lib/etorrent-1.0/src/etorrent_listener.erl

   1 %%%-------------------------------------------------------------------
   2 %%% File    : listener.erl
   3 %%% Author  : Jesper Louis Andersen <jesper.louis.andersen@gmail.com>
   4 %%% License : See COPYING
   5 %%% Description : Listen for incoming connections
   6 %%%
   7 %%% Created : 30 Jul 2007 by Jesper Louis Andersen <jesper.louis.andersen@gmail.com>
   8 %%%-------------------------------------------------------------------
   9 -module(etorrent_listener).
  10
  11 -behaviour(gen_server).
  12
  13 %% API
  14 -export([start_link/0, get_socket/0]).
  15
  16 %% gen_server callbacks
  17 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
  18          terminate/2, code_change/3]).
  19
  20 -record(state, { listen_socket = none}).
  21
  22 -define(SERVER, ?MODULE).
  23 -define(DEFAULT_SOCKET_INCREASE, 10).
  24
  25
  26 %%====================================================================
  27 %% API
  28 %%====================================================================
  29 %%--------------------------------------------------------------------
  30 %% Function: start_link() -> {ok,Pid} | ignore | {error,Error}
  31 %% Description: Starts the server
  32 %%--------------------------------------------------------------------
  33 start_link() ->
  34     gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
  35
  36 %%--------------------------------------------------------------------
  37 %% Function: get_socket() -> listen_socket()
  38 %% Description: Return the listen socket we are bound to.
  39 %%--------------------------------------------------------------------
  40 get_socket() ->
  41     gen_server:call(?SERVER, get_socket).
  42
  43 %%====================================================================
  44 %% gen_server callbacks
  45 %%====================================================================
  46
  47 %%--------------------------------------------------------------------
  48 %% Function: init(Args) -> {ok, State} |
  49 %%                         {ok, State, Timeout} |
  50 %%                         ignore               |
  51 %%                         {stop, Reason}
  52 %% Description: Initiates the server
  53 %%--------------------------------------------------------------------
  54 init([]) ->
  55     {ok, Port} = application:get_env(etorrent, port),
  56     {ok, ListenSocket} = find_listen_socket(Port, ?DEFAULT_SOCKET_INCREASE),
  57     {ok, #state{ listen_socket = ListenSocket}}.
  58
  59 %%--------------------------------------------------------------------
  60 %% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |
  61 %%                                      {reply, Reply, State, Timeout} |
  62 %%                                      {noreply, State} |
  63 %%                                      {noreply, State, Timeout} |
  64 %%                                      {stop, Reason, Reply, State} |
  65 %%                                      {stop, Reason, State}
  66 %% Description: Handling call messages
  67 %%--------------------------------------------------------------------
  68 handle_call(get_socket, _From, S) ->
  69     {reply, {ok, S#state.listen_socket}, S};
  70 handle_call(_Request, _From, State) ->
  71     Reply = ok,
  72     {reply, Reply, State}.
  73
  74 %%--------------------------------------------------------------------
  75 %% Function: handle_cast(Msg, State) -> {noreply, State} |
  76 %%                                      {noreply, State, Timeout} |
  77 %%                                      {stop, Reason, State}
  78 %% Description: Handling cast messages
  79 %%--------------------------------------------------------------------
  80 handle_cast(_Msg, State) ->
  81     {noreply, State}.
  82
  83 %%--------------------------------------------------------------------
  84 %% Function: handle_info(Info, State) -> {noreply, State} |
  85 %%                                       {noreply, State, Timeout} |
  86 %%                                       {stop, Reason, State}
  87 %% Description: Handling all non call/cast messages
  88 %%--------------------------------------------------------------------
  89 handle_info(_Info, State) ->
  90     {noreply, State}.
  91
  92 %%--------------------------------------------------------------------
  93 %% Function: terminate(Reason, State) -> void()
  94 %% Description: This function is called by a gen_server when it is about to
  95 %% terminate. It should be the opposite of Module:init/1 and do any necessary
  96 %% cleaning up. When it returns, the gen_server terminates with Reason.
  97 %% The return value is ignored.
  98 %%--------------------------------------------------------------------
  99 terminate(_Reason, State) ->
 100     % Explicitly close the socket if we terminate.
 101     error_logger:info_report([listener_closing_socket]),
 102     gen_tcp:close(State#state.listen_socket),
 103     ok.
 104
 105 %%--------------------------------------------------------------------
 106 %% Func: code_change(OldVsn, State, Extra) -> {ok, NewState}
 107 %% Description: Convert process state when code is changed
 108 %%--------------------------------------------------------------------
 109 code_change(_OldVsn, State, _Extra) ->
 110     {ok, State}.
 111
 112 %%--------------------------------------------------------------------
 113 %%% Internal functions
 114 %%--------------------------------------------------------------------
 115 find_listen_socket(_Port, 0) ->
 116     {error, could_not_find_free_socket};
 117 find_listen_socket(Port, N) ->
 118     case gen_tcp:listen(Port, [binary, inet, {active, false}]) of
 119         {ok, Socket} ->
 120             {ok, Socket};
 121         {error, eaddrinuse} ->
 122             find_listen_socket(Port+1, N-1)
 123     end.
 124