Improve API to be more Erlang-ish

.gitignore

@@ -2,3 +2,6 @@
 **/*.rs.bk
 Cargo.lock
 **/*~
+/parity-ethereum
+/_build
+/ebin

Cargo.toml

@@ -9,7 +9,7 @@ edition = "2018"
 [dependencies]
 base64 = "0.10.1"
 c_vec = "1.3.3"
-ethcore-builtin = { path = "../parity-ethereum/ethcore/builtin" }
+ethcore-builtin = { path = "parity-ethereum/ethcore/builtin" }
 lazy_static = "1.3.0"
 libc = "0.2.60"
 parity-bytes = "0.1.0"

Makefile

@@ -1,8 +1,11 @@
 all: priv/ecrecover.so
 
-priv/ecrecover.so: src/lib.rs
+priv/ecrecover.so: src/lib.rs parity-ethereum/
 	cargo build --release
 	cp target/release/libecrecover.so priv/ecrecover.so
 
 clean:
 	rm -f src/ecrecover.so target/release/libecrecover.so
+
+parity-ethereum/:
+	git clone https://github.com/johnsnewby/parity-ethereum.git

rebar.config

@@ -1,10 +1,4 @@
-
-{erl_opts, [{parse_transform, lager_transform}, {lager_extra_sinks, [ecrecover]}]}.
-
 {deps, [
-        {lager, {git, "https://github.com/erlang-lager/lager.git",
-                 {ref, "69b4ada"}}}, % tag: 3.6.7
-
         %% ecrecover prebuilt libraries
         {ecrecoverprebuilt,
          {ecrecoverprebuilt_app_with_priv_from_git,
@@ -17,8 +11,6 @@
              {ref, "f982da061c5f2e0ffbf1ad58ac25b3b32e182b01"}}}
           ]}.
 
-%%{profiles, [{test, [{deps, [{meck, "0.8.12"}]}]}]}.
-
 {dialyzer, [{warnings, [unknown]},
             {plt_apps, all_deps},
             {base_plt_apps, [erts, kernel, stdlib, crypto]}

rebar.lock

@@ -0,0 +1,5 @@
+[{<<"ecrecoverprebuilt">>,
+  {ecrecoverprebuilt_app_with_priv_from_git,
+      {git,"https://github.com/aeternity/ecrecover-prebuilt.git",
+          {ref,"93569ca272e59682366cdf3c7ed2ee991540701a"}}},
+  0}].

src/ecrecover.erl

@@ -1,44 +1,41 @@
 -module(ecrecover).
 
 %% API
--export([ecrecover/1,
-	 ecrecover_hex/1,
-	 bin_to_hexstr/1,
-	 hexstr_to_bin/1,
-	 time_taken_to_execute/1
-]).
+-export([recover/2]).
 
-%% Native library support
+%% NIF
 -export([load/0]).
 -on_load(load/0).
 
-ecrecover(_Input) ->
-    not_loaded(?LINE).
-
-ecrecover_hex(Input) ->
-    Decoded = hexstr_to_bin(Input),
-    {ok, PubKey} = ecrecover(Decoded),
-    Encoded = bin_to_hexstr(PubKey),
-    Encoded.
-
+%%=============================================================================
+%% NIF API
 
 load() ->
-    Dir = case code:priv_dir(ecrecoverprebuilt) of
-              {error, bad_name} ->
-                  filename:join(
-                    filename:dirname(
-                      filename:dirname(
-                        code:which(?MODULE))), "priv");
-              D -> D
-          end,
-    SoName = filename:join(Dir, atom_to_list(?MODULE)),
+    SoName = filename:join(priv(), atom_to_list(?MODULE)),
     ok = erlang:load_nif(SoName, 0).
 
 not_loaded(Line) ->
     erlang:nif_error({error, {not_loaded, [{module, ?MODULE}, {line, Line}]}}).
 
+%%=============================================================================
+%% External API
+
+recover(<<_:32/binary>> = Hash, <<_:65/binary>> = Sig) ->
+    Input = <<Hash/binary, 0:(8*31), Sig/binary>>,
+    case recover_(Input) of
+        {ok, []} ->
+            <<0:256>>;
+        {ok, Res} ->
+            erlang:list_to_binary(Res);
+        _Err ->
+            <<0:256>>
+    end.
+
+%%=============================================================================
+%% Internal Functions
+
 priv()->
-  case code:priv_dir(?MODULE) of
+  case code:priv_dir(ecrecoverprebuilt) of
       {error, _} ->
           EbinDir = filename:dirname(code:which(?MODULE)),
           AppPath = filename:dirname(EbinDir),
@@ -47,23 +44,5 @@ priv()->
           Path
   end.
 
-%%
-time_taken_to_execute(F) -> Start = os:timestamp(),
-  F(),
-  io:format("total time taken ~f seconds~n", [timer:now_diff(os:timestamp(), Start) / 1000000]).
-
-%%
-bin_to_hexstr(Bin) ->
-  lists:flatten([io_lib:format("~2.16.0B", [X]) ||
-    X <- binary_to_list(Bin)]).
-
-hexstr_to_bin(S) ->
-  hexstr_to_bin(S, []).
-hexstr_to_bin([], Acc) ->
-  list_to_binary(lists:reverse(Acc));
-hexstr_to_bin([X,Y|T], Acc) ->
-  {ok, [V], []} = io_lib:fread("~16u", [X,Y]),
-  hexstr_to_bin(T, [V | Acc]);
-hexstr_to_bin([X|T], Acc) ->
-  {ok, [V], []} = io_lib:fread("~16u", lists:flatten([X,"0"])),
-  hexstr_to_bin(T, [V | Acc]).
+recover_(_Input) ->
+    not_loaded(?LINE).

src/ecrecover_util.erl

@@ -0,0 +1,28 @@
+-module(ecrecover_util).
+
+-export([ recover_from_hex/1
+        , bin_to_hex/1
+        , hex_to_bin/1
+        ]).
+
+%%=============================================================================
+%% External API
+
+recover_from_hex(Input) ->
+    <<Hash:32/binary, _:31/binary, Sig:65/binary>> = hex_to_bin(Input),
+    PubKey = ecrecover:recover(Hash, Sig),
+    bin_to_hex(PubKey).
+
+bin_to_hex(Bin) ->
+    lists:flatten([io_lib:format("~2.16.0B", [X]) || X <- binary_to_list(Bin)]).
+
+hex_to_bin(S) ->
+    hex_to_bin(S, []).
+hex_to_bin([], Acc) ->
+    list_to_binary(lists:reverse(Acc));
+hex_to_bin([X,Y|T], Acc) ->
+    {ok, [V], []} = io_lib:fread("~16u", [X,Y]),
+    hex_to_bin(T, [V | Acc]);
+hex_to_bin([X|T], Acc) ->
+    {ok, [V], []} = io_lib:fread("~16u", lists:flatten([X,"0"])),
+    hex_to_bin(T, [V | Acc]).

src/lib.rs

@@ -37,9 +37,9 @@ pub fn nif_ecrecover<'a>(env: Env<'a>, args: &[Term<'a>]) -> Result<Term<'a>, Er
     let mut byte_ref = Vec::new();
     let ecrecover = EcRecover { };
     let _result = match ecrecover.execute(input.as_slice(),
-                                          &mut BytesRef::Flexible(&mut byte_ref)) {
+                                          &mut BytesRef::Fixed(&mut byte_ref)) {
         Ok(_) => (),
-        Err(_e) => return Err(rustler::Error::Atom("ecrecover failed")),
+        Err(_e) => return Err(rustler::Error::Atom("ecrecover_failed")),
     };
     Ok((atoms::ok(), byte_ref.as_slice()).encode(env))
 }