Add middleware support

Middlewares allow customizing the request processing.

All existing Cowboy project are incompatible with this commit.
You need to change `{dispatch, Dispatch}` in the protocol options
to `{env, [{dispatch, Dispatch}]}` to fix your code.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/cowboy_middleware.erl b/src/cowboy_middleware.erl
new file mode 100644
index 0000000..0c1ca77
--- /dev/null
+++ b/src/cowboy_middleware.erl
@@ -0,0 +1,36 @@
+%% Copyright (c) 2013, Loïc Hoguin <[email protected]>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+%% @doc Behaviour for middlewares.
+%%
+%% Only one function needs to be implemented, <em>execute/2</em>.
+%% It receives the Req and the environment and returns them
+%% optionally modified. It can decide to stop the processing with
+%% or without an error. It is also possible to hibernate the process
+%% if needed.
+%%
+%% A middleware can perform any operation. Make sure you always return
+%% the last modified Req so that Cowboy has the up to date information
+%% about the request.
+-module(cowboy_middleware).
+
+-type env() :: [{atom(), any()}].
+-export_type([env/0]).
+
+-callback execute(Req, Env)
+	-> {ok, Req, Env}
+	| {suspend, module(), atom(), any()}
+	| {halt, Req}
+	| {error, cowboy_http:status(), Req}
+	when Req::cowboy_req:req(), Env::env().