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https://github.com/ninenines/cowboy.git
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58909b0144
This implements the upcoming draft-13 but has bits to make it work with draft-02 that most (all?) Chromium versions use. Data and events are not going through cowboy_stream beyond init. Since this approach appears to work well it may be a good idea to do the same for Websocket over HTTP/2+ and improve its performance.
103 lines
3.5 KiB
Erlang
103 lines
3.5 KiB
Erlang
%% This module echoes client events back,
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%% including creating new streams.
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-module(wt_echo_h).
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-behavior(cowboy_webtransport).
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-export([init/2]).
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-export([webtransport_handle/2]).
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-export([webtransport_info/2]).
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-export([terminate/3]).
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%% -define(DEBUG, 1).
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-ifdef(DEBUG).
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-define(LOG(Fmt, Args), ct:pal(Fmt, Args)).
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-else.
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-define(LOG(Fmt, Args), _ = Fmt, _ = Args, ok).
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-endif.
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init(Req0, _) ->
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?LOG("WT init ~p~n", [Req0]),
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Req = case cowboy_req:parse_header(<<"wt-available-protocols">>, Req0) of
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undefined ->
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Req0;
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[Protocol|_] ->
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cowboy_req:set_resp_header(<<"wt-protocol">>, cow_http_hd:wt_protocol(Protocol), Req0)
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end,
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{cowboy_webtransport, Req, #{}}.
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webtransport_handle(Event = {stream_open, StreamID, bidi}, Streams) ->
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?LOG("WT handle ~p~n", [Event]),
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{[], Streams#{StreamID => bidi}};
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webtransport_handle(Event = {stream_open, StreamID, unidi}, Streams) ->
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?LOG("WT handle ~p~n", [Event]),
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OpenStreamRef = make_ref(),
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{[{open_stream, OpenStreamRef, unidi, <<>>}], Streams#{
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StreamID => {unidi_remote, OpenStreamRef},
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OpenStreamRef => {unidi_local, StreamID}}};
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webtransport_handle(Event = {opened_stream_id, OpenStreamRef, OpenStreamID}, Streams) ->
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?LOG("WT handle ~p~n", [Event]),
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case Streams of
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#{OpenStreamRef := bidi} ->
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{[], maps:remove(OpenStreamRef, Streams#{
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OpenStreamID => bidi
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})};
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#{OpenStreamRef := {unidi_local, RemoteStreamID}} ->
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#{RemoteStreamID := {unidi_remote, OpenStreamRef}} = Streams,
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{[], maps:remove(OpenStreamRef, Streams#{
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RemoteStreamID => {unidi_remote, OpenStreamID},
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OpenStreamID => {unidi_local, RemoteStreamID}
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})}
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end;
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webtransport_handle(Event = {stream_data, StreamID, _IsFin, <<"TEST:", Test/bits>>}, Streams) ->
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?LOG("WT handle ~p~n", [Event]),
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case Test of
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<<"open_bidi">> ->
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OpenStreamRef = make_ref(),
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{[{open_stream, OpenStreamRef, bidi, <<>>}],
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Streams#{OpenStreamRef => bidi}};
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<<"initiate_close">> ->
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{[initiate_close], Streams};
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<<"close">> ->
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{[close], Streams};
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<<"close_app_code">> ->
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{[{close, 1234567890}], Streams};
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<<"close_app_code_msg">> ->
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{[{close, 1234567890, <<"onetwothreefourfivesixseveneightnineten">>}], Streams};
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<<"event_pid:", EventPidBin/bits>> ->
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{[{send, StreamID, nofin, <<"event_pid_received">>}],
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Streams#{event_pid => binary_to_term(EventPidBin)}}
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end;
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webtransport_handle(Event = {stream_data, StreamID, IsFin, Data}, Streams) ->
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?LOG("WT handle ~p~n", [Event]),
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case Streams of
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#{StreamID := bidi} ->
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{[{send, StreamID, IsFin, Data}], Streams};
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#{StreamID := {unidi_remote, Ref}} when is_reference(Ref) ->
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%% The stream isn't ready. We try again later.
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erlang:send_after(100, self(), {try_again, Event}),
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{[], Streams};
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#{StreamID := {unidi_remote, LocalStreamID}} ->
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{[{send, LocalStreamID, IsFin, Data}], Streams}
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end;
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webtransport_handle(Event = {datagram, Data}, Streams) ->
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?LOG("WT handle ~p~n", [Event]),
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{[{send, datagram, Data}], Streams};
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webtransport_handle(Event = close_initiated, Streams) ->
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?LOG("WT handle ~p~n", [Event]),
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{[{send, datagram, <<"TEST:close_initiated">>}], Streams};
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webtransport_handle(Event, Streams) ->
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?LOG("WT handle ignore ~p~n", [Event]),
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{[], Streams}.
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webtransport_info({try_again, Event}, Streams) ->
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?LOG("WT try_again ~p", [Event]),
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webtransport_handle(Event, Streams).
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terminate(Reason, Req, State=#{event_pid := EventPid}) ->
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?LOG("WT terminate ~0p~n~0p~n~0p", [Reason, Req, State]),
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EventPid ! {'$wt_echo_h', terminate, Reason, Req, State},
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ok;
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terminate(Reason, Req, State) ->
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?LOG("WT terminate ~0p~n~0p~n~0p", [Reason, Req, State]),
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ok.
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