From 6fcb19616b09b59f8fab68b30c08606f9260a5b3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= <essen@ninenines.eu>
Date: Mon, 2 Jan 2017 16:28:03 +0100
Subject: Implement HTTP/2 server push

---
 src/gun.erl       |  4 ++--
 src/gun_http2.erl | 37 ++++++++++++++++++++++++++++++++++---
 src/gun_spdy.erl  |  6 +++---
 3 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/src/gun.erl b/src/gun.erl
index 82f658d..eeaaa1e 100644
--- a/src/gun.erl
+++ b/src/gun.erl
@@ -309,8 +309,8 @@ await(ServerPid, StreamRef, Timeout, MRef) ->
 			{response, IsFin, Status, Headers};
 		{gun_data, ServerPid, StreamRef, IsFin, Data} ->
 			{data, IsFin, Data};
-		{gun_push, ServerPid, StreamRef, NewStreamRef, Method, Host, Path, Headers} ->
-			{push, NewStreamRef, Method, Host, Path, Headers};
+		{gun_push, ServerPid, StreamRef, NewStreamRef, Method, URI, Headers} ->
+			{push, NewStreamRef, Method, URI, Headers};
 		{gun_error, ServerPid, StreamRef, Reason} ->
 			{error, Reason};
 		{gun_error, ServerPid, Reason} ->
diff --git a/src/gun_http2.erl b/src/gun_http2.erl
index 1f852e2..e58db74 100644
--- a/src/gun_http2.erl
+++ b/src/gun_http2.erl
@@ -154,9 +154,40 @@ frame(settings_ack, State) -> %% @todo =#http2_state{next_settings=_NextSettings
 	State;
 %% PUSH_PROMISE frame.
 %% @todo Continuation.
-%frame({push_promise, StreamID, head_fin, PromisedStreamID, HeaderBlock}, State) ->
-%	%% @todo
-%	State;
+frame({push_promise, StreamID, head_fin, PromisedStreamID, HeaderBlock},
+		State=#http2_state{owner=Owner, decode_state=DecodeState0}) ->
+	case get_stream_by_id(PromisedStreamID, State) of
+		false ->
+			case get_stream_by_id(StreamID, State) of
+				#stream{ref=StreamRef} ->
+					try cow_hpack:decode(HeaderBlock, DecodeState0) of
+						{Headers0, DecodeState} ->
+							{Method, Scheme, Authority, Path, Headers} = try
+								{value, {_, Method0}, Headers1} = lists:keytake(<<":method">>, 1, Headers0),
+								{value, {_, Scheme0}, Headers2} = lists:keytake(<<":scheme">>, 1, Headers1),
+								{value, {_, Authority0}, Headers3} = lists:keytake(<<":authority">>, 1, Headers2),
+								{value, {_, Path0}, Headers4} = lists:keytake(<<":path">>, 1, Headers3),
+								{Method0, Scheme0, Authority0, Path0, Headers4}
+							catch error:badmatch ->
+								stream_reset(State, StreamID, {stream_error, protocol_error,
+									'Malformed push promise; missing pseudo-header field. (RFC7540 8.1.2.3)'})
+							end,
+							NewStreamRef = make_ref(),
+							Owner ! {gun_push, self(), StreamRef, NewStreamRef, Method,
+								iolist_to_binary([Scheme, <<"://">>, Authority, Path]), Headers},
+							new_stream(PromisedStreamID, NewStreamRef, nofin, fin,
+								State#http2_state{decode_state=DecodeState})
+					catch _:_ ->
+						terminate(State, {connection_error, compression_error,
+							'Error while trying to decode HPACK-encoded header block. (RFC7540 4.3)'})
+					end;
+				_ ->
+					stream_reset(State, StreamID, {stream_error, stream_closed,
+						'DATA frame received for a closed or non-existent stream. (RFC7540 6.1)'})
+			end;
+		_ ->
+			stream_reset(State, StreamID, {stream_error, todo, ''})
+	end;
 %% PING frame.
 frame({ping, Opaque}, State=#http2_state{socket=Socket, transport=Transport}) ->
 	Transport:send(Socket, cow_http2:ping_ack(Opaque)),
diff --git a/src/gun_spdy.erl b/src/gun_spdy.erl
index ef5d0cb..dcd7496 100644
--- a/src/gun_spdy.erl
+++ b/src/gun_spdy.erl
@@ -97,15 +97,15 @@ handle_frame(Rest, State=#spdy_state{owner=Owner,
 handle_frame(Rest, State=#spdy_state{owner=Owner,
 		socket=Socket, transport=Transport},
 		{syn_stream, StreamID, AssocToStreamID, IsFin, IsUnidirectional,
-		_, Method, _, Host, Path, Version, Headers})
+		_, Method, Scheme, Host, Path, Version, Headers})
 		when AssocToStreamID =/= 0, IsUnidirectional ->
 	case get_stream_by_id(StreamID, State) of
 		false ->
 			case get_stream_by_id(AssocToStreamID, State) of
 				#stream{ref=AssocToStreamRef} ->
 					StreamRef = make_ref(),
-					Owner ! {gun_push, self(), AssocToStreamRef,
-						StreamRef, Method, Host, Path, Headers},
+					Owner ! {gun_push, self(), AssocToStreamRef, StreamRef, Method,
+						iolist_to_binary([Scheme, <<"://">>, Host, Path]), Headers},
 					handle_loop(Rest, new_stream(StreamID, StreamRef,
 						not IsFin, false, Version, State));
 				false ->
-- 
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