nng_tls(7)
==========
:doctype: manpage
:manmanual: nng
:mansource: nng
:icons: font
:source-highlighter: pygments
:copyright: Copyright 2018 Staysail Systems, Inc. <info@staysail.tech> \
            Copyright 2018 Capitar IT Group BV <info@capitar.com> \
            This software 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_tls - TLS transport for nng

SYNOPSIS
--------

[source,c]
----------
#include <nng/transport/tls/tls.h>

int nng_tls_register(void);
----------

DESCRIPTION
-----------

The _nng_tls_ transport provides communication support between
_nng_ sockets across a TCP/IP network using 
https://tools.ietf.org/html/rfc5246[TLS v1.2] on top of
https://tools.ietf.org/html/rfc793[TCP].  Both IPv4 and IPv6
are supported when the underlying platform also supports it.

The protocol details are documented in
http://nanomsg.org/rfcs/sp-tls-v1.html[TLS Mapping for Scalability Protocols].

Registration
~~~~~~~~~~~~

Depending upon how the library was built, it may be necessary to
register the transport by calling `nng_tls_register`.  This function
returns zero on success, or an nng error value if the transport
cannot be initialized for any reason.

Availability
~~~~~~~~~~~~

The _tls_ transport depends on the use of an external library.
As of this writing, https://tls.mbed.org/[mbed TLS] version 2.0
or later is required.

TIP: Applications may need to add this library (or libraries) to
their link line, particularly when using a statically built
_nng_ library.

NOTE: The mbed TLS library uses different licensing terms than
_nng_ itself; as of this writing it is offered under either
https://opensource.org/licenses/Apache-2.0[Apache License 2.0] or
https://opensource.org/licenses/gpl-license[GNU GPL] terms.
You are responsible for understanding and adhering to the
license terms of any libraries you make use of.

URI Format
~~~~~~~~~~

This transport uses URIs using the scheme `tls+tcp://`, followed by
an IP address or hostname, followed by a colon and finally a
TCP port number.  For example, to contact port 4433 on the localhost
either of the following URIs could be used: `tls+tcp://127.0.0.1:4433` or
`tls+tcp://localhost:4433`.

When specifying IPv6 addresses, the address must be enclosed in
square brackets (`[]`) to avoid confusion with the final colon
separating the port.

For example, the same port 4433 on the IPv6 loopback address ('::1') would
be specified as `tls+tcp://[::1]:4433`.

NOTE: When using symbolic names, the name is resolved when the
name is first used. _nng_ won't become aware of changes in the
name resolution until restart,
usually.footnote:[This is a bug and will likely be fixed in the future.]

TIP: Certificate validation generally works when using names
rather than IP addresses. This transport automatically
uses the name supplied in the URL when validating the
certificate supplied by the server.

The special value of 0 (`INADDR_ANY`) 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 (`*`) character.  For example, the following three
URIs are all equivalent, and could be used to listen to port 9999
on the host:

  1. `tls+tcp://0.0.0.0:9999`
  2. `tls+tcp://*:9999`
  3. `tls+tcp://:9999`

The entire URI must be less than `NNG_MAXADDRLEN` bytes long.

Socket Address
~~~~~~~~~~~~~~

When using an `nng_sockaddr` structure, the actual structure is either
of type `nng_sockaddr_in` (for IPv4) or `nng_sockaddr_in6` (for IPv6).
These are `struct` types with the following definitions:

[source,c]
--------
#define NNG_AF_INET    3 <1>
#define NNG_AF_INET6   4
#define NNG_MAXADDRLEN 128

typedef struct {
    // ... <2>
    uint16_t sa_family;                 // must be NNG_AF_INET
    uint16_t sa_port;                   // TCP port number
    uint32_t sa_addr;
    // ...
} nng_sockaddr_in;

typedef struct {
    // ... <2>
    uint16_t sa_family;                 // must be NNG_AF_INET6
    uint16_t sa_port;                   // TCP port number
    uint8_t  sa_addr[16];
    // ...
} nng_sockaddr_in6;
--------
<1> The values of these macros may change, so applications
should avoid depending upon their values and instead use them symbolically.
<2> Other members may be present, but only those listed here
are suitable for application use.

The `sa_family` member will have the value `NNG_AF_INET` or `NNG_AF_INET6`.
The `sa_port` and `sa_addr` are the TCP port number and address, both in
network byte order (most significant byte is first).

X.509 Formats
~~~~~~~~~~~~~

The _tls_ transport supports certificates and key material provided
in either PEM or DER encoding.  When using PEM format data, the
encoding must be at the start of the data, with no intervening
content.  Furthermore, PEM encoded objects may have a terminating
NUL byte, which will be ignored if present.

Transport Options
~~~~~~~~~~~~~~~~~

The following transport options are available. Note that
setting these must be done before the transport is started.

`NNG_OPT_TLS_CONFIG`::

This option is used to set or obtain the TLS configuration
object (type `nng_tls_config *`), which is passed as a pointer.
Setting this option adds a reference to the object; obtaining the
object pointer does not.  (Therefore when retrieving this option,
care must be taken not to access it after the endpoint is closed.)

Note that configuration object is not modifiable once it has been
used in a running TLS stream.

`NNG_OPT_TLS_AUTH_VERIFIED`::

This is a read-only boolean option available only for
pipes, indicating whether the peer certificate was
valdiated or not.  This is only set when the pipe
has completed the handshake with the peer (which always
occurs before exchanging data), and will only be set
if the `NNG_OPT_TLS_AUTH_MODE` option is set to
`nng_tls_auth_mode_optional` or `nng_tls_auth_mode_required`.

SEE ALSO
--------
<<nng#,nng(7)>>,
<<nng_tls_config_alloc#,nng_tls_config_alloc(3)>>

COPYRIGHT
---------

Copyright 2018 mailto:info@staysail.tech[Staysail Systems, Inc.] +
Copyright 2018 mailto:info@capitar.com[Capitar IT Group BV]

This document is supplied under the terms of the
https://opensource.org/licenses/MIT[MIT License].
