listen(2) [hpux man page]

listen(2)							System Calls Manual							 listen(2)

NAME

       listen - listen for connections on a socket

SYNOPSIS

DESCRIPTION

       To  accept  connections,  a  socket  is	first  created	using a queue for incoming connections is activated using and then connections are
       accepted using applies only to unconnected sockets of type SOCK_STREAM.	Except for AF_VME_LINK, if the socket has  not	been  bound  to  a
       local  port  before is invoked, the system automatically binds a local port for the socket to listen on (see inet(7F)).	For sockets in the
       address family AF_CCITT and AF_VME_LINK, the socket be bound to an address by using before connection establishment can continue, otherwise
       an error is returned.

       A listen queue is established for the socket specified by the s parameter, which is a socket descriptor.

       backlog defines the desirable queue length for pending connections.  The actual queue length may be greater than the specified backlog.	If
       a connection request arrives when the queue is full, the client will receive an error.

       backlog is limited to the range of 0 to which is defined in is currently set to 4096.  If any other value is specified, the system automat-
       ically  assigns	the  closest  value  within the range.	Note that for a backlog of 0 specifies only 1 pending connection is allowed at any
       given time.  For a backlog of 0 specifies no further connection is allowed.

   X/Open Sockets Compilation Environment
       See xopen_networking(7).

DEPENDENCIES

   AF_CCITT
       Call-acceptance can be controlled by the call described in Upon successful completion, returns 0; otherwise, it	returns  -1  and  sets	to
       indicate the error.

ERRORS

       fails if any of the following conditions are encountered:

	      s 		  is not a valid file descriptor.

	      The socket	  s has not been bound to an address by using

	      s 		  is a valid file descriptor but it is not a socket.

	      The socket referenced by
				  s does not support

	      The socket has been shut down or is already connected.

WARNINGS

       Linking	binary	objects  compiled to specification and binary objects compiled to specification to the same executable may result in unex-
       pected behavior, including application abnormal termination and unexpected socket errors.  See xopen_networking(7) for details and remedy.

FUTURE DIRECTION

       Currently, the default behavior is the however, it might be changed to in a future release.  At that time, any behavior that is	incompati-
       ble  with  might be obsoleted.  Applications that conform to the X/Open specification now will avoid migration problems (see xopen_network-
       ing(7)).

AUTHOR

       was developed by HP and the University of California, Berkeley.

SEE ALSO

       accept(2), connect(2), socket(2), thread_safety(5), xopen_networking(7), inet(7F).

STANDARDS CONFORMANCE

																	 listen(2)

accept(2)							System Calls Manual							 accept(2)

NAME

       accept - accept a connection on a socket

SYNOPSIS

   AF_CCITT only
   UNIX 03 only (X/Open Sockets)
   Obsolescent UNIX 95 only (X/Open Sockets)
DESCRIPTION

       The  system  call is used with connection-based socket types, such as The argument, s, is a socket descriptor created with bound to a local
       address by and listening for connections after a extracts the first connection on the queue of pending connections, creates  a  new  socket
       with the same properties as s, and returns a new file descriptor, ns, for the socket.

       If  no  pending connections are present on the queue and nonblocking mode has not been enabled with the or flags or the request, blocks the
       caller until a connection is present.  and are defined in (see fcntl(2), fcntl(5), and socket(7)).  and the equivalent request are  defined
       in although use of is not recommended (see ioctl(2), ioctl(5), and socket(7)).

       If  the	socket has nonblocking mode enabled and no pending connections are present on the queue, returns an error as described below.  The
       accepted socket, ns, cannot be used to accept more connections.	The original socket s remains open for incoming connection  requests.	To
       determine whether a listening socket has pending connection requests ready for an call, use for reading.

       The  argument addr should point to a socket address structure.  The call fills in this structure with the address of the connecting entity,
       as known to the underlying protocol.  In the case of AF_UNIX sockets, the peer's address is filled in only if the peer had done an explicit
       before  doing  a Therefore, for AF_UNIX sockets, in the common case, when the peer had not done an explicit before doing a the structure is
       filled with a string of nulls for the address.  The format of the address depends upon the protocol and the address-family of the socket s.

       The argument addrlen is a pointer to a variable.  Initially, the variable should contain the size of the structure pointed to by addr.	On
       return,	it contains the actual length (in bytes) of the address returned.  If the memory pointed to by addr is not large enough to contain
       the entire address, only the first addrlen bytes of the address are returned.  If addr is  NULL	or  addrlen  contains  0,  the	connecting
       entity's address will not be returned.

       The and flags and request are all supported.  These features interact as follows:

	  o  If the or flag has been set, requests behave accordingly, regardless of any requests.

	  o  If neither the flag nor the flag has been set, requests control the behavior of

   AF_CCITT only
       The addr parameter to returns addressing information for the connecting entity, except for the field of addr which contains the name of the
       local X.25 interface through which the connection request arrived.  Call-acceptance can be controlled with the request.

   X/Open Sockets Compilation Environment
       See xopen_networking(7).

RETURN VALUE

       Upon successful completion, returns a nonnegative integer which is a descriptor for the accepted socket.

       If an error occurs, returns and sets to indicate the cause.

ERRORS

       If fails, is set to one of the following values:

       Nonblocking I/O is enabled using
			   and no connections are present to be accepted.

       The argument,	   s, is not a valid file descriptor.

       The socket is being shutdown due to a request by software.  This
			   is usually caused by a system call.

       The		   addr parameter is not a valid pointer.

       The call was interrupted by a signal before a valid connection arrived.

       The socket referenced by
			   s is not currently a listen socket or has been shut down with A must be done before an is allowed.

       The maximum number of file descriptors for this process
			   are currently open.

       The system's table of open files is full and no more
			   calls can be processed at this time.

       No buffer space is available.
			   The cannot complete.  The queued socket connect request is aborted.

       No memory is available.
			   The cannot complete.  The queued socket connect request is aborted.

       The argument,	   s, is a valid file descriptor, but it is not a socket.

       The socket referenced by
			   s does not support

       Nonblocking I/O is enabled using
			   or and no connections are present to be accepted.

OBSOLESCENCE

       Currently, the and types are the same size.  This is compatible with the UNIX 95 and UNIX 03 profiles.  However, in a future release, might
       be  a  different size.  In that case, passing a pointer will evoke compile-time warnings, which must be corrected in order for the applica-
       tion to behave correctly.  Applications that use now, where appropriate, will avoid such migration problems.  On the other  hand,  applica-
       tions that need to be portable to the UNIX 95 profile should follow the X/Open specification (see xopen_networking(7)).

WARNINGS

       Linking	binary	objects  compiled to specification and binary objects compiled to specification to the same executable may result in unex-
       pected behavior, including application abnormal termination and unexpected socket errors.  See xopen_networking(7) for details and remedy.

FUTURE DIRECTION

       Currently, the default behavior is the however, it might be changed to in a future release.  At that time, any behavior that is	incompati-
       ble  with  might be obsoleted.  Applications that conform to the X/Open specification now will avoid migration problems (see xopen_network-
       ing(7)).

AUTHOR

       was developed by HP and the University of California, Berkeley.

SEE ALSO

       bind(2), connect(2), listen(2), select(2), socket(2), privileges(5), thread_safety(5), xopen_networking(7).

STANDARDS CONFORMANCE

																	 accept(2)