%%
%% %CopyrightBegin%
%% 
%% Copyright Ericsson AB 1999-2009. All Rights Reserved.
%% 
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%% 
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% %CopyrightEnd%
%%

%% Purpose: Provide cryptographic algorithms.

-module(crypto_server).

-behaviour(gen_server).

-export([start_link/0,client_port/0]).

%% Internal exports, call-back functions.
-export([init/1,handle_call/3,handle_cast/2,handle_info/2,code_change/3,
	 terminate/2]).

%% Measurements shows that inlining port_names/0 is worth doing.
-compile({inline,[{port_names,0}]}).

%%% --------------------------------------------------------
%%% Interface Functions. 
%%% --------------------------------------------------------

start_link() ->
    gen_server:start_link({local, crypto_server}, crypto_server, [], []).

init([]) ->
    process_flag(trap_exit, true),
    erl_ddll:start(),
    PrivDir = code:priv_dir(crypto),
    LibDir1 = filename:join([PrivDir, "lib"]),
    {Status, LibDir} =
	case erl_ddll:load_driver(LibDir1, crypto_drv) of
	    ok -> {ok,LibDir1};
	    {error,Error1} ->
		LibDir2 = 
		    filename:join(LibDir1, 
				  erlang:system_info(system_architecture)),
		Candidate =
		    filelib:wildcard(filename:join([LibDir2,"crypto_drv*"])),
		case Candidate of
		    [] ->
			{{error,Error1},LibDir1};
		    _ ->
			case erl_ddll:load_driver(LibDir2, crypto_drv) of
			    ok ->
				{ok,LibDir2};
			    {error, Error2} ->
				{{error,Error2},LibDir2}
			end
		end
	end,
    case Status of
	ok ->
	    Cmd = "crypto_drv elibcrypto " ++ 
		filename:join([LibDir, "elibcrypto"]),
	    open_ports(Cmd,size(port_names()));
	{error, E} ->
	    Str = erl_ddll:format_error(E),
	    error_logger:error_msg("Unable to load crypto_drv. Failed with error:~n\"~s\"~nOpenSSL might not be installed on this system.~n",[Str]),
	    {stop,nodriver}
    end.

open_ports(_,0) ->
    {ok, []};
open_ports(Cmd,N) ->   
    Port = open_port({spawn, Cmd}, []),
    %% check that driver is loaded, linked and working
    %% since crypto_drv links towards libcrypto, this is a good thing
    %% since libcrypto is known to be bad with backwards compatibility
    case catch port_control(Port, 0, []) of
	{'EXIT', _} ->
	    {stop, nodriver};
	_ ->
	    register(element(N,port_names()), Port),
	    open_ports(Cmd,N-1)
    end.

port_names() -> 
    { crypto_drv01, crypto_drv02, crypto_drv03, crypto_drv04,
      crypto_drv05, crypto_drv06, crypto_drv07, crypto_drv08,
      crypto_drv09, crypto_drv10, crypto_drv11, crypto_drv12,
      crypto_drv13, crypto_drv14, crypto_drv15, crypto_drv16 }.

client_port() ->
    element(erlang:system_info(scheduler_id) rem size(port_names()) + 1,
	    port_names()).


%%% --------------------------------------------------------
%%% The call-back functions.
%%% --------------------------------------------------------

handle_call(_, _, State) ->
    {noreply, State}.

handle_cast(_, State) ->
    {noreply, State}.

handle_info({'EXIT', Pid, _Reason}, State) when is_pid(Pid) ->
    {noreply, State};

handle_info({'EXIT', Port, Reason}, State) when is_port(Port) ->
    {stop, {port_died, Reason}, State};
handle_info(_, State) ->
    {noreply, State}.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

terminate(_Reason, _State) ->
    close_ports(size(port_names())).

close_ports(0) ->
    ok;
close_ports(N) ->   
    element(N,port_names()) ! {self(), close},
    close_ports(N-1).