1 /*
2 * Copyright (c) 1996, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.rmi.transport;
27
28 import java.io.IOException;
29 import java.io.ObjectOutput;
30 import java.rmi.MarshalException;
31 import java.rmi.NoSuchObjectException;
32 import java.rmi.Remote;
33 import java.rmi.RemoteException;
34 import java.rmi.server.LogStream;
35 import java.rmi.server.ObjID;
36 import java.rmi.server.RemoteCall;
37 import java.rmi.server.RemoteServer;
38 import java.rmi.server.ServerNotActiveException;
39 import java.security.AccessControlContext;
40 import java.security.AccessController;
41 import java.security.Permissions;
42 import java.security.PrivilegedAction;
43 import java.security.ProtectionDomain;
44 import sun.rmi.runtime.Log;
45 import sun.rmi.server.Dispatcher;
46 import sun.rmi.server.UnicastServerRef;
47
48 /**
49 * Transport abstraction for enabling communication between different
50 * VMs.
51 *
52 * @author Ann Wollrath
53 */
54 public abstract class Transport {
55
56 /** "transport" package log level */
57 static final int logLevel = LogStream.parseLevel(getLogLevel());
58
59 private static String getLogLevel() {
60 return java.security.AccessController.doPrivileged(
61 new sun.security.action.GetPropertyAction("sun.rmi.transport.logLevel"));
62 }
63
64 /* transport package log */
65 static final Log transportLog =
66 Log.getLog("sun.rmi.transport.misc", "transport", Transport.logLevel);
67
68 /** References the current transport when a call is being serviced */
69 private static final ThreadLocal currentTransport = new ThreadLocal();
70
71 /** ObjID for DGCImpl */
72 private static final ObjID dgcID = new ObjID(ObjID.DGC_ID);
73
74 /** AccessControlContext for setting context ClassLoader */
75 private static final AccessControlContext SETCCL_ACC;
76 static {
77 Permissions perms = new Permissions();
78 perms.add(new RuntimePermission("setContextClassLoader"));
79 ProtectionDomain[] pd = { new ProtectionDomain(null, perms) };
80 SETCCL_ACC = new AccessControlContext(pd);
81 }
82
83 /**
84 * Returns a <I>Channel</I> that generates connections to the
85 * endpoint <I>ep</I>. A Channel is an object that creates and
86 * manages connections of a particular type to some particular
87 * address space.
88 * @param ep the endpoint to which connections will be generated.
89 * @return the channel or null if the transport cannot
90 * generate connections to this endpoint
91 */
92 public abstract Channel getChannel(Endpoint ep);
93
94 /**
95 * Removes the <I>Channel</I> that generates connections to the
96 * endpoint <I>ep</I>.
97 */
98 public abstract void free(Endpoint ep);
99
100 /**
101 * Export the object so that it can accept incoming calls.
102 */
103 public void exportObject(Target target) throws RemoteException {
104 target.setExportedTransport(this);
105 ObjectTable.putTarget(target);
106 }
107
108 /**
109 * Invoked when an object that was exported on this transport has
110 * become unexported, either by being garbage collected or by
111 * being explicitly unexported.
112 **/
113 protected void targetUnexported() { }
114
115 /**
116 * Returns the current transport if a call is being serviced, otherwise
117 * returns null.
118 **/
119 static Transport currentTransport() {
120 return (Transport) currentTransport.get();
121 }
122
123 /**
124 * Verify that the current access control context has permission to accept
125 * the connection being dispatched by the current thread. The current
126 * access control context is passed as a parameter to avoid the overhead of
127 * an additional call to AccessController.getContext.
128 */
129 protected abstract void checkAcceptPermission(AccessControlContext acc);
130
131 /**
132 * Sets the context class loader for the current thread.
133 */
134 private static void setContextClassLoader(final ClassLoader ccl) {
135 AccessController.doPrivileged(new PrivilegedAction<Void> () {
136 public Void run() {
137 Thread.currentThread().setContextClassLoader(ccl);
138 return null;
139 }
140 }, SETCCL_ACC);
141 }
142
143 /**
144 * Service an incoming remote call. When a message arrives on the
145 * connection indicating the beginning of a remote call, the
146 * threads are required to call the <I>serviceCall</I> method of
147 * their transport. The default implementation of this method
148 * locates and calls the dispatcher object. Ordinarily a
149 * transport implementation will not need to override this method.
150 * At the entry to <I>tr.serviceCall(conn)</I>, the connection's
151 * input stream is positioned at the start of the incoming
152 * message. The <I>serviceCall</I> method processes the incoming
153 * remote invocation and sends the result on the connection's
154 * output stream. If it returns "true", then the remote
155 * invocation was processed without error and the transport can
156 * cache the connection. If it returns "false", a protocol error
157 * occurred during the call, and the transport should destroy the
158 * connection.
159 */
160 public boolean serviceCall(final RemoteCall call) {
161 try {
162 /* read object id */
163 final Remote impl;
164 ObjID id;
165
166 try {
167 id = ObjID.read(call.getInputStream());
168 } catch (java.io.IOException e) {
169 throw new MarshalException("unable to read objID", e);
170 }
171
172 /* get the remote object */
173 Transport transport = id.equals(dgcID) ? null : this;
174 Target target =
175 ObjectTable.getTarget(new ObjectEndpoint(id, transport));
176
177 if (target == null || (impl = target.getImpl()) == null) {
178 throw new NoSuchObjectException("no such object in table");
179 }
180
181 final Dispatcher disp = target.getDispatcher();
182 target.incrementCallCount();
183 try {
184 /* call the dispatcher */
185 transportLog.log(Log.VERBOSE, "call dispatcher");
186
187 final AccessControlContext acc =
188 target.getAccessControlContext();
189 ClassLoader ccl = target.getContextClassLoader();
190
191 ClassLoader savedCcl = Thread.currentThread().getContextClassLoader();
192
193 try {
194 setContextClassLoader(ccl);
195 currentTransport.set(this);
196 try {
197 java.security.AccessController.doPrivileged(
198 new java.security.PrivilegedExceptionAction<Void>() {
199 public Void run() throws IOException {
200 checkAcceptPermission(acc);
201 disp.dispatch(impl, call);
202 return null;
203 }
204 }, acc);
205 } catch (java.security.PrivilegedActionException pae) {
206 throw (IOException) pae.getException();
207 }
208 } finally {
209 setContextClassLoader(savedCcl);
210 currentTransport.set(null);
211 }
212
213 } catch (IOException ex) {
214 transportLog.log(Log.BRIEF,
215 "exception thrown by dispatcher: ", ex);
216 return false;
217 } finally {
218 target.decrementCallCount();
219 }
220
221 } catch (RemoteException e) {
222
223 // if calls are being logged, write out exception
224 if (UnicastServerRef.callLog.isLoggable(Log.BRIEF)) {
225 // include client host name if possible
226 String clientHost = "";
227 try {
228 clientHost = "[" +
229 RemoteServer.getClientHost() + "] ";
230 } catch (ServerNotActiveException ex) {
231 }
232 String message = clientHost + "exception: ";
233 UnicastServerRef.callLog.log(Log.BRIEF, message, e);
234 }
235
236 /* We will get a RemoteException if either a) the objID is
237 * not readable, b) the target is not in the object table, or
238 * c) the object is in the midst of being unexported (note:
239 * NoSuchObjectException is thrown by the incrementCallCount
240 * method if the object is being unexported). Here it is
241 * relatively safe to marshal an exception to the client
242 * since the client will not have seen a return value yet.
243 */
244 try {
245 ObjectOutput out = call.getResultStream(false);
246 UnicastServerRef.clearStackTraces(e);
247 out.writeObject(e);
248 call.releaseOutputStream();
249
250 } catch (IOException ie) {
251 transportLog.log(Log.BRIEF,
252 "exception thrown marshalling exception: ", ie);
253 return false;
254 }
255 }
256
257 return true;
258 }
259 }