org.rnorth.tcpunixsocketproxy.TcpToUnixSocketProxy Maven / Gradle / Ivy
package org.rnorth.tcpunixsocketproxy;
import org.newsclub.net.unix.AFUNIXSocket;
import org.newsclub.net.unix.AFUNIXSocketAddress;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
/**
* Listens on a TCP port and proxies connections to a UNIX domain socket.
*
* Like socat TCP-LISTEN:2375,fork UNIX-CONNECT:/var/tmp/docker.sock, except this is literally the only
* thing this program does.
*
* Purposefully simplistic in implementation, using blocking I/O for simplicity over performance.
*
* @author Richard North <[email protected]>
*/
public class TcpToUnixSocketProxy {
private final String listenHostname;
private final int listenPort;
private final File unixSocketFile;
private ServerSocket listenSocket;
private static final Logger logger = LoggerFactory.getLogger(ProxyThread.class);
private Thread acceptThread;
private boolean running = true;
/**
* Create an instance of the proxy that will listen for TCP connections on localhost on a
* random available port.
*
This should be the usual method of instantiating a proxy.
* @param unixSocketFile the local unix domain socket as a File
*/
public TcpToUnixSocketProxy(File unixSocketFile) {
if (!unixSocketFile.exists()) {
throw new IllegalArgumentException("Socket file does not exist: " + unixSocketFile);
}
this.listenHostname = "localhost";
this.listenPort = 0;
this.unixSocketFile = unixSocketFile;
}
/**
* Create an instance of the proxy.
* @param listenHostname hostname to listen on
* @param listenPort port to listen on, or 0 if an available port should be allocated
* @param unixSocketFile the local unix domain socket as a File
*/
public TcpToUnixSocketProxy(String listenHostname, int listenPort, File unixSocketFile) {
if (!unixSocketFile.exists()) {
throw new IllegalArgumentException("Socket file does not exist: " + unixSocketFile);
}
this.listenHostname = listenHostname;
this.listenPort = listenPort;
this.unixSocketFile = unixSocketFile;
}
/**
* Start the proxy
* @return the proxy's listening socket address
* @throws IOException on socket binding failure
*/
public InetSocketAddress start() throws IOException {
listenSocket = new ServerSocket();
listenSocket.bind(new InetSocketAddress(listenHostname, listenPort));
logger.debug("Listening on {} and proxying to {}", listenSocket.getLocalSocketAddress(), unixSocketFile.getAbsolutePath());
acceptThread = new Thread(() -> {
while (running) {
try {
Socket incomingSocket = listenSocket.accept();
logger.debug("Accepting incoming connection from {}", incomingSocket.getRemoteSocketAddress());
AFUNIXSocket outgoingSocket = AFUNIXSocket.newInstance();
outgoingSocket.connect(new AFUNIXSocketAddress(unixSocketFile));
new ProxyThread(incomingSocket, outgoingSocket);
} catch (IOException ignored) {
}
}
});
acceptThread.start();
return (InetSocketAddress) listenSocket.getLocalSocketAddress();
}
/**
* Stop the proxy.
*/
public void stop() {
try {
running = false;
listenSocket.close();
} catch (IOException ignored) {
}
}
}