Crate idm_frame 

IDM Frame Utilities

ITU-T Recommendation X.519 (2019) defines a protocol, Internet Directly-Mapped (IDM) Protocol, which is used to provide the OSI ROSE service and all lower layers of the OSI networking stack over TCP/IP, specifically for the purpose of making the X.500 directory easily available over the Internet.

There are two versions of the IDM protocol defined. This crate supports both. The second version supports negotiation of the transfer syntax, whereas the first uses the Basic Encoding Rules (BER).

This crate does not handle decoding of the contained IDM-PDU ASN.1 data structure: it only handles the frames.

This crate

This crate is no_std and does not require alloc, except for running the tests. This crate was not written in any part by AI or LLMs. This crate was fuzz-tested. It has no dependencies. Extremely simple and light-weight.

Usage

To read an IDM frame, simply create an IdmFrameIter, and iterate over it one or more times.

let buffer: Vec<u8> = Vec::from([
    1, 1, 0, 0, 0, 5, 1, 2, 3, 4, 5,
].as_slice());
let mut frames = IdmFrameIter::new(buffer.as_slice());
let frame = frames.next()
  .expect("uh oh, no frame")
  .expect("uh oh, unrecognized / unsupported version");
assert_eq!(frame.version, 1);
assert_eq!(frame.final_, 1);
assert_eq!(frame.encoding, 0);
assert_eq!(frame.data, [1,2,3,4,5].as_slice());

This crate also provides two fairly trivial functions for helping you write valid IDM frames: write_idm_v1_frame_header and write_idm_v2_frame_header. These can be used like so:

let mut buf: [u8; IDMV2_FRAME_SIZE] = [0, 0, 0, 0, 0, 0, 0, 0];
write_idm_v2_frame_header(&mut buf, true, IDM_ENCODING_XER, 1024);
assert_eq!(buf, [2, 1, 0x10, 0, 0, 0, 4, 0]);

Cheers!

Structs

IdmFrame

An IDM Frame

IdmFrameIter

Iterator that reads IDM frames from a buffer, such as a buffer of bytes read in from a TCP socket.

Enums

IdmError

An error pertaining to IDM frame decoding

Constants

IDMV1_FRAME_SIZE

Size of a Version 1 IDM Frame

IDMV2_FRAME_SIZE

Size of a Version 2 IDM Frame

IDM_ENCODING_DER

Distinguished Encoding Rules (DER) as described in ITU-T Recommendation X.690.

IDM_ENCODING_PER_ALIGNED

Basic Aligned variant of Packed Encoding Rules (PER) as described in ITU-T Recommendation X.691.

IDM_ENCODING_PER_UNALIGNED

Basic Unaligned variant of Packed Encoding Rules (PER) as described in ITU-T Recommendation X.691.

IDM_ENCODING_XER

XML Encoding Rules (XER) as described in ITU-T Recommendation X.693.

IDM_FINAL

A final frame relaying the last bytes of a complete IDM-PDU

IDM_NOT_FINAL

Not a final frame relaying the last bytes of a complete IDM-PDU

IDM_VERSION_1

IDM Protocol Version 1

IDM_VERSION_2

IDM Protocol Version 2

MIN_FRAME_SIZE

Absolute smallest valid IDM frame

Functions

write_idm_v1_frame_header

Write an IDM version 1 frame header to header

write_idm_v2_frame_header

Write an IDM version 2 frame header to header

Type Aliases

EncodingMask

Mask for the encoding field of a version 2 IDM frame.

IDMFinality

Values of the IDM final field

IDMVersion

Values of the IDM version field