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API over DNS

This library provide a simple API to send request using DNS protocol (the TXT query record)

It does not implement the DNS protocol, it uses the dns.

Installation

The library

Assuming that the Haskell compiler GHC and the Haskell build tool cabal is already installed run the following command from the shell:

cabal install

Build the example

In the examples directory:

  • Client:

    • "echo" query: ask to return what I send to him
    • "db" query: ask to access something in a database (try the keys "linux" or "haskell")

  • Server:

    • respond to "echo" or "db" queries
    • return ServerError in case of bad queries or non-TXT request

    cabal configure -f executable

Test the example:

./dist/build/Server/Server --bind example/bind.conf


./dist/build/Client/Client localtest.me. db haskell

The API

Request

Encodable

The DNS-API provides an interface to send query. A query MUST implements the Class Encodable.

An encodable data MUST implement two methods:

  • encode: converts the data into a valid FQDN
  • decode: converts a FQDN into the needed data

The default Encodable type

You can implement your own type of Request. Network.DNS.API.Types already implements a Request Encodable:

data Request p = Request
    { domain :: ByteString
    , cmd    :: p
    , nonce  :: ByteString
    }

Where p is an instance of Packable (see below).

In the case of the Request p the encoded command will look like:

<encoded32(command and nonce)>.domain

Packable

For those who want to use the default Request type, there is only one thing to do: Implements the commands.

Response

data Response = Response
    { signature :: ByteString
    , response  :: ByteString
    }

Every response to a valide request will be return in this structure.

The query methods

Let to user wishes.