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
|
%%
%% %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%
%%
%%
%% A diameter callback module that can redirect selected callbacks,
%% providing reasonable default implementations otherwise.
%%
%% To order alternate callbacks, configure a #diameter_callback record
%% as the Diameter application callback in question. The record has
%% one field for each callback function as well as 'default' and
%% 'extra' fields. A function-specific field can be set to a
%% diameter:eval() in order to redirect the callback
%% corresponding to that field, or to 'false' to request the default
%% callback implemented in this module. If neither of these fields are
%% set then the 'default' field determines the form of the callback: a
%% module name results in the usual callback as if the module had been
%% configured directly as the callback module, a diameter_eval()
%% in a callback applied to the atom-valued callback name and argument
%% list. For all callbacks not to this module, the 'extra' field is a
%% list of additional arguments, following arguments supplied by
%% diameter but preceding those of the diameter:eval() being
%% applied.
%%
%% For example, the following config to diameter:start_service/2, in
%% an 'application' tuple, would result in only a mymod:peer_down/3
%% callback, this module implementing the remaining callbacks.
%%
%% {module, #diameter_callback{peer_down = {mymod, down, []}}}
%%
%% Equivalently, this can also be specified with a [Mod | Args]
%% field/value list as follows.
%%
%% {module, [diameter_callback, {peer_down, {mymod, down, []}}]}
%%
%% The following would result in this module suppying peer_up and
%% peer_down callback, others taking place in module mymod.
%%
%% {module, #diameter_callback{peer_up = false,
%% peer_down = false,
%% default = mymod}}
%%
%% The following would result in all callbacks taking place as
%% calls to mymod:diameter/2.
%%
%% {module, #diameter_callback{default = {mymod, diameter, []}}}
%%
%% The following are equivalent and result in all callbacks being
%% provided by this module.
%%
%% {module, #diameter_callback{}}
%% {module, diameter_callback}
%%
-module(diameter_callback).
%% Default callbacks when no aleternate is specified.
-export([peer_up/3,
peer_down/3,
pick_peer/4,
prepare_request/3,
prepare_retransmit/3,
handle_request/3,
handle_answer/4,
handle_error/4]).
%% Callbacks taking a #diameter_callback record.
-export([peer_up/4,
peer_down/4,
pick_peer/5,
prepare_request/4,
prepare_retransmit/4,
handle_request/4,
handle_answer/5,
handle_error/5]).
-include_lib("diameter/include/diameter.hrl").
%%% ----------------------------------------------------------
%%% # peer_up/3
%%% ----------------------------------------------------------
peer_up(_Svc, _Peer, State) ->
State.
peer_up(Svc, Peer, State, D) ->
cb(peer_up,
[Svc, Peer, State],
D#diameter_callback.peer_up,
D).
%%% ----------------------------------------------------------
%%% # peer_down/3
%%% ----------------------------------------------------------
peer_down(_Svc, _Peer, State) ->
State.
peer_down(Svc, Peer, State, D) ->
cb(peer_down,
[Svc, Peer, State],
D#diameter_callback.peer_down,
D).
%%% ----------------------------------------------------------
%%% # pick_peer/4
%%% ----------------------------------------------------------
pick_peer([Peer|_], _, _Svc, _State) ->
{ok, Peer};
pick_peer([], _, _Svc, _State) ->
false.
pick_peer(PeersL, PeersR, Svc, State, D) ->
cb(pick_peer,
[PeersL, PeersR, Svc, State],
D#diameter_callback.pick_peer,
D).
%%% ----------------------------------------------------------
%%% # prepare_request/3
%%% ----------------------------------------------------------
prepare_request(Pkt, _Svc, _Peer) ->
{send, Pkt}.
prepare_request(Pkt, Svc, Peer, D) ->
cb(prepare_request,
[Pkt, Svc, Peer],
D#diameter_callback.prepare_request,
D).
%%% ----------------------------------------------------------
%%% # prepare_retransmit/3
%%% ----------------------------------------------------------
prepare_retransmit(Pkt, _Svc, _Peer) ->
{send, Pkt}.
prepare_retransmit(Pkt, Svc, Peer, D) ->
cb(prepare_retransmit,
[Pkt, Svc, Peer],
D#diameter_callback.prepare_retransmit,
D).
%%% ----------------------------------------------------------
%%% # handle_request/3
%%% ----------------------------------------------------------
handle_request(_Pkt, _Svc, _Peer) ->
{protocol_error, 3001}. %% DIAMETER_COMMAND_UNSUPPORTED
handle_request(Pkt, Svc, Peer, D) ->
cb(handle_request,
[Pkt, Svc, Peer],
D#diameter_callback.handle_request,
D).
%%% ----------------------------------------------------------
%%% # handle_answer/4
%%% ----------------------------------------------------------
handle_answer(#diameter_packet{msg = Ans, errors = []}, _Req, _Svc, _Peer) ->
Ans;
handle_answer(#diameter_packet{msg = Ans, errors = Es}, _Req, _Svc, _Peer) ->
[Ans | Es].
handle_answer(Pkt, Req, Svc, Peer, D) ->
cb(handle_answer,
[Pkt, Req, Svc, Peer],
D#diameter_callback.handle_answer,
D).
%%% ---------------------------------------------------------------------------
%%% # handle_error/4
%%% ---------------------------------------------------------------------------
handle_error(Reason, _Req, _Svc, _Peer) ->
{error, Reason}.
handle_error(Reason, Req, Svc, Peer, D) ->
cb(handle_error,
[Reason, Req, Svc, Peer],
D#diameter_callback.handle_error,
D).
%% ===========================================================================
%% cb/4
%% Unspecified callback: use default field to determine something
%% appropriate.
cb(CB, Args, undefined, D) ->
cb(CB, Args, D);
%% Explicitly requested default.
cb(CB, Args, false, _) ->
apply(?MODULE, CB, Args);
%% A specified callback.
cb(_, Args, F, #diameter_callback{extra = X}) ->
diameter_lib:eval([[F|X] | Args]).
%% cb/3
%% No user-supplied default: call ours.
cb(CB, Args, #diameter_callback{default = undefined}) ->
apply(?MODULE, CB, Args);
%% Default is a module name: make the usual callback.
cb(CB, Args, #diameter_callback{default = M,
extra = X})
when is_atom(M) ->
apply(M, CB, Args ++ X);
%% Default is something else: apply if to callback name and arguments.
cb(CB, Args, #diameter_callback{default = F,
extra = X}) ->
diameter_lib:eval([F, CB, Args | X]).
|
