Add option to shorten mod-synthrecord records

Probably we could introduce an option for this (predefined list of formats). But I would like to avoid arbitrary formats, as it should be reasonably fast to generate a response.

@telmich What about 2a0a-e5c0--3.loves.ipv6.at.ungleich.ch.?

@dsalzman That would be optimal! Beauty!

mentioned in merge request !1010 (closed)

added feature knot labels

@telmich do you think you could test this branch https://gitlab.labs.nic.cz/knot/knot-dns/commits/synthrecord_fixes?

It contains:

Full support for compressed IPv6 address format in the forward mode.
Removed leading zeros from IPv6 address blocks in the reverse mode.
Reasonable IPv6 address blocks compression in the reverse mode. The IDN restrictions are considered. So the first, second, and last zero address blocks are not compressed.

There is no configuration option for that. If works out-of-the-box.

@dsalzman very cool, will give it a try these days!

@telmich any news? :-) If you need a binary package, just let me know...

In short: it looks very good. One tiny, tiny detail: it might be good to turn on/off compression of reverse dns lookups, as one might want to provide full names vs short names by default.

The advantage of full names is that the size is always the same, so it might be easier/of advantage to support them by default instead of short names.

In long:

I tested 3.0.dev.1578406399.c6853a45, directly checked out from git.

Running as follows:

[15:59] line:knot-dns% ./src/knotd -c ~/knottest/knot.conf  -v -s ~/knottest/knot.sock
2020-01-07T15:59:38 debug: module 'mod-cookies', loaded static
2020-01-07T15:59:38 debug: module 'mod-dnsproxy', loaded static
2020-01-07T15:59:38 debug: module 'mod-geoip', loaded static
2020-01-07T15:59:38 debug: module 'mod-noudp', loaded static
2020-01-07T15:59:38 debug: module 'mod-onlinesign', loaded static
2020-01-07T15:59:38 debug: module 'mod-queryacl', loaded static
2020-01-07T15:59:38 debug: module 'mod-rrl', loaded static
2020-01-07T15:59:38 debug: module 'mod-stats', loaded static
2020-01-07T15:59:38 debug: module 'mod-synthrecord', loaded static
2020-01-07T15:59:38 debug: module 'mod-whoami', loaded static
2020-01-07T15:59:38 info: Knot DNS 3.0.dev.1578406399.c6853a456 starting
2020-01-07T15:59:38 info: loaded configuration file '/home/nico/knottest/knot.conf'
2020-01-07T15:59:38 info: using reuseport for UDP
2020-01-07T15:59:38 info: binding to interface ::@5555
2020-01-07T15:59:38 info: loading 2 zones
2020-01-07T15:59:38 info: [ip6.arpa.] zone will be loaded
2020-01-07T15:59:38 info: [has-a.name.] zone will be loaded
2020-01-07T15:59:38 info: starting server
2020-01-07T15:59:38 info: [has-a.name.] zone file parsed, serial 2019041501
2020-01-07T15:59:38 info: [has-a.name.] loaded, serial none -> 2019041501, 158 bytes
2020-01-07T15:59:38 info: [ip6.arpa.] zone file parsed, serial 2019050105
2020-01-07T15:59:38 info: [ip6.arpa.] loaded, serial none -> 2019050105, 3876 bytes
2020-01-07T15:59:38 info: server started in the foreground, PID 31419
2020-01-07T15:59:38 info: control, binding to '/home/nico/knottest/knot.sock'

Using this config:

[15:56] line:db% cat ~/knottest/knot.conf 
server:
    listen: ::@5555
    #user: knot:knot

mod-synthrecord:
  - id: ungleich-reverse
    type: reverse
    origin: has-a.name
    ttl: 600
    network: ::/0
  - id: ungleich-forward
    type: forward
    ttl: 600
    network: ::/0

zone:
    - domain: ip6.arpa.
      file: /home/nico/knottest/db/ip6.arpa
      module: mod-synthrecord/ungleich-reverse
    - domain: has-a.name
      file: /home/nico/knottest/db/has-a.name
      module: mod-synthrecord/ungleich-forward

Zone files are empty/only contain the necessary header.

Tests:

for name in 2a0a-e5c0--0 0--0 1--0 0--1 2a0a-e5c1-137--42 $(echo 2a0a:e5c0:2:5:70c2:d35d:93a0:e367 | sed 's/:/-/g') ; do addr=$(dig -p 5555 +short ${name}.has-a.name @::1 aaaa); name_dns=$(dig -p 5555 +short -x ${addr} @::1);   printf '%s: %s <-> %s\n' $name $addr $name_dns;  done

produces

0--0: :: <-> 0-0--0.has-a.name.
1--0: 1:: <-> 1-0--0.has-a.name.
0--1: ::1 <-> 0-0--1.has-a.name.
2a0a-e5c1-137--42: 2a0a:e5c1:137::42 <-> 2a0a-e5c1-137--42.has-a.name.
2a0a-e5c0-2-5-70c2-d35d-93a0-e367: 2a0a:e5c0:2:5:70c2:d35d:93a0:e367 <-> 2a0a-e5c0-2-5-70c2-d35d-93a0-e367.has-a.name.

What is especially well is that I can just take the IPv6 address of my notebook and replace : with - and it 'just works.

From my side: good to go and if you add a boolean flag "reverse-full: true|false" defaulting to false (because I'd assume that most people prefer shortened by default" at some point in the future: perfect!

Thanks for the ping, @dsalzman!

@telmich thanks for the test! I will add the config option. If you are impatient, you can backport this feature to 2.9 when finished.

closed via commit 72dd2b4e

mentioned in commit 72dd2b4e

Add option to shorten mod-synthrecord records

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Add option to shorten mod-synthrecord records

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