38 * NameNode tree containing the zone's contents.
39 *
40 * <p> A populated zone's contents will be flagged as having expired after
41 * the time specified by the minimum TTL value in the zone's SOA record.
42 *
43 * <p> Since zone cuts aren't directly modeled by a tree of ZoneNodes,
44 * ZoneNode.isZoneCut() always returns false.
45 *
46 * <p> The synchronization strategy is documented in DnsContext.java.
47 *
48 * <p> The zone's contents are accessed via a soft reference, so its
49 * heap space may be reclaimed when necessary. The zone may be
50 * repopulated later.
51 *
52 * @author Scott Seligman
53 */
54
55
56 class ZoneNode extends NameNode {
57
58 private SoftReference contentsRef = null; // the zone's namespace
59 private long serialNumber = -1; // the zone data's serial number
60 private Date expiration = null; // time when the zone's data expires
61
62 ZoneNode(String label) {
63 super(label);
64 }
65
66 protected NameNode newNameNode(String label) {
67 return new ZoneNode(label);
68 }
69
70 /*
71 * Clears the contents of this node. If the node was flagged as
72 * expired, it remains so.
73 */
74 synchronized void depopulate() {
75 contentsRef = null;
76 serialNumber = -1;
77 }
78
79 /*
80 * Is this node currently populated?
81 */
82 synchronized boolean isPopulated() {
83 return (getContents() != null);
84 }
85
86 /*
87 * Returns the zone's contents, or null if the zone is not populated.
88 */
89 synchronized NameNode getContents() {
90 return (contentsRef != null)
91 ? (NameNode) contentsRef.get()
92 : null;
93 }
94
95 /*
96 * Has this zone's data expired?
97 */
98 synchronized boolean isExpired() {
99 return ((expiration != null) && expiration.before(new Date()));
100 }
101
102 /*
103 * Returns the deepest populated zone on the path specified by a
104 * fully-qualified domain name, or null if there is no populated
105 * zone on that path. Note that a node may be depopulated after
106 * being returned.
107 */
108 ZoneNode getDeepestPopulated(DnsName fqdn) {
109 ZoneNode znode = this;
110 ZoneNode popNode = isPopulated() ? this : null;
111 for (int i = 1; i < fqdn.size(); i++) { // "i=1" to skip root label
113 if (znode == null) {
114 break;
115 } else if (znode.isPopulated()) {
116 popNode = znode;
117 }
118 }
119 return popNode;
120 }
121
122 /*
123 * Populates (or repopulates) a zone given its own fully-qualified
124 * name and its resource records. Returns the zone's new contents.
125 */
126 NameNode populate(DnsName zone, ResourceRecords rrs) {
127 // assert zone.get(0).equals(""); // zone has root label
128 // assert (zone.size() == (depth() + 1)); // +1 due to root label
129
130 NameNode newContents = new NameNode(null);
131
132 for (int i = 0; i < rrs.answer.size(); i++) {
133 ResourceRecord rr = (ResourceRecord) rrs.answer.elementAt(i);
134 DnsName n = rr.getName();
135
136 // Ignore resource records whose names aren't within the zone's
137 // domain. Also skip records of the zone's top node, since
138 // the zone's root NameNode is already in place.
139 if ((n.size() > zone.size()) && n.startsWith(zone)) {
140 NameNode nnode = newContents.add(n, zone.size());
141 if (rr.getType() == ResourceRecord.TYPE_NS) {
142 nnode.setZoneCut(true);
143 }
144 }
145 }
146 // The zone's SOA record is the first record in the answer section.
147 ResourceRecord soa = (ResourceRecord) rrs.answer.firstElement();
148 synchronized (this) {
149 contentsRef = new SoftReference(newContents);
150 serialNumber = getSerialNumber(soa);
151 setExpiration(getMinimumTtl(soa));
152 return newContents;
153 }
154 }
155
156 /*
157 * Set this zone's data to expire in <tt>secsToExpiration</tt> seconds.
158 */
159 private void setExpiration(long secsToExpiration) {
160 expiration = new Date(System.currentTimeMillis() +
161 1000 * secsToExpiration);
162 }
163
164 /*
165 * Returns an SOA record's minimum TTL field.
166 */
167 private static long getMinimumTtl(ResourceRecord soa) {
168 String rdata = (String) soa.getRdata();
169 int pos = rdata.lastIndexOf(' ') + 1;
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38 * NameNode tree containing the zone's contents.
39 *
40 * <p> A populated zone's contents will be flagged as having expired after
41 * the time specified by the minimum TTL value in the zone's SOA record.
42 *
43 * <p> Since zone cuts aren't directly modeled by a tree of ZoneNodes,
44 * ZoneNode.isZoneCut() always returns false.
45 *
46 * <p> The synchronization strategy is documented in DnsContext.java.
47 *
48 * <p> The zone's contents are accessed via a soft reference, so its
49 * heap space may be reclaimed when necessary. The zone may be
50 * repopulated later.
51 *
52 * @author Scott Seligman
53 */
54
55
56 class ZoneNode extends NameNode {
57
58 private SoftReference<NameNode> contentsRef = null; // the zone's namespace
59 private long serialNumber = -1; // the zone data's serial number
60 private Date expiration = null; // time when the zone's data expires
61
62 ZoneNode(String label) {
63 super(label);
64 }
65
66 protected NameNode newNameNode(String label) {
67 return new ZoneNode(label);
68 }
69
70 /*
71 * Clears the contents of this node. If the node was flagged as
72 * expired, it remains so.
73 */
74 synchronized void depopulate() {
75 contentsRef = null;
76 serialNumber = -1;
77 }
78
79 /*
80 * Is this node currently populated?
81 */
82 synchronized boolean isPopulated() {
83 return (getContents() != null);
84 }
85
86 /*
87 * Returns the zone's contents, or null if the zone is not populated.
88 */
89 synchronized NameNode getContents() {
90 return (contentsRef != null)
91 ? contentsRef.get()
92 : null;
93 }
94
95 /*
96 * Has this zone's data expired?
97 */
98 synchronized boolean isExpired() {
99 return ((expiration != null) && expiration.before(new Date()));
100 }
101
102 /*
103 * Returns the deepest populated zone on the path specified by a
104 * fully-qualified domain name, or null if there is no populated
105 * zone on that path. Note that a node may be depopulated after
106 * being returned.
107 */
108 ZoneNode getDeepestPopulated(DnsName fqdn) {
109 ZoneNode znode = this;
110 ZoneNode popNode = isPopulated() ? this : null;
111 for (int i = 1; i < fqdn.size(); i++) { // "i=1" to skip root label
113 if (znode == null) {
114 break;
115 } else if (znode.isPopulated()) {
116 popNode = znode;
117 }
118 }
119 return popNode;
120 }
121
122 /*
123 * Populates (or repopulates) a zone given its own fully-qualified
124 * name and its resource records. Returns the zone's new contents.
125 */
126 NameNode populate(DnsName zone, ResourceRecords rrs) {
127 // assert zone.get(0).equals(""); // zone has root label
128 // assert (zone.size() == (depth() + 1)); // +1 due to root label
129
130 NameNode newContents = new NameNode(null);
131
132 for (int i = 0; i < rrs.answer.size(); i++) {
133 ResourceRecord rr = rrs.answer.elementAt(i);
134 DnsName n = rr.getName();
135
136 // Ignore resource records whose names aren't within the zone's
137 // domain. Also skip records of the zone's top node, since
138 // the zone's root NameNode is already in place.
139 if ((n.size() > zone.size()) && n.startsWith(zone)) {
140 NameNode nnode = newContents.add(n, zone.size());
141 if (rr.getType() == ResourceRecord.TYPE_NS) {
142 nnode.setZoneCut(true);
143 }
144 }
145 }
146 // The zone's SOA record is the first record in the answer section.
147 ResourceRecord soa = rrs.answer.firstElement();
148 synchronized (this) {
149 contentsRef = new SoftReference<NameNode>(newContents);
150 serialNumber = getSerialNumber(soa);
151 setExpiration(getMinimumTtl(soa));
152 return newContents;
153 }
154 }
155
156 /*
157 * Set this zone's data to expire in <tt>secsToExpiration</tt> seconds.
158 */
159 private void setExpiration(long secsToExpiration) {
160 expiration = new Date(System.currentTimeMillis() +
161 1000 * secsToExpiration);
162 }
163
164 /*
165 * Returns an SOA record's minimum TTL field.
166 */
167 private static long getMinimumTtl(ResourceRecord soa) {
168 String rdata = (String) soa.getRdata();
169 int pos = rdata.lastIndexOf(' ') + 1;
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