1 /*
2 * Copyright (c) 2000, 2002, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package com.sun.jndi.dns;
27
28
29 import java.util.Hashtable;
30
31
32 /**
33 * A NameNode represents a node in the DNS namespace. Each node
34 * has a label, which is its name relative to its parent (so the
35 * node at Sun.COM has label "Sun"). Each node has a hashtable of
36 * children indexed by their labels converted to lower-case.
37 *
38 * <p> A node may be addressed from another by giving a DnsName
39 * consisting of the sequence of labels from one node to the other.
40 *
41 * <p> Each node also has an <tt>isZoneCut</tt> flag, used to indicate
42 * if the node is a zone cut. A zone cut is a node with an NS record
43 * that is contained in one zone, but that actually belongs to a child zone.
44 *
45 * <p> All access is unsynchronized.
46 *
47 * @author Scott Seligman
48 */
49
50
51 class NameNode {
52
53 private String label; // name of this node relative to its
54 // parent, or null for root of a tree
55 private Hashtable<String,NameNode> children = null; // child nodes
56 private boolean isZoneCut = false; // true if this node is a zone cut
57 private int depth = 0; // depth in tree (0 for root)
58
59 NameNode(String label) {
60 this.label = label;
61 }
62
63 /*
64 * Returns a newly-allocated NameNode. Used to allocate new nodes
65 * in a tree. Should be overridden in a subclass to return an object
66 * of the subclass's type.
67 */
68 protected NameNode newNameNode(String label) {
69 return new NameNode(label);
70 }
71
72 /*
73 * Returns the name of this node relative to its parent, or null for
74 * the root of a tree.
75 */
76 String getLabel() {
77 return label;
78 }
79
80 /*
81 * Returns the depth of this node in the tree. The depth of the root
82 * is 0.
83 */
84 int depth() {
85 return depth;
86 }
87
88 boolean isZoneCut() {
89 return isZoneCut;
90 }
91
92 void setZoneCut(boolean isZoneCut) {
93 this.isZoneCut = isZoneCut;
94 }
95
96 /*
97 * Returns the children of this node, or null if there are none.
98 * The caller must not modify the Hashtable returned.
99 */
100 Hashtable<String,NameNode> getChildren() {
101 return children;
102 }
103
104 /*
105 * Returns the child node given the hash key (the down-cased label)
106 * for its name relative to this node, or null if there is no such
107 * child.
108 */
109 NameNode get(String key) {
110 return (children != null)
111 ? children.get(key)
112 : null;
113 }
114
115 /*
116 * Returns the node at the end of a path, or null if the
117 * node does not exist.
118 * The path is specified by the labels of <tt>name</tt>, beginning
119 * at index idx.
120 */
121 NameNode get(DnsName name, int idx) {
122 NameNode node = this;
123 for (int i = idx; i < name.size() && node != null; i++) {
124 node = node.get(name.getKey(i));
125 }
126 return node;
127 }
128
129 /*
130 * Returns the node at the end of a path, creating it and any
131 * intermediate nodes as needed.
132 * The path is specified by the labels of <tt>name</tt>, beginning
133 * at index idx.
134 */
135 NameNode add(DnsName name, int idx) {
136 NameNode node = this;
137 for (int i = idx; i < name.size(); i++) {
138 String label = name.get(i);
139 String key = name.getKey(i);
140
141 NameNode child = null;
142 if (node.children == null) {
143 node.children = new Hashtable<>();
144 } else {
145 child = node.children.get(key);
146 }
147 if (child == null) {
148 child = newNameNode(label);
149 child.depth = node.depth + 1;
150 node.children.put(key, child);
151 }
152 node = child;
153 }
154 return node;
155 }
156 }