%%% @doc Per-tunnel server session for CONNECT-IP (RFC 9484) over
%%% HTTP/1.1.
%%%
%%% Spawned by `masque_h1_server' after a `GET' with
%%% `Upgrade: connect-ip' passes validation. The session calls
%%% `h1:accept_upgrade/3' in `init/1' so socket ownership lands on
%%% this gen_server. After the 101 response, the raw TLS socket
%%% becomes the tunnel; datagrams and control capsules are framed
%%% via RFC 9297 capsules on that socket.
%%%
%%% Wire format is identical to the h2 / h3 paths, so
%%% `masque_ip_capsule' + `masque_datagram' are reused unchanged;
%%% only the transport plumbing differs.
-module(masque_ip_h1_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").
-include("masque_ip.hrl").
-record(state, {
transport :: gen_tcp | ssl,
socket :: ssl:sslsocket() | gen_tcp:socket(),
handler :: module(),
h_state :: term(),
req :: map(),
cap_buf = <<>> :: binary(),
max_cap :: pos_integer(),
peer_pending = #{} :: #{pos_integer() => true},
start_time :: integer() | undefined,
idle_ms :: non_neg_integer() | infinity,
idle_ref :: reference() | 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,
handler := Handler, handler_opts := HOpts, req := Req}) ->
process_flag(trap_exit, true),
MaxCap = maps:get(max_capsule_size, HOpts,
?MASQUE_DEFAULT_MAX_CAPSULE_SIZE),
IdleMs = maps:get(idle_timeout_ms, HOpts, 300000),
%% init_handler before accept_upgrade: a handler rejection (e.g.
%% address pool exhausted) becomes a 502 on the as-yet-unupgraded
%% connection, not a "101 + immediate close".
case init_handler(Handler, Req, HOpts) of
{ok, HState, Actions} ->
case h1:accept_upgrade(Conn, StreamId,
[{<<"capsule-protocol">>, <<"?1">>}]) of
{ok, Socket, Buffer} ->
Transport = socket_transport(Socket),
State0 = arm_idle(#state{
transport = Transport,
socket = Socket,
handler = Handler,
h_state = HState,
req = Req,
cap_buf = Buffer,
max_cap = MaxCap,
start_time = erlang:monotonic_time(millisecond),
idle_ms = IdleMs
}),
case drain_and_arm(State0) of
{ok, State1} ->
apply_init_actions(Actions, State1);
{stop, Reason, _State} ->
_ = close_socket(State0),
{stop, Reason}
end;
{error, Reason} ->
try_callback(Handler, terminate,
[{accept_upgrade, Reason}, HState]),
{stop, {accept_upgrade, Reason}}
end;
{stop, Reason} ->
{stop, Reason}
end.
handle_call(_Req, _From, S) ->
{reply, {error, unknown_call}, S}.
handle_cast({inject_packet, Pkt}, S) when is_binary(Pkt) ->
%% Out-of-band packet injection. Re-uses the same h1 capsule
%% send path that the `{send_ip_packet, _}' action takes.
case do_actions([{send_ip_packet, Pkt}], S) of
{ok, S2} -> {noreply, S2};
{stop, Reason, S2} -> {stop, Reason, S2}
end;
handle_cast(_Msg, S) ->
{noreply, S}.
handle_info({ssl, Sock, Bytes},
#state{socket = Sock, cap_buf = Buf, max_cap = Max} = S) ->
S1 = arm_idle(S),
New = <<Buf/binary, Bytes/binary>>,
case byte_size(New) > Max of
true -> {stop, capsule_buffer_overflow, S1};
false -> step(S1#state{cap_buf = New})
end;
handle_info({tcp, Sock, Bytes},
#state{socket = Sock, cap_buf = Buf, max_cap = Max} = S) ->
S1 = arm_idle(S),
New = <<Buf/binary, Bytes/binary>>,
case byte_size(New) > Max of
true -> {stop, capsule_buffer_overflow, S1};
false -> step(S1#state{cap_buf = New})
end;
handle_info({timeout, Ref, idle},
#state{idle_ref = Ref} = S) ->
{stop, idle_timeout, S};
handle_info({ssl_closed, Sock}, #state{socket = Sock} = S) ->
{stop, peer_closed, S};
handle_info({tcp_closed, Sock}, #state{socket = Sock} = S) ->
{stop, peer_closed, S};
handle_info({ssl_error, Sock, Reason}, #state{socket = Sock} = S) ->
{stop, {ssl_error, Reason}, S};
handle_info({tcp_error, Sock, Reason}, #state{socket = Sock} = S) ->
{stop, {tcp_error, Reason}, S};
handle_info({'EXIT', _Pid, _Reason}, S) ->
{noreply, S};
handle_info(Msg, S) ->
dispatch(handle_info, [Msg], S).
terminate(Reason, #state{handler = Handler, h_state = HState,
start_time = Start} = S) ->
_ = cancel_idle(S),
_ = close_socket(S),
try_callback(Handler, terminate, [Reason, HState]),
_ = emit_tunnel_closed(Start),
ok.
code_change(_OldVsn, S, _Extra) ->
{ok, S}.
emit_tunnel_closed(undefined) -> ok;
emit_tunnel_closed(T) ->
Duration = erlang:monotonic_time(millisecond) - T,
masque_metrics:tunnel_closed(Duration,
#{protocol => ip, transport => h1}).
%%====================================================================
%% Capsule decode loop
%%====================================================================
step(#state{cap_buf = Buf} = S) ->
case h1_capsule:decode(Buf) of
{ok, {Type, Inner}, Rest} ->
case dispatch_capsule(Type, Inner, S#state{cap_buf = Rest}) of
{noreply, S2} -> step(S2);
Stop -> Stop
end;
{more, _} ->
_ = arm_once(S),
{noreply, S}
end.
drain_and_arm(S) ->
case step(S) of
{noreply, S2} -> {ok, S2};
{stop, Reason, S2} -> {stop, Reason, S2}
end.
apply_init_actions(Actions, State) ->
case do_actions(Actions, State) of
{ok, S2} -> {ok, S2};
{stop, Reason, _S} -> {stop, Reason}
end.
dispatch_capsule(datagram, Inner, S) ->
dispatch_datagram(Inner, S);
dispatch_capsule(?MASQUE_CAPSULE_ADDRESS_REQUEST, Body,
#state{peer_pending = Pend} = S) ->
case masque_ip_capsule:decode_address_request(Body) of
{ok, Entries} ->
Pend1 = lists:foldl(
fun(#ip_prefix_request{request_id = Id}, Acc) ->
Acc#{Id => true}
end, Pend, Entries),
dispatch(handle_address_request, [Entries],
S#state{peer_pending = Pend1});
{error, _} ->
{stop, malformed_capsule, S}
end;
dispatch_capsule(?MASQUE_CAPSULE_ADDRESS_ASSIGN, Body, S) ->
case masque_ip_capsule:decode_address_assign(Body) of
{ok, Entries} ->
dispatch(handle_address_assign, [Entries], S);
{error, _} ->
{stop, malformed_capsule, S}
end;
dispatch_capsule(?MASQUE_CAPSULE_ROUTE_ADVERTISEMENT, Body, S) ->
case masque_ip_capsule:decode_route_advertisement(Body) of
{ok, Entries} ->
dispatch(handle_route_advertisement, [Entries], S);
{error, _} ->
{stop, malformed_capsule, S}
end;
dispatch_capsule(Type, Inner, S) when is_integer(Type) ->
%% RFC 9297 §3.3: unknown capsule types are silently ignored.
%% `dispatch/3' returns `{noreply, S}' unchanged when the handler
%% does not export `handle_capsule/3', which preserves that
%% behaviour; handlers that do export it get an extension hook.
dispatch(handle_capsule, [Type, Inner], S).
dispatch_datagram(Payload, S) ->
case masque_datagram:decode(Payload) of
{ok, {?MASQUE_CONTEXT_ID_IP, IPPkt}} ->
dispatch(handle_ip_packet, [IPPkt], S);
{ok, {_OtherCtx, _}} ->
{noreply, S};
{error, _} ->
{noreply, S}
end.
%%====================================================================
%% Handler dispatch (mirrors masque_ip_server_session)
%%====================================================================
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.
exported(Mod, Fun, Arity) ->
_ = code:ensure_loaded(Mod),
erlang:function_exported(Mod, Fun, Arity).
apply_actions_noreply(Actions, State) ->
case do_actions(Actions, State) of
{ok, S2} -> {noreply, S2};
{stop, Reason, S2} -> {stop, Reason, S2}
end.
%%====================================================================
%% Action interpreter (matches masque_ip_server_session's surface so
%% user handlers work unchanged across transports).
%%====================================================================
do_actions([], S) ->
{ok, S};
do_actions([{send_ip_packet, Pkt} | Rest], S) ->
_ = send_datagram(S, ?MASQUE_CONTEXT_ID_IP, Pkt),
do_actions(Rest, S);
do_actions([{assign, Entries} | Rest], S) ->
case send_assign(Entries, S) of
{ok, S2} -> do_actions(Rest, S2);
{error, _} -> do_actions(Rest, S)
end;
do_actions([{advertise, Routes} | Rest], S) ->
_ = send_advertise(Routes, S),
do_actions(Rest, S);
do_actions([{request_addresses, Prefixes} | Rest], S) ->
_ = send_request(Prefixes, S),
do_actions(Rest, S);
do_actions([{icmp_error, {Kind, Spec, Invoking}} | Rest], S)
when is_binary(Invoking) ->
Pkt = masque_icmp:apply_action(Kind, Spec, Invoking),
_ = send_datagram(S, ?MASQUE_CONTEXT_ID_IP, Pkt),
do_actions(Rest, S);
do_actions([{icmp_error, _Bad} | Rest], S) ->
do_actions(Rest, S);
do_actions([{send_capsule, Type, Value} | Rest], S) ->
_ = h1_upgrade:send_capsule(S#state.transport, S#state.socket,
Type, Value),
do_actions(Rest, S);
do_actions([{close, _Reason} | _Rest], S) ->
{stop, normal, S};
do_actions([close_session | _Rest], S) ->
{stop, normal, S};
do_actions([_Unknown | Rest], S) ->
do_actions(Rest, S).
send_datagram(#state{transport = T, socket = Sock}, Ctx, Payload) ->
Inner = iolist_to_binary(masque_datagram:encode(Ctx, Payload)),
h1_upgrade:send_capsule(T, Sock, datagram, Inner).
send_assign(Entries, #state{peer_pending = Pend} = S) ->
case consume_pending(Entries, Pend) of
{ok, Pend1} ->
try masque_ip_capsule:encode_address_assign(Entries) of
Body ->
case h1_upgrade:send_capsule(S#state.transport,
S#state.socket,
?MASQUE_CAPSULE_ADDRESS_ASSIGN,
Body) of
ok -> {ok, S#state{peer_pending = Pend1}};
{error, _} = Err -> Err
end
catch
error:Reason -> {error, Reason}
end;
{error, _} = Err -> Err
end.
consume_pending([], Pend) -> {ok, Pend};
consume_pending([#ip_assignment{request_id = 0} | Rest], Pend) ->
consume_pending(Rest, Pend);
consume_pending([#ip_assignment{request_id = Id} | Rest], Pend) ->
case maps:is_key(Id, Pend) of
true -> consume_pending(Rest, maps:remove(Id, Pend));
false -> {error, {no_such_pending_request, Id}}
end.
send_advertise(Routes, S) ->
try masque_ip_capsule:encode_route_advertisement(Routes) of
Body ->
h1_upgrade:send_capsule(S#state.transport, S#state.socket,
?MASQUE_CAPSULE_ROUTE_ADVERTISEMENT,
Body)
catch
error:Reason -> {error, Reason}
end.
send_request(Prefixes, S) ->
Ids = allocate_request_ids(length(Prefixes)),
Entries = lists:zipwith(
fun(Id, {V, A, P}) ->
#ip_prefix_request{request_id = Id, version = V,
address = A, prefix_len = P}
end, Ids, Prefixes),
try masque_ip_capsule:encode_address_request(Entries) of
Body ->
h1_upgrade:send_capsule(S#state.transport, S#state.socket,
?MASQUE_CAPSULE_ADDRESS_REQUEST,
Body)
catch
error:Reason -> {error, Reason}
end.
allocate_request_ids(N) ->
Base = erlang:unique_integer([positive, monotonic]),
[Base + I || I <- lists:seq(0, N - 1)].
%%====================================================================
%% Socket helpers
%%====================================================================
arm_once(#state{transport = ssl, socket = Sock}) ->
ssl:setopts(Sock, [{active, once}, {mode, binary}]);
arm_once(#state{transport = gen_tcp, socket = Sock}) ->
inet:setopts(Sock, [{active, once}, {mode, binary}]).
close_socket(#state{transport = T, socket = S}) ->
try close_transport(T, S) catch _:_ -> ok end.
close_transport(ssl, S) -> ssl:close(S);
close_transport(gen_tcp, S) -> gen_tcp:close(S).
socket_transport(Socket) when is_tuple(Socket),
element(1, Socket) =:= sslsocket ->
ssl;
socket_transport(_) ->
gen_tcp.
%%====================================================================
%% Misc
%%====================================================================
safe_apply(M, F, A) ->
try apply(M, F, A)
catch
Class:Reason:Stack ->
error_logger:error_msg(
"masque ip-h1 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.
%%====================================================================
%% Idle timer
%%====================================================================
arm_idle(#state{idle_ms = infinity} = S) -> S;
arm_idle(#state{idle_ms = 0} = S) -> S;
arm_idle(#state{idle_ref = OldRef, idle_ms = Ms} = S) ->
case OldRef of
undefined -> ok;
_ -> _ = erlang:cancel_timer(OldRef), ok
end,
Ref = erlang:start_timer(Ms, self(), idle),
S#state{idle_ref = Ref}.
cancel_idle(#state{idle_ref = undefined}) -> ok;
cancel_idle(#state{idle_ref = Ref}) ->
_ = erlang:cancel_timer(Ref),
ok.