JMAP B. Gondwana, Ed. Internet-Draft Fastmail Updates: 8620 (if approved) 4 January 2023 Intended status: Standards Track Expires: 8 July 2023 JMAP Blob management extension draft-ietf-jmap-blob-18 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- Drafts is at https://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 8 July 2023. Copyright Notice Copyright (c) 2023 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 Gondwana Expires 8 July 2023 [Page 1] Internet-Draft JMAP Blob January 2023 and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised 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 3.1.1. Capability Example . . . . . . . . . . . . . . . . . 4 4. Blob Methods . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Blob/upload . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.1. Blob/upload simple example . . . . . . . . . . . . . 8 4.1.2. Blob/upload complex example . . . . . . . . . . . . . 9 4.2. Blob/get . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2.1. Blob/get simple example . . . . . . . . . . . . . . . 13 4.2.2. Blob/get example with range and encoding errors . . . 15 4.3. Blob/lookup . . . . . . . . . . . . . . . . . . . . . . . 20 4.3.1. Blob/lookup example . . . . . . . . . . . . . . . . . 21 5. Security considerations . . . . . . . . . . . . . . . . . . . 23 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 23 6.1. JMAP Capability registration for "blob" . . . . . . . . . 23 6.2. JMAP Error Codes Registration for "unknownDataType" . . . 24 6.3. Creation of "JMAP Data Types" Registry . . . . . . . . . 24 7. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 9. Normative References . . . . . . . . . . . . . . . . . . . . 29 10. Informative References . . . . . . . . . . . . . . . . . . . 29 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 30 1. Introduction Sometimes JMAP ([RFC8620]) interactions require creating a blob and then referencing it. In the same way that IMAP Literals were extended by [RFC7888], embedding small blobs directly into the JMAP method calls array can be an option for reducing roundtrips. Likewise, when fetching an object, it can be useful to also fetch the raw content of that object without a separate roundtrip. Since raw blobs may contain arbitrary binary data, this document defines a use of the base64 coding specified in [RFC4648] for both creating and fetching blob data. Gondwana Expires 8 July 2023 [Page 2] Internet-Draft JMAP Blob January 2023 Where JMAP is being proxied through a system which applies additional access restrictions, it can be useful to know which objects reference any particular blob, and this document defines a way to discover those references. 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. The definitions of JSON keys and datatypes in the document follow the conventions described in the core JMAP specification [RFC8620]. 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 The capability urn:ietf:params:jmap:blob being present in the "accountCapabilities" property of an account represents support for additional API methods on the Blob datatype. Servers that include the capability in one or more "accountCapabilities" properties MUST also include the property in the "capabilities" property. The value of this property in the JMAP session "capabilities" property MUST be an empty object. The value of this property in an account's "accountCapabilities" property is an object that MUST contain the following information on server capabilities and permissions for that account: * maxSizeBlobSet: UnsignedInt|null This is the maximum size of blob (in octets) that the server will allow to be created (including blobs created by concatenating multiple data sources together). Clients MUST NOT attempt to create blobs larger than this size. Gondwana Expires 8 July 2023 [Page 3] Internet-Draft JMAP Blob January 2023 If this value is null, then clients are not required to limit the size of blob they try to create, though servers can always reject creation of blobs regardless of size; e.g. due to lack of disk space, or per-user rate limits. * maxDataSources: UnsignedInt The maximum number of DataSourceObjects allowed per creation in a Blob/upload. Servers MUST allow at least 64 DataSourceObjects per creation. * supportedTypeNames: String[] An array of data type names that are supported for Blob/lookup. If the server does not support lookups then this will be the empty list. NOTE, the supportedTypeNames list may include private types which are not in the JMAP Types Registry defined by this document. Clients MUST ignore type names they do not recognise. * supportedDigestAlgorithms: String[] An array of supported digest algorithms that are supported for Blob/get. If the server does not support calculating blob digests, then this will be the empty list. Algorithms in this list MUST be present in the HTTP Digest Algorithms registry defined by [RFC3230], and are always lowercased. Clients SHOULD prefer algorithms listed earlier in this list. 3.1.1. Capability Example Gondwana Expires 8 July 2023 [Page 4] Internet-Draft JMAP Blob January 2023 { "capabilities": { ..., "urn:ietf:params:jmap:blob": {} }, "accounts": { "A13842": { ... "accountCapabilities": { "urn:ietf:params:jmap:blob": { "maxSizeBlobSet": 50000000, "maxDataSources": 100, "supportedTypeNames" : [ "Mailbox", "Thread", "Email" ], "supportedDigestAlgorithms" : [ "sha", "sha-256" ] } } } } } 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 specification, 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/upload This is similar to a Foo/set from [RFC8620] in some ways, however blobs can not be updated or deleted, so only create is allowed in the method call, and blobs do not have state, so there is no state field present in the method response. *Parameters* * accountId: Id Gondwana Expires 8 July 2023 [Page 5] Internet-Draft JMAP Blob January 2023 The id of the account in which the blobs will be created. * create: Id[UploadObject] A map of creation id to UploadObjects. *Result* The result is the same as for Foo/set in RFC8620, with created and notCreated objects mapping from the creationId. The created objects contain: * id: Id the blobId which was created * type: String|null the media type as given in the creation (if any); or detected from content by the server; or null * size: UnsignedInt as per RFC8620 - the size of the created blob in octets It will also contain any other properties identical to those that would be returned in the JSON response of the RFC8620 upload endpoint (which may be extended in the future - this document anticipates that implementations will extend both the upload endpoint and the Blob/ upload responses in the same way) Or if there is a problem with a creation, then the server will return a notCreated response with a map from the failed creationId to a SetError object. For each successful upload, servers MUST add an entry to the creationIds map for the request. This allows the blob id to be used via back-reference in subsequent method calls. The created blob will have the same lifetime and same expiry semantics as any other binary object created via the mechanism specified in [!@RFC8620] section 6. Uploads using with this mechanism will be restricted by the maxUploadSize limit for JMAP requests specified by the server, and clients SHOULD consider using the upload mechanism defined by [!@RFC8620] for blobs larger than a megabyte. Gondwana Expires 8 July 2023 [Page 6] Internet-Draft JMAP Blob January 2023 *UploadObject* * data: DataSourceObject[] an array of zero or more octet sources in order (zero to create an empty blob). The result of each of these sources is concatenated together in order to create the blob. * type: String|null (default: null) hint for media type of the data *DataSourceObject* Exactly one of: * data:asText: String|null (raw octets, must be UTF-8) * data:asBase64: String|null (base64 representation of octets) or a blobId source: * blobId: Id * offset: UnsignedInt|null (MAY be zero) * length: UnsignedInt|null (MAY 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. begins or extends past the end of the data in the blob) then the DataSourceObject is invalid and results in a notCreated response for this creation id. If the data 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 characters in the base64 of data:asBase64, or invalid UTF-8 in data:asText MUST result in a nonCreated response. It is envisaged that the definition for DataSourceObject might be extended in the future, for example to fetch external content. Gondwana Expires 8 July 2023 [Page 7] Internet-Draft JMAP Blob January 2023 A server MUST accept at least 64 DataSourceObjects per create, as described in Section 3.1 of this document. 4.1.1. Blob/upload simple example The data:asBase64 field is set over multiple lines for ease of publication here, however all data:asBase64 would be sent as a continuous string with no whitespace on the wire. Method Call: [ "Blob/upload", { "accountId": "account1", "create": { "1": { "data" : [ { "data:asBase64": "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKA AAAA1BMVEX/AAAZ4gk3AAAAAXRSTlN/gFy0ywAAAApJRE FUeJxjYgAAAAYAAzY3fKgAAAAASUVORK5CYII=", } ], "type": "image/png" }, }, }, "R1" ] Response: [ "Blob/upload", { "accountId" : "account1", "created" : { "1": { "id" : "G4c6751edf9dd6903ff54b792e432fba781271beb", "type" : "image/png", "size" : 95 }, }, }, "R1" ] Gondwana Expires 8 July 2023 [Page 8] Internet-Draft JMAP Blob January 2023 4.1.2. Blob/upload complex example Method Calls: [ [ "Blob/upload", { "create": { "b4": { "data": [ { "data:asText": "The quick brown fox jumped over the lazy dog." } ] } } }, "S4" ], [ "Blob/upload", { "create": { "cat": { "data": [ { "data:asText": "How" }, { "blobId": "#b4", "length": 7, "offset": 3 }, { "data:asText": "was t" }, { "blobId": "#b4", "length": 1, "offset": 1 }, { "data:asBase64": "YXQ/" } ] } } Gondwana Expires 8 July 2023 [Page 9] Internet-Draft JMAP Blob January 2023 }, "CAT" ], [ "Blob/get", { "properties": [ "data:asText", "size" ], "ids": [ "#cat" ] }, "G4" ] ] Responses: [ [ "Blob/upload", { "oldState": null, "created": { "b4": { "id": "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e", "size": 45, "type": "application/octet-stream" } }, "notCreated": null, "accountId": "account1" }, "S4" ], [ "Blob/upload", { "oldState": null, "created": { "cat": { "id": "Gcc60576f036321ae6e8037ffc56bdee589bd3e23", "size": 19, "type": "application/octet-stream" } }, Gondwana Expires 8 July 2023 [Page 10] Internet-Draft JMAP Blob January 2023 "notCreated": null, "accountId": "account1" }, "CAT" ], [ "Blob/get", { "list": [ { "id": "Gcc60576f036321ae6e8037ffc56bdee589bd3e23", "data:asText": "How quick was that?", "size": 19 } ], "notFound": [], "accountId": "account1" }, "G4" ] ] 4.2. Blob/get A standard JMAP get, with two additional optional parameters: * offset: UnsignedInt|null start this many octets into the blob data. If null or unspecified, this defaults to zero. * length: UnsignedInt|null return at most this many octets of the blob data. If null or unspecified, then all remaining octets in the blob are returned. This can be considered equivalent to an infinitely large length value, except that the isTruncated warning is not given unless the start offset is past the end of the blob. *Request Properties:* Any of * data:asText * data:asBase64 * data (returns data:asText if the selected octets are valid UTF-8, or data:asBase64) Gondwana Expires 8 July 2023 [Page 11] Internet-Draft JMAP Blob January 2023 * digest: (where is one of the named algorithms in the supportedDigestAlgorithms capability) * 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 octets in the selected range * digest: String the base64 encoding of the digest of the octets in the selected range, calculated using the named algorithm * isEncodingProblem: Boolean (default: false) * isTruncated: Boolean (default: false) * size: UnsignedInt the number of octets in the entire blob The size value MUST always be the number of octets in the underlying blob, regardless of offset and length. 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 or data:asText was requested, then the key isEncodingProblem MUST be set to true and the data:asText response value MUST be null. In the case where data was requested and the data is not valid UTF-8, then data:asBase64 MUST be returned. Gondwana Expires 8 July 2023 [Page 12] Internet-Draft JMAP Blob January 2023 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 MUST be set to true to tell the client that the requested range could not be fully satisfied. If digest was requested, any digest is calculated on the octets that would be returned for a data field. Servers SHOULD store the size for blobs in a format which is efficient to read, and clients SHOULD limit their request to just the size parameter if that is all they need, as fetching blob content could be significantly more expensive and slower for the server. 4.2.1. Blob/get simple example Where a blob containing the string "The quick brown fox jumped over the lazy dog." has blobId Gc0854fb9fb03c41cce3802cb0d220529e6eef94e. The first method call requests just the size for multiple blobs, and the second requests both size and a short range of the data for one of the blobs. Method Calls: [ [ "Blob/get", { "accountId" : "account1", "ids" : [ "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e", "not-a-blob" ], "properties" : [ "data:asText", "digest:sha", "size" ] }, "R1" ], [ "Blob/get", { "accountId" : "account1", "ids" : [ "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e" Gondwana Expires 8 July 2023 [Page 13] Internet-Draft JMAP Blob January 2023 ], "properties" : [ "data:asText", "digest:sha", "digest:sha-256", "size" ], "offset" : 4, "length" : 9 }, "R2" ] ] Responses: [ [ "Blob/get", { "accountId": "account1", "list": [ { "id": "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e", "data:asText": "The quick brown fox jumped over the lazy dog.", "digest:sha": "wIVPufsDxBzOOALLDSIFKebu+U4=", "size": 45 } ], "notFound": [ "not-a-blob" ] }, "R1" ], [ "Blob/get", { "accountId": "account1", "list": [ { "id": "Gc0854fb9fb03c41cce3802cb0d220529e6eef94e", "data:asText": "quick bro", "digest:sha": "QiRAPtfyX8K6tm1iOAtZ87Xj3Ww=", "digest:sha-256": "gdg9INW7lwHK6OQ9u0dwDz2ZY/gubi0En0xlFpKt0OA=", "size": 45 } ] Gondwana Expires 8 July 2023 [Page 14] Internet-Draft JMAP Blob January 2023 }, "R2" ] ] 4.2.2. Blob/get example with range and encoding errors The b1 value is the text: "The quick brown fox jumped over the \x81\x81 fox" which contains an invalid utf8 sequence. The results have the following interesting properties: * G1: defaults to data and size - so b1 returns isEncodingProblem and a base64 value. * G2: since data:asText was explicitly selected, does not attempt to return a value for the data, just isEncodingProblem for b1. * G3: since only data:asBase64 was requested, there is no encoding problem and both values are returned. * G4: since the requested range could be satisfied as text, both blobs are returned as data:asText and there is no encoding problem. * G5: both blobs cannot satisfy the requested range, so isTruncated is true for both. Note: some values have been wrapped for line length - there would be no whitespace in the data:asBase64 values on the wire Method calls: [ [ "Blob/upload", { "create": { "b1": { "data": [ { "data:asBase64": "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZW Qgb3ZlciB0aGUggYEgZG9nLg==" } ] }, "b2": { "data": [ Gondwana Expires 8 July 2023 [Page 15] Internet-Draft JMAP Blob January 2023 { "data:asText": "hello world" } ], "type" : "text/plain" } } }, "S1" ], [ "Blob/get", { "ids": [ "#b1", "#b2" ] }, "G1" ], [ "Blob/get", { "ids": [ "#b1", "#b2" ], "properties": [ "data:asText", "size" ] }, "G2" ], [ "Blob/get", { "ids": [ "#b1", "#b2" ], "properties": [ "data:asBase64", "size" ] }, "G3" ], Gondwana Expires 8 July 2023 [Page 16] Internet-Draft JMAP Blob January 2023 [ "Blob/get", { "offset": 0, "length": 5, "ids": [ "#b1", "#b2" ] }, "G4" ], [ "Blob/get", { "offset": 20, "length": 100, "ids": [ "#b1", "#b2" ] }, "G5" ] ] Responses: [ [ "Blob/upload", { "oldState": null, "created": { "b2": { "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed", "size": 11, "type": "application/octet-stream" }, "b1": { "id": "G72cfa4804194563685d9a4b695f7ba20e7739576", "size": 43, "type": "text/plain" } }, "updated": null, "destroyed": null, "notCreated": null, Gondwana Expires 8 July 2023 [Page 17] Internet-Draft JMAP Blob January 2023 "notUpdated": null, "notDestroyed": null, "accountId": "account1" }, "S1" ], [ "Blob/get", { "list": [ { "id": "G72cfa4804194563685d9a4b695f7ba20e7739576", "isEncodingProblem": true, "data:asBase64": "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZW Qgb3ZlciB0aGUggYEgZG9nLg==", "size": 43 }, { "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed", "data:asText": "hello world", "size": 11 } ], "notFound": [], "accountId": "account1" }, "G1" ], [ "Blob/get", { "list": [ { "id": "G72cfa4804194563685d9a4b695f7ba20e7739576", "isEncodingProblem": true, "size": 43 }, { "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed", "data:asText": "hello world", "size": 11 } ], "notFound": [], "accountId": "account1" }, "G2" ], Gondwana Expires 8 July 2023 [Page 18] Internet-Draft JMAP Blob January 2023 [ "Blob/get", { "list": [ { "id": "G72cfa4804194563685d9a4b695f7ba20e7739576", "data:asBase64": "VGhlIHF1aWNrIGJyb3duIGZveCBqdW1wZW Qgb3ZlciB0aGUggYEgZG9nLg==", "size": 43 }, { "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed", "data:asBase64": "aGVsbG8gd29ybGQ=", "size": 11 } ], "notFound": [], "accountId": "account1" }, "G3" ], [ "Blob/get", { "list": [ { "id": "G72cfa4804194563685d9a4b695f7ba20e7739576", "data:asText": "The q", "size": 43 }, { "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed", "data:asText": "hello", "size": 11 } ], "notFound": [], "accountId": "account1" }, "G4" ], [ "Blob/get", { "list": [ { "id": "G72cfa4804194563685d9a4b695f7ba20e7739576", "isTruncated": true, Gondwana Expires 8 July 2023 [Page 19] Internet-Draft JMAP Blob January 2023 "isEncodingProblem": true, "data:asBase64": "anVtcGVkIG92ZXIgdGhlIIGBIGRvZy4=", "size": 43 }, { "id": "G2aae6c35c94fcfb415dbe95f408b9ce91ee846ed", "isTruncated": true, "data:asText": "", "size": 11 } ], "notFound": [], "accountId": "account1" }, "G5" ] ] 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. Since different datatypes will have different semantics of "contains", the definition of reference is somewhat loosely defined, but roughly means "you could discover this blobId by looking at this object or at other objects recursively contained within this object". For example with an [RFC8621] server, if checking whether a Mailbox references a blob, then if any Emails within that Mailbox reference the blobId, then the Mailbox references that blobId. For any Thread which references an Email that references a blobId, it can be said that the Thread references the blobId. But this does not mean that if an Email references a Mailbox in its mailboxIds property, then any blobId referenced by other Emails in that Mailbox are also referenced by the initial Email. *Parameters* * accountId: Id The id of the account used for the call. * typeNames: String[] Gondwana Expires 8 July 2023 [Page 20] Internet-Draft JMAP Blob January 2023 A list of names from the "JMAP Data Types" registry, or defined by private extensions which the client has requested. 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. * matchedIds: String[Id[]] A map from type name to list of Ids of that data type (e.g. the name "Email" maps to a list of emailIds) If a blob is not visible to a user, or does not exist on the server at all, then the server MUST still return an empty array for each type as this doesn't leak any information about whether the blob is on the server but not visible to the requesting user. 4.3.1. Blob/lookup example Gondwana Expires 8 July 2023 [Page 21] Internet-Draft JMAP Blob January 2023 Method call: [ "Blob/lookup", { "typeNames": [ "Mailbox", "Thread", "Email" ], "ids": [ "Gd2f81008cf07d2425418f7f02a3ca63a8bc82003", "not-a-blob" ] }, "R1" ] Response: [ "Blob/lookup", { "list": [ { "id": "Gd2f81008cf07d2425418f7f02a3ca63a8bc82003", "matchedIds": { "Mailbox": [ "M54e97373", "Mcbe6b662" ], "Thread": [ "T1530616e" ], "Email": [ "E16e70a73eb4", "E84b0930cf16" ] } } ], "notFound": [ "not-a-blob" ] }, "R1" ] Gondwana Expires 8 July 2023 [Page 22] Internet-Draft JMAP Blob January 2023 5. Security considerations All security considerations of JMAP [RFC8620] apply to this specification. Additional considerations specific to the data types and functionality introduced by this document are described here. 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 only return a null value if data:asText is requested for a range of octets which is not valid UTF-8, and set isEncodingProblem: true. 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 not 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. The server MUST NOT trust that the data given to a Blob/upload 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. Blob/upload with carefully chosen data sources can be used to recreate dangerous content on the far side of security scanners (anti-virus or exfiltration scanners for example) which may be watching the upload endpoint. Server implementations SHOULD provide a hook to allow security scanners to check the resulting blob after concatenating the data sources in the same way that they do for the upload endpoint. Digest algorithms can be expensive for servers to calculate. Servers which share resources between multiple users should track resource usage by clients, and rate-limit expensive operations to avoid resource starvation. 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 Gondwana Expires 8 July 2023 [Page 23] Internet-Draft JMAP Blob January 2023 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. 6.3. Creation of "JMAP Data Types" Registry IANA is requested to create a new registry "JMAP Data Types" with the initial content: Gondwana Expires 8 July 2023 [Page 24] Internet-Draft JMAP Blob January 2023 +================+=========+======+=====================================+=========+ |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 This policy for this registry is "Specification required", either an RFC or a similarly stable reference document which defines a JMAP Data Type and associated capability. IANA is asked to appoint designated experts to review requests for additions to this registry, with guidance to allow any registration which provides a stable document describing the capability, and control over the URI namespace where the capability URI points. 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/) Gondwana Expires 8 July 2023 [Page 25] Internet-Draft JMAP Blob January 2023 *draft-ietf-jmap-blob-18* * add security considerations for Digest algorithm performance (was supposed to be in -13 but I had a commit that never got pushed) * artart review: - clarify that created blobs behave identically to RFC8620 section 6 binary objects. - clearer text about "references a blob" - remove contractions * Roman Danyliw DISCUSS - corrected example text - missing comma and extra data:asBase64. - simplify Blob/lookup to not have multiple ways of saying "not found" for a blob and then need a security considerations around it. - said that clients SHOULD prefer algorithms earlier in the list. - clarified that supportedTypeNames could include private extensions. - editorial/spelling fixes * genart review - editorial/spelling fixes * Robert Winton review - added a suggestion to use the regular upload mechanism for blobs over a megabyte in size. *draft-ietf-jmap-blob-17* * AD review, one more wording nit *draft-ietf-jmap-blob-16* * secdir last-call review changes - nit fixes and security considerations *draft-ietf-jmap-blob-15* * changed capabilities object to MUST contain all specified keys, to align with all other published JMAP extensions. *draft-ietf-jmap-blob-14* * AD review - fixed MUST usage * AD review - added instructions regarding expert review for IANA *draft-ietf-jmap-blob-13* * added examples of digest responses *draft-ietf-jmap-blob-12* Gondwana Expires 8 July 2023 [Page 26] Internet-Draft JMAP Blob January 2023 * updates based on Neil Jenkins' feedback: - fixed [] positions for type specs - documented delta between /upload and /set better - allowed zero-length blobId sources - fixed examples with /set leftovers - documented datatypes registry policy * added optional "digest" support *draft-ietf-jmap-blob-11*: * updates based on IETF113 feedback: - added wording to suggest the a Blob/get of just size might be faster - added an example with just the size field being selected *draft-ietf-jmap-blob-10*: * removed remaining references to catenate. *draft-ietf-jmap-blob-09*: * tidied up introduction text * replaced Blob/set with Blob/upload * made all upload creates take an array of sources to normalise behaviour at the cost of a slightly more complex default case. *draft-ietf-jmap-blob-08*: * Fixed spelling of Neil's name in acknowledgements * Last call review (thanks Jim Fenton) - fixed mmark sillyness causing RFC8620 to be non-normative in the references - clarified the capability object and accountCapability object requirements - made capability keys much more tightly defined, with mandatory minimum catenate limit and default values. - increased use of normative language generally - lowercased 'blob' anywhere it wasn't explicitly the object - lowercased titles of the columns in the registry *draft-ietf-jmap-blob-07*: * more examples to cover the interactions of offset, length and encoding checks. *draft-ietf-jmap-blob-06*: * removed asHex - we only need base64 and text Gondwana Expires 8 July 2023 [Page 27] Internet-Draft JMAP Blob January 2023 * added reference to where base64 is defined * made 'destroy' not be allowed * expanded JSON examples for readability * removed 'expires' from examples *draft-ietf-jmap-blob-05*: * discovered I hadn't actually included typeNames and matchedIds anywhere except the updates section, oops! * added a catenate example * tightened up some text *draft-ieft-jmap-blob-04*: * added security considerations for scanning catenate results *draft-ieft-jmap-blob-03*: * added capabilities object * 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* Gondwana Expires 8 July 2023 [Page 28] Internet-Draft JMAP Blob January 2023 * 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* * initial proposal 8. Acknowledgements Joris Baum, Jim Fenton, Neil Jenkins, Alexey Melnikov, Ken Murchison, Robert Stepanek and the JMAP working group at the IETF. 9. Normative References [RFC2119] Bradner, S. and RFC Publisher, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3230] Mogul, J., Van Hoff, A., and RFC Publisher, "Instance Digests in HTTP", RFC 3230, DOI 10.17487/RFC3230, January 2002, . [RFC4648] Josefsson, S. and RFC Publisher, "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, . [RFC8174] Leiba, B. and RFC Publisher, "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8620] Jenkins, N., Newman, C., and RFC Publisher, "The JSON Meta Application Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, July 2019, . 10. Informative References [RFC7888] Melnikov, A., Ed. and RFC Publisher, "IMAP4 Non- synchronizing Literals", RFC 7888, DOI 10.17487/RFC7888, May 2016, . Gondwana Expires 8 July 2023 [Page 29] Internet-Draft JMAP Blob January 2023 [RFC8621] Jenkins, N., Newman, C., and RFC Publisher, "The JSON Meta Application Protocol (JMAP) for Mail", RFC 8621, DOI 10.17487/RFC8621, August 2019, . 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 Gondwana Expires 8 July 2023 [Page 30]