[master] Rename nsec3param_salt_totext() to dns_nsec3param_salttotext(), make it public, add unit tests

4786.	[cleanup]	Turn nsec3param_salt_totext() into a public function,
			dns_nsec3param_salttotext(), and add unit tests for it.
			[RT #46289]

lib/dns/tests/nsec3_test.c

@@ -43,6 +43,82 @@ iteration_test(const char *file, unsigned int expected) {
 	dns_db_detach(&db);
 }
 
+/*%
+ * Structure containing parameters for nsec3param_salttotext_test().
+ */
+typedef struct {
+	const char *nsec3param_text;	/* NSEC3PARAM RDATA in text form */
+	const char *expected_salt;	/* string expected in target buffer */
+} nsec3param_salttotext_test_params_t;
+
+/*%
+ * Check whether dns_nsec3param_salttotext() handles supplied text form
+ * NSEC3PARAM RDATA correctly: test whether the result of calling the former is
+ * as expected and whether it properly checks available buffer space.
+ *
+ * Assumes supplied text form NSEC3PARAM RDATA is valid as testing handling of
+ * invalid NSEC3PARAM RDATA is out of scope of this unit test.
+ */
+static void
+nsec3param_salttotext_test(const nsec3param_salttotext_test_params_t *params) {
+	dns_rdata_t rdata = DNS_RDATA_INIT;
+	dns_rdata_nsec3param_t nsec3param;
+	unsigned char buf[1024];
+	isc_result_t result;
+	char salt[64];
+	size_t length;
+
+	/*
+	 * Prepare a dns_rdata_nsec3param_t structure for testing.
+	 */
+	result = dns_test_rdata_fromstring(&rdata, dns_rdataclass_in,
+					   dns_rdatatype_nsec3param, buf,
+					   sizeof(buf),
+					   params->nsec3param_text);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+	result = dns_rdata_tostruct(&rdata, &nsec3param, NULL);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	/*
+	 * Check typical use.
+	 */
+	result = dns_nsec3param_salttotext(&nsec3param, salt, sizeof(salt));
+	ATF_CHECK_EQ_MSG(result, ISC_R_SUCCESS,
+			 "\"%s\": expected success, got %s\n",
+			 params->nsec3param_text, isc_result_totext(result));
+	ATF_CHECK_EQ_MSG(strcmp(salt, params->expected_salt), 0,
+			 "\"%s\": expected salt \"%s\", got \"%s\"",
+			 params->nsec3param_text, params->expected_salt, salt);
+
+	/*
+	 * Ensure available space in the buffer is checked before the salt is
+	 * printed to it and that the amount of space checked for includes the
+	 * terminating NULL byte.
+	 */
+	length = strlen(params->expected_salt);
+	ATF_REQUIRE(length < sizeof(salt) - 1);	/* prevent buffer overwrite */
+	ATF_REQUIRE(length > 0U);		/* prevent length underflow */
+
+	result = dns_nsec3param_salttotext(&nsec3param, salt, length - 1);
+	ATF_CHECK_EQ_MSG(result, ISC_R_NOSPACE,
+			 "\"%s\": expected a %lu-byte target buffer to be "
+			 "rejected, got %s\n",
+			 params->nsec3param_text, length - 1,
+			 isc_result_totext(result));
+	result = dns_nsec3param_salttotext(&nsec3param, salt, length);
+	ATF_CHECK_EQ_MSG(result, ISC_R_NOSPACE,
+			 "\"%s\": expected a %lu-byte target buffer to be "
+			 "rejected, got %s\n",
+			 params->nsec3param_text, length,
+			 isc_result_totext(result));
+	result = dns_nsec3param_salttotext(&nsec3param, salt, length + 1);
+	ATF_CHECK_EQ_MSG(result, ISC_R_SUCCESS,
+			 "\"%s\": expected a %lu-byte target buffer to be "
+			 "accepted, got %s\n",
+			 params->nsec3param_text, length + 1,
+			 isc_result_totext(result));
+}
+
 /*
  * Individual unit tests
  */
@@ -68,6 +144,40 @@ ATF_TC_BODY(max_iterations, tc) {
 
 	dns_test_end();
 }
+
+ATF_TC(nsec3param_salttotext);
+ATF_TC_HEAD(nsec3param_salttotext, tc) {
+	atf_tc_set_md_var(tc, "descr", "check dns_nsec3param_salttotext()");
+}
+ATF_TC_BODY(nsec3param_salttotext, tc) {
+	isc_result_t result;
+	size_t i;
+
+	const nsec3param_salttotext_test_params_t tests[] = {
+		/*
+		 * Tests with non-empty salts.
+		 */
+		{ "0 0 10 0123456789abcdef", "0123456789ABCDEF" },
+		{ "0 1 11 0123456789abcdef", "0123456789ABCDEF" },
+		{ "1 0 12 42", "42" },
+		{ "1 1 13 42", "42" },
+		/*
+		 * Test with empty salt.
+		 */
+		{ "0 0 0 -", "-" },
+	};
+
+	UNUSED(tc);
+
+	result = dns_test_begin(NULL, ISC_FALSE);
+	ATF_REQUIRE_EQ(result, ISC_R_SUCCESS);
+
+	for (i = 0; i < sizeof(tests) / sizeof(tests[0]); i++) {
+		nsec3param_salttotext_test(&tests[i]);
+	}
+
+	dns_test_end();
+}
 #else
 ATF_TC(untested);
 ATF_TC_HEAD(untested, tc) {
@@ -85,6 +195,7 @@ ATF_TC_BODY(untested, tc) {
 ATF_TP_ADD_TCS(tp) {
 #if defined(OPENSSL) || defined(PKCS11CRYPTO)
 	ATF_TP_ADD_TC(tp, max_iterations);
+	ATF_TP_ADD_TC(tp, nsec3param_salttotext);
 #else
 	ATF_TP_ADD_TC(tp, untested);
 #endif