auth nsupdate: duplicate entries when mixing case

[Habbie]

• Program: Authoritative
• Issue type: Bug report/Feature request

Short description

Our 2136-code prevents adding duplicate entries, but this fails in the face of mixed case entries.

Patching one of the existing tests like this reveals the issue:

diff --git a/regression-tests/tests/1dyndns-update-replace-cname/command b/regression-tests/tests/1dyndns-update-replace-cname/command
index 17bd7c818..3eef41f0e 100755
--- a/regression-tests/tests/1dyndns-update-replace-cname/command
+++ b/regression-tests/tests/1dyndns-update-replace-cname/command
@@ -1,22 +1,22 @@
 #!/bin/sh
-cleandig cname1.test.dyndns CNAME
+cleandig ptr1.test.dyndns PTR

 cleannsupdate <<!
 server $nameserver $port
 zone test.dyndns
-update add cname1.test.dyndns. 3600 CNAME host-2.test.dyndns.
+update add ptr1.test.dyndns. 3600 PTR host-2.test.dyndns.
 send
 answer
 !

-cleandig cname1.test.dyndns CNAME
+cleandig ptr1.test.dyndns PTR

 cleannsupdate <<!
 server $nameserver $port
 zone test.dyndns
-update add cname1.test.dyndns. 3600 CNAME host-1.test.dyndns.
+update add ptr1.test.dyndns. 3600 PTR HOST-2.test.dyndns.
 send
 answer
 !

-cleandig cname1.test.dyndns CNAME
+cleandig ptr1.test.dyndns PTR

[Habbie]

Fixed in #8235:

• this issue when pertaining to PTR, MX or SRV

Not fixed in #8235:

• the HTTP API allows case-mixed duplicates when they come in a single REPLACE call
• comparison (in rfc2136, HTTP API and check-zone) should be done on the wire format, ignoring case for those fields that don't care about case

• 6914