# DNS
![](https://img.shields.io/hexpm/v/dns.svg)
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. Add dns to your list of dependencies in `mix.exs`:
```elixir
def deps do
[{:dns, "~> 0.0.3"}]
end
```
2. Ensure dns is started before your application:
```elixir
def application do
[applications: [:dns]]
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", {"8.8.8.8", 53})
...
```
### DNS server
```elixir
defmodule TestServer do
use Application
@behaviour DNS.Server
def start(_args, _opts) do
import Supervisor.Spec, warn: false
port = Application.get_env(:dns, :server)[:port]
children = [
worker(Task, [DNS.Server, :accept, [port, __MODULE__]])
]
opts = [strategy: :one_for_one, name: DNS.Server.Supervisor]
Supervisor.start_link(children, opts)
end
def handle(record, {ip, _}) do
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
```
For more information, see [API Reference](http://hexdocs.pm/dns/0.0.3/api-reference.html)
## License
BSD-3-Clauses