No longer necessary to use cowboy fork.

The master branch of cowboy now has all the support for HTTP2 that
is required for gRPC.

Makefile

@@ -6,7 +6,8 @@ PROJECT_VERSION = 0.1.0
 SP = 4
 
 DEPS = cowboy grpc_lib
-dep_cowboy = git https://github.com/willemdj/cowboy
+# Use the cowboy version that has support for trailers.
+dep_cowboy_commit = master
 dep_grpc_lib = git https://github.com/Bluehouse-Technology/grpc_lib
 
 TEST_DEPS = grpc_client

README.md

@@ -115,9 +115,7 @@ tested against the go gRPC implementation.
 
 ## Dependencies
 
-- [cowboy](https://github.com/willemdj/cowboy) is used for the server.
-  This is a fork with some additional HTTP/2, most notably support for
-  trailers.
+- [cowboy](https://github.com/ninenines/cowboy) is used for the server.
 
 - [gpb](https://github.com/tomas-abrahamsson/gpb) is used to encode and
   decode the protobuf messages. This is a 'build' dependency: gpb is

src/grpc_server.erl

@@ -147,11 +147,11 @@ get_authfun(_, _) ->
     undefined.
 
 authenticate(Req, #{auth_fun := AuthFun}) when is_function(AuthFun) ->
-    case cowboy_req:peercert(Req) of
-        {ok, Cert} ->
-            AuthFun(Cert);
-        {error, no_peercert} ->
-            false
+    case cowboy_req:cert(Req) of
+        undefined ->
+            false;
+        Cert when is_binary(Cert) ->
+            AuthFun(Cert)
     end;
 authenticate(_Req, _Options) ->
     {true, undefined}.

src/grpc_stream_handler.erl

@@ -72,7 +72,8 @@ data(StreamID, IsFin, Data, State0=#state{bytes_received = Received,
     -> {cowboy_stream:commands(), State} when State::#state{}.
 info(StreamID, Info, State0=#state{next=Next0}) ->
     {Commands0, Next} = cowboy_stream:info(StreamID, Info, Next0),
-    {Commands0, State0#state{next=Next}}.
+    Commands = remove_date_and_server(Commands0),
+    {Commands, State0#state{next=Next}}.
 
 -spec terminate(cowboy_stream:streamid(), cowboy_stream:reason(), #state{}) -> any().
 terminate(StreamID, Reason, #state{next=Next}) ->
@@ -83,3 +84,17 @@ terminate(StreamID, Reason, #state{next=Next}) ->
     when Resp::cowboy_stream:resp_command().
 early_error(StreamID, Reason, PartialReq, Resp, Opts) ->
     cowboy_stream:early_error(StreamID, Reason, PartialReq, Resp, Opts).
+
+
+%%-----------------------------------------------------------------------------
+%% Internal functions
+%%-----------------------------------------------------------------------------
+
+%% cowboy adds headers for "date" and "server", these must be removed.
+remove_date_and_server(Commands) ->
+    F = fun({headers, Status, Headers}) ->
+                {headers, Status, maps:without([<<"date">>, <<"server">>], Headers)};
+           (Other) ->
+                Other
+        end,
+    [F(C) || C <- Commands].