listen() -- Sockets Function (libsocket)

Listen for a connection on a socket
#include <sys/socket.h>
int listen(socket, backlog)
int socket, int backlog;

Function listen()  ``listens'' for a connection on  socket. It also signals
the  system  your process's  willingness  to accept  a  connection on  that
socket.   This function  applies  only to  sockets of  type SOCK_STREAM  or
SOCK_SEQPACKET.

socket is  a file  descriptor that identifies  the socket in  question.  It
must have been returned by a  call to socket(). backlog defines the maximum
length to  which the  queue of  pending connections may  grow.  As  of this
writing, backlog is limited to a  maximum of five.  If a connection request
arrives  with the  queue full,  the  client may  receive an  error with  an
indication  of  ECONNREFUSED;   or  if  the  underlying  protocol  supports
retransmission, the request may be ignored so that retries may succeed.

If all goes well, listen() returns zero.  If an error occurs, it returns -1
and sets  errno to  an appropriate value.   The following lists  the errors
that can occur, by the value to which listen() sets errno:

EBADF
     socket is not a valid descriptor.

ENOTSOCK
     socket does not identify a socket.

EOPNOTSUPP
     socket is not of a type that supports listen().

Example

For an example of this function, see the Lexicon entry for libsocket.

See Also

accept(),
connect(),
libsocket,
socket()

© 2012 by Stephen A. Ness