', 'response-content-encoding', 'tagging',
'notification', 'cors'
]
def __init__(self, access_key, secret_key, service_url=None):
if service_url:
self.service_base_url = service_url
self.access_key = str(access_key)
self.secret_key = str(secret_key)
def __call__(self, r):
# Create date header if it is not created yet.
if 'date' not in r.headers and 'x-amz-date' not in r.headers:
r.headers['date'] = formatdate(
timeval=None,
localtime=False,
usegmt=True)
signature = self.get_signature(r)
if py3k:
signature = signature.decode('utf-8')
r.headers['Authorization'] = 'AWS %s:%s' % (self.access_key, signature)
return r
def get_signature(self, r):
canonical_string = self.get_canonical_string(
r.url, r.headers, r.method)
if py3k:
key = self.secret_key.encode('utf-8')
msg = canonical_string.encode('utf-8')
else:
key = self.secret_key
msg = canonical_string
h = hmac.new(key, msg, digestmod=sha)
return encodestring(h.digest()).strip()
def get_canonical_string(self, url, headers, method):
parsedurl = urlparse(url)
objectkey = parsedurl.path[1:]
query_args = sorted(parsedurl.query.split('&'))
bucket = parsedurl.netloc[:-len(self.service_base_url)]
if len(bucket) > 1:
# remove last dot
bucket = bucket[:-1]
interesting_headers = {
'content-md5': '',
'content-type': '',
'date': ''}
for key in headers:
lk = key.lower()
try:
lk = lk.decode('utf-8')
except:
pass
if headers[key] and (lk in interesting_headers.keys()
or lk.startswith('x-amz-')):
interesting_headers[lk] = headers[key].strip()
# If x-amz-date is used it supersedes the date header.
if not py3k:
if 'x-amz-date' in interesting_headers:
interesting_headers['date'] = ''
else:
if 'x-amz-date' in interesting_headers:
interesting_headers['date'] = ''
buf = '%s\n' % method
for key in sorted(interesting_headers.keys()):
val = interesting_headers[key]
if key.startswith('x-amz-'):
buf += '%s:%s\n' % (key, val)
else:
buf += '%s\n' % val
# append the bucket if it exists
if bucket != '':
buf += '/%s' % bucket
# add the objectkey. even if it doesn't exist, add the slash
buf += '/%s' % objectkey
params_found = False
# handle special query string arguments
for q in query_args:
k = q.split('=')[0]
if k in self.special_params:
buf += '&' if params_found else '?'
params_found = True
try:
k, v = q.split('=', 1)
except ValueError:
buf += q
else:
# Riak CS multipart upload ids look like this, `TFDSheOgTxC2Tsh1qVK73A==`,
# is should be escaped to be included as part of a query string.
#
# A requests mp upload part request may look like
# resp = requests.put(
# 'https://url_here',
# params={
# 'partNumber': 1,
# 'uploadId': 'TFDSheOgTxC2Tsh1qVK73A=='
# },
# data='some data',
# auth=S3Auth('access_key', 'secret_key')
# )
#
# Requests automatically escapes the values in the `params` dict, so now
# our uploadId is `TFDSheOgTxC2Tsh1qVK73A%3D%3D`,
# if we sign the request with the encoded value the signature will
# not be valid, we'll get 403 Access Denied.
# So we unquote, this is no-op if the value isn't encoded.
buf += '{key}={value}'.format(key=k, value=unquote(v))
return buf
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