AXFR garbage in zone with eccentric RRtypes

[mdavids]

• Program: Authoritative
• Issue type: Bug report

Short description

SIDN Labs runs a so called DNS workbench.

One of the zone files in that workbench contains a range of different RRtypes. We managed to load it successfully in PowerDNS by slaving it with a sqlite3 back-end (and earlier attempt to do it with a bind backend resulted in #7437)

The zone appears to work, but an AXFR fails:

dig AXFR types.wb.sidnlabs.nl @powerdns.sidnlabs.nl
;; Got bad packet: bad compression pointer

Environment

• Operating system: Ubuntu 18.04
• Software version: pdns-server 4.1.1-1 package
• Software source: Operating system repository

Steps to reproduce

1. dig AXFR types.wb.sidnlabs.nl @powerdns.sidnlabs.nl
2. dig AXFR types-signed.wb.sidnlabs.nl @powerdns.sidnlabs.nl

Expected behaviour

Successful zone transfer

Actual behaviour

; <<>> DiG 9.13.3 <<>> AXFR types.wb.sidnlabs.nl @powerdns.sidnlabs.nl
;; global options: +cmd
types.wb.sidnlabs.nl. 86400 IN SOA bind9.sidnlabs.nl. hostmaster.sidnlabs.nl. 1549195009 3600 600 1814400 3600
;; Got bad packet: bad compression pointer
3790 bytes

[mdavids]

workbench_powerdns_axfr.pcap.gz

[omoerbeek]

This seems to happen at least with MR and MG records. e.g.

dig MR mr.types.wb.sidnlabs.nl @powerdns.sidnlabs.nl

Is enough to trigger the issue.

How did you import the zone? Via a slave copy, db import using the sqlite tool, zone2sql or maybe another method?

[omoerbeek]

I can reproduce using 4.1.x, but this is fixed in 4.2, which will be released soon.

Please confirm using https://downloads.powerdns.com/autobuilt_browser/#/auth/4.2.0-rc1

See #6377 (although this PR does not seem to fix the MR case, it is fixed as well in my testing).

IMO this is not worth the trouble to backport since the record types are deprecated anyway.

[omoerbeek]

@mdavids I'd appreciate some feedback. Thanks.

[mdavids]

Unable to verify this on the short term, sorry.
Will try to do this a.s.a.p.
Feel free to close the ticket, I have great confidence in your claims.
Totally agree with the 'no backporting' view.

[mdavids]

How did you import the zone? Via a slave copy, db import using the sqlite tool, zone2sql or maybe another method?

We load it in PowerDNS by slaving it with a sqlite3 backend (an earlier attempt to do it with a bind backend resulted in #7437).

[omoerbeek]

OK, I'm closing this and next will take a look at #7437