* Add multiple string support to SPF optimizer
Notes:
* This implements [RFC 4408][rfc] for the SPF optimizer. Allowing for
more SPF records to fit within the 10 lookups by using multiple strings.
* By default the max size of the TXT remains at 255. Meaning users will
still only get a single 255 length string unless they modify `txtMaxSize`
and opt into this feature.
* The general recommendation when using multiple strings for TXT records
is to keep the size within a single UDP packet. It seems like the
maximum size for this depends on a bunch of factors that are sometimes
outside of your control. A similar tool has a [formula for estimating the
maximum allowed size][formula]. However I felt giving a user
configurable size would fit with the current configuration style that
dnscontrol has. Similar to how dnscontrol recommends only flattening a
record if absolutely needed, I can see this length being increased by
only enough to get you within 10 lookups.
[rfc]: https://tools.ietf.org/html/rfc4408#section-3.1.3
[formula]: https://github.com/oasys/mkspf/blob/master/Overhead.md
* Add a nice comment for the Chunks function
* Replaced errors.Wrap with fmt.Errorf (#589)
* Find: errors\.Wrap\(([^,]+),\s+(["`][^"`]*)(["`])\)
Replace: fmt.Errorf($2: %w$3, $1)
* Replaced errors.Wrapf with fmt.Errorf (#589)
* Find: errors\.Wrapf\(([^,]+),\s+(["`][^"`]*)(["`])\)
Replace: fmt.Errorf($2: %w$3, $1)
* Find: errors\.Wrapf\(([^,]+),\s+(["`][^"`]*)(["`])(,[^)]+)\)
* Replace: fmt.Errorf($2: %w$3$4, $1)
* Replaced errors.Errorf with fmt.Errorf (#589)
* Find: errors\.Errorf
Replace: fmt.Errorf
* Cleaned up remaining imports
* Cleanup
* Regenerate provider support matrix
This was broken by #533 ... and it's now the third time this has been missed.
FYI: The support is very minimal. It only supports redirect if it is the last item in an SPF record. At that point, it is equivalent to include.
* In SFP, treat redirect like a special include.
* Document SPF redirect: limited implementation.
