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Deadwood bug fixed
January 4 2012
I have fixed a bug in Deadwood: Srinivas Hebbar reported that Deadwood
changed the TTL of cached records to always have a TTL of at least
30 seconds. This resulted in Deadwood not removing a record from the
cache if it's retrieved every 30 seconds or more.
The reason why Deadwood did this is because:
- The code for adding records to Deadwood's LRU hash requires a record
to have a TTL of at least 30 seconds
- Deadwood's code that ages TTLs and rotates records fetches a record
from the LRU hash, then immediately puts the same record back in the
LRU hash.
To fix this issue, I modified the code that adds a record to the LRU
hash. I have added special code, so that if the TTL has a value of
-2, this means do the following:
- Look to see if the record is already in the LRU hash.
- If it is, do not alter the TTL when updating the record.
- If it is not, give the new record a new TTL of 30 seconds.
Using a SQA test I created for this issue yesterday, I have verified
that my patch resolves Srinivas' issue.
The patch is here:
http://maradns.org/deadwood/patches/deadwood-3.1.03-ttl_expire.patch
And the snapshot with this patch as well as the new SQA test is here:
http://www.maradns.org/deadwood/snap/
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