]> Transloadit

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next generation unicorn sparkling distributed ledger This document specifies problem types that servers can use in responses to problems encountered while dealing with a request carrying integrity fields and integrity preference fields. About This Document The latest revision of this draft can be found at . Status information for this document may be found at . Source for this draft and an issue tracker can be found at .

Introduction by design does not define, require or recommend any specific behavior for error handling relating to integrity. The responsibility is instead delegated to applications. This draft defines a set of problem types that can be used by server applications to indicate that a problem was encountered while dealing with a request carrying integrity fields and integrity preference fields. For example, a request message may include content alongside Content-Digest and Repr-Digest header fields that use a digest algorithm the server does not support. An application could decide to reject this request because it cannot validate the integrity. Using a problem type, the server can provide machine-readable error details to aid debugging or error reporting, as shown in the following example.

Conventions and Definitions 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 when, and only when, they appear in all capitals, as shown here. The terms "integrity fields" and "integrity preference fields" are from .

Problem Types

Unsupported Hashing Algorithm This section defines the "https://iana.org/assignments/http-problem-types#unsupported-hashing-algorithm" problem type . A server MAY use this problem type when responding to a request, whose integrity or integrity preference fields reference a hashing algorithm that the server can not or does not want to support for this request, and if the server wants to indicate this problem to the sender. For this problem type, the unsupported-algorithm is defined as the only extension member. It SHOULD be populated in a response using this problem type, with its value being the algorithm key of the unsupported algorithm from the request. The response SHOULD include the corresponding integrity preference field to indicate the server's algorithm support and preference. The following example shows a response for a request with an integrity field utilizing an unsupported hashing algorithm foo. The response also includes a list of supported algorithms. This problem type is a hint to the client about algorithm support, which the client could use to retry the request with a different algorithm supported by the server.

Invalid Digest Value This section defines the "https://iana.org/assignments/http-problem-types#invalid-digest-value" problem type . A server MAY use this problem type when responding to a request, whose integrity fields include a digest value, that cannot be generated by the corresponding hashing algorithm. For example, if the digest value of the sha-512 hashing algorithm is not 64 bytes long, it cannot be a valid digest value and the server can skip computing the digest value. This problem type MUST NOT be used if the server is not able to parse the integrity fields according to , for example because of a syntax error in the field value. The server SHOULD include a human-readable description why the value is considered invalid in the title member. The following example shows a response for a request with an invalid digest value. This problem type indicates a fault in the sender's calculation or encoding of the digest value. A retry of the same request without modification will likely not yield a successful response.

Mismatching Digest Value This section defines the "https://iana.org/assignments/http-problem-types#mismatching-digest-value" problem type . A server MAY use this problem type when responding to a request, whose integrity fields include a digest value that does not match the digest value that the server calculated for the request content or representation. Three problem type extension members are defined: the algorithm, provided-digest, and calculated-digest members. A response using this problem type SHOULD populate all members, with the value of algorithm being the algorithm key of the used hashing algorithm, with the value of provided-digest being the digest value taken from the request's integrity fields, and the value of calculated-digest being the calculated digest. The digest values MUST BE serialized as byte sequences as described in . The following example shows a response for a request with a mismatching SHA-256 digest value. If the sender receives this problem type, the request might be modified unintentionally by an intermediary. The sender could use this information to retry the request without modification to address temporary transmission issues.

Security Considerations Although an error appeared while handling the digest fields, the server may choose to not disclose this error to the sender to avoid lacking implementation details. Similar, the server may choose a general problem type for the response even in a more specific problem type is defined if it prefers to hide the details of the error from the sender.

IANA Considerations IANA is asked to register the following entry in the "HTTP Problem Types" registry:

Type URI:

https://iana.org/assignments/http-problem-types#unsupported-hashing-algorithm

Title:

Unsupported Hashing Algorithm

Recommended HTTP status code:

400

Reference:

This document

IANA is asked to register the following entry in the "HTTP Problem Types" registry:

Type URI:

https://iana.org/assignments/http-problem-types#invalid-digest-value

Title:

Invalid Digest Value

Recommended HTTP status code:

400

Reference:

This document

IANA is asked to register the following entry in the "HTTP Problem Types" registry:

Type URI:

https://iana.org/assignments/http-problem-types#mismatching-digest-value

Title:

Mismatching Digest Value

Recommended HTTP status code:

400

Reference:

This document

Normative References This document defines HTTP fields that support integrity digests. The Content-Digest field can be used for the integrity of HTTP message content. The Repr-Digest field can be used for the integrity of HTTP representations. Want-Content-Digest and Want-Repr-Digest can be used to indicate a sender's interest and preferences for receiving the respective Integrity fields. This document obsoletes RFC 3230 and the Digest and Want-Digest HTTP fields. This document defines a "problem detail" to carry machine-readable details of errors in HTTP response content to avoid the need to define new error response formats for HTTP APIs. This document obsoletes RFC 7807. This document describes a set of data types and associated algorithms that are intended to make it easier and safer to define and handle HTTP header and trailer fields, known as "Structured Fields", "Structured Headers", or "Structured Trailers". It is intended for use by specifications of new HTTP fields that wish to use a common syntax that is more restrictive than traditional HTTP field values. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.

Acknowledgments This document is based on ideas from a discussion with Roberto Polli, so thanks to him for his valuable input and feedback on this topic.