An Elixir library designed to write SIP protocol middleware.

Introduction

Sippet is not intended to be a fully functional SIP UAC/UAS, proxy server, B2BUA, SBC or application; instead, it has only the very basic to build any kind of SIP middleware.

One of the most central parts of Sippet is the Sippet.Message. Instead of many headers that you end up having to parse by yourself, there's an internal parser written in C++ (an Erlang NIF) that does all the hard work for you. This way, the Sippet.Message.headers is a simple Map where the key is the header name, and the value varies accordingly the header type. For instance, the header :cseq has the form {sequence :: integer, method} where the methodis an atom with the method name (like :invite), and :via is a list of tuples {version, protocol, sent_by, parameters}, where version is of the form {major, minor}, protocol is an atom representing the Via header protocol (such as :udp), sent_by is a tuple {host :: binary, port} and parameters is always a Map of the form %{name => value} where name and value are String.t.

Other than the Sippet.Message, you will find the Sippet.Transport and the Sippet.Transaction modules, which implement the two standard SIP layers.

As Sippet is a simple SIP library, the developer has to understand the protocol very well before writing a middleware. This design decision came up because all attempts to hide any inherent SIP complexity by other frameworks have failed.

There is no support for plugins or hooks, all just have to be done from a Sippet.Core module implementation. Also there is no support for fancy protocols; a simple Sippet.Transport.UDP (but still performatic) implementation is provided, which is enough for several SIP middleware apps.

Installation

If available in Hex, the package can be installed as:

1. Add sippet to your list of dependencies in mix.exs:

```elixir
def deps do
  [{:sippet, "~> 0.1.0"}]
end
```

1. Ensure sippet is started before your application:

```elixir
def application do
  [applications: [:sippet, :logger, :gen_state_machine, :socket, poolboy]]
end
```