%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1999-2011. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(erl_distribution_wb_SUITE).
-include_lib("common_test/include/ct.hrl").
-include_lib("kernel/include/inet.hrl").
-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1,
init_per_group/2,end_per_group/2]).
-export([init_per_testcase/2, end_per_testcase/2, whitebox/1,
switch_options/1, missing_compulsory_dflags/1]).
%% 1)
%%
%% Connections are now always set up symetrically with respect to
%% publication. If connecting node doesn't send DFLAG_PUBLISHED
%% the other node wont send DFLAG_PUBLISHED. If the connecting
%% node send DFLAG_PUBLISHED but the other node doesn't send
%% DFLAG_PUBLISHED, the connecting node should consider its
%% DFLAG_PUBLISHED as dropped, i.e the connecting node wont be
%% published on the other node.
-define(to_port(Socket, Data),
case inet_tcp:send(Socket, Data) of
{error, closed} ->
self() ! {tcp_closed, Socket},
{error, closed};
R ->
R
end).
-define(DFLAG_PUBLISHED,1).
-define(DFLAG_ATOM_CACHE,2).
-define(DFLAG_EXTENDED_REFERENCES,4).
-define(DFLAG_DIST_MONITOR,8).
-define(DFLAG_FUN_TAGS,16#10).
-define(DFLAG_DIST_MONITOR_NAME,16#20).
-define(DFLAG_HIDDEN_ATOM_CACHE,16#40).
-define(DFLAG_NEW_FUN_TAGS,16#80).
-define(DFLAG_EXTENDED_PIDS_PORTS,16#100).
%% From R9 and forward extended references is compulsory
%% From R10 and forward extended pids and ports are compulsory
-define(COMPULSORY_DFLAGS, (?DFLAG_EXTENDED_REFERENCES bor ?DFLAG_EXTENDED_PIDS_PORTS)).
-define(shutdown(X), exit(X)).
-define(int16(X), [((X) bsr 8) band 16#ff, (X) band 16#ff]).
-define(int32(X),
[((X) bsr 24) band 16#ff, ((X) bsr 16) band 16#ff,
((X) bsr 8) band 16#ff, (X) band 16#ff]).
-define(i16(X1,X0),
(?u16(X1,X0) -
(if (X1) > 127 -> 16#10000; true -> 0 end))).
-define(u16(X1,X0),
(((X1) bsl 8) bor (X0))).
-define(u32(X3,X2,X1,X0),
(((X3) bsl 24) bor ((X2) bsl 16) bor ((X1) bsl 8) bor (X0))).
suite() -> [{ct_hooks,[ts_install_cth]}].
all() ->
[whitebox, switch_options, missing_compulsory_dflags].
groups() ->
[].
init_per_suite(Config) ->
Config.
end_per_suite(_Config) ->
ok.
init_per_group(_GroupName, Config) ->
Config.
end_per_group(_GroupName, Config) ->
Config.
init_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
Dog=?t:timetrap(?t:minutes(1)),
[{watchdog, Dog}|Config].
end_per_testcase(_Func, Config) ->
Dog=?config(watchdog, Config),
?t:timetrap_cancel(Dog).
switch_options(doc) ->
["Tests switching of options for the tcp port, as this is done"
" when the distribution port is to be shortcut into the emulator."
" Maybe this should be in the inet test suite, but only the distribution"
" does such horrible things..."];
switch_options(Config) when is_list(Config) ->
ok = test_switch_active(),
ok = test_switch_active_partial() ,
ok = test_switch_active_and_packet(),
ok.
whitebox(doc) ->
["Whitebox testing of distribution handshakes. Tests both BC with R5 and "
"the md5 version. Note that after R6B, this should be revised to "
"remove BC code."];
whitebox(Config) when is_list(Config) ->
?line {ok, Node} = start_node(?MODULE,""),
?line Cookie = erlang:get_cookie(),
?line {_,Host} = split(node()),
?line ok = pending_up_md5(Node, join(ccc,Host), Cookie),
?line ok = simultaneous_md5(Node, join('A',Host), Cookie),
?line ok = simultaneous_md5(Node, join(zzzzzzzzzzzzzz,Host), Cookie),
?line stop_node(Node),
ok.
%%
%% The actual tests
%%
%%
%% Switch tcp options test
%%
test_switch_active() ->
?line {Client, Server} = socket_pair(0, 4),
?line ok = write_packets_32(Client, 1, 5),
receive after 2000 -> ok end,
?line ok = read_packets(Server, 1, 1),
receive after 2000 -> ok end,
?line ok = read_packets(Server, 2, 2),
?line inet:setopts(Server, [{active, true}]),
?line ok = receive_packets(Server, 3, 5),
close_pair({Client, Server}),
ok.
test_switch_active_partial() ->
?line {Client, Server} = socket_pair(0, 4),
?line ok = write_packets_32(Client, 1, 2),
?line ok = gen_tcp:send(Client,[?int32(4), [0,0,0]]),
receive after 2000 -> ok end,
?line ok = read_packets(Server, 1, 1),
receive after 2000 -> ok end,
?line ok = read_packets(Server, 2, 2),
?line inet:setopts(Server, [{active, true}]),
?line ok = gen_tcp:send(Client,[3]),
?line ok = write_packets_32(Client, 4, 5),
?line ok = receive_packets(Server, 3, 5),
close_pair({Client, Server}),
ok.
do_test_switch_active_and_packet(SendBefore, SendAfter) ->
?line {Client, Server} = socket_pair(0, 2),
?line ok = write_packets_16(Client, 1, 2),
?line ok = gen_tcp:send(Client,SendBefore),
receive after 2000 -> ok end,
?line ok = read_packets(Server, 1, 1),
receive after 2000 -> ok end,
?line ok = read_packets(Server, 2, 2),
?line inet:setopts(Server, [{packet,4}, {active, true}]),
?line ok = gen_tcp:send(Client,SendAfter),
?line ok = write_packets_32(Client, 4, 5),
?line ok = receive_packets(Server, 3, 5),
close_pair({Client, Server}),
ok.
test_switch_active_and_packet() ->
?line ok = do_test_switch_active_and_packet([0],[0,0,4,0,0,0,3]),
?line ok = do_test_switch_active_and_packet([0,0],[0,4,0,0,0,3]),
?line ok = do_test_switch_active_and_packet([0,0,0],[4,0,0,0,3]),
?line ok = do_test_switch_active_and_packet([0,0,0,4],[0,0,0,3]),
?line ok = do_test_switch_active_and_packet([0,0,0,4,0],[0,0,3]),
?line ok = do_test_switch_active_and_packet([0,0,0,4,0,0],[0,3]),
?line ok = do_test_switch_active_and_packet([0,0,0,4,0,0,0],[3]),
?line ok = do_test_switch_active_and_packet([0,0,0,4,0,0,0,3],[]),
ok.
%%
%% Handshake tests
%%
pending_up_md5(Node,OurName,Cookie) ->
?line {NA,NB} = split(Node),
?line {port,PortNo,_} = erl_epmd:port_please(NA,NB),
?line {ok, SocketA} = gen_tcp:connect(atom_to_list(NB),PortNo,
[{active,false},
{packet,2}]),
?line send_name(SocketA,OurName,5),
?line ok = recv_status(SocketA),
?line {hidden,Node,5,HisChallengeA} = recv_challenge(SocketA), % See 1)
?line OurChallengeA = gen_challenge(),
?line OurDigestA = gen_digest(HisChallengeA, Cookie),
?line send_challenge_reply(SocketA, OurChallengeA, OurDigestA),
?line ok = recv_challenge_ack(SocketA, OurChallengeA, Cookie),
%%%
%%% OK, one connection is up, now lets be nasty and try another up:
%%%
%%% But wait for a while, the other node might not have done setnode
%%% just yet...
?line receive after 1000 -> ok end,
?line {ok, SocketB} = gen_tcp:connect(atom_to_list(NB),PortNo,
[{active,false},
{packet,2}]),
?line send_name(SocketB,OurName,5),
?line alive = recv_status(SocketB),
?line send_status(SocketB, true),
?line gen_tcp:close(SocketA),
?line {hidden,Node,5,HisChallengeB} = recv_challenge(SocketB), % See 1)
?line OurChallengeB = gen_challenge(),
?line OurDigestB = gen_digest(HisChallengeB, Cookie),
?line send_challenge_reply(SocketB, OurChallengeB, OurDigestB),
?line ok = recv_challenge_ack(SocketB, OurChallengeB, Cookie),
%%%
%%% Well, are we happy?
%%%
?line inet:setopts(SocketB, [{active, false},
{packet, 4}]),
?line gen_tcp:send(SocketB,build_rex_message('',OurName)),
?line {Header, Message} = recv_message(SocketB),
?line io:format("Received header ~p, data ~p.~n",
[Header, Message]),
?line gen_tcp:close(SocketB),
ok.
simultaneous_md5(Node, OurName, Cookie) when OurName < Node ->
?line pong = net_adm:ping(Node),
?line LSocket = case gen_tcp:listen(0, [{active, false}, {packet,2}]) of
{ok, Socket} ->
Socket;
Else ->
exit(Else)
end,
?line EpmdSocket = register(OurName, LSocket, 1, 5),
?line {NA, NB} = split(Node),
?line rpc:cast(Node, net_adm, ping, [OurName]),
?line receive after 1000 -> ok end,
?line {port, PortNo, _} = erl_epmd:port_please(NA,NB),
?line {ok, SocketA} = gen_tcp:connect(atom_to_list(NB),PortNo,
[{active,false},
{packet,2}]),
?line send_name(SocketA,OurName,5),
%% We are still not marked up on the other side, as our first message
%% is not sent.
?line SocketB = case gen_tcp:accept(LSocket) of
{ok, Socket1} ->
?line Socket1;
Else2 ->
?line exit(Else2)
end,
?line nok = recv_status(SocketA),
% Now we are expected to close A
?line gen_tcp:close(SocketA),
% But still Socket B will continue
?line {normal,Node,5} = recv_name(SocketB), % See 1)
?line send_status(SocketB, ok_simultaneous),
?line MyChallengeB = gen_challenge(),
?line send_challenge(SocketB, OurName, MyChallengeB,5),
?line HisChallengeB = recv_challenge_reply(SocketB, MyChallengeB, Cookie),
?line DigestB = gen_digest(HisChallengeB,Cookie),
?line send_challenge_ack(SocketB, DigestB),
?line inet:setopts(SocketB, [{active, false},
{packet, 4}]),
% This should be the ping message.
?line {Header, Message} = recv_message(SocketB),
?line io:format("Received header ~p, data ~p.~n",
[Header, Message]),
?line gen_tcp:close(SocketB),
?line gen_tcp:close(LSocket),
?line gen_tcp:close(EpmdSocket),
ok;
simultaneous_md5(Node, OurName, Cookie) when OurName > Node ->
?line pong = net_adm:ping(Node),
?line LSocket = case gen_tcp:listen(0, [{active, false}, {packet,2}]) of
{ok, Socket} ->
?line Socket;
Else ->
?line exit(Else)
end,
?line EpmdSocket = register(OurName, LSocket, 1, 5),
?line {NA, NB} = split(Node),
?line rpc:cast(Node, net_adm, ping, [OurName]),
?line receive after 1000 -> ok end,
?line {port, PortNo, _} = erl_epmd:port_please(NA,NB),
?line {ok, SocketA} = gen_tcp:connect(atom_to_list(NB),PortNo,
[{active,false},
{packet,2}]),
?line SocketB = case gen_tcp:accept(LSocket) of
{ok, Socket1} ->
?line Socket1;
Else2 ->
?line exit(Else2)
end,
?line send_name(SocketA,OurName,5),
?line ok_simultaneous = recv_status(SocketA),
%% Socket B should die during this
?line case catch begin
?line {normal,Node,5} = recv_name(SocketB), % See 1)
?line send_status(SocketB, ok_simultaneous),
?line MyChallengeB = gen_challenge(),
?line send_challenge(SocketB, OurName, MyChallengeB,
5),
?line HisChallengeB = recv_challenge_reply(
SocketB,
MyChallengeB,
Cookie),
?line DigestB = gen_digest(HisChallengeB,Cookie),
?line send_challenge_ack(SocketB, DigestB),
?line inet:setopts(SocketB, [{active, false},
{packet, 4}]),
?line {HeaderB, MessageB} = recv_message(SocketB),
?line io:format("Received header ~p, data ~p.~n",
[HeaderB, MessageB])
end of
{'EXIT', Exitcode} ->
?line io:format("Expected exitsignal caught: ~p.~n",
[Exitcode]);
Success ->
?line io:format("Unexpected success: ~p~n",
[Success]),
?line exit(unexpected_success)
end,
?line gen_tcp:close(SocketB),
%% But still Socket A will continue
?line {hidden,Node,5,HisChallengeA} = recv_challenge(SocketA), % See 1)
?line OurChallengeA = gen_challenge(),
?line OurDigestA = gen_digest(HisChallengeA, Cookie),
?line send_challenge_reply(SocketA, OurChallengeA, OurDigestA),
?line ok = recv_challenge_ack(SocketA, OurChallengeA, Cookie),
?line inet:setopts(SocketA, [{active, false},
{packet, 4}]),
?line gen_tcp:send(SocketA,build_rex_message('',OurName)),
?line {Header, Message} = recv_message(SocketA),
?line io:format("Received header ~p, data ~p.~n",
[Header, Message]),
?line gen_tcp:close(SocketA),
?line gen_tcp:close(LSocket),
?line gen_tcp:close(EpmdSocket),
ok.
missing_compulsory_dflags(doc) -> [];
missing_compulsory_dflags(Config) when is_list(Config) ->
?line [Name1, Name2] = get_nodenames(2, missing_compulsory_dflags),
?line {ok, Node} = start_node(Name1,""),
?line {NA,NB} = split(Node),
?line {port,PortNo,_} = erl_epmd:port_please(NA,NB),
?line {ok, SocketA} = gen_tcp:connect(atom_to_list(NB),PortNo,
[{active,false},
{packet,2}]),
?line BadNode = list_to_atom(atom_to_list(Name2)++"@"++atom_to_list(NB)),
?line send_name(SocketA,BadNode,5,0),
?line not_allowed = recv_status(SocketA),
?line gen_tcp:close(SocketA),
?line stop_node(Node),
?line ok.
%%
%% Here comes the utilities
%%
%%
%% Switch option utilities
%%
write_packets_32(_, M, N) when M > N ->
ok;
write_packets_32(Sock, M, N) ->
ok = gen_tcp:send(Sock,[?int32(4), ?int32(M)]),
write_packets_32(Sock, M+1, N).
write_packets_16(_, M, N) when M > N ->
ok;
write_packets_16(Sock, M, N) ->
ok = gen_tcp:send(Sock,[?int16(4), ?int32(M)]),
write_packets_16(Sock, M+1, N).
read_packets(_, M, N) when M > N ->
ok;
read_packets(Sock, M, N) ->
Expected = ?int32(M),
case gen_tcp:recv(Sock, 0) of
{ok, Expected} ->
read_packets(Sock, M+1, N);
{ok, Unexpected} ->
exit({unexpected_data_read, Unexpected});
Error ->
exit({error_read, Error})
end.
receive_packets(Sock, M, N) when M > N ->
receive
{tcp, Sock, Data} ->
exit({extra_data, Data})
after 0 ->
ok
end;
receive_packets(Sock, M, N) ->
Expect = ?int32(M),
receive
{tcp, Sock, Expect} ->
receive_packets(Sock, M+1, N);
{tcp, Sock, Unexpected} ->
exit({unexpected_data_received, Unexpected})
after 500 ->
exit({no_data_received_for,M})
end.
socket_pair(ClientPack, ServerPack) ->
{ok, Listen} = gen_tcp:listen(0, [{active, false},
{packet, ServerPack}]),
{ok, Host} = inet:gethostname(),
{ok, Port} = inet:port(Listen),
{ok, Client} = gen_tcp:connect(Host, Port, [{active, false},
{packet, ClientPack}]),
{ok, Server} = gen_tcp:accept(Listen),
gen_tcp:close(Listen),
{Client, Server}.
close_pair({Client, Server}) ->
gen_tcp:close(Client),
gen_tcp:close(Server),
ok.
%%
%% Handshake utilities
%%
%%
%% MD5 hashing
%%
gen_challenge() ->
rand:uniform(1000000).
%% Generate a message digest from Challenge number and Cookie
gen_digest(Challenge, Cookie) when is_integer(Challenge), is_atom(Cookie) ->
C0 = erlang:md5_init(),
C1 = erlang:md5_update(C0, atom_to_list(Cookie)),
C2 = erlang:md5_update(C1, integer_to_list(Challenge)),
binary_to_list(erlang:md5_final(C2)).
%%
%% The differrent stages of the MD5 handshake
%%
send_status(Socket, Stat) ->
case gen_tcp:send(Socket, [$s | atom_to_list(Stat)]) of
{error, _} ->
?shutdown(could_not_send_status);
_ ->
true
end.
recv_status(Socket) ->
case gen_tcp:recv(Socket, 0) of
{ok, [$s|StrStat]} ->
list_to_atom(StrStat);
Bad ->
exit(Bad)
end.
send_challenge(Socket, Node, Challenge, Version) ->
send_challenge(Socket, Node, Challenge, Version, ?COMPULSORY_DFLAGS).
send_challenge(Socket, Node, Challenge, Version, Flags) ->
{ok, {{_Ip1,_Ip2,_Ip3,_Ip4}, _}} = inet:sockname(Socket),
?to_port(Socket, [$n,?int16(Version),?int32(Flags),
?int32(Challenge), atom_to_list(Node)]).
recv_challenge(Socket) ->
case gen_tcp:recv(Socket, 0) of
{ok,[$n,V1,V0,Fl1,Fl2,Fl3,Fl4,CA3,CA2,CA1,CA0 | Ns]} ->
Flags = ?u32(Fl1,Fl2,Fl3,Fl4),
Type = case Flags band ?DFLAG_PUBLISHED of
0 ->
hidden;
_ ->
normal
end,
Node =list_to_atom(Ns),
Version = ?u16(V1,V0),
Challenge = ?u32(CA3,CA2,CA1,CA0),
{Type,Node,Version,Challenge};
_ ->
?shutdown(no_node)
end.
send_challenge_reply(Socket, Challenge, Digest) ->
?to_port(Socket, [$r,?int32(Challenge),Digest]).
recv_challenge_reply(Socket, ChallengeA, Cookie) ->
case gen_tcp:recv(Socket, 0) of
{ok,[$r,CB3,CB2,CB1,CB0 | SumB]} when length(SumB) == 16 ->
SumA = gen_digest(ChallengeA, Cookie),
ChallengeB = ?u32(CB3,CB2,CB1,CB0),
if SumB == SumA ->
ChallengeB;
true ->
?shutdown(bad_challenge_reply)
end;
_ ->
?shutdown(no_node)
end.
send_challenge_ack(Socket, Digest) ->
?to_port(Socket, [$a,Digest]).
recv_challenge_ack(Socket, ChallengeB, CookieA) ->
case gen_tcp:recv(Socket, 0) of
{ok,[$a | SumB]} when length(SumB) == 16 ->
SumA = gen_digest(ChallengeB, CookieA),
if SumB == SumA ->
ok;
true ->
?shutdown(bad_challenge_ack)
end;
_ ->
?shutdown(bad_challenge_ack)
end.
send_name(Socket, MyNode0, Version) ->
send_name(Socket, MyNode0, Version, ?COMPULSORY_DFLAGS).
send_name(Socket, MyNode0, Version, Flags) ->
MyNode = atom_to_list(MyNode0),
ok = ?to_port(Socket, [<<$n,Version:16,Flags:32>>|MyNode]).
%%
%% recv_name is common for both old and new handshake.
%%
recv_name(Socket) ->
case gen_tcp:recv(Socket, 0) of
{ok,Data} ->
get_name(Data);
Res ->
?shutdown({no_node,Res})
end.
get_name([$m,VersionA,VersionB,_Ip1,_Ip2,_Ip3,_Ip4|OtherNode]) ->
{normal, list_to_atom(OtherNode), ?u16(VersionA,VersionB)};
get_name([$h,VersionA,VersionB,_Ip1,_Ip2,_Ip3,_Ip4|OtherNode]) ->
{hidden, list_to_atom(OtherNode), ?u16(VersionA,VersionB)};
get_name([$n,VersionA, VersionB, Flag1, Flag2, Flag3, Flag4 | OtherNode]) ->
Type = case ?u32(Flag1, Flag2, Flag3, Flag4) band ?DFLAG_PUBLISHED of
0 ->
hidden;
_ ->
normal
end,
{Type, list_to_atom(OtherNode),
?u16(VersionA,VersionB)};
get_name(Data) ->
?shutdown(Data).
%%
%% The communication with EPMD follows
%%
get_epmd_port() ->
case init:get_argument(epmd_port) of
{ok, [[PortStr|_]|_]} when is_list(PortStr) ->
list_to_integer(PortStr);
error ->
4369 % Default epmd port
end.
do_register_node(NodeName, TcpPort, VLow, VHigh) ->
case gen_tcp:connect({127,0,0,1}, get_epmd_port(), []) of
{ok, Socket} ->
{N0,_} = split(NodeName),
Name = atom_to_list(N0),
Extra = "",
Elen = length(Extra),
Len = 1+2+1+1+2+2+2+length(Name)+2+Elen,
gen_tcp:send(Socket, [?int16(Len), $x,
?int16(TcpPort),
$M,
0,
?int16(VHigh),
?int16(VLow),
?int16(length(Name)),
Name,
?int16(Elen),
Extra]),
case wait_for_reg_reply(Socket, []) of
{error, epmd_close} ->
exit(epmd_broken);
Other ->
Other
end;
Error ->
Error
end.
wait_for_reg_reply(Socket, SoFar) ->
receive
{tcp, Socket, Data0} ->
case SoFar ++ Data0 of
[$y, Result, A, B] ->
case Result of
0 ->
{alive, Socket, ?u16(A, B)};
_ ->
{error, duplicate_name}
end;
Data when length(Data) < 4 ->
wait_for_reg_reply(Socket, Data);
Garbage ->
{error, {garbage_from_epmd, Garbage}}
end;
{tcp_closed, Socket} ->
{error, epmd_close}
after 10000 ->
gen_tcp:close(Socket),
{error, no_reg_reply_from_epmd}
end.
register(NodeName, ListenSocket, VLow, VHigh) ->
{ok,{_,TcpPort}} = inet:sockname(ListenSocket),
case do_register_node(NodeName, TcpPort, VLow, VHigh) of
{alive, Socket, _Creation} ->
Socket;
Other ->
exit(Other)
end.
%%
%% Utilities
%%
%% Split a nodename
split([$@|T],A) ->
{lists:reverse(A),T};
split([H|T],A) ->
split(T,[H|A]).
split(Atom) ->
{A,B} = split(atom_to_list(Atom),[]),
{list_to_atom(A),list_to_atom(B)}.
%% Build a distribution message that will make rex answer
build_rex_message(Cookie,OurName) ->
[$?,term_to_binary({6,self(),Cookie,rex}),
term_to_binary({'$gen_cast',
{cast,
rpc,
cast,
[OurName, hello, world, []],
self()} })].
%% Receive a distribution message
recv_message(Socket) ->
case gen_tcp:recv(Socket, 0) of
{ok,Data} ->
B0 = list_to_binary(Data),
{_,B1} = erlang:split_binary(B0,1),
Header = binary_to_term(B1),
Siz = byte_size(term_to_binary(Header)),
{_,B2} = erlang:split_binary(B1,Siz),
Message = case (catch binary_to_term(B2)) of
{'EXIT', _} ->
could_not_digest_message;
Other ->
Other
end,
{Header, Message};
Res ->
exit({no_message,Res})
end.
%% Build a nodename
join(Name,Host) ->
list_to_atom(atom_to_list(Name) ++ "@" ++ atom_to_list(Host)).
%% start/stop slave.
start_node(Name, Param) ->
?t:start_node(Name, slave, [{args, Param}]).
stop_node(Node) ->
?t:stop_node(Node).
get_nodenames(N, T) ->
get_nodenames(N, T, []).
get_nodenames(0, _, Acc) ->
Acc;
get_nodenames(N, T, Acc) ->
U = erlang:unique_integer([positive]),
get_nodenames(N-1, T, [list_to_atom(?MODULE_STRING
++ "-"
++ atom_to_list(T)
++ "-"
++ integer_to_list(U)) | Acc]).
