commit eb28b43d69ea3d91b8ccab6fbc7569817fc25ebb Author: Isis Lovecruft isis@torproject.org Date: Fri Dec 5 23:57:36 2014 +0000

Implement `client` and `getHashringPlacement()` interfaces.

* ADD base class implementations of IRequestBridges.client and IRequestBridges.getHashringPlacement() to BridgeRequestBase class. --- lib/bridgedb/bridgerequest.py | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)

diff --git a/lib/bridgedb/bridgerequest.py b/lib/bridgedb/bridgerequest.py index 840b2fc..d7b4d18 100644 --- a/lib/bridgedb/bridgerequest.py +++ b/lib/bridgedb/bridgerequest.py @@ -20,6 +20,7 @@ from zope.interface import Attribute from zope.interface import Interface

from bridgedb import Filters +from bridgedb.crypto import getHMACFunc

class IRequestBridges(Interface): @@ -93,8 +94,34 @@ class BridgeRequestBase(object): self.filters = list() self.transports = list() self.notBlockedIn = list() + #: This should be some information unique to the client making the + #: request for bridges, such that we are able to HMAC this unique data + #: in order to place the client into a hashring (determining which + #: bridge addresses they get in the request response). It defaults to + #: the string ``'default'``. + self.client = 'default' self.valid = False

+ def getHashringPlacement(self, key, client=None): + """Create an HMAC of some **client** info using a **key**. + + :param str key: The key to use for HMACing. + :param str client: Some (hopefully unique) information about the + client who is requesting bridges, such as an IP or email address. + :rtype: long + :returns: A long specifying index of the first node in a hashring to + be distributed to the client. This value should obviously be used + mod the number of nodes in the hashring. + """ + if not client: + client = self.client + + # Get an HMAC with the key of the client identifier: + digest = getHMACFunc(key)(client) + # Take the lower 8 bytes of the digest and convert to a long: + position = long(digest[:8], 16) + return position + def isValid(self, valid=None): """Set or determine if this request was valid.