JMAP Blob management extension
draft-ietf-jmap-blob-03
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (jmap WG) | |
|---|---|---|---|
| Author | Bron Gondwana | ||
| Last updated | 2021-10-16 | ||
| Replaces | draft-gondwana-jmap-blob | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text htmlized pdfized bibtex | ||
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draft-ietf-jmap-blob-03
JMAP B. Gondwana, Ed.
Internet-Draft Fastmail
Updates: 8620 (if approved) 16 October 2021
Intended status: Standards Track
Expires: 19 April 2022
JMAP Blob management extension
draft-ietf-jmap-blob-03
Abstract
The JMAP base protocol (RFC8620) provides the ability to upload and
download arbitrary binary data via HTTP POST and GET on defined
endpoint. This binary data is called a "Blob".
This extension adds additional ways to create and access Blobs, by
making inline method calls within a standard JMAP request.
This extension also adds a reverse lookup mechanism to discover where
blobs are referenced within other data types.
Status of This Memo
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-
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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 19 April 2022.
Copyright Notice
Copyright (c) 2021 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 (https://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
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used In This Document . . . . . . . . . . . . . . 3
3. Addition to the Capabilities Object . . . . . . . . . . . . . 3
3.1. urn:ietf:params:jmap:blob . . . . . . . . . . . . . . . . 3
4. Blob Methods . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Blob/set . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1.1. create . . . . . . . . . . . . . . . . . . . . . . . 4
4.1.2. update . . . . . . . . . . . . . . . . . . . . . . . 6
4.1.3. destroy . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Blob/get . . . . . . . . . . . . . . . . . . . . . . . . 7
4.3. Blob/lookup . . . . . . . . . . . . . . . . . . . . . . . 9
5. Security considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 11
6.1. JMAP Capability registration for "blob" . . . . . . . . . 11
6.2. JMAP Error Codes Registration for "unknownDataType" . . . 11
6.3. Creation of "JMAP Data Types" Registry . . . . . . . . . 12
7. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
9. Normative References . . . . . . . . . . . . . . . . . . . . 14
10. Informative References . . . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
Sometimes JMAP ([RFC8620]) interactions require creating a Blob and
then referencing it. In the same way that IMAP Literals ([RFC7888])
were extended to reduce roundtrips for simple data, embedding simple
small blobs into the JMAP method stream can reduce roundtrips.
Likewise, when fetching an object, it can be useful to also fetch the
raw content of that object without a separate roundtrip.
Where JMAP is being proxied through a system which applies additional
access restrictions, it can be useful to be able to see where a blob
is referenced in order to decide whether to allow it to be
downloaded.
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2. Conventions Used In This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Addition to the Capabilities Object
The capabilities object is returned as part of the JMAP Session
object; see [RFC8620], Section 2.
This document defines an additional capability URI.
3.1. urn:ietf:params:jmap:blob
This represents support for additional API methods on the Blob
datatype.
The value of this property in the JMAP session "capabilities"
property is an empty object.
The value of this property in an account's "accountCapabilities"
property is an object that MAY contain the following information on
server capabilities and permissions for that account:
* "maxSizeBlobSet": UnsignedInt - if set, gives the maximum size of
a blob that the server will allow you to create (including with
catenate). This SHOULD be the same as the RFC8620 value
maxSizeUpload.
* "maxCatenateItems": UnsignedInt - if set, gives the maximum number
of of CatenateSourceObjects allowed per creation in a Blob/set.
Servers SHOULD allow at least 64 items.
* "supportedTypeNames": [String] - an array of data type names that
are supported for Blob/lookup.
Example:
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{
"capabilities": {
...,
"urn:ietf:params:jmap:blob": {}
},
"accounts": {
"A13842": {
...
"accountCapabilities": {
"urn:ietf:params:jmap:blob": {
"maxSizeBlobSet": 50000000,
"maxCatenateItems": 100,
"supportedTypeNames" : [
"Mailbox",
"Thread",
"Email"
]
}
}
}
}
}
4. Blob Methods
A blob is a sequence of zero or more octets.
The JMAP base spec [RFC8620] defines the Blob/copy method, which is
unchanged by this specfication, and is selected by the
urn:ietf:params:jmap:core capability.
The following JMAP Methods are selected by the
urn:ietf:params:jmap:blob capability.
4.1. Blob/set
This is a standard JMAP set method.
4.1.1. create
*Properties:*
Exactly one of:
* data:asText: String|null
* data:asBase64: String|null
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* data:asHex: String|null
* catenate: [CatenateSourceObject] _list of one or more octet
sources in order_
Also:
* type: String|null _hint for media type of the data_
Result is: * id: Id _the blobId_ * type: String|null _media type as
given in the creation (if any); or detected from content; or null_ *
size: UnsignedInt _as per RFC8620 - the size of the blob in Octets_
Any other properties identical to those that would be returned in the
JSON response of the RFC8620 upload endpoint.
CatenateSourceObject:
Exactly one of:
* data:asText: String|null
* data:asBase64: String|null
* data:asHex: String|null
or a blobId source:
* blobId: Id
* offset: UnsignedInt|null _may be zero_
* length: UnsignedInt|null _must not be zero_
If null then offset is assumed to be zero. If null then length is
the remaining octets in the blob. If the range can not be fully
satisfied (i.e. extends past the end of the data in the blob) then
the catenate itself is invalid and results in a notCreated response
for this creation id.
If the data properties or catenate properties have any invalid
references or invalid data contained in them, the server MUST NOT
guess as to the user's intent, and MUST reject the creation and
return a notCreated response for that creation id.
Likewise, invalid data in the base64 or hex fields is an error and
must result in a notCreated response for this creation id.
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It is legal to create a blob by calling catenate with a single
CatenateSourceObject. Please note that a catenate source can not
contain additional sub-catenates, only data or blob sources.
A server SHOULD accept at least 64 catenate items.
4.1.2. update
It is not possible to update a Blob, so any update will result in a
notUpdated response.
4.1.3. destroy
If an uploaded Blob is not referenced by any persistent object, the
server SHOULD destroy the object. Some systems use a content-based
ID for blobs, so the server MAY respond destroyed and yet that blobId
still exist with the same content.
Example:
Method Call:
[ "Blob/set", {
"accountId" : "account1",
"create" : {
"1": {
"data:asBase64": "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKA
AAAA1BMVEX/AAAZ4gk3AAAAAXRSTlN/gFy0ywAAAApJRE
FUeJxjYgAAAAYAAzY3fKgAAAAASUVORK5CYII=",
"type" : "image/png"
},
},
}, "R1" ]
Response:
[ "Blob/set", {
"accountId" : "account1",
"created" : {
"1": {
"id" : "G4c6751edf9dd6903ff54b792e432fba781271beb",
"type" : "image/png",
"size" : 95
},
},
}, "R1" ]
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4.2. Blob/get
A standard JMAP get with two additional parameters:
* offset: UnsignedInt|null _start this many octets into the blob
data_
* length: UnsignedInt|null _return at most this many octets of the
blob data_
*Request Properties:*
Any of
* data:asText
* data:asBase64
* data:asHex
* data _selects data:asText if the content is valid UTF-8, or
data:asBase64_
* size
If not given, properties defaults to data and size.
*Result Properties:*
* data:asText: String|null _the raw octets of the selected range if
they are valid utf-8, otherwise null_
* data:asBase64: String _the base64 encoding of the selected range_
* data:asHex: String _the octets of the selected range encoded as
lowercase hexadecimal (0-9, a-f)_
* isEncodingProblem: Boolean _(default: false)_
* isTruncated: Boolean _(default: false)_
* size: UnsignedInt _the number of octets in the entire blob,
regardless of offset/length selectors_
The size value is always the number of octets in the entire blob,
regardless of offset and length.
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The data fields contain a representation of the octets within the
selected range that are present in the blob. If the octets selected
are not valid utf-8 (including truncating in the middle of a multi-
octet sequence) and data:asText or data is selected, then the key
isEncodingProblem is set to true and the data:asText value is null.
In the case where data was requested, this also causes data:asBase64
to be returned.
If the selected range requests data outside the blob (i.e. the
offset+length is larger than the blob) then the result is either just
the octets from the offset to the end of the blob, or an empty string
if the offset is past the end of the blob. Either way, the
isTruncated property in the result is set to true to tell the client
that the requested range could not be fully satisfied.
Example (a blob containing the string "The quick brown fox jumped
over the lazy dog!")
Method Call:
[ "Blob/get", {
"accountId" : "account1",
"ids" : [ "G6ec94756e3e046be78fcb33953b85b944e70673e", "not-a-blob" ],
"properties" : [ "data:asText", "data:asBase64",
"data:asHex", "size" ],
"offset" : 4,
"length" : 9
}, "R1" ]
Response:
[ "Blob/get", {
"accountId" : "account1",
"list" : [
{
"id" : "G6ec94756e3e046be78fcb33953b85b944e70673e",
"data:asText" : "quick bro",
"data:asBase64" : "cXVpY2sgYnJvCg==",
"data:asHex" : "717569636b2062726f",
"size" : 46
}
],
"notFound" : [ "not-a-blob" ]
}, "R1" ]
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4.3. Blob/lookup
Given a list of blobIds, this method does a reverse lookup in each of
the provided type names to find the list of Ids within that data type
which reference the provided blob.
The definition of reference is somewhat loosely defined, but roughly
means "you could discover this blobId by looking inside this object",
for example if a Mailbox contains an Email which references the
blobId, then it references that blobId. Likewise for a Thread.
*Parameters*
* accountId: "Id"
The id of the account used for the call.
* types: [String]
A list of type names from the "JMAP Data Types" registry. Only names
for which "Can Reference Blobs" is true may be specified, and the
capability which defines each type must also be used by the overall
JMAP request in which this method is called.
If a type name is not known by the server, or the associated
capability has not been requested, then the server returns an
"unknownDataType" error.
* ids: [Id]
A list of blobId values to be looked for.
*Response*
* list: [BlobInfo]
A list of BlobInfo objects.
*BlobInfo Object*
* id: Id
The Blob Identifier.
* types: String[Id List]
A map from type name to list of Ids of that data type (e.g. the name
"Email" maps to a list of emailIds)
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If a blob is not visible to a user at all, then the server SHOULD
return that blobId in the notFound array, however it may also return
an empty list for each type name, as it may not be able to know if
other data types do reference that blob.
e.g.
[ "Blob/lookup", {
"types": ["Mailbox", "Thread", "Email"],
"ids": ["Gd2f81008cf07d2425418f7f02a3ca63a8bc82003",
"not-a-blob"]
}, "R1" ]
Response:
[ "Blob/lookup", {
"list": [
{
"id": "Gd2f81008cf07d2425418f7f02a3ca63a8bc82003",
"types": {
"Mailbox": ["M54e97373", Mcbe6b662"],
"Thread": ["T1530616e"],
"Email": ["E16e70a73eb4", "E84b0930cf16"]
}
}
],
"notFound": ["not-a-blob"]
}, "R1"]
5. Security considerations
JSON parsers are not all consistent in handling non-UTF-8 data. JMAP
requires that all JSON data be UTF-8 encoded, so servers MUST either
return data:asBase64 or isEncodingProblem: true and modify the data
to be UTF-8 safe.
Servers MUST apply any access controls such that if the authenticated
user would be unable to discover the blobId by making queries, then
this fact can't be discovered via a Blob/lookup. For example, if an
Email exists in a Mailbox which the authenticated user does not have
access to see, then that emailId MUST not be returned in a lookup for
a blob which is referenced by that email.
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If a server might sometimes return all names empty rather than
putting a blobId in the notFound response to a Blob/get, then the
server SHOULD always return the same type of response, regardless of
whether a blob exists but the user can't access it, or doesn't exist
at all. This avoids leaking information about the existence of the
blob.
The server MUST NOT trust that the data given to a Blob/set is a well
formed instance of the specified media type, and if the server
attempts to parse the given blob, only hardened parsers designed to
deal with arbitrary untrusted data should be used. The server SHOULD
NOT reject data on the grounds that it is not a valid specimen of the
stated type.
6. IANA considerations
6.1. JMAP Capability registration for "blob"
IANA is requested to register the "blob" JMAP Capability as follows:
Capability Name: urn:ietf:params:jmap:blob
Specification document: this document
Intended use: common
Change Controller: IETF
Security and privacy considerations: this document, Section XXX
6.2. JMAP Error Codes Registration for "unknownDataType"
IANA is requested to register the "unknownDataType" JMAP Error Code
as follows:
JMAP Error Code: unknownDataType
Intended use: common
Change Controller: IETF
Reference: this document
Description: The server does not recognise this data type, or the
capability to enable it was not present.
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6.3. Creation of "JMAP Data Types" Registry
IANA is requested to create a new registry "JMAP Data Types" with the
initial content:
+================+=========+======+=====================================+=========+
|Type Name |Can |Can |Capability |Reference|
| |Reference|use | | |
| |Blobs |for | | |
| | |State | | |
| | |Change| | |
+================+=========+======+=====================================+=========+
|Core |No |No |urn:ietf:params:jmap:core |[RFC8620]|
+----------------+---------+------+-------------------------------------+---------+
|PushSubscription|No |No |urn:ietf:params:jmap:core |[RFC8620]|
+----------------+---------+------+-------------------------------------+---------+
|Mailbox |Yes |Yes |urn:ietf:params:jmap:mail |[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|Thread |Yes |Yes |urn:ietf:params:jmap:mail |[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|Email |Yes |Yes |urn:ietf:params:jmap:mail |[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|EmailDelivery |No |Yes |urn:ietf:params:jmap:mail |[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|SearchSnippet |No |No |urn:ietf:params:jmap:mail |[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|Identity |No |Yes |urn:ietf:params:jmap:submission |[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|EmailSubmission |No |Yes |urn:ietf:params:jmap:submission |[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|VacationResponse|No |Yes |urn:ietf:params:jmap:vacationresponse|[RFC8621]|
+----------------+---------+------+-------------------------------------+---------+
|MDN |No |No |urn:ietf:params:jmap:mdn |[RFC9007]|
+----------------+---------+------+-------------------------------------+---------+
Table 1
7. Changes
EDITOR: please remove this section before publication.
The source of this document exists on github at:
https://github.com/brong/draft-gondwana-jmap-blob/
(https://github.com/brong/draft-gondwana-jmap-blob/)
*draft-ieft-jmap-blob-03*:
* added capabilities object
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* renamed types to typeNames and matchedIds
* added details of how to handle non-UTF8 data and truncation in
Blob/get
* added isTruncated and isEncodingProblem to Blob/get to tell the
client if the request wasn't entirely satisfied.
*draft-ieft-jmap-blob-02*:
* fixed incorrect RFC number in reference and HTTP PUT -> POST,
thanks Ken.
* added acknowledgements section
* removed all 'datatype' text and changed to 'data type' or 'type
name' as appropriate (issue #1 proposal)
* expanded security considerations section and moved optional Blob/
lookup empty case into Blob/lookup section
*draft-ieft-jmap-blob-01*:
* renamed 'datatypes' to 'types' to align with PushSubscription from
RFC8620.
* added example for Blob/get
* specified offset and length precisely
*draft-ieft-jmap-blob-00*:
* initial adoption as an IETF document, otherwise identical to
draft-gondwana-jmap-blob-02
*draft-gondwana-jmap-blob-02*
* renamed 'objects' to 'datatypes'
* specified Blob/lookup
* added IANA registry for datatypes
*draft-gondwana-jmap-blob-01*
* added an example
*draft-gondwana-jmap-blob-00*
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* initial proposal
8. Acknowledgements
Alexey Melnikov, Ken Murchison, and the JMAP working group at the
IETF.
9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10. Informative References
[RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals",
RFC 7888, DOI 10.17487/RFC7888, May 2016,
<https://www.rfc-editor.org/info/rfc7888>.
[RFC8621] Jenkins, N. and C. Newman, "The JSON Meta Application
Protocol (JMAP) for Mail", RFC 8621, DOI 10.17487/RFC8621,
August 2019, <https://www.rfc-editor.org/info/rfc8621>.
[RFC8620] Jenkins, N. and C. Newman, "The JSON Meta Application
Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, July
2019, <https://www.rfc-editor.org/info/rfc8620>.
Author's Address
Bron Gondwana (editor)
Fastmail
Level 2, 114 William St
Melbourne VIC 3000
Australia
Email: brong@fastmailteam.com
URI: https://www.fastmail.com
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