%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2013. 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%
%%
%%
%% Some gen_sctp-specific tests demonstrating problems that were
%% encountered during diameter development but have nothing
%% specifically to do with diameter. At least one of them can cause
%% diameter_transport_SUITE testcases to fail.
%%
-module(diameter_gen_sctp_SUITE).
-export([suite/0,
all/0,
init_per_suite/1,
end_per_suite/1]).
%% testcases
-export([send_not_from_controlling_process/1,
send_from_multiple_clients/1,
receive_what_was_sent/1]).
-include_lib("kernel/include/inet_sctp.hrl").
%% Message from gen_sctp are of this form.
-define(SCTP(Sock, Data), {sctp, Sock, _, _, Data}).
%% Open sockets on the loopback address.
-define(ADDR, {127,0,0,1}).
%% Snooze, nap, siesta.
-define(SLEEP(T), receive after T -> ok end).
%% An indescribably long number of milliseconds after which everthing
%% that should have happened has.
-define(FOREVER, 2000).
%% The first byte in each message we send as a simple guard against
%% not receiving what was sent.
-define(MAGIC, 42).
%% ===========================================================================
suite() ->
[{timetrap, {minutes, 2}}].
all() ->
[send_not_from_controlling_process,
send_from_multiple_clients,
receive_what_was_sent].
init_per_suite(Config) ->
case gen_sctp:open() of
{ok, Sock} ->
gen_sctp:close(Sock),
Config;
{error, E} when E == eprotonosupport;
E == esocktnosupport ->
{skip, no_sctp}
end.
end_per_suite(_Config) ->
ok.
%% ===========================================================================
%% send_not_from_controlling_process/1
%%
%% This testcase failing shows gen_sctp:send/4 hanging when called
%% outside the controlling process of the socket in question.
send_not_from_controlling_process(_) ->
Pids = send_not_from_controlling_process(),
?SLEEP(?FOREVER),
try
[] = [{P,I} || P <- Pids, I <- [process_info(P)], I /= undefined]
after
lists:foreach(fun(P) -> exit(P, kill) end, Pids)
end.
%% send_not_from_controlling_process/0
%%
%% Returns the pids of three spawned processes: a listening process, a
%% connecting process and a sending process.
%%
%% The expected behaviour is that all three processes exit:
%%
%% - The listening process exits upon receiving an SCTP message
%% sent by the sending process.
%% - The connecting process exits upon listening process exit.
%% - The sending process exits upon gen_sctp:send/4 return.
%%
%% The observed behaviour is that all three processes remain alive
%% indefinitely:
%%
%% - The listening process never receives the SCTP message sent
%% by the sending process.
%% - The connecting process has an inet_reply message in its mailbox
%% as a consequence of the call to gen_sctp:send/4 call from the
%% sending process.
%% - The call to gen_sctp:send/4 in the sending process doesn't return,
%% hanging in prim_inet:getopts/2.
send_not_from_controlling_process() ->
FPid = self(),
{L, MRef} = spawn_monitor(fun() -> listen(FPid) end),%% listening process
receive
{?MODULE, C, S} ->
erlang:demonitor(MRef, [flush]),
[L,C,S];
{'DOWN', MRef, process, _, _} = T ->
error(T)
end.
%% listen/1
listen(FPid) ->
{ok, Sock} = open(),
ok = gen_sctp:listen(Sock, true),
{ok, PortNr} = inet:port(Sock),
LPid = self(),
spawn(fun() -> connect1(PortNr, FPid, LPid) end), %% connecting process
Id = assoc(Sock),
?SCTP(Sock, {[#sctp_sndrcvinfo{assoc_id = Id}], _Bin})
= recv(). %% Waits with this as current_function.
%% recv/0
recv() ->
receive T -> T end.
%% connect1/3
connect1(PortNr, FPid, LPid) ->
{ok, Sock} = open(),
ok = gen_sctp:connect_init(Sock, ?ADDR, PortNr, []),
Id = assoc(Sock),
FPid ! {?MODULE,
self(),
spawn(fun() -> send(Sock, Id) end)}, %% sending process
MRef = erlang:monitor(process, LPid),
down(MRef). %% Waits with this as current_function.
%% down/1
down(MRef) ->
receive {'DOWN', MRef, process, _, Reason} -> Reason end.
%% send/2
send(Sock, Id) ->
ok = gen_sctp:send(Sock, Id, 0, <<0:32>>).
%% ===========================================================================
%% send_from_multiple_clients/0
%%
%% Demonstrates sluggish delivery of messages.
send_from_multiple_clients(_) ->
{S, Rs} = T = send_from_multiple_clients(8, 1024),
Max = ?FOREVER*1000,
{false, [], _} = {Max < S,
Rs -- [OI || {O,_} = OI <- Rs, is_integer(O)],
T}.
%% send_from_multiple_clients/2
%%
%% Opens a listening socket and then spawns a specified number of
%% processes, each of which connects to the listening socket. Each
%% connecting process then sends a message, whose size in bytes is
%% passed as an argument, the listening process sends a reply
%% containing the time at which the message was received, and the
%% connecting process then exits upon reception of this reply.
%%
%% Returns the elapsed time for all connecting process to exit
%% together with a list of exit reasons for the connecting processes.
%% In the successful case a connecting process exits with the
%% outbound/inbound transit times for the sent/received message as
%% reason.
%%
%% The observed behaviour is that some outbound messages (that is,
%% from a connecting process to the listening process) can take an
%% unexpectedly long time to complete their journey. The more
%% connecting processes, the longer the possible delay it seems.
%%
%% eg. (With F = fun send_from_multiple_clients/2.)
%%
%% 5> F(2, 1024).
%% {875,[{128,116},{113,139}]}
%% 6> F(4, 1024).
%% {2995290,[{2994022,250},{2994071,80},{200,130},{211,113}]}
%% 7> F(8, 1024).
%% {8997461,[{8996161,116},
%% {2996471,86},
%% {2996278,116},
%% {2996360,95},
%% {246,112},
%% {213,159},
%% {373,173},
%% {376,118}]}
%% 8> F(8, 1024).
%% {21001891,[{20999968,128},
%% {8997891,172},
%% {8997927,91},
%% {2995716,164},
%% {2995860,87},
%% {134,100},
%% {117,98},
%% {149,125}]}
%%
%% This turns out to have been due to SCTP resends as a consequence of
%% the listener having an insufficient recbuf. Increasing the size
%% solves the problem.
%%
send_from_multiple_clients(N, Sz)
when is_integer(N), 0 < N, is_integer(Sz), 0 < Sz ->
timer:tc(fun listen/2, [N, <<?MAGIC, 0:Sz/unit:8>>]).
%% listen/2
listen(N, Bin) ->
{ok, Sock} = open(),
ok = gen_sctp:listen(Sock, true),
{ok, PortNr} = inet:port(Sock),
%% Spawn a middleman that in turn spawns N connecting processes,
%% collects a list of exit reasons and then exits with the list as
%% reason. loop/3 returns when we receive this list from the
%% middleman's 'DOWN'.
Self = self(),
Fun = fun() -> exit(connect2(Self, PortNr, Bin)) end,
{_, MRef} = spawn_monitor(fun() -> exit(fold(N, Fun)) end),
loop(Sock, MRef, Bin).
%% fold/2
%%
%% Spawn N processes and collect their exit reasons in a list.
fold(N, Fun) ->
start(N, Fun),
acc(N, []).
start(0, _) ->
ok;
start(N, Fun) ->
spawn_monitor(Fun),
start(N-1, Fun).
acc(0, Acc) ->
Acc;
acc(N, Acc) ->
receive
{'DOWN', _MRef, process, _, RC} ->
acc(N-1, [RC | Acc])
end.
%% loop/3
loop(Sock, MRef, Bin) ->
receive
?SCTP(Sock, {[#sctp_sndrcvinfo{assoc_id = Id}], B}) ->
Sz = size(Bin),
{Sz, Bin} = {size(B), B}, %% assert
ok = send(Sock, Id, mark(Bin)),
loop(Sock, MRef, Bin);
?SCTP(Sock, _) ->
loop(Sock, MRef, Bin);
{'DOWN', MRef, process, _, Reason} ->
Reason
end.
%% connect2/3
connect2(Pid, PortNr, Bin) ->
erlang:monitor(process, Pid),
{ok, Sock} = open(),
ok = gen_sctp:connect_init(Sock, ?ADDR, PortNr, []),
Id = assoc(Sock),
%% T1 = time before send
%% T2 = time after listening process received our message
%% T3 = time after reply is received
T1 = now(),
ok = send(Sock, Id, Bin),
T2 = unmark(recv(Sock, Id)),
T3 = now(),
{timer:now_diff(T2, T1), timer:now_diff(T3, T2)}. %% {Outbound, Inbound}
%% recv/2
recv(Sock, Id) ->
receive
?SCTP(Sock, {[#sctp_sndrcvinfo{assoc_id = Id}], Bin}) ->
Bin;
T -> %% eg. 'DOWN'
exit(T)
end.
%% send/3
send(Sock, Id, Bin) ->
gen_sctp:send(Sock, Id, 0, Bin).
%% mark/1
mark(Bin) ->
Info = term_to_binary(now()),
<<Info/binary, Bin/binary>>.
%% unmark/1
unmark(Bin) ->
{_,_,_} = binary_to_term(Bin).
%% ===========================================================================
%% receive_what_was_sent/1
%%
%% Demonstrates reception of a message that differs from that sent.
receive_what_was_sent(_Config) ->
send_from_multiple_clients(1, 1024*32). %% fails
%% ===========================================================================
%% open/0
open() ->
open([]).
%% open/1
open(Opts) ->
gen_sctp:open([{ip, ?ADDR}, {port, 0}, {active, true}, binary,
{recbuf, 1 bsl 16}, {sndbuf, 1 bsl 16}
| Opts]).
%% assoc/1
assoc(Sock) ->
receive
?SCTP(Sock, {[], #sctp_assoc_change{state = S,
assoc_id = Id}}) ->
comm_up = S, %% assert
Id
end.
