106 lines
3.9 KiB
Python
106 lines
3.9 KiB
Python
# combo - content management system
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# Copyright (C) 2015-2018 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 random
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from django.conf import settings
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from django.utils.encoding import 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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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_request_signature(django_request, keys=[]):
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query_string = django_request.META['QUERY_STRING']
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if not query_string:
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return False
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orig = django_request.GET.get('orig', '')
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known_services = getattr(settings, 'KNOWN_SERVICES', None)
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if known_services and orig:
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for services in known_services.values():
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for service in services.values():
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if 'verif_orig' in service and service['verif_orig'] == orig:
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keys.append(service['secret'])
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break
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return check_query(query_string, keys)
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def check_query(query, keys, known_nonce=None, timedelta=30):
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parsed = urlparse.parse_qs(query)
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if not ('signature' in parsed and 'algo' in parsed and 'timestamp' in parsed and 'nonce' in parsed):
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return False
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unsigned_query, signature_content = query.split('&signature=', 1)
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if '&' in signature_content:
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return False # signature must be the last parameter
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signature = base64.b64decode(parsed['signature'][0])
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algo = parsed['algo'][0]
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timestamp = parsed['timestamp'][0]
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timestamp = datetime.datetime.strptime(timestamp, '%Y-%m-%dT%H:%M:%SZ')
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nonce = parsed['nonce']
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if known_nonce is not None and known_nonce(nonce):
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return False
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if abs(datetime.datetime.utcnow() - timestamp) > datetime.timedelta(seconds=timedelta):
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return False
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return check_string(unsigned_query, signature, keys, algo=algo)
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def check_string(s, signature, keys, algo='sha256'):
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if not isinstance(keys, list):
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keys = [keys]
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for key in keys:
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signature2 = sign_string(s, key, algo=algo)
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if len(signature2) != len(signature):
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continue
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res = 0
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# constant time compare
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for a, b in zip(signature, signature2):
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res |= a ^ b
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if res == 0:
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return True
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return False
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