%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2011. 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%
%%
-module(diameter_session).
-export([sequence/0,
session_id/1,
origin_state_id/0]).
%% towards diameter_sup
-export([init/0]).
-include("diameter_types.hrl").
-define(INT64, 16#FFFFFFFFFFFFFFFF).
-define(INT32, 16#FFFFFFFF).
%% ---------------------------------------------------------------------------
%% # sequence/0
%%
%% Output: 32-bit
%% ---------------------------------------------------------------------------
%% 3588, 3:
%%
%% Hop-by-Hop Identifier
%% The Hop-by-Hop Identifier is an unsigned 32-bit integer field (in
%% network byte order) and aids in matching requests and replies.
%% The sender MUST ensure that the Hop-by-Hop identifier in a request
%% is unique on a given connection at any given time, and MAY attempt
%% to ensure that the number is unique across reboots. The sender of
%% an Answer message MUST ensure that the Hop-by-Hop Identifier field
%% contains the same value that was found in the corresponding
%% request. The Hop-by-Hop identifier is normally a monotonically
%% increasing number, whose start value was randomly generated. An
%% answer message that is received with an unknown Hop-by-Hop
%% Identifier MUST be discarded.
%%
%% End-to-End Identifier
%% The End-to-End Identifier is an unsigned 32-bit integer field (in
%% network byte order) and is used to detect duplicate messages.
%% Upon reboot implementations MAY set the high order 12 bits to
%% contain the low order 12 bits of current time, and the low order
%% 20 bits to a random value. Senders of request messages MUST
%% insert a unique identifier on each message. The identifier MUST
%% remain locally unique for a period of at least 4 minutes, even
%% across reboots. The originator of an Answer message MUST ensure
%% that the End-to-End Identifier field contains the same value that
%% was found in the corresponding request. The End-to-End Identifier
%% MUST NOT be modified by Diameter agents of any kind. The
%% combination of the Origin-Host (see Section 6.3) and this field is
%% used to detect duplicates. Duplicate requests SHOULD cause the
%% same answer to be transmitted (modulo the hop-by-hop Identifier
%% field and any routing AVPs that may be present), and MUST NOT
%% affect any state that was set when the original request was
%% processed. Duplicate answer messages that are to be locally
%% consumed (see Section 6.2) SHOULD be silently discarded.
-spec sequence()
-> 'Unsigned32'().
sequence() ->
Instr = {_Pos = 2, _Incr = 1, _Threshold = ?INT32, _SetVal = 0},
ets:update_counter(diameter_sequence, sequence, Instr).
%% ---------------------------------------------------------------------------
%% # origin_state_id/0
%% ---------------------------------------------------------------------------
%% 3588, 8.16:
%%
%% The Origin-State-Id AVP (AVP Code 278), of type Unsigned32, is a
%% monotonically increasing value that is advanced whenever a Diameter
%% entity restarts with loss of previous state, for example upon reboot.
%% Origin-State-Id MAY be included in any Diameter message, including
%% CER.
%%
%% A Diameter entity issuing this AVP MUST create a higher value for
%% this AVP each time its state is reset. A Diameter entity MAY set
%% Origin-State-Id to the time of startup, or it MAY use an incrementing
%% counter retained in non-volatile memory across restarts.
-spec origin_state_id()
-> 'Unsigned32'().
origin_state_id() ->
ets:lookup_element(diameter_sequence, origin_state_id, 2).
%% ---------------------------------------------------------------------------
%% # session_id/1
%% ---------------------------------------------------------------------------
%% 3588, 8.8:
%%
%% The Session-Id MUST begin with the sender's identity encoded in the
%% DiameterIdentity type (see Section 4.4). The remainder of the
%% Session-Id is delimited by a ";" character, and MAY be any sequence
%% that the client can guarantee to be eternally unique; however, the
%% following format is recommended, (square brackets [] indicate an
%% optional element):
%%
%% <DiameterIdentity>;<high 32 bits>;<low 32 bits>[;<optional value>]
%%
%% <high 32 bits> and <low 32 bits> are decimal representations of the
%% high and low 32 bits of a monotonically increasing 64-bit value. The
%% 64-bit value is rendered in two part to simplify formatting by 32-bit
%% processors. At startup, the high 32 bits of the 64-bit value MAY be
%% initialized to the time, and the low 32 bits MAY be initialized to
%% zero. This will for practical purposes eliminate the possibility of
%% overlapping Session-Ids after a reboot, assuming the reboot process
%% takes longer than a second. Alternatively, an implementation MAY
%% keep track of the increasing value in non-volatile memory.
%%
%% <optional value> is implementation specific but may include a modem's
%% device Id, a layer 2 address, timestamp, etc.
-spec session_id('DiameterIdentity'())
-> 'OctetString'().
%% Note that Session-Id has type UTF8String and that any OctetString
%% is a UTF8String.
session_id(Host) ->
Instr = {_Pos = 2, _Incr = 1, _Threshold = ?INT64, _Set = 0},
N = ets:update_counter(diameter_sequence, session_base, Instr),
Hi = N bsr 32,
Lo = N band ?INT32,
[Host, ";", integer_to_list(Hi),
";", integer_to_list(Lo),
";", atom_to_list(node())].
%% ---------------------------------------------------------------------------
%% # init/0
%% ---------------------------------------------------------------------------
init() ->
Now = now(),
random:seed(Now),
Time = time32(Now),
Seq = (?INT32 band (Time bsl 20)) bor (random:uniform(1 bsl 20) - 1),
ets:insert(diameter_sequence, [{origin_state_id, Time},
{session_base, Time bsl 32},
{sequence, Seq}]),
Time.
%% ---------------------------------------------------------
%% INTERNAL FUNCTIONS
%% ---------------------------------------------------------
%% The minimum value represented by a Time value. (See diameter_types.)
%% 32 bits extends to 2104.
-define(TIME0, 62105714048). %% {{1968,1,20},{3,14,8}}
time32(Now) ->
Time = calendar:now_to_universal_time(Now),
Diff = calendar:datetime_to_gregorian_seconds(Time) - ?TIME0,
Diff band ?INT32.
