httpserver.erl

%%
%% Tiny webserver always answer Hello World
%% listen on port speficied when starting it
%%
%% start :
%%   httpserver:start(port)
%%
-module(httpserver).
-export([start/1]).

start(Port) ->
    spawn(fun () -> {ok, Sock} = gen_tcp:listen(Port, [{active, false}]),
                    loop(Sock) end).

loop(Sock) ->
    {ok, Conn} = gen_tcp:accept(Sock),
    Handler = spawn(fun () -> handle(Conn) end),
    gen_tcp:controlling_process(Conn, Handler),
    loop(Sock).

handle(Conn) ->
    gen_tcp:send(Conn, response("Hello World")),
    gen_tcp:close(Conn).

response(Str) ->
    B = iolist_to_binary(Str),
    iolist_to_binary(
      io_lib:fwrite("HTTP/1.0 200 OK\nContent-Type: text/html\nContent-Length: ~p\n\n~s",
                    [size(B), B])).