| /* |
| * Copyright (c) 1996, 2008, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.rmi.dgc; |
| |
| import java.io.*; |
| import java.net.*; |
| import java.rmi.server.UID; |
| import java.security.*; |
| |
| /** |
| * A VMID is a identifier that is unique across all Java virtual |
| * machines. VMIDs are used by the distributed garbage collector |
| * to identify client VMs. |
| * |
| * @author Ann Wollrath |
| * @author Peter Jones |
| */ |
| public final class VMID implements java.io.Serializable { |
| |
| /** array of bytes uniquely identifying this host */ |
| private static byte[] localAddr = computeAddressHash(); |
| |
| /** |
| * @serial array of bytes uniquely identifying host created on |
| */ |
| private byte[] addr; |
| |
| /** |
| * @serial unique identifier with respect to host created on |
| */ |
| private UID uid; |
| |
| /** indicate compatibility with JDK 1.1.x version of class */ |
| private static final long serialVersionUID = -538642295484486218L; |
| |
| /** |
| * Create a new VMID. Each new VMID returned from this constructor |
| * is unique for all Java virtual machines under the following |
| * conditions: a) the conditions for uniqueness for objects of |
| * the class <code>java.rmi.server.UID</code> are satisfied, and b) an |
| * address can be obtained for this host that is unique and constant |
| * for the lifetime of this object. <p> |
| */ |
| public VMID() { |
| addr = localAddr; |
| uid = new UID(); |
| } |
| |
| /** |
| * Return true if an accurate address can be determined for this |
| * host. If false, reliable VMID cannot be generated from this host |
| * @return true if host address can be determined, false otherwise |
| * @deprecated |
| */ |
| @Deprecated |
| public static boolean isUnique() { |
| return true; |
| } |
| |
| /** |
| * Compute hash code for this VMID. |
| */ |
| public int hashCode() { |
| return uid.hashCode(); |
| } |
| |
| /** |
| * Compare this VMID to another, and return true if they are the |
| * same identifier. |
| */ |
| public boolean equals(Object obj) { |
| if (obj instanceof VMID) { |
| VMID vmid = (VMID) obj; |
| if (!uid.equals(vmid.uid)) |
| return false; |
| if ((addr == null) ^ (vmid.addr == null)) |
| return false; |
| if (addr != null) { |
| if (addr.length != vmid.addr.length) |
| return false; |
| for (int i = 0; i < addr.length; ++ i) |
| if (addr[i] != vmid.addr[i]) |
| return false; |
| } |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| /** |
| * Return string representation of this VMID. |
| */ |
| public String toString() { |
| StringBuffer result = new StringBuffer(); |
| if (addr != null) |
| for (int i = 0; i < addr.length; ++ i) { |
| int x = (int) (addr[i] & 0xFF); |
| result.append((x < 0x10 ? "0" : "") + |
| Integer.toString(x, 16)); |
| } |
| result.append(':'); |
| result.append(uid.toString()); |
| return result.toString(); |
| } |
| |
| /** |
| * Compute the hash an IP address. The hash is the first 8 bytes |
| * of the SHA digest of the IP address. |
| */ |
| private static byte[] computeAddressHash() { |
| |
| /* |
| * Get the local host's IP address. |
| */ |
| byte[] addr = java.security.AccessController.doPrivileged( |
| new PrivilegedAction<byte[]>() { |
| public byte[] run() { |
| try { |
| return InetAddress.getLocalHost().getAddress(); |
| } catch (Exception e) { |
| } |
| return new byte[] { 0, 0, 0, 0 }; |
| } |
| }); |
| |
| byte[] addrHash; |
| final int ADDR_HASH_LENGTH = 8; |
| |
| try { |
| /* |
| * Calculate message digest of IP address using SHA. |
| */ |
| MessageDigest md = MessageDigest.getInstance("SHA"); |
| ByteArrayOutputStream sink = new ByteArrayOutputStream(64); |
| DataOutputStream out = new DataOutputStream( |
| new DigestOutputStream(sink, md)); |
| out.write(addr, 0, addr.length); |
| out.flush(); |
| |
| byte digest[] = md.digest(); |
| int hashlength = Math.min(ADDR_HASH_LENGTH, digest.length); |
| addrHash = new byte[hashlength]; |
| System.arraycopy(digest, 0, addrHash, 0, hashlength); |
| |
| } catch (IOException ignore) { |
| /* can't happen, but be deterministic anyway. */ |
| addrHash = new byte[0]; |
| } catch (NoSuchAlgorithmException complain) { |
| throw new InternalError(complain.toString()); |
| } |
| return addrHash; |
| } |
| } |