// Copyright (C) 2009 The Android Open Source Project
//
// 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 com.google.gerrit.sshd;
import com.google.common.util.concurrent.Atomics;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.git.WorkQueue;
import com.google.gerrit.sshd.SshScope.Context;
import com.google.inject.Inject;
import com.google.inject.Provider;
import org.apache.sshd.server.Command;
import org.apache.sshd.server.CommandFactory;
import org.apache.sshd.server.Environment;
import org.apache.sshd.server.ExitCallback;
import org.apache.sshd.server.SessionAware;
import org.apache.sshd.server.session.ServerSession;
import org.eclipse.jgit.lib.Config;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
/**
* Creates a CommandFactory using commands registered by {@link CommandModule}.
*/
class CommandFactoryProvider implements Provider<CommandFactory> {
private static final Logger logger = LoggerFactory
.getLogger(CommandFactoryProvider.class);
private final DispatchCommandProvider dispatcher;
private final SshLog log;
private final SshScope sshScope;
private final ScheduledExecutorService startExecutor;
private final Executor destroyExecutor;
@Inject
CommandFactoryProvider(
@CommandName(Commands.ROOT) final DispatchCommandProvider d,
@GerritServerConfig final Config cfg, final WorkQueue workQueue,
final SshLog l, final SshScope s) {
dispatcher = d;
log = l;
sshScope = s;
int threads = cfg.getInt("sshd","commandStartThreads", 2);
startExecutor = workQueue.createQueue(threads, "SshCommandStart");
destroyExecutor = Executors.newSingleThreadExecutor(
new ThreadFactoryBuilder()
.setNameFormat("SshCommandDestroy-%s")
.setDaemon(true)
.build());
}
@Override
public CommandFactory get() {
return new CommandFactory() {
public Command createCommand(final String requestCommand) {
return new Trampoline(requestCommand);
}
};
}
private class Trampoline implements Command, SessionAware {
private final String commandLine;
private final String[] argv;
private InputStream in;
private OutputStream out;
private OutputStream err;
private ExitCallback exit;
private Environment env;
private Context ctx;
private DispatchCommand cmd;
private final AtomicBoolean logged;
private final AtomicReference<Future<?>> task;
Trampoline(final String cmdLine) {
commandLine = cmdLine;
argv = split(cmdLine);
logged = new AtomicBoolean();
task = Atomics.newReference();
}
public void setInputStream(final InputStream in) {
this.in = in;
}
public void setOutputStream(final OutputStream out) {
this.out = out;
}
public void setErrorStream(final OutputStream err) {
this.err = err;
}
public void setExitCallback(final ExitCallback callback) {
this.exit = callback;
}
public void setSession(final ServerSession session) {
final SshSession s = session.getAttribute(SshSession.KEY);
this.ctx = sshScope.newContext(s, commandLine);
}
public void start(final Environment env) throws IOException {
this.env = env;
final Context ctx = this.ctx;
task.set(startExecutor.submit(new Runnable() {
public void run() {
try {
onStart();
} catch (Exception e) {
logger.warn("Cannot start command \"" + ctx.getCommandLine()
+ "\" for user " + ctx.getSession().getUsername(), e);
}
}
@Override
public String toString() {
return "start (user " + ctx.getSession().getUsername() + ")";
}
}));
}
private void onStart() throws IOException {
synchronized (this) {
final Context old = sshScope.set(ctx);
try {
cmd = dispatcher.get();
cmd.setArguments(argv);
cmd.setInputStream(in);
cmd.setOutputStream(out);
cmd.setErrorStream(err);
cmd.setExitCallback(new ExitCallback() {
@Override
public void onExit(int rc, String exitMessage) {
exit.onExit(translateExit(rc), exitMessage);
log(rc);
}
@Override
public void onExit(int rc) {
exit.onExit(translateExit(rc));
log(rc);
}
});
cmd.start(env);
} finally {
sshScope.set(old);
}
}
}
private int translateExit(final int rc) {
switch (rc) {
case BaseCommand.STATUS_NOT_ADMIN:
return 1;
case BaseCommand.STATUS_CANCEL:
return 15 /* SIGKILL */;
case BaseCommand.STATUS_NOT_FOUND:
return 127 /* POSIX not found */;
default:
return rc;
}
}
private void log(final int rc) {
if (logged.compareAndSet(false, true)) {
log.onExecute(rc);
}
}
@Override
public void destroy() {
Future<?> future = task.getAndSet(null);
if (future != null) {
future.cancel(true);
destroyExecutor.execute(new Runnable() {
@Override
public void run() {
onDestroy();
}
});
}
}
private void onDestroy() {
synchronized (this) {
if (cmd != null) {
final Context old = sshScope.set(ctx);
try {
cmd.destroy();
log(BaseCommand.STATUS_CANCEL);
} finally {
ctx = null;
cmd = null;
sshScope.set(old);
}
}
}
}
}
/** Split a command line into a string array. */
static String[] split(String commandLine) {
final List<String> list = new ArrayList<String>();
boolean inquote = false;
boolean inDblQuote = false;
StringBuilder r = new StringBuilder();
for (int ip = 0; ip < commandLine.length();) {
final char b = commandLine.charAt(ip++);
switch (b) {
case '\t':
case ' ':
if (inquote || inDblQuote)
r.append(b);
else if (r.length() > 0) {
list.add(r.toString());
r = new StringBuilder();
}
continue;
case '\"':
if (inquote)
r.append(b);
else
inDblQuote = !inDblQuote;
continue;
case '\'':
if (inDblQuote)
r.append(b);
else
inquote = !inquote;
continue;
case '\\':
if (inquote || ip == commandLine.length())
r.append(b); // literal within a quote
else
r.append(commandLine.charAt(ip++));
continue;
default:
r.append(b);
continue;
}
}
if (r.length() > 0) {
list.add(r.toString());
}
return list.toArray(new String[list.size()]);
}
}