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 (file)
index 0000000..f4cb385
--- /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 (file)
index 0000000..873b315
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 13969950262f7901e7cbff41178b7698e5670838..83877b102f229e1a3c914c1705cd92d4f99c57c1 100644 (file)
--- a/bin/tests/system/dnstap/tests.sh
+++ b/bin/tests/system/dnstap/tests.sh
@@ -736,5 +736,14 @@ EOF
        status=`expr $status + $ret`
 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 899a0bf1dac87b4e1879841dc5b1bf5b6c8fd0a2..e6b939c85dfbe4909830a3856f260fdb8203be0b 100644 (file)
--- a/bin/tools/dnstap-read.c
+++ b/bin/tools/dnstap-read.c
@@ -157,6 +157,7 @@ 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 bbcddfed64a42d67825b3ed27617bd17bae95c00..2f47ad9ce149512b80638b7976797a7abee583d3 100644 (file)
--- a/util/copyrights
+++ b/util/copyrights
@@ -558,7 +558,9 @@
 ./bin/tests/system/dnssec/signer/general/bogus-ksk.key X       2018,2019
 ./bin/tests/system/dnssec/signer/general/bogus-zsk.key X       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/clean.sh             SH      2015,2016,2017,2018,2019
+./bin/tests/system/dnstap/large-answer.fstrm   X       2019
 ./bin/tests/system/dnstap/setup.sh             SH      2018,2019
 ./bin/tests/system/dnstap/tests.sh             SH      2015,2016,2017,2018,2019
 ./bin/tests/system/dnstap/ydump.py             PYTHON  2016,2017,2018,2019