CoRE C. Amsüss Internet-Draft 4 February 2023 Intended status: Informational Expires: 8 August 2023 Concise Problem Details: Body Error Position draft-amsuess-core-pd-body-error-position-00 Abstract This defines a single standard problem detail for use with the Concise Problem Details format: Request Body Error Position. Using this detail, the server can point at the position inside the client's request body that induced the error. Discussion Venues This note is to be removed before publishing as an RFC. Discussion of this document takes place on the Constrained RESTful Environments Working Group mailing list (core@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/core/. Source for this draft and an issue tracker can be found at https://gitlab.com/chrysn/problem-detail-body-error-position. 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 August 2023. Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. Amsüss Expires 8 August 2023 [Page 1] Internet-Draft Concise Problem Details: Body Error Posi February 2023 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 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 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Document lifecycle . . . . . . . . . . . . . . . . . . . 2 2. Request Body Error Position . . . . . . . . . . . . . . . . . 3 3. Usage example . . . . . . . . . . . . . . . . . . . . . . . . 3 4. IANA considerations . . . . . . . . . . . . . . . . . . . . . 4 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Normative References . . . . . . . . . . . . . . . . . . 4 5.2. Informative References . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction Concise Problem Details for CoAP APIs [RFC9290] describes how a server can provide details about an error processing a client request, and how to extend these error messages. This document uses that extension mechanism and adds the Request Body Error Position detail. 1.1. Terminology The description of the problem detail uses the term "body" as defined in [RFC7959]. 1.2. Document lifecycle Registering a standard problem detail merely requires a specification, not an RFC (let alone of a particular track). It is the author's opinion that an Interned Draft can provide sufficient specification, and is more suitable than an informal note published at some arbitrary website due to its archival through the draft submission process. It is not expected that this draft will proceed all the way to an RFC; instead, once sufficiently mature, it will be used as a reference in a request to IANA, and updated with the assigned number. Amsüss Expires 8 August 2023 [Page 2] Internet-Draft Concise Problem Details: Body Error Posi February 2023 This document will eventually expire as an Internet Draft, but nonetheless be usable as the permanent reference for the assigned problem detail. 2. Request Body Error Position The Request Body Error Position problem detail indicates that the error described by the Concise Problem Details response resulted from processing the request body. The numeric value indicates a byte position inside that body that corresponds to the error. The precise error position for invalid data may vary by implementation -- for example, if a numeric value inside a CBOR ([STD94]) item exceeds the expected range, it may indicate the number's initial byte (typically if the implementation doesn't even implement the indicated argument size) or the argument (if it implements it). When the request's content format indicated a non-identity content coding, the offset points into the uncompressed body. Consequently, this error detail is not suitable for pointing out errors that occur during uncompressing. The main envisioned use of this option is for the client to highlight or back-annotate (eg. to counteract minification, or to display it on some diagnostic notation) the erroneous item in the request body for a human author. 3. Usage example The figures in this section illustrate a CoAP [RFC7252] message exchange using CBOR [STD94] bodies, and a hypothetical CoAP tool's output that utilizes this error detail. Req: FETCH coap://example.com/alpha/archive Content-Format: 60 (application/cbor) Payload: A2071A000123A0182C192118 Payload (diagnostic notation): {7: 74656, 44: 8472} Res: 4.00 Bad Request Content-Format: 257 (application/concise-problem-details+cbor) Payload: A22071556E6B6E6F776E207175657279206B6579381808 Payload (diagnostic notation): { / title / -1: "Unknown query key", / request-body-error-position / -25: 8 } Amsüss Expires 8 August 2023 [Page 3] Internet-Draft Concise Problem Details: Body Error Posi February 2023 Figure 1: Messages exchanged between client and server $ coap post coap://example.com/alpha/archive cbor '{7: 74656, 44: 8472}' Error: Bad Request: Unknown query key {7: 74656, 44: 8472} ^^ The server indicated that the error occurred here. Figure 2: Output of a hypothetical CoAP client that utilizes the Request Body Error Position detail 4. IANA considerations A new entry is requested for the "Standard Problem Detail Keys" subregistry of the "Constrained RESTful Environments (CoRE) Parameters" registry. Key value: The value -25 is suggested Name: request-body-error-position CDDL type: uint Brief description: Byte index inside the request body at which the error became apparent Reference: This document Change controller: IETF CoRE working group 5. References 5.1. Normative References [RFC9290] Fossati, T. and C. Bormann, "Concise Problem Details for Constrained Application Protocol (CoAP) APIs", RFC 9290, DOI 10.17487/RFC9290, October 2022, . [RFC7959] Bormann, C. and Z. Shelby, Ed., "Block-Wise Transfers in the Constrained Application Protocol (CoAP)", RFC 7959, DOI 10.17487/RFC7959, August 2016, . 5.2. Informative References [STD94] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", STD 94, RFC 8949, December 2020. Amsüss Expires 8 August 2023 [Page 4] Internet-Draft Concise Problem Details: Body Error Posi February 2023 [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, June 2014, . Author's Address Christian Amsüss Austria Email: christian@amsuess.com Amsüss Expires 8 August 2023 [Page 5]