%% Copyright (c) 2015, 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.
-module(cowboy_http2).
-export([init/6]).
-export([system_continue/3]).
-export([system_terminate/4]).
-export([system_code_change/4]).
-record(stream, {
id = undefined :: cowboy_stream:streamid(),
state = undefined :: any(),
%% Whether we finished sending data.
local = nofin :: cowboy_stream:fin(),
%% Whether we finished receiving data.
remote = nofin :: cowboy_stream:fin()
}).
-type stream() :: #stream{}.
%% @todo priority: if we receive a message for a stream, do a selective receive
%% to get all messages in the mailbox and prioritize them. (later)
-record(state, {
parent = undefined :: pid(),
ref :: ranch:ref(),
socket = undefined :: inet:socket(),
transport :: module(),
opts = #{} :: map(),
handler :: module(),
%% Settings are separate for each endpoint. In addition, settings
%% must be acknowledged before they can be expected to be applied.
%%
%% @todo Since the ack is required, we must timeout if we don't receive it.
%% @todo I haven't put as much thought as I should have on this,
%% the final settings handling will be very different.
local_settings = #{} :: map(),
next_settings = #{} :: undefined | map(), %% @todo perhaps set to undefined by default
remote_settings = #{} :: map(),
%% Stream identifiers.
server_streamid = 2 :: pos_integer(),
%% @todo last known good streamid
%% Currently active HTTP/2 streams. Streams may be initiated either
%% by the client or by the server through PUSH_PROMISE frames.
streams = [] :: [stream()],
%% Streams can spawn zero or more children which are then managed
%% by this module if operating as a supervisor.
children = [] :: [{pid(), cowboy_stream:streamid()}],
%% The client starts by sending a sequence of bytes as a preface,
%% followed by a potentially empty SETTINGS frame. Then the connection
%% is established and continues normally. An exception is when a HEADERS
%% frame is sent followed by CONTINUATION frames: no other frame can be
%% sent in between.
parse_state = preface :: preface | settings | normal
| {continuation, cowboy_stream:streamid(), cowboy_stream:fin(), binary()},
%% HPACK decoding and encoding state.
decode_state = cow_hpack:init() :: cow_hpack:state(),
encode_state = cow_hpack:init() :: cow_hpack:state()
}).
-spec init(pid(), ranch:ref(), inet:socket(), module(), cowboy:opts(), module()) -> ok.
init(Parent, Ref, Socket, Transport, Opts, Handler) ->
before_loop(#state{parent=Parent, ref=Ref, socket=Socket,
transport=Transport, opts=Opts, handler=Handler}, <<>>).
%% @todo Add the timeout for last time since we heard of connection.
before_loop(State, Buffer) ->
loop(State, Buffer).
loop(State=#state{parent=Parent, socket=Socket, transport=Transport,
handler=Handler, children=Children}, Buffer) ->
Transport:setopts(Socket, [{active, once}]),
{OK, Closed, Error} = Transport:messages(),
receive
%% Socket messages.
{OK, Socket, Data} ->
parse(State, << Buffer/binary, Data/binary >>);
{Closed, Socket} ->
terminate(State, {socket_error, closed, 'The socket has been closed.'});
{Error, Socket, Reason} ->
terminate(State, {socket_error, Reason, 'An error has occurred on the socket.'});
%% System messages.
{'EXIT', Parent, Reason} ->
exit(Reason);
{system, From, Request} ->
sys:handle_system_msg(Request, From, Parent, ?MODULE, [], {State, Buffer});
%% Messages pertaining to a stream.
{{Handler, StreamID}, Msg} ->
loop(info(State, StreamID, Msg), Buffer);
%% Exit signal from children.
Msg = {'EXIT', Pid, _} ->
loop(down(State, Pid, Msg), Buffer);
%% Calls from supervisor module.
{'$gen_call', {From, Tag}, which_children} ->
Workers = [{?MODULE, Pid, worker, [?MODULE]} || {Pid, _} <- Children],
From ! {Tag, Workers},
loop(State, Buffer);
{'$gen_call', {From, Tag}, count_children} ->
NbChildren = length(Children),
Counts = [{specs, 1}, {active, NbChildren},
{supervisors, 0}, {workers, NbChildren}],
From ! {Tag, Counts},
loop(State, Buffer);
{'$gen_call', {From, Tag}, _} ->
From ! {Tag, {error, ?MODULE}},
loop(State, Buffer);
Msg ->
error_logger:error_msg("Received stray message ~p.", [Msg]),
loop(State, Buffer)
%% @todo Configurable timeout.
after 60000 ->
terminate(State, {internal_error, timeout, 'No message or data received before timeout.'})
end.
parse(State=#state{socket=Socket, transport=Transport, next_settings=Settings, parse_state=preface}, Data) ->
case Data of
<< "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", Rest/bits >> ->
%% @todo To speed up connection we may be able to construct the frame when starting the listener.
%% We send next_settings and use defaults until we get a ack.
Transport:send(Socket, cow_http2:settings(Settings)),
parse(State#state{parse_state=settings}, Rest);
_ when byte_size(Data) >= 24 ->
Transport:close(Socket),
exit({shutdown, {connection_error, protocol_error,
'The connection preface was invalid. (RFC7540 3.5)'}});
_ ->
before_loop(State, Data)
end;
%% @todo Perhaps instead of just more we can have {more, Len} to avoid all the checks.
parse(State=#state{parse_state=ParseState}, Data) ->
case cow_http2:parse(Data) of
{ok, Frame, Rest} ->
case ParseState of
normal -> parse(frame(State, Frame), Rest);
settings -> parse(frame(State, Frame), Rest);
_ -> parse(continuation_frame(State, Frame), Rest)
end;
{stream_error, StreamID, Reason, Human, Rest} ->
parse(stream_reset(State, StreamID, {stream_error, Reason, Human}), Rest);
Error = {connection_error, _, _} ->
terminate(State, Error);
more ->
before_loop(State, Data)
end.
%% @todo When we get a 'fin' we need to check if the stream had a 'fin' sent back
%% and terminate the stream if this is the end of it.
%% DATA frame.
frame(State=#state{handler=Handler, streams=Streams0}, {data, StreamID, IsFin, Data}) ->
case lists:keyfind(StreamID, #stream.id, Streams0) of
Stream = #stream{state=StreamState0} -> %% @todo in=open
try Handler:data(StreamID, IsFin, Data, StreamState0) of
{Commands, StreamState} ->
Streams = lists:keyreplace(StreamID, #stream.id, Streams0,
Stream#stream{state=StreamState}),
commands(State#state{streams=Streams}, StreamID, Commands)
catch Class:Reason ->
error_logger:error_msg("Exception occurred in ~s:data(~p, ~p, ~p, ~p) with reason ~p:~p.",
[Handler, StreamID, IsFin, Data, StreamState0, Class, Reason]),
stream_reset(State, StreamID, {internal_error, {Class, Reason},
'Exception occurred in StreamHandler:data/4 call.'})
end;
false ->
stream_reset(State, StreamID, {stream_error, stream_closed,
'DATA frame received for a closed or non-existent stream. (RFC7540 6.1)'})
end;
%% Single HEADERS frame headers block.
frame(State, {headers, StreamID, IsFin, head_fin, HeaderBlock}) ->
%% @todo We probably need to validate StreamID here and in 4 next clauses.
stream_init(State, StreamID, IsFin, HeaderBlock);
%% HEADERS frame starting a headers block. Enter continuation mode.
frame(State, {headers, StreamID, IsFin, head_nofin, HeaderBlockFragment}) ->
State#state{parse_state={continuation, StreamID, IsFin, HeaderBlockFragment}};
%% Single HEADERS frame headers block with priority.
frame(State, {headers, StreamID, IsFin, head_fin,
_IsExclusive, _DepStreamID, _Weight, HeaderBlock}) ->
%% @todo Handle priority.
stream_init(State, StreamID, IsFin, HeaderBlock);
%% HEADERS frame starting a headers block. Enter continuation mode.
frame(State, {headers, StreamID, IsFin, head_nofin,
_IsExclusive, _DepStreamID, _Weight, HeaderBlockFragment}) ->
%% @todo Handle priority.
State#state{parse_state={continuation, StreamID, IsFin, HeaderBlockFragment}};
%% PRIORITY frame.
frame(State, {priority, _StreamID, _IsExclusive, _DepStreamID, _Weight}) ->
%% @todo Validate StreamID?
%% @todo Handle priority.
State;
%% RST_STREAM frame.
frame(State, {rst_stream, StreamID, Reason}) ->
stream_reset(State, StreamID, {stream_error, Reason, 'Stream reset requested by client.'});
%% SETTINGS frame.
frame(State, {settings, Settings}) ->
%% @todo Apply SETTINGS.
io:format("settings ~p~n", [Settings]),
State;
%% Ack for a previously sent SETTINGS frame.
frame(State=#state{next_settings=_NextSettings}, settings_ack) ->
%% @todo Apply SETTINGS that require synchronization.
State;
%% Unexpected PUSH_PROMISE frame.
frame(State, {push_promise, _, _, _, _}) ->
terminate(State, {connection_error, protocol_error,
'PUSH_PROMISE frames MUST only be sent on a peer-initiated stream. (RFC7540 6.6)'});
%% PING frame.
frame(State=#state{socket=Socket, transport=Transport}, {ping, Opaque}) ->
Transport:send(Socket, cow_http2:ping_ack(Opaque)),
State;
%% Ack for a previously sent PING frame.
%%
%% @todo Might want to check contents but probably a waste of time.
frame(State, {ping_ack, _Opaque}) ->
State;
%% GOAWAY frame.
frame(State, Frame={goaway, _, _, _}) ->
terminate(State, {stop, Frame, 'Client is going away.'});
%% Connection-wide WINDOW_UPDATE frame.
frame(State, {window_update, _Increment}) ->
%% @todo control flow
State;
%% Stream-specific WINDOW_UPDATE frame.
frame(State, {window_update, _StreamID, _Increment}) ->
%% @todo stream-specific control flow
State;
%% Unexpected CONTINUATION frame.
frame(State, {continuation, _, _, _}) ->
terminate(State, {connection_error, protocol_error,
'CONTINUATION frames MUST be preceded by a HEADERS frame. (RFC7540 6.10)'}).
continuation_frame(State=#state{parse_state={continuation, StreamID, IsFin, HeaderBlockFragment0}},
{continuation, StreamID, fin, HeaderBlockFragment1}) ->
stream_init(State#state{parse_state=normal}, StreamID, IsFin,
<< HeaderBlockFragment0/binary, HeaderBlockFragment1/binary >>);
continuation_frame(State=#state{parse_state={continuation, StreamID, IsFin, HeaderBlockFragment0}},
{continuation, StreamID, nofin, HeaderBlockFragment1}) ->
State#state{parse_state={continuation, StreamID, IsFin,
<< HeaderBlockFragment0/binary, HeaderBlockFragment1/binary >>}};
continuation_frame(State, _) ->
terminate(State, {connection_error, protocol_error,
'An invalid frame was received while expecting a CONTINUATION frame. (RFC7540 6.2)'}).
down(State=#state{children=Children0}, Pid, Msg) ->
case lists:keytake(Pid, 1, Children0) of
{value, {_, StreamID}, Children} ->
info(State#state{children=Children}, StreamID, Msg);
false ->
error_logger:error_msg("Received EXIT signal ~p for unknown process ~p.", [Msg, Pid]),
State
end.
info(State=#state{handler=Handler, streams=Streams0}, StreamID, Msg) ->
case lists:keyfind(StreamID, #stream.id, Streams0) of
Stream = #stream{state=StreamState0} ->
try Handler:info(StreamID, Msg, StreamState0) of
{Commands, StreamState} ->
Streams = lists:keyreplace(StreamID, #stream.id, Streams0,
Stream#stream{state=StreamState}),
commands(State#state{streams=Streams}, StreamID, Commands)
catch Class:Reason ->
error_logger:error_msg("Exception occurred in ~s:info(~p, ~p, ~p) with reason ~p:~p.",
[Handler, StreamID, Msg, StreamState0, Class, Reason]),
stream_reset(State, StreamID, {internal_error, {Class, Reason},
'Exception occurred in StreamHandler:info/3 call.'})
end;
false ->
error_logger:error_msg("Received message ~p for unknown stream ~p.", [Msg, StreamID]),
State
end.
commands(State, _, []) ->
State;
%% Send response headers.
%%
%% @todo Kill the stream if it sent a response when one has already been sent.
%% @todo Keep IsFin in the state.
%% @todo Same two things above apply to DATA, possibly promise too.
commands(State=#state{socket=Socket, transport=Transport, encode_state=EncodeState0}, StreamID,
[{response, IsFin, StatusCode, Headers0}|Tail]) ->
Headers = Headers0#{<<":status">> => integer_to_binary(StatusCode)},
{HeaderBlock, EncodeState} = headers_encode(Headers, EncodeState0),
Transport:send(Socket, cow_http2:headers(StreamID, IsFin, HeaderBlock)),
commands(State#state{encode_state=EncodeState}, StreamID, Tail);
%% Send a response body chunk.
%%
%% @todo WINDOW_UPDATE stuff require us to buffer some data.
commands(State=#state{socket=Socket, transport=Transport}, StreamID,
[{data, IsFin, Data}|Tail]) ->
Transport:send(Socket, cow_http2:data(StreamID, IsFin, Data)),
commands(State, StreamID, Tail);
%% Send a push promise.
%%
%% @todo We need to keep track of what promises we made so that we don't
%% end up with an infinite loop of promises.
commands(State0=#state{socket=Socket, transport=Transport, server_streamid=PromisedStreamID,
encode_state=EncodeState0}, StreamID,
[{promise, Method, Scheme, Authority, Path, Headers0}|Tail]) ->
Headers = Headers0#{<<":method">> => Method,
<<":scheme">> => Scheme,
<<":authority">> => Authority,
<<":path">> => Path},
{HeaderBlock, EncodeState} = headers_encode(Headers, EncodeState0),
Transport:send(Socket, cow_http2:push_promise(StreamID, PromisedStreamID, HeaderBlock)),
%% @todo iolist_to_binary(HeaderBlock) isn't optimal. Need a shortcut.
State = stream_init(State0#state{server_streamid=PromisedStreamID + 2, encode_state=EncodeState},
PromisedStreamID, fin, iolist_to_binary(HeaderBlock)),
commands(State, StreamID, Tail);
%% @todo Update the flow control state.
commands(State, StreamID, [{flow, _Size}|Tail]) ->
commands(State, StreamID, Tail);
%% Supervise a child process.
commands(State=#state{children=Children}, StreamID, [{spawn, Pid}|Tail]) ->
commands(State#state{children=[{Pid, StreamID}|Children]}, StreamID, Tail);
%% Upgrade to a new protocol.
%%
%% @todo Implementation.
%% @todo Can only upgrade if: there are no other streams and there are no children left alive.
%% @todo For HTTP/1.1 we should reject upgrading if pipelining is used.
commands(State, StreamID, [{upgrade, _Mod, _ModState}]) ->
commands(State, StreamID, []);
commands(State, StreamID, [{upgrade, _Mod, _ModState}|Tail]) ->
%% @todo This is an error. Not sure what to do here yet.
commands(State, StreamID, Tail).
terminate(#state{socket=Socket, transport=Transport, handler=Handler,
streams=Streams, children=Children}, Reason) ->
%% @todo Send GOAWAY frame; need to keep track of last good stream id; how?
terminate_all_streams(Streams, Reason, Handler, Children),
Transport:close(Socket),
exit({shutdown, Reason}).
terminate_all_streams([], _, _, []) ->
ok;
terminate_all_streams([#stream{id=StreamID, state=StreamState}|Tail], Reason, Handler, Children0) ->
stream_call_terminate(StreamID, Reason, Handler, StreamState),
Children = stream_terminate_children(Children0, StreamID, []),
terminate_all_streams(Tail, Reason, Handler, Children).
%% Stream functions.
stream_init(State0=#state{socket=Socket, transport=Transport, handler=Handler,
streams=Streams0, decode_state=DecodeState0}, StreamID, IsFin, HeaderBlock) ->
%% @todo Add clause for CONNECT requests (no scheme/path).
try headers_decode(HeaderBlock, DecodeState0) of
{Headers0=#{
<<":method">> := Method,
<<":scheme">> := Scheme,
<<":authority">> := Authority,
<<":path">> := Path}, DecodeState} ->
State = State0#state{decode_state=DecodeState},
Headers = maps:without([<<":method">>, <<":scheme">>, <<":authority">>, <<":path">>], Headers0),
try Handler:init(StreamID, IsFin, Method, Scheme, Authority, Path, Headers) of
{Commands, StreamState} ->
Streams = [#stream{id=StreamID, state=StreamState}|Streams0],
commands(State#state{streams=Streams}, StreamID, Commands)
catch Class:Reason ->
error_logger:error_msg("Exception occurred in ~s:init(~p, ~p, ~p, ~p, ~p, ~p, ~p) "
"with reason ~p:~p.",
[Handler, StreamID, IsFin, Method, Scheme, Authority, Path, Headers, Class, Reason]),
stream_reset(State, StreamID, {internal_error, {Class, Reason},
'Exception occurred in StreamHandler:init/7 call.'})
end;
{_, DecodeState} ->
Transport:send(Socket, cow_http2:rst_stream(StreamID, protocol_error)),
State0#state{decode_state=DecodeState}
catch _:_ ->
terminate(State0, {connection_error, compression_error,
'Error while trying to decode HPACK-encoded header block. (RFC7540 4.3)'})
end.
%% @todo We might need to keep track of which stream has been reset so we don't send lots of them.
stream_reset(State=#state{socket=Socket, transport=Transport}, StreamID,
StreamError={internal_error, _, _}) ->
Transport:send(Socket, cow_http2:rst_stream(StreamID, internal_error)),
stream_terminate(State, StreamID, StreamError);
stream_reset(State=#state{socket=Socket, transport=Transport}, StreamID,
StreamError={stream_error, Reason, _}) ->
Transport:send(Socket, cow_http2:rst_stream(StreamID, Reason)),
stream_terminate(State, StreamID, StreamError).
stream_terminate(State=#state{handler=Handler, streams=Streams0, children=Children0}, StreamID, Reason) ->
case lists:keytake(StreamID, #stream.id, Streams0) of
{value, #stream{state=StreamState}, Streams} ->
stream_call_terminate(StreamID, Reason, Handler, StreamState),
Children = stream_terminate_children(Children0, StreamID, []),
State#state{streams=Streams, children=Children};
false ->
%% @todo Unknown stream. Not sure what to do here. Check again once all
%% terminate calls have been written.
State
end.
stream_call_terminate(StreamID, Reason, Handler, StreamState) ->
try
Handler:terminate(StreamID, Reason, StreamState),
ok
catch Class:Reason ->
error_logger:error_msg("Exception occurred in ~s:terminate(~p, ~p, ~p) with reason ~p:~p.",
[Handler, StreamID, Reason, StreamState, Class, Reason])
end.
stream_terminate_children([], _, Acc) ->
Acc;
stream_terminate_children([{Pid, StreamID}|Tail], StreamID, Acc) ->
exit(Pid, kill),
stream_terminate_children(Tail, StreamID, Acc);
stream_terminate_children([Child|Tail], StreamID, Acc) ->
stream_terminate_children(Tail, StreamID, [Child|Acc]).
%% Headers encode/decode.
headers_decode(HeaderBlock, DecodeState0) ->
{Headers, DecodeState} = cow_hpack:decode(HeaderBlock, DecodeState0),
{maps:from_list(Headers), DecodeState}.
%% @todo We will need to special-case the set-cookie header here.
headers_encode(Headers0, EncodeState) ->
Headers = maps:to_list(Headers0),
cow_hpack:encode(Headers, EncodeState).
%% System callbacks.
-spec system_continue(_, _, #state{}) -> ok.
system_continue(_, _, {State, Buffer}) ->
loop(State, Buffer).
-spec system_terminate(any(), _, _, _) -> no_return().
system_terminate(Reason, _, _, _) ->
exit(Reason).
-spec system_code_change(Misc, _, _, _) -> {ok, Misc} when Misc::{#state{}, binary()}.
system_code_change(Misc, _, _, _) ->
{ok, Misc}.
