Source Code Cross Referenced for InetAddressCachePolicy.java in  » 6.0-JDK-Modules » j2me » sun » net » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » 6.0 JDK Modules » j2me » sun.net 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * @(#)InetAddressCachePolicy.java	1.14 06/10/10
003:         *
004:         * Copyright  1990-2006 Sun Microsystems, Inc. All Rights Reserved.  
005:         * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
006:         *   
007:         * This program is free software; you can redistribute it and/or  
008:         * modify it under the terms of the GNU General Public License version  
009:         * 2 only, as published by the Free Software Foundation.   
010:         *   
011:         * This program is distributed in the hope that it will be useful, but  
012:         * WITHOUT ANY WARRANTY; without even the implied warranty of  
013:         * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
014:         * General Public License version 2 for more details (a copy is  
015:         * included at /legal/license.txt).   
016:         *   
017:         * You should have received a copy of the GNU General Public License  
018:         * version 2 along with this work; if not, write to the Free Software  
019:         * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
020:         * 02110-1301 USA   
021:         *   
022:         * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
023:         * Clara, CA 95054 or visit www.sun.com if you need additional  
024:         * information or have any questions. 
025:         *
026:         */
027:
028:        package sun.net;
029:
030:        import java.net.InetAddress;
031:        import java.security.PrivilegedAction;
032:        import java.security.Security;
033:
034:        public final class InetAddressCachePolicy {
035:
036:            // Controls the cache policy for successful lookups only
037:            private static final String cachePolicyProp = "networkaddress.cache.ttl";
038:            private static final String cachePolicyPropFallback = "sun.net.inetaddr.ttl";
039:
040:            // Controls the cache policy for negative lookups only
041:            private static final String negativeCachePolicyProp = "networkaddress.cache.negative.ttl";
042:            private static final String negativeCachePolicyPropFallback = "sun.net.inetaddr.negative.ttl";
043:
044:            public static final int FOREVER = -1;
045:            public static final int NEVER = 0;
046:
047:            /* The Java-level namelookup cache policy for successful lookups:
048:             * 
049:             * -1: caching forever
050:             * any positive value: the number of seconds to cache an address for
051:             *
052:             * default value is forever (FOREVER), as we let the platform do the
053:             * caching. For security reasons, this caching is made forever when
054:             * a security manager is set.
055:             */
056:            private static int cachePolicy;
057:
058:            /* The Java-level namelookup cache policy for negative lookups:
059:             * 
060:             * -1: caching forever
061:             * any positive value: the number of seconds to cache an address for
062:             *
063:             * default value is 0. It can be set to some other value for
064:             * performance reasons.
065:             */
066:            private static int negativeCachePolicy;
067:
068:            /* 
069:             * Whether or not the cache policy for successful lookups was set
070:             * using a property (cmd line).
071:             */
072:            private static boolean set = false;
073:
074:            /* 
075:             * Whether or not the cache policy for negative lookups was set
076:             * using a property (cmd line).
077:             */
078:            private static boolean negativeSet = false;
079:
080:            /*
081:             * Initialize
082:             */
083:            static {
084:
085:                set = false;
086:                negativeSet = false;
087:
088:                cachePolicy = FOREVER;
089:                negativeCachePolicy = 0;
090:
091:                Integer tmp = null;
092:
093:                try {
094:                    tmp = new Integer((String) java.security.AccessController
095:                            .doPrivileged(new PrivilegedAction() {
096:                                public Object run() {
097:                                    return Security
098:                                            .getProperty(cachePolicyProp);
099:                                }
100:                            }));
101:                } catch (NumberFormatException e) {
102:                    // ignore
103:                }
104:                if (tmp != null) {
105:                    cachePolicy = tmp.intValue();
106:                    if (cachePolicy < 0) {
107:                        cachePolicy = FOREVER;
108:                    }
109:                    set = true;
110:                } else {
111:                    tmp = (Integer) java.security.AccessController
112:                            .doPrivileged(new sun.security.action.GetIntegerAction(
113:                                    cachePolicyPropFallback));
114:                    if (tmp != null) {
115:                        cachePolicy = tmp.intValue();
116:                        if (cachePolicy < 0) {
117:                            cachePolicy = FOREVER;
118:                        }
119:                        set = true;
120:                    }
121:                }
122:
123:                try {
124:                    tmp = new Integer((String) java.security.AccessController
125:                            .doPrivileged(new PrivilegedAction() {
126:                                public Object run() {
127:                                    return Security
128:                                            .getProperty(negativeCachePolicyProp);
129:                                }
130:                            }));
131:                } catch (NumberFormatException e) {
132:                    // ignore
133:                }
134:
135:                if (tmp != null) {
136:                    negativeCachePolicy = tmp.intValue();
137:                    if (negativeCachePolicy < 0) {
138:                        negativeCachePolicy = FOREVER;
139:                    }
140:                    negativeSet = true;
141:                } else {
142:                    tmp = (Integer) java.security.AccessController
143:                            .doPrivileged(new sun.security.action.GetIntegerAction(
144:                                    negativeCachePolicyPropFallback));
145:                    if (tmp != null) {
146:                        negativeCachePolicy = tmp.intValue();
147:                        if (negativeCachePolicy < 0) {
148:                            negativeCachePolicy = FOREVER;
149:                        }
150:                        negativeSet = true;
151:                    }
152:                }
153:            }
154:
155:            public static synchronized int get() {
156:                return cachePolicy;
157:            }
158:
159:            public static synchronized int getNegative() {
160:                return negativeCachePolicy;
161:            }
162:
163:            /**
164:             * Sets the cache policy for successful lookups if the user has not
165:             * already specified a cache policy for it using a
166:             * command-property.
167:             * @param newPolicy the value in seconds for how long the lookup
168:             * should be cached
169:             */
170:            public static synchronized void setIfNotSet(int newPolicy) {
171:
172:                /* 
173:                 * When setting the new value we may want to signal that the
174:                 * cache should be flushed, though this doesn't seem strictly
175:                 * necessary.
176:                 */
177:
178:                if (!set) {
179:                    checkValue(newPolicy, cachePolicy);
180:                    cachePolicy = newPolicy;
181:                }
182:
183:            }
184:
185:            /**
186:             * Sets the cache policy for negative lookups if the user has not
187:             * already specified a cache policy for it using a
188:             * command-property.
189:             * @param newPolicy the value in seconds for how long the lookup
190:             * should be cached
191:             */
192:            public static synchronized void setNegativeIfNotSet(int newPolicy) {
193:
194:                /* 
195:                 * When setting the new value we may want to signal that the
196:                 * cache should be flushed, though this doesn't seem strictly
197:                 * necessary.
198:                 */
199:
200:                if (!negativeSet) {
201:                    // Negative caching does not seem to have any security
202:                    // implications.
203:                    // checkValue(newPolicy, negativeCachePolicy);
204:                    negativeCachePolicy = newPolicy;
205:                }
206:            }
207:
208:            private static void checkValue(int newPolicy, int oldPolicy) {
209:
210:                /*
211:                 * If malicious code gets a hold of this method, prevent
212:                 * setting the cache policy to something laxer or some
213:                 * invalid negative value.
214:                 */
215:
216:                if (newPolicy == FOREVER)
217:                    return;
218:
219:                if ((oldPolicy == FOREVER) || (newPolicy < oldPolicy)
220:                        || (newPolicy < FOREVER)) {
221:
222:                    throw new SecurityException(
223:                            "can't make InetAddress cache more lax");
224:
225:                }
226:            }
227:        }
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