kinit fails on AIX 7.1 - res_nsearch returns -1

[Vipul Mehta]

Hi,

When i am trying kinit in AIX 7.1, it fails with "Illegal instruction" as
output. core dump generated was corrupted.

On debugging i found out that dnsglue.c -> krb5int_dns_init() -> line152
returns -1. Following is the call:
len = SEARCH(h, host, ds->nclass, ds->ntype, ds->ansp, ds->ansmax);

SEARCH is expanded to use res_nsearch() in AIX.
After return statement from krb5int_dns_init(), looks like call stack gets
corrupted.

To find out why res_nsearch() failed, i enabled following debug flag for it
and recompiled:
h.options |= RES_DEBUG;

Following was the output:
;; res_nquerydomain(, informatica.com, 1, 33)
;; res_query(.informatica.com, 1, 33)
;; res_nmkquery(QUERY, .informatica.com, IN, SRV)
;; res_query: mkquery failed
;; res_nquerydomain(, <Nil>, 1, 33)
;; res_query(, 1, 33)
;; res_nmkquery(QUERY, , IN, SRV)
;; res_send()
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10721
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;      ., type = SRV, class = IN
;; Querying server (# 1) address = 10.23.32.61
server rejected query:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 10721
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;      ., type = SRV, class = IN
;; Querying server (# 2) address = 10.23.32.62
server rejected query:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 10721
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;      ., type = SRV, class = IN
;; Querying server (# 3) address = 10.1.32.114
server rejected query:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 10721
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;      ., type = SRV, class = IN
;; res_query: send error

errno set after this was 78 and translating it to string gives "A remote
host did not respond within the timeout period" which looks like misleading
because following AIX standalone command works fine:
RES_OPTIONS=debug host informatica.com

I understand that MIT Kerberos is not supported on AIX but any pointer
towards solving this issue would be of great help.

-- 
Regards,
Vipul