116 lines
4.2 KiB
Python
116 lines
4.2 KiB
Python
# bijoe - BI dashboard
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# Copyright (C) 2015 Entr'ouvert
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#
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# This program is free software: you can redistribute it and/or modify it
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# under the terms of the GNU Affero General Public License as published
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# by the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import base64
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import datetime
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import hashlib
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import hmac
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import logging
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import random
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import urllib
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from django.utils import six
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from django.utils.encoding import force_bytes, smart_bytes
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from django.utils.http import quote, urlencode
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from django.utils.six.moves.urllib import parse as urlparse
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'''Simple signature scheme for query strings'''
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# from http://repos.entrouvert.org/portail-citoyen.git/tree/portail_citoyen/apps/data_source_plugin/signature.py
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def sign_url(url, key, algo='sha256', timestamp=None, nonce=None):
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parsed = urlparse.urlparse(url)
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new_query = sign_query(parsed.query, key, algo, timestamp, nonce)
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return urlparse.urlunparse(parsed[:4] + (new_query,) + parsed[5:])
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def sign_query(query, key, algo='sha256', timestamp=None, nonce=None):
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if timestamp is None:
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timestamp = datetime.datetime.utcnow()
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timestamp = timestamp.strftime('%Y-%m-%dT%H:%M:%SZ')
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if nonce is None:
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nonce = hex(random.getrandbits(128))[2:]
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new_query = query
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if new_query:
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new_query += '&'
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new_query += urlencode((('algo', algo), ('timestamp', timestamp), ('nonce', nonce)))
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signature = base64.b64encode(sign_string(new_query, key, algo=algo))
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new_query += '&signature=' + quote(signature)
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return new_query
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def sign_string(s, key, algo='sha256', timedelta=30):
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digestmod = getattr(hashlib, algo)
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hash = hmac.HMAC(smart_bytes(key), digestmod=digestmod, msg=smart_bytes(s))
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return hash.digest()
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def check_url(url, key, known_nonce=None, timedelta=30):
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parsed = urlparse.urlparse(url, 'https')
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return check_query(parsed.query, key)
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def check_query(query, key, known_nonce=None, timedelta=30):
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res, error = check_query2(query, key, known_nonce=known_nonce, timedelta=timedelta)
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if not res:
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key_hash = 'md5:%s' % hashlib.md5(force_bytes(key)).hexdigest()[:6]
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logging.getLogger(__name__).warning(
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'could not check signature of query %r with key %s: %s', query, key_hash, error
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)
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return res
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def check_query2(query, key, known_nonce, timedelta):
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parsed = urlparse.parse_qs(query)
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try:
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signature = parsed['signature'][0]
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algo = parsed['algo'][0]
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timestamp = parsed['timestamp'][0]
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nonce = parsed['nonce'][0]
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except KeyError as e:
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return False, 'missing required field %r' % e.args[0]
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try:
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signature = base64.b64decode(parsed['signature'][0])
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except Exception as e:
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return False, 'could not decode base64 signature (%s)' % e
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if algo not in hashlib.algorithms_guaranteed:
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return False, 'hash algorithm %s is not supported' % algo
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try:
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timestamp = datetime.datetime.strptime(timestamp, '%Y-%m-%dT%H:%M:%SZ')
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except Exception as e:
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return False, 'could not parse the timestamp %s' % timestamp
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unsigned_query = query.split('&signature=')[0]
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if known_nonce is not None and known_nonce(nonce):
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return False, 'used nonce'
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if abs(datetime.datetime.utcnow() - timestamp) > datetime.timedelta(seconds=timedelta):
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return False, 'timestamp is older than %d seconds' % timedelta
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if not check_string(unsigned_query, signature, key, algo=algo):
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return False, 'signature does not match'
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return True, None
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def check_string(s, signature, key, algo='sha256'):
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# constant time compare
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signature2 = sign_string(s, key, algo=algo)
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if len(signature2) != len(signature):
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return False
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res = 0
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for a, b in zip(signature, signature2):
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res |= a ^ b
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return res == 0
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