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

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version: tip
layout: manpage_v2
title: nng_ws(7)
---
<h1>nng_ws(7)</h1>
<div class="sect1">
<h2 id="_name">NAME</h2>
<div class="sectionbody">
<div class="paragraph">
<p>nng_ws - WebSocket 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/websocket/ws.h&gt;</span>

<span class="tok-kt">int</span><span class="tok-w"> </span><span class="tok-nf">nng_ws_register</span><span class="tok-p">(</span><span class="tok-kt">void</span><span class="tok-p">);</span>
<span class="tok-kt">int</span><span class="tok-w"> </span><span class="tok-nf">nng_wss_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>ws</em> transport provides communication support between
peers across a TCP/IP network using
<a href="https://tools.ietf.org/html/rfc6455">WebSockets</a>.
Both IPv4 and IPv6 are supported when the underlying platform also supports it.</p>
</div>
<div class="paragraph">
<p>The protocol details are documented in
<a href="http://nanomsg.org/rfcs/sp-websocket-v1.html">WebSocket Mapping for Scalability Protocols</a>.</p>
</div>
<div class="sect2">
<h3 id="_registration">Registration</h3>
<div class="paragraph">
<p>Depending upon how the library was built, it may be necessary to
register the transport by calling <a href="nng_ws_register.3.html"><code>nng_ws_register()</code></a>.</p>
</div>
<div class="paragraph">
<p>If TLS support is enabled in the library, secure WebSockets (over TLS v1.2)
can be used as well, but the secure transport may have to be registered using
the <a href="nng_wss_register.3.html"><code>nng_wss_register()</code></a> function.</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>ws://</code>, followed by
an IP address or hostname, optionally followed by a colon and an
TCP port number, optionally followed by a path.
(If no port number is specified then port 80 is assumed.
If no path is specified then a path of <code>/</code> is assumed.)
For example, the URI <code>ws://localhost/app/pubsub</code> would use
port 80 on localhost, with the path <code>/app/pubsub</code>.</p>
</div>
<div class="paragraph">
<p>Secure WebSockets 
(if enabled) use the scheme <code>wss://</code>, and the default TCP port number of 443.
Otherwise the format is the same as for regular WebSockets.</p>
</div>
<div class="paragraph">
<p>A URI may be restricted to IPv6 using the scheme <code>ws6://</code> or <code>wss6://</code>, and may
be restricted to IPv4 using the scheme <code>ws4://</code> or <code>wss4://</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>ws6://</code>  or <code>wss6://</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">
The <code>ws4://</code> , <code>ws6://</code>, <code>wss4://</code> and <code>wss6://</code> schemes 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 path and port on the IPv6 loopback address (<code>::1</code>)
would be specified as <code>ws://[::1]/app/pubsub</code>.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
The value specified as the host, if any, will also be used
in the <code>Host:</code> HTTP header during HTTP negotiation.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>To listen to all ports on the system, the host name may be elided from
the URL on the listener.  This will wind up listening to all interfaces
on the system, with possible caveats for IPv4 and IPv6 depending on what
the underlying system supports.  (On most modern systems it will map to the
special IPv6 address <code>::</code>, and both IPv4 and IPv6 connections will be
permitted, with IPv4 addresses mapped to IPv6 addresses.)</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="_server_instances">Server Instances</h3>
<div class="paragraph">
<p>This transport makes use of shared HTTP server 
instances, permitting multiple
sockets or listeners to be configured with the same hostname and port.
When creating a new listener, it is registered with an existing HTTP server
instance if one can be found.
Note that the matching algorithm is somewhat simple,
using only a string based hostname or IP address and port to match.
Therefore it is recommended to use only IP addresses or the empty string as
the hostname in listener URLs.</p>
</div>
<div class="paragraph">
<p>Likewise, when sharing a server instance, it may not be possible to alter
TLS configuration if the server is already running, as there is only a single
TLS configuration context for the entire server instance.</p>
</div>
<div class="paragraph">
<p>All sharing of server instances is only typically possible within the same
process.</p>
</div>
<div class="paragraph">
<p>The server may also be used by other things (for example to serve static
content), in the same process.</p>
</div>
</div>
<div class="sect2">
<h3 id="_transport_options">Transport Options</h3>
<div class="paragraph">
<p>The following transport options are available. Note that
setting these must be done before the transport is started.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
The TLS specific options (beginning with <code>NNG_OPT_TLS_</code>) are
only available for <code>wss://</code> endpoints.
</td>
</tr>
</table>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1"><code>NNG_OPT_WS_REQUEST_HEADERS</code></dt>
<dd>
<p>(string) Concatenation of multiple lines terminated
by CRLF sequences, that can be used to add further headers to the
HTTP request sent when connecting.
This option can be set on dialers, and retrieved from pipes.</p>
</dd>
<dt class="hdlist1"><code>NNG_OPT_WS_RESPONSE_HEADERS</code></dt>
<dd>
<p>(string) Concatenation of multiple lines terminated
by CRLF sequences, that can be used to add further headers to the
HTTP response sent when connecting.
This option can be set on listeners, and retrieved from pipes.</p>
</dd>
<dt class="hdlist1"><code>NNG_OPT_WS_RECV_TEXT</code></dt>
<dd>
<p>(bool) Enable receiving of TEXT frames at the WebSocket layer.
This option should only be used with the low level
<a href="nng_stream.5.html"><code>nng_stream</code></a> API.
When set, the stream will accept in-bound TEXT frames as well as BINARY frames.</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 SP protocols (such as <a href="nng_req.7.html">REQ</a>) require BINARY frames as they pass binary protocol data.
Hence this option should not be used with such protocols.
</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">
RFC 6455 requires that TEXT frames be discarded and the connection closed if the frame does not contain valid UTF-8 data.
NNG does not perform any such validation.
Applications that need to be strictly conformant should check for this themselves.
</td>
</tr>
</table>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1"><code>NNG_OPT_WS_SEND_TEXT</code></dt>
<dd>
<p>(bool) Enable sending of TEXT frames at the WebSocket layer.
This option should only be used with the low level
<a href="nng_stream.5.html"><code>nng_stream</code></a> API.
When set, the stream will send TEXT frames instead of BINARY frames.</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">
NNG does not check the frame data, and will attempt to send whatever the client requests.
Peers that are compliant with RFC 6455 will discard TEXT frames (and break the connection) if they do not contain valid UTF-8.
</td>
</tr>
</table>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1"><code>NNG_OPT_TLS_CONFIG</code></dt>
<dd>
<p>(<code>nng_tls_config *</code>) The underlying TLS
configuration object for <code>wss://</code> endpoints.
A hold is placed on the underlying
configuration object before returning it.
The caller should release the object with
<a href="nng_tls_config_free.3tls.html"><code>nng_tls_config_free()</code></a> when it no
longer needs the TLS configuration.</p>
</dd>
</dl>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
Use this option when advanced TLS configuration is required.
</td>
</tr>
</table>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1"><code>NNG_OPT_TLS_CA_FILE</code></dt>
<dd>
<p>(string) Write-only option naming a file containing certificates to
use for peer validation.
See <a href="nng_tls_config_ca_file.3tls.html"><code>nng_tls_config_ca_file()</code></a> for more
information.</p>
</dd>
<dt class="hdlist1"><code>NNG_OPT_TLS_CERT_KEY_FILE</code></dt>
<dd>
<p>(string) Write-only option naming a file containing the local certificate and
associated private key.
The private key used must be unencrypted.
See <a href="nng_tls_config_own_cert.3tls.html"><code>nng_tls_config_own_cert()</code></a> for more
information.</p>
</dd>
<dt class="hdlist1"><code>NNG_OPT_TLS_AUTH_MODE</code></dt>
<dd>
<p>(<code>int</code>) Write-only option used to configure the authentication mode used.
See <a href="nng_tls_config_auth_mode.3tls.html"><code>nng_tls_config_auth_mode()</code></a> for
more details.</p>
</dd>
<dt class="hdlist1"><code>NNG_OPT_TLS_VERIFIED</code></dt>
<dd>
<p>(<code>bool</code>) Whether the remote peer has been properly verified using TLS
authentication.
May return incorrect results if peer authentication is disabled.</p>
</dd>
<dt class="hdlist1"><code>NNG_OPT_TLS_PEER_CN</code></dt>
<dd>
<p>(string) This read-only option returns the common name of the peer certificate.
May return incorrect results if peer authentication is disabled.</p>
</dd>
<dt class="hdlist1"><code>NNG_OPT_TLS_PEER_ALT_NAMES</code></dt>
<dd>
<p>(string list) returns string list with the subject alternative names of the
peer certificate. May return incorrect results if peer authentication
is disabled.</p>
</dd>
</dl>
</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_tls_config_alloc.3tls.html">nng_tls_config_alloc(3tls)</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.7.html">nng(7)</a></p>
</div>
</div>
</div>