Most of RT#6923, except for the part that depends on the sendto_kdc rewrite
(it's still in locate_kdc in this version): pass AI_ADDRCONFIG whenever we
specify hints to getaddrinfo() to get the address of a server.

Index: src/plugins/locate/python/py-locate.c
===================================================================
--- src/plugins/locate/python/py-locate.c.orig
+++ src/plugins/locate/python/py-locate.c
@@ -303,6 +303,7 @@ lookup(void *blob, enum locate_service_t
             return -1;
         }
         aihints.ai_socktype = thissocktype;
+        aihints.ai_flags = AI_ADDRCONFIG;
         x = getaddrinfo (hoststr, portstr, &aihints, &airesult);
         if (x != 0)
             continue;
Index: src/appl/sample/sclient/sclient.c
===================================================================
--- src/appl/sample/sclient/sclient.c.orig
+++ src/appl/sample/sclient/sclient.c
@@ -124,6 +124,7 @@ main(int argc, char *argv[])
 
     memset(&aihints, 0, sizeof(aihints));
     aihints.ai_socktype = SOCK_STREAM;
+    aihints.ai_flags = AI_ADDRCONFIG;
     aierr = getaddrinfo(argv[1], portstr, &aihints, &ap);
     if (aierr) {
         fprintf(stderr, "%s: error looking up host '%s' port '%s'/tcp: %s\n",
Index: src/kadmin/dbutil/kadm5_create.c
===================================================================
--- src/kadmin/dbutil/kadm5_create.c.orig
+++ src/kadmin/dbutil/kadm5_create.c
@@ -182,7 +182,7 @@ static int add_admin_princs(void *handle
         goto clean_and_exit;
     }
     memset(&ai_hints, 0, sizeof(ai_hints));
-    ai_hints.ai_flags = AI_CANONNAME;
+    ai_hints.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
     gai_error = getaddrinfo(localname, (char *)NULL, &ai_hints, &ai);
     if (gai_error) {
         ret = EINVAL;
Index: src/lib/kadm5/alt_prof.c
===================================================================
--- src/lib/kadm5/alt_prof.c.orig
+++ src/lib/kadm5/alt_prof.c
@@ -901,7 +901,7 @@ kadm5_get_admin_service_name(krb5_contex
     }
 
     memset(&hint, 0, sizeof(hint));
-    hint.ai_flags = AI_CANONNAME;
+    hint.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
     err = getaddrinfo(params_out.admin_server, NULL, &hint, &ai);
     if (err != 0) {
         ret = KADM5_CANT_RESOLVE;
Index: src/lib/kadm5/clnt/client_init.c
===================================================================
--- src/lib/kadm5/clnt/client_init.c.orig
+++ src/lib/kadm5/clnt/client_init.c
@@ -563,8 +563,9 @@ connect_to_server(const char *hostname,
     (void) snprintf(portbuf, sizeof(portbuf), "%d", port);
     memset(&hint, 0, sizeof(hint));
     hint.ai_socktype = SOCK_STREAM;
+    hint.ai_flags = AI_ADDRCONFIG;
 #ifdef AI_NUMERICSERV
-    hint.ai_flags = AI_NUMERICSERV;
+    hint.ai_flags |= AI_NUMERICSERV;
 #endif
     err = getaddrinfo(hostname, portbuf, &hint, &addrs);
     if (err != 0)
Index: src/lib/krb5/os/hostaddr.c
===================================================================
--- src/lib/krb5/os/hostaddr.c.orig
+++ src/lib/krb5/os/hostaddr.c
@@ -44,7 +44,7 @@ krb5_os_hostaddr(krb5_context context, c
         return KRB5_ERR_BAD_HOSTNAME;
 
     memset (&hints, 0, sizeof (hints));
-    hints.ai_flags = AI_NUMERICHOST;
+    hints.ai_flags = AI_NUMERICHOST | AI_ADDRCONFIG;
     /* We don't care what kind at this point, really, but without
        this, we can get back multiple sockaddrs per address, for
        SOCK_DGRAM, SOCK_STREAM, and SOCK_RAW.  I haven't checked if
Index: src/lib/krb5/os/hst_realm.c
===================================================================
--- src/lib/krb5/os/hst_realm.c.orig
+++ src/lib/krb5/os/hst_realm.c
@@ -103,7 +103,7 @@ get_fq_hostname(char *buf, size_t bufsiz
     int err;
 
     memset (&hints, 0, sizeof (hints));
-    hints.ai_flags = AI_CANONNAME;
+    hints.ai_flags = AI_CANONNAME | AI_ADDRCONFIG;
     err = getaddrinfo (name, 0, &hints, &ai);
     if (err)
         return krb5int_translate_gai_error (err);
Index: src/slave/kprop.c
===================================================================
--- src/slave/kprop.c.orig
+++ src/slave/kprop.c
@@ -325,6 +325,7 @@ open_connection(krb5_context context, ch
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = PF_UNSPEC;
     hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_ADDRCONFIG;
     error = getaddrinfo(host, port, &hints, &answers);
     if (error != 0) {
         com_err(progname, 0, "%s: %s", host, gai_strerror(error));
Index: src/lib/krb5/os/locate_kdc.c
===================================================================
--- src/lib/krb5/os/locate_kdc.c.orig
+++ src/lib/krb5/os/locate_kdc.c
@@ -259,8 +259,9 @@ krb5int_add_host_to_list (struct addrlis
     memset(&hint, 0, sizeof(hint));
     hint.ai_family = family;
     hint.ai_socktype = socktype;
+    hint.ai_flags = AI_ADDRCONFIG;
 #ifdef AI_NUMERICSERV
-    hint.ai_flags = AI_NUMERICSERV;
+    hint.ai_flags |= AI_NUMERICSERV;
 #endif
     result = snprintf(portbuf, sizeof(portbuf), "%d", ntohs(port));
     if (SNPRINTF_OVERFLOW(result, sizeof(portbuf)))