%%% @doc Per-tunnel server session for CONNECT-TCP.
%%%
%%% Raw bytes on the HTTP stream body are relayed to/from the handler
%%% module. No datagram framing, no context-IDs. Stream END_STREAM
%%% maps to TCP FIN.
-module(masque_tcp_server_session).
-behaviour(gen_server).
-export([start_link/1]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-include("masque.hrl").
-record(state, {
conn :: pid(),
stream_id :: non_neg_integer(),
transport :: h3 | h2,
handler :: module(),
h_state :: term(),
req :: map(),
%% Actions from handler init, applied after finalize (H3 path)
pending_actions :: [term()] | undefined
}).
%%====================================================================
%% API
%%====================================================================
-spec start_link(map()) -> {ok, pid()} | ignore | {error, term()}.
start_link(Args) ->
gen_server:start_link(?MODULE, Args, []).
%%====================================================================
%% gen_server
%%====================================================================
init(#{conn := Conn, stream_id := StreamId, transport := Transport,
handler := Handler, handler_opts := HOpts, req := Req} = Args) ->
process_flag(trap_exit, true),
%% Monitor router (H3 path) so we stop if it dies.
_ = case maps:find(router, Args) of
{ok, Router} -> erlang:monitor(process, Router);
error -> ok
end,
case init_handler(Handler, Req, HOpts) of
{ok, HState, Actions} ->
State = #state{conn = Conn, stream_id = StreamId,
transport = Transport, handler = Handler,
h_state = HState, req = Req},
case maps:is_key(router, Args) of
true ->
%% H3 path: defer 200 + claim to finalize
{ok, State#state{pending_actions = Actions}};
false ->
%% H2 path: immediate finalize
case send_response(State, 200,
[{<<"capsule-protocol">>, <<"?1">>}]) of
ok ->
case claim_stream(State) of
ok ->
apply_actions(Actions, State);
{ok, _} ->
apply_actions(Actions, State);
{error, _} ->
{stop, stream_dead}
end;
{error, _} ->
{stop, stream_dead}
end
end;
{stop, Reason} ->
{stop, Reason}
end.
send_response(#state{transport = h3, conn = C, stream_id = S}, Status, Hdrs) ->
quic_h3:send_response(C, S, Status, Hdrs);
send_response(#state{transport = h2, conn = C, stream_id = S}, Status, Hdrs) ->
h2:send_response(C, S, Status, Hdrs).
claim_stream(#state{transport = h3, conn = C, stream_id = S}) ->
quic_h3:set_stream_handler(C, S, self());
claim_stream(#state{transport = h2, conn = C, stream_id = S}) ->
h2:set_stream_handler(C, S, self()).
handle_call(finalize, _From,
#state{pending_actions = Actions} = S)
when Actions =/= undefined ->
case send_response(S, 200, [{<<"capsule-protocol">>, <<"?1">>}]) of
ok ->
case claim_stream(S) of
ok ->
{reply, ok,
run_init_actions(Actions,
S#state{pending_actions = undefined})};
{ok, _} ->
{reply, ok,
run_init_actions(Actions,
S#state{pending_actions = undefined})};
{error, _} ->
{reply, {error, stream_dead}, S}
end;
{error, _} ->
{reply, {error, stream_dead}, S}
end;
handle_call(_Req, _From, S) ->
{reply, {error, unknown_call}, S}.
handle_cast(connection_closed, S) ->
{stop, connection_closed, S};
handle_cast(_Msg, S) ->
{noreply, S}.
%% Incoming stream data - raw TCP bytes
handle_info({Tag, _Conn, {data, StreamId, Bytes, Fin}},
#state{stream_id = StreamId} = S)
when Tag =:= quic_h3; Tag =:= h2 ->
case dispatch(handle_data, [Bytes], S) of
{noreply, S2} when Fin -> dispatch_eof(S2);
Result -> Result
end;
handle_info({masque_stream_data, StreamId, Bytes, Fin},
#state{stream_id = StreamId} = S) ->
case dispatch(handle_data, [Bytes], S) of
{noreply, S2} when Fin -> dispatch_eof(S2);
Result -> Result
end;
handle_info({Tag, _Conn, {stream_reset, StreamId, _}},
#state{stream_id = StreamId} = S)
when Tag =:= quic_h3; Tag =:= h2 ->
{stop, peer_reset, S};
handle_info({masque_stream_reset, StreamId, _},
#state{stream_id = StreamId} = S) ->
{stop, peer_reset, S};
handle_info({h2, _Conn, closed}, S) ->
{stop, peer_closed, S};
handle_info({'EXIT', _Pid, _Reason}, S) ->
{noreply, S};
handle_info({'DOWN', _MRef, process, _Pid, _Reason}, S) ->
%% Router died - clean up
{stop, router_gone, S};
handle_info(Msg, S) ->
dispatch(handle_info, [Msg], S).
terminate(Reason, #state{conn = Conn, transport = Transport,
handler = Handler, h_state = HState})
when Reason =:= connection_closed;
Reason =:= router_gone;
Reason =:= peer_reset;
Reason =:= peer_closed ->
maybe_release_h2_tunnel(Transport, Conn),
try_callback(Handler, terminate, [Reason, HState]),
ok;
terminate(Reason, #state{conn = Conn, transport = Transport,
handler = Handler, h_state = HState} = S) ->
maybe_release_h2_tunnel(Transport, Conn),
_ = (try transport_send_data(S, <<>>, true) catch _:_ -> ok end),
try_callback(Handler, terminate, [Reason, HState]),
ok.
maybe_release_h2_tunnel(h2, Conn) -> masque_h2_server:release_tunnel(Conn);
maybe_release_h2_tunnel(_, _) -> ok.
code_change(_OldVsn, S, _Extra) ->
{ok, S}.
%%====================================================================
%% Handler dispatch
%%====================================================================
init_handler(Handler, Req, HOpts) ->
case exported(Handler, init, 2) of
true ->
case safe_apply(Handler, init, [Req, HOpts]) of
{ok, HState} -> {ok, HState, []};
{ok, HState, Actions} -> {ok, HState, Actions};
{stop, Reason} -> {stop, Reason};
Other -> {stop, {bad_init, Other}}
end;
false ->
{ok, undefined, []}
end.
dispatch(CB, Extra, #state{handler = Handler, h_state = HS} = S) ->
case exported(Handler, CB, length(Extra) + 1) of
true ->
case safe_apply(Handler, CB, Extra ++ [HS]) of
{ok, HS2} -> {noreply, S#state{h_state = HS2}};
{ok, HS2, Actions} -> apply_actions_noreply(
Actions, S#state{h_state = HS2});
{stop, Reason, HS2} -> {stop, Reason,
S#state{h_state = HS2}};
_ -> {noreply, S}
end;
false ->
{noreply, S}
end.
dispatch_eof(#state{handler = Handler} = S) ->
case exported(Handler, handle_eof, 1) of
true -> dispatch(handle_eof, [], S);
false -> {stop, normal, S}
end.
exported(Mod, Fun, Arity) ->
_ = code:ensure_loaded(Mod),
erlang:function_exported(Mod, Fun, Arity).
apply_actions(Actions, State) ->
case do_actions(Actions, State) of
{ok, S2} -> {ok, S2};
{stop, Reason, _} -> {stop, Reason}
end.
apply_actions_noreply(Actions, State) ->
case do_actions(Actions, State) of
{ok, S2} -> {noreply, S2};
{stop, Reason, S2} -> {stop, Reason, S2}
end.
run_init_actions([], S) -> S;
run_init_actions(Actions, S) ->
case do_actions(Actions, S) of
{ok, S2} -> S2;
{stop, Reason, _} -> exit(Reason)
end.
do_actions([], S) -> {ok, S};
do_actions([{send_data, Bytes} | Rest], S) ->
_ = transport_send_data(S, Bytes, false),
do_actions(Rest, S);
do_actions([{send_data, Bytes, Fin} | Rest], S) ->
_ = transport_send_data(S, Bytes, Fin),
do_actions(Rest, S);
do_actions([close_session | _Rest], S) ->
_ = transport_send_data(S, <<>>, true),
{stop, normal, S};
do_actions([_Unknown | Rest], S) ->
do_actions(Rest, S).
transport_send_data(#state{transport = h3, conn = C, stream_id = Sid}, Bytes, Fin) ->
quic_h3:send_data(C, Sid, Bytes, Fin);
transport_send_data(#state{transport = h2, conn = C, stream_id = Sid}, Bytes, Fin) ->
h2:send_data(C, Sid, Bytes, Fin).
safe_apply(M, F, A) ->
try apply(M, F, A)
catch
Class:Reason:Stack ->
error_logger:error_msg(
"masque tcp handler ~p:~p/~p failed: ~p:~p~n~p~n",
[M, F, length(A), Class, Reason, Stack]),
{stop, {handler_crash, Reason}}
end.
try_callback(Mod, Fun, Args) ->
Arity = length(Args),
case erlang:function_exported(Mod, Fun, Arity) of
true -> (try apply(Mod, Fun, Args) catch _:_ -> ok end);
false -> ok
end.