From 874050cb72f70206df81eecb3ac5435ff99d639d Mon Sep 17 00:00:00 2001
From: Linus Nordberg <linus@nordu.net>
Date: Sat, 26 Apr 2014 08:44:21 +0200
Subject: Make plop a gen_server.

---
 src/plop.erl           | 104 +++++++++++++++++++++++++++----------------------
 src/test/plop_test.erl |  19 +++------
 2 files changed, 63 insertions(+), 60 deletions(-)

diff --git a/src/plop.erl b/src/plop.erl
index 13bad30..90a5249 100644
--- a/src/plop.erl
+++ b/src/plop.erl
@@ -7,46 +7,77 @@
 %%% to prove that your entry is indeed present in the log.
 
 -module('plop').
+-behaviour(gen_server).
+
+%% API.
+-export([start_link/0, start_link/2, stop/0]).
+-export([add/1, sth/0]).
+%% gen_server callbacks.
+-export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2, code_change/3]).
+
 -include("plop.hrl").
 -include_lib("public_key/include/public_key.hrl").
 -include_lib("eunit/include/eunit.hrl").
 
--export([start/2, loop/1]).
-
 -define(PLOPVERSION, 1).
-
 -record(plop, {pubkey :: public_key:rsa_public_key(),
                privkey :: public_key:rsa_private_key(),
                logid :: binary(),
                hashtree :: ht:head()}).
 
--spec start(string(), string()) -> pid().
-start(Keyfile, Passphrase) ->
+start_link() ->
+    start_link("test/rsakey.pem", "sikrit").
+start_link(Keyfile, Passphrase) ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [Keyfile, Passphrase], []).
+
+stop() ->
+    gen_server:call(?MODULE, stop).
+
+%%%%%%%%%%%%%%%%%%%%
+init([Keyfile, Passphrase]) ->
     {Private_key, Public_key} = read_keyfile(Keyfile, Passphrase),
     LogID = crypto:hash(sha256,
                         public_key:der_encode('RSAPublicKey', Public_key)),
-    Plop = #plop{pubkey = Public_key,
-                 privkey = Private_key,
-                 logid = LogID,
-                 hashtree = ht:create()},
-    Pid = spawn_link(plop, loop, [Plop]),
-    register(plop, Pid),
-    Pid.
-
-log(Format, Data) ->
-    io:format(Format, Data).
-
-loop(Plop) ->
-    receive
-        {From, quit} ->
-            From ! {ok, quit};
-        {From, Data} ->
-            handle_req(From, Plop, Data),
-            loop(Plop);
-        Unknown ->
-            log("DEBUG: Received malformed command: ~p~n", [Unknown]),
-            loop(Plop)
-    end.
+    {ok, #plop{pubkey = Public_key,
+               privkey = Private_key,
+               logid = LogID,
+               hashtree = ht:create()}}.
+
+handle_cast(_Request, State) ->
+    {noreply, State}.
+
+handle_info(_Info, State) ->
+    {noreply, State}.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+%%%%%%%%%%%%%%%%%%%%
+add(Data) when is_record(Data, plop_data) ->
+    gen_server:call(?MODULE, {add, Data}).
+
+sth() ->
+    gen_server:call(?MODULE, sth).
+%%%%%%%%%%%%%%%%%%%%
+
+handle_call(stop, _From, State) ->
+    {stop, normal, stopped, State};
+handle_call({add, Data = #plop_data{entry = Entry}},
+            _From,
+            Plop = #plop{privkey = Privkey,
+                         logid = LogID,
+                         hashtree = Tree}) ->
+    %% fixme: add Entry to db,
+    ht:append(Tree, serialise(Entry)),
+    SPT = spt(LogID, Privkey, Data),
+    {reply, SPT, Plop};
+handle_call(sth, _From, Plop = #plop{hashtree = Tree}) ->
+    {reply, sth(Tree), Plop}.
+
+%%%%%%%%%%%%%%%%%%%%
 
 -spec serialise(plop_entry() | plop_data()) -> iolist().
 serialise(#plop_entry{type = EntryType, entry = Entry}) ->
@@ -57,25 +88,6 @@ serialise(#plop_data{version = Version,
                      entry = Entry}) ->
     [<<Version:8, Sigtype:8, Timestamp:64>>, serialise(Entry)].
 
-handle_req(From,
-           #plop{privkey = Privkey,
-                 logid = LogID,
-                 hashtree = Tree},
-           Arg) ->
-    case Arg of
-        {add, PlopData = #plop_data{entry = Entry}}
-          when is_record(Entry, plop_entry) ->
-            %% fixme: add Entry to db,
-            ht:append(Tree, serialise(Entry)),
-            SPT = spt(LogID, Privkey, PlopData),
-            %% io:format("adding ~p to ~p -> H: ~p, SPT: ~p~n", [Entry, Tree, H, SPT]),
-            From ! {ok, SPT};
-        sth ->                                  % Signed tree head.
-            From ! {ok, sth(Tree)};
-        Unknown ->
-            From ! {error, Unknown}
-    end.
-
 %% @doc Signed Plop Timestamp according to RFC6962 3.2 and RFC5246 4.7.
 spt(LogID,
     PrivKey,
diff --git a/src/test/plop_test.erl b/src/test/plop_test.erl
index 6b612dd..83b5240 100644
--- a/src/test/plop_test.erl
+++ b/src/test/plop_test.erl
@@ -12,16 +12,12 @@ adding_test_() ->
       end}}.
      
 start() ->
-    plop:start("test/rsakey.pem", "sikrit").
+    plop:start_link("test/rsakey.pem", "sikrit").
 
-stop(Pid) ->
-    Pid ! {self(), quit},
-    [?_assert(receive
-                  {ok, quit} -> true
-              after 500 -> false
-              end)].
+stop(_Pid) ->
+    [?_assertEqual({ok, plop}, plop:stop())].
 
-test_add(Pid) ->
+test_add(_Pid) ->
     TestVector =
         <<1,247,141,118,3,148,171,128,29,143,106,97,200,179,204,166,242,98,70,185,
           231,78,193,39,12,245,82,254,230,136,69,69,0,0,0,0,0,0,0,18,103,71,39,45,
@@ -43,11 +39,6 @@ test_add(Pid) ->
     PlopData = #plop_data{signature_type = ?PLOP_SIGTYPE_TEST,
                           timestamp = 4711,
                           entry = Entry},
-    Pid ! {self(), {add, PlopData}},
-    Res = receive M -> M end,
-    %% {ok, Dev} = file:open("d", write),
-    %% io:format(Dev, "~p~n", [Res]),
-    %% file:close(Dev),
-    [?_assertEqual({ok, TestVector}, Res)].
+    [?_assertEqual(TestVector, plop:add(PlopData))].
 
 % Helpers.
-- 
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