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Code Issues Releases Activity

SPF Optimizer: Enable the use of TXTMulti records to support longer SPF records (#794)

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* 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
This commit is contained in:
Michael Russell
2020-07-31 19:28:13 +02:00
committed by GitHub
parent 237c573c2a
commit f21c8fc400
6 changed files with 245 additions and 119 deletions
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5
pkg/js/helpers.js
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@ -733,6 +733,7 @@ var FRAME = recordBuilder('FRAME');
// split: The template for additional records to be created (default: '_spf%d')
// flatten: A list of domains to be flattened.
// overhead1: Amout of "buffer room" to reserve on the first item in the spf chain.
// txtMaxSize: The maximum size for each TXT string. Values over 255 will result in multiple strings (default: '255')
function SPF_BUILDER(value) {
if (!value.parts || value.parts.length < 2) {
@ -771,6 +772,10 @@ function SPF_BUILDER(value) {
p.overhead1 = value.overhead1;
}
if (value.txtMaxSize) {
p.txtMaxSize = value.txtMaxSize;
}
// Generate a TXT record with the metaparameters.
if (value.ttl) {
r.push(TXT(value.label, rawspf, p, TTL(value.ttl)));