From: Kees Monshouwer <mind04@monshouwer.org>
Date: Tue, 4 Jun 2019 18:02:24 +0000 (+0200)
Subject: auth: always truncate when the additional records do not fit
X-Git-Tag: dnsdist-1.4.0-beta1~2^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=06ba4702400afc4eb2983f768495aa71d55c5713;p=thirdparty%2Fpdns.git

auth: always truncate when the additional records do not fit
in a response
fixes #7315
---

diff --git a/pdns/dnspacket.cc b/pdns/dnspacket.cc
index c7f3070338..ac752f506f 100644
--- a/pdns/dnspacket.cc
+++ b/pdns/dnspacket.cc
@@ -340,10 +340,8 @@ void DNSPacket::wrapup()
         pos->dr.d_content->toPacket(pw);
         if(pw.size() + optsize > (d_tcp ? 65535 : getMaxReplyLen())) {
           pw.rollback();
-          if(pos->dr.d_place == DNSResourceRecord::ANSWER || pos->dr.d_place == DNSResourceRecord::AUTHORITY) {
-            pw.truncate();
-            pw.getHeader()->tc=1;
-          }
+          pw.truncate();
+          pw.getHeader()->tc=1;
           goto noCommit;
         }
       }
diff --git a/regression-tests/tests/too-big-for-udp-query-no-truncate-additional/command b/regression-tests/tests/too-big-for-udp-query-always-truncate-additional/command
similarity index 100%
rename from regression-tests/tests/too-big-for-udp-query-no-truncate-additional/command
rename to regression-tests/tests/too-big-for-udp-query-always-truncate-additional/command
diff --git a/regression-tests/tests/too-big-for-udp-query-no-truncate-additional/description b/regression-tests/tests/too-big-for-udp-query-always-truncate-additional/description
similarity index 53%
rename from regression-tests/tests/too-big-for-udp-query-no-truncate-additional/description
rename to regression-tests/tests/too-big-for-udp-query-always-truncate-additional/description
index e694a2fcad..b00e0ccc74 100644
--- a/regression-tests/tests/too-big-for-udp-query-no-truncate-additional/description
+++ b/regression-tests/tests/too-big-for-udp-query-always-truncate-additional/description
@@ -1,4 +1,6 @@
 UDP dns packets can only be 512 bytes long - when they are longer, they need
 to get truncated, and have the 'TC' bit set, to inform the client that they
 need to requery over TCP. This query however does not need truncation, since
-the information that causes things to go over limit is 'additional'.
+the information that causes things to go over limit are 'courtesy' additionals.
+But truncation is harmless and will avoid a lot of additional complexity.
+https://tools.ietf.org/html/rfc4472#appendix-B
diff --git a/regression-tests/tests/too-big-for-udp-query-always-truncate-additional/expected_result b/regression-tests/tests/too-big-for-udp-query-always-truncate-additional/expected_result
new file mode 100644
index 0000000000..d714295eca
--- /dev/null
+++ b/regression-tests/tests/too-big-for-udp-query-always-truncate-additional/expected_result
@@ -0,0 +1,2 @@
+Rcode: 0 (No Error), RD: 0, QR: 1, TC: 1, AA: 1, opcode: 0
+Reply to question for qname='together-too-much.example.com.', qtype=MX
diff --git a/regression-tests/tests/too-big-for-udp-query-no-truncate-additional/expected_result b/regression-tests/tests/too-big-for-udp-query-no-truncate-additional/expected_result
deleted file mode 100644
index 99aa1092ad..0000000000
--- a/regression-tests/tests/too-big-for-udp-query-no-truncate-additional/expected_result
+++ /dev/null
@@ -1,29 +0,0 @@
-0	together-too-much.example.com.	IN	MX	120	25 toomuchinfo-X.example.com.
-0	together-too-much.example.com.	IN	MX	120	25 toomuchinfo-X.example.com.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-2	toomuchinfo-X.example.com.	IN	A	120	192.168.99.
-Rcode: 0 (No Error), RD: 0, QR: 1, TC: 0, AA: 1, opcode: 0
-Reply to question for qname='together-too-much.example.com.', qtype=MX