# DNS
[![Hex.pm](https://img.shields.io/hexpm/v/dns.svg)](https://hex.pm/packages/dns)
[![Hex.pm](https://img.shields.io/hexpm/dt/dns.svg)](https://hex.pm/packages/dns)
[![Build Status](https://travis-ci.org/tungd/elixir-dns.svg?branch=master)](https://travis-ci.org/tungd/elixir-dns)
DNS library for Elixir. Currently, the package provides:
- Elixir structs to interface with `inet_dns` module.
- DNS.Server behavior
- DNS client
Note: the `inet_dns` module is considered internal to Erlang and subject to
change. If this happened this library will be updated to accommodate for that,
but for now `inet_dns` is simple and worked for me.
## Installation
The package is available in [Hex](https://hex.pm) and can be installed as:
1. Make sure you have the Erlang/OTP source files installed,
otherwise the compilation will fail with an `{:error, :enoent}`
message. On Ubuntu, this can be done using `apt-get install
erlang-src`.
2. Add dns to your list of dependencies in `mix.exs`:
```elixir
def deps do
[{:dns, "~> 2.1.2"}]
end
```
## Usage
### DNS client
```elixir
iex> DNS.resolve("google.com")
{:ok, [{216, 58, 221, 110}]}
iex> DNS.resolve("notfound.domain")
{:error, :not_found}
iex> DNS.query("google.com")
%DNS.Record{anlist: [%DNS.Resource{bm: [], class: :in, cnt: 0,
data: {216, 58, 221, 110}, domain: 'google.com', func: false, tm: :undefined,
ttl: 129, type: :a}], arlist: [],
header: %DNS.Header{aa: false, id: 0, opcode: :query, pr: false, qr: true,
ra: true, rcode: 0, rd: false, tc: false}, nslist: [],
qdlist: [%DNS.Query{class: :in, domain: 'google.com', type: :a}]}
iex> DNS.resolve("google.com", :a, {"8.8.8.8", 53})
...
```
### DNS server
```elixir
defmodule ServerExample do
@moduledoc """
Example implementing DNS.Server behaviour
"""
@behaviour DNS.Server
use DNS.Server
def handle(record, _cl) do
Logger.info(fn -> "#{inspect(record)}" end)
query = hd(record.qdlist)
result =
case query.type do
:a -> {127, 0, 0, 1}
:cname -> 'your.domain.com'
:txt -> ['your txt value']
_ -> nil
end
resource = %DNS.Resource{
domain: query.domain,
class: query.class,
type: query.type,
ttl: 0,
data: result
}
%{record | anlist: [resource]}
end
end
# To create a server
{:ok, server_pid} = ServerExample.start_link 8000
```
For more information, see [API Reference](https://hexdocs.pm/dns/2.1.2/api-reference.html)
## License
BSD-3-Clauses