Allow zone names to be generated parametrically

Special tokens can now be specified in a zone "file" option
in order to generate the filename parametrically. The first
instead of "$name" in the "file" option is replaced with the
zone origin, the first instance of "$type" is replaced with the
zone type (i.e., primary, secondary, etc), and the first instance
of "$view" is replaced with the view name..

This simplifies the creation of zones using initial-file templates.
For example:

   $ rndc addzone <zonename> \
     { type primary; file "$name.db"; initial-file "template.db"

bin/tests/system/masterfile/ns2/named.conf.j2

@@ -36,12 +36,12 @@ zone "." {
 
 zone "example" {
 	type primary;
-	file "example.db";
+	file "$name.db";
 };
 
 zone "missing" {
 	type primary;
-	file "missing.db";
+	file "$name.db";
 };
 
 zone "initial" {

doc/arm/reference.rst

@@ -7132,13 +7132,21 @@ Zone Options
    :tags: zone
    :short: Specifies the zone's filename.
 
-   This sets the zone's filename. In :any:`primary <type primary>`, :any:`hint <type hint>`, and :any:`redirect <type redirect>`
+   This sets the zone's filename. In :any:`primary <type primary>`,
+   :any:`hint <type hint>`, and :any:`redirect <type redirect>`
    zones which do not have :any:`primaries` defined, zone data is loaded from
    this file. In :any:`secondary <type secondary>`, :any:`mirror <type mirror>`, :any:`stub <type stub>`, and :any:`redirect <type redirect>` zones
    which do have :any:`primaries` defined, zone data is retrieved from
    another server and saved in this file. This option is not applicable
    to other zone types.
 
+   The filename can be generated parametrically by including special
+   tokens in the string: the first instance of ``$name`` in the string
+   is replaced with the zone name in lower case; the first instance of
+   ``$type`` is replaced with the zone type -- i.e., ``primary``,
+   ``secondary``, etc); and the first instance of ``$view`` is replaced
+   with the view name. These tokens are case-insensitive.
+
 :any:`forward`
    This option is only meaningful if the zone has a forwarders list. The ``only`` value
    causes the lookup to fail after trying the forwarders and getting no
@@ -7163,10 +7171,12 @@ Zone Options
    ::
 
       $ rndc addzone example.com \
-        '{ type primary; file "example.db"; initial-file "template.db"; };'
+        '{ type primary; file "$name.db"; initial-file "template.db"; };'
 
-    Using "@" to reference the zone origin name within ``template.db``
-    allows the same file to be used with multiple zones, as in:
+    This creates a zone ``example.com``, with filename ``example.com.db``.
+
+    Using "@" to reference the zone origin within the initial file
+    allows the same file to be used for multiple zones, as in:
 
     ::
 

lib/dns/zone.c

@@ -1797,6 +1797,108 @@ setstring(dns_zone_t *zone, char **field, const char *value) {
 	*field = copy;
 }
 
+static int
+position_order(const void *a, const void *b) {
+	/* sort char pointers in order of which occurs first in memory */
+	return (char *)*(char **)a - (char *)*(char **)b;
+}
+
+static isc_result_t
+putmem(isc_buffer_t *b, const char *base, size_t length) {
+	size_t space = isc_buffer_availablelength(b) - 1;
+	if (space < length) {
+		isc_buffer_putmem(b, (const unsigned char *)base, space);
+		return ISC_R_NOSPACE;
+	}
+
+	isc_buffer_putmem(b, (const unsigned char *)base, length);
+	return ISC_R_SUCCESS;
+}
+
+/*
+ * Set the masterfile field, expanding $name to the zone name,
+ * $type to the zone type, and $view to the view name. Cap the
+ * length at PATH_MAX.
+ */
+static void
+setfilename(dns_zone_t *zone, char **field, const char *value) {
+	isc_result_t result;
+	char *t = NULL, *n = NULL, *v = NULL;
+	char *positions[3];
+	char filename[PATH_MAX];
+	isc_buffer_t b;
+	size_t tags = 0;
+
+	if (value == NULL) {
+		*field = NULL;
+		return;
+	}
+
+	t = strcasestr(value, "$type");
+	if (t != NULL) {
+		positions[tags++] = t;
+	}
+
+	n = strcasestr(value, "$name");
+	if (n != NULL) {
+		positions[tags++] = n;
+	}
+
+	v = strcasestr(value, "$view");
+	if (v != NULL) {
+		positions[tags++] = v;
+	}
+
+	if (tags == 0) {
+		setstring(zone, field, value);
+		return;
+	}
+
+	isc_buffer_init(&b, filename, sizeof(filename));
+
+	/* sort the tag offsets in order of occurrence */
+	qsort(positions, tags, sizeof(char *), position_order);
+
+	const char *p = value;
+	for (size_t i = 0; i < tags; i++) {
+		size_t tokenlen = 0;
+
+		CHECK(putmem(&b, p, (positions[i] - p)));
+
+		p = positions[i];
+		INSIST(p != NULL);
+		if (p == n) {
+			dns_fixedname_t fn;
+			dns_name_t *name = dns_fixedname_initname(&fn);
+			char namebuf[DNS_NAME_FORMATSIZE];
+
+			result = dns_name_downcase(&zone->origin, name);
+			RUNTIME_CHECK(result == ISC_R_SUCCESS);
+			dns_name_format(name, namebuf, sizeof(namebuf));
+			CHECK(putmem(&b, namebuf, strlen(namebuf)));
+			tokenlen = 5; /* "$name" */
+		} else if (p == t) {
+			const char *typename = dns_zonetype_name(zone->type);
+			CHECK(putmem(&b, typename, strlen(typename)));
+			tokenlen = 5; /* "$type" */
+		} else if (p == v) {
+			CHECK(putmem(&b, zone->view->name,
+				     strlen(zone->view->name)));
+			tokenlen = 5; /* "$view" */
+		}
+
+		/* Advance the input pointer past the token */
+		p += tokenlen;
+	}
+
+	const char *end = value + strlen(value);
+	putmem(&b, p, end - p);
+
+failure:
+	isc_buffer_putuint8(&b, 0);
+	setstring(zone, field, filename);
+}
+
 void
 dns_zone_setfile(dns_zone_t *zone, const char *file, const char *initial_file,
 		 dns_masterformat_t format, const dns_master_style_t *style) {
@@ -1804,7 +1906,7 @@ dns_zone_setfile(dns_zone_t *zone, const char *file, const char *initial_file,
 	REQUIRE(zone->stream == NULL);
 
 	LOCK_ZONE(zone);
-	setstring(zone, &zone->masterfile, file);
+	setfilename(zone, &zone->masterfile, file);
 	setstring(zone, &zone->initfile, initial_file);
 	zone->masterformat = format;
 	if (format == dns_masterformat_text) {

tests/dns/Makefile.am

@@ -51,6 +51,7 @@ check_PROGRAMS =		\
 	transport_test		\
 	tsig_test		\
 	update_test		\
+	zonefile_test		\
 	zonemgr_test		\
 	zt_test
 

tests/dns/zonefile_test.c

@@ -0,0 +1,121 @@
+/*
+ * 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 <inttypes.h>
+#include <sched.h> /* IWYU pragma: keep */
+#include <setjmp.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#define UNIT_TESTING
+#include <cmocka.h>
+
+#include <isc/atomic.h>
+#include <isc/lib.h>
+
+#include <dns/lib.h>
+#include <dns/view.h>
+
+#include <tests/dns.h>
+
+typedef struct {
+	const char *input, *expected;
+} zonefile_test_params_t;
+
+static int
+setup_test(void **state) {
+	setup_loopmgr(state);
+	return 0;
+}
+
+static int
+teardown_test(void **state) {
+	teardown_loopmgr(state);
+	return 0;
+}
+
+ISC_LOOP_TEST_IMPL(filename) {
+	isc_result_t result;
+	dns_zone_t *zone = NULL;
+	const zonefile_test_params_t tests[] = {
+		{ "$name", "example.com" },
+		{ "$name.db", "example.com.db" },
+		{ "./dir/$name.db", "./dir/example.com.db" },
+		{ "$type", "primary" },
+		{ "$type-file", "primary-file" },
+		{ "./dir/$type", "./dir/primary" },
+		{ "./$type/$name.db", "./primary/example.com.db" },
+		{ "./$TyPe/$NAmE.db", "./primary/example.com.db" },
+		{ "./$name/$type", "./example.com/primary" },
+		{ "$name.$type", "example.com.primary" },
+		{ "$type$name", "primaryexample.com" },
+		{ "$type$type", "primary$type" },
+		{ "$name$name", "example.com$name" },
+		{ "typename", "typename" },
+		{ "$view", "local" },
+		{ "./$type/$view-$name.db", "./primary/local-example.com.db" },
+		{ "./$view/$type-$name.db", "./local/primary-example.com.db" },
+		{ "./$name/$view-$type.db", "./example.com/local-primary.db" },
+		{ "", "" },
+	};
+
+	dns_view_t *view = NULL;
+	result = dns_test_makeview("local", false, false, &view);
+	assert_int_equal(result, ISC_R_SUCCESS);
+
+	/* use .COM here to test that the name is correctly downcased */
+	result = dns_test_makezone("example.COM", &zone, view, false);
+	assert_int_equal(result, ISC_R_SUCCESS);
+
+	dns_zone_setview(zone, view);
+	dns_view_detach(&view);
+
+	for (size_t i = 0; i < ARRAY_SIZE(tests); i++) {
+		dns_zone_setfile(zone, tests[i].input, NULL,
+				 dns_masterformat_text,
+				 &dns_master_style_default);
+		assert_string_equal(dns_zone_getfile(zone), tests[i].expected);
+	}
+
+	/* test PATH_MAX overrun */
+	char longname[PATH_MAX] = { 0 };
+	memset(longname, 'x', sizeof(longname) - 1);
+	dns_zone_setfile(zone, longname, NULL, dns_masterformat_text,
+			 &dns_master_style_default);
+	assert_string_equal(dns_zone_getfile(zone), longname);
+
+	/*
+	 * overwrite the beginning of the long name with $name. when
+	 * it's expanded to the zone name, the resulting string should
+	 * still be capped at PATH_MAX characters.
+	 */
+	memmove(longname, "$name", 5);
+	dns_zone_setfile(zone, longname, NULL, dns_masterformat_text,
+			 &dns_master_style_default);
+	assert_int_equal(strlen(longname), PATH_MAX - 1);
+	memmove(longname, "example.com", 11);
+	assert_string_equal(dns_zone_getfile(zone), longname);
+
+	dns_zone_detach(&zone);
+	isc_loopmgr_shutdown(loopmgr);
+}
+
+ISC_TEST_LIST_START
+ISC_TEST_ENTRY_CUSTOM(filename, setup_test, teardown_test)
+ISC_TEST_LIST_END
+
+ISC_TEST_MAIN