What were you trying to do that didn't work?

Resolving a hostname using host command works when having a TTY:

# host www.tribunal-fédéral.ch
www.tribunal-fédéral.ch is an alias for bnetm.x.incapdns.net.
bnetm.x.incapdns.net has address 107.154.115.41

But it fails when not having a TTY, e.g.:

1. With piping the output

   # host www.tribunal-fédéral.ch | cat
   Host www.tribunal-fédéral.ch not found: 3(NXDOMAIN)
   

2. As a service

   # systemd-run host www.tribunal-fédéral.ch
   Running as unit: run-r91b04b09794d4250884722ff003b9470.service
   # journalctl -u run-r91b04b09794d4250884722ff003b9470.service
   Nov 06 15:34:53 vm-host9 systemd[1]: Started /usr/bin/host -4 -T www.tribunal-fédéral.ch.
   Nov 06 15:34:53 vm-host9 host[33165]: Host www.tribunal-fédéral.ch not found: 3(NXDOMAIN)

3. As a cron

   # crontab -e
   * * * * * host www.tribunal-fédéral.ch >/tmp/host.out
   # sleep 60; cat /tmp/host.out
   Host www.tribunal-fédéral.ch not found: 3(NXDOMAIN)
   

The reason for this is ACE conversion is performed only when having a TTY (line 674), which is wrong:

 673 #ifdef HAVE_LIBIDN2
 674         looknew->idnin = isatty(1) ? (getenv("IDN_DISABLE") == NULL) : false;

2133 #ifdef HAVE_LIBIDN2
2134         if (lookup->idnin) {
2135                 idn_locale_to_ace(textname, idn_textname, sizeof(idn_textname));
2136                 debug("idn_textname: %s", idn_textname);
2137                 textname = idn_textname;
2138         }

What is the impact of this issue to you?

Cannot perform queries of internationalized domains programmatically

Please provide the package NVR for which the bug is seen:

bind-utils-9.16.23-18.el9_4.6
bind-utils-9.18.28-2.fc40.x86_64 (Fedora 40)

How reproducible is this bug?:

Always, see above.