Interface SocketOptions

Interface of methods to get/set socket options. This interface is implemented by: SocketImpl and DatagramSocketImpl. Subclasses of these should override the methods of this interface in order to support their own options.

The methods and constants which specify options in this interface are for implementation only. If you're not subclassing SocketImpl or DatagramSocketImpl, you won't use these directly. There are type-safe methods to get/set each of these options in Socket, ServerSocket, DatagramSocket and MulticastSocket.

Fields

TCP_NODELAY

@Native
static final int TCP_NODELAY

See Also:

Socket.setTcpNoDelay(boolean), Socket.getTcpNoDelay(), Constant Field Values

SO_BINDADDR

@Native
static final int SO_BINDADDR

See Also:

Socket.getLocalAddress(), DatagramSocket.getLocalAddress(), Constant Field Values

SO_REUSEADDR

@Native
static final int SO_REUSEADDR

See Also:

Constant Field Values

SO_BROADCAST

@Native
static final int SO_BROADCAST

Sets SO_BROADCAST for a socket. This option enables and disables the ability of the process to send broadcast messages. It is supported for only datagram sockets and only on networks that support the concept of a broadcast message (e.g. Ethernet, token ring, etc.), and it is set by default for DatagramSockets.

Since:

1.4

See Also:

Constant Field Values

IP_MULTICAST_IF

@Native
static final int IP_MULTICAST_IF

See Also:

MulticastSocket.setInterface(InetAddress), MulticastSocket.getInterface(), Constant Field Values

IP_MULTICAST_IF2

@Native
static final int IP_MULTICAST_IF2

Same as above. This option is introduced so that the behaviour with IP_MULTICAST_IF will be kept the same as before, while this new option can support setting outgoing interfaces with either IPv4 and IPv6 addresses. NOTE: make sure there is no conflict with this

Since:

1.4

See Also:

MulticastSocket.setNetworkInterface(NetworkInterface), MulticastSocket.getNetworkInterface(), Constant Field Values

IP_MULTICAST_LOOP

@Native
static final int IP_MULTICAST_LOOP

This option enables or disables local loopback of multicast datagrams. This option is enabled by default for Multicast Sockets.

Since:

1.4

See Also:

Constant Field Values

IP_TOS

@Native
static final int IP_TOS

This option sets the type-of-service or traffic class field in the IP header for a TCP or UDP socket.

Since:

1.4

See Also:

Constant Field Values

SO_LINGER

@Native
static final int SO_LINGER

See Also:

Socket.setSoLinger(boolean, int), Socket.getSoLinger(), Constant Field Values

SO_TIMEOUT

@Native
static final int SO_TIMEOUT

ServerSocket.accept();
 SocketInputStream.read();
 DatagramSocket.receive();

See Also:

Socket.setSoTimeout(int), ServerSocket.setSoTimeout(int), DatagramSocket.setSoTimeout(int), Constant Field Values

SO_SNDBUF

@Native
static final int SO_SNDBUF

Set a hint the size of the underlying buffers used by the platform for outgoing network I/O. When used in set, this is a suggestion to the kernel from the application about the size of buffers to use for the data to be sent over the socket. When used in get, this must return the size of the buffer actually used by the platform when sending out data on this socket. Valid for all sockets: SocketImpl, DatagramSocketImpl

See Also:

Socket.setSendBufferSize(int), Socket.getSendBufferSize(), DatagramSocket.setSendBufferSize(int), DatagramSocket.getSendBufferSize(), Constant Field Values

SO_RCVBUF

@Native
static final int SO_RCVBUF

Set a hint the size of the underlying buffers used by the platform for incoming network I/O. When used in set, this is a suggestion to the kernel from the application about the size of buffers to use for the data to be received over the socket. When used in get, this must return the size of the buffer actually used by the platform when receiving in data on this socket. Valid for all sockets: SocketImpl, DatagramSocketImpl

See Also:

Socket.setReceiveBufferSize(int), Socket.getReceiveBufferSize(), DatagramSocket.setReceiveBufferSize(int), DatagramSocket.getReceiveBufferSize(), Constant Field Values

SO_KEEPALIVE

@Native
static final int SO_KEEPALIVE

When the keepalive option is set for a TCP socket and no data has been exchanged across the socket in either direction for 2 hours (NOTE: the actual value is implementation dependent), TCP automatically sends a keepalive probe to the peer. This probe is a TCP segment to which the peer must respond. One of three responses is expected: 1. The peer responds with the expected ACK. The application is not notified (since everything is OK). TCP will send another probe following another 2 hours of inactivity. 2. The peer responds with an RST, which tells the local TCP that the peer host has crashed and rebooted. The socket is closed. 3. There is no response from the peer. The socket is closed. The purpose of this option is to detect if the peer host crashes. Valid only for TCP socket: SocketImpl

See Also:

Socket.setKeepAlive(boolean), Socket.getKeepAlive(), Constant Field Values

SO_OOBINLINE

@Native
static final int SO_OOBINLINE

When the OOBINLINE option is set, any TCP urgent data received on the socket will be received through the socket input stream. When the option is disabled (which is the default) urgent data is silently discarded.

See Also:

Socket.setOOBInline(boolean), Socket.getOOBInline(), Constant Field Values

Methods

setOption

void setOption(int optID,
               Object value)
        throws SocketException

Enable/disable the option specified by optID. If the option is to be enabled, and it takes an option-specific "value", this is passed in value. The actual type of value is option-specific, and it is an error to pass something that isn't of the expected type:

SocketImpl s;
 ...
 s.setOption(SO_LINGER, new Integer(10));
    // OK - set SO_LINGER w/ timeout of 10 sec.
 s.setOption(SO_LINGER, new Double(10));
    // ERROR - expects java.lang.Integer

s.setOption(TCP_NODELAY, new Boolean(true));
    // OK - enables TCP_NODELAY, a binary option

s.setOption(TCP_NODELAY, new Boolean(false));
    // OK - disables TCP_NODELAY
 s.setOption(SO_LINGER, new Boolean(false));
    // OK - disables SO_LINGER

Parameters:

optID - identifies the option

value - the parameter of the socket option

Throws:

SocketException - if the option is unrecognized, the socket is closed, or some low-level error occurred

See Also:

getOption(int)

getOption

Object getOption(int optID)
          throws SocketException

SocketImpl s;
 ...
 Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
 if (noDelay.booleanValue()) {
     // true if TCP_NODELAY is enabled...
 ...
 }

Object o = s.getOption(SO_LINGER);
 if (o instanceof Integer) {
     System.out.print("Linger time is " + ((Integer)o).intValue());
 } else {
   // the true type of o is java.lang.Boolean(false);
 }

Parameters:

optID - an int identifying the option to fetch

Returns:

the value of the option

Throws:

SocketException - if the socket is closed

SocketException - if optID is unknown along the protocol stack (including the SocketImpl)

See Also:

setOption(int, java.lang.Object)