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
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
|
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2017. 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(diameter_codec).
-export([encode/2,
decode/2,
decode/3,
setopts/1,
getopt/1,
collect_avps/1,
decode_header/1,
sequence_numbers/1,
hop_by_hop_id/2,
msg_name/2,
msg_id/1]).
%% Towards generated encoders (from diameter_gen.hrl).
-export([pack_avp/1,
pack_avp/2]).
-include_lib("diameter/include/diameter.hrl").
-include("diameter_internal.hrl").
-define(PAD(Len), ((4 - (Len rem 4)) rem 4)).
-define(BIT(B,I), (if B -> I; true -> 0 end)).
-define(BIT(B), ?BIT(B,1)).
-define(FLAGS(R,P,E,T), ?BIT(R):1, ?BIT(P):1, ?BIT(E):1, ?BIT(T):1, 0:4).
-define(FLAG(B,D), (if is_boolean(B) -> B; true -> 0 /= (D) end)).
-type u32() :: 0..16#FFFFFFFF.
-type u24() :: 0..16#FFFFFF.
-type u1() :: 0..1.
%% 0 1 2 3
%% 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | Version | Message Length |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | command flags | Command-Code |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | Application-ID |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | Hop-by-Hop Identifier |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | End-to-End Identifier |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | AVPs ...
%% +-+-+-+-+-+-+-+-+-+-+-+-+-
%%% ---------------------------------------------------------------------------
%%% # setopts/1
%%% # getopt/1
%%% ---------------------------------------------------------------------------
%% These functions are a compromise in the same vein as the use of the
%% process dictionary in diameter_gen.hrl in generated codec modules.
%% Instead of rewriting the entire dictionary generation to pass
%% encode/decode options around, the calling process sets them by
%% calling setopts/1. At current, the only option is whether or not to
%% decode binaries as strings, which is used by diameter_types.
setopts(Opts)
when is_list(Opts) ->
lists:foreach(fun setopt/1, Opts).
%% The default string_decode true is for backwards compatibility.
setopt({K, false = B})
when K == string_decode;
K == strict_mbit ->
setopt(K, B);
%% Regard anything but the generated RFC 3588 dictionary as modern.
%% This affects the interpretation of defaults during the decode
%% of values of type DiameterURI, this having changed from RFC 3588.
%% (So much for backwards compatibility.)
setopt({common_dictionary, diameter_gen_base_rfc3588}) ->
setopt(rfc, 3588);
setopt(_) ->
ok.
setopt(Key, Value) ->
put({diameter, Key}, Value).
getopt(Key) ->
case get({diameter, Key}) of
undefined when Key == string_decode;
Key == strict_mbit ->
true;
undefined when Key == rfc ->
6733;
V ->
V
end.
%%% ---------------------------------------------------------------------------
%%% # encode/2
%%% ---------------------------------------------------------------------------
-spec encode(module(), Msg :: term())
-> #diameter_packet{}
| no_return().
encode(Mod, #diameter_packet{} = Pkt) ->
try
e(Mod, Pkt)
catch
exit: {Reason, Stack, #diameter_header{} = H} = T ->
%% Exit with a header in the reason to let the caller
%% count encode errors.
?LOG(encode_error, {Reason, Stack, H}),
exit({?MODULE, encode, T});
error: Reason ->
T = {Reason, diameter_lib:get_stacktrace()},
?LOG(encode_error, T),
exit({?MODULE, encode, T})
end;
encode(Mod, Msg) ->
Seq = diameter_session:sequence(),
Hdr = #diameter_header{version = ?DIAMETER_VERSION,
end_to_end_id = Seq,
hop_by_hop_id = Seq},
encode(Mod, #diameter_packet{header = Hdr,
msg = Msg}).
e(_, #diameter_packet{msg = [#diameter_header{} = Hdr | As]} = Pkt) ->
try encode_avps(reorder(As)) of
Avps ->
Bin = list_to_binary(Avps),
Len = 20 + size(Bin),
#diameter_header{version = Vsn,
is_request = R,
is_proxiable = P,
is_error = E,
is_retransmitted = T,
cmd_code = Code,
application_id = Aid,
hop_by_hop_id = Hid,
end_to_end_id = Eid}
= Hdr,
Pkt#diameter_packet{header = Hdr,
bin = <<Vsn:8, Len:24,
?FLAGS(R,P,E,T), Code:24,
Aid:32,
Hid:32,
Eid:32,
Bin/binary>>}
catch
error: Reason ->
exit({Reason, diameter_lib:get_stacktrace(), Hdr})
end;
e(Mod, #diameter_packet{header = Hdr0, msg = Msg} = Pkt) ->
MsgName = rec2msg(Mod, Msg),
{Code, Flags, Aid} = msg_header(Mod, MsgName, Hdr0),
#diameter_header{version = Vsn,
is_request = R,
is_proxiable = P,
is_error = E,
is_retransmitted = T,
hop_by_hop_id = Hid,
end_to_end_id = Eid}
= Hdr0,
RB = ?FLAG(R, Flags band 2#10000000),
PB = ?FLAG(P, Flags band 2#01000000),
EB = ?FLAG(E, Flags band 2#00100000),
TB = ?FLAG(T, Flags band 2#00010000),
Values = values(Msg),
try encode_avps(Mod, MsgName, Values) of
Avps ->
Bin = list_to_binary(Avps),
Len = 20 + size(Bin),
Hdr = Hdr0#diameter_header{length = Len,
cmd_code = Code,
application_id = Aid,
is_request = RB,
is_proxiable = PB,
is_error = EB,
is_retransmitted = TB},
Pkt#diameter_packet{header = Hdr,
bin = <<Vsn:8, Len:24,
?FLAGS(RB, PB, EB, TB), Code:24,
Aid:32,
Hid:32,
Eid:32,
Bin/binary>>}
catch
error: Reason ->
Hdr = Hdr0#diameter_header{cmd_code = Code,
application_id = Aid,
is_request = RB,
is_proxiable = PB,
is_error = EB,
is_retransmitted = TB},
exit({Reason, diameter_lib:get_stacktrace(), Hdr})
end.
%% values/1
values([H|T])
when is_atom(H) ->
T;
values(Avps) ->
Avps.
%% encode_avps/3
%% Specifying values as a #diameter_avp list bypasses arity and other
%% checks: the values are expected to be already encoded and the AVP's
%% presented are simply sent. This is needed for relay agents, since
%% these have to be able to resend whatever comes.
%% Message as a list of #diameter_avp{} ...
encode_avps(_, _, [#diameter_avp{} | _] = Avps) ->
encode_avps(reorder(Avps));
%% ... or as a tuple list or record.
encode_avps(Mod, MsgName, Values) ->
Mod:encode_avps(MsgName, Values).
%% reorder/1
%%
%% Reorder AVPs for the relay case using the index field of
%% diameter_avp records. Decode populates this field in collect_avps
%% and presents AVPs in reverse order. A relay then sends the reversed
%% list with a Route-Record AVP prepended. The goal here is just to do
%% lists:reverse/1 in Grouped AVPs and the outer list, but only in the
%% case there are indexed AVPs at all, so as not to reverse lists that
%% have been explicilty sent (unindexed, in the desired order) as a
%% diameter_avp list. The effect is the same as lists:keysort/2, but
%% only on the cases we expect, not a general sort.
reorder(Avps) ->
case reorder(Avps, []) of
false ->
Avps;
Sorted ->
Sorted
end.
%% reorder/3
%% In case someone has reversed the list already. (Not likely.)
reorder([#diameter_avp{index = 0} | _] = Avps, Acc) ->
Avps ++ Acc;
%% Assume indexed AVPs are in reverse order.
reorder([#diameter_avp{index = N} = A | Avps], Acc)
when is_integer(N) ->
lists:reverse(Avps, [A | Acc]);
%% An unindexed AVP.
reorder([H | T], Acc) ->
reorder(T, [H | Acc]);
%% No indexed members.
reorder([], _) ->
false.
%% encode_avps/1
encode_avps(Avps) ->
lists:map(fun pack_avp/1, Avps).
%% msg_header/3
msg_header(Mod, 'answer-message' = MsgName, Header) ->
0 = Mod:id(), %% assert
#diameter_header{application_id = Aid,
cmd_code = Code}
= Header,
{-1, Flags, ?APP_ID_COMMON} = Mod:msg_header(MsgName),
{Code, Flags, Aid};
msg_header(Mod, MsgName, _) ->
Mod:msg_header(MsgName).
%% rec2msg/2
rec2msg(_, [Name|_])
when is_atom(Name) ->
Name;
rec2msg(Mod, Rec) ->
Mod:rec2msg(element(1, Rec)).
%%% ---------------------------------------------------------------------------
%%% # decode/2
%%% ---------------------------------------------------------------------------
%% Unsuccessfully decoded AVPs will be placed in #diameter_packet.errors.
-spec decode(module() | {module(), module()}, #diameter_packet{} | binary())
-> #diameter_packet{}.
%% An Answer setting the E-bit. The application dictionary is needed
%% for the best-effort decode of Failed-AVP, and the best way to make
%% this available to the AVP decode in diameter_gen.hrl, without
%% having to rewrite the entire codec generation, is to place it in
%% the process dictionary. It's the code in diameter_gen.hrl (that's
%% included by every generated codec module) that looks for the entry.
%% Not ideal, but it solves the problem relatively simply.
decode({Mod, Mod}, Pkt) ->
decode(Mod, Pkt);
decode({Mod, AppMod}, Pkt) ->
Key = {?MODULE, dictionary},
put(Key, AppMod),
try
decode(Mod, Pkt)
after
erase(Key)
end;
%% Or not: a request, or an answer not setting the E-bit.
decode(Mod, Pkt) ->
decode(Mod:id(), Mod, Pkt).
%% decode/3
%% Relay application: just extract the avp's without any decoding of
%% their data since we don't know the application in question.
decode(?APP_ID_RELAY, _, #diameter_packet{} = Pkt) ->
case collect_avps(Pkt) of
{E, As} ->
Pkt#diameter_packet{avps = As,
errors = [E]};
As ->
Pkt#diameter_packet{avps = As}
end;
%% Otherwise decode using the dictionary.
decode(_, Mod, #diameter_packet{header = Hdr} = Pkt) ->
#diameter_header{cmd_code = CmdCode,
is_request = IsRequest,
is_error = IsError}
= Hdr,
MsgName = if IsError andalso not IsRequest ->
'answer-message';
true ->
Mod:msg_name(CmdCode, IsRequest)
end,
decode_avps(MsgName, Mod, Pkt, collect_avps(Pkt));
decode(Id, Mod, Bin)
when is_binary(Bin) ->
decode(Id, Mod, #diameter_packet{header = decode_header(Bin), bin = Bin}).
%% decode_avps/4
decode_avps(MsgName, Mod, Pkt, {E, Avps}) ->
?LOG(invalid_avp_length, Pkt#diameter_packet.header),
#diameter_packet{errors = Failed}
= P
= decode_avps(MsgName, Mod, Pkt, Avps),
P#diameter_packet{errors = [E | Failed]};
decode_avps('', _, Pkt, Avps) -> %% unknown message ...
?LOG(unknown_message, Pkt#diameter_packet.header),
Pkt#diameter_packet{avps = lists:reverse(Avps),
errors = [3001]}; %% DIAMETER_COMMAND_UNSUPPORTED
%% msg = undefined identifies this case.
decode_avps(MsgName, Mod, Pkt, Avps) -> %% ... or not
{Rec, As, Errors} = Mod:decode_avps(MsgName, Avps),
?LOGC([] /= Errors, decode_errors, Pkt#diameter_packet.header),
Pkt#diameter_packet{msg = Rec,
errors = Errors,
avps = As}.
%%% ---------------------------------------------------------------------------
%%% # decode_header/1
%%% ---------------------------------------------------------------------------
-spec decode_header(binary())
-> #diameter_header{}
| false.
decode_header(<<Version:8,
MsgLength:24,
R:1, P:1, E:1, T:1, _:4,
CmdCode:24,
ApplicationId:32,
HopByHopId:32,
EndToEndId:32,
_/binary>>) ->
%% 3588 (ch 3) says that reserved bits MUST be set to 0 and ignored
%% by the receiver.
%% The RFC is quite unclear about the order of the bits in this
%% case. It writes
%%
%% 0 1 2 3 4 5 6 7
%% +-+-+-+-+-+-+-+-+
%% |R P E T r r r r|
%% +-+-+-+-+-+-+-+-+
%%
%% in defining these but the scale refers to the (big endian)
%% transmission order, first to last, not the bit order. That is,
%% R is the high order bit. It's odd that a standard reserves
%% low-order bit rather than high-order ones.
#diameter_header{version = Version,
length = MsgLength,
cmd_code = CmdCode,
application_id = ApplicationId,
hop_by_hop_id = HopByHopId,
end_to_end_id = EndToEndId,
is_request = 1 == R,
is_proxiable = 1 == P,
is_error = 1 == E,
is_retransmitted = 1 == T};
decode_header(_) ->
false.
%%% ---------------------------------------------------------------------------
%%% # sequence_numbers/1
%%% ---------------------------------------------------------------------------
%% The End-To-End identifier must be unique for at least 4 minutes. We
%% maintain a 24-bit wraparound counter, and add an 8-bit persistent
%% wraparound counter. The 8-bit counter is incremented each time the
%% system is restarted.
-spec sequence_numbers(#diameter_packet{}
| #diameter_header{}
| binary()
| Seq)
-> Seq
when Seq :: {HopByHopId :: u32(), EndToEndId :: u32()}.
sequence_numbers({_,_} = T) ->
T;
sequence_numbers(#diameter_packet{bin = Bin})
when is_binary(Bin) ->
sequence_numbers(Bin);
sequence_numbers(#diameter_packet{header = #diameter_header{} = H}) ->
sequence_numbers(H);
sequence_numbers(#diameter_packet{msg = [#diameter_header{} = H | _]}) ->
sequence_numbers(H);
sequence_numbers(#diameter_header{hop_by_hop_id = H,
end_to_end_id = E}) ->
{H,E};
sequence_numbers(<<_:12/binary, H:32, E:32, _/binary>>) ->
{H,E}.
%%% ---------------------------------------------------------------------------
%%% # hop_by_hop_id/2
%%% ---------------------------------------------------------------------------
-spec hop_by_hop_id(u32(), binary())
-> binary().
hop_by_hop_id(Id, <<H:12/binary, _:32, T/binary>>) ->
<<H/binary, Id:32, T/binary>>.
%%% ---------------------------------------------------------------------------
%%% # msg_name/2
%%% ---------------------------------------------------------------------------
-spec msg_name(module(), #diameter_header{})
-> atom()
| {ApplicationId :: u32(), CommandCode :: u24(), Rbit :: u1()}.
msg_name(Dict0, #diameter_header{application_id = ?APP_ID_COMMON,
cmd_code = C,
is_request = R}) ->
Dict0:msg_name(C,R);
msg_name(_, Hdr) ->
msg_id(Hdr).
%% Note that messages in different applications could have the same
%% name.
%%% ---------------------------------------------------------------------------
%%% # msg_id/1
%%% ---------------------------------------------------------------------------
-spec msg_id(#diameter_packet{} | #diameter_header{})
-> {ApplicationId :: u32(), CommandCode :: u24(), Rbit :: u1()}.
msg_id(#diameter_packet{msg = [#diameter_header{} = Hdr | _]}) ->
msg_id(Hdr);
msg_id(#diameter_packet{header = #diameter_header{} = Hdr}) ->
msg_id(Hdr);
msg_id(#diameter_header{application_id = A,
cmd_code = C,
is_request = R}) ->
{A, C, ?BIT(R)};
msg_id(<<_:32, Rbit:1, _:7, CmdCode:24, ApplId:32, _/binary>>) ->
{ApplId, CmdCode, Rbit}.
%%% ---------------------------------------------------------------------------
%%% # collect_avps/1
%%% ---------------------------------------------------------------------------
%% Note that the returned list of AVP's is reversed relative to their
%% order in the binary. Note also that grouped avp's aren't unraveled,
%% only those at the top level.
-spec collect_avps(#diameter_packet{} | binary())
-> [Avp]
| {Error, [Avp]}
when Avp :: #diameter_avp{},
Error :: {5014, #diameter_avp{}}.
collect_avps(#diameter_packet{bin = <<_:20/binary, Avps/binary>>}) ->
collect_avps(Avps, 0, []);
collect_avps(Bin)
when is_binary(Bin) ->
collect_avps(Bin, 0, []).
%% collect_avps/3
%% 0 1 2 3
%% 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | AVP Code |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% |V M P r r r r r| AVP Length |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | Vendor-ID (opt) |
%% +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
%% | Data ...
%% +-+-+-+-+-+-+-+-+
collect_avps(<<Code:32, V:1, M:1, P:1, _:5, Len:24, I:V/unit:32, Rest/binary>>,
N,
Acc) ->
collect_avps(Code,
if 1 == V -> I; 0 == V -> undefined end,
1 == M,
1 == P,
Len - 8 - V*4, %% Might be negative, which ensures
?PAD(Len), %% failure of the Data match below.
Rest,
N,
Acc);
collect_avps(<<>>, _, Acc) ->
Acc;
%% Header is truncated. pack_avp/1 will pad this at encode if sent in
%% a Failed-AVP.
collect_avps(Bin, _, Acc) ->
{{5014, #diameter_avp{data = Bin}}, Acc}.
%% collect_avps/9
%% Duplicate the diameter_avp creation in each branch below to avoid
%% modifying the record, which profiling has shown to be a relatively
%% costly part of building the list.
collect_avps(Code, VendorId, M, P, Len, Pad, Rest, N, Acc) ->
case Rest of
<<Data:Len/binary, _:Pad/binary, T/binary>> ->
Avp = #diameter_avp{code = Code,
vendor_id = VendorId,
is_mandatory = M,
need_encryption = P,
data = Data,
index = N},
collect_avps(T, N+1, [Avp | Acc]);
_ ->
%% Length in header points past the end of the message, or
%% doesn't span the header. As stated in the 6733 text
%% above, it's sufficient to return a zero-filled minimal
%% payload if this is a request. Do this (in cases that we
%% know the type) by inducing a decode failure and letting
%% the dictionary's decode (in diameter_gen) deal with it.
%%
%% Note that the extra bit can only occur in the trailing
%% AVP of a message or Grouped AVP, since a faulty AVP
%% Length is otherwise indistinguishable from a correct
%% one here, as we don't know the types of the AVPs being
%% extracted.
Avp = #diameter_avp{code = Code,
vendor_id = VendorId,
is_mandatory = M,
need_encryption = P,
data = <<0:1, Rest/binary>>,
index = N},
[Avp | Acc]
end.
%% 3588:
%%
%% DIAMETER_INVALID_AVP_LENGTH 5014
%% The request contained an AVP with an invalid length. A Diameter
%% message indicating this error MUST include the offending AVPs
%% within a Failed-AVP AVP.
%% 6733:
%%
%% DIAMETER_INVALID_AVP_LENGTH 5014
%%
%% The request contained an AVP with an invalid length. A Diameter
%% message indicating this error MUST include the offending AVPs
%% within a Failed-AVP AVP. In cases where the erroneous AVP length
%% value exceeds the message length or is less than the minimum AVP
%% ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
%% header length, it is sufficient to include the offending AVP
%% ^^^^^^^^^^^^^
%% header and a zero filled payload of the minimum required length
%% for the payloads data type. If the AVP is a Grouped AVP, the
%% Grouped AVP header with an empty payload would be sufficient to
%% indicate the offending AVP. In the case where the offending AVP
%% header cannot be fully decoded when the AVP length is less than
%% the minimum AVP header length, it is sufficient to include an
%% offending AVP header that is formulated by padding the incomplete
%% AVP header with zero up to the minimum AVP header length.
%%
%% The underlined clause must be in error since (1) a header less than
%% the minimum value mean we might not know the identity of the AVP and
%% (2) the last sentence covers this case.
%%% ---------------------------------------------------------------------------
%%% # pack_avp/1
%%% ---------------------------------------------------------------------------
%% The normal case here is data as an #diameter_avp{} list or an
%% iolist, which are the cases that generated codec modules use. The
%% other cases are a convenience in the relay case in which the
%% dictionary doesn't know about specific AVP's.
%% Decoded Grouped AVP with decoded components: ignore components
%% since they're already encoded in the Grouped AVP.
pack_avp([#diameter_avp{} = Grouped | _Components]) ->
pack_avp(Grouped);
%% Grouped AVP whose components need packing. It's intentional that
%% this isn't equivalent to [Grouped | Components]: here the
%% components need to be encoded before wrapping with the Grouped AVP,
%% and the list is flat, nesting being accomplished in the data
%% fields.
pack_avp(#diameter_avp{data = [#diameter_avp{} | _] = Components} = Grouped) ->
pack_data(encode_avps(Components), Grouped);
%% Data as a type/value tuple ...
pack_avp(#diameter_avp{data = {Type, Value}} = A)
when is_atom(Type) ->
pack_data(diameter_types:Type(encode, Value), A);
%% ... with a header in various forms ...
pack_avp(#diameter_avp{data = {T, {Type, Value}}}) ->
pack_avp(T, diameter_types:Type(encode, Value));
pack_avp(#diameter_avp{data = {T, Data}}) ->
pack_avp(T, Data);
pack_avp(#diameter_avp{data = {Dict, Name, Data}}) ->
pack_avp(Dict:avp_header(Name), Dict:avp(encode, Data, Name));
%% ... with a truncated header ...
pack_avp(#diameter_avp{code = undefined, data = B})
when is_binary(B) ->
%% Reset the AVP Length of an AVP Header resulting from a 5014
%% error. The RFC doesn't explicitly say to do this but the
%% receiver can't correctly extract this and following AVP's
%% without a correct length. On the downside, the header doesn't
%% reveal if the received header has been padded. Discard bytes
%% from the length header for this reason, to avoid creating a sub
%% binary for no useful reason.
Len = header_length(B),
Sz = min(5, size(B)),
<<B:Sz/binary, 0:(5-Sz)/unit:8, Len:24, 0:(Len-8)/unit:8>>;
pack_avp(#diameter_avp{data = Data} = A) ->
pack_bits(Data, A).
header_length(<<_:32, 1:1, _/bits>>) ->
12;
header_length(_) ->
8.
%% pack_bits/2
%% Ignoring errors in Failed-AVP or during a relay encode.
pack_bits(<<0:1, B/binary>>, Avp) ->
pack_bits(B, Avp);
pack_bits(Data, Avp) ->
pack_data(Data, Avp).
%% pack_data/2
pack_data(Data, #diameter_avp{code = Code,
vendor_id = V,
is_mandatory = M,
need_encryption = P}) ->
Flags = ?BIT(V /= undefined, 2#10000000)
bor ?BIT(M, 2#01000000)
bor ?BIT(P, 2#00100000),
pack_avp(Code, Flags, V, Data).
%%% ---------------------------------------------------------------------------
%%% # pack_avp/2
%%% ---------------------------------------------------------------------------
pack_avp({Code, Flags, VendorId}, Data) ->
pack_avp(Code, Flags, VendorId, Data).
%% pack_avp/4
pack_avp(Code, Flags, VendorId, Data) ->
Sz = iolist_size(Data),
pack_avp(Code, Flags, Sz, VendorId, Data, ?PAD(Sz)).
%% Padding is not included in the length field, as mandated by the RFC.
%% pack_avp/6
%%
%% Prepend the vendor id as required.
pack_avp(Code, Flags, Sz, _Vid, Data, Pad)
when 0 == Flags band 2#10000000 ->
pack_avp(Code, Flags, Sz, 0, 0, Data, Pad);
pack_avp(Code, Flags, Sz, Vid, Data, Pad) ->
pack_avp(Code, Flags, Sz+4, Vid, 1, Data, Pad).
%% pack_avp/7
pack_avp(Code, Flags, Sz, VId, V, Data, Pad) ->
[<<Code:32, Flags:8, (8+Sz):24, VId:V/unit:32>>, Data, <<0:Pad/unit:8>>].
|