Mitigate flooding attacks at sync layer
The sync layer should mitigate flooding attacks by preventing any contact or group from exhausting any resource (computation, bandwidth, memory or storage).
This might be done by implementing something similar to fair queueing for each resource: when the resource gets close to being fully used, prioritise demand from contacts and groups that are using less than their fair share over demand from contacts and groups that are using more than their fair share.
Edited by Cleopatra