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/*
* Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package sun.nio.ch;
import java.lang.reflect.Constructor;
import java.io.FileDescriptor;
import java.io.IOException;
import java.net.InetAddress;
import java.net.Inet6Address;
import java.net.InetSocketAddress;
import java.net.ProtocolFamily;
import java.net.SocketAddress;
import java.net.UnixDomainSocketAddress;
import java.nio.channels.Channel;
import java.nio.channels.spi.SelectorProvider;
import static java.net.StandardProtocolFamily.INET6;
import static java.net.StandardProtocolFamily.INET;
import static java.net.StandardProtocolFamily.UNIX;
class InheritedChannel {
// the "types" of socket returned by soType0
private static final int UNKNOWN = -1;
private static final int SOCK_STREAM = 1;
private static final int SOCK_DGRAM = 2;
// socket address type
static final int AF_UNKNOWN = -1;
static final int AF_INET = 1;
static final int AF_INET6 = 2;
static final int AF_UNIX = 3;
// oflag values when opening a file
private static final int O_RDONLY = 0;
private static final int O_WRONLY = 1;
private static final int O_RDWR = 2;
/*
* In order to "detach" the standard streams we dup them to /dev/null.
* In order to reduce the possibility of an error at close time we
* open /dev/null early - that way we know we won't run out of file
* descriptors at close time. This makes the close operation a
* simple dup2 operation for each of the standard streams.
*/
private static int devnull = -1;
private static void detachIOStreams() {
try {
dup2(devnull, 0);
dup2(devnull, 1);
dup2(devnull, 2);
} catch (IOException ioe) {
// this shouldn't happen
throw new InternalError(ioe);
}
}
static ProtocolFamily protocolFamily(SocketAddress sa) {
if (sa instanceof UnixDomainSocketAddress) {
return UNIX;
} else {
InetSocketAddress isa = (InetSocketAddress) sa;
return (isa.getAddress() instanceof Inet6Address) ? INET6 : INET;
}
}
static ProtocolFamily protocolFamily(int family) {
return switch (family) {
case AF_INET -> INET;
case AF_INET6 -> INET6;
case AF_UNIX -> UNIX;
default -> throw new IllegalArgumentException();
};
}
/*
* Override the implCloseSelectableChannel for each channel type - this
* allows us to "detach" the standard streams after closing and ensures
* that the underlying socket really closes.
*/
public static class InheritedSocketChannelImpl extends SocketChannelImpl {
InheritedSocketChannelImpl(SelectorProvider sp,
FileDescriptor fd,
SocketAddress remote)
throws IOException
{
super(sp, protocolFamily(remote), fd, remote);
}
protected void implCloseSelectableChannel() throws IOException {
super.implCloseSelectableChannel();
detachIOStreams();
}
}
public static class InheritedServerSocketChannelImpl extends ServerSocketChannelImpl {
InheritedServerSocketChannelImpl(SelectorProvider sp,
ProtocolFamily family,
FileDescriptor fd)
throws IOException
{
super(sp, family, fd, true);
}
@Override
protected void implCloseSelectableChannel() throws IOException {
super.implCloseSelectableChannel();
detachIOStreams();
}
}
public static class InheritedDatagramChannelImpl extends DatagramChannelImpl {
InheritedDatagramChannelImpl(SelectorProvider sp,
FileDescriptor fd)
throws IOException
{
super(sp, fd);
}
protected void implCloseSelectableChannel() throws IOException {
super.implCloseSelectableChannel();
detachIOStreams();
}
}
/*
* If there's a SecurityManager then check for the appropriate
* RuntimePermission.
*/
private static void checkAccess() {
@SuppressWarnings("removal")
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(new RuntimePermission("inheritedChannel"));
}
}
/*
* If standard inherited channel is connected to a socket then return a Channel
* of the appropriate type based standard input.
*/
private static Channel createChannel() throws IOException {
// dup the file descriptor - we do this so that for two reasons :-
// 1. Avoids any timing issues with FileDescriptor.in being closed
// or redirected while we create the channel.
// 2. Allows streams based on file descriptor 0 to co-exist with
// the channel (closing one doesn't impact the other)
int fdVal = dup(0);
// Examine the file descriptor - if it's not a socket then we don't
// create a channel so we release the file descriptor.
int st;
st = soType0(fdVal);
if (st != SOCK_STREAM && st != SOCK_DGRAM) {
close0(fdVal);
return null;
}
// Next we create a FileDescriptor for the dup'ed file descriptor
// Have to use reflection and also make assumption on how FD
// is implemented.
Class<?> paramTypes[] = { int.class };
Constructor<?> ctr = Reflect.lookupConstructor("java.io.FileDescriptor",
paramTypes);
Object args[] = { Integer.valueOf(fdVal) };
FileDescriptor fd = (FileDescriptor)Reflect.invoke(ctr, args);
// Now create the channel. If the socket is a streams socket then
// we see if there is a peer (ie: connected). If so, then we
// create a SocketChannel, otherwise a ServerSocketChannel.
// If the socket is a datagram socket then create a DatagramChannel
SelectorProvider provider = SelectorProvider.provider();
assert provider instanceof sun.nio.ch.SelectorProviderImpl;
Channel c;
if (st == SOCK_STREAM) {
int family = addressFamily(fdVal);
if (family == AF_UNKNOWN)
return null;
ProtocolFamily pfamily = protocolFamily(family);
if (family == AF_UNIX) {
if (isConnected(fdVal)) {
var sa = UnixDomainSocketAddress.of(unixPeerAddress(fdVal));
return new InheritedSocketChannelImpl(provider, fd, sa);
} else {
return new InheritedServerSocketChannelImpl(provider, pfamily, fd);
}
}
InetAddress ia = inetPeerAddress0(fdVal);
if (ia == null) {
c = new InheritedServerSocketChannelImpl(provider, pfamily, fd);
} else {
int port = peerPort0(fdVal);
assert port > 0;
InetSocketAddress isa = new InetSocketAddress(ia, port);
c = new InheritedSocketChannelImpl(provider, fd, isa);
}
} else {
c = new InheritedDatagramChannelImpl(provider, fd);
}
return c;
}
private static boolean haveChannel = false;
private static Channel channel = null;
/*
* Returns a Channel representing the inherited channel if the
* inherited channel is a stream connected to a network socket.
*/
public static synchronized Channel getChannel() throws IOException {
if (devnull < 0) {
devnull = open0("/dev/null", O_RDWR);
}
// If we don't have the channel try to create it
if (!haveChannel) {
channel = createChannel();
haveChannel = true;
}
// if there is a channel then do the security check before
// returning it.
if (channel != null) {
checkAccess();
}
return channel;
}
private static String unixPeerAddress(int fd) throws IOException {
byte[] bytes = unixPeerAddress0(fd);
return new String(bytes);
}
// -- Native methods --
private static native void initIDs();
private static native int dup(int fd) throws IOException;
private static native void dup2(int fd, int fd2) throws IOException;
private static native int open0(String path, int oflag) throws IOException;
private static native void close0(int fd) throws IOException;
private static native int soType0(int fd);
private static native int addressFamily(int fd);
private static native InetAddress inetPeerAddress0(int fd);
private static native byte[] unixPeerAddress0(int fd);
private static native int peerPort0(int fd);
// return true if socket is connected to a peer
private static native boolean isConnected(int fd);
static {
IOUtil.load();
initIDs();
}
}