Java Code Examples for android.system.Os#bind()

protected void setupSocket(
        int sockType, int protocol, long writeTimeout, long readTimeout, int dstPort)
        throws ErrnoException, IOException {
    final int oldTag = TrafficStats.getAndSetThreadStatsTag(TrafficStats.TAG_SYSTEM_PROBE);
    try {
        mFileDescriptor = Os.socket(mAddressFamily, sockType, protocol);
    } finally {
        TrafficStats.setThreadStatsTag(oldTag);
    }
    // Setting SNDTIMEO is purely for defensive purposes.
    Os.setsockoptTimeval(mFileDescriptor,
            SOL_SOCKET, SO_SNDTIMEO, StructTimeval.fromMillis(writeTimeout));
    Os.setsockoptTimeval(mFileDescriptor,
            SOL_SOCKET, SO_RCVTIMEO, StructTimeval.fromMillis(readTimeout));
    // TODO: Use IP_RECVERR/IPV6_RECVERR, pending OsContants availability.
    mNetwork.bindSocket(mFileDescriptor);
    if (mSource != null) {
        Os.bind(mFileDescriptor, mSource, 0);
    }
    Os.connect(mFileDescriptor, mTarget, dstPort);
    mSocketAddress = Os.getsockname(mFileDescriptor);
}
 

/**
 * This function finds and forcibly binds to a random system port, ensuring that the port cannot
 * be unbound.
 *
 * <p>A socket cannot be un-bound from a port if it was bound to that port by number. To select
 * a random open port and then bind by number, this function creates a temp socket, binds to a
 * random port (specifying 0), gets that port number, and then uses is to bind the user's UDP
 * Encapsulation Socket forcibly, so that it cannot be un-bound by the user with the returned
 * FileHandle.
 *
 * <p>The loop in this function handles the inherent race window between un-binding to a port
 * and re-binding, during which the system could *technically* hand that port out to someone
 * else.
 */
private int bindToRandomPort(FileDescriptor sockFd) throws IOException {
    for (int i = MAX_PORT_BIND_ATTEMPTS; i > 0; i--) {
        try {
            FileDescriptor probeSocket = Os.socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
            Os.bind(probeSocket, INADDR_ANY, 0);
            int port = ((InetSocketAddress) Os.getsockname(probeSocket)).getPort();
            Os.close(probeSocket);
            Log.v(TAG, "Binding to port " + port);
            Os.bind(sockFd, INADDR_ANY, port);
            return port;
        } catch (ErrnoException e) {
            // Someone miraculously claimed the port just after we closed probeSocket.
            if (e.errno == OsConstants.EADDRINUSE) {
                continue;
            }
            throw e.rethrowAsIOException();
        }
    }
    throw new IOException("Failed " + MAX_PORT_BIND_ATTEMPTS + " attempts to bind to a port");
}
 

/**
 * Open a socket via the system server and bind it to the specified port (random if port=0).
 * This will return a PFD to the user that represent a bound UDP socket. The system server will
 * cache the socket and a record of its owner so that it can and must be freed when no longer
 * needed.
 */
@Override
public synchronized IpSecUdpEncapResponse openUdpEncapsulationSocket(int port, IBinder binder)
        throws RemoteException {
    if (port != 0 && (port < FREE_PORT_MIN || port > PORT_MAX)) {
        throw new IllegalArgumentException(
                "Specified port number must be a valid non-reserved UDP port");
    }
    checkNotNull(binder, "Null Binder passed to openUdpEncapsulationSocket");

    int callingUid = Binder.getCallingUid();
    UserRecord userRecord = mUserResourceTracker.getUserRecord(callingUid);
    final int resourceId = mNextResourceId++;
    FileDescriptor sockFd = null;
    try {
        if (!userRecord.mSocketQuotaTracker.isAvailable()) {
            return new IpSecUdpEncapResponse(IpSecManager.Status.RESOURCE_UNAVAILABLE);
        }

        sockFd = Os.socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
        mUidFdTagger.tag(sockFd, callingUid);

        // This code is common to both the unspecified and specified port cases
        Os.setsockoptInt(
                sockFd,
                OsConstants.IPPROTO_UDP,
                OsConstants.UDP_ENCAP,
                OsConstants.UDP_ENCAP_ESPINUDP);

        mSrvConfig.getNetdInstance().ipSecSetEncapSocketOwner(sockFd, callingUid);
        if (port != 0) {
            Log.v(TAG, "Binding to port " + port);
            Os.bind(sockFd, INADDR_ANY, port);
        } else {
            port = bindToRandomPort(sockFd);
        }

        userRecord.mEncapSocketRecords.put(
                resourceId,
                new RefcountedResource<EncapSocketRecord>(
                        new EncapSocketRecord(resourceId, sockFd, port), binder));
        return new IpSecUdpEncapResponse(IpSecManager.Status.OK, resourceId, port, sockFd);
    } catch (IOException | ErrnoException e) {
        IoUtils.closeQuietly(sockFd);
    }
    // If we make it to here, then something has gone wrong and we couldn't open a socket.
    // The only reasonable condition that would cause that is resource unavailable.
    return new IpSecUdpEncapResponse(IpSecManager.Status.RESOURCE_UNAVAILABLE);
}