| Internet Engineering Task Force | M. Veillette, Ed. |
| Internet-Draft | Trilliant Networks Inc. |
| Intended status: Standards Track | A. Pelov, Ed. |
| Expires: December 25, 2016 | Acklio |
| A. Somaraju | |
| Tridonic GmbH & Co KG | |
| R. Turner | |
| Landis+Gyr | |
| A. Minaburo | |
| Acklio | |
| June 23, 2016 |
CBOR Encoding of Data Modeled with YANG
draft-ietf-core-yang-cbor-01
This document defines encoding rules for serializing configuration data, state data, RPC input and RPC output, Action input, Action output and notifications defined within YANG modules using the Concise Binary Object Representation (CBOR) [RFC7049].
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 25, 2016.
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
The specification of the YANG 1.1 data modelling language [I-D.ietf-netmod-rfc6020bis] defines only an XML encoding for data instances, i.e. contents of configuration datastores, state data, RPC inputs and outputs, action inputs and outputs, and event notifications.
A new set of encoding rules has been defined to allow the use of the same data models in environments based on the JavaScript Object Notation (JSON) Data Interchange Format [RFC7159]. This is accomplished in the JSON Encoding of Data Modeled with YANG specification [I-D.ietf-netmod-yang-json].
The aim of this document is to define a set of encoding rules for the Concise Binary Object Representation (CBOR) [RFC7049]. The resulting encoding is more compact compared to XML and JSON and more suitable for Constrained Nodes and/or Constrained Networks as defined by [RFC7228].
The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in [RFC2119].
The following terms are defined in [I-D.ietf-netmod-rfc6020bis]:
The following terms are defined in [I-D.ietf-netmod-yang-json]:
The following term is defined in [I-D.vanderstok-core-comi]:
This specification also makes use of the following terminology:
Within this document, CBOR binary contents are represented using an equivalent textual form called CBOR diagnostic notation as defined in [RFC7049] section 6. This notation is used strictly for documentation purposes and is never used in the data serialization.
| CBOR content | CBOR type | Diagnostic notation | Example | CBOR encoding |
|---|---|---|---|---|
| Unsigned integer | 0 | Decimal digits | 123 or +123 | 18 7b |
| Negative integer | 1 | Decimal digits prefixed by a minus sign | -123 | 38 7a |
| Byte string | 2 | Hexadecimal value enclosed between single quotes and prefixed by an ‘h’ | h’f15c’ | 42 f15c |
| Text string | 3 | String of Unicode characters enclosed between double quotes | “txt” | 63 747874 |
| Array | 4 | Comma-separated list of values within square brackets | [ 1, 2 ] | 82 01 02 |
| Map | 5 | Comma-separated list of key : value pairs within curly braces | { 1: 123, 2: 456 } | a2 01187b 021901c8 |
| Boolean | 7/20 | false | false | f4 |
| 7/21 | true | true | f5 | |
| Null | 7/22 | null | null | f6 |
| Not assigned | 7/23 | undefined | undefined | f7 |
The following extensions to the CBOR diagnostic notation are supported:
This document defines CBOR encoding rules for YANG schema trees and their subtrees.
Basic schema nodes such as leaf, leaf-list, list, anydata and anyxml can be encoded standalone. In this case, only the value of this schema node is encoded in CBOR. Identification of this value need to be provided by some external means when needed.
A collection such as container, list instance, notification, RPC input, RPC output, action input and action output is serialized using a CBOR map in which each child schema node is encoded using a key and a value. This specification supports three type of keys; SID as defined in [I-D.somaraju-core-sid], member names as defined in [I-D.ietf-netmod-yang-json] and YANG hash as defined by [I-D.vanderstok-core-comi]. Each of these key type is encoded using a specific CBOR type which allows their interpretation during the deserialization process. The end user of this mapping specification can mandate the use of a specific key type or a specific subset of key types.
In order to minimize the size of the encoded data, the proposed mapping avoid any unnecessary meta-information beyond those natively supported by CBOR. For instance, CBOR tags are used sorely in the case of the union datatype to distinguish explicitly the use of different YANG datatypes encoded using the same CBOR major type.
It is expected that entities generating and decoding CBOR contents have enough knowledge about the information processed in order to perform the expected task without the need of such extra meta-information. The CoAP Content-Format Option, or an HTTP Content-Type header field, conveys that the data is YANG-encoded CBOR in the first place.
Schema node instances defined using the YANG modeling language are encoded using CBOR [RFC7049] based on the rules defined in this section. We assume that the reader is already familiar with both YANG [I-D.ietf-netmod-rfc6020bis] and CBOR [RFC7049].
Leafs MUST be encoded based on the encoding rules specified in Section 5.
Collections such as containers, list instances, notifications, RPC inputs, RPC outputs, action inputs and action outputs MUST be encoded using a CBOR map data item (major type 5). A map is comprised of pairs of data items, with each data item consisting of a key and a value. Each key within the CBOR map is set to a data node identifier, each value is set to the value of this data node instance.
This specification supports three type of keys; SID as defined in [I-D.somaraju-core-sid], member names as defined in [I-D.ietf-netmod-yang-json] and YANG hash as defined by [I-D.vanderstok-core-comi].
SIDs as keys
Keys implemented using SIDs MUST be encoded using a CBOR unsigned integer (major type 0) or CBOR signed integer (major type 1), depending on the actual value. Keys are set to the delta of the associated SID, delta values are computed as follows:
Member names as keys
Keys implemented using member names MUST be encoded using a CBOR text string data item (major type 3). A namespace-qualified member name MUST be used for all members of a top-level collection, and then also whenever the namespaces of the schema node and its parent are different. In all other cases, the simple form of the member name MUST be used. Member names and namespaces are defined in [I-D.ietf-netmod-yang-json] section 4.
YANG hashes as keys
Keys implemented using YANG hashes MUST be encoded using a CBOR byte string data item (major type 2).
Values MUST be encoded using the appropriate rules defined in Section 4 and Section 5.
Definition example [RFC7317]:
typedef date-and-time {
type string {
pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z|[\+\-]
\d{2}:\d{2})';
}
}
container system {
leaf hostname {
type inet:domain-name;
container clock {
leaf current-datetime {
type date-and-time;
}
leaf boot-datetime {
type date-and-time;
}
}
}
SIDs example
This example is encoded using the SIDs defined in [I-D.somaraju-core-sid] Appendix C.
CBOR diagnostic notation:
{
1708 : { # clock
+2 : "2015-10-02T14:47:24Z-05:00", # current-datetime, SID 1710
+1 : "2015-09-15T09:12:58Z-05:00" # boot-datetime, SID 1709
}
}
CBOR encoding:
a1 # map(1)
19 06ac # unsigned(1708)
a2 # map(2)
02 # unsigned(2)
78 1a # text(26)
323031352d31302d30325431343a34373a32345a2d30353a3030
01 # unsigned(1)
78 1a # text(26)
323031352d30392d31355430393a31323a35385a2d30353a3030
Member names example
CBOR diagnostic notation:
{
"ietf-system:clock" : {
"current-datetime" : "2015-10-02T14:47:24Z-05:00",
"boot-datetime" : "2015-09-15T09:12:58Z-05:00"
}
}
CBOR encoding:
a1 # map(1)
71 # text(17)
696574662d73797374656d3a636c6f636b # "ietf-system:clock"
a2 # map(2)
70 # text(16)
63757272656e742d6461746574696d65 # "current-datetime"
78 1a # text(26)
323031352d31302d30325431343a34373a32345a2d30353a3030
6d # text(13)
626f6f742d6461746574696d65 # "boot-datetime"
78 1a # text(26)
323031352d30392d31355430393a31323a35385a2d30353a3030
YANG Hashes example
CBOR diagnostic notation:
{
h'334c67d9' : { # clock
h'047c468b' : "2015-10-02T14:47:24Z-05:00", # current-datetime
h'2fe1a167' : "2015-09-15T09:12:58Z-05:00" # boot-datetime
}
}
CBOR encoding:
a1 # map(1)
44 # bytes(4)
334c67d9
a2 # map(2)
44 # bytes(4)
047c468b
78 1a # text(26)
323031352d31302d30325431343a34373a32345a2d30353a3030
44 # bytes(4)
2fe1a167
78 1a # text(26)
323031352d30392d31355430393a31323a35385a2d30353a3030
A leaf-list MUST be encoded using a CBOR array data item (major type 4). Each entry of this array MUST be encoded using the rules defined by the YANG type specified.
Definition example [RFC7317]:
typedef domain-name {
type string {
length "1..253";
pattern '((([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9].)
*([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.?
)|\.';
}
}
leaf-list search {
type domain-name;
ordered-by user;
}
CBOR diagnostic notation: [ “ietf.org”, “ieee.org” ]
CBOR encoding: 82 68 696574662e6f7267 68 696565652e6f7267
A list MUST be encoded using a CBOR array data item (major type 4). Each list instance within this CBOR array is encoded using a CBOR map data item (major type 5) based on the same rules as a YANG container as defined in Section 4.2.
Definition example [RFC7317]:
list server {
key name;
leaf name {
type string;
}
choice transport {
case udp {
container udp {
leaf address {
type host;
mandatory true;
}
leaf port {
type port-number;
}
}
}
}
leaf association-type {
type enumeration {
enum server;
enum peer;
enum pool;
}
default server;
}
leaf iburst {
type boolean;
default false;
}
leaf prefer {
type boolean;
default false;
}
}
SIDs example
SIDs used in this example are defined in [I-D.somaraju-core-sid] Appendix C. It is important to note that the protocol or method using this mapping may carry a parent SID or may have the knowledge of this parent SID based on its context. In these cases, delta encoding can be performed based on this parent SID which minimizes the size of the encoded data.
CBOR diagnostic notation:
[
{
1746 : "NRC TIC server", # name
1748 : { # udp
+1 : "tic.nrc.ca", # address, SID 1749
+2 : 123 # port, SID 1750
},
1744 : 0, # association-type
1745 : false, # iburst
1747 : true # prefer
},
{
1746 : "NRC TAC server", # name
1748 : { # udp
+1 : "tac.nrc.ca" # address, SID 1749
}
}
]
CBOR encoding:
82 # array(2)
a5 # map(5)
19 06d2 # unsigned(1746)
6e # text(14)
4e52432054494320736572766572 # "NRC TIC server"
19 06d4 # unsigned(1748)
a2 # map(2)
01 # unsigned(1)
6a # text(10)
7469632e6e72632e6361 # "tic.nrc.ca"
02 # unsigned(2)
18 7b # unsigned(123)
19 06d0 # unsigned(1744)
00 # unsigned(0)
19 06d1 # unsigned(1745)
f4 # primitive(20)
19 06d3 # unsigned(1747)
f5 # primitive(21)
a2 # map(2)
19 06d2 # unsigned(1746)
6e # text(14)
4e52432054414320736572766572 # "NRC TAC server"
19 06d4 # unsigned(1748)
a1 # map(1)
01 # unsigned(1)
6a # text(10)
7461632e6e72632e6361 # "tac.nrc.ca"
Member names example
CBOR diagnostic notation:
[
{
"ietf-system:name" : "NRC TIC server",
"ietf-system:udp" : {
"address" : "tic.nrc.ca",
"port" : 123
},
"ietf-system:association-type" : 0,
"ietf-system:iburst" : false,
"ietf-system:prefer" : true
},
{
"ietf-system:name" : "NRC TAC server",
"ietf-system:udp" : {
"address" : "tac.nrc.ca"
}
}
]
CBOR encoding:
82 # array(2)
a5 # map(5)
70 # text(16)
696574662d73797374656d3a6e616d65 # "ietf-system:name"
6e # text(14)
4e52432054494320736572766572 # "NRC TIC server"
6f # text(15)
696574662d73797374656d3a756470 # "ietf-system:udp"
a2 # map(2)
67 # text(7)
61646472657373 # "address"
6a # text(10)
7469632e6e72632e6361 # "tic.nrc.ca"
64 # text(4)
706f7274 # "port"
18 7b # unsigned(123)
78 1c # text(28)
696574662d73797374656d3a6173736f63696174696f6e2d74797065
00 # unsigned(0)
72 # text(18)
696574662d73797374656d3a696275727374 # "ietf-system:iburst"
f4 # primitive(20)
72 # text(18)
696574662d73797374656d3a707265666572 # "ietf-system:prefer"
f5 # primitive(21)
a2 # map(2)
70 # text(16)
696574662d73797374656d3a6e616d65 # "ietf-system:name"
6e # text(14)
4e52432054414320736572766572 # "NRC TAC server"
6f # text(15)
696574662d73797374656d3a756470 # "ietf-system:udp"
a1 # map(1)
67 # text(7)
61646472657373 # "address"
6a # text(10)
7461632e6e72632e6361 # "tac.nrc.ca"
YANG hashes example
CBOR diagnostic notation:
[
{
h'06c32032' : "NRC TIC server", # name
h'11889c84' : { # udp
h'3158c529' : "tic.nrc.ca", # address
h'34492d05' : 123 # port
},
h'2c2c2ccf' : 0, # association-type
h'1058dc5d' : false, # iburst
h'390e346a' : true # prefer
},
{
h'06c32032' : "NRC TAC server", # name
h'11889c84' : { # udp
h'3158c529' : "tac.nrc.ca" # address
}
}
]
CBOR encoding:
82 # array(2)
a5 # map(5)
44 # bytes(4)
06c32032"
6e # text(14)
4e52432054494320736572766572 # "NRC TIC server"
44 # bytes(4)
11889c84 "
a2 # map(2)
44 # bytes(4)
3158c529
6a # text(10)
7469632e6e72632e6361 # "tic.nrc.ca"
44 # bytes(4)
34492d05
18 7b # unsigned(123)
44 # bytes(4)
2c2c2ccf
00 # unsigned(0)
44 # bytes(4)
1058dc5d
f4 # primitive(20)
44 # bytes(4)
390e346a
f5 # primitive(21)
a2 # map(2)
44 # bytes(4)
06c32032
6e # text(14)
4e52432054414320736572766572 # "NRC TAC server"
44 # bytes(4)
11889c84
a1 # map(1)
44 # bytes(4)
3158c529
6a # text(10)
7461632e6e72632e6361 # "tac.nrc.ca"
An anydata serves as a container for an arbitrary set of schema nodes that otherwise appear as normal YANG-modeled data. An anydata instance is encoded using the same rules as a container, i.e., CBOR map. The requirement that anydata content can be modeled by YANG implies the following:
An anyxml instance is encoded as a CBOR key/value pair. The key of the anyxml schema node MUST be a valid SID, member name or YANG hash but the value is unrestricted, i.e., the value can be any CBOR encoded content.
Leafs of type uint8, uint16, uint32 and uint64 MUST be encoded using a CBOR unsigned integer data item (major type 0).
Definition example [RFC7277]:
leaf mtu {
type uint16 {
range "68..max";
}
}
CBOR diagnostic notation: 1280
CBOR encoding: 19 0500
Leafs of type int8, int16, int32 and int64 MUST be encoded using either CBOR unsigned integer (major type 0) or CBOR signed integer (major type 1), depending on the actual value.
Definition example [RFC7317]:
leaf timezone-utc-offset {
type int16 {
range "-1500 .. 1500";
}
}
CBOR diagnostic notation: -300
CBOR encoding: 39 012b
f type decimal64 MUST be encoded using either CBOR unsigned integer (major type 0) or CBOR signed integer (major type 1), depending on the actual value. Leafs oThe position of the decimal point is defined by the fraction-digits YANG statement and is not available in the CBOR encoding.
Definition example [RFC7317]:
leaf my-decimal {
type decimal64 {
fraction-digits 2;
range "1 .. 3.14 | 10 | 20..max";
}
}
CBOR diagnostic notation: 257 (Represents decimal value 2.57)
CBOR encoding: 19 0101
Leafs of type string MUST be encoded using a CBOR text string data item (major type 3).
Definition example [RFC7223]:
leaf name {
type string;
}
CBOR diagnostic notation: “eth0”
CBOR encoding: 64 65746830
Leafs of type boolean MUST be encoded using a CBOR true (major type 7, additional information 21) or false data item (major type 7, additional information 20).
Definition example [RFC7317]:
leaf enabled {
type boolean;
}
CBOR diagnostic notation: true
CBOR encoding: f5
Leafs of type enumeration MUST be encoded using a CBOR unsigned integer (major type 0) or CBOR signed integer (major type 1), depending on the actual value. Enumeration values are either explicitly assigned using the YANG statement ‘value’ or automatically assigned based on the algorithm defined in [I-D.ietf-netmod-rfc6020bis] section 9.6.4.2.
Definition example [RFC7317]:
leaf oper-status {
type enumeration {
enum up { value 1; }
enum down { value 2; }
enum testing { value 3; }
enum unknown { value 4; }
enum dormant { value 5; }
enum not-present { value 6; }
enum lower-layer-down { value 7; }
}
}
CBOR diagnostic notation: 3 (Represents enumeration value ‘testing’)
CBOR encoding: 03
Leafs of type bits MUST be encoded using a CBOR byte string data item (major type 2). Bits position are either explicitly assigned using the YANG statement ‘position’ or automatically assigned based on the algorithm defined in [I-D.ietf-netmod-rfc6020bis] section 9.7.4.2.
Bits position 0 to 7 are assigned to the first byte within the byte string, bits 8 to 15 to the second byte, and subsequent bytes are assigned similarly. Within each byte, bits are assigned from least to most significant.
Definition example [I-D.ietf-netmod-rfc6020bis]:
leaf mybits {
type bits {
bit disable-nagle {
position 0;
}
bit auto-sense-speed {
position 1;
}
bit 10-Mb-only {
position 2;
}
}
}
CBOR diagnostic notation: h’05’ (Represents bits disable-nagle and 10-Mb-only set)
CBOR encoding: 41 05
Leafs of type binary MUST be encoded using a CBOR byte string data item (major type 2).
Definition example:
leaf aes128-key {
type binary {
length 16;
}
}
CBOR diagnostic notation: h’1f1ce6a3f42660d888d92a4d8030476e’
CBOR encoding: 50 1f1ce6a3f42660d888d92a4d8030476e
Leafs of type leafref MUST be encoded using the rules of the schema node referenced by the ‘path’ YANG statement.
Definition example [RFC7223]:
typedef interface-state-ref {
type leafref {
path "/interfaces-state/interface/name";
}
}
container interfaces-state {
list interface {
key "name";
leaf name {
type string;
}
leaf-list higher-layer-if {
type interface-state-ref;
}
}
}
CBOR diagnostic notation: “eth1”
CBOR encoding: 64 65746831
This specification supports two approaches for encoding identityref, a SID as defined in [I-D.somaraju-core-sid] or a name as defined in [I-D.ietf-netmod-yang-json] section 6.8.
SIDs as identityref
SIDs are globally unique and can be used as identityref. This approach is both compact and simple to implement. When SIDs are used, identityref MUST be encoded using a CBOR unsigned integer data item (major type 0) or CBOR signed integer (major type 1), depending on the actual value. The value represents the delta between the SID of the identity assigned to the leaf and the SID of the base identity defined for this leaf.
Name as identityref
Alternatively, an identityref may be encoded using a name as defined in [I-D.ietf-netmod-yang-json] section 6.8. When names are used, identityref MUST be encoded using a CBOR text string data item (major type 3). If the identity is defined in another module than the leaf node containing the identityref value, the namespace-qualified form MUST be used. Otherwise, both the simple and namespace-qualified forms are permitted.
Definition example [RFC7317]:
identity radius-authentication-type {
description
"Base identity for RADIUS authentication types.";
}
identity radius-chap {
base radius-authentication-type;
}
identity radius-pap {
base radius-authentication-type;
}
leaf authentication-type {
type identityref {
base radius-authentication-type;
}
}
SIDs as identityref
This example represents the encoding of identity “radius-pap” (SID 1705) assuming the base identity “radius-authentication-type” (SID 1703).
CBOR diagnostic notation: 2
CBOR encoding: 02
Name as identityref
CBOR diagnostic notation: “ietf-system:radius-pap”
CBOR encoding: 76 696574662d73797374656d3a7261646975732d706170
Leafs of type empty MUST be encoded using the CBOR null value (major type 7, additional information 22).
Definition example [RFC7277]:
leaf is-router {
type empty;
}
CBOR diagnostic notation: null
CBOR encoding: f6
Leafs of type union MUST be encoded using the rules associated with one of the types listed. When used in a union, the following YANG datatypes are prefixed by CBOR tag to avoid confusion between different YANG datatypes encoded using the same CBOR major type.
See Section 7.1 for more information about these CBOR tags.
Definition example [RFC7317]:
typedef ipv4-address {
type string {
pattern '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}
([0-9][1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(%[\p{N}
\p{L}]+)?';
}
}
typedef ipv6-address {
type string {
pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}((([0-9a
-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|(((25[0-5]|2[0-4][0
-9]|[01]?[0-9]?[0-9])\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0
-9]?[0-9])))(%[\p{N}\p{L}]+)?';
pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|((([^:]+:)*[^:]+)
?::(([^:]+:)*[^:]+)?)(%.+)?';
}
}
typedef ip-address {
type union {
type ipv4-address;
type ipv6-address;
}
}
leaf address {
type inet:ip-address;
}
CBOR diagnostic notation: “2001:db8:a0b:12f0::1”
CBOR encoding: 74 323030313a6462383a6130623a313266303a3a31
This specification supports three approaches for encoding an instance-identifier, one based on SIDs as defined in [I-D.somaraju-core-sid], one based on names as defined in [I-D.ietf-netmod-yang-json] section 6.13 and one based on YANG hashes as defined in [I-D.vanderstok-core-comi].
SIDs as instance-identifier
SIDs uniquely identify a data node. For a single instance data node, the SID is sufficient to identify this instance. For a multi-instance data node, a SID is combined with the list key(s) to identify each instance of this data node within the YANG list(s).
Single instance data nodes MUST be encoded using a CBOR unsigned integer data item (major type 0) and set to the targeted data node SID.
Multi-instances data nodes MUST be encoded using a CBOR array data item (major type 4) containing the following entries:
Names as instance-identifier
The use of names as instance-identifier is defined in [I-D.ietf-netmod-yang-json] section 6.11. The resulting xpath MUST be encoded using a CBOR text string data item (major type 3).
YANG hashes as instance-identifier
When YANG hashes are used, xpath can be compressed based on the method defined by [I-D.vanderstok-core-comi] sections 4.1.4.1 and 4.1.4.2. The resulting hash MUST be encoded using a CBOR byte string data item (major type 2).
Definition example [RFC7317]:
container system {
leaf contact {
type string;
}
leaf hostname {
type inet:domain-name;
}
}
First example based on SID
In this example, a field of type instance-identifier identifies the data node “/system/contact” (SID 1728).
1728
CBOR encoding:
19 06c0
First example based on name
Same example as above based on names.
"/ietf-system:system/contact"
CBOR encoding:
78 1c 2f20696574662d73797374656d3a73797374656d2f636f6e74616374
First example based on YANG hash
Same example assuming data node “/system/contact” is associated to YANG hash 0x09b06d17 or “JsG0X” in base64.
CBOR diagnostic notation:
"/JsG0X"
CBOR encoding:
66 2f4a73473058
Definition example [RFC7317]:
list user {
key name;
leaf name {
type string;
}
leaf password {
type ianach:crypt-hash;
}
list authorized-key {
key name;
leaf name {
type string;
}
leaf algorithm {
type string;
}
leaf key-data {
type binary;
}
}
Second example based on SID
In this example, a field of type instance-identifier identify the data node “/system/authentication/user/authorized-key/key-data” (SID 1721) for the user name “bob” and the authorized-key name “admin”.
CBOR diagnostic notation:
[1721, "bob", "admin"]
CBOR encoding:
83 # array(3)
19 06b9 # unsigned(1721)
63 # text(3)
626f62 # "bob"
65 # text(5)
61646d696e # "admin"
Second example based on name
Same example as above based on names.
CBOR diagnostic notation:
"/ietf-system:system/authentication/user[name='bob']/authorized-key [name='admin']/key-data"
CBOR encoding:
78 59 2f696574662d73797374656d3a73797374656d2f61757468656e74696361 74696f6e2f757365725b6e616d653d27626f62275d2f617574686f72697a 65642d6b65795b6e616d653d2761646d696e275d2f6b65792d64617461
Second example based on YANG hash
Same example assuming data node “/ietf-system:system/authentication/user/authorized-key/key-data” is associated to YANG hash 0x0d6e7afb or “Nbnr7” in base64.
CBOR diagnostic notation:
"/Nbnr7?keys=\"bob\",\"admin\""
CBOR encoding:
78 19 2f4e626e72373f6b6579733d22626f62222c2261646d696e22
Third example based on SID
This third example identify an instance within the list “/system/authentication/user” (SID 1717) corresponding to the user name “jack”.
CBOR diagnostic notation:
[1717, "jack"]
CBOR encoding:
82 # array(2)
19 06b5 # unsigned(1717)
64 # text(4)
6a61636b # "jack"
Third example based on name
Same example as above based on names.
CBOR diagnostic notation:
"/ietf-system:system/authentication/user[name='bob']"
CBOR encoding:
78 33 2f696574662d73797374656d3a73797374656d2f61757468656e74696361 74696f6e2f757365725b6e616d653d27626f62275d
Third example based on YANG hash
Same example assuming data node “/ietf-system:system/authentication/user” is associated to YANG hash 0x2677c6c1 or “md8bB” in base64.
CBOR diagnostic notation:
"/md8bB?keys=\"bob\""
CBOR encoding:
71 2f6d643862423f6b6579733d22626f6222
The security considerations of [RFC7049] and [I-D.ietf-netmod-rfc6020bis] apply.
This document defines an alternative encoding for data modeled in the YANG data modeling language. As such, this encoding does not contribute any new security issues in addition of those identified for the specific protocol or context for which it is used.
To minimize security risks, software on the receiving side SHOULD reject all messages that do not comply to the rules of this document and reply with an appropriate error message to the sender.
This specification requires the assignment of CBOR tags for the following YANG datatypes. These tags are added to the Tags Registry as defined in section 7.2 of [RFC7049].
| Tag | Data Item | Semantics | Reference |
|---|---|---|---|
| 40 | bits | YANG bits datatype | RFC XXXX |
| 41 | decimal64 | YANG decimal64 datatype | RFC XXXX |
| 42 | enumeration | YANG enumeration datatype | RFC XXXX |
| 43 | identityref | YANG identityref datatype | RFC XXXX |
| 44 | instance-identifier | YANG instance-identifier datatype | RFC XXXX |
// RFC Ed.: update Tag values using allocated tags if needed and remove this note // RFC Ed.: replace XXXX with RFC number and remove this note
This document has been largely inspired by the extensive works done by Andy Bierman and Peter van der Stok on [I-D.vanderstok-core-comi]. [I-D.ietf-netmod-yang-json] has also been a critical input to this work. The authors would like to thank the authors and contributors to these two drafts.
The authors would also like to acknowledge the review, feedback, and comments from Ladislav Lhotka and Juergen Schoenwaelder.
| [I-D.ietf-netmod-rfc6020bis] | Bjorklund, M., "The YANG 1.1 Data Modeling Language", Internet-Draft draft-ietf-netmod-rfc6020bis-14, June 2016. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC7049] | Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, October 2013. |
| [I-D.ietf-netmod-yang-json] | Lhotka, L., "JSON Encoding of Data Modeled with YANG", Internet-Draft draft-ietf-netmod-yang-json-10, March 2016. |
| [I-D.somaraju-core-sid] | Somaraju, A., Veillette, M., Pelov, A., Turner, R. and A. Minaburo, "Structure Identifier (SID)", Internet-Draft draft-somaraju-core-sid-00, March 2016. |
| [I-D.vanderstok-core-comi] | Stok, P. and A. Bierman, "CoAP Management Interface", Internet-Draft draft-vanderstok-core-comi-09, March 2016. |
| [RFC7159] | Bray, T., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 2014. |
| [RFC7223] | Bjorklund, M., "A YANG Data Model for Interface Management", RFC 7223, DOI 10.17487/RFC7223, May 2014. |
| [RFC7228] | Bormann, C., Ersue, M. and A. Keranen, "Terminology for Constrained-Node Networks", RFC 7228, DOI 10.17487/RFC7228, May 2014. |
| [RFC7277] | Bjorklund, M., "A YANG Data Model for IP Management", RFC 7277, DOI 10.17487/RFC7277, June 2014. |
| [RFC7317] | Bierman, A. and M. Bjorklund, "A YANG Data Model for System Management", RFC 7317, DOI 10.17487/RFC7317, August 2014. |