path: root/man/tip/nng_tcp.7.html

---
version: tip
layout: manpage_v2
title: nng_tcp(7)
---
<h1>nng_tcp(7)</h1>
<div class="sect1">
<h2 id="_name">NAME</h2>
<div class="sectionbody">
<div class="paragraph">
<p>nng_tcp - TCP/IP transport</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">&lt;nng/transport/tcp/tcp.h&gt;</span>

<span class="tok-kt">int</span><span class="tok-w"> </span><span class="tok-nf">nng_tcp_register</span><span class="tok-p">(</span><span class="tok-kt">void</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 <em>tcp</em> transport provides communication support between
sockets across a TCP/IP network.
Both IPv4 and IPv6 are supported when the underlying platform also supports it.</p>
</div>
<div class="sect2">
<h3 id="_registration">Registration</h3>
<div class="paragraph">
<p>This transport is generally built-in to the core of <em>NNG</em>, so
no extra steps to use it should be necessary.</p>
</div>
</div>
<div class="sect2">
<h3 id="_uri_format">URI Format</h3>
<div class="paragraph">
<p>
This transport uses URIs using the scheme <code>tcp://</code>, followed by
an IP address or hostname, followed by a colon and finally a
TCP port number.
For example, to contact port 80 on the localhost either of the following URIs
could be used: <code>tcp://127.0.0.1:80</code> or <code>tcp://localhost:80</code>.</p>
</div>
<div class="paragraph">
<p>A URI may be restricted to IPv6 using the scheme <code>tcp6://</code>, and may
be restricted to IPv4 using the scheme <code>tcp4://</code>.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Specifying <code>tcp6://</code> may not prevent IPv4 hosts from being used with
IPv4-in-IPv6 addresses, particularly when using a wildcard hostname with
listeners.
The details of this varies across operating systems.
</td>
</tr>
</table>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Both <code>tcp6://</code> and <code>tcp4://</code> are specific to <em>NNG</em>, and might not
be understood by other implementations.
</td>
</tr>
</table>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
We recommend using either numeric IP addresses, or names that are
specific to either IPv4 or IPv6 to prevent confusion and surprises.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>When specifying IPv6 addresses, the address must be enclosed in
square brackets (<code>[]</code>) to avoid confusion with the final colon
separating the port.</p>
</div>
<div class="paragraph">
<p>For example, the same port 80 on the IPv6 loopback address (<code>::1</code>) would
be specified as <code>tcp://[::1]:80</code>.</p>
</div>
<div class="paragraph">
<p>The special value of 0 (<code>INADDR_ANY</code>)
can be used for a listener to indicate that it should listen on all
interfaces on the host.
A short-hand for this form is to either omit the address, or specify
the asterisk (<code>*</code>) character.
For example, the following three URIs are all equivalent,
and could be used to listen to port 9999 on the host:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p><code>tcp://0.0.0.0:9999</code></p>
</li>
<li>
<p><code>tcp://*:9999</code></p>
</li>
<li>
<p><code>tcp://:9999</code></p>
</li>
</ol>
</div>
<div class="paragraph">
<p>The entire URI must be less than <code>NNG_MAXADDRLEN</code> bytes long.</p>
</div>
</div>
<div class="sect2">
<h3 id="_socket_address">Socket Address</h3>
<div class="paragraph">
<p>When using an <a href="nng_sockaddr.5.html"><code>nng_sockaddr</code></a> structure,
the actual structure is either of type
<a href="nng_sockaddr_in.5.html"><code>nng_sockaddr_in</code></a> (for IPv4) or
<a href="nng_sockaddr_in6.5.html"><code>nng_sockaddr_in6</code></a> (for IPv6).</p>
</div>
</div>
<div class="sect2">
<h3 id="_transport_options">Transport Options</h3>
<div class="paragraph">
<p>The following transport options are supported by this transport,
where supported by the underlying platform.</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="nng_options.5.html#NNG_OPT_LOCADDR"><code>NNG_OPT_LOCADDR</code></a></p>
</li>
<li>
<p><a href="nng_options.5.html#NNG_OPT_REMADDR"><code>NNG_OPT_REMADDR</code></a></p>
</li>
<li>
<p><a href="nng_tcp_options.5.html#NNG_OPT_TCP_KEEPALIVE"><code>NNG_OPT_TCP_KEEPALIVE</code></a></p>
</li>
<li>
<p><a href="nng_tcp_options.5.html#NNG_OPT_TCP_NODELAY"><code>NNG_OPT_TCP_NODELAY</code></a></p>
</li>
<li>
<p><a href="nng_options.5.html#NNG_OPT_URL"><code>NNG_OPT_URL</code></a></p>
</li>
</ul>
</div>
</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_options.5.html">nng_options(5)</a>,
<a href="nng_sockaddr.5.html">nng_sockaddr(5)</a>,
<a href="nng_sockaddr_in.5.html">nng_sockaddr_in(5)</a>,
<a href="nng_sockaddr_in6.5.html">nng_sockaddr_in6(5)</a>,
<a href="nng_tcp_options.5.html">nng_tcp_options(5)</a>,
<a href="nng.7.html">nng(7)</a></p>
</div>
</div>
</div>