Backport the support/ changes from this commit, to avoid future
conflicts:

commit 446997ff1433d33452b81dfa9e626b8dccf101a4
Author: Florian Weimer <fweimer@redhat.com>
Date:   Wed Oct 30 17:26:58 2019 +0100

    resolv: Implement trust-ad option for /etc/resolv.conf [BZ #20358]
    
    This introduces a concept of trusted name servers, for which the
    AD bit is passed through to applications.  For untrusted name
    servers (the default), the AD bit in responses are cleared, to
    provide a safe default.
    
    This approach is very similar to the one suggested by Pavel Šimerda
    in <https://bugzilla.redhat.com/show_bug.cgi?id=1164339#c15>.
    
    The DNS test framework in support/ is enhanced with support for
    setting the AD bit in responses.
    
    Tested on x86_64-linux-gnu.
    
    Change-Id: Ibfe0f7c73ea221c35979842c5c3b6ed486495ccc

diff --git a/support/resolv_test.c b/support/resolv_test.c
index 3f2a09f36f445878..28af227cb5ed901c 100644
--- a/support/resolv_test.c
+++ b/support/resolv_test.c
@@ -182,6 +182,8 @@ resolv_response_init (struct resolv_response_builder *b,
   if (flags.tc)
     b->buffer[2] |= 0x02;
   b->buffer[3] = 0x80 | flags.rcode; /* Always set RA.  */
+  if (flags.ad)
+    b->buffer[3] |= 0x20;
 
   /* Fill in the initial section count values.  */
   b->buffer[4] = flags.qdcount >> 8;
diff --git a/support/resolv_test.h b/support/resolv_test.h
index 4c2e6c1b417f5fcd..be736aead40cd0cc 100644
--- a/support/resolv_test.h
+++ b/support/resolv_test.h
@@ -134,6 +134,9 @@ struct resolv_response_flags
   /* If true, the TC (truncation) flag will be set.  */
   bool tc;
 
+  /* If true, the AD (authenticated data) flag will be set.  */
+  bool ad;
+
   /* Initial section count values.  Can be used to artificially
      increase the counts, for malformed packet testing.*/
   unsigned short qdcount;