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/*
* 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.android.server.vpn;
import android.net.LocalSocket;
import android.net.LocalSocketAddress;
import android.net.vpn.VpnManager;
import android.os.SystemProperties;
import android.util.Log;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Proxy to start, stop and interact with an Android service defined in init.rc.
* The android service is expected to accept connection through Unix domain
* socket. When the proxy successfully starts the service, it will establish a
* socket connection with the service. The socket serves two purposes: (1) send
* commands to the service; (2) for the proxy to know whether the service is
* alive.
*
* After the service receives commands from the proxy, it should return either
* 0 if the service will close the socket (and the proxy will re-establish
* another connection immediately after), or 1 if the socket is remained alive.
*/
public class AndroidServiceProxy extends ProcessProxy {
private static final int WAITING_TIME = 15; // sec
private static final String SVC_STATE_CMD_PREFIX = "init.svc.";
private static final String SVC_START_CMD = "ctl.start";
private static final String SVC_STOP_CMD = "ctl.stop";
private static final String SVC_STATE_RUNNING = "running";
private static final String SVC_STATE_STOPPED = "stopped";
private static final int END_OF_ARGUMENTS = 255;
private static final int STOP_SERVICE = -1;
private static final int AUTH_ERROR_CODE = 51;
private String mServiceName;
private String mSocketName;
private LocalSocket mKeepaliveSocket;
private boolean mControlSocketInUse;
private Integer mSocketResult = null;
private String mTag;
/**
* Creates a proxy with the service name.
* @param serviceName the service name
*/
public AndroidServiceProxy(String serviceName) {
mServiceName = serviceName;
mSocketName = serviceName;
mTag = "SProxy_" + serviceName;
}
@Override
public String getName() {
return "Service " + mServiceName;
}
@Override
public synchronized void stop() {
if (isRunning()) {
try {
setResultAndCloseControlSocket(STOP_SERVICE);
} catch (IOException e) {
// should not occur
throw new RuntimeException(e);
}
}
SystemProperties.set(SVC_STOP_CMD, mServiceName);
}
/**
* Sends a command with arguments to the service through the control socket.
*/
public synchronized void sendCommand(String ...args) throws IOException {
OutputStream out = getControlSocketOutput();
for (String arg : args) outputString(out, arg);
out.write(END_OF_ARGUMENTS);
out.flush();
checkSocketResult();
}
/**
* {@inheritDoc}
* The method returns when the service exits.
*/
@Override
protected void performTask() throws IOException {
String svc = mServiceName;
Log.d(mTag, "+++++ Execute: " + svc);
SystemProperties.set(SVC_START_CMD, svc);
boolean success = blockUntil(SVC_STATE_RUNNING, WAITING_TIME);
if (success) {
Log.d(mTag, "----- Running: " + svc + ", create keepalive socket");
LocalSocket s = mKeepaliveSocket = createServiceSocket();
setState(ProcessState.RUNNING);
if (s == null) {
// no socket connection, stop hosting the service
stop();
return;
}
try {
for (;;) {
InputStream in = s.getInputStream();
int data = in.read();
if (data >= 0) {
Log.d(mTag, "got data from control socket: " + data);
setSocketResult(data);
} else {
// service is gone
if (mControlSocketInUse) setSocketResult(-1);
break;
}
}
Log.d(mTag, "control connection closed");
} catch (IOException e) {
if (e instanceof VpnConnectingError) {
throw e;
} else {
Log.d(mTag, "control socket broken: " + e.getMessage());
}
}
// Wait 5 seconds for the service to exit
success = blockUntil(SVC_STATE_STOPPED, 5);
Log.d(mTag, "stopping " + svc + ", success? " + success);
} else {
setState(ProcessState.STOPPED);
throw new IOException("cannot start service: " + svc);
}
}
private LocalSocket createServiceSocket() throws IOException {
LocalSocket s = new LocalSocket();
LocalSocketAddress a = new LocalSocketAddress(mSocketName,
LocalSocketAddress.Namespace.RESERVED);
// try a few times in case the service has not listen()ed
IOException excp = null;
for (int i = 0; i < 10; i++) {
try {
s.connect(a);
return s;
} catch (IOException e) {
Log.d(mTag, "service not yet listen()ing; try again");
excp = e;
sleep(500);
}
}
throw excp;
}
private OutputStream getControlSocketOutput() throws IOException {
if (mKeepaliveSocket != null) {
mControlSocketInUse = true;
mSocketResult = null;
return mKeepaliveSocket.getOutputStream();
} else {
throw new IOException("no control socket available");
}
}
private void checkSocketResult() throws IOException {
try {
// will be notified when the result comes back from service
if (mSocketResult == null) wait();
} catch (InterruptedException e) {
Log.d(mTag, "checkSocketResult(): " + e);
} finally {
mControlSocketInUse = false;
if ((mSocketResult == null) || (mSocketResult < 0)) {
throw new IOException("socket error, result from service: "
+ mSocketResult);
}
}
}
private synchronized void setSocketResult(int result)
throws VpnConnectingError {
if (mControlSocketInUse) {
mSocketResult = result;
notifyAll();
} else if (result > 0) {
// error from daemon
throw new VpnConnectingError((result == AUTH_ERROR_CODE)
? VpnManager.VPN_ERROR_AUTH
: VpnManager.VPN_ERROR_CONNECTION_FAILED);
}
}
private void setResultAndCloseControlSocket(int result)
throws VpnConnectingError {
setSocketResult(result);
try {
mKeepaliveSocket.shutdownInput();
mKeepaliveSocket.shutdownOutput();
mKeepaliveSocket.close();
} catch (IOException e) {
Log.e(mTag, "close keepalive socket", e);
} finally {
mKeepaliveSocket = null;
}
}
/**
* Waits for the process to be in the expected state. The method returns
* false if after the specified duration (in seconds), the process is still
* not in the expected state.
*/
private boolean blockUntil(String expectedState, int waitTime) {
String cmd = SVC_STATE_CMD_PREFIX + mServiceName;
int sleepTime = 200; // ms
int n = waitTime * 1000 / sleepTime;
for (int i = 0; i < n; i++) {
if (expectedState.equals(SystemProperties.get(cmd))) {
Log.d(mTag, mServiceName + " is " + expectedState + " after "
+ (i * sleepTime) + " msec");
break;
}
sleep(sleepTime);
}
return expectedState.equals(SystemProperties.get(cmd));
}
private void outputString(OutputStream out, String s) throws IOException {
byte[] bytes = s.getBytes();
out.write(bytes.length);
out.write(bytes);
out.flush();
}
}
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