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NAME

       accept - accept a connection on a socket

SYNOPSIS

       #include <network.h>

       int accept(int s, struct sockaddr *addr, int *addrlen);

DESCRIPTION

       The  argument  s  is  a  socket that has been created with

       socket(2), bound to an address with bind(2), and  is  lis-

       tening  for  connections  after  a  listen(2).  The accept

       function extracts the  first  connection  request  on  the

       queue  of  pending  connections, creates a new socket with

       the same  properties  of  s,  and  allocates  a  new  file

       descriptor  for the socket.  If no pending connections are

       present on the queue, and the socket is not marked as non-

       blocking,  accept  blocks the caller until a connection is

       present.  If the socket  is  marked  non-blocking  and  no

       pending  connections  are  present  on  the  queue, accept

       returns an error as described below.  The socket  returned

       by accept may not be used to accept more connections.  The

       original socket s remains open.

       The argument addr is a result parameter that is filled  in

       with the address of the connecting entity, as known to the

       communications layer.  The exact format of the addr param-

       eter  is  determined by the domain in which the communica-

       tion is occurring.  addrlen is a  value-result  parameter:

       it should initially contain the amount of space pointed to

       by addr; on return it will contain the actual  length  (in

       bytes)  of  the  address returned.  This call is used with

       connection-based socket types, currently with SOCK_STREAM.

       It  is  possible to select(2) a socket for the purposes of

       doing an accept by selecting it for read.

       For certain protocols which require an explicit  confirma-

       tion,  such  as DECNet, accept can be thought of as merely

       dequeuing the next connection  request  and  not  implying

       confirmation.   Confirmation  can  be  implied by a normal

       read or write on the new file  descriptor,  and  rejection

       can  be  implied by closing the new socket. Currently only

       DECNet has these semantics on Linux.

NOTES

       If you want accept to never  block  the  listening  socket

       needs  to  have  the  non blocking flag set. Assuming that

       there is always a connection waiting after select returned

       true  is  not  reliable,  because  the connection might be

       removed by  an  asynchronous  network  error  between  the

       select/poll returning and the accept call. The application

       would hang then if the listen socket is not non  blocking.

RETURN VALUES

       The  call returns -1 on error.  If it succeeds, it returns

       a non-negative  integer  that  is  a  descriptor  for  the

       accepted socket.

ERRORS

       EBADF   The descriptor is invalid.

       ENOTSOCK

               The descriptor references a file, not a socket.

       EOPNOTSUPP

               The referenced socket is not of type  SOCK_STREAM.

       EAGAIN  The socket is marked non-blocking and  no  connec-

               tions are present to be accepted.

       ENOBUFS, ENOMEM

               Not enough free memory.