pool: report dcap local endpoint

Motivation:
make all movers to provide the same information

Result:
dcache mover will report local endpoint address

Acked-by: Paul Millar
Target: master
Require-book: no
Require-notes: yes

modules/dcache-dcap/src/main/java/org/dcache/pool/movers/DCapProtocol_3_nio.java

@@ -25,6 +25,7 @@
 import java.nio.channels.SocketChannel;
 import java.nio.file.OpenOption;
 import java.nio.file.StandardOpenOption;
+import java.util.Optional;
 import java.util.Set;
 import java.util.UUID;
 import java.util.function.Consumer;
@@ -72,6 +73,7 @@ public class DCapProtocol_3_nio implements MoverProtocol, ChecksumMover, CellArg
 
     private Consumer<Checksum> _integrityChecker;
 
+    private volatile InetSocketAddress _localEndpoint;
 
     // bind passive dcap to port defined as org.dcache.dcap.port
     private static ProtocolConnectionPoolFactory factory;
@@ -294,6 +296,7 @@ public void runIO(FileAttributes fileAttributes,
         }
 
         Socket socket = socketChannel.socket();
+        _localEndpoint = new InetSocketAddress(socket.getLocalAddress(), socket.getLocalPort());
         socket.setKeepAlive(true);
         socket.setTcpNoDelay(true);
         if (bufferSize.getSendBufferSize() > 0) {
@@ -1025,4 +1028,9 @@ public long getTransferTime() {
               System.currentTimeMillis() - _transferStarted :
               _transferTime;
     }
+
+    @Override
+    public Optional<InetSocketAddress> getLocalEndpoint() {
+        return Optional.ofNullable(_localEndpoint);
+    }
 }