aboutsummaryrefslogtreecommitdiffstats
path: root/lib/erl_interface/test/ei_tmo_SUITE.erl
blob: 5b9de8012827adc0c39baedce3fcb8e05b2c7f4f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2003-2018. 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(ei_tmo_SUITE).

-include_lib("common_test/include/ct.hrl").
-include_lib("kernel/include/inet.hrl").
-include("ei_tmo_SUITE_data/ei_tmo_test_cases.hrl").

-export([all/0, suite/0,
         init_per_testcase/2, end_per_testcase/2,
         framework_check/1, ei_accept_tmo/1, ei_connect_tmo/1, ei_send_tmo/1,
	 ei_connect_tmo/0,
         ei_recv_tmo/1]).

suite() ->
    [{ct_hooks,[ts_install_cth]},
     {timetrap, {minutes, 1}}].

all() -> 
    [framework_check, ei_accept_tmo, ei_connect_tmo,
     ei_send_tmo, ei_recv_tmo].

init_per_testcase(Case, Config) ->
    Config1 = runner:init_per_testcase(?MODULE, Case, Config),

    % test if platform is vxworks_simso
    {_,Host} = split(node()),
    Bool = case atom_to_list(Host) of
               [$v,$x,$s,$i,$m | _] -> true;
               _ -> false
           end,
    [{vxsim,Bool} | Config1].

end_per_testcase(_Case, _Config) ->
    ok.

%% Check the framework.
framework_check(Config) when is_list(Config) ->
    %%dbg:tracer(),
    %%dbg:p(self()),
    P = runner:start(Config, ?framework_check),
    runner:send_term(P,{hello,world}),
    {term, {hello,world}} = runner:get_term(P),
    runner:recv_eot(P),
    ok.


%% Check recv with timeouts.
ei_recv_tmo(Config) when is_list(Config) ->
    do_one_recv(Config,c_node_recv_tmo_1),
    do_one_recv_failure(Config,c_node_recv_tmo_2),
    ok.


do_one_recv(Config,CNode) ->
    {_,Host} = split(node()),
    P1 = runner:start(Config, ?recv_tmo),
    runner:send_term(P1,{CNode,
                         erlang:get_cookie(),
                         node()}),
    {term, X} = runner:get_term(P1, 10000),
    true = is_integer(X),
    CNode1 = join(CNode,Host),
    Term1 = {hej,[hopp,{i,[lingon,"skogen"]}]},
    {test,CNode1} ! Term1,
    {term, Term1} = runner:get_term(P1, 10000),
    runner:recv_eot(P1).

do_one_recv_failure(Config,CNode) ->
    P1 = runner:start(Config, ?recv_tmo),
    runner:send_term(P1,{CNode,
                         erlang:get_cookie(),
                         node()}),
    {term, X} = runner:get_term(P1, 10000),
    true = is_integer(X),
    {term, {Ret,ETimedout,ETimedout}} = runner:get_term(P1, 10000),
    true = (Ret < 0),
    runner:recv_eot(P1).


%% Check send with timeouts.
ei_send_tmo(Config) when is_list(Config) ->
    %dbg:tracer(),
    %dbg:p(self()),
    VxSim = proplists:get_value(vxsim, Config),
    register(ei_send_tmo_1,self()),
    do_one_send(Config,self(),c_node_send_tmo_1),
    do_one_send(Config,ei_send_tmo_1,c_node_send_tmo_2),
    do_one_send_failure(Config,self(),cccc1,c_nod_send_tmo_3,VxSim),
    do_one_send_failure(Config,ei_send_tmo_1,cccc2,c_nod_send_tmo_4,VxSim),
    ok.


do_one_send(Config,From,CNode) ->
    {_,Host} = split(node()),
    P1 = runner:start(Config, ?send_tmo),
    runner:send_term(P1,{CNode,
                         erlang:get_cookie(),
                         node()}),
    {term, X} = runner:get_term(P1, 10000),
    true = is_integer(X),
    CNode1 = join(CNode,Host),
    Term1 = {hej,[hopp,{i,[lingon,"skogen"]}]},
    {test,CNode1} ! {From,1,Term1},
    ok = receive
             Term1 ->
                 ok
         after 2000 ->
                   error
         end,
    {term, 0} = runner:get_term(P1, 10000),
    runner:recv_eot(P1).

do_one_send_failure(Config,From,FakeName,CName,VxSim) ->
    {_,Host} = split(node()),
    OurName = join(FakeName,Host),
    Node = join(CName,Host),
    LSocket = case gen_tcp:listen(0, [{active, false}, {packet,2}]) of
                  {ok, Socket} ->
                      Socket;
                  Else ->
                      exit(Else)
              end,
    EpmdSocket = register(OurName, LSocket, 1, 5),
    P3 = runner:start(Config, ?send_tmo),
    Cookie = kaksmula_som_ingen_bryr_sig_om,
    runner:send_term(P3,{CName,
                         Cookie,
                         OurName}),
    SocketB = case gen_tcp:accept(LSocket) of
                  {ok, Socket1} ->
                      Socket1;
                  Else2 ->
                      exit(Else2)
              end,
    {hidden,Node,5} = recv_name(SocketB),  % See 1)
    send_status(SocketB, ok),
    MyChallengeB = gen_challenge(),
    send_challenge(SocketB, OurName, MyChallengeB, 5),
    HisChallengeB = recv_challenge_reply(SocketB,
                                         MyChallengeB,
                                         Cookie),
    DigestB = gen_digest(HisChallengeB,Cookie),
    send_challenge_ack(SocketB, DigestB),
    inet:setopts(SocketB, [{active, false},
                           {packet, 4}]),
    {term, X} = runner:get_term(P3, 10000),
    true = is_integer(X),
    Message = [112,term_to_binary({6,self(),'',test}),
               term_to_binary({From,50000,
                               {app,["lapp",{sa,["att",du,{slapp,
                                                           sitta}]}]}})],
    gen_tcp:send(SocketB,Message),

    %% At this point the test program starts sending messages (max 50000). Since
    %% we're not receiving, eventually the send buffer fills up. Then no more 
    %% sending is possible and select() times out. The number of messages sent
    %% before this happens is returned in Iters. The timeout value for get_term/2
    %% must be large enough so there's time for the select() to time out and
    %% the test program to return the error tuple (below).

    Res0 = if VxSim == false ->
                  {term,{Res,ETO,Iters,ETO}} = runner:get_term(P3, 20000),
                  Res;
              true ->   % relax the test for vxsim
                  case runner:get_term(P3, 20000) of
                      {term,{Res,ETO,Iters,ETO}} ->
                          Res;
                      {term,{Res,_,Iters,_ETO}} -> % EIO?
                          Res
                  end
           end,
    runner:recv_eot(P3),
    true = ((Res0 < 0) and (Iters > 0)),
    gen_tcp:close(SocketB),
    gen_tcp:close(EpmdSocket),
    ok.


%% Check accept with timeouts.
ei_connect_tmo() -> [{require, test_host_not_reachable}].

ei_connect_tmo(Config) when is_list(Config) ->
    %dbg:tracer(),
    %dbg:p(self()),
    VxSim = proplists:get_value(vxsim, Config),
    DummyNode = make_and_check_dummy(),
    P = runner:start(Config, ?connect_tmo),
    runner:send_term(P,{c_nod_connect_tmo_1,
                        kaksmula_som_ingen_bryr_sig_om,
                        DummyNode}),
    ETimedout =
    if VxSim == false ->
           {term,{-3,ETO,ETO}} = runner:get_term(P, 10000),
           ETO;
       true ->				% relax the test for vxsim
           case runner:get_term(P, 10000) of
               {term,{-3,ETO,ETO}} ->
                   ETO;
               {term,{-1,_,ETO}} ->	% EHOSTUNREACH = ok
                   ETO
           end
    end,
    runner:recv_eot(P),
    P2 = runner:start(Config, ?connect_tmo),
    runner:send_term(P2,{c_nod_connect_tmo_2,
                         erlang:get_cookie(),
                         node()}),
    {term, X} = runner:get_term(P2, 10000),
    runner:recv_eot(P2),
    true = is_integer(X),
    %% Aborted handshake test...
    {_,Host} = split(node()),
    OurName = join(cccc,Host),
    Node = join(c_nod_connect_tmo_3,Host),
    LSocket = case gen_tcp:listen(0, [{active, false}, {packet,2}]) of
                  {ok, Socket} ->
                      Socket;
                  Else ->
                      exit(Else)
              end,
    EpmdSocket = register(OurName, LSocket, 1, 5),
    P3 = runner:start(Config, ?connect_tmo),
    Cookie = kaksmula_som_ingen_bryr_sig_om,
    runner:send_term(P3,{c_nod_connect_tmo_3,
                         Cookie,
                         OurName}),
    SocketB = case gen_tcp:accept(LSocket) of
                  {ok, Socket1} ->
                      Socket1;
                  Else2 ->
                      exit(Else2)
              end,
    {hidden,Node,5} = recv_name(SocketB),  % See 1)
    send_status(SocketB, ok),
    MyChallengeB = gen_challenge(),
    send_challenge(SocketB, OurName, MyChallengeB, 5),
    _HisChallengeB = recv_challenge_reply(SocketB,
                                          MyChallengeB,
                                          Cookie),
    {term,{-1,ETimedout,ETimedout}} = runner:get_term(P3, 10000),
    runner:recv_eot(P3),
    gen_tcp:close(SocketB),
    gen_tcp:close(EpmdSocket),
    ok.


%% Check accept with timeouts.
ei_accept_tmo(Config) when is_list(Config) ->
    %%dbg:tracer(),
    %%dbg:p(self()),
    P = runner:start(Config, ?accept_tmo),
    runner:send_term(P,{c_nod_som_ingen_kontaktar_1,
                        kaksmula_som_ingen_bryr_sig_om}),
    {term,{-1,ETimedout,ETimedout}} = runner:get_term(P, 10000),
    runner:recv_eot(P),
    P2 = runner:start(Config, ?accept_tmo),
    runner:send_term(P2,{c_nod_som_vi_kontaktar_1,
                         erlang:get_cookie()}),
    receive after 1000 -> ok end,
    CNode1 = make_node(c_nod_som_vi_kontaktar_1),
    {ignored,CNode1} ! tjenare,
    {term, X} = runner:get_term(P2, 10000),
    runner:recv_eot(P2),
    true = is_integer(X),
    P3 = runner:start(Config, ?accept_tmo),
    runner:send_term(P3,{c_nod_som_vi_kontaktar_2,
                         erlang:get_cookie()}),
    receive after 1000 -> ok end,
    CNode2 = make_node(c_nod_som_vi_kontaktar_2),
    {NA,NB} = split(CNode2),
    {_,Host} = split(node()),
    OurName = join(ccc,Host),
    {port,PortNo,_} = erl_epmd:port_please(NA,NB),
    {ok, SocketA} = gen_tcp:connect(atom_to_list(NB),PortNo,
                                    [{active,false},
                                     {packet,2}]),
    send_name(SocketA,OurName,5),
    ok = recv_status(SocketA),
    {hidden,_Node,5,HisChallengeA} = recv_challenge(SocketA), % See 1)
    _OurChallengeA = gen_challenge(),
    _OurDigestA = gen_digest(HisChallengeA, erlang:get_cookie()),
    %% Dont do the last two steps of the connection setup...
    %% send_challenge_reply(SocketA, OurChallengeA, OurDigestA),
    %% ok = recv_challenge_ack(SocketA, OurChallengeA, erlang:get_cookie()),
    {term, {-1,ETimedout,ETimedout}} = runner:get_term(P3, 10000),
    runner:recv_eot(P3),
    gen_tcp:close(SocketA),
    ok.

make_node(X) ->
    list_to_atom(atom_to_list(X) ++ "@" ++ 
                 hd(tl(string:tokens(atom_to_list(node()),"@")))).


make_and_check_dummy() ->
    % First check that the host has an ip and is *not* reachable
    HostNotReachable = ct:get_config(test_host_not_reachable),
    case gen_tcp:connect(HostNotReachable, 23, [{active,false}],5000) of
        {error,timeout} -> ok;
        {error,ehostunreach} -> ok
    end,

    list_to_atom("dummy@"++HostNotReachable).

%%
%% Stolen from the erl_distribution_wb_test in kernel
%% To be able to do partial handshakes...
%%

-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_EXTENDED_PIDS_PORTS,16#100).
-define(DFLAG_NEW_FLOATS,16#800).
-define(DFLAG_DIST_MONITOR,8).

%% From R9 and forward extended references is compulsory
%% From 14 and forward new float is compulsory
-define(COMPULSORY_DFLAGS, (?DFLAG_EXTENDED_REFERENCES bor ?DFLAG_EXTENDED_PIDS_PORTS bor ?DFLAG_NEW_FLOATS)).

-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))).

%%
%% Handshake utilities
%%

%%
%% MD5 hashing
%%

%% This is no proper random number, but that is not really important in 
%% this test
gen_challenge() ->
    {_,_,N} = os:timestamp(),
    N.

%% 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),
    ?to_port(Socket, [$n,?int16(Version),?int32(Flags)] ++ 
             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).

%%
%% tell_name is for old handshake
%%
%tell_name(Socket, MyNode0, Version) ->
%    MyNode = atom_to_list(MyNode0),
%    {ok, {{Ip1,Ip2,Ip3,Ip4}, _}} = inet:sockname(Socket),
%    ?to_port(Socket, [$h,?int16(Version),Ip1,Ip2,Ip3,Ip4] ++ MyNode).

%%
%% The communication with EPMD follows
%%
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 nodename
join(Name,Host) ->
    list_to_atom(atom_to_list(Name) ++ "@" ++ atom_to_list(Host)).

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.