From: Michał Kępień <michal@isc.org>
Date: Fri, 28 Jun 2019 10:12:46 +0000 (+0200)
Subject: dnstap-read: clear buffer before expanding it
X-Git-Tag: v9.11.9~10^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=511f3c360182b6adbe753ed8dd70add2c109714c;p=thirdparty%2Fbind9.git

dnstap-read: clear buffer before expanding it

When printing a packet, dnstap-read checks whether its text form takes
up more than the 2048 bytes allocated for the output buffer by default.
If that is the case, the output buffer is automatically expanded, but
the truncated output is left in the buffer, resulting in malformed data
being printed.  Clear the output buffer before expanding it to prevent
this issue from occurring.

(cherry picked from commit 3549abe81df2a8a2757c37990e19db213725878e)
---

diff --git a/bin/tests/system/dnstap/README b/bin/tests/system/dnstap/README
new file mode 100644
index 00000000000..f4cb38569a1
--- /dev/null
+++ b/bin/tests/system/dnstap/README
@@ -0,0 +1,20 @@
+Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+
+See COPYRIGHT in the source root or http://isc.org/copyright.html for terms.
+
+The "large-answer.fstrm" file was generated by configuring a named instance
+compiled with --enable-dnstap and --enable-fixed-rrset with the following
+directives:
+
+    minimal-responses yes;
+    rrset-order { order fixed; };
+    dnstap { auth response; };
+    dnstap-identity none;
+    dnstap-output file "large-answer.fstrm";
+
+The captured RRset from the "example." zone was created using:
+
+    $GENERATE 1-48 @ IN A 127.0.0.$
+
+A server instance set up this way was then queried non-recursively (RD=0) for
+"example/A".
diff --git a/bin/tests/system/dnstap/large-answer.fstrm b/bin/tests/system/dnstap/large-answer.fstrm
new file mode 100644
index 00000000000..873b3159c07
Binary files /dev/null and b/bin/tests/system/dnstap/large-answer.fstrm differ
diff --git a/bin/tests/system/dnstap/tests.sh b/bin/tests/system/dnstap/tests.sh
index 3e3aaa918d8..b46fb929de2 100644
--- a/bin/tests/system/dnstap/tests.sh
+++ b/bin/tests/system/dnstap/tests.sh
@@ -587,5 +587,14 @@ if [ -n "$FSTRM_CAPTURE" ] ; then
 	}
 fi
 
+echo_i "checking large packet printing"
+ret=0
+# Expect one occurrence of "opcode: QUERY" below "reponse_message_data" and
+# another one below "response_message".
+lines=`$DNSTAPREAD -y large-answer.fstrm | grep -c "opcode: QUERY"`
+[ $lines -eq 2 ] || ret=1
+if [ $ret != 0 ]; then echo_i "failed"; fi
+status=`expr $status + $ret`
+
 echo_i "exit status: $status"
 [ $status -eq 0 ] || exit 1
diff --git a/bin/tools/dnstap-read.c b/bin/tools/dnstap-read.c
index 49dbb9b5c0b..70ae7ebeb3a 100644
--- a/bin/tools/dnstap-read.c
+++ b/bin/tools/dnstap-read.c
@@ -127,6 +127,7 @@ print_packet(dns_dtdata_t *dt, const dns_master_style_t *style) {
 
 			result = dns_message_totext(dt->msg, style, 0, b);
 			if (result == ISC_R_NOSPACE) {
+				isc_buffer_clear(b);
 				textlen *= 2;
 				continue;
 			} else if (result == ISC_R_SUCCESS) {
diff --git a/util/copyrights b/util/copyrights
index 10ba42a4690..7fae33a59ca 100644
--- a/util/copyrights
+++ b/util/copyrights
@@ -1197,6 +1197,7 @@
 ./bin/tests/system/dnssec/signer/remove.db.in	ZONE	2016,2018,2019
 ./bin/tests/system/dnssec/signer/remove2.db.in	ZONE	2016,2018,2019
 ./bin/tests/system/dnssec/tests.sh		SH	2000,2001,2002,2004,2005,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019
+./bin/tests/system/dnstap/README		TXT.BRIEF	2019
 ./bin/tests/system/dnstap/bad-fstrm-set-buffer-hint-max.conf	CONF-C	2016,2018,2019
 ./bin/tests/system/dnstap/bad-fstrm-set-buffer-hint-min.conf	CONF-C	2016,2018,2019
 ./bin/tests/system/dnstap/bad-fstrm-set-flush-timeout-max.conf	CONF-C	2016,2018,2019
@@ -1218,6 +1219,7 @@
 ./bin/tests/system/dnstap/good-fstrm-set-output-queue-model-spsc.conf	CONF-C	2016,2018,2019
 ./bin/tests/system/dnstap/good-fstrm-set-output-queue-size.conf	CONF-C	2016,2018,2019
 ./bin/tests/system/dnstap/good-fstrm-set-reopen-interval.conf	CONF-C	2016,2018,2019
+./bin/tests/system/dnstap/large-answer.fstrm	X	2019
 ./bin/tests/system/dnstap/ns1/named.conf.in	CONF-C	2018,2019
 ./bin/tests/system/dnstap/ns1/root.db		ZONE	2015,2016,2018,2019
 ./bin/tests/system/dnstap/ns2/example.db	ZONE	2015,2016,2018,2019