(libc.info.gz) Socket-Level Options

Info Catalog

(libc.info.gz) Socket Option Functions

(libc.info.gz) Socket Options

 
 16.12.2 Socket-Level Options
 ----------------------------
 
  -- Constant: int SOL_SOCKET
      Use this constant as the LEVEL argument to 'getsockopt' or
      'setsockopt' to manipulate the socket-level options described in
      this section.
 
 Here is a table of socket-level option names; all are defined in the
 header file 'sys/socket.h'.
 
 'SO_DEBUG'
 
      This option toggles recording of debugging information in the
      underlying protocol modules.  The value has type 'int'; a nonzero
      value means "yes".
 
 'SO_REUSEADDR'
      This option controls whether 'bind' ( Setting Address)
      should permit reuse of local addresses for this socket.  If you
      enable this option, you can actually have two sockets with the same
      Internet port number; but the system won't allow you to use the two
      identically-named sockets in a way that would confuse the Internet.
      The reason for this option is that some higher-level Internet
      protocols, including FTP, require you to keep reusing the same port
      number.
 
      The value has type 'int'; a nonzero value means "yes".
 
 'SO_KEEPALIVE'
      This option controls whether the underlying protocol should
      periodically transmit messages on a connected socket.  If the peer
      fails to respond to these messages, the connection is considered
      broken.  The value has type 'int'; a nonzero value means "yes".
 
 'SO_DONTROUTE'
      This option controls whether outgoing messages bypass the normal
      message routing facilities.  If set, messages are sent directly to
      the network interface instead.  The value has type 'int'; a nonzero
      value means "yes".
 
 'SO_LINGER'
      This option specifies what should happen when the socket of a type
      that promises reliable delivery still has untransmitted messages
      when it is closed; see  Closing a Socket.  The value has
      type 'struct linger'.
 
       -- Data Type: struct linger
           This structure type has the following members:
 
           'int l_onoff'
                This field is interpreted as a boolean.  If nonzero,
                'close' blocks until the data are transmitted or the
                timeout period has expired.
 
           'int l_linger'
                This specifies the timeout period, in seconds.
 
 'SO_BROADCAST'
      This option controls whether datagrams may be broadcast from the
      socket.  The value has type 'int'; a nonzero value means "yes".
 
 'SO_OOBINLINE'
      If this option is set, out-of-band data received on the socket is
      placed in the normal input queue.  This permits it to be read using
      'read' or 'recv' without specifying the 'MSG_OOB' flag.  
      Out-of-Band Data.  The value has type 'int'; a nonzero value
      means "yes".
 
 'SO_SNDBUF'
      This option gets or sets the size of the output buffer.  The value
      is a 'size_t', which is the size in bytes.
 
 'SO_RCVBUF'
      This option gets or sets the size of the input buffer.  The value
      is a 'size_t', which is the size in bytes.
 
 'SO_STYLE'
 'SO_TYPE'
      This option can be used with 'getsockopt' only.  It is used to get
      the socket's communication style.  'SO_TYPE' is the historical
      name, and 'SO_STYLE' is the preferred name in GNU. The value has
      type 'int' and its value designates a communication style; see
       Communication Styles.
 
 'SO_ERROR'
 
      This option can be used with 'getsockopt' only.  It is used to
      reset the error status of the socket.  The value is an 'int', which
      represents the previous error status.
 

Info Catalog

(libc.info.gz) Socket Option Functions

(libc.info.gz) Socket Options