add a node chain traversal mechanism

dns_qp_findname_ancestor() now takes an optional 'chain' parameter;
if set, the dns_qpchain object it points to will be updated with an
array of pointers to the populated nodes between the tree root and the
requested name. the number of nodes in the chain can then be accessed
using dns_qpchain_length() and the individual nodes using
dns_qpchain_node().

tests/bench/qplookups.c

@@ -254,7 +254,7 @@ main(int argc, char **argv) {
 	start = isc_time_monotonic();
 	for (i = 0; i < n; i++) {
 		name = dns_fixedname_name(&items[i]);
-		dns_qp_findname_ancestor(qp, name, 0, NULL, NULL, NULL);
+		dns_qp_findname_ancestor(qp, name, 0, NULL, NULL, NULL, NULL);
 	}
 	stop = isc_time_monotonic();
 
@@ -280,7 +280,7 @@ main(int argc, char **argv) {
 			++search->ndata[1];
 		}
 
-		dns_qp_findname_ancestor(qp, search, 0, NULL, NULL, NULL);
+		dns_qp_findname_ancestor(qp, search, 0, NULL, NULL, NULL, NULL);
 	}
 	stop = isc_time_monotonic();
 

tests/dns/qp_test.c

@@ -286,7 +286,7 @@ check_partialmatch(dns_qp_t *qp, struct check_partialmatch check[]) {
 
 		dns_test_namefromstring(check[i].query, &fn1);
 		result = dns_qp_findname_ancestor(qp, name, check[i].options,
-						  foundname, &pval, NULL);
+						  foundname, NULL, &pval, NULL);
 
 #if 0
 		fprintf(stderr, "%s (flags %u) %s (expected %s) "
@@ -432,11 +432,108 @@ ISC_RUN_TEST_IMPL(partialmatch) {
 	dns_qp_destroy(&qp);
 }
 
+struct check_qpchain {
+	const char *query;
+	dns_qpfind_t options;
+	isc_result_t result;
+	unsigned int length;
+	const char *names[10];
+};
+
+static void
+check_qpchain(dns_qp_t *qp, struct check_qpchain check[]) {
+	for (int i = 0; check[i].query != NULL; i++) {
+		isc_result_t result;
+		dns_fixedname_t fn1;
+		dns_name_t *name = dns_fixedname_initname(&fn1);
+		dns_qpchain_t chain;
+
+		dns_qpchain_init(qp, &chain);
+		dns_test_namefromstring(check[i].query, &fn1);
+		result = dns_qp_findname_ancestor(qp, name, check[i].options,
+						  NULL, &chain, NULL, NULL);
+
+#if 0
+		fprintf(stderr, "%s (%d) %s (expected %s), "
+			"len %d (expected %d)\n",
+			check[i].query, check[i].options,
+			isc_result_totext(result),
+			isc_result_totext(check[i].result),
+			dns_qpchain_length(&chain), check[i].length);
+#endif
+		assert_int_equal(result, check[i].result);
+		assert_int_equal(dns_qpchain_length(&chain), check[i].length);
+		for (unsigned int j = 0; j < check[i].length; j++) {
+			dns_fixedname_t fn2, fn3;
+			dns_name_t *expected = dns_fixedname_initname(&fn2);
+			dns_name_t *found = dns_fixedname_initname(&fn3);
+
+			dns_test_namefromstring(check[i].names[j], &fn2);
+			dns_qpchain_node(&chain, j, found, NULL, NULL);
+#if 0
+			char nb[DNS_NAME_FORMATSIZE];
+			dns_name_format(found, nb, sizeof(nb));
+			fprintf(stderr, "got %s, expected %s\n", nb,
+				check[i].names[j]);
+#endif
+			assert_true(dns_name_equal(found, expected));
+		}
+	}
+}
+
+ISC_RUN_TEST_IMPL(qpchain) {
+	dns_qp_t *qp = NULL;
+	int i = 0;
+
+	dns_qp_create(mctx, &string_methods, NULL, &qp);
+
+	/*
+	 * Fixed size strings [16] should ensure leaf-compatible alignment.
+	 */
+	const char insert[][16] = { ".",	  "a.",	    "b.",   "c.b.a.",
+				    "e.d.c.b.a.", "c.b.b.", "c.d.", "a.b.c.d.",
+				    "a.b.c.d.e.", "" };
+
+	while (insert[i][0] != '\0') {
+		insert_str(qp, insert[i++]);
+	}
+
+	static struct check_qpchain check1[] = {
+		{ "b.", 0, ISC_R_SUCCESS, 2 },
+		{ "c.", 0, DNS_R_PARTIALMATCH, 1 },
+		{ "e.d.c.b.a.", 0, ISC_R_SUCCESS, 4 },
+		{ "a.b.c.d.", 0, ISC_R_SUCCESS, 3 },
+		{ "a.b.c.d.", DNS_QPFIND_NOEXACT, DNS_R_PARTIALMATCH, 2 },
+		{ NULL, 0, 0, 0 },
+	};
+
+	check1[0].names[0] = ".";
+	check1[0].names[1] = "b.";
+
+	check1[1].names[0] = ".";
+
+	check1[2].names[0] = ".";
+	check1[2].names[1] = "a.";
+	check1[2].names[2] = "c.b.a.";
+	check1[2].names[3] = "e.d.c.b.a.";
+
+	check1[3].names[0] = ".";
+	check1[3].names[1] = "c.d.";
+	check1[3].names[2] = "a.b.c.d.";
+
+	check1[4].names[0] = ".";
+	check1[4].names[1] = "c.d.";
+
+	check_qpchain(qp, check1);
+	dns_qp_destroy(&qp);
+}
+
 ISC_TEST_LIST_START
 ISC_TEST_ENTRY(qpkey_name)
 ISC_TEST_ENTRY(qpkey_sort)
 ISC_TEST_ENTRY(qpiter)
 ISC_TEST_ENTRY(partialmatch)
+ISC_TEST_ENTRY(qpchain)
 ISC_TEST_LIST_END
 
 ISC_TEST_MAIN