Add {shutdown, Req} to websocket_init/3 to fail a websocket upgrade

This change allows application developers to refuse websocket upgrades
by returning {shutdown, Req}. The application can also send a reply
with a custom error before returning from websocket_init/3, otherwise
an error 400 is sent.

Note that right now Cowboy closes the connection immediately. Also note
that neither terminate/3 nor websocket_terminate/3 will be called when
the connection is shutdown by websocket_init/3.

1 files changed, 22 insertions, 2 deletions

diff --git a/test/http_SUITE.erl b/test/http_SUITE.erl
index 10d26b8..187d5af 100644
--- a/test/http_SUITE.erl
+++ b/test/http_SUITE.erl
@@ -20,7 +20,7 @@
 	init_per_group/2, end_per_group/2]). %% ct.
 -export([chunked_response/1, headers_dupe/1, headers_huge/1,
 	keepalive_nl/1, nc_rand/1, pipeline/1, raw/1,
-	ws0/1, ws8/1, ws8_single_bytes/1,
+	ws0/1, ws8/1, ws8_single_bytes/1, ws8_init_shutdown/1,
 	ws_timeout_hibernate/1]). %% http.
 -export([http_200/1, http_404/1]). %% http and https.
 -export([http_10_hostless/1]). %% misc.
@@ -34,7 +34,7 @@ groups() ->
 	BaseTests = [http_200, http_404],
 	[{http, [], [chunked_response, headers_dupe, headers_huge,
 		keepalive_nl, nc_rand, pipeline, raw,
-		ws0, ws8, ws8_single_bytes,
+		ws0, ws8, ws8_single_bytes, ws8_init_shutdown,
 		ws_timeout_hibernate] ++ BaseTests},
 	{https, [], BaseTests}, {misc, [], [http_10_hostless]}].
 
@@ -95,6 +95,7 @@ init_http_dispatch() ->
 			{[<<"chunked_response">>], chunked_handler, []},
 			{[<<"websocket">>], websocket_handler, []},
 			{[<<"ws_timeout_hibernate">>], ws_timeout_hibernate_handler, []},
+			{[<<"ws_init_shutdown">>], websocket_handler_init_shutdown, []},
 			{[<<"init_shutdown">>], http_handler_init_shutdown, []},
 			{[<<"headers">>, <<"dupe">>], http_handler,
 				[{headers, [{<<"Connection">>, <<"close">>}]}]},
@@ -394,6 +395,25 @@ ws_timeout_hibernate(Config) ->
 	{error, closed} = gen_tcp:recv(Socket, 0, 6000),
 	ok.
 
+ws8_init_shutdown(Config) ->
+	{port, Port} = lists:keyfind(port, 1, Config),
+	{ok, Socket} = gen_tcp:connect("localhost", Port,
+		[binary, {active, false}, {packet, raw}]),
+	ok = gen_tcp:send(Socket, [
+		"GET /ws_init_shutdown HTTP/1.1\r\n"
+		"Host: localhost\r\n"
+		"Connection: Upgrade\r\n"
+		"Upgrade: websocket\r\n"
+		"Sec-WebSocket-Origin: http://localhost\r\n"
+		"Sec-WebSocket-Version: 8\r\n"
+		"Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==\r\n"
+		"\r\n"]),
+	{ok, Handshake} = gen_tcp:recv(Socket, 0, 6000),
+	{ok, {http_response, {1, 1}, 403, "Forbidden"}, _Rest}
+		= erlang:decode_packet(http, Handshake, []),
+	{error, closed} = gen_tcp:recv(Socket, 0, 6000),
+	ok.
+
 websocket_headers({ok, http_eoh, Rest}, Acc) ->
 	[Acc, Rest];
 websocket_headers({ok, {http_header, _I, Key, _R, Value}, Rest}, Acc) ->