%% -*- erlang -*-
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2010-2016. 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 grammar for dictionary specification.
%%
Nonterminals
application_id avp avp_code avp_def avp_defs avp_flags avp_header
avp_header_tok avp_name avp_names avp_ref avp_spec avp_type
avp_vendor avps bit bits command_def command_id diameter_name
dictionary enum_def enum_defs group_def group_defs header header_tok
ident idents message_defs module qual section sections.
Terminals
avp_types avp_vendor_id codecs custom_types define enum grouped
id inherits messages name prefix vendor
number word
'{' '}' '<' '>' '[' ']' '*' '::=' ':' ',' '-'
code
'answer-message'
'AVP' 'AVP-Header'
'Diameter' 'Diameter-Header' 'Header'
'REQ' 'PXY' 'ERR'.
Rootsymbol dictionary.
Endsymbol '$end'.
%% ===========================================================================
dictionary -> sections : '$1'.
sections -> '$empty' : [].
sections -> section sections : ['$1' | '$2'].
section -> name ident : ['$1', '$2'].
section -> prefix ident : ['$1', '$2'].
section -> id number : ['$1', '$2'].
section -> vendor number ident : ['$1', '$2', '$3'].
section -> inherits module avp_names : ['$1', '$2' | '$3'].
section -> avp_types avp_defs : ['$1' | '$2'].
section -> avp_vendor_id number avp_names : ['$1', '$2' | '$3'].
section -> custom_types module avp_names : ['$1', '$2' | '$3'].
section -> codecs module avp_names : ['$1', '$2' | '$3'].
section -> messages message_defs : ['$1' | '$2'].
section -> grouped group_defs : ['$1' | '$2'].
section -> enum ident enum_defs : ['$1', '$2' | '$3'].
section -> define ident enum_defs : ['$1', '$2' | '$3'].
%% =====================================
module -> ident : '$1'.
avp_names -> idents : '$1'. %% Note: not 'AVP'
avp_defs -> '$empty' : [].
avp_defs -> avp_def avp_defs : ['$1' | '$2'].
avp_def -> ident number avp_type avp_flags : ['$1', '$2', '$3', '$4'].
avp_type -> ident : '$1'.
idents -> '$empty' : [].
idents -> ident idents : ['$1' | '$2'].
avp_flags -> '-' :
{_, Lineno} = '$1',
{word, Lineno, ""}.
avp_flags -> ident :
'$1'.
%% Could support lowercase here if there's a use for distinguishing
%% between Must and Should in the future in deciding whether or not
%% to set a flag.
ident -> word : '$1'.
%% Don't bother mapping reserved words to make these usable in this
%% context. That an AVP can't be named Diameter-Header is probably no
%% great loss, and that it can't be named AVP may even save someone
%% from themselves. (Temporarily at least.)
group_defs -> '$empty' : [].
group_defs -> group_def group_defs : ['$1' | '$2'].
message_defs -> '$empty' : [].
message_defs -> command_def message_defs : ['$1' | '$2'].
enum_defs -> '$empty' : [].
enum_defs -> enum_def enum_defs : ['$1' | '$2'].
enum_def -> ident number : ['$1', '$2'].
%% =====================================
%% 3.2. Command Code ABNF specification
%%
%% Every Command Code defined MUST include a corresponding ABNF
%% specification, which is used to define the AVPs that MUST or MAY be
%% present when sending the message. The following format is used in
%% the definition:
%% command-def = <command-name> "::=" diameter-message
%%
%% command-name = diameter-name
%%
%% diameter-name = ALPHA *(ALPHA / DIGIT / "-")
%%
%% diameter-message = header [ *fixed] [ *required] [ *optional]
%% answer-message is a special case.
command_def -> 'answer-message' '::=' '<' header_tok ':' code
',' 'ERR' '[' 'PXY' ']' '>'
avps
: ['$1', false | '$13'].
command_def -> diameter_name '::=' header avps
: ['$1', '$3' | '$4'].
%% Ensure the order fixed/required/optional by semantic checks rather
%% than grammatically since the latter requires more lookahead: don't
%% know until after a leading qual which of the three it is that's
%% being parsed.
diameter_name -> ident : '$1'.
%% header = "<" "Diameter Header:" command-id
%% [r-bit] [p-bit] [e-bit] [application-id] ">"
%%
%% command-id = 1*DIGIT
%% ; The Command Code assigned to the command
%%
%% r-bit = ", REQ"
%% ; If present, the 'R' bit in the Command
%% ; Flags is set, indicating that the message
%% ; is a request, as opposed to an answer.
%%
%% p-bit = ", PXY"
%% ; If present, the 'P' bit in the Command
%% ; Flags is set, indicating that the message
%% ; is proxiable.
%%
%% e-bit = ", ERR"
%% ; If present, the 'E' bit in the Command
%% ; Flags is set, indicating that the answer
%% ; message contains a Result-Code AVP in
%% ; the "protocol error" class.
%%
%% application-id = 1*DIGIT
header -> '<' header_tok ':' command_id bits application_id '>'
: ['$4', '$5', '$6'].
command_id -> number : '$1'.
%% Accept both the form of the base definition and the typo (fixed in
%% 3588bis) of the grammar.
header_tok -> 'Diameter' 'Header'.
header_tok -> 'Diameter-Header'.
bits -> '$empty' : [].
bits -> ',' bit bits : ['$2' | '$3'].
%% ERR only makes sense for answer-message so don't allow it here
%% (despite 3588).
bit -> 'REQ' : '$1'.
bit -> 'PXY' : '$1'.
application_id -> '$empty' : false.
application_id -> number : '$1'.
%% fixed = [qual] "<" avp-spec ">"
%% ; Defines the fixed position of an AVP
%%
%% required = [qual] "{" avp-spec "}"
%% ; The AVP MUST be present and can appear
%% ; anywhere in the message.
%%
%% optional = [qual] "[" avp-name "]"
%% ; The avp-name in the 'optional' rule cannot
%% ; evaluate to any AVP Name which is included
%% ; in a fixed or required rule. The AVP can
%% ; appear anywhere in the message.
%% ;
%% ; NOTE: "[" and "]" have a slightly different
%% ; meaning than in ABNF (RFC 5234]). These braces
%% ; cannot be used to express optional fixed rules
%% ; (such as an optional ICV at the end). To do this,
%% ; the convention is '0*1fixed'.
avps -> '$empty' : [].
avps -> avp avps : ['$1' | '$2'].
avp -> avp_ref : [false | '$1'].
avp -> qual avp_ref : ['$1' | '$2'].
avp_ref -> '<' avp_spec '>' : [$<, '$2'].
avp_ref -> '{' avp_name '}' : [${, '$2'].
avp_ref -> '[' avp_name ']' : [$[, '$2'].
%% Note that required can be an avp_name, not just avp_spec. 'AVP'
%% is specified as required by Failed-AVP for example.
%% qual = [min] "*" [max]
%% ; See ABNF conventions, RFC 5234 Section 4.
%% ; The absence of any qualifiers depends on
%% ; whether it precedes a fixed, required, or
%% ; optional rule. If a fixed or required rule has
%% ; no qualifier, then exactly one such AVP MUST
%% ; be present. If an optional rule has no
%% ; qualifier, then 0 or 1 such AVP may be
%% ; present. If an optional rule has a qualifier,
%% ; then the value of min MUST be 0 if present.
%%
%% min = 1*DIGIT
%% ; The minimum number of times the element may
%% ; be present. If absent, the default value is zero
%% ; for fixed and optional rules and one for required
%% ; rules. The value MUST be at least one for for
%% ; required rules.
%%
%% max = 1*DIGIT
%% ; The maximum number of times the element may
%% ; be present. If absent, the default value is
%% ; infinity. A value of zero implies the AVP MUST
%% ; NOT be present.
qual -> number '*' number : {'$1', '$3'}.
qual -> number '*' : {'$1', true}.
qual -> '*' number : {true, '$2'}.
qual -> '*' : true.
%% avp-spec = diameter-name
%% ; The avp-spec has to be an AVP Name, defined
%% ; in the base or extended Diameter
%% ; specifications.
avp_spec -> diameter_name : '$1'.
%% avp-name = avp-spec / "AVP"
%% ; The string "AVP" stands for *any* arbitrary AVP
%% ; Name, not otherwise listed in that command code
%% ; definition. Addition this AVP is recommended for
%% ; all command ABNFs to allow for extensibility.
avp_name -> 'AVP' : '$1'.
avp_name -> avp_spec : '$1'.
%% The following is a definition of a fictitious command code:
%%
%% Example-Request ::= < Diameter Header: 9999999, REQ, PXY >
%% { User-Name }
%% * { Origin-Host }
%% * [ AVP ]
%% =====================================
%% 4.4. Grouped AVP Values
%%
%% The Diameter protocol allows AVP values of type 'Grouped'. This
%% implies that the Data field is actually a sequence of AVPs. It is
%% possible to include an AVP with a Grouped type within a Grouped type,
%% that is, to nest them. AVPs within an AVP of type Grouped have the
%% same padding requirements as non-Grouped AVPs, as defined in Section
%% 4.
%%
%% The AVP Code numbering space of all AVPs included in a Grouped AVP is
%% the same as for non-grouped AVPs. Receivers of a Grouped AVP that
%% does not have the 'M' (mandatory) bit set and one or more of the
%% encapsulated AVPs within the group has the 'M' (mandatory) bit set
%% MAY simply be ignored if the Grouped AVP itself is unrecognized. The
%% rule applies even if the encapsulated AVP with its 'M' (mandatory)
%% bit set is further encapsulated within other sub-groups; i.e. other
%% Grouped AVPs embedded within the Grouped AVP.
%%
%% Every Grouped AVP defined MUST include a corresponding grammar, using
%% ABNF [RFC5234] (with modifications), as defined below.
%% grouped-avp-def = <name> "::=" avp
%%
%% name-fmt = ALPHA *(ALPHA / DIGIT / "-")
%%
%% name = name-fmt
%% ; The name has to be the name of an AVP,
%% ; defined in the base or extended Diameter
%% ; specifications.
%%
%% avp = header [ *fixed] [ *required] [ *optional]
group_def -> ident '::=' avp_header avps : ['$1', '$3' | '$4'].
%% header = "<" "AVP-Header:" avpcode [vendor] ">"
%%
%% avpcode = 1*DIGIT
%% ; The AVP Code assigned to the Grouped AVP
%%
%% vendor = 1*DIGIT
%% ; The Vendor-ID assigned to the Grouped AVP.
%% ; If absent, the default value of zero is
%% ; used.
avp_header -> '<' avp_header_tok ':' avp_code avp_vendor '>'
: ['$4', '$5'].
avp_header_tok -> 'AVP-Header'.
avp_header_tok -> 'AVP' 'Header'.
avp_code -> number : '$1'.
avp_vendor -> '$empty' : false.
avp_vendor -> number : '$1'.
