Merge in a commit from upstream..

- Fix 0x20 capsforid fallback to omit gratuitous NS and additional
  section changes.

ok sthen@

3 files changed, 48 insertions, 0 deletions

diff --git a/usr.sbin/unbound/iterator/iter_utils.c b/usr.sbin/unbound/iterator/iter_utils.c
index 9d0aa698f99..10ae12f75c6 100644
--- a/usr.sbin/unbound/iterator/iter_utils.c
+++ b/usr.sbin/unbound/iterator/iter_utils.c
@@ -715,6 +715,42 @@ reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region)
 }
 
 void 
+caps_strip_reply(struct reply_info* rep)
+{
+	size_t i;
+	if(!rep) return;
+	/* see if message is a referral, in which case the additional and
+	 * NS record cannot be removed */
+	/* referrals have the AA flag unset (strict check, not elsewhere in
+	 * unbound, but for 0x20 this is very convenient). */
+	if(!(rep->flags&BIT_AA))
+		return;
+	/* remove the additional section from the reply */
+	if(rep->ar_numrrsets != 0) {
+		verbose(VERB_ALGO, "caps fallback: removing additional section");
+		rep->rrset_count -= rep->ar_numrrsets;
+		rep->ar_numrrsets = 0;
+	}
+	/* is there an NS set in the authority section to remove? */
+	/* the failure case (Cisco firewalls) only has one rrset in authsec */
+	for(i=rep->an_numrrsets; i<rep->an_numrrsets+rep->ns_numrrsets; i++) {
+		struct ub_packed_rrset_key* s = rep->rrsets[i];
+		if(ntohs(s->rk.type) == LDNS_RR_TYPE_NS) {
+			/* remove NS rrset and break from loop (loop limits
+			 * have changed) */
+			/* move last rrset into this position (there is no
+			 * additional section any more) */
+			verbose(VERB_ALGO, "caps fallback: removing NS rrset");
+			if(i < rep->rrset_count-1)
+				rep->rrsets[i]=rep->rrsets[rep->rrset_count-1];
+			rep->rrset_count --;
+			rep->ns_numrrsets --;
+			break;
+		}
+	}
+}
+
+void 
 iter_store_parentside_rrset(struct module_env* env, 
 	struct ub_packed_rrset_key* rrset)
 {
diff --git a/usr.sbin/unbound/iterator/iter_utils.h b/usr.sbin/unbound/iterator/iter_utils.h
index d7c2b68afa2..9373487e002 100644
--- a/usr.sbin/unbound/iterator/iter_utils.h
+++ b/usr.sbin/unbound/iterator/iter_utils.h
@@ -223,6 +223,15 @@ int iter_msg_from_zone(struct dns_msg* msg, struct delegpt* dp,
 int reply_equal(struct reply_info* p, struct reply_info* q, struct regional* region);
 
 /**
+ * Remove unused bits from the reply if possible.
+ * So that caps-for-id (0x20) fallback is more likely to be successful.
+ * This removes like, the additional section, and NS record in the authority
+ * section if those records are gratuitous (not for a referral).
+ * @param rep: the reply to strip stuff out of.
+ */
+void caps_strip_reply(struct reply_info* rep);
+
+/**
  * Store parent-side rrset in seperate rrset cache entries for later 
  * last-resort * lookups in case the child-side versions of this information 
  * fails.
diff --git a/usr.sbin/unbound/iterator/iterator.c b/usr.sbin/unbound/iterator/iterator.c
index 6e05c99a0e9..21ef397f1c9 100644
--- a/usr.sbin/unbound/iterator/iterator.c
+++ b/usr.sbin/unbound/iterator/iterator.c
@@ -2878,6 +2878,9 @@ process_response(struct module_qstate* qstate, struct iter_qstate* iq,
 			iq->response->rep);
 	
 	if(event == module_event_capsfail || iq->caps_fallback) {
+		/* for fallback we care about main answer, not additionals */
+		/* removing that makes comparison more likely to succeed */
+		caps_strip_reply(iq->response->rep);
 		if(!iq->caps_fallback) {
 			/* start fallback */
 			iq->caps_fallback = 1;