From f0bd3361e09d206c47c0dc439c6642f96f67fab9 Mon Sep 17 00:00:00 2001
From: Stephen Frost <sfrost@snowman.net>
Date: Fri, 7 Apr 2023 19:36:03 -0400
Subject: [PATCH] For Kerberos testing, disable reverse DNS lookup

In our Kerberos test suite, there isn't much need to worry about the
normal canonicalization that Kerberos provides by looking up the reverse
DNS for the IP address connected to, and in some cases it can actively
cause problems (eg: a captive portal wifi where the normally not
resolvable localhost address used ends up being resolved anyway, and
not to the domain we are using for testing, causing the entire
regression test to fail with errors about not being able to get a TGT
for the remote realm for cross-realm trust).

Therefore, disable it by adding rdns = false into the krb5.conf that's
generated for the test.

Reviewed-By: Heikki Linnakangas
Discussion: https://postgr.es/m/Y/QD2zDkDYQA1GQt@tamriel.snowman.net
---
 src/test/kerberos/t/001_auth.pl | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/test/kerberos/t/001_auth.pl b/src/test/kerberos/t/001_auth.pl
index 9e0a2150de..65910ac3c1 100644
--- a/src/test/kerberos/t/001_auth.pl
+++ b/src/test/kerberos/t/001_auth.pl
@@ -72,6 +72,17 @@ $stdout =~ m/Kerberos 5 release ([0-9]+\.[0-9]+)/
   or BAIL_OUT("could not get Kerberos version");
 $krb5_version = $1;
 
+# Build the krb5.conf to use.
+#
+# Explicitly specify the default (test) realm and the KDC for
+# that realm to avoid the Kerberos library trying to look up
+# that information in DNS, and also because we're using a
+# non-standard KDC port.
+#
+# Reverse DNS is explicitly disabled to avoid any issue with a
+# captive portal or other cases where the reverse DNS succeeds
+# and the Kerberos library uses that as the canonical name of
+# the host and then tries to acquire a cross-realm ticket.
 append_to_file(
 	$krb5_conf,
 	qq![logging]
@@ -80,6 +91,7 @@ kdc = FILE:$kdc_log
 
 [libdefaults]
 default_realm = $realm
+rdns = false
 
 [realms]
 $realm = {