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---
version: tip
layout: manpage_v2
title: nng_recvmsg(3)
---
<h1>nng_recvmsg(3)</h1>
<div class="sect1">
<h2 id="_name">NAME</h2>
<div class="sectionbody">
<div class="paragraph">
<p>nng_recvmsg - receive a message</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="c"><span></span><span class="tok-cp">#include</span><span class="tok-w"> </span><span class="tok-cpf"><nng/nng.h></span>
<span class="tok-kt">int</span><span class="tok-w"> </span><span class="tok-nf">nng_recvmsg</span><span class="tok-p">(</span><span class="tok-n">nng_socket</span><span class="tok-w"> </span><span class="tok-n">s</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">nng_msg</span><span class="tok-w"> </span><span class="tok-o">**</span><span class="tok-n">msgp</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-kt">int</span><span class="tok-w"> </span><span class="tok-n">flags</span><span class="tok-p">);</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The <code>nng_recvmsg()</code> receives a message on socket <em>s</em>, storing the
received message at the location pointed to by <em>msgp</em>.</p>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
Using this function gives access to the message structure, and thus may
offer more functionality than the simpler <a href="nng_recv.3.html"><code>nng_recv()</code></a> function.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The <em>flags</em> may contain the following value:</p>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1"><code>NNG_FLAG_NONBLOCK</code></dt>
<dd>
<p>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 <em>s</em>, or any configured timer expires.</p>
</dd>
</dl>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
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 <a href="nng_req.7.html"><em>req</em></a> socket a message may only be received
after a request has been sent, and an <a href="nng_sub.7.html"><em>sub</em></a> 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
<a href="nng_pub.7.html"><em>pub</em></a>.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_return_values">RETURN VALUES</h2>
<div class="sectionbody">
<div class="paragraph">
<p>This function returns 0 on success, and non-zero otherwise.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_errors">ERRORS</h2>
<div class="sectionbody">
<div class="hdlist">
<table>
<tr>
<td class="hdlist1">
<code>NNG_EAGAIN</code>
</td>
<td class="hdlist2">
<p>The operation would block, but <code>NNG_FLAG_NONBLOCK</code> was specified.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ECLOSED</code>
</td>
<td class="hdlist2">
<p>The socket <em>s</em> is not open.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_EINVAL</code>
</td>
<td class="hdlist2">
<p>An invalid set of <em>flags</em> was specified.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ENOMEM</code>
</td>
<td class="hdlist2">
<p>Insufficient memory is available.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ENOTSUP</code>
</td>
<td class="hdlist2">
<p>The protocol for socket <em>s</em> does not support receiving.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ESTATE</code>
</td>
<td class="hdlist2">
<p>The socket <em>s</em> cannot receive data in this state.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ETIMEDOUT</code>
</td>
<td class="hdlist2">
<p>The operation timed out.</p>
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph text-left">
<p><a href="nng_msg_free.3.html">nng_msg_free(3)</a>,
<a href="nng_recv.3.html">nng_recv(3)</a>,
<a href="nng_sendmsg.3.html">nng_sendmsg(3)</a>,
<a href="nng_strerror.3.html">nng_strerror(3)</a>,
<a href="nng_socket.5.html">nng_socket(5)</a>,
<a href="nng.7.html">nng(7)</a></p>
</div>
</div>
</div>
|
