From bbfc1569ccffab060c4c2b402a45119fb1f57495 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= <essen@ninenines.eu>
Date: Wed, 4 Apr 2018 17:23:37 +0200
Subject: Add initial implementation of Websocket over HTTP/2

Using the current draft:

  https://tools.ietf.org/html/draft-ietf-httpbis-h2-websockets-01
---
 src/cowboy_stream_h.erl | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

(limited to 'src/cowboy_stream_h.erl')

diff --git a/src/cowboy_stream_h.erl b/src/cowboy_stream_h.erl
index 93b8417..620975c 100644
--- a/src/cowboy_stream_h.erl
+++ b/src/cowboy_stream_h.erl
@@ -33,7 +33,7 @@
 	expect = undefined :: undefined | continue,
 	read_body_ref = undefined :: reference() | undefined,
 	read_body_timer_ref = undefined :: reference() | undefined,
-	read_body_length = 0 :: non_neg_integer() | infinity,
+	read_body_length = 0 :: non_neg_integer() | infinity | auto,
 	read_body_is_fin = nofin :: nofin | {fin, non_neg_integer()},
 	read_body_buffer = <<>> :: binary(),
 	body_length = 0 :: non_neg_integer()
@@ -65,8 +65,9 @@ expect(Req) ->
 	end.
 
 %% If we receive data and stream is waiting for data:
-%%	If we accumulated enough data or IsFin=fin, send it.
-%%	If not, buffer it.
+%%   If we accumulated enough data or IsFin=fin, send it.
+%%   If we are in auto mode, send it and update flow control.
+%%   If not, buffer it.
 %% If not, buffer it.
 %%
 %% We always reset the expect field when we receive data,
@@ -75,6 +76,7 @@ expect(Req) ->
 
 -spec data(cowboy_stream:streamid(), cowboy_stream:fin(), cowboy_req:resp_body(), State)
 	-> {cowboy_stream:commands(), State} when State::#state{}.
+%% Stream isn't waiting for data.
 data(_StreamID, IsFin, Data, State=#state{
 		read_body_ref=undefined, read_body_buffer=Buffer, body_length=BodyLen}) ->
 	{[], State#state{
@@ -82,6 +84,16 @@ data(_StreamID, IsFin, Data, State=#state{
 		read_body_is_fin=IsFin,
 		read_body_buffer= << Buffer/binary, Data/binary >>,
 		body_length=BodyLen + byte_size(Data)}};
+%% Stream is waiting for data using auto mode.
+%%
+%% There is no buffering done in auto mode.
+data(_StreamID, IsFin, Data, State=#state{pid=Pid, read_body_ref=Ref,
+		read_body_length=auto, body_length=BodyLen}) ->
+	send_request_body(Pid, Ref, IsFin, BodyLen, Data),
+	{[{flow, byte_size(Data)}], State#state{
+		read_body_ref=undefined,
+		body_length=BodyLen}};
+%% Stream is waiting for data but we didn't receive enough to send yet.
 data(_StreamID, nofin, Data, State=#state{
 		read_body_length=ReadLen, read_body_buffer=Buffer, body_length=BodyLen})
 		when byte_size(Data) + byte_size(Buffer) < ReadLen ->
@@ -89,9 +101,11 @@ data(_StreamID, nofin, Data, State=#state{
 		expect=undefined,
 		read_body_buffer= << Buffer/binary, Data/binary >>,
 		body_length=BodyLen + byte_size(Data)}};
+%% Stream is waiting for data and we received enough to send.
 data(_StreamID, IsFin, Data, State=#state{pid=Pid, read_body_ref=Ref,
 		read_body_timer_ref=TRef, read_body_buffer=Buffer, body_length=BodyLen0}) ->
 	BodyLen = BodyLen0 + byte_size(Data),
+	%% @todo Handle the infinity case where no TRef was defined.
 	ok = erlang:cancel_timer(TRef, [{async, true}, {info, false}]),
 	send_request_body(Pid, Ref, IsFin, BodyLen, <<Buffer/binary, Data/binary>>),
 	{[], State#state{
@@ -121,6 +135,16 @@ info(StreamID, Exit = {'EXIT', Pid, {Reason, Stacktrace}}, State=#state{ref=Ref,
 		{error_response, 500, #{<<"content-length">> => <<"0">>}, <<>>},
 		{internal_error, Exit, 'Stream process crashed.'}
 	], State};
+%% Request body, auto mode, no body buffered.
+info(_StreamID, {read_body, Ref, auto, infinity}, State=#state{read_body_buffer= <<>>}) ->
+	{[], State#state{
+		read_body_ref=Ref,
+		read_body_length=auto}};
+%% Request body, auto mode, body buffered or complete.
+info(_StreamID, {read_body, Ref, auto, infinity}, State=#state{pid=Pid,
+		read_body_is_fin=IsFin, read_body_buffer=Buffer, body_length=BodyLen}) ->
+	send_request_body(Pid, Ref, IsFin, BodyLen, Buffer),
+	{[{flow, byte_size(Buffer)}], State#state{read_body_buffer= <<>>}};
 %% Request body, body buffered large enough or complete.
 %%
 %% We do not send a 100 continue response if the client
@@ -136,6 +160,7 @@ info(StreamID, {read_body, Ref, Length, Period}, State=#state{expect=Expect}) ->
 		continue -> [{inform, 100, #{}}, {flow, Length}];
 		undefined -> [{flow, Length}]
 	end,
+	%% @todo Handle the case where Period =:= infinity.
 	TRef = erlang:send_after(Period, self(), {{self(), StreamID}, {read_body_timeout, Ref}}),
 	{Commands, State#state{
 		read_body_ref=Ref,
-- 
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