%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2011. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
-module(diameter_sctp).
-behaviour(gen_server).
%% interface
-export([start/3]).
%% child start from supervisor
-export([start_link/1]).
%% child start from here
-export([init/1]).
%% gen_server callbacks
-export([handle_call/3,
handle_cast/2,
handle_info/2,
code_change/3,
terminate/2]).
-include_lib("kernel/include/inet_sctp.hrl").
-include_lib("diameter/include/diameter.hrl").
-define(ERROR(T), erlang:error({T, ?MODULE, ?LINE})).
%% The default port for a listener.
-define(DEFAULT_PORT, 3868). %% RFC 3588, ch 2.1
%% How long a listener with no associations lives before offing
%% itself.
-define(LISTENER_TIMEOUT, 30000).
%% How long to wait for a transport process to attach after
%% association establishment.
-define(ACCEPT_TIMEOUT, 5000).
-type uint() :: non_neg_integer().
%% Accepting/connecting transport process state.
-record(transport,
{parent :: pid(),
mode :: {accept, pid()}
| {connect, {list(inet:ip_address()), uint(), list()}}
%% {RAs, RP, Errors}
| connect,
socket :: gen_sctp:sctp_socket(),
assoc_id :: gen_sctp:assoc_id(), %% association identifier
peer :: {[inet:ip_address()], uint()}, %% {RAs, RP}
streams :: {uint(), uint()}, %% {InStream, OutStream} counts
os = 0 :: uint()}). %% next output stream
%% Listener process state.
-record(listener,
{ref :: reference(),
socket :: gen_sctp:sctp_socket(),
count = 0 :: uint(),
tmap = ets:new(?MODULE, []) :: ets:tid(),
%% {MRef, Pid|AssocId}, {AssocId, Pid}
pending = {0, ets:new(?MODULE, [ordered_set])},
tref :: reference()}).
%% Field tmap is used to map an incoming message or event to the
%% relevent transport process. Field pending implements a queue of
%% transport processes to which an association has been assigned (at
%% comm_up and written into tmap) but for which diameter hasn't yet
%% spawned a transport process: a short-lived state of affairs as a
%% new transport is spawned as a consequence of a peer being taken up,
%% transport processes being spawned by the listener on demand. In
%% case diameter starts a transport before comm_up on a new
%% association, pending is set to an improper list with the spawned
%% transport as head and the queue as tail.
%% ---------------------------------------------------------------------------
%% # start/3
%% ---------------------------------------------------------------------------
start(T, #diameter_service{capabilities = Caps}, Opts)
when is_list(Opts) ->
diameter_sctp_sup:start(), %% start supervisors on demand
Addrs = Caps#diameter_caps.host_ip_address,
s(T, Addrs, lists:map(fun ip/1, Opts)).
ip({ifaddr, A}) ->
{ip, A};
ip(T) ->
T.
%% A listener spawns transports either as a consequence of this call
%% when there is not yet an association to associate with it, or at
%% comm_up on a new association in which case the call retrieves a
%% transport from the pending queue.
s({accept, Ref} = A, Addrs, Opts) ->
{LPid, LAs} = listener(Ref, {Opts, Addrs}),
try gen_server:call(LPid, {A, self()}, infinity) of
{ok, TPid} -> {ok, TPid, LAs}
catch
exit: Reason -> {error, Reason}
end;
%% This implementation is due to there being no accept call in
%% gen_sctp in order to be able to accept a new association only
%% *after* an accepting transport has been spawned.
s({connect = C, _}, Addrs, Opts) ->
diameter_sctp_sup:start_child({C, self(), Opts, Addrs}).
%% start_link/1
start_link(T) ->
proc_lib:start_link(?MODULE,
init,
[T],
infinity,
diameter_lib:spawn_opts(server, [])).
%% ---------------------------------------------------------------------------
%% # init/1
%% ---------------------------------------------------------------------------
init(T) ->
gen_server:enter_loop(?MODULE, [], i(T)).
%% i/1
%% A process owning a listening socket.
i({listen, Ref, {Opts, Addrs}}) ->
{LAs, Sock} = AS = open(Addrs, Opts, ?DEFAULT_PORT),
proc_lib:init_ack({ok, self(), LAs}),
ok = gen_sctp:listen(Sock, true),
true = diameter_reg:add_new({?MODULE, listener, {Ref, AS}}),
start_timer(#listener{ref = Ref,
socket = Sock});
%% A connecting transport.
i({connect, Pid, Opts, Addrs}) ->
{[As, Ps], Rest} = proplists:split(Opts, [raddr, rport]),
RAs = [diameter_lib:ipaddr(A) || {raddr, A} <- As],
[RP] = [P || {rport, P} <- Ps] ++ [P || P <- [?DEFAULT_PORT], [] == Ps],
{LAs, Sock} = open(Addrs, Rest, 0),
proc_lib:init_ack({ok, self(), LAs}),
erlang:monitor(process, Pid),
#transport{parent = Pid,
mode = {connect, connect(Sock, RAs, RP, [])},
socket = Sock};
%% An accepting transport spawned by diameter.
i({accept, Pid, LPid, Sock}) ->
proc_lib:init_ack({ok, self()}),
erlang:monitor(process, Pid),
erlang:monitor(process, LPid),
#transport{parent = Pid,
mode = {accept, LPid},
socket = Sock};
%% An accepting transport spawned at association establishment.
i({accept, Ref, LPid, Sock, Id}) ->
proc_lib:init_ack({ok, self()}),
MRef = erlang:monitor(process, LPid),
%% Wait for a signal that the transport has been started before
%% processing other messages.
receive
{Ref, Pid} -> %% transport started
#transport{parent = Pid,
mode = {accept, LPid},
socket = Sock};
{'DOWN', MRef, process, _, _} = T -> %% listener down
close(Sock, Id),
x(T)
after ?ACCEPT_TIMEOUT ->
close(Sock, Id),
x(timeout)
end.
%% close/2
close(Sock, Id) ->
gen_sctp:eof(Sock, #sctp_assoc_change{assoc_id = Id}).
%% Having to pass a record here is hokey.
%% listener/2
listener(LRef, T) ->
l(diameter_reg:match({?MODULE, listener, {LRef, '_'}}), LRef, T).
%% Existing process with the listening socket ...
l([{{?MODULE, listener, {_, AS}}, LPid}], _, _) ->
{LAs, _Sock} = AS,
{LPid, LAs};
%% ... or not: start one.
l([], LRef, T) ->
{ok, LPid, LAs} = diameter_sctp_sup:start_child({listen, LRef, T}),
{LPid, LAs}.
%% open/3
open(Addrs, Opts, PortNr) ->
{LAs, Os} = addrs(Addrs, Opts),
{LAs, case gen_sctp:open(gen_opts(portnr(Os, PortNr))) of
{ok, Sock} ->
Sock;
{error, Reason} ->
x({open, Reason})
end}.
addrs(Addrs, Opts) ->
case proplists:split(Opts, [ip]) of
{[[]], _} ->
{Addrs, Opts ++ [{ip, A} || A <- Addrs]};
{[As], Os} ->
LAs = [diameter_lib:ipaddr(A) || {ip, A} <- As],
{LAs, Os ++ [{ip, A} || A <- LAs]}
end.
portnr(Opts, PortNr) ->
case proplists:get_value(port, Opts) of
undefined ->
[{port, PortNr} | Opts];
_ ->
Opts
end.
%% x/1
x(Reason) ->
exit({shutdown, Reason}).
%% gen_opts/1
gen_opts(Opts) ->
{L,_} = proplists:split(Opts, [binary, list, mode, active, sctp_events]),
[[],[],[],[],[]] == L orelse ?ERROR({reserved_options, Opts}),
[binary, {active, once} | Opts].
%% ---------------------------------------------------------------------------
%% # handle_call/3
%% ---------------------------------------------------------------------------
handle_call({{accept, Ref}, Pid}, _, #listener{ref = Ref,
count = N}
= S) ->
{TPid, NewS} = accept(Pid, S),
{reply, {ok, TPid}, NewS#listener{count = N+1}};
handle_call(_, _, State) ->
{reply, nok, State}.
%% ---------------------------------------------------------------------------
%% # handle_cast/2
%% ---------------------------------------------------------------------------
handle_cast(_, State) ->
{noreply, State}.
%% ---------------------------------------------------------------------------
%% # handle_info/2
%% ---------------------------------------------------------------------------
handle_info(T, #transport{} = S) ->
{noreply, #transport{} = t(T,S)};
handle_info(T, #listener{} = S) ->
{noreply, #listener{} = l(T,S)}.
%% ---------------------------------------------------------------------------
%% # code_change/3
%% ---------------------------------------------------------------------------
code_change(_, State, _) ->
{ok, State}.
%% ---------------------------------------------------------------------------
%% # terminate/2
%% ---------------------------------------------------------------------------
terminate(_, #transport{assoc_id = undefined}) ->
ok;
terminate(_, #transport{socket = Sock,
mode = {accept, _},
assoc_id = Id}) ->
close(Sock, Id);
terminate(_, #transport{socket = Sock}) ->
gen_sctp:close(Sock);
terminate(_, #listener{socket = Sock}) ->
gen_sctp:close(Sock).
%% ---------------------------------------------------------------------------
%% start_timer/1
start_timer(#listener{count = 0} = S) ->
S#listener{tref = erlang:start_timer(?LISTENER_TIMEOUT, self(), close)};
start_timer(S) ->
S.
%% l/2
%%
%% Transition listener state.
%% Incoming message from SCTP.
l({sctp, Sock, _RA, _RP, Data} = Msg, #listener{socket = Sock} = S) ->
setopts(Sock),
case find(Data, S) of
{TPid, NewS} ->
TPid ! Msg,
NewS;
false ->
S
end;
%% Transport is asking message to be sent. See send/3 for why the send
%% isn't directly from the transport.
l({send, AssocId, StreamId, Bin}, #listener{socket = Sock} = S) ->
send(Sock, AssocId, StreamId, Bin),
S;
%% Accepting transport has died. One that's awaiting an association ...
l({'DOWN', MRef, process, TPid, _}, #listener{pending = [TPid | Q],
tmap = T,
count = N}
= S) ->
ets:delete(T, MRef),
ets:delete(T, TPid),
start_timer(S#listener{count = N-1,
pending = Q});
%% ... ditto and a new transport has already been started ...
l({'DOWN', _, process, _, _} = T, #listener{pending = [TPid | Q]}
= S) ->
#listener{pending = NQ}
= NewS
= l(T, S#listener{pending = Q}),
NewS#listener{pending = [TPid | NQ]};
%% ... or not.
l({'DOWN', MRef, process, TPid, _}, #listener{socket = Sock,
tmap = T,
count = N,
pending = {P,Q}}
= S) ->
[{MRef, Id}] = ets:lookup(T, MRef), %% Id = TPid | AssocId
ets:delete(T, MRef),
ets:delete(T, Id),
Id == TPid orelse close(Sock, Id),
case ets:lookup(Q, TPid) of
[{TPid, _}] -> %% transport in the pending queue ...
ets:delete(Q, TPid),
S#listener{pending = {P-1, Q}};
[] -> %% ... or not
start_timer(S#listener{count = N-1})
end;
%% Timeout after the last accepting process has died.
l({timeout, TRef, close = T}, #listener{tref = TRef,
count = 0}) ->
x(T);
l({timeout, _, close}, #listener{} = S) ->
S.
%% t/2
%%
%% Transition transport state.
t(T,S) ->
case transition(T,S) of
ok ->
S;
#transport{} = NS ->
NS;
stop ->
x(T)
end.
%% transition/2
%% Incoming message.
transition({sctp, Sock, _RA, _RP, Data}, #transport{socket = Sock,
mode = {accept, _}}
= S) ->
recv(Data, S);
transition({sctp, Sock, _RA, _RP, Data}, #transport{socket = Sock} = S) ->
setopts(Sock),
recv(Data, S);
%% Outgoing message.
transition({diameter, {send, Msg}}, S) ->
send(Msg, S);
%% Request to close the transport connection.
transition({diameter, {close, Pid}}, #transport{parent = Pid}) ->
stop;
%% TLS over SCTP is described in RFC 3436 but has limitations as
%% described in RFC 6083. The latter describes DTLS over SCTP, which
%% addresses these limitations, DTLS itself being described in RFC
%% 4347. TLS is primarily used over TCP, which the current RFC 3588
%% draft acknowledges by equating TLS with TLS/TCP and DTLS/SCTP.
transition({diameter, {tls, _Ref, _Type, _Bool}}, _) ->
stop;
%% Listener process has died.
transition({'DOWN', _, process, Pid, _}, #transport{mode = {accept, Pid}}) ->
stop;
%% Parent process has died.
transition({'DOWN', _, process, Pid, _}, #transport{parent = Pid}) ->
stop.
%% Crash on anything unexpected.
%% accept/2
%%
%% Start a new transport process or use one that's already been
%% started as a consequence of association establishment.
%% No pending associations: spawn a new transport.
accept(Pid, #listener{socket = Sock,
tmap = T,
pending = {0,_} = Q}
= S) ->
Arg = {accept, Pid, self(), Sock},
{ok, TPid} = diameter_sctp_sup:start_child(Arg),
MRef = erlang:monitor(process, TPid),
ets:insert(T, [{MRef, TPid}, {TPid, MRef}]),
{TPid, S#listener{pending = [TPid | Q]}};
%% Placing the transport in the pending field makes it available to
%% the next association. The stack starts a new accepting transport
%% only after this one brings the connection up (or dies).
%% Accepting transport has died. This can happen if a new transport is
%% started before the DOWN has arrived.
accept(Pid, #listener{pending = [TPid | {0,_} = Q]} = S) ->
false = is_process_alive(TPid), %% assert
accept(Pid, S#listener{pending = Q});
%% Pending associations: attach to the first in the queue.
accept(Pid, #listener{ref = Ref, pending = {N,Q}} = S) ->
TPid = ets:first(Q),
TPid ! {Ref, Pid},
ets:delete(Q, TPid),
{TPid, S#listener{pending = {N-1, Q}}}.
%% send/2
%% Outbound Diameter message on a specified stream ...
send(#diameter_packet{bin = Bin, transport_data = {stream, SId}}, S) ->
send(SId, Bin, S),
S;
%% ... or not: rotate through all steams.
send(Bin, #transport{streams = {_, OS},
os = N}
= S)
when is_binary(Bin) ->
send(N, Bin, S),
S#transport{os = (N + 1) rem OS}.
%% send/3
%% Messages have to be sent from the controlling process, which is
%% probably a bug. Sending from here causes an inet_reply, Sock,
%% Status} message to be sent to the controlling process while
%% gen_sctp:send/4 here hangs.
send(StreamId, Bin, #transport{assoc_id = AId,
mode = {accept, LPid}}) ->
LPid ! {send, AId, StreamId, Bin};
send(StreamId, Bin, #transport{socket = Sock,
assoc_id = AId}) ->
send(Sock, AId, StreamId, Bin).
%% send/4
send(Sock, AssocId, Stream, Bin) ->
case gen_sctp:send(Sock, AssocId, Stream, Bin) of
ok ->
ok;
{error, Reason} ->
x({send, Reason})
end.
%% recv/2
%% Association established ...
recv({[], #sctp_assoc_change{state = comm_up,
outbound_streams = OS,
inbound_streams = IS,
assoc_id = Id}},
#transport{assoc_id = undefined}
= S) ->
up(S#transport{assoc_id = Id,
streams = {IS, OS}});
%% ... or not: try the next address.
recv({[], #sctp_assoc_change{} = E},
#transport{assoc_id = undefined,
socket = Sock,
mode = {connect = C, {[RA|RAs], RP, Es}}}
= S) ->
S#transport{mode = {C, connect(Sock, RAs, RP, [{RA,E} | Es])}};
%% Lost association after establishment.
recv({[], #sctp_assoc_change{}}, _) ->
stop;
%% Inbound Diameter message.
recv({[#sctp_sndrcvinfo{stream = Id}], Bin}, #transport{parent = Pid})
when is_binary(Bin) ->
diameter_peer:recv(Pid, #diameter_packet{transport_data = {stream, Id},
bin = Bin}),
ok;
recv({[], #sctp_shutdown_event{assoc_id = Id}},
#transport{assoc_id = Id}) ->
stop;
%% Note that diameter_sctp(3) documents that sctp_events cannot be
%% specified in the list of options passed to gen_sctp and that
%% gen_opts/1 guards against this. This is to ensure that we know what
%% events to expect and also to ensure that we receive
%% #sctp_sndrcvinfo{} with each incoming message (data_io_event =
%% true). Adaptation layer events (ie. #sctp_adaptation_event{}) are
%% disabled by default so don't handle it. We could simply disable
%% events we don't react to but don't.
recv({[], #sctp_paddr_change{}}, _) ->
ok;
recv({[], #sctp_pdapi_event{}}, _) ->
ok.
%% up/1
up(#transport{parent = Pid,
mode = {connect = C, {[RA | _], RP, _}}}
= S) ->
diameter_peer:up(Pid, {RA,RP}),
S#transport{mode = C};
up(#transport{parent = Pid,
mode = {accept, _}}
= S) ->
diameter_peer:up(Pid),
S.
%% find/2
find({[#sctp_sndrcvinfo{assoc_id = Id}], _}
= Data,
#listener{tmap = T}
= S) ->
f(ets:lookup(T, Id), Data, S);
find({_, Rec} = Data, #listener{tmap = T} = S) ->
f(ets:lookup(T, assoc_id(Rec)), Data, S).
%% New association and a transport waiting for one: use it.
f([],
{_, #sctp_assoc_change{state = comm_up,
assoc_id = Id}},
#listener{tmap = T,
pending = [TPid | {_,_} = Q]}
= S) ->
[{TPid, MRef}] = ets:lookup(T, TPid),
ets:insert(T, [{MRef, Id}, {Id, TPid}]),
ets:delete(T, TPid),
{TPid, S#listener{pending = Q}};
%% New association and no transport start yet: spawn one and place it
%% in the queue.
f([],
{_, #sctp_assoc_change{state = comm_up,
assoc_id = Id}},
#listener{ref = Ref,
socket = Sock,
tmap = T,
pending = {N,Q}}
= S) ->
Arg = {accept, Ref, self(), Sock, Id},
{ok, TPid} = diameter_sctp_sup:start_child(Arg),
MRef = erlang:monitor(process, TPid),
ets:insert(T, [{MRef, Id}, {Id, TPid}]),
ets:insert(Q, {TPid, now()}),
{TPid, S#listener{pending = {N+1, Q}}};
%% Known association ...
f([{_, TPid}], _, S) ->
{TPid, S};
%% ... or not: discard.
f([], _, _) ->
false.
%% assoc_id/1
assoc_id(#sctp_shutdown_event{assoc_id = Id}) ->
Id;
assoc_id(#sctp_assoc_change{assoc_id = Id}) ->
Id;
assoc_id(#sctp_sndrcvinfo{assoc_id = Id}) ->
Id;
assoc_id(#sctp_paddr_change{assoc_id = Id}) ->
Id;
assoc_id(#sctp_adaptation_event{assoc_id = Id}) ->
Id.
%% connect/4
connect(_, [], _, Reasons) ->
x({connect, lists:reverse(Reasons)});
connect(Sock, [Addr | AT] = As, Port, Reasons) ->
case gen_sctp:connect_init(Sock, Addr, Port, []) of
ok ->
{As, Port, Reasons};
{error, _} = E ->
connect(Sock, AT, Port, [{Addr, E} | Reasons])
end.
%% setopts/1
setopts(Sock) ->
case inet:setopts(Sock, [{active, once}]) of
ok -> ok;
X -> x({setopts, Sock, X}) %% possibly on peer disconnect
end.
