* The location of the digest type field has changed to where the
reserved field was.
* The reserved field is now called scheme and is where the digest
type field was.
* Digest type 2 has been defined (SHA256).
Define a :gl: Sphinx role that takes a GitLab issue/MR number as an
argument and creates a hyperlink to the relevant ISC GitLab URL. This
makes it easy to reach ISC GitLab pages directly from the release notes.
Make all GitLab references in the release notes use the new Sphinx role.
When introducing change 5149, "rndc dumpdb" started to print a line
above a stale RRset, indicating how long the data will be retained.
At that time, I thought it should also be possible to load
a cache from file. But if a TTL has a value of 0 (because it is stale),
stale entries wouldn't be loaded from file. So, I added the
'max-stale-ttl' to TTL values, and adjusted the $DATE accordingly.
Since we actually don't have a "load cache from file" feature, this
is premature and is causing confusion at operators. This commit
changes the 'max-stale-ttl' adjustments.
A check in the serve-stale system test is added for a non-stale
RRset (longttl.example) to make sure the TTL in cache is sensible.
Also, the comment above stale RRsets could have nonsensical
values. A possible reason why this may happen is when the RRset was
marked a stale but the 'max-stale-ttl' has passed (and is actually an
RRset awaiting cleanup). This would lead to the "will be retained"
value to be negative (but since it is stored in an uint32_t, you would
get a nonsensical value (e.g. 4294362497).
To mitigate against this, we now also check if the header is not
ancient. In addition we check if the stale_ttl would be negative, and
if so we set it to 0. Most likely this will not happen because the
header would already have been marked ancient, but there is a possible
race condition where the 'rdh_ttl + serve_stale_ttl' has passed,
but the header has not been checked for staleness.
