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1
5 package com.terracotta.session.util;
6
7 import com.tc.object.bytecode.Manager;
8 import com.terracotta.session.SessionId;
9
10 import java.security.SecureRandom  ;
11
12
15 public class DefaultIdGenerator implements SessionIdGenerator {
16
17 private static final int MIN_LENGTH = 8;
19 private static final char DLM = '!';
20 private final SecureRandom random;
21 private final int idLength;
22 private final String serverId;
23 private short nextId = Short.MIN_VALUE;
24 private final int lockType;
25
26 public static SessionIdGenerator makeInstance(ConfigProperties cp, int lockType) {
27 Assert.pre(cp != null);
28 final int idLength = cp.getSessionIdLength();
29 final String servetId = cp.getServerId();
30 return new DefaultIdGenerator(idLength, servetId, lockType);
31 }
32
33 public DefaultIdGenerator(final int idLength, final String serverId) {
35 this(idLength, serverId, Manager.LOCK_TYPE_WRITE);
36 }
37
38 public DefaultIdGenerator(final int idLength, final String serverId, int lockType) {
39 random = new SecureRandom ();
40 random.nextInt();
42
43 this.lockType = lockType;
44 this.idLength = Math.max(idLength, MIN_LENGTH);
45 this.serverId = serverId;
46 }
47
48 public SessionId generateNewId() {
49 final String key = generateKey();
50 final String externalId = key + DLM + serverId;
51 return new DefaultSessionId(key, null, externalId, lockType);
52 }
53
54 public SessionId makeInstanceFromBrowserId(String requestedSessionId) {
55 Assert.pre(requestedSessionId != null);
56 final int dlmIndex = requestedSessionId.indexOf(DLM);
57 if (dlmIndex > 0) {
59 final String key = requestedSessionId.substring(0, dlmIndex);
60 final String externalId = key + DLM + serverId;
61 return new DefaultSessionId(key, requestedSessionId, externalId, lockType);
62 } else {
63 return null;
65 }
66 }
67
68 public SessionId makeInstanceFromInternalKey(String key) {
69 final String externalId = key + DLM + serverId;
70 return new DefaultSessionId(key, externalId, externalId, lockType);
71 }
72
73
77 protected synchronized String generateKey() {
78 final byte[] bytes = new byte[2];
79 final StringBuffer sb = new StringBuffer ();
80 random.nextBytes(bytes);
82 sb.append(toHex(bytes, 2));
83
84 toBytes(getNextId(), bytes);
86 sb.append(toHex(bytes, 2));
87
88 if (sb.length() < idLength) {
90 final byte[] extraBytes = new byte[idLength - MIN_LENGTH];
91 random.nextBytes(extraBytes);
92 sb.append(toHex(extraBytes, extraBytes.length));
93 }
94 return sb.substring(0, idLength);
95 }
96
97 protected synchronized short getNextId() {
98 return nextId++;
99 }
100
101 protected static void toBytes(short s, byte[] bytes) {
102 bytes[0] = (byte) ((s & 0xff00) >> 8);
103 bytes[1] = (byte) (s & 0x00ff);
104 }
105
106 protected static String toHex(byte[] bytes, int byteCnt) {
107 final char[] hexChars = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
108 StringBuffer sb = new StringBuffer ();
109 for (int i = 0; i < byteCnt; i++) {
110 byte b = bytes[i];
111 byte b1 = (byte) ((b & 0xf0) >> 4);
112 byte b2 = (byte) (b & 0x0f);
113 sb.append(hexChars[b1]).append(hexChars[b2]);
114 }
115 return sb.toString();
116 }
117 }
118 |
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