Java tutorial
/* * RHQ Management Platform * Copyright (C) 2005-2008 Red Hat, Inc. * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation version 2 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ package org.rhq.plugins.www.snmp; import java.io.InputStream; import java.net.InetAddress; import java.net.UnknownHostException; import java.util.Collection; import java.util.Enumeration; import java.util.HashMap; import java.util.Map; import java.util.Properties; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.snmp4j.smi.OID; public class SNMPClient { static final int AUTH_MD5 = 0; static final int AUTH_SHA = 1; public static final String DEFAULT_HOST = "127.0.0.1"; public static final int DEFAULT_PORT = 161; public static final String DEFAULT_COMMUNITY = "public"; public static final String DEFAULT_USERNAME = "username"; public static final String DEFAULT_PASSWORD = "password"; public static final SNMPVersion DEFAULT_VERSION = SNMPVersion.V2C; public enum SNMPVersion { V1, V2C, V3 } public static final String[] VALID_AUTHTYPES = { "md5", "sha" }; private static Log log = LogFactory.getLog(SNMPClient.class); //XXX cache should be configurable by subclasses private static int CACHE_EXPIRE_DEFAULT = 60 * 1000; //60 seconds private static final Map<String, OID> MIB_OID_CACHE = new HashMap<String, OID>(); private static final Map<Integer, SNMPSession> SESSION_CACHE = new HashMap<Integer, SNMPSession>(); private static final Properties OIDS = new Properties(); private int sessionCacheExpire = CACHE_EXPIRE_DEFAULT; private static final int SESSION_TIMEOUT = 500; private static final int SESSION_RETRIES = 1; // NOTE: We do *not* use a leading slash, since ClassLoader.getResourceAsStream() does not work if there is a one. private static final String OIDS_PROPERTIES_RESOURCE_PATH = "org/rhq/plugins/apache/oids.properties"; public SNMPClient() { if (OIDS.isEmpty()) { initOids(); } } private static int parseAuthMethod(String authMethod) { if (authMethod == null) { throw new IllegalArgumentException("authMethod is null"); } if (authMethod.equalsIgnoreCase("md5")) { return AUTH_MD5; } else if (authMethod.equalsIgnoreCase("sha")) { return AUTH_SHA; } throw new IllegalArgumentException("unknown authMethod: " + authMethod); } private void initOids() { ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader(); ClassLoader classLoader = (contextClassLoader != null) ? contextClassLoader : this.getClass().getClassLoader(); InputStream stream = classLoader.getResourceAsStream(OIDS_PROPERTIES_RESOURCE_PATH); if (stream == null) { throw new IllegalStateException( "Resource '" + OIDS_PROPERTIES_RESOURCE_PATH + "' not found by " + classLoader); } Properties props = new Properties(); try { try { props.load(stream); } finally { stream.close(); } } catch (Exception e) { throw new IllegalStateException("Failed to parse oids.properties file from plugin classloader.", e); } Enumeration<?> propNames = props.propertyNames(); while (propNames.hasMoreElements()) { String propName = (String) propNames.nextElement(); OIDS.setProperty(propName, props.getProperty(propName).trim()); } } static synchronized OID getMibOID(String mibName) throws MIBLookupException { if (mibName.charAt(0) == '.') { // snmp4j doesn't like OIDs with leading dots... mibName = mibName.substring(1); } if (Character.isDigit(mibName.charAt(0))) { // passed-in string is already in numeric form. return new OID(mibName); } OID oid = MIB_OID_CACHE.get(mibName); if (oid == null) { String oidString = OIDS.getProperty(mibName); if (oidString == null) { String msg = "Failed to lookup OID for name=" + mibName; throw new MIBLookupException(msg); } oid = new OID(oidString); if (oid.size() == 0) { throw new IllegalStateException( "Failed to parse OID string [" + oidString + "] while mapping MIB name [" + mibName + "]."); } log.debug("MIB name [" + mibName + "] mapped to OID [" + oid + "]."); MIB_OID_CACHE.put(mibName, oid); } return oid; } public static String getOID(String mibName) { try { return getMibOID(mibName).toString(); } catch (MIBLookupException e) { return null; } } /** * Begins a "session" with an SNMP agent. * * @param version The version of SNMP to use. Can be one of the following values: VERSION_1, VERSION_2C, VERSION_3 * * @return A SNMPSession object to be used in all future communications with the SNMP agent. * * @throws SNMPException on error */ static SNMPSession startSession(SNMPVersion version) throws SNMPException { switch (version) { case V1: { return new SNMPSession_v1(); } case V2C: { return new SNMPSession_v2c(); } case V3: { return new SNMPSession_v3(); } default: { throw new SNMPException("Invalid SNMP Version: " + version); } } } public boolean init(Properties props) throws SNMPException { //this is mainly for debugging. final String prop = "snmp.sessionCacheExpire"; String expire = props.getProperty(prop); if (expire != null) { this.sessionCacheExpire = Integer.parseInt(expire) * 1000; } return true; } public void close() { synchronized (SESSION_CACHE) { Collection<SNMPSession> sessions = SESSION_CACHE.values(); for (SNMPSession session : sessions) { session.close(); } SESSION_CACHE.clear(); // clean out old sessions after they have been closed. } } public SNMPSession getSession(String host, Integer port, String community, SNMPVersion version) throws SNMPException { SNMPSession session; if (host == null) { host = DEFAULT_HOST; } if (port == null) { port = DEFAULT_PORT; } if (community == null) { community = DEFAULT_COMMUNITY; } if (version == null) { version = DEFAULT_VERSION; } int id = host.hashCode() ^ port.hashCode() ^ community.hashCode() ^ version.hashCode(); synchronized (SESSION_CACHE) { session = SESSION_CACHE.get(id); } if (session != null) { return session; } InetAddress ip; try { ip = InetAddress.getByName(host); } catch (UnknownHostException e) { throw new SNMPException("Invalid Host: '" + host + "': " + e); } if ((port < 1) || (port > 65535)) { throw new SNMPException("Invalid Port: " + port); } if (!community.trim().equals(community)) { throw new SNMPException("Invalid Community: '" + community + "': whitespace is not permitted"); } try { session = startSession(version); switch (version) { case V1: case V2C: { ((SNMPSession_v1) session).init(host, port, community); break; } case V3: { // TODO String user = "TODO"; String pass = "TODO"; int authType = parseAuthMethod("TODO"); ((SNMPSession_v3) session).init(host, port, user, pass, authType); break; } default: { throw new SNMPException("unsupported SNMP version"); } } //should be enough for properly functioning SNMP //and not too long for one that is not functioning at all session.setTimeout(SESSION_TIMEOUT); session.setRetries(SESSION_RETRIES); log.info("Initialized SNMP session for agent at " + ip + ":" + port); } catch (SNMPException e) { String msg = "Failed to initialize snmp session"; throw new SNMPException(msg, e); } session = SNMPSessionCache.newInstance(session, this.sessionCacheExpire); synchronized (SESSION_CACHE) { SESSION_CACHE.put(id, session); } return session; } }