src/jdk.net/share/classes/jdk/net/ExtendedSocketOptions.java

@@ -178,17 +178,38 @@
       * @since 15
       */
      public static final SocketOption<Integer> SO_INCOMING_NAPI_ID
              = new ExtSocketOption<Integer>("SO_INCOMING_NAPI_ID", Integer.class);
  
+     /**
+      * Unix Domain peer credentials.
+      *
+      * <p> The value of this socket option is a {@link UnixDomainPrincipal} that
+      * represents the credentials of a peer connected to a Unix Domain socket.
+      * The credentials are those that applied at the time the socket was first
+      * connected or accepted.
+      *
+      * <p> The socket option is read-only and an attempt to set the socket option
+      * will throw {@code SocketException}. {@code SocketException} is also thrown
+      * when attempting to get the value of the socket option on an unconnected Unix
+      * Domain socket.
+      *
+      * @since 16
+      */
+     public static final SocketOption<UnixDomainPrincipal> SO_PEERCRED
+         = new ExtSocketOption<UnixDomainPrincipal>
+             ("SO_PEERCRED", UnixDomainPrincipal.class);
+ 
      private static final PlatformSocketOptions platformSocketOptions =
              PlatformSocketOptions.get();
  
      private static final boolean quickAckSupported =
              platformSocketOptions.quickAckSupported();
      private static final boolean keepAliveOptSupported =
              platformSocketOptions.keepAliveOptionsSupported();
+     private static final boolean peerCredentialsSupported =
+             platformSocketOptions.peerCredentialsSupported();
      private static final boolean incomingNapiIdOptSupported  =
              platformSocketOptions.incomingNapiIdSupported();
      private static final Set<SocketOption<?>> extendedOptions = options();
  
      static Set<SocketOption<?>> options() {

@@ -200,10 +221,13 @@
              options.add(SO_INCOMING_NAPI_ID);
          }
          if (keepAliveOptSupported) {
              options.addAll(Set.of(TCP_KEEPCOUNT, TCP_KEEPIDLE, TCP_KEEPINTERVAL));
          }
+         if (peerCredentialsSupported) {
+             options.add(SO_PEERCRED);
+         }
          return Collections.unmodifiableSet(options);
      }
  
      static {
          // Registers the extended socket options with the base module.

@@ -231,10 +255,12 @@
                  } else if (option == SO_INCOMING_NAPI_ID) {
                      if (!incomingNapiIdOptSupported)
                          throw new UnsupportedOperationException("Attempt to set unsupported option " + option);
                      else
                          throw new SocketException("Attempt to set read only option " + option);
+                 } else if (option == SO_PEERCRED) {
+                     throw new SocketException("SO_PEERCRED cannot be set ");
                  } else {
                      throw new InternalError("Unexpected option " + option);
                  }
              }
  

@@ -253,10 +279,12 @@
                      return getTcpkeepAliveProbes(fd);
                  } else if (option == TCP_KEEPIDLE) {
                      return getTcpKeepAliveTime(fd);
                  } else if (option == TCP_KEEPINTERVAL) {
                      return getTcpKeepAliveIntvl(fd);
+                 } else if (option == SO_PEERCRED) {
+                     return getSoPeerCred(fd);
                  } else if (option == SO_INCOMING_NAPI_ID) {
                      return getIncomingNapiId(fd);
                  } else {
                      throw new InternalError("Unexpected option " + option);
                  }

@@ -270,10 +298,15 @@
      private static void setQuickAckOption(FileDescriptor fd, boolean enable)
              throws SocketException {
          platformSocketOptions.setQuickAck(fdAccess.get(fd), enable);
      }
  
+     private static Object getSoPeerCred(FileDescriptor fd)
+             throws SocketException {
+         return platformSocketOptions.getSoPeerCred(fdAccess.get(fd));
+     }
+ 
      private static Object getQuickAckOption(FileDescriptor fd)
              throws SocketException {
          return platformSocketOptions.getQuickAck(fdAccess.get(fd));
      }
  

@@ -343,10 +376,14 @@
  
          static PlatformSocketOptions get() {
              return instance;
          }
  
+         boolean peerCredentialsSupported() {
+             return false;
+         }
+ 
          void setQuickAck(int fd, boolean on) throws SocketException {
              throw new UnsupportedOperationException("unsupported TCP_QUICKACK option");
          }
  
          boolean getQuickAck(int fd) throws SocketException {

@@ -367,10 +404,14 @@
  
          void setTcpKeepAliveTime(int fd, final int value) throws SocketException {
              throw new UnsupportedOperationException("unsupported TCP_KEEPIDLE option");
          }
  
+         UnixDomainPrincipal getSoPeerCred(int fd) throws SocketException {
+             throw new UnsupportedOperationException("unsupported SO_PEERCRED option");
+         }
+ 
          void setTcpKeepAliveIntvl(int fd, final int value) throws SocketException {
              throw new UnsupportedOperationException("unsupported TCP_KEEPINTVL option");
          }
  
          int getTcpkeepAliveProbes(int fd) throws SocketException {