= nng_socket(7)
//
// Copyright 2023 Staysail Systems, Inc. <info@staysail.tech>
//
// 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_socket - BSD Socket transport (experimental)

== DESCRIPTION

(((BSD Socket)))(((transport, _socket_)))
The ((_socket_ transport)) provides communication support between
peers across a arbitrary BSD sockets, such as those that are
created with xref:nng_socket_pair.3supp.adoc[`nng_socket_pair()`].

This transport only supports xref:nng_listener.5.adoc[listeners], using xref:nng_listener_create.3.adoc[`nng_listener_create()`].

NOTE: Attempts to create a xref:nng_dialer.5.adoc[dialer] using this transport will result in `NNG_ENOTSUP`.

The socket file descriptor is passed to the listener using the `NNG_OPT_SOCKET_FD` option (as an integer).
Setting this option (which is read-only and can be set multiple times) will cause the listener
to create a xref:nng_pipe.5.adoc[pipe] associated backed by the file descriptor.

The protocol between peers using this pipe is at present compatible with the protocol used for the
xref:nng_tcp.7.adoc[TCP] transport, but this is an implementation detail and subject to change without notice.

NOTE: This transport is *experimental*, and at present is only supported on POSIX platforms.

=== Registration

No special action is necessary to register this transport.

=== URI Format

(((URI, `socket://`)))
This transport uses the URL `socket://`, without further qualification.

=== Socket Address

The socket address will be of family `NNG_AF_UNSPEC`.
There are no further socket details available.

=== Transport Options

The following transport option is available:

((`NNG_OPT_SOCKET_FD`))::

(int) This is a write-only option, that may be set multiple times on a listener.
The listener will create a pipe backed by the given file descriptor passed as an argument.

Additionally, the following options may be supported on pipes when the platform supports them:

* xref:nng_options.5.adoc#NNG_OPT_PEER_GID[`NNG_OPT_PEER_GID`]
* xref:nng_options.5.adoc#NNG_OPT_PEER_PID[`NNG_OPT_PEER_PID`]
* xref:nng_options.5.adoc#NNG_OPT_PEER_UID[`NNG_OPT_PEER_UID`]
* xref:nng_options.5.adoc#NNG_OPT_PEER_ZONEID[`NNG_OPT_PEER_ZONEID`]

== SEE ALSO

[.text-left]
xref:nng_socket_pair.3supp.adoc[nng_socket_pair(3)],
xref:nng_dialer.5.adoc[nng_dialer(5)],
xref:nng_listener.5.adoc[nng_listener(5)],
xref:nng_options.5.adoc[nng_options(5)],
xref:nng_pipe.5.adoc[nng_pipe(5)],
xref:nng_sockaddr.5.adoc[nng_sockaddr(5)],
xref:nng.7.adoc[nng(7)]
