diff options
Diffstat (limited to 'src/mailman/rest/helpers.py')
| -rw-r--r-- | src/mailman/rest/helpers.py | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/src/mailman/rest/helpers.py b/src/mailman/rest/helpers.py index 025ad1779..db3e43af0 100644 --- a/src/mailman/rest/helpers.py +++ b/src/mailman/rest/helpers.py @@ -38,6 +38,7 @@ from cStringIO import StringIO from datetime import datetime, timedelta from enum import Enum from lazr.config import as_boolean +from pprint import pformat from restish import http from restish.http import Response from restish.resource import MethodDecorator @@ -89,11 +90,12 @@ class ExtendedEncoder(json.JSONEncoder): def etag(resource): """Calculate the etag and return a JSON representation. - The input is a dictionary representing the resource. This dictionary must - not contain an `http_etag` key. This function calculates the etag by - using the sha1 hexdigest of the repr of the dictionary. It then inserts - this value under the `http_etag` key, and returns the JSON representation - of the modified dictionary. + The input is a dictionary representing the resource. This + dictionary must not contain an `http_etag` key. This function + calculates the etag by using the sha1 hexdigest of the + pretty-printed (and thus key-sorted and predictable) representation + of the dictionary. It then inserts this value under the `http_etag` + key, and returns the JSON representation of the modified dictionary. :param resource: The original resource representation. :type resource: dictionary @@ -101,8 +103,10 @@ def etag(resource): :rtype string """ assert 'http_etag' not in resource, 'Resource already etagged' - etag = hashlib.sha1(repr(resource)).hexdigest() - + # Calculate the tag from a predictable (i.e. sorted) representation of the + # dictionary. The actual details aren't so important. pformat() is + # guaranteed to sort the keys. + etag = hashlib.sha1(pformat(resource)).hexdigest() resource['http_etag'] = '"{0}"'.format(etag) return json.dumps(resource, cls=ExtendedEncoder) |