From e65d4989a138c7a4c196a8137524453a7fedae20 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Tue, 14 May 2019 11:38:13 +1000
Subject: [PATCH] Recurse to find the root server list with 'dig +trace'.

---
 CHANGES             | 3 +++
 bin/dig/dig.c       | 2 +-
 bin/dig/dig.docbook | 6 ++++--
 bin/dig/dighost.c   | 8 +++++---
 4 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/CHANGES b/CHANGES
index 535669948b..53bf0b65f4 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+5237.	[bug]		Recurse to find the root server list with 'dig +trace'.
+			[GL #1028]
+
 5236.	[func]		Add SipHash 2-4 implementation in lib/isc/siphash.c
 			and switch isc_hash_function() to use SipHash 2-4.
 			[GL #605]
diff --git a/bin/dig/dig.c b/bin/dig/dig.c
index afaf3e76d3..8b11e035b6 100644
--- a/bin/dig/dig.c
+++ b/bin/dig/dig.c
@@ -1462,7 +1462,7 @@ plus_option(char *option, bool is_batchfile,
 				lookup->trace = state;
 				lookup->trace_root = state;
 				if (state) {
-					lookup->recurse = false;
+					lookup->recurse = true;
 					lookup->identify = true;
 					lookup->comments = false;
 					lookup->rrcomments = 0;
diff --git a/bin/dig/dig.docbook b/bin/dig/dig.docbook
index e401442716..0e5e374a0d 100644
--- a/bin/dig/dig.docbook
+++ b/bin/dig/dig.docbook
@@ -1010,8 +1010,10 @@
 	      in the query.  This bit is set by default, which means
 	      <command>dig</command> normally sends recursive
 	      queries.  Recursion is automatically disabled when
-	      the <parameter>+nssearch</parameter> or
-	      <parameter>+trace</parameter> query options are used.
+	      using the <parameter>+nssearch</parameter> option, and
+	      when using <parameter>+trace</parameter> except for
+	      an initial recursive query to get the list of root
+	      servers.
 	    </para>
 	  </listitem>
 	</varlistentry>
diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index a7ea342670..c3e553b7ab 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -2191,12 +2191,14 @@ setup_lookup(dig_lookup_t *lookup) {
 	lookup->sendmsg->id = (dns_messageid_t)isc_random16();
 	lookup->sendmsg->opcode = lookup->opcode;
 	lookup->msgcounter = 0;
+
 	/*
-	 * If this is a trace request, completely disallow recursion, since
-	 * it's meaningless for traces.
+	 * If this is a trace request, completely disallow recursion after
+	 * looking up the root name servers, since it's meaningless for traces.
 	 */
-	if (lookup->trace || (lookup->ns_search_only && !lookup->trace_root))
+	if ((lookup->trace || lookup->ns_search_only) && !lookup->trace_root) {
 		lookup->recurse = false;
+	}
 
 	if (lookup->recurse &&
 	    lookup->rdtype != dns_rdatatype_axfr &&