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= nng_pipe_notify(3)
//
// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
// Copyright 2018 Capitar IT Group BV <info@capitar.com>
//
// This document is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
== NAME
nng_pipe_notify - register pipe notification callback
== SYNOPSIS
[source, c]
----
#include <nng/nng.h>
typedef enum {
NNG_PIPE_ADD,
NNG_PIPE_REM,
} nng_pipe_action;
typedef void (*nng_pipe_cb)(nng_pipe, nng_pipe_action, void *);
int nng_pipe_notify(nng_socket s, nng_pipe_cb cb, void *arg);
----
== DESCRIPTION
The `nng_pipe_notify()` function registers the callback function _cb_
to be called whenever a <<nng_pipe.5#,pipe>> is added to or removed from the
socket _s_.
The function _cb_ will be called with the action `NNG_PIPE_ADD` just before
a pipe is added to the socket (as a result of a connection being established).
The final argument passed will be the argument _arg_ that was specified when
the function was registered.
The function _cb_ will also be called with the action `NNG_PIPE_REM` when
the pipe is being removed from the socket for any reason.
This will also use the same argument _arg_.
NOTE: Only one callback can be registered for a given socket.
Subsequent calls to `nng_pipe_notify()` on the same socket will overwrite
any prior registration.
TIP: The callback _cb_ may reject a pipe for any reason by simply closing
it using `<<nng_pipe_close.3#,nng_pipe_close()>>`.
This might be done, for example, if the remote peer is not authorized to
access this session, based on values determined with the aid of
`<<nng_pipe_getopt.3#,nng_pipe_getopt()>>`.
== RETURN VALUES
This function returns 0 on success, and non-zero otherwise.
== ERRORS
`NNG_ECLOSED`:: The socket _s_ does not refer to an open socket.
== SEE ALSO
<<nng_pipe_close.3#,nng_pipe_close(3)>>,
<<nng_pipe_getopt.3#,nng_pipe_getopt(3)>>,
<<nng_pipe.5#,nng_pipe(5)>>,
<<nng_socket.5#,nng_socket(5)>>,
<<nng.7#,nng(7)>>
|
