org.snmp4j.security.UsmTimeTable Maven / Gradle / Ivy
/*_############################################################################
_##
_## SNMP4J - UsmTimeTable.java
_##
_## Copyright (C) 2003-2024 Frank Fock (SNMP4J.org)
_##
_## Licensed under the Apache License, Version 2.0 (the "License");
_## you may not use this file except in compliance with the License.
_## You may obtain a copy of the License at
_##
_## http://www.apache.org/licenses/LICENSE-2.0
_##
_## Unless required by applicable law or agreed to in writing, software
_## distributed under the License is distributed on an "AS IS" BASIS,
_## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
_## See the License for the specific language governing permissions and
_## limitations under the License.
_##
_##########################################################################*/
package org.snmp4j.security;
import org.snmp4j.log.LogAdapter;
import org.snmp4j.log.LogFactory;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.Variable;
import java.io.Serializable;
import java.util.Hashtable;
/**
* The {@code UsmTimeTable} class is a singleton that stores USM user information as part of the Local
* Configuration Datastore (LCD).
*
* @author Frank Fock
* @version 1.2
*/
public class UsmTimeTable implements Serializable {
private static final long serialVersionUID = -1538321547688349797L;
private static final LogAdapter logger = LogFactory.getLogger(UsmTimeTable.class);
static final long TIME_PRECISION = 1000000000L;
public static final int USM_MAX_TIME_DIFFERENCE_HUNDREDS = 150;
private Hashtable table = new Hashtable(10);
private long lastLocalTimeChange = System.nanoTime();
private UsmTimeEntry localTime;
public UsmTimeTable(OctetString localEngineID, int engineBoots) {
setLocalTime(new UsmTimeEntry(localEngineID, engineBoots, 0));
}
public void addEntry(final UsmTimeEntry entry) {
table.put(entry.getEngineID(), entry);
}
public UsmTimeEntry getEntry(final OctetString engineID) {
return table.get(engineID);
}
public UsmTimeEntry getLocalTime() {
UsmTimeEntry entry = new UsmTimeEntry(localTime.getEngineID(),
localTime.getEngineBoots(),
getEngineTime());
entry.setTimeDiff(entry.getTimeDiff() * (-1) + localTime.getTimeDiff());
return entry;
}
public void setLocalTime(UsmTimeEntry localTime) {
this.localTime = localTime;
lastLocalTimeChange = System.nanoTime();
}
/**
* Sets the number of engine boots.
*
* @param engineBoots
* the number of engine boots.
*
* @since 1.2
*/
public void setEngineBoots(int engineBoots) {
this.localTime.setEngineBoots(engineBoots);
}
/**
* Returns the number of seconds since the value of the engineBoots object last changed. When incrementing this
* object's value would cause it to exceed its maximum, engineBoots is incremented as if a re-initialization had
* occurred, and this object's value consequently reverts to zero.
*
* @return a positive integer value denoting the number of seconds since the engineBoots value has been changed.
* @since 1.2
*/
public int getEngineTime() {
return (int) ((((System.nanoTime() - lastLocalTimeChange) / TIME_PRECISION) +
localTime.getLatestReceivedTime()) %
2147483648L);
}
/**
* The number of times that the SNMP engine has (re-)initialized itself since snmpEngineID was last configured.
*
* @return the number of SNMP engine reboots.
*/
public int getEngineBoots() {
return localTime.getEngineBoots();
}
public synchronized UsmTimeEntry getTime(OctetString engineID) {
if (localTime.getEngineID().equals(engineID)) {
return getLocalTime();
}
UsmTimeEntry found = table.get(engineID);
if (found == null) {
return null;
}
return new UsmTimeEntry(engineID, found.getEngineBoots(), found.getTimeDiff() +
(int) (System.nanoTime() / TIME_PRECISION));
}
/**
* Removes the specified engine ID from the time cache.
*
* @param engineID
* the engine ID of the remote SNMP engine to remove from this time cache.
*/
public void removeEntry(final OctetString engineID) {
table.remove(engineID);
}
public synchronized int checkEngineID(OctetString engineID,
boolean discoveryAllowed,
int engineBoots,
int engineTime) {
if (table.get(engineID) != null) {
return SnmpConstants.SNMPv3_USM_OK;
} else if (discoveryAllowed) {
addEntry(new UsmTimeEntry(engineID, engineBoots, engineTime));
return SnmpConstants.SNMPv3_USM_OK;
}
return SnmpConstants.SNMPv3_USM_UNKNOWN_ENGINEID;
}
public synchronized int checkTime(final UsmTimeEntry entry) {
int now = (int) (System.nanoTime() / TIME_PRECISION);
if (localTime.getEngineID().equals(entry.getEngineID())) {
/* Entry found, we are authoritative */
if ((localTime.getEngineBoots() == 2147483647) ||
(localTime.getEngineBoots() != entry.getEngineBoots()) ||
(Math.abs(now + localTime.getTimeDiff() - entry.getLatestReceivedTime())
> USM_MAX_TIME_DIFFERENCE_HUNDREDS)) {
if (logger.isDebugEnabled()) {
logger.debug(
"CheckTime: received message outside time window (authoritative):" +
((localTime.getEngineBoots() !=
entry.getEngineBoots()) ? "engineBoots differ " +
localTime.getEngineBoots() + "!=" + entry.getEngineBoots() :
"" + (Math.abs(now + localTime.getTimeDiff() -
entry.getLatestReceivedTime())) + " > 150"));
}
return SnmpConstants.SNMPv3_USM_NOT_IN_TIME_WINDOW;
} else {
if (logger.isDebugEnabled()) {
logger.debug("CheckTime: time ok (authoritative)");
}
return SnmpConstants.SNMPv3_USM_OK;
}
} else {
UsmTimeEntry time = table.get(entry.getEngineID());
if (time == null) {
return SnmpConstants.SNMPv3_USM_UNKNOWN_ENGINEID;
}
// RFC 3414 section 3.2.7 b) 1):
if ((entry.getEngineBoots() > time.getEngineBoots()) ||
((entry.getEngineBoots() == time.getEngineBoots()) &&
(entry.getLatestReceivedTime() > time.getLatestReceivedTime()))) {
/* time ok, update values */
time.setEngineBoots(entry.getEngineBoots());
time.setLatestReceivedTime(entry.getLatestReceivedTime());
time.setTimeDiff(entry.getLatestReceivedTime() - now);
}
// RFC 3414 section 3.2.7 b) 2):
if ((entry.getEngineBoots() < time.getEngineBoots()) ||
((entry.getEngineBoots() == time.getEngineBoots()) &&
(time.getLatestReceivedTime() > entry.getLatestReceivedTime() + 150)) ||
(time.getEngineBoots() == 2147483647)) {
if (logger.isDebugEnabled()) {
logger.debug(
"CheckTime: received message outside time window (non authoritative)");
}
return SnmpConstants.SNMPv3_USM_NOT_IN_TIME_WINDOW;
} else {
if (logger.isDebugEnabled()) {
logger.debug("CheckTime: time ok (non authoritative)");
}
return SnmpConstants.SNMPv3_USM_OK;
}
}
}
public void reset() {
}
}
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