From ec17868a648604599fbf85899e1c7a68a4dcfabd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Vavru=C5=A1a?= <marek.vavrusa@nic.cz>
Date: Mon, 9 Feb 2015 19:14:31 +0100
Subject: [PATCH] lib: requery when nameserver returns (falsely) NXDOMAIN
---
lib/layer/iterate.c | 9 +-
tests/testdata/iter_minim_a_nxdomain.rpl | 107 +++++++++++++++++++++++
2 files changed, 112 insertions(+), 4 deletions(-)
create mode 100644 tests/testdata/iter_minim_a_nxdomain.rpl
diff --git a/lib/layer/iterate.c b/lib/layer/iterate.c
index e30089f0f..19c5434d6 100644
--- a/lib/layer/iterate.c
+++ b/lib/layer/iterate.c
@@ -209,11 +209,13 @@ static int process_answer(knot_pkt_t *pkt, struct kr_layer_param *param)
/* Response for minimized QNAME.
* NODATA => may be empty non-terminal, retry (found zone cut)
* NOERROR => found zone cut, retry
- * NXDOMAIN => parent is zone cut, terminate
+ * NXDOMAIN => parent is zone cut, retry as a workaround for bad authoritatives
*/
+ const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
bool is_minimized = (!knot_dname_is_equal(knot_pkt_qname(pkt), query->sname));
- bool is_noerror = (knot_wire_get_rcode(pkt->wire) == KNOT_RCODE_NOERROR);
- if (is_minimized && is_noerror) {
+ bool is_nodata = (knot_wire_get_rcode(pkt->wire) == KNOT_RCODE_NOERROR) && !an->count;
+ bool is_nxdomain = (knot_wire_get_rcode(pkt->wire) == KNOT_RCODE_NXDOMAIN);
+ if (is_minimized && (is_nodata || is_nxdomain)) {
query->flags |= QUERY_NO_MINIMIZE;
return KNOT_NS_PROC_DONE;
}
@@ -227,7 +229,6 @@ static int process_answer(knot_pkt_t *pkt, struct kr_layer_param *param)
/* Process answer section records. */
const knot_dname_t *cname = query->sname;
- const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
for (unsigned i = 0; i < an->count; ++i) {
const knot_rrset_t *rr = knot_pkt_rr(an, i);
int state = callback(rr, 0, param);
diff --git a/tests/testdata/iter_minim_a_nxdomain.rpl b/tests/testdata/iter_minim_a_nxdomain.rpl
new file mode 100644
index 000000000..cca9fa1e6
--- /dev/null
+++ b/tests/testdata/iter_minim_a_nxdomain.rpl
@@ -0,0 +1,107 @@
+; config options
+server:
+ target-fetch-policy: "0 0 0 0 0"
+ query-minimization: on
+
+stub-zone:
+ name: "."
+ stub-addr: 193.0.14.129 # K.ROOT-SERVERS.NET.
+CONFIG_END
+
+SCENARIO_BEGIN Test basic query minimization sub.www.example.com. when NS doesn't show empty non-terminal.
+
+; K.ROOT-SERVERS.NET.
+RANGE_BEGIN 0 100
+ ADDRESS 193.0.14.129
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+. IN NS
+SECTION ANSWER
+. IN NS K.ROOT-SERVERS.NET.
+SECTION ADDITIONAL
+K.ROOT-SERVERS.NET. IN A 193.0.14.129
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+com. IN NS
+SECTION AUTHORITY
+com. IN NS a.gtld-servers.net.
+SECTION ADDITIONAL
+a.gtld-servers.net. IN A 192.5.6.30
+ENTRY_END
+RANGE_END
+
+; a.gtld-servers.net.
+RANGE_BEGIN 0 100
+ ADDRESS 192.5.6.30
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+example.com. IN NS
+SECTION AUTHORITY
+example.com. IN NS ns.example.com.
+SECTION ADDITIONAL
+ns.example.com. IN A 1.2.3.4
+ENTRY_END
+RANGE_END
+
+; ns.example.com.
+RANGE_BEGIN 0 100
+ ADDRESS 1.2.3.4
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NXDOMAIN
+SECTION QUESTION
+www.example.com. IN NS
+SECTION ANSWER
+SECTION AUTHORITY
+example.com. IN NS ns.example.com.
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+sub.www.example.com. IN A
+SECTION ANSWER
+sub.www.example.com. IN A 10.20.30.40
+SECTION AUTHORITY
+example.com. IN NS ns.example.com.
+SECTION ADDITIONAL
+ns.example.com. IN A 1.2.3.4
+ENTRY_END
+
+RANGE_END
+
+STEP 1 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+sub.www.example.com. IN A
+ENTRY_END
+
+; recursion happens here.
+STEP 10 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+sub.www.example.com. IN A
+SECTION ANSWER
+sub.www.example.com. IN A 10.20.30.40
+ENTRY_END
+
+SCENARIO_END
--
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