Add dns_master_loadbuffer() fuzzer

Corpus focuses on "extra" things in master files like $GENERATE etc.
Text encoding for RRs is thoroughly tested in dns_rdata_fromtext
fuzzer.

fuzz/.gitignore

@@ -1,5 +1,6 @@
 /*.dSYM/
 /*.out/
+/dns_master_load
 /dns_message_parse
 /dns_name_fromtext_target
 /dns_rdata_fromwire_text

fuzz/Makefile.am

@@ -19,6 +19,7 @@ libfuzzmain_la_SOURCES =		\
 	main.c
 
 check_PROGRAMS =			\
+	dns_master_load			\
 	dns_message_parse		\
 	dns_name_fromtext_target	\
 	dns_rdata_fromwire_text		\
@@ -26,6 +27,7 @@ check_PROGRAMS =			\
 	isc_lex_gettoken
 
 EXTRA_DIST =				\
+	dns_master_load.in		\
 	dns_message_parse.in		\
 	dns_name_fromtext_target.in	\
 	dns_rdata_fromwire_text.in	\

fuzz/dns_master_load.c

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include <isc/buffer.h>
+#include <isc/mem.h>
+#include <isc/util.h>
+
+#include <dns/callbacks.h>
+#include <dns/db.h>
+#include <dns/master.h>
+#include <dns/types.h>
+
+#include "fuzz.h"
+
+bool debug = false;
+
+int
+LLVMFuzzerInitialize(int *argc, char ***argv) {
+	UNUSED(argc);
+	UNUSED(argv);
+	return (0);
+}
+
+int
+LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+	isc_buffer_t buf;
+	isc_result_t result;
+	isc_mem_t *mctx = NULL;
+
+	isc_buffer_constinit(&buf, data, size);
+	isc_buffer_add(&buf, size);
+	isc_buffer_setactive(&buf, size);
+
+	dns_rdatacallbacks_t callbacks;
+	dns_rdatacallbacks_init(&callbacks);
+	dns_db_t *db = NULL;
+
+	isc_mem_create(&mctx);
+	result = dns_db_create(mctx, "rbt", dns_rootname, dns_dbtype_zone,
+			       dns_rdataclass_in, 0, NULL, &db);
+	if (result != ISC_R_SUCCESS) {
+		return 0;
+	}
+
+	result = dns_db_beginload(db, &callbacks);
+	if (result != ISC_R_SUCCESS) {
+		goto end;
+	}
+
+	result = dns_master_loadbuffer(&buf, &db->origin, &db->origin,
+				       db->rdclass, DNS_MASTER_ZONE, &callbacks,
+				       db->mctx);
+	if (debug) {
+		fprintf(stderr, "loadbuffer: %s\n", isc_result_totext(result));
+	}
+	result = dns_db_endload(db, &callbacks);
+	if (debug) {
+		fprintf(stderr, "endload: %s\n", isc_result_totext(result));
+	}
+
+end:
+	dns_db_detach(&db);
+	isc_mem_destroy(&mctx);
+	return (0);
+}

fuzz/dns_master_load.in/date.db

@@ -0,0 +1,21 @@
+$TTL 300	; 5 minutes
+@			SOA	mname1. . (
+				2000062101 ; serial
+				20         ; refresh (20 seconds)
+				20         ; retry (20 seconds)
+				1814400    ; expire (3 weeks)
+				3600       ; minimum (1 hour)
+				)
+			NS	a1
+$DATE 20210101000000
+
+a1		123	A	\# 4 0A000001
+a2		456	A	\# 4 0A000001
+
+txt1			TXT	\# 6 0568656C6C6F
+txt2			TXT	"hello"
+txt3			TXT	\# 6 0568656C6C6F
+txt4			TXT	"hello"
+
+unk1                    TYPE123 \# 1 00
+unk2            	TYPE123 \# 1 00

fuzz/dns_master_load.in/generate.db

@@ -0,0 +1,10 @@
+$ORIGIN .
+$TTL	120
+@		SOA	tld4.  hostmaster.ns.tld4. ( 1 3600 1200 604800 60 )
+		NS	ns
+ns		A	10.53.0.2
+$GENERATE 11-18 all$.a9 A 192.0.2.8
+$GENERATE 1-2 @ PTR SERVER$.EXAMPLE.
+$GENERATE 1-7 $ CNAME $.0
+$GENERATE 17-27 HOST-$ A 1.2.3.$
+$GENERATE 277-288 HOST-$ MX "0 ."

fuzz/dns_master_load.in/include.db

@@ -0,0 +1,8 @@
+$ORIGIN .
+$TTL	120
+@		SOA	tld4.  hostmaster.ns.tld4. ( 1 3600 1200 604800 60 )
+		NS	ns
+ns		A	10.53.0.2
+$INCLUDE withoutorigin
+$INCLUDE withoutorigin origin
+

fuzz/dns_master_load.in/minimal.db

@@ -0,0 +1,4 @@
+.	SOA ns1. hostmaster.warn.example. (
+	    1 3600 1200 604800 3600 )
+	NS  ns1.
+ns1. 555 IN A 10.53.0.1