Here is the beginnings of a Bonjour / ZeroConf module in Erlang. I always like to ZeroConf all my servers I write so I don’t have to play the xml/properties/ini file game with how a server or clients connect to each other. All my previous Python and Java servers have used bindings to a C library to work their magic, I want to create a native Erlang module since I am trying to ween myself off Python/Twisted and onto Erlang for good. And I want to do it in a way that doesn’t require ports or linked-in libraries, I want a native Erlang solution.
zeroconf.erl
-include("zeroconf.hrl").
-export([open/0,start/0]).
-export([stop/1,receiver/0]).
-export([send/1]).
-define(ADDR, {224,0,0,251}).
-define(PORT, 5353).
open() ->
{ok,S} = gen_udp:open(?PORT,[{reuseaddr,true}, {ip,?ADDR}, {multicast_ttl,4}, {multicast_loop,false}, binary]),
inet:setopts(S,[{add_membership,{?ADDR,{0,0,0,0}}}]),
S.
close(S) -> gen_udp:close(S).
start() ->
S=open(),
Pid=spawn(?MODULE,receiver,[]),
gen_udp:controlling_process(S,Pid),
{S,Pid}.
stop({S,Pid}) ->
close(S),
Pid ! stop.
receiver() ->
receive
{udp, _Socket, IP, InPortNo, Packet} ->
io:format("~n~nFrom: ~p~nPort: ~p~nData: ~p~n",[IP,InPortNo,inet_dns:decode(Packet)]),
receiver();
stop -> true;
AnythingElse -> io:format("RECEIVED: ~p~n",[AnythingElse]),
receiver()
end.
zeroconf.hrl ( these were taken directly from inet_dns.hrl )
{
id = 0, %% ushort query identification number
%% byte F0
qr = 0, %% :1 response flag
opcode = 0, %% :4 purpose of message
aa = 0, %% :1 authoritive answer
tc = 0, %% :1 truncated message
rd = 0, %% :1 recursion desired
%% byte F1
ra = 0, %% :1 recursion available
pr = 0, %% :1 primary server required (non standard)
%% :2 unused bits
rcode = 0 %% :4 response code
}).
-record(dns_rec,
{
header, %% dns_header record
qdlist = [], %% list of question entries
anlist = [], %% list of answer entries
nslist = [], %% list of authority entries
arlist = [] %% list of resource entries
}).
-record(dns_query,
{
domain, %% query domain
type, %% query type
class %% query class
}).
in one console window do a
you should start seeing traffic spewing out onto the console to issue queries for iTunes for example in another console
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