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= nng_recvmsg(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_recvmsg - recv message
== SYNOPSIS
[source, c]
-----------
#include <nng/nng.h>
int nng_recvmsg(nng_socket s, nng_msg **msgp, int flags);
-----------
== DESCRIPTION
The `nng_recvmsg()` receives a message on socket _s_, storing the
received message at the location pointed to by _msgp_.
TIP: Using this function gives access to the message structure, and thus may
offer more functionality than the simpler <<nng_recv#,nng_recv(3)>> function.
The _flags_ may contain the following value:
`NNG_FLAG_NONBLOCK`::
The function returns immediately, even if no message is available. Without
this flag, the function will wait until a message is received by the socket
_s_, or any configured timer expires.
NOTE: The semantics of what receiving a message means vary from protocol to
protocol, so examination of the protocol documentation is encouraged. (For
example, with an <<nng_req#,nng_req(7)>> socket a message may only be received
after a request has been sent, and an <<nng_sub#,nng_sub(7)>> socket
may only receive messages corresponding to topics to which it has subscribed.)
Furthermore, some protocols may not support receiving data at all, such as
<<nng_pub#,nng_pub(7)>>.
== RETURN VALUES
This function returns 0 on success, and non-zero otherwise.
== ERRORS
`NNG_EAGAIN`:: The socket _s_ cannot accept data for sending.
`NNG_ECLOSED`:: The socket _s_ is not open.
`NNG_EINVAL`:: An invalid set of _flags_ was specified.
`NNG_ENOMEM`:: Insufficient memory is available.
`NNG_ENOTSUP`:: The protocol for socket _s_ does not support receiving.
`NNG_ESTATE`:: The socket _s_ cannot receive data in this state.
== SEE ALSO
<<nng_msg_free#,nng_msg_free(3)>>,
<<nng_recv#,nng_recv(3)>>,
<<nng_sendmsg#,nng_sendmsg(3)>>,
<<nng_strerror#,nng_strerror(3)>>,
<<nng#,nng(7)>>
|
