/*
 * Copyright (C) 2007 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 android.net;

import android.system.ErrnoException;
import android.system.Int32Ref;
import android.system.Os;
import android.system.OsConstants;
import android.system.StructLinger;
import android.system.StructTimeval;

import java.io.FileDescriptor;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.SocketOptions;

Socket implementation used for android.net.LocalSocket and
android.net.LocalServerSocket. Supports only AF_LOCAL sockets.
/**
 * Socket implementation used for android.net.LocalSocket and
 * android.net.LocalServerSocket. Supports only AF_LOCAL sockets.
 */
class LocalSocketImpl
{
    private SocketInputStream fis;
    private SocketOutputStream fos;
    private Object readMonitor = new Object();
    private Object writeMonitor = new Object();

    
null if closed or not yet created /** null if closed or not yet created */
    private FileDescriptor fd;
    
whether fd is created internally /** whether fd is created internally */
    private boolean mFdCreatedInternally;

    // These fields are accessed by native code;
    
file descriptor array received during a previous read /** file descriptor array received during a previous read */
    FileDescriptor[] inboundFileDescriptors;
    
file descriptor array that should be written during next write /** file descriptor array that should be written during next write */
    FileDescriptor[] outboundFileDescriptors;

    
An input stream for local sockets. Needed because we may
need to read ancillary data.
/**
     * An input stream for local sockets. Needed because we may
     * need to read ancillary data.
     */
    class SocketInputStream extends InputStream {
        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public int available() throws IOException {
            FileDescriptor myFd = fd;
            if (myFd == null) throw new IOException("socket closed");

            Int32Ref avail = new Int32Ref(0);
            try {
                Os.ioctlInt(myFd, OsConstants.FIONREAD, avail);
            } catch (ErrnoException e) {
                throw e.rethrowAsIOException();
            }
            return avail.value;
        }

        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public void close() throws IOException {
            LocalSocketImpl.this.close();
        }

        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public int read() throws IOException {
            int ret;
            synchronized (readMonitor) {
                FileDescriptor myFd = fd;
                if (myFd == null) throw new IOException("socket closed");

                ret = read_native(myFd);
                return ret;
            }
        }

        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public int read(byte[] b) throws IOException {
            return read(b, 0, b.length);
        }

        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public int read(byte[] b, int off, int len) throws IOException {
            synchronized (readMonitor) {
                FileDescriptor myFd = fd;
                if (myFd == null) throw new IOException("socket closed");

                if (off < 0 || len < 0 || (off + len) > b.length ) {
                    throw new ArrayIndexOutOfBoundsException();
                }

                int ret = readba_native(b, off, len, myFd);

                return ret;
            }
        }
    }

    
An output stream for local sockets. Needed because we may
need to read ancillary data.
/**
     * An output stream for local sockets. Needed because we may
     * need to read ancillary data.
     */
    class SocketOutputStream extends OutputStream {
        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public void close() throws IOException {
            LocalSocketImpl.this.close();
        }

        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public void write (byte[] b) throws IOException {
            write(b, 0, b.length);
        }
        
        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public void write (byte[] b, int off, int len) throws IOException {
            synchronized (writeMonitor) {
                FileDescriptor myFd = fd;
                if (myFd == null) throw new IOException("socket closed");

                if (off < 0 || len < 0 || (off + len) > b.length ) {
                    throw new ArrayIndexOutOfBoundsException();
                }
                writeba_native(b, off, len, myFd);
            }
        }

        
{@inheritDoc} /** {@inheritDoc} */
        @Override
        public void write (int b) throws IOException {
            synchronized (writeMonitor) {
                FileDescriptor myFd = fd;
                if (myFd == null) throw new IOException("socket closed");
                write_native(b, myFd);
            }
        }

        
Wait until the data in sending queue is emptied. A polling version
for flush implementation.
Throws:
IOException – 
            if an i/o error occurs./**
         * Wait until the data in sending queue is emptied. A polling version
         * for flush implementation.
         * @throws IOException
         *             if an i/o error occurs.
         */
        @Override
        public void flush() throws IOException {
            FileDescriptor myFd = fd;
            if (myFd == null) throw new IOException("socket closed");

            // Loop until the output buffer is empty.
            Int32Ref pending = new Int32Ref(0);
            while (true) {
                try {
                    // See linux/net/unix/af_unix.c
                    Os.ioctlInt(myFd, OsConstants.TIOCOUTQ, pending);
                } catch (ErrnoException e) {
                    throw e.rethrowAsIOException();
                }

                if (pending.value <= 0) {
                    // The output buffer is empty.
                    break;
                }

                try {
                    Thread.sleep(10);
                } catch (InterruptedException ie) {
                    break;
                }
            }
        }
    }

    private native int read_native(FileDescriptor fd) throws IOException;
    private native int readba_native(byte[] b, int off, int len,
            FileDescriptor fd) throws IOException;
    private native void writeba_native(byte[] b, int off, int len,
            FileDescriptor fd) throws IOException;
    private native void write_native(int b, FileDescriptor fd)
            throws IOException;
    private native void connectLocal(FileDescriptor fd, String name,
            int namespace) throws IOException;
    private native void bindLocal(FileDescriptor fd, String name, int namespace)
            throws IOException;
    private native Credentials getPeerCredentials_native(
            FileDescriptor fd) throws IOException;

    
Create a new instance.
/**
     * Create a new instance.
     */
    /*package*/ LocalSocketImpl()
    {
    }

    
Create a new instance from a file descriptor representing
a bound socket. The state of the file descriptor is not checked here
 but the caller can verify socket state by calling listen().
Params:
fd – non-null; bound file descriptor/**
     * Create a new instance from a file descriptor representing
     * a bound socket. The state of the file descriptor is not checked here
     *  but the caller can verify socket state by calling listen().
     *
     * @param fd non-null; bound file descriptor
     */
    /*package*/ LocalSocketImpl(FileDescriptor fd)
    {
        this.fd = fd;
    }

    public String toString() {
        return super.toString() + " fd:" + fd;
    }

    
Creates a socket in the underlying OS.
Params:
sockType – either LocalSocket.SOCKET_DGRAM, LocalSocket.SOCKET_STREAM or LocalSocket.SOCKET_SEQPACKET
Throws:
IOException – /**
     * Creates a socket in the underlying OS.
     *
     * @param sockType either {@link LocalSocket#SOCKET_DGRAM}, {@link LocalSocket#SOCKET_STREAM}
     * or {@link LocalSocket#SOCKET_SEQPACKET}
     * @throws IOException
     */
    public void create(int sockType) throws IOException {
        if (fd != null) {
            throw new IOException("LocalSocketImpl already has an fd");
        }

        int osType;
        switch (sockType) {
            case LocalSocket.SOCKET_DGRAM:
                osType = OsConstants.SOCK_DGRAM;
                break;
            case LocalSocket.SOCKET_STREAM:
                osType = OsConstants.SOCK_STREAM;
                break;
            case LocalSocket.SOCKET_SEQPACKET:
                osType = OsConstants.SOCK_SEQPACKET;
                break;
            default:
                throw new IllegalStateException("unknown sockType");
        }
        try {
            fd = Os.socket(OsConstants.AF_UNIX, osType, 0);
            mFdCreatedInternally = true;
        } catch (ErrnoException e) {
            e.rethrowAsIOException();
        }
    }

    
Closes the socket.
Throws:
IOException – /**
     * Closes the socket.
     *
     * @throws IOException
     */
    public void close() throws IOException {
        synchronized (LocalSocketImpl.this) {
            if ((fd == null) || (mFdCreatedInternally == false)) {
                fd = null;
                return;
            }
            try {
                Os.close(fd);
            } catch (ErrnoException e) {
                e.rethrowAsIOException();
            }
            fd = null;
        }
    }

    
note timeout presently ignored /** note timeout presently ignored */
    protected void connect(LocalSocketAddress address, int timeout)
                        throws IOException
    {        
        if (fd == null) {
            throw new IOException("socket not created");
        }

        connectLocal(fd, address.getName(), address.getNamespace().getId());
    }

    
Binds this socket to an endpoint name. May only be called on an instance
that has not yet been bound.
Params:
endpoint – endpoint address
Throws:
IOException – /**
     * Binds this socket to an endpoint name. May only be called on an instance
     * that has not yet been bound.
     *
     * @param endpoint endpoint address
     * @throws IOException
     */
    public void bind(LocalSocketAddress endpoint) throws IOException
    {
        if (fd == null) {
            throw new IOException("socket not created");
        }

        bindLocal(fd, endpoint.getName(), endpoint.getNamespace().getId());
    }

    protected void listen(int backlog) throws IOException
    {
        if (fd == null) {
            throw new IOException("socket not created");
        }
        try {
            Os.listen(fd, backlog);
        } catch (ErrnoException e) {
            throw e.rethrowAsIOException();
        }
    }

    
Accepts a new connection to the socket. Blocks until a new
connection arrives.
Params:
s – a socket that will be used to represent the new connection.
Throws:
IOException – /**
     * Accepts a new connection to the socket. Blocks until a new
     * connection arrives.
     *
     * @param s a socket that will be used to represent the new connection.
     * @throws IOException
     */
    protected void accept(LocalSocketImpl s) throws IOException {
        if (fd == null) {
            throw new IOException("socket not created");
        }

        try {
            s.fd = Os.accept(fd, null /* address */);
            s.mFdCreatedInternally = true;
        } catch (ErrnoException e) {
            throw e.rethrowAsIOException();
        }
    }

    
Retrieves the input stream for this instance.
Throws:
IOException – if socket has been closed or cannot be created.
Returns:
input stream/**
     * Retrieves the input stream for this instance.
     *
     * @return input stream
     * @throws IOException if socket has been closed or cannot be created.
     */
    protected InputStream getInputStream() throws IOException
    {
        if (fd == null) {
            throw new IOException("socket not created");
        }

        synchronized (this) {
            if (fis == null) {
                fis = new SocketInputStream();
            }

            return fis;
        }
    }

    
Retrieves the output stream for this instance.
Throws:
IOException – if socket has been closed or cannot be created.
Returns:
output stream/**
     * Retrieves the output stream for this instance.
     *
     * @return output stream
     * @throws IOException if socket has been closed or cannot be created.
     */
    protected OutputStream getOutputStream() throws IOException
    { 
        if (fd == null) {
            throw new IOException("socket not created");
        }

        synchronized (this) {
            if (fos == null) {
                fos = new SocketOutputStream();
            }

            return fos;
        }
    }

    
Returns the number of bytes available for reading without blocking.
Throws:
IOException – 
Returns:
>= 0 count bytes available/**
     * Returns the number of bytes available for reading without blocking.
     *
     * @return >= 0 count bytes available
     * @throws IOException
     */
    protected int available() throws IOException
    {
        return getInputStream().available();
    }

    
Shuts down the input side of the socket.
Throws:
IOException – /**
     * Shuts down the input side of the socket.
     *
     * @throws IOException
     */
    protected void shutdownInput() throws IOException
    {
        if (fd == null) {
            throw new IOException("socket not created");
        }

        try {
            Os.shutdown(fd, OsConstants.SHUT_RD);
        } catch (ErrnoException e) {
            throw e.rethrowAsIOException();
        }
    }

    
Shuts down the output side of the socket.
Throws:
IOException – /**
     * Shuts down the output side of the socket.
     *
     * @throws IOException
     */
    protected void shutdownOutput() throws IOException
    {
        if (fd == null) {
            throw new IOException("socket not created");
        }

        try {
            Os.shutdown(fd, OsConstants.SHUT_WR);
        } catch (ErrnoException e) {
            throw e.rethrowAsIOException();
        }
    }

    protected FileDescriptor getFileDescriptor()
    {
        return fd;
    }

    protected boolean supportsUrgentData()
    {
        return false;
    }

    protected void sendUrgentData(int data) throws IOException
    {
        throw new RuntimeException ("not impled");
    }

    public Object getOption(int optID) throws IOException
    {
        if (fd == null) {
            throw new IOException("socket not created");
        }

        try {
            Object toReturn;
            switch (optID) {
                case SocketOptions.SO_TIMEOUT:
                    StructTimeval timeval = Os.getsockoptTimeval(fd, OsConstants.SOL_SOCKET,
                            OsConstants.SO_SNDTIMEO);
                    toReturn = (int) timeval.toMillis();
                    break;
                case SocketOptions.SO_RCVBUF:
                case SocketOptions.SO_SNDBUF:
                case SocketOptions.SO_REUSEADDR:
                    int osOpt = javaSoToOsOpt(optID);
                    toReturn = Os.getsockoptInt(fd, OsConstants.SOL_SOCKET, osOpt);
                    break;
                case SocketOptions.SO_LINGER:
                    StructLinger linger=
                            Os.getsockoptLinger(fd, OsConstants.SOL_SOCKET, OsConstants.SO_LINGER);
                    if (!linger.isOn()) {
                        toReturn = -1;
                    } else {
                        toReturn = linger.l_linger;
                    }
                    break;
                case SocketOptions.TCP_NODELAY:
                    toReturn = Os.getsockoptInt(fd, OsConstants.IPPROTO_TCP,
                            OsConstants.TCP_NODELAY);
                    break;
                default:
                    throw new IOException("Unknown option: " + optID);
            }
            return toReturn;
        } catch (ErrnoException e) {
            throw e.rethrowAsIOException();
        }
    }

    public void setOption(int optID, Object value)
            throws IOException {

        if (fd == null) {
            throw new IOException("socket not created");
        }

        /*
         * Boolean.FALSE is used to disable some options, so it
         * is important to distinguish between FALSE and unset.
         * We define it here that -1 is unset, 0 is FALSE, and 1
         * is TRUE.
         */
        int boolValue = -1;
        int intValue = 0;
        if (value instanceof Integer) {
            intValue = (Integer)value;
        } else if (value instanceof Boolean) {
            boolValue = ((Boolean) value)? 1 : 0;
        } else {
            throw new IOException("bad value: " + value);
        }

        try {
            switch (optID) {
                case SocketOptions.SO_LINGER:
                    StructLinger linger = new StructLinger(boolValue, intValue);
                    Os.setsockoptLinger(fd, OsConstants.SOL_SOCKET, OsConstants.SO_LINGER, linger);
                    break;
                case SocketOptions.SO_TIMEOUT:
                    // The option must set both send and receive timeouts.
                    // Note: The incoming timeout value is in milliseconds.
                    StructTimeval timeval = StructTimeval.fromMillis(intValue);
                    Os.setsockoptTimeval(fd, OsConstants.SOL_SOCKET, OsConstants.SO_RCVTIMEO,
                            timeval);
                    Os.setsockoptTimeval(fd, OsConstants.SOL_SOCKET, OsConstants.SO_SNDTIMEO,
                            timeval);
                    break;
                case SocketOptions.SO_RCVBUF:
                case SocketOptions.SO_SNDBUF:
                case SocketOptions.SO_REUSEADDR:
                    int osOpt = javaSoToOsOpt(optID);
                    Os.setsockoptInt(fd, OsConstants.SOL_SOCKET, osOpt, intValue);
                    break;
                case SocketOptions.TCP_NODELAY:
                    Os.setsockoptInt(fd, OsConstants.IPPROTO_TCP, OsConstants.TCP_NODELAY,
                            intValue);
                    break;
                default:
                    throw new IOException("Unknown option: " + optID);
            }
        } catch (ErrnoException e) {
            throw e.rethrowAsIOException();
        }
    }

    
Enqueues a set of file descriptors to send to the peer. The queue
is one deep. The file descriptors will be sent with the next write
of normal data, and will be delivered in a single ancillary message.
See "man 7 unix" SCM_RIGHTS on a desktop Linux machine.
Params:
fds – non-null; file descriptors to send.
Throws:
IOException – /**
     * Enqueues a set of file descriptors to send to the peer. The queue
     * is one deep. The file descriptors will be sent with the next write
     * of normal data, and will be delivered in a single ancillary message.
     * See "man 7 unix" SCM_RIGHTS on a desktop Linux machine.
     *
     * @param fds non-null; file descriptors to send.
     * @throws IOException
     */
    public void setFileDescriptorsForSend(FileDescriptor[] fds) {
        synchronized(writeMonitor) {
            outboundFileDescriptors = fds;
        }
    }

    
Retrieves a set of file descriptors that a peer has sent through
an ancillary message. This method retrieves the most recent set sent,
and then returns null until a new set arrives.
File descriptors may only be passed along with regular data, so this
method can only return a non-null after a read operation.
Throws:
IOException – 
Returns:
null or file descriptor array/**
     * Retrieves a set of file descriptors that a peer has sent through
     * an ancillary message. This method retrieves the most recent set sent,
     * and then returns null until a new set arrives.
     * File descriptors may only be passed along with regular data, so this
     * method can only return a non-null after a read operation.
     *
     * @return null or file descriptor array
     * @throws IOException
     */
    public FileDescriptor[] getAncillaryFileDescriptors() throws IOException {
        synchronized(readMonitor) {
            FileDescriptor[] result = inboundFileDescriptors;

            inboundFileDescriptors = null;
            return result;
        }
    }

    
Retrieves the credentials of this socket's peer. Only valid on
connected sockets.
Throws:
IOException – 
Returns:
non-null; peer credentials/**
     * Retrieves the credentials of this socket's peer. Only valid on
     * connected sockets.
     *
     * @return non-null; peer credentials
     * @throws IOException
     */
    public Credentials getPeerCredentials() throws IOException {
        return getPeerCredentials_native(fd);
    }

    
Retrieves the socket name from the OS.
Throws:
IOException – on failure
Returns:
non-null; socket name/**
     * Retrieves the socket name from the OS.
     *
     * @return non-null; socket name
     * @throws IOException on failure
     */
    public LocalSocketAddress getSockAddress() throws IOException {
        // This method has never been implemented.
        return null;
    }

    @Override
    protected void finalize() throws IOException {
        close();
    }

    private static int javaSoToOsOpt(int optID) {
        switch (optID) {
            case SocketOptions.SO_SNDBUF:
                return OsConstants.SO_SNDBUF;
            case SocketOptions.SO_RCVBUF:
                return OsConstants.SO_RCVBUF;
            case SocketOptions.SO_REUSEADDR:
                return OsConstants.SO_REUSEADDR;
            default:
                throw new UnsupportedOperationException("Unknown option: " + optID);
        }
    }
}