DNS Service Discovery Haskell Bindings

dnssd provides Haskell bindings to Multicast DNS (mDNS) and DNS Service Discovery (DNS-SD). Also known as Bonjour or Avahi.

WARNING: There is currently a bug that causes the C code to get stuck in a loop when used in a large network in GHCi. This is an experimental library.

Install

cabal install dnssd

On Linux you need the libavahi-compat-libdnssd-dev package installed as well.

Example

slide-simple.hs is a simple example of displaying jpegs to an Apple TV.

To find all local web servers.

import Network.DNSSD
main = do
  servers <- dnsBrowse "_http._tcp"
  putStrLn . show $ servers

This should look something like this:

[
  SRecord {deviceName = "Maxwell\8217s Server",
           serviceName = "_http._tcp.", deviceDomain = "local."}
, SRecord {deviceName = "Jenkins",
           serviceName = "_http._tcp.", deviceDomain = "local."}
]

Find just one and then resolve it's IP and port.

import Network.DNSSD

dnsAny :: String -> IO (Maybe SResolved)
dnsAny s = do
  things <- dnsBrowse s
  if null things
    then return Nothing
    else dnsResolve $ head things

main = do
  web <- dnsAny "_http._tcp"
  print web

Cross Platform Status

Works on:

• Mac
• Linux

Doesn't work on yet:

• Windows